RU2361841C1 - Ceramic mass - Google Patents

Abstract

FIELD: construction.

SUBSTANCE: ceramic mass includes keramzite clay and low-strength loam with compression strength after annealing at temperature of 1000°C of at least 7.5 MPa, limestone or chalk with specific surface of 280-300 m²/kg, unground granulated blast-furnace slag with fraction of 0-5 mm and crushed sheet glass with specific surface of 280-300 m²/kg at the following ratio of components, wt %: keramzite clay - 22.0-24.0; loam - 43.5-47.0; chalk or limestone with specific surface of 280-300 m²/kg - 20-23; unground granulated blast-furnace slag with fraction of 0-5 mm - 8-11; crushed sheet glass with specific surface of 280-300 m²/kg - 0.5-1.0.

EFFECT: broadening of clayey low-melt raw materials resources due to utilisation of off-grade materials and increased crack resistance in drying, without reduction in strength and variation in product colour.

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Description

The invention relates to the production of building materials and can be used in the manufacture of facing and ordinary bricks, from light-burning to cream-colored, from fusible, red-baked clay raw materials.

The known composition of the ceramic mass shown in the patent of the Russian Federation No. 2024463, IPC ⁵ С04В 33/00, 33/02, published 12/15/94, and including components in the following ratio, wt.%:

- fusible clay - 44-60;

- finely ground limestone - 10-20;

- burnt clay fireclay - 12-20;

- chalk with a specific surface area of 7000-8000 cm ² / g - 5-10;

- sodium glass with a specific surface area of 7000-8000 cm ² / g - 5-10.

Along with the great advantages of the known composition (the architectural appearance is enhanced, due to the exclusion of efflorescence, properties that meet the requirements of GOST 7784-78 are achieved), there are also disadvantages:

1) the mechanical and heat-intensive process of preparing all additives due to firing of low-melting clay for chamotte and very fine grinding to 8000 cm ² / g of the specific surface of most additives;

2) low crack resistance during drying of raw brick despite the presence of a thinning additive - chamotte, which is also finely ground to 30% to a specific surface of 6000 cm ² / g.

The high specific surface of thinning additives and sodium-containing glass leads to a decrease in the water-conducting ability of raw brick during drying and, consequently, to low crack resistance.

The second ceramic mass of increased architectural expressiveness and strength is also known, which is given in RF patent No. 2300507, IPC ⁷ С04В 33/132, published on June 10, 2007, Bull. No. 16. The composition of the known mass, including components in the following ratio, volume%:

loam 64-68 burnable additive (scop) 6-9 iron-containing waste - fine sediment from cyclones from surface cleaning steel parts and structures shot blasting apparatus 7-13 expanded clay expanded clay 15-20

Introduced into the composition of the mass of osprey, containing 50% cellulose and 50% kaolin, acts as a burnable additive and simultaneously bleach, since kaolin has a white color.

Along with great advantages: strength is increased, overall shrinkage is reduced, efflorescence is eliminated, substandard clay raw materials, for example expanded clay clay with a high content of Fe ₂ O ₃ , are disposed of, and there are some disadvantages:

1) the formation of an effective (hollow) raw brick by a plastic molding method is difficult, since the osprey fibers adhere to the surface of the press core;

2) kaolin contained in the osprey has a lower degree of bleaching compared to traditional bleaching with finely ground carbonate-containing components of limestone or chalk.

The closest composition, both in terms of quality and technical solution, is given in the USSR Copyright Certificate No. 1606495, IPC ⁷ С04В 33/00, published on November 15, 1990, Bull. No. 42, containing components in the following ratio, wt.%:

- fusible clay - 29.5 - 94.0;

- limestone fr. <0.06 mm - 2.5-35;

- quartz sand - 2.5-35;

- sodium chloride - 0.5-1.

The known composition achieved an increase in strength to 15.2-28.1 MPa and a decrease in firing temperature to 850-950 ° C for 24 hours. Color of ceramics (brick, tile, light yellow, cream).

