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By Li Jiuping, Zhong Gang, Chen Yong Zhang, I. Michael Gowring

The Liaoning Dahuofang Reservoir Water Transfer Project is an important development for the Department of Water Resources of Liaoning Province in northeastern China. The 85.3 km water conduit will transport water from the Hun River downstream of the Huanren Reservoir to the outlet on the Suzi River leading to the Dahuofang Reservoir. The additional water is required to sustain the growing cities of Fushun, Shen-yang, Liaoyang, Anshan, Panjin and Yingkou. The project is divided into seven contracts. Three TBM contracts comprise almost 75% of the work and the others are drill and shoot. The focus of this paper is about the creditable TBM performances achieved and some of the problems encountered by Chinese contractors; notably two having had no previous TBM experience.

Jan 1, 2007

By S. Maurhofer

The Uetliberg Tunnel in Switzerland is the longest tunnel in Zurich?s new Western Bypass Expressway, connecting the Birmensdorf bypass in the west with the existing Zurich-Chur national motorway in the east. Thus the tunnel links the Zurich-West motorway interchange with the Zurich-South interchange (shown in Figure 1). The Uetliberg Tunnel project comprises two parallel tubes, each about 4.4 km long. The two tunnel tubes are connected every 300 m by a transverse walkway and every 900 m by a transverse roadway (Figure 2). The SOS niches are spaced 150 m apart. Portal stations with machinery rooms are located at the west and east portals. The tunnel falls with a gradient of 1.6% from the west portal at Wannenboden to the east portal at Gänziloo. The Project costs are about CHF 1.12 billion. The carcass construction started in March 2001. The Opening of the Uetliberg Tunnel is planed in spring 2009.

By E. B. Graves

I have been asked to talk to you this morning about phosphate marketing and distribution. In discussing this I will attempt to answer such questions as: What is phosphate? Where do we get it? What form is it and how do we sell it? How do we distribute it? How is it applied? And last, but not least, What about the future? To start with, phosphate is one of the three primary plant nutrients. It is the element essential for root structure of plants. Plants, like humans, need a balanced diet. Thus, the amount of phosphate required by individual plants is, in part, related to how much of the other nutrients are used. Virtually all soils contain a certain amount of available phosphates. Back at the turn of the century the most common source of additional plant nutrient, including phosphates, was from cattle manure. The use of chemical fertilizers is something that has grown significantly during the last half century, and in particular, the last 20 years.

Jan 1, 1977

By B. L. Bessinger

Because of a, work stoppage at the Carlsbad plant, IMC faced the challenge of operating a 24-hour-a-day mine and plant with inexperienced maintenance and production crews. This is an underground mining operation, using the room-and-pillar mining- method. The mine was entirely, mechanized with conventional equipment, was hoisting an average of 13,539 tons off ore per 24 hours, and employed a, mine maintenance group of 100 men. The 100-man, mine maintenance group was equally divided between mechanics and electricians. In re-forming this maintenance group, two main objectives were to be achieved (1) a general upgrading off the intelligence level; and (2) the elimination of craft lines for greater flexibility.

Jan 1, 1966

By P. J. Best

Due to its low mine production costs, competitive rail rates and low sulfur content, the Southern Powder River Basin (SPRB) now commands 30 percent of the U.S. utility coal market. In 1996, production exceeded 260 million tons, a growth of 110 million tons since 1989 and 15 million tons over 1995. Continued growth is expected as the second phase of the Clean Air Act Amendments (CAAA) looms. This growth will be the greatest in the southern part of the basin, where coal quality is higher. This article is an overview of supply and demand issues affecting markets for SPRB coal. It reviews the current markets for SPRB coal and addresses future prospects for market expansion.

Jan 1, 1998

By Steve Kral

Mining is a risky business. The cost of exploring for new mineral deposits is high and the success rate of finding one worthy of development is relatively low. And once a deposit is identified, there is no guarantee that it will become a mine. Mining companies have to spend a lot of time and money on due diligence, prefeasibility and feasibility studies, and sustainable development and environmental issues before deciding whether the deposit will become a profitable mine. And then there are the millions of dollars spent in developing the deposit and building a mine. No wonder the mining industry has trouble attracting investment capital. Companies take a large risk in developing reserves and investors take a similar risk in investing in them. So mining companies must be as accurate as possible in determining mineralization that makes it to reserve status. After all, reserves are a company’s most important asset and one of the critical factors analysts and funding sources look at when determining if a mine or mining company is worth the risk.

