Phosphoric acid purification - by solvent extraction - with a solvent capable of absorbing at least 9% water

摘要

Pure phosphates suitable for use in food industry are prepd. from impure H3PO4 by (1) intimately mixing crude H3PO4 with an organic solvent or mixture of solvents capable of absorbing >=9% water (2) separating the phases to give a phase (A) contng. solvent, water and H3PO4, and a phase (B) contng. impurities (3) adding to phase (A) one or more basic cpds. in amount corresponding to 1-40 wt.% (caculated as oxide) of the quantity necessary for the prepn. of residual mineral impurities and a phase (D) contng. solvent, water and H3PO4; (5) phase (D) is reacted with further base(s) to form the mono-, di- or tri-orthophosphate; (6) the aqueous phase (E) contng. the product is separated from the solvent phase.