Study of Bitumen Liberation from Oil Sands Ores by Online Visualization

A novel visualization cell was designed to study the kinetics of bitumen liberation from oil sands. This novel visualization cell allows for direct observation of bitumen recession from sand grains in real time under various experimental conditions, thereby providing a better understanding of bitumen liberation and the critical role of process conditions in bitumen extraction from oil sands ores. Although direct recession of bitumen from sand grains is found to be the primary mechanism of bitumen liberation, the presence of entrained air in oil sands ores greatly enhances bitumen liberation via bitumen spreading over air bubbles. Imaging analysis of the recorded real-time bitumen liberation process allowed for quantitative analysis of bitumen liberation kinetics. A rapid bitumen recession and, consequently, high bitumen recovery were observed for a good processing ore, in contrast to a slower bitumen liberation and lower bitumen recovery for a high-fines ore, which was considered to be a poor processing ore. The weathering (aging) of good processing ore was found to significantly reduce bitumen liberation kinetics, leading to a lower bitumen recovery, even though the bitumen content and solids composition of the ore remained the same. These findings confirmed the critical role of bitumen liberation in bitumen extraction. Increasing the process water temperature was found to increase significantly bitumen liberation kinetics and led to a higher degree of bitumen liberation. While high pH facilitated bitumen liberation, the presence of excessive salts (16 000 ppm sodium) was found to be detrimental to bitumen liberation, in particular at high pH. The bitumen liberation study using this novel visualization cell was extremely valuable for identifying and understanding critical operating parameters that control bitumen liberation and, hence, ore processability, providing a scientific basis for designing breakthrough technology to improve processability of oil sands ores and reducing the environmental impact of oil sands development.