RU2290372C1 - Block heat-insulation foamed glass manufacture process - Google Patents

Abstract

FIELD: manufacture of building materials.

SUBSTANCE: powdered mixture of glass, carbonate gasifier, and chemically active substance (0.8-5%) is heated in metal mold with adjustable walls and removable liner placed in oven. Heating is carried out until foaming temperature (680-740°C) for 0.8-1.5 h. resulting foamed glass blocks are then placed in annealing chamber, wherein cooling from 600°C to 50°C is accomplished at cooling velocity 1.2-1.6°C/min.

EFFECT: reduced foaming temperature.

1 tbl

Description

The invention relates to the production of foam glass, a highly effective thermal insulation material widely used in construction.

For thermal insulation, foam glass is used with closed ones, and for sound insulation - with interconnected pores.

It is known that the quality of heat-insulating foam glass when using carbon-containing foaming agents (coke, soot, anthracite) is significantly higher than when using carbonate foaming agents (chalk, marble, dolomite), therefore, in world practice, heat-insulating foam glass in blocks is obtained exclusively using carbon gas blowing agents [1] .

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 upon heating: at T> 600 ° C, 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 ° C, 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. The foaming process at these temperatures, depending on the composition of the glass, the heating method and the design of the furnaces, lasts from 30 minutes to 1.5 hours. 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. Two side walls of the molds are made inclined, which facilitates the release of the block. This is followed by annealing in a tunnel furnace (stage 2), the head of which is heated. Annealing is necessary to relieve mechanical stresses in the volume of foam glass. This is the slowest production process, the duration of which ranges from 8 to 16 hours. At shorter times, cracks appear in the volume and on the surface of the foam glass, which reduces strength and increases water absorption. 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 two-stage method has closed pores and low thermal conductivity.

The disadvantages of the known carbon method:

- high foaming temperatures (> 800 ° C), require a large consumption of energy and expensive heat-resistant steels, reduce the life of equipment and accessories, 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, most often manually the dangerous operation of removing the foam glass blocks from the molds and loading them into the annealing furnace is carried out;

- the presence of harmful and laborious mechanical filing of all 6 faces of the foam glass block;

- foam glass pores contain toxic hydrogen sulfide.

As a prototype adopted the method of production of heat-insulating block foam glass [2].

The method includes preparing a powdery mixture of glass and a blowing agent, heating the mixture in metal form in a foaming furnace, annealing the products, while a mineral surfactant is additionally introduced into the mixture in an amount of 3-5% by weight. mixtures, carbonate blowing agents are used, as well as metal molds in which the cover and one of the walls are released before the annealing furnace, making them movable, preventing the foam glass block from being crushed in the annealing furnace, which is carried out using the heat of the blocks and molds, and heating to a foaming temperature of 750 ± 10 ° C is carried out for 1-2 hours, foaming directly - 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.

The disadvantages of the method:

- A large number of expensive metal molds are required;

- significant heat costs spent on heating thick-walled forms from room temperatures to foaming temperatures;

- the transport system of the annealing furnace cannot use simpler and cheaper metal nets or ribbons and requires a large number of metal live rolls of large diameter and chain transmissions;

- large length of the annealing furnace (≥45 m);

- long production cycle (≥14 hours).

These disadvantages of the prototype are eliminated by the proposed solution.

The problem to be solved is the reduction of energy consumption, material consumption and the duration of the production cycle.

The technical result is an increase in the manufacturability of the method for producing heat-insulating foam glass in blocks by lowering the foaming temperature, while improving its technical characteristics (compressive strength and moisture absorption), more uniform heating of the charge, and melt due to the heat of the chemical reaction into which the active component enters, and reducing the heating time of the charge, reducing the length of the annealing furnace by 1.5-2.0 times due to an increase in the rate of temperature decrease in this furnace.

This technical result is achieved by the fact that in the method for producing heat-insulating block foam glass, which includes preparing a powdery mixture of glass, a blowing agent and a surfactant component, heating the mixture in a metal form in a foaming furnace, directly foaming, annealing the product, chemically is used as a surface-active component active substance in an amount of 0.8-5.0% of the mass. a mixture that provides the effect of heating a mixture of a chemical reaction, the product of which is a surface-active component, also use metal molds with sliding walls and pushed liners, on which foam glass blocks are transferred to an annealing furnace from a foaming furnace, where it is heated to a foaming temperature of 680-740 ° С lead 0.8-1.5 hours, and the rate of temperature decrease in the annealing furnace from 600 to 50 ° C is 1.2-1.6 ° C / min.

Heating the foam-glass mixture to foaming temperatures at times less than 0.8 hours leads to incomplete heating of the charge. When heated for more than 1.5 hours, part of the blowing agent has time to decompose, which leads to the formation of a thick vitrified film on the surface of the block or non-foaming of the foam glass and, as a result, the spread of the technical characteristics of the foam glass. An increase in the cooling rate in the annealing furnace of more than 1.6 ° C / min leads to the accumulation of mechanical stresses in the block volume, the appearance of cracks, a decrease in strength, and an increase in the moisture absorption of foam glass. Cooling rates less than 1.2 ° C / min lead to an increase in the length of the annealing furnace and a decrease in the productivity of the production line as a whole. At foaming temperatures below 680 ° C, the required values of the viscosity of the glass melt and gas pressure are not achieved when using carbonate blowing agents. At temperatures above 740 ° C, the structure of the foam glass becomes coarse, which leads to a decrease in strength and an increase in moisture absorption. In addition, higher foaming temperatures lead to an unjustified consumption of energy.

