Colorado Oil Shale Research Articles

A DTA study of some oxidation characteristics of Colorado oil shale

A DTA study of some oxidation characteristics of Colorado oil shale

Flow of curshed oil shale through circular orifices

The gravity flow of crushed Colorado oil shale from a 18 cm dia. glass column through flat circular and converging conical orifices was studied using high-speed cinematography. Factors tested were: (1) diameter of flat-entry and conical orifices, (2) three sizes of shale in one broad and two narrow distributions, (3) upward air velocity, (4) viscosity and surface tension of wetting liquids (one simulating hot shale oil), and (5) presence of up to three crossing tubes in the shale bed. Arching sometimes caused stoppage of flow with orifice-to-particle size ratios (D/W) as high as 7.25. No interparticle motions were visible at levels above about 1.5 column diameters from the orifice. Except when there was air flowing upward, discharge rates were not consistently different when the bed was full than at other levels while it emptied, but local mean velocities measured over 10 cm depth sections ranged widely, about 40% of the mean value. For the runs made with dry shales through flat orifices, the rate of discharge was proportional to the square of the effective opening, D-2W, rather than the 2.5 power reported by other workers for more uniform, smoother, rounder materials. In a flat-bottom vessel, crushed shale forms its own final entrance cone around the orifice, with an included angle of 90°. When conical throats with an included angle of 40° were inserted, flow rates were 50–100% higher. Shale 6 mm and larger that was wet with simulated shale oil flowed as well as dry shale. The presence of only 0.7% of very fine material in dry shale appears to have a lubricating effect, causing the shale to pack more tightly and flow faster.

Factors affecting the percussive drillability of Colorado oil shale

Factors affecting the percussive drillability of Colorado oil shale

Trace and minor elements in Green River oil shale (Colorado, U.S.A.), concentrated by differential density centrifugation

A combination of separatory and analytical techniques was used to investigate the chemistry of 3 major elements and 9 trace elements in fine-grained Colorado oil shale. The separatory procedure involved low-temperature ashing, followed by high-speed centrifugation in a liquid density-gradient column. The density gradient ranged from 2.0 to 2.9 g cm −3. Application of this combination of techniques to four samples of oil shale demonstrates the feasibility of separating micrometer-size mineral grains held tightly by carbonates and organic matter. We have defined the “maximum enrichment factor” as being the ratio of the maximum observed concentration of an element in a given density fraction of ashed sample to the concentration of the same element in the bulk ashed sample. Resulting values of the maximum enrichment factors range from 1.2 to 12 for various elements. Hierarchial cluster dendrograms reveal different mineralogical residences for the elemental groupings of: Ca-Fe-Mn; Cu-Pb-Ni; As-Zn; and Mo-F-K-Fe. Fluorine is concentrated in the 2.4- and 2.5-g-cm −3 fractions, in association with illite.

Regional resource management techniques: The case of Colorado oil shale development

Regions under stress from rapid development require comprehensive planning and management tools, capable of identifying the pace, location and magnitude of growth and assessing social, economic and environmental impacts. Northwest Colorado, endowed with massive rich deposits of oil shale, went through a boom-bust cycle of growth during the early 1980s as US interest in synthetic fuels peaked and then rapidly declined. An innovative resource information system has been developed which has assisted the region in anticipating growth and modifying its consequences. This article reviews the organization and development of the Colorado Resource Information System (CRIS) and evaluates its role and impact in the decisionmaking process. Experience shows that regions which develop and maintain planning and information tools can have significant influence on economic development.

Kinetics of decomposition of CaCo 3 in an Australian oil shale

The kinetics of decomposition of calcium carbonate in an Australian (Julia Creek) oil shale were measured because the extent of the carbonate decomposition affects the energy balance for combustors burning either raw or spent shale. The apparent activation energy was similar to that previously reported for the decomposition of calcium carbonate in Colorado oil shale but the Julia Creek shale had rate constants which were smaller than those reported for the Colorado shale.

Pyrolysis kinetics for Green River oil shale from the saline zone

The nature of the organic and mineral reactions during the pyrolysis of Saline-zone Colorado oil shale containing large amounts of nahcolite and dawsonite has been determined. Results reported include a material-balanced Fischer assay and measurements of gas evolution rate of CH 4, C 2H x, H 2, CO and CO 2, Stoichiometry and kinetics of the organic pyrolysis reactions are similar to oil shale from the Mahogany zone. X-ray diffraction and thermogravimetric analysis results are used to help determine the characteristics of the mineral reactions. Kinetic expressions are reported for dawsonite decomposition, and it is demonstrated that the temperature of dolomite decomposition is substantially lower than for Mahogany-zone shale because of the presence of the sodium minerals.

