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By Hasan Sevim

This paper summarizes recent developments in modeling of underground coal slurry haulage networks for determination of optimum design and operating parameters. The model presented here is based on a stochastic dynamic programming formulation, applicable in any typical room-and-pillar and/or longwall mining configuration commonly practiced in the United States. The formulation and the structure of the model is general enough to handle design problems involving more than one face and mining method. Given the stochastic operating characteristics and a system layout, the model can be used to determine the equipment configuration and operating regimes that minimize the overall unit cost of coal haulage.

Jan 1, 1983

By C. D. Keith

Erie Mining Company, a pioneer in the iron ore pelletizing industry, has continued to develop methods and equipment to improve cost and quality. Under the management of Pickands Mather & Co., this property, owned by Bethlehem Steel Corporation, Youngstown Sheet and Tube Company, Steel Company of Canada, Ltd., and Interlake, Inc., has initiated a number of operating improvements for the taconite industry. One of the most noteworthy of these, which is applicable to the entire mineral industry, is the principle of fine screening with rappers (FSR). Erie's original efforts in the field of fine screening, which date back to 1961, were described in the April 1967 issue of the MINING ENGINEERING magazine. In that same month, Erie placed into operation a full scale PSR and regrind plant addition, capable of processing 10.3 million long tons of iron ore concentrates, produced by conventional taconite grinding, classification, and magnetic separation methods. Since this first successful commercial operation of the PSR principle et Erie, it has been applied in eight other iron ore beneficiation plants end is being tested by other U.S. and foreign companies. In addition to the use of PSR units at Erie Mining Company, Pickands Mather has applied PSR to other of its managed properties end to projects under development. This paper covers these applications as well as a now application at Erie Mining Company.

Jan 1, 1971

By I. J. Dowdeswell

Perspective Man is a model maker. Throughout recorded history man has-used models both to provide insights into the workings of the processes which surround him and as a step towards the eventual control of those processes. These models have covered the field from extremely large systems (solar and celestial. models) to infinitesimally small systems (sub-atomic .and atomic models). Models have been developed for social systems, ecological systems, biological systems and economic systems: all fields of human endeavour contain the fruits of this restless model-making. The Role of Models Since the evidence of mans' industry in formulating models is so abundant, it is worthwhile stating some of the reasons. Based on the simple definition that "a model is a convenient and useful representation of some facet of the 'real' world", then a model provides a means for: 1. Understanding the thing being studied. 2. Communicating that understanding to others. 3. Manipulating the thing being modelled. The common denominator implicit in these reasons is that- improved control is the. objective off all modelling or simulation work. Improved control shows itself either directly by the development of devices which perform the control functions or indirectly by improvement in the decision making process itself. For example, in a process plant, a suitable model of part of the process could lead either to the use of automatic control devices such as set-point controllers or to the implementation of instructions (pre-defined decisions) which permit the operator to better control the process. Typical process control systems use both of these since fully automatic control is restricted to processes where the required information can be effectively measured.

Jan 1, 1972

By P. Henderson, M. E. Morris, W. A. Johnson, F. D’Alessandro, D. Wilton

"The objective of this research is to develop and apply computer models to evaluate the potential lightning impacts on underground coal-mining. These models can then be utilised to assist in the design of effective controls. This project will provide a significantly improved level of knowledge and control over current lightning abatement techniques. The findings may also be applied to open cut and coal preparation situations. Computer modelling identified that by isolating cased boreholes from underground conductive media such as roof mesh, and placing spacings between roof mesh the risk of an ignition can be reduced by more than a factor of ten. These controls should be applied in conjunction with minimising the potential for a flammable atmosphere to exist underground and ensuring that there is no transmission medium for the lightning to reach the atmosphere. INTRODUCTION The objective of this research was to develop and apply computer models to evaluate the potential lightning impacts on underground coal-mining. These models could then be utilised to assist in the design of effective controls. If successful this project would provide a significantly improved level of knowledge and control over current lightning abatement techniques. The direct potential for harm from lightning has long been recognised for the surface facilities of coal mines. However recent events at Blakefield South in NSW on January 5 2011 (DTI, 2011) and at Sago mine in the USA in 2006 (MSHA, 2007) have suggested that there is potential for lightning to cause significant damage to the underground workings of a coal mine. A very detailed analysis carried out by as part of the MSHA investigation into the SAGO disaster by Sandia Laboratories identified at least ten other incidents over the past thirteen years where lightning had probably caused the ignition of a sealed goaf area of a mine (SANDIA, 2011). In addition there is a long history of lightning related incidents in South African coal mines (Geldenhuys, 1985). Fortunately in those cases no lives were lost. The event at Blakefield South has suggested that there may be the potential for ignition to occur in an active longwall goaf. The potential for a lightning strike to ignite a flammable atmosphere in an underground coal mine has been demonstrated from the past experience both here and overseas. It requires three things: • Lightning • A mechanism to convey the lightning underground to the flammable atmosphere • A flammable atmosphere."

