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Role of carrier flotation in accelerating bitumen extraction recovery from mineable athabasca oil sands


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Ore blending is a strategy developed in the oil sands industry to enhance bitumen recovery from low grade oil sands ores. It involves blending low grade ores with high grade ores at a certain ratio, resulting in a higher overall bitumen recovery from the mixture than the simple recovery summation of the two extracted separately. To understand the underlying mechanisms, both bitumen-coated glass beads (−150 + 125 µm) and raw coal particles (−500 + 300, −300 + 150 and −150 µm) were used as carrier materials in this study to simulate bitumen droplets from high grade ores. Experimental results revealed that coal particles were more efficient than hydrophobised bitumen-coated glass beads in accelerating bitumen recovery and that better bitumen extraction performance was obtained by using smaller sizes of coal. This was attributed to the gravitational effect of larger, heavier particles on the detachment of bitumen-particle aggregates from bubbles. For smaller sizes of coal (−150 µm), a faster bitumen flotation recovery was achieved with more coal added. An increase in bitumen recovery up to 20–30% (absolute) was obtained by adding coal into the oil sands slurry. The interaction of bitumen with coal particles or bitumen-coated glass beads during oil sands slurry conditioning and flotation was visually verified from simple coagulation tests. The similarity of ore blending in oil sands extraction to carrier flotation in minerals flotation and the potential application of carrier flotation principles to oil sands extraction were discussed.