RU2459769C2 - Method of producing foamed glass - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of foamed glass. Powdered mixture based on crushed glass and mineral substance - talc, is prepared, with the following ratio of components in wt %: talc 2-8, glass - the balance. The mixture is heated in a metal mould at foaming temperature of 720-780°C, followed by annealing.

EFFECT: simple method of producing foamed glass, low cost thereof, high strength, water absorption and frost resistance of the obtained material.

2 cl, 1 tbl

Description

The invention relates to the production of foam glass. Technical characteristics of foam glass meet the highest requirements for thermal insulation and structural materials and allow it to be used for all types of building envelopes of buildings and structures for various purposes in any climatic zone.

Foam glass has significant positive qualities that make it useful. A unique combination of foam glass properties allows the use of this material quite widely. It can be used as a heat-insulating and structural material in construction and housing and communal complexes, as well as in agriculture, energy, engineering, chemical and petrochemical industries, food, paper, pharmaceutical and other industries.

The quality and properties of foam glass depend on its strength characteristics, heat conductivity, volumetric water absorption, frost resistance, etc. The disadvantages of foam glass include the high cost of equipment and technological energy.

In industry, for the manufacture of foam-glass plates and blocks, the “powder” method is mainly used, which consists in sintering a mixture of finely ground glass powder with a blowing agent.

A known method (US patent No. 2775524), in which the dispersion of cullet is carried out with a specially prepared material from the group of diatomite, silica with a specific surface area of more than 10 m ² / g, containing carbon in the amount of 5-50 mass parts per 100 parts, based on 0.08 -0.15 wt.% Carbon by weight of cullet, heating to a temperature sufficient to soften and foaming the glass, cooling and annealing.

A known method of producing foam glass (US patent No. 5516351, C03B 19/06), which includes the use of ground glass and a foaming agent from the number of CaCO ₃ or CaSO _{4 of a} given particle size distribution, mixing them in a mill, filling out a mold, displacing air from the mixture by blowing it with SO gases _x and / or CO _x and heating to a foaming temperature, cooling and annealing, allowing the use of mixed glass. It is well known that the use of ingredients whose chemical reactions with glass are accompanied by foaming does not provide fine-porous foam glass with mostly and / or completely closed pores from the external environment. The apparent density, thermal insulation, mechanical and other properties of such materials quickly and severely degrade in a humid atmosphere. The use of SO _x and CO _x gases leads to a higher cost of production, has adverse environmental consequences and requires high costs for the capture and processing of gaseous emissions hazardous to operating personnel and the environment.

It is known to produce heat-insulating foam glass using carbon-containing foaming agents (coke, soot, anthracite), as well as using carbonate foaming agents (chalk, marble, dolomite).

A known method of producing foam glass (patent for invention RU No. 2187473, C03B 19/08, dated July 12, 2000), which relates to methods for producing foam glass from recyclable waste glass, consisting in the fact that the cullet is dispersed to a specific surface of 6000-20000 cm ² / g, then hydroxylated to a moisture content of 0.4-1.6 wt.% and to 75-98 wt.% hydroxylated cullet add 2-25 wt.% a foaming mixture comprising active carbon black with a specific surface area of 75-150 as a carbon-containing component m ² / g, as metal sulfate - sodium sulfate and additional relatively liquid sodium glass and boron oxide in the following ratio of ingredients, wt.%: liquid sodium glass 0.5-5.0, active carbon black with a specific surface area of 75-150 m ² / g 0.2-1.5, sodium sulfate 0.5-1.5, active silica 0.6-12.0 boron oxide 0.2-5.0, mixed, granulated into particles with a diameter of 30-2000 microns, filled into a mold and compacted to an apparent density of 0.96-1.35 g / cm ³ , sintered at a temperature of 450-700 ° C, foamed, subjected to hardening at a temperature of 540 -620 ° C at a rate of 80-300 ° C / min and annealed at a temperature of 420-520 ° C. Using this method solves the problem of utilizing alkaline aluminosilicate glasses that have accumulated in a large volume of domestic and industrial technical waste. But the output properties of the final product in the known method are far from always at the proper level. In addition, in the manufacture of foam glass by this method, a large number of components are used in the composition of the material necessary to produce foam glass. In addition to the components of the foaming mixture itself (oxidizing agent - sodium sulfate, reducing agent - active soot), the additive also includes components that directly affect the melt properties and the output properties of foam glass (active silica, boron oxide, water glass). The additives used in the known method are necessary to achieve the required output properties of the foam glass, but, as you know, a large number of components always complicates the technological process of producing a material with stable properties. This is primarily due to the problems of uniform distribution of ingredients in the mixture and directly in the foamed glass. This is especially important in the production of foam glass, where the distribution of the components of the additive in the mass of the charge and recyclable cullet should be uniform, otherwise foaming in the glass volume will go uneven, which will lead to heterogeneity of the structure due to the formation of caverns, uneven volume distribution of pores. This will lead to defectiveness, heterogeneity of the properties of the foam material.

