METHOD FOR OBTAINING PURE TUNGSTIC ACID Russian patent published in 2015 - IPC C01G41/00 C22B34/36 C22B3/06 C22B3/14 

FIELD: chemistry.

SUBSTANCE: method includes processing of tungsten-containing raw material with acid with obtaining sediment of technical tungstic acid, which is processed with ammonia solution to dissolve tungstic acid and obtain ammonia solution of ammonium tungstate. After that, purification of ammonia solution of ammonium tungstate from admixtures is carried out, with obtaining tungsten-containing product, which is processed with acidic solution to obtain sediment of pure tungstic acid. As acidic solution used is ammonium hydrosulphate solution. Processing results in sediment of pure tungstic acid in ammonium sulphate solution. After separation of residue of pure tungstic acid, crystalline ammonium sulphate is separated from solution, with its further thermal decomposition into ammonium hydrosulphate and ammonia. Ammonium hydrosulphate is returned to processing of purified from admixtures tungsten-containing product, with ammonia being returned for processing of technical tungstic acid.

EFFECT: obtaining pure tungstic acid with reduction of hydrochloric acid consumption, termination of discharging solutions, polluting the environment, and regeneration of reagents.

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