Author ORCID Identifier

https://orcid.org/0000-0002-8626-6197

Semester

Fall

Date of Graduation

2024

Document Type

Dissertation

Degree Type

PhD

College

Eberly College of Arts and Sciences

Department

Geology and Geography

Committee Chair

Shikha Sharma

Committee Member

Aaron Maxwell

Committee Member

Amy Weislogel

Committee Member

Christina Lopano

Abstract

Although rare earth elements and yttrium (REY) are essential for manufacturing technologies vital to economic and national security, the U.S. is heavily reliant on foreign imports of these critical metals. There is significant interest in identifying and developing unconventional REY resources including coal and coal-byproducts to help secure domestic supplies of these elements. Appalachian Basin coals and byproducts are particularly enriched in REY. Coal-producing states within the basin, including West Virginia, can utilize existing infrastructure and legacy coal mining wastes to transition into the production of REY. However, in order to develop these resources, it is critical to understand the elemental phase associations and provenance of REY in coal to inform prospecting and recovery techniques. This dissertation utilizes a combination of statistical methods using open-source data and laboratory-based approaches, including sequential leaching and scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS), to investigate REY phase associations in coal. The results indicate that heavier REY have a stronger association with the organic fraction of coal and that phosphate minerals are common hosts of both heavy and light REY. However, REY-bearing minerals are often shielded by a resistant aluminosilicate matrix that can impede recovery. In order to maximize REY recovery from coal-based resources, methods must be developed to efficiently decompose the aluminosilicate matrix and REY-phosphate minerals. To this end, experiments were designed to evaluate the use of thermal pre-treatment methods paired with dilute acid leaching to recover REY. A maximum recovery of 70% - 84% total REY was achieved using sodium carbonate roasting followed by dilute citric acid leaching.

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