Characterization and Leaching Kinetics of Rare Earth Elements from Phosphogypsum in Hydrochloric Acid

The characterization and leaching mechanism of REEs from phosphogypsum (PG) in HCl was studied in-depth. contained the PG were 208 ppm, which Y, La, Ce, Nd four most abundant elements. modes occurrence rare earth elements (REEs) quantified using sequential chemical extraction (SCE) method. Among five REE species, metal oxide form accounted for largest proportion, followed by residual, organic matter, ion-exchangeable fractions, bound to carbonates least. From comparison distributions calcium different states, it can be determined that mainly present residue state (existed gypsum lattice) (easily leached). results show suitable conditions acid concentration 1.65 mol/L, S/L ratio 1/10, reaction temperature 60 °C. At condition, maximum efficiency ∑REE 65.6%, yttrium rate highest reached 73.8%. Importantly, A new kinetic equation based on cylindrical shrinking core model (SCM) deduced could well describe process PG. apparent activation energy 20.65 kJ·mol−1.