Evaluation of wind-induced resuspension of flooded mine tailings at Shebandowan Mine Site, Ontario, Canada

摘要

Oxidation of sulphide bearing mine tailings caused by wind-induced waves and currents under shallow water cover conditions, can adversely impact the surrounding environment. This paper presents a study conducted to evaluate the performance of a water cover over sulfide-bearing tailings at Shebandowan Mine site, Ontario, Canada using field measurements and design winds. A new method developed by Samad and Yanful (2005) for selecting the minimum water depth required to eliminate resuspension was adopted in the study. A comparison of existing and calculated water depths revealed the inability of the existing water in the west cell of the pond to completely eliminate resuspension. The present water cover depth was designed using existing methods, such as the one described in the MEND Manual (2001), which prescribes a single bed shear stress for the entire pond relative to the bed critical shear stress. In-situ resuspension was evaluated using sediment traps and OBS sensors. The amount of resuspended tailings varied between 0.18 and 6.03 g during July 28 to October 06, 2006. Total suspended solids concentration measured with the OBS sensors was up to 80 mg/L. Analysis using the new method and design winds shows that an improved design of the water cover can be obtained by discretizing the tailings pond into grids and computing bed shear stress at each grid station and comparing to it the critical shear stress of the tailings. This allows the water depth to be selected for the various regions of the pond, including those along the longest fetch.