RU2387617C1 - Method for production of raw materials mix for ash-ceramic wall materials - Google Patents

Abstract

FIELD: construction. ^ SUBSTANCE: method for production of raw materials mix for ash-ceramic wall materials may be used in production of beating and facing wall construction and also heat insulation materials for metallurgical equipment, which are manufactured on the basis of production waste - ash from burning of coals. Method for production of raw materials mix for ash-ceramic wall materials includes production of slurry by joint wet grinding of clay and silica-alumina alkali-containing sintering additive. Mixing of slurry with rated amount of ash, at the following ratio of components by dry mass, wt %: clay - 8-50; silica-alumina alkali-containing sintering additive - 5-40; ash from burning of coals - 20-90. At the same time, according to dry mass, 0.1-1.0 wt % of organic and/or inorganic disperser-plasticiser is added into slurry. ^ EFFECT: increased physical and mechanical properties and reduction of power inputs. ^ 2 cl, 1 tbl

Description

The invention relates to the building materials industry (products) and can be used in the production of load-bearing and facing wall building, as well as heat-insulating materials for metallurgical equipment made on the basis of production waste - ash from burning coal.

The prior art compositions of raw mixes based on fly ash of thermal power plants (TPPs) and methods for making ceramic-ceramic building materials from them are known. Known raw mix for the manufacture of tiles for external cladding of buildings (RU 2323194, publ. 2008) [1]. The mixture contains in wt.%: Ash TPP (40 ÷ 48), clay (38 ÷ 42), phosphorus slag (4 ÷ 8), lime (8 ÷ 10). The method of obtaining products from this mixture includes grinding clay into powder, mixing with pre-ground phosphoric slag, adding lime, forming tiles, autoclaving in a saturated steam atmosphere at a pressure of 0.9 MPa and a temperature of 170 ÷ 180 ° C for 8 ÷ 10 hours.

Known raw mix for wall blocks and panels for the construction of storage and livestock buildings, garages (RU 2326852, publ. 2008) [2]. This mixture contains in wt.%: Ash TPP (40 ÷ 50), clay (40 ÷ 50), caustic soda (2 ÷ 4), ground granulated silicomanganese slag (6 ÷ 8). Caustic soda is added to the ground granulated slag of silicomanganese, mixed, the resulting mass is kept for 2–3 hours, then the ash of the thermal power station and clay are added to it. From a raw material mixture with a moisture content of 7 ÷ 9% are formed semi-dry products that are fired at a temperature of 950 ÷ 1000 ° C.

Also known is the raw material mixture for wall materials (RU 2304123, publ. 2007) [3], which contains in wt.%: Ash TPP (50 ÷ 60), clay (30 ÷ 40), caustic magnesite (5 ÷ 7) Ceramic battle (3 ÷ 5). The preparation of this mixture also involves mixing the starting components.

As can be seen from the sources [1 ÷ 3], raw mixtures, differing in composition and preparation process, are aimed at solving the same problem - increasing the mechanical strength of materials obtained from these mixtures. Moreover, despite the rather high quantitative content of TPP ash in their composition, it acts in them as a thinner additive and an additional energy source during firing, and not the main component.

A known method of producing raw material mixtures for ceramic-ash materials with a wide range of physical and mechanical properties, where the ash TPP is used as the main source of raw materials for the production of ceramic wall materials (S.Zh.Saybulatov "Resource-saving technology of ceramic brick based on the ash TPP", M .: Stroyizdat, 1990) [4]. According to the known method, the ash of TPPs is plasticized with binders, which are used as various clays. For the optimal composition of zologlinnyh mixtures, it is recommended that they contain 15–25% highly plastic or 25–35% medium plastic clay. Moreover, the known method [4] involves mixing clay and ash with dampening the mixture to a moisture content of 17 ÷ 25%. To obtain products, the mixture is processed on stone grinding rollers of fine grinding, molded on a plastic molding press without evacuation, a primary beam ("wad"), a "wad" is aged for at least 24 hours, a beam is formed using a plastic method, which is cut into individual products, dried in tunnel or chamber dryers at a maximum temperature of 85 ÷ 110 ° C to a residual moisture content of 1.5 ÷ 10.7%, and then fired in batch furnaces at a maximum firing temperature of 1100 ÷ 1180 ° C.

