1. PhD Candidate, Dept. of Chem. Engrg., Dupuis Hall, Queen's Univ., Kingston, ON, Canada K7L 3N6. E-mail: blouin@chee.queensu.ca (corresponding author).
2. Dept. of Min. and Metallurgical Engrg., F.D.A. Build., McGill Univ., Montréal, PQ, Canada H3A 2A7. E-mail: hemami@minmet.lan.mcgill.ca
3. Syncrude Canada Ltd., Edmonton Research Ctr., 9421-17 Ave., Edmonton, AB, Canada T6N 1H4. E-mail: lipsett.mike@syncrude.com