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By W. W. Mason

The US began exporting coal in the late 1800s, at first in very small quantities to Canada and, beginning in 1897 and 1898, to the east coast of South America. Shipments to European countries began on a very limited basis in 1902 and these shipments increased gradually until World War I when shipments overseas increased from 7.3 Mt/a to 20 Mt/a. After the war exports dropped as fast as they had increased and, with the exception of exports to Canada, remained at very low levels until just after World War II when the US again emerged as a major coal exporter. World War II left the coal industries of Europe in ruin. As the US was the only country able to supply large quantities of coal at reasonable prices needed for reconstruction of the European economy, the US coal exports overseas expanded rapidly to 38.6 Mt in 1947. Additionally, we shipped 23.8 Mt of coal to Canada in that year for a total export of 62.3 Mt. Unfortunately, that level was not reached again until 1957 when exports reached an all-time high of 69.3 Mt - a high that has not been reached since. Over the years the level of US coal exports has fluctuated fairly widely. Approximately 80-90% of all US coal exports are high quality metallurgical grade coal so our exports level depends directly on world-wide economic conditions and world steel production levels.

Jan 1, 1982

By Mingju Liu

China has been suffering from coal and gas outbursts since 1950s. Nowadays, the situation has become worse than ever with the need to mine deeper coal deposits at higher production rates in a more complex underground mining environment. In the year 2006 alone, 37 outbursts occurred in underground coal mines with a death toll of 232. This paper describes a case study of an outburst event, which occurred in July 2006 during the shaft development of the Mengjin Coal Mine, Henan Province, China at a depth of 768m below surface. Detailed analysis of the possible causes that led to the occurrence of the outburst is reported. These include the study of complex geological features, gas storage conditions, possible improper technical management practice as well as incomplete prevention and control measures. Based on the case study and the observation of outburst occurrence in China in the year 2007, suggestions have been put forward to help prevent and control future coal and gas outbursts.

Jan 1, 2007

By C. F. Wang

Manchuria in General Manchuria, called the "Three Eastern Provinces" in Chinese, forms the northeastern corner of China and is bordered by Siberia on the north and northeast, and by Korea on the east. It is a land famous in Chinese annals as the place of origin of the Ching dynasty, and in more recent times it has been an arena for diplomatic maneuvering and commercial competition between the Russians, advancing from the north, and the' Japanese from the southeast. It derives its name of "three eastern provinces" from the fact that it is divided into three provinces; Hei-

Jan 2, 1918

By Ellis J. Brien, O&apos

This afternoon I would like to talk to you about coal, its defi- nition, its constituents, its associated minerals and present and future coal preparation techniques. This discussion will be an attempt at presenting sufficient coal preparation and associated fundamentals to enable you to understand "deep cleaning", a more advanced beneficiation process which will be commercially practiced in the near future.

Jan 1, 1976

By Kent Phillips, Meredith Scaggs-Witte, Emily Sarver, Cigden Keles

"After nearly four decades of decline, the prevalence of coal workers’ pneumoconiosis (CWP, or black lung) in the United States has been on the rise since the mid-1990s (Laney et al., 2014; Laney et al., 2010; Suarthana et al., 2011; Pollock et al., 2010; Antao et al., 2005; Blackley et al., 2016). Particularly alarming is the number of cases of rapidly progressive disease such as progressive massive fibrosis (PMF) (Pollock et al., 2010; Antao et al., 2005; Blackley et al., 2016; Laney et al., 2017). A recent study by Laney et al. (2017) observed 192 U.S. coal miners participating in the Coal Workers’ Health Surveillance Program (CWHSP) who had been diagnosed with PMF since 2000. Of the 163 (85 percent) that had a normal radiograph on file to use as a baseline, 27 (17 percent) of these individuals had progressed from a normal radiograph to PMF diagnosis in less than 10 years. Moreover, 162 (84 percent) of the individuals in that study worked in Kentucky, West Virginia or Virginia, and 169 (88 percent) had only ever mined underground. Blackley et al. (2016) also reported on a group of 60 PMF cases that were discovered by a single black lung clinic in eastern Kentucky. Since seeking care at such clinics and participation in the CWHSP are voluntary, and could be influenced by a number of factors, there has been some concern that these reports may overestimate the degree of resurgence in severe disease (i.e., versus disease that was previously under-reported). Even so, they highlight a critical need to better understand the cause(s) of disease development and progression — such that effective interventions can be devised.The notable uptick in CWP and PMF rates among miners in central Appalachia has led to this region being called a hot spot for disease (Pollock et al., 2010; Antao et al., 2005; Blackley et al., 2014; Laney et al., 2017). While the geographic clustering has been well documented (Pollock et al., 2010; Antao et al., 2005; Wade et al., 2011; Wang et al., 2013), the root cause is still unknown. Leading hypotheses have focused on the relative amount of rock being cut along with coal in many central Appalachian mines, as there has been a tendency to mine increasingly thinner coal seams over the past couple of decades (Laney et al., 2010; Schatzel, 2009). This shift has likely been accompanied by changes in specific dust exposure factors, such as increased abundance of particularly harmful dust constituents (e.g., silica or silicates) or increased frequency of harmful exposures (e.g., due to work in more risky environments) (Pollock et al., 2010; Blackley et al., 2016; Cohen et al., 2016; Douglas et al., 1986)."

