2026 Lin Controlled HCl Leaching for Phosphorus and REE Recovery

Rare earth elements (REEs), as significant associated resources in sedimentary phosphate deposits, are commonly processed via the conventional hydrochloric acid wet-process phosphoric acid route (IMI process). In this study, a dolomitic rare earth-bearing phosphate concentrate from the Zhijin region of Guizhou Province was selected for research. A stepwise phosphorus-prioritized leaching process was proposed, whereby precise regulation of hydrochloric acid dosage and reaction temperature enabled the preferential leaching of phosphorus (91.27%) and the directed enrichment of rare earth elements in the leaching residue (enrichment ratio of 4.7), achieving efficient phosphorus–rare earth separation at source. Subsequently, process mineralogical analyses revealed that rare earth elements primarily occur in fluorapatite through isomorphic substitution. Following preferential phosphorus leaching, residual calcium combines with fluorine to form CaF2, while rare earth elements concentrate within the leaching residue. Finally, kinetic investigations and response surface analyses demonstrated that the preferential phosphorus leaching process is governed by diffusion through the solid product layer.