Stability and settling characteristics of solvent-diluted bitumen emulsions

When bitumen emulsions are diluted with aliphatic solvents at solvent-to-bitumen ratios above a certain value, water droplets, solids, and precipitated asphaltenes tend to form clusters that are much larger than the individual components. This work demonstrates that bitumen emulsions diluted with aliphatic solvent exhibit settling behavior distinctly different from that of bitumen emulsions diluted with aromatic solvent. The aliphatic system exhibits a zone settling mode with sharp interfaces. A characteristic interface appears as a discontinuity between the clean oil phase and the hindered settling zone. Laboratory techniques have been developed for measuring settling rates by tracking the interface positions with time. As an example, an experimentally observed settling curve was modeled by solving the conservation law hyperbolic equations.