Microanalytical Approaches to Characterizing REE in Appalachian Basin Underclays
The search for a reliable U.S. domestic source of rare earth elements (REE) is necessary to support the demand of advanced energy applications (e.g., catalysts, electronics, magnets). Sedimentary deposits may be sources for selectively recovering REE and critical metals—specifically the interbedded...
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| Format: | Article |
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MDPI AG
2020-06-01
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| Series: | Minerals |
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| Online Access: | https://www.mdpi.com/2075-163X/10/6/546 |
| _version_ | 1797565124695818240 |
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| author | Jon Yang Scott Montross Jim Britton Mengling Stuckman Christina Lopano Circe Verba |
| author_facet | Jon Yang Scott Montross Jim Britton Mengling Stuckman Christina Lopano Circe Verba |
| author_sort | Jon Yang |
| collection | DOAJ |
| description | The search for a reliable U.S. domestic source of rare earth elements (REE) is necessary to support the demand of advanced energy applications (e.g., catalysts, electronics, magnets). Sedimentary deposits may be sources for selectively recovering REE and critical metals—specifically the interbedded seat rock, or underclay, that underlies or forms the floor of a coal seam. This material is often a major component of coal waste fines and refuse and thus readily available. This study examines several Appalachian Basin underclays associated with actively mined coal seams as potential feedstocks for the REE. Multimodal microanalytical electron microscopy (SEM, FIB-SEM, EMPA) synchrotron-based µXRF, and image processing techniques are coupled with detailed elemental and mineral data to classify the 2D and 3D petrophysical properties of the materials. The REE contents of Appalachian Basin underclays were measured from 235–399 ppm and predominantly observed as discrete REE-bearing minerals such as monazite and xenotime on the order of 10–100 µm in size. These REE-bearing minerals typically accounted for less than 1% of the scanned areas and volumes under SEM and FIB-SEM analysis, with the exception of regions enriched in crandallite. Synchrotron-based µXRF elemental maps further identified several REE deposition environments in different underclays, including micro-scale (10–100 µm) light REEs co-localizing with Ca and P, micro-scale heavy REEs with Fe, and large-scale light REEs (>200 µm) co-localizing with Sr, Ba, Ca and P. |
| first_indexed | 2024-03-10T19:07:27Z |
| format | Article |
| id | doaj.art-cf83bae659fa46f8956464a74a47f16a |
| institution | Directory Open Access Journal |
| issn | 2075-163X |
| language | English |
| last_indexed | 2024-03-10T19:07:27Z |
| publishDate | 2020-06-01 |
| publisher | MDPI AG |
| record_format | Article |
| series | Minerals |
| spelling | doaj.art-cf83bae659fa46f8956464a74a47f16a2023-11-20T04:05:36ZengMDPI AGMinerals2075-163X2020-06-0110654610.3390/min10060546Microanalytical Approaches to Characterizing REE in Appalachian Basin UnderclaysJon Yang0Scott Montross1Jim Britton2Mengling Stuckman3Christina Lopano4Circe Verba5National Energy Technology Laboratory, U.S. Department of Energy, Albany, OR 97321, USANational Energy Technology Laboratory, U.S. Department of Energy, Albany, OR 97321, USAWest Virginia Geological and Economic Survey, Morgantown, WV 26508, USANational Energy Technology Laboratory, 626 Cochrans Mill Road, P.O. Box 10940, Pittsburgh, PA 15236-0940, USANational Energy Technology Laboratory, 626 Cochrans Mill Road, P.O. Box 10940, Pittsburgh, PA 15236-0940, USANational Energy Technology Laboratory, U.S. Department of Energy, Albany, OR 97321, USAThe search for a reliable U.S. domestic source of rare earth elements (REE) is necessary to support the demand of advanced energy applications (e.g., catalysts, electronics, magnets). Sedimentary deposits may be sources for selectively recovering REE and critical metals—specifically the interbedded seat rock, or underclay, that underlies or forms the floor of a coal seam. This material is often a major component of coal waste fines and refuse and thus readily available. This study examines several Appalachian Basin underclays associated with actively mined coal seams as potential feedstocks for the REE. Multimodal microanalytical electron microscopy (SEM, FIB-SEM, EMPA) synchrotron-based µXRF, and image processing techniques are coupled with detailed elemental and mineral data to classify the 2D and 3D petrophysical properties of the materials. The REE contents of Appalachian Basin underclays were measured from 235–399 ppm and predominantly observed as discrete REE-bearing minerals such as monazite and xenotime on the order of 10–100 µm in size. These REE-bearing minerals typically accounted for less than 1% of the scanned areas and volumes under SEM and FIB-SEM analysis, with the exception of regions enriched in crandallite. Synchrotron-based µXRF elemental maps further identified several REE deposition environments in different underclays, including micro-scale (10–100 µm) light REEs co-localizing with Ca and P, micro-scale heavy REEs with Fe, and large-scale light REEs (>200 µm) co-localizing with Sr, Ba, Ca and P.https://www.mdpi.com/2075-163X/10/6/546rare earth elementsrare earth mineralscoal underclay |
| spellingShingle | Jon Yang Scott Montross Jim Britton Mengling Stuckman Christina Lopano Circe Verba Microanalytical Approaches to Characterizing REE in Appalachian Basin Underclays Minerals rare earth elements rare earth minerals coal underclay |
| title | Microanalytical Approaches to Characterizing REE in Appalachian Basin Underclays |
| title_full | Microanalytical Approaches to Characterizing REE in Appalachian Basin Underclays |
| title_fullStr | Microanalytical Approaches to Characterizing REE in Appalachian Basin Underclays |
| title_full_unstemmed | Microanalytical Approaches to Characterizing REE in Appalachian Basin Underclays |
| title_short | Microanalytical Approaches to Characterizing REE in Appalachian Basin Underclays |
| title_sort | microanalytical approaches to characterizing ree in appalachian basin underclays |
| topic | rare earth elements rare earth minerals coal underclay |
| url | https://www.mdpi.com/2075-163X/10/6/546 |
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