Leaching of Light Rare Earth Elements from Sichuan Bastnaesite: A Facile Process to Leach Trivalent Rare Earth Elements Selectively from Tetravalent Cerium

The effects of the nitric acid concentration, leaching time, leaching temperature, and solid-to-liquid ratio on leaching efficiency were examined. From those results, a facile process for the selective leaching of trivalent rare earth elements (RE(III)) from tetravalent cerium (Ce(IV)) was proposed. The roasted bastnaesite was used to leach 34.87% of RE(III) and 2.15% of Ce(IV) at 60 degrees C for 0.5 h with an acid concentration of 0.5 mol/L. This selective leaching process can be described by the shrinking-core model that follows the kinetic model 1 - 2/3 alpha - (1 - alpha)(2/3). Subsequently, the leached slag was hydrothermally treated and followed by thorough leaching with 4.0-mol/L nitric acid. Furthermore, the specific surface area of the final leached slag is 57.7 m(2)/g, which is approximately 650 times higher than that of raw ore. Finally, selective leaching of RE(III) (>90%) was achieved without using an organic solvent for extraction, whereas lower value Ce(IV) was presented in the leached slag (>92%).