RU2178395C2 - Blend for preparing refractories - Google Patents

Abstract

FIELD: metallurgical and building industries and heat engineering. SUBSTANCE: blend comprises, wt. %: alumina, 10-80; silicon carbide, 1-50; spinel and/or clinker, 1-80; ferrosilicon, 3-20; liquid glass, 3-10; and water, 5-15. Ferrosilicon is used in the form of cyclonic dust after crushing ferrosilicon ingot having silicon content of not lower than 75 wt. %. EFFECT: drying time of refractories reduced by 5 or 6 times, elimination of ecologically adverse factors, lower manufacturing cost of refractories. 1 tbl

Description

 The invention relates to the metallurgical industry, and in particular to the production of refractory materials used in the construction, heat engineering and other industries.

 Known mixture containing aluminum oxide in an amount of 100 wt. % and 0.1-4 wt. % elemental silicon or ferrosilicon [1].

 The disadvantage of this mixture is the need for mandatory firing with an excess of oxygen in the process of obtaining refractories. This reduces the performance of the process of obtaining refractories, requires the use of expensive equipment.

 The closest in technical essence and the achieved effect to the proposed one is a mixture for producing refractory material, including alumina, spinel or its mixture with clinker, silicon carbide, ferrosilicon and tar tar as a binder [2].

 The disadvantage of this mixture is the length of the drying process, as well as harmful environmental factors associated with the use of tar tar and phenolic, furan resins.

 The objective of the invention is to eliminate these disadvantages, namely reducing the drying time of refractories, the exclusion of environmentally harmful components.

This object is achieved by the fact that in the known mixture to obtain refractories containing alumina, silicon carbide, spinel and / or clinker, ferrosilicon and a binder, according to the invention, it contains water glass as a binder, and ferrosilicon in the form of cyclone dust after crushing ferrosilicon ingot with a silicon content of not less than 75 wt. %, in the following ratio of these components, wt. %:
Alumina - 10-80
Silicon Carbide - 1-50
Spinel and / or clinker - 1-80;
Ferrosilicon - 3-20
Liquid glass - 3-10
Water - 5-15
The fact that the charge additionally contains liquid glass leads to the fact that during the mixing of the components of the charge, a reaction occurs between the alkali contained in the liquid glass and the active silicon located in the cyclone dust of ferrosilicon with the release of heat:
2 NaOH + Si + H ₂ O = Na SiO ₃ + 2H ₂ + g.

 The passage of this reaction with the release of heat reduces the drying time of refractories.

In a thermally insulated container, this temperature of self-heating reaches 1000 ^o C, and in open containers it reaches 70-75 ^o C.

 The use of liquid glass with ferrosilicon makes it possible to exclude environmentally harmful components from the compositions that act as a binder and an accelerator for sintering (resins, tar). This will improve the ecology of the production of refractories.

 Adding to the charge of liquid glass less than 3 wt. % leads to a slowdown of the reaction between the alkali contained in the liquid glass and the active silicon, which is part of ferrosilicon. This increases the drying time of the refractories and reduces the strength of the refractories. Adding to the mixture of liquid glass more than 10 wt. % leads to a decrease in the strength of refractories at high temperatures, i.e., to fusibility.

 The use of ferrosilicon in the mixture in the form of cyclone dust after crushing a ferrosilicon ingot with a silicon content of less than 75 wt. % leads to the exclusion of microvolume sintering, to delayed “seizure” of refractories.

 The use of a mixture of ferrosilicon less than 3 wt. % leads to incomplete volumetric sintering of the mixture, which reduces the strength of the refractory, its use is more than 20 wt. % - reduces the temperature resistance and strength of the refractory.

 The proposed mixture is prepared as follows.

 Alumina, silicon carbide, ferrosilicon, spinel or clinker are mixed. Then pour the mixture into liquid glass diluted with water, continuously mixing the components.

 The proposed mixture was manufactured and tested at the Chelyabinsk Abrasive Plant. It contained ferrosilicon in the form of cyclone dust after crushing of a ferrosilicon ingot with a silicon content of 75 and 65 wt. % The mixture contained magnesite spinel with high alumina clinker.

 The test data are summarized in table.

After drying, all samples N 2, 4, 5, 7-9, 11, 13-16 showed a bending strength of at least 12 MPa / cm ² , compressive strength of at least 30 MPa / cm ² .

 A decrease in water content of less than 5 wt. % leads to incomplete passage of the reaction, which reduces the strength characteristics of refractories. Water pressure of more than 15% leads to the formation of pores during drying and a decrease in temperature resistance.

Samples N 6 and 12 showed, respectively, bending strength of 6 and 8 MPa / cm ² , compressive strength of 22 and 14 MPa / cm ² , which is 1.5-2 times lower than that of samples of the claimed composition.

 A plate made from the composition of sample No. 16 under the same conditions, withstood 7 thermal cycles and collapsed.

The manufactured plates with sizes 400x200x25mm of samples 6, 8, 9, 10, 11 and 13 were subjected to loading of 15 kg, in the center of the plates in a continuous kiln at a temperature of 1250 ^o C. All the samples withstood 60 thermal cycles without external changes.

 The drying time of refractories was reduced in comparison with the known charge by 5-6 times.

 The proposed mixture is expediently used to obtain refractory masses used for lining steel casting ladles, for the manufacture of backing plates for high-temperature firing of ceramic products for the production of refractory bricks, as well as for packing masses in metallurgy and heat engineering.

Sources of information
1. Japanese patent N 52-31369. Production of corundum refractories with mullite binder. MKI S 04 B 35/10, declaration 12/23/68, N 50-2524, publ. 08/15/77.

 2. Japanese Patent Laid-Open No. 55-37459, Refractory material for a molten metal trough. MKI S 04 B 35/10, declaration 09/09/78. publ. 03/15/80.

Claims (1)

A mixture for producing refractories containing alumina, silicon carbide, spinel and / or clinker, ferrosilicon and a binder, characterized in that it contains liquid glass with water as a binder, and ferrosilicon in the form of cyclone dust after crushing of a ferrosilicon ingot with a silicon content not below 75 wt. % in the following ratio of components, wt. %:
Alumina - 10-80
Silicon Carbide - 1-50
Spinel and / or clinker - 1-80
Ferrosilicon - 3-20
Liquid glass - 3-10
Water - 5-15

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