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By John C. Edwards, F. Friel, John J. Opferman, Robert A. Franks

A series of diesel fuel fire experiments were conducted in the Pittsburgh Research Center's Safety Research Coal Mine (SRCM) to determine products-of combustion (POC) spread rates along a single entry under zero imposed airflow conditions. Six experiments with an average fire intensity of 330 kW and three experiments with an average fire intensity of 30 kW were con- ducted in a 180 m long entry which had an average 2 m height and 4 m width. POC spread rates were measured by the response time of diffusion type CO detectors, positioned at 30 m intervals, to CO concentrations 5 ppm above ambient. For the 330 kW fires, average POC spread rates of 0.22, 0.1 3, and 0.06 m/s were determined at 30, 60, and 90 m distances from the fire. For the 30 kW fires these average spread rates were reduced to 0.08, 0.04, and 0.04 m/s. The measured maximum roof layer temperature 30 m from two of the 330 kW fire was 30 and 36"C, which is less than the 57°C alarm point of a typical mine thermal sensor. It was determined that smoke detectors can be more effective for mine fire detection than CO detectors. The experimentally determined POC spread rates can be used to provide guidance for specification of sensor spacing to improve early fire detection at zero or very low air flows.

Jan 1, 1997

By J. W. Mahar, E. J. Cording

INTRODUCTION In exploration for rock tunnels, the geology should not only be described, but its effect on excavation and support assessed. It is not an easy task to correlate exploration results with support and excavation requirements, even when the exploration program is detailed and geologic conditions are relatively well known. Many of the significant geologic features are subtle and their effect is difficult to interpret from exploration results. However, in similar geologic settings, there are specific geologic features which will cause recurring support problems. Such features should be actively sought out when exploring in a given geologic setting. In blocky and seamy rock, the primary features controlling performance are the joints, shears, and shear zones. This paper describes the effect of such features on the formation and movement of rock wedges in tunnels driven in foliated metamorphic rocks in Washington, D. C. and New York City. In both areas the foliation commonly forms a N-S striking plane of weakness along which major shear zones, shears, and joints have formed. In addition, the structural history of the two areas has been similar, so that there are similarities in the orientation and character of the other major joint sets and shear zones in the rock mass. The observations were made in tunnels ranging from 10 to 70 ft in width and excavated at depths ranging from 80 to 800 ft. Most of the tunnels described were deep enough to be located in unweathered rock, or in rock only slightly weathered along joints and shears. Variations in the planarity, filling, spacing, and attitude of joints, shears, and shear zones accounted for significant differences in the

Jan 1, 1974

By T. Shungu, N. Vermaut

The various copper-cobalt ores mined by Gecamines, together with typical plant applications and results, are briefly described. Intensive laboratory investigations have been undertaken in recent years to improve the metallurgical performances of the various concentrators. As a result of these tests, it was shown that the flotation of the siliceous oxide ores could be improved by increasing the efficiency of the palm oil collector (energetic conditioning, chemical emulsifier, petroleum sulfonate addition) and by varying the froth depth in the cells. A new flowsheet incorporating these modifications and a regrinding stage has been approved for the rehabilitation of the Kolwezi concentrator. For what affects dolomitic oxide ores, hydroxamates were tested as secondary collectors and, based on successful laboratory results, plant trials were run but failed due to excessive frothing. In other plant tests, xanthates were replaced by a xanthate- fatty acid mixture; plant trials over more than one year proved successful for copper, but not for cobalt. Mercaptans were tested as secondary collectors for the sulfides flotation from sulfide or mixed oxide-sulfide ores; laboratory results proved successful but, to date, no plant test has been run.

