Mineral and trace element composition of the Lokpanta oil shales in the Lower Benue Trough, Nigeria

The concentrations of minerals and trace elements in the Lokpanta oil shale from the Lower Benue Trough, Nigeria have been determined by X-ray diffraction (XRD) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS), respectively. X-ray diffraction data were evaluated using the SIROQUANT™ interactive data processing system based on Rietveld interpretation methods. A new method of trace element determination in oil shale, involving LA-ICP-MS analysis of glass beads prepared by fusing oil shale ash on an iridium strip heater was used, and the accuracy of the method was assessed by including a standard shale reference material (SGR-1b) in the analysis program.The minerals in the raw oil shales are mainly quartz, calcite and clay minerals, with the latter being represented by kaolinite and interstratified illite/smectite. Ashes of the oil shale samples prepared at 815 °C have quartz and (in some cases) illite as the dominant mineral phases, along with a significant proportion of amorphous materials. The Lokpanta oil shales are highly enriched in some potentially hazardous trace elements, including V, Cr and Ni, when compared with oil shales from other deposits around the world. The results obtained for the trace elements in the reference material show that the LA-ICP-MS method described in this study is very accurate and precise for the determination of a wide range of trace elements in oil shales.     

Comparative assessment of the trace-element composition of coals,crude oils,and oil shales

A comparative analysis of the amounts of 42 trace elements in coals, crude oils, and oil and black shales was performed. The degree of concentration of trace elements by caustobioliths and their ashes relative to their abundance in argillaceous rocks and the Earth’s crust was calculated. Typomorphic trace elements were distinguished, of which many turned out to be common for the different kinds of caustobioliths in question. The trace elements were classified according to their concentration factors in different caustobioliths. The ash of crude oils is enriched in trace elements (Cs, V, Mo, Cu, Ag, Au, Zn, Hg, Se, Cr, Co, Ni, U) to the greatest extent (concentration factor above 3.5) and that of oil shales is enriched to the least extent (Re, Cs, Hg, Se). The ratios between typomorphic trace elements in general strongly differ from those in the Earth’s crust and argillaceous rocks and are not identical in different caustobioliths. Quantitative parameters that make it possible to calculate a change in these ratios on passing from one caustobiolith type to another were proposed and the relative trace-element affinity of different caustobioliths was estimated.     

Environmental data from bench-scale pressurized fluidized-bed hydroretorting of Eastern oil shales

As part of a three year programme to develop the pressurized fluidized-bed hydroretorting (PFH) process for Eastern oil shales, tests were conducted in laboratory-scale batch and continuous units as well as a bench-scale unit (45 kg h⁻¹) to generate a data base for six Eastern shales. Data were collected during PFH processing of raw Alabama and Indiana shales and a beneficiated Indiana shale for environmental mitigation analyses. The data generated include trace element analyses of the raw feeds and spent shales, product oils and sour waters. The sulphur compounds present in the product gas and trace components in the sour water were also determined. In addition, the leaching characteristics of the feed and residue solids were determined. The data obtained were used to evaluate the environmental impact of a shale processing plant based on the PFH process. This paper presents the environmental data obtained from bench-scale tests conducted during the programme.     

Potential volatility of trace metals in oil shales

Potential massive volatilization of trace metals from oil shales with a clay matrix is predicted on the basis of preliminary laboratory ashing tests. The role of carbonate matrix in suppressing volatilization intensity is demonstrated and some environmental implications are discussed.     

Effect of lignite addition and steam on the pyrolysis of Turkish oil shales

Steam was found to be a more effective sweep gas than nitrogen at low velocities in fixed-bed pyrolysis of Goynuk oil shale but, at higher velocities and in fluidized-bed pyrolysis, the differences were considerably less marked. Relatively small but significant synergistic effects were observed between lignites and the two oil shales investigated — Goynuk and Seyitomer — under static retorting conditions. These effects were more pronounced with large concentrations of oil shales but disappeared in fluidized-bed pyrolysis, where conversions are considerably higher because mass transfer limitations largely disappear.     

Electrical Resistivity of Coal and Oil Shales

The physicochemical properties of coal and oil shales are compared: specifically, the ash content, moisture content, porosity, and yield of volatiles. The electrical resistivity of the oil shales, lignite, and coal is compared, as a function of the temperature. On account of their large content of volatiles, lignite and oil shales are characterized by similar electrical resistivity.     

Characterization of the residual carbon in retorted oil shale by solid-state 13C n.m.r.

