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By E. Carvajal I

Large diesel engines provide the mining industry the substantial power and torque needed to move large amounts of material efficiently. But the stresses generated by such power and torque necessitate complex maintenance programs to ensure the utmost operating capabilities are not compromised. Of all its available sensors, the Exhaust Temperature differential between the right and left banks can provide the most valuable indicator of the overall operating condition and potential degradation of a large diesel engine. BHP Billiton Escondida Mining has implemented real-time remote monitoring, diagnostics, reporting, and tracking of Exhaust Temperature differential using Modular® technology. As a result of the processes and procedures put into place surrounding their MineCare maintenance management system, Escondida has proactively replaced over 300 injectors, resulting in an increase of 4% in Engine availability.

Jan 1, 2011

By Michael McNinch, LaTasha R. Swanson, Jennica L. Bellanca, Justin Helton

Accident data indicates that mobile haulage poses a significant pinning, crushing, and striking risk. Proximity detection systems (PDSs) have the potential to protect mineworkers from these risks. However, unintended consequences of mobile PDSs can undermine the safety benefit they provide. Soliciting iterative user input can improve the design process. Users help provide a critical understanding of how mobile PDSs may hinder normal operation and endanger mineworkers. Researchers explored users’ perspectives by conducting interviews with mineworkers from seven mines that have installed mobile PDSs on some of their haulage equipment. Mineworkers reported that mobile PDSs affect loading, tramming, section setup, maintenance, and general work on the section. Mineworkers discussed the operational effects and increased burden, exposure, and risk. Mineworkers also suggested that improved task compatibility, training, logistics, and PDS performance might help address some of these identified issues. This paper also gives additional insights into mobile PDS design and implementation.

By Michael McNinch, LaTasha R. Swanson, Jennica L. Bellanca, Justin Helton

Accident data indicates that mobile haulage poses a significant pinning, crushing, and striking risk. Proximity detection systems (PDSs) have the potential to protect mineworkers from these risks. However, unintended consequences of mobile PDSs can undermine the safety benefit they provide. Soliciting iterative user input can improve the design process. Users help provide a critical understanding of how mobile PDSs may hinder normal operation and endanger mineworkers. Researchers explored users’ perspectives by conducting interviews with mineworkers from seven mines that have installed mobile PDSs on some of their haulage equipment. Mineworkers reported that mobile PDSs affect loading, tramming, section setup, maintenance, and general work on the section. Mineworkers discussed the operational effects and increased burden, exposure, and risk. Mineworkers also suggested that improved task compatibility, training, logistics, and PDS performance might help address some of these identified issues. This paper also gives additional insights into mobile PDS design and implementation.

By B. R. Benner

Progressive improvements in crusher design, screening efficiency, and operating experience along with the downsizing of many taconite operations has resulted in the abilitv of some crushing plants to produce a substantially finer product. This finer product opens the possibility of replacing the rods in the rod mill with balls as is the current practice at Sydvaranger, Norway. If this replacement could be accomplished substantial savings associated with metal wear and the elimination of rod charging may be realized. The purpose of this study was to compare the performance of a mill charged with rods with the performance of the same mill charged with balls at the pilot scale. The first objective was to establish whether we could achieve the same throughput rate at the same mesh-of-grind in a mill in which the rod media has been replaced by balls. The second point was to determine whether the ball media would create a significant tramp oversize problem.

Jan 1, 1990

By R. D. Smith

The Bureau of Mines (BOM) evaluated the technology, capital investment, and annual operating costs of emission control for further reductions of lead in ambient air at the East Helena, Montana, smelter, and the Glover, Herculaneum, and Buick smelter-refineries in Missouri. This study seeks to analyze the technology available to the domestic primary lead industry for attempting to further reduce lead emissions below 1985 levels. Through enclosure of concentrate unloading and handling areas and all lead-processing buildings, followed by venting these enclosures to the atmosphere through baghouses and the application of appropriate local controls, emissions can theoretically be reduced by a total of 2,424 pounds of lead per day from 1985 levels at the three Missouri operations. Using conventional technology, aggregated additional capital costs of $250,014,000 and annual operating costs of $18,507,800 are estimated for the four operations, resulting in a total cost of $0.063 per pound of refined lead. Continuous drossing techniques would assist in meeting OSHA standards in process areas. Continuous drossing would change capital and operating costs to $258,344,800 and $16,104,700, respectively, for a total cost of $0.062 per pound of refined lead. First quarter, 1986 open market price for refined lead was $0.184 per pound.