Jan 1, 1987

By Ajay Mahajan, Manoj Mohanty, Vishal Gupta

Modern coal processing plants utilize multiple cleaning circuits to efficiently beneficiate different size coal fractions of run-of-mine coal. An older plant optimization approach is to maintain average product quality from individual cleaning circuits at the same level as the given product specifications for the overall plant. However, many past studies indicate that the equalization of product quality approach fails to produce the maximum plant-yield. A newer approach, known as equalization of incremental product quality, requires that the incremental product quality obtained from each circuit be maintained at the same level to satisfy the overall plant product quality. This approach ensures the maximization of plant yield while satisfying a single product quality constraint. However, while dealing with multiple product quality constraints, this approach by itself may not be sufficient to obtain the desired maximum yield. For the simple reason that the dirtiest particle (or group of particles) with respect to one quality constraint may not be the same particle (or group of particles) with respect to another quality constraint, the mass yield versus product quality relationship generated by equalizing different incremental product quality may not be exactly the same. Therefore, an additional search technique has to be utilized to determine the global-maximum value of plant yield. Thus, the main objective of this study was to utilize an emerging optimization technique, known as genetic algorithms (GA) to maximize plant yield while satisfying multiple product quality constraints. The maximum plant yield obtained from this approach was nearly same as the maximum yield obtained by the incremental product quality approach while satisfying one specific product quality constraint. The GA was applied on a coal preparation plant that utilizes four circuit operations - heavy medium bath, heavy medium cyclone, spiral and froth flotation. The results showed that using GA as an optimization process gives 2.56% higher yield that will result in additional revenue generation of $5,120,000 per annum than average product quality approach.

Jan 1, 2005

By Robin J. Hickson

The Grasberg copper-gold deposit was discovered in the spring of 1988, one year before the planned closure of Freeport Indonesia's original Ertsberg openpit copper mine. In spite of Grasberg's remote location, 600 m (1968 ft) above the Ertsberg, atop a hitherto inaccessible mountain, Freeport-McMoRan brought its latest open-pit mine into production in the last week of 1989, less than two years after discovery. Freeport Indonesia's (FI) copper-gold mining operations are located in Irian Jaya, the easternmost province of Indonesia on the western side of the island of New Guinea. Fl's six ore deposits are all located within a 10- x 10-km' (3.9- x 3.9-sq mile) Contract of Work area. They are all between the elevations of 2900 and 4300 m (9515 and 14,100 ft) above sea level, some 96 km (60 miles) from the island's southern coast. A 118-km (74-mile) access route connects FT's port site of Amamapare on the Arafura Sea to the project area. The first section is an 18-km (11-mile) barge waterway. The final 100-km (63mile) is a two-lane gravel highway. The highway terminates 9 km (5.5 miles) beyond the FI townsite at the project's central mill, some 2850 m (9250 ft) above sea level. The mining areas are separated from the mill by a 780-m (2560-ft) sheer cliff face. The world's longest free span tramway system, with a total length of more than 1.6 km (1 mile), is the only means of access for men and materials between the mill and the surface mines. Weight restrictions for the tramway for equipment considered for the project are 15.4 t (17 st). The minimum clear width dimension of two tunnels along the portsite access road is 5.6 m (18.4 ft).

Jan 1, 1991

By William Moser, B. P. Shagula

INTRODUCTION Every day mine management and mining personnel face the threat of a possible mine disaster or fire. Their ability to deal with such a situation safely and effectively depends on the level of emergency preparation developed and maintained. After conducting numerous informal evaluations or audits at different mine sites throughout West Virginia (as well as other states), the authors concluded that many mining operations are not prepared to handle a fire situation. The results of the audits indicate that while most mines are in compliance with federal and state legal regulations regarding levels of emergency equipment, water systems and training sessions, these levels - particularly in the area of fire training - are probably not sufficient to enable the mine employees to effectively combat a fire in its early stage. This paper will present the authors' recommendations for designing and maintaining an efficient mine emergency preparedness Program and an overview of the curriculum of the mine fire training Program currently being conducted. MINE EMERGENCY FXEPAREDNESS PROGRAM The Mine Emergency Preparedness Pro- gram (MEPP) is a management tool developed by the Mining Extension Service at West Virginia University and was designed to assist company personnel in effectively managing a mine emergency operation. The program goes beyond the traditional and required training of mine rescue teams by offering a complete emergency operations package. Included in MEPP are suggested approaches for training and organizing all personnel, ideas for developing plans of action concerning transportation, security and communications. The MEPP program may also be used as to assess present readiness levels. While the MEPP program is designed to address all types of emergency operations, the authors are convinced that emergencies involving mine fires are the ones of greatest concern and so are concentrating their efforts in that direction. Incidents where fires are involved seem to be increasing in frequency and are extremely costly to control if allowed to go beyond the incipient stages. With a proper emergency preparedness program in place and properly trained and equipped fire brigades, the authors feel that it is possible

