US scientists figure cost-effective way to extract rare earths from coal

Concentrate of rare earth waiting for further refinement at the Molycorp Mountain Pass rare earth facility in California’s Mojave Desert. Molycorp filed for bankruptcy last year. (Image from archives)

A group of researchers from Penn State, led by the US Department of Energy (DOE) has discovered that rare earth elements can be extracted from two coal by-products through an ion-exchange process.

The new mineral processing technique has the potential to challenge the current Chinese dominance on global rare earth production, as it makes the extraction not only cost-effective, but also environmentally friendly.

“We have known for many decades that rare-earth elements are found in coal seams and near other mineral veins,” said Sarma Pisupati, professor of energy and mineral engineering at Penn State. “However, it was costly to extract the materials and there was relatively low demand until recently,” he said in a statement.

The new mineral processing technique makes the extraction not only cost-effective, but also environmentally friendly.

The team said they wanted to take a fresh look at the feasibility of extracting REEs, from coal given the fossil fuel abundance in the country.

The discovery could be the good news the industry has been waiting for, especially after the Obama administration recently placed a three-year moratorium on new leases for coal mined from federal lands. Such decision is part of a sweeping review on the government’s management of vast amounts of taxpayer-owned coal throughout the country.

Using by-products of coal production from the Northern Appalachian region, the experts investigated whether a chemical process called ion exchange could extract REEs, widely used in advanced electronics, in a safer manner than other extraction methods.

Rare earths are key in military communication systems too, which is partially why the U.S. Department of Energy recently offered $20 million to companies to solve the economic puzzle.

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, the group says.

The method, they explain, involves rinsing the coal with a solution that releases the REEs that are bound to the fossil fuel.

The team is now collaborating with several Pennsylvania coal miners to explore the viability of a commercial REE-extraction operation.