Affiliation: | (1) Polytechnique-UQAT NSERC Chair in Environment and Mine Wastes Management, Department of Applied Sciences, Universite du Quebec en Abitibi-Temiscamingue, 445 University Blvd, Rouyn-Noranda, Quebec, J9X 5E4, Canada;(2) Polytechnique-UQAT NSERC Chair in Environment and Mine Wastes Management, Department of Civil, Geological and Mining Engineering , Ecole Polytechnique de Montreal , Stn Centre-ville , PO Box 6079, Montreal, Quebec, H3C 3A7, Canada |
Abstract: | Covers with capillary barrier effects (CCBE) are considered to be one of the most effective ways to control acid mine drainage (AMD) production from mine wastes. The use of low-sulphide tailings in CCBE has been proposed recently for cases where other types of material may be unavailable near the mining site. This paper presents leaching column test results showing that CCBEs with a moisture-retaining layer made of slightly reactive tailings, with three different sulphide contents, can effectively limit the production of AMD from the acid-generating tailings placed underneath. With these layered covers, the leachate pH was maintained near neutrality throughout the testing period. When compared to uncovered tailings, the efficiency of the cover systems for reducing the amount of contaminants in the percolated water was determined to be greater than 99% for zinc, copper and iron. This study shows that the use of low-sulphide tailings can improve the ability of a CCBE to limit gas diffusion by consuming a fraction of the migrating oxygen. |