Author:

Keywords:

rare earths, bauxite residue, red mud

Abstract:

Liquid-solid extraction is often required in hydrometallurgy for the recovery of trace amounts of valuable metals from leaching solutions. Supported ionic liquid phases (SILPs) are a new class of adsorbents which involve covalently attached ionic liquid fragments on the surface of a solid material. In this work, we examined the recovery and separation of rare-earth elements (REEs) from leachate of high-pressure HCl leaching of bauxite residue (BR) slag in a column setup by a specially designed SILP with high affinity for REEs. The SILP showed higher adsorption affinity for the selected REEs [(Sc(III), Y(III), Nd(III), Dy(III)] than for the base elements [Ca(II), Al(III), Fe(III), Si(IV), Ti(IV)] of BR. Purification of the REEs from the coadsorbed base elements was achieved by a three-step elution with dilute H3PO4 and HNO3. Moreover, Sc(III) was completely separated from Y(III) and other REEs. Nd(III) was enriched over Dy(III) in the collected fractions. This indicates good separations between Sc(III), light REEs, heavy REEs and base metals.