Probing the Critical Element Chemistry of Coal-Combustion Fly Ash: Examination of Zircon and Associated Minerals from a Beneficiated Kentucky Fly Ash

Debora Berti; John G. Groppo; Prakash Joshi; Dorin V. Preda; David P. Gamliel; Todd Beers; Michael Schrock; Shelley D. Hopps; Tonya D. Morgan; Bernd Zechmann; James Hower

doi:10.3390/min15050461

Probing the Critical Element Chemistry of Coal-Combustion Fly Ash: Examination of Zircon and Associated Minerals from a Beneficiated Kentucky Fly Ash

Debora Berti, John G. Groppo, Prakash Joshi, Dorin V. Preda, David P. Gamliel, Todd Beers, Michael Schrock, Shelley D. Hopps, Tonya D. Morgan, Bernd Zechmann, James Hower

Research output: Contribution to journal › Article › peer-review

Abstract

Along with the principal rare earth (REE) minerals such as monazite, xenotime, and bastnasite, Y-and REE-bearing zircon and associated minerals survive the combustion process and are found in coal-combustion fly ash. Beneficiated fly ash from a power plant burning an eastern-Kentucky-sourced coal blend was found to have zircon (ZrSiO₄), baddeleyite (ZrO₂), fergusonite (YNbO₄), yttriaite (Y₂O₃), and xenotime (YPO₄). Previous studies of the same fly had also identified monazite with a broad REE suite. Scanning electron microscopy–electron dispersive spectroscopy (EDS) and transmission electron microscopy (TEM)–EDS as well as other TEM-based techniques revealed a variety of zircon associations, including heavy-REE suites with Y, Nb, and Hf. Hafnium is a common accessory element in zircons and the Y and Nb may be present as fergusonite (YNbO₄) intermixed with zircon.

Original language	English
Article number	461
Journal	Minerals
Volume	15
Issue number	5
DOIs	https://doi.org/10.3390/min15050461
State	Published - May 2025

Bibliographical note

Publisher Copyright:
© 2025 by the authors.

Funding

The pilot-scale beneficiation and extraction of the fly ash was supported by the U.S. Department of Energy under Award DE-FE0027167. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Scanning and transmission electron microscopy were conducted at the Center for Microscopy and Imaging of Baylor University, Waco, Texas. Purchase of the BioContinuum HD imaging filter and K3 single-electron detector was supported in part by Cancer Prevention Research Institute of Texas grant RR220081 awarded to Jonathan A. Clinger.

Funders	Funder number
Baylor University
United States Government
U.S. Department of Energy Oak Ridge National Laboratory U.S. Department of Energy National Science Foundation National Energy Research Scientific Computing Center	DE-FE0027167
U.S. Department of Energy Oak Ridge National Laboratory U.S. Department of Energy National Science Foundation National Energy Research Scientific Computing Center
Cancer Prevention and Research Institute of Texas	RR220081
Cancer Prevention and Research Institute of Texas

Keywords

coal combustion
critical elements
critical minerals
fly ash
rare earth elements
zircon

ASJC Scopus subject areas

Geotechnical Engineering and Engineering Geology
Geology

Access to Document

10.3390/min15050461

Cite this

Berti, D., Groppo, J. G., Joshi, P., Preda, D. V., Gamliel, D. P., Beers, T., Schrock, M., Hopps, S. D., Morgan, T. D., Zechmann, B., & Hower, J. (2025). Probing the Critical Element Chemistry of Coal-Combustion Fly Ash: Examination of Zircon and Associated Minerals from a Beneficiated Kentucky Fly Ash. Minerals, 15(5), Article 461. https://doi.org/10.3390/min15050461

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abstract = "Along with the principal rare earth (REE) minerals such as monazite, xenotime, and bastnasite, Y-and REE-bearing zircon and associated minerals survive the combustion process and are found in coal-combustion fly ash. Beneficiated fly ash from a power plant burning an eastern-Kentucky-sourced coal blend was found to have zircon (ZrSiO4), baddeleyite (ZrO2), fergusonite (YNbO4), yttriaite (Y2O3), and xenotime (YPO4). Previous studies of the same fly had also identified monazite with a broad REE suite. Scanning electron microscopy–electron dispersive spectroscopy (EDS) and transmission electron microscopy (TEM)–EDS as well as other TEM-based techniques revealed a variety of zircon associations, including heavy-REE suites with Y, Nb, and Hf. Hafnium is a common accessory element in zircons and the Y and Nb may be present as fergusonite (YNbO4) intermixed with zircon.",

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AU - Schrock, Michael

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AB - Along with the principal rare earth (REE) minerals such as monazite, xenotime, and bastnasite, Y-and REE-bearing zircon and associated minerals survive the combustion process and are found in coal-combustion fly ash. Beneficiated fly ash from a power plant burning an eastern-Kentucky-sourced coal blend was found to have zircon (ZrSiO4), baddeleyite (ZrO2), fergusonite (YNbO4), yttriaite (Y2O3), and xenotime (YPO4). Previous studies of the same fly had also identified monazite with a broad REE suite. Scanning electron microscopy–electron dispersive spectroscopy (EDS) and transmission electron microscopy (TEM)–EDS as well as other TEM-based techniques revealed a variety of zircon associations, including heavy-REE suites with Y, Nb, and Hf. Hafnium is a common accessory element in zircons and the Y and Nb may be present as fergusonite (YNbO4) intermixed with zircon.

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Probing the Critical Element Chemistry of Coal-Combustion Fly Ash: Examination of Zircon and Associated Minerals from a Beneficiated Kentucky Fly Ash

Abstract

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Keywords

ASJC Scopus subject areas

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