RU2206538C1 - Raw mixture and method for preparing ceramic article with reduced density - Google Patents

Abstract

FIELD: ceramics. SUBSTANCE: invention relates to production of ceramic articles with reduced density and can be used for preparing building materials. Raw mixture for preparing ceramic articles with reduced density comprises siliceous component, additives, pore-forming agent and water. Microsilica with specific surface above 25 000 cm²/g and content of amorphous SiO₂ 90-95% are used as a siliceous component; high-calcium fly ash and Portland cement are used as additives; aluminum powder and detergent "Taiga" are used as a pore-forming agent and components are taken in the following ratio, wt.-%: microsilica, 10.3-11.2; high-calcium fly ash, 18.5-20.2; Portland cement, 12.3-13.5; aluminum powder, 0.1; detergent "Taiga", 0.4; water, 54.6-58.3. Method for preparing ceramic articles with reduced density involves preparing indicated mixture, molding, drying and roasting material being heat-moistening treatment is carried out before drying at 100 C and roasting at temperature 750 C. Invention provides expanding raw basis, reduction of cost of material, improvement of heat-protective indices of material, reduction of linear shrinkage of material in drying. EFFECT: improved preparing method, valuable properties of material. 2 cl, 2 tbl, 1 ex

Description

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

 The closest to the proposed raw mix in technical essence and the achieved effect is the raw mix, including in wt.%: Diatomite 60.18-61.98, sawdust 1.81-1.84, casein-rosin foaming agent 9.50-7.75, water 28.51-28.41 [1].

 The disadvantage of this mixture is the need to use high quality raw materials, high thermal conductivity of the material.

The technical result is the expansion of the raw material base, reducing the cost of the material, improving the heat-shielding characteristics of the material, reducing the linear shrinkage of the material during drying, reducing the firing temperature to 750 ^o C.

The technical result is achieved in that the raw material mixture for the manufacture of ceramic products of low density includes a silica component, additives, a blowing agent and water, and silica fume is used as a silica component with a specific surface area of more than 25 thousand cm ² / g and an amorphous SiO ₂ content _of 90 .. .95%, as additives high calcium fly ash and Portland cement, as a pore former - aluminum powder and Taiga detergent in the following ratio, wt.%:
Silica fume - 10.3-11.2
High calcium fly ash - 18.5-20.2
Portland cement - 12.3-13.5
Aluminum powder - 0.1
Detergent "Taiga" - 0.4
Water - 54.6-58.3
Silica fume produced by crystalline silicon is a dispersed waste characterized by a small particle size (0.1... 3 μm) and, as a result, a high specific surface area (more than 25 thousand cm ² / g). Silica fume is deposited in electrostatic precipitators of the gas treatment system of crystalline silicon production furnaces. The chemical composition of silica fume (in wt.%): SiO ₂ - 90 ... 95; Al ₂ O ₃ to 0.8; Fe ₂ O ₃ to 0.8; CaO up to 1.6; MgO up to 1.2; SiC up to 5; From _total to 9; K ⁺ up to 0.25; Na ⁺ up to 0.06; p.p.p. up to 20.

Fly ash from burning brown coals of the Kansk-Achinsk basin (Irsha-Borodinskoye, Nazarovskoye, Berezovskoye deposits) is high-calcium and contains, wt.%: SiO ₂ - 21 ... 55; Al ₂ O ₃ - 4 ... 11; Fe ₂ O ₃ - 6 ... 16; CaO - 20. ..46; MgO - 3 ... 6; K ₂ O - 0.2 ... 1.5; Na ₂ O - 0.2 ... 0.6; SO ₃ - 0.9 ... 9; CaO _St. - 3 ... 13; combustible impurities no more than 2 ... 2.5.

 Portland cement M400 produced by Achinsk cement plant.

 Detergent "Taiga" (MS "Taiga") is a by-product of sulphate processing of wood produced by "Bratsk Complex Holding" in Bratsk [TU 13-4302007-032-92].

 Detergent is obtained by processing and refining raw sulfate soap, an intermediate product of sulfate-cellulose production.

 The chemical composition of the Taiga detergent, wt.%: Tall saponified fatty acids - 98.6; formalin (preservative) - 0.2; sodium salt of carboxymethyl cellulose or methyl cellulose (actiresorbent) - 0.5; fragrance for soap and detergents - 0.7.

 The introduction of Taiga detergent promotes the involvement of air in the raw material mixture due to the surface-active properties of the additive and intensifies gas evolution during firing due to organic burnout.

 High general and developed closed porosity of the material leads to low thermal conductivity of products.

 The introduction of Portland cement in the raw material mixture allows you to obtain material with sufficient formwork strength after heat-moisture treatment (TBO).

The interaction of CaO of Portland cement and fly ash with amorphous SiO ₂ silica fume strengthens the material during firing due to the synthesis of such high-strength neoplasms as wollastonite and feldspars.

 Closest to the proposed method according to the technical essence and the achieved effect, the method [1], including the preparation of the mixture, molding, drying and firing of the material.

 The disadvantages of this method are the large air shrinkage and high coefficient of thermal conductivity.

The specified technical result is also achieved by the fact that in the method of manufacturing ceramic products of reduced density from a raw mixture, including preparing the mixture, molding, drying and firing the material, prepare the above stated mixture, additionally carry out heat and moisture treatment before drying at 100 ^o C and firing at a temperature 750 ^o C.

Example
The manufacture of the material is as follows. Portland cement, fly ash and silica fume are thoroughly mixed, water (t = 40 ... 60 ^o C) and a pre-prepared 1% solution of MS Taiga are introduced. The mixture is stirred for 3. ..4 minutes The finished suspension of aluminum powder is introduced into the mixture and mixed for no more than 1 min. The mixture is poured into a well-lubricated and hermetically assembled form, the temperature of which is 45 - 55 ^o C. After pouring the mixture into the form is a preliminary exposure of the products. After 2.5-3 hours, the "hump" is cut off and the products are installed in the TVO chamber (steaming mode 3 + 6 + 2 hours at t = 85 ^o C). The cooled products are redistributed and dried to constant weight at a temperature of 100 ^o C. The products are fired at a temperature of 750 ^o C.

 The composition of raw mixes and physico-technical indicators of finished products are presented in table. 1 and 2.

Literature
1. Kitaytsev V.A. Technology of thermal insulation materials. - M .: Publishing house of literature on construction, 1970, p. 223, 227-230.

Claims (1)

1. The raw material mixture for the manufacture of ceramic products of low density, including a siliceous component, additives, a blowing agent and water, characterized in that as a siliceous component using silica fume with a specific surface area of more than 25 thousand cm ² / g and an amorphous SiO ₂ content _of 90 - 95 %, as additives - high-calcium fly ash and Portland cement, as a pore-forming agent - aluminum powder and Taiga detergent in the following ratio of components, wt.%:
Silica fume - 10.3 - 11.2
High calcium fly ash - 18.5 - 20.2
Portland cement - 12.3 - 13.5
Aluminum powder - 0.1
Detergent "Taiga" - 0.4
Water - 54.6 - 58.3
2. A method of manufacturing ceramic products of low density from a raw material mixture, including preparing the mixture, molding, drying and firing the material, characterized in that the mixture is prepared according to claim 1, additionally carry out heat and moisture treatment before drying at 100 ^o C and firing at a temperature of 750 ^o FROM.

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