METHOD OF PREPARING OF ORTHO-PHOSPHORIC ACID OF SPECIAL PURITY Russian patent published in 1994 - IPC

FIELD: chemical technology. SUBSTANCE: method involves hydration of phosphorus pentoxide at 160-200 C. Hydration is carried out at two stages: the first stage is carried out with 0.7-0.9-fold water quantity of stoichiometric one in the presence of 0.1-0.3 wt.-% (with regard to phosphorus pentoxide) inorganic oxygen-containing phosphorus compound with P-H-links; the second stage is carried out with 0.3-0.1-fold of water quantity of stoichiometric one. The source of compound containing P-H-links: lower oxygen acids of phosphorus (phosphorous, meta-phosphorous, hypophosphorous acids), and their salts also. EFFECT: preparing of special purity phosphoric acid with minimal impurities of metals, arsenic and organic impurities. 2 cl, 2 tbl