METHOD OF PROCESSING PHOSPHATE STOCK INTO PHOSPHORIC ACID Russian patent published in 2003 - IPC

FIELD: inorganic materials technology. SUBSTANCE: phosphate stock containing carbon dioxide and chlorine is preliminarily treated at temperature no lower than 90 C with mixture composed of sulfuric and phosphoric acids, amount of the former corresponding to 10-20% of stoichiometry based on CaO and liquid-to-solids ratio during the preliminary treatment being (0.2-0.8): 1. Resulting mass is then treated with sulfuric and phosphoric acids, after which follows crystallization of calcium sulfate and separation of phosphoric acid product by filtration. Degree of dechlorination of phosphate is 82-90% leading to residual chlorine content 0.028-0.05%. EFFECT: enabled processing of phosphorites with high level of chlorine. 2 cl, 2 ex