Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B28—WORKING CEMENT, CLAY, OR STONE
  • B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
  • B28B1/00—Producing shaped prefabricated articles from the material
  • B28B1/50—Producing shaped prefabricated articles from the material specially adapted for producing articles of expanded material, e.g. cellular concrete
• • 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
  • C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
  • C04B28/006—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing mineral polymers, e.g. geopolymers of the Davidovits type
• • 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
  • C04B2111/00612—Uses not provided for elsewhere in C04B2111/00 as one or more layers of a layered structure
• • 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
  • Y02P40/10—Production of cement, e.g. improving or optimising the production methods; Cement grinding
• • 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
  • Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
  • Y02W30/00—Technologies for solid waste management
  • Y02W30/50—Reuse, recycling or recovery technologies
  • Y02W30/91—Use of waste materials as fillers for mortars or concrete

Definitions

• the invention relates to a process for producing light, at least largely inorganic molded articles with a density ⁇ 400 kg / m 3 and a molded article made from at least largely inorganic constituents with a density ⁇ 400 kg / m 3 .
• I a finely divided oxide mixture with contents of amorphous silicon dioxide and aluminum oxide, obtained as filter dust from the production of corundum or mullite,
• lignite power plant filter ash in particular can be added.
• the stone-forming component reacts exothermically with an alkali silicate solution with 1.2 to 2.5 moles of SiO 2 per mole of K2O and / or Na2 O as hardener, a so-called geopolymer with a structure similar to zeolite or feldspar having a polycondensation or polyaddition reaction three-dimensional network structure.
• the foamed moldings produced by adding hydrogen peroxide as blowing agent in particular have sufficient strength and a relatively high temperature resistance for many purposes, the resistance to temperature changes is not sufficient for certain areas of application and the shrinkage is great when subjected to high temperatures.
• the relatively long curing time is also disadvantageous, since the foamed moldings can only be removed from the mold after about 10 to 60 minutes (green strength).
• EP-A2 0 071 897 discloses a lightweight building material and a process for its production in which perlite is bound as a light filler with a mixture of water glass, water and a water glass hardener.
• the binder is also foamed.
• K2SiFg or a CO2-releasing organic or inorganic agent is used as the hardener for the water glass.
• a drop in the silica and thus a solidification of the system is achieved by reducing the pH value of the water glass solution.
• These systems have the disadvantage of inadequate green strength and that they harden relatively slowly, so that short cycle times cannot be achieved when using expanded perlite as a light filler.
• these moldings have a relatively low resistance to temperature changes. The green strength is shortened by using expanded vermiculite instead of expanded pearlite, but the molded articles produced in this way have a significantly higher thermal conductivity.
• a preferred process product is a chimney or chimney element, produced in accordance with claim 15 or 16.
• the method according to the invention enables the production of particularly light inorganic insulating materials with relatively high strength, in particular high compressive strength and a favorable average pore size.
• the method above all produces an end product which is advantageously suitable for tape protection.
• the insulating material has practically no shrinkage and low thermal conductivity values. Even under extreme temperature changes, there are no cracks and no shrinkage. It is particularly important to emphasize that for the first time, such an insulating material can be used to produce moldings from light fillers which have a quality which has hitherto been unknown. These insulating materials can also advantageously be processed further.
• the method according to the invention differs in particular from the known method for producing lightweight moldings using lightweight fillers such as expanded pearlite or vermiculite in that a geopolymer known per se is used as the inorganic binder. It was not foreseeable that the use of this binding system would result in cycle times between the filling of the mixture into the mold or the pressing tool and demolding from a few minutes down to approximately 20 seconds and pure pressing times of a few seconds. the corresponding moldings have superior properties with regard to thermal conductivity, temperature resistance and resistance to temperature changes.
• the quick release from the mold is surprising even when using expanded perlite as the only light filler reached.
• the cycle times can in particular be achieved by heating the mold to 40 to 250 ° C., preferably 100 to 170 ° C., and by pressing with volume reduction of 20 to 80%, preferably 30 to 50% of the initial volume at a pressure of approx. 1 to 4 bar be shortened. Without such pressing the cycle times significantly extend what but for be ⁇ approved applications, in particular in the production of moldings with lost forms, can be put into "buying.
• the strength of the Formkör- inventively prepared by can substantially increased and the need to use the alkali silicate solution as a hardener can be reduced if the microporous fillers are treated with a water-containing wetting liquid before mixing, in particular warm water with additions of components which reduce the surface tension, such as a suspension made of aluminum phosphate or polysilicate or a surfactant
• a water-containing wetting liquid before mixing, in particular warm water with additions of components which reduce the surface tension, such as a suspension made of aluminum phosphate or polysilicate or a surfactant
• the wetting liquid is preferably injected into a stirred tank or the like, the light fillers being moved only carefully in order to damage the structure of the packing as little as possible If necessary, it can also be added after the light micro-porous components have been mixed with the stone-forming component, but before the alkali silicate solution is added as a hardener.
• An alkali silicate solution with 20 to 25% by weight of 2O, 23 to 28% by weight of SiO 2 and 50 to 60% by weight of water is preferably used as the hardener.
• the molar ratio of SiO 2 to K2O (or when using Na2 O to Na2 O or to the sum of Na2 O and K2O) is preferably 1.4 to 1.9.
• the thermal conductivity at high temperatures of around 400 to 1200 ° C can be reduced by adding opacifiers.
• Rutile, illmenite, carbon black or, preferably, vegetable ash with largely preserved flat silicate structure, such as, in particular, rice husk ash, are suitable for this.
