Abstract:

Repurposing of mine waste is a key component to a more sustainable mining industry and mitigation of climate change. At the same time, by turning waste into assets, through reuse of valuable materials, the mining industry can transform tailing ponds from a liability to an asset. One such example is the wet waste stream of tailings generated by the extraction of bitumen from the mineable oil sands deposits in northern Alberta. This tailings slurry comprised primarily of sand, fines (silt and clay) and ultrafine clay particles (<300 nm). Over the past decade industry has developed and deployed several techniques to rapidly dewater the tailings so that the disturbed landmass can be reclaimed into a terrestrial landform. However, the industry is still scouting for a more robust tailings technology that will add value while still addressing the ongoing concerns about the geotechnical and environmental risks as well as the long-term liabilities related to tailings storage.

EnviCore has developed a new tailings reduction technology that has the potential to accelerate the tailings consolidation, recovery and reuse of trapped process water at approximately one third of the current chemical costs associated with polymeric treatments. Furthermore, EnviCore’s process enables the extraction of nanosized clay minerals (<300 nm) from the tailings stream for application in enhanced oil recovery, drilling fluids, asphalt emulsification, cements, polymer nanocomposites and other usages. The nanoclays extracted from the oil sands tailings exhibit high surface area and bi-wettable characteristics due to the adsorption of organic material on the surface. Due to this bi-wettable behavior, Nano clays possess superior ability to emulsify oil in water Pickering emulsions and foams. The nanoclays owing to their small size, can easily propagate through the porous media and can be used to assist the water flooding performance to achieve high oil recovery. Lab experiments with nanoclays flooding showed a ~32% incremental oil recovery post waterflood for crude oil. Static foam stability tests revealed that synergistic interaction of nanoclays and surfactant resulted in a higher foam stability in comparison to a surfactant only system. The addition of nanoclays to cement improved the compressive and flexural strength by 11% and 25% respectively. For MgO based cement, the improvement was more pronounced resulting in 38% increase in compressive and 225% increase in flexural strength. These results demonstrate that by finding proactive ways to extract and use nanoclays as an additive for various applications, EnviCore provides a pathway to clean up existing tailings ponds, deliver a valued return on investment and contribute to the concept of a circular economy.

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Milana Trifkovic