RU2374191C2 - Method of making foam glass-ceramic - Google Patents

Abstract

FIELD: chemistry; glass.

SUBSTANCE: invention relates to production of construction materials, particularly to making granular foam glass-ceramic. Scrap glass and clay are cleaned and crushed. Scrap glass and a blowing agent undergo mixed grinding. The powdered mixture and other components of the charge are proportioned according to the proposed formula. Components of the charge are mixed and fed into a mixer, where they are thoroughly mixed and moistened with water until a plastic mixture with moisture content of 15 to 20% is obtained. The obtained plastic mass is granulated and a separating medium in form of fine-grained saw dust or straw is deposited. The granules are fed into a foaming furnace, where they first undergo drying at temperature not above 400°C, and then foamed at temperature between 750 and 800°C. A reducing environment is maintained in the furnace through incoming natural gas combined with oxygen. The granules are then taken to a sifting machine, where they are cooled, separated by screening off coked separating medium and fine granules. Further, the granules are burnt and taken to the finished product storage.

EFFECT: improved and simpler carbon technology in terms of energy and resource saving and environmental conservation.

8 cl, 2 tbl, 1 dwg

Description

The invention relates to the production of building materials, in particular to the manufacture of granular foam glass ceramic, as well as products from it, used as an effective heat-insulating material in various building insulation constructions, for example floors, walls, roofs of civil and industrial buildings.

A known method of manufacturing granular foam glass (BK Demidovich "Production and use of foam glass. - Minsk: Science and technology, 1972, s.198-201), including crushing and drying glass, weight dosing and joint grinding of glass and carbonate blowing agent in ball mill, feeding the ground mixture into the storage hopper, granulating the mixture on a plate granulator, where liquid glass solution is served as a binder for the granules, screening the little things on a vibrating screen, drying and foaming the granules in a rotary kiln with ground quartz in As a separating medium at a temperature of 780-820 ° С, the granules are annealed to a temperature of 30 ° С, the separating medium is removed, the annealed granules are sent to a warehouse.

The disadvantage of this method is that, the method is based on the use not of cullet, but glass specially made in glass melting furnaces with subsequent granulation of the glass melt, coating the surface of the granules with a heat-resistant emulsion during secondary granulation after grinding, the use of powders as ground quartz, talc or technical alumina, as well as the fact that the known method relates to carbonate technology.

A known method of manufacturing granulated foam glass from cullet (RU 2162825, class C03C 11/00, publ. 2001.02.10) on a continuously operating production line, including crushing cullet, washing and drying it in a washing and drying drum at a temperature of 110-120 ° C , weight dosing and co-grinding of cullet and blowing agent: a mixture of chalk and dolomite (4% by weight of glass) to reach a specific surface of 3000-5000 cm ² / g, granulation on a plate granulator with an aqueous solution of liquid glass, drying the granules on a belt-mesh dryer in the layer to 100 mm at a temperature of 400 ° C to a moisture content of 2%, screening of fines on a vibrating screen, foaming of granules in a rotary kiln with river quartz sand as a separating medium at a temperature of 780-820 ° C, annealing of granules in a rotary kiln to a temperature of 30 ° C and separation granules from the separating medium.

The known method allows to simplify the method of production of granular foam glass and reduce energy consumption, however, it does not allow widespread use of natural resources of the raw material base. The disadvantage of this method is that it relates to carbonate technology.

The closest analogue (prototype) of the method of manufacturing foam glass ceramic is RU 1479435, С04В 14/35, publ. 1989.05.05.

The manufacture of lightweight aggregate is carried out according to the following technology. Glass breakage, dry clay, sludge are crushed in a ball mill. Further, all components are sieved through a sieve of 10,000 holes / cm ² . A mixture consisting of 30-80 wt.% Glass powder, 10-20 wt.% Clay and 10-50 wt.% Sludge is fed to the mixer, where it is simultaneously shut with water in an amount of 20% by weight of the dry mixture, then it is fed to a granulator , the finished granules swell at a temperature of 900-950 ° C in the furnace, after powdering them with a thin layer of dust obtained by dry gas purification in the production of ferrosicilium.

The disadvantage of this method is that, in contrast to the proposed known method, involves the use of a higher expansion temperature and oxygen enriched air during the expansion process.

The task of the invention is the development of a continuously operating process for the manufacture of granular) foamglass ceramics. This invention allows us to solve not only the problem of recycling non-degradable waste-cullet (regardless of its chemical composition, i.e. unsorted cullet), but also the problem of the expanded use of resources of the raw material base, namely the use of the mixture in the recipe and in the process itself available natural inorganic and organic materials: fusible clay, coke, sawdust or straw, etc. with obtaining environmentally friendly high-performance durable durable and heat-insulating material with high performance properties up to 620 ° C. The invention also solves the problem of improving and simplifying carbon technology in terms of energy, resource conservation and environmental protection.

