Coal combustion residuals are the solid wastes generated at coal-fired power plants and include fly ash, bottom ash, and sludge from flue gas desulfurization scrubbers. Collectively coal ash represents one of the largest industrial waste streams in the United States, with more than 100 million tons generated annually. Recent failures of coal ash impoundments in the U.S. has encouraged environmental policy makers to reconsider guidelines for coal ash disposal and to explore opportunities for beneficial reuse. Here, we investigated the potential to use coal ash as an alternative resource for rare earth elements (REEs). Our previous survey of U.S. coal ashes demonstrated that the total REE content as well as the contents of high value REEs (Nd, Eu, Tb, Dy, Y and Er) varied considerably and depended on the origin basin of the feed coal.<sup> </sup>This presentation will focus on characterization of REEs in coal ash as a means to understand the different REE modes of occurrence within coal fly ash, the development of methods to leach REEs from coal ash, and technologies to separate and concentrate REEs using liquid membrane-based processes. The results demonstrate that the extractability and recovery potential of REEs from coal ash depend on the geochemical composition of the ash material as well as the origins of the feed coal that was burned to produce the ash.

Recovery of rare earth elements from coal combustion residuals

256th National Meeting (2018)

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