METHOD OF PURIFICATION OF WET-PROCESS PHOSPHORIC ACID Russian patent published in 1999 - IPC

FIELD: production of phosphotizing solutions and salts. SUBSTANCE: method comprises evaporating wet-process phosphoric acid, treating it with apatite concentrate, adding coagulant, clarifying and subsequently separating condensed precipitate from product. Evaporation involves using wet-process phosphoric acid containing 34-40% P₂O₅. Phosphoric acid is evaporated to P₂O₅ concentration of 52- 57% F to F:P₂O₅ and SO2-4

:P₂O₅ weight ratio in acid after evaporation is within 0.003-0.008 and 0.02-0.05, respectively. Acid is then treated with apatite concentrate so as to maintain SO2-4:P₂O₅ weight ratio in acid at 0.003-0.010. After treatment with apatite concentrate, wet-process phosphoric acid is clarified. Clarification rate is 0.18-0.24 m/h. During purification, sulfate content is reduced from 1.1-2.4 to 0.15-0.5% calculated for SO2-4. EFFECT: more efficient purification method. 2 cl, 4 ex, 1 tbl