Jan 1, 1992

By A. H. Morris, W. Harrison

1. INTRODUCTION Roadheaders have a shadowy origin - probably in Eastern Europe - but were introduced to Europe and the West by the importation of a Russian PK3 machine by the National Coal Board in 1961. A number of features rendered this type of machine an attractive tool for coal mine operators: its flexibility of operation, its combined cutting and loading ability, the opportunity it provided of making any shape of roadway, as well as its ability to cut some rocks. Encouraged and sponsored by the National Coal Board, the development of roadheaders was taken up in Great Britain, notably by Anderson Strathclyde and Dosco; in Europe, predominantly in numerical terms by Voest Alpine and Paurat. Over the 24 years since the importation of the first PK3, evolutionary development has taken place to the extent that machines are now available in many forms up to 120 tons in weight. Machine design has altered, partly as a result of increased power requirements and partly in line with the use of a ripping or a co-axial head. However, the basic concept remains: a boom containing a motor and transmission gear, with a driven cutting head at its extremity and capable of universal movement urged by hydraulic rams mounted on the boom turret and on the machine deck. Generally, the turret, hydraulic powerpack and all other necessary equipment are mounted on a chassis, which contains a discharge conveyor, the whole being carried on caterpillar tracks so that a complete machine entity is provided. Figure 1 shows how the weight, power and - non-proportionally - the cutting ability of machines have increased over the years. From

Jan 1, 1985

By William R. Beloff, Franklin M. Grynkewicz, Puza

Construction of the MBTA Red Line Extension through Somerville, MA, called for driving twin tube tunnels through a zone of approximately 83m (273 ft) with mixed face conditions. While the majority of the tunnels were driven through competent hard rock using drill and blast techniques, the mixed face zone was advanced using floating crown bars for primary support. The overburden consisted of medium clay, underlain by water bearing glacial till, over a sloping bedrock surface. Due to the unusual nature of the construction techniques, a program was undertaken by the Contractor to monitor ground movement and stresses in the temporary steel supports. This paper presents a description of the instrumentation employed, as well as the measured ground movements and support stresses. Additionally, the tunneling techniques are briefly presented and commented upon. PROJECT DESCRIPTION The Davis Square to Porter Square Tunnel Contract is part of the Massachusetts Bay Transportation Authorities (MBTA) Red Line Extension from Harvard Square in Cambridge to the Alewife Brook Parkway via Somerville. The 5.1km (17,000 ft) Red Line Extension consists of four major new stations, three of which will be interlinked via tunnel construction, and the remaining station will be the last link of an open cut portion, and a terminal point for this phase of the extension. This 866m (2,790 ft) portion began at Porter Square in Cambridge and rose at a 4% slope through Somerville, terminating at the new Davis Square Station. Twin tube tunnels were constructed through 763m (2,517 ft) of rock and 83m (273 ft) of mixed face conditions at the Davis Square end. Figure 1 presents a plan view of the entire contract.

