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By Paul C. Miclea, Robert E. Murphy

The behavior of fire and airflows in a confined tunnel differ significantly from more familiar fire situations outside, due to the buoyant effect which tends to create a layer of hot smoke and gases flowing away from the fire near the crown of the tunnel, while air supporting combustion moves toward the fire beneath the smoke layer. A subway emergency ventilation system is designed to force air to flow through the tunnel, shifting the balance of heated air in the direction of the forced flow and avoiding the "back-layering" of hot gases and fumes. This paper presents a computer program, called the "Subway Environment Simulation" (SES), which can be used to predict airflows created by the emergency ventilation system. It utilizes the latest state-of-the-art analytical treatment of fires in enclosed spaces, including observations from mine fires and gas explosions. The program allows designers to reduce construction cost by identifying unnecessary ventilation shafts and by verifying fan capacities. In addition, the program allows the designers and operators to determine safe evacuation routes, in case of a train fire, by predicting the occurrence of back-layering. It can be used to determine when the ventilation system can control the direction of smoke movement to provide a clear and safe path for evacuating people and facilitate fire fighting operations.

Jan 1, 1989

By F. W. Mueller

It seems to be a matter of general understnading that title extraction or use of ground water may not be used as the basis of a depletion deduction under the United States Revenue Code And indeed, I have been unable to find any precedent upon which to base such a deduction. It is for this reason that the Shurbet case, which is the subject of my discussion and is now before the Court, may well become a precedent as authority for the allowance or disallowance of a depletion deduction for income purposes. It is well known that the law recognized that capital is consumed in the process of extracting minerals, oil and has, other natural deposits, and timber (underscoring supplied). This exhaustion, or depletion, is likened to the using up of raw materials in manufacturing. The law, therefore, provides a deduction for depletion which is intended as compensation for the exhaustion of assets consumed in the production of income through severance of minerals, oil and gas, other natural deposits, and timber.

Jan 1, 1962

By R. H. Grau

The National Institute for Occupational Safety and Health (NIOSH) has conducted research to improve the ventilation of large-opening mines. The research has demonstrated that the ventilation of large-opening mines improves significantly by including ventilation requirements in the mine planning process and implementing some practical techniques during mining. Planning the location of long pillars to reduce the number of crosscuts between intake airways and return airways, positioning auxiliary fans in their proper locations, and establishing ventilation stoppings with minimal leakage all significantly improve the ventilation of large-opening mines. Mine operators that adopt these techniques in the mine ventilation plan will reduce mineworkers? exposure to airborne contaminants.

Jan 1, 2008

By John E. Tilton

Mining is one of the oldest human activities. It goes back at least to the Bronze Age and possibly even the Stone Age. The Romans mined copper in Spain and tin in England some two thousand years ago. The writings of Agricola in the 16th century show that mining was important in the Middle Ages. Today we mine more mineral commodities in greater tonnages than ever before. This long and fascinating history closely tied with the economic development of the human race is one of the charms of the mining industry. It also, unfortunately, gives rise to some widespread misconceptions.

Jan 1, 1997

"The Industrial Comminution Efficiency (ICE) working group, part of the Global Mining Standards and Guidelines Group (GMSG) has engaged a large number of industry professionals representing mining companies, equipment vendors, consultants and metallurgical laboratories with interests and capabilities in the comminution field. These participants have collaborated to develop three guidelines for the assessment of the efficiency of mineral comminution circuits. Two of these guidelines deal specifically with power based modelling techniques to quantify energy efficiency using widely practiced techniques, those developed by Bond (1961), Rowland and McIvor (2009), and Morrell (2009). The third guideline deals with the sampling and surveying of grinding circuits as is required to provide the necessary information, at appropriate quality, to furnish the efficiency analysis promoted by the first two guidelines. This preprint will focus on the Guideline on Methods to Survey and Sample Grinding Circuits, which is currently in the final stages of peer review and finalization by the GMSG. INTRODUCTION It is important to make a clear distinction on the scope of work of the GMSG guideline for sampling grinding circuits. Many mineral processing practitioners are familiar with the sampling and surveying of comminution circuits, in particular grinding circuits, for performance diagnosis and the identification of optimization potential. These surveys often provide information for population balance modelling of individual comminution and classification unit processes, and as a result require a large amount of information to calibrate and validate the unit models. As a result these surveys are labour intensive, somewhat expensive depending on internal capabilities of the mine site or company, and have a long time span from initial planning to final reporting. They also require a high level of expertise to process the survey data, simulate the circuit and make sensible recommendations on follow up actions. As a result of these factors full grinding circuit surveys are not a common occurrence at a large number of facilities, and several years may pass before follow up surveys are conducted. In the ensuing gap between surveys, the efficiency of the grinding circuit must often be taken on faith, and this is considered an unacceptable lapse in an environment of strained natural resources and low commodity prices. To support the rapid and productive energy efficiency analysis being promoted by the ICE working group, a much simplified survey and analysis process is required. The process reflected in the GMSG guideline is indeed more conducive to frequent analysis, at a skill level that is well within the capabilities of the average plant metallurgist. As a result it becomes feasible to conduct mini-surveys of plant performance, which can be used to quickly and precisely diagnose the high level impact of process changes. It can also be manipulated by experienced practitioner to provide sufficient information for modelling of the circuit to estimate the impact of process changes, supporting an initial rate and rank exercise to focus plant optimization efforts."

