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"Far from being eclipsed by petroleum and natural gas, Canadian coal continues to command wide (and apparently growing) interest.Major R & D investigations are currently heavily oriented toward coal beneficiation (e.g., cleaning and utilization of fines) and toward a broad range of studies on metallurgical coals and cokes. However, active work is also being carried out in the areas of coal geology, mining, transportation and combustion; and, in some laboratories, increasing stress has been laid on developing a number of new, essentially non-fuel uses for coal and coal products.This review summarizes the work of Canadian coal research agencies during 1966 and indicates some of the more important advances made by them."

Jan 1, 1967

By Morgan M. Sears, Mark Van Dyke, Gamal Rashed, John Rusnak, Khaled Mohamed

"In 2016, room-and-pillar mining provided nearly 40% of underground coal production in the United States. Over the past decade, rib falls have resulted in 12 fatalities, representing 28% of the ground-fall fatalities in U.S. underground coal mines. Nine of these 12 fatalities (75%) have occurred in room-and-pillar mines. The objective of this research is to study the geomechanics of bench room-and-pillar mining and the associated response of high pillar ribs at overburden depths greater than 1,000 ft. This paper provides a definition of the bench technique, the pillar response due to loading, observational data for a case history, a calibrated numerical model of the observed rib response, and application of this calibrated model to a second site. INTRODUCTION Bench mining is a an underground mining technique typically applied to room-and-pillar mines where full seam extraction on development presents an unacceptably high risk of injury from high pillar ribs or where the mining equipment is not designed to extract the full seam thickness. To mitigate the increased risk associated with high ribs and slender pillars, a more modest thickness is extracted from the top of the seam on development. This is followed by grading the floor and recovering the bottom of the seam with or without extraction of the pillars during retreat mining. A mine located in Eastern Kentucky extracts two seams at depths ranging from outcrop to 2,000 ft. In some areas of the mine, Seam A and Seam B are close enough together to be mined simultaneously. Seam A (top) is mined on development 7 to 9 ft. high for the entire length of the panel. On retreat, as each pillar is extracted, the continuous miner is ramped down into the floor (Seam B), two pairs of Mobile Roof Support (MRS) units are set, and the pillars are extracted at the full mining height of 14+ ft. During the pillar recovery process, the floor is extracted in each entry, from a ramp initiated outby the retreat line, sequentially just prior to extracting the lifts from the pillars (see Figure 1)."

Jan 1, 2017

By S Hayton

While coal seam gas is considered to be an unconventional gas, the proliferation of areas under exploration and development mean that it is rapidly becoming main stream. The potential of New Zealand's coals to produce coal seam gas has been recognised for some time. However, key market drivers have not been suitable for the progression of this potential into reality. Kenham Holdings Ltd and CRL Energy Ltd, recognising the potential for the gas in New Zealand have initiated what is the largest ever assessment of New Zealand's coal seam gas potential. The premature demise of the giant Maui field has raised the focus of new gas developments and has increased interest in what we are doing. Over the past couple of years Kenham Holdings Ltd and CRL Energy Ltd have approached the assessment of the coal seam gas potential in a staged programme. Preliminary assessment of the data on the permit areas indicates that the potential resource may be up to 500 PJ. To date, preliminary appraisals have been completed or are underway on a significant number of fields. Exploratory drilling has been completed or initiated on several of those fields, with results from this work being fed into the preliminary modelling as it has become available. Given that in many of these areas there is no pre-existing information concerning their gas potential and world wide experience with lignite is practically nonexistent, it has been a steep learning curve with many surprises. However, initial gas content results and preliminary gas flow models have been on the whole, rather pleasing, with the commerciality of some developments already apparent.

Jan 1, 2003

By McCarthy. Richard E.

