METHOD OF PRODUCTION OF PURIFIED PHOSPHORIC ACID Russian patent published in 2008 - IPC C01B25/234 C05G1/06 C01F11/46 

FIELD: production of purified phosphoric acid for food-processing industry and production of fertilizers : ammonium sulfate phosphate and commercial strontium or barium sulfates.

SUBSTANCE: proposed method of production of purified phosphoric acid at simultaneous production of ammonium sulfate phosphate and commercial strontium and barium sulfates; fertilizing ammonium sulfates are mixed with water and pulp is divided into ammonium phosphate solution and insoluble residue; ammonium phosphate solution is treated with cation in H⁺ form till complete absorption of ammonium ions from it, thus obtaining phosphoric acid and cationite in NH₄ ⁺ form; strontium or barium sulfates are settled from acid by their carbonates and are separated from liquid phase in form of commercial product; cationite in NH⁺ ₄ form is subjected to desorption by sulfuric acid solution, thus obtaining ammonium sulfate solution which is mixed with insoluble residue; pulp thus obtained is evaporated, granulated and dried. Fertilizing ammonium sulfate is mixed with water at solid-to-liquid ratio = 1 : (1-3). Phosphoric acid is evaporated to concentration of 73-85% of H₃PO₄ and is withdrawn from the process in form of finished product.

EFFECT: enhanced efficiency; high purity of acid.

4 cl, 6 tbl