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Non-aqueous extraction (NAE) of bitumen from oil sands has been gaining great attention from both the industry and academia as an alternative to the water-based extraction. A fine solids removal step is important for a NAE process in order to obtain high-quality bitumen product, which, however, remains a great challenge to reduce the fine solids content to the desired level. Here, we introduce a strategy of destabilizing the bitumen-coated silica particles in toluene with the addition of water and biomolecules extracted from Cyamopsiste tragonolobuosr L. Taup., i.e., high molecular weight guar gum (HGG) and low molecular weight guar gum (LGG), respectively. By virtue of sedimentation tests and focused beam reflectance measurement analysis, we demonstrate that the introduced water droplets modified with these biomolecules can facilitate the settling of the solid particles in toluene although the underlying mechanisms differ between these two biomolecule cases. Specifically, in the case of LGG, the added water droplets with the interfacial amphiphilic LGG can strengthen the attachment of solid particles from bulk toluene to the LGG surface. This research work provides useful insight into the development of effective approaches for destabilization and removal of bitumen-coated fine solids from NAE bitumen.

Bitumen froth, as the crude product from the surface mining of oil sands, requires the efficient removal of water and solids for further processing. This work has systematically characterized the properties of bitumen froth from an oil sands operation in Northern Alberta and their correlation to the froth treatment efficiency (i.e., removal of water and demulsification behaviors). Systematic characterization was performed regarding the composition, wettability, and particle size distribution of the solids separated from different phases (i.e., diluted bitumen, aqueous phase, and coarse solids). Multiscale analyses including Xray photoelectron spectroscopy (XPS), scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM/ EDX), X-ray powder diffraction (XRD), and elemental analysis were employed to analyze the surface and bulk chemistry of the solids. The results indicate that a great amount of toluene-soluble and toluene-insoluble organics are discontinuously adsorbed on the solid surfaces, making the solid biwettable with a water contact angle of around 90°. The biwettable and fine solids are apt to remain at the oil/water interface or are trapped between the oil droplets, strengthening the "protective" interfacial film, which contributes to the formation of rag layer. The fine and ultrafine solids with a surface coating of organics remain with bitumen and adversely influence the quality of the separated bitumen. The organiccoated coarse solids precipitate toward the bottom, reducing the overall bitumen recovery. In addition, a trace amount of the organics could be firmly adsorbed on the solid surface, which further impedes the demulsification efficiency. This work correlates the characteristics of the bitumen froth and its demulsification efficiency using two commercial demulsifiers, with useful implications for developing effective and cost-efficient demulsifiers and emulsion treatment technologies in oil production and other related chemical and engineering processes.

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