Cross-polarization and magic-angle spinning suggest that the aromatic carbons in oil shales are largely inert to thermal processes and instead are responsible for the carbonaceous residue obtained during retorting. These results are based on ¹³C n.m.r. measurements of the organic carbon distribution of oil shales, before and after Fischer assaying, and for oil shales of different grades, geographic location, geologic ages and formations. The n.m.r. measurements suggest further that measurements of the organic carbon distribution of oil shales heated to various temperatures have practical relevance, and that this information can be of value in discriminating between unconverted kerogen and residual carbon in heated oil shales.     

Characterization of shale oil solids removed by the high-gradient magnetic separation technique

The high-gradient magnetic separation (HGMS) technique has been previously shown to remove solid particles successfully from several types of shale oil. The nature of the separated solids was investigated in this study, principally by thermomagnetic measurements over the temperature range 4.2–1173 K and in applied fields up to 1600 kA m^?1. Several phase transformations were identified in the magnetization profiles as a function of temperature. These transitions varied depending on the particular sample, although the low-temperature behaviour was qualitatively similar for all the solids. The magnetization increased over the range of external field studied. The magnetometric data reflect the differences in composition of the different solid samples and indicate the general occurrence of a paramagnetic phase mixed with a trace amount of ferromagnetic component. The bulk mineralogy and elemental composition of the solids were similar to those of the oil shales prior to retorting. Relatively large concentrations of iron sulphides were identified.     

Oil shale as a promising source of raw materials for advanced solid fossil fuel technologies

Information on the chemical nature and structure of the organic matter of oil shale from different deposits, the composition and distribution of mineral impurities in the volume of oil shale, and the elemental composition of the organic matter is considered in this article. It was found that the composition and properties of oil shale from different deposits are essentially different, and significant differences can also be observed within the limits of a deposit. Oil shale from some deposits contain trace impurity elements such as uranium, molybdenum, vanadium, and rhenium. In a number of cases, the concentrations of such impurities are increased, and their extraction can be of industrial interest.     

Chemical and pyrolysis characteristics of two types of oil shale from the Condor deposit in Queensland,Australia

The Condor oil shale deposit contains two major seams: a brown seam of almost pure lamosite origin and a black, or carbonaceous, seam of mixed lignite—lamosite origin. These differences in origin of the organic matter in the shale are reflected in their pyrolysis characteristics and particularly in the chemical composition of the oil retorted from them. The brown shale was found to have oil and gas evolution profiles similar to those reported for shales from the Green River (Colorado) deposit and to give a highly aliphatic oil containing < 2 vol.% of phenols. In contrast, the carbonaceous shale showed gas and oil evolution profiles resembling those of coal, and gave an oil high (≈ 10–15 vol. %) in phenols typical of coal pyrolysis products.     

Principles of the production of valuable metal compounds from fossil fuels

The main methods for the production of potentially valuable elements from fossil fuels (petroleum and coal) are considered. A large body of factual data on this problem is analyzed based on the experimental and theoretical studies and the works of foreign and Russian scientists. The methods of the extraction of potentially valuable elements, in particular, Ge from coals and V from oils and petroleum products, are described. It is shown that, in addition to fossil fuels with the technological concentrations of potentially valuable elements, some by-products of the processing of caustobioliths are of interest for the recovery of these elements. These are mainly fly ashes, slags, and their mixtures trapped after the combustion or gasification of coals and oil conversion products and also after the utilization of overburden rocks and high-ash cleaning rejects by thermal methods. The minimum concentrations of a number of potentially valuable elements in fossil fuels are roughly estimated, at which oils and coals should be considered as complex raw materials for the use of their organic matter and the manufacture of the commercial compounds of valuable trace elements.     

Chattanooga Shale—An Important U. S. Mineral Resource

Abstract

Chattanooga shale, a major component of the eastern Devonian shales, covers a wide area from lower Kentucky through Tennessee and into northern Alabama. It contains sizable resources of oil and several critically needed metals. Leaching experiments with sulfuric acid have demonstrated that excellent trace metal solubilization can be obtained from hydroretorted Chattanooga shale, i.e. the solid residue remaining after the raw shale has been processed to produce oil and/or gas.     

Determination of shale oil yields by petrographic analysis

Rundle-type oil shales from five Australian deposits (Rundle, Stuart, Condor, Byfield and Duaringa) contain abundant lamellar alginite that is easily recognized using fluorescence microscopy. Shale oil yield, as determined by modified Fischer assay, is directly related to the volume per cent of alginite in the parent shales for each of the above deposits. Data provided show that interdeposit estimates of shale oil yield, based on alginite content, are more reliable than estimates based on specific gravity of the parent shales. Application of petrographic techniques should provide rapid assessment of the shale oil yield for other deposits with Rundle-type oil shale. The method requires initial calibration of alginite content, in a limited number of samples, with Fischer assays.     