The prime movers of the Centralia Project, the surface coal mine and the power plant, private utilities are very aware of public attitudes. They have established and maintain the reputation for leadership in public service and are genuinely concerned that this project initiate the pro-grams and design the hardware to answer the question :What will be the impact of the mine and the plant on the physical environment, i.e., the air, soil and the water." So in the beginning almost as soon as the decision had been made to go ahead with the project, officials of the two private utilities, Washington Water Power and Pacific Power & Light went on record and publicly stated time and again that the overall approach of the Operators would be to do all that was reasonably possible to safeguard the environment. This attitude became part of the thinking of the project planners, part of the design of the power plant and part of the plan for the surface mine. The coal to be mined is from the Skookumchuck formation. The formation is Late Eocene and is made up of poorly consolidated marine and non-marine deposits. The major overburden removal equipment is a bucket-wheel excavator -conveyor system and a 56 yard dragline. Mining of the coal will be done with truck and shovel. The coal is processed, washed and crushed to 1 ¼ " for delivery to the power plant. The muddy water created by the washing process is chemically treated and the solids removed by a thickener-vacuum filter system.

Jan 1, 1971

By J. O. Pitts

"Background The preponderance of Canada's coal resources is located in areas remote from high demand domestic users and at some significant distances from deepsea ports. This places great demands on the transportation system and has forced the coal and the transportation industries to adopt highly efficient methods of handling the product and hauling it to market position. Most of the coal not consumed in minemouth thermal power stations is carried by rail over lines operated by the two transcontinental railway systems, Canadian National and Canadian Pacific. These rail networks are extensive and have the advantage (as compared to most other North American railways) of being able to handle coal movements from origin through to destination without interchange to other rail carriers. Coal SourcesWith exception of the coal produced in Cape Breton, Nova iScotia, all the significant shipping volumes in Canada emanate ifrom mines located in the three most westerly provinces. Figure I ishows the geographic distribution of the major mining operaitions shipping coal to domestic and export markets. The prinicipal routes and the tonnages carried (1980 calendar year) are ialso indicated. iThe 1980 shipping data are summarized in Table I. Saskatchewan lignite began moving from Bienfait to Thunder Bay by CP Rail unit trains in mid-1981 at the rate of one million tonnes per year. The product is handled through Thunder Bay Terminals and delivered directly to a nearby Ontario Hydro electrical generating station."

Jan 1, 1985

By Brook W. H

The history of the reduction of iron from its ores is lost in antiquity. Archreologists state that man has practised it for over four thousand years. Until comparatively recent times charcoal was the principal reducing agent for making metallic iron from its various oxidised ores. Coke was first used by iron founders in England in 1619, and its use spread gradually throughout the civilised world from then onwards. Indeed, the destruction of forests to obtain the requisite charcoal made the iron founders, both in England and America, extremely unpopular, and this hampered the iron industry to a considerable extent, until coal provided the metallurgist with a new and better fuel--coke which is used by most pyro-metallurgists today. The transition from wood to coal products for iron smelting had a profound effect on the location of iron works. Particularly was this the case in America where, in the infancy of the industry, practically each of the early States had its own iron producers, but as coal and coke replaced charcoal, there came about a concentration of the iron and steel industry around the coking coal deposits, and so today there are huge steel plants clustered around the soft coal basins in Pennsylvania and Illinois.The development of the iron and steel industry in Australia, which is comparatively recent by world standards, has been cradled in the coal basins of New South Wales. The first steel works of any consequence in this country were built near Lithgow, close by the mines which produced the coal for coking.Incidentally, these works were rather unique in that the three essential materials for iron and steel manufacture-ore, coal, and limestone-were found virtually at the works' back door.When, in 1912, the location of the proposed steel works for The Broken Hill Pty. Co. Ltd. for smelting ore from Iron Knob in South Australia was considered, the site ultimately chosen was at Newcastle, almost on top of seams of satisfactory coking coal. One of the major factors which had determined the site of the steel works was the fact that, about 1912, three tons of coal were required to produce one ton of finished steel product, and the relative economics of ore and coal haulage were much in favour of bringing ore to the coal.

