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By S. Cotten

The regulations for current coal mine refuge alternative (RAs) require that there be sufficient life support to sustain survival of the maximum number of RA occupants for a minimum of 96 hours. This minimum duration assumes that rescuers can access the RA through the mine within four (4) days of the onset of the mine emergency. But what if mine rescue teams cannot reach the miners within the RA before the RA air supply is severely limited or exhausted? What could be done to extend the duration of the RA life support capability into the 97th hour and beyond? In addition, what might be done to enable more rapid rescue of the miners if they could not be reached through the mine in a timely manner? This paper describes a systems approach to address the potential need to extend the duration of RA life support beyond current design limits. New capabilities that need to be developed in advance of such a dire need include more reliable emergency communications, highly mobile and efficient drilling rigs, enhanced directional drilling techniques, and a standardized RA external life support interface along with RA internal design modifications to accommodate use of an external supply. The following sections describe the need, intent, and technology gaps associated with each of these capabilities. Government agencies and the mining industry should consider initiation of a program to investigate, design, and develop effective means of extending the current 96-hour time restriction on coal mine refuge alternative life support. The development process should begin with a focused study to refine the overall operational concept, investigate the current state-of-the art of critical technologies, identify specific technology development priorities, and make recommendations for a development program to provide in an organized, efficient, and timely manner a solution for extended refuge alternative life support and occupant rescue.

Jan 1, 2011

By Patrick J. Doig

In mid-1991, the design/build contractor set to work on the Pergau HEP in a remote corner of Malaysia, armed with only a slim volume of conceptual drawings. The next five years saw roads, power lines, buildings, dams, and over 30 kilometers of tunnel constructed, followed by two years of E&M installation and commissioning. Along the way, the project overcame geothermal groundwater, faults, land disputes, monsoon rains, marauding tigers, and those most fearsome of foes, politicians and the press. This paper is a testament to the ingenuity, commitment, and persistence of the construction industry professionals who brought this massive project to fruition.

Jan 1, 2001

By Luzheng Chen

Pulsating high-gradient magnetic separation (PHGMS) of fine hematite from tailings was studied using a pilot PHGMS separator to investigate the possibility of its application in industry. The results of this investigation indicate that PHGMS is effective for recovering fine hematite from the tailings and greatly improved the separation performance compared with the conventional high-gradient magnetic separation at the same conditions. By applying the pilot separator with a 1-mm rod matrix to a tailings containing 28.76% Fe, a concentrate assaying 54.35% Fe with 35.89% recovery was achieved. It was found that the separation performance of the pilot separator closely correlates with the main pulsating parameters, i.e., pulsating stroke and frequency. It was also found that a change in the wire diameter of the rod matrix from 2 to 1 mm causes a weak drop in concentrate grade but results in a considerable rise in recovery. This finding proves that the improved performance achieved by the pilot separator is attributed to the pulsating of slurry and to the use of a 1-mm rod matrix. When the first commercial SLon-2500 PHGMS separator with a 1-mm rod matrix was applied to recover fine hematite from the tailings, the results duplicated those achieved with the pilot PHGMS separator.

Jan 1, 2009

By J. O. Marsden

Over the past eight years, Phelps Dodge (a subsidiary of Freeport-McMoRan Copper & Gold, Inc.) devoted a significant amount of effort to the development of a suite of processes for the effective hydrometallurgical treatment of copper sulfide concentrates. This effort resulted in the development of high-temperature (>200ºC) and medium-temperature (150° to 165ºC) pressure leaching processes. Specific configurations of both processes have been commercially demonstrated at Phelps Dodge?s facility in Bagdad, Arizona. This paper reviews in detail the chemistry of medium-temperature pressure leaching of copper concentrates and reports on the process development work conducted by Phelps Dodge and others for this technology. This paper is Part I of a four-part series on this technology. Part II covers the development of medium-temperature pressure leaching and direct electrowinning technology; Part III considers the large-scale demonstration of the MT-DEW-SX process at Bagdad, Arizona; and Part IV addresses the development and design of a full-scale commercial application at Morenci, Arizona.

