Geotechnical evaluation of tailings thickening

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Economic prosperity is influenced by the exploration of new sources of energy and materials along with the development of existing reserves. The Canadian mining industry contributes $40 billion to the economy and accounts for about 4% of the Gross Domestic Product. This important activity is associated with large volumes of ever increasing mine wastes of variable nature and extent. The mine tailings (slurries generated during ore processing) are particularly challenging because of their slow settling rates and high standing toxic waters in the waste containment facilities. Several tailings dam failures around the world resulted in massive contamination causing acute public distress over the conventional practice of tailings disposal. The industry has been proactive in developing novel waste management methods to minimize its environmental footprint. The proposed research will devise sustainable (cost effective, environmentally friendly, and socially viable) engineering solutions for base-metal mining operations by investigating the innovative method of slurry thickening. The specific goals include the following: (a) design of nonsegregating thickener feed to maximize the effectiveness of flocculation; (b) improve tailings dewatering during thickening to increase the efficiency of gravity thickeners; and (c) predict the long-term behavior of thickener underflow to evaluate subaqueous disposal in tailings ponds. This research will help produce nonsegregating tailings streams with bulk of the process water removed and recycled back for ore beneficiation. The low water content engineered materials will occupy a much smaller disposal area that can be reclaimed as a useful landscape in a relatively short time. In addition to an increased storage capacity of the tailings impoundments, the new tailings management solutions will help decrease environmental liabilities due to reduced acid rock drainage and metal leaching.