Jan 1, 2016

By R. J. Sweigard

Three case studies were undertaken to investigate the role of land use potential evaluation in reclamation planning and to determine the impact of regional differences on the evaluation process. The three surface mines studied were representative of operations in the Appalachian, Interior, and Northern Great Plains provinces. The scope of the investigations included a survey of regional characteristics, a detailed investigation of the mining operations and site conditions, and an assessment of local land use planning activities in the area of the mine. Special attention was given to key factors that presently determine the use of reclaimed land. Also, for each case study, the postmining land use potential was evaluated using site planning principles. Specifically, the environmental, economic, and social impacts of several potential postmining land use plans were considered.

Jan 1, 1983

By David A. Milligan

This paper describes the Darwin Silver Recovery project, located 66 km (40 miles) outside of Lone Pine, near Darwin, Inyo County, California. A lead-zinc mine and a flotation concentrator were operated there from 1945 to 1957. By the time the mine was shut down, 1.53 Tg (1.69 million short tons) of tailings had been stored in ponds. An average silver assay of 47 mg/kg (1.38 troy oz/st) of tailings stimulated interest for commercial silver recovery. A heap leach process was developed in 1981 at the Tucson Research Center of Anaconda Minerals Company, a division of Atlantic Richfield Company. Agglomeration techniques were used on the ore since the fine grind did not allow direct heap leaching. Lime and cement were required as binders, Early laboratory tests showed that recoveries equal to those from an agitated leach could be achieved at lower capital and operating costs. Laboratory tests determined cyanide requirements, lime and cement usages, and percolation or leach rates, as well as confirming that a zinc precipitation step could recover the silver from the leach solution.

Jan 1, 1983

By F. F. Peng, S. S. Peng, V. Z. Sun

A detailed study of ponding phenomenon relative to surface subsidence due to longwall mining was conducted for various surface stream conditions. Based on field monitoring, the stream-ponding process and three forms of stream water are described. Also discussed are the criteria of stream ponding and the influences on the ponding process by two key factors: the angle of stream flow and the change in the stream-bed gradient. A numerical (mathematical) model, which combines trend surface technique that describe the topographical features in the vicinity of a stream and the modified influence function, which represents the profile of the surface subsidence trough (or basin), is constructed to predict the formation characteristics of stream ponding in terms of location, boundary and accumulated water volume of migratory and stationary ponds produced by the stream-ponding process. Three cases are analyzed using the model to predict the interaction of the underground operations and the environmental impact due to stream ponding. The feasibility of various mitigative measures are assessed.

Jan 1, 1997

By C. B. Rash, W. W. Fowler, Gill Montgomery

INTRODUCTION Fluorspar is the common term used for the mineral fluorite, which is naturally occurring calcium fluoride (CaF2). It is the principal source of fluorine, the most reactive of the chemical elements, from which a great variety of unique and strategically important chemicals are produced. Commercial deposits of fluorspar are widespread throughout the world, and its availability is essential to the industrial progress of all nations. GEOLOGY AND MINERALOGY In its pure form fluorspar, CaF2, contains 51.1% calcium and 48.9% fluorine, and has a sp gr of 3.18 and a hardness of 4. It is commonly a glassy mineral. colorless, white, or grayish. but may also be various shades of purple, pink, blue, green, yellow, or tan. It belongs to the cubic system mineralogically, and commonly crystallizes into cubic shapes in vugs and cavities, although most of it is massive, with interlocking crystals. Minable fluorspar deposits, in descending order of importance, occur as bedded limestone replacement deposits along fault zones; fissure-filling vein deposits; breccia filling in limestones, dolomites,

