Role of kerogen on the Solvent Retention and Sedimentation of Oil Sands in Non-Aqueous Bitumen Extraction

Abstract

One of the most problematic challenges of current hot water oil sands extraction methods is tailings ponds and the resulting environmental liability and risk. As a new method of extraction, non-aqueous extraction has the potential to replace the current hot-water extraction technology and eliminate the tailings ponds. Non-aqueous extraction can also substantially reduce the energy consumption for the extraction process, thereby reducing greenhouse gas emissions. Preliminary tests using solvents rich in cycloalkyl hydrocarbons, such as cyclohexane have confirmed that these solvents are capable to efficiently recover bitumen from the oil sands. Because non-aqueous bitumen extraction is not well known, characterizing inorganic and organic matter during a non-aqueous bitumen extraction process is a motivation for many researchers. Kerogen as an organic part of the oil sands is the subject of this research to understand its migration during extraction, and its effect on solvent retention and sedimentation of fine particles during non-aqueous extraction. The novel particle fractioning in a water/cyclohexane mixture shows that particles containing kerogen are accumulated in the hydrophobic fraction and migrate to the cyclohexane portion. Mass spectrometry measurements show that an increase of kerogen from 1 wt% to 5 wt% in the oil sand end members elevates solvent retention at room temperature from 80 to 226 ppm. This residual solvent could be released at a higher temperature of 50°C. Sedimentation of oil sands with different kerogen and bitumen contents revealed that kerogen has a slight effect on fine particle sedimentation, which makes the total process of settling slower and fine particles tend to stay in the supernatant.