Jan 1, 1947

By Gene M. Handel

Today the world is heavily dependent on petroleum for its energy. In the United States, over 75% of the primary energy used comes from petroleum. Other developed countries are similar. The less developed countries have a lower dependence on petroleum just as the United States did through the early 20th Century. However, these less-developed countries look upon petroleum as one of the primary energy sources for the economic growth required to improve their standard of living. So everyone considers petroleum an essential ingredient in the recipe for the good life. But there is a substantial problem with this recipe, and it is finally getting general recognition. Petroleum is a finite resource, and the world is using it up at a rapid, accelerating rate. Though it won't be exhausted for many decades, the early warnings of ultimate limits have already appeared. The suppliers of the incremental production in the Middle East have threatened to restrict increases in their production rates. And, of course, the short term embargo of four years ago clearly demonstrated the economic impact of reduced access to petroleum as a primary source of energy. World petroleum production will probably peak in. 10 to 15 years and then start declining. When that happens, economics--the allocation of scarce products (also known as the dismal science for obvious reasons)--indicates that the price of petroleum will escalate in real terms. So that's the situation today. We have a serious and growing problem facing us that could substantially alter the quality of our life over the next 25 years. Recognition that the society may face a period of lowered expectations after a long period of upward mobility will be a painful experience, but it is certainly not the moral equivalent of war. And, besides, we have time to take positive actions to avert the most serious consequences. When we consider alternate energy sources, the possibilities are almost endless: coal, oil shale, tar sands, solar, fission, fusion, wind, tides, biomass, etc. Actually, the list is endless because new possibilities are continually being proposed. Of these possibilities, coal uniquely stands out as an attractive substitute for petroleum. Coal can be, and is, burned to generate electricity and provide heat. It can be liquefied to supplement the liquid fuels from petroleum, and it can be gasified for use as synthetic natural gas. Unlike exotic alternate energy such as solar and fusion, coal has successfully been used commercially to produce synthetic fuels. But, the technology does need to be refined and modernized. Thus, coal's role is not to be "America's Ace in the Hole," but to bridge the transition from primary dependence on petroleum for energy to the utopia of renewable sources of energy. But don't be mislead by the prophets--those renewable sources of energy are going to be very, very expensive when they are invented.

Jan 1, 1978

By J. Keith Haddock

"Introduction The Coal Valley Mine is operated by Luscar Stereo (1977) Ltd. with the Alberta Energy Company having a minority interest. The mine produces 2.0 million tonnes of bituminous thermal coal per year. Deliveries include 1.5 million tonnes to Ontario Hydro and 0.5 million tonnes to the export market via bulk handling facilities on the west coast near Vancouver, B.C. There are a number of mining methods utilized at the mine including open-pit by truck and shovel, strip mining with large draglines and stripping with scrapers. The mine is located 100 km south of Edson, Alberta. Geology The coal measures are concentrated within a 210-metre int~rval of the Paleocene section. The coal seams were originally named by the mining companies in the earliest days of development of the area and these names continue to be used today. Of the five main seams, only three are presently economic to mine based on quality, thickness and depth of cover. These are the Val d'Or, Upper Silkstone and Mynheer. The Coal Valley Mine is located in the structurally deformed foothills area of Alberta and the structure of each mining area is therefore very complex. The general bedding strike is 305 degrees azimuth but major thrust faulting and folding has extensively deformed the natural seams as a closer examination will show. The Mynheer Seam, located at the base of the coal measures, ranges in thickness from 5 m to 10 m and has numerous bentonite and shale partings. Because of inherent geological features, the Mynheer Seam has been subdivided into two zones, the Mynheer 'A' and the Mynheer 'B', and the mining of coal in these zones has necessitated the utilization of distinctly different mining methods. The structural regime of the Mynheer 'A' zone consists of an overturned asymmetrical anticline crest containing a steeply dipping major thrust fault which has raised the seam above the present topographic level. Further extensive shearing and rotation of the coal has resulted in the coal taking a 'pod' shape. The Mynheer 'B' Zone is a continuation to the southeast along strike from the Mynheer 'A' Zone. The bedding dips to the southwest at an average of 12 degrees and is interrupted at the south end by a transverse fault and to the north by its outcrop at the surface."

