Method of preparing blend for fabricating glass foam

FIELD: manufacture of building materials.

SUBSTANCE: invention relates to building materials with low heat conductivity and density values. Preparation of blend comprises stirring glass-forming components and powderlike additives containing gasifier among other components. Glass-forming component utilized is sodium and/or potassium silicate aqueous solution taken in amounts 50 to 70% and silicate-reactive additive is fine powder of broken glass. Stirring is carried out at temperature not superior to 70°C and viscous-flow mix is thermally treated at 450-550°C to completely remove of water, including chemically bound one, after which mix is cooled and ground into power with particle size at most 60-70 μm.

EFFECT: improved heat-engineering characteristics at low power consumption.

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The invention relates to the production of building materials with low values of thermal conductivity and density, in particular to a method for producing a mixture for the production of foam glass having a homogeneous porous structure of the pores.

The subject of most research in this field of technology in the context of a sharp rise in energy prices is the development of materials with high thermal characteristics, but with low energy intensity of production. Among building materials with good heat and sound insulating characteristics of the foam glass attracts attention due to the complex thermal and sound insulation properties and high strength and low density.

It is known that bulk density, thermal and mechanical properties have the best performance for foam glass, in which the structure is dominated by closed pores, i.e. closed, not interconnected cavities, separated by layers of material. The presence in the structure of closed pore foam makes the product impervious to liquids, including water, water vapor and gases. Solid foam, a typical representative of which is a foam glass, are formed in the dispersion of a gaseous phase in a viscous liquid (dispersion medium) in the process of cooling the dispersion system. At lower t is mperature viscous liquid is solidified and formed in this way, the foam is stabilized.

Get the glass, as a rule, by powder, by sintering a mixture of a glass powder with a gas-forming additives. The powder produced either from specially welded glass melting, or from the breakage, tare and other glasses. For foaming glass in the composition of the glass batch is injected in the amount of 1-5% of the gas developing agents - carbon (coke, anthracite, black carbon, carbides of calcium and silicon), providing the material with a closed porosity or carbonate (limestone, chalk, marble chips).

As examples of the most effective ways to get the charge can result in two: the first is a special melting glass of the desired chemical composition and the second composition-based glass powder of cullet (glass waste) homogeneous chemical composition and the blowing agent with the subsequent foaming in the process of heating the entire sintered mass of glass. The powder produced either from specially welded glass melting (US, 4192664, CL 03 In 19/08, 1980, US, 3403990, CL 65-22, 1968), or from the breakage, tare and other glass (US, 4198224, CL 03 In 19/08, 1980). In some cases, to obtain a foamed glass is used granulate specially brewed glass (DE, 2010263, CL 03 With 11/00, 1979).

Technology for the production of foam glass includes the step of preparing the mixture by melting glass special is imicheskogo composition and granulation (or training cullet), grinding and mixing powders of glass and the gasifier and the subsequent stage of the foaming mixture during the heat treatment and annealing of foam glass. The foaming process is carried out at a temperature between 800 and 950°C for 20-30 minutes, after which the glass cooled rapidly to stabilize the structure (US, 4192664, CL 65-22, 1980, US, 3951632, CL 65-22, 1976). The mixture for the manufacture of foam glass can be obtained in many ways with the use of compositions based on various glass and gas developing agents. Thus, the known composition of the glass, including waste glass, soda-lime glass, borosilicate or aluminosilicate glass (e.g., US, 4119422, CL 65-22, 1978, and US, 4075025, CL 501-66, 1978) and the gas developing agents, such as carbonates and sulfates of various alkali and alkaline earth metals (for example, US, 5516351, CL 65-17 .4, 1996).

The analysis of literature data shows that the known technology of preparation of the mixture for the manufacture of foam glass granulate comprising grinding and drying of glass, batching and joint grinding glass and carbonate blowing agent in a ball mill, feeding ground of the charge in the hopper, granulating the mixture on a plate granulator, where as a binder for the pellets submit a solution of liquid glass. To obtain a foam obtained mixture is dried and foamed with mol is th quartz as a separating medium at a temperature of 780-820° C.

