Scientists successfully extracted precious rare earth elements from waste

Why mine for more, when you can recycle it?
Derya Ozdemir
The microscopic glass spheres found in coal fly ash containing REEs.Tour Group/Rice University

A team of researchers has successfully recovered precious rare earth elements (REE) which have magnetic and electronic properties crucial to modern electronics and green technologies from waste at high yields.

The process they utilized is gentler on the environment since it consumes significantly less energy and reduces the stream of acid commonly used to recover the elements into a drizzle, which is a huge breakthrough given how difficult it is to extract and recycle earth elements. This might be incredibly crucial because nothing makes more sense than recycling what has already been mined.

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How can we make sure rare earth elements don't waste away in waste?

Here is a fun fact: Rare earth elements are not in fact rare. If you'd look at cerium, you'd see that it is more abundant than copper, and all of them are more abundant than gold. But, like yttrium and scandium, these 15 lanthanide elements are widely scattered and difficult to extract from mined minerals.

This becomes a problem when you think about the fact that REEs are necessary components of more than 200 products across a wide range of applications, especially high-tech consumer products like cellular telephones, computer hard drives, electric and hybrid vehicles, and flat-screen monitors and TVs.

The researchers' flash Joule heating technology was devised some years ago to make graphene from any solid carbon source, and now, it's currently being applied to three sources of rare earth elements to recover rare earth metals: coal fly ash, bauxite residue, and electronic waste.

The new technique

The industrial extraction of these wastes often entails leaching with strong acid, which is a time-consuming and environmentally detrimental technique. In contrast, the researchers heated fly ash and other materials combined with carbon black to promote conductivity to roughly 5,432 degrees Fahrenheit (3,000 degrees Celsius) in a second.

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This process enabled them to convert the waste into highly soluble "activated REE species", according to the study published in Science Advances.

"The strategy is general for various wastes," postdoctoral researcher and lead author Bing Deng said, in a press release. "We proved that the REE recovery yields were improved from coal fly ash, bauxite residue, and electronic wastes by the same activation process."

And the process's universality is what makes it so promising: Millions of tons of bauxite residue and electronic trash are created each year. 

"The Department of Energy has determined this is a critical need that has to be resolved," Rice University chemist James Tour said. "Our process tells the country that we’re no longer dependent on environmentally detrimental mining or foreign sources for rare earth elements."

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