The problem is solved in that in the method of manufacturing granular foam glass ceramics on a continuously operating technological line, including cleaning and crushing of cullet, weight dosing and joint grinding of cullet and blowing agent, weight dosing of ground mixture and other charge components according to the proposed recipe, mixing the components of the charge, granulation, application of a separating medium, foaming of granules, separation of a separating medium, annealing, simultaneously in a continuously operating technological the preparation of another component of the mixture — clay, which consists in cleaning, drying, grinding and dosing it, after which it according to the proposed formulation simultaneously with the other components of the mixture enters the mixer, where the components of the mixture are thoroughly mixed and moistened with water until a plastic mass with a moisture content of 15- 20%, then the plastic mass is fed into the granulator to form raw granules of the required geometric dimensions, depending on the nozzle used, a section is applied to the obtained raw granules the nascent layer in the form of finely divided wood sawdust or straw and sent to the foaming furnace, where in the reducing medium provided by the oxygen-depleted natural gas supplied to it, drying is first carried out at a temperature of not more than 400 ° C, and then the foaming of granules at a temperature of 750- 800 ° C, then the granules are fed to a screen, where they are cooled, separated by screening from the coked separating medium and small granules (small things), then the granules are annealed and sent to the finished goods warehouse.

In the specified method, the joint grinding of cullet and blowing agent is carried out until a specific surface of 4000-5000 cm ² / g is reached.

In this method, the granules are cooled by the exhaust gases of a foaming furnace passing through a recuperator.

In the specified method, the coked separation medium is again used in the technological process.

In this method, the annealing of the granules is carried out at a temperature of 400 ° C.

In this method, a mixture of the following composition is used, wt.%: Pore former 3-5, organic additive 3-5, clay 10-20, cullet the rest,

In this method, coke is used as a blowing agent, and finely ground sawdust or straw is used as an organic additive.

In the specified method, the mixture contains fusible clay.

Practice shows that one of the determining factors affecting the process of obtaining high-quality foam glass is the raw material mixture for its production, since its physicochemical structure, which determines its thermal and mechanical properties, depends on the composition of the mixture. Various attempts have been made previously in this field to improve the properties of foam glass by selecting the composition of the raw material mixture for its manufacture.

In contrast to the prototype, the inventive mixture for foamed glass ceramics expands the use of natural raw materials, as the authors propose to include in its recipe, besides cullet (non-standard cullet - battle of container and building glass) and blowing agent (coke), also low-melting clay and organic additive, as which can be used, for example, finely ground sawdust or straw.

When the content of low-melting clay in the charge is more than 20 wt.% In terms of physical and mechanical properties, the resulting material will be close to expanded clay, and not to foam glass ceramic. When the content of fusible clay in the mixture is less than 10 wt.%, The resulting material is foam glass, and the authors of this invention sought to obtain foam glass ceramic. During the foaming process in a reducing medium in granules made from the proposed mixture, the following occurs. During the heat treatment, a redox reaction occurs between the reducing agent (carbon) and the oxidizing agent (oxides in the glass). As a result, gases are formed in the glass that form bubbles and impart a porous structure to the mass, while these bubbles “push” the excess clay mass onto the surface of the granules, which melts under the influence of the maximum temperature (750-800 ° C), and then hardens upon cooling, forming a durable granule shell, heat-resistant up to 620 ° C. It is important to carry out the foaming process in a reducing medium, which is provided by supplying to the foaming furnace a natural gas depleted in air (oxygen). Providing a reducing environment in the foaming furnace contributes to the composition of the charge, saturated with a carbon component: coke, organic additive: sawdust or straw, as well as the use of an organic additive as a separating medium. The reducing environment and the organic additive added to the proposed mixture has a stabilizing effect on the reproduction of the physico-mechanical properties of the resulting material. The optimal content of organic additives in the proposed charge 3-5 wt.% Determined experimentally.

In the proposed method, in contrast to the prototype, some technological operations are excluded and improved:

- excluded washing and drying of cullet,

- drying and foaming processes are combined in one equipment - in a foaming furnace by first passing through the granules a drying zone with a temperature of not more than 400 ° C, and then a foaming zone with a temperature of 750-800 ° C,

- as a separating medium, finely ground organic material is used, for example wood sawdust or straw, which, after the process of foaming and separation from granules, is sent to a warehouse of organic additives.

