Analysis led by the College of Utah has documented elevated concentrations of uncommon earth components (REEs) in energetic coal mines rimming the Uinta coal belt of Colorado and Utah, suggesting a brand new avenue for sourcing these supplies that play a vital function in renewable power and different high-tech programs.
“The mannequin is: should you’re already shifting rock, might you progress a bit of extra rock for assets in direction of power transition?” mentioned Lauren Birgenheier, an affiliate professor of geology and geophysics. “In these areas, we’re discovering that the uncommon earth components are concentrated in fine-grain shale items, the muddy shales which might be above and beneath the coal seams.”
This analysis was carried out in partnership with the Utah Geological Survey and Colorado Geological Survey as a part of the Division of Power-funded Carbon Ore, Uncommon Earth and Vital Minerals undertaking, or CORE-CM. The brand new findings will kind the idea for a grant request of an extra $9.4 million in federal funding to proceed the analysis.
Whereas these metals are essential for U.S. manufacturing, particularly in high-end applied sciences, they’re largely sourced from abroad.
“After we discuss them as ‘essential minerals,’ a whole lot of the criticality is said to the availability chain and the processing,” mentioned Michael Free, a professor metallurgical engineering and the principal investigator on the DOE grant. “This undertaking is designed round some various unconventional home sources for these supplies.”
The affiliation between coal and REE deposits has been effectively documented elsewhere, however little knowledge had been beforehand gathered or analyzed in Utah and Colorado’s coal fields.
“The purpose of this phase-one undertaking was to gather further knowledge to attempt to perceive whether or not this was one thing value pursuing within the West,” mentioned research co-author Michael Vanden Berg, Power and Minerals Program Supervisor on the Utah Geological Survey. “Is there uncommon earth component enrichment in these rocks that might present some sort of byproduct or worth added to the coal mining trade?”
Researchers analyzed 3,500 samples from 10 mines, 4 mine waste piles, seven stratigraphically full cores, and even some coal ash piles close to energy vegetation.
“The coal itself will not be enriched in uncommon earth components,” Vanden Berg mentioned. “There’s not going to be a byproduct from mining the coal, however for an organization mining the coal seam, might they take a pair toes of the ground on the identical time? May they take a pair toes of the ceiling? May there be potential there? That’s the course that the information led us.”
The workforce deployed two totally different strategies to report ranges of uncommon earths, expressed in elements per million, or ppm, within the samples. One was a hand-held system for fast readings within the discipline, the opposite used Inductively Coupled Plasma-Mass Spectrometry, or ICP-MS, in an on-campus lab.
“We’re principally utilizing this moveable x-ray fluorescence system, which is an evaluation gun that we maintain to the rock for 2 minutes, and it solely offers us 5 – 6 of the 17 uncommon earth components,” Birgenheier mentioned. If samples confirmed concentrations larger than 200 ppm, they ran a extra full evaluation utilizing the extra pricey mass spectrometry gear.
The Division of Power has set 300 ppm because the minimal focus for uncommon earth mining to be doubtlessly economically viable. However for the research, researchers deemed concentrations larger than 200 ppm to be thought-about “REE enriched.”
The research discovered the very best prevalence of such concentrations in coal-adjacent formations of siltstone and shale, whereas sandstone and the coal itself have been principally devoid of uncommon earths.
The workforce has analyzed 11,000 samples up to now, excess of have been used within the printed research. Subsequent steps embrace figuring out how a lot uncommon earth ore is current, more likely to be accomplished with colleagues on the College of Wyoming and New Mexico Institute of Mining and Expertise.
