Microwave Heating Of Non-Aqueous Oil Sands Extraction Gangue: Study Of Optimal Cyclohexane-Water Mass Ratio And Solvent Recovery Rate

• Author / Creator

  Dos Santos De Araujo, Filipe

• Non-aqueous bitumen extraction processes (NAE) of mined oil sands ore have been investigated to circumvent the environmental and operating limitations of the current hot water-based technology.
  However, one primary challenge of NAE is a solvent recovery that meets environmental and economic constraints. Microwave heating (MWH) has been identified as a possible solution due to its selective and rapid heating nature. Nonetheless, this technology is still in the early stages of development, requiring a better understanding of concentrations of solvent and fines that are industrially relevant. Therefore, this work quantifies the solvent removal (cyclohexane) from NAE reconstituted gangue using MWH across different concentrations of cyclohexane, fines particles, and water (MWH absorber). Based on the previous literature, two main mechanisms are suggested for the solvent removal from NAE reconstituted gangue. The main mechanism is attributed to the selective heating of water that efficiently transfers energy to the cyclohexane which vaporizes. Additionally, cyclohexane is removed by steam stripping due to the water vapor generated in the MHW process.
  In addition, findings demonstrate that a minimum mass ratio of water/cyclohexane of 1/2 is enough to reduce cyclohexane concentration to undetectable levels (150 ppm) after 780 seconds, in agreement with the previous literature. Therefore, a water/cyclohexane mass ratio of 1/2 was employed to investigate the removal rate of cyclohexane for samples with fine concentrations of 10 and 20 wt% as well as cyclohexane concentrations of 6 and 12 wt%. The experimental data reveal an excellent agreement with a simple Lewis exponential drying model. Moreover, regardless of the initial cyclohexane concentration, a higher fine content results in a shorter vaporization time and a faster solvent removal rate. Fine particles exhibit a specific surface area significantly higher than coarse solids. Therefore, this behavior is attributed to an improvement in heat transfer efficiency promoted by an increased contact area between the heating agent or microwave absorber (water) and the sample. Such results demonstrate an improvement compared to conventional heating which is approximately 3 times slower for low-grade ore (higher fines content). The initial cyclohexane concentration, however, did not substantially affect the removal rate at the same fine concentrations. Overall, the findings show that MWH can effectively remove cyclohexane from NAE gangue, meeting economic and environmental constraints, laying the foundation for developing a greener NAE technology, and supporting the efforts of the oil sands industry to achieve net zero emissions.

• Subjects / Keywords

  • Microwave heating
  • Microwave drying
  • Non-Aqueous Oil Sands Extraction Gangue
  • Bitumen

• Graduation date

  Fall 2023

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/r3-tcvh-c209

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.