Recovery of strategically important critical minerals from mine tailings

Society’s hunger for commodities is leading to an increased consumption of minerals considered critical or strategic. A range of minerals containing elements such as lithium (Li), cobalt (Co), rare earth elements (REEs) are considered critical and more important for strategic uses than others. In this paper we describe these as strategically important critical minerals (SICMs). However, their continuous depletion from primary sources coupled with supply risks due to geopolitical issues and geographical segregation is a major concern. As a consequence, recovering these valuable elements from non-conventional sources such as abandoned mine tailings has recently gained increased worldwide attention. In some part this is due to the fact that the potentially recoverable amount of these elements in abandoned mine tailings is often higher than the concentration in some primary ores. A review of the scientific literature reveals the use of modern recovery techniques such as tailored made hydrometallurgical and bio-hydrometallurgical processes can lead to effective recovery of these elements from low grade sources such as mine tailings. However, there remain some technical, economic and environmental challenges associated with recovering SICMs from mine tailings. This review critically analyzes these challenges and discusses the opportunities available for recovering SICMs from abandoned mine tailings using conventional hydrometallurgical techniques as well as bioleaching methods, which can offer significant advantages in reprocessing. This paper also concludes by providing an outlook of an integrated approach to the reprocessing of mine tailings where the recovery of SICMs as well as clean water production should be the combined overall reprocessing and recovery goal, helping to realize the full economic potential of the tailings.