The obtained ceramic-gold wall materials - solid and hollow ash bricks and ceramic stone, have the following physical and mechanical properties: compressive strength 10 ÷ 60 MPa, bending - 2.5 ÷ 20 MPa, bulk density 1080 ÷ 1600 kg / m ³ , frost resistance 25 ÷ 120 and more cycles, water absorption 10 ÷ 27%, there is a link to the possibility of obtaining materials with thermal conductivity of 0.4-0.5 W / (m · K). In this case, the best values of the quality indicators of wall materials are achieved by using a mixture of composition with an ash content of less than 60 wt.%. With an increase in the amount of ash in the composition of the known raw material mixture, the quality indicators of wall materials decrease.

In addition, despite the possibility of achieving high performance in a wide range of physicomechanical properties of wall materials obtained by the above technology, its disadvantages include the following. Before the stage of forming products, the raw mix in the form of a moistened mixture of clay and ash requires processing on a fine grinding roll, molding the primary beam, and aging for at least 24 hours. Thus, the process of preparing the raw mix for the manufacture of products from it is complex and accordingly costly. The increased humidity of the feedstock for the preparation of products (17 ÷ 25%)

causes additional costs for their drying.

The use of highly plastic and, therefore, more expensive clays with an ash content of more than 70 wt.%, Or a high clay content (30-50 wt.%) Leads to increased density and thermal conductivity of the resulting products. The use of the plastic molding method causes great laboriousness and high energy consumption for the process of obtaining products, despite the fact that this method has large errors in observing the shape and size of the products, their less uniform and denser structure, large apparent density and, consequently, greater thermal conductivity. It should be noted that the product brand is higher than 125 (strength more than 150 MPa, frost resistance more than 50 cycles) are obtained only from mixtures with ash content of less than 70 wt.%.

The objective of the present invention is to obtain a raw material mixture that allows to produce wall materials with high quality indicators in a wide range of physical and mechanical properties while reducing energy and raw materials costs by expanding the raw materials base of the ceramic industry, as well as accelerating the solution of the problem of recycling boiler ash dumps, State District Power Station and Thermal Power Station.

To solve this problem, the method of obtaining the raw material mixture for ceramic-gold-grained wall materials involves the preparation of a slip by co-wet grinding of clay and an aluminosilicate alkali-containing sintering additive, mixing the slip with the estimated amount of ash from burning coal in the following ratio of components by dry weight, wt.%: Clay (8 ÷ 50), aluminosilicate alkali-containing sintering additive (5 ÷ 40), ash from burning coal (20 ÷ 90).

As aluminosilicate alkali-containing additives, felsite, feldspar, nepheline - syenite, pyrophyllite and other materials can be used.

Upon receipt by joint wet grinding of a slip from clay and an aluminosilicate alkali-containing additive, complete homogenization of these components occurs, as well as complete “dissolution” (dispersion) of the clay and production of colloidal (ultrafine) fractions in the slip, which increase the plasticity of the mass necessary for the strength of the products. The use of additives - viscosity reducers: surfactants - dispersants - organic (superplasticizers) and / or inorganic (water glass, soda, etc.) used in concentrations conventional for ceramic technology allows to achieve low humidity and the required fluidity of the slip.

The introduction of clay in the form of a slurry in the amount of 8 ÷ 50 wt.% Into the raw material mixture provides optimal technological properties of the mass and the optimal pore structure of the calcined products, ensuring their high strength and frost resistance, as well as low thermal conductivity.

The introduction of clay in an amount of less than 8 wt.% Will lead to insufficient connectivity and plasticity of the mass and, accordingly, to a large number of defects in the molding of products and their insufficient strength after firing. The introduction of clay in an amount of more than 50 wt.% Can lead to an excessive increase in the plasticity of the mass, which makes the process of semi-dry pressing or hard molding impossible, to increase the sensitivity of the molded products to drying, increase the cost of drying and firing products, increased shrinkage of products during drying and firing and the formation of too dense products with suboptimal pore structure.

The introduction of the aluminosilicate alkali-containing additive in the declared amounts into the raw material mixture ensures the optimum sintering temperature range of the products due to the formation of a highly viscous liquid phase during firing in products, absorbing free silica from clay and ensuring minimal deformation of the products in firing and optimal product structure after firing.

