METHOD FOR PREPARING COMPLEX FERTILIZER Russian patent published in 2004 - IPC

FIELD: agriculture, fertilizers.

SUBSTANCE: invention relates to methods for preparing complex nitrophosphate fertilizers with prolonged effect that are used widely in agriculture. Method involves decomposition of apatite concentrate with nitric acid, isolation of calcium nitrate by crystallization, separation of nitric acid-phosphoric acid solution, its neutralization with ammonia to pH = 0.6-1.2, decomposition of low-grade raw with the neutralized nitric acid-phosphoric acid solution for two stages, additional ammonization of prepared suspension to pH = 4.5-5.5, evaporation, mixing evaporated pulp with ammonium nitrate melt and potassium salt, granulation and drying the ready product. Fluorine compound is added to pulp before additional ammonization to provide the ratio of fluorine and R₂O₃ containing in the pulp liquid phase obtained after the second stage of decomposition of low-grade phosphate raw = (2.5-3.5):1, respectively. Ammonium of alkaline metal fluorides are used as fluorine compounds. Method provides enhancing content of water-soluble forms in fertilizers and to simplify the technological process.

EFFECT: improved preparing method.

2 cl, 3 ex