Differences in bulk and microscale yttrium speciation in coal combustion fly ash - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Environmental Science: Processes & Impacts Année : 2018

Differences in bulk and microscale yttrium speciation in coal combustion fly ash

Résumé

Coal combustion ash is a promising alternative source of rare earth elements (REE; herein defined as the 14 stable lanthanides, yttrium, and scandium). Efforts to extract REE from coal ash will depend heavily on the location and speciation of these elements in the ash. This study sought to identify the major chemical forms of yttrium (Y), as a representative REE in coal fly ash samples selected from major coal sources in the United States. Y speciation was evaluated using both bulk scale analyses (sequential extractions, Y K-edge X-ray absorption near-edge spectroscopy-XANES) and complementary analyses at the micron scale (micro-focus X-ray fluorescence and micro-XANES). Sequential selective extractions revealed that the REE were primarily in the residual (unextracted fraction) of coal fly ash samples. Extraction patterns for yttrium resembled those of the lanthanides, indicating that these elements were collectively dispersed throughout the aluminosilicate glass in fly ash. Bulk XANES analysis indicated that Y coordination states resembled a combination of Y-oxides, Y-carbonate, and Y-doped glass, regardless of ash origin. However, in the microprobe analysis, we observed "hotspots" of Y ($10-50 mm) in some samples that included different Y forms (e.g., Y-phosphate) not observed in bulk measurements. Overall, this study demonstrated that yttrium (and potentially other REEs) are entrained in the glass phase of fly ash and that microscale investigations of individual high-REE regions in fly ash samples do not necessarily capture the dominant speciation.
Fichier principal
Vignette du fichier
c8em00264a.pdf (2.01 Mo) Télécharger le fichier
Origine : Publication financée par une institution
Loading...

Dates et versions

hal-01884609 , version 1 (01-10-2018)

Licence

Paternité - Pas d'utilisation commerciale

Identifiants

Citer

Ross K. Taggart, Nelson A. Rivera, Clément Levard, Jean-Paul Ambrosi, Daniel Borschneck, et al.. Differences in bulk and microscale yttrium speciation in coal combustion fly ash. Environmental Science: Processes & Impacts, 2018, 20 (10), ⟨10.1039/c8em00264a⟩. ⟨hal-01884609⟩
90 Consultations
112 Téléchargements

Altmetric

Partager

Gmail Facebook X LinkedIn More