Rare Earth-bearing particles in fly ash carbons: Examples from the combustion of eastern Kentucky coals

Graphitic carbons from the combustion of bituminous coals and, perhaps, other coal ranks, tend to capture iron and a number of hazardous elements, including As, Hg, and Se. Rare earth elements in fly ashes occur in minerals, such as monazite, xenotime, and davidite. They also occur in sub-nm particles, probably in a mineral form, within the Al–Si glass on the investigated fly ashes. Just as graphitic carbons can capture Fe and hazardous elements, the carbons surrounding the fly ash glass and magnetic particles captures or encapsulates a broad suite of rare earth elements.