Jan 1, 1985

By K. N. Han, P. B. Queneau, A. Stojsic, M. J. Collins, V. J. Ketcham, R. M. G. S. Berezowsky, W. D. Vardill

The bulk of the ore found in the Lihir Island deposit is refractory in nature, with the gold contained in auriferous pyrite. In support of an evaluation of the development of this deposit by Kennecott (a wholly owned subsidiary of RTZ) and Niugini Mining Ltd., testwork has been carried out at the Sherritt Research Centre to demonstrate the amenability of the Lihir ore to pressure oxidation pretreatment to liberate the refractory gold. The results of pilot plant treatment of the Lihir ore in a continuous circuit with a feed rate of between 10 and 30 kg/h ore are described. The integrated circuit comprised pressure oxidation, residue washing, and gold recovery from the washed residue by carbon in leach or carbon in pulp cyanide leaching. Significant factors affecting gold recovery included temperature and retention time in the pressure oxidation step, and the concentration of soluble chloride in the feed. Gold extraction from well washed ore, after oxidation at 210°C for 66 minutes in the autoclave, was typically between 94 and 96%, compared with less than 30% by direct cyanidation.

Jan 1, 1993

By Lester G. Rollins

Coal today enjoys a dominant position, serving the energy and metallurgical marketed The measure of success in the market place is, and will continue to be, the price per million BTUs or price per ton delivered to the user. The Coal Industry's remarkable record of price stability since World War II is well known. The next twenty years promise to be equally as challenging. This challenge will be met our president, Mr. Drain, has often stated that, ?The Joy Manufacturing Company is betting that coal will meet the challenge.? To this end, the resources of Joy have been committed to doing its part. Joy's efforts are directed toward a target which has been defined as: 1. Deliver coal to the user at a price of $.15/MBTU or less. or; 2. Deliver coal to the mine portal at a cost of $1.00 or less.

Jan 1, 1966

By B. Cavender

Mining managers trying to rapidly reduce production costs tend to implement a traditional set of topdown managerial practices: reductions in production volume, employee layoffs, renegotiation of supplier contracts, cancellation of employee training, restrictions on travel, reductions in office supplies, and so forth. While these practices do reduce costs, the benefits are often limited in both magnitude and duration, and the workforce is usually left demoralized. Successful cost-cutters take a different approach. They make the continuous reduction of costs a priority for all members of the organization, whether managers or workers. The culture of these firms emphasizes the commitment, voluntarily given, of individuals and work groups to this goal. Cost-cutting practices often reject all of the traditional methods mentioned above, but are far more numerous, innovative and successful. This culture of cost reduction is the result of a set of leadership competencies that establish direction for the organization, align the organization's various constituencies with this direction, and motivate and inspire the organization. Cost reduction then becomes a routine task rather than a heroic achievement.

Jan 1, 2002

By Reinhard Gertl, Maximilian Weithaler, Harald Kammerer, Juan Pablo Muñoz, Juan-Carlos Rueda

The Guillermo Gaviria Echeverri tunnel and its access roads project in Antioquia, Colombia is a mega infrastructure project that includes a road network with the longest tunnel in Latin America and several short tunnels, the latter being the focus of this study. The design of the project required careful consideration of several special factors, such as the tunnels’ steep slopes of up to 5%, high fire load of 100 MW, bidirectional operation, and short lengths that make it difficult to place ventilation equipment. The combination of all these parameters cause a challenging design problem for the ventilation systems and smoke control of the short tunnels. To address this challenge, a risk assessment study was conducted to support the design of a new and innovative ventilation strategy that deviates from relevant guidelines and standards, like the Austrian RVS [1][5][6] or the German EABT [8] in order to provide a customized solution for this particular project. This strategy resulted a cost-effective solution, that allowed a reduction in the number of required jet fans and at the same time reaches or reduces the risk level compared to traditional ventilation strategies.

Jun 13, 2023

By Clément F. Bernier

One of the chief sources of the world's supply of asbestos lies in a belt of ultrabasic rocks which runs northeastward through an area called the Eastern Townships, south of the St. Lawrence River in the Province of Québec. The productive portion of this belt extends from the town of Asbestos in the south, for a distance of some 9,5 km to beyond the village of East-Broughton. The first discovery of asbestos in this region was made in 1874. Only crude fibre was produced until 1888 when the first mill was erected near the town of Black Lake. Since the inception of the industry, almost 100 years ago, no less than 100 different compa¬nies have been formed and 46 different mines have been operated. There are presently 5 active companies in the area providing direct employment for 4100 workers, down from 6000 during the seventies.

