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Role of Caustic in Bitumen-Air Bubble Attachment and Slime Coating Open Access


Other title
Sodium Hydroxide
Bitumen Aeration
Slime Coating
Bitumen Extraction
Type of item
Degree grantor
University of Alberta
Author or creator
Curran, Meghan D
Supervisor and department
Xu, Zhenghe (Chemical and Materials Engineering)
Examining committee member and department
Xu, Zhenghe (Chemical and Materials Engineering)
Liu, Qingxia (Chemical and Materials Engineering)
Kuru, Ergun (Civil and Environmental Engineering)
Nikrityuk, Petr (Chemical and Materials Engineering)
Department of Chemical and Materials Engineering
Chemical Engineering
Date accepted
Graduation date
2016-06:Fall 2016
Master of Science
Degree level
Caustic is the most commonly used process aid to improve processability of mineable oil sands ores in the Athabasca region. The addition of caustic adjusts the pH of the extraction process, disperses clays, and acts as a water softener. Understanding how these changes affect the fundamental steps of extraction is important to improve current knowledge on the processability of oil sands ores by the addition of caustic. Understanding these effects enables the enhancement of bitumen recovery and improvement of froth quality in the extraction process. In this study, the aeration (bitumen-air bubble attachment) process was shown to be negatively impacted by caustic addition to the system. On the other hand, caustic addition reduces slime coating (bitumen-fines heterocoagulation). While the hindrance of aeration negatively impacts the extraction process, a reduction in slime coating positively impacts bitumen recovery. For aeration, the release of carboxylic surfactant, and a decrease in divalent cation concentration led to increases in the induction time of bitumen-bubble attachment. The release of carboxylic surfactant, decrease in divalent cation concentration and increase in humic acid concentration by caustic addition all hindered slime coating of fines on bitumen droplets. The types of fines/clays present in the oil sands also affect the slime coating. The processability of ores changes with these modifications to the aeration and slime coating processes. Aeration and slime coating, along with bitumen liberation, create a balance that governs the processability of each ore. Both bitumen liberation and slime coating are positively affected by increased caustic dosage, while the aeration process is hindered. The difference in recovery and froth quality between two ores processed using a batch extraction unit were explained by the differences in their bitumen liberation and slime coating behaviour, as the induction time of bitumen-air bubble attachment measured in the tailings water from these ores was quite similar.
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