METHOD OF PRODUCING PHOSPHORIC ACID FROM NODULAR PHOSPHORITES Russian patent published in 1998 - IPC

FIELD: chemical technology, inorganic chemistry. SUBSTANCE: invention relates to a method of producing wet-process phosphoric acid and can be used for mineral fertilizers making. The parent nodular phosphorites are ground, separated for fractions 0.1 mm (border grain size), fraction +0.1 mm is charged out with high-quality phosphate raw to required content of Fe₂O₃ in charge and processing is carried out for two stages. At the first stage the charged out large fraction is treated with an excess amount of reusable phosphoric acid at ratio P₂O₅ raw : P₂O₅ acid = 1:(6-12). The obtained pulp is condensed to ratio solid : liquid = 1:3 and decanted. At the second stage the condensed pulp is treated together with raw fraction - 0.1 mm with sulfuric and phosphoric acids at dihydrate regime and production acid and calcium sulfate are obtained. Discharge from the condensation stage is fed to the stage of calcium sulfate crystallization. EFFECT: increased content of nodular phosphorites in phosphoric acid production. 3 dwg, 3 tbl