[en] The midyear purchase of Arco's US coal properties for 1.14 billion dollars gave Arch coal, Inc. (ACI) a string of surface and underground mines stretching from Wyoming's Powder River Basin to the coalfields of central Utah. The transaction created a new entity, Arch Western Resources LLC. The article describes operations at Black Thunder and Coal Creek surface mines and SUFCO, Skyline, Dugout Canyon and West Elk longwall mines. 4 photos

[en] Wetlands are especially important in semi-arid environments, such as the Powder River Basin of northeastern Wyoming, where water is a limiting factor for living organisms. Within this coal mining region of northeastern Wyoming, jurisdictional wetlands are mapped according to the US Army Corps of Engineers 1987 delineation procedure. Within the coal mining region of northeastern Wyoming, little or no full-scale mitigation or reconstruction attempts of jurisdictional wetland areas have been made until recently. Based on the importance of wetlands in a semi-arid environment and lack of information on existing or reconstructed areas, the specific objectives of the 1998 fieldwork were: (1) To define the pre-disturbance ecological state of hydric soils within jurisdictional sections of stream channels on two coal permit areas in northeastern Wyoming, and (2) To determine the effect that hydric soil parameters have on plant community distribution and composition within the two coal permit areas. Undisturbed sections of stream channels and disturbed sections of reconstructed or modified stream channels at the Rawhide Mine and Buckskin Mine, located north of Gillette, Wyoming, were selected for the study. Soils field and laboratory information and field vegetation cover were collected during 1998 within native stream channels and disturbed stream channels that had been reclaimed at each mine. Soils laboratory information is currently preliminary and included pH, electrical conductivity and sodium adsorption ratio. Results and statistical comparisons between soils and vegetation data will be presented

[en] The use of Energy and Environmental Research Center (EERC) modeling tools and improved analytical methods has provided key information in optimizing advanced power system design and operating conditions for efficiency, producing minimal air pollutant emissions and utilizing a wide range of fossil fuel properties. This project was divided into four tasks: the demonstration of the ash transformation model, upgrading spreadsheet tools, enhancements to analytical capabilities using the scanning electron microscopy (SEM), and improvements to the slag viscosity model. The ash transformation model, Atran, was used to predict the size and composition of ash particles, which has a major impact on the fate of the combustion system. To optimize Atran key factors such as mineral fragmentation and coalescence, the heterogeneous and homogeneous interaction of the organically associated elements must be considered as they are applied to the operating conditions. The resulting model's ash composition compares favorably to measured results. Enhancements to existing EERC spreadsheet application included upgrading interactive spreadsheets to calculate the thermodynamic properties for fuels, reactants, products, and steam with Newton Raphson algorithms to perform calculations on mass, energy, and elemental balances, isentropic expansion of steam, and gasifier equilibrium conditions. Derivative calculations can be performed to estimate fuel heating values, adiabatic flame temperatures, emission factors, comparative fuel costs, and per-unit carbon taxes from fuel analyses. Using state-of-the-art computer-controlled scanning electron microscopes and associated microanalysis systems, a method to determine viscosity using the incorporation of grey-scale binning acquired by the SEM image was developed. The image analysis capabilities of a backscattered electron image can be subdivided into various grey-scale ranges that can be analyzed separately. Since the grey scale's intensity is dependent on the chemistry of the particle, it is possible to map chemically similar areas which can also be related to the viscosity of that compound at temperature. A second method was also developed to determine the elements associated with the organic matrix of the coals, which is currently determined by chemical fractionation. Mineral compositions and mineral densities can be determined for both included and excluded minerals, as well as the fraction of the ash that will be represented by that mineral on a frame-by-frame basis. The slag viscosity model was improved to provide improved predictions of slag viscosity and temperature of critical viscosity for representative Powder River Basin subbituminous and lignite coals

[en] The construction of a commercial In-Situ Leaching (ISL) uranium mine at Smith Ranch in Wyoming, USA, is described. The uranium is being extracted from sandstones at a depth ranging from 137 to 305 m and the planned annual capacity from 1998 onwards is 970 tonnes of U₃O₈. In the ISL process, a mild alkaline lixiviate, a standard bicarbonate and carbon dioxide leach, is injected with oxygen into the aquifer and as it contacts the ore, the oxygen reacts oxidising the uranium to the +6 valence state. This then complexes with the carbon dioxide and water to form a soluble uranyl dicarbonate ion. The pregnant lixiviate is pumped up through a recovery well and the uranium is extracted from the fluid by ion-exchange. Details of the pilot testing, well completion and processing plant are given. (UK)

[en] This paper describes our initial evaluation of a process designed to produce premium-quality solid fuel from Powder River Basin (PRB) coal. The process is based upon our experience gained by producing highly-reactive, high-heating-value char as part of a mild-gasification project. In the process char containing 20 to 25 wt % volatiles and having a gross heating value of 12,500 to 13,000 Btu/lb is produced. The char is then contacted by coal-derived liquid. The result is a deposit of 6 to 8 wt % pitch on the char particles. The lower boiling component of the coal-derived liquid which is not deposited on the char is burned as fuel. The authors' economic alveolation shows the process will be economically attractive if the product can be sold for about $20/ton or more. The authors' preliminary tests show that we can deposit pitch on to the char, and the product is less dusty, less susceptible to reabsorption of moisture, and has reduced susceptibility to self heating

