| 摘要 |
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. |
