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.

Abstract: Crude wet-process phosphoric acid prepared by mineral acid acidulation of uncalcined phosphate rock and containing contaminating amounts of organic impurities is purified and decolorized into an essentially colorless food-grade phosphoric acid, by (i) preliminarily decolorizing such crude acid, (ii) liquid-liquid extracting said predecolorized acid with an essentially water-insoluble organic extractant, (iii) back-extracting the extracted phosphoric acid with an aqueous phase, (iv) concentrating the back-extracted aqueous phosphoric acid solution at elevated, coloration-developing temperatures, and (v) then subjecting the concentrated solution which results to a final decolorization, to afford a purified, essentially colorless phosphoric acid solution.

Abstract: A continuous process for removing sulfate ions from a substantially water-insoluble organic phase containing phosphoric acid and sulfuric acid is described. The organic phase is treated countercurrently in a first zone with an aqueous solution originating in a third contact zone, the organic phase issuing from the first zone is treated in a second zone with an aqueous solution containing barium ions, then the resultant organic phase is treated in a third zone with water. The aqueous phase exiting from the second zone is separated from the BaSO.sub.4 precipitate, recharged with barium and recycled into the second contact zone. The phosphoric acid thus obtained is suitable for use in human foods and beverages.