Article ID Journal Published Year Pages File Type
8123493 International Journal of Coal Geology 2018 27 Pages PDF
Abstract
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.
Related Topics
Physical Sciences and Engineering Earth and Planetary Sciences Economic Geology
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