Jan 1, 1981

By Craig Ammar

JAMIE DAVIS: Our next speaker is Craig Ammar. He's director of equipment management for Cyprus Climax Metals Company. He has, prior to this assignment, been responsible for maintenance at Bagdad Copper, Cyprus' Miami smelter, and Thompson Creek. Like Jerry, he's very shy and retiring, and doesn't have any strong opinions about maintenance. INTRODUCTION CRAIG AMMAR: The ultimate goal behind implementing a proactive equipment management process is to provide capacity assurance and ultimately increase an organization's ability to generate revenue while reducing operating costs. Targeting such lofty objectives has brought many an organization to its knees, utilizing new maintenance techniques, concepts, and technology aimed at making our lives better and more organized. The root cause of such frustration generally stems from a lack of understanding or support for the fundamentals of implementing a proactive equipment management process. There are just two types of maintenance programs, reactive and proactive. It's an established fact that you need a little of both to run an effective equipment management process, obviously more of one (proactive) than the other. Here are some telltale signs that your equipment management process is in trouble: -Maintenance is performed as a knee jerk reaction when equipment fails. -Repeated and frequent equipment failures occur, with no focus on eliminating the root cause. -Sketchy, inconsistent, unclear preventive maintenance is performed or there is no support for the preventive maintenance process. -No predictive maintenance technology process is in place, or little support for predictive maintenance exists. -Less than 50 percent of your work is generated by the maintenance group resulting from inspections.

Jan 1, 1998

By Gerald L. Finfinger, Michael A. Trevits

Since 1964, the US Bureau of Mines has been conducting a comprehensive program of research on the origin and control of coal bed gas. Several extensive databases have been developed during the work representing information from every major coal producing region in the United States. Gas content measurements have been made on 885 coal samples from 15 states representing 221 coal beds. Records indicate that the range of gas content varies from zero to over 640 ft3 per ton (20 cm3 per gm). During the conduct of the research program, several drilling and completion techniques have been developed or refined to divert and collect coal bed gas before it enters the mine environment. Such techniques include horizontal, cross-measure and vertical boreholes. Samples of gas collected from boreholes drilled under the program indicate that the primary gas constituent is methane which comprises 97 pct, the remaining hydrocarbons make up approximately 0.2 pct. Nitrogen and carbon dioxide account for the majority of the remaining gases at average concentrations of 1 pct each. Surveys have been made on the total daily gas emissions from underground coal mines. In fact, the most recent survey indicates that 180 mines had emissions in excess of 100 Mft3 per day (2.8 Mm3 per day). Furthermore, total mine emissions were in excess of 300 MMft3 per day (8493 Mm3 per day). An analysis of the data showed that there appears to be no relationship between in-place gas content and coal bed gas composition. Furthermore, no correlation was observed between in- place gas content and daily mine emissions. In a general sense, the higher the gas content the higher the relative gas emissions. Perhaps a more direct relationship would be observed if more complete emissions information (including gob gas borehole production) was available.

Jan 1, 1989

By James J. Olson

INTRODUCTION The need for Government-sponsored research and development to increase excavation rates and lower costs for tunneling and mining operations in a variety of rock types has been emphasized in a wide range of publications from advisory panels, symposiums on rapid excavation, and individuals. In response to the predicted demands for mining and construction-oriented underground excavations for the next two decades (1970-1989), a comprehensive 10-year, $200-million research program in rapid excavation was proposed by the National Academy of Sciences in 1968 (1). Although the large program recommended by the Academy has not been funded, substantial Government-sponsored research in rapid excavation has been conducted during the past several years. This paper reviews some of the significant research accomplishments obtained under a three-year, $6.6-million research program in rock mechanics and rapid excavation sponsored by the Defense Department's Advanced Research Projects Agency (ARPA) and managed by the Bureau of Mines. In addition to the rock mechanics research, five major phases of excavation; systems analysis, geologic prediction, rock disintegration, ground support, and materials handling were represented by the projects funded under the ARPA program. The brief outline below recapitulates the major research areas and some of the projects summarized by this paper: Excavation Process Modeling by Computer Geologic Prediction Geologic Reconnaissance for Site Selection Longhole Probe Drilling for Hazard Detection

