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By Leonard Sargeant

The Pocahontas Coal Field consists of eight mineable seams of low-volatile coal in southern West Virginia and Virginia. The deeper seams, especially the Pocahontas No. 3 and No.4 Seams, under heavy cover and below drainage are notoriously gassy. Methane in the Pocahontas Field is generally thought of as being confined in the coal itself, rather than in mud slips or clay veins. Furthermore, it is characteristic of Pocahontas coal to retain its gas until the coal is broken and removed from the solid. Because of this inability for gas to escape from unmined coal, entries developed around large blocks are seldom of significant value in bleeding off methane before pillar extraction begins. This is evidenced by the fact that it is not uncommon to find gas liberated during the mining of chain pillars and barriers which have been developed for several years. The Pocahontas Fuel Company develops almost all solid coal by conventional methods with shuttle car haulage. To provide the maximum productive capacity without compromising ventilation and safety requirements, the Company has adopted standards for ventilating 5, 6 and 7-entry sections.

Jan 1, 1960

By M. Niec

Lignite deposits in Poland occur within clastic Tertiary series at the depth suitable for opencast mining. Aboundant aquifers with the good quality waters that should be protected against contamination or depletion often accompany them. Landscape and underground water protection are the main regional environ-mental factors that limit the possibility of exploration and mining; presented on map of lignite bearing series distribution allow to delimit areas "free" for exploration and mining and areas where some limitations can be met up to no admittance of any industrial activity.

Jan 1, 1994

By Adolph V. Mitterer

International Minerals and Chemical Corporation operates one of six potash mines in the Carlsbad potash basin. More than 90 percent of America's potash is produced at Carlsbad and IMC accounts for about one-fifth of that amount, Since the Company began operations in 1941 it has mined nearly 50 million tons of ore. Of the two types of ore mined at Carlsbad the principal tonnage is sylvinite in which sylvite-potassium chloride-is the ore mineral. It is produced by IMC as well as by all other mines in the area, In addition to sylvinite IMC is the exclusive producer of langbeinite ore--potassium-magnesium sulfate. From its two ores, International produces a spectrum of 8 high-quality agricultural and industrial chemical products.

Jan 1, 1959

By William F. Jenks

The possibility that a hypothesis explains almost all observed facts may be satisfying. Yet the almost gives a distinct sense of uncertainty. Moreover, overlooking the almost, reliance on the favored hypothesis may close our eyes to the discovery of new information and, in the field of mineral exploration, to the possibilities of finding new and hidden ores. A case in point is that of mines such as the Elizabeth and Ely, along the copper belt in eastern Vermont, principally in Orange County. The geology of the Strafford Quadrangle, where the Elizabeth Mine is located, has been described by Doll (1944). Two informative papers (McKinstry and Mikkola, 1954, Howard, 1959) present much valuable information about the geology of the Elizabeth Mine. Both reach the conclusion that the ores were emplaced after the peak of metamorphism, through the agency of metal-bearing hydrothermal solutions. Both, therefore, conclude that the source of the ores was somewhere below the outcrop area, presumably in some hidden intrusive mass. Neither yields a satisfactory guide for further exploration. Howard (1959) cites geophysical observations which show that there is a mass with a density similar to that of granite under the Strafford dome, adjacent to the Elizabeth Mine on the West. Yet examination of gneissic granite in the Chester dome, 25 miles to the South gives no suggestion of a young, near-surface intrusive capable of carrying or mobilizing large quantities of sulfur and metals. The Acadian intrusives in New Hampshire and in the Barre district

Jan 1, 1968

By Eugene C. Robertson

The exchange of heat from wall rock to ventilating air was studied in a cross-cut driven through fresh rock on the 4600 level of the Kelley Mine, Six- teen thermocouple probes, 10 inches long, twenty-three probes, 7 feet long, and five probes, 50 feet long, were emplaced in the walls soon after blasting and wall -rock temperatures were monitored intermittently over a two-year period to determine heat loss from the wall rock. Temperatures, humidity, and velocity measurements were made of the air at the same times to determine heat gain. An important but less well-defined variable was the heat transfer by water entering the crosscut from fractures and leaving in the ditch. The balance of heat in and heat out at each probe station is within an acceptable range. Theoretical and empirical models for heat flux into a cylindrical opening fit the data reasonably well, also.