According to this method, a mixture containing carefully mixed finely ground powders of glass and a carbon-containing blowing agent is metered into metal forms and sent to a foaming furnace (1 stage). In a foaming furnace, heating to foaming temperatures is carried out for 1-3 hours. The mixture undergoes a series of transformations when heated: at T> 600 ° С, the glass powder softens and sinter, turning into a viscous glass mass; at temperatures above 750 ° C, the carbon gas blower begins to decompose at a noticeable rate with the formation of gaseous products. At T> 800 ° С, the pressure of the evolved gases and the viscosity of the glass melt become sufficient for foaming the glass with the formation of closed gas cells. Foaming glass using carbon blowing agents is usually carried out at temperatures of 830-890 ° C. After the foaming furnace, the mold with the foam glass block is sharply cooled to temperatures of 500-600 ° C, freezing the resulting cellular structure. At these temperatures, the foam glass blocks are removed from the molds to prevent them from being crushed by the metal during cooling in the annealing furnace. This is followed by annealing in a tunnel furnace (stage 2), the head of which is heated. Then the foam glass is machined with saws to give the block a rectangular shape. This operation is accompanied by the release of a large amount of glass dust and the appearance of scraps of foam glass. Foam glass obtained by carbon technology in a 2-stage method has closed pores and low thermal conductivity.

The disadvantages of the methods in which carbon blowing agents are used are:

- high foaming temperatures (> 800 ° C) require increased energy consumption, the use of expensive heat-resistant steels, reduce the service life of equipment and tools, and also contribute to crystallization of glass, which reduces the strength of foam glass and increases the proportion of perforated pores;

- between the foaming and annealing furnaces at temperatures of 500-600 ° C, a dangerous operation is carried out to remove the foam glass blocks from the molds and transfer them to the annealing furnace;

- foam glass pores contain toxic hydrogen sulfide.

There is also a solution in accordance with RF patent No. 2167112 "Method for producing foam glass" IPC 7 C03C 11/00, C03B 19/08, where cullet is also used as raw material, foaming temperatures are lower by 10-40 ° C than in the above, and the number of charge components is reduced to four. In this method, a composition is prepared consisting of powders obtained by grinding in a ball mill of bottle glass, sand, sodium silicate, carbon blowing agent (coke, charcoal, soot), which is shut with water, the resulting paste is heated at a rate of 5-10 ° C / min to temperatures of 750-850 ° C and maintained at this temperature for 4-5 hours, then the blocks are cooled in the same furnace.

This method also has the following disadvantages:

- use of a 4-component mixture;

- introduction of additional operations - receiving paste and forming a block;

- a carbon blowing agent fills the gas pores with toxic hydrogen sulfide.

