Process Mineralogy Study on Scandium of a Rare Earth Ore Deposit Tailings in Inner Mongolia

Combined with electron probe element surface scanning distribution, multiple technics including SEM energy dispersive spectrometer, mineral liberation analyser (MLA), electron probe micro-analyzer (EPMA) were used to study the mineral composition, dissemination characteristics, dissemination size, liberation degree and occurrence of scandium bearing minerals in a rare earth ore deposit tailings from Inner Mongolia. The results showed that the scandium content in the tailings was 311×10^-6. The major scandium bearing minerals were magnesio-arfvedsonite, aegirine and aegirine-augite, and subordinately ilmenorutile and columbite with only a very small amount of scandium independent mineral thortveitite. The scandium mainly occurs in the form of isomorphism in scandium bearing minerals. The main grain size range of magnesio-arfvedsonite, aegirine and aegirine-augite was between 0.01~0.16 mm, with high liberation degree of 80%, which was good for sorting. The grain size of ilmenorutile and columbite was fine, mainly in the range of -0.005~0.08 mm, with very low degree of dissociation around 20%~30%, which was extremely disadvantageous to the separation. The theoretical grade and recovery of arfvedsonite, aegirine and aegirine-augite were 704×10^-6 and 81%, respectively, and the theoretical grade and recovery of ilmenorutile and columbite were 5 008×10^-6 and 10%, respectively. Most of the scandium in tailings could be recovered synthetically by sorting arfvedsonite, aegirine, aegirine-augite and niobium minerals using magnetic separation preliminary enrichment firstly, and then extracting scandium from rough concentrate using hydrometallurgical means of acid leaching-roasting-leaching.