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

FIELD: preparation of complex mineral fertilizers, more particularly preparation of fertilizers having NPK compositions. SUBSTANCE: method comprises nitrate of phosphate stock, ammoniating acid phosphorus-containing solution, evaporation, addition of potassium sulfate, granulation and drying of desired product. Pulp is evaporated to residual moisture content of 10-20 wt %, and potassium sulfate is added after these values of moisture content of pulp have been reached, ammoniating is first carried out with gaseous ammonia to pH of 1.5 and then with ammonia water to pH of 5.0-5.5. EFFECT: high-grade chlorine-free NPKS fertilizer, optimized production process due to evaporation of pulp to residual moisture content of 10-20 wt % and addition of final potassium sulfate without using sulfuric acid in said process. 5 cl