Jan 1, 2016

By Thomas E. Howard

Engineers today face a tremendous challenge. Growing population and rising standards of living all over the world are creating unprecedented and accelerating demands on and for all kinds of technology. At the same time, the public is becoming more and more conscious of--and concerned with--the impact of technology on human welfare. The growing controversy over the Supersonic Transport is a case in point, It is clear that the modern engineer must expect to spend a growing share of his time considering this dilemma and evaluating the tools that are available to him, not only with respect to their adequacy for the job at hand but also their capability for meeting the increasingly demanding--and, in many cases, conflicting--requirements of the future. This meeting seems a particularly appropriate place to speculate about the future of mining technology. The summary of the state-of-the-art in surface mining contained in the papers scheduled for the International Conference, together with the recently published Surface Mining volume, constitute not only a major contribution to the technical literature but also form an impressive record of technologic progress. That record, and the advanced technology displayed in the exhibits, and to be discussed in the SME technical sessions demonstrate engineering achievement in which the mining community can justly take pride.

Jan 1, 1968

By James C. Gilliand

Leo-potpourri, was selected as the title to this paper for several reasons. First, it is a fascinating word--not looking like it sounds or sounding like it looks. It also allows for a great degree of flexibility in designing a presentation around it. Further, it has become popular to use this eco hyphen something pattern. We hear of eco-mania, eco-hysteria and the like. Lastly, in this era of intense environmental concern, two of the principle elements on which the integrity of our efforts must be equated are ecology and economics. Accordingly, the term "Eco-potpourris" allows me to roam at will through the great number of considerations that make up this environmental issue. Whereas only a few years ago the subject of environment and environmental control had low visibility with the public, today it competes as the focus of attention with the many other popular social issues of our time. The program content here at this meeting, for example, is liberally represented by papers dealing with one or more aspects of environmental concern. If one would look at the 1964 program, in contrast, I would expect that no more than possibly one or two papers covered this subject and even then that those papers dealt principally with the environmental aspect of occupational health. It is gratifying that the program at this meeting demonstrates a serious awareness to a broad spectrum of environmental concerns. It would be a mistake, of course, to believe that this clamor for a quality environment is a "flash in the pan" that will soon subside. The general public has been thoroughly aroused and even frightened into

Jan 1, 1972

By Rennie B. Kaunda, Robert J. Sterrett

Some people in the mining-engineering field mistakenly believe that mine-water management primarily revolves around the treatment of mine waters that fail to meet applicable water-quality standards. While water-quality control is undoubtedly important, it represents only a fraction of what constitutes comprehensive site-wide, minewater management. A more holistic perspective recognizes that it also involves mine dewatering to maintain safe and workable conditions, securing sufficient water supply for operations, strategically handling surface water within and surrounding the openpit to prevent issues like flooding, developing robust post-closure plans to mitigate long-term environmental effects, and proactively minimizing any adverse impacts on local communities and ecosystems. This article provides a brief overview of topics that fall within the concepts of mine-water management. The focus is on openpit mines, as they are generally larger than underground mines. The management of mine water is highly dependent on local and regional climate such as tropical, desert or temperate climate. Each climatic setting has its own unique challenges, but there are also commonalities.

