METHOD FOR PRODUCING COMPOUND FERTILISERS Russian patent published in 2008 - IPC C05B11/00 

FIELD: chemistry.

SUBSTANCE: invention relates to the method for producing compound fertilisers, namely the nitro-phosphate fertilisers of prolonged action, and in the process involving low-grade phosphate raw material. The method for producing compound fertilisers, which includes decomposition of apatite concentrate of nitric acid, the isolation of calcium nitrate by crystallisation, separation of nitro-phosphoric solution, the decomposition of low-grade phosphate raw material, ammoniation, granulation and drying of finished product. To the decomposition of the low-grade phosphate part of the nitro-phosphoric solution is added, taken in a quantity necessary to get in the pulp of the decomposition pH=1.8 - 2.5, the remaining part of the solution is ammoniated to pH=4.5 - 5.5, the obtained ammoniated pulp is steamed and mixed with the pulp of the decomposed low-grade phosphate raw material, and then ammonia is added into the mixture of the pulps till pH=4.2 - 4.7. Additionally, ammonium nitrate is added, and before granulation potassium chloride is added.

EFFECT: reduced volume of the reactionary equipment, improved technological effectiveness of the process.

2 cl, 3 ex