Recovery of scandium from leaching solutions of tungsten residue using solvent extraction with Cyanex 572

Cyanex 572 has been first studied for the extraction of scandium from trivalent rare earths (REs). The extraction mechanism of Cyanex 572 for Sc(III) was proposed to be cation-exchange, and the stoichiometry of Cyanex 572 with Sc(III) was indicated to be close to 3:1. The extractabilities of Sc(III) from leaching solution of tungsten residue with Cyanex 572, P507, Cyanex 923 and TBP were compared at different concentrations, which indicated that Cyanex 572 was the best among them to extract scandium under the same conditions. The loading capacity of Cyanex 572 toward Sc(III) and stripping of loaded Sc(III) from the organic phase were also studied. By simple washing and stripping steps, the composition of scandium was increased more than eight hundred times.