Jan 5, 2018

By M. Scaggs, K. Phillips

"Coal Worker’s Pneumoconiosis (CWP) is an occupational lung disease caused by chronic exposure to respirable mine dust. After decades of steady decline, CWP incidence appears to be on the rise since the mid-1990s, particularly in some regions of Appalachia. Alarmingly, many of these cases have rapidly progressed to the most advanced form of CWP, referred to as Progressive Massive Fibrosis (PMF). Most of what is currently understood about respirable mine dust has been gleaned from routine regulatory monitoring, which tracks total mass concentration of respirable dust (mg/m3) and, less frequently, silica mass content. This paper focuses on the use of thermogravimetric analysis (TGA) as a way to provide basic characterization of the whole composition of the dust, allowing it to be classified into three mass fractions – coal, carbonate, and non-carbonate minerals. TGA was conducted on 59 dust samples collected by miners from eight coal mines in central Appalachia, and the results are discussed in terms of differences between mines, regions, and primary occupations. Consistent with prior results on area dust samples from some of the same mines, results of the personal samples generally show that the coal mass fraction of the dust is relatively low. Carbonate and non-carbonate minerals thus tend to make up the bulk of the dust mass, and vary across occupations and specific mines. INTRODUCTION After nearly four decades of decline, the prevalence of Coal Workers’ Pneumoconiosis (CWP, or “black lung”) in the US has been on the rise since the mid-1990s (Laney et al., 2014; Laney et al., 2010; Suarthana et al., 2011; Pollock et al., 2010; Antao et al., 2005; Blackley et al., 2016). Particularly alarming is the number of cases of progressive massive fibrosis (PMF), which is the most advanced form of the disease (Pollock et al., 2010; Antao et al., 2005; Blackley et al., 2016; Laney et al., 2017). A recent study by Laney et al. (2017) observed 192 US coal miners participating in the Coal Workers’ Health Surveillance Program (CWHSP) who had been diagnosed with PMF since 2000. Of the 163 (85%) that had a normal radiograph on file to use as a baseline, 27 (17%) of these individuals had progressed from a normal radiograph to PMF diagnosis in less than 10 years. Moreover, 162 (84%) of the individuals in that study worked in KY, WV or VA, and 169 (88%) had only ever mined underground. Blackley et al. (2016) also reported on a group of 60 PMF cases that were discovered by a single black lung clinic in eastern KY. Since seeking care at such clinics and participation in the CWHSP are voluntary, and could be influenced by a number of factors, these recent reports may well overestimate the degree of resurgence in severe disease (i.e., versus disease that was previously under-reported). Even so, they highlight a critical need to better understand the cause(s) of disease development and progression – such that effective interventions can be devised."

Jan 1, 2018

By Galecki G

The investigations conducted in the High Pressure Lab at the University of Missouri-Rolla demonstrated the ability of high pressure waterjets to excavate coal and minerals, disintegrate materials and as well as to comminute coal and minerals. Additional progress in comminution can be achieved if the compressive crushing principle commonly used at present is changed to one where particles are fragmented by the tensile growth of preexisting internal flaws or cracks, under internal waterjet pressure. This idea was studied in a number of tests. It covers tests with different jets imposed on coal and rock samples during compressive load as well as without any loading.

