RU2099307C1 - Ceramic mass for facing articles - Google Patents

Abstract

FIELD: production of facing articles. SUBSTANCE: ceramic mass comprises, mas. %: high-melting clay, 20-90; low-melting clay, 1.2-1.62; crushed broken articles, 0.3-10.5; foamed vermiculite sand having particles not more than 2.5 mm in size, 3.0-4.4; dry sulfite-yeast mash, 0.3-0.5. EFFECT: improved quality of desired product. 6 tbl

Description

 The invention relates to compositions of ceramic masses mainly for facing products and may find application in the industry of building materials and products for the production of facade tiles and stove tiles.

A known raw material mixture for the manufacture of lightweight refractories, including refractory or refractory clay, refractory filler, expanded vermiculite according to GOST 12865-67 and, to increase the strength of the formed products sulfite yeast mash (SDB) according to TU 81-04-546-79 or OST 81 -79-74 [1, 2]
Based on the known mixture, heat-insulating lightweight refractories with an average density of 351-1050 kg / cubic meter are obtained. with a compressive strength of 0.5-2.3 MPa, thermal resistance of at least 40 heat exchangers. Such high thermophysical properties of products are achieved due to the absence of flux in the mixture and the presence of the refractory component of expanded vermiculite with a particle size of 0 to 10 mm. The amount of the latter in the mixture is not less than 30 wt.

Along with these advantages, there are significant disadvantages that limit the use of the known mixture for the manufacture of facing products, for example, stove tiles, as well as unglazed facade ceramics, in particular:
1) low decorative appearance due to loose porous surface and faded color;
2) low strength (less than 2.5 MPa);
3) low frost resistance (less than 5 cycles).

The second ceramic mass is also known, including refractory clay, low-melting clay; skull (battle of products of the same mass), cullet ground and refractory sand (quartz) in the following ratio of all components, wt. [3]
low-melting clay 55-65;
refractory clay 11-14;
cullet 6-10;
quartz sand 18-21;
Products from the known mass have a compressive strength of 15 MPa, water absorption of 14-16%
Along with the indicated advantages, the mass has disadvantages that limit its use for the manufacture of facade tiles, stove tiles specifically:
high water absorption of 14-16%
low strength 15 MPa and frost resistance -15 cycles;
low decorative look of a ceramic crock;
low heat resistance.

 Closest to the claimed is a ceramic mass [4] comprising the following components, wt.

fusible montmorillonite-containing clay 30-43;
refractory montmorillonite-containing clay 40-47;
cullet 5-8;
skull 5-11;
silica sand 5-8.

From the composition of the known mass, majolica cladding products are obtained at a maximum temperature of poured firing of 980 ^o C with a compressive strength of 16.2-20 MPa and with a water absorption of 4.8-4.7%
Along with these advantages, the known method of mass has a low decorative appearance of a ceramic crock, which limits its use for the manufacture of unglazed facade tiles, stove tiles; low strength (16.2-20 MPa); frost resistance not less than 35 cycles.

 The present invention solves the problem of increasing frost resistance and decorative appearance of a ceramic crock.

 To achieve this goal, a low-density brown coal ash and sulphite-yeast mash are additionally introduced into the well-known composition of the ceramic mass for facing products, including refractory and low-melting clay, ground skull and cullet, refractory quartz sand, and expanded vermiculite sand is used as the refractory sand in the following ratio components, wt.

refractory clay 20-90.0;
low-melting clay (loam) 1.2-62.0;
skull (ground battle of the product) 0.5-2;
cullet 2.5-3.6;
low calcium lignite ash 0.3-10.5;
expanded vermiculite sand with a size of not more than 2.5 mm 3.0-4.4;
sulfite-yeast mash (dry) in excess of 100% dry mix 0.3-0.5.

Characterization of mass components:
1. Clay raw materials.

 1.1. Refractory clay of Novorayskoye deposit, Druzhkovsky ore management.

Refractoriness 1540-1570 ^o C. Plasticity not less than 13. Color after firing white.

 The chemical composition of this clay is given in table. one.

 Before use, the clay is dried, crushed and sieved through a sieve with a hole diameter of not more than 1 mm.

 1.2. Refractory clay of the Lukoshkinsky deposit TU 21-RSFSR-44341-84.

Refractoriness 1430-1570 ^o C. Plasticity 17. The color after firing is light red.

The chemical composition of clay Lukoshkinskoye deposits are given in table.2
1.3. Refractory clay of Gryzlovsky, Kimovsky coal opencasts (Tula region) (Table 3).

Clay refractoriness 1420-1520 ^o C White after firing white Clay ductility 18-20.