Jan 1, 1986

By G. Norman Owen, Roger E. Scholl

INTRODUCTION The analysis and design of underground structures to resist vibratory motion due to earthquakes has been of interest to engineers for several decades. The dynamic stability of a powerhouse cavern was considered in the 1960s (Campbell and Dodd, 1967). About the same time, the designers of the San Francisco Bay Area Rapid Transit system developed procedures for analyzing the subaqueous tunnels placed under San Francisco Bay and the tunnels excavated along the land portions of the alignment (Kuesel, 1969). Japanese designers developed fairly sophisticated procedures for analyzing subaqueous tunnels during the late 1960s and early 1970s (Kuribayashi et al., 1974). In the past decade, proposals to site important critical underground facilities in regions with moderate to high seismic activity have increased the interest in earthquake engineering of underground structures. Seismic designs or seismic studies have been conducted for rock caverns for storage of petroleum or location of power plants (Yamahara et al., 1977; Glass, 1976), buried tanks for fuels or rad¬ioactive waste (Fukushima et al., 1977; URS/Blume, 1976), tunnels for disposal of nuclear waste (Yanev and Owen, 1978; Wahi et al., 1980), and urban mass transit tunnels (Monsees and Merrit, 1984). One of the greatest drivers of the interest in seismic analysis and design of underground structures has been the proposals to dispose of high-level nuclear waste in mined repositories some 300 to 600 m (approximately 1,000 to 2,000 ft) below the ground surface. In 1979, the authors, in conjunction with Professor Tor Brekke, presented a paper on an evaluation and design procedure used in a study of a proposed nuclear waste repository (Owen, Scholl, and Brekke, 1979).

Jan 1, 1985

By R. N. Gow

The presence of enargite (Cu3AsS4) is problematic in gold processing because it is environmentally hazardous due to its arsenic content but also because it is double refractory causing both cyanide and oxygen consumption to increase. Selective leaching and treatment of the arsenic would prove advantageous prior to applying conventional gold leaching methods. The reactivity of enargite samples from Butte, Montana and Quiruvilca, Peru were spectroelectrochemically studied under alkaline conditions, pH range of 8-13, using Raman spectroscopy and cyclic voltammetry. Raman spectra of the surface were collected during and after voltammograms were potentially cycled in order to determine and compare surface species against theoretical EH-pH diagrams determined from mass-balanced thermodynamic calculations using StabCal software. Under slightly oxidizing conditions, covellite (CuS) peaks were found in a short matter of time, above ~100mV vs SHE for pH 9-13, suggesting arsenic leaching specifically occurred. At longer conditioning times, elemental sulfur was observed and tended to passivate the surface. The presence of sulfur suggests that copper was eventually leached. By operating above pH 12, under slightly reducing conditions near -300mV vs SHE, arsenic can be selectively leached as thioarsenate (AsS43-) or thiosulfate (AsO43-) without sulfur formation.

Feb 27, 2013

By S. L. Ducummon

Inactive underground mines now provide essential habitat for more than half of North America's 44 bat species, including some of the largest remaining populations. Thousands of abandoned mines have already been closed or are slated for safety closures, and many are destroyed during renewed mining in historic districts. The available evidence suggests that millions of bats have already been lost due to these closures. Bats are primary predators of night-flying insects that cost American farmers and foresters billions of dollars annually, therefore, threats to bat survival are cause for serious concern. Fortunately, mine closure methods exist that protect both bats and humans. Bat Conservation International (BCI) and the USDI-Bureau of Land Management founded the North American Bats and Mines Project to provide national leadership and coordination to minimize the loss of mine-roosting bats. This partnership has involved federal and state mine-land and wildlife managers and the mining industry. BCI has trained hundreds of mine-land and wildlife managers nationwide in mine assessment techniques for bats and bat-compatible closure methods, published technical information on bats and mine-land management, presented papers on bats and mines at national mining and wildlife conferences, and collaborated with numerous federal, state, and private partners to protect some of the most important mine-roosting bat populations. Our new mining industry initiative, Mining for Habitat, is designed to develop bat habitat conservation and enhancement plans for active mining operations. It includes the creation of cost-effective artificial underground bat roosts using surplus mining materials such as old mine-truck tires and culverts buried beneath waste rock.

