Valorisation of Partially Oxidized Tailings in a Cover System to Reclaim an Old Acid Generating Mine Site

The reclamation of acid-generating mine tailings typically involves building cover systems to limit interactions with water or oxygen. The choice of cover materials is critical to ensure long-term performance, and partly determines the environmental footprint of the reclamation strategy. The objecti...

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Bibliographic Details
Published in:Minerals (Basel) 2021-09, Vol.11 (9), p.987
Main Authors: Dublet-Adli, Gabrielle, Pabst, Thomas, Okkenhaug, Gudny, Sætre, Christian, Vårheim, Anna, Tvedten, Mari, Gelena, Samuel, Smebye, Andreas, Kvennås, Marianne, Breedveld, Gijs
Format: Article
Language:English
Subjects:
acid mine drainage
Acidic wastes
cover with capillary barrier effects
Drainage
Drying
Ecological footprint
Hydrology
Laboratories
Leachates
Materials selection
Mine reclamation
Mine tailings
Mine wastes
Minerals
Mining
Oxidation
Reclamation
Sand & gravel
sulfides
System effectiveness
Tailings
Water quality
Wetting
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Summary:The reclamation of acid-generating mine tailings typically involves building cover systems to limit interactions with water or oxygen. The choice of cover materials is critical to ensure long-term performance, and partly determines the environmental footprint of the reclamation strategy. The objective of this research was to evaluate if tailings pre-oxidized on-site could be used in cover systems. Column experiments were performed to assess the effectiveness of a cover with capillary barrier effects (CCBE), where the moisture retention layer (MRL) was made of pre-oxidized tailings with little to no remaining sulfides (LS tailings). The columns were submitted to regular wetting and drying cycles, and their hydrological and geochemical behaviour was monitored for 510 days. The LS tailings showed satisfying hydrological properties as an MRL and remained saturated throughout the test. The concentrations of Cu in the drainage decreased by more than two orders of magnitude compared to non-covered tailings. In addition, the pH increased by nearly one unit compared to the control column, and Fe and S concentrations decreased by around 50%. Despite these improvements, the leachate water remained acidic and contaminated, indicating that acid drainage continued to be generated despite a hydrologically efficient CCBE.
ISSN:2075-163X
2075-163X
DOI:10.3390/min11090987