Canada is reported to have one of the largest oil reserves in the world, with 97% of these reserves being related to oil sands. One key issue that challenges the oil sand companies is the large amount of tailings generated during the process of oil separation from mined sands, and the requirement of large surface areas for tailings storage. The problem is aggravated by the fact that oil sand tailings typically take a long time to consolidate, with limited reduction in volume and gain of strength over time. It appears to be a consensus that maximizing water removal from the tailings is critical to solve this problem.
This paper presents the results of laboratory drying column tests developed to evaluate the role of evaporation and under-drainage in the removal of water from oil sand tailings. The tests suggested that evaporation plays a major role in the process of water removal, while under-drainage is marginally beneficial. As a consequence, evaporation appears to be responsible for significant volume changes in the long term.