METHOD OF PRODUCING PHOSPHORIC ACID Russian patent published in 2009 - IPC C01B25/222 

FIELD: chemistry.

SUBSTANCE: method of producing phosphoric acid involves decomposition of phosphate material with stoichiometric ratio of sulphuric acid, which is pre-diluted to concentration ranging from 2 to 10% with circulating pulp, obtained at the decomposition stage, crystallisation of calcium sulphate, separation of precipitate through filtration, washing the precipitate and returning spillage solutions into the process. Sulphuric acid is diluted in a period of time which allows for formation at that stage of scaly and needle-like crystals of calcium sulphate in amount of not more than 10%, and the obtained mixture is used to treat phosphate material for 5 to 10 minutes, and the material is then taken to the decomposition stage.

EFFECT: method allows for stabilising the process of producing phosphoric acid, widening its use for different types of phosphate material and obtaining good technological parametres for the decomposition process, more specifically yield factor of P₂O₅ and efficiency of filtering calcium sulphate.

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