Remining for Renewable Energy Metals: A Review of Characterization Needs, Resource Estimates, and Potential Environmental Effects

Remining has been researched for decades, but its potential to supplement virgin extraction is currently unknown. This review addresses the remining of tailings/waste rock, coal residues, and byproduct and primary production materials for renewable energy metals (e.g., Co, Ni, REEs, Mn, Li). Geochemical characterization methods for estimating pollution potential must be supplemented with mineral liberation analysis and process testing to reliably estimate remining’s economic potential. National and regional remining characterization efforts currently exist in the U.S., Europe, Australia, and China but will take years to produce viable operations at scale. Tailings hold the most promise due to their large amounts worldwide and the fact that they are already extracted and pre-processed, which reduces energy and water use. Of the processing approaches examined, bioleaching appears to offer the most benefits with the fewest potential downsides. The advantages and challenges of the processing methods and remining sources are presented. Best remining practices are urgently needed to improve resource estimates and avoid impacts such as the tailings dam failures that occurred at remining operations in Romania and South Africa. Interest in remining is booming because it can increase domestic supply. If properly conducted, remining can also improve circularity and environmental conditions in areas affected by existing and legacy mining activity