Studies on Beneficiation and Leaching Characteristics of Rare Earth Elements in Indian Red Mud

Abstract

Bauxite residue (red mud) is a process reject composed of undissolved bauxite phases during digestion in the Bayer process. Rare earth elements present in the bauxite residue could be a potential resource for the extraction of REEs (Sc, La, Ce). It is difficult to recover REEs directly from red mud due to its low concentration and the presence of major minerals. Large amounts of iron in leach solution create problems for further recovery processes, as iron and scandium have some common chemical characteristics. It is, therefore, advisable to remove iron from the mud as much as possible through physical beneficiation. In the present study, physical beneficiation using hydrocyclone, characterization and acid leaching has been exploited. The beneficiation process enhanced the REEs from 200 to 240 mg/kg at a yield of 43%, with a subsequent reduction in the iron oxide content from 37.5 to 29.2%. Further, leaching efficiencies of REEs and impurity (Fe) co-extraction were studied before and after physical beneficiation. It is evident from the data obtained that upgrading minimizes iron co-extraction, which improves the leaching efficiency of REEs.