Analysis led by the College of Utah has documented elevated concentrations of uncommon earth parts (REEs) in lively 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 vitality and different high-tech methods.
“The model is: if you’re already moving rock, could you move a little more rock for resources towards energy transition?” stated Lauren Birgenheier, an affiliate professor of geology and geophysics. “In those areas, we’re finding that the rare earth elements are concentrated in fine-grain shale units, the muddy shales that are above and below 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 Vitality-funded Carbon Ore, Uncommon Earth and Crucial Minerals challenge, or CORE-CM. The brand new findings will kind the premise for a grant request of a further $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.
“When we talk about them as ‘critical minerals,’ a lot of the criticality is related to the supply chain and the processing,” stated Michael Free, a professor metallurgical engineering and the principal investigator on the DOE grant. “This project is designed around looking at some alternative unconventional domestic sources for these materials.”
The affiliation between coal and REE deposits has been nicely documented elsewhere, however little information had been beforehand gathered or analyzed in Utah and Colorado’s coal fields.
“The goal of this phase-one project was to collect additional data to try and understand whether this was something worth pursuing in the West,” stated research co-author Michael Vanden Berg, Vitality and Minerals Program Supervisor on the Utah Geological Survey. “Is there rare earth element enrichment in these rocks that could provide some kind of byproduct or value added to the coal mining industry?”
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 crops.
“The coal itself is not enriched in rare earth elements,” Vanden Berg stated. “There’s not going to be a byproduct from mining the coal, but for a company mining the coal seam, could they take a couple feet of the floor at the same time? Could they take a couple feet of the ceiling? Could there be potential there? That’s the direction that the data led us.”
The workforce deployed two completely different strategies to file ranges of uncommon earths, expressed in components per million, or ppm, within the samples. One was a hand-held machine for fast readings within the area, the opposite used Inductively Coupled Plasma-Mass Spectrometry, or ICP-MS, in an on-campus lab.
“We’re mostly using this portable x-ray fluorescence device, which is an analysis gun that we hold to the rock for two minutes, and it only gives us five or six of the 17 rare earth elements,” Birgenheier stated. If samples confirmed concentrations larger than 200 ppm, they ran a extra full evaluation utilizing the extra expensive mass spectrometry tools.
The Division of Vitality 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 of “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 had been largely devoid of uncommon earths.
The workforce has analyzed 11,000 samples thus far, excess of had been used within the revealed research. Subsequent steps embrace figuring out how a lot uncommon earth ore is current, more likely to be executed with colleagues on the College of Wyoming and New Mexico Institute of Mining and Expertise.
