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US 4,769,226 AGranted
Purification of wet-process phosphoric acid
AssigneeRhone-Poulenc Chimie de Base
InventorsLouis Winand, Dominique Perron
Life of this patent
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Abstract
Crude wet-process phosphoric acid is purified by treating a dilute such acid with a molybdenum value reducing amount of hydrogen sulfide or of a sulfide which in situ forms hydrogen sulfide, to afford a purified acid adopted for the production of food grade phosphoric acid, and which has a content in heavy metal and molybdenum values of less than 10 ppm.
Claims10
A process for purifying a crude wet-process phosphoric acid comprising:
- (a) providing a dilute wet-process phosphoric acid having a concentration in P.sub.2 O.sub.5 about 40% or less and a molybdenum content which would adversely detract from food and beverage products;
- (b) countercurrently contacting a stream of said dilute wet-process phosphoric acid with hydrogen sulfide or a sulfide which forms hydrogen sulfide upon contact with said dilute wet-process phosphoric acid to reduce said mulybdenum content to about 10 ppm/P.sub.2 O.sub.5 or less;
- and
- (c) separating and recovering said food-grade product phosphoric acid.
1 more element
Dependencies are inferred from the claim text.