Jan 1, 1974

By Naj Aziz

Both bolt profile shape and spacing (rib spacing) have been found to influence the bonding capacity of the grouted rock bolt. The bolt surface profile configuration has greater importance to rock bolting in strata reinforcement in mining than the steel rebar used in civil engineering construction. This is because a rock bolt in mining usually is subjected to greater dynamic loading than the steel rebar in civil engineering construction. The increased bonding capacity of a bolt is important when supported ground is either heavily fractured, faulted or the supported ground is of soft formation, typically that of coal measure rocks. Past laboratory studies have identified the bolt profile spacing as of significant relevance to bolt resin rock bonding increase, however, no attempt has been made to determine the optimum spacing between the bolt profiles spacing. Accordingly, a series of laboratory tests were carried out on 22 mm core diameter bolts, commonly used in Australian mines, installed in cylindrical steel sleeve. The study was carried out using both push and pull testing methods. The push test was carried out in 150 mm long sleeves while the pull testing was conducted in 115 mm long sleeves. Profile spacing tested include, 12.5, 25.0, 37.5, and 50 mm lengths. Additional studies undertaken include modelling the profile of the load-displacement data of pull testing. Bolts with a profile spacing of 37.5 mm were found to provide optimum load bearing capacity as compared to other tested profile spacings.

Jan 1, 2009

By Ron Robinson

Booster fans have been in regular use in British coal mines since the first half of this century, but a large increase in their use did not take place until after the Nationalization of coal mines in 1947. From that time the need was identified to improve standards of ventilation in general and mining engineers specializing in ventilation were appointed at all levels in the mining industry. A comprehensive approach to ventilation surveys and planning, together with the realisation of the benefits of booster fans, led to their more rapid introduction. Many coal mines in the U.K. are at moderate depth and have virgin strata temperatures of 30°C or less. The ability to control climatic conditions by increased ventilation rather than resort to cooling systems has led to the introduction of booster fans and recirculation systems in these mines. Large makes of methane and high levels of coal dust production due to increased mechanization have also required enhanced ventilation standards. This paper deals with the reasons for selecting booster fans and the specific safety considerations involved in their use. Numbers, types and sizes of booster fans in the U.K. are outlined, together with notes on installation and performance. Remote monitoring and control from the surface is dealt with, and current legislation. The evolution of controlled recirculation is also covered starting with auxiliary fan systems in 1970 and leading to very large district schemes in the late 1980s. The research at Newcastle upon Tyne University and other establishments in the climatic conditions associated with recirculation is summarised and its use in assisting existing and proposed conventional and recirculation systems is indicated.

Jan 1, 1989

By M. G. Ayat, J. W. Leonard

Introduction Coal preparation plants are continuously losing clean coal in their refuse and contaminating their clean coal product with impurities. This is due to the lack of a system by which the immediate efficiency of the cleaning operation can be determined at any given time. Moreover, the advantage of developing tagging/ tracing techniques would be a reduction in the time and money spent in evaluating the performance of advanced cleaning techniques. Currently, conventional sampling and testing, on-line analyses, and computer information systems are the major tools with which engineers analyze and control the efficiency of processing plants. Conventional sampling and testing is an effective analysis technique but it is slow. On-line analysis provides information on quality parameters rapidly, but these parameters do not provide all of the necessary information. The use of tagged particles in coal preparation plants may provide the necessary link between diagnosis and the application of computers to process control. In this work, a novel technique that uses tagged particles to generate partition data is presented (Leonard et al., 1982). Individually prepared tagged particles are added to the feed and detected in the product or refuse port of specific gravity based processes. Providing that a computer can interpret the output of a detection device and trace particles with predetermined physical properties through the coal preparation plant and that the trace particles actually represent desired raw material, sufficient partition data can be provided for computer analyses and control of processing efficiency. Coal tagging technique The use of tagged particles in coal preparation operations are in the early stages of development. Though there is a brief history of particle tracing in the mineral processing industry (Gardner et al., 1986; Foreman and Amundson, 1976; Poston et al., 1962), the concept has not yet been applied to the analysis and control of processing plant operations. Several methods for tagging coal particles have been identified. These include magnetic, radioactive, and fluorescent techniques. As far as the magnetic tagging of coal particles is concerned, a method has been developed to manufacture synthetic magnetic particles of various sizes and specific gravities. Ideally the synthetic particles would have identical size and density as the coal particles being separated.