Jun 1, 2025

By G. E. S. Valadao

Filtration is an important solid liquid separation technology employed widely in the mineral processing industries. The effectiveness of the filtration operation can be influenced by numerous variables, related to the particulate phase, the slurry rheology and the equipment. The classical approach for analysis is based on Darcy's law. Knowledge of the cake pore microstructure and its correlation to macroscopic cake properties is required to model the filtration operation from a fundamental point of view. Since cake formation seems to occur randomly, a 3D Monte Carlo method was used to simulate cake formation. The configuration for simulation was a space with width of 500 µm, length of 500 µm and height of 4000 µm. Size distributions of five different industrial products whose particle size distributions follow the Rosin Rammler distribution function were used. The particle shape was assumed to be spherical. The simulated cake structures were described in terms of volume porosity (volume of pore space per unit volume of cake) and surface porosity (area of pore space per unit area of a cross section). The results indicate: I) it is possible to simulate 3D packing, which mimics cake structure, using the Monte Carlo method, 2) segregation phenomena occurs during simulated cake formation, 3) the values of calculated porosity for simulated samples B, C, D, and E were lower than those determined for corresponding industrial products Br, Cr, Dr, and Er, and 4) some structures of simulated samples seem to correlate with laboratory leaf test data obtained for different products from plant operations.

Jan 1, 1999

By Ronald E. Yarbrough, Theodore L. Triplett, Larry R. Powell

The Bureau of Mines, in cooperation with the Illinois Mine Subsidence Insurance Fund, is monitoring the response of two foundations to ground movements induced by subsidence from a high-extraction retreat room-and-pillar operation in southern Illinois. The objective of this monitoring program is to study the inter- action between the ground surface and a structure during a subsidence event. Data from such a study should enhance the understanding of the mechanisms that produce structural damage and aid in the design of structures that resist such damage. This paper describes the monitoring instrumentation and techniques as they relate to the mining and site conditions. The capability of a tiltmeter to detect and follow the tilt of the foundations caused by the mining subsidence sequence is demonstrated. Using data from this tiltmeter, the development of curvature in the foundations as they conformed to the displaced ground surface is shown. This curvature is rep- resented by differences in tilt at various points on the foundations, indicating a change in tilt over a horizontal distance. Also, even though subsidence damage has not been fully analyzed, preliminary observations of the cracks that formed in the foundations are reported. These cracks resulted in the separation of one footing into distinct pieces; therefore, their effect on the tilt readings is cited.

Jan 1, 1986

By Jay Parrish

Appalachian kimberlites appear to be spatially distributed along two structure parallel trends running from Tennessee to New York. It is hypothesized that the kimberlites were emplaced at the intersection of structure parallel basement faults and cross- structural lineaments. The latter are expressed in potential field and remotely sensed data. The western trend follows the Rome Trough from eastern Kentucky to south central New York. The eastern trend parallels the edge of the Ridge and Valley in Virginia and Maryland.

Jan 1, 1984

By Allan Breitenbach

Leaching has been used since the 1600s on unlined ore dumps and since the late 1970s on lined leach pads for the recovery of metals from mined ore, the latter typically called ?heap? leaching and the former ?dump? leaching. Modern day run-of-mine (ROM) or crushed ore heaps are stacked in controlled lifts on lined leach pads and irrigated with a solvent solution (dilute alkaline cyanide for precious meals, dilute sulfuric acid for base metals and uranium). Conventional lined leach pads store process solutions and any storm water, snow melt and cumulative wet season surplus water by gravity flow to external ponds. Impounding valley leach pads (also known as valley fill heaps) differ from conventional leach pads by storing various combinations of process liquid solution and surplus water within internal ponds by using the interstitial pore volume of the ore. While impounding liquids within the heap is simple in concept, impounding leach pads are more complicated for construction and containment compared to conventional leach pads with external ponds.

Jan 1, 2012

By Brad Grothen, Lok Home

The choice of TBM type is never easy, but it becomes especially challenging when faced with a hard rock tunnel with expected high water flows and pressure. Slurry Shield tunneling has a long history of being used in these conditions to minimize the risk, though this method has brought with it other risks along with cost considerations. At recent projects around the world, another method has been proven to effectively manage these project risks without utilizing Slurry Shield tunneling: Shielded, NonContinuous Pressurized (NCP)-TBM tunneling in rock with a comprehensive grouting program. In this paper, the authors will analyze the use of Shielded NCP TBMs at projects around the world as compared with slurry shield tunneling in rock under water pressure. Recommendations will be given in order to establish a clear picture of the optimal tunneling method.

Jun 13, 2021

By R. S. Dennen

A ground penetrating synthetic pulse radar system has been used by the Bureau of Mines to probe into a coal pillar to locate hidden structures or anomalies. Two types of velocity tomographic reconstruction methods, direct matrix inversion and iterative, were used to obtain a velocity image of the interior of the pillar. The reconstructed image showed the existence and location of a relatively low velocity material within the pillar. Core samples were taken from the pillar in a region surrounding the low velocity material. Analysis of the cores showed the presence of a clay vein coinciding with the low velocity material imaged in the tomogram.

