This study is the first of two companion papers using hyperspectral data to generate predictive models of oil sand ore and froth characteristics as a potential new means for process control. In Alberta, Canada, shallow oil sands deposits are accessed by surface mining and crushed ore is transported to a processing plant for extraction of bitumen using flotation processes. The ore displays considerable variability in clay, bitumen, and fines which affects their behavior in flotation units. Using oil sand ore spanning a range of bitumen and fines characteristics, flotation experiments were performed to generate froth in a batch extractor to determine ore processability (e.g., separation performance) and froth characteristics (color, bitumen, solids). From hyperspectral observations of ore, models can predict the %bitumen content and %fines (particle passing at 44 and 3.9 µm) of ore but the models with highest r² (>0.96) predict the solids/bitumen of froth and the processability of ore. Spectral observations collected on ore upstream of the separation vessels could therefore offer a first order assessment of froth quality for an ore blend before the ore enters the plant. These models could also potentially be used to monitor and control the performance of the blending process as another means to control the performance of the flotation process. Full article

This is the second part of a study of predictive models of oil sand ore and froth characteristics using infrared hyperspectral data as a potential new means for process control. In Alberta, Canada, bitumen in shallow oil sands deposits is accessed by surface mining and then extracted from ore using flotation processes. The ore displays variability in the clay, bitumen, and fines content and this variability affects the separability and product quality in flotation units. Flotation experiments were performed on a set of ore samples of different types to generate froth and determine the ore processability (e.g., separation performance) and froth characteristics (bitumen and solids content, fines distribution). We show that point spectra and spectral imagery of good quality can be acquired rapidly (<1 s and <15 s, respectively) and these capture spectral features diagnostic of bitumen and solids. Ensuing models can predict the solids/bitumen (r² = 0.88) and the %fines and ultrafines (particle passing at 3.9 and 0.5 µm) content of froth (r² = 0.8 and 0.9, respectively). The latter model could be used to reject froth with a high solids content. Alternately, the strength of the illite-smectite absorption observed in froth could be used to retain all the samples above a pre-defined processability. Given that point spectrometers can currently be acquired for less than half the cost of an imaging system, we recommend the use of the former for future trials in operating environments. Full article

Starch-based flocculants have been emerged as a promising alternative to conventional synthetic flocculants in wastewater treatment, especially for the treatment of oil sand tailings, as they are low cost, safe, biodegradable, fairly shear-stable, readily available from reproducible agricultural resources, and do not result in secondary pollution. In this paper, three types of polymer-grafted starches (St-g-Polymer) with different charge properties were synthesized and their molecular structures were controlled by atom transfer radical polymerization (ATRP). The correlations between the charge properties of starch-based flocculants, external environmental parameters, and flocculation performance were systematically investigated by conducting jar tests under various environmental conditions. It was found that the charge properties of the branch chain had a significant impact on flocculation performance. The cationic St-g-Polymer demonstrated the best performance due to the grafting of the cationic monomer to the starch backbone which improved the solubility of the copolymer and aided in the removal of small/water-soluble particles. The results obtained could assist in guiding the selection and design of suitable biodegradable flocculants when treating targeted wastewater. Full article

A primary concern of commercial mined oil sands operations is the extent to which one can minimize the content of water and solids contaminants in the solvent-diluted bitumen products resulting from the bitumen production processes. During bitumen production, particles of about 2 µm or less may be responsible for the stabilization of water-in-bitumen emulsions that form during aqueous extraction of bitumen and purification of bitumen froth subsequently during the froth treatment processes, thus leading to the presence of those contaminants in solvent-diluted bitumen products. In this study, we separate and analyze sub-2 µm clay solids isolated from typical bitumen froth fed to a froth treatment plant at a commercial mined oil sands operation. Analytical transmission electron microscopy (TEM) with spatially-resolved energy-dispersive X-ray spectroscopy (EDX) and electron energy-loss spectroscopy (EELS) demonstrate key differences in morphology and composition between sub-2 µm clay aggregates with two distinct wettability characteristics: hydrophilic vs. biwettable particle surfaces. In particular, clay platelets with <200 nm lateral dimensions and thicknesses of a few atomic layers, which are intermixed within coarser sub-2 µm clay aggregates, are found to confer clear differences in morphological characteristics and wettability behaviors to the sub-2 µm clay aggregates. The <200 nm clay platelets found within sub-2 µm biwettable clays tend to arrange themselves with random orientations, whereas <200 nm clay platelets within sub-2 µm hydrophilic clays typically form well-ordered face-to-face stacks. Moreover, in biwettable sub-2 µm clay aggregates, <200 nm clay platelets often cover the surfaces of ~1–2 µm sized mineral particles, whereas similarly sized mineral particles in hydrophilic sub-2 µm clay aggregates, in contrast, generally have exposed surfaces without clay platelet coverage. These biwettable vs. hydrophilic behaviors are attributed to a difference in the surface characteristics of the <200 nm clay platelets caused by toluene-unextractable organic carbon coatings. Nanometer-scale carbon mapping reveals an inhomogeneous toluene-unextractable organic carbon coating on the surfaces of <200 nm platelets in biwettable clays. In contrast, hydrophilic clays have a significantly lower amount of toluene-unextractable organic carbon, which tends to be concentrated at steps or near metal oxide nanoparticles on clay particle surfaces. Mixing surface-active organic species, such as asphaltene, resin, or carboxylic organic acids of various types with inorganic solids can lead to a dramatically enhanced emulsion stability. Consequently, understanding the origin and characteristics of sub-2 µm clay solids in bitumen froth is important to (i) clarify their potential role in the formation of stable water-in-oil emulsions during bitumen production and (ii) improve froth treatment process performance to further reduce contaminant solids in solvent-diluted bitumen products. We discuss the implications of our results from these two perspectives. Full article