Jan 1, 1988

By William J. McCloy, Robert L. Gamble

A coal-fired fluidized bed steam generator rated at 12.6 kg/s has demonstrated the industrial and institutional application of fluidized bed combustion by burning high sulfur coal in an environmentally acceptable manner within a populated area. Designed to provide steam for heating and cooling, the unit was placed into service at Georgetown University in Washington, DC, and has already logged 5275 hours.* The unit has consistently operated well within Washington's strict regulations governing emissions of sulfur dioxide (SO2), nitrogen oxides (NOx), and particulates. The Georgetown program, cofunded by the university and the US Department of Energy, has shown that fluidized bed combustion is a promising way to realize the full potential of coal, the nation's most abundant energy resource. In a fluidized bed steam generator, a layer of granular limestone is placed on top of a grid designed to prevent particles from falling through. Air is passed upward through the bed with sufficient force to lift and float the particles. At this point the bed material resembles a boiling liquid. Crushed coal is then introduced into the bed and ignited. When high sulfur coal is burned, limestone absorbs the SO2 produced. The operating temperature of a fluidized bed steam generator is relatively low (approximately 871°C). As a result, NO, formation is minimal. Another potential problem encountered in burning coal is fly ash, a form of particulate. A feature of the fluidized bed design, developed by Foster Wheeler Energy Corp., is a fly ash reinjection system. Fly ash is reintroduced into the bed where it is burned again, thereby enhancing fuel efficiency. Nearly all remaining fly ash is captured by a baghouse dust collector. At Georgetown, the fluidized bed steam generator and all auxiliary equipment are enclosed in a structure aesthetically compatible with the surrounding university complex. The steam generator has two separate beds that can be fired independently, and operation to date has been with one and two beds in service, based on steam load demand. During several operating periods, when the fluidized bed unit was the only boiler in service, it supplied all the steam required by the 18.5 hm2 of buildings on campus. Initially fired with low sulfur coal, the unit was quickly switched over to higher sulfur fuel which will be used most of the time.

Jan 3, 1981

By John S. Timmons, Eivind B. Jensen

The Henderson mine is an underground panel-caving molybdenum mine located in the mountains of central Colorado. All development and primary production operations are performed using diesel-powered, rubber-tired mobile equipment. The growth in manpower and equipment was rapid in the five years following the July 1976 start-up, reaching about 250 machines and 2000 people to produce 9 Mt/a (10 million stpy) of ore. However, due to dramatic improvements in productivity, production is currently at a rate of 8.1 Mt/a (9 million stpy) with about 570 people and a much smaller equipment fleet. The mine's high degree of mechanization and accompanying maintenance costs have focused increased attention on the maintenance function as a cost center with potential for improvement. To realize some of that potential, several approaches to equipment maintenance have been adopted. None of these stand alone effectively, though, and their success relies on their working together in the overall program. The approaches that characterize the equipment mainte¬nance philosophy at Henderson are described here. Preventive maintenance The value of preventive maintenance as an alternative to breakdown or emergency repair is widely accepted in industry. When production began in 1976, few people at Henderson had experience maintaining diesel-powered, rubber-tired equipment. Other company operations such as its previous Urad operation and the Climax molybdenum mine near Leadville, CO used rail and Blusher technology. A maintenance consultant was hired to establish a formal preventive mainte¬nance program. The initial program contained four different preventive maintenance services, "A," "B," "C," and "D." Each was keyed to a different operating interval. • "A" service was the most frequent. It was a quick, general inspection and greasing of all fittings. •"B" service added a more detailed inspection. • "C" service included changing all filters and most fluids, such as engine oil. • "D" service was originally designed as a comprehensive inspection and testing of major component systems over a period of 24 hours during which the equipment was removed from operation. It was believed that most problems uncovered by the inspection could be reported and scheduled for repair at some later date, with only critical repairs being done during the service. In addition to these scheduled preventive maintenance services, a schedlle of minor and major rebuilds at intervals of 2500 to 5000 hours was established.

