METHOD OF OBTAINING AMMONIUM PHOSPHATES Russian patent published in 2009 - IPC C01B25/28 

FIELD: chemistry.

SUBSTANCE: invention relates to a method of obtaining ammonium phosphates, and more specifically to monoammonium phosphate and diammonium phosphate, based on decomposition of phosphate material with a mixture of sulphuric and phosphoric acid, obtaining wet-process phosphoric acid, and its subsequent processing into fertilisers. The method of obtaining ammonium phosphates involves decomposition of apatite concentrate with a mixture of sulphuric and phosphoric acid, separation of the obtained pulp by filtration with extraction of the produced phosphoric acid, washing the calcium sulphate residue with water, returning the wash water to the decomposition stage, clarifying the produced acid in a clarification tank, returning the thickened pulp after clarification to the decomposition stage of the phosphate material, ammoniation of the clarified acid, granulation and drying the product. In this method, before clarification, the produced phosphoric acid is held for 0.5-5.5 hours while cooling at a rate of 2-8°C/h and maintaining the ratio SO₃/P₂O₅ = 0.03-0.09 in the acid. The acid is clarified in the presence or absence of a flocculant.

EFFECT: method allows for stabilising quality of the product and increasing flexibility and stability of the technical flow diagram.

2 cl, 1 tbl, 1 ex