Jan 1, 2003

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 K. Zeidler, T. Schwind

The Fort Canning Tunnel, Singapore, is an approximately 50 feet (15m) wide vehicular tunnel under shallow ground cover that has been constructed according to the principles of the NATM. Its shallow location in soft ground combined with a high groundwater elevation in close vicinity of historically important features called for special design considerations combined with a rigorous monitoring scheme. Surface, sub-surface and in-tunnel instrumentation was installed to monitor the performance of the ground and tunnel support during construction. Comparison of actual reading data with the results from the computer modeling carried out during the design phase is provided in this paper.

Jan 1, 2007

By Jr. Pitts

Elevation of surface charge density on colloidal particles in the presence of a high potential electrostatic field is demonstrated as a viable technique for preventing the accumulation of solids in solvent extraction circuits. The effect of the technique is manifest by relative turbidity measurements between pregnant leach solution and raffinate, by changes in the character of the sludge accumulations, by alteration of the zeta potential of particulates, and by a general reduction in the mass of solids.

Jan 1, 1992

By S. Panigrahi

The SO2-ammoniacal ammonium sulfate leach liquor generated by leaching of manganese nodules, after removal of minor quantities of iron and manganese, contained copper, nickel, cobalt, zinc and (NH4)2SO4. After extraction of copper from the leach liquor with LIX 84I, stripping of ammonia from the Cu-barren raffinate was carried out followed by precipitation of metal ions from the ammonia-stripped solution as sulfides. Leaching of the sulfide precipitate was carried out with H2SO4 to obtain a leach liquor containing 0.58 kg/m3 Cu, 2.67 kg/m3 Zn, 2.00 kg/m3 Co, 24.68 kg/m3 Ni and 10.0 kg/m3 (NH4)2SO4. After extraction of copper and zinc from the sulfate leach liquor with LIX 84I and D2EHPA, respectively, the solution was left with Co and Ni. Extraction of cobalt from the Cu- and Zn-free solution was carried out with 0.1 M PC88A and stripping of the cobalt-loaded organic was carried out with the cobalt-spent electrolyte (pH 1.4). Extraction of nickel from the cobalt-free solution was carried out with 90% neutral 1M NaPC88A followed by stripping of the nickel-loaded organic with 120 kg/m3 H2SO4 solution. Extraction of metal ions increased with increasing equilibrium pH and extractant concentration. The maximum separation factors, with respect to the pH and extractant concentration variation studies, were 3796.7 and 15350.0, respectively. The extracted species for the metal ions were CoA2?3HA and NiA2?5HA.

Jan 1, 2009

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 John R. Sturgul, Elizabeth Yost

The number of Native Americans presently working as mining engineers is extremely low-perhaps three in the entire US. At the New Mexico Institute of Mining and Technology, it was felt that introducing high ability students to mining engineering at the high school level would encourage more to consider mining engineering as a career. New Mexico Tech, in Socorro, NM, has initiated a continuing summer college program for Native American high school students. The program, which began in the summer of 1980, is designed to introduce participants to college life, enrich their high school curricula, and expose them to the problems and challenges of a career in mining and related engineering fields. Students From reservations throughout New Mexico with a demonstrated aptitude for science and mathematics were encouraged to apply for admission. Preference was given to high school sophomores and juniors since it is hoped that students will want to return for a second year before graduating from high school and beginning university studies. The program seeks to impress upon the students the need fir Native Americans in the fields of seience and mineral engineering.

Jan 7, 1981

By R. J. Snoby, J. K. Alderman

Although once fairly common as a method of coal preparation in the United States, dry cleaning has virtually disappeared. Low-rank coals used for power generation in the western U.S. are suited for dry cleaning because water has limited availability in the American west. Surface moisture added through wet cleaning offsets energy improvement achieved from mineral matter reduction. Information will be presented on the commercial application of dry cleaning in North America, the historic development and current status of the technology, and the introduction of modern processing theory and control technology to the design of dry cleaning equipment and plants.