Jan 1, 1985

By J. R. Nawrot

Reclamation of potentially acid producing coal processing waste requires a 4-foot cover, and/or treatment to allow vegetation establishment. If not planned properly, soil covering alone does not prevent refuse acidification or formation of acid seeps. Adequate neutralization enhancement prior to soil covering can maintain an alkaline environment in the soil refuse interface and prevent acidification. Direct vegetation establishment using only limestone amendment (without soil cover) can successfully reclaim aged and weathered fine (Blurry) and coarse (gob) refuse if adequate neutralization treatment is provided for the oxidized surface zone. Acid seeps, representing an "after-the-fact" verification of an imbalance of acid-base equilibrium may also be corrected using upslope alkaline recharge techniques. Concentrated alkaline recharge pools have been constructed above previously soil covered acid gob at the Peabody Will Scarlet Mine to abate acid seeps. Preliminary monitoring results (1989-1992) from a concentrated alkaline recharge pool demonstration project in the Pit 4 area of the Will Scarlet Mine have documented a 50 to 80 percent reduction in acidity in the principal recharge pool groundwater zone. A 22% reduction in acidity has occurred in the primary seeps located downslope from the alkaline recharge pools. The initial improvements in water quality are seen as a positive indication that groundwater acidity will decrease further and amelioration of the acid seep will continue.