 1.4. Fusible clay (loam) Tula region. (table 4).

Plasticity 9-12. Refractoriness 1200-1230 ^o C. After firing, they are red.

 Clays are hydromica composition with admixtures of kaolinite and montmorillonite. The crushed clay is sieved through a sieve with a hole diameter of not more than 1 mm.

 1.5. Expanded vermiculite sand. GOST 12865-67 "Expanded vermiculite." The feedstock is the vermiculite concentrate of the Kovdor deposit.

The chemical composition corresponds to the chemical formula of phlogopite (K) ₂ Al ₂ O ₃ SiO ₆ (Mg) ₆ O ₂₀ (OH) ₄ . Expanded vermiculite after firing has a golden color, the size of scaly particles is from 1 to 10 mm. Bulk density from 80-200 kg / cubic m. Before use, expanded vermiculite with a bulk density of 150 kg / cu. m sifted through a sieve with a hole diameter of 2.5 mm. The residue on the sieve is reduced and again sifted again on a sieve with a hole diameter of 2.5 mm. Vermiculite sand sifted through the specified sieve has a bulk density of 200 kg / m3. Thus, in the claimed composition of the mass used expanded sand with a maximum size of individual particles of 2.5 mm and a bulk density of 200 kg / cubic meter. moreover, particles with a size of 1-2.5 mm should be no more than 25%
1.6. Sulphite-yeast mash (SDB) was adopted as a plasticizer in order to increase the strength of pressed semi-finished products and increase crack resistance during drying and pressing of TU 81-04-546-79 or OST 81-79-74.

 SDB is introduced with mixing water in the form of an aqueous solution of 5% concentration.

 1.7. Glass break. Adopted transparent battle glass containers. Allowed battle with blue and green shades. The specific surface of ground cullet is not less than 2000 sq. Cm / g.

 1.8. Skull. As the skull used ground marriage of ceramic shards from the claimed composition of the mass. Ground marriage was sieved through a sieve with a mesh diameter of 0.5 mm.

 1.9. Ash brown-coal near Moscow basin.

 The bulk density of the ash is 900-950 kg / m3. Ash should meet the requirements of GOST 4810-78 "Requirements for fly ash fly ash near Moscow coal basin" (table 5).

 In a production environment, the preparation of the proposed composition of the ceramic mass in the form of a press powder for facade tiles or tiles is prepared by any traditional domestic method. For example, finely ground dry clay raw materials are dosed, sifted through a sieve with a mesh diameter of not more than 1 mm, as well as all these components in a ratio by dry weight indicated in Table. 6. The mixture of dry components is moistened with a 5% SDB solution to a moisture content of 6-10% is mixed until smooth. The mixture is formed by semi-dry pressing under pressure.

Products are dried to a sufficient humidity of 0.5-2% and then fired at a maximum temperature of 980-1050 ^o C. Increased decorative appearance tiles, as well as stove tiles can be used in unglazed form or using transparent glaze.

 Example N 1. Weighed previously dried crushed and sieved through a sieve with a hole size of 1 mm Druzhkovsky clay of the Novoral deposit in the amount of 9.03 kg (90.3 wt.) By weight of the dry mixture. To this clay was added 120 g of hot-melt clay (1.2%), 50 g (0.5%) of ground scrap tiles sifted through a sieve with a mesh diameter of 0.5 mm, 360 g (3.6 wt.) Ground glass with a specific surface of 2000 sq. cm / g and 440 g (4.6 wt.) of expanded vermiculite sand sifted through a sieve with a mesh diameter of 2.5 mm and a bulk density of 200 kg / cubic meter and ash 30 g ( 0.3%).

 All components were mixed in a laboratory screw mixer and at the same time, during mixing for 2 min, a 5% solution of SDB in the amount of 1 kg was fed, in which 50 g of dry SDB was previously dissolved (0.5% in excess of 100% dry mixture). Semi-dry mass was formed by pressing on a hydraulic press under a specific pressure of 18 MPa.

The formed samples in the form of tiles with a size of 192x142x9 mm and cylinders with a diameter and height of 50 mm (the latter were intended to determine the compressive strength) were dried to a residual moisture content of 2% and then fired for 3 hours at a maximum temperature of 1050 ^o C with exposure at maximum temperature 20 min. After cooling, the tile samples were tested for strength, frost resistance, water absorption, heat resistance and appearance (visually). The test results are given in table. 6 (see mixture 2).

In a similar way, all other mixtures were prepared, but with the use of other refractory clays, the proposed ceramic mass and all, accordingly, based on it samples of the facing tiles, including transcendent compositions of masses 1 and 7, as well as the known composition of mass 8 (prototype). The results of the properties are given in table. 6. Samples from the mass with the prevailing amount of low-melting clay were fired at a temperature of 980 ^o C, and accordingly with the prevailing amount of refractory clay at a temperature of 1050 ^o C.

