Recovery of Metal Values from Bauxite Residue/Red Mud: A Review

Abstract

Red mud/bauxite residue is an industrial waste product of Bayer's process and because of its alkalinity poses a significant environmental problem. However, it is a potential source from which valuable metals such as iron, alumina, titanium, caustic soda, gallium and rare earth elements (REEs) especially scandium can be extracted. The aim of this article is to systematically review, research on metal and rare earth extraction from red mud from the year 2000 to 2024. Extraction methods by hydrometallurgy, pyrometallurgy and bioleaching have been reviewed in the paper. It is seen that in any extraction process, the different operational parameters, such as reagent concentrations, temperature and pH influence the extraction efficiency of metals and rare earths. The recovery challenges and limitations presented in this document highlights, above all, the underlying complexities. The paper also discusses the problems associated with the recovery processes, particularly because of the complex composition of the red mud.