Jan 1, 1970

By James B. Loftis

The importance of increasing the world's mineral production to help solve our food and energy problems has been widely discussed. Improved surface mining methods will be needed to meet these needs. This paper reviews the modern horizontal drilling and blasting methods which can increase the productivity and lower the costs of I surface mining. A substantial decrease in the number of blast holes required, total footage of blast hole required and amount of explosive used has been realized by many mining companies using this method. Applications of this method are presently in large coal surface mines. However, similar gains are possible and probable in open pit mining of copper and iron.

Jan 1, 1975

By G. J. Hodges

The Stillwater Mining Company, a partnership of Pittsburg & Midway Coal Mining Co. and Manville Corporation, operates a precious metals smelter at Columbus, Montana to further up-grade concentrates from its platinum/palladium mine. The smelter began operation in the summer of 1990. The gas cleaning system in the facility utilizes "oxidation/dilute mode" dual-alkali scrubbing technology to capture sulfur oxide gases from the process gas streams. This paper describes the rationale for selecting the dilute mode dual-alkali system and summarizes design parameters. Start-up problems and their solutions are also discussed.

Jan 1, 1992

By C. B. Manula

The application of computers to materials handling problems has recently been investigated by various mining groups. This approach has been found, especially useful where a large amount of alternatives must be investigated prior to arriving at a final decision. These alternatives may be expressed in terms of man hours, units and types of equipment such as trucks or conveyors, or the allocation and operation of proposed or existing haulage facilities. The decision problem becomes especially evident when we consider the mechanical revolution which has flooded the mining industry in recent years. The industry has become highly competitive, with the need to keep low profit materials away from high cost production faces ever increasing. The capital investment required for the highly sophisticated equipment that is necessary to perform this function is generally great, and management is faced with decisions which must all too often be made without sufficient data.

Jan 1, 1967

By C. D. Harrison

This paper presents the results of 18 high-G centrifuge tests performed at the Electric Power Research Institute's Coal Cleaning Test Facility in January 1985. These tests, using -28 mesh (0.6mm) froth flotation product, show that the high-G, solid-bowl centrifuge can produce clean-coal moistures of less than 12 percent at solids recovery rates exceeding 98 percent. The high-G centrifuge achieved these low moistures by applying centrifugal forces up to 2,000 times gravity. Because these forces are two to three times the forces used in a screen-bowl centrifuge, the high-G centrifuge can use a solid bowl and still produce a low-moisture product. The solid bowl captures ultrafines that would pass through a screen bowl, and thus obtains higher recovery rates than a screen-bowl centrifuge.

Jan 1, 1985

By Henry T. Mulryan

The philosophy, strategy and techniques of successful marketing of talc, differ sharply from those applied to most other mined products. Unlike non-ferrous metals, there are no commodity exchanges to facilitate the transfer of goods. Unlike iron ore and some non-metallics, assured markets by means of long term contracts are practically non-existent. Talc must be sold and sold and sold again. The normal channels of talc distribution are almost identical to those used, by the chemical industry. These consist of a blend of producer marketing staff, field technical service, and sales force; and independent chemical wholesalers. Like the term "chemicals", there is tremendous product diversity contained in the rather loose expression "commercial talc". Certain kinds of talc, processed in conventional ways, are regarded as commodities by the consumer. That is, that material from one source or supplier is considered to be effectively interchangeable with those available from a number of other areas and producers. Under such conditions, lowest delivered price, quickest delivery, and best, customer service, are the key factors in a successful sales effort.