Jan 1, 1989

By L. Alan Weakly

This paper was presented at the ‘17th U. S. Symposium on Rock Mechanics’ on August 29, 1976, at Snowbird, Utah, at the SME-AIME Fall Meeting on September 1, 1976, at Denver, Colorado, and at the Polish-American conference on Ground Control in Room-and-Pillar Mining on August 7, 1980 at Southern Illinois University, Carbondale, Illinois. Introduction The purpose of this paper is to present a viable method of reinforcing rock pillars by utilizing fully grouted reinforcing steel and a cement- fly ash mortar. Although the fully bonded bolt concept is not new as exemplified by the present widespread use of resin bolts within United States mines and by the use of cement grouted reinforcing used as back pins in the Kiruna Iron Ore Mine in northern Sweden, (1)(2)the method of stabilizing mine pillars with fully bonded reinforcing is new. This method, called the "grout-rebar system", was first incorporated at St. Joe Minerals Corporation's Fletcher Mine in December of 1972. The system was used on an emergency basis before extensive research on the mechanics of the system could be completed. Since Decmeber of 1972, however, approximately 206 pillars have been reinforced at Fletcher and the system is currently being used on a regular basis at two other St. Joe mines and at two competitor mines in the area. Basically, this paper is a case study of the efforts, research and results of utilizing the grout-rebar system, on a selective basis, at the Fletcher Mine. In addition to information about the system, this paper will explain in detail the three rock mechanics instruments developed by St. Joe and used to measure and monitor rock movement to validate the group-rebar system.

Jan 1, 1982

By James W. Babcock

Introduction Geologic ore deposit models are key to any exploration program. In the search for ore deposits, the geologist first tries to understand the genesis of known ore bodies. During reconnaissance and evaluation of a prospect, a valid exploration model of a known ore body can help the explorationist focus on critical geologic attributes of the target area. Exploration models can conserve exploration funds that might otherwise be spent collecting data not critical to delineating an ore body. This article examines the benefits of using models, factors to be considered in developing models, and examples of the way recent models have evolved. New exploration concepts and techniques are developed in response to increased competition in the mining industry. New techniques can give an exploration group a slight edge that may translate into a discovery. Mine geology staffs may find previously unlooked for extensions to the ore body by applying new genetic concepts. When all appropriate techniques are applied to exploration and mining efforts, greater efficiency and increased profits may result. Before the 1950s, scientists speculated on the genesis of ore deposits and other natural phenomena. But they presented their results as if universal and final, even though they applied to only a few deposits. Because it did not provide sufficient criteria to distinguish the genetic processes, the classic conflict between hydrothermalists, epitomized by Lindgren, and nonhydrothermalists did not help the minerals explorationist much. Important information about individual ore deposits, such as age of the host rocks and mineralization, composition of the mineralizing fluids, and separation of mineralizing and nonmineralizing events in the paragenetic sequence, could not be gathered with past equipment and methods. But these early concepts of ore genesis contained excellent empirical observations, perhaps the most useful parts of these hypotheses. Through the years, prospectors have found most of the ore deposits in the world using direct observations and their collective empirical wisdom - an empirical model. The geologist's contribution becomes increasingly important after the more obvious surficial ore deposits have been discovered. In Europe and North America that time has arrived. With the introduction of sophisticated equipment and matching techniques in the 1950s in geochronology, geochemistry, geophysics, remote sensing, and computers, many previously equivocal genetic questions can be resolved. This proliferation of highly technical data has allowed the construction of many well-founded genetic models.

