Highlights
- University of Texas research finds 11 million tons of rare earth elements in accessible coal ash, nearly 8 times current U.S. domestic reserves.
- Approximately 70% of coal ash produced from 1985-2021 is potentially recoverable, with varying extractability across different coal basins.
- The study provides a foundational analysis for transforming coal ash from industrial waste into a valuable resource for critical mineral extraction.
Interesting research spearheaded by the University of Texas at Austin (opens in a new tab) discovers that the national coal ash supply contains enough rare earth elements to significantly bolster the national supply without any new mining. Coal ash — the chalky remnants of coal that has been burned for fuel — has been piling up across the United States for decades.
An interesting study outcome made possible by funding from the U.S. Department of Energy Office of Fossil Energy and Carbon Management, and the Jackson School of Geosciences (opens in a new tab).
Bridget Scanlon, (opens in a new tab) a research professor at UT’s Bureau of Economic Geology at the Jackson School of Geosciences went on the record concerning the findings, “this really exemplifies the ‘trash to treasure’ mantra.” Scanlon continued “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.”
Total and potentially accessible coal ash reported by the electric power sector during 1985–2021
(opens in a new tab)The new UT Austin research suggests as much as 11 million tons of rare earth elements in accessible coal ash in the United States, which is nearly 8 times the amount that the U.S. currently has in domestic reserves, according to the researchers. Rare Earth Exchanges recently reported on a Utah-based effort involving the study of REE in coal seams and tailings.
But this Texas study is a first according to the authors: the first study to tally up national coal ash resources.
The researchers estimate that $8.4 billion worth of rare earth elements could be extracted from the accessible supply of coal ash.
Study Findings
Published in the International Journal of Coal Science & Technology (opens in a new tab), the authors note that the U.S. Department of Energy own applies the study’s methodology to conduct its own national assessment of coal ash resources.
But while the actual amount of rare earth elements in coal ash is actually relatively low at least when compared to rare earths in geological deposits, regardless of sufficient supply should attract attention, points out study co-author Davin Bagdonas, (opens in a new tab) a scientist at 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.”
Approximately 70% of the coal ash produced from 1985 to 2021 — a total of about 1,873 million tons — is potentially recoverable, with the material stored in landfills, ponds, and offsite storage areas. The rest of the coal ash has been sold and used by other industries, such as cement production and road construction.
What elements does coal ash contain?
According to the study’s authors, coal ash contains varying levels of rare earth elements, depending on where they originate. Place of origin also affects how much of the rare earth elements can be extracted.
The Appalachian Basin coal contain the highest amounts of rare earth elements, with an average value of 431 milligrams per kilogram. But only 30% of the rare earth elements it contains can be extracted, which undoubtedly may raise concern.
But Powder River Basin coal has the lowest average value of rare earth elements at 264 milligrams per kilogram, but it has an extractability of about 70%.
Most of the work around rare earth element extraction is still in the research phase. Bagdonas is involved with a pilot project at the National Energy Technology Lab that’s extracting rare earth elements from the Powder River Basin coal ash.
Estimated total associated ash from coal production in the United States by basin. About 83% of all ash produced during the period was from the Appalachian, Powder River, and Illinois basins combined.
(opens in a new tab)Scanlon suggests with this accumulating foundational data the prospect for building a broader market for coal ash as a resource becomes intriguing. “This kind of broad reconnaissance-level analysis has neverbeen done,” Scanlon said. “It provides a foundation for others to go into more detail.”
Are the companies that can perform this type of activity?
Absolutely! One mentioned in the study report at UT Austin is Chris Young, (opens in a new tab) the chief strategy officer at Element USA (opens in a new tab), a company that extracts critical minerals from mineral and metallic waste, said that the study underscores the great potential of coal ash as a resource. He said the challenge now for industry is developing the workforce and operations needed to extract rare earth elements and other materials 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,” he said. “The challenge is to convert that common-sense approach to an economic approach.”
To that end, Element USA is in the process of moving its analytical lab and pilot equipment to Austin to leverage the mineral expertise at The University of Texas at Austin and offer critical mineral experience to students interested in critical mineral research and careers.
“We’re excited about building that relationship with The University of Texas around mineral processing and mineral separation,” Young said.
The additional study co-authors are bureau researchers Robert Reedy (the other co-lead author), J. Richard Kyle and Kristine Uhlman, University of Kentucky research professor James Hower, and independent consultant Dennis James.
Daniel
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