Zircon mineral solids concentrated from Athabasca oil sands froth treatment tailings: Surface chemistry and flotation properties

Zircon mineral solids concentrated from Athabasca oil sands froth treatment tailings were compared by X-ray photoelectron spectroscopy, infrared spectroscopy, and collector-assisted froth flotation before and after surface cleaning in a low temperature, radio-frequency oxygen plasma. Plasma cleaning was effective at removing a surface bound layer of organic matter having chemical markers consistent with bituminous fractions. Specifically, the observation of long-chain aliphatics, ester and ether linkages, aromatic indicators, and hydroxyls in the absence of carboxylic acid groups, suggested the surface organic layer was representative of asphaltene or resin. Supporting this interpretation was the identification of pyrrolic and thiophenic chemical states. Plasma degradation of the hydrocarbon component transformed the zircon particles from hydrophobic to hydrophilic as evidenced by their recovery in water/ethanol froth flotation tests. The cleaned zircon particles were subsequently collected in the froth using dodecylamine. This work explains the surface conditions responsible for the reporting of zircon to the froth treatment tailings and demonstrates the efficacy of plasma cleaning as a means to condition zircon for coupling with collector agents. A physical model of surface adsorption is discussed and process implications are considered. \ua9 2014 Published by Elsevier Ltd.Peer reviewed: YesNRC publication: Ye

Adsorption of methylene blue as a descriptor of C-S-H nanostructure

The adsorption of methylene blue (MB) on C-S-H surfaces (C/S ratios 0.60-1.80) and its dependence on C-S-H nanostructure was investigated. UV-VIS spectroscopy was used to obtain the adsorption-desorption isotherms at 23 \ub0C, 35 \ub0C and 50 \ub0C. The character of the UV-VIS spectra and the nature of the C-S-H-MB interaction are discussed. Several sorption models including those due to Langmuir, Harkins-Jura, Halsey, Henderson, and Freundlich are fitted to the data using a non-linear multiple-regression method. Factors influencing the sorption of MB by C-S-H are discussed. The results demonstrated that the adsorption of MB molecules on C-S-H strongly depends on the nanostructural characteristics of C-S-H. \ua9 2010 Published by Elsevier Ltd. All rights reserved.Peer reviewed: YesNRC publication: Ye

The interaction of methylene blue dye with calcium-silicate-hydrate

The interaction of Methylene Blue (MB) dye solution with various C-S-H preparations (C/S ratio = 0.60 to 1.80) was investigated. Experiments were also performed by treating the C-S-H in lime-saturated water and distilled water. The effects of MB on the X-ray basal-spacing and the degree of polymerization were determined using low angle X-ray diffraction and 29Si MAS NMR spectroscopy. An interaction mechanism for C-S-H-MB using a ?bridging? model for the C-S-H nanostructure is proposed. The model is consistent with the XRD and 29Si MAS NMR results.Nous avons examin\ue9 l?interaction de la solution de colorant au bleu de m\ue9thyl\ue8ne (BM) avec diverses pr\ue9parations de C-S-H (rapport C/S = de 0,60 \ue0 1,80). Par ailleurs, on a men\ue9 des exp\ue9riences en traitant le C-S-H dans de l?eau satur\ue9e de chaux et dans de l?eau distill\ue9e. Les effets du BM sur l?espacement basal aux rayons X et le degr\ue9 de la polym\ue9risation ont \ue9t\ue9 d\ue9termin\ue9s au moyen de la diffraction des rayons X (DRX) aux faibles angles et de la spectroscopie de r\ue9sonance magn\ue9tique nucl\ue9aire (RMN) \ue0 MAS (rotation \ue0 l?angle magique) portant sur le 29Si. Un m\ue9canisme d?interaction pour C-S-H-BM utilisant un mod\ue8le de \uab pontage \ubb pour la nanostructure de C-S-H est ici propos\ue9. Ce mod\ue8le est en harmonie avec les r\ue9sultats de la DRX et de la spectroscopie RMN \ue0 MAS portant sur le 29Si.Peer reviewed: YesNRC publication: Ye

