Rare earth element associations in the Kentucky State University stoker ash

James C. Hower, Dali Qian, Nicolas J. Briot, Kevin R. Henke, Madison M. Hood, Ross K. Taggart, Heileen Hsu-Kim

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


The Kentucky State University heating plant stoker ash, with over 1000 μg/g Rare earth elements + yttrium (REY), was previously shown to be more resistant to acid-extraction than pulverized-coal fly ashes of similar bulk composition. In this study, the petrology and mineralogy of this stoker ash was examined in greater detail as a means to better understand why the REY were relatively inert towards acid extraction. The results showed that this stoker ash is dominated by mullite and quartz/cristobalite with lesser amounts of hematite and magnetite compared to the glass-dominated assemblages of pulverized-coal-combustion fly ashes with similar chemical compositions. On the nanometer to micron scale, La-Ce-Nd-bearing monazite and Ce phosphates (monazite – CePO4 and CeP3O9) are seen to be part of the mineral assemblage. Overall, the results demonstrate that despite the presence of discrete REY-bearing minerals in the sample, their encapsulation within other phases may explain their low extractability.

Original languageEnglish
Pages (from-to)75-82
Number of pages8
JournalInternational Journal of Coal Geology
StatePublished - Mar 15 2018

Bibliographical note

Publisher Copyright:
© 2018 Elsevier B.V.


  • Appalachian coal
  • Lanthanides
  • Nanominerals
  • Transmission electron microscopy

ASJC Scopus subject areas

  • Fuel Technology
  • Geology
  • Economic Geology
  • Stratigraphy


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