Researchers at the University of Regina have discovered a potentially new source of rare earth elements (REEs), the ash produced by coal-fired power plants. REEs are technically not rare, however, large deposits are only found in a few locations around the world and are difficult to extract.
As the world transitions to green energy, REE demand is soaring as these elements are vital to next-generation energy technologies.
"If we want to switch to electric vehicles by 2035 and be net-zero by 2050 we're going to need new sources of these metals," says Brendan Bishop, a Ph.D. candidate studying REEs at the University of Regina.
While coal ash has been studied in the United States and China, little work has been done to investigate Canadian coal ash. In the study, published in Environmental Science and Technology, the researchers utilized the X-ray beamlines at the Canadian Light Source (CLS) in search of yttrium. The team discovered that the element was distributed in specific mineral phases within the ash, most often in the silicates or phosphates.
The findings of the study could aid future researchers in developing an efficient process for recovering REEs from coal ash. "This will be important when we develop a recovery process because extracting rare earth elements is technologically challenging," said Bishop. "In this case, since it's in xenotime which is an ore mineral, maybe we can use an existing process and modify it for coal ash."
The amount of recoverable REEs that could be extracted will heavily depend on the method developed to extract them but the team feels as though it could be an acceptable short to medium-term source of the materials. Additionally, the recovery process would be an important step towards a circular energy economy.
"It not only gets rid of an environmental liability, but it also gives us the metals we need for clean energy technologies," added Bishop.