Solubility of YF3, CeF3, PrF3, NdF3, and DyF3 in solutions containing sulfuric and phosphoric acids

The solubility of YF 3 , CeF 3 , PrF 3 , NdF 3 , and DyF 3 in solutions containing 0–4.496% mol/L (0–35 wt %) of H 2 SO 4 and 0–27.6 g/L of H 3 PO 4 (0–20 g/L of P 2 O 5 ) at 20 °C was determined. Higher solubility in sulfuric acid solutions compared to that in hydrochloric and phosphoric acid solutions was attributed to the formation of fluorosulfate complexes M 2 (SO 4 )F 4 (M = Y, Ce, Pr, Nd, Dy). The effect of minor concentrations of the phosphate ions on the solubility of YF 3 , CeF 3 , PrF 3 , NdF 3 , and DyF 3 in sulfuric acid solutions and the effect of fluoride ions on the recovery of lanthanides during sulfuric acid leaching from the phosphohemihydrate were discussed.