METHOD OF PURIFYING EXTRACTIVE PHOSPHORIC ACID Russian patent published in 2001 - IPC

FIELD: purification of phosphoric acid to remove sulfates and suspensions, more particularly preparation of industrial salts, phosphotizing solutions. SUBSTANCE: method comprises treating extractive phosphoric acid with sulfate precipitator under stirring at elevated temperature, clarifying and subsequently separating condensed precipitate from product. Precipitator includes strontium compounds which are added in amount which is required to attain Sr²⁺:SO^2- ratio of 0.7-0.8 in acid, stirring is carried out for 24 hours. It is desirable to use strontium carbonate or strontium hydroxide or phosphate as strontium compound and to maintain treatment temperature within 75-85 C. As is obvious from invention, content of impurities such as SO2-4