Method of preparing raw mix for fabricating glass foam

FIELD: manufacture of building materials.

SUBSTANCE: invention relates to building materials with low values of heat conductivity and density. Preparation of raw mix 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 30 to 70% and silicate-reactive additive is fine powder of broken glass. Stirring is carried out at temperature not superior to 70°C and, after stirring, resulting mix is subjected to heat treatment at temperature between 450 and 550°C for a period of time long enough to completely remove of water, including chemically bound one, after which mix is cooled and powdered.

EFFECT: improved reproducibility of homogenous fine-porous structure of glass foam containing closed pores, improved heat-engineering characteristics, and reduced cost production cost.

2 cl

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

The area in which the glass is widely used, is the production of heat and sound insulation materials. It is known that among insulating materials currently used in construction and engineering, there is no equal glass for thermal conductivity at high mechanical strength. Foam glass insulation in comparison with other building materials, more efficient, does not require frequent repairs and its service life is longer.

The subject of most research in this field of technology is the production of a material with a stable performance, with a low density, which provides good heat and sound insulation properties, water resistance and resistance to acids. Found that bulk density, thermal insulation, mechanical properties and other properties have the best performance for foam glass, in which the structure is dominated by closed pores, i.e. closed, not interconnected cavities separated layers m is material. The presence in the structure of closed pore foam makes the product impervious to liquids, including water, water vapor and gases.

Practice shows that one of the determining factors influencing the process of obtaining high-quality foam, is a raw material mixture to obtain it, because of the composition of the mixture depends on its physico-chemical structure, which determines its thermal and mechanical properties. Have been made various attempts in this area to improve the properties of foam glass by choosing the composition of the raw mix for its manufacture. The foam glass can be obtained in many ways with the use of compositions based on various glass and foaming agents. As examples of the raw material mixtures can lead to two of the most effective: the first is a specially brewed glass of the desired composition and the second composition based on the different composition of the glass powder and a blowing agent, followed by foaming in the process of gradually heating the entire sintered mass of glass. Glass is usually used in powder form. 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 foam glass used is t granulate specially brewed glass, so you can get the foam glass of higher quality. The gas developing agents for foam glass production should decompose at a temperature of 50-70°above the softening temperature of the glass powder. The content of gas developing agents in the raw mix is usually 1-5%. For foaming glass in the composition of the glass batch is injected in the amount of 1-5% of the gas developing agents - carbon (carbon, coke, anthracite, black carbon, carbides of calcium and silicon), providing the material with a closed porosity or carbonate (limestone, chalk, marble chips).

The analysis of literature data shows that there is widespread production of foamed glass using a specially brewed and granulated glass, to improve properties which use scarce and expensive ingredients (WO 00/61512, CL 03 In 11/00, 03 At 19/08, 2000, DE 2010263, 03 AT 11/00, 1979).

Long time use of the raw mixture according to the US patent, 3151966, CL 65-22, 1996, a mixture of fine-grinded glass and blowing agent, which contains a reducing agent in the form of carbon ingredient and the oxidizer from sulfates, oxides, etc. Although the use of this well-known raw material mixture allows the glass sufficiently high quality with uniform structure, providing operational stability, od is ako the application of known raw materials are limited by its high cost due to the complexity of its receipt, associated with a number of additional operations, such as grinding, sintering, stabilization.

From patent US, 5516351, CL 03 In 19/06, 1996, well-known raw material mixture comprising powdered glass and foaming agent from among: calcium carbonate, caso₃or calcium sulphate CaS₄the specified particle size distribution. When cooking the mixture to obtain a foam using crushed glass in powdered form.

As examples can also lead raw material mixture comprising waste glass or foam glass, soda-lime glass, borosilicate or aluminosilicate glass and foaming agents. As the last raw materials may include carbonates and sulfates of various alkali and alkaline earth metals, for example calcium carbonate, sodium carbonate, barium carbonate, sodium sulfate, potassium sulfate, barium sulfate and carbon black, sulfur, dolomite.

In the patent RU, 2132307, CL 03 In 11/00, 1999 described the raw mix for the production of foam glass, including stekloobraznoi component and a foaming agent. As stekloobrazuyuschego component known mixture contains waste from the production of optical glasses, and as a foaming agent is manganese oxide MP₂About₃and additionally the waste of the production of phosphate fertilizers. To obtain raw CME and the above components are subjected to joint grinding, and then granularit and dried at a temperature of 100-150°C. Obtained from known raw material mixture, the glass has a low bulk density, which greatly improves the insulating properties of finished products. The use of waste reduces the cost of the foam glass. However, the known raw material mixture, the inherent drawback, as the heterogeneity of foam glass structure due to the presence of areas with high density and thermal conductivity.

