RU2514030C1 - Ceramic mixture and method of making ceramic articles based thereon - Google Patents

Abstract

FIELD: chemistry.

SUBSTANCE: invention relates to production of ceramic articles for construction purposes and can be used in making bricks and tiles. The ceramic mixture for making structural ceramic articles contains clay with content of Fe₂O₃>4%, natural sand and volcanic ash, with the following ratio of components, wt %: clay 70-90; sand 5-15; volcanic ash 5-15. The method of making structural ceramic articles from the ceramic mixture involves preparing a crude mixture, moulding articles, rapid drying and firing.

EFFECT: producing a ceramic mixture which reduces the cost of ceramic articles owing to use of a rapid drying technique.

2 cl, 3 tbl

Description

The invention relates to the production of building materials based on highly sensitive clay drying materials using high-speed drying.

Known ceramic mass (Pat. RF №2422398, IPC С04В 33/132) containing clay, cement dust, ground cullet and talc in the following ratio of components, wt.%: Clay 85.0-89.5; cement dust 0.5-1.0; ground cullet 4.0-6.0; talc 6.0-8.0.

The disadvantages of this invention are: multicomponent mass, the complexity of homogenization of the raw material mixture, additional energy consumption for grinding cullet and talc.

Closest to the invention is a ceramic mass (US Pat. RF No. 2430054, IPC С04В 33/00), containing, wt.%: Clay 74.5-84.5; crushed brick scrap after drying 0.1-1.0; volcanic ash 15.0-25.0.

The disadvantage of this invention is the need to use traditional drying modes that increase energy costs for production.

A known method of manufacturing ceramic products (Pat. RF №2204541 IPC С04В 33/00), including grinding clay raw materials, the introduction of dehydrated clay and sawdust, molding, drying, firing. The method uses clay Yumaguzinsky deposits with a chemical composition, wt.%: SiO ₂ 55,12; Al ₂ O ₃ 12.83; Fe ₂ O ₃ 4.75; CaO 6.02; MgO 1.91; SO ₃ 0,050. The components are taken in the following proportions, wt.%: Clay 65-70; dehydrated clay 12-25; sawdust 10-20. Firing is carried out in the temperature range 980-1050 ° C, while heating and cooling are carried out at a speed of 70-95 ° C / h.

The disadvantage of this invention is the need for the preparation of dehydrated clay, which greatly complicates the process.

A known method of manufacturing ceramic products (Pat. RF №2235080 MPK С04В 33/02, С04В 33/00), including the preparation of a thinning additive based on ash from the burning of industrial and domestic wastewater, mixing it with clay to the composition, in%: clay 90 -75, ash 10-25, forming blanks, drying and firing, while the preparation of a thinning additive is carried out by selecting 30-60% of the total clay volume, introducing it into the ash and forcibly dynamic contact of clay and ash for 5-30 minutes at the ratio of clay and ash from 2.7: 1 to 1.2: 1.

The disadvantage of this invention is the need for the introduction of an additional operation for the preparation of a thinner additive.

The objective of the invention is the use of ceramic mass, which allows to reduce the cost of ceramic products through the use of high-speed drying technology.

Volcanic ash, used to expand the raw material base and reduce the cost of finished products, has a depleting effect on clay and helps to intensify sintering processes due to the content of a significant amount of active amorphous silica and alkaline oxides. The use of high-speed drying not only helps reduce energy costs for production, but also allows the use of kaolinite-montmorillonite clay raw materials highly sensitive to drying, whose behavior under conditions of high-speed drying differs from traditional technologies.

The task and technical result are achieved due to the fact that the proposed ceramic mass for the manufacture of bricks and tiles contains in its composition, wt.%: Clay 70-90; silica sand 5-15; volcanic ash 5-15, and the drying of the semi-finished product is carried out by a high-speed method when heated at a speed of 3 ° C / min to a temperature of 150-200 ° C, for 4-8 hours.

