EP3013770A1 - Procédé de fabrication de granulés - Google Patents

Procédé de fabrication de granulés

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Publication number
EP3013770A1
EP3013770A1 EP14724010.5A EP14724010A EP3013770A1 EP 3013770 A1 EP3013770 A1 EP 3013770A1 EP 14724010 A EP14724010 A EP 14724010A EP 3013770 A1 EP3013770 A1 EP 3013770A1
Authority
EP
European Patent Office
Prior art keywords
finished product
binder
semi
temperature
mixture
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Withdrawn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
EP14724010.5A
Other languages
German (de)
English (en)
Inventor
Wolfgang RÜCKERT
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.)
Imerys Metalcasting Germany GmbH
Original Assignee
S & B Industrial Minerals GmbH
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 S & B Industrial Minerals GmbH filed Critical S & B Industrial Minerals GmbH
Publication of EP3013770A1 publication Critical patent/EP3013770A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/03—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite
    • C04B35/06—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on magnesium oxide, calcium oxide or oxide mixtures derived from dolomite based on oxide mixtures derived from dolomite
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B22—CASTING; POWDER METALLURGY
    • B22D—CASTING OF METALS; CASTING OF OTHER SUBSTANCES BY THE SAME PROCESSES OR DEVICES
    • B22D11/00—Continuous casting of metals, i.e. casting in indefinite lengths
    • B22D11/10—Supplying or treating molten metal
    • B22D11/11—Treating the molten metal
    • B22D11/111—Treating the molten metal by using protecting powders
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/62605—Treating the starting powders individually or as mixtures
    • C04B35/62695—Granulation or pelletising
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/622—Forming processes; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
    • C04B35/6303—Inorganic additives
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B38/00—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof
    • C04B38/02—Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof by adding chemical blowing agents
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
    • C04B2111/00474—Uses not provided for elsewhere in C04B2111/00
    • C04B2111/0087—Uses not provided for elsewhere in C04B2111/00 for metallurgical applications
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3205—Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
    • C04B2235/3206—Magnesium oxides or oxide-forming salts thereof
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3205—Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
    • C04B2235/3208—Calcium oxide or oxide-forming salts thereof, e.g. lime
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3205—Alkaline earth oxides or oxide forming salts thereof, e.g. beryllium oxide
    • C04B2235/3208—Calcium oxide or oxide-forming salts thereof, e.g. lime
    • C04B2235/321—Dolomites, i.e. mixed calcium magnesium carbonates
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/02—Composition of constituents of the starting material or of secondary phases of the final product
    • C04B2235/30—Constituents and secondary phases not being of a fibrous nature
    • C04B2235/44—Metal salt constituents or additives chosen for the nature of the anions, e.g. hydrides or acetylacetonate
    • C04B2235/443—Nitrates or nitrites
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/65—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes
    • C04B2235/656—Aspects relating to heat treatments of ceramic bodies such as green ceramics or pre-sintered ceramics, e.g. burning, sintering or melting processes characterised by specific heating conditions during heat treatment
    • C04B2235/6562—Heating rate
    • C—CHEMISTRY; METALLURGY
    • C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
    • C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
    • C04B2235/00—Aspects relating to ceramic starting mixtures or sintered ceramic products
    • C04B2235/70—Aspects relating to sintered or melt-casted ceramic products
    • C04B2235/74—Physical characteristics
    • C04B2235/77—Density