Jan 1, 1997

By A. Festa

Secondary crushing often gets good press for its increases in energy efficiency and SAG milling rates but for a project considering this option the proposed benefits soon get overshadowed by implementation concerns. Reverse engineering from the published case studies is risky unless the reader understands the drivers impacting stability and operability of the circuit. This paper discusses the features of secondary crushing for Greenfield and Brownfield SAG mill grinding circuits. It is the author?s view that secondary crushing rarely adds value to a Greenfield project and restricts future expansion. Its application is best retro fitted to Brownfield operations where the benefit gained for capital expended is excellent. Two case studies are presented to reaffirm these statements. The first case study shows that the implementation of partial and total secondary crushing increases SAG mill power efficiency and it offers substantial incremental increases in milling throughput with staged capital investments for the crushing and grinding circuits respectively. The paper provides a critical analysis of process conditions for secondary-crushed grinding circuits, with particular emphasis on Brownfield circuit retrofits. Furthermore, the second case study quantifies the economic impact of secondary crushing on circuit design for plant start up and it illustrates the limit imposed on plant expansion.

Feb 23, 2014

By B. Fagerberg

Crushing and grinding practice in Sweden follows largely the international pattern. Certain special circumstances, however, have had an influence on the development. Most mines are worked underground in either quite small or in very large units. To utilize small sulphide ores, custom milling is rather common. Apart from the cement industry, the rock species treated are hard and abrasive. Another important factor is the increasingly strict requirements placed on the mechanical condition of different products, especially lump ores and coarse iron ore concentrates. A significant feature in the design and development of Swedish crushing and grinding practice has also been close cooperation between machinery manufacturers and the users. An account of these conditions and an outline of the crushing and grinding techniques employed in Sweden are presented in this paper with emphasis on the mining industry. For background purposes it may be mentioned that crude ore production in Sweden last year included 45 mill. tonsx) of iron ore, of which some 20 mill. tons from Kiruna alone, and 4 mill. tons of sulphide ore from 22 other mines, fig. 1. In addition 8 mill. tons of limestone were quarried for cement production and several million tons of stone and sand for roads, aerated concrete, etc.

Jan 1, 1968

By Delon Hampton, Francis K. Mensah-Dwumah

INTRODUCTION The state-of-the art in the area of soil-structure interaction is not sufficiently developed that one can accurately predict the earth load distribution on buried structures. This lack of knowledge has led to the use of high factors of safety in their design and conservative assumptions for the loading diagrams. As a step towards the improvement of the design methodology for buried structures, it is important to be able to apply new analytical techniques and monitor the performance data obtained on full-size buried structures. The performance data should preferably include: 1) the actual stress distribution on the buried structure, 2) stress distribution in the buried structure and surrounding soil media, 3) vertical and lateral movements in the soil adjacent to the buried structure, and 4) deflection of the buried structure. Brown (1967), Davis (1972), Krizek, et al (1974), Krizek and MacQuade (1978), and some few others have compared the performance of full-size culverts with finite element results. Despite all these efforts, a complete understanding of the soil-structure interaction problem has not yet been fully achieved. In an effort to make improvements in the existing design procedures for buried structures constructed in an open-cut, the Department of Environmental Services (DES), Washington, D.C., in conjunction with Howard University, undertook a detailed study of Section II of the Capitol Hill Relief Sewer (CHRS). Inclinometers were used to measure lateral movements of the excavation wall and the total normal interface stresses acting on the concrete sewer were obtained using glotzl total pressure cells. This paper describes the results of the field instrumentation program for acquisition of data, their comparison with the design assumptions, and the results of a series of post-construction finite element analyses of the CHRS project.

