RU2272798C2 - Ceramic mass - Google Patents

Abstract

FIELD: construction industry; production of wall products.

SUBSTANCE: the invention is pertaining to field of construction industry and may be used for manufacture of the wall products including facial products (bricks, rocks). The technical result of the invention is an increased hardness of the kilned ceramic products, creation of the architectural nice appearance by elimination of mottles and superimposing the very small sparkling points on the surfaces of the wall products. The ceramic mass contains loamy clay, clay with the heightened content of sulfate and sulfite impurities (more than 2 mass % in terms of ion S₃ ^-2) and a finely dispersive refractory industrial waste - a mica-containing quartz sand - the waste of the coal mining, fractions of 0-0.315 mm with the share of the powder-like fraction of 0.014 mm -35 - 50 mass % at the following shares of the components (in mass %): the loamy clay - 72-80, the indicated clay - 10-17, the indicated quartz sand - 10-11. At that the indicated quartz sand contains: 95-98 mass % of quartz and 0.5-3 mass % of mica.

EFFECT: the invention ensures an increased hardness of the kilned ceramic products, creation of the architectural nice appearance by elimination of mottles and superimposing the very small sparkling points on the surfaces of the wall products.

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Description

The invention relates to the field of construction and can find application for the manufacture of wall products, including facial (bricks, stones).

The known composition of the ceramic mass, including clay raw materials containing sulfate and sulfite impurities of the type: Na ₂ SO ₄ , CaSO ₄ and others, for example FeS-pyrite), and containing, wt.%:

- Activated silica in the form of colloidal highly dispersed material - 10-20; - Clay raw materials containing sulphate and sulphite impurities - the rest.

(see Moroz I.I. Technology of building ceramics: Textbook for universities - 3rd ed. revised and supplemented. - Kiev: Vishcha school. Head publishing house, 1980 - 384 pp. Specifically, p. 144 below and p. 144 above).

Along with the advantages of the composition, efflorescences are excluded due to the chemical binding of salts to insoluble silicates, for example:

CaSO ₄ + SiO ₂ = CaSiO ₃ + SO ₃ ↑

MgSO ₄ + SiO ₂ = MgSiO ₃ + SiO ₃ ↑ there are also disadvantages:

1. Insufficient architectural expressiveness of ceramic products - a gray tint on the red tone of the brick, because colloidal active silica, such as diatomite, tripoli has a gray or dark gray hue.

2. Colloidal silica dramatically reduces crack resistance during drying, because the water-conducting structure decreases during the evaporation of moisture during the drying process.

3. Activated silica is among the scarce materials.

The closest composition of the ceramic mass in terms of technical nature and quality content is given in Autosvid. USSR No. 694474, IPC ³ C 04 V, publ. 10.30.79, Bull. No. 40 and containing components in the following ratio, wt.%:

- Fine refractory waste products (fly ash) - 60-69. - heavy loam - 25-30. - Clay containing an increased amount of sulfate and sulfite impurities (more than 2% in terms of SO ₃ ^-2 ion) - 6-10.

According to OST 21-78-88, such clay is substandard, but despite this, many plants are forced to introduce such clays (in addition to loams) into the molding composition, as they have 1.5-2 times higher strength in comparison with loams, on the basis of which wall ceramics are made.

Along with the advantages of the method (fly ash is utilized, the increased strength of raw bricks), there are also disadvantages that limit the use of ceramic products as face bricks, specifically:

1. Low architectural expressiveness, i.e. defects: flies, fading (due to sulfate salts and pyrite) and a gray tint, because fly ash in accordance with GOST 6133-84 "Concrete wall stones" refers to gray pigment.

2. Insufficient compressive strength of burnt bricks 129-270 kgf / cm ² , which limits the production of bricks with a voidness of 40% and higher with a grade of at least M100, M125 in strength.

The objective of the invention is to increase the strength of fired ceramics and architectural expressiveness by eliminating fading and providing micro-shiny points on the surface.

The problem is achieved in that the ceramic mass, including heavy loam, clay with a high content of sulfate and sulfite impurities - more than 2 wt.% In terms of SO ₃ ^-2 ion and fine refractory waste from the production, contains micaceous quartz as a fine refractory waste from the production. sand - coal waste, fractions of less than 0-0.315 mm, with a dust content of 0-0.14 mm, 35-50 wt.% in the following ratio of all components, wt.%:

          heavy loam 72-80           indicated clay 10-17           specified quartz sand 10-11,

moreover, the specified quartz sand contains 95-98 wt.% quartz and 0.5-3 wt.% mica.

