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Role of Nano and Microsize Clay Minerals in Non-Aqueous Bitumen Extraction from Alberta Oil Sands
- Author / Creator
- Mirjavad Geramian
The current commercial aqueous extraction processes produce large amounts of tailings and is the major obstacle to recovery of bitumen from the oil sands. Solvent-based bitumen extraction is an alternative process, due to its high bitumen recovery and dry solids/tailings (gangue). During non-aqueous extraction, it is expected that some minerals, particularly nano and microsize minerals (NMM), change the processability of the oil sands ore due to their interaction with other ingredients such as water, bitumen and solvent. The gap of knowledge on the influence of mineralogical and chemical composition of the NMM during non-aqueous extraction directed us to the present study.
The aim of this study was first to identify the mineralogy, chemistry and surface properties of four petrologic end member samples from Syncrude’s North Mine collected in 2009 (NM09) and 2012 (NM12), i.e., marine claystone (MC), marine sand (MS), estuarine claystone (EC) and estuarine sand (ES). The as-received (ASRE) petrological end members and their different size fractions were examined in this study by various analytical techniques and the results were compared with samples taken from the Aurora Mine in 2010 (AM10) of Syncrude Canada Ltd. (Fort McMurray, Alberta).
XRD analysis of oriented preparations (air dried-54 % RH and ethylene glycolated) of the < 0.2 µm fractions of the four end members showed that interstratified illite-smectite of high (~30 %) and low (~10 %) expandability were observed only in clay-rich end members, i.e., NM12-EC and MC, respectively. Kaolinite-smectite was only found in the < 0.2 µm fraction of the NM12-MC with an expandability between 5 and 10 %. Interstratification of illite-smectite was observed in the < 0.2 µm fraction of NM09-MC and EC samples, but the expandability was only 10 % for both fractions. ES and EC had the highest and lowest bitumen contents, respectively, for the NM12, NM09 and AM10 samples.
The second underpinning aim of this research was to determine the mechanism of preferential clay segregation during the solvent-based bitumen extraction process. Different adsorption amounts of hydrocarbon components by clay minerals, which is due to their different properties, may affect the processability of oil sands ore during the extraction process. However, due to the highly heterogeneous nature of the clay minerals in the oil sands, it is difficult to determine the effect of individual clay minerals on bitumen recovery when testing the whole ore sample. Artificial mixtures of bitumen with standard clay minerals (swelling and non-swelling clays) were prepared and the influence of individual clays on the extraction process was investigated.
Swelling clays are significantly affected by increasing RH; however, RH has minimal effect on non-swelling clays. After bitumen treatment, the residual organic carbon content increased and the cation exchange capacity (CEC) and SSA decreased for all samples. SEM observations showed that swelling clays formed larger aggregates than non-swelling clays, which was consistent with the decrease in SSA for the swelling clays.
The third aim of the study was to identify the most important species affecting the non-aqueous bitumen extraction process and bitumen quality. This investigation was carried out on four petrologic end member from NM12. Each end member was separately mixed with cyclohexane at a ratio of 40:60 (cyclohexane:end member), and the bitumen-cyclohexane solutions were collected at different settling times (1 min to 30 min). These solutions were analyzed to characterize the SFS and water content, as well as the bitumen content, using various analytical techniques.
XRD analysis showed that the SFS were composed of mainly kaolinite and illite after cyclohexane extraction from MC, MS, EC and ES. Although mixed layer expandable clay minerals were identified in the original clay end members (EC and MC), illite-smectite and kaolinite-smectite were not observed in the SFS of the bitumen-cyclohexane solutions obtained from the four petrologic end members. The SFS content and bitumen quality of the bitumen product were affected by the end member composition and settling time, respectively. Kerogen and/or asphaltene were also present in the SFS of end members based on the N/C ratio (>0.018). XRD and SEM analysis showed that the amount of large grains decreased with increasing settling time. The solids were mostly fine clay particles (kaolinite and illite) and were typically several microns in size.
- Graduation date
- Fall 2018
- Type of Item
- Doctor of Philosophy
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