Jan 1, 1993

By W. Weissberger, Frankiewicz, L. Pommier

Introduction In the U.S., about one-quarter of the fuel oil and natural gas consumption is associated with power production in utility and industrial boilers and process heat needs in industrial furnaces. Coal has been an attractive candidate for replacing these premium fuels because of its low cost, but there are penalties associated with the solid fuel form. In many cases pulverized coal in unacceptable as a premium fuel replacement because of the extensive cost of retrofitting an existing boiler designed to burn oil or gas. In the cases of synthetic fuels from coal, research and development still have a long way to go and costs are very high. Another option, which appears very attractive, is the use of solid coal in a liquid fuel form - coal slurry fuels. Occidental Research Corp. has been developing coal slurry fuels in conjunction with Island Creek Coal (ICC), a wholly-owned subsidiary. Both coal-oil mixtures and coalwater mixtures are under development. ICC is a large eastern coal producer, engaged in the production and marketing of bituminous coal, both utility steam and high quality metallurgical coals. There are a number of incentives for potential users of coal slurry fuels and in particular for coal-water mixtures (CWMs). First, CWM represents an assured supply of fuel at a price predictable into future years. Second, CWM is available in the near term; there are no substantial advances in technology needed to provide coal slurry fuels commercially. Third, there is minimal new equipment required to accommodate CWM in the end-user's facility. Fourth, CWM is nearly as convenient to handle, store, and combust as is fuel oil. Several variants of CWM technology could be developed for different end-users in the future. One concept is to formulate slurry at the mine mouth in association with an integrated beneficiation process. This slurry fuel may be delivered to the end-user by any number of known conveyances such as barge, tank truck, and rail. Slurry fuel would then be stored on-site and used on demand in utility boilers, industrial boilers, and potentially for process heat needs or residential and commercial heating. An alternative approach is to formulate a low viscosity pre-slurry at the mine mouth and to pipeline it for a considerable distance, finishing up slurry formulation near the end-user's plant. Finally, at the other extreme of manufacturing alternatives, washed coal would be shipped to a CWM manufacturing plant just outside the end-user's gate. Depending on fuel specifications and locations of the mine and end-user facility, any of these alternatives may make economic sense. They are all achievable in the near term using existing technology or variants thereof. The Coal-Water Mixture CWMs contain a nominal 70 wt. % coal ground somewhat finer than the standard pulverized ("utility grind") coal grind suspended in water; a complex chemical additive system gives the desired CWM properties, making the suspension pumpable and preventing sedimentation and hardening over time. Figure 1 shows the difference between a sample of pulverized coal containing 30 wt. % moisture and a CWM of identical coal/water ratio. The coal sample behaves like sticky coal, while the CWM flows readily. The combustion energy of a CWM is 96-97% of that associated with the coal present, due to the penalty for vaporizing water in the CWM. Potentially any coal can be incorporated in the CWM, depending on the combustion performance required and the allowable cost. CWMs are usually formulated using high quality steam coals containing around 6% ash, 34% volatile matter, 0.8% sulfur, 1500°C (2730°F) initial deformation temperatures, and energy content of 25 GJ/t (21.5 million Btu per st). Additional beneficiation to the 3% ash level can be accomplished in an integrated process. There are a number of minimum requirements which a satisfactory CWM must meet: pumpability, stability, combustibility, and affordability. In addition, a CWM should be: resistant to extended shear, generally applicable to a wide variety of coals, forgiving/flexible, and compatible with the least expensive processing. It was found that a complex chemical additive package and control of particle size distribution are necessary to achieve these attributes simultaneously, while maximizing coal content in the slurry fuel. Formulation of Coal-Water Mixtures A major consideration in the manufacture, transportation, and utilization of a slurry fuel is its pumpability, or effective viscosity. Most CWM formulations are nonNewtonian, i.e., viscosity depends on the rate and/or duration of shear applied. Viscosities reported in this paper were obtained using a Brookfield viscometer fitted with a T-spindel and rotated at 30 rev/min, thus they are apparent viscosities measured at a shear rate of approximately 10 sec-1. The instrument does reproducibly generate a shear field if spindle size and rotation rate are held fixed. By observing the apparent viscosities of several slurries at fixed conditions it is possible to obtain a relative measure of their viscosities for comparison purposes. A true shear stress-shear rate relationship at the shear rates at which the CWM will be subjected in industry may be obtained using the Haake type and a capillary viscometer. These viscometers are used for specific applications. However, for comparison purposes, apparent viscosities are reported.

Jan 1, 1985

By Hongyan Qu, Lihui Zheng

"Horizontal wells in coal seams, Qinshui basin, China are prone to wellbore instability problems induced by drilling, completion and production operations due to the presence of natural cleat network, anisotropy with regard to permeability, brittleness and mechanically weak property of the coal rock. The mechanism of wellbore instability in coal seams is very different from that in conventional formations, the traditional wellbore stability study methods therefore, are not proper for wellbore stability analysis in coal.In this study, the mechanism and controlling of wellbore stability of coal seams in the Qinshui basin was investigated through theoretical modeling, laboratory experiment and field operation. Firstly, a new physical model of wellbore stability for highly-cleated coalbed was proposed, considering the combined effect of mechanical mechanism and reservoir characteristics, specifically, taking the effect of reservoir pore pressure in the vicinity of the wellbore on the wellbore stability into account. Then experiments on the triaxial stress evaluation were conducted at laboratory where rock mechanical parameters such as Poisson's ratio, Young's modulus, compressive strength, tensile strength, angle of internal friction and cohesion ability were measured respectively. The in situ stress at different depths in four wells of Zheng 1-303, Zheng 1-308, Zheng 1-309, and Zheng 1-310 in the Zhengzhuang were calculated, and the collapse pressure and formation breakdown pressure were predicted through the theoretical model we developed. Finally, by comparing the maximum collapse pressure and minimum breakdown pressure of the four wells in the coal as well as in the roof and floor of the coal seams, the fluid weight window for safe drilling in each coal seams was determined, and appropriate approaches against anti-sloughing in coal seams, Qinshui basin were applied in the field operation.The wellbore stability was found not only related to the wellbore pressure, but also affected by the pressure in the reservoir through the theoretical model. The fluid weight window for safe drilling in each coal seams varies with the coefficient of wellbore stability in the model. The laboratory experiment results indicate that the roof and floor of 3 # coal in Qinshui basin has high breaking strength, high heterogeneity, and are easy to collapse and breakdown. In addition, the whole rock mineral analysis shows that 3 # coal in the Duanshi block has high clay content, resulting in the phenomenon of hydration swelling as clay encountered water, and leading to unstable coal and extreme large drilling uncertainties. Due to the effect of the unstable rock mechanical properties of the roof and floor formation on the wellbore stabilizing, drilling parameters, drilling fluid performance and BHA were optimized during the drilling process according to the formation properties, rock mechanical properties and drilling techniques in the field operation."

