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THE PENNSYLVANIA STATE UNIVERSITY, 101 MINERAL SCIENCES BUILDING UNIVERSITY PARK. PENNSYLVANIA 16803 To the Editor: With respect to the Fenvessy and Schwab article, I offer the following: As thorough as the study may be, it still has a glaring weakness. The presumption of constant supply in face of falling demand - their "low growth" case - is just wrong. It does not allow for the rapid migration, by transfer and change of major, from former high-demand programs, such as mining, to programs that have more recently obtained the cachet of job security. The figures that are shown for rapid growth in mining engineering enrollments in the period 1970-1981 are, no doubt, correct and reflect a rapid inmigration of students into mining. A similar out-migration, which began in 1982, from mining to other engineering and science disciplines is not factored into their study. Given 1983-84 enrollments, which can already be documented, it is clear that the low-growth case will, by 1985, be 50% or less of 1981. I wish students would pick their majors on the basis of their own individual abilities and interests rather than rushing lemming-like to programs that are reputed to have jobs. In the end, students will have better jobs and careers if their college majors match their talents and we, in the academic side of things, will have a livelier and more dedicated student. Lee W. Saperstein Professor and Chairman of Mining Engineering UNIVERSITY OF MISSOURI-ROLLA To the Editor: I write concerning the recent article on future demand for graduates in the mining industry. The article is, unfortunately, inaccurate because of the erroneous assumptions it makes in its basic premises. To cite but two of these, class sizes will not continue at their current level, but will, in fact, alter dramatically as a function of the perceived immediate job market rather than the future trend, so that enrollments are already below those predicted. Secondly, it is patently wrong to assume that everyone who gets a degree in the mining field will continue until retirement to work in that field. People who do not have a job in the industry will get work elsewhere and often do not come back. Others will later move to different areas. My major argument, however, deals with the underlying assumptions and methodology of the survey itself, with the concomitant challenge to the subsequent conclusions. It is no great secret that the technological world is undergoing a dramatic revolution. Computer use is rapidly spreading to the point where the microcomputer will be an integral part of every mine engineer's desk. Such a tool, which for optimal benefit must be operated by knowledgeable mining engineers, will make mining much more of a science than the current level. To remain competitive, mines will increasingly rely on higher level deci-

Jan 1, 1984

By Gerrit V. R. Goodman, Fred N. Kissell

The Bureau of Mines has evaluated the effectiveness of the safety elements used to prevent tunnel methane explosions. These fa1l under the general categories of better ventilation, better gas monitoring, reducing ignition sources, and improved worker training. For this evaluation, a technique called fault-tree analysis was used to analyze questionnaire responses from 27 tunneling experts. This analysis allowed us to rank the effectiveness of each safety element, and indicates where money is best spent to reduce the chance of a methane explosion. Results indicated that large decreases in the explosion hazard only take place with the simultaneous application of several elements. Most of these involve a human component - the everyday vigilance and awareness of those working underground.

Jan 1, 1991

By Jung-Hum Lee, Young-Joon Lee, Eui-Joon Hong, Seon-Hong Kim, Chan-Dong Kim, Keon-Woong Jeong, Ki-Lim Kim

"Subsea tunnel needs to be built over 50km long to connect between nations and continents. However there are only 19 tunnels longer than 5km in Korea, and there is no history of constructing and operating a tunnel longer than 50km. As the concept of a subsea tunnel, which withstands high water pressure and has an extremely long length is completely different from that of a land tunnel, all kinds of the latest technologies for tunnel construction are required such as survey and analysis of geology, design and construction under high water pressure, ventilation and prevention of disasters within an ultra long tunnel. Therefore, this paper describes the determination of tunnel cross-section under a high speed railway, structural stability, ventilation and fire safety under construction and operation, etc. through the virtual project for the length of 108km subsea tunnel under high water pressure of maximum 20bars from Honam to Jeju island in Korea. 1. INTRODUCTION The Honam-Jeju virtual project is subsea tunnel project to link from Honam(land) to Jeju(island) extending the currently operating Honam high speed railway line, and the same express train(t=18, design speed 350km/h, total train length 200m) operating at Honam line is applied in this project. As Honam-Jeju site is approximately 80km in straight distance with 160m maximum depth, subsea tunnel project should determine the various issues such as air quality/ventilation, aerodynamics, temperature, drainage, fire & life safety, structural stability. Figure 1. is the plan of subsea tunnel, with be constructed using Shield TBM. This double tube-Single track is composed of cross passages (every 350m in general section and 40m in emergency station), service tunnel, pressure relief ducts (every 250m), cross-over tunnels, shafts and emergency stations. 2. ALIGNMENT AND SITE CONDITON This project is planned as an ultra long tunnel of total length more than 105km via existing islands between Honam and Jeju island because straight alignment requires an artificial island which has high cost and construction risk, by deep water depth, though this is the shortest distance (see Fig 2). Water depth and topography in project site is divided into two blocks by Chuja Island. In first block to Chuja Island, depth of the water is 40m on average and maximum 60m, which indicates gradual change of water depth relatively. Also, outcrop bedrock is widely distributed near island."

