RU2731323C1 - Ceramic mixture - Google Patents

Abstract

FIELD: construction materials; technological processes.

SUBSTANCE: invention relates to production of ceramic construction materials and articles, particularly, to light color clinker brick of soft molding based on siliceous opal-cristobalite rocks – gaize. Ceramic mixture containing opal-cristobalite rock – gaize, with grinding degree less than 0.5 mm, superplasticiser C-3, additionally contains finely ground chalk-like limestone (less than 0.05 mm) and lithium carbonate, with the following ratio of components, wt%: opal-cristobalite rock – gaize – 60–70; chalk-like limestone – 5–15; lithium carbonate – 0.6–1.2; superplasticiser C-3 – 0.2–1.0; water – balance.

EFFECT: obtaining white clinker bricks with low water absorption, high strength and frost resistance.

1 cl, 2 tbl, 1 ex

Description

The invention relates to the production of ceramic building materials and products, in particular, to wall clinker bricks of soft molding of light colors based on siliceous opal-cristobalite rocks - flasks, produced according to GOST 530-2012 "Ceramic bricks and stones. General technical conditions ".

A soft-molded brick is a brick made using the technology of filling molds with a mass with a moisture content higher than the molding one, providing the operational characteristics of the masonry and creating a decorative effect of "antique masonry" with a visually "aged" surface.

Soft-formed facing brick is a very popular product nowadays. In Russia, it is produced in small quantities by only a few enterprises. White brick is especially appreciated, since the raw materials for its production are very limited.

Known ceramic mass based on siliceous rocks (flasks) with a small amount of low-melting impurities. (In N. Ivanenko Building materials and products from siliceous rocks, Budevelnik, Kiev, 1978, pp. 10, 22-23).

The closest technical solution is a ceramic mass (patent RU 2354628, С04В 35/14, publ. 05/10/2009), including opal-cristobalite rock - flask, crushed to a particle size of less than 1 mm, additionally containing marly clay with a particle size of less 0.1 mm, superplasticizer C-3, with the following ratio of components, wt. %: opal-cristobalite rock (flask) - 50-80; marly clay - 5-30; superplasticizer C-3 - 0.1-1.2; water is the rest.

The disadvantage of the known mass is relatively high water absorption rates - more than 6% (for wall clinker bricks, water absorption should be no more than 6%), insufficient frost resistance of products - less than 75 cycles (frost resistance for wall clinker bricks should be more than 75 cycles), and also insufficient white color of products.

The objective of the present invention is to obtain a facing clinker brick of white color with reduced water absorption, increased strength and frost resistance.

The essence of the invention lies in the fact that the ceramic mass, including the opal-cristobalite rock - flask, with a grinding degree of less than 0.5 mm, superplasticizer C-3, additionally contains finely ground chalk-like limestone (less than 0.05 mm) and lithium carbonate, with the following the ratio of components, wt. %:

Opal-cristobalite rock - flask - 60-70;

Chalk-like limestone - 5-15;

Lithium carbonate - 0.6-1.2;

Superplasticizer C-3 - 0.2-1.0;

Water is the rest.

The technical result is achieved due to the fact that flasks are the most suitable raw material (especially clay varieties) for soft molding technology, since even when using high-quality clays, ceramic masses for soft molding should contain a lot of weakening agent in the form of chamotte and other components (magazine "Construction materials ", 2019, No. 12. S. 18-23). The opal-cristobalite rock crushed to a particle size of less than 0.5 mm - a flask - promotes better sintering during firing and, as a result, an improvement in strength characteristics, as well as active interaction with particles of chalk-like limestone.

The use of chalk-like limestone with a particle size of less than 0.05 mm allows you to enhance the clarifying ability, increase strength, reduce water absorption, increase the degree of sintering, and also eliminate the formation of free calcium oxide ("dutik", lime decay).

The introduction of lithium carbonate contributes to an increase in the degree of sintering, an increase in the strength of products, a decrease in water absorption and an intensification of the clarification of the shard.

The introduction of C-3 makes it possible to reduce the molding moisture, improve the molding properties, and achieve greater uniformity of the ceramic shard, which, in turn, significantly increases the strength of fired products.

Characteristics of raw materials

1. Opal-cristobalite rock - opoka

Light dense fine-porous rocks, consisting mainly of the smallest (less than 0.005 mm) particles of opal-cristobalite. Their average density is 1200-1600 kg / m ³ , their porosity reaches 55% (usually 30-40%).

Opokas are not pure silicites, but multicomponent systems. Their constant component, along with amorphous silica, are clay minerals, which were contained in one or another quantity. Sandy-silty and carbonate material may be present as impurities, the particles of which usually do not exceed 0.01 mm. In this regard, various lithological varieties of opokas are distinguished - clay, sandy, carbonate and mixed. The variety of composition determines a wide range of physical, technical and technological properties. The average chemical composition of the investment ring is shown in Table 1.