Carbonate blowing agents, unlike carbon, are not surface-active substances, are characterized by a significant affinity for molten glass and cannot exert a stabilizing effect on glass foam (Schill F. Penosteklo, Publishing House of Construction Literature, M., 1965, 307 pp. .; Demidovich BK Production and application of foam glass, Minsk: Science and technology, 1972, 304 p.). These blowing agents reduce the foaming temperature by 70-100 ° C, but the foam glass is spongy, with perforated walls of the gas cells. It is believed that it is impossible to obtain foam glass characterized by low water absorption (less than 10%) and a density of <200 kg / m ³ using carbonates, which was the reason for the rejection of this technology in world practice. By this technology only acoustic and granular foam glass is produced.

Closest to the claimed method, which is devoid of some of the disadvantages of the above methods, is a method for the production of heat-insulating block foam glass (patent RU No. 2237031 "Method for the production of heat-insulating block foam glass" IPC ⁸ C03C 11/00, C03B 19/08), including the preparation of a powdery mixture of glass and gas formation, heating the mixture in metal form in a foaming furnace, annealing the products, an additional mineral surfactant is added to the mixture in an amount of 3-5 wt.% of the mixture, carbonate gases are used browser, as well as metal molds in which the cover and one of the walls are released in front of the annealing furnace, making them movable, preventing crushing of the foam glass block in the annealing furnace, which is carried out using the heat of the blocks and forms, and directly foaming at a temperature of 750 ± 10 ° С lead for 20-30 minutes, and the rate of temperature decrease in the annealing furnace from 550 to 50 ° C is 0.7-0.8 ° C / min. This method is more technological and environmentally friendly, carried out at lower temperatures. However, for the production of foam glass, three components are used, including carbonate blowing agents, therefore, the method remains quite complex, and the foam glass obtained by this method is expensive.

In addition, some of the above methods do not allow to obtain colored foam glass, since the glass, as a rule, is already painted black or gray.

The claimed invention solves the problem of creating a simpler and cheaper method for producing foam glass, and the technical result is, accordingly, the simplification and cheapening of the method.

This technical result is achieved in that in the production of foam glass, including the preparation of a powder mixture, including ground glass and mineral matter, heating the mixture in metal form in an oven at a foaming temperature, annealing the product, the foaming temperature is selected in the range 720-780 ° C, and talc in the amount of 2-8 wt.% the mixture is used as a mineral substance. To add color to the charge, mineral dyes can be added, which are used as metal oxides and sulfides in an amount of 0.1-5%.

The inventive method is as follows. A fine-ground mixture with a specific surface> 400 m ² / kg containing glass (92-98%) of the total mass and layered talc silicate (GOST 21234-75) in an amount of 2-8% of the total mass is prepared from a container or window fight of glass. . An increase in the amount of talc in the charge of more than 8% leads to an unjustified consumption of talc, as the necessary properties do not improve, and increases the cost of foam glass, and a decrease in its amount of less than 2% reduces the formation of pore. A mixture containing carefully mixed powders of glass and talc is metered into a closed metal alloy steel alloy, which is fed into a furnace, for example, of a tunnel type. Within 1-1.5 hours, heating is carried out from room temperature to (720-780 ° C) and foaming (aging) at this temperature for (10-30 minutes). After foaming, the foam glass is rapidly cooled to temperatures of 500-600 ° C for 3-10 minutes, freezing the resulting cellular structure. At these temperatures, the foam glass products are removed from the mold and sent to annealing in a tunnel type furnace. To facilitate the extraction of foam glass products, molds with collapsible walls are used.

The use of molds for the production of foam glass products, which are made with (collapsible) walls, allows to obtain various construction products, including blocks, bricks, lintels, slabs, paving slabs, tiles, etc., with specified geometric dimensions and excluded from the technological process harmful operation of machining blocks. The surface of the product in this case has a vitrified surface that increases the strength of the foam glass.

