Extraction process of bitumen from the oil sand ore must undergo an evolutionary change, as the mine sites farther away from the plant site must be developed in the future. At present the processes that breakup the lumps, liberate the bitumen from the sand grain and to some extent aerate the bitumen take place in the traditional rotating drum digester. As the distance between the plant site and the mine site is forced to increase, transportation of the ore by conveyor belt is not feasible and alternate technologies must be developed. Hydrotransport is one such technology in which a slurry of the ore is transported over long distance from the mine site to the extraction plant site. In the alternate technologies, the process of liberating and aerating the bitumen are to take place in the hydrotransport pipeline to some extent. While the total energy required to accomplish these steps can in principal be provided in the hydrotransport technology, and the industry is identifying the operating parameters of such a facility, it is becoming clear that the residence time of the slurry in the pipeline is significantly higher than in the traditional digester which introduces some new problems. In the proposed research, we are investigating the relationships between the solids content in the froth and the conditions (or environment) that produces the froth. We are designing a novel experimental setup in which we can control the shear environment. We plan to measure the solids content in both the bitumen and the aqueous phase as a function of controlled shear rate, the residence time of the mixture in the experimental cell, and the initial solids distribution between the aqueous and oleic phases.
Traditional characterization of multiphase flows in pipelines entails, (a) mapping the flow structure (e.g. homogeneous flow, slug flow, core annular flow, bubble flow etc, (b) relating macroscopic quantities like pressure drop vs flow rate relationship as a function of flow structure, amounts of each phase, diameter and inclination of the pipe etc., (c) characterizing the microstructure of the dispersed phases (like the equilibrium size of droplets or bubbles), and (d) measuring the spatial variation of concentration of different phases (particularly for transport in the horizontal direction where density stratification can cause significant operational problems). Items (a) and (b) have been looked at in sufficient detail for two-phase flow situations while (c) and (d) have not been looked at such great details.
In the present work, we are focusing on the effect of shear, chemical and thermal environment on the distribution of solids (both fine and coarse solids) between the aqueous and oleic phases and on the mechanisms of bitumen liberation. There is very little information on the amount of solids engulfed by the bitumen in a shear environment, typically encountered in hydrotransport technology. Traditional multiphase flow measurements such as the pressure drop-flow rate relationships, flow maps etc of three-phase flows in pipelines are equally important, but they will be conducted under a separate NSERC strategic grant project joint with Dr. Masliyah.
