Selectivity of scandium precipitation under conditions of crystallization of double sulfates of alkali metals or ammonium

The results of the scandium behavior in sulfate systems obtained during the processing of alumina production red mud were presented. It is shown that ammonium sulfoscandate NH4Sc(SO4)2 crystallizing under the chosen conditions has great prospects as a gravimetric form. The precipitation of NH4Sc(SO4)2 has a high selectivity in the separation of scandium from other components of solutions, as evidenced by the higher separation factors between scandium and impurities of the most common metals βSc/M (for example, for a pair with aluminum βSc/Al = 4280). Additionally, the possibility of selective precipitation of a less soluble double salt KSc(SO4)2 has been established. The product of recrystallization and calcination contains 99% Sc2O3.