The annealing furnace for the device is similar to a foaming furnace. After the annealing furnace, the foamglass blocks are removed from the molds and packaged and sent to the warehouse. The molds are brushed with a metal brush and an inorganic protective coating is applied to the inner surface to prevent the adhesion of molten glass. After coating, the molds are dried, filled with a charge and the foaming cycle - annealing is repeated again. It is possible to obtain colored products. To this end, powders with a specific surface area of at least 400 m ² / kg of metal compounds as a mineral dye in an amount of 0.1-5 wt.% Of the mixture are added to the glass and talc mixture with their mixing. This can be cobalt oxide GOST 18671-73, copper oxide TU 6-09-02-381-85, titanium dioxide GOST 9808-84, manganese dioxide GOST 25823-83, manganese oxide GOST 4470-79, chromium oxide TU 6-09 -4272-84, iron oxide TU 6-09-5346-87, iron oxide GOST 2912-79.

Talc has a finer dispersed structure than ground glass. When mixing, particles of a larger fraction (glass) seem to form a skeleton, the voids of which are filled with particles of a small fraction (talc). Upon heating and reaching a temperature of 600 ° C, the particles of glass begin to stick together with each other, forming pores filled with talc and air. It is known that talc belongs to the group of montmorillonite, as a result of which it has a sheet crystal lattice (W. Warrell “Clays and Ceramic Raw Materials” translated from English. Edited by Dr. Geol.-Min. Science V.P. Petrova, Publishing House “Mir” ", M, 1978, p. 42-44). In the minerals of this group, individual crystals consist of many single complex layers (packets). These complex packets are adjacent to each other by siliceous sheets, there are no hydroxyl bonds between them and they are held together only by the van der Waals forces, which are easily broken. Water located in the interlayer positions evaporates already at a temperature of 150-300 ° C, however, water inside the crystal lattice can begin to evaporate only with a further increase in temperature even after the formation of pores by the adhesion of glass particles. It is known that, with closed porosity, water evaporates in the pores, forming high pressure microzones (V.I. Nazarov, R.G. Melkonyan, V.G. Kalygin, “Technique of compaction of glass blends”, M., Legprombytizdat, 1985). Pores under the influence of such pressure expand, as a result of which the glass swells. During cooling (freezing) of the expanded glass, the pores remain of the same expanded size. Oxides contained in talc are distributed over the surface of the pores, strengthening them.

Examples of the method.

Example 1. 950 g (92 wt.%) Of window or bottle glass battle powder or a mixture thereof was mixed with 82.6 g (8 wt.%) Of talcum powder (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ) for the ceramic industry ( GOST 21234-75), ground to a specific glass surface of 600 m ² / kg. The mixture was poured into a metal mold with dimensions of 250 × 125 × 60 mm and sent to a batch foaming oven. The heating time of the furnace to a temperature of 720 ° C 1 hour 10 minutes In the interval between the foaming and annealing furnaces, the foam block was cooled to 600 ° C for 5 min, after which the mold locks were opened for 10-30 s, and the mold itself was sent to the annealing furnace. Annealing in the temperature range 600–50 ° С was carried out at a rate of 1.2 ° С / min. The technological parameters of the resulting foam glass are shown in the table.

Example 2. 950 g (98 wt.%) Of window or bottle glass breakdown powder or a mixture thereof was mixed with 19.5 g (2 wt.%) Ground talc (Mg ₃ Si ₄ O ₁₀ (OH) ₂ ) for the ceramic industry ( GOST 21234-75), ground to a specific glass surface of 600 m ² / kg. The mixture was poured into a metal mold with dimensions of 250 × 125 × 60 mm and sent to a batch foaming oven. The heating time of the furnace to a temperature of 780 ° C 1 hour 10 minutes In the interval between the foaming and annealing furnaces, the foam block was cooled to 600 ° C for 5 min, after which the mold locks were opened for 10-30 s, and the mold itself was sent to the annealing furnace. Annealing in the temperature range 600–50 ° С was carried out at a rate of 1.2 ° С / min. The technological parameters of the resulting foam glass are shown in the table.

