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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 Ian Hooper, Alan Winter, Stefan Sadokierski, Craig Covil

The existing Tappan Zee Bridge was built in the late 1950s and has been working over its design traffic load for some time now. A new project, which is being jointly sponsored by the New York State Thruway Authority and Metro-North Rail Road, is looking at new alternatives to provide new road and rail crossings of the Hudson River. These include 2 to 5 mile and potentially longer tunnel crossing options that include hardrock TBM and EPBM opportunities. The paper describes the project needs and tunnel concept design work done on some of the alternatives. It also relates to the current EIS process for the project and talks about a possible double-stacked tunnel option. It also talks about the geology and environmental constraints relating to tunneling and provides and introduction to the tunnel ventilation work necessary for tunnel crossing of this magnitude. It does not report on the bridge engineering options being evaluated.

Jan 1, 2005

By Harald Ulrik Sverdrup, Anna Hulda Olafsdottir

The long-term supply of nickel to society was assessed with theWORLD7 model for the global nickel cycle, using new estimates of nickel reserves and resources, indicating that the best estimate of the ultimately recoverable resources for nickel is in the range of 650–720 million ton. This is significantly larger than earlier estimates. The extractable amounts were stratified by extraction cost and ore grade in the model, making them extractable only after price increases and cost reductions. The model simulated extraction, supply, ore grades, and market prices. The assessment predicts future scarcity and supply problems after 2100 for nickel. The model reconstructs observed extraction, supply and market prices for the period 1850–2020, and is used to simulate development for the period 2020–2200. The quality of nickel ore has decreased significantly from 1850 to 2020 and will continue to do so in the future according to the simulated predictions from the WORLD7 model. For nickel, extraction rates are suggested to reach their maximum value in 2050, and that most primary nickel resources will have been exhausted by 2130. After 2100, the supply per capita for nickel will decline towards exhaustion if business-as-usual is continuing. This will be manifested as reduced supply and increased prices. The peak year can be delayed by a maximum of 100 years if recycling rates are improved significantly and long before scarcity is visible.

Jan 26, 2021

By A. W. Khair

This paper deals with the design characteristics of cutting tools and the operating parameters these tools are usually subjected to. Eight types of cutting tools/bits with different geometrical shapes and sizes were tested in a linear cutting apparatus, utilizing concrete blocks. The objectives of these experiments were to study the performance of each type of bit, make qualitative assessment of each bit geometry and size and establish cutting parameters for efficient utilization of the tools. During the experiment required forces Fx, Fy, and Fz, cutting, penetrating and lateral forces respectively and audible and sub-audible noises were measured. In these experiments, the depth of cut was kept constant to 1.5 inch while the bit spacing was varied 1.5,2.25 and 3.0 inch (3.75,5.6 and 7.5cm respectively). The results of these experiments indicated that by optimum ratio of depth of cut to bit spacing, the cutting face will be cleaned with the least ridge/land remains between the bit groves, resulting in least specific energy consumption, more large and less fine product particles and substantial reduction of audible noise. The results of these experiments also showed that proper bit design not only decreased cutting energy consumption but also reduced audible noise.

Jan 1, 2001

By Derek. C. Arnold

In order to meet increasing demands for water supply in the next millennium, the Government of the Hong Kong Special Administrative Region have identified the need for a major new water treatment and transfer scheme. The project now under construction will comprise a 1.2 km long raw water aqueduct, a major new 0.25million cubic metres per day water treatment works (with space for upgrading to 1.2Mm³/d), a 12.1 km long treated water aqueduct and a primary service reservoir. In order to meet increasing demands for water supply in the next millennium, the Government of the Hong Kong Special Administrative Region have identified the need for a major new water treatment and transfer scheme. The project now under construction will comprise a 1.2 km long raw water aqueduct, a major new 0.25million cubic metres per day water treatment works (with space for upgrading to 1.2Mm³/d), a 12.1 km long treated water aqueduct and a primary service reservoir.