- all technological heat treatments are carried out in a reducing environment through the use of natural gas depleted in air (oxygen) and carbon-containing components of the mixture, namely coke, an organic additive in the form of finely ground sawdust or straw.

A technological line that implements a technological process using the proposed mixture recipe consists of sequentially interconnected equipment, units and devices.

The drawing shows a flow diagram of the manufacturing of granular foamglass ceramic, built on the basis of the proposed method and mixture recipe: 1 - cullet warehouse, 2 - jaw crusher, 3 - roller crusher, 4 - cullet reserve tank, 5 - ball mill, 6 - recipe additives warehouse (blowing agent), 7 - storage bin for prescription additives (blowing agent), 8 - loading device, 9 - storage bin for finely ground cullet and blowing agent, 10 - mixer, 11 - clay warehouse, 12 - dry clay storage bin, 13 - grinders tel-disintegrator, 14 - hopper of finely ground clay, 15 - hopper of stock of finely ground organic additives, 16 - screw granulator, 18 - rotary foaming furnace, 17 - recuperator, 19 - screen, 20 - annealing furnace, 21 - finished goods warehouse, SK - scraper conveyor, LC - belt conveyor, ShK - screw conveyor, KE - bucket elevator, MS - batch separator, VD weight dispenser.

The proposed method for the manufacture of granular foam glass is as follows.

From the storage of raw materials 1, the irregular cullet periodically enters, using a scraper conveyor (SC), into the jaw crusher 2 for crushing large pieces, while the operator servicing the processing line manually removes foreign inclusions that have entered the cullet mass, and metal inclusions from the incoming cullet are removed using a magnetic separator (MS). From a jaw crusher 2, a cullet, destroyed to pieces of the same size, is fed into a roller crusher 3 with a bucket elevator (KE), in which cullet is further crushed, after which a mass of crushed cullet is fed to a cullet stock bin 4 using a bucket elevator (KE) .

A portion of cullet measured by a weight doser (VD) using a belt conveyor (LC) is fed to a ball mill 5, cullet is loaded into a ball mill from a conveyor belt using a gate.

At the same time as cullet on the conveyor belt (LC), the loading device 8 feeds the blowing agent measured on the weighing batcher (VD) —coke coming from the stocking bin of the blowing agent 7.

In a ball mill 5, cullet with coke is carefully ground, forming a finely ground mass with a specific surface of 4000-5000 cm ² / g.

From the ball mill 5, the finely ground mass with a belt conveyor (LK) and a bucket elevator (KE) is moved to the stock hopper with a finely ground mass of cullet and coke 9.

At the same time, clay is being prepared on other technological equipment, which is fed from the warehouse 11 via a scraper conveyor (SC) to the dry clay storage bin 12, while the operator manually removes foreign inclusions of non-metallic origin, and metal ones are removed using a magnetic separator (MS) .

Drying the clay in the hopper 12 is carried out by air heated in the recuperator 17 by the exhaust gases of the foaming furnace 16. A weight batcher (BC) from the hopper 12 doses dry clay into the chopper-disintegrator 13, from which the crushed clay enters the hopper with finely ground clay 14.

From the bunker 14, finely ground clay and from the bunker 9, the finely ground mass of cullet and coke are supplied respectively to the weight batchers (VD), from which the measured portions, in accordance with the mixture recipe, are loaded into the screw mixer 10 by screw conveyors (ШК).

In the screw mixer 10, the mixture is thoroughly mixed while supplying the calculated amount of water and finely divided organic additives from the storage tank of the organic additive 15 to obtain a plastic mass with a moisture content of 15-20%, after which it is fed to the screw granulator 16, which forms raw granules of a given geometric size, depending on the nozzle used. The degree of humidification of the mass is determined from the optimal operational parameters used by the devices of the production line.

The obtained raw granules are dumped onto a conveyor belt (LC), on which a separating layer is preliminarily applied in the form of finely divided organic material (accompanying burning medium), for example wood sawdust or straw, while the upper part of the raw granules is “dusted” with the same material using a sprayer. By a conveyor belt (LC), raw granules, without preliminary drying, together with the accompanying burn-out medium, are loaded into a rotary foaming furnace 18. Raw granules passing in the furnace zone with a temperature of not more than 400 ° C are dried, the organic accompanying material is coked, preventing the granules from sticking together and furnace lining. In the zone of the furnace with a temperature of 750-800 ° C, the process of foaming of the granules takes place, after which the granules are fed to the screen 19, where they are cooled by the exhaust gases of the foaming furnace passed through the recuperator 17. The coked separation medium separated from the granules at the screen 19 is returned to the warehouse of the organic additive for further use in the technological process. The granules are annealed in an annealing furnace 20 at a temperature of 400 ° C and then enter the finished product warehouse 21.

