Refining Technology of Scandium Concentrate Obtained from Bauxite Residue

Global production of commercial scandium oxide currently produces only ~15–20 tonne per year. It is produced from tailings and streams of titanium and uranium industries and complies with high quality standards with Sc₂O₃ content ≥99.9 mass%. UC RUSAL has developed a technology for Sc₂O₃ extraction from bauxite residue that can provide for a substantial increase of Sc₂O₃ output making it a commodity product with low production cost. For the scandium concentrate obtained at RUSAL pilot plant (Sc₂O₃ content up to 52%) the purification technology was developed combining both well-known and novel methods like double hydrolysis and scandium precipitation in the form of complex compounds, i.e. double sulphate of scandium and sodium Na₃Sc(SO₄)₃5H₂O. The process assures efficient removal of impurities (incl. Zr, Ti, Hf, Th, REM), low operation costs, minimal secondary losses of scandium, low amount of hazardous wastes and was successfully tested at lab and pilot plant scales.