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.
|Number of pages||8|
|Journal||International Journal of Coal Geology|
|State||Published - Mar 15 2018|
Bibliographical noteFunding Information:
This work was supported by National Science Foundation grants CBET-1510965 and CBET-1510861 to Duke University and the University of Kentucky, respectively.
© 2018 Elsevier B.V.
- Appalachian coal
- Transmission electron microscopy
ASJC Scopus subject areas
- Fuel Technology
- Economic Geology