Jan 1, 1993

By S. W. Parr

STUDIES relating to the behavior of coal toward oxygen may have for their purpose the determination of the fundamental factors that underlie spontaneous combustion, weathering and deterioration, and the general topic of storage, as well as those properties that have to do with the underlying principles of carbonization. There is also involved the possibility of developing information relating to the constitution of coal, or at least the chemical properties inherent in the type substances of which the coal is composed. It is the purpose here to record certain FIG. 1. results bearing on this latter idea of the chemical properties that characterize the main constituents of bituminous coal. The avidity of freshly mined coal for oxygen has long been known. What happens to the coal or to the oxygen is not so clear. Is the oxygen absorbed or chemically combined, and what are the conditions as to time, temperature, texture, or components that are most involved in the phenomenon?

Jan 6, 1925

By A. B. Cook

The South African socio-economic history started with pastoral and agrarian communities which had low levels of industrialization and small needs for energy. The discovery of diamonds (in the Northern Cape in 1867) and of gold (in the Transvaal in 1886) heralded economic and industrial development, with a concomitant demand for energy. The energy needs of the fledgling mines, and mining towns, were met by the combustion of wood, cut locally, or by coal, hauled laboriously from the primitive collieries, and sold to the mining companies and townships at high prices.

Jan 1, 1994

By Yuting Xue

The classification of rock and coal will assist in automated coal rib rating and shearer horizon control, and is studied with machine learning techniques in this work. A database of rock and coal images is created by filtering photographs taken by researchers from the National Institute for Occupational Safety and Health (NIOSH). The classifier was trained with patches extracted from the coal and rock images, and an accuracy score of 0.9 was obtained. The trained classifier was then applied to classify rock from a new coal rib image with three rock layers of different thicknesses, and good agreement was achieved. The results demonstrate that it is promising to use machine learning techniques and rib images for rock and coal classification.

By Yuting Xue

Classification of rock and coal is one preliminary problem for fully automated or intelligent mining. It assists in automated rib stability analysis and enables the shearer to adjust the drums without human intervention. This paper studies the classification of rock from coal on rib images using machine learning techniques. A database of rock and coal images was created by filtering photographs taken by NIOSH researchers during site visits. Machine learning was conducted on patches, smaller images randomly extracted from each rock or coal image. After training, the classifier was validated with the testing dataset and achieved an accuracy score of 0.9.

Jan 13, 2022

By A. W. Khair, L. D. Gehl

"This paper describes the mechanism of coal and rock cutting from quasi-static indentation through dynamic indentation to rotary cutting. The results indicate that during quas~static indentation, a crushed zone, and subsurface fractures develop. The crushed zone is a potential source of dust generation. Dynamic indentation produces a crushed zone due to the frictional resistance offered by the coal or rock during penetration of the bit. Confining pressure changes the mode of failure from tension to mixed tension and shear. The wider bit causes larger crushed zone and more dust generation. The rotary cutting is a combination of quasi-static and dynamic indentation which results in chip formation. 1. INTRODUCTIONThe trend from conventional mining to continuous machine-cutting of coal, using more productive machinery is inexorable. Intolerable levels of dust generated at the face is an indication of inefficient coal or rock cutting by these machines. The Federal Government of the United States paid about 11.7 billion dollars workman compensation to more than 470,000 miners with Coal Workers Pneumoconiosis (Newmeyer, 1981). Bieniawski and Zipf (1985) reported that annual benefit payments were about 2 billion dollars. The need for research m improving coal cutting 1s therefore paramount. The enactment of Health and Safety Act in 1969 in the United States triggered the initial investigation into coal cutting mechanism and cutting tool design. The European countries were also engaged in the same area of research, however, their emphasis was in the use of wedge shaped bits. In 1981, the United States Bureau of Mines commissioned the South West Research Institute to investigate the effect of operating parameters mainly on airborne respirable dust in order to provide a healthier and safer atmosphere for coal mine workers.A research program by the Department of Mining Engineering, West Virginia University, USA was initiated to study the fragmentation mechanism during coal/ rock cutting. The research program was divided into three areas of research, namely quasi-static indentation, dynamic indentation and rotary cutting."