Jan 1, 1984

The estimation of local recoveries, such as the local recovered tonnage of ore and its corresponding grade at a given cutoff grade, is an important problem in a selective mining operation. Multigaussian kriging provides a simple solution to this specific problem. The solution is also complete in the sense that local recoveries are estimated together with their estimation variances. It is thus possible to assess confidence limit intervals on the estimated recoveries. Multigaussian kriging has been applied to the Jerritt Canyon deposit in a most realistic situation. The various steps of the estimation procedure are presented in detail and the potential of the method is demonstrated in view of the results. The obtained results show that the estimated recoveries are in good agreement with the actual recoveries and the actual estimation errors are correctly predicted by the estimation variances. Multigaussian kriging thus appears as a useful and fully operationable tool for the mining industry.

Jan 1, 1986

"Tell us how you got involved in mining and about your career path.My dad was a coal miner and my uncle was a metallurgist, so when I enrolled at Penn State’s New Kensington Campus, I chose the College of Earth and Mineral Sciences — exact majors didn’t get picked till the end of your sophomore year. Penn State New Ken had an associate degree in mining program and one of the guys in my carpool was going to take Mining 30 in the evening and the other guy (mechanical engineer) was also able to take an evening class. I didn’t want to break up the carpool, so I took Mining 30, complete with essay tests. I could write, so I did well, and the professor said I should go into mining engineering. Fast forward to the end of the next term at University Park, and I realized there wasn’t enough chemistry in mining. Switching to metallurgy would have meant another term at that point, so Dr. Lovell, my advisor, trotted me down the hall and to the next building and said I was a mineral processor. That stuck. I was a summer student at U.S. Steel Research between my junior and senior year and they paid for my master’s degree — all about clay and macerals in coal flotation. During that time, the steel industry tanked, and I thought a Ph.D. would be a good idea — I could always teach at the university level if I had those credentials. The Electric Power Research Institute had a Coal Cleaning Test Facility in Homer City, PA, and I conducted my Ph.D. research on rate and residence time in conventional coal froth flotation cells there and at a local cleaning plant. I went to work at the test facility in 1987 (later CQ Inc.) and stayed there until I started PrepTech Inc. in 1997. PrepTech offers some consulting services for coal cleaning plants and sells mineral processing equipment, mostly to coal companies. I can’t believe it’s been 21 years.And what about your SME career?Of course, I was a student SME member at Penn State. We used many of the SME books in class, so who wouldn’t want the student discount? While in Homer City, I became involved with the Appalachian Plateau Subsection of the Pittsburgh Section. We’d hold quarterly meetings with interesting speakers and had good attendance. I was the secretary. I’m still the secretary and also get the bank statements. We’ll need to close that out some time, but I guess I’ve been hoping for resurgence in the Indiana/Cambria/ Somerset area."

Jan 3, 2018

By Steven Atkin, Rens Verburg, Bryony Hansen, David McWharter

The use of paste tailings as underground backfill and for surface disposal is rapidly expanding, and with it comes the requirement to understand and predict its long-term environmental stability. This paper presents the results from a kinetic testing study performed on cemented tailings paste mixtures under both subaqueous and subaerial conditions. In addition, the effects of grainsize reduction are investigated. It will be demonstrated that the long-term weathering behavior of tailings paste is controlled by its physical and chemical characteristics, as well as its placement conditions. The testing indicates that subaqueous disposal of paste inhibits acid generation, whereas the exposed samples produced acidic leachate despite the presence of cement added to meet geotechnical requirements.

Jan 1, 2000

By D. C. Yang

A packed column jig has been developed for sharp separation of fine particles--150 down to 1 micron--having different densities. The packed jig is a column filled with corrugated packing. A slurry of mixed particles is fed into the middle of the column. Water enters near the bottom of the column as both a steady state and a pulsating flow. The pulsating water sets up a jigging action that interacts with the packing causing the dense particles to sink and exit the bottom of the jig and the lighter particles to rise and exit the top of the packed jig. The result is a sharp, environmentally friendly, gravity separation machine with low operating costs. Grades and recoveries of iron ore exceed that of known devices. Grades as high as 95 percent purity with concomitantly high recoveries are common for iron ore concentration. Low silica, sulfur and phosphate are common. This paper is the first to unveil the packed column jig technology in detail and presents its physical model with performance data. The purification of iron ores and coal is the paper's focus.