Jan 1, 1999

By James McKelvey, Larry Drolet, Jason Swartz

INTRODUCTION When divers discovered that sections of a tunnel housing the pipeline that conveys wastewater from the Charleston Peninsula to the Plum Island Wastewater Treatment Facility had caved in, the Charleston Commissioners of Public Works(CPW) moved quickly to determine a long term solution for the city’s collection system, immediately focusing on the Ashley River sewer tunnel along the western boundary of the peninsula. Working with the Charleston community, as well as federal, state, and local officials, CPW developed a fast track yet long life design that can be used as a model for underground construction of tunnels in urban areas. The paper that follows summarizes key aspects of the Ashley River sewer tunnel project. HISTORICAL CHARLESTON Charleston, South Carolina is a culturally significant and historic city that was originally settled in 1670. There are over 100 buildings on the National Register of Historic Places within the Charleston area. Additionally, the first shots of the American Civil War were fired at Fort Sumter in the Charleston Harbor in 1861. As one can imagine, tourism generates significant business for the area with over 1.5 million people visiting Charleston each year. No project, especially one that requires digging, is done within the old city on the Charleston peninsula without careful planning. Many precautions are necessary to prevent damage or disruption to the historical properties. The Ashley River sewer tunnel project is exclusively in the old city. A lot of work was done during the design phase to minimize the impact to historical properties. Some of this work included: an archeological study (where pre-digs were monitored at all shaft sites by an archeologist); a building/structure assessment study (where structures near a shaft site were completely surveyed and cataloged); and an environmental study.

Jan 1, 2005

By J. Reed

The RockWorks EarthApps represent a free collection of 74 geology-related programs that read data from a built-in datasheet and create diagrams within Google Earth. EarthApps also includes programs that extract data from Google Earth. The programs that create diagrams include: point mapping (e.g. borehole locations), proportionally scaled icons (e.g. geochemistry), and strike & dip symbols. Line mapping utilities include; polylines, parabolas and pipelines. Polygon mapping programs include; thematic mapping (e.g. geology), mining claims, and public land survey sections. Image overlay capabilities include; draping (e.g. geologic maps) and time-based animations. Vertical image display capabilities are centered on either midpoints (e.g. drill-hole logs) or stretched between endpoints (e.g. cross-sections). The Flyover programs create virtual tours for site presentations. The cell-mapping includes a variety of algorithms (e.g. geochemical and geophysical contouring). Survey programs convert and export survey data to Google Earth as points and polygons. Programs that extract data from Google Earth include; points, lineations, polylines, and polygons. The RockWorks/EarthApps collection is developed by RockWare Incorporated based in Golden, Colorado.

Feb 27, 2013

By T. T. Chen

The behavior of gold in a conventional copper electrorefinery anode slimes treatment process is expounded on in this study. In the raw anode slimes generated in a copper electrorefinery, gold occurs mainly as tiny particles of metallic gold, which are commonly attached to selenide particles. Some gold is also present in selenide form. Decopperizing the anode slimes retains much of the metallic gold, but also promotes the incorporation of gold in the structure of silver-rich selenide species. A greater fraction of the gold is converted to (Ag,Au)2Se or Ag3AuSe2 when high-Se and high-Ag anode slimes are decopperized at elevated temperatures and pressures. After pelletization and roasting of the slimes, the gold is converted to a (Ag,Au)-alloy and Ag3AuSe2. Smelting of the roaster products eliminates the selenium and converts the gold to a silver-rich (Ag,Au,Pd)-alloy in the dore metal. In the subsequent silver electrorefining process, gold collects as a gold-rich (Au,Ag,Pd)-alloy in the gold mud. Dore smelting rejects many impurities as a silica slag; minor amounts of gold are present as a (Ag,Au,Pd)-alloy in the silica slag. This gold is recovered by flotation and is recycled to the dore furnace. Gold is identified in both the tellurium caustic leach residue and the parting plant wash water mud as tiny particles of metallic gold. These products are also recycled to the dore furnace to recover their gold values.