Jan 1, 1979

This geometallurgical study examines the gangue mineral variability at the Bingham Canyon porphyry copper mine in Utah. Understanding an orebody?s mineralogy is important for mine and mill planning because it provides information on the size, texture, and distribution of ore minerals, the relationship between ore and gangue minerals, and the extent and type of alteration. Quantification of the mineralogical variability and properties of an orebody provides valuable input to the ore model and may have a significant effect on recovery optimization. This study was designed to be carried out on an initially detailed scale in order to develop a robust methodology for measuring and quantifying specific parameters, such as the distribution of mineral phases, alteration assemblages and fractures from key ore domains at the Bingham Canyon mine (Figure 1). Details of the methodology are reported below. This technique can be applied to testing the impact of mineralogy on a number of processing parameters. [ ] Figure 1. Ore domain map of Bingham Canyon (Kennecott Utah Copper, 2003) showing the 33 geometallurgical ore domains. The samples for this study were collected from the northwest part of the deposit circled on the map. PROJECT BACKGROUND Geology The Bingham Canyon deposit is a large porphyry Cu-Mo-Au deposit with associated skarn and base-metal replacement deposits mined in an open-pit mine measuring about 2.5 miles across and 4,000 feet deep. The deposit is hosted by the Bingham Stock, a Late Eocene to Mid-Oligocene intrusive complex. The skarn is hosted by the Late Carboniferous-age Bingham Mine Formation, which is comprised of quartzites and basal limestones (Babcock Jr. et al., 1998). The Bingham Stock is a composite intrusive complex that was emplaced over a period of about two million years. The oldest phase is described as a fine-grained equigranular monzonite (MZ), which intruded the country rocks at 39.8 ± 0.4 Ma (U-Pb zircon TIMS age) (Parry et al., 2001). Subsequently, the quartz monzonite porphyry (QMP) was emplaced, followed by intrusion of a latite porphyry (LP). The final intrusive phase, which forms narrow dikes that crosscut the Bingham Stock, is represented by a quartz latite porphyry (QLP), which is dated to 37.5 ± 0.4 Ma by 40Ar/39Ar dating of sanidine (Deino and Keith, 1998). Also present, are a minette dike in contact with a QLP dike (Waite et al., 1998; Deino and Keith, 1998), and a biotite porphyry (BP), a quartz latite porphyry breccia (QLPbx), and a pebble dike (Redmond, 2002). The copper orebody is centered above the Bingham Stock and forms an inverted cup shape with three high-grade copper zones extending to depth. Molybdenite mineralization occurs within and extends below the copper orebody, but is not correlated with copper mineralization. The main sulfide assemblage is chalcopyrite, bornite, molybdenite, and pyrite. Gold is locally intergrown with chalcopyrite and bornite (Babcock Jr. et al., 1998; Phillips et al., 1998). The surrounding country rocks host skarn deposits with three main ore types - garnet skarns, massive sulfides, and iron oxides. The garnet skarns contain chalcopyrite and pyrite with magnetite veins. In the massive sulfides chalcopyrite and pyrite occur either in banded sulfides or in unconsolidated microbreccias. The iron oxides contain disseminated chalcopyrite with minor chalcocite and bornite (Harrison and Reid, 1998). The deposit is overprinted by several stages of alteration. Potassic alteration is concentrated at the center of the deposit. It is surrounded and partially overlapped by a propylitic alteration zone. Both zones are overprinted by sericitic alteration. In the northern part of the deposit evidence for argillic alteration can be found (Bowman et al., 1987). Similarly, the skarn deposit was also overprinted by several stages of alteration: wollastonite, idocrase, and garnet in cherty limestones, and quartz and diopside forming in calcareous quartzites. Distally, diopside was replaced by talc, tremolite, dolomite, secondary calcite, and pyrite, and quartz and sulfide veinlets with biotite and actinolite selvages are present. Andradite garnet, diopside, quartz, magnetite, hematite, and copper sulfides were overprinted by wollastonite (Babcock Jr. et al., 1998). Because the monzonite, quartz monzonite porphyry, latite porphyry, and quartz latite porphyry host the bulk of the mineralization, our research is focused on these lithologic units. Geometallurgy On the basis of geological (lithology, alteration assemblages, fracture density, copper mineralization) and metallurgical properties, the deposit has been divided into 33 ore domains by mine geologists and metallurgists (Figure 1). In map view, these domains cross geologically defined boundaries (MZ, QMP etc.). These domains reflect regions of the deposit that have particular, mapable attributes or properties. They reflect a combination of geological and mineralogical characteristics that combine to impact processing. Alteration, for example, as shown by talc mineralization, is one such key feature. Hardness may reflect the absence of sericitic but presence of potassic alteration. Structural discontinuities such as faulting, fracturing, or development of void