Jan 1, 1989

By Monica Campos, Jose Mujica, Maria Campos

The extraction and processing of metals and other minerals have played an important role in economic, political, and social development worldwide, from the early stages of prehistory to the present day (Gosner, 2020). In other words, mining has been a fundamental part of human civilization, providing the raw materials necessary for technological, infrastructure, and industrial advances. As society progresses, the importance of mining continues to grow, supporting the development of everything from the smallest electronic devices to the tallest skyscrapers (The Importance Of Mining In Modern Society, 2024). The mining industry is closely linked to a country’s economy and activities related to natural resources. The economy of a nation is connected to its extractive industries (Moreira & McMahon, 2014), which have seen dramatic growth in recent years (Pietrobelli et al., 2018). In a context of increasing demand for natural resources, driven by the development of emerging technologies, the expansion of infrastructure, and the foundation of engineering achievements for the coming decades (Importance Of Mining - Minerals Education Coalition, 2024), mining should focus efforts on global development, requiring a comprehensive approach to sustainability that addresses the planet’s needs and protects the well-being, primarily, of the communities and environments where mining operations take place (Figari, 2024). In these areas, diversity and inclusion should be promoted, thus fostering equitable and sustainable development. Speaking of sustainable development, diversity, and inclusion brings us to an interesting topic: the Sustainable Development Goals (SDGs), also known as the Global Goals, which could serve as a key framework for fostering a strong social management culture in mining. The SDGs were adopted by the United Nations in 2015 as a universal call to end poverty, protect the planet, and ensure that all people enjoy peace and prosperity by 2030 (Sustainable Development Goals, n.d.). Companies have compelling reasons to align their actions with the SDGs, as their long-term success depends on healthy communities. This is a major challenge and requires collaborative efforts (Singh & Rahman, 2021). As Fraser (2021) mentions, achieving more sustainable outcomes may involve mining companies and communities working together collaboratively. This research proposes an innovative approach: Inclusive Mining for Sustainable Development, which aims not only to maximize economic profitability but also to promote social and environmental well-being by integrating the United Nations’ Sustainable Development Goals (SDGs), primarily focused on diversity and inclusion. This can be achieved through the implementation of a key value-added initiative for mining companies: the Creation and operation of a corporate volunteering program aimed at developing and executing inclusive practices to promote gender equality, the inclusion of local communities and indigenous peoples, and accessibility for people with disabilities. This proposal will educate employees and stakeholders about sustainability and promote concrete actions through corporate volunteering to strengthen the mining company’s commitment to community development, improve social relations, and advance toward achieving the United Nations’ Sustainable Development Goals, establishing the company as a global change agent.

Feb 1, 2025

By Raj K. Rajamani

In ball milling the rates of breakage vary primarily with the size distribution of powder in the mill. In wet grinding viscosity of the slurry varies continually as size distribution changes and hence the breakage rates change. In this study a simpler estimation scheme is used to determine breakage rates in batch grinding. Using an approximate solution to the batch grinding equation, acceleration and deceleration of breakage rates of all individual size classes is determined when the grinding environment is varied. Experimental results with limestone and copper ore show time-dependent breakage rates under both dry and wet grinding conditions. In general the breakage rates increase for coarse sizes and decrease for fine sizes with increase in the fines present in the mill. Such variations have strong implications in closed-circuit grinding.

