DIAMMONIUM PHOSPHATE PRODUCTION PROCESS Russian patent published in 2007 - IPC C05B7/00 C01B25/28 

FIELD: mineral fertilizers.

SUBSTANCE: process of production of diammonium phosphate useful as mineral fertilizer for various types of soils comprises neutralization of phosphoric acid solution with ammonia first to molar ratio 1.4 followed by additional ammonization to molar ratio 1.8, granulation, drying of product, and two-step absorption of emission gases: first with phosphoric acid and then with first-step effluents. Phosphoric acid used for the first-step absorption is supplied separately in concentrated and non-concentrated forms. Concentrated phosphoric acid is introduced by two flows. To the first-step absorption effluent first all non-concentrated acid is added, then 15-35% of the total amount of concentrated acid and second-step effluent having density 1.01-1.3 g/cm³, after which resulting mixture is supplemented by the rest of concentrated acid. Proportions of concentrated acid, non-concentrated acid, and second-step effluent are maintained within limits providing density of the mixture not exceeding 1.55 g/cm³.

EFFECT: enhanced efficiency of process using concentrated and non-concentrated extraction phosphoric acid obtained under semihydrate conditions.

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