Jan 1, 2009

By G. Heinrichs

This paper is intended to provide information for one to be able to determine the slurry system head curve for pump applications. The slurry characteristics are the basis for what the size, material of construction, and critical carrying velocity of the pipe will be. The system head curve is adjusted by use of the pipe friction coefficient factor and slurry derate factors. An example using multi-staging of slurry pump curves is presented to compare the wear life relationship of pump parts for a tailing pipeline system head curve.

Jan 1, 1996

By Thomas C. Shapiro

This is the final article in a three-part series on microcomputers and application software in the mineral industry. The first article covered microcomputer terms and concepts. The second discussed exploration and mining software. This article will examine plant, administrative, and geotechnical software. Every effort has been made to be current in the latest software developments. Rapid change, however, is a fact of life in the computer world and any omission is inadvertent. Introduction Geotechnical disciplines have received considerable attention in software programming. Calculations are repetitive and the formulas needed to solve them are not extremely complicated. These programs are ideally suited to the microcomputer and the microcomputer is ideally suited to the consulting geologist or engineer, due to its low cost and reliability. In fact, the advent of the Apple (a registered trademark of Apple Computer Inc.) and, more recently, the IBM personal computer has caused an explosion of inexpensive software programs available to the microcomputing public. Another area that has benefited from computerization, although not in the same way, has been mineral beneficiation. Here, process control for start-up or phase-down operations has been used in newer plants for some time. Programs to perform various calculations are becoming more common as micros increase in number. Tappi Journal has a section with solutions to handheld-calculator and microcomputer problems. Process Modeling Most process modeling is still done only on mainframes. One such program is called ASPEN PLUS (a registered trademark of Aspen Technology), and a one-week course is recommended so the user can best use the program. This program is available through timesharing from University Computing Co. Programs to find an optimal solution using Linear Programming (LP) have been around for some time. Also, plant process simulation has been possible using simulation programs. Both simulation and LP are expensive to program and run. Although there are LP programs available for some micros, the user must be fairly knowledgeable about how to set up the problem. This is because each problem must be set up as a unique program that typically requires custom programming. There are some programs that can handle blending of mine crudes and examine economic parameters over the life of the mine. Plant Applications Areas relating to mine and plant applications with programs available for micros are maintenance, production reporting, inventory, accounting, and personnel scheduling. Maintenance Maintenance typically requires that certain jobs be performed in a particular sequence and parts be ordered with enough lead time for maintenance to take place on time. There is, therefore, a critical sequence of tasks that must be performed or the scheduled maintenance will not take place. Two answers needed for maintenance project scheduling are: what is the lead time needed

Jan 4, 1984

By Dennis Molvik, Omar Fulton, Chris D. Breeds, Don Gonzales

This paper presents and describes the South Interceptor Parallel Phase III Contract C93012C, which involved construction of a nominal 2.7 m (9-ft) finished diameter sewer conveyance using both pipe jacking and conventional tunneling methods. Earth Pressure Balance (EPB) excavation was required to minimize the potential for settlement beneath a main rail line, overpass, sensitive wetland, areas of contaminated soils, and nearby structures. Ground conditions predicted in the Geotechnical Baseline Report included low plasticity, clayey silt (40 to 10%) and silty sand (60–90%) with pieces of wood such as logs, stumps, branches and other tree fragments. Soil cover ranged from 2.7 m (9-ft) to 5.4 m (18-ft) over the tunnel crown with a groundwater table between 1.5 m (5-ft) and 3.7 m (12-ft) deep.