Jan 1, 1965

By Wayne P. Myers

Electricity, as normally thought of by a layman's definition, is a man- made force that has no color, no odor, is not visible, cannot be heard, yet man can control it and make it perform his work for him. A person dare not cheat on it, for it then will master him. It has laws, rules, and regulations that must be strictly adhered to if it is to perform in the safest, most reliable, and economical manner. In the early days of coal mining the power source was man himself. Later man employed steam and compressed air to reduce his muscle power requirements needed in the extraction of coal. By the turn of the 20th century, electricity had become the most common source of power for the coal industry. Steam and compressed air are still found in use in isolated cases today for specific applications; however, they are rapidly being replaced by electricity. Electrical laws and regulations are quite extensive and somewhat complex for the proper generation and use of electricity. Man-made laws, rules, and regulations for the care and handling of electricity, designed for man's safety, are rigidly enforced by Mine Safety and Health Ad- ministration (MSHA), as well as the various state departments of mines.

Jan 1, 1981

By William M. Phillips

This paper will concern the processing of kaolin clays from the sedimentary deposits of Georgia and South Carolina, While the major processing steps will be touched on briefly, emphasis will be given to the dewatering of the clay-water slurries (slips) formed in the processing of kaolin clays The dewatering steps discussed will include gravity settling, centrifugal dewatering, vacuum filtration, and thermal dryings Of these dewatering steps particular attention will be given to vacuum filtration and the variables affecting filtration of these kaolin clays.

Jan 1, 1962

Horizontal stress is an important factor that contributes to roof failure during a long wall entry development, especially when the immediate roof is weak. In this study, the effects of the three factors, the stress angle between the maximum horizontal stress and entry development, the stress ratio of the maximum to the minimum horizontal stresses, and the sequence of entry development, on the stress distributions in the weak immediate roof of a three-entry system are analyzed using the finite element method, when the horizontal stress is fixed. The results have confirmed that the stress angle has a significant influence on the stress distributions. Generally, the three-entry system is in the worst stress condition when the angle is about 60°_75°. The stress ratio has little effect on the roof stresses. In addition, the sequence of entry development has also little effect on the roof stress for the specific case analyzed.

Jan 1, 1999

By Carolina Bruecker, Axel Preusse

"The topic of ground movements in Germany has been studied extensively in the past, especially in the field of active mines. The active hard coal mines were finally shut down in 2018 in Germany and lignite mining is expected to take place only until 2038. The so-called long-term liabilities of the mine operators in Germany include, among other things, the long-term guarantee of stability and thus the monitoring of ground motion.So far, the economic use of underground mining in Germany was mainly the supply of raw materials. In the future, the underground storage of compressed air, methane, or hydrogen will play an important role in renewable energy supply and climate change. Therefore, underground storage space will become more important and spatial planning is essential to ensure availability of safe underground openings for the various options of environmentally friendly energy storage.However, this renewed usage of underground openings may also bring new and sometimes unknown challenges of geomechanical influence. On the one hand, the aftermath of hard coal and lignite mining will be an increasing challenge in mining subsidence engineering. On the other hand, new possibilities due to underground spatial planning may lead to subsidence and/or heaving of the upper surface.INTRODUCTIONBoth hard coal and lignite have a long tradition in Germany. The Prosper Haniel mine in the Ruhr area was closed at the end of 2018 after 150 years, which signalled the end of hard coal production in Germany. Lignite mining still takes place in the Central German, Lausitz, and Rhineland districts. However, lignite mining in Germany is expected to be phased out gradually by 2038 (MDR, 2019). With the closure of these mines, however, mining damage is not over. The long-term consequences of mining, which extend far beyond the closure of the mines, are associated with the liability and responsibility of the individual mining companies. The so-called eternity burdens on the mining company continue to apply. In the field of lignite production, the discontinuation of dewatering and the resulting possible elevations of the surface will be a relevant topic for the future of mine surveying. The same applies to the hard coal mines, which are partially flooded in Germany and therefore require extensive monitoring of soil movements in the future.The discontinuation of energy from hard coal and lignite calls for a change in the energy mix. With the renewable energy revolution in Germany, the focus is on a sustainable and environmentally compatible climate and energy policy based on renewable energies. Sustainable use of the subsoil, both natural and anthropogenically produced cavities, will play an essential role in the objectives of this policy. For example, disused mine cavities can be used to store electricity from renewable energy sources. (Umwelt Bundesamt, 2018) These functions will again cause classical ground movements such as subsidence and uplift, but will also bring new challenges for the mine surveyor. Challenges can be underground cavity exploration in inaccessible areas or legal aspects of underground competition."

