Asphaltene precipitation kinetics and oil sands processing

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Oil sands mining contributes 1.6 million barrels per day of oil to the global oil supply and is a major contributor to the Canadian economy. To date, mined bitumen is recovered using aqueous extraction methods which produce significant amounts of greenhouse gases and require large tailings ponds for the waste water. An alternative is non-aqueous extraction, where a solvent is used instead of water so that the process is less energy intensive and does not require tailings ponds at all. However, there are a number of technical and economic issues to be resolved before non-aqueous extraction becomes a viable technology. One of these issues it that the product bitumen may contain suspended fine inorganic solids which can be problematic for refiners. This proposal investigates a method to remove these fine solids by promoting particle aggregation near the onset of asphaltene precipitation. Asphaltenes are the heaviest components of the bitumen and can precipitate as micron sized particles in certain solvents. The precipitated particles tend to flocculate rapidly into aggregates which are hundreds of microns in diameter. The inorganic particles in the bitumen are often partially coated with asphaltenic material and may also flocculate at the solvent conditions that cause asphaltene precipitation. In this proposal, asphaltene (and fine solids) precipitation and flocculation rates are to be investigated over a range of conditions to identify the conditions where fine solids can be flocculated without significant asphaltene precipitation. Settling experiments will be performed to determine if the solids can be removed in a practical timeframe. The proposed research will also provide a relevant background and the necessary experience to prepare two graduate students for oil sands related careers in industry, research institutes, and academia.