Jan 1, 2007

By Steve Kral

Amax Coal Industries Inc.'s Delta Mine is a medium-sized. high-sulfur coal producer that has lived up to the challenges posed by nearly six decades of a highly competitive domestic coal market. The mine now faces one of its biggest challenges - the same one staring at the dozens of other high-sulfur producers in the Midwest - the Clean Air Act Amendments of 1990. The 59-year-old mine, located in the coal fields of southern Illinois, has remained one of the state's oldest continuously operating mines by rolling with the ups and downs of the coal market and by incorporating new technologies and innovative productivity improvements into its operation.

Jan 1, 1993

By J. P. Rider

The number of extended cut mining systems has increased significantly in coal mines over the last decade, and there is a constant push to extend the face ventilation systems to even greater setback distances. The need to maintain airflow at setback distances of 12.2 m (40 ft) and beyond requires that methods for delivering intake air to the face be improved, or alternative ventilation techniques be implemented. The emphasis of this research effort was to examine various techniques to improve the distribution of available air at the mining face in order to reduce face methane levels. A study was conducted comparing the performance of a jet fan, used in conjunction with a machine mounted scrubber, with blowing curtain ventilation in a 27.5 m (90 ft) heading. In addition, a second study was performed on blowing curtain systems examining how scrubber flow, intake air velocity, and curtain setback influence face methane concentrations. Results showed that when the heading advances to a depth of 27.5 m (90 ft) blowing curtain systems were more efficient at diluting face methane levels when compared to a jet fan. Also, increases in scrubber flows and curtain velocity resulted in lower face methane concentrations for blowing curtain systems at 9.2 and 15.2 m (30 and 50 ft) setbacks.

Feb 24, 1997

By L. Frederick

Measurement of gamma radiation occurring in nature to characterize geological formations has been widely recognized in mineral exploration. Different methods and apparatuses have been developed for drill hole logging purposes. Geological formations vary in amount of naturally emitted gamma radiation. A gamma signature from a geological formation is captured by utilizing different types of gamma detectors. A natural gamma radiation detector (NGRD) can be used to control mining whenever there is a significant difference between the radiation levels in the mineral or ore being mined and the waste materials surrounding the ore. Surface miners, such as the one shown in Figure 1, can precisely control the elevation of the cutter as the machine moves over the surface of the formation. This type of machine is predominantly used in selective mining operations, e.g. surface coal mining. If there is a means to know the position of the cutter relative to the interface between the ore and waste, the miner can recover all or most all of the valuable mineral with very little out-of-seam dilution. This paper discusses the results of a successful application of gamma detectors to control a surface miner at one of North American Coal Corporations? locations - Red Hills Mine. The mine has nine coal seams in total with thicknesses ranging from 12? to 60?. The bottom six seams (Figure 2) are minable. The mine has complex geology and a significant amount of annual rainfall (4.7 ft). The mine produces approximately 3.5 million tons of coal and about 40 bcy of overburden per year. The operation utilizes diverse mining equipment including Dragline Marion 8200, electric shovel P&H 2800, Caterpillar end dump trucks CAT 785 and 789; bulldozers CAT D11, D10, D8, and D6. Coal is mainly extracted by utilizing a Wirtgen SM 4200 surface miner that is loading CAT 785 trucks with high volume coal bodies and payload of 150 t. Operational cutting depth is 24 inches with maximum cutting depth of 36 inches. Surface miner operators determine a cutting depth based on multiple cues, the most important being visual observations of a coal seam being cleaned or mined. The cleaning process involves removal of the last foot of waste material covering the coal seam. This is one of two critical phases in the coal extraction process. If, during the cleaning process, an operator sets a cutting head too deep, valuable product is wasted. If it is set too shallow, waste material is left to be mined with the coal. The second critical phase occurs in the last cut on the interface between the coal and waste material at the bottom of the coal seam. If the cutting head goes deeper than favorable, then waste material is delivered to a power plant.