Jan 1, 2015

The surface properties of eight coal samples were studied by measuring contact angles, coal oxidation, equilibrium moisture and film flotation. The penetration tests were carried out with do de cane, while dodecane and MIBC were utilized in batch flotation tests and in the simplified release analysis. Coal floatability results from the properties of coal organic matter and coal liberation. While the wetting of coal by water seems to be determined by the surface properties of coal organic matter, wetting by hydrocarbons correlates very well with the content of coal mineral matter.

Jan 1, 1992

By Jiachen Wang, Nan Wang, Yang Li

The energy structure and consumption ratio in China determine the practical demand for the collaborative mining of coal and co-associated resources. The multi-layer mining of coal, uranium, coalbed methane, and oil and gas co-associated resources, represented by the Ordos Basin, Junggar Basin, and Tarim Basin, faces numerous challenges. Additionally, coal has been found to coexist with various mineral resources in 33 coal-bearing basins worldwide. The scientific issues related to the multi-layer development of coal related co-associated resources urgently need to be addressed. This paper discusses the unique challenges and potential solutions in the multi-layer development of coal-related co-associated resources. The challenges include large extraction space, high mining intensity, intense overburden movement, rapid surface subsidence, and severe overburden damage due to repeated mining disturbances. Proposed solutions include the establishment of a correlation mechanism between multi-layer mining and the carrying capacity of the overburden environment, analysis of the impact characteristics of multiple field couplings, and exploration of their superposition evolution laws. The paper also proposes the development of a comprehensive evaluation and prediction system for overburden environmental capacity loss, a global sensitivity analysis model for overburden environmental capacity, and an intelligent identification and early warning system based on multi-source information fusion. These solutions aim to achieve scientific and precise mining with minimal overburden environmental capacity loss. And the multi-layer development of coal-related co-associated resources is a complex task that requires a multidisciplinary approach and innovative solutions, and further research is needed to validate these strategies and explore new methods and technologies for efficient and sustainable extraction.

Jun 25, 2024

"The theoretical basis of ideal smelting reduction using coal as reductant in a process employing closed loop forced-circulation of hot metal is outlined. In the proposed process, an extensive area of relatively slag-free hot metal is available as a heat sink for absorbing the large amount of heat produced by complete combustion of CO within the furnace. Any slag that is formed within the oxidizing arm of the furnace loop is quickly swept away as a thin floating layer by the bulk movement of hot metal which is induced positively by forced melt circulation and sustained by causing the hot metal and the thin slag layer to overflow into a lower level hearth in which coal is carbonised and dissolved directly into the circulating melt.The proposed process is shown to offer very substantial cost savings over all other direct smelting technology. This is mainly because of its inherently low capital cost and its high energy efficiency. Furthermore, the favourable economics are not reliant on fuel gas credits as all the process gas is combusted within the reactor itself.IntroductionMetallurgical processes in the year 2000 will be compromise solutions to the metallurgical problems that already exist today. It is common knowledge that the mineralogical complexity of certain polymetallic sulphides, for example, precludes high degrees of separation and recovery by conventional mineral beneficiation. steps are therefore being taken towards the development of a truly polymetallic smelting process which will produce simultaneously zinc lead and copper as, metals from complex ores without prior beneficiation(l). In the ferrous extraction industry, the shortcomings of the highly efficient modern blast' furnace are well known and world-wide there is considerable effort being directed towards coal-based ironmaking without the requirement of metallurgical coke as a process intermediate. The current status 0f2Joal-based ironmaking has recently been reviewed by Smith and Corbett. (2)"

