Evaluation of thallium isotopic fractionation during the metallurgical processing of sulfides: An update

• Published in: Journal of hazardous materials Vol. 424; no. Pt A; p. 127325
• Main Authors: Vaněk, Aleš, Vejvodová, Kateřina, Mihaljevič, Martin, Ettler, Vojtěch, Trubač, Jakub, Vaňková, Maria, Teper, Leslaw, Cabala, Jerzy, Sutkowska, Katarzyna, Voegelin, Andreas, Göttlicher, Jörg, Holubík, Ondřej, Vokurková, Petra, Pavlů, Lenka, Galušková, Ivana, Zádorová, Tereza
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 15-02-2022
• Subjects: Environmental Monitoring; Isotopes - analysis; Isotopic Fractionation; Metallurgy; Soil Pollutants - analysis; Speciation; Sulfides; Thallium - analysis; Waste; Metallurgy; Waste; Isotopic Fractionation; Speciation
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2021.127325

In this study, we report combined Tl isotopic and Tl mineralogical and speciation data from a set of Tl-rich sulfide concentrates and technological wastes from hydrometallurgical Zn extraction. We also present the first evaluation of Tl isotopic ratios over a cycle of sulfide processing, from the ore flotation to pyro- and hydrometallurgical stages. The results demonstrate that the prevailing Tl form in all samples is Tl(I), without any preferential incorporation into sulfides or Tl-containing secondary phases, indicating an absence of Tl redox reactions. Although the Tl concentrations varied significantly in the studied samples (~9–280 mg/kg), the overall Tl isotopic variability was small, in the range of −3.1 to −4.4 ± 0.7 (2σ) ε205Tl units. By combining present ε205Tl results with the trends first found for a local roasting plant, it is possible to infer minimum Tl isotopic effects throughout the studied industrial process. As a result, the use of Tl isotopic ratios as a source proxy may be complicated or even impossible in areas with naturally high/extreme Tl background contents. On the other hand, areas with two or more isotopically contrasting Tl sources allow for relatively easy tracing, i.e., in compartments which do not suffer from post-depositional isotopic redistributions.
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•Thallium(I) – a major form in sulfide concentrates and metallurgical wastes.•No redox Tl reactions during sulfide processing, as revealed by XANES.•Overall small Tl isotopic variability (~1 ε205Tl) in the studied samples.•Minimum Tl isotopic effects throughout the industrial process.