Abstract
It is essential to develop effective mine waste management approaches and mine site reclamation techniques to curtail the adverse effects of mining processes on the natural environment. This study focuses on the use of partially desulphurized tailings as a moisture-retaining layer in an insulation cover with capillary barrier effects (ICCBE). Tailings were obtained from a nickel ultramafic ore processing plant at a mining company located in a continuous permafrost region of northern Québec, Canada. The geochemical response of tailings at two different sulphur contents (0.4 and 0.8 wt%), with and without ICCBEs, was tested by applying eight freeze-thaw and wetting cycles. Desulphurization of the tailings allowed to reduce the content of sulphide minerals by about 90%, from ~22 wt% to around 1.2–2.2 wt%. Column kinetic geochemical tests showed that Ni leaching was significantly reduced to concentrations ranging between 0.01–0.22 mg L−1 compared to 0.63–1.92 mg L−1 from the raw tailings (thanks to the desulphurization process). Zinc release was maintained around 0.04–1.72 mg L−1 compared to 0.4–3.69 mg L−1 from the raw tailing. Although all the columns produced leachates displaying circumneutral to slightly alkaline pH, the columns with ICCBE are expected to prevent acid mine drainage generation longer than the other columns due to reduced sulphide content and a constantly high degree of saturation maintained by capillary barrier effects.
Highlights
Metals and minerals extracted from the earth through mining significantly contribute to the economy of many countries worldwide
Raw tailings and waste rocks (WRs) were sampled from Raglan Mine, located at the extreme limit of Northern Quebec, Canada
According to to of the were classified as low plasticity silts (ML, the USCS soil classification [35], the raw tailings (RT) and desulphurized tailings (DST) were classified as low plasticity silts (ML, similar to to other other hard hard rock rock mine mine tailings; tailings; [15])
Summary
Metals and minerals extracted from the earth through mining significantly contribute to the economy of many countries worldwide. The main waste products produced from mining operations include waste rocks (WRs) and tailings (produced during ore processing) [1]. These WRs and tailings sometimes contain sulphide minerals (such as pyrite, arsenopyrite and pyrrhotite), which are unstable in atmospheric conditions (react with oxygen) and, upon receiving water, produce acidic leachates (known as Acid Mine Drainage or AMD). AMD is characterized by low pH and can contain elevated elemental concentrations of metals and metalloids [1,2,3,4]. Different technologies have been developed to avoid contamination from AMD generating wastes, and the selection of the most appropriate technology for a given site is a function of many factors such as the climatic conditions, material properties and availability, topography, mine waste reactivity, and in situ thermal and hydrogeological conditions [2,3,5,6]
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