The introduction of an aluminosilicate alkali-containing additive of less than 5 wt.% Does not affect the sintering process of products, and its introduction into the charge in an amount of more than 40 wt.% Leads to a narrowing of the sintering period of the mass, which leads to an increase in the number of scrap products in firing and the formation of brittle fragile highly porous structure of products after firing ("swelling" of products).

The presence in the ash of a large amount of glass phase aluminosilicate composition and a small number of crystalline phases - quartz, mullite, provides high ash sintering activity and low specific density and thermal conductivity of both the ash itself and products based on it. The size and shape of the ash grains - spherical, whole and broken particles from 4 to 300 microns in size with a predominant size of 50 ÷ 100 microns, moistened with the stated amount of slip, provide good mobility of the raw material mixture, which ensures uniformity of the structure of the pressed products and the formation of finely porous structure in the calcined products with a predominant pore size of up to 0.3 μm, which, as established, are not filled with water due to the difficulty of removing air from them and, thus, do not participate in the destruction of wall mats Series when freezing.

The introduction into the raw mix of ash from the combustion of coal in an amount of less than 20 wt.% Does not allow to obtain the optimal structure of wall materials due to the high ductility and density of the resulting mass. The introduction of ash from coal burning in an amount of more than 90 wt.% Leads to a decrease in the strength of wall materials due to a decrease in ductility and mass cohesion during pressing and an increase in the required sintering temperature of wall materials, which is associated with an increase in the cost of production.

Thus, the essence of the invention is to obtain a raw material mixture for ceramic-ceramic materials containing a wide range of the amount of ash used from burning coal, with an optimal ratio of the amount of all components of the mixture, which together with the receipt of the slip from mixed wet grinding of clay and aluminosilicate alkali-containing sintering additive, miscible with ash from burning coal, provides ductility, cohesion, sintering mass and the optimal structure of calcined products. The process of preparing the raw material mixture to obtain products from it, including the preparation of a slip from clay and an aluminosilicate alkali-containing additive, followed by the introduction of ash into the slip, is simpler than in the prototype. Moreover, the raw material mixture prepared in the claimed manner can be molded by semi-dry pressing or hard molding, which ensures the optimal structure of products that are fired at the optimum temperature, ensuring complete sintering of the mass.

A new technical result achieved by using the claimed invention is to expand the range of application of ash from coal combustion without compromising the quality of the wall materials obtained, as well as to improve the manufacturability of the raw mix for the manufacture of ceramic-ceramic wall materials, including, including the possibility of using more advanced and less costly methods of forming products.

At the same time, the use of ash from coal burning as the main starting component for the production of wall materials will allow expanding the raw material base of the ceramic industry, accelerating the solution of the problem of utilization of ash dumps of boiler houses, state district power stations and thermal power plants, and increasing production efficiency with high quality of the obtained wall materials.

To obtain wall materials used:

- ash from the combustion of coal Reftinskaya state district power station (p. Reftinsky Sverdlovsk region.). The chemical composition of the ash, wt.%: SiO ₂ - 50 ÷ 65, Al ₂ O ₃ - 25 ÷ 30, Fe ₂ O ₃ - 3 ÷ 6, CaO + MgO - 2 ÷ 4, R ₂ O - 1 ÷ 3, pp .≤5;

- clay of the Nizhneuvelskoye field of the NUK TU 14-8-338-80 brand. The chemical composition of clay, wt.%: SiO ₂ - 60 ÷ 70, Al ₂ O ₃ - 20 ÷ 30, Fe ₂ O ₃ - 3 ÷ 5, CaO + MgO - 1 ÷ 2, R ₂ O - 1 ÷ 3, pp . - 10 ÷ 15;

- clay deposits Starkovskoe-2 and Krasnoarmeyskoye-2 (Asbest, Sverdlovsk region.). The chemical composition of clay, wt.%: SiO ₂ - 65 ÷ 75, Al ₂ O ₃ - 15 ÷ 20, Fe ₂ O ₃ - 4 ÷ 6, CaO + MgO - 2 ÷ 3, R ₂ O - 2 ÷ 4, pp . - 5 ÷ 8;

- felsite of the Pokrovsky deposit (Sverdlovsk region). The chemical composition of felsite, wt.%: SiO ₂ - 70 ÷ 80, Al ₂ O ₃ - 10 ÷ 15, Fe ₂ O ₃ - 1 ÷ 3, CaO + MgO - 1 ÷ 3, R ₂ O - 5 ÷ 7, pp . - 1 ÷ 3;

- feldspar of the Vishnevogorsk field of the PShS-0.50-21 brand according to GOST 13451-77;

- nepheline - syenite of the Vishnevogorsk field of the KPSHM-0.2-0.5 grade GOST 15045-78;

- liquid sodium glass GOST 13078-81 "Liquid sodium glass. Technical conditions". Glass modulus 3.0 and density 1.47 ÷ 1.52 g / cm ³ ;

- technical water GOST 23732-79 "Water for concrete and mortars. Technical conditions";

- technical lignosulfonate TU 2455-028-00279580-2004.