Jan 1, 1991

By Bernard L. Cohen

I.INTRODUCTION The B E I R-III Report (NAS-1980) introduces large increases in the estimated health effects of radon as compared with previous work (NAS-1972). It is the purpose of this paper to point out some important failures of these new BEIR-III estimates, to offer a general critique of the procedures used in obtaining them, and to offer more rational estimates. In Sec. II we use the BEIR-III model to calculate the risk to non-smokers from environmental radon, and show that it predicts more than twice the total lung cancer rate actually experienced by nonsmokers. In Sec. III we review the histological evidence which shows that no more than about 10% of the lung cancers among non-smokers can be due to radiation. In Sec. IV, we discuss alternative causes of lung cancer, which further reduces the fraction that can be caused by radiation, and in Sec. V we summarize and conclude that the BEIR-III model over-estimates the lung cancer rate in nonsmokers due to environmental radon by at least a factor of 40. In Sec. VT we review the evidence on risk of radon exposure to smokers, and conclude that it is probably not more than four times the risk to non-smokers; this means that the BEIR-III model over-estimates the risk of low level radon exposure to smokers by at least a factor of 10. In Sec. VII, we consider the reasons for the large over-estimates in the BEIR-III. Report. II. BEIR-III LUNG CANCER RATES DUE TO ENVIRONMENTAL RADON AND COMPARISON WITH TOTAL LUNG CANCER RATES AMONG NON-SMOKERS The BEIR-III Report gives the following estimates of the lung cancer risk from low-level radon exposure in terms of working-level-months (WLM): age 35-49, risk = 10 x 10-6 /yr-WLM 50-64, 20 >65, 50 where ages refer to age at death. For latent periods between exposure and onset of these risks it gives age 0-14, latent period = 25 years 15-34, 15-20 years (we use 17 yr) >35, 10 years where ages refer to age at exposure. This is a clear and unambiguous model which is readily usable for deriving numerical estimates. We begin by using it to calculate lung cancer rates due to environmental radon. *This is an abridged version of a paper scheduled to appear shortly in Health Physics. The first step in this process is to estimate the environmental exposures; this was done in a recent paper (Cohen-1981) which concluded that these are about 0.22 WLM/year. In Table 1, this is used to calculate the BEIR-111 predictions for radoninduced lung cancer rates in the U.S. (Col. (5)), and by combining these with population statistics, it is shown (Col.(7)), that it predicts about 24,500 fatalities per year, almost one-third of all U.S. lung cancers. The comparison between the age-specific expected rates from Col. (5) of Table 1 and observed rates among non-smokers is shown in Table 2. The recent paper by Garfinkel (1980) presents the results of a 12 year follow-up on one million Americans in a study by the American Cancer Society. The paper by Hammond (1966) gave the results of the first four years of that study. The paper by Kahn (1966) is based on the so-called "Dorn Study" of 293,000 U.S. veterans of World War II who carry government health insurance. It represents 8 and 1/2 years of follow-up. A recent update on that study (Rogot-1980) does not give absolute lung cancer rates, but the age-standardized ratio between smokers and non-smokers has remained the same which indicates that there has probably not been an important change in the rates for either. The paper by Hammond and Horn (Ha-1958) was an early study by American Cancer Society. It is immediately evident from Table 2 that the BEIR-III estimates for lung cancer induced by environmental radon exceed the [total] lung cancer rates due to [all] causes among non-smokers by about a factor of two at every age. It is only fair to point out that this does not represent a direct discrepancy with the BEIR-III Report since the latter states that its estimates for non-smokers may be too high by a factor ranging from 1 to 6, favoring a factor intermediate between these. Comparisons can also be made with total lung cancer incidence for all ages. A paper by Hammond and Seidman (Hammond-1980) gives the rate for ages above 40 to be 177 x 10-6/year for men and 124 x 10-6/year for women, whereas the rate calculated in Table 1 from BEIR-III for ages above 40 is 309 x 10-6, a factor of two higher. For all ages, the rate among women was reported as 36 x 10-6/year (Hammond 1958) as compared with 114 x 10-6/year calculated from BEIR-III in Table 1, a discrepancy of well over a factor of two. All of the data we have presented are basically from three study groups, but in all three cases the BEIR-III estimates for lung cancer induced [by environmental radon alone] are a factor of two higher than actual [tota] lung cancer rates among non-smokers. Another approach to comparing the BEIR-III pre-

Jan 1, 1981

By Tzou-Shin Ueng

Rock reinforcement of rock anchors and rock bolts are commonly used for the support of large rock caverns. The rocks at the location of most large underground openings are usually under very high initial stresses prior to excavation. Hence, the stress redistribution caused by excavation will induce considerable rebound deformations of rocks surrounding the caverns. Since the pressures exerted by the reinforcement are generally far below the initial rock stresses, the reinforcement will be stretched along with the rock deformations, and the stresses in the reinforcement increase accordingly. It is not uncommon for the stress in the reinforcement to reach the yield strength, and in some cases the reinforcement may even have failed. Therefore, the increase of stresses caused by the rebound deformations of rocks should be taken into account in addition to the force required to stabilize the caverns. It was found that the measured stress increases of the prestressed tendons after installation were in good agreement with those computed based on the measured rock deformations between surface and the anchoring point of the reinforcement. The rebound rock deformations and the stress increases in the reinforcement can be estimated based on the results of the finite element analysis and experiences in previous field measurements incorporated with considerations of the geologic conditions, rock properties, rock reinforcement and construction procedures.