Characterization of the components involved in the implementation of the task

1. Clay raw materials:

1.1. Kukuiskaya clay (Tula region) has a dark gray color, and after firing cream. Medium plastic, semi-acidic, insensitive to drying. Fusible - fire resistance 1250-1270 ° С. At a firing temperature of 950-980 ° C, it acquires high strength of 42-46 MPa. The latter serves as the main reason for using such substandard clay as an additive to loams with a strength of 2 times lower. By the amount of sulfur-containing impurities does not meet the requirements of OST 21-78-88.

1.2. Loam Novomoskovsky (Tula region). The color is yellow, and when fired, it has a light red color and the strength of the samples based on them is 17-23 MPa (firing temperature - 1000-1050 ° C). The raw materials are acidic, low melting point (temperature of refractoriness - 1250 ° С). It is moderately ductile (Ch.P = 12.6-12.7), highly sensitive to drying (low crack resistance). It is non-sintering up to 1250 ° С.

Table 1 shows the chemical composition of the clay raw materials. For comparison, similar indicators of clay raw materials, adopted in a known composition (prototype).

Table 1
The chemical composition of the clay raw materials of the proposed and known compositions. No. p / p Chemical composition (oxides) Requirements OST 21-78-88 for chemical composition For the proposed composition For prototype Clay Kukuyskaya Loam Novomoskovsky Clay Ainabulak Burundian loam Content: - Al ₂ About ₃ , > 7 21.45 11.64 14.44 15,5 - Fe ₂ O ₃ + FeO, <14 5.3 4.00 4.83 4.86 - CaO + MgO, <20 3.39 4.4 4,54 11.34 - sulfate and sulfite-containing impurities in terms of ion SO ₃ ^-2 , <2 3.19 traces 2.49 0.19 - Na ₂ O + K ₂ O, - SiO ₂ , <7 2.26 3.14 2,36 4.88 - Losses at <85 52.7 72.28 59.02 57.06 calcining 7.36 4.35 12.32 6.17 Original Humidity 15-18 16-18 - 6-13

1.3. Mica-containing fine quartz sand. Color is white or light yellow. Bulk density (dry) 1510-1515 kg / m ³ . Fractional composition: 0-0.14 mm (quartz dust) - 35-50 wt%; 0.14-0.315 mm - 50-65 wt.%. Career humidity 5-7%. Refractory - melting point 1700-1710 ° С. The mineralogical composition includes: quartz (SiO ₂ ) - 95-98 wt.%; mica - 0.5-3 wt.%; hematite Fe ₂ O ₃ , carbonates, organics - the rest.

Examples of the implementation of the proposed composition of the ceramic mass.

Example 1. Loam Novomoskovsky and clay Kukuiskogo quarry previously dried, crushed and sieved through a sieve with a diameter of 2 mm

Fine mica-containing silica sand was sieved through a sieve with a diameter of 0.315 mm to delay foreign inclusions.

Dry powder components were dosed by weight in the ratio shown in table 2.

A homogeneous mixture of powders was moistened with water to 20% humidity and a plastic dough was prepared, which was passed through laboratory rollers with a gap of 2 mm and placed in a hermetically sealed cellophane bag (to maintain moisture), followed by aging for two days. Samples — cubes of 7.07 × 7.07 × 7.07 cm in size — were formed from the prepared dough, removed onto a perforated tray, and then dried and calcined, respectively, at a maximum temperature of 75 ± 2 ° C and 1000 ° C. After firing, product samples were tested for compressive strength and visual architectural expressiveness.

Property test data are shown in table 2 and 3.

table 2
The composition of the ceramic mass No. p / p The dry weight components, wt.% Numbers of experimental ceramics Prototype one 2 3 four 5 6 7 8 one Heavy loam 70.0 72 76 80 81.5 84 thirty 25 2 Clay containing sulfate impurities (more than 2 wt.% in terms of SO ₃ ^-2 ) 18.5 17 13.5 10 9.5 8 10 6 3 Finely divided refractory waste production: 3.1 - Ash TPP; - - - - - - 60 62 3.2 - Mica silica sand with 11.5 eleven 10.5 10 9 8 - - fraction 0-0.315 mm. Table 3
Properties of ceramic samples No. p / p Properties Units rev. Non experienced masses of ceramics. Composition, wt% Prototype one 2 3 four 5 6 7 8 one Tensile strength MPa 34.2 32,5 28.8 28.0 25.1 15.6 27,2 12.9 under compression 2 Architectural view: 2.1 The presence of fading - there is no no no no no there is there is (efflorescence) 2.2 Color - Apricot Light red with gray a touch 2.3 The presence of brilliant golden - there is No points.

