RU2255919C1 - Raw mixture and method for making wall ceramic article - Google Patents

Abstract

FIELD: ceramics, building industry and materials.

SUBSTANCE: invention is designated for manufacturing wall ceramic articles. The raw mixture comprises the following components in the ratio, wt.-%: microsilica in manufacturing crystalline silicon, 33.9-54.5; ash fly after combustion of brown coals, 44.5-63.5, and electrofilter dust in basic manufacturing aluminum, 1.0-2.6. Electrofilter dust represents brown color waste and comprises calcium, magnesium and aluminum fluorides, cryolite and organic substances. Method involves preparing the charge, molding, drying, roasting at 800°C and moistening ready articles by keeping in water for 24 h. Invention provides enhancing resistance to cold, reducing average density and roasting temperature of material.

EFFECT: improved method for preparing, improved properties.

2 cl, 2 tbl, 2 ex

Description

The present invention relates to the production of wall ceramic products and can be used for the manufacture of building materials.

Closest to the proposed raw material mixture in terms of technical nature and the achieved effect is a raw material mixture, including, wt.%: Clay 23 ... 41, silica fume 77 ... 59 [1].

The disadvantages of this mixture are relatively low values of strength and frost resistance and increased firing temperature.

The technical result is the involvement of technogenic raw materials in the production of building materials, increasing strength, frost resistance and coefficient of structural quality, lowering the firing temperature.

The technical result is achieved by the fact that the raw material mixture for the manufacture of wall ceramic products containing silica fume and aluminosilicate component includes, as an aluminosilicate component, fly ash with CaO content of 7-12 wt. %, and also additionally includes an organomineral additive in the form of dust from electrostatic precipitators of the main aluminum production in the following ratio of components, wt.%:

Silica fume 33.9 ... 5 4.5;

Fly ash 44.5 ... 63.5;

Dust of electrostatic precipitators 1.0 ... 2.6.

Silica fume production of crystalline silicon is a dispersed waste with a specific surface area of 25 ... 34 m ² / g and an amorphous silicon oxide content of up to 93 wt.%. The chemical composition of silica fume (in wt.%): SiO ₂ 86-93; Fe ₂ O ₃ 0.14-1.28; MgO 1.03-1.20; Na ₂ O 0.39-0.46; K ₂ O 0.28-0.42; Al ₂ O ₃ 0.7-1.05; CaO 0.26-0.44; RFP 3.7-5.29.

The aluminosilicate component - fly ash with a relatively low content of calcium oxide is formed from the burning of brown coal of the Azean deposit and contains, wt.%: SiO ₂ 43.0-49.6; Al ₂ O ₃ 23.9-24.2; Fe ₂ O ₃ 6.9-20.6; CaO 6.9-11.8; MgO 1.3-1.6; K ₂ O 0.7-0.8; Na ₂ O 0.1-0.2; SO ₃ 1.2-2.1.

The dust of electrostatic precipitators is a brown dispersed waste with a particle size of 5-8 microns. The choice of dust from electrostatic precipitators as an additive to intensify the processes of sintering of technogenic raw materials and improve the properties of ceramic products is due to the presence of a number of valuable (low viscosity in the temperature range of firing ceramic products) mineralizing components: fluorides of calcium, magnesium, aluminum, cryolite, etc. Dust of electrostatic precipitators The fraternal aluminum smelter contains, wt. %: F 16.0; Al 12.0; Na 9.9; Ca 0.46; Mg 0.1; Fe ₂ O ₃ 2.87; SiO ₂ 0.65; RFP 38%.

The combination of silica fume and fly ash with a relatively low content of calcium oxide causes the formation of high-strength, long-lasting crystalline phases - feldspars, mullite, cristobolite, reinforcing ceramic shards.

Closest to the proposed method according to the technical essence and the achieved effect is the method [1], including the preparation of the mixture, molding, drying, firing the product at 900-950 ° C and moistening after firing. The disadvantages of this method are the relatively low values of strength and frost resistance and increased firing temperature.

The technical result is achieved in that the method of manufacturing wall ceramic products includes the preparation of the mixture, molding, drying and firing at 800 ° C and additional wetting of the product after firing.