Jan 1, 2016

By A. W. Mitchell

Mining of a bedded barite deposit exposed highly pyritic siliceous sediments which have weathered and degraded subsurface and surface waters. The ph, sulfate, and total dissolved solids are the most seriously affected parameters. Several solutions were tried and eventually horizontal holes were drilled into the mine wall to draw down the water table and decrease the movement of groundwater through oxidizing zones opened up by the mining operation. Areas of surface disturbance were capped with layers of soil, bentonite, and gravel to decrease the infiltration of water into the disturbed areas. These actions have begun to decrease sulfate and total dissolved solids concentrations and increase ph values.

Jan 1, 1987

By B. Schimm

Mining of material without blasting and / or selectively becomes more and more important for high quality ROM-products. Surface Miners have been developed especially for this purpose. The cutting technology of these machines has been improved, so that harder material as well as wet and sticky materials can be cut with better results now. Especially the cutting drum design and more precise drum manufacturing process now allow production and equal tool wear over a long period. The better knowledge of rock parameters influencing the cuttability and cutting results allow higher production, less cutting tool wear and therefore reduced production costs.

Jan 1, 1999

By M. Nichols

Where am I? Where are they? Where is it? These are the fundamental questions that need to be answered in managing people and resources. This paper explains how GPS positioning technologies answer those fundamental questions and provide better information management from initial exploration work through daily mine operations to reclamation work and environmental monitoring.

Jan 1, 1998

By Lane White

The nature of the new Mining Law in Mexico, how it works and its implications for foreign investors were discussed from a variety of points of view by speakers participating in SME's special programming on Mining in Mexico at its An¬nual Meeting in Albuquerque, NM Feb. 14-17, 1994. Following are summaries of three papers whose primary objective was to give foreign investors some insight into the nature of doing business under the current Mexican Mining Law and its regulations. Lane White, Publisher.

Jan 1, 1994

By John E. Tilton

Looking back on the second half of the 20th century, future historians, I believe, will be fascinated by two major political upheavals. The first is the environmental revolution in the 1960s. It erupted in the United States and parts of Western Europe and then swept across the rest of the globe like a wild fire. The second event is the collapse of the Soviet Union. It was the last of the world's great imperial empires. With its demise went central planning as a viable economic system. History, I suspect, will see this second revolution as an offspring of the first. This is because economic and environmental issues were largely responsible for the unraveling of the Soviet Union.

Jan 1, 1994

The first of this two part series takes a look at some of the history and types of flotation as well as agents and mechanisms involved in it. Part two, next month, will examine flotation processes as applied to various sulfide and nonsulfide mineral ores. Flotation-"froth" flotation-is a physicochemical method of concentrating finely ground ores. The process involves chemical treatment of an ore pulp to create conditions favorable for the attachment of predetermined mineral particles to air bubbles. The air bubbles carry the selected minerals to the surface of the pulp, there forming a stabilized froth that is skimmed off and from which the predetermined mineral particles are recovered. Other minerals remain submerged in the pulp.

Jan 3, 1982

By Jay A. Bowden

In April of 1990, Homestake Mining Company began a 5,100 m (16,700 ft.) exploration drift from the Homestake Mine in Lead, South Dakota. The drift starts from the mine's 6800 level, nearly 2,100 m below the surface, and extends north to further explore occurrences of gold discovered by surface drilling. Access to the North Drift for men and materials and for disposal of waste rock is limited to the Homestake Mine's #6 Winze, which serves as the major production shaft for the deep levels of the mine. This paper will discuss the successes and challenges encountered while managing a tunneling project 2,100 m below the surface and from an active mine.

Jan 1, 1993

By Fernando Concha, Arturo Barrientos, María Cristina Bustos

Manufacturers referred to high capacity thickening as a filtration operation rather than thickening in spite of the fact that it is performed in thickeners and that conventional thickeners can be operated as high capacity thickeners by changing the feeding level and operate it in a different manner. In this work we derive a phenomenological model for high capacity thickening based on mass and momentum balances. The difference with a conventional thickening is the presence of a surface source within the variable domain. The model can be used to design, simulate and to develop control strategies.