Jan 1, 2001

S.L. Barua and Y.C. Kim M. Armstrong's paper is very interesting and can be regarded as a pioneering work of applying geostatistics on washed coal. The density levels used in her study are uniformly spaced, which facilitated curve fitting through a proper experimental design. Most of the existing coal washing plants in the US, however, gather washability data at non-uniform intervals which, in turn, affects the goodness of curve fitting. We would like to emphasize the importance of having a proper experimental design, if a similar geostatistical application is to be conducted on washed coal. We, at the University of Arizona, tried the variogram on recovery (Kim, Barua, and Baafi, 1982, SME preprint 82-143) which showed a similar pattern as Fig. 4 of Armstrong's paper. In both cases, the first experimental variogram value is invariably and inexplicably higher than the second variogram value. Although Armstrong ignores the first point because of "small number of sample points," we did not do so because there were 17 sample pairs. As a consequence, we concluded that the obtained experimental variogram was unsatisfactory and that further research is warranted. In other words, this disagreement in variogram interpretation between M. Armstrong and the University of Arizona begs the question whether the experimental variogram of Fig. 4 truly reflects the spatial correlation in washed coal, assuming there is such a correlation. Finally, we wish that Armstrong could have done a similar study on clean sulfur, which is a vital interest to the coal mines in the US. Her implied remark on sulfur in the concluding section of the paper may turn out to be incorrect because our experimental variograms on clean sulfur at different density levels were even less satisfactory than those on recovery.

Jan 1, 1985

By D. R. Nagaraj, Napoleon Tercero, Raymond Farinato

Historically, as for most reagents used in flotation, the wide-spread use of dialkyl dithiophosphinates as collectors in practical applications has preceded a detailed scientific understanding of how they work. Dialkyl dithiophosphinates are a technologically and commercially important class of collectors used in the flotation processing of Cu-Au, complex polymetallic, and precious metal ores. Plant usage has demonstrated that dithiophosphinates exhibit higher selectivity and flotation rates for Cu sulfides, galena, and precious metal values in the presence of other gangue sulfides, than the traditionally used collectors such as dialkyl dithiophosphates and xanthates. They also have an attractive health, safety, and environmental (HSE) profile. Although dithiophosphinates received little attention in the past in the flotation research community, recently, there has been significant interest in this chemistry, and numerous studies have been conducted to understand the fundamental interactions of dithiophosphinates with several base metal sulfides and precious metals. A critical overview of fundamental studies, laboratory ore flotation, and plant practice of dithiophosphinates is given in this paper. The findings from these studies are rationalized and explained by drawing on concepts and insights from coordination chemistry. A comparison between the interactions with various minerals and metals of dithiophosphinate and dithiophosphate analogues brings out some of the subtleties that seemingly minor changes in collector chemistry can make. The critical overview and analysis given here is useful in identifying gaps in knowledge regarding this important class of compounds. This in turn can provide a basis for the design of studies to advance our understanding of dithiophosphinate flotation performance.

By R. J. Lytle

INTRODUCTION Prior to excavation in soil and rock, it is useful to know the subsurface structure. This is important information both for safety and for equipment scheduling reasons. It is useful to know whether parts of the subsurface might be potentially troublesome or of different character than is generally thought present. By using geophysical probing, it is possible to infer the location and size of these unusual regions. The ground structure is commonly estimated from core samples taken from boreholes. These cores give a detailed knowledge of the structure in the borehole. However, knowledge of the structure exterior to the borehole can only be extrapolated from core data. By using seismic and electromagnetic cross-borehole geophysical probing, remote probing can be used to sense the region exterior to boreholes. A recent advance has significantly improved the state-of-the-art for defining the ground structure between boreholes. This new procedure utilizes large amounts of data and provides a detailed picture of the subsurface. The data processing algorithms used are similar to those in medical imaging of the human body using x-rays, a science called x-ray tomography. This imaging of the ground is called geotomography, which is a shortened acronym for geophysical tomography. Several examples of geotomography applied to imaging ground structure are presented. Our approach has been to probe the ground with electromagnetic and seismic waves. We map the region of interest with signals transmitted between multiple source and receiver pairs lowered in boreholes on opposite sides of the region (Figure 1). The received signals vary according to the transmission properties of the media

Jan 1, 1979

By Jan Van Greunen, Mark Vanderzee, David Haug, Geoffrey Hughes, Yiming Sun, Roozbeh Geraili Mikola

