New Method Recovers Rare Metals from Coal Ash for Clean Energy

As the global community pivots towards cleaner energy sources, the demand for rare earth elements (REEs) is experiencing a swift surge. These metals are indispensable in fabricating green technologies such as electric vehicles and wind turbines. 
 
Even though REEs aren't genuinely scarce, significant deposits of these elements are primarily located in certain regions worldwide, with China being a notable source. Furthermore, extracting these valuable minerals presents its own set of challenges due to their intricate chemical properties. 
 
Brendan Bishop, a Ph.D. student at the University of Regina, has embarked on an innovative study aimed at finding new methods to obtain these precious resources. Bishop and his team have shifted their focus onto coal ash—the residual waste from coal-fired power plants—as potential sources for REE extraction. 
 
While previous research has delved into exploring REEs within coal waste from China and the U.S., Canadian coal ash hasn't been extensively studied so far. The team gathered ash samples from power stations situated across Alberta and Saskatchewan to determine both the quantity of present REEs and possible extraction techniques. 
 
The results revealed that Canadian coal ash's concentration levels were comparable to those discovered elsewhere globally. However, it was unclear whether these elements were uniformly dispersed throughout or concentrated within specific minerals in the ash. 
 
To elucidate this quandary further, Bishop turned towards advanced X-ray technology housed at Saskatchewan’s Canadian Light Source (CLS). The researchers focused on yttrium—a particular type of rare earth element—and found it predominantly nestled within silicates and phosphates like xenotime—specific minerals preserved unaltered during coal combustion—which makes them relatively easier to identify for potential extraction purposes. 
 
These findings were published recently in the Environmental Science & Technology journal, which signifies an essential step forward because it provides researchers with enhanced insight on how they can recover REEs more efficiently while maintaining environmental sustainability standards from the vast pools of available coal ash waste dumps around Canada—if not globally too! 
 
Since yttrium is present in xenotime—a recognized ore mineral—existing techniques used for extracting REEs from ores could be modified and applied to coal ash as well, according to Bishop. 
 
The potential yield of recoverable REEs would largely hinge on the efficiency of the extraction process developed. Even though the concentration levels aren't extremely high within coal ash, the enormous volumes of waste generated by power plants might make this a viable solution. 
 
Moreover, unlike mined ores where rare elements are unevenly distributed necessitating intricate sorting procedures, these elements are fairly evenly dispersed throughout coal ash, simplifying the extraction process significantly. 
 
Additionally, compared to opening new mines—which can take up to 17 years from exploration through production—the method of extracting REEs from coal ash could prove much quicker once perfected. 
 
By recovering these precious metals from otherwise discarded waste products like coal ash, we not only contribute towards creating a circular economy but also mitigate environmental damage while simultaneously acquiring essential resources needed for clean energy technologies. 
 
In Bishop’s words: "This process helps solve two problems—we can clean up the coal ash while getting the rare earth elements we need for green energy."