Mining for the future

Coal slurry. Fly ash. Incinerated garbage. Grass. What if these and other materials could be turned into electric cars, solar panels, and smartphones?

Researchers in Virginia Tech's Department of Mining and Minerals Engineering are working to give companies and innovators stable, sustainable, domestic supplies of the critical minerals needed for a thriving economy and a green energy future.

The U.S. Geological Survey maintains a list of several dozen critical minerals — many of which must be mined — that are important for society to advance. Lithium and cobalt, for example, are essential to the production of electric vehicles, which are a major part of the American climate protection strategy.

Environmentalists typically take a dim view of mining, given historical damage from the industry. But electric car manufacturers such as Tesla have made it clear that without reliable mined resources, production will remain limited and such vehicles will remain expensive. That challenges mining engineers to develop environmentally and socially responsible ways to harvest these critical minerals — a challenge perfectly suited to a land-grant research university.

“I think we understand our dependence because of the push toward electric vehicles, wind turbines, and solar panels — all the technologies that are moving us toward decarbonization of our society and our country,” said Richard Bishop, professor of practice in mining engineering. “And all of those technologies require critical minerals.”

Demand for these minerals, including cobalt, nickel, and so-called rare earth elements, is projected to rise by up to 600 percent in the coming decades, and the amount of lithium and graphite needed to produce electric car batteries may climb by about 4,000 percent, according to the White House. But because these minerals are often mined outside the U.S., supply chain bottlenecks and tense diplomatic relations can limit our nation's access to them. 

“Critical minerals are essential for societal advancement,” said mining engineering Associate Professor Aaron Noble. “They are also considered critical because they are subject to heightened risk for supply chain manipulation or disruption. Some materials may only be produced in a single country, perhaps one with poor geopolitical ties to the U.S. This vulnerability can lead to supply disruption.”

To help solve the supply problem, Bishop, a researcher in the Virginia Center for Coal and Energy Research and who has industry experience in mining finance, is leading a regional project to help build a new Appalachian economy around critical minerals extraction and processing. The Evolve Central Appalachia (Evolve CAPP) project is developing and implementing strategies that enable this region hard-hit by the decline of the traditional coal industry to find ways to spur new economic growth by producing rare earth elements, other critical minerals, and high-value, nonfuel, carbon-based products.

“We put together a consortium of academics from the University of Kentucky, West Virginia University, Virginia Tech, but also industry and government agencies,” Bishop said. “We have a team of about 40 people right now looking at critical minerals within this region.”

The team’s work “encompasses the geology aspects of critical minerals, as well as economic development and social aspects like environmental justice. We’re looking at what infrastructure that we have right now and infrastructure that we may need to build to create jobs in extraction and processing of critical minerals,” Bishop said.

Meanwhile, Assistant Professor Wencai Zhang and Noble are working to develop innovative technologies to extract and refine critical minerals and rare earth elements from waste streams and other nontraditional sources — often with industry partners.

At the off-campus mining engineering lab in Blacksburg, Zhang’s graduate students are growing grass from hardware store seed and potting soil to help feed the nation’s hunger for rare earth elements — a collection of lesser-known materials needed to produce high-tech devices and, most critically, the magnets needed to power electric vehicles.

“If we want to produce electric vehicles, we need motors, right? And to make those high-efficiency motors, we need to produce permanent magnets,” Zhang said. “So if we want to produce permanent magnets, we need a lot of rare earths, especially neodymium and praseodymium.”

But there are challenges to meeting that demand. Rare earth elements are in some ways misnamed, Zhang said. These molecules are abundant in the environment, from backyard soils to kitchen trash. But unlike other high-value minerals, they rarely coalesce in deposits big enough to harvest economically. Only one such mine exists in the United States. Mountain Pass Mine, owned by MP Materials, is a rare earth elements, open-pit mine located in California’s Clark Mountain Range. In 2020, it fulfilled about 16 percent of the world's rare earth demand.

The search is on for other such domestic deposits, but Zhang and his team are looking closely at secondary sources and working to make them economically viable. Zhang focuses mostly on innovations in chemical separation and has developed government and industry partnerships to do so.

The U.S. Department of Energy recently announced a $500,000 project with Zhang and two companies, Australia-based American Rare Earths Limited and Phinix LLC, headquartered in Missouri. The group will partner on extraction and separation-focused processing technology studies. It also will promote the College of Engineering’s commitment to meet critical global needs through high-impact research. 

“This project represents a fantastic opportunity to showcase our new state-of-the-art minerals and materials processing laboratory capabilities that we renovated and expanded over the past year,” Zhang said. “We now have one of the finest research facilities in the world that is focused on rare earths processing to facilitate the global transition to the reduced carbon, new energy future.”

Noble works in both areas of critical minerals — new source identification and developing processes to separate the raw materials from waste. Noble, University Distinguished Professor Roe-Hoan Yoon, and other faculty in the department's Center for Advanced Separation Technologies  recently initiated $1.3 million in funding to “focus on cleaning low-, medium- and high-rank coal and resulting waste coal streams to sufficient levels, making it suitable for feedstock in high-value synthetic graphite processes,” according to the U.S. Department of Energy. The project uses technology developed by Yoon to harvest high purity carbon deposits from coal slurry ponds.

Yoon and Noble also developed technologies that extract rare earth elements from these same coal slurry ponds and similar mining wastes. This technology package was recently licensed to American Green Elements, headquartered in Bluefield, West Virginia, which aims to deploy the process in a commercial setting. Details of the technology are the subject of a series of pending patents. The innovative approach provides a pathway to recover rare earths in a manner that uses fewer chemicals and less energy than conventional approaches.

“My group has focused on mine tailings, refuse, and acid mine drainage, to name a few,” Noble said. “Some of these sources are current environmental liabilities; however, through our research, we have found that they also have significant quantities of critical minerals. By repurposing these waste streams, our scientific work addresses ways to effectively process these materials that are economically competitive and have fewer environmental impacts than conventional methods.”

The end goal is sustainable supply chains that support superior economic, environmental, and social outcomes. And the research has further benefits, in that it helps train new generations of mining engineers on ways to improve society through their profession.

“I also employ a lot of undergraduate researchers who work every day in our labs. And, in my classes, we explore the social, economic, and environmental aspects of critical mineral production. Last year, we hosted an in-class debate on the social and environmental implications of domestic rare earth production,” Noble said. “I believe our students at Virginia Tech are getting a lot of exposure to critical minerals in our curriculum, and as such, they will be the ones who facilitate change in this country.”