Jan 1, 1988

By Edward W. Parker

(Toronto Meeting, July, 1907.) NOTE.-The material from which this paper has been prepared was collected for the U. S. Geological Survey Bulletin, Contributions to Economic Geology, 1906, and appears also, though in somewhat more extended form without illustrations, in that publication. ALTHOUGH the briquetting of coals and lignites has been carried on for many years in Europe, and has reached a particularly high state of development in France, Belgium, and Germany, it has made comparatively little progress in the United States. The causes for the backwardness of the United States in this regard are several, and first among them has been the abundant supply of cheap raw fuel with which the manufactured article has to compete. With our millions of acres of coal-productive territory, from which the product can in most cases be cheaply extracted, it has appeared in many districts more economical to waste the slack or culm, which con¬stitutes a considerable percentage -of the product, than to attempt to save it at the additional expense required for briquetting. It is for this reason that the view in all sections of the anthracite-region of Pennsylvania is marred by the unsightly culm-banks which encumber the ground, and that in some of the bituminous-districts one sees huge piles of unmarketable- slack allowed to burn up in order to get rid of them. When the coal is of a coking quality, or when the slack can be used for steaming-purposes, these losses are not sustained, but many thousands of tons of what might be converted into usable fuel have been wasted every year simply because of the increased expense involved in its preparation.

Sep 1, 1907

By D. R. Wright

"The modest thermal efficiency of the steam turbine cycle essentially determines the heat required and, therefore, the coal consumption and ash production of pulverized-coal-fired powerplants. This paper emphasizes how some properties of coal and its ash can crucially affect the operation of a steam generator and its flue gas cleaning equipment. A brief reference to some siting factors and economics reaffirms the all-pervasive influence of the properties of coal and ash and establishes the importance of a firm supply of cooling water. The economics of scale remains a compelling factor in selecting the size of units, despite disappointing performances by some of the larger units. Environmental considerations suggest that smaller units still have a role to play. IntroductionCoal fuelled one industrial and economic revolution, beginning two hundred year s ago . It was the precursor of competing fuels, notably natural gas, oil and uranium, which eclipsed it in terms of convenience and rate of growth.The turmoil that now exists because of rapidly dwindling supplies of no-longer-cheap oil and the concerns about nuclear energy-justified or unjustified-exacerbated by an operating incident at the Three Mile Island Nuclear Powerplant, prompt speculation for a resurgence of coal, especially where it cangenerate electricity to replace energy from imported oil.The world's reserves of coal are not inexhaustible, although they are ample for several decades. Of greater import is the fact that the world's coal reserve s are more widely distributed than its oil reserves, and they appear less convenient as instruments of economic and political persuasion by opportunist powers. The crux is whether or not the world will accept all that a massive, if temporary, return to coal implies.Combustion of pulverized coal in steam generators to pro duce electricity is a 50-year-old, well-understood technique; it is undergoing continuous refinement to meet evolving environmental and economic criteria and is not found wanting. It is certainly the only technique available and technologically advanced enough to replace oil immediately on a large scale. Although it may take a decade to bring a new coal-fired powerplant into service, this delay is a reflection on nontechnical and administrative processes. Capital and operating costs of coal-fired powerplants are significant and subject to inflation, but, because of the accumulated experience in this field, the ability to control costs is better than for those energy processes which are less mature or still in embryo form. More exotic, soft energy systems, touted as the panacea for world energy problems, have still to prove themselves on the scale they are needed and under the stringent climatic and operating conditions coal-fired powerplants have already mastered."

