A Review on Rare Earth Elements (REEs) in Mine Tailings: Mineral Hosts, Extraction Chemistry, and Recovery Potential

Abstract

The rare earth elements (REEs) are the essential elements of modern technologies such as renewable energy systems, electric vehicles, and sophisticated electronics. In spite of the name, REEs are quite common in the crust of the Earth, but they are seldom found in economically viable concentrations. Mine tailings (remains of mining phosphate, iron, carbonatite and rare metals) in Africa, include huge amounts of REE-bearing minerals, monazite, bastnasite, xenotime and allanite. These materials constitute a relatively unexploited secondary resource that would fit the goal of sustainable mining and the circular economy. This review paper discusses the phenomenon, mineral associations, and the mining chemistry of REEs in African mine tailings, with particular focus given to selective methods of leaching appropriate to local conditions. The paper identifies the geological provinces with the greatest amount of REE-enriched residues, an analysis of the effectiveness of different leaching reagents, and environmental and economic considerations. Results suggest that African tailings may be a valuable alternate REE source with enhanced hydrometallurgical facilities, thorium handling techniques, and interregional collaboration. Through valorization of current mine wastes, Africa will gain by cutting environmental liabilities and also bolster its place in the global supply chain of REE.

Keywords: Rare earth elements, Mine tailings in Africa, Selective leaching, Hydrometallurgy, Sustainability, The circular economy.