EP3390309A1 - Traitement à la vapeur d'eau d'une poudre de dioxyde de silicium lors de la fabrication de verre de silice - Google Patents

Traitement à la vapeur d'eau d'une poudre de dioxyde de silicium lors de la fabrication de verre de silice

Info

Publication number
EP3390309A1
EP3390309A1 EP16822951.6A EP16822951A EP3390309A1 EP 3390309 A1 EP3390309 A1 EP 3390309A1 EP 16822951 A EP16822951 A EP 16822951A EP 3390309 A1 EP3390309 A1 EP 3390309A1
Authority
EP
European Patent Office
Prior art keywords
range
less
silica
quartz glass
content
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP16822951.6A
Other languages
German (de)
English (en)
Inventor
Matthias OTTER
Walter Lehmann
Michael HÜNERMANN
Nils Christian NIELSEN
Nigel Robert WHIPPEY
Boris Gromann
Abdoul-Gafar KPEBANE
Thomas Kayser
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Heraeus Quarzglas GmbH and Co KG
Original Assignee
Heraeus Quarzglas GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Heraeus Quarzglas GmbH and Co KG filed Critical Heraeus Quarzglas GmbH and Co KG
Publication of EP3390309A1 publication Critical patent/EP3390309A1/fr
Withdrawn legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B20/00—Processes specially adapted for the production of quartz or fused silica articles, not otherwise provided for
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01B—NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C
    • C01B33/00—Silicon; Compounds thereof
    • C01B33/113—Silicon oxides; Hydrates thereof
    • C01B33/12—Silica; Hydrates thereof, e.g. lepidoic silicic acid
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B17/00—Forming molten glass by flowing-out, pushing-out, extruding or drawing downwardly or laterally from forming slits or by overflowing over lips
    • C03B17/04—Forming tubes or rods by drawing from stationary or rotating tools or from forming nozzles
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/06—Other methods of shaping glass by sintering, e.g. by cold isostatic pressing of powders and subsequent sintering, by hot pressing of powders, by sintering slurries or dispersions not undergoing a liquid phase reaction
    • C03B19/066—Other methods of shaping glass by sintering, e.g. by cold isostatic pressing of powders and subsequent sintering, by hot pressing of powders, by sintering slurries or dispersions not undergoing a liquid phase reaction for the production of quartz or fused silica articles
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/10—Forming beads
    • C03B19/1005—Forming solid beads
    • C03B19/106—Forming solid beads by chemical vapour deposition; by liquid phase reaction
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/10—Forming beads
    • C03B19/108—Forming porous, sintered or foamed beads
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B19/00—Other methods of shaping glass
    • C03B19/10—Forming beads
    • C03B19/1095—Thermal after-treatment of beads, e.g. tempering, crystallisation, annealing
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/01205—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments
    • C03B37/01211—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube
    • C03B37/01222—Manufacture of preforms for drawing fibres or filaments starting from tubes, rods, fibres or filaments by inserting one or more rods or tubes into a tube for making preforms of multiple core optical fibres
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/02—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor
    • C03B37/025—Manufacture of glass fibres or filaments by drawing or extruding, e.g. direct drawing of molten glass from nozzles; Cooling fins therefor from reheated softened tubes, rods, fibres or filaments, e.g. drawing fibres from preforms
    • C03B37/027—Fibres composed of different sorts of glass, e.g. glass optical fibres
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C13/00—Fibre or filament compositions
    • C03C13/04—Fibre optics, e.g. core and clad fibre compositions
    • C03C13/045—Silica-containing oxide glass compositions
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/06—Glass compositions containing silica with more than 90% silica by weight, e.g. quartz
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/02—Optical fibres with cladding with or without a coating
    • G02B6/02042—Multicore optical fibres
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J61/00—Gas-discharge or vapour-discharge lamps
    • H01J61/02—Details
    • H01J61/30—Vessels; Containers
    • H01J61/302—Vessels; Containers characterised by the material of the vessel
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
    • H01J9/24—Manufacture or joining of vessels, leading-in conductors or bases
    • H01J9/245—Manufacture or joining of vessels, leading-in conductors or bases specially adapted for gas discharge tubes or lamps
    • H01J9/247—Manufacture or joining of vessels, leading-in conductors or bases specially adapted for gas discharge tubes or lamps specially adapted for gas-discharge lamps
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/51—Particles with a specific particle size distribution
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2004/00—Particle morphology
    • C01P2004/60—Particles characterised by their size
    • C01P2004/61—Micrometer sized, i.e. from 1-100 micrometer
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/11—Powder tap density
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/12—Surface area
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/14—Pore volume
    • C—CHEMISTRY; METALLURGY
    • C01—INORGANIC CHEMISTRY
    • C01P—INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
    • C01P2006/00—Physical properties of inorganic compounds
    • C01P2006/80—Compositional purity
    • C01P2006/82—Compositional purity water content
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/02—Pure silica glass, e.g. pure fused quartz
    • C03B2201/03—Impurity concentration specified
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/02—Pure silica glass, e.g. pure fused quartz
    • C03B2201/03—Impurity concentration specified
    • C03B2201/04—Hydroxyl ion (OH)
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2201/00—Glass compositions
    • C03C2201/06—Doped silica-based glasses
    • C03C2201/08—Doped silica-based glasses containing boron or halide
    • C03C2201/11—Doped silica-based glasses containing boron or halide containing chlorine
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2201/00—Glass compositions
    • C03C2201/06—Doped silica-based glasses
    • C03C2201/20—Doped silica-based glasses containing non-metals other than boron or halide
    • C03C2201/23—Doped silica-based glasses containing non-metals other than boron or halide containing hydroxyl groups
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2201/00—Glass compositions
    • C03C2201/06—Doped silica-based glasses
    • C03C2201/20—Doped silica-based glasses containing non-metals other than boron or halide
    • C03C2201/26—Doped silica-based glasses containing non-metals other than boron or halide containing carbon
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2201/00—Glass compositions
    • C03C2201/06—Doped silica-based glasses
    • C03C2201/30—Doped silica-based glasses containing metals
    • C03C2201/32—Doped silica-based glasses containing metals containing aluminium
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2203/00—Production processes
    • C03C2203/10—Melting processes
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2203/00—Production processes
    • C03C2203/40—Gas-phase processes
    • C03C2203/42—Gas-phase processes using silicon halides as starting materials
    • C03C2203/44—Gas-phase processes using silicon halides as starting materials chlorine containing
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C2203/00—Production processes
    • C03C2203/50—After-treatment
    • C03C2203/52—Heat-treatment
    • C03C2203/54—Heat-treatment in a dopant containing atmosphere
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/41—Refractivity; Phase-affecting properties, e.g. optical path length
    • G01N21/412—Index profiling of optical fibres
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P40/00—Technologies relating to the processing of minerals
    • Y02P40/50—Glass production, e.g. reusing waste heat during processing or shaping
    • Y02P40/57—Improving the yield, e-g- reduction of reject rates