Jan 1, 1986

By Bradley S. Van Gosen, Anjana K. Shah, George M. Bedinger, Donald I. Bleiwas, Karl J. Ellefsen

"Ancient and modern coastal deposits of heavy mineral sands (HMS) are the principal source of several heavy industrial minerals, with mining and processing operations on every continent except Antarctica. For example, HMS deposits are the main source of titanium feedstock for the titanium dioxide (TiO2) pigments industry, obtained from the minerals ilmenite (Fe2+TiO3), rutile (TiO2) and leucoxene (an alteration product of ilmenite). HMS deposits are also the principal source of zircon (ZrSiO4), from which zirconium dioxide (ZrO2) is obtained for uses mostly in refractory products. Sometimes monazite [(Ce,La,Nd,Th) PO4] is recovered as a byproduct mineral, sought for its rare earth elements, and thorium (Ault and others, 2016; Sengupta and Van Gosen, 2016; Van Gosen and Tulsidas, 2016).HMS are sediments containing dense (heavy) minerals that accumulate with sand, silt and clay in coastal environments, locally forming economic concentrations of the heavy minerals (Fig. 1). Economic (mined) HMS deposits include Holocene sediments on modern coasts, such as examples in India and Brazil, as well as coastal deposits formed by transgressions and regressions of the seas during intervals in the Quaternary, Tertiary and Cretaceous, such as in Australia and the southeastern United States. Economic deposits typically contain heavy-mineral concentrations of at least two percent. Individual heavy minerals are commonly defined as minerals with a specific gravity greater than approximately 2.9 g/cm3. These minerals are generally resistant to chemical weathering and physical degradation and thus survive well in fluvial and coastal environments. Heavy minerals in coastal HMS deposits may include, in order of general abundance, ilmenite, leucoxene, rutile, magnetite, zircon, staurolite, kyanite, sillimanite, tourmaline, garnet, epidote, hornblende, spinel, iron oxides, sulfides, anatase, monazite, cassiterite and xenotime. Of these, ilmenite, leucoxene, rutile and zircon are the primary economic minerals. Garnet, monazite, cassiterite and xenotime are occasionally recovered as byproducts. The heavy minerals as a suite typically make up no more than 15 weight percent of a deposit and usually much less. Quartz and clay minerals form the bulk of the sediment. The geology of HMS deposits and examples of significant districts are summarized in Van Gosen and others (2014) and Hou and Keeling (2016)."

Oct 1, 2016

By Dru Brown

More than 150 Mt (165 million st) of material crashed down at the Bingham Canyon Mine (Rio Tinto/Kennecott Utah Copper) near Salt Lake City, UT on April 10, 2013. The mine, one of the largest openpit mines in the world, ceased operations and evacuated personnel prior to the slide when it was discovered that material was moving at a rate of 5 cm/d (2 in./day). The slide destroyed the mine?s visitor?s center, buried several pieces of large mining equipment and severely hampered production. The Kennecott Utah Copper Corp. immediately began to assess the damage and look for options to reestablish operations. The highly unstable ground ? emphasized by another minor slide in September 2013 ? makes any cleanup efforts extremely dangerous. With terrain too dangerous for human operators, Kennecott was forced to look for alternatives that would help the company work on the treacherous slopes of the landslide while also keeping personnel safe.

Jan 1, 2014

By R. D. Herron

Mining coal under deep cover conditions is certainly the proper phrase to use in describing one of our newest operations. Located in the southwest corner of Virginia is this operation which is the Beatrice Mine of the Beatrice Pocahontas Company, a joint venture of Republic Steel Corporation and Island Creek Coal Company. The mine is working in the No. 3 Pocahontas seam in an assigned area of over 9500 acres containing over 60 million tons of recoverable, high quality, low volatile coal. The site of the mine opening was at Keen Mountain, Virginia, where the seam lay 1350 feet below the surface. This depth, greater than anything attempted thus far in the coal industry on this continent, would pose some problems, we felt, with which we had not previously had to contend.

Jan 1, 1968