Jan 1, 1997

By Bernard L. Cohen

INTRODUCTION The most serious occupational radiation episode in U.S. history was the exposure of uranium miners to radon daughters in the 1945-1968 time period. Although the maximum permissible dose at that time was 12 WLM (working level months) per year, average exposures were several times that figure, and ten times higher exposures were not uncommon. Starting in the early 1960s, mounting epidemiological evidence appeared for an excess incidence of lung cancer among these miners; up to 1974, there was an excess of 134 cases (159 observed vs 25 expected) among the 4000 in the group under study (NAS-1980). When this excess became apparent, the Federal Government took jurisdiction, greatly tightened enforcement, and in 1969 lowered the maximum permissible exposure to 4 WLM per year. These standards were met largely by a great improvement in ventilation. As a result of these measures, average miner exposures were reduced 5-fold from 1965 to 1968 and by another factor of 3 by 1970. In 1978, the 4 WLM/year maximum permissible exposure was exceeded by only 37 of 7500 underground miners, for only 16 wars it exceeded by more than 25%, and for only 8 was it exceeded by 502 (AIF-1980). The average exposures to the various groups are listed in Table 1. We see that the average exposure for all miners was 1.03 WLM, and for those who worked essentially full time underground it was 1.45 WLM. For purpose of later discussion, it will be convenient to choose a single value for average exposures. In view of the fact that employment situations and job categories are bound to vary over a lifetime of work, we take this to be 1.3 WLM/year. The purpose of this paper is not to dwell on history, but rather to address the question of whether or not this present situation is satisfactory. This question was considered recently by a study group under the auspices of National Institue of Occupational Safety and Health (NIOSH-1980) and it answered the question in the negative, concluding that the maximum permissible exposure should be substantially reduced. However, their arguments were incomplete and were lacking in perspective. The principal thrust of this paper is to provide some of the material overlooked. RISK TO URANIUM MINERS FROM RADON EXPOSURE In order to quantify the risk to uranium miners under present working conditions, it is first necessary to estimate the risk of lung cancer per WLM of exposure. The most straightforward way of doing this is to use the data on the group of uranium miners under study. These are listed in Table 2 for 8 exposure ranges and for the total group (NAS-1980). If all data are given equal weight, the risk is seen to be 3.5 x 10-6 per year per WLM. Much can be said in favor of using this value for the risk as dose independent; it is within one standard deviation (SD) of the observations in 5 of the 8 dose categories (as expected from the definition of SD), and within 2 SD for all 8, and for the three cases differing from the mean by more than one SD, two are above and one is below. However, the uranium miner exposures in the present situation will be far below those covered in Table 2, so it is worth considering the possibility that the risk differs from this at low doses. From the last column of Table 2 we see that the experience from all exposures below 600 WLM indicates a risk higher than the mean for the entire group by more than two standard deviations (the value 600 WLM in this comparison was deliberately chosen to maximize this deviation; for exposures below 360 WLM and 840 WLM, the excess is only 1.0 and 1.6 standard deviations respectively). In view of this tendency for the risk to be higher at lower dose, we will take the risk to be 5.0 x 10-6 per year per WLM in what we will refer to as model A. This risk estimate is based entirely on exposures much [higher] than those that will be experienced by

Jan 1, 1981

By G. Kritikakis

Rehabilitation of sites contaminated by oil products and chlorinated organic compounds is a costly task which affects the planning of urban and infrastructure development. An integrated approach based on the non-invasive geophysical technology is utilized for subsurface characterization of contaminated land. In this approach the localized information, provided by chemical analysis of soil samples collected from bore-holes, is used for the calibration of the geophysical data. This information is subsequently extrapolated to the area under investigation by combining it with the geophysical results, providing thus information about pollution accumulation, contaminants? flow and pollution sources. Two case studies are presented from sites contaminated by heavy metals (Venice, Italy) and oil products (Athens, Greece). Resistivity, electromagnetic and seismic methods were used in this approach. Namely, electrical tomography, electromagnetic mapping, ground penetrating radar (GPR), multichannel analysis of surface waves (MASW) and seismic refraction experiments were conducted. In Italy, the sections from the multichannel analysis of surface waves imaged successfully a buried channel where the pollution is concentrated. Preliminary results are also discussed from the geophysical survey in Greece where the thickness of the oil phase located on top of the water layer is 60 cm.

Jan 1, 2006