Abstract:

The past two decades have seen repeated increases in lithium demand as the popularization of consumer electronics and battery electric vehicles have intrinsically linked lithium to modernization efforts and low-carbon policy across the globe. Yet projections show conventional supply in high-grade hard rock and brine deposits is at risk of exhaustion within thirty years. Meeting continually increasing demand for lithium products will require valorization of new sources, including lower-grade (<1.10% Li₂O) hard rock spodumene deposits. Process transformations that adapt existing methods and build upon a thorough understanding of the behaviour of low-grade ores must be deployed to rapidly incorporate these deposits into the global reserve base. One such option is ore sorting, which has been widely adopted in other industries, including food, manufacturing, and recycling, and some segments of the mineral industry (notably diamonds). Aided by the incorporation of artificial intelligence tools, ore sorting technologies are rapidly evolving to overcome operational and cost constraints that have previously slowed their adoption and created gaps in literature regarding their application to specific ores. This study demonstrates the economic and environmental potential of ore sorting based on spodumene’s unique position in a sustainable economy and its mineral properties. A systematic review of literature, patents, and industry case studies is presented to validate the general benefits of ore sorting for spodumene-bearing ores, including quantification of the knock-on effects brought by minimizing gangue material carried through the flowsheet. While case studies employing colour sorting are reported, special consideration is given to the use of ultraviolet (UV) sorting. Spodumene’s emission of orange light under long-wave UV (365 nm) excitation can be employed to separate it from similarly-coloured gangue and co-occurring minerals known to affect flotation such as petalite. UV sorting is theorized to present a unique opportunity to address spodumene flotation challenges while also improving crushing efficiency. Beyond its focus on UV sorting, this study provides a current perspective on the challenges and opportunities of ore sorting for spodumene-bearing ores, from material handling adaptations to emissions reduction and operational cost savings, with applicability to other low-grade ore deposits.

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