Modern technologies depend on a steady supply of minerals such as lithium, copper, and nickel. From clean energy systems to communications infrastructure, the materials that power today's innovations often begin in mines. But expanding mineral production brings challenges that extend beyond extraction, including water use, environmental impacts, and relationships with local communities.

Those interconnected challenges have become a focus of Professor Jennifer Dunn's research. Dunn, a professor of chemical and biological engineering at Northwestern Engineering, studies the environmental and economic dimensions of energy and manufacturing material supply chains. This work increasingly intersects with growing demand for critical minerals used in batteries, electronics, and other advanced technologies.

She addressed these issues with McCormick School of Engineering colleagues Giuseppe Buscarnera, Jean-Francois Gaillard, Matthew Grayson, and Ashty Karim, with an international team of researchers from Australia and Chile in the paper “Global, Interdisciplinary Research to Guide a Secure and Sustainable Expansion of Mineral Supply Chains.” The paper was published earlier this month in Environmental Science & Technology Letters. 

Three takeaways from the team's work are below.

Mining challenges require interdisciplinary research

Mining projects involve far more than the extraction of minerals. Decisions about production, waste management, water use, and land reclamation can have environmental, economic, and social consequences.

To better understand those interactions, the researchers examined mining challenges through multiple disciplines: engineering, environmental science, social science, governance, sensing technologies, and AI.

The need for that breadth became apparent when the researchers explored ways to recover valuable minerals from mining wastewater. Doing that successfully could improve water quality while recovering critical minerals from waste streams, but evaluating the benefits and tradeoffs requires expertise that extends beyond engineering.

The team also examined whether mining byproducts such as tailings, waste rock, and smelting slag, could be repurposed as construction materials could be repurposed as construction materials. Doing so requires understanding not only material performance but also environmental chemistry and the potential consequences of introducing those materials into new applications.

“If we stay in our silos, we can struggle to find solutions, but when we work across institution types, such as company, academia, government, and across disciplines, we can find new, viable solutions,” Dunn said.

Buscarnera said researchers from across disciplines also need to collaborate to rethink how they evaluate mine waste itself.

“I was also interested in the need to study mine waste as a chemically active, human-made material whose properties depend strongly on the specific mining and processing history of each site, a combination of factors that is likely to demand a complete rethinking of multiple components of the geotechnical characterization workflow,” said Buscarnera, a professor of civil and environmental engineering. His research focuses on the mechanics and behavior of geomaterials, including unsaturated soils and porous rocks, material stability, fracture and crushing in granular materials, and the analysis and forecasting of natural hazards such as landslides and slope failures.

Other countries offer time-tested knowledge

Australia and Chile have long-established mining sectors and extensive experience managing the opportunities and challenges associated with mineral production.

Those countries have spent decades expanding mining operations, testing technologies, and working with communities affected by mining activity. Their experiences provided additional perspectives during discussions about future research priorities.

Chile has confronted issues related to mine reclamation and the long-term management of abandoned mines. Dunn noted that when mining companies walk away from sites, governments can be left responsible for managing the consequences. Those experiences have led policymakers to explore ways to ensure resources are available for reclamation after mines close.

Mining also represents a significantly larger share of the Chilean economy than it does in the United States, giving the country extensive experience balancing mineral production, environmental stewardship, and community concerns.

“We have a lot to learn from countries that have more experience in the last century with mining, expanding mining, trying out new technologies, and working with communities,” Dunn said.

Every change can have ripple effects

Changes intended to improve one aspect of mining operations can affect other parts of the system in unexpected ways.

Dunn pointed to efforts to recover products from mining waste as one example.  Repurposing mining waste for use in construction can reduce risks associated with storing mining waste, but also adds processing steps that consume energy.   In addition, valuable minerals can be recovered from mining wastewater and recovering those materials could reduce pollution while producing additional value.  Adding technologies to mines to recover minerals from wastes, however, could also increase energy consumption.

The researchers said those kinds of tradeoffs can be difficult to anticipate without expertise from multiple fields. A change intended to improve environmental performance, for example, could create new operational challenges or prompt concerns from nearby communities.

“Without all the disciplines engaged, you're going to miss the domino effect,” Dunn said. “One of those dominoes could be that potentially avoidable environmental challenges cause community concerns that slow or cancel projects that would reduce supply chain risks.”

Those kinds of interactions are central to Buscarnera's work on the mechanics of mine waste and other granular materials.

“Geotechnical engineering helps translate laboratory recovery technologies into safe, large-scale operations by evaluating drainage, settlement, strength, erosion, and failure risk,” he said.