METHOD OF PRODUCING NITROGEN-PHOSPHORUS FERTILISER Russian patent published in 2011 - IPC C05G1/06 

FIELD: chemistry.

SUBSTANCE: invention relates to production of nitrogen-phosphorus fertilisers of the ammonium-phosphate-sulphate type. The method involves preliminary neutralisation of phosphoric acid with ammonia, followed by mixing ammonium phosphate pulp with sulphuric acid to obtain ammonium phosphate and ammonium sulphate pulp, granulating the latter and drying. Preliminary neutralisation of concentrated phosphoric acid with ammonia is carried out in a reactor-mixer. Subsequent mixing of ammonium phosphate pulp with sulphuric acid is carried out in a pipe reactor while simultaneously feeding ammonia into the reactor. Wet-process phosphoric acid with P₂O₅ content of 35-40% is used. Ammonium phosphate, sulphuric acid and ammonia are fed into the pipe reactor in such a way that the effect of sulphuric acid on the walls of the reactor is minimised. Ammonium phosphate and ammonium sulphate pulp is sprayed onto a recycle layer mixed with phosphogypsum in an ammoniator-granulator where liquid ammonia is fed until complete neutralisation of the pulp. Drying is carried out in a drum drier.

EFFECT: invention increases efficiency of the process of producing fertiliser, increases content of nutrients in the fertiliser, enables utilisation of heat of neutralisation of sulphuric acid with ammonia to evaporate moisture of the pulp, and minimises the aggressive effect of sulphuric acid on equipment.

4 cl, 1 tbl, 1 ex, 1 dwg