METHOD OF PRODUCING TRISODIUM PHOSPHATE Russian patent published in 2009 - IPC C01B25/30 

FIELD: chemistry.

SUBSTANCE: invention relates to the technology of producing inorganic phosphorous compounds, and more specifically to a method of producing trisodium phosphate (TSP) from wet-process phosphoric acid. The method of producing trisodium phosphate involves neutralisation of phosphoric acid with soda ash, separation of the solution and residue of trace constituents, neutralisation of separated solution with sodium hydroxide at pH=11.5 to 12.0, obtaining a solution of trisodium phosphate, its subsequent cooling, crystallisation of the final product and separation of the crystallisation mother solution, in which neutralisation of phosphoric acid with soda ash is done at the beginning before formation of a solution containing 12 to 14% monosodium phosphate and 27 to 30% disodium phosphate at temperature of 55 to 62°C, and soda ash is then added until obtaining a disodium phosphate solution with concentration 40 to 42%. Introduction of crystallisation mother solution during neutralisation of the separated solution with sodium hydroxide is preferred.

EFFECT: method increases degree of extraction of P₂O₅, improves quality of product and increases technological effectiveness of the process by increasing efficiency of the filtration stage.

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