In the patent RU, 2187473, CL 03 In 19/08, 2000, describes the raw mix for the production of foamed glass containing gidroksilirovanii fine-grinded powder of glass that is to be disposed, and foaming a mixture comprising the carbonaceous component is active carbon black, sodium sulfate, and optionally liquid sodium glass and boron oxide. The content of silicate in the composition of the foaming agent is 0.5-5.0 wt.%. For the preparation of the raw mixture shattered glass gidroksilnuyu in the process of grinding in the presence of 0.8 wt.% water additives or processing water vapor. Then gidroksilirovanii it is the glass powder is mixed with a foaming mixture, ensuring the greatest possible uniformity. The resulting mixture granularit in the presence of liquid glass to improve the gathering of the material into pellets. Then the granules are subjected JV is the caña.

To improve the granulation of the material mixture is moistened, if liquid glass is introduced dry powder. The use of known raw mix allows you to get the foam glass structure predominantly or completely closed pores with high thermal insulation properties, volumetric absorption of not more than 10%.

However, the known raw mixture is characterized by a high cost associated with the complexity of its receipt, the need for long and complicated mechanical mixing of the components of the raw mix to a very uniform distribution of the particles of the foaming agent in the powder. Special attention should be paid to the degree of dispersion of the grinding of glass, which may only be performed in the mill type, such as a ceramic or silicon liners and grinding bodies. Grinding in metal mills leads to contamination of the raw material metal balls and lining, which further violates the terms of steam formation in the sintered agglomerate. This in turn affects the stability, uniformity and reproducibility of the structure of closed pore foam.

The closest in technical essence and the achieved result to the invention is a raw mix for the production of foam glass, obtained from stekloobrazuyuschego component and d is babok, and how it is received, comprising mixing stekloobrazuyuschego component and powdered additives (US, 4198224, CL 03 In 19/08,1980) well-Known raw material mixture, manufactured by Pittsburgh Coming Corporation, contains a fine powder of glass and blowing agent. Raw mix for the production of foam glass is made from glass, to be disposed of (so-called cullet), and the gasifier. Glass and blowing agent, which is in a solid phase, carefully milled and mixed in a ball mill to an average grain size of 3-10 μm. While grinding components operate separately and megatape: first, carry out the grinding of glass for 4-6 hours, and then grinding the gasifier for 6-8 hours, and then conduct a joint grinding for 4-5 hours. Mixing finely dispersed components of the raw material mixture is carried out in solid phase. The obtained powdery mixture then is sintered in two stages at a temperature below the foaming, and then cooled. Using known mixtures allows to obtain a high-quality density foam glass 0,17-0, 25 g/cm³. Unfortunately, the known method is complicated by the fact that he is also connected with the problem of energy - and labour-consuming operations boiling glass of special composition and grinding, while mixing the starting components is carried out in the solid state f is PS, that does not provide them with a high level of uniformity of distribution in the volume of the mixture. In addition, the grinding in metal mills leads to contamination of the mixture of the metal balls and the lining, which, as mentioned above, in further violation of the conditions of steam formation in the stage production of foam glass. 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. In addition, the sharp rise in energy prices and the use of raw mix and how you can get leads to higher cellular glass. This requirement imposes constraints on the choice subjected to foaming of the composition.

In the framework of this proposal solves the problem of developing such a raw material mixture, and technology of its receipt, which would allow to produce foam glass with high thermal characteristics, but with low energy intensity of production. In addition, the task of improving 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 is then closed forms.

This object is achieved in that the raw cm is camping for the production of foam glass, obtained from stekloobrazuyuschego component and powdered additives, including the blowing agent is a dehydrated composition as a result of physico-chemical interaction at a temperature of 450-550°With an aqueous alkaline solution of sodium silicate and/or potassium and chemically active towards him additives.

The task is achieved by the fact that in the method of obtaining the raw mix for the production of foam glass, comprising mixing stekloobrazuyuschego components and additives, including gasifier, as stekloobrazuyuschego components using aqueous alkaline solution of sodium silicate and/or potassium, and as additives using substances chemically active with respect to the silicate content of an aqueous solution of sodium silicate and/or potassium when mixing is the magnitude of the range of 30-70 wt.%, after stirring at a temperature not exceeding 70°To carry out heat treatment at a temperature of 450-550°C and subsequent cooling to ambient temperature. Mixing an aqueous solution of silicate additives perform primarily at ambient temperature. In this way obtain a raw material mixture using aqueous alkaline solution of sodium silicate and/or potassium density of 1.3-1.5 g/cm³with the amount is Oh silicate module 2-3,5.