A known method of obtaining a mixture for the production of granulated foam glass having a homogeneous structure of closed pores (WO 00/61512 A₁, CL 03 With 11/00, 03 At 19/08, 2001). The method includes preparation of glass powder, which is used as cullet, synthesized glass natural glass or their mixture. The glass powder is mixed with a liquid glass at a temperature of 60-120°at normal pressure or in an autoclave. The resulting product is cooled to obtain pellets. Granulated mixture is subjected to two-stage heat treatment: first at a temperature of 200 to 300°With no more than 15 minutes, and then at a temperature of 400-800°With no more than 15 minutes.

From the patent RU, 2087432, CL 03 In 19/08, 1997, a method of obtaining the mixture for the production of foam glass, in which glass powder and foaming agent are mixed, then the mixture is heated to a temperature of the foaming 765-960°and cool. Glass is usually chosen from a group including waste glass, sodium silicate glass, borosilicate glass, aluminosilicate glass, and mixtures thereof, and a blowing agent selected from the group including carbonates of alkali and alkaline earth metals, carbon, sulfur, dolomite and mixtures thereof. In the resulting powdery mixture is injected binder and water. Additionally, the composition of the charge, you can enter the Lam pumice in the amount of 25 wt.% by weight of the mixture.

From patent US, 5516351, CL 03 In 19/06, 1996, a method of obtaining charge for foam glass production, comprising mixing powdered glass and foaming agent specified particle size distribution, which is used as calcium carbonate or calcium sulfate.

The closest in technical essence and the achieved result to the claimed method is a method of obtaining a mixture for the production of foam glass, comprising mixing stekloobrazuyuschego component and powdered supplements containing including gasifier (US, 4198224, CL 03 In 19/08, 1980). The mixture is made from glass that is to be disposed, and the gasifier. Glass and blowing agent, which is in solid condition, carefully milled and mixed in a ball mill to an average grain size of 3-10 μm. In the known method grinding components operate separately and in several stages to achieve the required degree of dispersion. The obtained powdery mixture then is sintered at a temperature below the foaming, then subjected to heat treatment at a foaming temperature to complete the process of foaming, and then cooled. Using the known charge allows to obtain a high-quality glass, but the method of obtaining a charge related to the problem of energy and trademco and operation of cooking glass of special composition and grinding. While mixing the starting components is carried out in the state of the solid phase, which does not allow to achieve high uniformity of the distribution by volume of the charge additives, including the gasifier. Since mixing of the components occurs in the condition of the solid phase, even a high degree of dispersion of the powder and the duration of mixing may not provide the desired degree of level of homogeneity that at the stage of heat treatment of the mixture at a temperature of foaming does not give the desired degree of homogeneity and uniformity of the physico-chemical structure of the resulting foam. In addition, prolonged grinding and mixing, requiring much labor and energy costs, affects the cost of the foam glass. It should also be noted that the grinding in metal mills leads to contamination of the charge of the metal balls and the lining that further in the stage production of foam glass violates the terms of steam formation. The production of quality foam requires that in addition to specifically enter the gasifier powdered raw mixture did not contain any of the substances, when heated, which could be allocated gases. This requirement imposes constraints on the choice subjected to foaming of the mixture.

In the framework of this proposal solves the problem of the development of such a method of obtaining a mixture, of which the first would produce foam glass with high thermal characteristics, but with a low intensity of production. In addition, there is a need to improve the reproducibility of foam glass structure with a homogeneous porous structure containing pores of a closed form. There is also a need to achieve a uniform distribution of the volume of foam glass fine pores are closed character.

This object is achieved in that in the method of obtaining a mixture for the production of foam glass, comprising mixing stekloobrazuyuschego component and additives, including carbon-containing blowing agent, as stekloobrazuyuschego component using aqueous alkaline solution of sodium silicate and/or potassium, and as additives for use chemically active with respect to it substance, stirring is carried out at a temperature not exceeding 70°received a plastic mixture thermoablative at a temperature of 450-550°to obtain a dehydrated composition, and then cooled to ambient temperature and grind into powder.

