In the United States, increased production of renewable energy products, computer components, catalysts, and superconductors drives an increased need for Rare Earth Elements (REEs). In 2021, the United States government passed the Bipartisan Infrastructure Law (BIL), devoting millions of federal dollars to research and development of technologies to begin domestic production of REEs (SME, 2024).
SCS Engineers is involved in regional assessments of rare earth elements and critical minerals across the United States. Below we describe the process, science, and potential benefits of these studies that aim to help meet the increasing REE demands, provide coal mines with additional markets for their product, and transition coal into feedstocks for the REE market.
Exploration, Characterization, and Extraction for REE Potential
Under exploration are the characterization and extraction efforts within unconventional feedstocks like coal, coal refuse, coal fly ash, acid mine drainage (AMD), mine waste, oil and gas waters, and brines extracted for carbon sequestration. Waste streams related to mining in Pennsylvania also have proven potential for REE production.
Research relating to REE characterization and acquisition within Pennsylvania has identified sources of REEs within coal refuse and AMD. There are approximately 2 billion cubic yards of coal refuse within Pennsylvania (Verba, 2019) and AMD across the commonwealth. Universities and research groups are researching coal refuse and AMD solids in Pennsylvania to determine the viability of REE production.
Appalachian Basin Contains REEs and Treatment Potential
Research finds that host formations within the Appalachian Basin contain clays with REE. In 2019, electron microscopy, image processing, and complementary synchrotron methodologies were used to characterize the Pittsburgh formation. These methods utilized image processing to determine the distribution of the REEs and identified the individual elements, including yttrium, between 1.5-2.4% of the total volume. This method allows for pinpointing coal seams and waste coal refuse containing these clays for REE production once advanced extraction technologies are available (Verba, 2019).
While AMD is a pollutant to waters across Pennsylvania, its acidity can leach REE from host minerals in the surrounding rock. Treatment of AMD produces AMD solid waste in which REEs are present and extractable. Similar to the characterization of the Pittsburgh formation, a study was conducted on AMD solids from three AMD treatment systems using x-ray diffraction, sequential extraction, and synchrotron methodology to characterize REE materials and determine extraction potential. The study concluded that, during the treatment process for AMD, initial REE concentrations in AMD are reduced by 90% and sequestered into solid phases of iron, aluminum, or manganese, of which the manganese (Mn) and aluminum (Al) contain gadolinium and dysprosium. Mobilizing these REEs in AMD solids via sequential extractions with mild acidic and reducing treatments makes AMD solids a potential production source of REEs (Hedin, 2024).
REE Studies Across the United States
SCS Engineers is conducting a regional assessment of rare earth elements and critical minerals in parts of Iowa, Kansas, Missouri, Nebraska, Oklahoma, and the Osage Nation as part of a multi-state effort led by the Kansas Geological Survey. This survey includes a correlation of coal resources in the Cherokee-Forest City Basin via drill cores and coal mine waste to assess this region’s REE and critical mineral potential. This study and the studies in Pennsylvania aim to help meet the increasing REE demands, provide coal mines with additional markets for their product, and transition coal into feedstocks for the REE market.
References
Hedin, Benjamin C.; Stuckman, Mengling Y.; Cravotta III, Charles A.; Lopano, Christina L.; Capo, Rosemary C. (2024). Determination and Prediction of Micro Scale Rare Earth Element Geochemical Associations in Mine Drainage Treatment Wastes.
Society for Mining, Metallurgy, and Exploration (2024). Why the U.S. Needs a National Materials and Minerals Council.
Verba. Circe; Yang, Jonathan; Montross, Scott; Sanville, Henri; Lopano, Christina; and Stuckman, Mengling (2019). Microanalysis of Rare Earth Elements in Coal Prep Fines.
About the Authors:
Aaron Pysher, PG, has years of technical and consulting experience as a geologist serving commercial real estate, industrial, manufacturing, land acquisition firms, and energy utilities. He specializes in e geophysical surveys using gravimetry, seismic reflection, electrical resistivity imaging, and magnetics. His geophysical projects include karst feature delineation, bedrock depth and rippability, ArcMap/GIS for georeferencing, conducting road network evaluations, executing suitability analyses, and digitizing features from high-resolution aerial photography.
Christina Helms, PG, has nearly two decades of technical and environmental consulting experience as a geologist, project manager, senior technical advisor, and Licensed Site Remediation Professional (LSRP) on national, regional, and local environmental projects for private sector clients in commercial real estate, industrial, manufacturing, mining, and energy utilities.
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SCS Engineers is working to complete a regional assessment of rare earth elements and other critical mineral (CM) opportunities within parts of Iowa, Kansas, Missouri, Nebraska, Oklahoma, and the Osage Nation as part of a multi-state effort led by the Kansas Geological Survey (Critical Minerals in Coaly Strata of the Cherokee-Forest City Basin | netl.doe.gov).
This project is part of a multi-year Carbon Ore, Rare Earth, and Critical Minerals (CORE-CM, FOA-0002364) initiative funded by the U.S. Department of Energy to address all aspects of establishing a domestic critical mineral supply chain and the reuse of high-value, nonfuel, carbon-based resources. SCS Engineers is working with stakeholders within the Cherokee-Forest City Basin to develop assessments and strategies for waste stream reuse, infrastructural capacities and capabilities, technology development, outreach, and public-private partnerships.
The work from this project will identify information, technology, and infrastructure gaps that will need to be addressed to develop economic opportunities for critical mineral production, refining, and utilization specific to the Cherokee-Forest City Basin. These assessments may be utilized in future Phase II and Phase III components of the planned CORE-CM program for potential implementation within the region.
This study along with others have the potential to reduce U.S. reliance on foreign sources of critical minerals that are essential for electronics, renewable energy technologies, advanced manufacturing, and defense applications. It could also provide coal mines with additional markets for their product, transforming coal from something that is burned into a 21st century feedstock for advanced manufacturing.
Department of Energy Program Goals and Funding
Some research efforts are focused on unconventional and secondary feedstocks, such as coal and coal refuse, coal fly ash, acid mine drainage, mine waste, oil- and gas-produced waters, and brines extracted as part of carbon sequestration efforts. These feedstocks are known to contain elevated concentrations of CMMs, potentially in economic quantities, however their occurrence and distribution is not well constrained.
In April 2024, the U.S. Department of Energy’s (DOE) Office of Fossil Energy and Carbon Management (FECM) announced up to $60 million in funding to create regional teams to support the development of critical mineral and materials supply chains and novel high-value, nonfuel carbon-based products from unconventional and secondary feedstocks, such as coal and coal by-products, effluent waters from oil and natural gas development and production, and acid mine drainage. Realizing the critical mineral and materials potential in these feedstocks would enable the United States to rebuild a domestic supply chain for rare earth elements and other critical minerals and materials—which support high-tech manufacturing and the production of components for clean energy technologies—and reduce our dependence on international supply chains.
The funding period is now closed but projects selected under this funding opportunity will be announced in October and will continue the work of DOE’s CORE-CM Initiative, and expand the focus from the basin scale to a larger, regional scale. CORE-CM projects will develop and implement strategies that enable each specific basin to realize its full economic potential for producing REE, CM and high-value, nonfuel, carbon-based products from basin-contained resources.
Learn More Here:
Speak with our Author, Dr. Jon Yang, Senior Project Professional. Dr. Yang is a geochemist/engineer experienced in identifying and developing solutions to geochemical questions utilizing skillsets in experimental design, analytical chemistry, geochemical modelling, geological characterization, and engineering process design. He is also experienced in advancing research from early technology readiness levels along pathways for potential commercialization and/or technological transfer.
