RU2837030C1 - Mixture for making ceramic bricks - Google Patents

Abstract

FIELD: ceramics.

SUBSTANCE: invention relates to production of ceramic wall articles and can be used in production of ceramic bricks. Ceramic mixture for making bricks includes loam of Buguruslansky deposit, wt.%: SiO₂ 59.24; Al₂O₃ 9.98; Fe₂O_3com 4.48; MgO 2.93; CaO 8.95; K₂O 1.70; TiO₂ 0.71; Na₂O 1.47; LOI 10.54, ash and slag wastes of Orsk TPP-1, wt. %: SiO₂ 31.57; CaO 4.04; MgO 1.34; Fe₂O_3com 3.93; Al₂O₃ 9.34; K₂O 1.01; TiO₂ 0.52; Na₂O 0.33; LOI 47.92 and silicate lump SiO₂ 72.39; Al₂O₃ 0.51; Fe₂O_3com 0.51; Na₂O 25.87; CaO 0.41; SO₃ 0.31 at the following ratio of components, wt.%: low-melting loam 65-75, ash and slag wastes of Orsk TPP 15-25, lump silicate 10.

EFFECT: high strength and reduced water absorption, which increases crack resistance of the raw brick during drying, provides the possibility of defect-free automatic loading and transportation of the dried semi-finished product, expands mineral-raw material base for production of ceramic bricks and colour gamut of finished products depending on quantity of introduced ash-and-slag wastes.

1 cl, 4 tbl

Description

The invention relates to the production of wall ceramic products and can be used in the technology of manufacturing ceramic bricks.

A ceramic mass is known for the production of ceramic bricks and facing tiles of the following composition, wt.%: dispersed crystalline schists 90.0-99.0; dispersed silicate lump 1.0-10.0 (SU 1805119 A1, published 27.08.1990). The disadvantages of this invention are a fairly high average density (1870-2000 kg/ ^cm3 ), which allows them to be classified as low-efficiency building materials in terms of thermal performance and requires an increase in material costs at the manufacturing stage and, as a consequence, makes the mass of wall structures heavier.

The closest in technical essence is the batch for the production of clay bricks (SU 1 379 283 A1, published 03.07.1988), which includes clay, burnout additives and silicate lump in the following ratio of components, mass %: clay 92-83.2%; silicate lump 1-1.8%; unburnt mine rock 7-15%.

The disadvantage of this solution is the low physical and mechanical characteristics of the resulting product - compressive strength of 26.5-29 MPa and a long drying time of 48-60 hours at a temperature of 60-80°C, which leads to significant energy consumption in the production of products.

The technical objective of the invention is to increase strength and reduce water absorption, which allows for increased crack resistance of green bricks during drying, provides the possibility of defect-free automatic loading and transportation of dried semi-finished products, expands the mineral resource base for the production of ceramic bricks and the color range of finished products depending on the amount of ash and slag waste introduced.

The problem is solved in that the batch for the production of ceramic bricks includes low-melting loam, sodium silicate lump and ash and slag waste from Orsk TPP No. 1 (Orsk, Orenburg Region). The components are crushed to a grain size of no more than, mm: 0.16 - loam, 0.08 - sodium silicate lump, 0.32 - ash and slag waste. Unlike the prototype, instead of the plastic molding method, the semi-dry pressing method is used with the following ratio of components, wt.%: low-melting loam 75-55; ash and slag waste 15-35; silicate lump 10.

The main component of the raw mix for brick production is loam from the Buguruslan clay deposit in the Orenburg region, which belongs to the group of medium plastic clays.

Using X-ray phase analysis, the average mineral composition of the average loam sample was determined to be: quartz 32.5%, feldspars: albite 17.4%, microcline 5.2%, micas and hydromicas: muscovite 8.1%, chlorite 7.5%, carbonate minerals: calcite 25.4%, dolomite 3.9%, according to which the clay raw material belongs to the group of hydromica clays with inclusions of quartz, feldspar and calcite. Refractory loam 1150-1170 °C.

Ash and slag waste from Orsk TPP No. 1, i.e. ash and slag waste that is formed during combustion of solid fuel – coal, was used as a leaner and burnout additive to obtain bricks with low shrinkage and improved molding properties. All components of ash and slag are refractory. But in the alloy, the melting point is significantly lower than the melting points of individual components of the charge. The ability of ash and slag waste to spontaneous cementation is determined by such minerals as silicates, aluminates and calcium ferrites, which also improves the strength characteristics of the product.

Mineralogical composition of ash and slag waste of Orsk TPP, wt. %: quartz 51.1; albite 20.04; gypsum 1.47; calcite 4.52; mullite 15.89; impurities of hematite, chabazite and ctenasite 6.98. The content of glassy granules in ash and slag waste is 12%.

The chemical composition of the loam of the Buguruslan deposit in the Orenburg region and the ash and slag waste of the Orsk Thermal Power Plant No. 1 is presented in Table 1.

Table 1. Chemical composition of the feedstock

Type of raw material Oxide content, % _{SiO2 TiO2 Al2O3 ​ Fe2O3 ​} CaO MgO _{Na2O K2O} p.p.p. Loam 59.24 0.71 9.98 4.48 8.95 2.93 1.47 1.70 10.54 Ash and slag waste 31.57 0.52 9.34 3.93 4.04 1.34 0.33 1.01 47.92

To obtain products from the developed ceramic mass, the technology of semi-dry pressing of bricks was used. First, low-melting loam and ash and slag waste from Orsk TPP-1 were dried to an air-dry state at a temperature of 100°C±5, then the components, including silicate lump, were separately ground in a planetary mill, after which they were sifted through a sieve to the required grinding fineness of 0.16 mm, and silicate lump through 0.08 mm.