Definitions

  • the invention relates to a method for producing a quartz glass body comprising the method steps i.) Providing a silica granule, ii.) Forming a glass melt from the silicon dioxide granules and iii.) Forming a quartz glass body from at least a part of the glass melt, wherein the providing the steps I. Generate a silica powder having at least two particles made of a silicon-chlorine compound, II. contacting the silica powder with water vapor to obtain a treated silica powder, and III. Granulating the treated silica powder to a silica granule, and wherein the chlorine content of the silica powder is higher than the chlorine content of the silica granules.
  • the invention further relates to a quartz glass body obtainable by this method.
  • the invention also relates to a method for producing a silica granulate.
  • the invention relates to a light guide, a lighting means and a shaped body, which are each available by further processing of the quartz glass body.
  • Quartz glass, quartz glass products and products containing quartz glass are known.
  • various methods for producing quartz glass and quartz glass bodies are already known. Nevertheless, considerable efforts continue to be made to identify manufacturing processes by which silica glass of even higher purity, that is, absence of impurities, can be produced.
  • quartz glass and its processing products particularly high demands, for example, in terms of homogeneity and purity. This is, among other things, the case with quartz glass, which is processed into optical fibers or in light sources. Impurities can cause absorption here. This is disadvantageous because it leads to color changes and to the attenuation of the emitted light.
  • Another example of the use of high-purity quartz glass are production steps in semiconductor production. Here, any contamination of the glass body potentially leads to defects of the semiconductor, and thus to rejects in the production.
  • the high-purity, often synthetic quartz glass used for these methods are therefore produced very expensive. They are high priced.
  • quartz glass bodies Shapes into quartz glass bodies from the melt. Irregularities in a vitreous body, for example due to the inclusion of gases in the form of bubbles, can result in failure of the vitreous under load, especially at high temperatures, or preclude use for a particular purpose. Thus, impurities of the quartz glass-forming raw material for the formation of cracks, bubbles, stripes and Discoloration in the quartz glass lead. When used in processes for the manufacture and treatment of semiconductor devices, it is also possible to work out impurities in the glass body and transfer them to the treated semiconductor components. This is the case, for example, in etching processes and then leads to rejects in the semiconductor blanks. A frequently occurring problem in the known production methods is consequently an insufficient quality of the quartz glass body.
  • Another aspect concerns the raw material efficiency. It appears to be advantageous to supply fumed silica and by-products thereof as by-products as possible to industrial processing into fused silica products rather than by-products as hitherto as filling material, e.g. in building construction, to spend or to dispose of waste as expensive. These by-products are often deposited as particulate matter in filters. The particulate matter raises further problems, in particular with regard to health, occupational safety and handling.
  • An object of the present invention is to at least partially overcome one or more of the disadvantages of the prior art.
  • components is meant in particular devices that can be used for or in reactors for chemical and / or physical treatment steps.
  • tempering can be dispensed with.
  • Foreign atoms are understood to mean components that have not been deliberately introduced.
  • Homogeneity of a property or a substance is a measure of the uniformity of the distribution of that property or substance in a sample.
  • the homogeneity of the substance is a measure of the uniformity of the distribution of elements and compounds contained in the light guide, illuminant or semiconductor apparatus, in particular of OH, chlorine, metals, in particular aluminum, alkaline earth metals, refractory metals and dopants.
  • Particulate matter has.
  • Another object is to further improve the processability of quartz glass bodies.
  • Another object is to further improve the manufacturability of quartz glass bodies.
  • a contribution to the at least partial fulfillment of at least one of the aforementioned tasks is provided by the independent claims.
  • the dependent claims provide preferred embodiments that contribute to at least partially performing at least one of the tasks.
  • Providing a silica granule comprising the steps of:
  • Wl a relative humidity of at least 50% by volume, for example of at least 60% by volume, more preferably of at least 70% by volume, based on the total volume of water vapor used;
  • a content of water in a range of 0.1 to 60 kg / m 3 , for example in a range of 0.15 to 50 kg / m 3 , particularly preferably in a range of 0.2 to 40 kg / m 3 , based on the total volume of water vapor;
  • a content of a gas other than water vapor for example, He, Ar, air or a
  • W5. a temperature in a range of 100 to 600 ° C, or preferably in a range of 120 to 550 ° C, or preferably in a range of 150 to 500 ° C;
  • a pressure of the steam in a range of 0.1 to 10 bar, preferably from 0.1 to 5 bar, the
  • Silica powder has at least one of the following features:
  • G a total content of metals other than aluminum of less than 2.5 ppm
  • H at least 70% by weight of the powder particles, based on the total number of powder particles, have a primary particle size of less than 100 nm
  • ppm and ppb are each based on the total weight of the silica powder.
  • a method for producing a silica granule comprising the following method steps:
  • chlorine content of the Sihziumdioxidpulvers is higher than the chlorine content of the Siliziumdioxidgranulats.
  • having at least one of the following characteristics:
  • G a pore volume in a range of 0.1 to 2.5 mL / g;
  • ppm and ppb are each related to the total weight of the silica granules.
  • a quartz glass body obtainable by a method according to one of the embodiments
  • C] has an aluminum content of less than 200 ppb
  • K a cylindrical shape
  • L has a tungsten content of less than 1000 ppb
  • M] has a molybdenum content of less than 1000 ppb
  • a method for producing a light guide comprising the following steps:
  • a method of manufacturing a luminous means comprising the following steps
  • Quartz glass body is first processed into a hollow body
  • a method for producing a shaped article comprising the following steps:
  • a use of a silica powder made of a silicon-chlorine compound for producing products comprising quartz glass selected from the group consisting of a light guide, a lighting means and a shaped body
  • range indications also include the values called limits.
  • An indication of the kind "in the range of X to Y" with respect to a quantity A thus means that A has the values X, Y and can take values between X and Y.
  • One-sided limited areas of the kind "up to Y" for a size A mean accordingly as values Y and smaller than Y.
  • a first subject of the present invention is a method for producing a quartz glass body comprising the method steps:
  • Providing a silica granule comprising the steps of:
  • the silicon dioxide powder selected in step i.) Has a particle size distribution D 50 in the range from 6 to 15 ⁇ m.
  • Silica powders of the aforementioned particle size distribution can be processed particularly well according to the present invention, in particular in the industrial production of quartz glass. Silica powders with a large proportion of particularly small powder particles are disadvantageous for the production of quartz glass. Such silicon powders mainly contain particulate matter. Most dust filters let particulate matter through much stronger than larger powder particles. Even after a steam treatment as in step II, difficulties arise with such silica powders. For example, it is difficult to separate powder suspended in water with a large proportion of particularly small powder particles, because those which do not separate the particularly small powder particles from the aqueous phase by gravity.
  • Silica powders with a proportion of large powder particles are considered disadvantageous in the further processing of the slurry into granules.
  • the slurry of silica powder and water described below is filtered.
  • fibers are separated from transport containers or possibly separating filters. It has been found that the filters which can be used for this purpose are added particularly quickly if the slurry contains many large powder particles.
  • the preferred range of the particle size distribution of silicon dioxide powder described above forms a particularly preferred section of the amount of available particle size distributions of silica powder.
  • the provision of the silicon dioxide granules includes the following method steps:
  • a powder is understood as meaning particles of dry solids having a primary particle size in the range of 1 to less than 100 nm.
  • the silica granules can be obtained by granulating silica powder.
  • a silica granule typically has a BET surface area of 3 m 2 / g or more and a density of less than 1.5 g / cm 3 .
  • Granulating is understood as meaning the transfer of powder particles into granules.
  • Granulation forms aggregates of multiple silica powder particles, ie larger agglomerates called “silica granules.” These are often referred to as “silica granule particles” or “granule particles.” Granules form granules in their entirety, eg, the silica granules are “silica granules.” , The silica granules have a larger particle diameter than the silica powder.
  • silicon dioxide granulation is understood as meaning silicon dioxide particles obtainable by comminuting a silicon dioxide body, in particular a quartz glass body.
  • a silica grain usually has a density of more than 1.2 g / cm 3 , for example in a range of 1.2 to 2.2 g / cm 3 , and more preferably about 2.2 g / cm 3 , More preferably, the BET surface area of a silica grain is generally less than 1 m 2 / g, determined according to DIN ISO 9277: 2014-01.
  • all silica particles suitable to the person skilled in the art come into consideration as silica particles.
  • Preferably selected are silica granules and silica granules.
  • a silicon dioxide powder is produced in step I.
  • the silica powder may be any silica powder having at least two particles and produced from a silicon-chlorine compound. Any method which is familiar to the person skilled in the art and suitable for the present purpose can be considered as the production method.
  • Under a silicon-chlorine compound is an inorganic compound of the elements silicon and chlorine, and optionally understood hydrogen and oxygen.
  • Preferred silicon-chlorine compounds are silicon tetrachloride and trichlorosilane.
  • the silica powder is produced in the production of quartz glass as a by-product, in particular in the production of so-called soot bodies.
  • silica of such origin is often referred to as "soot dust."
  • a preferred source of the silica powder is silica particles obtained in the synthetic production of soot bodies using flame hydrolysis burners Oxygen and hydrogen and the starting materials, for example silicon tetrachloride, for the formation of silicon dioxide primary particles can be supplied to the flame hydrolysis burners as fuel gases.
  • the silica primitives produced by flame hydrolysis aggregate or agglomerate to form silica particles with particle sizes of about 9 ⁇ m (DIN ISO 13320: 2009-1) d the silicon dioxide prima ⁇ umble recognizable by scanning electron microscopy in shape and the Primä ⁇ umble distress can be determined.
  • a portion of the silicon dioxide particles are deposited on the cylinder jacket surface of the support tube rotating about its longitudinal axis.
  • So layer by layer of 8 ⁇ is built.
  • Another part of the silicon dioxide particles is not deposited on the cylinder jacket surface of the support tube, but accumulates as dust, for example in a filter system.
  • This other part of silicon dioxide particles forms the silicon dioxide powder, often also referred to as "soot dust.”
  • the silicon dioxide particles deposited on the support tube are larger than the part of silicon dioxide particles resulting from soot dust based on the total weight of the silica particles.
  • soot dust is usually disposed of consuming and expensive as waste or spent without added value as a filler, e.g. in road construction, as additives in the dyestuff industry, as a raw material for tile production and for the production of hexafluorosilicic acid, which is used for the renovation of building foundations.
  • a filler e.g. in road construction, as additives in the dyestuff industry, as a raw material for tile production and for the production of hexafluorosilicic acid, which is used for the renovation of building foundations.
  • it is suitable as a starting material and can be processed to a high quality product.
  • Fumed silica is usually in the form of amorphous silica priming particles or silica particles.
  • the silica powder can be prepared by flame hydrolysis from a gas mixture.
  • the silica particles are also formed in the flame hydrolysis and discharged as silica powder before agglomerates or aggregates are formed.
  • the silica powder previously referred to as soot dust main product.
  • a preferred composition of a suitable gas mixture includes a proportion of oxygen in the flame hydrolysis in a range of 25 to 40% by volume.
  • the proportion of hydrogen may be in a range of 45 to 60% by volume.
  • the proportion of silicon tetrachloride is preferably from 5 to 30 vol .-%, all of the aforementioned Vol .-% based on the total volume of the gas stream.
  • the flame in the hydrolysis of the flame preferably has a temperature in a range from 1500 to 2900 ° C., for example in a range from 1600 to 2600 ° C., more preferably in one range from 1700 to 2300 ° C.
  • the silicon dioxide formed in the flame hydrolysis are preferably removed as silica powder before agglomerates or aggregates are formed.
  • the silica powder after its production in step I, and thus before contacting with water vapor in step II has at least one, for example a combination of two, three, four, five or six, particularly preferably all of the following characteristics:
  • I.-a a chlorine content of less than 500 ppm, for example less than 300 ppm or less than 200 ppm, more preferably in a range of from 1 ppb to 100 ppm;
  • I.-b an aluminum content of less than 200 ppb, for example in the range of 1 to 100 ppb, more preferably in the range of 1 to 80 ppb;
  • I.-C. a residual moisture of less than 5 wt .-%, for example in the range of 0.25 to 3 wt .-%, particularly preferably in the range of 0.5 to 2 wt .-%;
  • I.-D. a BET surface area in a range of 10 to 70 m 2 / g, for example, 15 to
  • I.-f. a carbon content of less than 50 ppm, for example less than 40 ppm or less than 30 ppm, more preferably in a range of from 1 ppb to 20 ppm;
  • I.-G. a total content of metals other than aluminum of less than 2500 ppb, for example in the range of 1 to 2300 ppb or of 10 to 2200 ppb or of 100 to 2200 ppb, or more preferably of 1000 to 2200 ppb;
  • I.-h. at least 70% by weight of the powder particles, based on the total number of powder particles, have a primary particle size of less than 100 nm, for example in a range of 10 to less than 100 nm, for example in the range of 15 to less than 100 nm, more preferably in the range of 20 to less than 100 nm;
  • a particle size distribution D 10 in the range of 1 to 10 ⁇ , for example in the range of 2 to 8 ⁇ , or in the range of 3 to 7 ⁇ , more preferably in the range of 4 to 6 ⁇ ;
  • I.-l. a particle size distribution D 90 in the range of 5 to 40 ⁇ , for example in the range of 10 to 30 ⁇ , more preferably in the range of 12 to 20 ⁇ ; wherein the wt%, ppm or ppb are each based on the total weight of the silica powder.
  • step II the silicon dioxide powder is contacted with water vapor and thus converted into a treated silica powder.
  • the water vapor contacting may be selected to wash out HCl formed.
  • both the "soot dust" produced by filtering off as a by-product or the "soot dust" formed as the main product in the flame hydrolysis can be used.
  • the contacting of the silicon dioxide powder with water vapor can be carried out in any manner known to the person skilled in the art and appearing suitable for this purpose. Preferably, the contacting takes place immediately after the flame hydrolysis.
  • immediate is understood as meaning a period of 0.01 to 180 s, for example in a period of 0.05 to 150 s, particularly preferably in a period of 0.1 to 120 s after the formation of the silicon dioxide powder.
  • the contacting in step II Takes place in the reaction space of the flame hydrolysis, or in direct connection to the reaction space.
  • the contacting of the silicon dioxide powder with the water vapor can in principle be carried out in any plant known to the person skilled in the art and suitable for this treatment.
  • the contacting of the silicon dioxide powder with the steam is preferably carried out in a continuous system, a discontinuous system or a combination thereof.
  • the plant preferably has an elongated shape.
  • the system preferably has a round, oval or angular cross section or a combination thereof, particularly preferably a round cross section.
  • the system can in principle be arbitrarily oriented.
  • the system is preferably oriented vertically. "Vertical" is understood to mean the direction of the solder, that is to say the direction of the gravity vector.
  • the plant is preferably selected from the group consisting of a vertical column, a horizontal column, a vertical rotary kiln, a horizontal rotary kiln or a combination of at least two thereof.
  • the silica powder is contacted in a vertical column with the water vapor. More preferably, the silica powder is contacted in a horizontal rotary kiln with the water vapor.
  • the contacting of the silica powder with steam to obtain a treated silica powder is preferably carried out at an elevated temperature, for example at a temperature of more than 50 ° C, more preferably at a temperature in a range of 60 to 90 ° C.
  • the temperature at the beginning of the system is at least 5 ° C, for example at least 10 ° C, more preferably at least 15 ° C higher than at the end of the system.
  • the temperature at the beginning of the plant is determined at a point which is 10 to 15% of the total length of the plant and related to the
  • the temperature at the end of the plant is determined at a point which is 10 to 15%, based on the total length of the plant and in relation to the direction of material transport in the plant, located in front of the solids outlet.
  • the residence time of the silica powder in the plant is preferably in a range of 1 s to 60 min, for example in a range of 5 s to 50 min, more preferably in a range of 10 s to 40 min.
  • the plant preferably has a length in a range from 1 to 100 m, for example in a range from 2 to 80 m, particularly preferably in a range from 3 to 50 m.
  • the plant preferably has a round diameter in a range of 0.1 to 30 m, for example in a range of 0.5 to 25 m, particularly preferably in a range of 1 to 20 m.
  • an amount of silica powder in a range of 0.1 to 100 kg / h, for example in a range of 0.2 to 80 kg / h, more preferably in a range of 0.5 to 50 kg / h passed through.
  • the plant passes an amount of water vapor in a range of 0.001 to 10 kg / h, for example in a range of 0.005 to 8 kg / h.
  • the ratio of steam to silica powder is preferably in a range of 1: 1000 to 1: 100, for example in a range of 1: 900 to 1: 150, more preferably in a range of 1: 800 to 1: 200.
  • this information applies to a batch which is limited by loading and unloading of the system.
  • the water vapor is in combination with a gas, for example air.
  • a gas for example air.
  • the amount of vapor V "of gas, for example air in a range of 0.001 to 0.3 m 3 per kg of water vapor, for example an amount V" in a range of 0.005 to 0.25 m 3 per kg of water vapor, more preferably, an amount of V "in a range of 0.01 to 0.2 m 3 per kg of water vapor added.
  • the quantity V " is understood to be the standard volume of the gas.
  • the standard volume V " is the amount of gas contained at 1.01325 bar and 273.15 K (0 ° C) in a volume V, where V" and V are the same under these conditions.
  • the silica powder is contacted in a continuously operated plant with the water vapor.
  • a continuously operated plant preferably has a solids inlet and a solids outlet. Silicon dioxide powder can enter the system through the solids inlet. Silica powder can be removed from the system through the solids outlet.
  • the solids inlet can in principle have any shape which is known to the person skilled in the art and which is suitable for introducing a solid into a plant.
  • the solids inlet is preferably a lock, a nozzle, an opening, a filler neck, particularly preferably a lock, for example a Zelbad lock.
  • the solids outlet can in principle have any shape which is known to the person skilled in the art and which is suitable for removing a solid from a plant.
  • the solids outlet is a sluice, a nozzle, an opening, a filler neck, particularly preferably a sluice, for example a Zelbad sluice.
  • About the solids outlet preferably contacted with steam silica powder is removed from the plant.
  • a continuously operated plant preferably has a fluid inlet and a fluid outlet. Through the fluid inlet water vapor can be entered into the system. Through the fluid outlet water vapor can be removed from the system.
  • the fluid inlet can in principle have any shape which is known to the person skilled in the art and which is suitable for introducing water vapor into the system.
  • the fluid inlet is a lock, a nozzle, an opening, a filler neck, particularly preferably a nozzle.
  • the fluid outlet can in principle have any shape which is known to the person skilled in the art and which is suitable for removing water vapor from the system.
  • the fluid outlet is preferably a lock, a nozzle, an opening, a filler neck, a pressure relief valve, particularly preferably a pressure relief valve.
  • the fluid inlet and the fluid outlet can be arranged arbitrarily in the system.
  • the fluid inlet and the fluid outlet are as far apart as possible.
  • the fluid inlet is at the end of the system and the fluid outlet is at the beginning of the system.
  • the contacting of the silicon dioxide powder takes place in countercurrent to water vapor.
  • the fluid inlet is at the beginning of the system and the fluid outlet is at the end of the system.
  • the contacting of the silicon dioxide powder takes place in a stream of steam.
  • the steam is introduced under pressure into the system.
  • the pressure with which the steam is introduced into the system is preferably in the range from 1.3 to 20 bar, for example in the range from 1.5 to 18 bar or from 2 to 15 bar or from 4 to 13 bar, or more preferably in the range of 5 to 12 bar, the pressure being absolute.
  • By-products may be formed in the process of contacting the silica powder with the water vapor, for example HCl. These are usually gaseous at the process conditions chosen for the contacting. Gaseous by-products are preferably removed from the plant through the fluid outlet.
  • the plant for contacting the silica powder with water vapor is a vertical column.
  • the plant for contacting the silicon dioxide powder with water vapor is a horizontal rotary kiln.
  • a rotary kiln at least a part of the furnace, which comes in contact with the silica powder, rotates about a horizontal or vertical axis of the rotary kiln.
  • the rotary kiln has at least one opening for loading and unloading the furnace.
  • the rotary kiln has at one end of the rotary tube an opening as an inlet for loading and at the other end of the rotary tube an opening as an outlet for discharging.
  • such a rotary kiln is operated continuously.
  • the at least two particles of the silica powder due to the rotational movement of a portion of the furnace body from a relative movement to each other. This relative movement can be assisted by contacting the silica powder with the water vapor. More preferably, the silica powder is contacted in a continuously operated plant with the water vapor.
  • a kettle in which the silica powder is filled.
  • the water vapor can be brought into contact with the silicon dioxide powder.
  • the kettle is provided with at least one device to move the silica powder in the kettle.
  • suitable devices which are known and suitable for this purpose to the person skilled in the art can be selected.
  • stirring, shaking or swiveling devices Preferably, the contents of the kettle are mixed so that the silica powder is completely contacted with the water vapor.
  • the contacting of the silicon dioxide powder with water vapor is carried out in at least two steps.
  • at least two systems are used in succession.
  • the systems can be operated independently of each other continuously, discontinuously or semi-continuously.
  • the at least two plants are two or more continuously operated plants.
  • the silica powder taken from the first plant is preferably introduced directly into the second plant.
  • the second system preferably has the same structure as the first system.
  • the steam is preferably introduced simultaneously or subsequently to the introduced silicon dioxide powder.
  • the at least two plants are two continuously operated vertical columns arranged one behind the other, wherein at the end of the first column the outlet for the treated silicon dioxide powder is arranged, which opens directly into the inlet at the beginning of the second column. In this way, more than two columns can be connected to each other.
  • the use of more than one plant for contacting the silica powder with steam has the advantage that a higher degree of purification of the silica powder of HCl can be achieved.
  • the method is characterized by performing a relative movement of the at least two particles to each other.
  • the relative movement of the at least two particles may preferably be effected by a measure selected from the group consisting of contacting with water vapor, preferably under elevated pressure, moving at least a portion of the plant containing the silica powder, applying gravity to the silica powder or a gravitational force Combining at least two of these measures.
  • the contacting of the silica powder with the water vapor may be effected before, during or after the relative movement of the at least two particles or a combination of at least two thereof.
  • the relative movement preferably takes place at least during the contacting of the silicon dioxide powder with the water vapor, more preferably before, during and after the contacting.
  • a continuous system is preferably used.
  • the relative movement of the at least two particles relative to one another takes place in a rotary kiln, as described above.
  • the steam preferably has at least one, for example at least two or at least three or at least four, more preferably at least five of the following characteristics:
  • Wl. a relative humidity of at least 50% by volume, for example of at least 60% by volume, more preferably of at least 70% by volume, based on the total volume of the starting material used
  • a content of water in a range of 0.1 to 60 kg / m 3 , for example in a range of
  • a content of a gas other than water vapor for example, He, Ar, air or a
  • a content of noble gas in a range of 0.1 to 5 vol.%, for example, in a range of
  • W5. a temperature in a range of 100 to 600 ° C, or preferably in a range of 120 to
  • a pressure of the steam in a range of 0.1 to 10 bar, preferably from 0.1 to 5 bar, the
  • the sum of all constituents of the water vapor always give 100 wt .-% based on the total weight of the water vapor.
  • the noble gas according to feature W4 is preferably selected from the group consisting of helium, argon, krypton, xenon or a mixture of at least two thereof, more preferably the noble gas is helium or argon or a combination thereof.
  • the weight ratio of steam to silica is in a range of 1: 1 to 100: 1, for example in a range of 2: 1 to 50: 1, more preferably in a range of 5: 1 to 20: 1.
  • the ratio of the chlorine content of the silica powder before the steaming treatment and the chlorine content of the silica powder after the steaming is in a range of 500: 1 to 10: 1, for example, in a range of 450: 1 to 20: 1, more preferably in a range of 400: 1 to 30: 1.
  • the pH of an aqueous 4% dispersion of the treated silica powder is in one
  • Range from 3.0 to 5.5 for example in a range from 3.3 to 5.3, more preferably in a range from 3.5 to 5.0.
  • the pH of an aqueous 4% dispersion of the silica powder before the steam treatment is preferably in a range of 1.0 to 2.5, for example in a range of 1.3 to 2.2, particularly preferably in a range of 1, 5 to 2.0.
  • the pH of an aqueous 4% dispersion of the silica powder before the steam treatment is preferably in a range of 1.0 to 2.5, for example in a range of 1.3 to 2.2, particularly preferably in a range of 1, 5 to 2.0.
  • the pH of an aqueous 4% dispersion of the silica powder before the steam treatment is preferably in a range of 1.0 to 2.5, for example in a range of 1.3 to 2.2, particularly preferably in a range of 1, 5 to 2.0.
  • the pH of an aqueous 4% dispersion of the silica powder before the steam treatment is preferably
  • the steam-treated silica powder has the following characteristics:
  • a residual moisture content of less than 5% by weight for example in the range of 0.25 to 3% by weight, more preferably in the range of 0.5 to 2% by weight;
  • a BET surface area in a range from 10 to 70 m 2 / g, for example from 25 to 55 m 2 / g, or from 30 to 50 m 2 / g, particularly preferably from 20 to 40 m 2 / g, and
  • a bulk density of 0.01 to 0.3 g / cm 3 for example in the range of 0.02 to 0.2 g / cm 3 , preferably in the range of 0.03 to 0.15 g / cm 3 ;
  • G a total content of metals other than aluminum of less than 2500 ppb, for example in the range of 1 to 2300 ppb or of 10 to 2200 ppb or of 100 to 2200 ppb, or more preferably of 1000 to 2200 ppb;
  • At least 70% by weight of the powder particles have a primary particle size in a range of 10 to less than 100 nm, for example in the range of 15 to less than 100 nm, more preferably in the range of 20 to less than 100 nm;
  • a tamped density in a range of 0.001 to 0.3 g / cm 3 for example in the range of 0.002 to 0.2 g / cm 3 or from 0.005 to 0.1 g / cm 3 , preferably in the range of 0.01 to 0.06 g / cm 3 ;
  • a particle size distribution D 10 in the range of 1 to 7 ⁇ for example in the range of 2 to 6 ⁇ or in the range of 3 to 5 ⁇ , more preferably in the range of 3.5 to 4.5 ⁇ ;
  • a particle size distribution D 90 in the range of 10 to 40 ⁇ , for example in the range of 15 to 35 ⁇ , particularly preferably in the range of 20 to 30 ⁇ ;
  • the treated silica powder contains silica.
  • the treated silica powder contains silica in an amount of more than 95% by weight, for example, in an amount of more than 98% by weight or more than 99% by weight or more than 99.9% by weight .-%, each based on the total weight of the treated silica powder. More preferably, the treated silica powder contains silica in an amount greater than 99.99 wt%, based on the total weight of the treated silica powder.
  • the treated silica powder has a metal content of metals other than aluminum of less than 5 ppm, for example less than 2.5 ppm or less than 2 ppm, more preferably less than 1 ppm, each based on the total weight of the treated silica powder , on.
  • the treated silica powder has a content of metals other than aluminum in an amount of at least 1 ppb.
  • metals include sodium, lithium, potassium, magnesium, calcium, strontium, germanium, copper, molybdenum, tungsten, titanium, iron and chromium. These may be present, for example, as an element, as part of a molecule or an ion or a complex.
  • the treated silica powder has a total content of metals other than aluminum in a range of 1 to 2300 ppb, for example, in the range of 10 to 2200 ppb or 100 to 2200 ppb, or more preferably 1000 to 2200 ppm
  • the treated silica powder has a total content of other ingredients of less than 30 ppm, for example less than 20 ppm, more preferably less than 15 ppm, the ppm each based on the total weight of the treated silica powder. Often, however, the treated silica powder has a content of other ingredients in an amount of at least 1 ppb. Further constituents are understood as meaning all constituents of the treated silica powder which do not belong to the following group: silicon dioxide, chlorine, aluminum, OH groups.
  • the indication of an ingredient when the ingredient is a chemical element means that it may be present as an element or as an ion in a compound or a salt.
  • aluminum also includes aluminum salts, aluminum oxides and aluminum metal complexes
  • chlorine includes, in addition to elemental chlorine, chlorides such as sodium chloride and hydrogen chloride. Often, the other ingredients are in the same state of matter as the substance in which they are contained.
  • the indication of an ingredient when the ingredient is a chemical compound or a functional group, means that the ingredient may be in said form, as a charged chemical compound, or as a derivative of the chemical compound.
  • the indication of the chemical ethanol includes ethanol as well as ethanol, for example, sodium ethanolate.
  • the term "OH group” also includes silanol, water and metal hydroxides
  • the term derivative in acetic acid also includes acetic acid ester and acetic anhydride.
  • At least 70% of the powder particles of the treated silica powder have a primary article size of less than 100 nm, for example in the range of 10 to 100 nm or 15 to 100 nm, and more preferably in the range of 20 to 100 nm.
  • the primary particle size is determined by dynamic light scattering according to ISO 13320: 2009-10.
  • At least 75% of the powder particles of the treated silica powder, based on the number of powder particles, have a primary article size of less than 100 nm, for example in the range of 10 to 100 nm or 15 to 100 nm, and more preferably in the range of 20 to 100 nm.
  • at least 80% of the powder particles of the treated silica powder, based on the number of powder particles have a primary article size of less than 100 nm, for example in the range of 10 to 100 nm or 15 to 100 nm, and more preferably in the range of 20 to 100 nm.
  • At least 85% of the powder particles of the treated silica powder have a primary article size of less than 100 nm, for example in the range of 10 to 100 nm or 15 to 100 nm, and more preferably in the range of 20 to 100 nm.
  • At least 90% of the powder particles of the treated silica powder have a primary article size of less than 100 nm, for example in the range of 10 to 100 nm or 15 to 100 nm, and more preferably in the range of 20 to 100 nm.
  • At least 95% of the powder particles of the treated silica powder have a primary article size of less than 100 nm, for example in the range of 10 to 100 nm or 15 to 100 nm, and more preferably in the range of 20 to 100 nm.
  • the treated silica powder has a particle size D 10 in the range of 1 to 7 ⁇ , for example in the range of 2 to 6 ⁇ or in the range of 3 to 5 ⁇ , particularly preferably in the range of 3.5 to 4.5 ⁇ .
  • the treated silica powder has a particle size D 50 in the range of 6 to 15 ⁇ , for example in the range of 7 to 13 ⁇ or in the range of 8 to 11 ⁇ , particularly preferably in the range of 8.5 to 10.5 ⁇ .
  • the treated silica powder has a particle size D 90 in the range of 10 to 40 ⁇ , for example in the range of 15 to 35 ⁇ , particularly preferably in the range of 20 to 30 ⁇ .
  • the treated silica powder has a specific surface area (BET surface area) in a range from 10 to 70 m 2 / g, for example from 20 to 60 m 2 / g, or from 30 to 50 m 2 / g, more preferably from 20 to 40 m 2 / g.
  • BET surface area is determined according to the method of Brunauer, Emmet and Teller (BET) on the basis of DIN 66132 and is based on gas absorption at the surface to be measured.
  • the treated silica powder has a pH of less than 7, for example in the range of 3 to 6.5 or of 3.5 to 6 or of 4 to 5.5, more preferably in the range of 4.5 to 5.
  • the pH can be determined by means of a dipstick electrode (4% by weight of treated silica powder in water).
  • the silicon dioxide powder preferably has the feature combination a./b./d. or a./b./e. or a./b./h. on, more preferably the combination of features a./b./d./e. or a./b./d./h. or a./b./e./h., particularly preferably the combination of features a./b./d./e./h.
  • the silicon dioxide powder preferably has the feature combination a./b./d. wherein the chlorine content is less than 100 ppm, the aluminum content is in a range of 1 to 100 ppb, and the BET surface area is in a range of 20 to 40 m 2 / g.
  • the silicon dioxide powder preferably has the feature combination a./b./e. wherein the chlorine content is less than 100 ppm, the aluminum content is in a range of 1 to 100 ppb, and the bulk density is in a range of 0.03 to 0.15 g / cm 3 .
