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.