Probing the Critical Element Chemistry of Coal-Combustion Fly Ash: Examination of Zircon and Associated Minerals from a Beneficiated Kentucky Fly Ash
2025
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 C. Hower
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&ndash:electron dispersive spectroscopy (EDS) and transmission electron microscopy (TEM)&ndash: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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