  • the silicon dioxide powder preferably has the feature combination a./b./h. wherein the chlorine content is less than 100 ppm, the aluminum content is in a range of 1 to 100 ppb, and at least 70% by weight of the powder particles have a primary particle size in a range of 20 to less than 100 nm.
  • the silicon dioxide powder more preferably has the feature combination a./b./d./e. wherein the chlorine content is less than 100 ppm, the aluminum content is in a range of 1 to 100 ppb, the BET surface area is in a range of 20 to 40 m 2 / g, and the bulk density is in a range of 0.03 to 0.15 g / cm 3 .
  • the silicon dioxide powder more preferably has the feature combination a./b./d./h. wherein the chlorine content is less than 100 ppm, the aluminum content is in a range of 1 to 100 ppb, the BET surface area is in a range of 20 to 40 m 2 / g, and at least 70 wt% of the powder particles is one Primary particle size in a range of 20 to less than 100 nm.
  • the silicon dioxide powder more preferably has the feature combination a./b./e./h. wherein the chlorine content is less than 100 ppm, the aluminum content is in a range of 1 to 100 ppb, the bulk density is in a range of 0.03 to 0.15 g / cm 3 and at least 70% by weight of Powder particles have a primary particle size in a range of 20 to less than 100 nm.
  • the silicon dioxide powder particularly preferably has the feature combination a./b./d./e./h. wherein the chlorine content is less than 100 ppm, the aluminum content is in a range of 1 to 100 ppb, the BET surface area is in a range of 20 to 40 m 2 / g, the bulk density is in a range of 0.03 to 0.15 g / cm 3 and at least 70 wt .-% of the powder particles have a primary particle size in a range of 20 to less than 100 nm. Step III.
  • the treated silica powder is processed in step III to a granular silica, wherein the silica granules have a larger particle diameter than the treated silica powder.
  • Suitable in principle are all methods known to those skilled in the art, which lead to an increase in the particle diameter.
  • the silica granules have a particle diameter larger than the particle diameter of the silica powder.
  • the particle diameter of the silica granules is in a range of 500 to 50,000 times larger than the particle diameter of the silica powder, for example, 1,000 to 10,000 times larger, more preferably 2,000 to 8,000 times larger.
  • At least 90% of the silicon dioxide granules provided in step i) are preferably formed from pyrogenically produced silicon dioxide powder, for example at least 95% by weight or at least 98% by weight, more preferably at least 99% by weight or more, based in each case on the Total weight of silica granules.
  • the silica granules used have the following features:
  • G a pore volume in a range of 0.1 to 2.5 mL / g, for example in a range of 0.15 to 1.5 mL / g; more preferably in a range of 0.2 to 0.8 mL / g;
  • ppm and ppb are each based on the total weight of the silica granules.
  • the granules of the silica granules preferably have a spherical morphology.
  • Spherical morphology refers to a round to oval shape of the particles.
  • the granules of the silica granules preferably have an average sphericity in a range of 0.7 to 1.3 SPHT3, for example, an average sphericity in a range of 0.8 to 1.2 SPHT3, more preferably an average sphericity in a range of 0 , 85 to 1.1 SPHT3 on.
  • the characteristic SPHT3 is described in the test methods.
  • the granules of the silica granules have a mean symmetry in a range of 0.7 to 1.3 Symm3, for example a mean symmetry in a range of 0.8 to 1.2 Symm3, more preferably a mean symmetry in a range of 0.85 to 1.1 Symm3.
  • Symm3 The feature of symmetry Symm3 is described in the test methods.
  • the silica granules have a metal content of metals other than aluminum of less than 1000 ppb, for example less than 500 ppb, more preferably less than 100 ppb, each based on the total weight of the silica granules. Often this indicates
  • silica granules have a content of metals other than aluminum in an amount of at least 1 ppb.
  • the silica granules have a metal content of metals other than aluminum of less than 1 ppm, preferably in a range of 40 to 900 ppb, for example in a range of 50 to 700 ppb, more preferably in a range of 60 to 500 ppb, respectively based on the total weight of the silica granules.
  • metals include sodium, lithium, potassium, magnesium, calcium, strontium, germanium, copper, molybdenum, titanium, iron and chromium. These may be present, for example, as an element, as part of a molecule or an ion or a complex.
  • the silica granules may contain further constituents, for example in the form of molecules, ions or elements.
  • the silica granules contain less than 500 ppm, for example less than 300 ppm, more preferably less than 100 ppm, in each case based on the total weight of the silica granules, further constituents.
  • further ingredients are included in an amount of at least 1 ppb.
  • the further constituents may in particular be selected from the group consisting of carbon, fluoride, iodide, bromide, phosphorus or a mixture of at least two thereof.
  • the silica granules contain less than 10 ppm carbon, for example less than 8 ppm or less than 5 ppm, more preferably less than 4 ppm, each based on the total weight of the silica granules. Often, carbon is included in an amount of at least 1 ppb.
  • the silica granules contain less than 100 ppm, for example less than 80 ppm, more preferably less than 70 ppm, based in each case on the total weight of the silica granules, of further constituents. Often, however, the other ingredients are included in an amount of at least 1 ppb.
  • step III following steps:
  • a liquid is understood as meaning a substance or a substance mixture which is liquid at a pressure of 1013 hPa and a temperature of 20 ° C.
  • a "slurry" means a mixture of at least two substances, the mixture having at least one liquid and at least one solid under the conditions under consideration.
  • liquids are suitable as liquids.
  • the liquid is selected from the group consisting of organic liquids and water.
  • the silica powder is soluble in the liquid in an amount of less than 0.5 g / L, preferably in an amount of less than 0.25 g / L, more preferably in an amount of less than 0.1 g / L, the g / L is given as g silica powder per liter of liquid.
  • Preferred liquids are polar solvents. These can be organic liquids or water.
  • the liquid is selected from the group consisting of water, methanol, ethanol, n- Propanol, iso-propanol, n-butanol, tert-butanol and mixtures of more than one of them.
  • the liquid is water.
  • the liquid includes distilled or deionized water.
  • the silica powder is processed into a slurry.
  • the silica powder is almost insoluble in the liquid at room temperature, but may be incorporated into the liquid in high weight fractions to obtain the slurry.
  • the silica powder and the liquid may be mixed in any manner.
  • the silica powder may be added to the liquid or the liquid to the silica powder.
  • the mixture may be agitated during addition or after addition. Most preferably, the mixture is agitated during and after adding. Examples of agitation are shaking and stirring, or a combination of both.
  • the silica powder may be added to the liquid with stirring. More preferably, a portion of the silica powder may be added to the liquid, with the resulting mixture agitated, and the mixture subsequently mixed with the remainder of the silica powder.
  • a portion of the liquid may be added to the silica powder, with the resulting mixture agitated, and the mixture subsequently mixed with the remainder of the liquid.
  • the slurry is a suspension in which the silica powder is evenly distributed in the liquid.
  • uniformly it is meant that the density and composition of the slurry at each point does not differ by more than 10% from the average density and the average composition, based on the total amount of slurry, uniform distribution of the silica powder in the liquid can be made or obtained by moving as previously described, or both.
  • the slurry has a liter weight in the range of 1000 to 2000 g / L, for example in the range of 1200 to 1900 g / L or of 1300 to 1800 g / L, more preferably in the range of 1400 to 1700 g / L.
  • the weight per liter is determined by weighing a volume calibrated container.
  • the slurry has at least one, for example at least two or at least three or at least four, more preferably at least five of the following characteristics:
  • the slurry has a temperature of more than 0 ° C, preferably in a range of 5 to 35 ° C;
  • the slurry has a zeta potential at a pH of 7 in a range of 0 to -100 mA, for example from -20 to -60 mA, more preferably from -30 to -45 mA; e. ) the slurry has a pH in a range of 7 or more, for example greater than 7 or a pH in the range of 7.5 to 13 or from 8 to 11, more preferably from 8.5 to 10 ;
  • the slurry has an isoelectric point of less than 7, for example in one
  • the slurry has a solids content of at least 40% by weight, for example in one
  • the slurry has a viscosity in accordance with DIN 53019-1 (5 rpm, 30 wt .-%) in a range of 500 to 2000 mPas, for example in the range of 600 to 1700 mPas, particularly preferably in the range of 1000 to 1600 mPas ;
  • the slurry has a thixotropy according to DIN SPEC 91143-2 (30 wt .-% in water, 23 ° C,
  • the silica particles in the slurry have in a 4% by weight slurry an average particle size in suspension according to DIN ISO 13320-1 in the range from 100 to 500 nm, for example in a range from 200 to 300 nm.
  • the silica particles in a 4 wt .-% aqueous slurry has a particle size D 10 in a range of 50 to 250 nm, more preferably in the range of 100 to 150 nm.
  • the silica particles in a 4 wt .-% aqueous slurry has a particle size D 50 in the range of 100 to 400 nm, more preferably in the range of 200 to 250 nm.
  • the silica particles have, in a 4 wt .-% aqueous slurry has a particle size D 90 in the range of 200 to 600 nm, more preferably in a range of 350 to 400 nm.
  • the particle size is determined by means of DIN ISO 13320-1.
  • isolectric point is understood to mean the pH value at which the zeta potential assumes the value 0.
  • the zeta potential is determined in accordance with ISO 13099-2: 2012.
  • the pH of the slurry is adjusted to a value in the above range.
  • substances such as NaOH or NH 3 may be added , for example, as an aqueous solution of the slurry. The slurry is often moved.
  • the silica granules are obtained by granulating silica powder. Granulating is understood as meaning the transfer of powder particles into granules. During granulation, agglomerates, called “silica granules,” are formed by the intercalations of multiple silica powder particles, often referred to as “silica particles.” "Silica granule particles” or “granule particles”. In their entirety, granules form a granulate, eg the silica granules a "silica granulate”.
  • any granulation process which is known to the person skilled in the art and suitable for granulating silicon dioxide powder can be selected.
  • the granulation process a distinction can be made between built-up granulation and pressing granulation, and further between wet and dry granulation processes.
  • Known methods are rolling granulation in a granulating dish, spray granulation, centrifugal atomization, fluidized-bed granulation, granulation processes using a granulating mill, compaction, roll pressing, briquetting, flake production or extrusion.
  • a silica granule is formed with granules having a spherical morphology; wherein the processing is more preferably done by spray granulation or roll granulation.
  • silica granules containing granules having a spherical morphology include at most 50% granules, preferably at most 40% granules, more preferably at most 20% granules, more preferably between 0 and 50%, between 0 and 40%, or between 0 and 20 %>, or between 10 and 50%), between 10 and 40% o or between 10 and 20% o Granules that do not have a spherical morphology, the percentages in each case based on the total number of granules in the granules.
  • the granules with a spherical morphology have the already mentioned in this description SPHT3 values.
  • a silica granule is obtained by spray granulating the slurry.
  • Spray granulation is also referred to as spray drying.
  • the spray drying is preferably carried out in a spray tower.
  • the slurry is pressurized at elevated temperature.
  • the pressurized slurry is then released through a nozzle and sprayed into the spray tower.
  • droplets form, which dry instantly and initially form dry micro-particles ("germs.")
  • the micro-particles together with a gas stream acting on the particles, form a fluidized bed which holds them in suspension and can thus form a surface for drying further droplets form.
  • the nozzle through which the slurry is sprayed into the spray tower preferably forms an inlet into the interior of the spray tower.
  • the nozzle preferably has a contact surface with the slurry during spraying. Often, at least a portion of the nozzle is shaped as a tube through which the slurry is passed during spraying so that the inside of the hollow tube communicates with the slurry Slurry comes into contact.
  • the contact surface preferably includes a glass, a plastic or a combination thereof.
  • the contact surface comprises a glass, more preferably quartz glass.
  • the contact surface includes a plastic.
  • all plastics known to those skilled in the art are suitable, which in the Process temperatures are stable and donate any impurities to the slurry.
  • Preferred plastics are polyolefins, for example homo- or copolymers containing at least one olefin, more preferably homopolymers or copolymers comprising polypropylene, polyethylene, polybutadiene or combinations of two or more thereof.
  • the contact surface consists of a glass, a plastic or a combination thereof, for example selected from the group consisting of quartz glass and polyolefins, more preferably selected from the group consisting of quartz glass and homopolymers or copolymers comprising polypropylene, polyethylene, polybutadiene or combinations of two or more of them.
  • the contact surface preferably contains no metals, in particular no tungsten, titanium, tantalum, chromium, cobalt, nickel, iron, vanadium, zirconium and manganese.
  • the contact surface and the other parts of the nozzle consist of the same or of different materials.
  • the other parts of the nozzle contain the same material as the contact surface.
  • the other parts of the nozzle contain a different material from the contact surface.
  • the contact surface may be coated with a suitable material, for example a glass or a plastic.
  • the nozzle is preferably more than 70% by weight, based on the total weight of the nozzle, of an element selected from the group consisting of glass, plastic or a combination of glass and plastic, for example more than 75% by weight. % or more than 80 wt .-% or more than 85 wt .-% or more than 90 wt .-% or more than 95 wt .-%, particularly preferably more than 99 wt .-%.
  • the nozzle comprises a nozzle plate.
  • the nozzle plate is preferably formed of glass, plastic or a combination of glass and plastic.
  • the nozzle plate is formed of glass, particularly preferably quartz glass.
  • the nozzle plate is formed of plastic.
  • Preferred plastics are polyolefins, for example homo- or copolymers containing at least one olefin, more preferably homopolymers or copolymers comprising polypropylene, polyethylene, polybutadiene or combinations of two or more thereof.
  • the nozzle plate preferably contains no metals, in particular no tungsten, titanium, tantalum, chromium, cobalt, nickel, iron, vanadium, zirconium and manganese.
  • the nozzle preferably comprises a spiral screw.
  • the spiral screw is preferably made of glass, plastic or a combination of glass and plastic.
  • the spiral screw is formed of glass, more preferably quartz glass.
  • the spiral screw is formed from plastic.
  • Preferred plastics are polyolefins, for example homo- or copolymers containing at least one olefin, more preferably homopolymers or copolymers comprising polypropylene, polyethylene, polybutadiene or combinations of two or more thereof.
  • the spiral screw contains no metals, in particular no tungsten, titanium, tantalum, chromium, cobalt, nickel, iron, vanadium, zirconium and manganese.
  • the nozzle may further comprise other components.
  • Preferred further components are a nozzle body, particularly preferred is a nozzle body surrounding the spiral screw and the nozzle plate, a cross piece and a baffle plate.
  • a nozzle comprises one or more, more preferably all, the other
  • the other components can, independently of one another, in principle be made from any one skilled in the art known and suitable for this purpose material, for example, from a metal-containing material, glass or plastic.
  • the nozzle body is formed of glass, more preferably quartz glass.
  • the other components are formed from plastic.
  • Preferred plastics are polyolefins, for example homopolymers or copolymers containing at least one olefin, more preferably homopolymers or copolymers comprising polypropylene, polyethylene, polybutadiene or combinations of two or more thereof.
  • the other components preferably do not contain any metals, in particular no tungsten, titanium, tantalum, chromium, cobalt, nickel, iron, vanadium, zirconium and manganese.
  • the spray tower has a gas inlet and a gas outlet.
  • gas inlet gas can be introduced into the interior of the spray tower, and through the gas outlet, it can be discharged. It is also possible to introduce gas through the nozzle into the spray tower. Similarly, gas can be discharged through the outlet of the spray tower.
  • gas may be supplied via the nozzle and a gas inlet of the spray tower, and discharged via the outlet of the spray tower and a gas outlet of the spray tower.
  • an atmosphere selected from air, an inert gas, at least two inert gases or a combination of air with at least one inert gas, preferably at least two inert gases is present in the interior of the spray tower.
  • inert gases are preferably selected from the list consisting of nitrogen, helium, neon, argon, krypton and xenon.
  • air, nitrogen or argon is present in the interior of the spray tower, more preferably air.
  • the atmosphere present in the spray tower is part of a gas stream.
  • the gas stream is preferably introduced into the spray tower via a gas inlet and discharged via a gas outlet. It is also possible to introduce parts of the gas stream through the nozzle and divert parts of the gas stream through a solids outlet.
  • the gas stream can take up additional components in the spray tower. These may originate from the slurry during spray drying and pass into the gas stream.
  • a dry gas stream is fed to the spray tower.
  • a dry gas stream is understood as meaning a gas or a gas mixture whose relative humidity is below the condensation point at the temperature set in the spray tower.
  • a relative humidity of 100% corresponds to a water volume of 17.5 g / m 3 at 20 ° C.
  • the gas is preferably preheated to a temperature in a range of from 150 to 450 ° C, for example from 200 to 420 ° C or from 300 to 400 ° C, more preferably from 350 to 400 ° C.
  • the interior of the spray tower is preferably tempered.
  • the temperature in the interior of the spray tower is up to 550 ° C, for example 300 to 500 ° C, more preferably 350 to 450 ° C.
  • the gas stream at the gas inlet preferably has a temperature in a range from 150 to 450 ° C, for example from 200 to 420 ° C or from 300 to 400 ° C, particularly preferably from 350 to 400 ° C.
  • the withdrawn gas stream preferably has a temperature of less than 170 ° C, for example from 50 to 150 ° C, more preferably from 100 to 130 ° C. More preferably, the difference between the temperature of the gas stream at the time of introduction and the gas flow when discharged is in a range of 100 to 330 ° C, for example, 150 to 300 ° C.
  • the silica granules thus obtained are present as an agglomerate of individual particles of silica powder.
  • the individual particles of the silicon dioxide powder are still recognizable in the agglomerate.
  • the average particle size of the particles of the silica powder is preferably in the range of 10 to 1000 nm, for example, in the range of 20 to 500 nm or 30 to 250 nm or 35 to 200 nm or 40 to 150 nm, or more preferably in the range from 50 to 100 nm.
  • the average particle size of these particles is determined according to DIN ISO 13320-1.
  • auxiliaries can be used as auxiliaries, which are known in the art and appear suitable for the present purpose.
  • auxiliaries are, for example, so-called binders.
  • suitable binders are metal oxides such as calcium oxide, metal carbonates such as calcium carbonate and polysaccharides such as cellulose, cellulose ethers, starch and starch derivatives.
  • spray drying is particularly preferably carried out without auxiliaries.
  • a portion thereof is separated.
  • the separation is done by sifting or sieving.
  • the sifting is preferably carried out by a cyclone, which is preferably arranged in the lower region of the spray tower, particularly preferably above the outlet of the spray tower.
  • the sieving of the particles can be carried out in principle by all methods known to the person skilled in the art and suitable for this purpose. Sieving is preferably carried out by means of a vibrating trough.
  • the spray-drying of the slurry through a nozzle is into one
  • Spray tower by at least one, for example two or three, most preferably all of the following
  • a temperature of the droplets entering the spray tower in a range of 10 to 50 ° C, preferably in a range of 15 to 30 ° C, more preferably in a range of 18 to 25 ° C.
  • a temperature at the spray tower side of the nozzle in a range of 100 to 450 ° C, for example in a range of 250 to 440 ° C, more preferably from 350 to 430 ° C;
  • a flow rate of slurry through the die in a range of 0.05 to 1 m 3 / h, for example in a range of 0.1 to 0.7 m 3 / h or from 0.2 to 0.5 m 3 / h, more preferably in a range of 0.25 to 0.4 m 3 / h;
  • a solids content of the slurry of at least 40% by weight for example in a range of 50 to 80% by weight, or in a range of 55 to 75% by weight, particularly preferably in a range of 60 to 70% by weight. %, based in each case on the total weight of the slurry; a gas flow in the spray tower in a range of 10 to 100 kg / min, for example in a range of 20 to 80 kg / min or from 30 to 70 kg / min, more preferably in a range of 40 to 60 kg / min;
  • a temperature of the gas stream entering the spray tower in a range of 100 to 450 ° C, for example in a range of 250 to 440 ° C, more preferably 350 to 430 ° C;
  • a temperature of the gas stream exiting the spray tower of less than 170 ° C;
  • the gas is selected from the group consisting of air, nitrogen and helium, or a
  • a residual moisture content of the granules when taken from the spray tower of less than 5 wt .-%, for example less than 3 wt .-% or less than 1 wt .-% or in a range of 0.01 to 0.5 wt .-%, particularly preferably in a range of 0.1 to 0.3 wt .-%, each based on the total weight of the resulting during spray drying silica granules;
  • At least 50% by weight of the spray granules based on the total weight of the silica granules formed in the spray drying, has a time of flight in a range of 1 to 100 s, for example over a period of 10 to 80 s, particularly preferably over a period of 25 up to 70 s;
  • At least 50% by weight of the spray granules travels more than 20 m, for example more than 30 or more than 50, or more than 70 or more than 100 or more than 150 or more than 200 or in a range of 20 to 200 m or from 10 to 150 or from 20 to 100, particularly preferably in a range of 30 to 80 m.
  • the spray tower has a cylindrical geometry
  • a height of the spray tower of more than 10 m, for example of more than 15 m or of more than 20 m or of more than 25 m or of more than 30 m or in a range of 10 to 25 m, particularly preferably in one area from 15 to 20 m;
  • the flight path means the path that a droplet of slurry travels from the exit of the nozzle into the headspace of the spray tower to form granules until completion of the flight and fall operation.
  • the flight and fall process will periodically end by impacting the granule at the bottom of the spray tower, or by granules coming into contact with other granules resting on the bottom of the spray tower, whichever comes first.
  • the flight time is the time it takes for a granule to cover the flight path in the spray tower.
  • the granules preferably have a helical trajectory in the spray tower.
  • At least 60% by weight of the spray granules based on the total weight of the silica granules formed during the spray drying, have an average flight distance of more than 20 m, for example greater than 30 or greater than 50 or greater than 70 or more than 100 or more than 150 or more than 200 or in a range of 20 to 200 m or from 10 to 150 or from 20 to 100, particularly preferably in a range of 30 to 80 m.
  • At least 70% by weight of the spray granules based on the total weight of the silica granules formed in the spray drying, have an average flight distance of more than 20 m, for example greater than 30 or greater than 50 or greater than 70 or more than 100 or more than 150 or more than 200 or in a range of 20 to 200 m or from 10 to 150 or from 20 to 100, particularly preferably in a range of 30 to 80 m.
  • At least 80% by weight of the spray granules based on the total weight of the silica granules formed in the spray drying, have an average flight distance of more than 20 m, for example greater than 30 or greater than 50 or greater than 70 or more than 100 or more than 150 or more than 200 or in a range of 20 to 200 m or from 10 to 150 or from 20 to 100, particularly preferably in a range of 30 to 80 m.
  • At least 90% by weight of the spray granules based on the total weight of the silica granules formed in the spray drying, have an average flight distance of more than 20 m, for example greater than 30 or greater than 50 or greater than 70 or more than 100 or more than 150 or more than 200 or in a range of 20 to 200 m or from 10 to 150 or from 20 to 100, particularly preferably in a range of 30 to 80 m.
  • a silica granule is obtained by roll granulating the slurry.
  • Roll granulation is done by stirring the slurry in the presence of a gas at elevated temperature.
  • Roll granulation preferably takes place in a stirred tank equipped with a stirring tool.
  • the stirring container rotates in the opposite direction to the stirring tool.
  • the stirring vessel further comprises an inlet through which silica powder can be introduced into the stirring vessel, an outlet through which silica granules can be removed, a gas inlet and a gas outlet.
  • a pinworm is understood to mean a stirrer tool which is provided with a plurality of elongate pins whose longitudinal axis runs in each case coaxially with the axis of rotation of the stirrer tool.
  • the movement sequence of the pins preferably describes coaxial circles about the axis of rotation.
  • the slurry is adjusted to a pH of less than 7, for example to a pH in the range of 2 to 6.5, more preferably to a pH in the range of 4 to 6.
  • a pH - Value is preferably an inorganic acid used, for example, an acid selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid and phosphoric acid, particularly preferably hydrochloric acid.
  • an atmosphere selected from air, an inert gas, at least two inert gases or a combination of air with at least one inert gas, preferably at least two inert gases.
  • inert gases are preferably selected from the list consisting of nitrogen, helium, neon, argon, krypton and xenon.
  • air, nitrogen or argon is present in the stirred tank, more preferably air.
  • the atmosphere present in the stirred tank is part of a gas stream.
  • the gas stream is preferably introduced into the stirred tank via the gas inlet and discharged via the gas outlet.
  • the gas stream can take up additional components in the stirred tank. These may originate from the slurry during roll granulation and pass into the gas stream.
  • the stirred tank is preferably supplied with a dry gas stream.
  • a "dry gas stream” is understood as meaning a gas or a gas mixture whose relative humidity is below the condensation point at the temperature set in the stirring vessel.
  • the gas is preferably at a temperature in a range from 50 to 300 ° C., for example from 80 to 250 ° C, more preferably preheated from 100 to 200 ° C.
  • 10 to 150 m 3 of gas per hour are preferably introduced per 1 kg of the slurry used into the stirred tank, for example 20 to 100 m 3 of gas per hour, more preferably 30 to 70 m 3 of gas per hour.
  • the gas stream dries the slurry while stirring to form silica granules.
  • the granules formed are removed from the stirred chamber.
  • the withdrawn granules are further dried.
  • the drying is carried out continuously, for example in a rotary kiln.
  • Preferred temperatures for drying are in a range of 80 to 250 ° C, for example in a range of 100 to 200 ° C, more preferably in a range of 120 to 180 ° C.
  • Continuously in the context of the present invention in relation to a method means that it can be operated continuously. This means that the supply and removal of substances and materials involved in the process can be carried out continuously during the execution of the process. It is not necessary to interrupt the procedure for this.
  • Continuously as an attribute of an object, e.g. with respect to a "continuous furnace", means that this article is designed so that a process occurring in it or in it process step can be carried out continuously.
  • the granules obtained by roll granulation can be screened.
  • Sieving can be done before or after drying. Preference is given to sieving before drying. Granules having a particle size of less than 50 ⁇ m, for example having a particle size of less than 80 ⁇ m, are particularly preferably screened out with a particle size of less than 100 ⁇ m. Preference is given to granules having a particle size of more than 900 ⁇ m, for example having a particle size of more than 700 ⁇ m, and more preferably having a particle size of more than 500 ⁇ m.
  • the sieving of larger particles can be carried out in principle by all methods known to the person skilled in the art and suitable for this purpose. The screening of larger particles preferably takes place by means of a vibrating trough.
  • roll granulation is characterized by at least one, for example two or three, most preferably all of the following features:
  • [b] granulation is carried out under a gas stream of 10 to 150 kg gas per hour and per 1 kg slurry;
  • Granules with a particle size of less than 100 ⁇ and more than 500 ⁇ are sieved;
  • the granules formed have a residual moisture of 15 to 30 wt .-%;
  • the granules formed are dried at 80 to 250 ° C, preferably in a continuous drying tube, more preferably up to a residual moisture content of less than 1 wt .-%.
  • this is obtained by granulation, preferably by spray or roll granulation
  • Silica granules also referred to as silica granules I
  • Silica granules are treated before being processed into quartz glass bodies. This pretreatment can serve a variety of purposes, including either processing Facilitate quartz glass bodies or affect the properties of the resulting quartz glass body.
  • the silica granules I may be compacted, cleaned, surface modified or dried.
  • the silica granules I may be subjected to a thermal, mechanical or chemical treatment or a combination of two or more treatments to obtain a silica granule II.
  • the silica granules I have a carbon content Wcpj.
  • the carbon content Wcpj is preferably less than 50 ppm, for example in the range of 5 to 45 ppm or of 15 to 40 ppm, particularly preferably in the range of 25 to 35 ppm, in each case based on the total weight of the silica granulate I.
  • the silica granule I comprises at least two particles.
  • the at least two particles can perform a relative movement to each other.
  • all measures known to the person skilled in the art and appearing suitable come into consideration as measures for generating the relative movement.
  • Particularly preferred is a mixing.
  • mixing can be carried out in any desired manner.
  • a continuous furnace is selected for this purpose.
  • the at least two particles can preferably perform a relative movement to each other by being moved in a continuous furnace, for example a rotary kiln.
  • Continuous ovens are understood to mean furnaces in which the loading and unloading of the furnace, the so-called charging, takes place continuously.
  • Examples of continuous furnaces are rotary kilns, roller kilns, conveyor ovens, drive-through ovens, push-through ovens.
  • rotary kilns are used to treat the silica granules I.
  • the silica granule I is treated with a reactant to obtain a silica granule II.
  • the treatment is carried out to change the concentration of certain substances in the silica granules.
  • the silica granules I may have impurities or certain functionalities whose content is to be reduced, such as: OH groups, carbon-containing compounds, transition metals, alkali metals and alkaline earth metals.
  • the impurities and functionalities may originate from the starting material or be added during the process.
  • the treatment of the silica granulate I can serve various purposes.
  • the use of treated silica granules I may facilitate the processing of the silica granules into quartz glass bodies.
  • the properties of the resulting quartz glass body can be adjusted.
  • the silica granules I can be purified or surface-modified.
  • the treatment of the silica granulate I can therefore be used to improve the properties of the resulting quartz glass body.
  • the reactants used are preferably a gas or a combination of several gases. This is also called gas mixture. In principle, it is possible to use all gases known to the person skilled in the art which are known and suitable for the said treatment.
  • the treatment is carried out in the presence of a gas or a combination of two or more as gases.
  • the treatment is carried out in a gas countercurrent, or in a gas direct current.
  • the reactant is selected from the group consisting of HCl, Cl 2 , F 2 , O 2 , O 3 or combinations of two or more thereof.
  • mixtures of two or more of the aforementioned gases are used to treat silica granules I.
  • metals contained as impurities in the silica granules I such as transition metals, alkali metals and alkaline earth metals can be removed.
  • the aforementioned metals with constituents of the gas mixture can undergo gaseous compounds under the process conditions, which are subsequently discharged and thus no longer present in the granules.
  • the OH content in the silica granules I can be reduced by treating the silica granules I with these gases.
  • a gas mixture of HCl and Cl 2 is used as the reactant.
  • the gas mixture has a content of HCl in a range from 1 to 30% by volume, for example in a range from 2 to 15% by volume, particularly preferably in a range from 3 to 10% by volume.
  • the gas mixture has a content of Cl 2 in a range of 20 to 70 vol .-%, for example in a range of 25 to 65 vol .-%, particularly preferably in a range of 30 to 60 vol .-%.
  • the remainder to 100% by volume may be supplemented by one or more inert gases, eg N 2 , He, Ne, Ar, Kr, or by air.
  • the proportion of inert gas in reactants is preferably in a range from 0 to less than 50% by volume, for example in a range from 1 to 40% by volume or from 5 to 30% by volume, more preferably in one range from 10 to 20% by volume, based in each case on the total volume of the reactant.
  • C 2 F 2 , or mixtures thereof with Cl 2 are preferably used for the purification of silica granules I, which was prepared from a siloxane or a mixture of several siloxanes.
  • the reactant in the form of a gas or gas mixture is preferably used as a gas stream or as part of a gas stream with a throughput in a range of 50 to 2000 L / h, for example in a range of 100 to 1000 L / h, more preferably in a range of 200 up to 500 L / h contacted with the silica granules.
  • a preferred embodiment of the contacting is a contact of gas flow and silica granules in a continuous furnace, for example a rotary kiln.
  • Another preferred embodiment of the contacting is a fluidized bed process.
  • a silica granule II having a carbon content Wcpj is obtained.
  • the carbon content Wcpj of the silica granules II is smaller than the carbon content w C ( i ) of the silica granules I based on the total weight of each Siliziumdioxidgranulats.
  • w c (2) is from 0.5 to 99%, for example from 0.5 to 50% or from 1 to 45%, more preferably from 1 to 5 to 40% less than w C (i).
  • the silica granule I is additionally subjected to a thermal or mechanical treatment or a combination of these treatments.
  • One or more of these additional treatments may be before or during the treatment with the reactant.
  • the additional treatment can also be carried out on the silica granules II.
  • the general term "silica granules" used below includes the alternatives “silica granules I” and “silicon dioxide granules II.” It is also possible to apply the treatments described below to both the "silicon dioxide granules I" and the treated silicon dioxide granules I, the "silicon dioxide granules II". to perform.
  • the treatment of the silica granules can serve a variety of purposes. For example, this treatment facilitates the processing of the silica granules into quartz glass bodies.
