Rare Earths From Coal?

Futurity reported that researchers at Penn State University have found that it may be possible to use ammonium sulfate to extract rare earth elements from coal deposits in the United States.
As quoted in the publication:

Using byproducts of coal production from the Northern Appalachian region, the team investigated whether a chemical process called ion exchange could extract REEs in a safer manner than other extraction methods.
For example, past research has examined “roasting,” a process that is energy intensive and requires exposure to concentrated acids. In contrast, ion exchange is more environmentally friendly and requires less energy. Ion exchange involves rinsing the coal with a solution that releases the REEs that are bound to the coal.
“Essentially, REEs are sticking to the surface of molecules found in coal, and we use a special solution to pluck them out,” says Pisupati. “We experimented with many solvents to find one that is both inexpensive and environmentally friendly.”
The team reported in their findings, published in the current issue of Metallurgical and Materials Transactions E, that ammonium sulfate was both environmentally friendly and able to extract the highest amount of REEs. Extracting 2 percent of the available REEs would provide an economic boon to companies, the team says.
“We were able to very easily extract 0.5 percent of REEs in this preliminary study using a basic ion exchange method in the lab,” says Pisupati. We are confident that we can increase that to 2 percent through advanced ion exchange methods.”

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