Feb 27, 2013

By Lane White

The 1989 Annual Meeting and Exhibit of SME in Las Vegas, NV, February 27 - March 2, 1989, was the largest ever, drawing more than 4000 regis¬trants and 240 exhibit booths. Technical sessions included presentation of nearly 500 papers, including symposia on Biotechnology in Minerals and Metals Processing, Surplus Capacity in the International Metals Industry, and APCOM `89 - the 21st International Symposium on Application of Computers and Operations Research in the Mineral Industry. Technical sessions covered the gamut of minerals industry interests; however, the proximity of the meeting to recently surging gold development in Nevada drew special attention to gold operating practices. Several of the papers on gold processing are reviewed below. To keep pace with the strong world- wide interest in gold development, SME has scheduled three additional upcoming programs that will focus specifically on gold: World Gold '89 - Gold Forum on Technology and Practices will be held November 5 - 8, 1989 in Reno, NV, as a joint meeting and exhibit between SME and the Australasian Institute of Mining and Metallurgy. Technical sessions will encompass a full program of papers covering geology and exploration, mining, and mineral and metallurgical processing. Cooperating sponsors for this meeting include the Canadian Mineral Processors Division of CIM, The Institute of Metals, The Institution of Mining and Metallurgy, The Mining, Geological & Metallurgical Institute of India, and The South African Institute of Mining and Metallurgy. Gold '90 - Salt Lake City, UT, February 26 - March 1, 1990, will be a symposium held in conjunction with the 1990 SME Annual Meeting. Current research on the processing of refractory gold ores will generate innovative papers on process mineralogy at this symposium, with special emphasis on gold with pyrite and gold with carbon. Other sessions are planned for gold exploration and mining, gold metallurgy, gold plant design and practice, and gold in scams. Advances in Gold and Silver Processing Conference, October 1 - 3, 1990 will be held in Reno, NV. Preliminary planning calls for technical sessions on heap leaching practice, refractory ore processing, non-traditional lixiviants, bioleaching, metal recovery from solution, and the environmental aspects of processing operations. PLANT DESIGN, OPERATION Technical sessions organized by the Minerals and Metallurgical Processing Division of SME at this year's meeting in Las Vegas covered a wide range of gold operating practices. Eight papers relating to gold plant design, operation, and equipment are summarized here. Preprints of these papers are available by writing to Publications Sales, PO Box 625002, Littleton, CO 80162-5002 ($2.50 per paper for AIME members, $4 for nonmembers). Continuous elution process A. M. Stone, of Bechtel Australia Pty. Ltd., described the "Development of the Continuous Elution Process for Extraction of Gold from Carbon" (pre-print 89-75). Developed by Bechtel Pacific Corp. for Ok Tedi Mining Ltd., the Continuous Elution Process uses the same reagents as batch processes for elution of gold from carbon, while yielding significant savings in stripping vessel size and energy consumed in comparison with equivalent batch processes. The process is also simpler to operate than batch processes. Other advantages include reduced maintenance costs, higher average eluate grade, and near steady final eluate grade. Pilot testing for the Continuous Elution Process was conducted at Western Mining's Kambalda gold plant beginning in December 1982. The Continuous Elution Process is a continuous countercurrent system operating in a pressure vessel at elevated

Jan 1, 1989

By S. K. Kawatra, K. J. Shoop, T. C. Rao, T. C. Eisele

This study investigates the use of a horizontally- baffled column (7.6 cm inside diameter by 344.2 cm high) to reduce the ash content of a high ash bituminous coal. Tests were carried out to determine how the baffled column responded to changes in feedrate, reagent dosage, and feed quality, and to compare its performance with a conventional column installation in an operating plant. In this paper, the results of this investigation will be reviewed and discussed.

Feb 24, 1997

By J. R. Piper

“Old Borate,” located in the Calico Mountains east of Barstow, California, lead domestic colemanite production from 1884 through 1907. Mineral exploration at “Old Borate” in the early 1980's, examined borate mineralization in Tertiary lacustrine strata. Surface sample and drill hole locations, geology and structure, were hand-drafted on paper maps. To re-evaluate this data, the information was digitized using Geographic Information Systems software. Digital Elevation Model based terrain modeling integrated surficial samples with drill hole data to locate favorable drilling targets. Structural relationships were used to identify hypothetical resources formed by the leaching of boron from surface exposures, redeposited at depth.

