Ilaria Rosella Pagliaro Demand for rare earths, essential for clean energy technologies, is growing: studies in Canada examine the possibility of extracting them from coal ash
Contrary to the misleading name, these rare earth elements are actually not as difficult to find as one might imagine. In fact, the challenge usually lies in their extraction, which is often complicated and confined to a few areas around the world, with China leading. This group of materials is called critical because the wind turbines, electric vehicles, and also batteries associated with clean energy technologies depend on them. As demand has continuously gone up, so has the issue’s relevance.
This is where Brendan Bishop, a PhD student at the University of Regina (Canada), comes in with his interesting challenge: finding new sources of rare earth elements in coal ash. Yes, coal-the very substance we consider enemy number one of the environment. His idea, nonetheless, was simple as it was brilliant: recycling waste from an antiquated industry to power the green future. It almost sounds like an oxymoron.
Whereas research in this area has been ongoing for some time in the United States and China, Bishop’s team in Canada is only just beginning to explore the potential of coal ash produced by power plants in Alberta and Saskatchewan.
The science behind the discovery
In attempting to surmount the problem of the heterogeneous distribution of the rare elements in the ash, Bishop utilized the X-ray beamlines of the Canadian Light Source, of the University of Saskatchewan, further concentrating his research on yttrium-one of the most valuable of the elements. To this end, it had been found that yttrium was concentrated in particular mineral phases within the ash, such as silica and phosphates-for example, xenotime-which survived intact during the combustion of coal. This is according to research published in the journal Environmental Science and Technology; it ushers in new methods of rare earth recovery and lays the bedrock for a process that is more efficient and sustainable.
Of course, not everything that glitters is gold neither are rare earth elements. Far from being simple, it requires much effort to extract them from coal ash; Bishop sees this field as a viable opportunity for eco-friendly recovery. This includes the rare earth elements, which come in the form of xenotime, a mineral already familiar to traditional extraction processes, and the idea is to adapt those already developed techniques to coal ash. Not impossible, nor far-fetched: the ash is abundant, well-distributed, and ready for usage.
The circular economy: from waste to resource
That’s the real beauty of this discovery: It’s not just a matter of providing rare earth elements without digging new mines but encouraging a model of the circular economy. The coal ash that presently comes out, mostly into landfills or storage ponds, can turn into a resource. Not tiny advantages, but a reduction in the environmental impact that this kind of industrial waste has, while changing it into valuable metals for future technologies, would be a success for both the environment and the economy. In the words of Bishop: “We wouldn’t just be eliminating an environmental problem; we would also be obtaining the metals needed to power clean energy.” That is just a classic example, when doing the right thing is the smartest choice.
Rare earth metals are going to define the future of green technologies, and perhaps the key to getting them just lies in wastes from the past. If innovation could be made from coal, then indeed we may have a reason to believe that a future of clean energy is not so farfetched after all.