"The Sanitation Districts of Los Angeles County is planning to construct a new, approximately 7-mile-long (11.3 km) effluent outfall tunnel to be excavated by TBM and lined with precast concrete segments. Anticipated net operating pressures within the tunnel are expected to approach 3 bar. To counteract joint opening and exfiltration leakage, an approach has been investigated to post-tension the precast concrete tunnel lining with steel tendons. The tunnel alignment crosses several seismically active fault zones, at which installation of steel pipe is proposed as a secondary inner lining to mitigate potential offset displacements. This paper discusses the tunnel lining design approach and methods used to address these unique challenges.INTRODUCTION The Sanitation Districts of Los Angeles County (Sanitation Districts) is planning to construct a new 18-foot-diameter (5.5 m), approximately 7-mile-long (11.3 km) tunnel from the Joint Water Pollution Control Plant (JWPCP), located in the City of Carson, to the existing White Point outfall manifold structure at Royal Palms State Beach (RPSB) (Figure 1). The project is part of the Sanitation Districts’ Clearwater Program, which will improve overall system reliability through the repair and replacement of the existing aging infrastructure. The existing system includes two 6-mile-long (9.7 km) tunnels, 8- and 12-feet in diameter (2.4 and 3.7 m), and four ocean outfall pipes with a maximum capacity of approximately 675 million gal/day (MGD) (2.6 billion L/day). Addition of the new parallel tunnel will increase overall capacity to accommodate peak wet weather wastewater flows of up to 1,262 MGD (4.8 billion L/day) and will allow inspection and repair of the existing tunnels. The new outfall tunnel will be excavated using a pressurized face tunnel boring machine (TBM). Shafts at the north (JWPCP Shaft) and south (RPSB Shaft) ends of the proposed alignment will connect the tunnel to the existing wastewater treatment plant and existing ocean outfalls manifold and during construction act as launch and receiving shafts for the TBM. The tunnel will be excavated from north to south as a single heading."

Jan 1, 2016

By J. F. Childs

Montana consists of an Archean crystalline basement overlain by Proterozoic through Cenozoic sedimentary rocks. Igneous rocks range in age from Archean to Pleistocene; the most voluminous magmatism and volcanism occurred during the Late Cretaceous and early Tertiary. The state can be divided into three tectonic provinces whose deformational styles are a function of different bedrock responses to Late Cretaceous-early Eocene compressional tectonism. Several long-lived structural zones have been periodically reactivated since the Precambrian, and were the sites of recurrent magmatism. Regional gold distributions are strongly influenced by the tectonic provinces and structural zones. Lode gold systems in Montana occur in diverse geologic settings resulting from a complex interaction between structure, magmatism, and sedimentary depositional processes. Reserves or resources are known for 19 significant lode gold systems, and additional unannounced discoveries have been made recently. Mineralization ranges in age from Archean to Tertiary. The influence of long-lived structures is apparent at both the regional and deposit scale, and in some cases multiple mineralizing events have been superimposed upon one another. Most Montana gold systems have a direct spatial and genetic association with Late Cretaceous through Oligocene igneous rocks. However, the importance of sedimentary rocks and associated depositional processes should not be underestimated.

Jan 1, 1993

By D. Pappas

Over the past decade the number of contractors working in underground coal mines has nearly doubled; however, the effect this has had on the industry?s injury rates has been the subject of much speculation. The confusion exists because the U.S. Mine Safety and Health Administration (MSHA) database does not assign contractor hours to the individual mining operations where they worked. To better understand the safety record of the contractor segment of the industry, the National Institute for Occupational Safety and Health (NIOSH) undertook a comprehensive analysis of the data contained in the MSHA database. The first part of the study compared overall contractor and operator trends from 1983 to 2009 related to employment, hours worked, injury rate, and days lost. One unexpected finding was that the larger contractors tended to have higher injury rates than the smaller ones. The second part of the study directly addressed the role of contractors on the safety record of 10 large underground coal mines. A detailed analysis provided both injuries and estimated contractor hours worked at these mines for the period 1992?2007. Comparison between the estimated contractor injury rates and the reported operator injury rates at these mines indicated that the contractor injury rates were significantly higher at most of the operations studied. However, the industry-wide data indicates that contractor and operator injury rates have converged since 2005 and are now equivalent.

Jan 1, 2011

By Paul D. Tomlingson

Modern production equipment has been designed with greater productive capacity and higher reliability to meet the rigorous operating demands of the mining industry. These improvements have also made the equipment more complex and challenging to maintain. Whether these equipment enhancements contribute to more effective mining operations depends on the overall quality of maintenance. Maintenance is not a stand-alone activity. Although its quality depends primarily on maintenance, cooperation and support from other departments, coupled with the skillful guidance of mining managers, greatly influence maintenance success. Therefore, maintenance risk management must look beyond maintenance itself. Successful maintenance risk management begins with an assessment of the maintenance-related interactions of all mining departments within the mine’s stated operating strategy.

Jan 1, 2005