METHOD OF PRODUCING AMMOPHOS Russian patent published in 2011 - IPC C01B25/28 C05B7/00 

FIELD: chemistry.

SUBSTANCE: invention relates to technology of producing mineral fertiliser. Low-grade phosphate raw material - Karatau phosphorites are decomposed by a mixture of phosphoric and nitric acid. Product acid is extracted from the reaction mass, concentrated, purified from impurities, ammoniated to obtain phosphate pulp, granulated and dried. In the concentrated acid, content of P₂O₅ is kept in the range of 39-44%, content of SO₃ - 2.5 - 4 %, residual content of solid impurities in the clarified concentrated acid is kept at 0.4-2 wt %, and molar ratio NH₃ : H₃PO₄ is kept in the range of 1.0-1.20. Control of the yield of the required type of ammophos on content of nutrients and ratio thereof is carried out by adding sulphuric acid to the process in amount of 90-225 kg mng per 1 t of P₂O₅ in the product. Sulphuric acid is added to the absorption system in amount of 50-75 kg mng per 1 t of P₂O₅, and the remaining amount is added to phosphoric acid before ammoniation.

EFFECT: method enables to obtain ammophos with high content of nutrients with improved quality of the product on chemical composition using low-grade phosphate raw material.

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