Definitions

  • the invention relates to a process for the production of granules, in particular for use as thermal insulation for a molten metal and preferably for molten steel, after which a powdered solid or a powdered mineral raw material mixed with a binder or an adjuvant or excipient mixture and granulated the mixture to a semi-finished product becomes.
  • thermal insulation is generally achieved by means of a low bulk density of the thermal insulation agent.
  • thermal insulation materials are used particularly in the course of steelmaking in order to protect molten steel from possible heat loss on its way through the various stages of production.
  • the covering means can additionally be used to absorb impurities from the molten metal.
  • impurities eg. As alumina
  • the covering can partially melt by changing its chemical composition.
  • the cover must not completely melt to his
  • thermal insulation would make it possible to reduce the consumption of raw materials in metal production and to conserve global resources, since less material would be needed for the purpose of thermal insulation.
  • Such a method is described in DE 197 31 653 C2.
  • This is a process for the production of beads or pellets of rice husk ash, which are used as a thermal insulation material and thus covering means for a molten metal.
  • the thermal insulation material is used for thermal insulation of molten steel.
  • thermal insulation materials are used particularly in the course of steelmaking in order to protect molten steel from possible heat loss on its way through the various stages of production.
  • such granules are typically applied to the surface of the molten metal or steel surface as a covering agent.
  • the covering should also shield the molten steel or molten metal from atmospheric gases and avoid unwanted chemical reactions of the molten metal. Another requirement is that such covering agents should not be hazardous to health and / or the environment.
  • EP 1 572 399 B1 is concerned with a covering agent or covering material for covering the free surface of a molten steel bath in an open metallurgical vessel.
  • the covering agent is used in particular in steelmaking in the field of pig iron and secondary metallurgy and in continuous casting and forms a so-called top slag.
  • a porous granules is used whose grains have a porosity of 5 to 70% by volume.
  • the granules consist of calcium aluminates. This should be ensured overall easier insulation.
  • EP 2 573 058 A1 which is still to be considered and which is also generic, deals with a granulate which contains at least one agglomerated reactive bulk material and a binder matrix.
  • Binder matrix is composed of at least one organic or inorganic salt as a binder. In this way, an agglomeration without the aid of water and avoiding high temperatures to be achieved.
  • the state of the art can not convince in all aspects. So health hazards of the covering materials or granules used are still not excluded. In addition, environmental hazards can not be prevented and the processing of the known covering agents is in some cases problematical. Here, the invention aims to provide a total remedy.
  • the invention is based on the technical problem of further developing such a process for the production of granules in such a way that granules which are harmless to health are made available which are stable to reaction and can be easily processed.
  • a generic method for the production of granules in the context of the invention is characterized in that the granules or the associated semi-finished product is heated to a temperature above the melting temperature of the binder formed as salt abruptly, so that consequently in the melt state located binder under gas release and volume increase at least partially decomposed.
  • the bulk density of the granule mixture and consequently of the finished product thus produced decreases compared to the non-heat treated semi-finished product.
  • the gas release of the binder leads to an increase in volume or expansion of the binder and consequently of the semi-finished product, which thereby becomes the finished product.
  • the powdery constituents of the solid are held together and form the desired granules.
  • the bulk density of the granule mixture and thus the bulk density of the finished product thus produced from the granules decreases compared to the semi-finished product.
  • the sudden heating of the semi-finished product or the mixture of the pulverulent solid and the binder and thus the granule mixture can generally with a temperature gradient of at least 20 ° C / sec. respectively.
  • the semi-finished product is heated in an oven in such a way that the above-indicated temperature increase or the associated temperature gradient in the individual granules is observed.
  • a suitable furnace can be used, for example, with a rotary kiln or rotary kiln, as it is known for lime burning and is described inter alia in DE 580 572.
  • the invention works with a temperature as quasi final temperature of the semi-finished product, which is located above the melting temperature and preferably even above the decomposition temperature of the salt-formed binder.
  • the salt used is particularly preferably calcium nitrate tetrahydrate or magnesium nitrate decahydrate, as will be described in more detail below.
  • the melting temperature of calcium nitrate tetrahydrate or the melting point is about 45 ° C, while anhydrous calcium nitrate has a melting point of about 560 ° C.
