PROCESS FOR PREPARING MIXED PHOSPHORUS CONTAINING FERTILIZERS Russian patent published in 1997 - IPC

FIELD: agriculture. SUBSTANCE: claimed process comprises mixing phosphorite with sulfuric acid and dry ammonium sulfate at P₂O₅:H₂SO₄:(NH₄)₂SO₄ ratio of 1: (0.05- 1.0):(0.05-11). The resulting mixture is granulated by addition of ammonium sulfate solution in amount of 20-50% (calculated for ammonium sulfate) of the total amount of ammonium sulfate, and product is treated at 70 to 140 C. Ammonium sulfate solution is used at concentration of 15- 45%, and potassium containing additives, nitrogen- phosphorus containing additives and microelements are additionally added to the mixture. Potassium containing additives include potassium sulfate and potassium chloride, and nitrogen phosphorus containing additive includes dihydroammonium phosphate. The claimed process makes it possible to obtain fertilizers having high granule strength and to produce wide range of fertilizers. EFFECT: improved properties of the title fertilizer. 3 cl