Jan 1, 2003

By K. Mondal

A macroscopic approach integrated with microscopic analyses for wettability characterization is presented. Wetting depends on 1) Contact between the dust and the fluid droplets, 2) Wettability of the particles by the wetting fluid, and 3) Wettability rate (due to low contact times). The goal of this paper is to show that the wetting rate is a significant factor in dust control. Samples from the roof, three different horizons of the coal seam and the floor were pulverized to less than 25 µm. Experiments were conducted with known wetting fluids to correlate surface tension and equilibrium wettability. Further analyses were performed in terms of surface charge (zeta potential), particle size, mineral composition, elemental composition, and quartz content. The surface tension reduction was also achieved by the use of chemicals and/or altering the temperature of the water. Two methods were used to evaluate wettability rates: a) near real-time comparison of wettability rates, and b) comprehensive evaluation of the intrinsic wettability rates. The data obtained provides meaningful insights towards the design of engineering controls for an economical solution to dust control in coal mines.

Jan 1, 2012

By V. Gall, J. Rudolf

The Virginia Department of Rail and Public Transportation and the Metropolitan Washington Airports Authority are undertaking the extension of Washington Metropolitan Area Transit Authority’s Metrorail service to Washington Dulles International Airport and beyond to Route 772 in Loudoun County, Virginia. The roughly 37 kilometers long, double track alignment involves two 700 meters long single track, soft ground NATM tunnels at Tysons Corner, two 3.3 kilometers long single track rock TBM tunnels at Dulles Airport and one 25-meter deep station at the airport to be constructed by NATM in sedimentary rock. The design-build project is being implemented in a Public-Private-Partnership. A joint venture of Bechtel and Washington Group International has concluded the preliminary engineering and construction is scheduled to start in late 2007.

Jan 1, 2007

By L. Schlink

Impacted waters, often complex, are created in mining which at some point in the mine life cycle will need to be attended. The simplest and most cost effective method of handling impacted water is to reuse it as makeup water for operations. At the end of mine life, operational reuse will not be an option and the impacted water will require treatment to achieve alternative reuse goals. Conventional mine impacted water treatment is successful in removing unwanted constituents but create brine and sludge that may require special handling or additional treatment, resulting in additional liabilities and costs. Freeport-McMoRan Copper & Gold has taken an approach to water treatment that focuses on transformation not concentration. The Water Treatment Test Facility located at Sierrita Mine has three test plants that are piloting the mine impacted water transformation process. Two plants have been designed for the removal of calcium and sulfate with products of gypsum and sulfur. The third plant removes metals from process water and transforms them into marketable metal sulfides. The transformation, rather than concentration, of mine impacted water solutes greatly reduce long term risks.

Feb 23, 2014

By M. R. Yenchek

Faulty insulators on mine trolley/track haulageways may allow the flow of leakage currents into the mine roof and ultimately result in combustion of the local roof material. The National Institute for Occupational Safety and Health (NIOSH), Pittsburgh Research Laboratory (PRL), has devised a passive means to detect overheating insulators on direct current systems. The detector consists of a spring-loaded cartridge that ejects a reflective streamer of white Teflon tape when subjected to elevated temperatures. The cartridge assembly can be easily installed over the outer metallic shell of an existing trolley line insulator. If an insulator overheats due to ground leakage currents, the visible streamer alerts mine personnel traveling on the haulageway.

Jan 1, 1998

By R. A. Limons

Natural ores, sinters, and pellets were subjected to a carbon monoxide reduction-disintegration test under laboratory conditions including a simulated blast furnace gas and a 1000°F temperature. The most significant findings were that: 1. Self-fluxed pellets broke down to a greater extent than either the acid pellets or the acid or self -fluxed sinter. 2. When pre-reduced, both the acid and self-fluxed pellets had very good resistance to breakdown.

Jan 1, 1964