Extraction and stripping of phosphoric acid from dissoluble phosphate or in hydrochloric acid

ABSTRACT

H3PO4, CaCl2, and some chlorides of impurities, derived from the phosphate ore, e.g. Al, Fe,... are formed when phosphate ore is dissolved in hydrochloric acid. Both iso-butanol and n-butanol are used to extract H3PO4 from the digestion medium, and H3PO4 is then stripped by water from the organic layer. Optimum conditions of extraction and stripping are studied. A stepwise process to improve the extraction and recovery is also applied. The chemical analysis of the stripped H3PO4 points out that the iron content is reduced to 0.79% and 0.13% and the fluoride content reduced to 3.8%, 4.2% of the original values of iso-butanol and n-butanol, respectively. The results are discussed in comparison with the literature data. They indicated that, the efficiency of extraction and stripping depends on the nature of the solvent, the ratio of the organic to the aqueous layers and the number of steps followed in the process