METHOD OF PREPARING PHOSPHORIC FERTILIZERS Russian patent published in 1999 - IPC

FIELD: agriculture. SUBSTANCE: method comprises decomposition of phosphate raw materials with mineral acid in the presence of monocalcium phosphate followed by granulation, drying and purification of off-gases. Monocalcium phosphate is added to mixture of phosphate raw materials and mineral acid in amount sufficient to maintain ratios (wt parts) of monocalcium phosphate to SO₃ ratio of (9.8-25):1, respectively. Mineral acid includes phosphoric and/or sulfuric acid, and phosphate raw materials include either apatite concentrate or dust- like fraction resulting from purification of off-gases in apatite concentrate production. Monocalcium phosphate constituent includes superphosphate pulp, coarse and fine fraction of final product, dust resulting from purification of gases. In order to use dust-like fraction of phosphate raw materials, dust is taken from cyclones and electric filters intended to purify apatite concentrate at 4:1 ratio, respectively. EFFECT: improved granulation and drying conditions of the phosphoric fertilizers and ecologically safe process. 4 cl, 6 ex