Bitumen-Mineral Interaction in Aqueous Solutions Containing Multivalent Metal Ions
Weibing Gan, PhD student in Materials Engineering
Supervisor - Dr. Qi Liu
The interaction between bitumen and minerals (quartz, kaolinite and illite) in aqueous solutions containing multivalent metal cations was studied with the objective of recovering residual bitumen from Athabasca oil sands froth treatment tailings. It was observed that the bitumen-quartz coagulation caused by hydrolysable multivalent metal cations (Fe3+, Mg2+, Ca2+) was reduced or prevented by organic chemicals including citric acid, oxalic acid and EDTA. Citric acid was found particularly effective even at very low concentration. Zeta potential measurements of quartz and bitumen at different pH suggested that the adsorption of the first order metal hydroxyl complexes and metal hydroxide precipitates on quartz was responsible for the strong affinity of bitumen for quartz. Removal of free multivalent metal cations through complexation by organic acids was considered the principal mechanism for preventing bitumen-quartz coagulation as a consequence of increased electrostatic repulsion between bitumen and quartz.
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