Glass foam fabrication method

FIELD: manufacture of building materials.

SUBSTANCE: invention relates to building materials with low heat conductivity and density values. Fabrication of glass foam comprises preliminary heat treatment at temperature below foaming temperature of starting mixture prepared from broken glass powder, carbon-containing gasifier, and sodium and/or potassium silicate aqueous solution, pausing at this temperature to complete foaming process, and subsequent cooling. Starting mixture is prepared at temperature not superior to 70°C by consecutively mixing sodium and/or potassium silicate aqueous solution (30-70%), not sorted broken glass powder (25-65%), and carbon-containing gasifier (4-9%), after which mixture is treated at 450-550°C until removal of water, including chemically bound one, is completed. Resulting product is cooled and then heated to foaming temperature (750-830°C).

EFFECT: improved quality of glass foam at low labor and powder consumption.

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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, and can be applied upon receipt of foam glass from recycled glass breakage regardless of its chemical composition.

Among building materials with good heat and sound insulating characteristics of the foam glass is light bulk density, low heat conductivity and high absorption; it is non-flammable, heat-resistant and chemically resistant material. Foam glass is a lightweight porous material obtained by sintering and foaming at high temperatures a mixture of powdered source of glass or other vitreous materials with gas developing agents (finely ground limestone, chalk, soot, coke).

The foam glass can be obtained in many ways with the use of compositions based on various glass and foaming agents. The powder produced either from specially welded glass melting, or from the breakage, tare, optical and other glasses. Traditional technology of production of foam glass includes a glass of special composition,milling with a blowing agent to obtain a finely dispersed mixture, foaming molded mixture in the annealing process at a temperature not less than 700°With (US, 4192664, CL 03 In 19/00, 1980, US, 3403990, CL 65-22, 1968). Glass is usually used in powder form. 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 high intensity operations produce glass of the desired composition.

It is known that to obtain a foam with constant physical properties (bulk density less than 280 kg/m³, a water absorption of less than 5% and a relatively ordered structure) technology developed in relation to the original glass of a specific composition. That is why the selection of the raw materials is of great importance. Raw material for production of foam glass must be suitable taking into account the cost of its production, which pays attention to time and temperature foaming.

In the patent US, 4198224, CL 03 In 19/08, 1980, disclosed a method of producing foamed glass from cullet comprising heating the powder mixture to a temperature of foaming, holding at that temperature to complete the process of foaming and subsequent cooling. Foam glass is manufactured by Pittsburgh Corning Corporation, produced from fine n the Rosca glass and the gasifier. The charge for the production of foam glass is made from glass, to be disposed of (so-called cullet), and the gasifier. Glass of a specific composition and a 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: the first consists of separate grinding of glass and blowing agent, and then spend their joint grinding. 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. Unfortunately, the known method is complicated by the fact that he is also connected with the problem of mixing the starting components in the solid state 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. Unfortunately, in the context of a sharp rise in energy prices using known powder charge and how you can get leads to higher cellular glass. This requirement is algae constraints on the choice subjected to foaming of the composition.

From the patent RU, 2109700, CL 03 With 11/00, 1998-known technology of manufacturing granulated foam glass-based glass waste by preparing a powder mixture of glass of the battle and of the gasifier. In document WO 00/61512, 03 11/00, 2000 disclosed a method of obtaining a granulated foam glass using waste glass with one - or two-stage processing of the granulate at a temperature of 200 to 300°or 400-800°With in a period of time not more than 15 minutes.

Liquid glass is widely known as an additive in the production of foam glass granulate required as a binder for the pellets (e.g., DE, 2010263, 03 11/00, 1979). In the patent RU, 2162825, CL 03 With 11/00, 2001, disclosed a method of making foam glass from disassembled the broken glass of a specific composition, comprising preparing a mixture by joint grinding of broken glass and carbonate blowing agent, granulating the mixture with irrigation water solution of soluble glass, drying the granules and heat treatment at a temperature of foaming 780-820°C, followed by annealing.

The closest in technical essence and the achieved result to this method is a method of producing foamed glass, including a preliminary heat treatment at a temperature below the foaming of the mixture obtained from the fine powder is ka cullet, carbon-containing component and sodium silicate, heating the mixture to a temperature of foaming, holding at that temperature to complete the process of foaming and subsequent cooling (EN, 2187473, CL 03 In 19/08, 2000). There is a method allows to obtain high-quality foam glass block on the basis of alkaline aluminosilicate glassy waste. In the known method mix dispersible broken glass and foaming the mixture containing silica, carbon-containing component, a metal sulfate and a liquid sodium glass in the amount of 0.5-5.0 wt.%. Then, the first mixture is sintered, and then foamed at a temperature 790-860°and conduct quenching and annealing. Foaming additive is prepared by mixing silica, water glass in a dry or moistened with water, soot, sulfate and boric acid. The resulting mixture is subjected to granulation in the presence of liquid glass to improve the gathering of the material into pellets. To improve the granulation of the material mixture is moistened, if liquid glass is introduced dry powder. Fill the metal forms a granular material and sent to the sintering furnace, expansion and annealing. Obtained by known techniques the glass is characterized by high cost associated with the need for long and complicated mechanical mixing to the components to a very uniform distribution of the particles of the foaming agent in the powder. In addition, the 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 coefficient of uniformity of such foam is not high enough. Technological regimes known method worked out in relation to the specific composition of the glass, which makes them unacceptable when using cullet arbitrary composition. The instability and complexity of the composition of the cullet, due to the dependence on functional assignments made technical glass, the composition of the starting ingredients, as well as its modes of cooking, lead to instability of the qualities produced from foamed glass.