Jan 1, 2019

By Stephen H. E. Phillips

Geological and hydrological conditions in the strata overlying the Salado Formation vary considerably in the Carlsbad, New Mexico area. The first four shafts sunk at international Minerals and Chemical Corporation's property have been located in competent and essentially dry conditions, while other shafts on adjacent properties have had such adverse conditions that ground freezing has been chosen as the water and ground control technique for shaft sinking. At the location of the IMC No. 5 Shaft there has been extensive-erosion and salt dissolution in the Rustler Formation which has led to collapse of some zones of the strata. Both ground freezing and pregrouting were considered as alternative methods of stabilizing the extremely poor ground conditions and controlling the potentially very heavy water inflows it was decided that pregrouting the shaft was feasible and would offer substantial cost and time saving over a ground freezing technique. This paper describes the pregrouting techniques used and illustrates the requirement for flexibility in a grouting program so that it can be codified to reflect any new or additional information which is obtained during the progress of the grouting.

Jan 1, 1984

By Anthony G. Fonseca

The acid leach-solvent extraction processing of oxide copper ores can be improved when selected cation additives are utilized. Bench scale testing showed improvements in both sulfuric acid leaching and solvent extraction processing. Treatment with the method to be described shows improvement in copper recovery in the acid leaching section as well as reduced acid consumption and reduced iron and aluminum dissolution. Processing the copper bearing leach solution with LIX-64N shows increased loading of the LIX reagent which relates to reduced aqueous and organic flow rates, reduced organic loss and inventory as well as a reduction in the size of mixer-settlers. The use of selected monovalent cations controls fluctuations within the pro- cessing system to accomplish the above named improvements. Additionally, these cations are totally compatible throughout the processing system and are quite inexpensive. Bench scale recycle data will be presented both for the leaching section and the continuous solvent extraction processing section up to (but not including) processing the loaded electrolyte. Material balances as well as major solution component monitoring will also be presented.

Jan 1, 1975

By T. P. Meloy

Riffles on a shaking table have a major effect on particle separation. This effect is modeled in a spreadsheet.

Jan 1, 1993

By Louis D. Murino

Compared to coal or many metals industries, talc must be considered a small, specialty market catering to niches and dependent primarily on the physical attributes of the mined and processed mineral rather than the chemical attributes with copper, lead or uranium concentrate, the primary objective is the percent metal that ultimately is refined by the smelter, as opposed to the brightness, particle size distribution, trace impurities or morphology. The latter constitute the important determinants of where, how and why talc and similar industrial minerals are used. This paper addresses the talc market-place: where it is, how much of a market there is, who the producers are, available capacity, market growth, and marketing techniques.

Jan 1, 1984

By C. W. Overton

The operations of Bethlehem Copper are situated in the south-central interior of British Colombia at an elevation of 4900 feet above sea level. Main road and rail transportation systems pass through Ashcroft in the Thompson Valley, which is 28 miles by road from the minesite. The operation was the first low-grade open-pit porphyry copper mine in British Colombia. The minerals are chiefly chalcopyrite and bornite, while the rock is principally feldspar and quartz. In the outer fringes of the orebodies sane pyrite is present. Average grade of mill feed is 0.55% copper.

Jan 1, 1973

By George F. Weaton

During the past eight years there has been a dramatic change in the iron ore industry of Minnesota, in that its status has changed from that of a seller's market to a higly competitive buyer's market. Minnesota's natural ores must now be beneficiated and up-graded considerably to be marketed in order to compete with the higher grade foreign ores as well as with the locally produced and highly desirable taconite pellets. With the passage of the "Taconite Amendment' in the November, 1964 election, the taconite industry commenced to expand in Minnesota, which, although initiated in that state, was benefiting many other states and some foreign countries to a much greater extent than Minnesota. These other areas were actually appropriating markets that had been established and retained by Minnesota for many years. Since the approval by the state voters of this amendment, there has been a great increase in the development of taconite properties on the Mesabi Range.

Jan 1, 1966