Rare earth elements from coal and coal discard – A review

• Published in: Minerals engineering Vol. 173; p. 107187
• Main Authors: Eterigho-Ikelegbe, Orevaoghene, Harrar, Hamza, Bada, Samson
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.11.2021
• Subjects: Coal discard; Critical elements; Floatation; Leachability; Rare earth elements; Thermal treatment; Critical elements; Coal discard; Leachability; Floatation; Rare earth elements; Thermal treatment
• ISSN: 0892-6875; 1872-9444
• DOI: 10.1016/j.mineng.2021.107187

[Display omitted] •Coal and coal discard have been identified as a secondary source of REEs.•Review of physical beneficiation techniques of REEs from coal and coal discard.•Pre-treatment and hydrometallurgical processing of REEs from coal and coal discard are discussed.•Heap leaching of coal discard dumps to recover REEs.•Summary of REEs separation and/or recovery techniques. Given the geographical imbalance distribution and supply shortage of rare earth elements (REEs) in renewable energy processes, magnets, many high-tech technologies, etc., researchers are increasingly seeking to recover REEs from unconventional sources such as coal and coal by-products. This article provides a brief overview of the REEs mode of occurrence and its association in coal. It also discusses existing and potential beneficiation strategies for enriching REEs from coal and coal discard. Furthermore, the hydrometallurgical leaching of REEs from coal and coal discard is reviewed and a summary of recent outcomes on REEs recovery from the coal source is presented. The review validated the technical feasibility of the physical beneficiation of REE minerals from coal without a significant particle size reduction to produce high-grade REE feedstocks for leaching. Although ultrafine milling results in higher REE recovery values, additional milling costs may affect the viability of the process. Overall, the study confirms the abundance of REEs in coal, identifies gaps in knowledge, and highlighs future research that must be addressed to advance REEs recovery from these sources.