Highlights

• Mining engineer develops Metals Recovery Assessment (MRA) Protocol to evaluate critical mineral extraction from over 500,000 abandoned U.S. mine sites.
• Research demonstrates how legacy mine waste can be transformed from an environmental liability to a strategic mineral resource with careful assessment.
• Thesis provides a systematic approach to identifying viable mine sites for critical mineral recovery while addressing safety and environmental risks.

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Claire Rosaline Mbia Bounougou (opens in a new tab) proposes a new path for critical mineral recovery from U.S. mine waste. In a groundbreaking master’s thesis from Montana Technological University, mining engineer Mbia Bounougou introduces a pragmatic solution to one of America’s biggest overlooked mineral opportunities: abandoned mine waste. Her proposed Metals Recovery Assessment (MRA) Protocol provides a structured framework to evaluate the feasibility of extracting rare earth elements (REEs) and other critical minerals from legacy mine sites—before costly and often incomplete remediation efforts are initiated.

With more than 500,000 abandoned and inactive mine sites across the United States—and over 3,000 in Montana alone—this research couldn’t come at a more urgent time. As U.S.-China tensions threaten rare earth supply chains, Mbia’s thesis challenges policymakers and mining companies alike to rethink “waste” as a potentially untapped strategic resource.

Turning Liabilities into Assets

Mbia’s MRA protocol is a stepwise decision tool that assesses mine waste based on three primary filters: economic viability, safety, environmental risk, and regulatory permissibility. Her research shows that reprocessing waste not only offsets the ecological and financial burden of remediation but could also localize the domestic supply of REEs—vital for EVs, missiles, clean energy, and electronics.

Using two Montana sites as case studies—Berkeley Pit in Butte and the Empire Millsite near Marysville—Mbia demonstrates how the protocol can distinguish between promising reprocessing targets and those better suited for cleanup only.

• Berkeley Pit, a Superfund site flooded with acidic mine water, was identified as a viable candidate for critical mineral recovery. Already used for copper precipitation by Montana Resources, the pit contains high concentrations of aluminum, cobalt, neodymium, praseodymium, and zinc. Sherpa Costmine modeling projects feasible processing using existing infrastructure, suggesting this site could yield real economic returns while simultaneously reducing environmental liabilities.
• Empire Millsite, although rich in copper, zinc, and lead, fails to meet the safety threshold. Ranked 19th out of 276 in Montana’s abandoned mine hazard list, its high toxicity and complex remediation needs outweigh short-term economic benefits. Mbia’s recommendation: prioritize cleanup, not reprocessing—at least for now.

Limitations and Opportunities for Policy

While the protocol is robust and scalable, limitations exist. Mbia’s analysis relies on historical sampling data and modeled cost estimates that may not capture dynamic market prices or full site variability. Furthermore, site-specific permitting issues, liability risks, and community engagement challenges require careful case-by-case consideration.

Yet, the implications are clear: legacy mine waste is no longer just a cleanup cost—it’s a critical mineral reservoir. With federal investment under the Defense Production Act and growing bipartisan support for rare earth independence, Mbia’s MRA protocol provides a blueprint for evaluating sites nationwide.

Regardless of its eventual implementation, Rare Earth Exchanges (REEx) applauds the vision and rigor of Claire Mbia Bounougou’s thesis and the bold spirit it brings to the future of critical mineral recovery.

Strategic Takeaway

In the new industrial age, waste is no longer disposable—it very well might be strategic. Mbia’s thesis signals a powerful shift in mining thinking: from abandonment to assessment, from remediation to reclamation. The U.S. can’t afford to leave billions of dollars of REEs buried in its own backyard. It’s time to dig smarter.

Full thesis available at Montana Tech Digital Commons: https://digitalcommons.mtech.edu/grad_rsch/ (opens in a new tab).