  • the treatment may also affect the properties of the resulting silica glass body.
  • the silica granules may be compacted, cleaned, surface modified or dried.
  • the specific surface area (BET) may decrease.
  • bulk density and average particle size may increase due to agglomeration of silica particles.
  • the thermal treatment can be carried out dynamically or statically.
  • all furnaces are suitable for the dynamic thermal treatment, in which the silicon dioxide granules can be thermally treated and thereby moved.
  • the dynamic thermal treatment preferably continuous furnaces are used.
  • a preferred average residence time of the silica granules in the dynamic thermal treatment is quantity dependent.
  • the average residence time of the silica granules in the dynamic thermal treatment is preferably in the range from 10 to 180 minutes, for example in the range from 20 to 120 minutes or from 30 to 90 minutes.
  • the average residence time of the silica granules in the dynamic thermal treatment in the range of 30 to 90 min.
  • a defined portion of a stream of silica granules e.g. a gram, a kilogram or a ton. Beginning and end of the stay are determined here by running in and out of the continuous furnace operation.
  • the throughput of the silica granules in a continuous process for dynamic thermal treatment is in the range of 1 to 50 kg / h, for example in the range of 5 to 40 kg / h or 8 to 30 kg / h. Particularly preferred is the throughput in the range of 10 to 20 kg / h.
  • the treatment time results from the period between a loading and subsequent unloading of the furnace.
  • the throughput is in a range of 1 to 50 kg / h, for example in the range of 5 to 40 kg / h or 8 to 30 kg / h.
  • the throughput is particularly preferably in the range from 10 to 20 kg / h.
  • the throughput can be achieved by a batch of a certain amount treated for one hour.
  • the throughput may be achieved by a number of batches per hour, for example, the amount of a batch corresponding to the throughput per hour by the number of batches.
  • the treatment time then corresponds to the fraction of an hour, which results from 60 minutes by the number of batches per hour.
  • the dynamic thermal treatment of the silica granules preferably takes place at an oven temperature of at least 500 ° C., for example in the range from 510 to 1700 ° C. or from 550 to 1500 ° C. or from 580 to 1300 ° C., particularly preferably in the range from 600 to 1200 ° C.
  • the oven in the oven chamber has the specified temperature.
  • this temperature deviates upwards or downwards from the indicated temperature by less than 10%, based on the total treatment time and the entire length of the furnace, both at each time of treatment and at each point of the furnace.
  • the continuous process of a dynamic thermal treatment of the silica granules can be carried out at different furnace temperatures.
  • the oven may have a constant temperature over the treatment time, with the temperature varying in sections over the length of the oven. Such sections can be the same length or different lengths.
  • a temperature which increases from the inlet of the furnace to the outlet of the furnace is preferred.
  • the temperature at the inlet is at least 100 ° C lower than at the outlet, for example 150 ° C lower or 200 ° C lower or 300 ° C lower or 400 ° C lower. More preferably, the temperature at the exit is preferably at least 500 ° C., for example in the range from 510 to 1700 ° C.
  • the temperature at the inlet is preferably at least 300 ° C, for example from 400 to 1000 ° C or from 450 to 900 ° C or from 500 to 800 ° C or from 550 to 750 ° C, more preferably from 600 to 700 ° C.
  • each of the mentioned temperature ranges at the furnace inlet can be combined with each of the temperature ranges at the furnace outlet. Preferred combinations of furnace inlet and furnace outlet temperature ranges are:
  • crucibles preferably are used in an oven.
  • Crucibles or tin crucibles are suitable as crucibles.
  • Preferred are Rolled sheet crucible made of several, riveted plates.
  • refractory metals are refractory metals, in particular tungsten, molybdenum and tantalum.
  • the crucibles may also be formed from graphite or, in the case of crucibles of refractory metals, be lined with graphite foil. More preferably, the crucibles may be formed of silicon dioxide. Particular preference is given to using silicon dioxide crucibles.
  • the average residence time of the silica granules in the static thermal treatment is quantity-dependent.
  • the average residence time of the silica granules in the static thermal treatment at an amount of 20 kg of silica granules I in the range of 10 to 180 minutes, for example in the range of 20 to 120 minutes, more preferably in the range of 30 to 90 min.
  • the static thermal treatment of the silica granules is carried out at an oven temperature of at least 800 ° C, for example in the range of 900 to 1700 ° C or 950 to 1600 ° C or 1000 to 1500 ° C or 1050 to 1400 ° C, especially preferably in the range of 1100 to 1300 ° C.
  • the static thermal treatment of the silicon dioxide granules I preferably takes place at a constant oven temperature.
  • the static thermal treatment can also be carried out at a varying oven temperature.
  • the temperature increases in the course of the treatment, wherein the temperature at the beginning of the treatment by at least 50 ° C is lower than at the end, for example 70 ° C lower or 80 ° C lower or 100 ° C lower or 110 ° C lower, and wherein the temperature at the end is preferably at least 800 ° C, for example in the range of 900 to 1700 ° C or 950 to 1600 ° C or 1000 to 1500 ° C or 1050 to 1400 ° C, more preferably in Range from 1100 to 1300 ° C. mechanically
  • the silicon dioxide granulate I can be treated mechanically.
  • the mechanical treatment can be carried out to increase the bulk density.
  • the mechanical treatment can be combined with the thermal treatment described above.
  • By means of a mechanical treatment it can be avoided that the agglomerates in the silica granulate and thus the average particle size of the individual, treated silica granules in the silicon dioxide granules become too large. An enlargement of the agglomerates can complicate the further processing or have adverse effects on the properties of the quartz glass body produced by the method according to the invention, or a combination of the two effects.
  • Mechanical treatment of the silica granules also promotes uniform contact of the surfaces of the individual silica granules with the gas or gases. This is achieved in particular with a combination of simultaneous mechanical and chemical treatment with one or more gases. Thereby, the effect of the chemical treatment can be improved.
  • the mechanical treatment of the silica granules may be accomplished by moving two or more silica granules in relative motion, for example, by rotating the tube of a rotary kiln.
  • the silicon dioxide granulate I is preferably treated chemically, thermally and mechanically.
  • a simultaneous chemical, thermal and mechanical treatment of the silica granules I may be accomplished by moving two or more silica granules in relative motion, for example, by rotating the tube of a rotary kiln.
  • the silica granules I can be treated in a rotary kiln at elevated temperature under a chlorine- and oxygen-containing atmosphere. Water present in silica granules I evaporates, organic materials react to CO and CO 2 . Metal contaminants can be converted to volatile, chlorine-containing compounds.
  • the chlorine-containing atmosphere contains, for example, HCl or CI 2 or a combination of both. This treatment causes a reduction of the carbon content.
  • alkali and iron impurities are preferably reduced.
  • a reduction in the number of OH groups is preferably achieved. At temperatures below 700 ° C, long treatment times may result, at temperatures above 1100 ° C there is a risk that close pores of the granules, including chlorine or gaseous chlorine compounds.
  • the silicon dioxide granules I can be treated first in a chlorine-containing atmosphere and then in an oxygen-containing atmosphere.
  • the resulting low concentrations of carbon, hydroxyl groups and chlorine facilitate the melting of the silica granules II.
  • step II.2) is characterized by at least one, for example by at least two or at least three, more preferably by a combination of all of the following features:
  • the reactant includes HCl, CI 2 or a combination thereof;
  • the treatment is carried out at a temperature in a range of 600 to 900 ° C; N4) the reactant forms a countercurrent;
  • the reactant has a gas flow in a range of 50 to 2000 L / h, preferably 100 to 1000
  • L / h more preferably 200 to 500 L / h;
  • the reactant has a volume fraction of inert gas in a range of 0 to less than 50
  • the silica granules I have a particle diameter which is larger than that
  • Particle diameter of the silica powder Preferably, the particle diameter of the silica powder.
  • Silica granules I up to 300 times larger than the particle diameter of the silica powder, for Example up to 250 times larger or up to 200 times larger or up to 150 times larger or up to 100 times larger or up to 50 times larger or up to 20 times larger or up to 10 times larger, more preferably 2 to 5 times larger ,
  • silica granules thus obtained are also referred to as silica granules II. More preferably, the silica granules II are obtained from the silica granules I in a rotary kiln by means of a combination of thermal, mechanical and chemical treatment.
  • the silica granulate provided in step i.) Is preferably selected from the group consisting of silica granules I, silica granules II and a combination thereof.
  • silicon dioxide granules I granules of silicon dioxide which are produced by granulation of silicon dioxide powder which was obtained in the pyrolysis of silicon compounds in a fuel gas flame.
  • Silicon granules II is understood as meaning a granulate of silicon dioxide which is formed by post-treatment of the silicon dioxide granulate I. As after-treatment, chemical, thermal and / or mechanical treatments are contemplated first object of the invention).
  • the silicon dioxide granulate I provided in step i.) Is particularly preferably the silicon dioxide granulate I.
  • the silicon dioxide granule I has the following features:
  • a BET surface area in the range of 20 to 50 m 2 / g for example in a range of 20 to 40 m 2 / g; more preferably in a range of 25 to 35 m 2 / g;
  • the microporous fraction preferably amounts to a BET surface area in the range from 4 to 5 m 2 / g; for example, in a range of 4.1 to 4.9 m 2 / g; more preferably in a range of 4.2 to 4.8 m 2 / g; and
  • [B] an average particle size in a range of 180 to 300 ⁇ .
  • the silicon dioxide granulate I is preferably characterized by at least one, for example by at least two or at least three or at least four, more preferably by at least five of the following features:
  • [C] has a bulk density in a range of 0.5 to 1.2 g / cm 3 , for example, in a range of 0.6 to 1.1 g / cm 3 , more preferably in a range of 0.7 to 1 , 0 g / cm 3 ;
  • [E] has an aluminum content of less than 200 ppb, preferably less than 100 ppb, for example less than 50 ppb or from 1 to 200 ppb or from 15 to 100 ppb, more preferably in a range from 1 to 50 ppb.
  • [F] a tamped density in a range of 0.5 to 1.2 g / cm 3 , for example in a range of
  • [G] a pore volume in a range of 0.1 to 1.5 mL / g, for example in a range of
  • a chlorine content of less than 200 ppm preferably less than 150 ppm, for example less than 100 ppm, or less than 50 ppm, or less than 1 ppm, or less than 500 ppb, or less than 200 ppb, or in a range of 1 ppb to less than 200 ppm, or from 1 ppb to 100 ppm, or from 1 ppb to 1 ppm, or from 10 ppb up to 500 ppb, or from 10 ppb to 200 ppb, more preferably from 1 ppb to 80 ppb;
  • Metal content of metals other than aluminum preferably less than 1,000, in a range of 1 to 900 ppb, for example, in a range of 1,700 ppb, more preferably in a range of 1 to 500 ppb;
  • a residual moisture of less than 10 wt .-% preferably in a range of 0.01 wt .-% to 5 wt .-%, for example from 0.02 to 1 wt .-%, particularly preferably from 0.03 to 0.5% by weight; wherein the wt .-%, ppm and ppb are each based on the total weight of the silica granules I.
  • the OH content also hydroxy group content, is understood as meaning the content of OH groups in a material, for example in silica powder, in granules of silicon dioxide or in a quartz glass body.
  • the content of OH groups is determined spectroscopically after in the infrared by comparing the first and the third OH band.
  • the chlorine content is understood as meaning the content of elemental chlorine or chloride ions in the silicon dioxide granules, the silica powder or the quartz glass body.
  • the aluminum content is understood as meaning the content of elemental aluminum or aluminum ions in the silicon dioxide granules, the silicon dioxide powder or the quartz glass body.
  • the silica granule I has a microporous fraction in a range of 4 to 5 m 2 / g; for example, in a range of 4.1 to 4.9 m 2 / g; more preferably in a range of 4.2 to 4.8 m 2 / g.
  • the silicon dioxide granulate I preferably has a density in a range from 2.1 to 2.3 g / cm 3 , particularly preferably in a range from 2.18 to 2.22 g / cm 3 .
  • the Sihziumdioxidgranulat I preferably has an average particle size in a range of 180 to 300 ⁇ , for example in a range of 220 to 280 ⁇ , more preferably in a range of 230 to 270 ⁇ on.
  • the Sihziumdioxidgranulat I preferably has a particle size D 50 in a range of 150 to 300 ⁇ , for example in a range of 200 to 280 ⁇ , more preferably in a range of 230 to 270 ⁇ . Further preferably, the Sihziumdioxidgranulat I has a particle size D 10 in a range of 50 to 150th ⁇ , for example in a range of 100 to 150 ⁇ , more preferably in a range of 120 to 150 ⁇ on. Further preferably, the silica granules I a particle size D 90 in a range of 250 to 620 ⁇ , for example in a range of 300 to 550 ⁇ , more preferably in a range of 300 to 450 ⁇ on.
  • the silica granulate I preferably has the combination of features [A] / [B] / [C] or [A] / [B] / [E] or [A] / [B] / [G], more preferably the combination of features [A ] / [B] / [C] / [E] or [A] / [B] / [C] / [G] or [A] / [B] / [E] / [G], particularly preferably the combination of features [A] / [B] / [C] / [e] / [G].
  • the silica granulate I preferably has the combination of features [A] / [B] / [C], wherein the BET surface area in a range of 20 to 40 m 2 / g, the average particle size in a range of 180 to 300 ⁇ and the Bulk density is in a range of 0.6 to 1.1 g / mL.
  • the silica granulate I preferably has the combination of features [A] / [B] / [E], wherein the BET surface area in a range of 20 to 40 m 2 / g, the average particle size in a range of 180 to 300 ⁇ and the Aluminum content is in a range of 1 to 50 ppb.
  • the silica granulate I preferably has the combination of features [A] / [B] / [G], wherein the BET surface area in a range of 20 to 40 m 2 / g, the average particle size in a range of 180 to 300 ⁇ and the Pore volume is in a range of 0.2 to 0.8 mL / g.
  • the silica granulate I preferably has the combination of features [A] / [B] / [C] / [E], wherein the BET surface area in a range of 20 to 40 m 2 / g, the average particle size in a range of 180 to 300 ⁇ , the bulk density in a range of 0.6 to 1.1 g / mL and the aluminum content in a range of 1 to 50 ppb.
  • the silica granulate I preferably has the combination of features [A] / [B] / [C] / [G], wherein the BET surface area in a range of 20 to 40 m 2 / g, the average particle size in a range of 180 to 300 ⁇ , the bulk density in a range of 0.6 to 1.1 g / mL and the pore volume in a range of 0.2 to 0.8 mL / g.
  • the silica granulate I preferably has the combination of features [A] / [B] / [E] / [G], wherein the BET surface area in a range of 20 to 40 m 2 / g, the average particle size in a range of 180 to 300 ⁇ , the aluminum content in a range of 1 to 50 ppb and the pore volume in a range of 0.2 to 0.8 mL / g.
  • the silica granulate I preferably has the combination of features [A] / [B] / [C] / [E] / [G], wherein the BET surface area in a range of 20 to 40 m 2 / g, the average particle size in a Range from 180 to 300 ⁇ , the bulk density in a range of 0.6 to 1.1 g / mL, the aluminum content in a range of 1 to 50 ppb and the pore volume in a range of 0.2 to 0.8 mL / g is.
  • Particle size is understood to be the size of the particles composed of the primary particles which are present in a silica powder, in a slurry or in a silica granulate.
  • the mean particle size is understood as meaning the arithmetic mean of all particle sizes of said substance.
  • the D 50 value indicates that 50% of the particles, based on the total number of particles, are smaller than the specified value.
  • the D 10 value indicates that 10% of the particles, based on the total number of particles, are smaller than the specified value.
  • the D 90 value indicates that 90% of the particles, based on the total number of particles, are smaller than the specified value.
  • the particle size is determined by dynamic image analysis method according to ISO 13322-2: 2006-11.
  • the silicon dioxide granules provided in step i.) are the silicon dioxide granules II.
  • the silicon dioxide granules II have the following features:
  • the silicon dioxide granules II preferably have at least one, for example at least two or at least three or at least four, more preferably at least five of the following characteristics:
  • (C) a bulk density in a range of 0.7 to 1.2 g / cm 3 , for example, in a range of 0.75 to 1.1 g / cm 3 , particularly preferably in a range of 0.8 to 1 , 0 g / cm 3 ;
  • (G) a pore volume in a range of 0.1 to 2.5 mL / g, for example, in a range of 0.2 to 1.5 mL / g; more preferably in a range of 0.4 to 1 mL / g;
  • (H) a chlorine content of less than 500 ppm, preferably less than 400 ppm, for example less than 350 ppm or preferably less than 330 ppm or in a range from 1 ppb to 500 ppm or from 10 ppb to 450 ppm particularly preferred from 50 ppb to 300 ppm;
  • the silica granule II has a microporous fraction in a range of 1 to 2 m 2 / g, for example in a range of 1.2 to 1.9 m 2 / g, particularly preferably in a range of 1.3 to 1.8 m 2 / g on.
  • the silica granule II preferably has a density in a range from 0.5 to 2.0 g / cm 3 , for example from 0.6 to 1.5 g / cm 3 , particularly preferably from 0.8 to 1.2 g / cm 3 up. The density is determined according to the method described in the test methods.
  • the silica granules II preferably has a particle size D 50 in a range of 150 to 300 ⁇ , for example in a range of 200 to 280 ⁇ , more preferably in a range of 230 to 270 ⁇ . Further preferably, the silica granules II has a particle size D 10 in a range of 50 to 150 ⁇ , for example in a range of 100 to 150 ⁇ , more preferably in a range of 120 to 150 ⁇ on. Further preferably, the granular silica II has a particle size D 90 in a range of 250 to 620 ⁇ , for example in a range of 300 to 550 ⁇ , more preferably in a range of 300 to 450 ⁇ on.
  • the silica granule II preferably has the feature combination (A) / (B) / (D) or (A) / (B) / (F) or (A) / (B) / (I), more preferably the combination of features (A ) / (B) / (D) / (F) or (A) / (B) / (D) / (I) or (A) / (B) / (F) / (I), particularly preferably the combination of features (A) / (B) / (D) / (F) / (I).
  • the silica granule II preferably has the feature combination (A) / (B) / (D), wherein the BET surface area is in a range of 10 to 30 m 2 / g, the mean particle size is in a range of 150 to 280 ⁇ and the carbon content is less than 4 ppm.
  • the silica granules II preferably has the combination of features (A) / (B) / (F), wherein the BET surface area in a range of 10 to 30 m 2 / g, the average particle size in a range of 150 to 280 ⁇ and the Tamping density is in a range of 0.8 to 1.0 g / mL.
  • the silica granules II preferably has the combination of features (A) / (B) / (I), wherein the BET surface area in a range of 10 to 30 m 2 / g, the average particle size in a range of 150 to 280 ⁇ and the Metal content of metals other than aluminum in a range of 1 to 400 ppb.
  • the silica granule II preferably has the feature combination (A) / (B) / (D) / (F), wherein the BET surface area is in a range of 10 to 30 m 2 / g, the average particle size in a range of 150 to 280 ⁇ , the carbon content is less than 4 ppm and the tamped density is in a range of 0.8 to 1.0 g / mL.
  • the silica granule II preferably has the feature combination (A) / (B) / (D) / (I), wherein the BET surface area is in a range of 10 to 30 m 2 / g, the average particle size in a range of 150 to 280 ⁇ , the carbon content is less than 4 ppm and the metal content of metals other than aluminum in a range of 1 to 400 ppb.
  • the silica granule II preferably has the feature combination (A) / (B) / (F) / (I), wherein the BET surface area in a range of 10 to 30 m 2 / g, the average particle size in a range of 150 to 280 ⁇ , the tamped density in a range of 0.8 to 1.0 g / mL and the metal content of metals other than aluminum, in a range of 1 to 400 ppb.
  • the silica granule II preferably has the feature combination (A) / (B) / (D) / (F) / (I), wherein the BET surface area is in a range of 10 to 30 m 2 / g, the average particle size in is a range of 150 to 280 ⁇ m, the carbon content is less than 4 ppm, the tamped density is in a range of 0.8 to 1.0 g / ml, and the metal content of metals other than aluminum is in a range of 1 to 400 ppb.
  • step ii. A glass melt is formed from the silica granules.
  • the silica granules are heated until a glass melt is obtained.
  • the heating of the silicon dioxide granules to a molten glass can in principle be carried out in any way known to the person skilled in the art for this purpose.
  • the formation of a glass melt from the silica granules can be carried out by a continuous process.
  • the silicon dioxide granules may preferably be introduced continuously into an oven or the glass melt may be removed continuously from the oven, or both. More preferably, the silica granules are continuously introduced into the furnace and the molten glass continuously removed from the furnace.
  • a furnace which has at least one inlet and at least one outlet.
  • An inlet means an opening through which silicon dioxide and optionally further substances can be introduced into the furnace.
  • An outlet means an opening through which at least part of the silicon dioxide can be removed from the oven.
  • the oven may be vertically and horizontally aligned.
  • the oven is vertically aligned.
  • at least one inlet is located above at least one outlet.
  • "Above" in connection with internals and features of a furnace, in particular an inlet and outlet means that the fixture or feature located "above” another occupies a higher position NormalNull (NN).
  • the furnace includes a hanging metal sheet
  • Sheet metal crucible is the silicon dioxide granules registered and under Receiving a molten glass heated.
  • a sheet metal crucible is understood to mean a crucible which contains at least one rolled sheet.
  • a sheet metal crucible preferably has a plurality of rolled sheets.
  • Under a hanging metal sheet is understood to mean a metal sheet of the type described above, which is arranged hanging in a furnace.
  • the hanging metal sheet can in principle consist of all materials known to those skilled in the art and suitable for melting silicon dioxide.
  • the sheet metal of the hanging sheet metal crucible includes a sintered material, for example, a sintered metal.
  • sintered metals is meant metals or alloys obtained by sintering metal powders.
  • the sheet metal of the sheet metal crucible preferably contains at least one element selected from the group consisting of refractory metals.
  • Refractory metals are the metals of the 4th subgroup (Ti, Zr, Hf), the 5th subgroup (V, Nb, Ta) and the 6th subgroup (Cr, Mo, W).
  • the sheet metal of the sheet metal crucible preferably contains a sintered metal selected from the group consisting of molybdenum, tungsten or a combination thereof. More preferably, the sheet metal of the sheet crucible contains at least one further refractory metal, particularly preferably rhenium, osmium, iridium, ruthenium or a combination of two or more thereof.
  • the sheet metal of the sheet metal crucible preferably contains an alloy of molybdenum with a refractory metal, or tungsten with a refractory metal.
  • Particularly preferred alloying metals are rhenium, osmium, iridium, ruthenium or a combination of two or more thereof.
  • the sheet metal of the sheet crucible is an alloy of molybdenum with tungsten, rhenium, osmium, iridium, ruthenium or a combination of two or more thereof.
  • the sheet metal of the sheet crucible is an alloy of tungsten with molybdenum, rhenium, osmium, iridium, ruthenium or a combination of two or more thereof.
  • the sheet metal of the sheet metal crucible described above may be coated with a refractory metal.
  • the sheet metal of the sheet crucible is coated with rhenium, osmium, iridium, ruthenium, molybdenum or tungsten, or a combination of two or more thereof.
  • the sheet and the coating have various compositions.
  • a molybdenum sheet is coated with one or more layers of rhenium, osmium, iridium, ruthenium, tungsten, or any combination of two or more thereof.
  • a tungsten sheet is coated with one or more layers of rhenium, osmium, iridium, ruthenium, molybdenum, or any combination of two or more thereof.
  • the sheet metal of the sheet metal crucible may be rhenium alloyed molybdenum or rhenium alloyed tungsten, and may be coated on the crucible inner side with one or more layers including rhenium, osmium, iridium, ruthenium, or any combination of two or more thereof.
  • the sheet of the hanging plate crucible has a density of 95% or more of the theoretical density, for example, a density of 95% to 98% or of 96% to 98%. Further preferred are higher theoretical densities, in particular in the range of 98 to 99.95%.
  • the theoretical density of a material corresponds to the density of a nonporous and 100% dense material.
  • a density of the sheet metal sheet of more than 95% of the theoretical density can be obtained, for example, by sintering a sintered metal and then compacting the sintered material. More preferably, a metal sheet is obtainable by sintering a sintered metal, rolling to obtain a sheet, and processing the sheet into a crucible.
  • the hanging metal sheet has at least one, for example at least two or at least three or at least four, more preferably at least five or all of the following features:
  • At least one sheet e.g. at least three or at least four or at least six or at least eight or at least twelve or at least 15 or at least 16 or at least 20 sheets, more preferably twelve or 16 sheets;
  • At least one compound of two sheet pieces e.g. at least two or at least five or at least ten or at least 18 or at least 24 or at least 36 or at least 48 or at least 60 or at least 72 or at least 48 or at least 96 or at least 120 or at least 160, more preferably 36 or 48 compounds of two or more various sheet metal pieces of the hanging plate crucible;
  • the sheet metal pieces of the hanging sheet metal crucible are riveted, e.g. on at least one compound, by deep drawing, e.g. by a combination of deep drawing with sheet tapping, or by sinking, bolting or welding, e.g. by electron beam welding and United of the welds, particularly preferably riveted;
  • the metal sheet of the hanging sheet metal crucible is obtainable by a forming step associated with an increase in physical density, preferably by forming a sintered metal or a sintered alloy; more preferably, the forming is a rolling;
  • a suspension of copper, aluminum, steel, iron, nickel or a refractory metal e.g. from the crucible material, preferably a water-cooled suspension made of copper or steel;
  • a mandrel for example a mandrel fixed to the nozzle by means of webs or a mandrel fastened to the cover by means of a holding rod or a mandrel connected to a holding rod from underneath the crucible;
  • At least one gas inlet e.g. in the form of a filling tube or as a separate inlet
  • external insulation preferably outer zirconia insulation.
  • the hanging metal sheet can in principle be familiar to any person skilled in the art and suitable for this purpose
  • the hanging sheet metal can, for example, by means of electrical heating elements (resistive) or heated by induction.
  • resistive heating the solid surface of the sheet metal crucible is heated from the outside and releases the energy from there to the inside.
  • the energy input into the metal sheet is not effected by heating the sheet metal crucible, or a melt material therein, or both, by means of a flame, such as a burner flame directed into the sheet metal crucible or plate.
  • the hanging metal sheet can be moved in the oven.
  • the crucible can be at least partially moved in and out of the furnace. If different heating zones are present in the oven, their temperature profiles are transferred to the crucible located in the oven. By changing the position of the crucible in the oven so several heating zones, varying heating zones or more varying heating zones can be realized in the crucible.
  • the metal plate has a nozzle.
  • the nozzle is formed of a nozzle material.
  • the nozzle material preferably comprises a precompressed material, for example with a density in a range of more than 95%, for example from 98 to 100%, particularly preferably from 99 to 99.999%, in each case based on the theoretical density of the nozzle material.
  • the nozzle material includes a refractory metal, for example, molybdenum, tungsten, or a combination thereof with another refractory metal.
  • a refractory metal for example, molybdenum, tungsten, or a combination thereof with another refractory metal.
  • Particularly preferred nozzle material is molybdenum.
  • a nozzle containing molybdenum may have a density of 100% of the theoretical density.
  • the bottom plate contained in a metal sheet is thicker than the sides of the sheet metal crucible.
  • the bottom plate of the sheet metal crucible is not a rolled sheet.
  • the bottom plate is, for example, 1.1 to 5000 times thicker or 2 to 1000 times thicker or 4 to 500 times thicker, more preferably 5 to 50 times thicker, each with respect to a wall of the plate crucible.
  • the furnace includes a hanging or a standing sintered crucible.
  • the silica granules are introduced and heated to obtain a glass melt.
  • a sintered crucible is understood to mean a crucible made of a sintered material containing at least one sintered metal and having a density of not more than 96% of the theoretical density of the metal.
  • sintered metals is meant metals or alloys obtained by sintering metal powders.
  • the sintered material of the sintered crucible preferably has a density of 85% or more of the theoretical density of the sintered material, for example a density of 85% to 95% or of 90% to 94%, particularly preferably of 91% to 93%.
  • the sintered material can consist of all materials known to those skilled in the art and suitable for melting silicon dioxide.
  • the sintered material is made of at least one of the elements selected from the group consisting of refractory metals, graphite or lined with graphite foil materials.
  • the sintered material includes a first sintered metal selected from the group consisting of molybdenum, tungsten and a combination thereof. More preferably, the sintered material further includes at least one other refractory metal other than the first sintered metal, more preferably selected from the group consisting of molybdenum, tungsten, rhenium, osmium, iridium, ruthenium, or a combination of two or more thereof.
  • the sintered material includes an alloy of molybdenum with a refractory metal, or tungsten with a refractory metal.
  • the alloying metal are rhenium, osmium, iridium, ruthenium or a combination of two or more thereof.
  • the sintered material includes an alloy of molybdenum with tungsten, rhenium, osmium, iridium, ruthenium, or a combination of two or more thereof.
  • the sintered material includes an alloy of tungsten with molybdenum, rhenium, osmium, iridium, ruthenium or a combination of two or more thereof.
  • the above-described sintered material may include a coating containing a refractory metal, in particular rhenium, osmium, iridium, ruthenium or a combination of two or more thereof.
  • the coating contains rhenium, osmium, iridium, ruthenium, molybdenum or tungsten, or a combination of two or more thereof.
  • the sintered material and its coating have various compositions.
  • a sintered material including molybdenum is coated with one or more layers of rhenium, osmium, iridium, ruthenium, tungsten, or each a combination of two or more thereof.
  • a sintered material including tungsten is coated with one or more layers of rhenium, osmium, iridium, ruthenium, molybdenum, or any combination of two or more thereof.
  • the sintered material may be rhenium alloyed molybdenum or rhenium alloyed tungsten, and may be coated on the inside of the crucible with one or more layers including rhenium, osmium, iridium, ruthenium or any combination of two or more thereof.
  • a sintered crucible is made by sintering the sintered material in a mold. The sintered crucible can be made as a whole in one mold.
  • the crucible is made of more than one part, for example, a bottom plate and one or more side parts.
  • the side parts are preferably manufactured in one piece based on the circumference of the crucible.
  • the sintered crucible can be manufactured from a plurality of side parts arranged one above the other. The side parts of the
  • Sealing crucible by screwing or sealed by a tongue and groove joint.
  • a screwing done preferably by manufacturing side parts which have a thread at the edges.
  • two side parts to be joined each have a groove at the edges, into which a spring is inserted as a connecting third part, so that a positive connection is formed perpendicular to the crucible wall plane.
  • a sintered crucible is produced from more than one side part, for example from two or more side parts, particularly preferably from three or more side parts.
  • the parts of the hanging sintered crucible are screwed.
  • the parts of the stationary sinter crucible are connected by means of a tongue and groove connection.
  • the bottom plate can in principle be connected to the crucible wall by all measures known to the person skilled in the art and suitable for this purpose.
  • the bottom plate is provided with an external thread and is connected by screwing the bottom plate in the crucible wall with this.
  • the bottom plate is connected by means of screws with the crucible wall.
  • the bottom plate is suspended in the sintered crucible, for example by inserting the bottom plate on an inner collar of the crucible wall.
  • at least a part of the crucible wall and a thickened bottom plate are sintered in one piece.
  • the bottom plate and the crucible wall of the hanging sintered crucible are screwed.
  • the bottom plate and the crucible wall of the stationary sinter crucible are connected by means of a tongue and groove connection.
  • the bottom plate contained in a sintered crucible is thicker than the sides, for example 1.1 to 20 times thicker or 1.2 to 10 times thicker or 1.5 to 7 times thicker, more preferably 2 to 5 times thicker.
  • the sides preferably have a constant wall thickness over the circumference and over the height of the sintered crucible.
  • the sinter crucible has a nozzle.
  • the nozzle is formed of a nozzle material.
  • the nozzle material preferably comprises a precompressed material, for example with a density in a range of more than 95%, for example from 98 to 100%, particularly preferably from 99 to 99.999%, in each case based on the theoretical density of the nozzle material.
  • the nozzle material includes a refractory metal, for example, molybdenum, tungsten, or a combination thereof with a refractory metal.
  • Particularly preferred nozzle material is molybdenum.
  • a nozzle containing molybdenum may have a density of 100% of the theoretical density.
  • the hanging sintered crucible can in principle be heated in any manner familiar to the person skilled in the art and appear suitable for this purpose.
  • the hanging sintered crucible can be heated, for example, inductively or resistively.
  • inductive heating the energy is coupled directly by means of coils in the side wall of the sinter crucible and discharged from there to the inside of the crucible.
  • resistive heating the energy is coupled by radiation, the solid surface is heated from the outside and the energy is discharged from there to the inside.
  • the sintered crucible is preferably heated inductively.
  • the energy input into the sintered crucible is not effected by heating the sinter crucible, or a melt material therein, or both, by means of a flame, such as a burner flame directed into the sintering crucible or sintered crucible.
  • the sintered crucible has one or more than one heating zone, for example one or two or three or more than three heating zones, preferably one or two or three heating zones, particularly preferably a heating zone.
  • the heating zones of the sinter crucible can be brought to the same or different temperatures.
  • all heating zones may be heated to one temperature or all heating zones to different temperatures, or two or more heating zones to one and one or more heating zones independently of one another to different temperatures.