When this heat treatment is carried out in a period of time sufficient to remove water, including chemically bound.

The invention consists in establishing a causal link between such characteristics of the raw mix, as the presence in its synthesis of aqueous alkaline solution of sodium silicate and/or potassium and chemically active against him additives and physico-chemical condition of the raw material mixture at the time of completion of the process of its synthesis in the form of a dehydrated composition at a temperature of processing 450-550°and properties of the foam obtained with the use of this raw material mixture. To obtain efficient and cost-effective foam developed the method of its production, excluding many energy-intensive operation for obtaining the raw material mixture in the solid phase associated with obtaining glass of the desired chemical composition using expensive ingredients and grinding. This is achieved through the use of such inexpensive starting materials, synthetic silicates of sodium and/or potassium in the form of a so-called liquid or soluble glass and creating conditions for the subsequent foaming at high temperatures. Silicates of sodium (Na₂O·nSiO₂) and potassium (K₂O·nSiO₂), where n - silicate module glass, fusible, well dissolved in water. They are the main components of liquid glass in water undergo hydrolysis.

In this way obtain a raw material mixture, mixing original stekloobrazuyuschego component and additives is carried out not in solid state and in aqueous solution of alkali metal silicate, representing a plastic fluid that enables you to evenly distribute the components of the mixture in the volume. Mixing the source component of the raw mix in the state of liquid phase allows further in the stage production of foam glass is produced to obtain a homogeneous and uniform volume structure of closed gas-filled pores.

The selection of content of an aqueous solution of alkali metal silicate with stirring was carried out experimentally on the basis of the conditions for obtaining samples of the 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 1.3-1.5 g/cm³. Derived from this raw material, the foam glass has a resistance to weathering when used in a wet environment.

Example.

The invention is illustrated by way of getting the raw mix. As stekloobrazuyuschego component using aqueous alkaline solution of sodium silicate and potassium (optimalnoe ratio 1:1), custom Ryazan plant of Tripoli autoclave or bezavtoklavnym method hydrothermal leaching of oxide of silica in an alkaline medium at a temperature of 90-100°With the amount of 150 kg of an Aqueous solution of sodium silicate and potassium density of 2.0 g/cm³stirred at ambient temperature with additives in the form of fine-grinded powder of glass, taken in an amount of 65 kg for 10-15 minutes to form a viscous composition. After that, the process of mixing viscous composition is added to 30 kg of carbon gasifier. During mixing of the composition is the binding free water and alkali, are in liquid glass and adversely affect the solubility of the final product - foam glass. The increase in viscosity of the obtained composition indicates the reactions of physico-chemical interaction of its components. After stirring carry out the heat treatment of the mixture of gray at a temperature of 510°for 60-65 minutes. When the heat treatment be further physico-chemical processes, accompanied by the removal of free hydrated and chemically bound water and increase the viscosity of the mixture, after which it becomes dark grey. Weight cooled to the ambient temperature of the raw mix is about 60% of the t weight of the starting components. Then carry out the grinding of the mixture to the grain size of 15-20 microns. The crushed raw material mixture is poured into metal molds treated with a special compound, and thermoablative at a temperature in the range 790 - 800°With about 90 minutes. Heat treatment is accompanied by foaming milled raw material mixture.

The invention can be used to obtain the raw material mixture, which may find application as an inexpensive starting material for the production of foam glass having a reproducible and uniform size of closed pores. The invention provides for the use of an aqueous solution of sodium silicate and/or potassium and reactive to him additives, allowing you to get after mixing and subsequent heat treatment at a temperature of 450-550°From raw materials, suitable for the production of foam glass with closed pore structure, which can be obtained with arbitrary shapes and sizes. 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 by eliminating special cooking on the chemical composition of the glass at high temperatures.

1. The method of obtaining the raw mix for the production of foam glass, comprising mixing stekloobrazuyuschego components and poro is the crustacean leaves additives, including and carbon blowing agent, characterized in that as stekloobrazuyuschego component using aqueous alkaline solution of sodium silicate and/or potassium, taken in an amount of 30-70 wt.%, and as chemically active with respect to the silicate additives - it is the cullet powder, stirring is carried out at a temperature not exceeding 70°after mixing carry out the heat treatment of the mixture at a temperature of 450-550°With in a period of time sufficient for complete removal of water, including chemically bound, then cooled and pulverized into powder.

2. The method according to claim 2, characterized in that use an aqueous solution of sodium silicate and/or potassium density of 1.3-1.5 g/cm³with the amount of silicate module 2-3,5.