Athabasca fraction

Lithium isotopes do not fractionate as a result of redox reactions, but Li is preferentially partitioned into the fluid phase, whereas Li prefers sites in alteration minerals such as micas. The Li/ Li ratios of mica and chlorite in alteration zones around uranium deposits are higher and decrease to lower values with distance from the ore relative to background mica in the Athabasca Group sandstones. In barren areas, high ratios are rare and background ratios are dominant. When used together, the isotopic composition of uranium and lithium can be utilized to refine both the genesis of uranium deposits and as exploration tools. 

The chondrite-normalized REE patterns for basement-hosted uranium oxides are similar, except for a small variation of LREE abundances, indicating identical physico-chemical deposition conditions (T, pH, fluid composition) for the Eastern part of the Athabasca Basin basement. The previous REE distinction made between Ingress and Egress deposits (Fayek Kyser 1997) is not confirmed by the present study, because both types have similar REE abundance and fractionations, indicating the similarity of the sources and the processes for both deposit types. Thus, these results suggest... 

The paddle mill was used to study the effect of surfactant type on a solvent-aqueous-surfactant extraction scheme for the recovery of bitumen from Athabasca tar sand. n the experiments of Figures 4,5 and 6, bitumen recovered from the surface phases was measured as a function of the mole fraction of ethylene oxide in the surfactant and as a function of the extraction step in which the surfactant was added. The results are reported as the % of the total bitumen present in the surface fraction. The amount of surfactant used was that required to give a final aqueous concentration of 0.02% (w/v), but in different sets of experiments the surfactant was added at various stages in the process. 

After hot water extraction, crude bitumen is upgraded into synthetic oil fractions by either delayed coking or fluidized coking. A representative product yield from direct coking of Athabasca oil sand bitumen is provided in TABLE 12-7. 

Sulfur compounds in the gas oil fractions from two bitumens (Athabasca oil sand and Cold Lake deposit)> a heavy oil (Lloydminster) from Cretaceous reservoirs along the western Canada sedimentary basin, and a Cretaceous oil from a deep reservoir that may be mature (Medicine River) are investigated. The gas oil distillates were separated to concentrates of different hydrocarbon types on a liquid adsorption chromatographic column. The aromatic hydrocarbon types with their associated sulfur compounds were resolved by gas chromatographic simulated distillation and then by gas solid chromatography. Some sulfur compounds were further characterized by mass spectrometry. The predominant sulfur compounds in these fractions are alkyl-substituted benzo- and dibenzothiophenes with short side chains which have few dominant isomers. 

There is an increasing trend in the amount of saturates in the sequence Athabasca, Cold Lake, Lloydminster, and Medicine River. This trend is reversed for the biaromatic and especially for the polyaromatic-polar fraction. 

The chromatogram from the corresponding Lloydminster fraction, Figure 10, is similar to that from the Athabasca but appears to contain considerably more lower molecular weight benzothiophenes, particularly those with four methylene groups represented by peak 2. The Cold Lake fraction, Figure 11, is not well resolved but also shows peaks that match those from the other oils. 

The first polyaromatic polar fraction from the Athabasca oil was similar to the largest fraction in this class from the Lloydminster oil. All the simulated distillation chromatograms of the first polyaromatic polar fractions in the C region of the liquid chromatograms are shown in Figures 14-17. Sulfur peaks from the three oils are fairly well resolved,... 

Figure 18. Athabasca main polyaromatic-yolar fraction, SE-30 on Chromosorb W...

Fractions as Determined by Structural-Group Analysis Methods, Athabasca Oil Sands A Collection of Papers Presented to K. A. Clark on His 75th Birthday, Research Council of Alberta, Alberta, Canada, 1963. 

Long progressions of alkyl benzo- and dibenzothiophenes have been detected in the aromatic fraction of Athabasca oil sand bitumen, along with some higher aromatic thiophenes. 

Figure 1. IR spectrum of the sulfoxide and the corresponding sulfide fractions of deasphaltened Athabasca bitumen. (Reproduced with permission from Ref. 3. Copyright 1983 Pergamon Press Ltd.)...

Figure 3. z-Plots for the sulfoxide fraction of deasphaltened Athabasca bitumen as derived from FIMS (Figure 2). The z = -2, -4 and -6 traces have maxima at n = 13, 18 and 23, respectively. These substances differ by five carbon atoms (an isoprene unit) and one ring. (Reproduced with permission from Ref. 4. Copyright 1985, Alberta Oil Sands Technology and Research Authority.)...