From the above clay and the aluminosilicate alkali-containing component with the addition of water glass and lignosulfonate, a slip of 1.44 g / cm ³ and a humidity of 50% was prepared by technical wet co-grinding. The finished slip was mixed with the calculated amount of ash from burning coal in a forced planetary mixer. The mass was pressed at a pressing pressure of 300 ± 25 kg / cm ² and subjected to heat treatment at a temperature of 1180 ± 30 ° C.

Examples of the composition of the raw mix for the manufacture of wall materials and the properties of the materials obtained are presented in tables 1 and 2.

From the tables it can be seen that wall materials made on the basis of the obtained raw material mixture have a sufficiently high mechanical strength (brand of at least 200) and frost resistance of at least F 50, lower apparent density and thermal conductivity than ceramic-ceramic wall materials obtained by known technology . In addition to these advantages, the technology of manufacturing wall materials from a mixture obtained according to the claimed method has fewer harmful emissions during heat treatment, and the materials themselves are characterized by greater stability of properties during operation, which allows them to be successfully operated in many areas of industrial and civil construction.

Table 1. Raw mixes for ceramic-ceramic wall materials Content, wt.% Components The inventive composition one 2 3 four 5 6 7 8 9 10 eleven 12 13 fourteen Clay NUK 5 10 thirty 40 - - - - fifteen 10 - - 10 - Clay deposits Starkovskoe-2 and - - - - 40 fifteen 10 fifteen - - fifteen fifty - 10 Red Army-2 Felsit 5 8 10 0.5 40 fifteen twenty 5 - - - 8 8 Feldspar PShS-0.50-21 - 8 5 - - Nepheline-syenite KPSHM-0.2-0.5 10 - 5 - - Coal burning ash 90 82 60 59.5 twenty 70 70 80 75 75 80 45 82 82 Liquid glass* 0.001 0.01 0.005 0.01 0.003 0.007 0.005 0.01 0.007 0.001 0.009 0.01 0.06 - Technical lignosulfonate * 0.5 0.1 0.1 1.0 0.7 0.1 0.3 0.7 1.0 0.5 0.7 0.5 - 0.5 Water* 17 17 eighteen eighteen 17 17 eighteen eighteen eighteen 17 17 eighteen 17 17 * over 100%

Table 2. Properties of ceramic-ceramic wall materials Properties of wall materials ** one 2 3 four 5 6 7 8 9 10 eleven 12 13 fourteen The limit of compressive strength, N / mm ² twenty 45 fifty 35 60 35 45 35 thirty fifty 45 45 47 45 The apparent density, g / cm ³ 1.2 1.3 1.3 1.5 1.6 1.5 1.5 1.3 1.5 1.3 1.3 1.5 1.3 1.3 Frost resistance, cycles 60 70 70 45 70 70 70 70 fifty 70 70 70 60 60 Thermal conductivity, W / (m * K) 0.3 0.3 0.5 0.3 0.4 0.3 0.4 0.4 0.5 0.4 0.4 0.5 0.3 0.25 ** water absorption of materials obtained from mixtures of composition 1-14 is 10 · 12%.

Claims (2)

1. A method of obtaining a raw material mixture for ceramic-ceramic wall materials, comprising mixing ash from burning coal, clay and a sintering additive, characterized in that a slurry is prepared from clay and an aluminosilicate alkali-containing sintering additive with joint wet grinding, which is mixed with the calculated amount of ash, in the following ratio components by dry weight, wt.%: clay 8-50; aluminosilicate alkali-containing sintering additive 5-40; ash from burning coal 20-90. 2. The method according to claim 1, characterized in that 0.1-1.0 wt.% Organic and / or inorganic plasticizer dispersant is introduced into the slip on a dry basis.