The management of tailings is one of the major operational and environmental challenges faced by the mining industry. Indeed, the consolidation rate of high water-content materials such as tail-ings is generally limited by their high physical stability and low hydraulic conductivity. For example, oil sands tailings tend to reach equilibrium with as little as about 30 wt% solids within a few years. After-wards, they will not consolidate any further. Their storage thus requires large dedicated areas for virtually infinite periods, or until innovative solutions are found to permit additional consolidation / dewatering.
Extended laboratory work conducted in the last 4 years has shown that the use of electrically conductive drain-tube planar geocomposites (eGCP) can accelerate the dewatering rate of oil sands tailings. eGCPs combine a nonwoven geotextile which provides filtration and drainage, perforated pipes regularly posi-tioned within the geotextile, and a conductive component acting as an electrode. Water displacement to the product drainage pipes is driven by electro-osmosis potential. From there, water is evacuated by gravi-ty through the pipes.
The efficiency of eGCP for dewatering mature fine tailings (MFT) was demonstrated with a laboratory device developed to simulate tailings dewatering in the field. An increase in solids content from 45 to 70% was obtained with the application of 10.6 kWh per dry ton of treated MFT, leading to an improve-ment in shear strength from ± 0 to a mean value of 25 kPa in a little more than 40 days. The study also in-vestigated the effect of eGCP characteristics, conditions of the electrokinetic treatment, and tailings com-position and temperature. The results demonstrate the large potential of eGCPs at accelerating the dewatering of mine tailings with a minimal impact on mining operations.
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