Analysis of the results of the task

1. As can be seen from table 3, the ceramic masses of compositions No. 1 and No. 6 are beyond, because products from composition No. 1 have fading on the surface, therefore, the ratio of the mass of quartz sand is 11.5 wt. % to the mass of sulfate-containing clay 18.5 wt.% is not enough. The composition No. 6 provides a strength of 15.6 MPa, which is in the ultimate strength of the prototype, and also does not allow to obtain a high-hollow face brick (voidness 42%) of the brand with a strength of at least M100.

2. The strength of the samples of products from mixtures of composition No. 2, 3, 4, 5 exceeds the strength of the samples of the prototype by 5.3-12.2 MPa.

3. Products do not have fading, “flies” and acquire a pronounced light orange color - the color of ripe apricots, with shiny golden microdots on the surface. Which helps to increase the architectural expressiveness of facial ceramics.

The physico-chemical essence of achieving this goal is explained by the following:

Fine crystalline quartz sand contains 35-50 wt.% Pulverized silica (SiO ₂ ), which, when firing ceramics, is able to react with lime released during the decomposition of anhydrite (CaSO ₄ ), sodium sulfate (Na ₂ SO ₄ ) and pyrite (FeS), forming water-insoluble silicates of calcium, sodium, fayalite (FeSiO ₃ ).

For example:

CaSO ₄ = CaO + SO ₃ ↑

CaO + SiO ₂ = CaSiO ₃

FeS + SiO ₂ + 2O ₂ = FeSiO ₃ + SO ₃

In the composition of the ceramic mass of the prototype, lime (CaO), freed from the decomposition of sulfates, reacts with calcium carbonate (CO ₂ ) contained in the combustion products of the kiln firing zone, i.e. carbonized into white spots, and this process continues outside the furnace or reacts with SO ₂ gas contained in the combustion products, i.e. there is a reverse process of the formation of insoluble sulfates, especially if a slight pressure is maintained in the kiln firing zone. SO ₂ gases are formed from the decomposition of pyrite contained in clay, i.e. anhydrite forms on the surface.

Thus, in the proposed composition, pulverized silica reacts like colloidal.

The formation of silicates CaSiO ₃ , fayalite FeSiO ₃ contribute to an increase in the composition of ceramics: glass phase, and consequently, an increase in strength, and the possibility of formation of fading is eliminated. Note that colloidal silica is involved in the composition of the analogue. Microparticles of micas present in quartz sand have a dual role, specifically:

- At a temperature of 900-950 ° C, these particles swell, densifying the ceramic stalk and, due to fusion with ceramic minerals, increase strength.

- Expanded microparticles of mica acquire a golden color, forming on the surface of the ceramics golden shiny microdots with a size of less than 0.3 mm, which positively affects the architectural expressiveness of ceramics.

- Microdispersed - quartz sand, having white or light yellow color, also positively affects the architectural appearance. The economic advantages compared to the prototype are as follows:

1. Quartz sand, introduced into the composition of the mass, despite the microdispersion, does not have the property of dusting, and the more that it has a moisture content of 5-6%, and fly ash from cyclones used in the composition of the prototype ceramics requires powerful ventilation systems for dust removal of the premises of the workshop.

In addition, for the removal of fly ash from cyclones special installations are required and such ash is transported by pneumatic transport either in cement trucks or paper bags, and quartz sand (in bulk), and by any transport (dump trucks or in platforms). Hence, the use of quartz sand in comparison with ash is 2 times cheaper.

2. For the first time, the microdispersed sands of the Moscow coal basin are proposed to be disposed of as part of facial ceramics. Earlier (80s) they could be used only for the production of glass containers. There are no such plants in the Tula region. Therefore, the present invention is directed to the disposal of sand, which thousands of tons have accumulated in open brown coal opencasts.

3. On the basis of the proposed composition of ceramics, it is possible to produce face brick, which is sold at a price of 1.3-1.5 times more expensive in comparison with the prototype brick.

Thus, the profit from the recommended composition of ceramics is 20-25% higher in comparison with the known composition of the prototype.

Claims (1)

Ceramic mass, including heavy loam, clay with a high content of sulfate and sulfite impurities of more than 2 wt.% In terms of SO ₃ ^-2 ion and fine refractory production waste, characterized in that micaceous quartz sand is used as a fine refractory production waste coal fraction 0-0.315 mm with a dust content of 0-0.14 mm 35-50 wt.%, with the following ratio of components, wt.%:  Heavy loam 72-80  Indicated clay 10-17  Specified Quartz Sand 10-11 moreover, the specified quartz sand contains 95-98 wt.% quartz and 0.5-3 wt.% mica.