Understanding the Properties of Bitumen Froth from Oil Sands Surface Mining and Treatment of Water-in-Oil Emulsions

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 X-ray 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 degrees. 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 organic-coated 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