  • all heating zones are brought to different temperatures, for example, the temperature of the heating zones increases in the direction of material transport of the silica granules.
  • a hanging sintered crucible is understood to mean a sinter crucible of the type described above, which is suspended in a furnace.
  • the hanging sintered crucible has at least one, for example at least two or at least three or at least four, particularly preferably all of the following features:
  • ⁇ a ⁇ a suspension preferably a height-adjustable suspension
  • ⁇ b ⁇ at least two sealed rings as side parts, preferably at least two rings screwed together as side parts;
  • a mandrel for example a mandrel fixed to the nozzle by means of webs or a mandrel fastened to the cover by means of a support rod or a mandrel connected to a support rod from below the crucible;
  • At least one gas inlet e.g. in the form of a filling tube or as a separate inlet, particularly preferably in the form of a filling tube;
  • ⁇ f ⁇ at least one gas outlet, e.g. on the lid or in the wall of the crucible,
  • a cooled jacket more preferably a water-cooled jacket
  • an insulation on the outside of the crucible for example on the outside of the cooled shell, preferably an insulating layer of zirconium oxide.
  • a suspension is a suspension mounted in the production of the hanging sintered crucible, for example a suspension provided as an integral part of the crucible, more preferably a suspension of the sintered material provided as an integral part of the crucible.
  • a suspension attached to the sintered crucible of a material other than the sintered material for example, aluminum, steel, iron, nickel or copper, preferably copper, more preferably a cooled one, for example a water-cooled, attached to the sinter crucible Suspension made of copper. Due to the hanging arrangement, the hanging sintered crucible can be moved in the oven.
  • the hanging sintered crucible can be moved in the oven.
  • the hanging sintered crucible can be moved in the oven.
  • the hanging sintered crucible can be moved in the oven.
  • a standing sintered crucible is understood to mean a sinter crucible of the type described above, which is arranged standing in an oven.
  • the standing sintered crucible has at least one, for example at least two or at least three or at least four, particularly preferably all of the following features:
  • ßol at least two sealed rings as side parts, preferably at least two sealed by a tongue and groove joint rings as side parts;
  • nozzle preferably a nozzle fixedly connected to the crucible, more preferably a portion of the bottom of the crucible not formed as a standing surface;
  • Idl a mandrel, for example, a mandrel fixed to the nozzle with bars or a pin secured to webs on the lid or a mandrel connected from below the crucible with a holding rod;
  • Id at least one gas inlet, e.g. in the form of a filling tube or as a separate inlet;
  • Iii at least one gas outlet, e.g. as a separate outlet on the lid or in the wall of the crucible;
  • the standing sintered crucible preferably has a separation of the gas spaces in the furnace and in the area below the furnace. Under the area below the furnace, the area below the nozzle is understood, in which the withdrawn molten glass is located.
  • the gas spaces are preferably separated by the area on which the crucible stands. Gas, which is located in the gas space of the furnace between the furnace inner wall and the outer wall of the crucible, can not escape down into the area below the furnace.
  • the extracted molten glass has no contact with the gases from the gas space of the furnace.
  • glass melts taken from a furnace with a vertically arranged sintered crucible and quartz glass bodies formed therefrom have a higher surface purity than glass melts taken from a furnace with a sintered crucible arranged in a suspended position and quartz glass bodies formed therefrom.
  • the crucible is connected to the inlet and the outlet of the furnace such that silica granules can pass into the crucible through the inlet of the furnace via the inlet of the crucible and glass melt can be withdrawn through the outlet of the crucible and the outlet of the furnace.
  • the crucible adjacent to the at least one inlet at least one opening, preferably a plurality of openings through which gas can be introduced and discharged.
  • the crucible comprises at least two openings, at least one being used as gas inlet and at least one as gas outlet can. The use of at least one opening as gas inlet and at least one opening as gas outlet preferably leads to a gas flow in the crucible.
  • the silica granules are introduced into the crucible and then heated in the crucible.
  • the heating may be carried out in the presence of a gas or a mixture of two or more gases.
  • water bound to the silica granules may also pass into the gas phase to form another gas.
  • the gas or mixture of two or more gases is in the headspace of the crucible.
  • the gas space of the crucible is understood to mean the area inside the crucible which is not occupied by a solid or liquid phase. Suitable gases are, for example, hydrogen, inert gases and two or more thereof.
  • Inert gases are understood to mean those gases which do not react with the substances provided in the crucible up to a temperature of 2400 ° C.
  • Preferred inert gases are nitrogen, helium, neon, argon, krypton and xenon, more preferably argon and helium.
  • the heating is carried out in a reducing atmosphere.
  • This may preferably be provided by hydrogen or a combination of hydrogen and an inert gas, for example by a combination of hydrogen and helium, or of hydrogen and nitrogen, or of hydrogen and argon, more preferably by a combination of hydrogen and helium.
  • an at least partial gas exchange of air, oxygen and water to hydrogen, at least one inert gas, or against a combination of hydrogen and at least one inert gas is carried out on the silica granules.
  • the at least partial gas exchange is performed on the silica granules upon introduction of the silica granules, or before heating, or during heating, or during at least two of the aforementioned activities.
  • the silica granules are heated to melt in a gas stream of hydrogen and at least one inert gas, for example, argon or helium.
  • the dew point of the gas as it exits through the gas outlet is less than 0 ° C.
  • the dew point is understood to mean the temperature below which, under unchanged pressure, a constituent of the gas or gas mixture under investigation condenses. In general, this refers to the condensation of water.
  • the dew point is determined with a dew point mirror hygrometer according to the measuring method described in the Methods section
  • the furnace preferably also a crucible located therein, at least one gas outlet, is removed through the gas supplied to the furnace and formed during operation of the furnace.
  • the furnace may also have at least one dedicated gas inlet.
  • gas may be introduced through the solid feed, also referred to as solids inlet, for example together with the silica particles, or before, after, or by a combination of two or more of the aforementioned possibilities.
  • the gas withdrawn from the furnace through the gas outlet as it exits the furnace through the gas outlet has a dew point of less than 0 ° C, for example less than -10 ° C, or less than
  • a measuring device for example, a device called "Optidew” the company Michell Instruments GmbH, D-61381 Friedrichsdorf.
  • the dew point of the gas is preferably determined at a measuring point at a distance of 10 cm or more from the gas outlet of the furnace. Often this distance is between 10 cm and 5 m. In this distance range - here described by "at the outlet” - the distance of the measuring point from the gas outlet of the furnace is insignificant for the result of the dew point measurement.
  • the gas is guided from the outlet to the measuring point in a fluid-conducting manner, for example in a hose or a tube
  • the temperature of the gas at the measuring point is often between 10 and 60 ° C., for example 20 to 50 ° C., in particular 20 to 30 ° C.
  • the gas or gas mixture before entry into the furnace, in particular the crucible has a dew point of less than -50 ° C, for example less than -60 ° C, or less than -70 ° C, or less than -80 ° C.
  • a dew point of -60 ° C is usually not exceeded.
  • the dew point of the gas before entering the furnace is at least 50 ° C less than when it leaves the crucible, for example at least 60 ° C, or even 80 ° C.
  • the above information applies. The same applies to a measurement of the dew point before entering the furnace. Since no source of moisture entry and no condensation precipitation is provided between the location of the measurement and the oven, the distance from the measuring point to the gas inlet of the oven is not important here.
  • the furnace in particular the crucible, is operated at a gas exchange rate in a range from 200 to 3000 L / h.
  • the dew point is determined in a measuring cell, wherein the measuring cell is separated by a membrane from the gas passing through the gas outlet.
  • the membrane is preferably permeable to moisture.
  • a dew point mirror measuring device is used to determine the dew point.
  • the dew point at the gas outlet of the oven can be adjusted.
  • a method of adjusting the dew point at the outlet of the furnace includes the following steps:
  • the dew point can be adjusted to a range of less than 0 ° C, for example, less than -10 ° C, more preferably less than -20 ° C. More preferably, the dew point can be set in a range of less than 0 ° C to -100 ° C, for example, less than -10 ° C to -80 ° C, more preferably less than -20 ° C to -60 ° C become.
  • input material silica particles prepared for producing a quartz glass body, preferably silica granules, silica granules or combinations thereof
  • silicon dioxide particles, the granules and the granules are preferably characterized by the features described in the context of the first subject.
  • the furnace and the gas stream are preferably characterized by the features described in the context of the first subject.
  • the gas stream is formed by introducing a gas through an inlet into the furnace and discharging a gas through an outlet from the furnace.
  • the "gas exchange rate” is understood to mean the volume of gas that is passed out of the furnace per outlet through the outlet,
  • the gas exchange rate is also referred to as the flow rate of the gas or as the volume flow rate.
  • the setting of the dew point can be effected in particular by varying the residual moisture of the input material or the gas exchange rate of the gas stream. For example, by increasing the residual moisture of the input material, the dew point can be increased. By reducing residual moisture of the input material, the dew point can be lowered. An increased gas exchange rate can lead to a reduction in the dew point. On the other hand, a reduced gas exchange rate can result in an increased dew point.
  • the gas exchange rate of the gas stream is preferably in a range from 200 to 3000 L / h, for example from 200 to 2000 L / h, particularly preferably from 200 to 1000 L / h.
  • the residual moisture of the starting material is preferably in a range from 0.001% by weight to 5% by weight, for example from 0.01 to 1% by weight, particularly preferably from 0.03 to 0.5% by weight, in each case based on the total weight of the input material.
  • the dew point can preferably be influenced by further measures.
  • measures are the dew point of the gas stream entering the furnace, the furnace temperature and the composition of the gas stream.
  • a decrease in the dew point of the gas stream as it enters the furnace, a decrease in the furnace temperature, or a decrease in the temperature of the gas stream at the outlet of the furnace Furnace may cause a reduction in the dew point of the gas flow at the outlet.
  • the temperature of the gas stream at the exit of the furnace has no influence on the dew point, if it is above the dew point.
  • the gas exchange rate of the gas stream is varied.
  • the process is preferably characterized by at least one, for example at least two or at least three, more preferably at least four of the following features:
  • a gas exchange rate of the gas stream in a range from 200 to 3000 L / h, for example from 200 to 2000 L / h, more preferably from 200 to 1000 L / h;
  • an oven temperature in a range of 1700 to 2500 ° C, for example in a range of 1900 to 2400 ° C, more preferably in a range of 2100 to 2300 ° C;
  • V ⁇ the gas stream comprises helium, hydrogen or a combination thereof, preferably helium and hydrogen in a ratio of from 20:80 to 95: 5;
  • VI ⁇ a temperature of the gas at the outlet in a range of 10 to 60 ° C, for example from 20 to
  • a gas stream with a high gas exchange rate and a low dew point at the inlet of the furnace when using a granular silica with a high residual moisture content.
  • a gas flow with a low gas exchange rate and a higher dew point can be used at the inlet of the furnace.
  • the gas exchange rate of a gas stream comprising helium and hydrogen is particularly preferably in the range from 200 to 3000 L / h.
  • a dew point of less than 0 ° C is obtained.
  • the furnace temperature for melting the silica granules is preferably in the range of 1700 to 2500 ° C, for example, in the range of 1900 to 2400 ° C, more preferably in the range of 2100 to 2300 ° C.
  • the residence time in the furnace is preferably in the range from 1 hour to 50 hours, for example 1 to 30 hours, particularly preferably 5 to 20 hours.
  • the residence time in the context of the present invention means the time required to remove a filling amount of the melting furnace according to the method during the implementation of the method according to the invention, the melting furnace in which the molten glass is formed.
  • the filling quantity is the total amount of silicon dioxide present in the melting furnace.
  • the silicon dioxide can be present as a solid and as a glass melt.
  • the furnace temperature increases over the length, in the direction of material transport.
  • the furnace temperature preferably increases over the length, in the direction of material transport by at least 100 ° C., for example by at least 300 ° C. or by at least 500 ° C.
  • the highest temperature in the oven is 1700 to 2500 ° C, for example 1900 to 2400 ° C, more preferably 2100 to 2300 ° C.
  • the increase in the oven temperature can be uniform or according to a temperature profile.
  • the oven temperature decreases before the glass melt is removed from the oven.
  • the oven temperature before the glass melt is removed from the oven by 50 to 500 ° C from, for example, to 100 ° C or 400 ° C, more preferably from 150 to 300 ° C.
  • the temperature of the glass melt during removal is preferably 1750 to 2100 ° C, for example 1850 to 2050 ° C, particularly preferably 1900 to 2000 ° C.
  • the oven temperature increases over the length, in the direction of material transport, and before the glass melt is removed from the oven.
  • the furnace temperature increases over the length, in the direction of material transport by at least 100 ° C, for example by at least 300 ° C or by at least 500 ° C or by at least 700 ° C, more preferably by at least 1000 ° C.
  • the highest temperature in the oven is 1700 to 2500 ° C, for example 1900 to 2400 ° C, more preferably 2100 to 2300 ° C.
  • the furnace has at least a first and a further chambers connected to each other through a passage, wherein the first and the further chamber have different temperatures, wherein the temperature of the first chamber is lower than the temperature of the further chamber.
  • a glass melt is formed from the silica granules.
  • This chamber is referred to below as the melting chamber.
  • a connected to the melting chamber via a fabric guide, but upstream chamber is also referred to as preheating. It is, for example, that in which at least one outlet is directly connected to an inlet of the melting chamber.
  • the aforementioned arrangement can also be formed in independent ovens.
  • the melting chamber is a melting furnace. With regard to the further description, however, the melting furnace can be understood to be synonymous with the melting chamber. Accordingly, the remarks on the melting furnace also apply to the melting chamber, and vice versa.
  • the term preheating line is the same for both approaches.
  • the silica granules entering the furnace have a temperature in a range of 20 to 1300 ° C.
  • the silica granules are not tempered before entering the melting chamber.
  • the silica granules entering the oven have a temperature in a range of 20 to 40 ° C, more preferably 20 to 30 ° C.
  • silicon dioxide granules II are provided in accordance with step i.)
  • It preferably has a temperature in the range from 20 to 40 ° C., particularly preferably from 20 to 30 ° C., on entering the furnace.
  • the silica granules are tempered before entering the furnace to a temperature in a range of 40 to 1300 ° C.
  • Tempering means setting the temperature to a selected value.
  • the tempering can be carried out in principle on all known to those skilled and known for controlling the temperature of silica granules.
  • the tempering may be carried out in a furnace separate from the melting chamber or in an oven connected to the melting chamber.
  • the tempering takes place in a chamber connected to the melting chamber.
  • the furnace thus preferably comprises a preheating section in which the silicon dioxide can be tempered.
  • the preheating section itself is preferably a continuous furnace, particularly preferably a rotary kiln.
  • a continuous furnace is understood to mean a heated chamber which, during operation, causes a movement of the silicon dioxide from an inlet of the continuous furnace to an outlet of the continuous furnace.
  • the outlet is directly connected to the inlet of the melting furnace.
  • the silica granules from the preheating without further intermediate steps or measures can enter the furnace.
  • the preheating section comprises at least one gas inlet and at least one gas outlet.
  • gas inlet gas can enter the interior, the gas space of the preheating, and through the gas outlet, it can be discharged.
  • gas inlet gas can enter the interior, the gas space of the preheating, and through the gas outlet, it can be discharged.
  • gas into the preheating section via the inlet for the silicon dioxide granules of the preheating section.
  • gas can be discharged via the outlet of the preheating section and subsequently separated from the silicon dioxide granulate.
  • gas can be supplied via the inlet for the silicon dioxide granules and a gas inlet of the preheating section, and discharged via the outlet of the preheating section and a gas outlet of the preheating section.
  • a gas flow is formed in the preheat section by using the gas inlet and the gas outlet.
  • gases are, for example, hydrogen, inert gases and two or more thereof.
  • Preferred inert gases are nitrogen, helium, neon, argon, krypton and xenon, more preferably nitrogen and helium.
  • a reducing atmosphere is present in the preheating section. This may preferably be provided by hydrogen or a combination of hydrogen and an inert gas, for example by a combination of hydrogen and helium or of hydrogen and nitrogen, more preferably by a combination of hydrogen and helium. More preferably, an oxidizing atmosphere is present in the preheating section.
  • the furnace includes at least two chambers.
  • the furnace includes a first and at least one further chamber. The first and the further chambers are connected to each other by a passage.
  • the at least two chambers can in principle be arranged as desired in the oven, preferably vertically or horizontally, particularly preferably vertically.
  • the chambers are arranged in the furnace so that in the implementation of the method according to the first subject of the invention, silica granules pass through the first chamber and then heated in the further chamber to obtain a molten glass.
  • the further chamber preferably has the above-described features of the melting furnace and the crucible arranged therein.
  • each of the chambers includes an inlet and an outlet.
  • the inlet of the furnace is connected to the inlet of the first chamber through a passage.
  • the outlet of the furnace is connected to the outlet of the further chamber through a passage.
  • the outlet of the first chamber is connected by a passage to the inlet of the further chamber.
  • the chambers are preferably arranged in the furnace in such a way that the silica granules can pass into the first chamber through the inlet of the furnace.
  • the chambers are preferably arranged in the furnace such that a silicon dioxide glass melt can be removed from the further chamber through the outlet of the furnace.
  • the silica granules can enter the first chamber through the inlet of the furnace and a silicon dioxide glass melt can be taken out of another chamber through the outlet of the furnace.
  • the silicon dioxide can pass as granules or powder in the direction predetermined by the method of transporting material from a first chamber to another.
  • Chambers connected by a passage include arrangements in which further intermediate elements are arranged between a first and a further chamber in the direction of material transport.
  • gases, liquids and solids can pass through the passage.
  • silica powders, slurries of silica powder and silica granules may pass the transition between a first and a further chamber.
  • all substances introduced into the first chamber can pass into the further chamber via the passage between the first and the further chambers.
  • silicon dioxide in the form of granules or powder passes into the further chamber via the passage between the first and further chambers.
  • the passage between the first and the further chambers is closed by silicon dioxide, so that the chamber of the first chamber and the further chamber are separated from one another, preferably in that the chambers can have different gas or gas mixtures, different pressures or both.
  • the passageway is formed by a slag, preferably by a cellular radioscler.
  • the first chamber of the hearth gives to the stove a nest and to a Gaeauelaee.
  • the thing may be of any shape known to those skilled in the art and suitable for introducing a gesture, such as a nozzle, a valve, or a pipe.
  • the Gaeauelaee may be of any shape which is known to the person skilled in the art and suitable for outdoor use, for example a nozzle, a valve or a tube.
  • silicon dioxide granules are introduced and heated into the first chamber by the inlet of the furnace.
  • the heating may be carried out in the presence of a gooe or a combination of two or more goae.
  • dae Gae or the combination of two or more Gaeen is present in the chamber of the chamber.
  • the area of the grounded chamber is situated, which is not occupied by a fair or flute-like phaee.
  • Suitable guests include Waeeeretoff, Saueretoff, Inertgaee and two or more of them.
  • Preferred inert gas including nitrogen, helium, neon, argon, krypton and xenon, preferably a nitrogen, helium and a combination thereof.
  • the heating is carried out in a reducing atmosphere.
  • the tea may preferably be prepared by heat or a combination of heat and helium.
  • the silica granules are heated in the first chamber in a flow of gas or the combination of two or more gases.
  • the silica granules be heated in the first chamber at reduced pressure, for example at a pressure of less than 500 mbar or less than 300 mbar, for example 200 mbar or less.
  • the first chamber is sealed with a device of the type with which silicon dioxide granules are agitated.
  • a device of the type with which silicon dioxide granules are agitated Preferably suitable a stirring, shaking or swiveling devices.
  • the temperatures in the first and in the further chamber are different.
  • the temperature in the first chamber is lower than the temperature in the other chamber.
  • the temperature difference between the first and the further chamber in a range of 600 to 2400 ° C, for example in a range of 1000 to 2000 ° C or from 1200 to 1800 ° C, more preferably in a range of 1500 to 1700 ° C.
  • the temperature in the first chamber is 600 to 2400 ° C, for example 1000 to 2000 ° C or 1200 to 1800 ° C, more preferably 1500 to 1700 ° C lower than the temperature in the other chamber.
  • the first chamber of the furnace is a preheating section, more preferably a preheating section as described above, having the features described above.
  • the preheating is connected by a passage with the other chamber.
  • silicon dioxide passes from the preheating section via an opening into the further chamber.
  • the passage between the preheating section and the further chamber may be closed, so that no gases introduced into the preheating section pass through the passage into the further chamber.
  • the passage between the preheating and the other chamber is closed, so that the silicon dioxide does not come into contact with water.
  • the passage between the preheating section and the further chamber can be closed, so that the gas space of the preheating section and the first chamber are separated from one another such that different gases or gas mixtures, different pressures or both can be present in the gas spaces.
  • a passage are preferably the embodiments described above.
  • the first chamber of the furnace is not a preheating section.
  • the first chamber is a compensation chamber.
  • a compensation chamber is understood to mean a chamber of the furnace in which throughput variations in an upstream preheating section or throughput differences between a preheating section and the further chamber are compensated.
  • the first chamber may be preceded by a rotary kiln as described above. This usually has a throughput that can vary by up to 6% of the average throughput.
  • silica is maintained in a compensation chamber at the temperature with which it enters the compensation chamber.
  • the furnace has a first chamber and more than one further chamber, for example two further chambers or three further chambers or four further chambers or five further chambers or more than five further chambers, particularly preferably two further chambers.
  • the first chamber is preferably a preheating section
  • the first of the further chambers is a compensation chamber
  • the second of the further chambers is the melting chamber, based on the direction of material transport.
  • an additive is present in the first chamber.
  • the additive is preferably selected from the group consisting of halogens, inert gases, bases, oxygen or a combination of two or more thereof.
  • halogens in elemental form and halogen compounds are suitable as additives.
  • Preferred halogens are selected from the group consisting of chlorine, fluorine, chlorine-containing compounds and fluorine-containing compounds. Particularly preferred are elemental chlorine and hydrogen chloride.
  • all inert gases and mixtures of two or more thereof are suitable as additives.
  • Preferred inert gases are nitrogen, helium or a combination thereof.
  • bases are also suitable as additives.
  • Preferred bases as additives are inorganic and organic bases.
  • the oxygen is preferably present as an oxygen-containing atmosphere, for example in combination with an inert gas or a mixture of two or more inert gases, particularly preferably in combination with nitrogen, helium or nitrogen and helium.
  • the first chamber may in principle include any material known to those skilled in the art and suitable for heating silica.
  • the first chamber preferably contains at least one element selected from the group consisting of quartz glass, a refractory metal, aluminum and a combination of two or more thereof, particularly preferably the first chamber contains quartz glass or aluminum.
  • the temperature in the first chamber does not exceed 600 ° C when the first chamber includes a polymer or aluminum.
  • the temperature in the first chamber is 100 to 1100 ° C when the first chamber includes quartz glass.
  • the first chamber preferably contains essentially quartz glass.
  • the silicon dioxide When transporting the silicon dioxide from the first chamber to the further chamber through the passage between the first and the further chamber, the silicon dioxide can in principle be in any state.
  • the silicon dioxide is preferably present as a solid, for example as particles, powders or granules.
  • the transport of the silicon dioxide from the first to the further chamber takes place as granules.
  • the further chamber is a crucible of a sheet metal or a sintered material, which contains a sintered metal, wherein the sheet or the sintered metal is selected from the group consisting of molybdenum, tungsten and a combination thereof.
  • the glass melt is removed through the outlet from the oven, preferably via a nozzle.
  • a quartz glass body is formed from at least part of the molten glass.
  • at least part of the glass melt produced in step ii) is preferably removed and the quartz glass body formed therefrom.
  • the removal of a portion of the glass melt produced in step ii) can, in principle, continuously from
  • a part of the molten glass is removed continuously.
  • the molten glass is removed through the outlet from the furnace or the outlet of the melting chamber, preferably via a nozzle.
  • the molten glass may be cooled before, during or after removal to a temperature which allows the molten glass to be molded. With the cooling of the molten glass, an increase in the viscosity of the molten glass is connected.
  • the molten glass is preferably cooled to the extent that during molding the formed form is maintained and the molding can be performed simultaneously as quickly as possible, reliable and with little effort.
  • the person skilled in the art can easily determine the viscosity of the molten glass for molding by varying the temperature of the molten glass on the mold.
  • When removing the molten glass preferably has a temperature in the range of 1750 to 2100 ° C, for example 1850 to 2050 ° C, particularly preferably 1900 to 2000 ° C.
  • the glass melt after removal to a temperature of less than 500 ° C, for example, less than 200 ° C or less than 100 ° C or less than 50 ° C, more preferably to a temperature in the range of 20 to 30 ° C cooled.
  • the formed quartz glass body may be a solid body or a hollow body.
  • a solid body is meant a body consisting essentially of a single material.
  • a solid body may have one or more inclusions, eg, gas bubbles.
  • Such inclusions in a solid body often have a size of 65 mm 3 or less, for example less than 40 mm 3 , or less than 20 mm 3 , or less than 5 mm 3 'or less than 2 mm 3 , more preferably less than 0.5 mm 3 .
  • a solid body contains less than 0.02% by volume of its volume, for example, less than 0.01% by volume or less than 0.001% by volume of inclusions, each based on the total volume of the solid body.
  • the quartz glass body has an outer shape.
  • the outer shape is understood to be the shape of the outer edge of the cross section of the quartz glass body.
  • the outer shape of the quartz glass body is preferably round, elliptical or polygonal in cross-section with three or more corners, for example 4, 5, 6, 7 or 8 corners, more preferably the quartz glass body is round.
  • the quartz glass body has a length in the range of 100 to 10,000 mm, for example from 1000 to 4000 mm, particularly preferably from 1200 to 3000 mm.
  • the quartz glass body has an outer diameter in the range of 1 to 500 mm, for example in a range of 2 to 400 mm, more preferably in a range of 5 to 300 mm.
  • the molding of the quartz glass body takes place by means of a nozzle.
  • the molten glass is passed through the nozzle.
  • the outer shape of a quartz glass body formed by the nozzle is determined by the shape of the opening of the nozzle.
  • a cylinder is formed as the quartz glass body is formed. If the opening of the nozzle has a structure, this structure is transferred to the outer shape of the quartz glass body.
  • a quartz glass body which is formed by means of a nozzle with structures at the opening, has an image of the structures in the longitudinal direction on the glass strand.
  • the nozzle is integrated in the furnace. Preferably, it is integrated as part of the crucible in the furnace, more preferably as part of the outlet of the crucible.
  • the at least part of the molten glass is removed through the nozzle.
  • the outer shape of the quartz glass body is formed by removing at least a portion of the glass melt through the nozzle.
  • the quartz glass body is cooled after forming to obtain its shape.
  • the quartz glass body is cooled after molding to a temperature which is at least 1000 ° C below the temperature of the glass melt during molding, for example at least 1500 ° C or at least 1800 ° C, more preferably 1900 to 1950 ° C.
  • the quartz glass body is cooled to a temperature of less than 500 ° C, for example of less than 200 ° C or less than 100 ° C or less than 50 ° C, more preferably to a temperature in the range of 20 to 30 ° C.
  • the resulting quartz glass body may be treated with at least one measure selected from the group consisting of chemical, thermal or mechanical treatment.
  • the quartz glass body is chemically treated.
  • Post-treatment refers to the treatment of an already formed quartz glass body.
  • chemical aftertreatment of the quartz glass body is understood in principle any measure which is known to the person skilled in the art and appears to be suitable for changing the chemical structure or the composition of the surface of the quartz glass body or both by the use of substances.
  • the chemical aftertreatment comprises at least one measure selected from the group consisting of treatment with fluorine compounds and ultrasonic cleaning.
  • Particularly suitable fluorine compounds are hydrogen fluoride and fluorine-containing acids, for example hydrofluoric acid.
  • the liquid preferably has a content of fluorine compounds in a range of 35 to 55 wt .-%, preferably in a range of 35 to 45 wt .-%, the wt .-% in each case based on the total amount of liquid.
  • the remainder to 100% by weight is usually water.
  • demineralized or deionized water is selected as the water.
  • Ultrasonic cleaning is preferably carried out in a liquid bath, more preferably in the presence of detergents.
  • detergents usually no fluorine compounds, for example, neither hydrofluoric acid nor hydrogen fluoride, are used.
  • the ultrasonic cleaning of the quartz glass body is preferably carried out under at least one, for example at least two or at least three or at least four or at least five, more preferably all of the following conditions:
  • the ultrasonic cleaning takes place in a continuous process.
  • the ultrasonic cleaning system has six chambers connected to each other by pipes. - The residence time of the quartz glass body in each chamber can be adjusted.
  • the quartz glass body in each chamber can be adjusted.
  • Residence time of the quartz glass body in each chamber is in each Chamber in a range of 1 to 120 minutes, for example less than 5 minutes or from 1 to 5 minutes or from 2 to 4 minutes or less than 60 minutes or from 10 to 60 minutes or from 20 to 50 minutes, more preferably in a range of 5 to 60 min.
  • the first chamber comprises a basic medium, preferably containing water and a base, and an ultrasonic cleaner.
  • the third compartment comprises an acidic medium, preferably containing water and an acid, and an ultrasound leg.
  • the quartz glass body is cleaned with water, preferably demineralized water.
  • the fourth to sixth chamber is operated as a cascade with water, preferably desalted water.
  • the water is introduced only in the sixth chamber and runs from the sixth to the fifth and from the fifth to the fourth chamber.
  • the quartz glass body is thermally treated.
  • thermal aftertreatment of the quartz glass body is understood in principle any measure which is known to the person skilled in the art and appears suitable for changing the quartz glass body by the action of temperature in its shape or structure or both.
  • the thermal aftertreatment preferably comprises at least one measure selected from the group consisting of annealing, upsetting, inflation, drawing, welding and a combination of two or more thereof.
  • the thermal aftertreatment preferably takes place without the goal of material removal.
  • the annealing is preferably carried out by heating the quartz glass body in an oven, preferably at a temperature in a range of 900 to 1300 ° C, for example in a range of 900 to 1250 ° C or 1040 to 1300 ° C, more preferably in one range from 1000 to 1050 ° C or from 1200 to 1300 ° C.
  • a temperature of 1300 ° C is not exceeded for a continuous period of more than 1 h, more preferably, a temperature of 1300 ° C is not exceeded during the entire thermal treatment time.
  • the annealing can in principle be carried out at reduced pressure, at atmospheric pressure or at elevated pressure, preferably at reduced pressure, particularly preferably in vacuo.
  • the compression is preferably carried out by heating the quartz glass body, preferably to a temperature of about 2100 ° C, and then forming during a rotary rotary motion, preferably at a rotational speed of about 60 U / min.