Dec 1, 1995

By E. J. Ostrowski

The history of ironmaking dates back to 4000 BC when an open forge was used to produce a sponge iron from a heap of ore and charcoal. Even at this early date, man recognized the need for a fuel and a reducing agent. As time passed, man developed new methods of producing iron; however, these developments were centered on the mechanical aspects, and as a result, a furnace evolved which is now known as a blast furnace. During this period of evolution,' man struggled with the only fuel he knew - charcoal. Some 5600 years passed before any attempt was made to use coal as a fuel for the blast furnace. The use of coal had its beginning in 1619 when Dud Dudley of England first attempted its use in the blast furnace; as a-fuel and as a reducing agent. Coal charged to the top of the blast furnace was not satisfactory. The volatile matter of the coal choked the flues, and also the poor, strength qualities would not support the weight of the ore. Breaking up of the coal compacted the stock column to an impervious mass. One hundred and sixteen. years later in 1735, Abraham Darby of England introduced coke as the fuel and reducing agent in the blast furnace. The acceptance of coke as a fuel for the blast furnace was not spontaneous. As late as 1870, one-half of the pig iron product of the United States was made with anthracite coal, 30 per cent with raw bituminous coal and coke, and 20 per cent with charcoal. However, by 1910, 96.2 per cent of the blast furnace product was made with coke, 2.4 per cent with anthracite and coke admixture, and 1.4 per cent with charcoal. Coke became the standard fuel in the blast furnace. As the art of ironmaking progressed, more pig iron was produced and more coke was consumed. Coke oven capacity was progressively increased. In 1910, there existed approximately 4,000 coke ovens; in 1960 there was approximately 15,000 ovens. This increase in coke oven capacity was necessary to feed the mammoth appetite of modern blast furnaces.

Jan 1, 1962

By Corliss R. Kinney

SINCE the first atomic bomb exploded over Japan, a great deal of speculation has been published about the use of atomic energy instead of coal for the production of power. Atomic energy, in time, may displace coal for this purpose, but atomic energy will not displace coal in supplying chemical raw materials to the rapidly expanding carbon-chemicals market. Modern civilization demands large quantities of carbon compounds and the logical source of many of these is coal. Consequently, many progressive operators are considering the possibilities of the utilization of coal as a chemical raw material as never before. Furthermore, the demand for clean, smokeless, and ashless fuels will continue to increase and the only way to handle coal under those conditions is to take it apart, just as crude petroleum is taken apart. One can readily imagine where the petroleum industry would be now if it had insisted on selling customers only crude oil, perhaps emulsified with a little salt water to correspond to the moisture and mineral matter in raw coal. The time seems to be coming at an accelerated pace when mine operators will find that competing for a highly selective fuel market by producing a larger tonnage at smaller cost will be less profitable than to increase the value of a smaller tonnage many fold by producing something more valuable to industry and civilization than raw coal. For example, about 750,000 tons of carbon black selling for $50 to $60 per ton was produced in the United States in 1945. This tonnage is insignificant compared with the total production of coal in the United States, but a very tidy tonnage, together with the coal necessary to operate the process, for any mine operator fortunate enough to obtain a method of producing a better carbon black from coal. From the point of view of tonnage, the manufacture of coke of various kinds and its by-products is at present the most important source of carbon chemicals from coal. Nearly 20 per cent of the coal mined in this country is used for this purpose. A large proportion of the coke is used for the production of iron and steel, but even in this operation a considerable part of the coke is used for a chemical purpose; that is, the reduction of the ore to metallic iron. In addition, large quantities of coke are used in manufacturing many important products that find their way into the market. POSSIBILITIES OF ACETYLENE One of the important chemicals manufactured from coke is calcium carbide, from which many products are made. One of these is acetylene. This hydrocarbon can also be manufactured from natural gas or from waste oil-refinery gas and' these industries will probably offer competition for the manufacture of acetylene. Coke-oven gas can be used for making acetylene and should receive consideration

