METHOD OF PRODUCING GRANULAR MINERAL FERTILISER Russian patent published in 2014 - IPC C05B11/06 

FIELD: chemistry.

SUBSTANCE: invention relates to agriculture. The method of producing granular mineral fertiliser includes decomposing apatite with nitric acid, precipitating from a nitric acid extract a portion of strontium nitrate crystals and an insoluble residue in the form of a strontium concentrate, wherein the amount of the precipitated strontium nitrate is 20-60% of the amount contained in the nitric acid extract, freezing out calcium nitrate continuously in crystallisers with a self-contained heat exchanger, separating calcium nitrate tetrahydrate crystals by filtering, treating said crystals with ammonium nitrate and chalk, processing the mother solution into granular mineral fertiliser, wherein the strontium concentrate is added to the mother solution and taken for production of compound mineral fertilisers by granulation in a drum granulator-drier.

EFFECT: invention increases filtration output at the step of separating calcium nitrate from nitric acid solution when conducting the process in continuous mode in cascade of crystallisers with a self-contained heat exchanger.

3 cl, 5 ex