![](/assets/locked-uofa-logo-d8c9669735d7334344db5f2c2b51d7459495fed9ce7fba28ebe880787b52b381.png)
Item Restricted to University of Alberta Users
Log In with CCID to View Item- 100 views
- 1 download
Rehabilitation of Mine Tailings by Simultaneous Prevention of Oxidation and Treatment of Acid Effluents Using a Wood-Waste Cover
-
- Author(s) / Creator(s)
-
At the East Sullivan site, wood wastes covering the abandoned mine tailings impoundment prevent sulfide oxidation by creating an anoxic environment. The addition of coarse ligneous wastes and their high permeability favour infiltration, resulting in a water table rise that maintains most tailings under water saturation and thus provides an additional protection against sulfide oxidation. Moreover, high infiltration allows a more rapid flushing of acid prone groundwater generated prior to the cover placement, which could cause acid mine drainage over a long period of time. Finally, the pore-waters under the cover are characterised by a strong reducing potential, high alkalinity, and near neutral pHs. These conditions favour sulfate reduction and base metal precipitation as sulfides and as carbonates. Pore-water composition monitored from 1992 to 1998 showed a significant Fe2+ decrease, following cover placement. Thereafter, the restoration strategy capitalised on the alkaline and reductive properties of the waters underlying the wood-waste cover. An original treatment of acid effluents, based on the recirculation of water discharging around the impoundment through the organic cover, was implemented. In 2002, the recirculated water from May to October had a mean pumping rate of 240 m3 /h, for a total volume of 800 000 m3 . Data gathered near the dispersal zone from 2000 to 2002 show that despite the recirculation of acid water (pH ≈3), the pH decreases by only one unit from 7 to 6, during the recirculation period, ie from May to November. However, alkalinity decreases from 800 to 100 mg/L-CaCO3. Despite this decrease, the alkalinity is back up to 800 mg/L-CaCO3 the following May, thanks to sulfate reduction. From 2000 to 2002, Fe2+ concentration in the pore waters near the dispersal zone is maintained below 2 mg/L. Evolution of surface water quality suggests that the contaminated groundwater flush is completed in the north and north-west area of the impoundment; the east sector is under recovery, while the south sector remains the most problematic. A wood-waste cover, besides limiting sulfide oxidation, can fill the role of alkaline reducing barrier for the treatment of these acidogenic waters, until a balance between acidity and alkalinity in the effluent is reached.
-
- Date created
- 2003
-
- Type of Item
- Article (Published)
-
- License
- Use of this product is restricted to current faculty, staff, and students of the University. It is the responsibility of each user to ensure that he or she uses this product for individual, non-commercial educational or research purposes only, and does not systematically download or retain substantial portions of information. Users may not reproduce or redistribute unprocessed/raw data portions of the data to any third party, or otherwise engage in the systematic retransmission or commercialization of the data.