  • a quartz glass body in the form of a rod can be reshaped by compression into a cylinder.
  • a quartz glass body can be inflated by blowing a gas into the quartz glass body.
  • a quartz glass body can be reshaped by blowing into a large pipe.
  • the quartz glass body preferably to a temperature of about 2100 ° C, while a rotary rotational movement, preferably at a rotational speed of about 60 U / min, is performed, heated and the interior is purged with a gas, preferably at a defined and regulated Internal pressure up to about 100 mbar.
  • a large pipe is understood to mean a pipe with an outer diameter of at least 500 mm.
  • a quartz glass body can preferably be pulled out. The drawing is preferably carried out by heating the quartz glass body, preferably to a temperature of about 2100 ° C, and then drawing with a controlled drawing speed to the desired outer diameter of the quartz glass body.
  • lamp tubes can be formed by drawing out of quartz glass bodies.
  • the quartz glass body is mechanically aftertreated.
  • mechanical aftertreatment of the quartz glass body is understood in principle any measure which is known to the person skilled in the art and which appears suitable for changing the shape of the quartz glass body by an abrasive measure or for dividing the quartz glass body into several pieces.
  • the mechanical aftertreatment includes at least one measure selected from the group consisting of grinding, drilling, honing, sawing, water jet cutting, laser beam cutting, thawing by sand blasting, milling and a combination of two or more thereof.
  • the quartz glass body with a combination of these measures for example with a combination of a chemical and a thermal aftertreatment or a chemical and a mechanical aftertreatment or a thermal and a mechanical aftertreatment, particularly preferably with a combination of a chemical, a thermal and a treated mechanical aftertreatment.
  • the quartz glass body can each be subjected, independently of one another, to a plurality of the aforementioned measures.
  • the method includes the following method step:
  • the formed hollow body has an inner and an outer shape.
  • Inner form is understood to mean the shape of the inner edge of the hollow body in cross section.
  • the inner and outer shape of the cross section of the hollow body may be the same or different.
  • the inner and outer shapes of the hollow body may be round, elliptical or polygonal in cross-section with three or more corners, for example 4, 5, 6, 7 or 8 corners.
  • the outer shape of the cross section corresponds to the inner shape of the cross section of the hollow body.
  • the hollow body in cross section has a round inner and a round outer shape.
  • the hollow body may differ in the inner and outer shape.
  • the hollow body in cross section has a round outer shape and a polygonal inner shape.
  • the hollow body has a round outer shape and a hexagonal inner shape in cross section.
  • the hollow body has a length in the range of 100 to 10,000 mm, for example from 1000 to 4000 mm, more preferably from 1200 to 2000 mm.
  • the hollow body has a wall thickness in a range of 0.8 to 50 mm, for example in a range of 1 to 40 mm or from 2 to 30 mm or from 3 to 20 mm, particularly preferably in a range of 4 to 10 mm .
  • the hollow body has an outer diameter of 2.6 to 400 mm, for example in a range of 3.5 to 450 mm, more preferably in a range of 5 to 300 mm.
  • the hollow body preferably has an inner diameter of 1 to 300 mm, for example in a range of 5 to 280 mm or of 10 to 200 mm, particularly preferably in a range of 20 to 100 mm.
  • the hollow body contains one or more openings.
  • the hollow body includes an opening.
  • the hollow body preferably contains an even number of openings, for example 2, 4, 6, 8, 10, 12, 14, 16, 18 or 20 openings.
  • the hollow body contains two openings.
  • the hollow body is a tube. This shape of the hollow body is particularly preferred when the optical fiber includes only one core.
  • the hollow body may contain more than two openings.
  • the openings are preferably in pairs opposite each other in the ends of the quartz glass body. For example, each end of the quartz glass body has 2, 3, 4, 5, 6, 7 or more than 7 openings, more preferably 5, 6 or 7 openings.
  • Preferred shapes are, for example, tubes, twin tubes, ie tubes with two parallel channels, multi-channel bars, ie tubes with more than two parallel channels.
  • the hollow body can in principle be formed in any way known to those skilled in the art.
  • the hollow body is formed by means of a nozzle.
  • the nozzle in the center of its opening contains a device which dissipates the molten glass during molding.
  • a hollow body can be formed from a molten glass.
  • the formation of a hollow body can be done by using a nozzle and subsequent aftertreatment.
  • all processes known to the person skilled in the art for producing a hollow body from a solid body for example the swaging of channels, drilling, honing or grinding, are suitable as aftertreatment.
  • As a post-treatment it is preferable to guide the solid body over one or more spikes, whereby a hollow body is formed.
  • the mandrel can be introduced into the solid body to form a hollow body.
  • the hollow body is cooled after forming.
  • the hollow body is after forming at a temperature of less than 500 ° C, for example less than 200 ° C or less than 100 ° C or less than 50 ° C, more preferably at a temperature in the range of 20 to 30 ° C cooled.
  • the silicon dioxide granules provided in step i One or more
  • pretreatment steps for example, thermal or mechanical treatment steps into consideration.
  • the silica granules are compacted before heating in step ii.).
  • the silica granules are preferably densified thermally by heating the silica granules or mechanically by applying a pressure to the silica granules, for example, rolling or pressing the silica granules.
  • the silica granules are compacted by heating.
  • the compacting of the silicon dioxide granules is carried out by heating by means of a preheating section connected to the melting furnace.
  • the silica is densified by heating at a temperature in a range of 800 to 1400 ° C, for example, at a temperature in a range of 850 to 1300 ° C, particularly preferably at a temperature in a range of 900 to 1200 ° C.
  • the BET surface area of the silica granule prior to heating in step ii.) Is not reduced to less than 5 m 2 / g, preferably not less than 7 m 2 / g or not less than 10 m 2 / g, more preferably not less than 15 m 2 / g. It is further preferred that the BET surface area of the silica granules prior to heating in step ii.) Is not reduced over the silica granules provided in step i.).
  • the BET surface area of Siliziumdioxidgranulats is reduced to less than 20 m 2 / g, for example less than 15m 2 / g, or less than 10 m 2 / g, or to a range from more than 5 to less than 20 m 2 / g or from 7 to 15 m 2 / g, more preferably in a range from 9 to 12 m 2 / g.
  • the BET surface area of the silica granules is reduced by less than 40 m 2 / g, for example by 1 to 20 m 2 / g or by 2 to 10, prior to heating in step ii.) Over the silica granules provided in step i.) m 2 / g, more preferably around 3 to 8 m 2 / g, wherein the BET surface area after compaction is more than 5 m 2 / g.
  • the compacted silica granules are referred to below as silica granules III.
  • the silicon dioxide granules III preferably have at least one, for example at least two or at least three or at least four, more preferably at least five of the following characteristics:
  • a particle size D 10 in a range of 100 to 300 ⁇ , more preferably in a range of 120 to 200 ⁇ ;
  • E a bulk density in a range of 0.8 to 1.6 g / cm 3 , more preferably from 1.0 to 1.4 g / cm 3 ;
  • G an amount of carbon of less than 5 ppm, for example less than 4.5 ppm, more preferably less than 4 ppm; H. a Cl content of less than 500 ppm, more preferably from 1 ppb to 200 ppm, wherein the ppm and ppb are each based on the total weight of the silica granules III.
  • the silica granule III preferably has the feature combination A./F./G. or A./F./H. or A./G./H. on, particularly preferably the combination of features A./F./G./H.
  • the silica granule III preferably has the feature combination A./F./G. wherein the BET surface area is in a range of 10 to 30 m 2 / g, the tamped density is in a range of 1.15 to 1.35 g / mL, and the carbon content is less than 4 ppm.
  • the silica granules III preferably has the combination of features A./F./H. wherein the BET surface area is in a range of 10 to 30 m 2 / g, the tapped density is in a range of 1.15 to 1.35 g / ml, and the chlorine content is in a range of 1 ppb to 200 ppm.
  • the silica granules III preferably has the feature combination A./G./H. wherein the BET surface area is in a range of 10 to 30 m 2 / g, the carbon content is less than 4 ppm, and the chlorine content is in a range of 1 ppb to 200 ppm.
  • the silica granules III preferably has the feature combination A./F./G./H. wherein the BET surface area is in a range of 10 to 30 m 2 / g, the tamped density is in a range of 1.15 to 1.35 g / ml, the carbon content is less than 4 ppm and the chlorine content in one Range from 1 ppb to 200 ppm.
  • a silicon component other than silicon dioxide is added.
  • the addition of a silicon component other than silicon dioxide is also referred to below as Si doping.
  • the Si doping can be carried out in any method step.
  • the Si doping is preferably carried out in step i) or in step iL).
  • the silicon component other than silicon dioxide can in principle be added in any desired form, for example as a solid, as a liquid, as a gas, in solution or as a dispersion.
  • the silicon dioxide-different silicon component is added as a powder.
  • the silicon dioxide-different silicon component is added as a liquid or as a gas.
  • the silicon dioxide-non-silicon component is preferably added in an amount within a range of 1 to 100,000 ppm, for example, in a range of 10 to 10,000 ppm or 30 to 1,000 ppm or in a range of 50 to 500 ppm, more preferably in one Range of 80 to 200 ppm, more preferably in a range of 200 to 300 ppm, each based on the total weight of silica.
  • the silicon dioxide-different silicon component may be solid, liquid or gaseous.
  • it preferably has an average particle size of up to 10 mm, for example of up to 1000 ⁇ of up to 400 ⁇ or in a range of 1 to 400 ⁇ , for example 2 to 200 ⁇ or 3 to 100 ⁇ , more preferably in a range of 5 to 50 ⁇ .
  • the particle size data are based on the state of the non-silicon dioxide silicon component at room temperature.
  • the silicon component preferably has a purity of at least 99.5 wt .-%, for example of at least 99.8 wt .-% or of at least 99.9 wt .-%, or of at least 99.99 wt .-%, more preferably of at least 99.999 wt .-%, each based on the total weight of the silicon component.
  • the silicon component has an amount of carbon of not more than 10 ppm, for example not more than 50 ppm, more preferably not more than 1 ppm, in each case based on the total weight of the silicon component. This is particularly preferred for silicon used as a silicon component.
  • the silicon component has an amount of impurities selected from the group consisting of Al, Ca, Co, Cr, Cu, Fe, Ge, Hf, K, Li, Mg, Mn, Mo, Na, Nb, Ni, Ti, V, W, Zn, Zr of not more than 250 ppm, for example not more than 150 ppm, more preferably not more than 100 ppm, in each case based on the total weight of the silicon component. This is particularly preferred for silicon used as a silicon component.
  • a silicon component other than silicon dioxide is preferably added.
  • the silica component other than silicon dioxide is added to a silica granule during processing of the silica powder (step II).
  • the silicon dioxide-different silicon component may be added to the silica before, during, or after granulation.
  • the silica may be Si-doped by adding the silicon dioxide-disparate silicon component to the slurry including silica powder.
  • the silicon dioxide-dissimilar silicon component is mixed with silica powder and then slurried in a liquid, or the silicon dioxide-non-silicon component is added to a slurry of silica powder in a liquid and slurried, or the silica powder becomes a slurry or solution of Silicon dioxide various silicon component in a liquid and slurried.
  • the silicon dioxide can be Si-doped by adding the silicon dioxide-different silicon component during granulation. It is in principle possible to add the silicon dioxide-different silicon component at any time during granulation.
  • the silica component other than silica may be sprayed through the nozzle together with the slurry into the spray tower.
  • the silicon dioxide-different silicon component may preferably be added in solid form or as a slurry, for example, after the slurry is introduced into the stirred tank. More preferably, the silica may be Si-doped by adding the silicon dioxide-disparate silicon component after granulation.
  • the silica in the treatment of the silica granules I, may be doped to the silica granules II, preferably by adding the non-silica silicon component during the thermal or mechanical treatment of the silica granules I.
  • the silica granule II is doped with the silicon dioxide-different silicon component. More preferably, the silicon dioxide-different silicon component can also be added during several of the aforementioned sections, in particular during and after the thermal or mechanical treatment of the silicon dioxide granules I to the silicon dioxide granules II.
  • the silicon component which is different from silicon dioxide, may in principle be silicon or any compound containing silicon which is known and has a reducing effect on the person skilled in the art.
  • the silicon component other than silicon dioxide is preferably silicon, a silicon-hydrogen compound, for example a silane, a silicon-oxygen compound, for example silicon monoxide, or a silicon-hydrogen-oxygen compound, for example disiloxane.
  • a silicon-hydrogen compound for example a silane
  • a silicon-oxygen compound for example silicon monoxide
  • silicon-hydrogen-oxygen compound for example disiloxane.
  • Examples of preferred silanes are monosilane, disilane, trisilane, tetrasilane pentasilane, hexasilane heptasilane, higher homologs and isomers of the aforementioned, as well as cyclic silanes such as cyclopentasilane.
  • a silicon component other than silicon dioxide is preferably added.
  • the silicon dioxide-different silicon component may be added directly to the crucible together with the silica granules.
  • silicon may be added to the crucible as the non-silica silicon component together with the silica granules.
  • the silicon is preferably added as a powder, in particular in the particle size already mentioned for the silicon dioxide-different silicon component.
  • the silica component other than silicon dioxide is added to the silica granules prior to introduction into the crucible. The addition can in principle be carried out at any time after the formation of the granules, for example in the preheating section, before or during the precompression of the silicon dioxide granules II or to the silicon dioxide granules III.
  • Si-doped granules are referred to below as "Si-doped granules.”
  • the Si-doped granules have at least one, for example at least two or at least three or at least four, more preferably at least five of the following characteristics:
  • a BET surface area in a range of more than 5 to less than 40 m 2 / g, for example, 10 to 30 m 2 / g, particularly preferably in a range of 15 to 25 m 2 / g;
  • a particle size D 10 in a range of 100 to 300 ⁇ , more preferably in a range of 120 to 200 ⁇ ;
  • a particle size D 90 in a range of 300 to 650 ⁇ , more preferably in a range of 400 to 500 ⁇ ;
  • Wt .-% particularly preferably from 0.01 to 1 wt .-%;
  • the melting energy is transferred to the silica granules via a solid surface.
  • a solid surface is understood to mean a surface which is different from the surface of the silica granules and which does not melt or decompose at temperatures to which the silica granules are heated to melt.
  • Suitable materials of the solid surface are, for example, the materials suitable as crucible materials.
  • the solid surface may, in principle, be any surface known to those skilled in the art and suitable for these purposes.
  • the crucible or a separate component other than the crucible may be used as a solid surface.
  • the solid surface may, in principle, be heated in any way known to the person skilled in the art and suitable for this purpose in order to transfer the melting energy to the silicon dioxide granules.
  • the solid surface is heated by resistive heating or induction heating.
  • inductive heating the energy is coupled directly by coils in the solid surface and discharged from there to the inside.
  • resistive heating the solid surface is heated from the outside and releases the energy from there to the inside.
  • a heating chamber gas with a lower heat capacity for example an argon atmosphere or an argon-containing atmosphere, is advantageous.
  • the solid surface may be heated electrically or by firing the solid surface with a flame from the outside.
  • the solid surface is heated to a temperature that can transfer an amount of energy sufficient to melt the silica granules to the silica granules and / or partially melted silica granules.
  • a separate component is used as a solid surface, it can be brought into contact with the silicon dioxide granules in any manner, for example by placing the component on the silica granules or by introducing the component between the granules of the silicon dioxide granules or by interposing the component between crucible and silicon dioxide granules or by a combination of two or more of them.
  • the component may be heated before or during or before and during the transfer of the melting energy.
  • the melting energy is transferred via the crucible inside to the silica granules.
  • the crucible is heated to the point where the silica granulate melts.
  • the crucible is preferably heated resistively or inductively. The heat is transferred from the outside to the inside of the crucible.
  • the solid surface of the inner crucible transmits the melting energy to the silica granules.
  • the melting energy is not transferred to the silica granules via a gas space on the silica granules. More preferably, the melting energy is not transferred to the silica granules by firing the silica granules with a flame. Examples of these excluded energy transmission paths are directing one or more burner flames from the top into the crucible, or onto the silica, or both.
  • the above-described method according to the first aspect of the invention relates to the production of a quartz glass body.
  • the quartz glass body preferably has at least one of the following features, for example at least two or at least three or at least four, particularly preferably at least five of the following features:
  • C] has an aluminum content of less than 200 ppb, for example less than 100 ppb, more preferably less than 80 ppb;
  • D has an ODC content of less than 5-10 15 / cm 3 , for example in a range of 0.1 ⁇ 10 15 to 3-10 15 / cm 3 , particularly preferably in a range of 0.5 ⁇ 10 15 to 2.0 ⁇ 10 15 / cm 3 ;
  • a metal content of metals other than aluminum of less than 1 ppm, for example less than 0.5 ppm, more preferably less than 0.1 ppm;
  • G a standard deviation of the OH content of not more than 10%, preferably not more than 5%, based on the OH content A] of the quartz glass body; H] a standard deviation of the Cl content of not more than 10%, preferably not more than 5%, based on the Cl content B] of the quartz glass body;
  • a tungsten content of less than 1000 ppb for example less than 500 ppb or less than 300 ppb or less than 100 ppb or in a range of 1 to 500 ppb or from 1 to 300 ppb, more preferably in a range of 1 up to 100 ppb;
  • a molybdenum content of less than 1000 ppb for example less than 500 ppb or less than 300 ppb or less than 100 ppb or in a range of from 1 to 500 ppb or from 1 to 300 ppb, more preferably in a range of one up to 100 ppb,
  • the quartz glass body preferably has a metal content of metals other than aluminum of less than 1000 ppb, for example less than 500 ppb, particularly preferably less than 100 ppb, in each case based on the total weight of the quartz glass body. Often, however, the quartz glass body has a content of metals other than aluminum in an amount of at least 1 ppb.
  • metals include sodium, lithium, potassium, magnesium, calcium, strontium, germanium, copper, molybdenum, titanium, iron and chromium. These may be present, for example, as an element, as an ion, or as part of a molecule or an ion or a complex.
  • the quartz glass body may include other ingredients.
  • the quartz glass body contains less than 500 ppm, for example less than 450 ppm, more preferably less than 400 ppm of further constituents, the ppm being in each case based on the total weight of the quartz glass body.
  • Other constituents which may be considered are, for example, carbon, fluorine, iodine, bromine and phosphorus. These may be present, for example, as an element, as an ion, or as part of a molecule or an ion or a complex. Often, however, the quartz glass body has a content of other constituents in an amount of at least 1 ppb.
  • the quartz glass body contains carbon in an amount of less than 5 ppm, for example less than 4.5 ppm, more preferably less than 4 ppm, each based on the total weight of the quartz glass body.
  • the silica glass body has a content of carbon in an amount of at least 1 ppb.
  • the quartz glass body preferably has a homogeneously distributed OH amount, Cl amount or Al amount.
  • An indicator of the homogeneity of the quartz glass body can be expressed in the standard deviation of OH amount, Cl amount or AI amount.
  • the standard deviation is the measure of the spread of the values of a variable, here the OH quantity, amount of chlorine or amount of aluminum, by their arithmetic mean.
  • the content of the component to be determined in the sample for example OH, chlorine or aluminum, is determined at at least seven measurement points.
  • the quartz glass body preferably has the combination of features A] / B] / C] or A] / B] / D] or A] / B] / F], more preferably the combination of features A] / B] / C] / D] or A] / B] / C] / F] or A] / B] / D] / F], particularly preferably the combination of features A] / B] / C] / D] / F].
  • the quartz glass body preferably has the combination of features A] / B] / C], wherein the OH content is less than 400 ppm, the chlorine content less than 100 ppm and the aluminum content less than 80 ppb.
  • the quartz glass body preferably has the combination of features A] / B] / D], the OH content is less than 400 ppm, the chlorine content is less than 100 ppm and the ODC content is in a range of 0.1 -10 15 to 3 -10 15 / cm 3 lies.
  • the quartz glass body preferably has the combination of features A] / B] / C] / D], wherein the OH content is less than 400 ppm, the chlorine content less than 100 ppm, the aluminum content less than 80 ppb and the ODC content in one Range from 0, M0 15 to 3-10 15 / cm 3 .
  • a second object of the present invention is a method for producing a silica granule comprising the following method steps:
  • the silicon dioxide powder selected in step I. particularly preferably has a particle size distribution D 50 in the range from 6 to 15 ⁇ m.
  • Silica powders of the aforementioned particle size distribution can be processed particularly well according to the present invention, in particular in the industrial production of quartz glass.
  • Silica powders with a large proportion of particularly small powder particles are disadvantageous for the production of quartz glass.
  • Such silicon powders mainly contain particulate matter.
  • Most dust filters let particulate matter through much stronger than larger powder particles.
  • Even after a steam treatment as in step II difficulties arise with such silica powders. For example, it is difficult to separate powder suspended in water with a large proportion of particularly small powder particles, because such particles do not separate the particularly small powder particles from the aqueous phase due to gravity.
  • Silica powders with a proportion of large powder particles are considered disadvantageous in the further processing of the slurry into granules.
  • the slurry of silica powder and water described below is filtered.
  • fibers are separated from transport containers or possibly separating filters. It has been found that the filters which can be used for this purpose are added particularly quickly if the slurry contains many large powder particles.
  • the preferred range of the particle size distribution of silicon dioxide powder described above forms a particularly preferred section of the amount of available particle size distributions of silica powder.
  • the silica granules produced according to the second aspect of the invention preferably have at least one of the following features, for example at least two or at least three or at least four, more preferably at least five of the following features:
  • the steps I, II and III of the method according to the second subject of the invention are characterized by the features as described in the context of the first subject of the invention.
  • the silica granules have the characteristics of the silica granules I described in the context of the first subject of the invention.
  • silica granules having the characteristics of the silica granulate I described in the scope of the first aspect of the invention, obtainable by the process for producing a silica granulate I described in the context of the first subject of the invention. Preferred embodiments described herein are also preferred.
  • the silica granules have the characteristics of the silica granules II described in the context of the first subject of the invention.
  • Preferred is silica granules having the characteristics of the silica granule II described in the scope of the first aspect of the invention, obtainable by the method for producing a silica granule II described in the context of the first subject of the invention.
  • Embodiments described herein as preferred are also preferred.
  • a third object of the present invention is a quartz glass body obtainable by the method according to the first aspect of the invention.
  • the quartz glass body preferably has at least one of the following features, for example at least two or at least three or at least four, particularly preferably at least five of the following features:
  • C] has an aluminum content of less than 200 ppb, for example less than 100 ppb, more preferably less than 80 ppb;
  • 3-10 15 / cm 3 more preferably in a range of 0.5-101 1 5 J to 2.0-101 1 5 J / cm 3 J ;
  • a metal content of metals other than aluminum of less than 1 ppm, for example less than 0.5 ppm, more preferably less than 0.1 ppm;
  • G a standard deviation of the OH content of not more than 10%, preferably not more than 5%, based on the OH content A] of the quartz glass body;
  • H a standard deviation of the Cl content of not more than 10%, preferably not more than 5%, based on the Cl content B] of the quartz glass body;
  • I a standard deviation of the Al content of not more than 10%, preferably not more than 5%, based on the Al content C] of the quartz glass body;
  • L has a tungsten content of less than 1000 ppb, for example less than 500 ppb or less than 300 ppb or less than 100 ppb or in a range of from 1 to 500 ppb or from 1 to 300 ppb, more preferably in one range from 1 to 100 ppb;
  • M] has a molybdenum content of less than 1000 ppb, for example less than 500 ppb or less than 300 ppb or less than 100 ppb or in a range of from 1 to 500 ppb or from 1 to 300 ppb, more preferably in one range from 1 to 100 ppb,
  • ppb and ppm are each based on the total weight of the quartz glass body.
  • a fourth subject of the present invention is a method for manufacturing a light guide comprising the following steps:
  • Step AJ Pulling the precursor from step B / in the heat to obtain a light guide with one or more cores and a shell Ml.
  • the quartz glass body provided in step AJ is a hollow body having at least one opening.
  • the quartz glass body provided in step AJ is preferably characterized by the features according to the third aspect of the invention.
  • the quartz glass body provided in step AJ is preferably obtainable by a method according to the first aspect of the invention as step iv.) Forming a hollow body having at least one opening of the quartz glass body.
  • the quartz glass body obtainable in this way has the features according to the third object of the invention.
  • One or more core rods are introduced through the at least one opening of the quartz glass body (step B /).
  • a core rod in the context of the present invention, an object is referred to, which is intended to be in a shell, for example, a shell Ml, introduced and processed into a light guide.
  • the core rod has a core of quartz glass.
  • the core rod includes a core of quartz glass and a first cladding layer MO surrounding the core.
  • Each core rod has a shape chosen to fit within the quartz glass body.
  • the outer shape of a core rod is in the form of an opening of the quartz glass body.
  • the quartz glass body is a tube and the core rod is a rod with a round cross section.
  • the diameter of the core rod is less than the inner diameter of the hollow body.
  • the diameter of the core rod is 0.1 to 3 mm smaller than the inner diameter of the hollow body, for example 0.3 to 2.5 mm smaller or 0.5 to 2 mm smaller or 0.7 to 1.5 mm smaller, especially preferably 0.8 to 1.2 mm smaller.
  • the ratio of the inside diameter of the quartz glass body to the diameter of the core rod is in the range of 2: 1 to 1,0001: 1, for example in the range of 1.8: 1 to 1.01: 1 or in the range of 1.6: 1 to 1.005: 1 or in the range of 1.4: 1 to 1.01: 1, more preferably in the range of 1.2: 1 to 1.05: 1.
  • a region within the quartz glass body which is not filled by the core rod can be filled with at least one further component, for example a silica powder or a silica granulate.
  • a core rod already located in at least one further quartz glass body can be introduced into a quartz glass body.
  • the further quartz glass body has an outer diameter which is smaller than the inner diameter of the quartz glass body.
  • the core rod introduced into the quartz glass body can also already be located in two or more further quartz glass bodies, for example in 3 or 4 or 5 or 6 or more further quartz glass bodies.
  • the precursor is pulled hot (step C /).
  • the product thus obtained is a light guide with one or more cores and at least one shell Ml.
  • the drawing of the quartz glass body takes place at a speed in the range of 5 to 25 m / h.
  • the drawing is performed in the heat at a temperature of up to 2500 ° C, for example, at a temperature in the range of 1700 to 2400 ° C, more preferably at a temperature in the range of 2100 to 2300 ° C.
  • the precursor is passed through an oven which heats the precursor from outside.
  • the precursor is extended until the desired thickness of the optical fiber is achieved.
  • the precursor is elongated to 1,000 to 6,000,000 times the length, for example, 10,000 to 500,000 times or 30,000 to 200,000 times, each based on the length of the quartz glass body provided in step AI. More preferably, the precursor is elongated to 100,000 to 10,000,000 times the length, for example, 150,000 to 5,800,000 times or 160,000 to 640,000 times or 1,440,000 to 5,760,000 times or 14,400,000 1,440,000 to 2,560,000 times the length, based in each case on the length of the quartz glass body provided in step AI.
  • the diameter of the precursor is reduced by elongation by a factor in a range of 100 to 3,500, for example, in a range of 300 to 3,000 or 400 to 800, or 1,200 to 2,400, or 1,200 to 1,600 in diameter of the quartz glass body provided in step AI.
  • the light guide also referred to as an optical waveguide, may include any material that is suitable for conducting or guiding electromagnetic radiation, in particular light.
  • the optical waveguide conducts electromagnetic radiation in a wavelength range from 170 to 5000 nm.
  • the attenuation of the radiation through the optical waveguide in the respective wavelength range is preferably in a range of 0.1 to 10 dB / km.
  • the optical fiber has a transmission rate of up to 50 Tbit / s.
  • the light guide preferably has a curl parameter of more than 6 m.
  • the curl parameter according to the invention the bending radius of a fiber, e.g. a light guide or a sheath Ml, understood that adjusts itself to a freely movable fiber without external force.
  • the light guide is preferably configured bendable. Bendable in the sense of the invention means that the light guide is characterized by a bending radius of 20 mm or less, for example 10 mm or less, particularly preferably less than 5 mm or less. By a bend radius is meant the narrowest radius that can be formed without causing breakage of the light guide and directing radiation without affecting the ability of the light guide.
  • An impairment is present at an attenuation of the transmitted light by a bend of the light guide by more than 0.1 dB.
  • the attenuation is preferably given at a reference wavelength of 1550 nm.
  • the quartz preferably consists of silicon dioxide with less than 1% by weight of other substances, for example less than 0.5% by weight of other substances, more preferably less than 0.3% by weight of other substances, based in each case on the total weight of the quartz. More preferably, the quartz contains at least 99% by weight of silica, based on the total weight of the quartz.
  • the light guide preferably has an elongated shape.
  • the light guide is defined in its shape by its longitudinal extent L and its cross-section Q.
  • the light guide preferably has a round outer wall along its longitudinal extent L. A cross-section Q of the light guide is always determined in a plane which is perpendicular to the outer wall of the light guide.
  • the light guide preferably has a diameter d L in a range of 0.04 to 1.5 mm.
  • the light guide preferably has a length in a range of 1 m to 100 km.
  • the optical fiber includes one or more cores, for example one or two cores or three cores or four cores or five cores or six cores or seven cores or more than seven cores, more preferably a core.
  • more than 90%, for example more than 95%, more preferably more than 98%, of the electromagnetic radiation conducted through the optical fiber is guided in the cores.
  • the material of the cores is preferably selected from the group consisting of glass or quartz glass, or a combination of the two, particularly preferably quartz glass.
  • the cores can be made of the same material or different materials independently of each other.
  • all cores made of the same material, more preferably made of quartz glass.
  • Each core has a, preferably round, cross-section Q K and has an elongated shape with the length L K.
  • the cross section Q K of a core is independent of the cross section Q K of each other core.
  • the cross sections Q K of the cores may be the same or different.
  • the cross sections QK of all cores are the same.
  • a cross section Q K of a core is always determined in a plane that is perpendicular to the outer wall of the core or the optical fiber outer wall. If a core is curved in the longitudinal extent, the cross-section Q K is determined perpendicular to the tangent at a point on the outer wall of this core.
  • the length L K of a core is independent of the length L K of each other core.
  • the lengths L K of the cores may be the same or different.
  • the lengths L K of all cores are the same.
  • Each core preferably has a length L K in a range of 1 m to 100 km.
  • Each core has a diameter d.
  • the diameter d of a core is independent of the diameter d K of each other core.
  • the diameters d K of the cores may be the same or different.
  • the diameters d K of all cores are the same.
  • the diameter d K of each core in a range of 0.1 to 1000 ⁇ , for example from 0.2 to 100 ⁇ or from 0.5 to 50 ⁇ , more preferably from 1 to 30 ⁇ on.
  • Each core has at least one refractive index profile perpendicular to the maximum core extent.
  • 'Refractive index curve' means that the refractive index is constant or changes perpendicular to the maximum core extent.
  • the preferred refractive index profile corresponds to a concentric refractive index profile, for example a concentric refractive index profile, in which a first region with the maximum refractive index is in the center of the core, followed by another region with a lower refractive index.
  • each core has only one refractive index profile over its length L K.
  • the refractive index profile of a core is independent of the refractive index profile of each additional core.
  • the refractive index profiles of the cores may be the same or different. Preferred are the Refractive index curves of all cores equal. It is also possible in principle for a core to have a multiplicity of different refractive index profiles.
  • Each refractive index profile perpendicular to the maximum core extent has a maximum refractive index n K.
  • Each refractive index profile perpendicular to the maximum core extent may also have further lower refractive indices.
  • the lowest refractive index of the refractive index profile is preferably not more than 0.5 lower than the maximum refractive index n K of the refractive index profile.
