A Cleaner Way To Get Rare Earth Elements Out Of Coal

What do sleek laptops and smartphones have in common with a lump of coal? It’s not two sides to what might be rattling around in your stocking next Christmas. Instead it’s something much more basic: rare earth elements, also known as rare earth minerals or REE’s.

Rare earths are essential components of modern technologies, from iPhones to missiles, and just about everything in between. But although rare earth elements can be found all over the world, they are incredibly difficult to isolate, and it is even harder to draw them out of their matrix (usually clays or other geological deposits) without using harsh chemicals or other methods considered bad for the environment. Adding to the problem is the fact that most of the world’s rare earth supply comes from China, leaving other countries, including the United States, worried about shortages.

But a new study shows that it might be possible to extract rare earth elements from coal in the United States by rinsing discarded coal in a chemical solution.

“Essentially, REEs are sticking to the surface of molecules found in coal, and we use a special solution to pluck them out,” says Sarma Pisupati, an author of the study. “We experimented with many solvents to find one that is both inexpensive and environmentally friendly.”

Their solution of ammonium sulfate (more commonly used fertilizer) can currently extract 0.5 percent of the rare earths from the coal, and Pisupati is confident that they could eventually extract as much as 2 percent, a number that would be able to generate a decent amount of rare earths from coal that would otherwise be discarded as not fit for use in power plants.

Getting rare earth elements out of the ground in a cheap and environmentally friendly way is a goal long pursued by researchers and countries around the world. Chile has announced efforts to make extracting rare earth elements less damaging for the Earth. Other researchers are trying to extract rare earth elements from plants, and more controversially, some companies are looking to the seafloor as a resource for rare earths.

The coal industry is facing its own problems, with demand declining as countries shut down coal-fired power plants and coal mines amidst serious environmental concerns. Finding another use for this resource that doesn’t involve burning it could be indispensable for areas that are slowly transitioning away from coal mining towards other industries.