Influence of Nonswelling Clay Minerals (Illite, Kaolinite, and Chlorite) on Nonaqueous Solvent Extraction of Bitumen

Abstract

Artificial mixtures of bitumen with three natural clay standards, dominated by illite, kaolinite, and chlorite, were reacted for several days and washed three times each with cyclohexane to remove bitumen from the clays. The main goal was to determine and better understand the effect of nonswelling clay minerals (illite, kaolinite, and chlorite) on nonaqueous solvent bitumen extraction. The experimental results showed that the total amount of residual cyclohexane insoluble organic carbon (CIOC) measured for clay−bitumen mixtures after nonaqueous solvent bitumen removal is a function of intrinsic resistance of high molecular weight (MW) organic compounds to cyclohexane extraction and the nature of nonswelling clays. The intrinsic resistance of high MW organic compounds to cyclohexane extraction accounted for 42−80% of the total CIOC content. The nonswelling clays retained from 20 to 58% of CIOC of the total CIOC content primarily on the external surfaces (basal planes and edges) of clay mineral particles in the form of patches rather than continuous coatings. Cation exchange capacity (CEC) and specific surface area (SSA) were reduced by the reaction with bitumen due to organic coatings on the clay mineral surfaces and/ or due to bridging of clay particles to aggregates. The results indicate that the SSA is the primary controlling parameter affecting the amount of CIOC retained on the nonswelling clays within the studied experimental conditions. Higher amounts of CIOC resist on clays which have larger SSAs. CEC and layer charge density (LCD) are contributing parameters possibly affecting the extractability of bitumen from studied clays. It seems that, with increasing CEC and LCD, the CIOC was bonded more strongly to the clay mineral surface; consequently, more CIOC resisted nonaqueous solvent bitumen removal. ■ INTRODUCTIONThe Alberta oil sands deposits represent the third largest resource of bitumen on the planet after Venezuela and Saudi Arabia. 1 Commercial recovery of bitumen from the Alberta oil sands is achieved by water-based extraction processes. Alternative nonaqueous solvent extraction processes have been investigated since the mid-1960s due to their potential advantages such as high bitumen recovery, elimination of sludge tailings ponds, and decrease in water consumption. 2 The Alberta oil sands are a mixture of coarse sand, fine clays, bitumen, and water. Quartz is the principal mineral of Alberta oil sands along with a small amount of clay minerals, carbonates, feldspars, and traces of TiO 2 minerals and pyrite. 3 Kaolinite, illite, chlorite, and interstratified illite−smectite have been reported as the main clay minerals of Alberta oil sands. 3 Variability in ore composition is known to affect bitumen recovery from the oil sands. It has been recognized that the presence of clay minerals may have negative consequences on bitumen extraction. 4,5 However, different types of clay minerals may have differing effects on the processability of oil sands ore during the extraction process, likely due to their d...

Characterization of four petrologic end members from Alberta oil sands and comparison between different mines and sampling times

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Mineral Elements in the Raw Milk of Several Dairy Farms in the Province of Alberta

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