Geochemical behavior of a multi-layered cover composed of desulfurized mine tailings

Acid Mine Drainage (AMD) produced by sulfidic tailings constitutes a serious problem that affects many Canadian hard rock mines. For mines with active tailings impoundments, the use of multi-layered covers is considered to be one of the most practical alternatives to control the generation of AMD. This paper reports the behavior of desulfurized tailings as a moisture-retaining layer in the cover. A series of column experiments were conducted. The results showed that contaminant production is reduced significantly when a cover made of desulfurized tailings is placed over the reactive tailings. For example, zinc concentration in effluent were about 4 order of magnitude less for the covered columns. The oxidation rates, measured with the Oxygen-consumption method, are also significantly lower for the columns with a multi-layered cover. This study showed the potential of using desulfurized tailings as component of a multi-layered cover for limiting AMD from sulfidic tailings.