METHOD OF PRODUCING COMPOUND NITROGEN-PHOSPHORUS-SULPHATE FERTILISER FROM PHOSPHOGYPSUM (VERSIONS) Russian patent published in 2013 - IPC C05G1/00 C05G1/02 

FIELD: chemistry.

SUBSTANCE: group of inventions relates to chemical industry and specifically to processing phosphogypsum, a large-tonnage waste from phosphoric acid production, and can be used to produce compound mineral fertilisers. The first version of the invention involves mixing phosphogypsum and a by-product of production of carbamide, II degree distillation ammonium carbonate salts, which are first saturated via a carbonisation reaction; components are mixed in weight ratio of 1:0.705 at temperature of 55°C and pH of the solution is brought to 7. The second version of the invention involves mixing phosphogypsum and 80% ammonium nitrate solution before the evaporation step in weight ratio 1:1.176 at temperature not higher than 62°C and pH of the solution is brought to 7. The third version of the invention involves mixing phosphogypsum and a by-product of soda production, ammonium chloride solution in weight ratio 1:0.78 at temperature not higher than 62°C and pH of the solution is brought to 7. The fourth version of the invention involves mixing phosphogypsum, ammonium nitrate, phosphoric acid and ammonia water in weight ratio 1:0.588:0.180:0.128 at temperature of 60-80°C and pH of the solution is brought to 7.

EFFECT: use of any of the versions of the invention enables to obtain a nutrient-rich nitrogen-phosphorus-sulphate fertiliser from phosphogypsum, which is used as a ready liquid compound fertiliser or is processed to obtain granules or is fed into an additional mixer-reactor for mixing with other mineral fertilisers in order to increase the amount of nutrients.

8 cl, 5 ex