Coal mining has been in progress in Southwest Virginia since before the time of the Civil War. During the period 1880 to 1930, the region changed from one of subsistence farming to economic dependence on the coal mining industry. As in many other mining regions, the following sixty years saw coal production being maintained or increased, using fewer employees, through the introduction of mechanized methods of mining. However, Table 1.1 shows that from a peak of 46.5 million tons in 1990, Virginia’s coal output has declined. This has occurred for a variety of reasons including competition from both domestic and overseas sources, environmental concerns, geological considerations and exhaustion of many of the thicker coal seams. (Holman, McPherson, and Loomis, 1999b).
Table 1.1 Virginia coal production and numbers of production-related employees since 1990+
In 1951 a detailed survey was conducted to determine the state of Virginia’s coal reserves. It was estimated that Virginia had 10.776 billion tons of bituminous coal in seams 14 inches and thicker. (Brown, 1952) Between 1951 and 1996, 1.577 billion tons were mined with estimated losses of 40%. (VCCER, Virginia Coal Directory, 1998) This effectively removed 2.208 billion tons from the resource leaving 8.568 billion tons. The original estimate for measured, indicated, and inferred reserves between seam thicknesses of 14 and 28 inches was 5.041 billion tons2. (U.S.G.S., 1952) Subtracting this from the 8.568 billion tons of remaining resource yields slightly more than3.5 billion tons of coal in seams greater than 28 inches. (Holman, McPherson, and Loomis, 1999b)
Using estimated values from Bureau of Mines studies on Appalachian coal the amount of economically mineable coal can be obtained. From the remaining 3.5 billion tons in seams thicker than 28 inches, 34% will be recoverable but only a little less than 9 percent can be considered as an economic reserve. (Rohrbacher, 1993). The latter represents 321 million economic tons. With an annual production of 36 million tons, this yields some 9 years of mining for the region. As reserves diminish, production will decrease, slightly extending this life.
It is the inevitable consequence of any mining region that the fuel or mineral resources that can be mined economically will eventually be depleted. If the region is to continue as economically viable then other industries and opportunities for employment must be developed well before mining ceases.* This may be encouraged and funded by utilizing some of the taxation revenues generated by the mining, as has occurred in Southwest Virginia through the Coalfields Economic Development Authority (CEDA).
In the case of Virginia’s Coalfields, it is estimated that a resource of over 5 billion tons of high quality coal remains in the ground in seams of between 14 and 28 inches thickness. The life of coal mining in Virginia would be extended greatly if techniques are developed to enable this valuable resource to be extracted in a manner that is both competitive and environmentally benign. An extension in the life of coal mining in Southwest Virginia would also extend the funds and time available to promote the development of other avenues of sustainable economic endeavor. However, it should not be expected that there will, ever again, be large numbers of persons employed in the coal mining industry of Virginia. In order to meet the challenges of the market, coal mining companies have little choice but to utilize increasingly sophisticated and automated equipment. If thin seams are to be extracted then those working places (faces) where the coal is actually won will be entirely manless. (Holman, McPherson, and Loomis, 1999b).
In 1996, the Virginia State Government enacted legislation that provided a tax credit to coal mining companies operating in the State. This was an enticement for those companies to remain in Virginia and to assist them in extracting some of the thinner seams. This has had the result of temporarily inhibiting the continuous decline in coal production. However, it can be no more than a stopgap. The only way that Virginian coal mining can be extended well into the next century, when coal will continue to be needed as a primary fuel source+ is through the development of thin seam mining technology.
Unfortunately, there are significant barriers to the research and development that is necessary for the introduction of new mining technologies. The selection of an underground mining method is influenced by numerous factors, including tradition. A pervasive idea is that what has worked in the past, will continue to work in the future.
This is a mode of operation that maintains the comfort of familiarity. Hard won experience with tried and true methods allows for sound decision making for as long as that method continues to be employed and remains viable. (Holman, McPherson, and Loomis, 1999b)
Many (but not all) American mining companies operate with a conservative outlook, and are reluctant to try something new until they see it working successfully elsewhere. The primary reason given for this unwillingness to innovate is low profit margins. This reluctance has resulted in a traditional lack of research and development by the American mining industries. Another contributing factor to this trend is that market trends often force coal companies to operate on a boom-bust cycle. While business is booming, many companies indicate that they have little need for research and development. Whereas when business is down they say they cannot afford it.
A further influence on this problem is that throughout most of the 20th century mining research and development has been conducted by government agencies in the U.S. and elsewhere. This effectively came to an end in 1996, in the United States, with dismemberment of the US Bureau of Mines, except for matters of safety and health that are now addressed by the National Institute for Safety and Health (NIOSH). The problem we are left with is that it is difficult to introduce new technologies and ideas that have potential to move the coal industry forward into the next century. New pathways that could yield safe, clean, and high production are not being explored, simply because they are new. For an innovative idea to bear fruit, it must first be tried. (Holman, McPherson, and Loomis, 1999b)
Within is presented a brief overview of current technologies utilized for underground coal mining in the United States. This is followed by a review of developments in highwall mining that show promise of having an application in the underground mining of thin seams. Some past attempts at thin seam mining are discussed. The more recent advances in the guidance systems used in autonomous mining machines are introduced. The state-of-the-art products of several manufacturers in addressing the integration of mining and continuous haulage systems are also highlighted.
All of that background is employed in outlining a conceptual mining system for the underground mining of coal seams in the 14 to 28 inch range of thickness. Most of the equipment suggested for this proposed system is currently available. Furthermore, the mining and manufacturing expertise necessary for the cooperative development of such a system is already available in Virginia and its neighboring states.
Underground thin-seam mining in Virginia cannot hope to achieve the productivity (in tons per man-hour) of western surface mines extracting much thicker seams. However, there are distinct incentives to continuing coal mining in Virginia where the coal is not only low in sulfur content, but has a calorific value some 20 percent higher than western coals. About 50 percent of Virginia coal is of metallurgical quality while proximity to the coal terminals in Hampton Roads allows a ready route to the export market. About 37 percent of Virginia coal is shipped overseas.
Furthermore, the environmental impacts of surface extraction are much greater than those of underground mining, a matter of increasing concern throughout the nation. These are some of the reasons that research into the feasibility of underground coal mining in Virginia is a worthwhile endeavor. (Holman, McPherson, and Loomis, 1999b).