Jan 1, 1946

By H. M. Garrett

Dr. Ft: L. Handy of Iowa State University's Engineering Experiment Station very handily reduced the relatively complex cement making process to ultimate simplicity: "Take two cups of crushed limestone; add one-half cup of clay or pulverized shale (plus perhaps some sandstone or iron ore; depending); mix thoroughly and grind up fine. Bake in white-hot oven at about 2,600 F. Cool. Add a tablespoon of gypsum: and, again, grind very fine. If you can do this for about a penny a pound, you can almost compete.' Before Dr. Handy's time, is the early days of the U. S. Cement Industry, from 1817 when the Erie Canal was started to 1895 when the first rotary kiln was built, this was the recipe, more or less. Dr. Handy's raw materials were deposited in a natural "cement rock" found in the Hudson, New York and Lehigh, Pennsylvania valleys. At first the natural rock was pulverized (not ground fine) and interlayed with wood for "baking" at about 1,800° F in a batch process vertical shaft kiln or beehive oven; then the calcined pozzalonic (lime and silica) product was cooled and ground fine for shipment in wooden barrels. Later, in 1871, true portland cement was made. The same natural rock was ground fine to make briquettes; interlaced with wood or coal in the "Beehives"; and baked at a clinkering temperature of about 2,6000 F to produce clinker (calcium silicates) which was ground fine for sale. In those days, the crude cements dropped in price from over 1 cent to 1/2 cent per pound. In 1895 the rotary kiln introduced-continuous instead of batch processing. The countercurrent process allowed the same raw materials (now finely ground to about 80% minus 200 mesh like face powder) to be fed at one end of the rotary kiln. Heat from a coal burner was introduced with combustion air at the other end to produce the requisite clinkering temperature. The clinker product was discharged for atmospheric cooling, mixed with gypsum, and again ground fine as face powder. The cement was sold primarily in barrels, later in jute or cloth bags, then paper bags, and now primarily in bulk truck and barge carriers. The price dropped to a 1/4 cent per pound by 1910, but with recent inflation it now sells for 2 cents per pound.

Jan 1, 1978

By H. M. Garrett

The basic cement making process is outlined relative to the fuel but chemically sensitive suspension preheater (SP) kiln which made its debut in the early 50s. The SP history is trailed through the process disasters of the late 50s; identification of chemical sensitivities in the 60s; and resurgence of the SP together with development of its stepchild process, the precalciner (PC) kiln, in the 70s. The current energy problem and related conversions to coal re-emphasize the process chemical sensitivity. Attention is focused on the basic problem of coal sulfur and ash variations and several solutions are presented.

Jan 1, 1981

By V. M. Johnston

The most abundant fuel resource in the U.S.A. is also the most under-utilized. Proven reserves of bituminous coal, sub-bituminous and lignite constitute from 60% to 90% of our total fossil fuel reserves -- dependent upon the parameters used by the analyst making the estimate. Despite this ample supply, bituminous coal provided only 20% of U. S. energy consumption in 1967 and 1968, this dropping to 17.57 in 1971 and 1972. By 1978, according to my projections, 16.7% of the Nation's mechanical energy will come from bituminous coal. However, our energy needs are growing at such a rate that the 20.6% provided by bituminous in 1967 equalled 480 million tons while the 16.7% of U. S. consumption visualized for 1978 will require nearly 650 million tons. In order to view coal's position with perspective in this developing energy crunch, it is necessary to examine the total energy situation. To this end, I have prepared a couple of tables which you should have before you. I chose this procedure rather than slides because I would need to utilize an entire wall to make the data visible to an audience. Therefore, I refer you to the long sheet entitled "U. S. Energy Consumption - Trillion Btu - 1967-1978." As you can see from the heading, I am confining my treatment of the problem to the intermediate term. In the long run, if we are willing to pay the cost, we can do a lot of things, including the complete conversion of coal into a sulfur-free fuel.