Along with the advantages, there are also disadvantages:

1) in the proposed composition, limestone plays the role of bleach, but not the role of flux and porizer, since the role of flux is lime (CaO), which is formed as a result of decomposition of limestone (CaCO ₃ ) at a temperature above 950 ° C, and calcium silicate CaSiO ₃ , which is part of the ceramic crock, is formed at a higher temperature (above 950 ° C), mainly 1000-1050 ° C. The latter is reported in many sources of technical literature on ceramic technology (Frost. Technology of building ceramics. - Kiev: Vishka school. 1980 - 384 p.). Thus, the entire useful potential of limestone in the formation of the structure of the ceramic crock due to the low firing temperature has not been used. Strength increase is achieved by flux - sodium chloride;

2) sodium chloride adversely affects the durability of the lining of kilns and the sanitary conditions in the firing workshop, since during the decomposition of NaCl, during the firing process, Cl ₂ gas is released;

3) low crack resistance during drying, since the detergent - quartz sand is finely crushed;

4) the known composition of ceramics did not use the direction of expanding the resources of natural clay raw materials due to the disposal of substandard, for ceramic bricks, shards, for example expanded clay with a high content of Fe ₂ O ₃ and other substandard types of clay-containing rocks.

The objective of the invention is to expand the resources of clay fusible raw materials by disposing of substandard and increase crack resistance during drying, without reducing the strength and color change of products (light yellow, cream) in relation to the firing temperature of 1000 ° C.

To accomplish the task, a ceramic mass comprising fusible clay raw materials, limestone or chalk, characterized in that clayd clay and loam with compressive strength after firing at a temperature of 1000 ° C less than 7.5 MPa are taken as fusible clay raw materials, additionally introduced non-ground granulated blast furnace slag with a fraction of 0-5 mm and sheet glass battle with the same specific bleach surface of 280-300 m ² / kg in the following ratio of components, wt.%:

expanded clay 22-24 loam 43.5-47 specific surface chalk or limestone 280-300 m ² / kg 20-23 granulated blast furnace slag fr. 0-5 mm 8-11 specific glass surface fight 280-300 m ² / kg 0.5-1.0

Tests were conducted where components with the following characteristic properties were used.

1. Fusible substandard clay raw materials for bricks.

1.1. Expanded clay. The clay of the Porechensky deposit of the Tula region with a high content of iron oxide was accepted.

The chemical composition of clay contains (%) by weight: SiO ₂ 48.2-48.6; Al ₂ O ₃ 23-23.45; TiO ₂ 0.64-0.76; FeO 0.98-1.01; Fe ₂ O ₃ 7.73-9.51; CaO 1.06-1.08; MgO 1.95-2.15; Na ₂ O 0.38-0.84; K ₂ O 3-3.22; P ₂ O ₂ 0.09-0.11; S _total 0.04-0.05; MnO 0-0.04; p.p.p. 10.49-11.65.

Hydromica clay with kaolinite impurities, highly dispersed, expansion coefficient at t = 980-1000 ° С - K _sun. = 1.5 at 1200 ° C 6-7, highly plastic, fusible.

1.2. Loam. Refers to acidic non-plastic clay raw materials (plasticity number 3-4), the color after firing is red. After firing at t = 1000 ° C, it has a compressive strength of at least 7.5 MPa (6-7.35 MPa). They occur after the overburden (sandy loam) and acidic clay loams. It is practically impossible to make brick of a brand of at least M75 from loam with a strength of less than 7.5 MPa, which contradicts GOST 530-95 “Brick and ceramic stones”. Therefore, this loam is substandard.

2. Chalk or limestone. Chalk and limestone contain 98-99% CaCO ₃ , the rest is impurities: silica, clay and organic matter. In the experiments, chalk of the Belgorod deposit and limestone seeding of the Barsukovsky deposit of the Tula region were adopted. In the experiments, chalk and limestone were crushed together with the battle of sheet window glass, specular, showcase to a specific surface of 280-300 m ² / kg.

