METHOD OF PURIFYING WET-PROCESS PHOSPHORIC ACID Russian patent published in 2012 - IPC C01B25/234 C01B25/46 B01D11/04 

FIELD: chemistry.

SUBSTANCE: method involves extraction of phosphoric acid with tributyl phosphate, re-extraction thereof from an organic phase and vacuum evaporation thereof to given concentration of P₂O₅. The phosphoric acid extracted tributyl phosphate has concentration P₂O₅ 36% - 39% and sulphate ion concentration equal to 2.5% - 4%, and is obtained via vacuum pre-evaporation of the starting wet-process phosphoric acid. The phosphoric acid re-extract undergoes vacuum evaporation to concentration 50% - 53% P₂O₅. Extraction is carried out in mixer-settlers with 4-5 extraction steps. Further, after extraction, the organic phase undergoes two-step washing with phosphate solution.

EFFECT: method enables to obtain acid which is free from iron, magnesium, fluorine and sulphate ion impurities, and is suitable for producing industrial phosphate salts and food products.

4 cl, 2 tbl, 2 ex