Jan 1, 1980

By W. W. Adams

With production of coal per man-hour of work highest in history, the coal mines of the United States established a lower accident-frequency4 rate in 1942 than in any year since 1930, the first for which the Bureau of Mines, United States Department of the Interior, collected complete reports of nonfatal as well as fatal injuries. Reports from mine operators and State mining departments showed that 530,861 men were employed in and about coal mines during the calendar year 1942. This number does not include office employees or coke-oven workers. The figure represents a decrease of 15,831 men from the previous year, owing to losses of men to the military services and to more lucrative employment in the munitions and other industries. The loss of men was offset to some degree by an increase in the number of days of mine activity and the average number of hours of work per man during the year. The volume of work done during 1942 was 910 million man-hours, 11 percent more than in 1941. The average employee worked 243 days, 30 days more than in 1941. Production reached the unprecedented total of 640 million short tons, an increase of 12 percent over 1941; 582 million tons came from the bituminous fields of the United States and 58 million tons from the anthracite fields of Pennsylvania. To produce this quantity of coal 1,471 men sacrified their lives, and 69,564 men suffered nonfatal injuries that disabled them for more than the remainder of the day on which the accident occurred. The nonfatal injuries were divided into three groups: 65 caused permanent total disability, 2,045 caused permanent partial disability, and 67,454 caused temporary disability of 1 day or more but did not result in the loss of, or permanent loss of use of, any part of the body.

Jan 1, 1944

By Charles T. Holland

ANALYSIS of 117 occurrences of bumps in coal mines shows that 67.6 percent are associated with pillar-line points.4 Slabbing and splitting pillars, development, and other unfavorable milling practices in abutment areas may be a contributory or the primary cause of bumps. The cure for pillar-line bumps is to recognize areas that can be expected to become highly stressed and to project the mining plan and operations to eliminate such areas insofar as possible. If such areas cannot be eliminated, then the mining plan and operations should be projected to avoid the necessity of disturbing these areas before the stresses have been dissipated.

Jan 1, 1954

By Kristineq Pankow

The August 2007 Crandall Canyon mine disaster raised national awareness of mining-induced seismicity (MIS) in Utah as well as general interest in how seismic monitoring might improve mine safety in the region. Unlike the situation in most other mining areas in the U.S., local seismographs in Utah?s Wasatch Plateau (WP) and Book Cliffs (BC) coal fields are an integral part of a modern real-time earthquake information system developed by the University of Utah Seismograph Stations (UUSS) as part of an Advanced National Seismic System. The UUSS earthquake catalog contains a continuous record of MIS at all active mine sites in the WP-BC region since 1978 (more than 18,000 seismic events = M 4.2). We describe characteristics of MIS and current seismic monitoring capabilities in the WP-BC region. We then demonstrate, using MIS from an example Utah coal mine, the ability to refine event locations with estimated absolute errors of ~200 m or less using a combination of (1) a double-difference relocation methodology and (2) ground truth information provided by mine operators. This approach enables sufficient spatial resolution to correlate MIS with mining activities, providing a useful tool to help improve mine safety.

Jan 1, 2008

By Casters B. Foster

The U.S. Department of Energy has undertaken, in a cost sharing partnership with industry and utilities, an extensive coal-oil mixture (COM) combustion program in a number of promising applications. One of these is the injection of COM through tuyeres into a blast furnace in lieu of oil. From work done previously, it has been established that COM can be burned in existing oil, fired facilities. The issues being addressed by the current DOE program are: 1) determination of best available technology to achieve environmentally acceptable operation, and 2) determination of applications for which COM can be utilized economically.

Jan 1, 1978