  • the lowest refractive index of the refractive index profile is preferably around 0.0001 to 0.15, for example around 0.0002 to 0.1, particularly preferably around 0.0003 to 0.05, less than the maximum refractive index n K of the refractive index profile.
  • n K refractive index
  • the refractive index n K of a core is independent of the refractive index n K of each other core.
  • the refractive indices n K of the cores may be the same or different.
  • the refractive indices n K of all cores are the same.
  • each core of the optical fiber has a density in a range of 1.9 to 2.5 g / cm 3 , for example in a range of 2.0 to 2.4 g / cm 3 , particularly preferably in a range of 2, 1 to 2.3 g / cm 3 .
  • the cores preferably have a residual moisture content of less than 100 ppb, for example less than 20 ppb or less than 5 ppb, particularly preferably less than 1 ppb, in each case based on the total weight of the core.
  • the density of a nucleus is independent of the density of each additional nucleus.
  • the densities of the cores can be the same or different. Preferably, the densities of all cores are the same.
  • each core is characterized by the above features independently of the other cores. It is preferred that all cores have the same characteristics.
  • the cores are according to the invention surrounded by at least one shell Ml.
  • the shell Ml surrounds the cores preferably over the entire length of the cores.
  • the shell Ml surrounds the cores to at least 95%, for example to at least 98% or at least 99%, more preferably 100% of the outer surface, ie the entire outer wall, the cores.
  • the cores are completely up to the ends (each the last 1-5 cm) surrounded by the shell Ml. This serves to protect the cores from mechanical damage.
  • the shell Ml may include any material including silicon dioxide having a lower refractive index than at least one point P in the course of the cross section Q K of the core.
  • this is at least one point in the course of the cross section Q K of the core, the point which lies in the center of the core.
  • the point P in the course of the cross section Q K of the core is the point which has a maximum of the refractive index n Kmax in the core.
  • the shell Ml has a refractive index n M1 which is at least 0.0001 less than the refractive index of the core n K at the at least one point in the course of the cross-section Q of the core.
  • the shell Ml has a refractive index n M1 , which is in a range from 0.0001 to 0.5, for example, in a range of 0.0002 to 0.4, more preferably in a range of 0.0003 to 0.3 is smaller than the refractive index of the core n K.
  • the shell M1 preferably has a refractive index n M1 in a range from 0.9 to 1.599, for example in a range from 1.30 to 1.59, particularly preferably in a range from 1.40 to 1.57.
  • the shell Ml forms a region of the light guide with a constant refractive index n M1 .
  • a range of constant refractive index is understood to mean a range in which the refractive index does not deviate more than 0.0001 from the mean value of the refractive index n M1 in this range.
  • the light guide may include further sheaths.
  • At least one of the further sheaths preferably several or all, has a refractive index which is lower than the refractive index n K of each core.
  • the optical waveguide preferably has one or two or three or four or more than four further sheaths which surround the sheath M1.
  • the further sheaths surrounding the sheath M1 preferably have a refractive index which is lower than the refractive index n M1 of the sheath M1.
  • the optical waveguide preferably has one or two or three or four or more than four further envelopes which surround the cores and are surrounded by the cladding M1, ie lie between the cores and the cladding M1. Further preferably, the other envelopes lying between the cores and the shell Ml have a refractive index which is higher than the refractive index n M1 of the shell Ml.
  • the refractive index preferably decreases from the core of the light guide to the outermost shell.
  • the decrease of the refractive index from the core to the outermost shell may be in steps or continuous.
  • the decrease of the refractive index may have different sections. More preferably, the refractive index may decrease gradually in at least one section and steadily in at least one other section. The steps can be the same or different. It is quite possible to provide sections of increasing refractive index between sections of decreasing refractive index.
  • the different refractive indices of the different sheaths can be adjusted, for example, by doping the sheath M1, the further sheaths and / or the cores.
  • a core may already have a first cladding layer MO after its production.
  • This cladding layer MO immediately adjacent to the core is sometimes referred to as an integral cladding layer.
  • the cladding layer MO is closer to the core center than the cladding M1 and, if included, the other cladding.
  • the cladding layer MO does not serve the light pipe or the radiation pipe. Rather, the cladding layer MO contributes to the radiation remaining within the core and being transported there.
  • the radiation conducted in the core is therefore preferably reflected at the transition from the core into the cladding layer MO.
  • This transition from the core to the cladding layer MO is preferably characterized by a refractive index change.
  • the refractive index of the cladding layer MO is preferably smaller than the refractive index n K of the core.
  • the cladding layer MO includes the same material as the core, but has a lower refractive index than the core due to doping or additives.
  • at least the sheath Ml is made of silicon dioxide and has at least one, preferably several or all of the following features:
  • 3-10 15 / cm 3 more preferably in a range of 0.5-101 1 5 J to 2.0-101 1 5 J / cm 3 J ;
  • h) a standard deviation of the OH content of not more than 10%, preferably not more than 5%, based on the OH content a) of the shell Ml;
  • a transformation point Tg in a range from 1150 to 1250 ° C, particularly preferably in a range from 1180 to 1220 ° C,
  • ppb and ppm are each based on the total weight of the shell Ml.
  • the sheath has a refractive index homogeneity of less than 1-10 "4.
  • the refractive index homogeneity is the maximum deviation of the refractive index at each point of a sample, for example a sheath Ml or a quartz glass body, relative to the average of all the refractive indices determined at the sample.
  • the refractive index is determined at at least seven measuring points.
  • the shell Ml preferably has a metal content of metals other than aluminum of less than 1000 ppb, for example less than 500 ppb, particularly preferably less than 100 ppb, in each case based on the total weight of the shell Ml. Often, however, the shell M1 has a content of metals other than aluminum in an amount of at least 1 ppb.
  • metals include sodium, lithium, potassium, magnesium, calcium, strontium, germanium, copper, molybdenum, titanium, iron and chromium. These may be present, for example, as an element, as an ion, or as part of a molecule or an ion or a complex.
  • the shell Ml may include other ingredients.
  • the shell M1 contains less than 500 ppm, for example less than 450 ppm, more preferably less than 400 ppm of further constituents, the ppm being in each case based on the total weight of the shell M1.
  • Other constituents which may be considered are, for example, carbon, fluorine, iodine, bromine and phosphorus. These may be present, for example, as an element, as an ion, or as part of a molecule or an ion or a complex.
  • the shell M1 has a content of further constituents in an amount of at least 1 ppb.
  • the shell M1 preferably contains carbon at less than 5 ppm, for example less than 4 ppm or less than 3 ppm, more preferably less than 2 ppm, based in each case on the total weight of the shell M1. Often, however, the shell M1 has a content of carbon in an amount of at least 1 ppb.
  • the shell Ml has a homogeneously distributed OH amount, Cl amount or Al amount.
  • the shell Ml has a weight fraction of at least 80 wt .-%. for example, at least 85 wt .-%, particularly preferably at least 90 wt .-%, each based on the total weight of the shell Ml and the cores on.
  • the shell Ml has a weight fraction of at least 80 wt .-%. for example, at least 85 wt .-%, particularly preferably at least 90 wt .-%, each based on the total weight of the shell Ml, the cores and lying between the shell Ml and the cores other shells, on.
  • the shell Ml has a weight fraction of at least 80 wt .-%. for example, at least 85 wt .-%, particularly preferably at least 90 wt .-%, each based on the total weight of the optical fiber on.
  • the shell Ml has a density in a range of 2.1 to 2.3 g / cm 3 , more preferably in a range of 2.18 to 2.22 g / cm 3 .
  • Another aspect relates to a light guide obtainable by a method including the following steps:
  • A2 / a quartz glass body according to the third aspect of the invention wherein the quartz glass body is first processed into a hollow body having at least one opening;
  • step B Pulling the precursor from step B / in the heat to obtain a light guide with one or more cores and a shell Ml.
  • the steps AI, Bl and Cl are preferably characterized by the features described in the context of the fourth subject.
  • the light guide is preferably characterized by that described in the context of the fourth article
  • a fifth subject of the present invention relates to a method for producing a luminous means comprising the following steps:
  • Quartz glass body is first processed into a hollow body
  • a hollow body is provided.
  • the hollow body provided in step (i) includes at least one opening, for example one opening or two openings or three openings or four openings, particularly preferably one opening or two openings.
  • a hollow body having at least one opening obtainable by a method according to the first subject of the invention including step iv.), Is provided (step (i-1)).
  • the hollow body has the features described in the context of the first or third object of the invention.
  • a hollow body is provided which is obtainable from a quartz glass body according to the third object of the invention (step (i-2)). For processing a quartz glass body according to the third subject of the invention to a hollow body, several possibilities come into consideration.
  • a hollow body having two openings can be formed analogously to step iv.) Of the first article of the invention from a quartz glass body.
  • the processing of the quartz glass body into a hollow body with an opening can in principle be effected by means of all methods known to the person skilled in the art and suitable for the production of hollow glass bodies with an opening. For example, methods including pressing, blowing, suction or combinations thereof are suitable. It is also possible to form a hollow body having an opening from a hollow body with two openings by closing an opening, for example by melting together.
  • the resulting hollow body preferably has the features described in the context of the first and third objects of the invention.
  • the hollow body is made of a material containing silicon dioxide, preferably in an amount in a range of 98 to 100 wt .-%, for example in a range of 99.9 to 100 wt .-%, particularly preferably 100 wt .-% , in each case based on the total weight of the hollow body.
  • the material from which the hollow body is made preferably has at least one, preferably several, for example two, or preferably all of the following features:
  • a silicon dioxide content of preferably more than 95% by weight, for example more than
  • HC2. a density in a range of 2.1 to 2.3 g / cm 3 , more preferably in a range of 2.18 to 2.22 g / cm 3 ;
  • HC3. a light transmittance at least one wavelength in the visible range of 350 to
  • HK4 an OH content of less than 500 ppm, for example less than 400 ppm, more preferably less than 300 ppm;
  • HK5. a chlorine content of less than 60 ppm, preferably less than 40 ppm, for example less than 20 or less than 2 ppm, more preferably less than 0.5 ppm; HK6. an aluminum content of less than 200 ppb, for example less than 100 ppb, more preferably less than 80 ppb;
  • HK7 a carbon content of less than 5 ppm, for example less than 4.5 ppm, more preferably less than 4 ppm;
  • HK11 HK11. a transformation point Tg in a range of 1150 to 1250 ° C, more preferably in a range of 1180 to 1220 ° C;
  • ppm and ppb are each based on the total weight of the hollow body.
  • the hollow body from step (i) is filled with a gas, preferably with two electrodes, before it is filled with a gas.
  • the electrodes are connected to an electrical power supply.
  • the electrodes are connected to a lamp base.
  • the material of the electrodes is preferably selected from the group of metals.
  • any metal may be selected as the electrode material that does not oxidize, corrode, melt, or otherwise adversely affect its shape or conductivity as an electrode during the operating conditions of the lamp becomes.
  • the electrode material is preferably selected from the group consisting of iron, molybdenum, copper, tungsten, rhenium, gold and platinum or at least two thereof, with tungsten, molybdenum or rhenium being preferred.
  • the hollow body provided in step (i) and optionally equipped with electrodes in step (ii) is filled with a gas.
  • the filling can be carried out in any manner known to those skilled in the art and suitable for filling.
  • a gas is passed through the at least one opening in the hollow body.
  • the hollow body is evacuated prior to filling with a gas, preferably to a pressure of less than 2 mbar.
  • a gas preferably to a pressure of less than 2 mbar.
  • the hollow body is filled with the gas.
  • These steps can be repeated to minimize contamination with air, especially with oxygen.
  • these steps are repeated at least twice, for example at least three times or at least four times, more preferably at least five times until the amount of impurities with other gases such as air, in particular oxygen, is sufficiently low.
  • This procedure is particularly preferred for filling hollow bodies with an opening. If a hollow body contains two or more openings, the hollow body is preferably filled through one of the openings. The air located in the hollow body before filling with the gas can escape through the at least one further opening.
  • the gas is passed through the hollow body until the amount of contamination with other gases such as air, in particular oxygen is sufficiently low.
  • the hollow body is filled with an inert gas or a combination of two or more inert gases, for example with nitrogen, helium, neon, argon, krypton, xenon or a combination of two or more thereof, more preferably with krypton, xenon or a combination of Nitrogen and argon.
  • Further preferred fillers for hollow bodies of lamps are deuterium and mercury.
  • the hollow body is closed after filling with a gas, so that the gas does not escape during further processing, so that in the further processing no air from the outside, or both. The closing can be done by melting or attaching a closure. Suitable closures are, for example, quartz glass closures, which are for example melted out onto the hollow body, or lamp sockets.
  • the hollow body is closed by melting.
  • the lighting means according to the fifth aspect of the invention includes a hollow body and optionally electrodes.
  • the illuminant preferably has at least one, for example at least two or at least three or at least four, more preferably at least five of the following features:
  • a volume in a range of 0.1 cm 3 to 10 m 3 for example in a range of 0.3 cm 3 to 8 m 3 , particularly preferably in a range of 0.5 cm 3 to 5 m 3 ;
  • 360 ° more preferably in a range of 30 to 360 °;
  • a radiation of light in a wavelength range of 145 to 4000 nm for example in a range of 150 to 450 nm, or of 800 to 4000 nm, particularly preferably in a range of 160 to 280 nm;
  • V. a power in a range of 1 mW to 100 kW, more preferably in a range of 1 kW to 100 kW, or in a range of 1 to 100 watts.
  • Another aspect relates to a lighting device obtainable by a method comprising the following steps:
  • steps (i), (ii) and (iii) are preferably characterized by the features described in the context of the fifth subject.
  • the luminous means is preferably characterized by the features described in the context of the fifth object.
  • a sixth aspect of the present invention relates to a method for producing a shaped article comprising the following steps:
  • the quartz glass body provided in step (1) is a quartz glass body according to the third aspect of the invention or obtainable by a method according to the first aspect of the invention.
  • the provided quartz glass body has the features of the first or third aspect of the invention.
  • the quartz glass body is formed into a shaped body as described in the first, fourth and fifth articles of the invention. More preferably, the shaped body can be formed by means of techniques known to glass blowers. In principle, the shaped body can assume any shape which can be shaped from quartz glass. Preferred shaped bodies are, for example:
  • Hollow body with at least one opening such as round-bottomed flasks and stand-up flasks,
  • Tubes and hollow cylinders for example reaction tubes, profile tubes, rectangular chambers,
  • Rods, rods and blocks for example in round or angular, symmetrical or asymmetrical design
  • bent parts for example convex or concave surfaces and plates, bent bars and tubes.
  • the shaped body can be treated after molding.
  • all methods described in connection with the first subject of the invention which are suitable for reworking the quartz glass body come into consideration.
  • the shaped body can be mechanically processed, for example by drilling, honing, external grinding, crushing or drawing.
  • Another aspect relates to a molded article obtainable by a method including the following steps:
  • steps (1) and (2) molding the quartz glass body to obtain the molded body.
  • the steps (1) and (2) are preferably characterized by the features described in the context of the sixth subject.
  • the molded body is preferably characterized by the features described in the context of the sixth article.
  • a seventh object of the present invention is the use of a silica powder prepared from a silicon-chlorine compound for the production of quartz glass and of products comprising quartz glass selected from the group consisting of a light guide, a luminous means and a shaped body.
  • the silica powder preferably has the following features:
  • a BET surface area in a range of 10 to 70 m 2 / g; and a bulk density of in a range of 0.01 to 0.3 g / cm 3 .
  • FIG. 2 is a flowchart (method for producing a silica granule 1)
  • FIG. 3 shows a flow chart (method for producing a silica granulate ⁇ 1)
  • FIG. 5 shows a flow chart (method for producing a luminous means)
  • FIG. 6 schematic representation of a hanging crucible in an oven
  • FIG. 7 schematic representation of a standing crucible in an oven
  • Fig. 8 is a schematic representation of a crucible with a purge ring
  • FIG. 9 schematic representation of a spray tower
  • Fig. 10 is a schematic representation of a cross section of a light guide
  • Fig. 11 is a schematic representation of a plan view of a light guide
  • Fig. 12 is a schematic representation of a crucible with a dew point measuring device
  • FIG. 14 Flowchart (Method for Producing a Molded Body)
  • FIG. 1 shows a flow chart containing steps 101 to 104 of a method 100 for producing a quartz glass body according to the present invention.
  • a silica granulate is provided in a first step 101.
  • a glass melt is formed from the silica granules in a second step 102.
  • molds are used for melting, which can be introduced into an oven and removed from it again.
  • Such forms are often made of graphite. They result in a negative mold of the casting.
  • the silica granules are filled into the mold, first melted in the mold in the third step 103.
  • the quartz glass body is formed in the same mold by cooling the melt.
  • This is then removed from the mold and processed further, for example in an optional step 104.
  • This procedure is discontinuous.
  • the formation of the melt is preferably carried out under reduced pressure, in particular under vacuum. It is also possible to temporarily charge the furnace with a reducing, hydrogen-containing atmosphere during step 103.
  • a quartz glass body is formed.
  • the formation of the quartz glass body is preferably carried out here by removing at least a portion of the glass melt from the crucible and cooling. The removal preferably takes place through a nozzle at the lower end of the crucible. In this case, the shape of the quartz glass body
  • REPORTED SHEET (RULE 91) ISA / EP be determined by the design of the nozzle.
  • massive bodies can be obtained.
  • Hollow bodies are obtained, for example, if a mandrel is additionally provided in the nozzle.
  • This exemplary method for the production of quartz glass bodies, and in particular step 103, is preferably carried out continuously. From a solid quartz glass body can be formed in an optional step 104, a hollow body.
  • FIG. 2 shows a flow chart containing the steps 201 to 204 of a method 200 for producing a silicon dioxide granulate I.
  • a silicon dioxide powder is provided.
  • a silica powder is preferably obtained from a synthetic process in which a silicon tetrachloride is converted to silica in a pyrogenic process.
  • the silica powder is contacted with water vapor to obtain a treated silica powder.
  • the treated silica powder has a lower chlorine content than the silica powder before the steam treatment.
  • the treated silica powder is mixed with a liquid, preferably water, to obtain a slurry of the treated silica powder.
  • a fourth step 204 the silica contained in the slurry is converted into a silica granulate, preferably by means of spray granulation.
  • the slurry is sprayed into a spray tower and dried to form granules.
  • FIG. 3 Production of silicon dioxide granules II
  • FIG. 3 shows a flow chart containing the steps 301, 302, 303 and 304 of a method 300 for producing a silica granulate ⁇ .
  • Steps 301, 302 and 303 run in accordance with steps 201, 202 and 203 according to FIG. 2.
  • the silicon dioxide granulate I obtained in step 303 is processed into a silicon dioxide granulate E. This is preferably done by heating the silica granules I in a chlorine-containing atmosphere.
  • FIG. 4 shows a flowchart containing the steps 401, 403 and 404 as well as the optional step 402 of a method for producing a light guide.
  • a quartz glass body is provided, preferably a quartz glass body produced according to method 100.
  • Such a quartz glass body may be a solid or a hollow quartz glass body.
  • a hollow quartz glass body corresponding to step 104 is formed in a second step 402.
  • one or more than one core rod is introduced into the hollow quartz glass body.
  • the quartz glass body provided with one or more than one core rod is processed to form a light guide.
  • the quartz glass body provided with one or more than one core rod is preferably heated to soften and elongated until the desired optical fiber thickness is reached.
  • FIG. 5 shows a flow chart including steps 501, 503 and 504 and optional step 502 of FIG
  • a quartz glass body is provided, preferably a quartz glass body produced according to method 100.
  • a quartz glass body may be a solid or a hollow quartz glass body.
  • the quartz glass body provided in step 501 is solid, it becomes a second step 502 optionally formed into a hollow quartz glass body according to step 104.
  • the hollow quartz glass body is equipped with electrodes.
  • the hollow quartz glass body is filled with a gas, preferably with argon, krypton, xenon or a combination thereof.
  • a solid quartz glass body is initially provided (501), shaped into a hollow body (502), equipped with electrodes (503) and filled with a gas (504).
  • FIG. 6 shows a preferred embodiment of a furnace 800 with a hanging crucible.
  • the crucible 801 is suspended in the furnace 800.
  • the crucible 801 has in its upper region a suspension 802, as well as a solids inlet 803 and a nozzle 804 as an outlet.
  • the crucible 801 is filled with silica granules 805 via the solids inlet 803.
  • silicon dioxide granules 805 are present in the upper region of the crucible 801, while a glass melt 806 is present in the lower region of the crucible 801.
  • the crucible 801 can be heated by heating elements 807, which are arranged on the outside of the crucible wall 810.
  • the furnace also has an insulation layer 809 between the heating elements 807 and the furnace outer wall 808.
  • the space between the insulating layer 809 and the crucible wall 810 may be filled with a gas and has a gas inlet 811 and a gas outlet 812 thereto.
  • a quartz glass body 813 can be removed from the oven.
  • FIG. 7 shows a preferred embodiment of a furnace 900 with a standing crucible.
  • the crucible 901 is arranged standing in the furnace 900.
  • the crucible 901 has a footprint 902, a solids inlet 903 and a nozzle 904 as an outlet.
  • the crucible 901 is filled via the inlet 903 with silicon dioxide granules 905.
  • silicon dioxide granules 905 are present in the upper region of the crucible, while a glass melt 906 is present in the lower region of the crucible.
  • the crucible can be heated by heating elements 907, which are arranged on the outside of the crucible wall 910.
  • the furnace also has an insulation layer 909 between the heating elements 907 and the furnace outer wall 908.
  • the space between the insulating layer 909 and the crucible wall 910 may be filled with a gas and has a gas inlet 91 1 and a gas outlet 912 thereto. Through the nozzle 904, a quartz glass body 913 can be removed from the crucible 901.
  • FIG. 8 shows a preferred embodiment of a crucible 1000.
  • the crucible 1000 has a solids inlet 1001 and a nozzle 1002 as an outlet.
  • the crucible 1000 is filled with silica granules 1003 via the solids inlet 1001.
  • silicon dioxide granules 1003 are present as bulk cone 1004, while a glass melt 1005 is present in the lower region of the crucible.
  • the crucible 1000 can be filled with a gas. It has a gas inlet 1006 and a gas outlet 1007-on.
  • the gas inlet is a purge ring mounted above the silica granules on the crucible wall.
  • FIG. 9 shows a preferred embodiment of a spray tower 1100 for spray granulating
  • the spray tower 1 100 comprises a feed 1 101, through which a pressurized Slurry containing silica powder and a liquid is supplied to the spray tower.
  • a nozzle 1102 At the end of the line is a nozzle 1102, through which the slurry is finely distributed in the spray tower - is introduced.
  • the nozzle is oriented obliquely upwards so that the slurry is sprayed as fine droplets in the direction of the nozzle orientation in the spray tower and then falls down in a bow driven by gravity.
  • a gas inlet 1103. By introducing a gas through the gas inlet 1103, a gas flow directed counter to the exit direction of the slurry from the nozzle 1102 is created.
  • the spray tower 1 100 also comprises a sighting device 1 104 and a screening device 1105.
  • a sighting device 1 104 particles are sucked off, which fall below a defined particle size, and removed by the discharge 1106.
  • the suction power of the sighting device 1104 can be regulated.
  • the sieve device 1105 particles are screened above a defined particle size and removed by the discharge 1 107.
  • the sieve permeability of the sieving apparatus 1105 can be selected. The remaining particles, a silica granule of the desired particle size, are withdrawn through the outlet 1108.
  • FIG. 10 schematically shows a cross section through an optical waveguide 1200 according to the invention, which has a core 1201 and a shell Ml] 202 surrounding the core 1201.
  • FIG. 11 schematically shows a plan view of an optical waveguide 1300 which has a cable-shaped structure.
  • a part of the core 1301 without cladding M1 1302 was shown.
  • typical is the cladding of the core 1301 over its entire length with the shell Ml 1302.
  • FIG. 12 shows a preferred embodiment of a crucible 1400.
  • the crucible has a solids inlet 1401 and an outlet 1402.
  • 1400 silicon dioxide granules 1403 are present in a bulk cone 1404 in the upper region of the crucible, while a glass melt 1405 is present in the lower region of the crucible.
  • the crucible 1400 has a gas inlet 1406 and a gas outlet 1407.
  • the gas inlet 1406 and the gas outlet 1407 are arranged above the bulk cone 1404 of the silicon dioxide granules 1403.
  • the gas outlet 1406 includes a gas guide 1408 and a device 1409 for measuring the dew point of the exiting gas.
  • the device 1409 includes a dew point mirror hygrometer (not shown). The distance between the crucible and the dew point measuring device 1409 may vary.
  • a quartz glass body 1410 can be removed.
  • FIG 13 shows a preferred embodiment of a furnace 1500 which is suitable for a vacuum sintering process, a gas pressure sintering process and in particular a combination thereof.
  • the oven has a pressure-resistant casing 1501 and a thermal insulating layer 1502 from outside to inside.
  • the enclosed space as
  • Oven inside designated can be acted upon via a gas supply 1504 with a gas or a gas mixture. Furthermore, the oven interior is provided with a gas outlet 1505, can be removed via the gas.
  • heating elements 1506 provided. These are often attached to the insulating layer 1502 (not here shown). To protect the melt from contamination, the interior of the furnace is provided with a so-called “liner” 1507 which separates the furnace chamber 1503 from the heating elements 1506. Melt molds 1508 with melt 1509 can be introduced into the furnace chamber 1503. The melt mold 1 508 can be placed on a Side open (shown here) or the melt 1509 completely surrounded (not shown).
  • FIG. 14 shows a flow chart containing the steps 1601 and 1602 of a method for producing a shaped body.
  • a quartz glass body is provided, preferably a quartz glass body produced according to method 100.
  • Such a quartz glass body may be a solid or a hollow quartz glass body.
  • a shaped body is formed in a second step 1602.
  • the fictive temperature is determined by means of Raman spectroscopy on the basis of the Raman scattering intensity at approximately 606 cm -1
  • the procedure and evaluation is described in the article by Pfleiderer et al., The UV-induced 210 nm absorption band in fused silica with different thermal history and stoichiometry. ; Journal of Non-Crystalline Solids, Vol. 159 (1993), pages 145-153. b. OH-content
  • the OH content of the glass is determined by infrared spectroscopy.
  • the method "Optical Determinations of OH in Fused Silica” (JAP 37, 3991 (1966)) specified by DM Dodd & DM Fraser is used instead of the device specified therein, an FTIR spectrometer (Fourier transform infrared spectrometer, current System 2000 from Perkin Elmer)
  • the evaluation of the spectra can in principle be carried out both at the absorption band at about 3670 cm -1 and at the absorption band at about 7200 cm -1 in that the transmission loss due to OH absorption is between 10 and 90% c.
  • Oxygen Deficiency Centers ODCs
  • ODC (I) absorption at 165 nm is determined by means of a transmission measurement on a 1-2 mm thick sample using a vacuum UV spectrometer, model VUVAS 2000, from McPherson, Inc. (USA).
  • N defect concentration [l / cra 3 ]
  • ⁇ optical absorption [1 / cm, base e] of the ODC (I) band
  • OES or MS depends on the expected element concentration. Typical determination limits for the MS are lppb, for the OES lOppb (in each case based on the weighted sample amount).
  • the determination of the element concentration with the measuring instruments is carried out in accordance with the equipment manufacturers (ICP-MS: Agilent 7500ce, ICP-OES: Perkin Elmer 7300 DV) and using certified reference liquids for calibration.
  • the element concentration in the solution (15 ml) determined by the devices is then converted to the original sample weight (2 g).
  • a well-defined volume of the liquid is weighed into a measuring vessel which is inert with respect to the liquid and its constituents, the empty weight and the weight of the filled vessel being measured.
  • the density results from the difference between the two weight measurements divided by the volume of liquid introduced.
  • the determination of the fluoride content of the measurement solution is carried out by means of an ion-sensitive (fluoride) electrode, suitable for the expected concentration range, and display device according to the manufacturer, here a fluoride ion-selective electrode and reference electrode F-500 with R503 / D on a pMX 3000 / pH / ION of the companyticianlich-Technische Werkmaschinen GmbH.
  • an ion-sensitive (fluoride) electrode suitable for the expected concentration range
  • display device here a fluoride ion-selective electrode and reference electrode F-500 with R503 / D on a pMX 3000 / pH / ION of the companyticianlich-Technische Werkmaschinen GmbH.
  • the measuring solution has a pH in the range between 5 and 7.
  • the determination of the chloride content of the measuring solution is carried out by means of ion-sensitive (chloride) electrode, suitable for the expected concentration range, and display device according to the manufacturer's instructions here a type Cl-500 electrode and reference electrode type R-503 / D on a pMX 3000 / pH / ION the company Scientific-Technical Workshops GmbH.
  • chloride ion-sensitive
  • Chlorine content ( ⁇ 50 ppm) Chlorine contents ⁇ 50 ppm up to 0.1 ppm in quartz glass are determined by neutron activation analysis (NAA).
  • NAA neutron activation analysis
  • 3 drill bits each with a diameter of 3 mm and a length of 1 cm each are drawn from the quartz glass body to be examined.
  • quartz glass samples The transmission of quartz glass samples is determined using commercial grid or FTIR spectrometers from Perkin Elmer (Lambda 900 [190-3000nm] or System 2000 [1000-5000nm]). The choice depends on the required measuring range. To determine the absolute transmission, the specimens are polished plane-parallel
  • sample thickness is 1cm. In the case of expected high transmission loss due to contamination, doping, etc., a thicker or thinner sample can also be selected to remain within the instrument's measuring range. A sample thickness (measuring length) is selected in which, due to the passage of light through the sample, only slight artifacts occur and at the same time a sufficiently detectable effect is measured.
  • the sample is placed in front of an Ulbrich sphere in the beam path.
  • the refractive index distribution of tubes / rods can be determined by means of a York Technology Ltd. Preform Profiler PI 02 or PI 04.
  • the rod is placed horizontally in the measuring chamber and this sealed. Thereafter, the measuring chamber is filled up with an immersion oil which has a refractive index at the test wavelength of 633nm, which is very similar to the outermost glass layer at 633nm.
  • the laser beam then passes through the measuring chamber. Behind the measuring chamber (in beam direction) a detector is mounted, which determines the deflection angle (jet entry in opposite to jet exit from the measuring chamber).
  • the diametric refractive index profile can be reconstructed by means of an inverse Abel transformation.
  • the refractive index of a sample is analogous to the above description with the York Technology Ltd. Preform Profiler PI 04 determined. In the case of isotropic samples, only one value is obtained even when measuring the refractive index distribution, the refractive index. Carbon content
  • the quantitative determination of the surface carbon content of silica granules and silica powder is carried out on a carbon analyzer RC612 from Leco Corporation, USA, by the complete oxidation of all surface carbon contaminants (except SiC) with oxygen to carbon dioxide.
  • a carbon analyzer RC612 from Leco Corporation, USA
  • 4.0 g of a sample are weighed and introduced into the carbon analyzer in a quartz glass boat.
  • the sample is lapped with pure oxygen and heated to 900 ° C for 180 seconds.
  • the resulting C0 2 is detected by the infrared detector of the carbon analyzer. Under these measurement conditions, the detection limit is ⁇ 1 ppm (ppm by weight) carbon.
  • quartz glass boat is available as a consumable for LECO analyzer with the LECO number 781-335 in the laboratory supplies trade, in the present case of Deslis laboratory trade, Flur No 21, D-40235 Dusseldorf (Germany), Deslis- No. LQ-130XL.
  • Such a boat has the dimensions of width / length / height of about 25mm / 60mm / 15mm.
  • the quartz glass boat is filled halfway up with sample material. For silicon dioxide powder, a weight of 1.0 g of sample material can be achieved in this way. The lower detection limit is then ⁇ 1 ppm by weight of carbon.
  • a weight of 4 g of a silica granules is reached (average particle size in the range of 100 to 500 ⁇ ).
  • the lower detection limit is then about 0.1 ppm by weight of carbon.
  • the Curl parameter (also called: "Fiber Curl”) is determined in accordance with DIN EN 60793-1-34: 2007-01 (German version of the standard IEC 60793-1-34: 2006) in the sections A.2.1, A.3.2 and A.4.1 ("extrema technique"). m. damping

