Shale elemental analysis

A hypothetical structural model developed by Yen (24) represented the organic components of Green River oil shale. The major components were isoprenoids, steroids, terpenoids and cartenoids. The common bridges consisted of disulfide, ether, ester, heterocyclic and alkadiene. Elemental analysis of typical oil shale samples has shown... 

In modern terms, asphaltene is conceptually defined as the normal-pentane-insoluble and benzene-soluble fraction whether it is derived from coal or from petroleum. The generalized concept has been extended to fractions derived from other carbonaceous sources, such as coal and oil shale (8,9). With this extension there has been much effort to define asphaltenes in terms of chemical structure and elemental analysis as well as by the carbonaceous source. It was demonstrated that the elemental compositions of asphaltene fractions precipitated by different solvents from various sources of petroleum vary considerably (see Table I). Figure 1 presents hypothetical structures for asphaltenes derived from oils produced in different regions of the world. Other investigators (10,11) based on a number of analytical methods, such as NMR, GPC, etc., have suggested the hypothetical structure shown in Figure 2. 

Fig. 1. Selected portable XRF element analyses for two pyrite masses and their shale host. The two masses, both 2 cm In diameter, are within 5 cm of one another but display different trace element contents, both from one another and from their silicate host. The shale matrix analysis Is taken between the two.

Human activities often mobilize and redistribute natural compounds in the environment to an extent that they can cause adverse effects. Much attention has been paid to the determination of trace of pollutant elements on account of their significant effect on the environment. The potential of USAL has been put into use in environmental element analysis. Thus, the US leaching of cadmium from coals and pyrolysed oil shale prior to ETAAS [56] resulted in a twofold increase in precision, better detection limits and decreased background absorbance in relation to total digestion. Cadmium has also been successfully leached with US assistance from ash samples with subsequent flow-injection coid-vapour atomic absorption spectrometry [57]. Additional examples include the leaching of germanium from soiis with an uitrasonic probe in 10 min [58] or that of lead from coal in 60 s [59]. 

Wortmann U. G., Hesse R., and Zacher W. (1999) Major-element analysis of cyclic black shales paleoceanographic implications for the early cretaceous deep western Tethys. Paleoceanography 114, 525-541. 

Organic petrography and organic element analysis reveal that the source of the kerogen is algal (lamosites dominating) while other maceral forms dominate locally to form carbonaceous shale and humic coals. 

TABLE I. ORGANIC ELEMENTAL ANALYSIS DATA FOR K- AND D-SERIES OIL SHALES... 

Analysis of the starting shale, retorting yields and conversions, elemental analysis of the oil and spent shale, and NMR analysis of the oil are summarized 1n Tables I-IV. 

Eastern U.S. oil shales are also sedimentary rocks. However, in contrast to Green River shales, the mineral constituents of Eastern U.S. shales are primarily silicates, with only about 1 wt% carbonate minerals. The bulk mineralogical composition of the Kentucky shale consisted primarily of quartz, illite and kaoli-nite, with some chlorite and pyrite. This is consistent with elemental analysis data which found the major mineral constituents to be Si, Al, Fe, and K. The elemental Ca concentration was less than 100 ppm. 

Table III. Elemental Analysis of Leachate Water Concentrations - mg/g Spent Shale...

Fracturing of Model Minerals. Further insight into the processes responsible for liquid SO2 fracturing of these shales is provided by the behavior of several minerals when subjected to liquid SO2. Authenic samples of calcite (crystals), dolomite (hard lumps), gypsum (hard lumps), and illite (hard lumps) were treated with liquid SO2 at 25°C for 2-5 hours after removal of the SO2, the treated minerals were heated for 2 hours at 100°C infrared spectra and sulfur analyses were then obtained. Calcite crystals developed numerous fine cracks and a fine powder flaked off. Although the powder contained no sulfur (elemental analysis) or S-0 moieties (IR spectra), the cracked crystals were shown to contain 0.18% sulfur in the form of sulfur-oxygen structures. Although these data are consisted with a 0.7% conversion via... 

The results of the elemental analysis show that asphaltenes derived from retorted shale oils have smaller values of H/C ratio and smaller oxygen and sulfur contents, but greater nitrogen content than that derived from shale bitumen. 

Figure 5a and Table la contain data for a set of samples taken from a 1500 m thick section of the Monterey shales. The kerogens were isolated (HCl, HCl/HF removal of carbonates and silicates and dilute nitric acid to remove the pyrite) for some of the core samples, but the total rock was used for the Rock Eval T ax determination to estimate maturation levels. The was measured for the extracted bitumen of each sample. The increase in T ax with depth is correlated with maturation indicating that burial of the samples increased their maturation. Two trends are indicated by the values one starts at +15.6 and increases to +17.7%o, and the second from +19.0 to +21.3%o. The data indicate that the bitumen produced at higher level of maturation is enriched with the heavier isotope. The elemental analysis of the bitumen shows that the shallowest (1400 m) sample has —11% S, whereas the deepest at 2490 m... 

Birge, W.J., J.A. Black, A.G. Westerman, and J.E. Hudson. 1980. Aquatic toxicity tests on inorganic elements occurring in oil shale. Pages 519-534 in C. Gale (ed.). Oil Shale Symposium Sampling, Analysis and Quality Assurance. U.S. Environ. Protection Agency Rep. 600/9-80-022. 

GER analysis incorporating element combinations designed to reflect the main minerals of the unaltered, altered and weathered rocks reveals clear separation of these different compositions and explains the mineralogical changes during alteration (Fig. 4). Unaltered shale compositions cluster toward the muscovite/ankerite node of the... 

Multivariate Analysts of Electron Microprobe-Energy Dispersive X-ray Chemical Element Spectra for Quantitative Mineralogical Analysis of Oil Shales... 

Analysis of Oil Shale Materials for Element Balance Studies... 

A Fischer assay simulates the conversion of oil shale to usable fuels in an above-ground retort. The results of an extensive program of chemical analysis of major and trace elements in spent shale, oil, and water collected from the Fischer assay of a standard oil shale are presented. The concentration of major elements in raw and spent shale can be determined only to 10% in this study. Two criteria show that fluorine and zinc may have been mobilized during the assays. The concentrations of arsenic and selenium in the Fischer assay retort water exceed the maximum permissible concentrations for drinking water. 

The focus of this research and other mass balance studies has been on trace elements (1,2,3). However, in future studies on speciation it will be necessary to know the concentrations of the elements present in amounts above 1%. Therefore, analyses of the oil shale and spent shale samples were performed for these elements. Atomic absorption and colorimetry were used for many of these analyses. Some major element results also were obtained by the broad-range instrumental analysis surveys. The comparison of the results obtained by the different techniques shows large discrepancies. 

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