 Data analysis table. 6 test results of the properties of samples of facing ceramics made from the composition of the proposed mass shows the following.

 1. All mixtures 2 6 meet the requirements of GOST 13996-84 "Facade ceramic tiles and carpets from them."

 2. Due to the increased heat resistance, the proposed mass can also be used for stove tiles.

 3. With an increase in the dose of vermiculite sand (more than 4.4) and an increase in the maximum size of individual particles more than 2.5 mm, the strength drops sharply and water absorption increases (more than 12%), which does not meet the requirements of GOST 13996-84, therefore, composition No. 1 is beyond.

 4. With a decrease in the dose of vermiculite sand (less than 3%) and the maximum particle size (less than 2.5 mm), a decrease in strength is also observed and an increased decorative appearance of the ceramic crock is not achieved. The decrease in refractory clay (less than 25%) also negatively affects this.

 With an increase in the size of individual particles of vermiculite sand more than 2.5 mm, there is no sufficient depth along their periphery of topochemical sintering when interacting with dusty glass particles and therefore their cores partially fall out, which reduces strength, i.e. adhesion of particles with a ceramic crock is not high enough.

 An excessively large amount (above 4.4%) of vermiculite sand also leads to an increase in water absorption.

 With a decrease in the dose of vermiculite sand (less than 3%), the goal of increasing the decorative look is not achieved, and especially with a corresponding decrease in the maximum size of individual particles less than 2.5 mm. Vermiculite sand is melted along the periphery contours so intensely that the size of the golden particles becomes less than 1 mm and the golden shine of these particles in the shard of the ceramic mass is extinguished, i.e. on a plain color tone, no golden inclusions are observed and such a ceramic crock cannot be used for these purposes without a blank coating of glaze.

The inventive composition of the ceramic mass in comparison with the prototype has the following advantages:
1. Increases the compressive strength of 1.23-2.30 times.

 2. The decorative look sharply rises; golden phlogopite flakes of vermiculite are evenly located on the solid color tone of the products. Such a ceramic shard of products may not be covered with deaf colored glaze at all, or may be coated with cheaper raw transparent. In the latter case, this gives the products durability during service.

The physicochemical nature of the technical solution to achieve the goal is as follows:
Expanded vermiculite sand, due to its low bulk density (200 kg / cubic meter), occupies 20-25% of the raw material volume, and the total specific surface area of these particles exceeds the total surface of all other mass particles, and therefore the conditions for their interaction with glass particles are more effective.

 Small particles of vermiculite sand with a size of 0-0.6 mm are almost completely melted, increasing the amount of glass phase and, accordingly, the sintering interval widens, because finely dispersed vermiculite sand complements the action of the glass phase, and acts as an additional flux, which increases the strength. Larger particles melt and completely adhere to the ceramic shard, and their size decreases by 40-50%. Particles of this sand with a size of 2.5 mm are reduced in diameter to 1-1.5 mm and do not lose their golden sheen and, therefore, on a plain ceramic color shard, depending on the color of the burnt clays (pink, beige, white, red), these particles evenly expand in the form of luminous golden dots, which provides an increased decorative appearance to the facing products. Such products do not require coating with colored dull glaze. For durability, they can be coated with transparent glaze, including jade transparent.

 Thus, vermiculite expanded sand in the claimed composition of the mass together with glass performs two functions: it effectively reduces the temperature of the onset of sintering (the appearance of a liquid phase), i.e. acts as a flux on the one hand and as a decorative filler on the other. In the latter case, in the presence of particles with a maximum size of 2.5 mm.

 Unmelted particles of vermiculite sand in the composition of the calcined ceramic crock play the role of more active adsorbents of water when it is saturated with water and, accordingly, the role of elastic dampers when this water freezes in a ceramic crock, i.e. able to taper and expand under the influence of ice, without losing its continuity and strength. The damping behavior of vermiculite particles during alternate freezing and thawing of water in a ceramic crock increases frost resistance.

Claims (1)

 Ceramic mass for facing products, including refractory and low-melting clay, ground skull, cullet and refractory sand, characterized in that it additionally contains low-calcium brown coal ash and sulphite-yeast mash, and expanded vermiculite sand is used as refractory sand in the following ratio of components, wt. Refractory clay 20 90
Low-melting clay 1.2 62.0
Skull (ground battle of products) 0.5 2.0
Cullet 2.5 3.6
Low calcium lignite ash 0.3 10.5
Expanded vermiculite sand with a particle size of not more than 2.5 mm 3.0 - 4.4
Sulphite-yeast mash (dry) in excess of 100% dry mix 0.3 0.5

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