The proposed method is as follows. A thinly ground mixture with a specific surface> 400 m ² / kg containing glass (92-98%), a chemically active substance, for example, aluminum powder (0), is prepared from glass or window fray of glass (or specially welded with a composition close to the window). , 8-5%), which, due to the exoeffect of the chemical reaction, additionally heats the mixture, forming a product that is surface-active, which allows one to obtain heat-insulating foam glass with closed gas cells, and a gasifier: chalk, dolomite or marble - (1-3 %). An increase in the amount of chemically active substance in the charge of more than 5% leads to uncontrolled heating of the charge, which leads to a decrease in the quality of foam glass, and a decrease in its amount is less than 0.8% of the mass. requires an increase in foaming temperature and leads to a sharp increase in volumetric moisture absorption from 1 to 25-30%.

The mixture is dosed in a form specially developed by us, which is fed to a tunnel-type foaming furnace, where it is heated from room temperature to 680-740 ° C for 0.8-1.5 hours and foaming itself at this temperature for 20-30 minutes .

Special double molds without caps are used, which, after a foaming oven, using a pneumatic device, slide the locking device from wedges located on the mold walls, as a result of which the two L-shaped mold walls become movable, which prevents the clamping of 2 inserts with foam glass blocks located on them when pushing them out with pushers through holes in the bottom of the mold. Using this form allows you to get blocks of foam glass with a given geometric dimensions of the 5 sides of the block, which facilitates the process of machining the remaining side. The five surfaces of the block in this case have a vitrified surface that increases the strength of the foam glass.

According to the device, the annealing furnace is similar to a foaming furnace, except that instead of thick roller tables intended for transporting heavy molds with blocks, this method conveys a light liner and foam block. The rate of temperature decrease in the annealing furnace from 600 ° C to 50 ° C is 1.2-1.6 ° C / min. Due to the higher cooling rate in the annealing furnace, the annealing time can be reduced from 12 hours to 7.0-8.0 hours and the length of the furnace can be reduced from 50 to 20-25 meters. After the annealing furnace, the foamglass blocks are removed from the liner, packaged and sent to a warehouse. After the foaming furnace and pushing the foam glass block into the hot molds, the insert is inserted, the mold is locked with locks and an inorganic protective coating is applied to the inner surface to prevent the molten glass from sticking. After coating, the molds are filled with the charge and the foaming cycle — annealing is repeated again.

An example implementation of the method.

1600 g of battle of window or bottle glass or a mixture thereof was mixed with 16 g of chalk and 16 g of a chemically active substance, for example, aluminum powder, and ground to a specific surface of ~ 450 m ² / kg. The mixture was poured into a double metal mold, each compartment of which had internal dimensions of 500 × 500 × 120 mm, and was sent to a tunnel-type foaming furnace. The heating time in the oven to the foaming temperature was 1.0 hour. The foaming time at 720 ° C corresponded to 20 min. In the interval between the foaming and annealing furnaces, the foam block was cooled to 600 ° С for 7 min, after which the mold locks were opened for 10-20 s, two inserts with foam glass blocks were pushed out of the molds, and the mold itself was sent again to fill with a charge, and then into the foaming oven. 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, with a density of 200-210 kg / m ³ are shown in the table.

The proposed technology for producing block heat-insulating foam glass allows to obtain high-quality heat-insulating foam glass with a density of ≥160 kg / m ³ . The density of foam glass blocks, equal to ~ 200 kg / m ³ , is most in demand by consumers and recommended for production. This is due to the fact that at a lower density the thermal conductivity coefficient decreases slightly, but the strength of the foam glass block decreases, which increases the percentage of battle during transportation and installation. With an increase in density over 200 kg / m ³ , the weight and strength of the foam glass increase, but the thermal conductivity also increases.

The proposed method for producing heat-insulating foam glass in blocks allows to reduce the foaming temperature of the melt, increase the heating rate of the charge and reduce the cooling temperature in the annealing furnace, is simple, technologically advanced and allows the disposal of household and industrial glass wastes.

Other examples were carried out, as example 1, changing the process parameters. Used the same sizes of forms. Technological modes and parameters of foam glass did not depend on the size of the molds. And the justification of the parameters according to the results of experiments is given above.

Information sources

1. Demidovich B.K. Production and application of foam glass, Minsk, Science and Technology, 1972, p. 304.

2. RF patent No. 2237031 "Method for the production of insulating block foam glass", Bull. No. 27, 09/27/2004, Naumov V.I., Naumov Yu.I.

Table Technical characteristics of the foam glass obtained by the proposed method and prototype Parameters of foam glass According to the proposed method According to the prototype Density of foam glass, kg / m ³ 190-210 190-210 Compressive strength, MPa 3.0-3.4 1.4-2.2 Moisture absorption, volume% <2.0 ≤ 4.0 Frost resistance cycles not less than 100 not less than 100 The coefficient of thermal conductivity, W / m.K 0,040-0,050 0.042-0.050

Claims (1)

A method for the production of heat-insulating block foam glass, including the preparation of a powdery mixture of glass, a blowing agent and a surfactant component, heating the mixture in a metal form in a foaming furnace, directly foaming, annealing the product, characterized in that the amount of reactive component used is chemically active substance in an amount 0.8-5.0 wt.% Of the mixture, providing the effect of a chemical reaction heating the mixture, the product of which is a surface-active component, using there are also forms with sliding walls and pushed liners, on which the foam glass blocks are placed in an annealing furnace from a foaming furnace, where they are heated to a foaming temperature of 680-740 ° C for 0.8-1.5 hours, and the temperature drop rate is from 600 to 50 ° C is 1.2-1.6 ° C / min.