The influence of interfacial tension in the recovery of bitumen by water-based conditioning and flotation of Athabasca oil sands

Studies of the processibility of a variety of types of Athabasca oil sands have been carried out to further elucidate the physical action of natural surfactants in the hot-water flotation process. In particular, the interfacial tensions between bitumen and aqueous phases were measured at process temperature (80 and 50 °C). The electrophoretic mobilities of the dispersed oil and fine mineral phases were also measured for each processibility determination. By varying the level of process aid addition, sub-optimal, optimal and overdosed conditions were represented. In the case of the oil/solution interface, the present work shows that the interfacial tension is reduced and passes through a minimum with increasing natural surfactant-producing alkaline process aid addition. The condition under which this minimum is achieved is associated with maximum efficiency of the hot-water flotation process. In the case of the bitumen/aqueous interface, optimal primary recovery efficiency was found to be associated with a maximum in interfacial electric charge and a minimum in interfacial tension.