Compositions: ceramic – Ceramic compositions – Refractory
Patent
1991-06-04
1993-01-19
Group, Karl
Compositions: ceramic
Ceramic compositions
Refractory
501 94, C04B 3542
Patent
active
051806983
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of preparing refractory chromium-containing material.
BACKGROUND OF THE INVENTION
Known in the art is a method of preparing refractory articles from a chromium-containing material (SU, A, 678042) which comprises the mixing of a chromite ore, finely ground baked magnesite, and a binder, for instance, lignosulphonate, roasting of the prepared mixture at a temperature of from 1600.degree. to 1700.degree. C., fractionation of the baked material, preparation of a charge from 60 mass % of chrome-magnesite bake and 40 mass % of baked magnesite powder, molding of blanks from the charge, and roasting of the blank at a temperature of from 1700.degree. to 1800.degree. C. The mixing of the components is performed by multiple successive delivery of portions of the binder and baked dispersed magnesite into the grainy chromite ore, the amount of each of the components in the portion being 10-25% of the required quantity.
Also known in the art is a method of preparing refractory chromium-containing material in the form of an article (U.S. Pat. No. 4,169,734) which comprises the preparation of a mixture from fractionated powders of magnesite and chromite ore at a mass ratio of 30-90: 10-70, respectively, in the presence of 0.5-1.5 mass % of a binder selected from the group consisting of: MgCl.sub.2, MgSO.sub.4, and Ca(NO.sub.3).sub.2, or without a binder; molding of a blank from the prepared mixture in the presence of water under a high pressure; roasting of the blank at a temperature of from 1700.degree. to 1800.degree. C. to the article.
Likewise known in the art is a method of preparing refractory chromium-containing material (GB, A, 1510949) in the form of an article which comprises the preparation of a mixture from 26-56 mass % of a chromium-containing component, for instance, chromite, which is fractionated preliminarily to 0.5-5 mm (10-40 mass %) and 0.1 mm (60-90 mass %), with the fraction of the particles .ltoreq.0.06 mm in size being no less than 70% of the chromite mass in said mixture. Baked magnesite (MgO) is ground preliminarily to a particle size <0.1 mm with the content of particle .ltoreq.0.06 mm in size equal to 70% of the magnesite mass; Blanks are molded from the mixture, and are subjected to a subsequent thermal treatment of the blanks at a temperature of from 1700.degree. to 1900.degree. C. for 4 hours to form the articles, for instance, bricks.
The known methods are multi-stage, power-intensive, and time-consuming. The prepared materials are characterized by refractoriness values not exceeding 1600.degree. C. which limits the field of application. Physical and mechanical characteristics of these materials are not constant and greatly depend on the dispersity of the initial components in the mixture which deteriorates essentially the quality of the articles manufactured from the above materials.
The principal object of the invention is to provide a method of preparing refractory chromium-containing material via a qualitative change of the composition of the mixture and thermal treatment conditions which will improve essentially physical and mechanical characteristics of the final material, simplify the technological process, and decrease energy consumption.
Said object is accomplished by a method of preparing refractory chromium-containing material comprising the preparation of a mixture from a chromium-containing component and a binder and thermal treatment of the mixture, wherein, according to the invention, as the binder introduced in an amount of 0.1-50 mass %, use is made of periclase, sand, clay refractory oxide, refractory scrap, wastes of blast-furnace processes, graphite production, and silicon carbide production, and inorganic salts taken separately or in a mixture. 8-20 mass % of a reducer is additionally introduced into the above mixture. As the reducer, use is made of at least one of the metals selected from the group consisting of aluminium, magnesium, silicon, zirconium, titanium and alloys thereof, after which the prepare
REFERENCES:
patent: 3542530 (1970-11-01), Talboom, Jr.
patent: 4169734 (1979-10-01), Brezny
patent: 4508835 (1985-04-01), Kaniuk et al.
Borovinskaya Inna P.
Ismailov Marat B.
Merzhanov Alexandr G.
Nersesian Mikael D.
Xandopulo Georgy I.
Gallo Chris
Group Karl
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