Jan 1, 1995

By R. Pakalnis

A comprehensive project has been completed at the University of British Columbia that focused on the development of a commercially competitive composite cable bolt. Laboratory evaluation consisted of pull tests, preliminary shear tests, grout column testing and scanning electron microscope evaluation of the composite cable bolt. Field implementation at five underground mines throughout Canada were completed for technical and overall performance evaluation of the new product. The project began in 1989 under the sponsorship of HDRK Ltd., a consortium of mining companies including Inco, Noranda and Falconbridge Ltd. The objective was to develop a cuttable cable bolt that would serve as support for a continuous miner within a hardrock environment (Mah, 1994). The bolt was required to be cuttable by a continuous roadheader without adverse effects to equipment, personnel and the milling process. From the beginning, the focus was to employ existing cable bolt installation technology (Goris et al., 1994) whereby the cable bolts are grouted within a 4.8-cm-diam (1.08-in.diam) or larger employing a portland cement grout having a water:cement ratio between 0.35:1 to 0.4:1.

Jan 1, 1994

By Steve Kral

The success of the industrial minerals end of the mining industry is often overshadowed by the high price of copper, the glamour of gold, and the nation's huge reserves of coal. Those three segments of the industry, however, along with every other business in the world, could not function without the products that are composed of a variety of industrial minerals. And, according to Haydn H. Murray, past president of SME, the value of industrial minerals in the United States is more than triple that of metals, about $19 billion a year versus $6 billion. In the developed countries of the world, he said, the value of industrial minerals is nearly always greater than the value of metallic minerals. Murray, also a professor of geology at Indiana University, was the luncheon speaker at the SME-sponsored Grinding of Industrial Minerals conference held in Asheville, NC this past September. Producers of industrial minerals know they must squeeze the maximum value out of the industrial mineral being mined and processed, Murray told the audience of about 100 people. Grinding and particle size, then, are vital to a commodity's profitability.

Jan 1, 1990

By John Wiebmer

Several industry trends are putting new demands on surface mining equipment. This is true both on the “hard” side of the equipment business - the research and product development programs, and on the “soft” side - the business processes, human resources and competitive strategies. This article describes seven key industry trends and the impact each is having on surface mining equipment suppliers. 1. Globalization Earth-spanning technologies are shrinking the world into an economic village, causing corporations to think and plan on a global scale. This “globalization” is one of the great buzzwords of the 1990s, meaning precisely whatever the user says it means. In this case, let us take it to mean that political boundaries arc less restrictive than in the past, permitting mining companies new freedom to roam the globe for ore bodies. Evolving out of this are global mining houses that have ownership and management interests in labyrinthian webs of mines spanning the world. There are several impacts on surface mining equipment suppliers.

Jan 1, 1994

By Silvano Perla

Peabody Western Coal Co. operates two mines in northern Arizona. The Black Mesa and Kayenta coal mines are unique for several reasons. They both have only two customers: Southern California Edison’s Mohave generating station near Laughlin, NV and the Navajo generating station near Page, AZ. Both mines are close together. Between the two, they ship nearly 11 Mt/a (12 million stpy) of coal. Material is shipped to the power stations in two ways. This first is a 440- km-long (273-mile-long) underground slurry pipeline, the longest in the world. The second is an 11 -km-long (17-mile- long) long conveyor to four storage silos. Product is then shipped by train from the storage silos to the plant sites. Another factor makes these mines unusual. They are both situated in the middle of the 68,795km2 (17 million- acre) Navajo Reservation, home to the Navajo Nation and Hopi Tribe members. Nearly 90% of the Black Mesa and Kayentamines’ 850 employees are tribe members. Peabody Western Coal is the United States’ largest private employer of Native Americans.

Jan 1, 1995

By L. R. Freitas, A. K. Resende, J. A. Oliveria, K. L. Gonçalves, L. F. D’Assumpção, L. R. Lage, J. D. Neto, F. Viveiros

Pará Pigmentos S.A. (PPSA) is an association between the Brazilian companies CVRD and CADAM, Mitsubishi Corporation of Japan, and the IFC (World Bank) created in 1992 in order to recover kaolin from Rio Capim deposit, northern Brazil. Commercial production at PPSA started in August 1996 using a process comprising mining and beneficiation at the mine site, pumping through a pipeline and drying/loading at the port site on the Amazon river estuary. Presently, all PPSA production is concentrated on 82% <2um, high-brightness coating clay shipped in bulk. In this paper, a detailed description of the development of PPSA beneficiation process is presented. The results of laboratory and pilot plant studies under- taken to develop alternative grades of clay, such as delaminated and calcined kaolins, are also discussed.