[en] The Nichols Ranch ISL Uranium Mine is located in the Powder River Basin of Wyoming, USA. The mine is owned and operated by Uranerz Energy Corporation (Uranerz); a U.S. corporation headquartered in Casper, Wyoming. Nichols Ranch started operations in April 2014 and is the newest uranium mine to go into production in the United States. The uranium being extracted is hosted in a sandstone, roll-front deposit at a depth ranging from 122 to 244 m (400 to 800 feet). The In-Situ Leach (ISL) mining method is employed at the Nichols Ranch mine which is the method currently being utilized at most uranium mines in the United States. Environmental permit applications for the Nichols Ranch mine were submitted to the appropriate regulatory agencies in late 2007. It required more than three and a half years to review and approve all the permits and licenses necessary to start construction of the mine. Construction of the mining facilities and the first wellfield started in late 2011 and was completed in late 2013. Mining results to date have been better than anticipated and Uranerz expects to reach its 2014 production target. (author)

[en] During the next decade it appears that utilities will have to effectively separate their power generation business from other regulated functions. Tighter restrictions of sulfur emissions will take effect in 2000 but, as of 1996 only 30 percent of US coal-fired electrical generating capacity had flue-gas scrubbers. New emission standards would likely accelerate the shift to low sulfur coal as the competitive pressures of power markets will restrict capital for investment. If power plants do not retrofit with scrubbers, then based on 1995 coal transactions data for Northern Appalachia, Central Appalachia, and the Illinois Basin, there is the equivalent of 216 million tons of annual shipments from these areas that will have to be replaced by low sulfur coal or be covered by emission permits. In the aggregate only 23 percent of the coal shipped in 1995 from these areas was shipped to power plants equipped with flue-gas scrubber systems. The purpose of this paper is to show the extent of the geographical shift in future coal production that could occur as the regulations are enforced. The paper initially discusses the deregulation of the electrical utility industry and the provisions of the 1990 Clean Air Act Amendments. Current composition and historical changes of markets for the four major coal-producing regions--Northern Appalachian, Central Appalachian, Illinois Basin, and Power River Basin--are examined. Data on sulfur content of the coal received at power plants from each of the four major coal-producing regions are presented and used to infer the quality of coal likely to be produced in the immediate future. For each market, volumes of coal used by power plants having flue-gas scrubbers are estimated. Based on these estimates and available low sulfur supplies in each market, the volumes of produced coal are calculated that will not meet the new Clean Air Act standards and will likely not be used in scrubber equipped power

[en] The Clean Air Act Amendments of 1990 (CAAA) required many utilities to sharply reduce sulfur emissions by January 1, 1995. This study describes and analyzes how the coal and transportation markets responded to this major development. The study focuses on five key coal supply regions and their associated transportation networks: the Uinta Basin (Colorado/Utah), Wyoming Powder River Basin, Illinois Basin, Monongahela region (Pittsburgh seam) and the central Appalachian region. From these regional studies, the report identifies key risk areas for future coal planning and general lessons for the fuels planning process. The study provides statistical information on coal production, demand, and transportation flows for each region. The analysis for each region focuses on developments which were generally unexpected; e.g., the relatively large volumes of medium-sulfur coal produced in the Illinois Basin and Monongahela region, the eastern penetration of Utah and Colorado coals, and the relatively modest growth in demand for central Appalachian coals. These developments generally worked to the advantage of utilities; i.e., medium- and low-sulfur coal was available at a lower price, in greater volumes and from a wider range of sources than many had expected. Utilities both took advantage of and helped to encourage these developments in the coal and transportation market. Looking ahead to Phase 11 strategies and future coal procurement, a major challenge will be to maintain the choice among supply and transportation alternatives which was so important to utility success in Phase 1. The report identifies rail transportation to be the major area of risk in most regions

[en] The paper presents the results of a dynamic nonlinear programming model of a mineral resource market with several features of heterogeneous quality in the mineral, links with related product markets, incorporation of institutional constraints, resource allocations for each year in the planning period, and analysis of outcomes under various severance tax rates. The model computes privately efficient competitive use paths to perform cost-benefit analysis of public mineral policies. Policy variables are evaluated for their impact on both private behaviour and public benefits. The application is to New Mexico's linked coal and electric power markets. Findings reveal that scarcity rents are currently 4% of coal's price, and peak at 27% in 43 years. Increasing the present 1 dollar/ton New Mexico severance tax to 11 dollars reduces current annual coal output by 25%, prolongs the life of the state's coal industry by three years, and increases discounted severance tax revenues by 850% or 4.2 billion dollars. 38 refs., 2 figs., 4 tabs

[en] The spectral emittance of deposits left by bituminous and sub-bituminous coals under oxidizing conditions have been measured in situ. Pulverized coal is injected into a down-fired entrained-flow reactor. Ash accumulates on a probe in the reactor effluent and radiation emitted by the ash layer is recorded using a Fourier transform infrared (FTIR) spectrometer. Values for the spectral emissive power emitted by the ash and the surface temperature of the ash are extracted from these data. These results are then used to calculate the spectral emittance of the deposit. The spectral emittances of ash deposits formed by burning Illinois no. 6 (bituminous) coal and Powder River Basin (sub-bituminous) coal were measured between 3000 and 500 wavenumbers. The spectral emittance of the deposit left by the bituminous coal has a constant value of approximately 0.46 between 3000 and 2400 wavenumbers. Between 2200 and 1200 wavenumbers, the spectral emittance of the deposit increases from approximately 0.47 to approximately 0.61. Between 1200 and 500 wavenumbers, the spectral emittance is relatively constant at 0.61. The spectral emittance of the deposit left by the sub-bituminous coal is also relatively constant between 3000 and 2400 wavenumbers at a value of 0.29. Between 2200 and 500 wavenumbers, the spectral emittance of deposits from the sub-bituminous coal increases from approximately 0.29 to 0.55. Differences between these spectral emittance measurements and those measured ex situ illustrate the importance of making in situ measurements. Band emittances were calculated using the measured spectral emittances, and band emittances of the deposits are reported as functions of temperature.