Jan 1, 2001

By Gregory R. Gorrell

The legal issues surrounding the regulation of subsidence are among the major concerns facing the underground mining industry today. Whether subsidence occurs almost immediately as a result of longwall mining or without warning as a result of room and pillar mining conducted years ago, the resulting disputes are highly controversial and typical of the disputes involving the competing interests of surface and mineral estate owners. Until recently, the law governing these disputes was firmly established under the common law. The passage of the Surface Mining Control and Reclamation Act 1, the utilization of new mining technologies, and the general heightened environmental awareness of our times, however, have interjected new issues into this area of the law. State and Federal court decisions and administrative agency interpretations have helped clarify some of the issues. However, as evidenced by the many recent lawsuits between operators, surface owners, and regulatory agencies, many uncertainties still exist.

Jan 1, 1986

By Bhawani Singh, A. K. Dube, B. Singh

At least three hydroelectric tunnels constructed during the last decade through the lower Himalayan region in India have met with serious problems of supporting in squeezing ground conditions. Steel ribs under went intolerable deformations requiring rectification to provide space for concrete lining which delayed the projects inordinately. In an attempt to choose a rational method of predicting rock load, the authors have compared rock loads estimated from various classification systems and elasto-plastic theory with observed values. The deficiencies of the classification systems have been highlighted to show that the combination of elastoplastic theory and tunnel instrumentation programme provides better guidelines for the design of tunnel supports in squeezing ground conditions.

Jan 1, 1981

By G. H. Glos

There was a time when an occasional failure of a tailings embankment was considered an acceptable risk associated with mining activities. This is not the case anymore. A major tailings failure today could result in the indictment of mine officials, huge fines and a possible site closure due to the loss of operating permits. As a result of this changed operational environment, tailings disposal facilities must be operated with these potential consequences in mind. Physical controls for tailings embankments are prohibitively expensive. However, the nuclear industry has developed a system of administrative controls as an alternative to physical controls. Administrative controls may be defined as control of actions, through organizations and management, using written procedures, record keeping, review and audit to assure operation of a facility in a safe manner (10 CFR 50). Administrative controls can reduce the cost of operating tailings impoundments, as well as increase the level of confidence in these facilities.

Jan 1, 1999

By John Sleavin

As part of the Link Light Rail project in Seattle, WA, work was completed at the Pine Street Stub Tunnel (PSST) in early 2007 for the Central Link project. This tunnel was excavated using cut-and-cover construction within the limits of Pine Street. The stub tunnel provides a turn back via double crossover for light rail trains running in the Downtown Transit Tunnel (DTT), as well as a connection point for the next phase of the project, the University Link (Fig. 1). Designing the new University Link tunnel connection to the existing PSST was a tricky task. The on-site geotechnical conditions, buried obstructions, geometry, requirements for construction and balancing operational considerations and neighborhood stakeholder concerns associated with the recently completed PSST combined to create a uniquely challenging assignment.

Jan 1, 2010

By Lloyd M. English

During the past 30 years, the research arena has changed significantly in all fields, mining included. The relative representation of the topics of research, how the research is performed and who has performed the research have all changed. Although there are a lot of subjective ideas and anecdotal "analyses" concerning these changes, there has been no actual study of these trends to verify the facts. This study was divided into six five-¬year periods for the purposes of comparison. Some of the trends analyzed are co-authorship, research areas, research sponsors and cooperative efforts. In today's research arena, 30 years is a long time. Technology has advanced more rapidly than in any time previously and that pace continues to increase. There are more researchers, more tools for research and an increasing number of companies, agencies and institutions engaged in research. The pace of change and its impact is often discussed and debated at professional meetings and in institutions that engage in research. These conversations will often influence the research decisions of the participants in directions to take or subjects to pursue.

Jan 1, 1995

By S. Bargigli, S. Ulgiati, M. Raugei, F. Cherubini

Metallic magnesium is mostly used in lightweight alloys in order to decrease fuel consumption in automotive applications. Several different production processes are currently used worldwide, and the magnesium production scenario is changing rapidly, with Chinese production increasingly dominating the world market. For the purpose of this paper, a novel approach to Life Cycle Assessment was applied, in which Material Flow Accounting and energy-based methods (Embodied Energy, Exergy and Emergy Analyses) are integrated and complemented, with a detailed description of the environmental hazards associated with emissions from all the different processes.

