Hydrometallurgical Extraction of Scandium from Bauxite Residue based on Sulfuric Acid Process

In this study, scandium extraction from Bauxite residue based on sulfuric acid leaching is presented. Scandium dissolves at elevated temperatures under high acid concentration reaching recovery yields up to 90%. It was found that increasing acid concentration in the range of 3-4 mol/L at elevated temperature, increase Sc recovery whereas simultaneously overcoming silica gel issues that occur from Si dissolution obtaining fast filtration rates while working at high pulp densities. Upon H2SO4 leaching, the main elements present in Bauxite residue such as Fe, Ti and Al co-dissolve, resulting to a pregnant solution of several g/L and Sc concentration in the range of 10-20 mg/L. Neutralisation of leachate for Iron precipitation as well as direct solvent extraction were applied to successfully remove iron or directly extract Sc from solution