Length change of C-S-H of variable composition immersed in aqueous solutions

The dimensional stability of C-S-H (with varying C/S ratios) in saturated-lime water, distilled water and a methylene (MB) solution was investigated in this study. Two distinct regions of C/S ratio exhibited maxima in length change versus C/S ratio curves generated from results in all three test solutions. Differences in behavior in all three solutions were minimal. It would appear that the C-S-H nanostructures that quickly form in MB solution are comparatively stable in aqueous media. Possible mechanisms for the length change behavior are discussed.La stabilit\ue9 dimensionnelle des hydrates de silicate de calcium (C-S-H) (pr\ue9sentant des ratios calcium/silicate [C/S] vari\ue9s) dans de l?eau de chaux satur\ue9e, de l?eau distill\ue9e et une solution de m\ue9thyl\ue8ne (MB) a \ue9t\ue9 examin\ue9e dans le cadre de cette \ue9tude. Deux (2) plages distinctes de ratio C/S ont pr\ue9sent\ue9 des maxima en termes de changement de longueur vs des courbes de ratio C/S g\ue9n\ue9r\ue9es \ue0 partir des r\ue9sultats obtenus dans les trois (3) solutions d?essai. Les diff\ue9rences de comportement dans les trois solutions \ue9taient minimes. Il semblerait que les nanostructures C-S-H qui se sont form\ue9es rapidement dans la solution de MB se r\ue9v\ue8lent relativement stables dans les milieux aqueux. On traite des m\ue9canismes possibles pouvant expliquer le comportement de changement de longueur.Peer reviewed: YesNRC publication: Ye

Optimizing XRF Calibration Protocols for Elemental Quantification of Mineral Solids from Athabasca Oil Sands

As world reserves of conventional oil keep decreasing, there is greater incentive to further develop the Athabasca oil sands of Alberta (Canada). Oil sands being composed of coarse sand, silt and clay solids (80-85%), bitumen (5-15%) and water (1-5%), complete extraction of bitumen from such heterogeneous mixtures is not easy. Studies have shown the adverse effects of some types of mineral solids on bitumen recovery. Quantitative analysis of the elemental composition of mineral solids in ores is then of great importance to the oil sands industry. Two calibration protocols were developed here and implemented for accurate determination of major and minor elements in oil-sand solids by wavelength dispersive X-ray fluorescence (WDXRF) analysis using a fusion-based procedure. Commercially available standards do not span the ranges of element concentrations found in the mineral solids from oil sands. As such, calibration standards for seventeen elements were then designed by mixing pure synthetic oxides or geological reference materials, in order to mimic the elemental concentrations of oil-sand solids fractions. Measurement conditions were optimized to ensure best signal-to-background ratio and minimum line overlap. The limit of detection, calibration ranges and uncertainty errors of the resulting calibration curves are reported, showing excellent precision and accuracy even without matrix-effects correction. Application to analyze a suite of oil sands samples showed that the elemental concentrations of Ti and Zr in problematic solids components correlated well with the concentration of these elements in the entire mineral solids content present in the ores. This observation might be relevant for the development of elemental compositions-based processability markers to identify problem ores yielding poor extraction performance in commercial operations.Peer reviewed: YesNRC publication: Ye

Optimizing XRF calibration protocols for elemental quantification of mineral solids from Athabasca oil sands

Peer reviewed: YesNRC publication: Ye

Colloidal clay gelation: relevance to current oil sands operations

Ultrafines are predominantly delaminated colloidal clays with dimensions <0.9um that exist naturally in oil sands and are released during conditioning of surface-mined ores. Critical concentrations of these ultrafines and the cations present in process water are capable of forming flocculated structures with a very high water holding capacity. During primary separation of bitumen these ultrafines are detrimental to recovery as a result of increased slurry viscosity as well as through slime coating of released bitumen. Disposition into tailings ponds eventually produces mature fine tailings (MFT) as a result of thixotropic gel formation that entraps coarser solids. The ultrafines concentration of ~3 wt% observed in MFT coincides with the critical gelation concentration determined for suspensions of ultrafines in salt solutions with cationic concentration representative of that in pond water. This observation accounts for 100% of the water holding capacity of MFT and also explains why virtually no water is released once an MFT gel state has been formed. Here, we review earlier research in this area and identify the harmful effects of ultrafines in some current problematic ores.Peer reviewed: YesNRC publication: Ye

Mineralogy of organic-rich solids from oil sands affecting processability

Peer reviewed: YesNRC publication: Ye

X-ray diffraction (XRD)-derived processability markers for oil sands based on clay mineralogy and crystallite thickness distributions

Peer reviewed: YesNRC publication: Ye