• Rice husk ash also has the advantage of increasing the strength of the molded article produced. It is worth mentioning that the thermal conductivity of the finished molded articles does not decrease when using rice husk ash at temperatures up to approx. 200 ° C. is set, but that the effect of reducing the thermal conductivity occurs only at higher temperatures.
• the rice husk ash is preferably cautious and mixed in while maintaining the structure of the rice husk ash and without a grinding process.
• Expanded vermiculite and / or expanded pearlite is preferably used as the microporous filler with a bulk density of ⁇ 150 kg / m 3 , pure pearlite or mixtures with up to 50% by volume pearlite being preferred.
• Expanded vermiculite has a bulk density of approximately 75 to 200 kg / m 3 , while the bulk density of expanded perlite is approximately 30 to 100 kg / m 3 .
• the microporous fillers preferably have a grain size of 0 to 2 ⁇ m, in particular of 0 to 1 mm.
• the total mixture preferably contains approximately 25 to 35% by weight of microporous filler, in particular
• Perlite approx. 25 to 35% by weight alkali silicate solution as hardener, approx. 10 to 20% by weight reactive solid, approx. 10 to 20% by weight rice husk ash, approx. 5 to 10% by weight wetting liquid.
• customary fillers such as rock powder, basalt, clays, feldspar, mica powder, glass powder, quartz sand or quartz powder, bauxite powder, alumina hydrate and waste from the alumina, bauxite or corundum industry, ashes, slags and mineral fiber materials can be used.
• the total mixture preferably contains less than 20% by weight of these additional fillers, in particular less than a total of 10% by weight.
• a system which has a first mixer in which the solids, ie. H. the reactive solid, the microporous fillers and possibly other additives are mixed, with this mixer being followed by a counterflow mixer with injection nozzles for the wetting liquid.
• This makes it possible with such a system to separate the individual components, ie. H. above all, mix the light filler with the wetting liquid carefully and evenly, in order to then mix the correspondingly pre-mixed solid with the hardener so that the even and easy-to-use "earth-moist" molding compound results.
• a further post-mixer is connected downstream of the countercurrent mixer, or that both mixers form a unit having several mixing sections.
• a press is arranged downstream of the counterflow mixer. This press is used to form plates and moldings which are ideally suited to a wide variety of operating conditions and have high insulating properties.
• the mixture containing the microporous fillers, the reactive solid and the hardener is filled into a mold or a pressing tool and reduced in volume to 20 to 80%, preferably 30 to 50% of the Initial volume pressed at a pressure of about 1 to 4 bar.
• This pressing in the mold or between two pressing plates ensures that the molded bodies are solidified after a very short time to such an extent that they can be removed from the mold and then hardened further.
• the reduction in volume is associated with a certain destruction of the structure of the light fillers, but the moldings obtained are nevertheless extremely light and have outstanding thermal insulation properties.
• chimneys or chimney elements can be produced by filling the molding compound into an annular gap between two walls and then curing it.
• the walls preferably consist of two stainless steel tubes arranged concentrically to one another.
• the molding compound adheres to the walls despite its low specific weight due to its low shrinkage and its high resistance to temperature changes, without later showing any unacceptable cracking or shrinkage.
• the moldings are constructed in multiple layers with a light core with a density below 400 kg / m 3 and at least one outer layer or coating of a geopolymer with a density between 400 kg / m 3 and 1200 kg / m 3 , the outer coating having a much higher strength and temperature resistance than the core.
• the lightweight molded articles as previously prepared may be ⁇ written to after the escape and possibly with a hardening molding composition, comprising a stone-forming component ⁇ an alkali silicate solution as a curing agent and optionally smaller amounts of perlite and / or be coated Vermicu- lit.
• the coating is preferably achieved by prior to pressing the mixture for the core, this mixture in the mold with a thin layer of a molding compound containing a stone-forming component, an alkali silicate solution as hardener and, if appropriate, smaller proportions of pearlite and / or vermiculite, and the two layers are pressed together.
• the denser film mass can also be filled into the mold in a thin layer first, whereupon the light layer is then filled with the higher proportion of light fillers.
• Fig. 1 is a schematic sketch of the system provided for the production of plates.
• the production plant 1 initially has a plurality of storage containers 2, 3, 4.
• the individual components for the solid are stored in these storage containers 2, 3, 4. namely a reactive solid, a temperature change-resistant aluminum silicate or aluminum titanate or aluminum oxide as filler, and rice husk ash to reduce the thermal conductivity at elevated temperatures.
• the solid components removed from these storage containers 2, 3, 4 are mixed together in the mixer 5 to form a solid mixture which is then further processed with the light fillers and the hardener to give a molding composition.
• the mixing can be carried out, for example, discontinuously in what are known as Eirichmisers or in suitable continuous mixers.
• the wetting liquid which consists of a suspension of aluminum phosphate or polysilicate in water, is fed from the tank 10 in countercurrent via the injection nozzle 9.
• the individual constituents separately and then to add them mixed or uniformly via the injection nozzle 9.
• a post-mixer 11 is provided which is constructed like the counterflow mixer 6 and to which both the mixture of light fillers and wetting liquid and the solid are fed.
• the hardener is then injected into the post-mixer 11 via the nozzle 12 from the tank 13 and is mixed in during the stirring in the post-mixer 11.
• the uniform molding compound thus obtained then reaches the press 14, where appropriate shaping takes place, whereupon, for example, insulating plates 15 are then stacked up and then sent for sale.
• the light fillers are placed in a countercurrent mixer, the wetting liquid (aluminum phosphates in water) is sprayed in while stirring, the solid mixture is added and finally the hardener (alkali silicate solution) is metered in with stirring.
• Sheets with a density between 280 and 400 kg / m 3 were produced by pressing from the earth-moist molding compound.
• the compressive strengths were between 0.9 to 1.2 N / mm 2 , the shrinkage (linear) at 800 ° C to approx. 1%.
• the thermal conductivity at 400 C was 0.07 to 0.10 W / mK.