Jan 1, 2008

By C. Bachmann, M. J. Laurila, A. J. Widenman, A. Klein

Elemental analysis of slurry streams using X-ray fluorescence (XRF) has long been employed. However, detector technology has limited the application of XRF devices. Using detector technology employed on NASA's Mars Pathfinder to analyze soil samples, Process Control, Inc. has developed an on-line analyzer to mount on a sampling system. The prototype XRF elemental analyzer was installed at Detroit Edison's Monroe Power Plant in January, 1998 and has been employed to monitor feedstock quality. A slurry system has been developed for flotation control. This paper describes the testing of the analyzer using the new, draft ISO standard for evaluating the performance of online analyzers (ISO/DIS15239).

Jan 1, 1999

By Brendan Demich, Brendan Macdonald, Timothy J. Orr, Jason Navoyski, Jennica L. Bellanca, William J. Helfrich

Recent advances in computing, rendering, and display technologies have generated increased accessibility for virtual reality (VR). VR allows the creation of dynamic, high-fidelity environments to simulate dangerous situations, test conditions, and visualize concepts. Consequently, numerous products have been developed, but many of these are limited in scope. Therefore, the National Institute for Occupational Safety and Health researchers developed a VR framework, called VR Mine, to rapidly create an underground mine for human data collection, simulation, visualization, and training. This paper describes the features of VR Mine using self-escape and proximity detection as case studies. Features include mine generation, simulated networks, proximity detection systems, and the integration and visualization of real-time ventilation models.

By A. Moergeli

The Swiss are currently building the world’s longest tunnel, the 35-mile long Gotthard Base Tunnel. At Sedrun, for the first time in tunneling, four Roadway Support Machines will drive through most difficult ground, supporting variable diameters of up to 13 m. The machines are prepared for their first deployment. At Amsteg, two Hard Rock TBMs have successfully crossed a known fault zone by applying full circle steel arches and shotcrete immediately behind the cutter head. Comparisons between Drill& Blast and Hard Rock TBM are shown.

Jan 1, 2005

By Jim Nickerson, James McCleish, Tom Abkemeier, Nicholas Willig

The purpose of this project is to convey sanitary sewage from an existing pump station to a new waste water treatment plant. This paper will discuss the design and construction aspects of the project. The scope includes construction of three main shafts ranging from 34 to 100 feet in diameter at depths of 200 to 230 feet and 21,000feet of tunnel. Shaft construction consisted of slurry wall excavations keyed into claystone and limestone at depths ranging from 114 to 130 feet, followed by rock excavation utilizing drill and blast methods. The tunnel is being excavated in the Warsaw and Salem shale and limestone formations utilizing a 12'-6" diameter Wirth hard rock TBM.

Jan 1, 2005

By J. C. Potvin

Although the occurrence of deposits of titanium minerals on Kenya’s present day beaches and adjacent dune systems has been well documented, the potential for older formations to host economically viable deposits had not been recognised until recently. The Magarini sands formation in Kenya has been found to contain deposits of ilmenite, rutile and zircon in quantities and grades that have the potential to be commercially exploited. Since 1995, Tiomin Resources Inc. has explored these deposits and has identified one deposit, the Kwale project, as being able to support the development of a mine producing some 300,000 tpa ilmenite, 75,000 tpa rutile and 37,000 tpa zircon. Tiomin plans to start production by late 2002. Construction of a US$137 million operation is set to commence in the first half of 2001.

Jan 1, 2001

The global tunneling industry has many challenges, both technically and financially, with the latter likely to be a significant feature over the next few years. Many industries have ad-opted standard practices in order to overcome specific technical challenges, from which standard out-comes are anticipated. In tunneling, however, every project is unique so standardized practice is not easy. This requires original thinking and being open to adopting new techniques and technologies as they emerge. Sprayed waterproofing is a hot industry topic and a paper recently presented at the North American Tunneling conference not only discussed this methodology for achieving a dry tunnel but also how it can reduce build costs and construction time. Despite their being relatively few ?universal truths? throughout the tunneling industry, there is one opinion that appears to be shared by most in the sector, ?all tunnels leak.?

