METHOD FOR TREATMENT OF WET-PROCESS PHOSPHORIC ACID Russian patent published in 2003 - IPC

FIELD: inorganic chemistry, chemical technology. SUBSTANCE: invention relates to method for preparing phosphoric acid with low content of impurities used in production of phosphates with technical and food grading. Method involves liquid extraction with tributyl phosphate and the following separation of aqueous and organic phases and re- extraction of phosphoric acid from organic phase with water. Extraction and re-extraction are carried out in pulsation columns by mixing aqueous and organic phases to form emulsion at air effect at temperature of extraction 30-50 C and temperature of re-extraction 40-80 C. The total water flow feeding to re-extraction stage is divided for two parts in the ratio V1 : V2 = 1 : (3-9); the first part of water is mixed with extract and after separation of phases an aqueous phase polluted with impurities is mixed with wet-process phosphoric acid in the volume ratio = 1 : (6-15) followed by transfer to the extraction stage with tributyl phosphate to the start of process and extract is fed to mixing with the second part of water for preparing the purified phosphoric acid. Method provides reducing content of impurities of metals in the purified acid by 2-4-fold, i. e. to enhance quality of the purified acid. EFFECT: improved treatment method. 6 cl, 1 tbl, 2 ex