  • the thermal decomposition of calcium nitrate takes place in different stages. First, a crystallization of the tetrahydrate takes place at temperatures ⁇ 100 ° C. The elimination of oxygen begins above 130 ° C. From about 225 ° C, the calcium nitrate begins to decompose.
  • the semi-finished product in the example of calcium nitrate as a binder from room temperature (about 20 ° C) to a temperature above the melting temperature, d. H. above 45 ° C for the tetrahydrate (calcium nitrate tetrahydrate), heated abruptly.
  • the sudden heating can also be up to above the decomposition temperature as the final temperature, in the present case to a temperature of more than 225 ° C.
  • the temperature of the semi-finished product or the individual granules or the granules increases with at least 20 ° C / sec. to.
  • the actual heating process can be carried out in the already described rotary kiln or rotary kiln by heat transfer. In general, however, the sudden heating of the semi-finished product takes place contactlessly via radiant heat.
  • the granules of the semi-finished product typically pass through a heating section and are in this case subjected to a corresponding temperature, so that the temperature gradient mentioned in the transition from semi-finished product to finished product and also the final temperature of the finished product are observed.
  • the granules may be passed through a heated tube of, for example, ceramics to produce the said conditions.
  • oppositely directed air flow are at least partially decelerated to intensify the effect of heat.
  • the abrupt heating takes place in this case without contact, namely due to radiated heat radiation from the side of the tube.
  • the decrease in the bulk density can essentially be attributed to the fact that the binder or the auxiliary substance produces pores in the finished product as a result of the gas release in the mixture. Also, when heated primarily from the binder escaping water of crystallization promotes pore formation. That is, the expansion of the binder in conjunction with the water released results in the result that the transition of the semi-finished product or the corresponding granules to the finished product, the porosity and the volume of the granules increases significantly and the expansion of the binder in conjunction with the liberated water to a puffing of the granules comparable to the "popcorn effect" leads.
  • any decomposition residues of the binder or of the auxiliary agent ensure that the finished product is stabilized.
  • the binder is usually decomposed to at least 90% by weight. That is, in the finished product, the binder is found to be 10% by weight or less as compared with the semi-finished product.
  • the binder or the decomposed binder or its gaseous decomposition products can be recycled in total. That is, the volatile components of the binder can be reused at least for the most part.
  • the invention proposes to carry out an exhaust gas purification. In fact, most of the decomposition of the binder resulting and deposited nitrogen oxides can be in
  • the exhaust gas purification can be made so that the resulting nitrogen oxides or nitrogen dioxide or nitric acid is bound with calcium hydroxide powder to calcium nitrate.
  • the calcium nitrate from the exhaust gas can then be fed again to the process according to the invention as a binder. Consequently, the binder is at least partially recycled.
  • the gaseous components of the binder are deposited following the sudden heating of the semi-finished product in the context of exhaust gas purification and can be fed again as a binder.
  • granules are first of all used, that is to say grain mixtures whose grain size is advantageously located above 0.2 mm for the semi-finished products.
  • an average grain size for the semi-finished product or its granule mixture in the range of about 0.5 mm to 1, 8 mm has proved to be favorable.
  • an average grain size of the granules, which is at least 0.2 mm, is observed for the finished products.
  • the grain size of the granules of the finished product in the range of about 0.5 mm to 2 mm settled.
  • the bulk densities can also be specified in units of kg / dm 3 in the unit t / m 3 , as has already been done in the introduction. After the heating process and for the finished product bulk densities are observed, which are typically in the range of 0.8 kg / dm 3 and less. In fact, the bulk density of the finished product can also be adjusted to values of less than 0.5 kg / dm 3 and in particular to values of 0.3 kg / dm 3 and less. This succeeds essentially with the help of the abrupt heating process or, in the primary case, the actually set temperature gradient is responsible for this.
  • the granule mixture and consequently the semi-finished product with a temperature gradient of at least 50 ° C / sec., In particular 70 ° C / sec. and most preferably with a temperature gradient of at least 100 ° C / sec. applied.
  • the higher the temperature gradient is set the lower the bulk density or the bulk density of the finished product thus produced.
  • the apparent bulk density observed on the output side of the finished product produced thereby can be set and predetermined.
  • the larger the temperature gradient the greater the decrease of the bulk density of the finished product compared to the semi-finished product.
  • a decrease in the apparent density in the finished product compared to the semi-finished product of at least 20% is observed.
