Coal and coal combustion byproducts can have significant concentrations of lanthanides (rare earth elements). Rare earths are vital in the production of modern electronics and optics, among other uses. Enrichment in coals may have been a function of a number of processes, with contributions from volcanic ash falls being among the most significant mechanisms. In this paper, we discuss some of the important coal-based deposits in China and the US and critique classification systems used to evaluate the relative value of the rare earth concentrations and the distribution of the elements within the coals and coal combustion byproducts.
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© 2016 by the authors; licensee MDPI, Basel, Switzerland.
- Coal combustion by-products
- Critical materials
ASJC Scopus subject areas
- Geotechnical Engineering and Engineering Geology