METHOD OF COMPLEX FERTILIZER PRODUCING Russian patent published in 1999 - IPC

FIELD: fertilizers. SUBSTANCE: invention relates to production of complex granulated fertilizers by nitric acid method of phosphate raw processing. Method involves a single-stage decomposition of phosphate raw with nitric acid, preparing nitric acid extract, crystallization of calcium nitrate and its removal, neutralization of phosphate solution, evaporation, melt mixing with potassium chloride and granulation. The process of decomposition is carried out with nitric acid at amount 110% of stoichiometry with 3-15% of ammonium nitrate at concentration 93%, not above, in the presence of carbamide and at maintenance of nitric acid concentration from 47.7% to 55.0% in the reaction zone. Method ensures to decrease the degree of nitrogen oxides evolution up to 75% at the stage of phosphate raw decomposition, increase the rate of calcium nitrate crystals filtering, decrease ammonia consumption for neutralization of nitrophosphate solution. EFFECT: improved method of producing, high effectiveness of the process. 2 tbl, 4 ex