  • the mixed with the powdered mineral or solid binder is also usually before pulverulent and is dissolved in a solvent such as water. D. h., The powdery binder is in
  • the solvent in question such as, for example, water
  • mixing with the pulverulent mineral or solid and then granulating the mixture to produce the semi-finished product or the granulate mixture.
  • the process of granulation can be done, for example, by plate granulation.
  • An intermediate extrusion process is also possible as long as the desired agglomerates or grains of the semi-finished product in the specified average grain size in the range of 0.5 mm to 1, 8 mm are present on the output side.
  • a possible drying process can be incorporated into the production of the semi-finished product.
  • the semi-finished product or the respective agglomerates or grains have bound water.
  • Moisture contents in the range from 5% by weight to 30% by weight and usually from 10% by weight to 30% by weight, typically from 16% by weight to 22% by weight, are typically observed in the semi-finished product.
  • the finished product has moisture contents of mostly less than 4 wt .-%.
  • the set temperature or melting temperature in the subsequent abrupt heating of the semi-finished product for the production of the finished product is located in such a binder with moisture content at the same time above a temperature of separation of the solvent respectively of the water in the example of the granule mixture.
  • the temperature of the separation corresponds to the boiling point of the solvent, and therefore to water at approx. 100 ° C (at atmospheric pressure).
  • the (final) temperature set above the melting temperature of the salt-forming binder during the abrupt heating process is such that both the melting temperature of the binder and the temperature of separation or
  • Boiling temperature of the solvent from the granules are exceeded in each case.
  • the (final) temperature in the sudden heating process is not only above the melting temperature of the binder formed as a salt, but is preferably also above the decomposition temperature of the salt-forming binder.
  • the solid decomposition residues of the binder can develop a binding effect in the finished product.
  • the decomposition products thus act as scaffold structure in the finished product.
  • the water of crystallization bound in the binder and consequently also in the semi-finished product is split off at the same time when heated to the temperature in question (final) temperature far above the decomposition temperature of the salt. This releases water vapor.
  • the salted binder is typically an organic and / or inorganic (nitrogen-containing) salt.
  • binders or salts such as, for example, calcium nitrate tetrahydrate or magnesium nitrate decahydrate have proven to be particularly advantageous.
  • Calcium nitrate is known to be the calcium salt of nitric acid.
  • magnesium nitrate is also the magnesium salt of nitric acid.
  • salts and, preferably, nitrate salts are used as binders and, as it were, adjuvants, which are distinguished by a significant release of nitrogen oxides during their decomposition.
  • the abrupt heating process according to the invention with the specified temperature gradients of at least 20 ° C. per second, not only is the water of crystallization bound in the binder or solvent generally released by evaporation, but also nitrogen oxides are released in the example. Both gases ensure that the binder is decomposed with foaming, so that as a result thereof, the bulk density of the semi-finished product as described in the transition to the finished product drops significantly.
  • an oven for example a so-called perlite oven, is usually used.
  • the granulate mixture or the semi-finished product is subjected to a hot air flow or contactless.
  • the granule mixture or the semi-finished product passes through the hot air stream generated in the furnace in countercurrent, so that a particularly intense and uniform heating of the individual granules is observed.
  • a vertical ceramic tube furnace can also be used. In both cases, temperatures of the hot air flow inside can be observed and adjusted, which usually exceed 600 ° C and even more.
  • the decomposition temperature of, for example, magnesium nitrate is about 330 ° C.
  • the water of magnesium nitrate is released at temperatures above 90 ° C.
  • a decomposition beginning at 225 ° C. is observed.
  • the crystallization of the tetrahydrate takes place at temperatures of more than 100 ° C.
  • the pulverulent solid used in particular mineral or the pulverulent mineral raw material usually used for producing the granules according to the invention, is generally calcium oxide, magnesium oxide, calcium magnesium oxide (calcined dolomite), dolomitic lime, aluminum oxide, dunite, forsterite, olivine, carbon or the like substances. It is crucial that the melting point of the powdered mineral or the solid is settled well above the decomposition temperature of the binder and also above the temperature of the solvent for the binder.
  • the powdered mineral can not ensure the desired and required grain formation or grain stability in the finished product after the decomposition of the binder and the cleavage of the crystal Iwassers from the binder.
  • calcium oxide as a possible powdered mineral used, has a melting point approaching more than 2500 ° C.
