Studies on the dissolution of phosphate ore in mineral acids

The dissolution of Abou-Tartor phosphate ore in sulphuric acid, phosphoric-sulphuric acid mixture and hydrochloric acid was studied. The effects of time, temperature, acid/ore ratio and shaking were investigated. The results indicated that the dissolution of the ore in sulphuric acid was rather difficult; but the dissolution in H3PO4- H2SO4 mixture [76.1: 54.5 g] gave good result from 100 g of the ore at an acid/ore ratio of 1.4 after 30 min, at 70 degree and a shaking rate of 100-200 rhm. The optimum condition of the dissolution in HCl/ore ratio of 27: 1 was 80 min, at 25 degree and a rate of shaking of 120 rhm. The obtained results showed that the dissolution of Abou- Tartor phosphate ore in HCl is more preferable than other mineral. acids

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

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