Oil shales of Mongolia

The results of studies of organic matter of Mongolian oil shales are presented. The total amount of bitumens in the shales is less than 2 wt %, whereas the kerogen content is about 15 wt %. A high H/C value (1.5–2.3) and the prevalence of aliphatic over aromatic structures in the insoluble organic matter indicate the usefulness of these oil shales as both power generation fuel and raw material for processing into chemicals.     

Trace element partitioning during the firing of washed and untreated power station coals

The effect of coal washing on trace element content and combustion behaviour of four world-traded coals has been studied at rig scale. The inputs and process outputs from a 1 MW combustion test facility, including coal, bottom ash, suspended fly ash, retained ash and flue gas, have been analysed for a standard suite of 17 trace elements. The results suggest that although coal cleaning significantly reduces the total ash content of the coal, the concentrations of individual trace elements are not reduced proportionately. Combustion of the washed coals resulted in increased concentrations of trace elements in the fly ash, although total fly ash loadings were reduced. Cleaning appeared to have little effect on concentrations of gaseous trace elements in the flue gas. The partitioning of the more volatile trace elements such as mercury and selenium between the vapour and solid phase was influenced by the amount of excess oxygen in the furnace, presumably affecting carbon-in-ash levels.The results suggest that the coal cleaning undertaken for these experiments did not significantly reduce the emissions to atmosphere of trace elements. The ultimate emissions will be determined by the efficiency of the dust capture systems.     

草浆黑液降低稠油粘度的研究

将碱法制浆黑液与稠油混合，可明显降低稠油的粘度．用均匀设计法设计试验，讨论了黑液浓度、稠油酸值、水油比（体积）、温度及水的矿化度对稠油降粘作用的影响．结果表明，黑液浓度为5％～15％，酸值为3～4.5mg／g（KOH／油）时，体系粘度最低，在试验范围内，水油比越大，温度越高，矿化度越小体系的粘度越低．     

Pyrolysis behaviour of Australian oil shales in a fluidized bed reactor and in a material balance modified Fischer assay retort

The pyrolysis behaviour of several Australian oil shales was determined using the material balance modified Fischer assay and a bench-scale fluidized bed pyrolysis reactor, with nitrogen or steam as the sweep gas. The assay oil yield, which ranged from 5.3 to 15.7 wt% of the dry shale, did not correlate well with the organic carbon contents of the shales. However, under both assay and fluidized bed pyrolysis conditions, a shale of high kerogen H/C had high organic carbon conversions to oil. Compared with the Fischer assay, nitrogen pyrolysis gave 7 ± 4 wt% more oil for the shales studied, and steam pyrolysis gave 15 ± 4 wt% more oil for all shales except one, which showed a 35 wt% increase in oil yield. However, the oils from both nitrogen and steam pyrolysis had lower H/Cs, higher sulphur and nitrogen contents, and more high boiling point fractions than those from the Fischer assay. Nitrogen pyrolysis oils were of higher quality than those produced by steam pyrolysis. With steam as the sweep gas, much more hydrogen and hydrogen sulphide were produced for all shales; in most cases, there was also more carbon monoxide and less hydrocarbon gases.     

Measurement of thermal conductivity of Green River oil shales by a thermal comparator technique

A thermal comparator method has been developed for the measurement of the thermal conductivity of oil shales from the Green River formation. Oil shales from two locations in the above formation were studied. Measurements were carried out in the temperature range 25–350 °C on oil shales assaying between 28.3 and 333.0 ml/kg (6.8 and 79.9 U.S. gal/short ton). Predictive equations showing the variation of thermal conductivity with temperature and shale grade are presented. A simple model is proposed to explain the anisotropic effects observed in the thermal-conductivity values for heat flowing in directions parallel and perpendicular to the shale bedding planes. The relative merits of the thermal comparator technique are discussed in the light of techniques previously employed for the measurement of thermal-conductivity factors of Green River oil shales.     

巴西塞尔西培-阿拉戈斯盆地油气地质特征

对巴西塞尔西培-阿拉戈斯盆地的地层与沉积和石油地质等特征进行了综合研究。盆地的主要烃源岩为阿普第阶湖相高盐度灰质黑色页岩,主要油气储集层为上侏罗统粗粒河流相砂岩储层、下白垩统三角洲相与风成相砂岩、砾岩与砾质砂岩储层、上白垩统-古近系浊积砂岩储层,区域性盖层为Ibura段和Carmpolis段及上侏罗统页岩和蒸发岩,油气主要运移期和聚集期发生在渐新世及以后,同裂谷期地层的上段（地层-构造圈闭）以及裂后层系（Calumbi地层圈闭）为具备勘探潜力的有利目标段。