Example 1. To prepare the raw material mixture, silica fume is used to produce crystalline silicon from the Bratsk aluminum plant, low-calcium fly ash formed from the burning of brown coal from the Azeysk deposit, and dust from electrostatic precipitators of the Bratsk aluminum plant.

Fly ash is mixed with silica fume and dust of electrostatic precipitators, after which water is added in the amount necessary to obtain a mixture with a moisture content of 16%. The content of ingredients (in wt.%) In the proposed compositions are given in table 1 (compounds No. 1, 2, 3, see the end of the description). From the resulting mixture by semi-dry pressing at a pressure of 25 MPa, cylinder samples with a diameter of 40 mm are formed, which are dried at 60 ° C to constant weight and fired at 800 ° C.

For fired products, the average density, water absorption, compressive strength are determined and the coefficient of structural quality is calculated.

The specific values of the estimated parameters according to claim 1 are given in table 1.

Example 2. Products made according to claim 1, dried at 60 ° C to constant weight and fired at 800 ° C. After firing, the samples are moistened by keeping in water for 24 hours.

For calcined products determine the average density, water absorption, frost resistance, compressive strength of dry and aged for 24 hours in water products.

Moistening of the calcined material leads to hydration of the low basic minerals formed during the firing process along with the traditional ceramic component, which in turn provides an additional increase in the strength of the products during wetting.

The specific values of the estimated parameters according to claim 2 are given in table.2 (see the end of the description).

The proposed method provides an increase in strength by 1.5 ... 2 times.

Sources of information

1. RF patent No. 2130912, MKI ⁶ C 04 V 35/14, 35/16. Raw mix and method of manufacturing wall ceramic products. M.A.Sadovich, N.A. Lokhova, O.E. Volkova, E.I. Yakovlev // Bull. Revelation Fig. - 1999. - No. 15.

Table 1 Composition Components and Product Properties The content of ingredients (wt.%) In the composition Famous Composition 1 2 3 Silica fume 33.9 44,2 54.5 - Fly ash 63.5 54.0 44.5 - Dust of electrostatic precipitators 2.6 1.8 1,0 - Water absorption, wt.% 29.7 31,4 33,2 28.7 ... 29.3 The average density, kg / m ³ 1280 1250 1220 1249 ... 1263 Compressive strength, MPa 29.6 32 34.3 13.0 ... 14.6 The coefficient of structural quality × 10 ^-2 , MPa / (kg / m ³ ) 2,3 2,5 2,8 1,0 ... 1,2 Frost resistance cycles 35 35 35 fifteen

table 2 Composition Components and Product Properties The content of ingredients (wt.%) In the composition Famous Composition 1 2 3 Silica fume 33.9 44,2 54.5 - Fly ash 63.5 54.0 44.5 - Dust of electrostatic precipitators 2.6 1.8 1,0 - Water absorption, wt.% 29.7 31,4 33,2 28.7 ... 29.3 The average density, kg / m ³ 1280 1250 1220 1249 ... 1263 Compressive strength, MPa 29.6 32 34.3 13.0 ... 14.6 The coefficient of structural quality × 10 ^-2 , MPa / (kg / m ³ ) 2,3 2,5 2,8 1,0 ... 1,2 Frost resistance cycles 35 35 35 fifteen Compressive strength after 24 hours in water, MPa 37.9 38.5 39.1 16.4 ... 22.9 Note: 1 - for the proposed option, values are given for samples calcined at 800 ° C;
2 - for a known composition, values are given for samples annealed at 900 ... 950 ° C.

Claims (2)

1. The raw material mixture for the manufacture of wall ceramic products containing silica fume and an aluminosilicate component, characterized in that it includes fly ash with an CaO content of 7-12 wt.% As an aluminosilicate component, and further includes an organomineral additive in the form of basic electrostatic dust aluminum production in the following ratio of components, wt.%: Silica fume 33.9-54.5 Fly ash 44.5-63.5 Dust of electrostatic precipitators 1.0-2.6 2. A method of manufacturing wall ceramic products from a raw mixture according to claim 1, including the preparation of the mixture, molding, drying, firing and moistening, characterized in that the products are fired at 800 ^about C.