YTTRIUM XANES AND XRF ANALYSIS IN CLAY-RICH AND IRON-RICH SETTINGS

Rare earth elements, including yttrium (REY) are a growing commodity in the world market. To keep up with growing global demand, more sources of REY will be needed. Understanding the occurrence, in-depth distribution, and the feasibility of REY recovery from coal mine wastes (CMW) is key to discovering new non-conventional REY resources [1].

In this study we investigated the concentration and distribution of REY using Y as a proxy, in the clay and iron rich samples from an abandoned coal mine in Southern Illinois, by the combined use of bulk chemical analysis and synchrotron-based X-ray fluorescence (XRF), diffraction (XRD), and absorption (XANES).

We found larger concentrations of REY in the Al-rich samples versus the Fe-coated samples, which is consistent with the findings that Al-phases tend to incorporate more REY than their Fe counterparts. Our XANES spectra also revealed Y k-edge at 16.9 keV. Our results were consistent with the XRF spectra of xenotime and detrital phases along with concentrations and associations with other elements which include Ga (analogue for Al), Cu, and Zi. REY appeared to not be associated with Ti and As. We also found As such we found that clay minerals tend to adsorb REY to their surface while detritus was also associated with the incorporation of REY into their structure. Our findings show the behavior of REY within mineral matrices and adsorbed onto clay rich sediments.

[1] Lefticariu, et al. (2020) International Journal of Coal Geology 217, 1-34.