Electrical conductivity of Colorado oil shale to 900 °C

Electrical conductivity of oil shale from the Anvil Points Mine, Colorado was measured to temperatures > 900 °C with conductance bridges operating at frequencies from 100 to 100 000 Hz. The conductivity of low, intermediate and high grade oil shales (15,124,233 ml kg −1, respectively) is dependent on water content up to ≈ 100 °C. At ≈ 120 °C, values of conductivity at ≈ 10 −7 S m −1 are observed for all grades. A strong, time-dependent, increase in conductivity, beginning at ≈400 °C, marks the loss of light hydrocarbons and the formation of a conductive char. The frequency dependence of conductivity-slightly less than a decade increase in conductivity per decade increase in frequency over the temperature range 100–400 °C-vanishes at temperatures near 500 °C. At 600–800 °C, the conductivity of these oil shales reaches a maximum value which is as much as 10 8 times larger than the conductivity near 250 °C.

Adsorption of mercury by soils from oil shale development areas in the Piceance Creek basin of northwestern Colorado

Six soils from the Colorado oil shale area were exposed to different concentrations of mercury vapor from elemental mercury and red HgO for periods of up to 13 months. These exposures were at room temperatures and under field conditions similar to those in the Piceance Creek basin. Large quantities of mercury were adsorbed by all soils at room temperature. Moderate quantities were adsorbed under field conditions, the amount being influenced by soil characteristics and temperature. Seasonal decrease in temperature or removal of samples from mercury exposure resulted in mercury loss. The most important soil parameters controlling mercury adsorption are amorphous oxides in the clay-sized fraction, reducible iron and manganese, and surface area.

Multiphase Quantitative Analysis of Colorado Oil Shales Involving Overlap of the Diffraction Peaks

AbstractThe method of intensity ratios can be used for quantitative x-ray diffraction analysis even when none of the diffraction peaks of any phase can be individually resolved. The method uses intensity values from a finite number of discrete integration intervals and appropriate reference-intensity-ratios measured on a set of reference samples to yield a best fit composite pattern that is matched to the unknown by least-squares refinement. Solid-solution phases are analyzed by using multiple reference patterns and determining the best choice during the pattern matching procedure. The method may be extended easily to employ whole diffraction traces by using a large number of small intervals.

Gas evolution during pyrolysis of various Colorado oil shales

Rates of evolution of C0 2, CO, H 2, CH 4 and the C 2 and C 3 hydrocarbons during the pyrolysis of seven Colorado oil shales have been measured. These shales, which are from various depths at two different sites, yield 34–255 ¦ of oil per tonne raw shale (9–61 US gal of oil per short ton raw shale) and linear heating at a rate of 2°C min −1 was used for the retorting of all samples. The objective of the study is to monitor variations in gas evolution from shales of different organic content and from various stratigraphic and areal locations. Comparisons between shales from each site are made together with correlations with data from Fischer assays. A kerogen concentrate (mineral fraction removed by HCl-HF treatment) and retorted shale from a Fischer assay are also included. The ability of a kinetic model due to Campbell et al. to predict gas evolution is tested and it is found necessary to modify slightly some of the stoichiometric coefficients to obtain good agreement. The resultant kinetic model should adequately describe the gas and oil evolution behaviour of shale from the upper portion of the Green River formation.

Heats of combustion of retorted and burnt Colorado oil shale

Heats of combustion were measured for 12 samples of retorted and 21 samples of burnt Colorado oil shale originating from raw shales with grades that ranged from 13 to 255 cm/sup 3/ of shale oil/kg of oil shale. For the retorted shales, the heat of combustion was resolved into exothermic contributions from combustion of carbon residue and iron sulfides and endothermic contributions from carbonate decomposition and glass formation. Eight samples reported in the literature were included in this analysis. Variations in the first three constituents account for over 99% of the variation in the heats of combustion. For the burnt shales, account must also be taken of the partial conversion of iron sulfides to sulfates. Equations are developed for calculating the heat of combustion of retorted and burnt oil shale with a standard error of about 60 J/g.

Trace elements in the products by retorting Thailand and Colorado oil shales.

Trace elements in the products by retorting Thailand and Colorado oil shales.

