RU2209800C1 - Raw mixture and method for preparing ceramic material with reduced density - Google Patents

Abstract

FIELD: building industry. SUBSTANCE: invention relates to production of ceramic materials with reduced density that can be used for making building materials. Raw mixture for preparing ceramic materials with reduced density comprising microsilica with specific surface above 25 000 cm²/g and content of amorphous SiO₂ 90-95%, high-calcium fly ash and water involves additionally Portland cement and pore-forming agents - aluminum powder and sulfate soap in the following ratio of components, wt.-%: indicated microsilica, 10.3-11.2; high-calcium fly ash, 18.5-20.2; Portland cement, 12.3-13.5; aluminum powder, 0.1; sulfate soap, 0.4; water, 54.6-58.3. In method for preparing ceramic materials with reduced density including preparing mixture containing microsilica with specific surface above 25 000 cm²/g and content of amorphous SiO₂ 90-95%, high-calcium fly ash and water process of molding, drying at 100 C and roasting material using above indicated mixture heat-wetting treatment is carried out before drying and roasting is carried out at 750 C. Invention provides expansion of raw base, reduced cost of material, improvement of heat-protective indices of material, reduction of linear drying shrinkage of material, reduced roasting temperature to 750 C. EFFECT: improved preparing method. 2 cl, 2 tbl, 1 ex

Description

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

 Known raw material mixture, including in wt.%: Diatomite 60.18-61.98, sawdust 1.81-1.84, casein-rosin foaming agent 7.75-9.50, water 28.41-28.51 [1 ].

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

 A known method, including the preparation of a mixture, molding, drying and firing of the material [1].

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

Closest to the proposed raw material mixture is a raw material mixture for the preparation of ceramic materials containing wt.%: Silica fume with a specific surface of more than 25 thousand cm ² / g and a SiO content _of 90-95% - 15-80 and high-calcium fly ash - 20 -85 and water to a moisture content of 16 [2]. This mixture provides products of reduced density.

Closest to the proposed method is a method of preparing ceramic materials, comprising preparing a mixture containing wt.%: Silica fume with a specific surface area of more than 25 thousand cm ² / g and a SiO content _of 90-95% - 15-80, high-calcium fly ash - 20-85 and water to a moisture content of 16, molding, drying at 100 ^o C, firing at 1000 ^o C [2]. The specified method provides a material of reduced density.

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 preparation of ceramic materials of reduced density, including silica fume with a specific surface area of more than 25 thousand cm ² / g and an amorphous SiO ₂ content _of 90-95%, high calcium fly ash and water, additionally contains Portland cement and pore formers - aluminum powder and sulfate soap, in the following ratio of components, wt.%:
The specified silica fume - 10.3 - 11.2
High calcium fly ash - 18.5 - 20.2
Portland cement - 12.3 - 13.5
Aluminum powder - 0.1
Sulphate soap - 0.4
Water - 54.6 - 58.3
The technical result is achieved by the fact that in the method of preparing ceramic materials of reduced density, including the preparation of a mixture containing silica fume with a specific surface area of more than 25 thousand cm ² / g and an amorphous content of SiO _{2 of} 90-95%, high-calcium fly ash and water, molding, drying at 100 ^o C and firing the material, when using this mixture, heat and moisture treatment is carried out before drying, and firing at 750 ^o C.

Silica fume produced by crystalline silicon is a dispersed waste characterized by a small particle size (0.1 ... 3 microns) and, as a result, a high specific surface (more than 25 thousand cm ² / g). Silica fume is deposited in electrostatic precipitators of the gas treatment system of melting furnaces for the production of crystalline silicon and ferroalloys. 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 to 1.6, MgO to 1.2, SiC to 5, C _total up to 9, K ⁺ up to 0.25, N ⁺ up to 0.06, p.p.p up to 20.

Fly ash from burning brown coal of the Kansk-Achinsk basin (Irsha-Borodinskoye, Nazarovoskoye, Berezovskoye deposits) is high-calcium and contains, wt.%: SiО 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 - not more than 2 ... 2.5.

 Portland cement M400 produced by Achinsk cement plant.

 Sulphate soap is a product that is removed from the surface of the black liquors of sulphate-cellulose production when cooking pulp from coniferous and deciduous species of wood, is a greasy product from dark yellow to dark brown.

 In accordance with the technical specifications TU 13-0281078-28-118-88, the chemical composition of sulfate soap, wt.%: Fatty resin acids and unsaponifiable substances - not less than 40-45; water - no more than 35-50; total alkali in terms of NaOH - not more than 9. Soap is contaminated with lignin, tannides and dyes, as well as mineral components.

 The introduction of sulfate soap 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 the burning out of organics.

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

 The introduction of Portland cement in the raw mix allows you to get after TVO material with sufficient formwork strength.

The interaction of CaO 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.

 A method of manufacturing products includes the preparation of a mixture, molding, TVO, drying and firing of the material, while the porization of the material occurs due to gas generation together with air entrainment.

 Example.

The manufacture of the material is as follows. Portland cement, fly ash and silica fume are thoroughly mixed, water is introduced (t = 40 ... 60 ^o C) and a pre-prepared 1% solution of sulfate soap. 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 mold, the products are pre-conditioned. After 2.5-3 hours, the "hump" is cut off and the products are installed in the TVE chamber (steaming mode 3 + 6 + 2h 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.

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

 2. RF patent 2086517, С 04 В 35/14, 08/10/1997, 3 pp.

Claims (1)

1. The raw material mixture for the preparation of ceramic materials of low density, including silica fume with a specific surface area of more than 25 thousand cm ² / g and an amorphous SiO ₂ content _of 90-95%, high calcium fly ash and water, characterized in that it additionally contains Portland cement and blowing agents - aluminum powder and sulfate soap, in the following ratio of components, wt. %:
The specified silica fume - 10.3-11.2
High calcium fly ash - 18.5-20.2
Portland cement - 12.3-13.5
Aluminum powder - 0.1
Sulphate soap - 0.4
Water - 54.6-58.3
2. A method of preparing ceramic materials of reduced density, including the preparation of a mixture containing silica fume with a specific surface area of more than 25 thousand cm ² / g and amorphous SiO ₂ content _of 90-95%, high-calcium fly ash and water, molding, drying at 100 ^° C and firing the material, characterized in that when using the mixture according to claim 1, heat and moisture treatment is carried out before drying, and firing at 750 ^o C.

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