3. Granular fine-grained main blast furnace slag with a fraction from dust to 5 mm. The basicity module is 1.05-1.08. In the experiments, the slag of OAO NPO Tulachermet from smelting ordinary cast iron was adopted.

4. Fight sheet glass. A fusible battle of window, mirror, showcase glasses with a melting temperature of 950-1000 ° C, that is, an alkali-containing battle (Na ₂ O or K ₂ O), was adopted. It is not recommended the battle of bottle, electric glass glasses, that is, more refractory. In the experiments, a ground battle of sheet glass with a specific surface area of 280-300 m ² / kg was adopted.

Table 1 shows the compositions of the experimental masses.

Note: * - compositions No. 1 and No. 6 are beyond;

** - the second digit (2; 3; 4; 5) - corresponds to the number of prototypes with an equal quantitative content of components: clay raw materials, bleach and flux.

As can be seen from table 1, in the experimental experiments the compositions of the ceramic masses of the prototype were accepted, which are within the quantitative limits of this prototype and the claimed composition by the quantitative content: clay raw materials, bleach, filler and flux, but with different quantitative composition of almost all components, including particle size distribution of cleaners and bleach.

Task implementation

Experience No. 1. (For composition No. 2, in table 1). Dosed by weight of 690 g (23%) of chalk and 15 g (0.5%) of window glass. The mixture was finely ground in an electroconditioner to a specific surface of 300 m ² / kg.

The prepared claydite clay powders and loam with a fraction of less than 2 mm, respectively, were dosed by weight in the amount of 660 g (22%) and 1 kg 305 g (43.5%).

Dosed in an amount of 330 g (11%) granulated blast furnace slag. All material powders were mixed until homogeneous. The homogeneous mixture was moistened to a molding moisture of 22%. Samples 5 × 5 × 5 cm in size were molded from the resulting plastic mass. Some of the samples were dried: 6 pieces in a natural way, the remaining samples (6 pieces) in tunnel dryers of a local brick factory at a maximum temperature of t = 70-75 ° C for 48 hours. After natural drying, the samples were calcined in a muffle furnace at a temperature of 1000 ° C for 2 hours. Other experimental batches of samples were made by a similar technique, including prototype samples, but with the corresponding clay raw materials (fusible clay) and with coarser finely dispersed limestone and quartz ground sand with a fraction of less than 0.06 mm.

On the test samples dried in tunnel dryers, the relative value of crack resistance of each test batch was determined by the formula (1):

,

,

where T _r.st - relative crack resistance,%;

S ₁ - the total surface of six prototypes measuring 5x5x5 cm, i.e.

S ₂ - the total surface of all planes - faces with cracks (shrinkage was not taken into account), after drying, cm ² ;

Samples made from composition No. 2 (table. No. 1) after drying had a common surface with cracks equal to: S ₂ = (5 × 5) × 3 _face = 75 cm ² .

Therefore, for these samples, crack resistance was:

The fracture toughness was also determined by a similar method for all samples from other mass compositions, including prototype samples. All batches of samples that were naturally dried had no cracks and, after firing, were tested for compressive strength. Values of strength, color and crack resistance are shown in table 2.

Analysis of the test results of the properties of samples of wall ceramics made from the compositions of the claimed mass and prototype.

1. As can be seen from table 1, the adopted clay natural raw materials (expanded clay expanded clay and loam) in terms of strength, and expanded clay and in the degree of crack resistance, are individually deficient raw materials for the production of wall ceramics.

2. The compressive strength of ceramic samples from the masses of the claimed composition, relative to the prototype samples, did not decrease, and the architectural appearance and color did not decrease.

3. The crack resistance of wall ceramics during artificial drying increased by 11.2-13.9%, which has a positive effect on reducing the cost of finished products.

