Bitumen spreading over an air bubble in water

Abstract

The spreading of bitumen over an air bubble is one important sub step in the surface mining method of bitumen extraction from oil sands. In this study, the spreading process of the whole bitumen and deasphalted bitumen (maltene) over an air bubble in an aqueous phase was investigated at a macroscopic scale using a high-speed camera. It was observed that in pure water at 50 °C, bitumen spread onto the air bubble while maltene did not. While in simulated process water, both bitumen and maltene spread in a similar pattern. Bitumen spreading had a shorter induction time but a slightly slower spreading rate compared to maltene spreading. It was suggested that the role asphaltene played in bitumen spreading might be to reduce the magnitude of the zeta-potential at the bitumen-water interface and thus the electrostatic repulsion between the bitumen-water and air-water interfaces. Further, the influence of the temperature on the spreading kinetics was studied at a temperature range of 22–73 °C. The results showed that the spreading kinetics increased with increasing temperature and the areal spreading velocity decreased with time for all temperatures. The activation energy for the bitumen spreading was calculated to be 94.7 and 107.9 kJ/mol for 1 and 2 mm2 coverage, respectively. In addition, it was found that the spreading kinetics increased with increasing the toluene amount added into the bitumen. The findings in this work will help better understand the mechanisms involved in the spreading of bitumen over an air bubble in water.