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Historical roasting of thallium- and arsenic-bearing pyrite: Current Tl pollution in the Riotinto mine area

López-Arce, P; Garrido, F; García-Guinea, J; Voegelin, A; Göttlicher, J; Nieto, JM; (2019) Historical roasting of thallium- and arsenic-bearing pyrite: Current Tl pollution in the Riotinto mine area. Science of The Total Environment , 648 pp. 1263-1274. 10.1016/j.scitotenv.2018.08.260. Green open access

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Abstract

Samples of an open-air pyrite roasting heap from the 19th century in the Riotinto mine area (SW Spain) and surrounding sediments and soil along a seasonal surface runoff channel were analyzed to study thallium (Tl) phase transformations during historical roasting of Tl-bearing arsenian pyrite, secondary weathering processes, Tl dispersion and current environmental pollution. Results from Electron Probe Microanalyses (EPMA) indicate an even distribution of Tl in pyrite grains of an ore sample (22 mg kg-1 total Tl), suggesting that Tl is incorporated in the pyrite structure rather than in discrete Tl-sulfide microparticles. The roasting residue (122 mg kg-1 total Tl) consists mainly of hematite. EPMA suggested that Tl in the roasting residue and contaminated soil was co-occurring with Fe oxide particles, with a mean Tl point concentration of 0.12% in samples from the roasting residues. Total concentrations of Tl in soil samples decrease with distance from the roasting heap to 14 mg kg-1. X-ray absorption near-edge structure (XANES) spectra collected on pyrite roasting residue and a soil sample suggest that most Tl is Tl(I) substituting K in jarosite. Sequential extractions show that most Tl (85-99%) in the soil and sediment samples is concentrated in the residual fraction and, thus, is rather strongly bound. Lastly, water extracts indicate that colloidal particles (i.e. <1 μm size) may contribute to the dispersion of Tl around and away from the roasting heaps.

Type: Article
Title: Historical roasting of thallium- and arsenic-bearing pyrite: Current Tl pollution in the Riotinto mine area
Location: Netherlands
Open access status: An open access version is available from UCL Discovery
DOI: 10.1016/j.scitotenv.2018.08.260
Publisher version: https://doi.org/10.1016/j.scitotenv.2018.08.260
Language: English
Additional information: This version is the author accepted manuscript. For information on re-use, please refer to the publisher’s terms and conditions.
Keywords: Colloids, Environmental pollution, Riotinto mine, Thallium, Tl XANES, Tl-jarosite
UCL classification: UCL
UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of the Built Environment
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of the Built Environment > Bartlett School Env, Energy and Resources
URI: https://discovery.ucl.ac.uk/id/eprint/10074543
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