METHOD OF PRODUCING PURIFIED ORTHOPHOSPHORIC ACID Russian patent published in 1999 - IPC

FIELD: industrial inorganic synthesis. SUBSTANCE: invention relates to producing purified concentrated orthophosphoric acid obtained from extraction destruction of natural phosphates followed by purification with organic extracts and afterpurification to remove fluoride and remains of organic phase by blowing with inert gaseous heat carrier. According to invention, extraction phosphoric acid preliminarily treated with tributyl phosphate and containing 0.040-0.045% fluoride and 0.005 % tributyl phosphate is subjected to afterpurification under intensive heat and mass-exchange conditions in foam apparatus at 80-95 C and specific gas-liquid loading (2-30)*10³m^-2 until 60-78% content of orthophosphoric acid is attained. Resultant product contains no more than 0.005-0.001% fluoride and no more than 0.0005-0.0001% tributyl phosphate and is characterized by elevated degree of decoloration. EFFECT: enhanced purification efficiency and considerable simplified process flowsheet. 3 ex