Glass foam fabrication method

FIELD: manufacture of building materials.

SUBSTANCE: invention relates to building materials with low values of heat conductivity and density. Fabrication of glass foam comprises heating powderlike blend with carbon-containing gasifier to foaming temperature, pausing at this temperature to complete foaming process, and subsequent cooling. Blend utilized is a cooled raw mix ground to powdered state, which is prepared via heat treatment of mixture of sodium and/or potassium silicate alkali aqueous solution and silicate-reactive additive, in particular fine broken glass powder and carbon-containing gasifier, at 450-550°C until removal of water, including chemically bound one, is completed. According to invention, content of sodium and/or potassium silicate alkali aqueous solution amounts to 30-70%, mixing is carried out at temperature not superior to 70°C, and foaming temperature of blend lies within a range of 750 to 830°C.

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

2 cl, 1 tbl

The invention relates to the production of building materials with low values of thermal conductivity and density, in particular for the production of block foam glass used as an effective heat insulating material in various building structures.

The area in which the glass is widely used, is the production of heat and sound insulation materials. Foam glass insulation in comparison with other building materials, more efficient, has a longer service life.

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.

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. When the temperature of the viscous fluid is solidified and formed in this way, the foam is stabilized. The foaming process is determined primarily by the temperature and nature of the ingredients included in the composition of the raw mix to obtain pinost the Klah.

The foam glass can be obtained in many ways with the use of compositions based on different glass. As examples two of the most effective ways: first, obtaining the foamed glass of 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. 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, optical and other glass (US 4198224, CL 03 In 19/08, 1980, EN 2132307, CL 03 With 11/00, 1999). Glass is usually used in powder form. For foaming glass in the composition of the glass batch type gas developing agents in the amount of 1-5 wt.%. For carrying out the foaming powder mixture of glass and blowing agent is poured into forms, which are then placed in a furnace, where the temperature of the foaming mixture is heated and foams. Then form cellular glass is cooled and stabilized at a temperature below the foaming. After completion of the heat treatment of the obtained blocks of foam glass is removed. The disadvantages of the known technology are its high energy consumption associated with high temperature heat treatment, the duration of the operations produce glass of the desired composition, and a great time of foaming.

Thus, the known method of producing foamed glass by melting glass in a controlled atmosphere at a temperature of 1350-1510°With his preliminary heat treatment in the temperature range softening 700-800°and further heat treatment at a temperature of foaming. There are also known methods for producing foamed glass, based on the use of another technology operations - graining of the finished glass and its subsequent grinding together with the blowing agent before the second heat treatment (US 4192664, CL 65-22, 1980). Known methods require significant energy costs for batch preparation in the form of fine powders of glass and blowing agent, and their subsequent joint grinding and mixing for a long time to achieve the required uniformity of the distribution component in the amount of the charge, and manufacturing operations produce glass of the desired composition.

Have been made various attempts in the field to produce high-quality foam with high thermal performance and low energy intensity of production.

Thus, patent RU 1719333, CL 03 With 11/00, 1992, a method of obtaining foam, comprising preparing a powder mixture of glass and the gasifier, which use isout silicon carbide, before the mixing process with a saturated aqueous solution of alkali metal sulfate. The foaming mixture is happening when it is heat-treated at a temperature of 850°C.

The analysis of literature data shows that there is widespread production of foamed glass using a specially brewed and granulated foam glass, to improve properties which use scarce and expensive ingredients (WO 00/61512, CL 03 With 11/00, 03 At 19/08, 2000). Long time use technology to produce foam glass from a powder mixture of fine-grinded glass and blowing agent (US 3151966, CL 65-22, US 3403990, CL 65-22, 1968), which contains the reducing agent in the form of carbon ingredient and the oxidizer from sulphates, oxides and other Application of known technology allows to receive the glass sufficiently high quality with uniform structure, providing operational stability, however, the glass has a high cost due to the complexity of the operations produce glass of the desired composition.

From the patent RU 2187473, CL 03 In 19/08, 2000, a method of obtaining a block of foamed glass, comprising dispersing recycling of cullet and additives foaming mixtures containing silica, carbon-containing component, a metal sulfate and a liquid sodium glass in the amount of 0.5-5.0 m is from.%, sintering, foaming at a temperature 790-860°With, quenching and annealing. The glass is subject to disposal, is subjected to dispersion in a mill in the presence of water additives, resulting in hydroxylation of glass. Prepare foaming additive by mixing silica, water glass, soot, sulfate and boric acid. Then gidroksilirovanii it is the glass powder is mixed with a foaming mixture in compliance with the required concentrations, achieving the greatest possible uniformity. The resulting mixture is subjected to granulation in the presence of liquid glass to improve the gathering of the material into pellets. Fill the metal forms a granular material and sent to the sintering furnace, foaming, annealing. To improve the granulation of the material mixture is moistened, if liquid glass is introduced dry powder. There is a method allows to obtain the glass structure is predominantly or completely closed pores with high thermal insulation properties, with the bulk absorption of not more than 10%. Obtained by known techniques the glass is characterized by high cost associated with the complexity of receipt of the charge, the need for long and complicated mechanical mixing of the components to a very uniform distribution of particles of penoobrazovatel is 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 charge of the metal balls and the 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 this method is a method of producing foamed glass comprising heating the powder mixture to a temperature of foaming, holding at that temperature to complete the process of foaming and subsequent cooling (US 4198224, CL 03 In 19/08, 1980). Foam glass is manufactured by the Pittsburgh Coming Corporation, get out of the fine glass powder and a 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 in several stages: first, implementing tlaut grinding glass for 4-6 hours, then the grinding of the gasifier for 6-8 hours, then spend the 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. There is a method allows to obtain the glass density of 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 state of a solid phase 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. In addition, the sharp rise in energy prices using known powder charge 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 technologies for foam glass, which would make protecl the high technological characteristics, but with a low 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 fine pores are closed character.

