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Effective oxygen diffusion coefficient of till and green liquor dregs (GLD) mixes used in sealing layer in mine waste covers

Anna Virolainen, Christian Maurice and Thomas Pabst

Article (2020)

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Cite this document: Virolainen, A., Maurice, C. & Pabst, T. (2020). Effective oxygen diffusion coefficient of till and green liquor dregs (GLD) mixes used in sealing layer in mine waste covers. Water, Air, & Soil Pollution, 231(2). doi:10.1007/s11270-020-4431-3
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Abstract

Cover systems can efficiently limit acid mine drainage generation from sulfidic mine wastes by controlling oxygen diffusion. Their performance relies on their high degree of saturation, as oxygen diffusion is substantially reduced in water or saturated medium. However, natural soils available in the mine vicinities do not necessarily have the hydrogeological properties required for the construction of sealing layers. A common strategy is to improve the characteristics of local soils using bentonite amendment, but this usually induces high costs and environmental footprint. An alternative is to reuse (or valorise) waste materials, such as mine wastes or industrial wastes like green liquor dregs (GLD). Blends of till and GLD can have advantageous properties regarding water retention capacity and hydraulic conductivity. In this study, the effective oxygen diffusion coefficient De of till-GLD blends was evaluated using 81 diffusion tests. Various quantities and different types of GLD were tested. The diffusion coefficient was found to vary greatly depending on the degree of saturation. Even though the GLD contained naturally a substantial amount of water, a high water content of the till was still required to reach a low De. Measurements were also compared with modified Millington-Shearer predictive model which could generally predict the diffusion coefficient within an acceptable range. Results also indicated that the till-GLD mixes should not be exposed to evaporation as significant performance loss may rapidly occur upon drying. Main experimental results are presented in this paper together with recommendations in terms of cover design using till-GLD mixes.

Uncontrolled Keywords

Oxygen diffusion; Green liquor dregs (GLD); Mine wastes; Covers; Sealing layers; Acid mine drainage; Reclamation

Open Access document in PolyPublie
Subjects: 1400 Génie minier et minéral > 1402 Traitement des minéraux
1500 Génie de l'environnement > 1500 Génie de l'environnement
1500 Génie de l'environnement > 1504 Gestion des déchets dangereux (y compris Radioactivité)
Department: Département des génies civil, géologique et des mines
Research Center: Autre
Funders: Mistra "Closing the loop" (project GLAD), Horizon 2020 research and innovation (project Paperchain), GeoRes Marie Skłodowska-Curie Research and Innovation Staff Exchange (RISE) project
Grant number: 730305, H2020-MSCA-RISE-2017, 778120
Date Deposited: 20 Jul 2020 16:31
Last Modified: 21 Jul 2020 01:20
PolyPublie URL: https://publications.polymtl.ca/5323/
Document issued by the official publisher
Journal Title: Water, Air, & Soil Pollution (vol. 231, no. 2)
Publisher: Springer
Official URL: https://doi.org/10.1007/s11270-020-4431-3

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