METHOD FOR PURIFYING EXTRACTION PHOSPHORIC ACID Russian patent published in 2008 - IPC C01B25/234 

FIELD: chemistry.

SUBSTANCE: invention relates to methods for purifying evaporated extraction phosphoric acid, produced during apatite concentrate decomposition, to eliminate sulphates and suspended matter. Purifying results in sulphateless phosphoric acid, which is used in purified phosphoric acid production based on solvent extraction with tributyl phosphate, as well as in phosphating agents and other technical grade phosphates production. Method for purifying evaporated extraction phosphoric acid, produced from apatite, from sulphates and suspended matter implies treatment of the acid (which is heated and stirred) with apatite concentrate, clarification in the presence of coagulant and separation of clarified sulphateless acid and concentrated portion thereof. For separation, sulphateless acid, which contains 5-11% of suspended matter, is supplied. Separation is carried out continuously in thin layer, on tilted sedimentation plates, linear speed of suspension being 3-11 m/h, until clarified acid in 60-80% yield (on the basis of Р₂О₅ )_{is obtained. Sulphates are eliminated until residual SO4 ^2- content in clarified extraction phosphoric acid is 0.3-0.5%, and acids are separated until residual content of suspended matter is 0.1-0.5%. Acid is treated with apatite concentrate at 70-95°С.}

EFFECT: process simplification and operational costs reduction.

3 cl, 4 ex