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US 3,993,733 AGranted
Food grade alkali metal phosphates from wet process H.sub.3 PO.sub.4
AssigneeStauffer Chemical Company
InventorMazin R. Irani
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Abstract
A process for converting wet process phosphoric acid to food grade alkali metal phosphates by a sequence of steps including extraction of the wet process acid, partial neutralization, dilution with water, contact with activated carbon, neutralization to a pH of from about 5 to about 9, contact with activated carbon, contact with insoluble alkaline earth metal phosphate salts and recovery of the dissolved alkali metal phosphate product in solution.
Claims21
A process for the preparation of high purity alkali phosphate solutions from wet process phosphoric acid which comprises:
- a. contacting a wet process phosphoric acid with an organic solvent capable of extracting said acid to form a solvent-acid phase, and a raffinate phase;
- b. partially neutralizing the solvent-acid phase by contacting with a concentrated alkali in amounts sufficient to precipitate impurities, and separating said impurities;
- c. diluting said partially neutralized solvent-acid phase with water to strip a dilute aqueous phosphoric acid phase from said solvent phase, and separating said phosphoric acid phase;
- d. neutralizing the aqueous phosphoric acid to a pH of between about 5 and about 9, thereby forming a solution of soluble salts of phosphoric acid and a precipitate, and separating said precipitate;
- e. contacting said solution of soluble salts with activated carbon;
- f. contacting said solution of soluble salts with an insoluble alkaline earth metal phosphate salt and separating said insoluble salt to thereby produce a high purity alkali phosphate solution.
3 more elements
Dependencies are inferred from the claim text.