Jan 1, 2005

By Mark Rybak

On Aug. 31, 2006, Tropical Storm Ernesto hit the city of Richmond, VA. The Battery Park area was hit particularly hard, as flooding forced an evacuation of the area. A large sinkhole collapsed a sewer line in the Battery Park area, blocking the pipe and causing more serious flooding. This article describes the fast track design, bidding and construction of an emergency tunnel to bypass the collapsed sewer. Innovative value engineering, tunneling and shaft-sinking methods and final lining design all contributed to the success of this project. The storm inundated Richmond, VA with up to 305 mm (12 in.) of rain that, in some areas, caused widespread flooding and damage. One of the hardest hit areas of Richmond was Battery Park. A major trunk sewer in the Battery Park area collapsed and caused local combined sewer and stormwater flooding. The collapsed sewer was a 2.4-m x 76-mm (8-ft- x 3-in.-) wide by 2.7-m- x 152-mm- (9-ft- x 6 in.-) high arch sewer that was constructed in the 1920s and later filled over with municipal solid waste and a soil fill cap to cur-rent elevations. A sinkhole was created in the area of collapse approximately 18 m (60 ft ) deep and 31 m (100 ft) in diameter. This caused the existing arch sewer to become blocked. As a result of this blockage, contaminated floodwaters reached depths in low-lying areas in excess of 8 m (25 ft).

Jan 1, 2008

By J. O. Marsden

Part I in this series of papers considered the chemistry of medium-temperature pressure leaching of copper sulfide concentrates and reviewed the metallurgical testing and initial process development for this technology. This initial work resulted in the development of a process flowsheet utilizing superfine grinding (to a P98 of 12 to 15 µm and P80 of 6 to 7 µm), pressure leaching at 160° to 170ºC, followed by conventional solution extraction (SX) and electrowinning (EW) for the recovery of copper. However, this process required a significant amount of concentrated acid to be fed to the pressure leach vessel to meet the reaction requirements, representing a cost of between $0.03 and 0.05/lb copper (2006 basis) produced by the process. It was immediately recognized that the development of a process that did not require such a large acid addition would be advantageous. This paper, which is Part II in the series, describes the development of a process that incorporates medium-temperature pressure leaching and direct electrowinning (DEW) in a novel and innovative process flowsheet. Phelps Dodge (a subsidiary of Freeport-McMoRan Copper & Gold Inc.) refers to this as the ?MT-DEW-SX? process. Part III in this series covers the large-scale demonstration of the MT-DEW-SX process at Bagdad, Arizona; and Part IV addresses the development and design of a full-scale commercial application at Morenci, Arizona.

Jan 1, 2007

By J. H. Daniel, S. Krzemien

Partners In Economic Reform, Inc., established a Polish-American Mine Center in Katowice, Poland, in 1996 to improve working conditions in the minerals industry. The program was based on the experience of mining companies, government, and labor in the United States, and was executed by a Coordinating Committee headed by the Center Director and Polish leaders from industry, State, labor, and academia. The cooperation among all parties has enabled safety and health issues to become part of industry restructuring with impressive initial reductions in coal mine fatalities. Existing work practices and attitudes of labor and management were assessed in coal mines throughout the country. Promotion, Rules, and Job and Task Analysis were identified as the areas requiring the most improvement, and are part of a post-graduate Safety Management program. Demonstration projects included measuring dust levels, using safety glasses, and promoting hazard awareness. Improved labor-management relations increased cooperation allowing for effective transfer of technology. Results can also be applied to improve the working environment of the manufacturing sector also undergoing restructuring.

Jan 1, 2001

By Peter B. Dowden, Robert A. Robinson

Boulders, frequently found in tunnels excavated through soils, can pose major problems for full face TBMs in terms of slowing or halting the tunnel advance, cutter damage, and abrasive wear. The paper aims to consider the problem as a whole, from the geological characteristics of boulder sites, to the appropriate physical design of theTBM, and its operation in boulder-laden soils. In addition, visualization of boulders and other subsurface obstructions by seismic methods and ground penetrating radar are reviewed. The paper will assist the construction planner in assessing the risks and preparing appropriate specifications.

Jan 1, 2001