Example 3. 1000 g (99.9 wt.%) Of glass and talc breakdown were mixed and 1 g of mineral dye (chromium oxide - GOST 2912-79) (0.5 wt.%), Ground to a specific surface of 600 m ² / kg . The mixture was poured into a metal mold with dimensions of 250 × 125 × 60 mm and sent to a foaming oven. The heating time of the furnace to a foaming temperature of 1 hour 10 minutes The foaming time at 720 ° C. corresponded to 25 minutes. In the interval between the foaming and annealing furnaces, the foam block was cooled to 620 ° C for 5 min, after which the mold locks were opened for 10-30 s, and the mold itself was sent to the annealing furnace. Annealing in the temperature range 600–50 ° С was carried out at a rate of 1.2 ° С / min. As a result, foam glass was obtained in a light green color.

Example 4. Mixed, as in example 3, 1000 g (95 wt.%) Glass and talc breakdown and 52.6 g of mineral dye (iron oxide - TU 6-09-02-5346-87) (5 wt.%). The mixture was poured into a metal mold with dimensions of 250 × 125 × 60 mm and sent to a foaming oven. The heating time of the furnace to a foaming temperature of 1 hour 10 minutes The foaming time at 780 ° C. corresponded to 25 minutes. In the interval between the foaming and annealing furnaces, the foam block was cooled to 620 ° C for 5 min, after which the mold locks were opened for 10-30 s, and the mold itself was sent to the annealing furnace. Annealing in the temperature range 550–50 ° С was carried out at a rate of 1.2 ° С / min. The result was foam glass in a dark lilac color. Due to the somewhat increased density, the resulting foam glass can be used as a structural element in construction, for example, for masonry walls.

The inventive method of obtaining a heat-insulating structural foam glass is simple, technologically advanced and allows the disposal of household and industrial waste glass.

Table No. p / p The name of indicators Test results for a series of samples: Technical requirements for TU 21002-2009 for grades: D300 D400 D500 The results of the testing of samples of the prototype Example 1 Example 2 Note 3 Note four one Tensile strength under compression, GOST 10180-90, MPa 7.91 7.52 7.46 7.56 2.5-4.5 1.4-2.2 6.0 2 Bending Strength, MPa 4.70 4,51 4,5 4,53 0.7 - 3 Water absorption by volume,%, no more 0.8 0.9 0.85 0.95 No more than 5 four four The average density of 12730.1-78, kg / m ³ 550 517 535 562 301-401 190-210 501-350 500-600 5 Frost resistance, GOST 25485-89 (tests are ongoing) F50 F50 F50 F50 F50 F40- 6 Thermal conductivity in the dry state, W / mK, GOST 7076-99 0.11 0.11 0.10 0.10 0.083 0.10
0.11 0,076-0,085 0.042-0.050

The table shows that the material obtained by the claimed method exceeds the material obtained by the method of the prototype in such indicators as tensile strength, water absorption, frost resistance, but inferior in thermal conductivity.

The technical characteristics of the foam glass obtained by the claimed method correspond to the highest requirements for heat-insulating and structural materials and allow it to be used for all types of enclosing structures of buildings and structures for various purposes in any climatic zones.

Such foam glass has significant positive qualities that make it useful, namely: durability; high strength due to increased density, dimensional stability, does not burn, does not emit toxic gases, low water absorption, high frost resistance

Claims (2)

1. A method for the production of foam glass, comprising preparing a powder mixture containing ground glass and a mineral substance, heating the mixture in metal form in an oven at a foaming temperature, annealing the product, characterized in that the foaming temperature is selected in the range 720-780 ° C, and as mineral matter use talc in the following ratio of components, wt.%:
Talc 2-8 Glass Rest 2. The method according to claim 1, characterized in that when preparing the powder mixture, metal compounds are additionally added to it as a mineral dye in an amount of 0.1-5 wt.% Of the mixture.