METHOD OF PHOSPHORIC ACID PRODUCTION Russian patent published in 1997 - IPC

FIELD: chemical technology, inorganic chemistry. SUBSTANCE: invention relates to production of wet-process phosphoric acid used in agriculture. Method involves decomposition of phosphate raw with reusable phosphoric and sulfuric acids. Decomposition is carried out in the presence of sulfuric acid amount sufficient for producing CaO pulp in liquid phase bound to monocalcium phosphate at amount 0.7-1.7 wt.-% and to producing the ratio of dihydrate to semihydrate in solid phase (precipitate of calcium sulfate) (1-5): 1, respectively. Then recrystallization is carried out by addition of sulfuric acid to preparing calcium sulfate precipitate to semihydrate. Precipitate is washed off and filtered. EFFECT: improved method of production.