Flasks are a very promising raw material for the production of ceramic bricks using soft molding technology. Since they are stone-like raw materials and contain clay minerals in addition to opal silica, the degree of grinding can be used to regulate the molding properties of the raw materials and the physical and mechanical properties of finished products, which greatly simplifies and reduces the cost of the production process.

Russia has the largest raw material base of siliceous opal-cristobalite rocks. On the territory of Russia, they are widely found in the regions of the Volga and Don regions, Western Siberia, in the south of Russia, in the central and western regions of the European part of Russia, Leningrad region, Dolny Vostok, Kola Peninsula, and Kamchatka.

2. Chalk-like limestone (chalk) belongs to sedimentary biogenic rocks and contains more than 90% calcium carbonate. It has low strength (R _comp. - up to 15 MPa) and density (on average 1500-1700 kg / m ³ ), increased porosity and water absorption (up to 30%). In ceramic technology it is used as a 2nd order flux and a brightening component. The average chemical composition of marly clays is shown in Table 1.

3. Superplasticizer C-3 (TU 6-36-020429-635) is obtained on the basis of sodium salts of the condensation product of naphthalenesulfonic acid and formaldehyde. Liquid or water-soluble powder (we used a liquid, since molding masses by soft molding technology are characterized by high humidity), does not emit when storing harmful gases and vapors. Aqueous solutions of C-3 do not change their properties when heated to 85 ° C, they are fire and explosion proof.

4. Lithium carbonate. Chemical formula - Li ₂ CO ₃ . Forms colorless crystals. Density 2.11 g / cm ³ (at 0 ° C), moderately soluble in cold water and poorly in hot. Melting point 732 ° C.

Lithium carbonate is used in pyrotechnics, the production of glass and plastics, electrical insulating porcelain, sitalls, as well as metallurgy, in agriculture. The glass industry is a major consumer of lithium carbonate. Lithium oxide in an amount of more than 0.15% in the glass composition leads to a decrease in the melting temperature (acts as a flux), a decrease in the viscosity of the molten glass, an increase in the quality and gloss of the finished product, and improves the color of the glass.

The composition claimed us ceramic materials, acts as a strong fluxing agent and a mineralizer that promotes reduction of the sintering temperature, a significant enhancement effect of clarifying a chalk-like limestone, increasing the strength of products, due to sintering and intensification of the formation of the mineral wollastonite - SaO⋅SiO ₂ having a white color and needle crystal structure. The effect of lithium carbonate is enhanced by the presence of the superplasticizer C-3, which contains sodium oxide, which is a strong flux.

Example. For experimental verification of the claimed compositions of the masses, standard samples of solid bricks with a size of 250 × 120 × 65 mm with a different ratio of the above components were made. Opal-cristobalite rock was used as a raw material - a flask of the Avilo-Fedorovskoye deposit of the Rostov region.

Samples were prepared as follows. The opal-cristobalite rock was preliminarily dried to an air-dry state, then crushed on a jaw crusher and disintegrator (passed once or twice) to a maximum particle size of less than 0.5 mm, after which it was sieved on sieves with a given mesh size and mixed in prescribed proportions with finely dispersed chalk-like limestone. Then from the dosed C-3 and lithium carbonate in the dissolved state were added to the flask, pre-mixed with chalk-like limestone at the required mass ratio, and water was added to the required molding moisture content, which is higher than the normal molding moisture for soft molding technology. The prepared mass was aged in sealed containers for 6 hours and then fed to molding. After drying, the products were fired with holding at a maximum temperature of 1000-1050 ° C for 2 hours.

EFFECT: obtaining front clinker bricks of white color with reduced water absorption, increased strength and frost resistance, with good molding properties of ceramic masses for soft molding technology is achieved through the use of opal-cristobalite rocks - flasks and the optimal content of plasticizing additives, the content of finely dispersed calcium carbonate in the form of chalk-like limestone (works as a clarifying component and second-order flux at firing temperatures above 1000 ° C), as well as the addition of lithium carbonate, which helps to reduce the sintering temperature, significantly enhance the clarifying effect of chalk-like limestone, increase the strength of products due to sintering and intensification of the formation of wollastonite mineral - CaO⋅SiO ₂ . The use of the declared ceramic masses will make it possible to establish the production of light-colored facing clinker bricks, which are so in demand in the modern market of wall materials and supplied only from abroad.

Claims (6)

Ceramic mass, including opal-cristobalite rock - flask, with a grinding degree of less than 0.5 mm, superplasticizer C-3, characterized in that it additionally contains finely ground chalk-like limestone - less than 0.05 mm and lithium carbonate, with the following ratio of components, mass ... %: opal-cristobalite rock - flask - 60-70; chalk-like limestone - 5-15; lithium carbonate - 0.6-1.2; superplasticizer C-3 - 0.2-1.0; water is the rest.