Separation of bitumen from oil sands using a switchable hydrophilicity solvent

Abstract

Separation of bitumen from oil sands is far more efficient with an organic solvent than with the conventional hot water (Clark) process, but the removal of the organic solvent from the bitumen requires distillation. Distillation is problematic because of the energy cost and the need for a volatile solvent (which is therefore likely to be flammable and smog-forming). A switchable hydrophilicity solvent (SHS) is a solvent that is water-miscible in the presence of an atmosphere of CO2 but separates from water when CO2 is absent. Extraction of bitumen from low-grade high-fines oil sands using a SHS (CyNMe2) is efficient, removing 94%–97% of the bitumen. The resulting solids (sand and clay) are dry, free-flowing, and contaminated with only 0.4 wt % of bitumen and as little as 102 ppm of the solvent. No distillation step was required to recover the solvent from the bitumen. Instead, carbonated water extraction removed the solvent from the oil. Losses of the CyNMe2 solvent were, for the best method, 0.06 grams of solvent per gram of bitumen recovered. The method recovers more oil than the Clark process, produces cleaner solids, works with low-grade high-fines oil sands, and requires neither distillation nor a volatile solvent.