Method for dry preparation of barium fluorosilicate and barium fluoride

Abstract

The invention relates to a method for dry preparation of barium fluoride and barium fluorosilicate, which specifically comprises the following steps: adding ammonia water or ammonium bicarbonate in fluorosilicic acid solution for carrying out reaction, cooling and filtering for preparing an ammonium fluorosilicate product; evenly mixing the prepared ammonium fluorosilicate with barium carbonate orbarium hydroxide according to the theoretical amount, and generating the barium fluorosilicate and ammonia or the ammonium bicarbonate; introducing the generated ammonia or the ammonium bicarbonate into the fluorosilicic acid solution, carrying re-ammonolysis for preparing the ammonium fluorosilicate and emptying the remaining gas; calcining the generated barium fluorosilicate for generating thebarium fluoride and silicon tetrafluoride gas; and using water for absorbing the generated silicon tetrafluoride gas and carrying out hydrolysis, filtering, preparing the fluorosilicic acid solution and being used for ammonolysis. The raw material of the fluorosilicic acid adopted by the method is a byproduct which is a hazardous waste generated during the production process of a phosphate fertilizer, thereby having few uses and causing serious impact on the environmental protection; and the method just utilizes the fluorosilicic acid as the raw material for ammonolysis for further preparing the ammonium fluorosilicate, the dry reaction of the ammonium fluorosilicate with a barium salt or alkaline solution of barium is carried out for preparing the barium fluorosilicate, and calcining theprepared barium fluorosilicate for preparing the barium fluoride.

Description

technical field [0001] The invention relates to a dry method for preparing barium fluoride and co-producing the intermediate product barium fluorosilicate, in particular to a method for preparing barium fluoride by using fluorosilicic acid or ammonium fluorosilicate, barium carbonate or barium hydroxide as main raw materials Or the method of intermediate product barium fluorosilicate. Background technique [0002] Barium fluorosilicate is white oblique needle crystal with a density of 4.29g / cm 3 , slightly soluble in water, acid, ammonium chloride, insoluble in alcohol, and decomposes at 300°C. Long-term contact with water produces hydrolyzate, which will accelerate hydrolysis in the presence of alkali. It is mainly used in the manufacture of silicon tetrafluoride, and can also be used in ceramics and pesticides. The traditional method for preparing barium fluorosilicate is to add barium chloride solution into fluorosilicic acid solution and heat for reaction, then filter,...

AI Technical Summary

Problems solved by technology

The traditional method of producing barium fluoride is to dissolve barium carbonate in excess hydrofluoric acid for reaction, which requires a large amount of hydrofluoric acid, which is mainly produced by the reaction of fluorite and sulfuric acid, so the traditional production method needs to consume valuable strategies Resources - fluorspar, the state has increased the control over fluorspar at present, the price of fluorspar is getting higher and higher, and the price of hydrofluoric acid is bound to rise accordingly, thus affecting the cost of barium fluoride

In addition, when barium fluoride is produced by traditional methods, the concentration of hydrofluoric acid is relatively strict. If the control is not appropriate, the barium fluoride produced will be finer. Under this condition, a large amount of mother liquor will be discharged, which will cause serious environmental problems big pressure

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