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Thorium speciation in titania slag: Implications for environmental remediation and valorisation

dc.contributor.authorChadirji-Martinez, K
dc.contributor.authorHudon, G
dc.contributor.authorChernikov, R
dc.contributor.authorHeredia, E
dc.contributor.authorFeng, Renfei
dc.contributor.authorCrawford, A
dc.contributor.authorPan, Yuanming
dc.date.accessioned2025-01-27T14:36:09Z
dc.date.available2025-01-27T14:36:09Z
dc.date.issued2024-11
dc.description.abstractTitania slag, produced from smelting placer ilmenite concentrates and used as a feedstock for TiO2 pigment production, contains low levels of radioactivity due to thorium and uranium. This study investigated the distribution and speciation of thorium in Rio Tinto Chloride Slag (RTCS), which contains an average of 170 ppm Th and 16 ppm U, using a variety of analytical methods from powder X-ray diffraction (pXRD) analysis to bulk and laser ablation inductively coupled plasma mass spectrometry (ICP-MS and LA-ICP-MS), electron microprobe analysis (EMPA), quantitative evaluation of materials by scanning electron microscopy (QEMSCAN), Raman spectroscopy, microbeam synchrotron X-ray fluorescence (µsXRF) mapping, synchrotron Laue X-ray diffraction (LXRD) and synchrotron X-ray absorption spectroscopy (XAS). Our data demonstrate that ~99.4% of Th in the RTCS is hosted by a chevkinite-like Th-REE-Ti aluminosilicate containing an average of 8.05±0.64 wt.% ThO2. The Th-REE-Ti aluminosilicate occurs as acicular (~0.3x12 µm) or tabular (~5x15 µm) crystals in association with a Th-bearing aluminosilicate glass (0.41±0.35 wt.% ThO2) as infillings either in interstitials or along the fractures of the main Ti-Fe oxides of the sassite-ferropseudobrookite solid-solution series. The Th-REE-Ti aluminosilicate and associated Th-bearing aluminosilicate glass formed probably during the quenching stage of the titania slag production. LA-ICP-MS analyses and µsXRF mapping show that the main Ti-Fe oxides in the RTCS contain only an average of 0.32±0.60ppm Th. Future pyrometallurgy operations that utilize Th- and U-bearing heavy mineral sands must consider their environmental effects and mitigate radioactivity. Also, preferential acid dissolution of the Th-REE-Ti aluminosilicate in RTCS and other titania slags may be used to recover Th and REE for dual environmental and economic benefits.
dc.description.sponsorshipWe also thank the University of Saskatchewan, Rio Tinto Fer et Titane, and the Natural Science and Engineering Research Council of Canada for funding this study
dc.description.versionPeer Reviewed
dc.identifier.citationChadirji-Martinez, K., Hudon, G., Chernikov, R., Heredia, E., Feng, R., Crawford, A., & Pan, Y. (2024). Thorium speciation in titania slag: Implications for environmental remediation and valorisation. Mineralogical Magazine, 1–35. https://doi.org/10.1180/mgm.2024.69
dc.identifier.doihttps://doi.org/10.1180/mgm.2024.69
dc.identifier.urihttps://hdl.handle.net/10388/16514
dc.language.isoen
dc.publisherMineralogical Magazine
dc.rightsAttribution 2.5 Canadaen
dc.rights.urihttp://creativecommons.org/licenses/by/2.5/ca/
dc.subjectThorium
dc.subjecttitania slag
dc.subjectchevkinite-group
dc.subjectsynchrotron XAS
dc.subjectvalorisation
dc.titleThorium speciation in titania slag: Implications for environmental remediation and valorisation
dc.typePreprint

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