High-efficiency Extraction of Bitumen from Oil Sands Using Mixture of Ionic Liquid [Emim][BF4] and Dichloromethane

An ionic liquid (IL), 1-ethyl-3-methyl imidazolium tetrafluoroborate ([Emim][BF4]), was used to enhance bitumen recovery from oil sands by dichloromethane solvent extraction. A multiphase system could be formed by simply mixing the components at ambient temperature, consisting of sands and clays, mixtures of ionic liquid and dichloromethane, and concentrated bitumen layer. The results demonstrated that [Emim][BF4] increased the bitumen recovery up to 92%. Much less clay fines were found in the recovered bitumen than those formed by using dichloromethane solvent extraction alone, and the dichloromethane residue was not detected in the spent sands. We proposed that [Emim][BF4] had an ability to reduce the adhesion of bitumen to sand, resulting in an improved separation efficiency. Furthermore, [Emim][BF4] could facilitate the transfer of the extracted bitumen to the surface interface, and then the bitumen was auto-partitioned to a separate immiscible phase for ease of harvesting. This technology circumvented the issue of high consumption of distillation energy due to separation of bitumen phase and low boiling point of dichloromethane. [Emim][BF4] and dichloromethane could be readily recycled through the system and used repeatedly. After ten cycles, the bitumen recovery remained above 88%. Initial scale-up work suggested that this approach would form the basis for a viable large-scale process.

Automated summary

The study demonstrated that using an ionic liquid and dichloromethane solvent together can enhance bitumen recovery from oil sands, increase recovery rate, reduce clay fines, and avoid residue. This technology facilitates the separation of bitumen from sand, simplifies the recovery process, and effectively saves energy.