Then, according to the recipe, the components, dosed at the required ratio, were thoroughly mixed and the mass was evenly moistened to 8-12%.

The amount of water for moistening depended on the content of the ash and slag material of Orsk TPP-1, at 35-12% water, at 15-8% water. The prepared mass was aged in desiccators for 12-18 hours and then sent for molding. For experimental verification of the declared compositions of the masses, cylindrical samples with a height and diameter of 50 mm were made with the ratio of the above components presented in Table 2. The pressing pressure was 20 MPa. After molding, the products were dried in a drying cabinet at a temperature of 100-110 ° C for 2 hours and fired with holding at a maximum temperature of 1000 ° C for 4 hours and subsequent cooling for 14 hours. After that, their physical and mechanical properties and compliance with the requirements of GOST 530-2012 "Ceramic brick and stone. General specifications" were determined.

Table 2 shows the compositions of the raw materials for the manufacture of ceramic bricks, and Table 3 shows the amount of substance in oxide form in molecular percent of the proposed ceramic masses and the prototype. Table 4 shows the physical and mechanical characteristics of products made from the proposed and known ceramic mixtures.

Table 2. Compositions of raw materials

Component Content of components, wt. % in composition 1 2 3 Prototype Loam 75 65 55 92-83.2 Ash and slag waste 15 25 35 - Silicate lump 10 10 10 1-1.8 Unburnt mine rock - - - 7-15

Table 3. Amount of substance in oxide form in molecular percent of the proposed ceramic masses and prototype

Name of chemical element Amount of substance, % Prototype The proposed ceramic mass 1 2 3 _SiO2 75.94 70.81 70.67 70.52 _{Al2O3 ​} 12.62 6.61 6.89 7.20 Fe ₂ O _3total 2.82 1.89 1.96 2.03 MgO 3.34 4.48 4.39 4.29 CaO 1.94 9.90 9.70 9.47 _K2O 1.3 1.14 1.14 1.14 _TiO2 0.63 0.57 0.58 0.59 _Na2O 1.41 4.56 4.64 4.72 SO ₃ 0,00 0.03 0.03 0.04 Sum 100 100 100 100

Thus, according to theoretical data by Avgustinik, A.I. "Ceramics", the obtained indicators of the proposed ceramic masses in relation to Al ₂ O ₃ + TiO ₂ indirectly indicate sintering and are in the optimal range of 7-28%. Also, the increase in strength indicators is estimated depending on the content of iron oxide, which is in the range of 2-15 (Al ₂ O ₃ + TiO ₂ ) / Fe ₂ O ₃ in terms of dry matter. These indicators for the proposed masses are 3.79; 3.81; 3.84, respectively, which allows us to conclude that the finished products will have high physical and mechanical properties.

Table 4. Physical and mechanical properties of bricks made from the proposed ceramic masses and prototype

Properties Samples made from the compositions 1 2 3 Prototype Firing temperature, °C 1000 1000 1000 950-1050 Pressing pressure, kgf/ ^cm2 200 200 200 80-100 Moulding moisture, % 8 10 12 18 Average density, g/ ^cm3 1.86 1.83 1.78 1.57-1.59 Water absorption, % 11.24 12.2 12.6 12-12.8 Compressive strength, kgf/ ^cm2 306.8 291.6 255.9 265-282 Bending strength, kgf/ ^cm2 82.6 77.2 65.3 93-101 Frost resistance, cycles 61 56 54 51-53

Thus, in comparison with the prototype, the claimed invention is characterized by:

- reducing the firing temperature by 50°C and holding for 7 hours;

- reducing the molding moisture content from 18 to 8-10%;

- less tendency to crack during drying and improved water absorption rates (reduced by 6.3-1.6%);

- higher porosity: compressive strength increases by 28-36%;

- increase in frost resistance from 1-10 cycles;

- obtaining products with clear edges and maximum deviations of ±2 mm in accordance with GOST requirements.

Claims (2)

Ceramic mass for producing bricks, including low-melting clay and production waste, characterized in that the clay used is loam of the Buguruslan deposit, wt.%: SiO ₂ 59.24; Al ₂ O ₃ 9.98; Fe ₂ O _3total 4.48; MgO 2.93; CaO 8.95; K ₂ O 1.70; TiO ₂ 0.71; Na ₂ O 1.47; LOI 10.54, and the waste is ash and slag waste of Orsk TPP-1, wt.%: SiO ₂ 31.57; CaO 4.04; MgO 1.34; Fe ₂ O _3total 3.93; Al ₂ O ₃ 9.34; K ₂ O 1.01; TiO ₂ 0.52; Na ₂ O-0.33; LOI 47.92 and silicate lump SiO ₂ 72.39; Al ₂ O ₃ 0.51; Fe ₂ O _3total 0.51; Na ₂ O 25.87; CaO 0.41; SO ₃ 0.31 with the following ratio of components, wt.%: Low-melting loam 75-65 Ash and slag waste from Orsk TPP 15-25 Silicate lump 10