METHOD OF OBTAINING EXTRACTION PHOSPHORIC ACID Russian patent published in 2014 - IPC C01B25/22 

FIELD: chemistry.

SUBSTANCE: method includes decomposition of phosphate raw material with ratio P₂O₅:MgO=14-53 with mixture of phosphoric and sulfuric acids in presence of pulp recirculating in decomposition zone with multiplicity 10-85 at temperature 85-95°C with obtaining calcium sulfate pulp in phosphoric acid. After that, carried out are: cooling of 30-100% of circulating pulp out in mode of foam layer at temperature gradient 0.5-0.4°C, pulp maturing, separation of production phosphoric acid by filtration, washing of precipitation in counterflow mode with formation of circulating phosphoric acid and its return to stage of decomposition. Decomposition of phosphate raw material is performed in presence of additives of acid-soluble aluminium compounds, supplied to process in amount sufficient to provide content of Al₂O₃ in pulp liquid phase 0.3-0.7%, and ratio of P₂O₅ to sulfates and fluoride compounds in phosphoric acid solution P₂O₅:SO₃=25-50 and P₂O₅:F=30-50 with crystallisation of calcium sulfate in form of easily-filtering a-semihydrate of calcium sulfate.

EFFECT: increase of equipment productivity, P₂O₅ content in production acid and efficiency of P₂O₅ washing, reduction of waste product formation.

2 cl, 1 tbl, 16 ex