SU44828A1 - The method of obtaining refractory material from dolomite and chromium iron - Google Patents

Description

Dolomite is mainly used for the filling of hearths in open-hearth furnaces, for which it is pre-crushed and mixed with resin.

The main disadvantage of baked dolomite is its poor stability. Dolomite with a relatively high content of SiO2 after calcination, due to the formation of dicall silicate 2CaO SiOj and its polymorphic transformation, is scattered during cooling. Dolomite with a relatively lower content of SiOj and other fluxes after calcination, under the influence of moisture in the air, is scattered over time due to the slaking of unbound lime. Only part of the dolomite remains in pieces suitable for crushing and use, but dolomite dust is not used. All this leads to the concentration of dolomite-firing installations at the place of consumption, which, due to the remoteness of the deposits from the consumer, entails the transportation of large masses of raw dolomite, and with it about 50% of ballast form of CO2.

The scattering of dolomite limits its use in the form of dolomite refractory bricks due to their instability.

The authors found that with a certain chemical composition of dolomite and a corresponding increase in chromic

A well-resistant dolomite refractory material can be obtained to it and to a proper technological process.

The addition of chromic iron to dolomite with appropriate roasting gives refractory materials that do not dissolve both during cooling and in moist air, while other satisfactory qualities, such as refractoriness, the absence of deformation under load at high temperatures, etc., remain. which is not achieved by the introduction of other components.

Mixing dolomite with a chromic iron can be done both wet and dry.

In the first case, the raw dolomite is crushed, crushed and mixed with water to a state of liquid sludge.

The analysis determines the percentage of SiO2 and the corresponding adjustment is adjusted to 5-8%, after which approximately 15% (by weight of dry dolomite) of finely chopped (a sieve of 900 holes, chromic iron.) Is added. The amount of chromium iron added depends on the chemical composition of dolomite and ranges from 12-18%. The resulting sludge is burned in rotary kilns, such as cement, to a temperature of approximately 1500 °, i.e., to a sintering temperature.

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roasting, after-grading crushing with or without crushing, is used as a padding material for baking steel-steel furnaces, sintering areas of rotary kilns, etc. Coal tar, molasses, sulfite, cellulose liquor, magnesium chloride, caustic magnesite (cement Sorel), etc.

The same clinker, after grinding, in order to obtain a specific particle size distribution, can be used for the manufacture of refractory products by mixing the crushed clinker with a binder, subsequent pressing and calcining, or without it.

When dry mixing, raw crushed dolomite containing SiOj in the range of 5–8% is mixed with chromium iron in an amount of approximately 15%. Add to the mix «« 1 ||| # Г

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the binder is pressed, briquettes are pressed, KOTOpbie is burned at a temperature of about -1500 ° and crushed. The material thus obtained can be used as a base for, heat, hell, furnaces or as a material for the production of refractory brick.

The subject matter of the invention.

The method of producing refractory material from dolomite and chromic iron, characterized in that about 15% of chromium iron is added to the crushed raw dolomite containing from 5 to 8% silica, the mixture is burned before sintering and milled for use or as a packing material for hearth and lining of furnaces or for the manufacture of refractory bricks, with or without subsequent firing.