Figure 5. Capillary GC trace of the sulfide fraction from Athabasca maltene. Peaks labelled Bn correspond to bicyclic terpenoid sulfides with n carbons. The tricyclic terpenoid Cis sulfide (Triis) is not resolved from the Bis sulfide. Peaks corresponding to the tetracyclic C23 sulfide (Tetra23) and the hexacyclic sulfides are indicated. (Reproduced with permission from Ref. 10. Copyright 1986, Pergamon Journals Ltd.)...

Figure 16. FIMS data for an Athabasca maltene fraction. The peaks marked with an asterisk correspond to a homologous series of benzothiophenes, 0S...

Addition of a low viscosity hydrocarbon solvent often extracts the oil from the water the extract layer of solvent and solute separates from the water. The large amount of solvent needed to separate emulsions of water in a viscous heavy oil is uneconomic because of the dilute solution needed to obtain a continuous water phase. Addition of solvent, possibly up to an equal amount, is reasonable and is desirable to reduce the viscosity sufficiently to pump and transport the heavy oil. A cheap aliphatic solvent— e.g.9 kerosene—is preferable, but bituminous oil fractions are much more soluble in aromatic solvents, particularly at temperatures near the ambient. However, the water and solid particles are not at acceptable limits even after much dilution, especially in the presence of fine particles as in some crudes from California and Venezuela and particularly from tar sands as those in Athabasca (Alberta, Canada). 

Fractionation of an asphaltene by stepwise precipitation with hydrocarbon solvents (heptane to decane) allows separation of the asphaltene by molecular weight. The structural parameters determined using the x-ray method (Table II) show a relationship to the molecular weight (16). For the particular asphaltene in question (Athabasca), the layer diameters (La) increase with molecular weight to a limiting value similar relationships also appear to exist for the interlamellar distance (c/2), micelle height (Lc), and even the number of lamellae (Nc) in the micelle. 

McKay s solvent sequence completely eluted the Wilmington asphaltenes but did not elute all the Athabasca asphaltene samples and had to be extended by additional solvent mixtures to obtain good sample recoveries (cf. Figure 2). For large scale preparative separations of asphaltenes, the asphaltenes were dissolved in benzene and eluted with the same solvent, omitting the cyclohexane step. This accelerated the operation, but at the same time, as expected, the percentage of the neutral fraction now increased from 20%-21% to approximately 28%-30%, in reasonable agreement with the bulk results from the cyclohexane experiments (see Table III). Table III also shows the additional solvent systems used. 

The separation of resin acids and bases has been described previously (II, 12), see also comments in (14). The percentage of resins, as determined for deasphaltened Athabasca bitumen by their separation on an Attapulgus clay column, was 34%, while combined acids, bases, and Lewis bases amounted to 25.9% of the whole bitumen. Thus, 8.1% of material retained as resins on Attapulgus clay did not interact with the ion exchangers or the complexation column and appeared in the polyaromatic fraction. The distribution of material within the resin fraction was 46.1% acids, 21.9% bases, and 32% neutral compounds. Thus, the pattern of acid and base distribution is similar for the resins and asphaltenes, except for a higher proportion of neutral material present in the resins. 

Table IV. Analyses and Element Ratios of Athabasca Asphaltene Fractions from Ion Exchangers...

Figure 3. FT-IR spectra of Athabasca asphaltene acids fractionated on A-27 ...

A study of MW distribution for precipitated asphaltenes and the derivation of conclusions about bitumen or asphalt properties from it has severe limitations since this complex mixture exhibits a considerable overlap of GPC curves for all the fractions obtained in a conventional separation procedure. Similarly, the resins separated on clay and the eluted hydrocarbons exhibit overlap, as shown by Figures 5 and 6. Figure 5 demonstrates the GPC profiles of Athabasca asphaltenes (nC5) and resins (Attapulgus clay—total resin eluent)... 

Figure 6. Gel permeation chromatograms of Athabasca mal-tene fractions separated on At-tapulgus clay into hydrocarbons, resins-I (Rt), and resins-II (R2) columns, 30 cm x y/ ii-Styragel 500 + 30 cm x l/2" p-Styragel 100 solvent, CH2Cl2 UV detector PhMe - V of toluene PS (15,000) - V0.

For the sake of completeness a series of Athabasca asphaltene-derived bases was chromatographed using the same column system and solvent sequence for elution and compared with the bases from the resin fraction of the same bitumen. These results are shown in Figure 8. First, the highest MW fraction of the asphaltenes was the tetrahydrofuran/i-propylamine fraction (6500 by VPO). This is one of the fractions that could not be eluted from the column by benzene/methanol/i-propylamine. Apparently, tetrahydrofuran/ t-propylamine is hardly a more polar solution than benzene/methanol/ i-propylamine. In cation exchanger chromatography, the decisive component... 

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