The physicochemical nature of the achievement of the task is as follows. A) In complex clay raw materials, the role of the main ligament is played not by loam, but expanded clay. Sandy loam in expanded clay clay acts as a cleanser, which reduces not only the plasticity of such clay and the corresponding shrinkage, but also reduces the degree of expansion during firing, since the amount of free quartz increases in complex raw materials and, accordingly, in expanded clay clay. With so much free quartz, expanded clay does not swell (see Rogovoy MI, Technology of artificial aggregates and ceramics: Textbook for high schools. - M .: Stroyizdat, 1974, p. 315). Thus, loam prevents expanded clay from swelling, and semi-acid clay expanded clay enriches loam with Al ₂ O ₃ , Fe ₂ O ₃ content, which ultimately has a positive effect on the strength of wall ceramics made from complex raw materials.

B) The increase in crack resistance in relation to the ceramic of the prototype is explained by the following factors:

- an increase in the water supplying ability of the raw material during drying due to the use of fine-grained gravel slag instead of the finely quartz sand of the prototype;

- the dust-like fraction of granulated slag activated by alkali-containing fine-ground glass is a glass-slag binder, and during drying (1 day) at high relative humidity this binder mixture begins to hydrate, that is, chemically attach part of the molding moisture from the raw brick mass, reducing shrinkage stresses , and in the first, more dangerous period of drying. Hydrated water is removed during firing at temperatures above 400 ° C; therefore, it is recommended not to separate the dust fraction from the granulated slag.

Feasibility study of the claimed invention.

1. Disposed granular blast furnace slag, and not ground, and in the prototype, the cleaner is crushed.

2. The battle of sheet glass is utilized, which accumulates in tens of tons when sorting city waste and in warehouses where glass is stored. The prototype uses an expensive salt of NaCl (800-1000 rubles per 1 ton).

3. Substandard clay raw materials are disposed of, which remain in quarries or accumulate in dumps in thousands of tons.

4. Increases the yield of finished products by 10-13% due to increased crack resistance during drying.

These factors PP.1-4 can reduce the cost of finished products by 15-20%.

Table 1 The composition of the mass of wall ceramics Mass components (dry) Non experimental masses and compositions, wt.% experienced prototype one 2 3 four 5 6 * 7-2 ** 7-3 ** 7-4 ** 7-5 ** 1. Fusible red-burning clay raw materials 1.1. Expanded clay semi-acid clay 21.6 22.0 22.7 23,4 24.0 21 - - - - 1.2. Loam low strength 42.0 43.5 44.75 46.0 47 51 - - - - 1.3. Fusible clay - - - - - - 65.5 67.45 69,4 71 2. Bleach 2.1. Ground limestone with fr. <0.06 mm - - - - - - 23 22 21 twenty 2.2. Ground chalk with a specific surface of 300 m ² / kg 24 23 - 21 - 19 - - - - 2.3. Ground limestone with a specific surface area of 280 m ² / kg - - 22 - twenty - - - - - 3. The scrubber 3.1. Quartz sand - - - - - - eleven 10 9 8 3.2. Granulated blast furnace slag fr. 0-5 mm 12 eleven 10 9 8.0 7.9 - - - - 4. Fluff 4.1. Sodium chloride - - - - - - 0.5 0.55 0.6 1,0 4.2. Fight of sheet glass (mirror, window, etc.) with a specific surface area of 280-300 m ² / kg 0.4 0.5 0.55 0.6 1,0 1,1 - - - -

Claims (1)

Ceramic mass, including low-melting clay raw materials, limestone or chalk, characterized in that clayd clay and loam with compressive strength after firing at a temperature of 1000 ° C less than 7.5 MPa are taken as low-melting clay raw materials, additionally ground granulated blast furnace slag with fraction of 0-5 mm and the battle of sheet glass with the same specific surface area of the bleach 280-300 m ² / kg in the following ratio of components, wt.%:
expanded clay 22.0-24.0 loam 43.5-47.0 bleach - chalk or limestone with specific gravity surface of 280-300 m ² / kg 20-23 non-ground granulated blast furnace slag fraction 0-5 mm 8-11 sheet glass battle with specific surface of 280-300 m ² / kg 0.5-1.0