Jan 1, 2010

By R. Larry Grayson, Ahmet Unal

Use of radio frequency identification (RFID) technology to solve informational needs in isolated and restricted underground mining environments will be reviewed, giving specifications of some past and currently available systems. The advantages and disadvantages of using various frequencies, system configurations, and specific components, including their construction standards and capability, will be discussed. The remaining challenges to more widespread use of RFID systems for personnel and vehicle tracking will be identified, and recommendations concerning operating environment capabilities will be detailed. Finally, the ultimate requirements for maintaining system integrity during and following a coal mine emergency will be discussed.

Feb 24, 1997

By Martin Herrenknecht

The world?s growing population and rapidly proceeding urbanization are boosting an enormous demand for new and high-capacity infrastructures to secure the mobility of goods and people. Densely populated areas face the challenge to provide efficient traffic infrastructure, such as a modern public transportation system. At the same time, the maintenance and modernization of supply and disposal structures for water, sewage, energy and communication are also essential. Additionally, supra-regional transportation routes such as long distance water diversion schemes are the challenges for the future. All these projects are as demanding as they are characterized by a tight time schedule.

Jan 1, 2010

By Syd S. Peng

Mountaintop removal (MTR) mining started in West Virginia nearly 30 years ago. This surface mining method can extract multiple coal seams as thin as a few inches in whole and minimum rock dilution in very steep mountainous terrain. MTR is highly efficient, even if coal seams are in close proximity and small in a real extent. Consequently, MTR has been widely used in the Central Appalachian coalfield (mainly Kentucky, Tennessee, Virginia and West Virginia) with great success. In that respect, there has been no demand for research and little scientific research has been performed to investigate its impact on the surrounding area. During the past two years, however, the debate over MTR mining has grown quickly and has become very intense. This article describes chronologically issues raised by various parties, legal actions, impacts on mining permit applications and research projects developed to address the issues.

Jan 1, 2000

By P. A. Plunkert, D. E. Morse, L. McCartan, J. F. Papp

The mineral sector is a fundamental part of the U.S. economy. It contributes to the real gross domestic product (GDP) at several levels — basic (mining), intermediate processing, manufacturing of finished goods and construction. The real GDP during 2004 increased by 4.4 percent. The nominal GDP was about $11.7 trillion. Housing starts were up by slightly more than 4 percent for the year. And the nation’s unemployment rate decreased to5.5 percent in 2004 from 6 percent in 2003. Interest rates continued to be low (prime rate was 5.25 percent at the end of 2004) but have risen gradually, following rising inflation.

Jan 1, 2005

By Shawn Orser, Jennifer Waddell, Mike Sierakowski, Tom Barrett

Production evaluations were conducted at Daisy Gold Mine (Glamis Gold, formerly Rayrock), between August, 1997 and August, 1998 to quantify the effect of 3M fluorochemical surfactants (fluorosurfactants) on extraction kinetics and gold recovery in gold heap leach mining operations. Ore was treated at a level of 7-10 grams surfactant per ton of ore using 3M Pluorad TM Leach Mining Additive PC-GOLD. Kinetics and gold recovery were determined by solution assay for each of the tests. Both tests indicated improved kinetics, and data from Test 2 was used for determination of a quantitative increase in gold recovery resulting from PC-GOLD addition. A discussion of test results including methods used to determine gold recovery is provided.

Jan 1, 2000

By G. M. Rao, P. N. Deo

Graphite is soft and easily floatable but it is quite difficult to obtain high purity concentrate at coarse sizes. Chemical treatment can produce high grade concentrate but it is an expensive process. Graphite containing plus 96% fixed carbon (FC) with coarse flakes commands high price in international market. Such graphite concentrate containing plus 96% FC was produced in Indian Bureau of Mines (IBM) by using newly developed reagent (mixture of different hydrocarbons and terpenes, IBM/D7) instead of commonly used frothers viz. pine oil, MIBC, kerosine etc. and regrinding in a special type of mill with special grinding media instead of grinding in a conventional ball/ rod mill followed by cleaning. Both the new reagent (frother) and special grinding media are inexpensive and readily available. The process is under patenting. This paper focuses application of this new grinding methodology for flake size protection, and the new reagent for selective flotation of high purity graphite.

Jan 1, 1995