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• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Ceramic Engineering (AREA)
• Geochemistry & Mineralogy (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Life Sciences & Earth Sciences (AREA)
• Environmental & Geological Engineering (AREA)
• General Life Sciences & Earth Sciences (AREA)
• Manufacturing & Machinery (AREA)
• Geology (AREA)
• Mechanical Engineering (AREA)
• Inorganic Chemistry (AREA)
• Materials Engineering (AREA)
• Structural Engineering (AREA)
• Organic Chemistry (AREA)
• Curing Cements, Concrete, And Artificial Stone (AREA)
• Press-Shaping Or Shaping Using Conveyers (AREA)
• Fireproofing Substances (AREA)
• Porous Artificial Stone Or Porous Ceramic Products (AREA)

Priority Applications (2)

Applications Claiming Priority (4)

Publications (1)

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Family Applications (1)

Country Status (4)

Cited By (20)

Families Citing this family (2)

Citations (4)

• 1993
  • 1993-04-13 WO PCT/EP1993/000900 patent/WO1993021126A1/de active Application Filing
  • 1993-04-13 DE DE4391555T patent/DE4391555D2/de not_active Expired - Fee Related
  • 1993-04-13 AU AU40398/93A patent/AU4039893A/en not_active Abandoned
  • 1993-04-13 JP JP51797993A patent/JP3563071B2/ja not_active Expired - Fee Related

Patent Citations (4)

Non-Patent Citations (1)

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