  • the powdered mineral is still able to provide a stable backbone for the granules of the finished product available, even taking into account the significant decrease in bulk density, which as described by 1, 2 kg / dm 3 to 0.5 kg / dm 3 and less can sink.
  • the melting temperature or decomposition temperature of the binder formed as a salt is always located above the removal temperature of the solvent from the binder or from the granule mixture.
  • the design is regularly made so that the proportion of binder or excipient in the semi-finished product is less than 50 wt .-%. Consequently, the powdered mineral is present in the semi-finished product at 50% by weight or more. Particularly suitable are mixtures in the semi-finished product, in which 20 wt .-% to 40 wt .-% binder or excipient and the rest of the powdered mineral are used. As a lower limit for the binder or the auxiliary in semi-finished product, the invention recommends 5 wt .-% of binder. Otherwise, the required mechanical stability can not be ensured with the finished product produced from the semi-finished product.
  • the powdered solid is present in the semi-finished product to more than 60 wt .-%. The remainder is taken up by the binder (except for any soiling or any additives which are not more than 5% by weight).
  • alumina as a solid, a melting point of more than 2000 ° C is regularly observed, which is also located well above the decomposition temperatures of on the one hand magnesium nitrate and on the other hand calcium nitrate as conceivable binders.
  • dolomitic lime or, in general, dolomite which has a melting point well above 450 ° C. Also in this case, there is a distance of the melting temperature of the pulverulent mineral (> 450 ° C) compared to the binder (about 330 ° C), which is 100 ° C and more.
  • the preparation of the semi-finished product from the powdered mineral, the binder and optionally the solvent for the binder can be done in principle two different ways.
  • the pulverulent mineral and also the binder in the powdery state are each mixed dry and then subsequently solvent is added before a granulation process
  • the term "pulverulent" refers in each case to bulk materials having an average grain size which is significantly below 0.5 mm. Usually average particle sizes of 200 ⁇ and less are observed.
  • the powdered mineral on the one hand and the binder digested with the solvent on the other hand are mixed wet.
  • the moisture content of the subsequently granulated semi-finished product is between about 5 wt .-% and 30 wt .-%.
  • the invention recommends the use of about 60% by weight of powdery mineral and about 40% by weight of binder for producing the semi-finished product or the corresponding granules of the semi-finished product.
  • the semi-finished product contains more than 60% by weight of the powdered mineral and the remainder predominantly the binding agent, ie, except for any soiling, residues, etc.
  • the apparent density is in the range of 1.2 kg / dm 3 if, for example, 66% by weight of hydrated dolomitic lime and 33% by weight of calcium nitrate tetrahydrate are used to produce the semi-finished product as described. After heating, apparent densities of the finished product are observed to be typically 0.5 kg / dm 3 or even less.
  • the finished product is composed of 91 wt .-% of anhydrous dolomitic lime and 6% lime or calcium oxide from the decomposition of the calcium nitrate tetrahydrate together. In the example, the heating is carried out at about room temperature
  • Fig. 1 shows the manufacturing process of the invention schematically
  • Fig. 2 shows the use of the recovered granules as covering means for a molten metal.
  • Fig. 1 the manufacturing process according to the invention is shown schematically.
  • the left part shows the semi-finished product at 20 ° C, which is composed of calcium nitrate (Ca (NO3) 2 ⁇ 4H2O) and dolomite, each with bound water of crystallization. Due to the schematically indicated abrupt heating process from 20 ° C to temperatures of more than 1000 ° C on the one hand water vapor (n H2O) and on the other hand nitrogen oxides (NO x ) released. As a result, the dolomite remains in the finished product together with lime or CaO from the decomposition of the binder.
  • the use of the granules produced by the process according to the invention is now shown as covering means for general metal melts and in particular steel melts.
  • a pouring ladle 1 is detected there, from which the molten metal or molten steel passes into a tundish 2.
  • the molten steel in the tundish 2 is covered with the aid of the covering agent according to the invention on its surface, so that oxidation at this point can not or practically can not occur.
  • the molten metal or molten steel is then poured into a strand, on the output side of a forming tool 3, which in the example is cooled by supplied water 4.
  • the metal strand thus formed is carried on support rollers 5 on.
  • spray nozzles 6 can be placed between the support rollers 5 on both sides of the generated metal strand, with the aid of which, for example, water is sprayed onto the metal surface.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Manufacturing & Machinery (AREA)
  • Materials Engineering (AREA)
  • Structural Engineering (AREA)
  • Organic Chemistry (AREA)
  • Inorganic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Mechanical Engineering (AREA)
  • Compounds Of Alkaline-Earth Elements, Aluminum Or Rare-Earth Metals (AREA)

