Enormous potential for rare Earth elements found in US coal ash

Enormous potential for rare Earth elements found in US coal ash
by Clarence Oxford
Los Angeles CA (SPX) Nov 20, 2024
Coal ash, the residue left after coal is burned for energy, has accumulated across the United States for decades. Researchers from The University of Texas at Austin have discovered that this extensive coal ash supply holds a significant amount of rare earth elements, potentially enhancing the national reserve without requiring new mining efforts.

"This really exemplifies the 'trash to treasure' mantra," said co-lead author Bridget Scanlon, a research professor at UT's Bureau of Economic Geology at the Jackson School of Geosciences. "We're basically trying to close the cycle and use waste and recover resources in the waste, while at the same time reducing environmental impacts."

Rare earth elements, a group of 17 elements critical for modern technology, play a key role in renewable energy technologies, including solar panels, batteries, and magnets. However, the United States depends heavily on imports for these elements, with about 75% sourced from China, posing potential risks in light of geopolitical tensions and supply chain challenges.

The research estimates that up to 11 million tons of rare earth elements could be present in accessible U.S. coal ash - approximately eight times the current domestic reserves. The researchers valued the potential extractable rare earth elements at $8.4 billion.

This study, published in the 'International Journal of Coal Science and Technology', marks the first national assessment of coal ash resources. The U.S. Department of Energy is adopting the study's methodology for its own national evaluation.

While coal ash typically contains lower concentrations of rare earth elements compared to mined geological deposits, its widespread availability presents a promising resource, explained co-author Davin Bagdonas, a research scientist at the University of Wyoming. "There's huge volumes of this stuff all over the country," Bagdonas said. "And the upfront process of extracting the (mineral host) is already taken care of for us."

The study found that about 70% of the 1,873 million tons of coal ash produced between 1985 and 2021 could be recovered from storage sites like landfills and ponds. The remainder has already been used in other industries, such as cement manufacturing and road construction.

Coal ash's content of rare earth elements varies based on its source. Ash from the Appalachian Basin contains an average of 431 milligrams of rare earth elements per kilogram, though only 30% is extractable. Conversely, Powder River Basin coal ash, with a lower average concentration of 264 milligrams per kilogram, offers an extractability rate of approximately 70%.

Current extraction efforts are largely in the research stage, with Bagdonas contributing to a pilot project at the National Energy Technology Lab focusing on Powder River Basin coal ash. The foundational data from this study can support the development of a market for coal ash as a rare earth resource.

"This kind of broad reconnaissance-level analysis has never been done," Scanlon said. "It provides a foundation for others to go into more detail."

Chris Young, chief strategy officer at Element USA, highlighted the promising potential of coal ash. He emphasized the need for developing both the workforce and operational frameworks required to economically extract rare earth elements from coal ash and other mining byproducts. "The idea of getting rare earth elements out of tailings (mining by-products) just makes a lot of sense. It's a common-sense approach," Young noted. "The challenge is to convert that common-sense approach to an economic approach."

Element USA is advancing its operations by moving analytical labs and pilot equipment to Austin, enabling closer collaboration with UT Austin and providing students with hands-on opportunities in mineral research and processing. "We're excited about building that relationship with The University of Texas around mineral processing and mineral separation," said Young.

The study was funded by the U.S. Department of Energy Office of Fossil Energy and Carbon Management and the Jackson School of Geosciences. Co-authors include UT Austin's Robert Reedy, J. Richard Kyle, and Kristine Uhlman; University of Kentucky's James Hower; and independent consultant Dennis James.

Research Report:Coal ash resources and potential for rare earth element production in the United States