VOLUME 84, DECEMBER 2006 THE CANADIAN JOURNAL OF CHEMICAL ENGINEERING 643 INTRODUCTION A t present, approximately 35% of Canada’s petroleum needs can be met from the Athabasca oil sands. As conventional sources of oil and gas are depleted, it is inevitable that the oil sands will play a greater role in meeting North America’s petroleum needs. The main technology used today to extract bitumen from the Athabasca oil sands is a lower temperature version of the Clark Hot Water Process (CHWP). A typical bitumen extraction process involves the following essential steps: First, oil sand lumps are crushed and transported to slurry preparation where hot water is mixed with the ore. The resulting slurry is pumped into a hydrotransport slurry pipeline where slurry conditioning takes place. During the slurry transport, bitumen is liberated from the sand grains and the liberated bitumen becomes aerated by the entrained air in the slurry. A gravity separator is then used to recover the aerated bitumen as bitumen froth. After removing the water and solids from the froth, the bitumen is ready for upgrading. It is evident Effect of Illite Clay and Divalent Cations on Bitumen Recovery Xinlin Ding 1 , Chris Repka 2 , Zhenghe Xu 3 and Jacob Masliyah 3 * 1. SNC-Lavalin Inc., Calgary, AB, Canada T2P 3H5 2. Baker Petrolite Corporation, Fort McMurray, AB, Canada T9K 1P1 3. Department of Chemical and Materials Engineering, University of Alberta, Edmonton, AB, Canada T6G 2G6 that the extraction process requires (Hepler and Hsi, 1989; Hepler and Smith, 1994): liberation of bitumen from the sand grains; attachment and/or engulfment of the liberated bitumen with air bubbles; and flotation of bitumen-air aggregates to form a bitumen-rich froth. Clearly, interactions between bitumen and clay minerals or air bubbles play a key role in bitumen recovery as they affect bitumen aeration. It is well known that extraction techniques to recover bitumen from mined oil sand ore use large volumes of water. Currently, to produce one barrel of bitumen, 2.5 to 4.0 barrels of imported water are required (National Energy Board, 2004). With the increasing need to produce bitumen and with an increasingly limited water supply, producers have to reclaim water from mature fine tailings. To achieve this purpose, gypsum is usually added into the tailings system to accelerate the settling of fine The adverse effect of illite clay on bitumen recovery was found to be related to its acidity. The addition of calcium or magnesium ions to the flotation deionized water had a marginal effect on bitumen recovery when measured using a Denver flotation cell. However, the co-addition of illite clay and divalent cations caused a significant reduction in bitumen recovery. The effect was found to be compounded at a lower process temperature and low pH values. Zeta potential distributions of illite suspensions and bitumen emulsions were measured individually and as a mixture to investigate the effect of divalent cations on the interaction between bitumen and illite clay. The presence of 1 mM calcium or magnesium ions in deionized water had a significant effect on the interactions between bitumen and illite clay. Slime coating of illite onto bitumen was not observed in zeta potential distribution measurements performed in alkaline tailings water. On a trouvé que l’effet adverse de l’argile d’illite sur la récupération de bitume était relié à son acidité. L’ajout d’ions de calcium ou de magnésium à l’eau déionisée de flottation a un effet marginal sur la récupération de bitume lorsqu’on la mesure avec une cellule de flottation de Denver. Toutefois, l’ajout combiné d’argile d’illite et de cations divalents entraîne une réduction significative de la récupération de bitume. On a trouvé que les effets étaient combinés à une faible température de procédé et de faibles valeurs de pH. Les distributions de potentiel zéta des suspensions d’illite et des émulsions de bitume ont été mesurées individuellement et dans le mélange afin d’étudier les effets des cations divalents sur l’interaction entre le bitume et l’argile d’illite. La présence de 1 mM d’ions de calcium ou de magnésium dans l’eau déionisée a un effet significatif sur les interactions entre le bitume et l’argile d’illite. On n’a pas observé de couche de boues d’illite sur le bitume dans les mesures de distributions de potentiel zéta obtenues dans de l’eau de rejets alcaline. Keywords: bitumen recovery, zeta potential distribution, divalent cations, illite clays, pH * Author to whom correspondence may be addressed. E-mail address: jacob.masliyah@ualberta.ca