Abstract

La présente invention concerne un procédé de fabrication de granulés, en particulier destinés à être utilisés pour le calorifugeage de métal en fusion. Pour cela, on mélange un minéral en poudre avec un liant et on soumet le mélange à une granulation pour obtenir un produit semi-fini. Selon l'invention, on chauffe le mélange de granulation ou le produit semi-fini brusquement à une température supérieure à la température de fusion respectivement la température de décomposition du liant sous forme de sel de façon que le liant se décompose en dégageant du gaz et en augmentant de volume, afin d'abaisser ainsi la densité apparente du mélange de granulation et donc la densité apparente du produit fini par rapport à celle du produit semi-fini.
EP14724010.5A 2013-06-28 2014-04-25 Procédé de fabrication de granulés Withdrawn EP3013770A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102013106832.4A DE102013106832A1 (de) 2013-06-28 2013-06-28 Verfahren zur Herstellung von Granulaten
PCT/EP2014/058493 WO2014206598A1 (fr) 2013-06-28 2014-04-25 Procédé de fabrication de granulés

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EP3013770A1 true EP3013770A1 (fr) 2016-05-04

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EP14724010.5A Withdrawn EP3013770A1 (fr) 2013-06-28 2014-04-25 Procédé de fabrication de granulés

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US (1) US9914665B2 (fr)
EP (1) EP3013770A1 (fr)
DE (1) DE102013106832A1 (fr)
WO (1) WO2014206598A1 (fr)

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Publication number Priority date Publication date Assignee Title
DE102013106832A1 (de) 2013-06-28 2014-12-31 S & B Industrial Minerals Gmbh Verfahren zur Herstellung von Granulaten
DE102016112042B4 (de) * 2016-06-30 2019-10-02 Refratechnik Holding Gmbh Wärmedämmender, feuerfester Formkörper, insbesondere Platte, und Verfahren zu dessen Herstellung und dessen Verwendung
DE102016112039B4 (de) * 2016-06-30 2019-07-11 Refratechnik Holding Gmbh Wärmedämmende Platte, insbesondere Abdeckplatte für Metallschmelzen, sowie Verfahren zur Herstellung der Platte und deren Verwendung
US10874975B2 (en) * 2018-07-11 2020-12-29 S. A. Lhoist Recherche Et Developpement Sorbent composition for an electrostatic precipitator

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Also Published As

Publication number Publication date
DE102013106832A1 (de) 2014-12-31
US20160297712A1 (en) 2016-10-13
WO2014206598A1 (fr) 2014-12-31
US9914665B2 (en) 2018-03-13

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