The comparison of bitumens from oil sands with different recovery profiles

It has been proposed that, regardless of origin, the recovery of bitumen from oil sands is related to its viscosity. Asphaltene and resin contents are known to affect the viscosity of bitumen. In this article we compare the composition of solvent-extracted bitumens from several Athabasca oil sands with very different recovery profiles. After careful removal of any associated mineral matter by ultra-centrifugation, each bitumen sample was separated into saturate, aromatic, resin, and asphaltene (SARA) fractions by an enhanced SARA technique. The individual components were then characterized by several complementary analytical techniques, including carbon, nitrogen, nitrogen, sulfur, size exclusion chromatography molecular weight (MW n) plus proton and 13C nuclear magnetic resonance spectroscopy. Based on this comparison, we see no correlation between the recovery of bitumen and its composition. \ua9 Crown Copyright.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