Composition of leachate from surface-retorted and unretorted Colorado oil shale

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTComposition of leachate from surface-retorted and unretorted Colorado oil shaleKenneth G. Stollenwerk and Donald D. RunnellsCite this: Environ. Sci. Technol. 1981, 15, 11, 1340–1346Publication Date (Print):November 1, 1981Publication History Published online1 May 2002Published inissue 1 November 1981https://doi.org/10.1021/es00093a005RIGHTS & PERMISSIONSArticle Views114Altmetric-Citations19LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (980 KB) Get e-Alerts Get e-Alerts

Non-linear three dimensional mechanical characterization of Colorado oil shale

Non-linear three dimensional mechanical characterization of Colorado oil shale

Weathering Effects on Some Chemical and Physical Properties of Retorted Oil Shale

AbstractUnion B retorted Utah oil shale, Paraho retorted Utah oil shale, and Paraho retorted Colorado oil shale differed in texture, pH, and salinity. Physical breakdown of Paraho retorted Colorado oil shale particles was observed at the surface of columns exposed to field conditions in eastern Utah for 9 months, but no physical weathering was observed in the other two retorted oil shale types under the same conditions. Exposure to weather resulted in pH reduction of all three retorted shales but was most pronounced in the more highly alkaline Paraho retorted Utah oil shale. The finer particle (<2 mm) fractions tended to have lower pH values and higher electrical conductivities than the more coarse fractions, even when the latter were crushed to <2 mm. Freezing and thawing in the laboratory were very effective in causing particle breakdown of Paraho retorted Colorado oil shale. During weathering the large particles first separated along cleavage planes, followed by disintegration of the lamina.

Effects of gas environment on mineral reactions in Colorado oil shale

The effects of various sweep gases (N2, CO2, and H2O) on the decomposition and reaction of calcite and dolomite (ankerite) in Colorado oil shale is reported. The disappearance of reactants and formation of products in the temperature range of 500 to 900 °C is monitored by using powder X-ray diffraction. The results show that, over this temperature range, the effect of gas environment on the rate of silicate formation follows the order H2Oś>CO2ś>N2. The ‘final’ silicate-product phases are observed to be a mixture of melilite, diopside, and merwinite. Global reaction kinetics are developed that describe the rate of CO2 evolution during decomposition of dolomite and calcite in the presence of various partial pressures of steam. Such data are useful in numerical models of oil shale retorting. Finally, the implications of these results on processing and on environmental aspects of oil shale retorting are discussed.

Non-linear three dimensional mechanical characterization of Colorado oil shale

A comprehensive mechanical characterization program on Green River Formation oil shale from the Mahogany zone near Anvil Points, Colorado, produced prediction equations for the three-dimensional non-linear stiffness coefficients based on the organic volume and stress level as independent variables. These coefficients are useful in the mine design, fragmentation modeling, investigations directed toward creating in-place permeability, and so on. The stiffness coefficients and compressive strengths perpendicular and parallel to bedding planes are obtained from tested samples. Each sample set consists of two square prisms taken from the same horizon but cut perpendicular and parallel to bedding planes. The twelve non-zero coefficients in the stiffness matrix for oil shale are expressed in terms of the elastic constants consisting of Young's moduli and Poisson's ratios obtained from uniaxial compression tests on these square prisms. Dependency on stress levels makes it difficult to determine the coefficients by acoustical methods.

Gas evolution during oil shale pyrolysis. 2. Kinetic and stoichiometric analysis

Nonisothermal rate measurements for the evolution of H 2, CH 4, C 2 hydrocarbons and C 3 hydrocarbons during the pyrolysis of Colorado oil shale have been analysed using the recent kinetic theory of Antony and Howard AIChE J. 1976, 22, 625. This analysis yields a simple set of rate expressions, which can be used for modelling kerogen pyrolysis under typical retort heating conditions. A stoichiometric representation of kerogen pyrolysis is also developed. These results are then used to derive a simple mechanistic picture of oil shale pyrolysis between 25 and 900 °C.

Gas evolution during oil shale pyrolysis. 1. Nonisothermal rate measurements

The rate of evolution of CH 4, CO, CO 2, H 2, C 2 hydrocarbons, and C 3 hydrocarbons during pyrolysis of Colorado oil shale between 25 and 900 °C is reported. All experiments were performed nonisothermally using linear heating rates varying from 0.5 to 4.0 °C min −1. Hydrogen is the major noncondensable gas produced by kerogen pyrolysis. The amount of H 2 released is influenced, via the shift and Boudouard reactions, by the CO 2 evolved from mineral carbonates. Lesser amounts of C 1, C 2, and C 3 hydrocarbons are produced. On the basis of heat content, however, the combined C 1 to C 3 hydrocarbons contribute twice as much as H 2 to the heating value of the pyrolysis gas. The evolution of H 2 and CH 4 involves processes that are interpreted as a ‘primary’ pyrolysis of the kerogen to generate oil, and a higher temperature ‘secondary’ pyrolysis of the carbonaceous residue. The CO formed is a product of the Boudouard reaction; nearly complete conversion of the carbon residue to CO via this reaction is observed.