Mineralogical and chemical composition of petrologic end members of Alberta oil sands

Abstract

The Alberta oil sands ores are a combination of four petrologically different kinds of rocks, called “end members”, deposited in marine and estuarine sedimentary environments. The combination of the different end members affects the properties of the oil sands. Applying organic solvents for bitumen extraction from the oil sands is an alternative to the current commercial hot water extraction process. Certain minerals (mainly clay minerals) in the oil sands may affect processability of the ore during non-aqueous extraction.The aim of the present study was to perform mineral and chemical characterization of the four end members in order to better understand the mineralogical and geochemical factors affecting bitumen extraction and subsequent solvent recovery from the extraction tailings.The as-received end members and their different size fractions were examined using XRD, QXRD, FTIR, ICP-MS and C, H, N and S content analysis. The results revealed variable amounts of toluene insoluble organic carbon in the samples after bitumen removal. The amount was higher in the finer size fractions, indicating its association mainly with the clay minerals. Bitumen removal was the most effective in the coarse grained quartz-rich samples containing a minimal amount of the clay minerals. The four end members consisted of quartz, clay minerals (kaolinite, illite, mixed layer illite–smectite and chlorite), carbonates (calcite, dolomite and siderite), K-feldspar, TiO2 minerals (anatase and rutile) and pyrite. The highest relative amount of mixed layer illite–smectite was found in the finest fractions (<0.2μm). The expandability (SXRD) of illite–smectite was 10±2%. The quantitative mineralogical analysis correlated well with chemical composition analysis of the petrologic end members of the oil sands.