Yttrium speciation in coal fly ash - What does this mean for recovering rare earth elements from coal ash?

Ross's paper on yttrium speciation in coal fly ash was just published in Environmental Science: Processes & Impacts (ESPI)! His study examined the chemical forms of yttrium and other rare earth elements in coal fly ash by using bulk scale and micro scale characterization techniques. His results demonstrate that micro scale analysis of yttrium can reveal discrete mineral phases of the element. However, these spot measurements do not necessary reflect the average form of yttrium (as determined by bulk analysis). Rather, yttrium and other rare earths are likely predominantly encased in glassy aluminosilicates of ash particles. These findings suggest that fairly aggressive leaching techniques are required to fully liberate rare earth elements during the recovery process.

Additional information can be found in these recent publications from the group:

Taggart, R.K.; Rivera, N.A.; Levard, C.; Ambrosi, J.-P.; Borschneck, D.; Hower, J.C.; Hsu-Kim, H. (2018). Differences in bulk and microscale yttrium speciation in coal combustion fly ash. Environmental Science: Processes & Impacts. In press. DOI: 10.1039/c8em00264a (available open access)

Taggart, R.K., Hower, J.C.; Hsu-Kim H. (2018). Effects of Roasting Additives and Leaching Parameters on the Extraction of Rare Earth Elements from Coal Fly Ash. International Journal of Coal Geology. 196, 106-114. DOI: 10.1016/j.coal.2018.06.021

King, J.F.; Taggart, R.K.; Smith, R.C.; Hower, J.C.; Hsu-Kim, H. (2018). Aqueous Acid and Alkaline Extraction of Rare Earth Elements from Coal Combustion Ash. International Journal of Coal Geology. 195: 75-83. DOI: 10.1016/j.coal.2018.05.009