Jan 1, 1998

The tungsten carbide insert bit has probably advanced blasthole drilling more than any other single improvement. Tungsten carbide inserts have longer life, maintain sharper edges, and penetrate faster than hardened steel edge bits. Before the tungsten carbide hit appeared, all-steel bits were used. Even with the new bits, blasthole drilling costs vary with the type of equipment used and its condition; the hole&apos;s length and diameter; the rock&apos;s texture, hardness, and nature; the operator efficiency. To help reduce drilling costs, the operator should be familiar with the use and care of drill bits. This article provides information about tungsten carbide rock bits used for percussion drilling. Consideration of tungsten carbide rock bits includes looking at bit materials [ ] as well as bit operation and maintenance. Two basic tungsten carbide rock hits are the button bit and the four-wing carbide insert bit. Three common hit-to-drill-steel connections are the bottom drive, tapered drive, and shoulder drive. Bottom drive bits arc typically used for singlepass or longhole drilling, with all percussion drills from handheld sinkers to heavy track drills. Tapered socket bits are available with shallow or deep carhide inserts, for the lowest cost depending on the rock type being drilled. Shoulder drive bits are available in all-steel or carbide insert design.

Jan 12, 1981

By Robert S. Mayo

The haulage of muck from mines was first illustrated by Georg Agricola in De Re Metallica in the year 1556. In many of his ancient wood cuts he showed a crude car running on wooden rails. These wheels had no flanges. There were four pins sticking down from the car to guide it along the rails. Eventually they made the wheels of cast iron with flanges on them. In England, coal was hauled from the pit mouth to the nearest river or canal in "wains", or wagons, running on the common highways. These wains carried one chaldron of coal, weighing 2500 lbs and it took six horses to haul these wains over the atrocious roads of that day. Somebody, about 1760, invented a cast iron rail. These were cast iron troughs, 4 ft long laid on wooden sleepers. With these iron rails they found that one horse could do the work of six. But this U-shaped groove trapped all the dirt and grit. Somebody had the brilliant idea of attaching a flange to the inside of the wheel and from then on the rails were of timber protected against wear by a strap of iron. Rolled rails, of wrought iron, were first used in England in 1820. I am sure that many of you people have wondered why the British and American railroads standardized

Jan 1, 1974

By Heflin. L.

The Washington Metropolitan Area Transit Authority, WMATA, has constructed over 92 revenue miles of rapid transit facilities including some 14 miles of rock tunnel and 12 miles of earth tunnel. The system map is shown in Figure 1. During construction it is not unusual for contractor to encounter ground conditions resulting in major problems and extra cost. Problems such as major rockfalls and a "stuck" boring machine in squeezing rock are not unusual. In recent years, faced with additional tunnel construction projects, the Authority has sought newer tunneling methods which might be less costly. One new method which has been tried is NATM, the New Austrian Tunnel¬ing Method. NATM, which is applicable to both soft ground, mixed face and rock tunneling, relies on miners and comparatively small machines to excavate in conventional ways, but it is unique in its methods of obtaining "stand-up" time at the excavated face and its method of using shotcrete as an initial lining, frequently with a drainage system to reduce hydro-static pressure on the final lining. Lower costs result from use of a cast-in-place concrete liner, and from a reduction in the number of work operations at the mine heading which provides better daily production. WMATA has recently completed three twin bore tunnels constructed by NATM technology. The first was the Wheaton Tunnel and Section, followed by the tail track tunnel to total some 4200 linear feet cut through jointed rock up to 270 feet below ground surface, and the last was in soft ground at Fort Totten. A

Jan 1, 1993

By Edwin J. Connell, O&apos

Investment in mining and related process facilities will be more costly and complex in the 1980s than ever before. Interest rates and inflation are soaring; regulations are expanding; and in order to achieve economies of scale, plant facilities and mines are getting larger. As the pace quickens, the time/cost circuit closes around the resource owner or developer. Larger modern projects cost more money and take more time to build. The longer it takes to bring a project onstream, the more it costs in interest, escalation, and lost production. One solution to the time/cost squeeze is to take advantage of systems developed by major contractors serving the mining industry. These contractors have been serving clients in planning and executing large and small projects for many years. They have developed systems which, if applied at an early point in the project&apos;s life, can be a significant benefit in development of mineral resources. The systems involve performance of feasibility studies, economic evaluations, and the project installation itself. First the Feasibility Study Feasibility studies can minimize risk through systematic evaluations while progressing toward the ultimate objective-an operating plant. Normally, studies are initiated with a minimum amount of specific information and a maximum number of as¬sumptions. Through the course of the study program, assumptions are continuously confirmed, refined, or rejected by facts until a sound basis for decision is available. High on the list of cost effective tools for evaluation is the use of a geostatistically derived sampling program that provides a highly accurate ore reserve estimate for economic evaluation. When a predetermined sample of data from the drilling program and bench-scale or pilot-plant tests are received, a detailed feasibility study may be started. This study can involve design of the mine,

Jan 10, 1980