Jan 1, 1973

By John I. Yellott

SINCE the days of Newcomen and Watt, when men first sought to turn the energy of fuels to useful purposes, coal-generated steam has supplied most of the power needed for both stationary and mobile applications. The low efficiency and large water requirements of the nineteenth century steam-power plant caused many engineers to turn their thoughts toward more direct means of converting heat into power. As far back as 1791, John Barber secured an English patent on a combination' which he might well have called a "gas turbine." He proposed to generate procducer gas from coal or charcoal, to burn it under pressure in air obtained from a reciprocating compressor, and to drive a turbine wheel with the resultant hot combustion products. With the optimism characteristic of the inventor, he hoped that the turbine would not only operate his compressor but also perform useful work. There is no record that Barber ever built his machine, but if he had done so he would have learned that useful power can result from such a combination only when both turbine and compressor are highly efficient and when the temperature of the gas entering the turbine is not far below 1000°F. Hot-air prime movers continued to attract attention, and both Stirling in England and Ericsson in America2 built reciprocating engines that operated with some success upon coal-heated air. The internal-combustion engine, burning liquid fuels, supplanted the hot-air type, and, for the first time, challenged the supremacy of both the steam cycle and its familiar fuel, coal. LIQUID FUELS COMPETE WITH COAL As the increasing use of the automobile multiplied the demand for gasoline, the supply of residual fuel increased rapidly, and heavy oil declined in price to the point where it became competitive with coal. First in the marine field and later in stationary plants in areas adjacent to refineries, oil began to be widely used. Oil's greater convenience and higher heating value per pound of weight or per cubic foot of bunker space have caused it to take over much of the marine field. The introduction of the highly efficient diesel engine, capable of burning a fuel that is cheaper than gasoline, again threatened the position of coal, for the operating costs of the diesel became directly competitive with those of coal- burning equipment. In isolated power plants and smaller marine installations, the diesel provided the medium by which oil again successfully invaded fields formerly dominated by coal. The diesel engine, provided with an

Jan 1, 1946

By Arthur F. Johnson

Plant sites for the light metal industry must be located where ample low cost power is available. In the first half of the century hydroelectric development was the only source of this power-now the best sites have been exploited and those remaining do not promise enough water to permit year-round capacity power plant operation. In searching for economic plant sites engineers have concentrated on locations with vast water power potential. Olin Mathieson Chemical Corp. has been studying the economics of developing water power to make aluminum. However natural gas, lignite, and even atomic energy have also been considered as possible power sources for aluminum production. Economic studies have given consideration not merely to investment and production costs, but to total costs of delivering fabricated products to the market center of the U. S. When delivered costs are considered and when full account is taken of the newest techniques of mining bituminous coal and utilizing it to make electric power, one arrives at the inescapable conclusion that coal has emerged as the economic answer to American aluminum production.

Jan 4, 1955

By Golding S. D, Price P. L

The Early Permian Aldebaran Sandstone is the main hydrocarbon reservoir in the Denison Trough. Contained hydrocarbon gas has a wet gas index (C1/CI - C4) of between 0.87 and 0.97 (N=10), and constituent methane has 813CPDB values ranging from -51.5 to -36.2% (N=10). These values clearly indicate that the gas is thermogenic rather than biogenic. Considering the predominantly humic nature and maturity of all organic source material for the gas, the methane 813C values are anomalously low, with typical values for humic methane present in natural gas formed at similar maturity levels significantly higher at -26 ¦ 5%o. This suggests that, in addition to disseminated organic matter in underlying marine mudrocks of the Cattle Creek Formation, methane substantially more depleted in 13C was derived from coal seams of the Reids Dome beds, a thick coal measure sequence which underlies the Cattle Creek Formation and, in the south, the Aldebaran Sandstone. This methane is likely to have S13C values of between -75 and -40 oo, based on the known isotopic composition of dry gas trapped in humic coals of similar rank in the Sydney Basin and elsewhere in the Bowen Basin. In addition to the low methane S13C values, the contribution of coal seam methane would explain the fact that, (1) methane S13C values do not show the normal increase with decreasing gas wetness, and (2)013C%o (ethane-methane) values do not show the expected decrease with decreasing gas wetness. The presence of co-existing, isotopically heavy CO2 (S13C = +2.0 to +3.4%0, N=3) in the Glentulloch and Merivale Fields is consistent with the view that natural gas in the Aldebaran Sandstone is in part coal seam derived.

Jan 1, 1991