(342j) Towards Improved Understanding of Polymer Flocculation Mechanism: Visualization of Mature Fine Tailings during Shear

Large tailing ponds formed during bitumen extraction continue to be a significant environmental issue in the development of oil sand reservoirs.  Quick remediation of these tailing ponds is important in order to mitigate their environmental impact.  The most challenging part of pond remediation is the settling of mature fine tailings, which contain stable water suspensions of clay nanoparticles and non-extracted bitumen.  The key to designing effective flocculants lies in the improved understanding of interactions within these suspensions, including clay-clay, flocculant-clay, and clay-bitumen interactions.  Here we aim to understand whether shearing, along with the use of commercially available polymer flocculants, can achieve the desired settling rate, or if further functionalization and development of new flocculants is required.  Mature fine tailings have been imaged in three dimensions using confocal rheology; laser scanning confocal microscopy combined with rheology.  This method provides unique insights into the direct connection between the applied shear and flocculation on both the micro and the macro scale.  Clay particles, polymer flocculants and the water phase are fluorescently tagged, while bitumen is autofluorescent, enabling true 3D imaging of the samples under shear.  The volume of clay/bitumen in the water suspension is evaluated from obtained images at varying temperatures and shear rates.  Significant differences in the flocculation process are observed for samples with different flocculants, presheering time and temperatures.  These findings provide new guidelines for the selection of effective flocculants depending on the clay/oil ratio and in the development of an operational process for flocculant use.