An experimental study on the separation of lanthanides from phosphate ore by organic and inorganic acids

In this study, the separation of Lanthanides from phosphate ore using
C2H2O4, C4H6O6, C3H6O3, H2SO4, and HCl was investigated. The ore was
characterized before and after leaching processes by XRF, SEM, XRD, and
IR. The different parameters affect the leaching rate such as leaching
time, acid concentration, liquid/solid ratios, temperature, and leaching
kinetics were studied. The optimal leaching conditions were determined as
0.4M H2C2O4, 2.5M C4H6O6, 1.8M C3H6O3, 2.0M H2SO4, and 3.0M HCl,
 with a L/S ratio of 6/1 H2C2O4, 8/1 for both C4H6O6 and C3H6O3,
5/1 for both H2SO4 and HCl at 30 °C, agitation rate ≈ 350 rpm and particle
size ≈ 144.8 μm. Under these optimum conditions, (%R) were 42.8% (for
C2H2O4), 93.2% (for C4H6O6), 89.1% (for C3H6O3), 89.3% (for H2SO4), and
94.6% (for HCl). SEM and FTIR characterization for the residue was
investigated. Experimental data reveals that, the leaching processes are
fitted by chemical reaction models for C2H2O4 and C3H6O3, and by
diffusion-reaction model for C4H6O6, H2SO4, and HCl. The activation
energies for these models were estimated to be 43.3, 30.33, 45.8, 31.3,
and 38.6 kJ/mol for C2H2O4, C4H6O6, C3H6O3, H2SO4 and HCl, respectively.
All data were confirmed and explained by XRD, FTIR and SEM studies.