Jan 12, 1984

By Jasinder S. Jaspal

The United States has very large coal reserves in seams that are less than 1065 mm (42 in.) thick. These reserves are often not mined because of the difficulty of working in low heights and, in most cases, the seams are beyond the technical or economical limits. It is estimated that the remaining reserves in 355 to 710 mm (14 to 28 in.) thick seams that are not faulted or intruded, dip less than 15° and under a cover of 610 m (2000 ft) or less are nearly 910 Gt (1 trillion st). This is a very large percentage of coal reserves in the United States (Unrug, 1985; DuCarme et al., 1990). The US Bureau of Mines is attempting to develop new techniques for mining 150 to 1065 mm (6 to 42 in.) thick coal seams. Research has focused on existing thin seam mining techniques, testing of small- and full-scale physical models of the Bureau's slot mining concept and computer modeling of the full-scale process. In 1986, only 21 % of the total US coal production came from -1065 mm (-42 in.) thick seams. Of that, 355 to 710 mm (14 to 28 in.) thick seams share of production was minimal, probably 5% or less (Mayercheck et al., 1990). This shows that the thin seams, particularly the seams 355 to 710 mm (14 to 28 in.) thick, have not been mined to the extent of the available reserves. Thin seam coal, generally, is of premium quality. As thicker seams are depleted, the mining of thin seams could become more important. Thus, there is a need to develop technology to mine these seams (J. Farinelli et al., 1987). A successfully applied technology could change reserve categorization. In the Appalachian Plateau there are 417 Gt (460 billion st) in 355 to 1065 mm (14 to 42 in.) seams. This represents nearly 9.2% of the US remaining reserves (Unrug, 1985). At depths of 152 m (500 ft) or less, the Appalachian Plateau has about 214 Gt (236 billion st) of reserves in 355 to 1065 mm (14 to 42 in.) thick seams. Other mining areas also have substantial coal reserves in this seam thickness category. Those, however, are not as attractive for mining as the Appalachian Plateau. In the past, most of the reserves of the Appalachian Plateau region were partially worked by contour and highwall auger mining. It is estimated that these mining systems had left some 40,230 km (25,000 miles) (Readers Digest, 1987) of unreclaimed highwalls. The Bureau recognized this situation. In FY1987, the agency initiated a research project to develop anew technology for mining thin seams of the Appalachian Plateau.

Jan 1, 1992

By Russell L. Wood

Introduction It is the morning after and there is one monumental hangover among many, if not most, of the oil companies that invested in mining in the past decade. How an oil company looks at mining depends on the time period. A few years back, around the time of investment, they were probably looking at a balance sheet of their own that was beginning to go wild. Many of their commodity prices already increased two-, three-, or fourfold, with no end in sight. There was a need to invest their earnings someplace before the stockholders or the government got too interested. And that someplace needed to be an industry where their own management skills could be applied. In mining there was an industry amazingly similar to their own. Both worked with nonrenewable natural resources, dealt with the same types of government agencies, and had the same type of critics and pressures from the general population. Oil executives saw mining as an industry that was somewhat backward as compared with their own. They also saw how a generous ration of the capital and management skills, so handsomely bestowed upon the oil industry, could be used to great advantage. But, looking at mining through the eyes of an oil company today, this is what might be seen: • An industry that has been spectacularly unprofitable for the past few years; • An industry of many commodities, any of which can go bad on short notice for protracted periods, for a variety of unpredictable and uncontrollable reasons, or for no reason at all; • A labor-intensive industry, often beset by labor problems. And with only limited potential for further economic mechanization or automation in today's primitive mining environment; • An industry confronted with external, foreign, and political problems, with no reasonable expectation of near-term relief; and • An industry that does not appear to have many "up" periods in its immediate future. And, there is little chance for either big, fast bucks or long periods of large, steady earnings. What Went Wrong? The visions of a few years back seemed as correct then as today's viewpoints seem to be now. What happened to change these views? What went wrong? The simplest and easiest answer is that if the economy was normal back then, nothing would have gone wrong. This is an easy answer but, unfortunately, probably incorrect. Let us take a broad overview. Certain events enabled and prompted oil companies to invest heavily in mining. These same events were major factors in precipitating the worldwide recession that has grievously injured mining and has brought those mining investments into disrepute. Taking a somewhat narrower, but still broad overview, the simi-

Jan 3, 1985