This object is achieved in that in the method of producing foamed glass comprising heating a powder mixture with a carbon-containing blowing agent to a temperature of foaming, holding at that temperature to complete the process of foaming and subsequent cooling, as charge use crushed to a powder chilled raw mixture obtained by heat treatment to a dehydrated state at a temperature of 450-550°With a mixture of aqueous alkaline solution of sodium silicate and/or potassium and powdered chemically active against silicate additives, the content of the aqueous solution of alkali metal silicate in obtaining the raw mix is 30-70 wt.%, and heating of the mixture is conducted to the temperature expansion of the range of 770-830°C. in Addition, the aqueous alkaline solution of sodium silicate and/or potassium is mixed with additives at a temperature not exceeding 70°C.

It is advisable to use an aqueous solution of sodium silicate and/or potassium PLO is of 1.3 to 1.5 g/cm ³with the amount of silicate module 2-3,5.

The invention consists in establishing a causal relationship between physico-chemical properties of foam glass and the original composition of the raw mix, its successive heat treatment with the initial stage of mixing the ingredients at a temperature not exceeding 70°C, cooling and grinding to obtain a powdery mixture and the temperature of the foaming mixture. In the absence of a well-known laws of the state of matter after its processing when the foaming temperature and initial composition of the charge authors were experimentally found the optimal values of the contents of an aqueous solution of alkali metal silicate at a temperature of processing 450-550°in which are provided the required parameters foamed glass, which has a low cost of its production. The most acceptable silicate module of an aqueous solution of alkali metal silicate is 2-3,5 when the density of a solution of 1.3-1.5 g/cm³.

In this method of producing foamed glass mixing the source component is not carried in the solid state and in aqueous solution of alkali metal silicate at a temperature not exceeding 70°representing the viscous flow of the liquid and which is such a component that provides both the homogeneity of the distribution of Poroskov the different additives by volume of the charge, and the course of physico-chemical processes at temperatures of 450-550°related, including dehydration of the mixture and removal of chemically bound water. Mixing the source component of the mixture in the state of liquid phase without pre-heating the main component and additives allows to obtain a uniform volume of foam glass structure closed gas-filled pores at low intensity of production.

Example.

The invention is illustrated by way of receipt of the foam glass. As stekloobrazuyuschego use component 120 kg BW of an aqueous alkaline solution of sodium silicate and potassium (the optimal ratio of 1:1), made at the Ryazan plant of Tripoli autoclave or bezavtoklavnym method hydrothermal leaching of oxide of silica in an alkaline medium at a temperature of 90-100°C. an Aqueous solution of alkali metal silicate 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. When mixing a plastic 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 water-solubility of the final product is the foam glass. The increase in viscosity of the obtained composition indicates the flow of physico-chemical interaction of its components already at ambient temperature. The resulting mixture has a gray color. After mixing all components of the raw material mixture carried out the heat treatment at a temperature 480°C for 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 weight of the original component. 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 when the foaming temperature of 780°With at least 90 minutes.

Table 1 shows the properties of foam glass produced using this technology, while table 2 shows the results in comparison with cellular glass "FOAMGLASS" production company "Pittsburgh Coming Europe(Belgium).

Table. 1

The invention can be used to obtain foams of the glass with reproducible porous structure. 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 heat treatment at a temperature of 450-550°dehydrated composition suitable after grinding to obtain a foam with high thermal insulation characteristics, but with low energy intensity of production by eliminating special cooking on the chemical composition of the glass at high temperatures.

1. A method of producing foamed glass comprising heating a powder mixture with a carbon-containing blowing agent to a temperature of foaming, holding at that temperature to complete the process of foaming and subsequent cooling, characterized in that as the charge used crushed to a powder chilled raw mixture obtained by heat treatment at a temperature of 450-550°C to remove water, including chemically bound water mixture alkaline solution of sodium silicate and/or potassium and chemically active against specified silicate additives - fine-grinded powder of broken glass and carbon-containing the blowing agent, the concentration of the aqueous alkaline solution of sodium silicate and/or potassium when the mixture is 30-70 wt.%, mixing is carried out at which the temperature is not above 70° C and heating of the mixture is conducted to the temperature expansion of the range 750-830°C.

2. The method according to claim 1, 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.