METHOD OF PREPARING GRANULAR SUPERPHOSPATE Russian patent published in 2001 - IPC

FIELD: preparation of granular superphosphate. SUBSTANCE: method comprises decomposing part of phosphate stock with sulfuric acid, subsequently mixing pulp with remaining part of phosphate stock, granulating and drying the product. In this case, phosphate stock is dust-like apatite concentrate containing particle size of greater than 0.071 mm (0.5-5%) and less than 0.005 mm (6-58%) of total weight, decomposition is carried out at P₂O₅ : H₂SO₄ ratio of 1:(3-5), and nepheline-containing components are added to the resulting pulp after it has been mixed with remaining part of phosphate stock in amount of 0.2-1.5 wt.pts per 1 wt.pt of P₂O₅ of free pulp. 30-80% of dust-like apatite concentrate of total amount are fed to decomposition stage. Method makes it possible to prepare product which is stable with respect to fractions and has high strong granules from substantially substandard dust-like apatite concentrate. EFFECT: more efficient preparation method. 3 cl