METHOD OF PREPARING DIAMMONIUM PHOSPHATE Russian patent published in 2001 - IPC

FIELD: agriculture. SUBSTANCE: method comprises stage by stage neutralization of ammonia with phosphoric and sulfuric acid first to NH₃:H₃PO₄ molar ratio of 1.4 and then to 1.75, granulation, drying of products and purification of flue gases; in this case, sulfur cake with particle size of 0.15-0.25 mm is added in neutralization stage in amount of 0.5-3 wt % of weight of the resulting final product. Sulfur cake is added either into phosphoric acid or to any stage of neutralization. The resulting fertilizer comprises free sulfur that improves granulation conditions which promote increased strength of the resulting granules. EFFECT: more efficient preparation method. 2 cl