Mine Tailings Offer Few Opportunities for Critical Mineral Recovery

Interest in reprocessing discarded mine tailings for critical minerals has skyrocketed among policymakers. The prospect of “re-mining” has stimulated significant investment—even discouraging policies supportive of conventional mining under the impression that tailings alone could soon meet much of U.S. demand.

However, overcommitment risks material consequences for the future of U.S. critical mineral supply chains. Tailings recovery largely remains a hypothetical and poorly characterized prospect.

Policymakers must recognize mine tailings as a limited, supplemental source of critical minerals given low concentrations and the likely prohibitively high energy and chemical inputs needed to recover them, altogether offering low economic feasibility.

Some opportunities for tailings recovery do exist. Specifically, we find 16 element-deposit type combinations that could offer economically feasible prospects. For many other important critical mineral needs like antimony, chromium, lithium, manganese, and tin, we emphasize that mine tailings are not likely to yield any economic or significant recovery potential.
 

Key Findings

1. Only in rare circumstances will mine tailings offer opportunities to unlock new production of some critical minerals. Initiatives to recover critical minerals from mine tailings therefore should not substitute policy support for conventional mineral resources. The feasibility of reprocessing mine tailings for critical minerals varies element by element and site by site, but prospects in general are low. For the majority of critical minerals including antimony, chromium, lithium, manganese, and tin, potential production from mine tailings is likely zero.
2. Technological improvements in mineral recovery are unlikely to improve economic feasibility. Concentrations near or below crustal abundances for many critical minerals indicate that tailings are no more enriched than ordinary sediment, like garden soil. In principle, mine waste containing the same mineral content as ordinary crustal material may not even warrant consideration as a critical mineral resource.
3. It is unlikely that active mines are unknowingly throwing away critical minerals. Few deposit types contain accessory elements at grades comparable to primary ores. Those that do reflect well-established geological associations rather than novel enrichment. This indicates that economic feasibility, not undiscovered potential, poses the chief barrier to recovery at active mines.