METHOD OF PRODUCING GRANULAR AMMONIUM PHOSPHATES Russian patent published in 2012 - IPC C01B25/28 

FIELD: chemistry.

SUBSTANCE: invention relates to production of granular fertiliser ammonium phosphates can be used in chemical industry and agriculture. Phosphoric acid is neutralised with ammonia to obtain ammonium phosphate pulp, followed by granulation and drying the product. Granulation is carried out in two steps. At the first step, a first portion of pulp is layered onto a fine fraction of the product with moisture content of the mixture equal to 4-8%. At the second step, a second portion of pulp with moisture content 15-20% is sprayed onto the obtained mixture. When producing mono-ammonium phosphate, consumption of pulp per P₂O₅ during the steps is in the ratio 1:0.3-0.5, molar ratio NH₃:H₃PO₄ at the layering step is kept equal to 1.0-1.1 and equal to 1.2-1.3 at the spraying step. When producing diammonium phosphate, consumption of pulp per P₂O₅ during the steps is in the ratio 1:1-0.5, molar ratio NH₃:H₃PO₄ at the layering step is kept equal to 1.8-1.85 and equal to 1.6-1.7 at the spraying step. The first granulation step is carried out in smooth-walled revolving drums and the second step is carried out in apparatus with a suspended layer.

EFFECT: method enables to obtain mono-ammonium phosphate and diammonium phosphate with transition of production of one product to another with maximum efficiency.

4 cl, 2 tbl, 2 ex