Bioleaching of rare earth elements from ores and waste materials: Current status, economic viability and future prospects.

Rare earth elements (REEs) are critical components of numerous products widely used in many areas, and the demand for REEs is increasing dramatically in recent years. Physical-chemical leaching is commonly adopted for the recovery of REEs from ores and solid wastes, but concerns over the generation of hazards, operation safety, and environmental pollution have urged the transition to greener and more sustainable leaching methods. Bioleaching is considered an excellent alternative for the recovery of REEs. This review provided an overview on the REEs recovery from primary and secondary resources via different bioleaching strategies. The techno-economics of bioleaching for REEs recovery were highlighted, and key factors affecting the economic viability of bioleaching were identified. Finally, strategies including the utilization of low-cost substrates as feedstocks, non-sterile bioleaching, recycling and reutilization of biolixiviants, and development of robust bioleaching strains were proposed to improve the economic competitiveness of bioleaching. It is expected that this review could serve as a useful guideline on the design of more economically competitive bioleaching processes for the recovery REEs from different resources.