The preparation of the ceramic mass is carried out by coarse grinding of raw materials, the chemical composition of which is given in table 1, mixing, fine grinding and homogenization. Ceramic products are molded by plastic molding. Then the semi-finished product is subjected to high-speed drying at a temperature of 150-200 ° C with a temperature set speed of 3 ° C / min. Drying time depends on the dimensions of the product and ranges from 4 to 8 hours. The firing of the dried semi-finished product is carried out at a temperature of 1050 ° C.

Ceramic products were made as follows. To prepare the mass, the charge composition of which is given in Table 2, sand in an amount of 10% and volcanic ash in an amount of 10%, passed through a vibrating screen, are fed to stone extraction rollers together with clay in an amount of 80%, subjected to loosening and magnetic separation. Then they are mixed in a twin-shaft mixer and joint grinding on a roll crusher. Then, after aging for 24 hours, the mixture is fed to a fine-grinding mill, then it is fed to a twin-shaft mixer with steam humidification, where it is finally homogenized and dampened to the molding moisture. The mass passing through the clay scraper is molded on a screw vacuum press, cut and takes its final shape (in the manufacture of tiles) on a pre-press. The molded products are dried at a temperature of 150-200 ° C with a speed of 3 ° C / min to a final moisture content of not more than 2% and fired at a temperature of 1050 ° C. The properties of the calcined products are given in table.3.

Compositions 1, 2 were made with optimal parameters of the proposed technical solution, compositions 3, 4 - with transcendental parameters of the proposed technical solution.

Table 1 Name of material Content, wt.% SiO ₂ Al ₂ O ₃ Fe ₂ O ₃ FeO CaO MgO K ₂ O Na ₂ O With _org. SO ₃ RFP ∑ Clay 64.56 22.78 4.49 - 0.46 0.46 - - 1.43 - 8.87 100.00 Sand 97.46 1.68 0.30 - 0.38 0.38 - - - - - 100.00 Ashes 65.25 17.00 1.45 1.45 4.00 4.00 3.00 3.70 - 0.10 2.75 100.00

                                                                        table 2 Components The content of components, wt.%, In the compositions one 2 3 four Clay 80.0 70.0 60.0 95.0 Quartz sand 10.0 15.0 20,0 2,5 Volcanic ash 10.0 15.0 20,0 2,5

Table 3 Indicators Indicators for products made from the mass of the composition one 2 3 four Ductility,% 13 12 8 17 Binding ability, MPa 1,2 1,1 0.8 1.4 Sensitivity to drying, with 105 118 130 85 Compressive strength, MPa 32 24 16 26 Air shrinkage,% 6.3 4.1 3.0 7.2 Fire shrinkage,% 1.4 1,2 1,1 1.8 Water permeability Waterproof Waterproof Waterproof Waterproof Frost resistance More than 25 cycles More than 25 cycles Less than 25 cycles More than 25 cycles Mass 1 m ^{2 of} coating, kg 24.3 21.0 20.1 25.7

From table 3 it is seen that only the use of mass compositions in the range specified in the method, allows to obtain ceramic products that meet all the requirements. A decrease in the ratio of clay to sand and volcanic ash leads to a significant decrease in the strength and frost resistance of finished products, and an increase in this ratio does not allow to obtain a ceramic mass that is less sensitive to drying, which makes it impossible to use high-speed drying modes.

Claims (2)

1. Ceramic mass containing clay, volcanic ash, characterized in that it further comprises quartz sand in the following ratio of components, wt.%:
Clay 70-90 Volcanic ash 5-15 Quartz sand 5-15 2. A method of manufacturing ceramic products from ceramic mass according to claim 1, including preparing a raw mix, molding, drying and firing, characterized in that the drying of the semi-finished product is carried out by a high-speed method when heated at a speed of 3 ° C / min to a temperature of 150-200 ° C , for 4-8 hours.