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US coal ash highly rich in rare earths, scientists find

The Roxboro Steam Station, a four-unit, 2,422-megawatt coal-fired Duke Energy plant in Semora, N.C., is one of US largest power plants. It began operation in 1966, with additions in 1973 and 1980. (Image courtesy of Duke University)

US scientists have found what it could be key for the future of the country’s ailing coal industry as they detected that ashes from local operations, particularly those around the Appalachian region, are very rich in rare earth elements.

Coal waste generated by Appalachian coal operations are the richest in rare earth elements.

Researchers from North Carolina-based Duke University analyzed coal ashes from coal-fired power plants throughout the US, including those in the largest coal-producing regions: the Appalachian Mountains; southern and western Illinois; and the Powder River Basin in Wyoming and Montana.

One of the team main conclusions was that coal waste generated by the Appalachian coal operations was the richest in rare earth elements, containing 591 milligrams of the coveted elements per kilogram of ashes.

US coal ash highly rich in rare earths, scientists find

Professor Heileen (Helen) Hsu-Kim, one of the team’s leaders. (Image courtesy of Jon Gardiner | Duke Photography)

“There are literally billions of dollars’ worth of rare earth elements contained in our nation’s coal ash,” the researchers said in a statement.

“If a program were to move forward, they’d clearly want to pick the coal ash with the highest amount of extractable rare earth elements, and our work is the first comprehensive study to begin surveying the options,” they noted.

Not only rare earths are crucial to the manufacture of high-tech devices, but also to military communication systems, which is partially why the US Department of Energy recently offered $20 million to companies to solve the economic puzzle.

Previous research has focused on methods that can make the extraction or rare earths from coal waste not only financially viable, but also environmentally friendly.