In addition, the content of the aqueous solution of alkali metal silicate with stirring is 30-70 wt.%, and mixing an aqueous solution of silicate with additives is carried out at a temperature not exceeding 70°mainly when the ambient temperature. Dehydrated composition grind into powder with size is ω grain not more than 60-70 microns, mostly 4-5 microns.

In the way that predominantly use an aqueous solution of alkali metal silicate density of 1.3-1.5 g/cm³with the amount of silicate module 2-3,5.

The invention consists in establishing a causal link between such characteristics of the charge, as the use in its synthesis of aqueous alkaline solution of sodium silicate and/or potassium, which represents the viscous flow of the liquid, mixed with additives, grinding dehydrated after heat treatment of the mixture to fine condition and properties of foam glass. The weight of the resulting charge mass after heat treatment is about 62-63% by weight of the starting components.

In this method of obtaining a mixture, the mixing of the starting components is carried out not in the solid state and in aqueous solution of alkali metal silicate, which represents the viscous flow of the liquid component, while allowing for a uniform distribution of the powdered additives by volume of the charge and the flow of certain physico-chemical processes at temperatures of 450-550°With, including those associated with dehydration of the mixture, and the creation of preconditions for the subsequent foaming of the mixture in powdered form. Mixing the starting components of the mixture in the state of liquid phase allows further policetraining volume of foam glass structure closed gas-filled pores.

The authors experimentally determined the content of the aqueous solution of the alkali metal with stirring, the temperature at the stage of mixing the starting components at the stage of processing of the mixture prior to foaming operation based on the conditions for obtaining a foam of the desired density, homogeneity, maximum strength, heat and moisture resistance. The most acceptable silicate module liquid glass is 2.0 to 3.5 at a density of a solution of 1.3-1.5 g/cm³. Obtained from this mixture the glass has a resistance to weathering when used in a wet environment.

Example.

The invention is illustrated by way of receiving the charge. As a main component is used 120 kg BW of an aqueous alkaline solution of sodium silicate, manufactured at the Ryazan plant of Tripoli autoclave or bezavtoklavnym method hydrothermal leaching of oxide of silica in an alkaline medium at a temperature of 90°C. an Aqueous solution of sodium silicate density of 1.9 g/cm³first stirred at ambient temperature with additives in the form of fine-grinded powder of glass, taken in an amount of 60 kg over 10-15 minutes. Then when mixing a plastic composition, it is added to 30 kg of carbon gasifier. In the process of peremeshivanija is the binding free water and alkali, in liquid glass and adversely affect the solubility of the final product - foam glass. The reduced viscosity of the obtained composition in the mixing process and the subsequent heat treatment shows the reactions of physico-chemical interaction of its components. After stirring carry out the heat treatment of the mixture of gray at a temperature 480°for 70-85 minutes. When the heat treatment there are physical and chemical processes, accompanied by the removal of free water of hydration, after which the mixture becomes dark gray. Weight cooled to the ambient temperature of the raw mix is about 60% by weight of the starting components. Then carry out grinding the cooled mixture to the grain size of 15-20 microns. The charge representing cooled after the heat treatment at a temperature below the foaming to ambient temperature and powdered raw mixture is poured into metal molds treated with a special compound, and thermoablative at a temperature range of 770-830°C. the Heat treatment is accompanied by foaming powdered mixture with the formation of foam.

The table shows the results of chemical analysis in comparison with cellular glass "FOAMGLAS"", manufactured by Pittsburg Coming Europe(Belgium).

The invention can be used to obtain the charge, which may find application as an inexpensive starting material for the production of foam glass with reproducible homogeneous porous structure. This leads to a number of commercial advantages, including the ability to obtain a foam with high thermal characteristics, but with low energy intensity of production.

A method of obtaining a mixture for the production of protecl is, comprising mixing stekloobrazuyuschego component and powdered additives, including carbon-containing blowing agent, characterized in that as stekloobrazuyuschego component using aqueous alkaline solution of sodium silicate and/or potassium content of which is 50-70 wt.%, as the powdery additives are finely ground glass, stirring is carried out at a temperature not exceeding 70°received a plastic mixture thermoablative at a temperature of 450-550°C to remove water, including chemically bound, then cooled and pulverized into a powder with a grain size not more than 60-70 microns.