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In the conventional Hot Water Extraction Process bitumen is separated as a froth that is then diluted with naphtha and subjected to two stages of centrifugation. The resulting bitumen solution still contains residual water, dissolved salts and mineral solids. Before upgrading the solvent and other volatile components are removed by topping at 524°C. The salts and mineral solids remain with topped bitumen; their presence can lead to serious operational problems in the bitumen upgrading process. In the present work the solids associated with bitumen (8S) have been identified as mainly ultra-fine (nano sized) aluminosilicate clays coated with strongly bound toluene insoluble organic material having "asphaltene characteristics". It is proposed that these ultra-fine clays with their strong tendency to collee! at oil-water interfaces, are the key component responsible for the presence of intractable water and associated salts in bitumen froth.

Bitumen separated from Athabasca oil sands by the hot water extraction process (HWEP) contains residual salty water and inorganic solids. Because of their strong interaction with bitumen, the solids fraction has been designated bitumen associated solids, abbreviated as BS. The major constituent of BS is ultrafine, aluminosilicate, clay crystallites. There is a minor contribution from sulfur-and titanium-bearing minerals. The surfaces of BS particles are rendered asphaltene-like owing to the adsorption of polar, aromatic, toluene-insoluble organics. Most of these solids are removed when asphaltenes are precipitated during treatment of bitumen with solvents less polar in nature than the naphtha in current use. Owing to their bi-wettable surface characteristics, the BS are likely to occur in association with water droplets in the bitumen phase. These droplets, or clusters, have an asphaltene-like exterior and exist as a stable colloidal dispersion in the maltene component of bitumen. These factors explain the intractable nature of the water and solids remaining with bitumen after conventional froth treatment by dilution with aromatic naphtha followed by centrifugation. During fluid, or delayed coking of bitumen, most of the BS are removed with the coke. However, deposition of the carbon-rich solids may also contribute to fouling in reactor systems and catalyst deactivation in catalytic hydroprocessing. Also, ultrafine BS and salt particles may themselves become entrained in the volatile overhead liquids and cause corrosion and fouling in downstream process units. Dilution of bitumen froth with a less polar solvent than naphtha reduces the overall stability of asphaltene micelles in the maltene component of bitumen. Asphaltene then co-precipitates with the inorganic particles and water to form a "rag layer". This process yields bitumen of excellent quality, in terms of solids and water content. However, in some cases, the product losses are unacceptable relative to the conventional froth treatment approach using centrifugation. It is expected that bitumen recovery can be improved by identifying a solvent, or solvent blend, capable of selective flocculation and precipitation of the clay-water clusters while precipitating only a minor amount of asphaltene. Preliminary results show that this approach is a realistic proposition.(1) Hocking, M. B. The chemistry of oil recovery from bituminous sands.

Organic coated solids in Athabasca bitumen : Characterization and process implications Bensebaa, Farid; Kotlyar, Luba S.; Sparks, Bryan D.; Chung, Keng H.

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/npsi/ctrl?action=rtdoc&an=8934308&lang=en http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/ctrl?action=rtdoc&an=8934308&lang=frAccess and use of this website and the material on it are subject to the Terms and Conditions set forth at http://nparc.cisti-icist.nrc-cnrc.gc.ca/npsi/jsp/nparc_cp.jsp?lang=en NRC Publications Archive Archives des publications du CNRCThis publication could be one of several versions: author's original, accepted manuscript or the publisher's version. / La version de cette publication peut être l'une des suivantes : la version prépublication de l'auteur, la version acceptée du manuscrit ou la version de l'éditeur. For the publisher's version, please access the DOI link below./ Pour consulter la version de l'éditeur, utilisez le lien DOI ci-dessous.http://dx.doi.org/10.1021/ef8002203 Energy & Fuels, 22, 5, pp. 3174-3193, 2008 Ottawa, Ontario K1J 7C4, Canada, and Syncrude Canada Ltd., Edmonton Research Centre, 9421-17 AVenue, Edmonton, Alberta T6N 1H4, Canada ReceiVed March 28, 2008. ReVised Manuscript ReceiVed June 13, 2008 An X-ray diffraction (XRD) methodology has been developed for characterizing clays in unextracted oil sands. Application of the new technique to five estuarine and five marine ores directly identified three clay mineral properties that may impact bitumen recovery: (1) The specific surface area of illite was significantly greater for four oil sand ores identified as problematic in batch extraction unit tests. (2) The correlation of illite/kaolinite XRD peak area ratios with bitumen recovery produced a processability classification similar to that proposed in earlier work. (3) Significant amounts of chlorite, as measured by XRD, were observed only in marine oil sands; this may provide a means to distinguish marine from estuarine ores. A combination of XRD analysis on separated clays and laser diffraction determination of clay contents provided a quantitative estimate for the illite and kaolinite contents of the oil sands. Also, the contribution from ultrathin illite and kaolinite for each oil sand (i.e., the mass fractions of illite and kaolinite with crystallite thicknesses of 1-3 composite layers) was determined. This methodology thus provides a direct method for the determination of the ultrafines content in unextracted oil sands and obviates the necessity for the time-consuming wet chemistry technique for separation of this component. For the 10 oil sands analyzed here, ultrathin crystallites occurred almost entirely in the illite clay fraction. The amount of ultrathin illite was critical and closely matched the ultrafines concentration required to cause sludging (gelation) in the primary separation vessel, with concomitant loss of bitumen recovery during extraction.

Effect of particle size on the flocculation behaviour of ultra-fine clays in salt solutions Kotlyar, L. S.; Sparks, B. D.; LePage, Y.; Woods, J. R.