Foamed glass ceramics obtained by the proposed technology using the composition of the mixture shown in table 1, was tested for the following technical characteristics.

Determination of the compressive strength of the foamglass granules was carried out in accordance with GOST 21520-89 according to the method of GOST 12852.0-77. To determine the tensile strength, cubic-shaped products with a size of 7.0 × 7.0 × 7.0 cm were used. Products are made of granules with a density of 200-290 kg / m ³ . The test results were calculated by the formula:

R = aKwP / F,

where P is the breaking load

F is the working area of the sample,

and - the conversion factor to the strength of the reference sample with dimensions of 15 × 15 × 15 cm, a = 0.9.

Kw is a conversion coefficient depending on the moisture content of the samples Kw = 0.9. The tests were carried out on the MS-500 press.

The determination of the upper temperature of the application was carried out in accordance with TU 5914-001-43189350-2004 p 8.11. The test results showed that the samples do not lose their integrity and strength properties to a temperature of 620 ° C.

Pellets for flammability, thermal conductivity, hygroscopicity, and water absorption were also tested. The test results are summarized in table 2.

The proposed method for the manufacture of granular foamglass ceramics tested in production conditions, on the basis of which it is assumed the construction and commissioning of a fully mechanized continuously operating line.

Table 1 Composition number Components of a batch Blowing agent Organic supplement Fusible clay Cullet Composition 1 5,0 3.0 10.0 82.0 Composition 2 3.0 4,5 15.0 77.5 Composition 3 4.0 5,0 15.0 76.0 Composition 4 3.0 3.0 20,0 76.0

table 2 Indicator Properties of foam glass ceramics Test method GOST, TU Composition 1 Composition 2 Composition 3 Composition 4 Bulk density, kg / m ³ 200 260 290 240 GOST 17177.3-81 Flammability Does not burn Does not burn Does not burn Does not burn GOST 12.044 Thermal Conductivity, W / mK 0.06 0,075 0,087 0,069 GOST 7076-99 Hygroscopicity, wt.% (Holding for 24 hours in a desiccator at a temperature of 20 ° C at 100% relative humidity) 0.18 0.12 0.10 0.11 GOST 171775-81 The limit of compressive strength, kgf / cm ² 8.2 17,2 25 12.6 GOST 21520-89 Water absorption,% 4.8 2.6 1.7 2.0 Exposure under a layer of water 10 cm for 24 hours

Claims (8)

1. A method of manufacturing foam glass ceramics on a continuously operating production line, including cleaning and crushing of cullet, weight dosing and joint grinding of cullet and blowing agent, weight dosing of ground mixture and other components of the mixture according to the proposed formulation, mixing the components of the mixture, granulation, applying a separating medium, foaming granules separation of the separating medium, annealing, characterized in that at the same time the preparation of another is included in the continuously operating technological line the component of the mixture is clay, which consists in its cleaning, drying, grinding and dosing, after which it according to the proposed formulation simultaneously with the other components of the mixture enters the mixer, where the components of the mixture are thoroughly mixed and moistened with water until a plastic mass with a moisture content of 15-20% is obtained, then the plastic mass is fed into the granulator to form raw granules of the required geometric dimensions, depending on the nozzle used, a separating layer is applied to the obtained raw granules in the form of finely divided x wood sawdust or straw and sent to a foaming furnace, where in the reducing medium provided by the oxygen depleted natural gas supplied to it, drying is carried out first at a temperature of not more than 400 ° C, and then the foaming of granules at a temperature of 750-800 ° C, then the granules are fed to a screen, where they are cooled, separated by screening from the coked separating medium and small granules (small things), then the granules are annealed and sent to the finished goods warehouse. 2. The method according to claim 1, characterized in that the joint grinding of cullet and blowing agent is carried out until a specific surface of 4000-5000 cm ² / g is reached. 3. The method according to claim 1, characterized in that the granules are cooled by the exhaust gases of a foaming furnace passing through a recuperator. 4. The method according to claim 1, characterized in that the coked separating medium is again used in the process. 5. The method according to claim 1, characterized in that the annealing of the granules is carried out at a temperature of 400 ° C. 6. The method according to claim 1, characterized in that a charge of the following composition is used, wt.%: Pore former 3-5; organic additive 3-5; clay 10-20; cullet - the rest. 7. The method according to claim 6, characterized in that coke is used as a blowing agent, and finely ground sawdust or straw is used as an organic additive. 8. The method according to claim 6, characterized in that the mixture contains fusible clay.

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