Uranium speciation control by uranyl sulfate and phosphate in tailings subject to a Sahelian climate, Cominak, Niger

Florian Lahrouch; Benoit Baptiste; Kathy Dardenne; Jörg Rothe; Erik Elkaim; Michael Descostes; Martine Gerard

doi:10.1016/j.chemosphere.2021.132139

Uranium speciation control by uranyl sulfate and phosphate in tailings subject to a Sahelian climate, Cominak, Niger

Chemosphere. 2022 Jan;287(Pt 2):132139. doi: 10.1016/j.chemosphere.2021.132139. Epub 2021 Sep 3.

Authors

Florian Lahrouch¹, Benoit Baptiste², Kathy Dardenne³, Jörg Rothe³, Erik Elkaim⁴, Michael Descostes⁵, Martine Gerard⁶

Affiliations

¹ Sorbonne Université, CNRS UMR7590, MNHN, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), 4 Place Jussieu, Paris, F- 75005, France. Electronic address: florian.lahrouch@upmc.fr.
² Sorbonne Université, CNRS UMR7590, MNHN, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), 4 Place Jussieu, Paris, F- 75005, France.
³ Karlsruhe Institute of Technology, Institute for Nuclear Waste Disposal (INE), P.O. Box 3640, Karlsruhe, D-76021, Germany.
⁴ Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP 48, Gif-sur-Yvette Cedex, F-91192, France.
⁵ ORANO Mines, Environmental R & D Department, 125 Avenue de Paris, Châtillon, F-93320, France; Centre de Géosciences, MINES ParisTech, PSL University, 35 rue St Honoré, Fontainebleau, 77300, France.
⁶ Sorbonne Université, CNRS UMR7590, MNHN, IRD, Institut de Minéralogie, de Physique des Matériaux et de Cosmochimie (IMPMC), 4 Place Jussieu, Paris, F- 75005, France. Electronic address: martine.gerard@sorbonne-universite.fr.

PMID: 34509019
DOI: 10.1016/j.chemosphere.2021.132139

Abstract

Long-term uranium mobility in tailings is an environmental management issue. The present study focuses on two U-enriched layers, surficial and buried 14.5 m, of the tailings pile of Cominak, Niger. The acidic and oxidizing conditions of the tailings pile combined with evapotranspiration cycles related to the Sahelian climate control U speciation. Uraninite, brannerite, and moluranite as well as uranophane are relict U phases. EXAFS spectroscopy, HR-XRD, and SEM/WDS highlight the major role of uranyl sulfate groups in uranium speciation. Uranyl phosphate neoformation in the buried layer (paleolayer) acts as an efficient trap for uranium.

Keywords: EXAFS spectroscopy; Environment; Mining wastes; Uranium; Uranium migration; Uranyl phosphate; Uranyl sulfate.

MeSH terms

Niger
Phosphates
Sulfates
Sulfur Oxides
Uranium* / analysis

Substances

Phosphates
Sulfates
Sulfur Oxides
Uranium