7. Purification of scandium halide (ScCl3)

Scandium halide is obtained by attacking scandine with HCl. Its purification can be carried out :

• by fractional vapo-metallurgy of scandium chloride at around 970°C before sublimation, and thorium and rare earth chlorides at higher temperatures;

• by exchange resins or solvents, applied to the aqueous solution of ScCl ₃ , depending on scandium concentrations. For low concentrations, scandium is extracted by column resins such as Dowex 50 W, a polystyrene resin with an ionic-SO ₃ group and usable at any pH (between 0 and 14); citric acid or an aminoacetic acid is employed as the elution solution. For Sc contents above a few g/L, ether-type solvents are effective after prior treatment of the hydrochloric solution, to be purified with...