Electron probe microanalysis for revealing occurrence mode of scandium in Bayer red mud

Abstract

Red mud is a bauxite residue generated during the process of alumina production. In this research, the occurrence mode of scandium in the Bayer red mud was investigated mainly by electron probe microanalysis (EPMA). The Bayer red mud used in this work is composed of 21.47 wt% hematite, 12.13 wt% goethite, 8.86 wt% gibbsite, 5.02 wt% perovskite, 9.70 wt% quartz, 3.23 wt% anhydrite, 29.92 wt% Na2Al2Si5O14 and 9.67 wt% Al3Fe5O12. Besides, the scandium content in the Bayer red mud is 84.32 × 10−6, indicating that this Bayer red mud is an important scandium resource deserving exploitation. The EPMA results show that the scandium within the Bayer red mud is mainly occurring in the iron minerals of hematite and goethite with the isomorphism form, but its distribution is not homogeneous in these iron minerals with the Sc2O3 content between 330 × 10−6 and 2040 × 10−6. This study provides a theoretical base for the further experimental work on the scandium extraction from this Bayer red mud.