Rare earth elements (REE) are of strategic importance because their numerous applications in various sectors of the global economy. The concern about the REE supply challenge has gained the interest and research in the recovery of REE from coal and coal by-products lately. In this study, we investigated leaching of rare earth elements and yttrium (REY) from a Central Appalachian coal and its ashes obtained at 550-950 oC with the main purpose of understanding the impact of ashing temperature on REY leachability in water, ammonium sulfate, and hydrochloric acid. It was found that the coal contained a negligible amount of water-soluble REY, less than 1% ion-exchangeable REY, and about 28% of HCl-soluble REY. Ashing led to dramatic changes in REY leachability in both ammonium sulfate and hydrochloric acid solutions, which is believed to be related to transformation and redistribution of organically-associated REY in coal during the ashing process. Ashing temperature significantly affected REY leaching from coal ashes; higher ashing temperature resulted in lower REY leachability in both solutions. Clay minerals might play a significant role in changing the leachability of REY after ashing. In addition, the results also suggested that the organic matter in the coal was relatively enriched in heavy REY.

Leaching of rare earth elements and yttrium from a central Appalachian coal and the ashes obtained at 550–950 oC

2019 Fall National Meeting

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