Landscapes

  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Organic Chemistry (AREA)
  • Materials Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Physics & Mathematics (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Optics & Photonics (AREA)
  • General Life Sciences & Earth Sciences (AREA)
  • Inorganic Chemistry (AREA)
  • Thermal Sciences (AREA)
  • Dispersion Chemistry (AREA)
  • General Physics & Mathematics (AREA)
  • Glass Melting And Manufacturing (AREA)
  • Silicon Compounds (AREA)
  • Glass Compositions (AREA)

Abstract

L'invention concerne un procédé pour produire un corps en verre de silice, qui comprend les étapes suivantes consistant à : i.) préparer un granulat de dioxyde de silicium, ii.) former un bain de verre fondu à partir du granulat de dioxyde de silicium et iii.) former un corps en verre de silice à partir d'au moins une partie du bain de verre fondu, l'étape de préparation comprenant les étapes consistant à I. réaliser une poudre de dioxyde de silicium ayant au moins deux particules à partir d'un composé de silicium et de chlore, II. mettre en contact la poudre de dioxyde de silicium avec de la vapeur d'eau afin d'obtenir une poudre de dioxyde de silicium traitée et III. réaliser la granulation de la poudre de dioxyde de silicium traitée afin d'obtenir un granulat de dioxyde de silicium, la teneur en chlore de la poudre de dioxyde de silicium étant supérieure à celle du granulat de dioxyde de silicium. L'invention concerne également un corps en verre de silice pouvant être obtenu au moyen de ce procédé. L'invention concerne également un procédé pour produire un granulat de dioxyde de silicium. L'invention concerne en outre un guide d'ondes optiques, une source lumineuse et un corps moulé pouvant chacun être obtenus par traitement ultérieur du corps en verre de silice.
EP16822951.6A 2015-12-18 2016-12-16 Traitement à la vapeur d'eau d'une poudre de dioxyde de silicium lors de la fabrication de verre de silice Withdrawn EP3390309A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP15201111 2015-12-18
PCT/EP2016/081523 WO2017103170A1 (fr) 2015-12-18 2016-12-16 Traitement à la vapeur d'eau d'une poudre de dioxyde de silicium lors de la fabrication de verre de silice

Publications (1)

Publication Number Publication Date
EP3390309A1 true EP3390309A1 (fr) 2018-10-24

Family

ID=54850385

Family Applications (1)

Application Number Title Priority Date Filing Date
EP16822951.6A Withdrawn EP3390309A1 (fr) 2015-12-18 2016-12-16 Traitement à la vapeur d'eau d'une poudre de dioxyde de silicium lors de la fabrication de verre de silice

Country Status (6)

Country Link
US (1) US20190062194A1 (fr)
EP (1) EP3390309A1 (fr)
JP (1) JP2019502634A (fr)
CN (1) CN108698884A (fr)
TW (1) TW201733932A (fr)
WO (1) WO2017103170A1 (fr)

Families Citing this family (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017103131A1 (fr) 2015-12-18 2017-06-22 Heraeus Quarzglas Gmbh & Co. Kg Diminution de la teneur en métaux alcalino-terreux d'un granulat de dioxyde de silicium par traitement à haute température de granulat de dioxyde de silicium dopé au carbone
KR20180095624A (ko) 2015-12-18 2018-08-27 헤래우스 크바르츠글라스 게엠베하 ＆ 컴파니 케이지 불투명 실리카 유리 제품의 제조
EP3390302B1 (fr) 2015-12-18 2023-09-20 Heraeus Quarzglas GmbH & Co. KG Fabrication d'un corps en verre de quartz dans un creuset contenant du molybdène ou du tungstène
TWI794150B (zh) 2015-12-18 2023-03-01 德商何瑞斯廓格拉斯公司 自二氧化矽顆粒製備石英玻璃體
KR20180095880A (ko) 2015-12-18 2018-08-28 헤래우스 크바르츠글라스 게엠베하 ＆ 컴파니 케이지 합성 석영 유리 결정립의 제조
US11952303B2 (en) 2015-12-18 2024-04-09 Heraeus Quarzglas Gmbh & Co. Kg Increase in silicon content in the preparation of quartz glass
KR20180095616A (ko) 2015-12-18 2018-08-27 헤래우스 크바르츠글라스 게엠베하 ＆ 컴파니 케이지 용융 가열로에서 이슬점 조절을 이용한 실리카 유리체의 제조
EP3390304B1 (fr) 2015-12-18 2023-09-13 Heraeus Quarzglas GmbH & Co. KG Granulation par pulverisation de dioxyde de silicium lors de la fabrication de verre de quartz
TWI788278B (zh) 2015-12-18 2023-01-01 德商何瑞斯廓格拉斯公司 由均質石英玻璃製得之玻璃纖維及預成型品
TW201731782A (zh) 2015-12-18 2017-09-16 何瑞斯廓格拉斯公司 在多腔式爐中製備石英玻璃體
EP4003923A1 (fr) * 2019-07-24 2022-06-01 Heraeus Quarzglas GmbH & Co. KG Procédé de préparation d'une suspension d'oxyde de silicium

Family Cites Families (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE1642994A1 (de) * 1967-01-21 1971-06-03 Degussa Verfahren zum Reinigen von hochdispersen Oxiden
JPS60260434A (ja) * 1984-06-04 1985-12-23 Shin Etsu Chem Co Ltd 光伝送用無水ガラス素材の製造方法
US5141786A (en) * 1989-02-28 1992-08-25 Shin-Etsu Chemical Co., Ltd. Synthetic silica glass articles and a method for manufacturing them
US6136736A (en) * 1993-06-01 2000-10-24 General Electric Company Doped silica glass
JP3751326B2 (ja) * 1994-10-14 2006-03-01 三菱レイヨン株式会社 高純度透明石英ガラスの製造方法
JP3546494B2 (ja) * 1994-10-27 2004-07-28 信越化学工業株式会社 微細シリカの精製法
US5855860A (en) * 1994-10-27 1999-01-05 Shin-Etsu Chemical Co., Ltd. Method for porifying fine particulate silica
DE10123950A1 (de) * 2001-05-17 2002-11-28 Degussa Granulate auf Basis von mittels Aerosol mit Aluminiumoxid dotiertem, pyrogen hergestelltem Siliziumdioxid, Verfahren zu ihrer Herstellung und ihre Verwendung
US20040118155A1 (en) * 2002-12-20 2004-06-24 Brown John T Method of making ultra-dry, Cl-free and F-doped high purity fused silica
JP4470479B2 (ja) * 2003-12-17 2010-06-02 旭硝子株式会社 光学部材用合成石英ガラスおよびその製造方法
US7166963B2 (en) * 2004-09-10 2007-01-23 Axcelis Technologies, Inc. Electrodeless lamp for emitting ultraviolet and/or vacuum ultraviolet radiation
EP1700824A1 (fr) * 2005-03-09 2006-09-13 Degussa AG Granulés à base de silice pyrogenique, procédé pour leur obtention, utilisation de ceux-ci
EP1700828A1 (fr) * 2005-03-09 2006-09-13 Degussa AG Procédé de fabrication de corps en verre de très haute pureté et de qualité optique
EP1717202A1 (fr) * 2005-04-29 2006-11-02 Degussa AG Matériaux frittés de silice
DE102006039273A1 (de) * 2006-08-22 2008-02-28 Evonik Degussa Gmbh Pyrogenes Siliciumdioxid zur Verwendung als Hilfsstoff in pharmazeutischen und kosmetischen Zusammensetzungen
CN101511744B (zh) * 2006-09-11 2012-11-14 东曹株式会社 熔融石英玻璃及其制造方法
WO2009096557A1 (fr) * 2008-01-30 2009-08-06 Asahi Glass Co., Ltd. Préforme de fibre optique utilisée pour la transmission d'énergie ou la transmission de lumière ultraviolette et procédé de fabrication de la préforme de fibre optique

Also Published As

Publication number Publication date
JP2019502634A (ja) 2019-01-31
CN108698884A (zh) 2018-10-23
US20190062194A1 (en) 2019-02-28
WO2017103170A1 (fr) 2017-06-22
TW201733932A (zh) 2017-10-01

Similar Documents

Publication Publication Date Title
EP3390293B1 (fr) Augmentation de la teneur en silicium lors de la fabrication de verre de quartz
EP3390294B1 (fr) Diminution de la teneur en metaux alcalino-terreux de granules de silice par traitement a haute temperature de granules de silice enrichies en carbone
EP3390296B1 (fr) Fabrication d'un corps en verre de quartz dans un four multi-chambres
EP3390305B1 (fr) Fabrication de corps de verre de quartz a partir de granules de dioxyde de silicium
EP3390303B1 (fr) Fabrication de corps de verre de quartz avec controle de point de rosee dans le four de fusion
WO2017103170A1 (fr) Traitement à la vapeur d'eau d'une poudre de dioxyde de silicium lors de la fabrication de verre de silice
WO2017103156A2 (fr) Fabrication de corps en verre de silice à partir de poudre de dioxyde de silicium
WO2017103133A1 (fr) Fabrication et post-traitement d'un corps en verre de silice
EP3390304B1 (fr) Granulation par pulverisation de dioxyde de silicium lors de la fabrication de verre de quartz
EP3390302B1 (fr) Fabrication d'un corps en verre de quartz dans un creuset contenant du molybdène ou du tungstène
WO2017103171A9 (fr) Traitement à l'ammoniac d'une poudre de dioxyde de silicium lors de la fabrication de verre de silice
EP3390297A1 (fr) Barbotage pour four de fusion et procédé de fabrication de verre de silice
EP3390306A2 (fr) Fabrication d'un corps en verre de silice dans un creuset fritté suspendu
EP3390300A1 (fr) Fabrication d'un corps en verre de silice dans un creuset fritté debout
WO2017103121A2 (fr) Fabrication d'un corps en verre de silice opaque
EP3390307A2 (fr) Réduction de la teneur en carbone d'un granulat de dioxyde de silicium et fabrication d'un corps de verre de silice
WO2017103112A1 (fr) Fabrication d'un corps en verre de silice dans un creuset en tôle suspendu
WO2017103120A1 (fr) Production de grains de verre de silice synthétiques

Legal Events

Date Code Title Description
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: UNKNOWN

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE INTERNATIONAL PUBLICATION HAS BEEN MADE

PUAI Public reference made under article 153(3) epc to a published international application that has entered the european phase

Free format text: ORIGINAL CODE: 0009012

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: REQUEST FOR EXAMINATION WAS MADE

17P Request for examination filed

Effective date: 20180713

AK Designated contracting states

Kind code of ref document: A1

Designated state(s): AL AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HR HU IE IS IT LI LT LU LV MC MK MT NL NO PL PT RO RS SE SI SK SM TR

AX Request for extension of the european patent

Extension state: BA ME

DAV Request for validation of the european patent (deleted)
DAX Request for extension of the european patent (deleted)
STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: EXAMINATION IS IN PROGRESS

17Q First examination report despatched

Effective date: 20200508

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: EXAMINATION IS IN PROGRESS

STAA Information on the status of an ep patent application or granted ep patent

Free format text: STATUS: THE APPLICATION IS DEEMED TO BE WITHDRAWN

RAP3 Party data changed (applicant data changed or rights of an application transferred)

Owner name: HERAEUS QUARZGLAS GMBH & CO. KG

18D Application deemed to be withdrawn

Effective date: 20220701