In the framework of this proposal solves the problem of expanding the resource base and development of such technology, which would make the glass without regard to the chemical composition of the glass, i.e. from unsorted cullet, and with low energy intensity of production. There is a need to develop a method of producing foamed glass with different chemical composition, types of technical glass - breakage, container, chemical glassware and mixtures thereof in various proportions with respect to the tion to each other. In addition, the task of improving the reproducibility of foam glass structure with a homogeneous porous structure containing pores of a closed form.

This object is achieved in that in the method of producing foamed glass, including a preliminary heat treatment at a temperature below the foaming of the mixture obtained from cullet powder, carbon component and sodium silicate, heating to a temperature of foaming, holding at that temperature to complete the process of foaming and subsequent cooling, the initial mixture is produced at a temperature not exceeding 70°by successive mixing aqueous alkaline solution of sodium silicate and/or potassium, powder of glass and carbon-containing component, the mixture is then treated at a temperature of 450-550°With up to a dehydrated state, the resulting product heat treatment after cooling, crushed, and then heated to a temperature expansion of the range 750-830°With ingredients upon receipt of the original mixture are chosen ratio, wt.%:

an aqueous solution of sodium silicate and/or potassium 30-70

powder unsorted cullet 25-65

carbon-containing blowing agent 4-9.

Since unsorted cullet, i.e. artificial technical glass, represent system containing their different oxides, the process of interaction in aqueous solution of an alkali metal and unsorted cullet demanded study its thermodynamic regimes. The data of the optimum ratio of ingredients and temperature regimes were established by the authors experimentally based on the study of thermodynamics of the process of synthesis of the source mixture based on an aqueous solution of an alkali metal and unsorted cullet, i.e. cullet arbitrary chemical composition. Dissolved in water to a concentration of sodium silicate and/or potassium is an alkaline solution, which is necessary for the occurrence of physical and chemical processes accompanying the interaction with oxides of cullet, regardless of their composition, including the content in the glass of alkaline oxides.

The invention consists in establishing a causal relationship between physico-chemical properties of foam glass, thermodynamic conditions obtaining raw mix, including raw ingredients and the temperature of its receipt, the sequence of mixing the ingredients and modes of its heat treatment. In the absence of well-known patterns of physico-chemical state of matter after its processing when the foaming temperature and initial composition upon receipt of the raw material mixture by the authors experimentally would and found the optimal value content of an aqueous solution of alkali metal silicate, powder of broken glass and carbon-containing the blowing agent, after which allow sequential mixing and subsequent processing at a temperature in the range 450-550°to obtain the required parameters of the foam glass. 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 of silicate of alkali metal, powder technical glass arbitrary chemical composition and carbon-containing the blowing agent is carried out not in the solid state and in aqueous solution of alkali metal silicate, which represents the viscous flow of the liquid from the hydrogen index of the medium pH>7 and which is such a component that provides a uniform distribution of the powdered additives by volume of the mixture, and passing the required physical and chemical processes under stirring, and then heated to a temperature of 450-550°With associated, including, with 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 at a temperature not exceeding 70°allows to obtain a uniform volume of foam glass structure closed gas-filled pores at low energy is Giamatti production without regard to the chemical composition of technical glass.

Example

The invention is illustrated by way of receipt of the foam glass. The initial mixture is prepared from the following components. As stekloobrazuyuschego component using 150 kg of commercially available, i.e. a commercially available 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 (pH>7) at a temperature of 90-100°C. an Aqueous solution of sodium silicate and potassium (optimal 1:1 ratio) when the ambient temperature is first stirred for 10-15 minutes with a fine-grinded powder unsorted, unsorted cullet different grades and chemical composition, taken in an amount 65 kg. This cullet is prepared from the battle window, container of any color and chemical ware in any proportions relative to each other. Then, in the mixing process received a plastic composition in it add 20 kg of carbon gasifier. During mixing of the composition is the binding free water and alkali, adversely affecting the solubility of the final product - foam glass. The resulting mixture has a gray color. After mixing all components of the raw mix hold it ther is a processing at a temperature of 530° With over 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 results of comparative tests of the foam produced by this technology, in comparison with cellular glass "FOAMGLAS"^Rproduction company Pittsburgh Corning Europe (Belgium).

Comparative analysis of the test results of this foam and foam FOAMGLAS^Rshows considerable overlap in the properties between them.

The invention can be used to obtain foam reproducible porous structure of cullet arbitrary chemical composition. The invention involves the use of aqueous alkaline solution of sodium silicate and/or potassium and reactive to him additives, one of which is powder cullet arbitrary chemical composition, allowing to obtain after mixing with carbon-containing blowing agent and heat treatment at a temperature of 450-550°dehydrated composition suitable for the production of foam glass with high thermal characteristics, but with low energy intensity of production by eliminating special cooking what about the chemical composition of the glass at high temperatures.

A method of producing foamed glass, including a preliminary heat treatment at a temperature below the foaming of the mixture obtained from a powder of glass, carbon-containing the blowing agent and an aqueous solution of sodium silicate and/or potassium, heating to a temperature of foaming, holding at that temperature to complete the process of foaming and subsequent cooling, wherein the initial mixture is produced at a temperature not exceeding 70°by successive mixing aqueous alkaline solution of sodium silicate and/or potassium, powder of glass and carbon-containing the blowing agent, the mixture is then treated at a temperature of 450-550°C to remove water, including chemically bound, the resulting product, after cooling, crushed, and then heated to a temperature expansion of the range 750-830°With ingredients upon receipt of the original mixture are chosen ratio, wt.%:

Aqueous alkaline solution of sodium silicate and/or potassium 30-70

Powder unsorted cullet 25-65

Carbon-containing blowing agent 4-9.