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By William R. Yernberg

The current state of the copper industry was the topic of discussion at the Copper 99 — Cobre 99conference held Oct. 10 to 13, 1999, in Phoenix, AZ. More than 700 copper-industry engineers, executives, consultants, academics, vendors and other interested parties attended. This successful and well-organized conference was the fourth in a series of international conferences devoted to the mineral processing and extractive metallurgy of copper. The 1999 meeting marked the first time that the conference was held in the United States. The meeting was co-organized by the Minerals, Metals and Materials Society (TMS); the Chilean Institute of Mining Engineers (IIMCH) and the Metallurgical Society of the Canadian Institute of Mining, Metallurgy & Petroleum(CIM). The meeting was also sponsored by The Society for Mining, Metallurgy and Exploration Inc.

Jan 1, 2000

By A. K. Majumder

Particle motion in fluids is a subject of considerable practical importance to engineers working in fields such as hydraulics, river mechanics, chemical engineering and mineral processing. Many mathematical models have been proposed to predict the terminal settling velocities of particles in a fluid medium. The selection of an appropriate mathematical model has, therefore, become a challenging task for practicing engineers. This paper reports on an attempt to identify some of the useful models found in the literature for predicting particle-settling velocities in a fluid under free- and hindered-settling conditions. From this study, it was concluded that there is no well-accepted model validated by experimental data available for predicting particle hindered-settling velocities in a suspension of polydisperse and polydens particles. Collective efforts should, therefore, be made towards developing a hindered-settling model, as this is an absolute prerequisite for many model structures in mineral processing and other engineering disciplines.

Jan 1, 2007

By J. B. Hadaway

The current limit to power transmission for grinding mills through one mill pinion is approximately 7,500kW. Above this power rating either twin pinion arrangements or Gearless drives are required. The SMTP concept was developed to overcome this limitation by using two pinions with a single large drive motor. The SMTP mill drive offers major advantages in capital cost and greatly simplifies plant layouts, while using an innovative adaptation of industry-proven single helical gearing. Through the use of a single motor, provision of variable speed drive is greatly simplified. The SMTP can also be used for significant power upgrades on existing mills.

Jan 1, 2001

By William R. Yernberg

The early part of the decade was marked by world-wide problems and economic difficulties. In 1980, President Jimmy Carter ordered the failed military mission to rescue hostages in the U.S. Embassy in Iran, Mt. Saint Helens, WA erupted killing 60 people and the Soviets and Mujaheddin guerrillas clashed in Afghanistan after the Soviet invasion. Later in the year, Ronald Reagan was elected president, defeating Carter. The first launch of a space shuttle (Columbia) occurred in 1981. Also in 1981, the first IBM-PC’s begin to roll off the lines. In 1982, Argentina invaded the Falkland Islands and Mexico’s economy was in collapse. In 1980, the U.S. unemployment rate stood at 7.1 percent, and by 1982 the rate increased to 9.7 percent. 1980 marked SME’s first full year in its new office building in Littleton, CO. The new facility was dedicated in November 1979. Claude L. Crowley was executive director of SME in 1980 and remained in that position throughout the decade. SME’s membership stood at about 26,000 throughout this period (1980-1982).

Jan 1, 2007

By B. K. Blashich

In responding to mine fires and explosions, accurate and timely analysis of the mine atmosphere is critical in making decisions regarding firefighting, mine rescue and mine recovery operations. For many years instantaneous analyses were available to rescue workers using handheld or portable gas detection equipment, including infrared, electrochemical, or catalytic measuring devices for a limited number of specific gases such as oxygen, methane, carbon monoxide and carbon dioxide. Instantaneous sensing technology is not available for all gases, such as nitrogen and hydrocarbons, found in a mine fire atmosphere and cross-sensitivity can be a problem with this technology. For these reasons, air samples are collected for injection into a gas chromatograph for a complete and accurate analysis for all gases including oxygen, nitrogen, methane, carbon monoxide and carbon dioxide, as well as ?fire gases? such as hydrogen, ethylene, ethane, and acetylene. This method requires additional time for transporting the samples to the laboratory near the mine, as well as an instrument operator to inject the samples for analysis. The use of a portable micro gas chromatograph with a continuous and automatic injection system has been implemented by the Mine Safety and Health Administration (MSHA) during mine recovery operations. The device directly samples the mine atmosphere from an underground location every twelve minutes and automatically analyzes the samples for all of the mine fire gases. The portable unit utilizes micro technology and the operating software has been modified to perform the calculation of sample results in and Excel® spreadsheet without user interaction. This paper describes the micro gas chromatograph system and its use at a recent mine recovery operation. The automated remote operation of the micro gas chromatograph has been shown to be a good alternative to infrared and electrochemical sensors used for mine atmosphere analysis.

Jan 1, 2009

By Wern-ping Chen

Technical and non-technical challenges exist in each mega infrastructure project. It?s no exception to the first US underground PPP Port of Miami Tunnel (POMT) project in Miami, FL. The POMT will connect two man-made islands, the Dodge and the Watson Islands, under the Biscayne Bay within highly porous limestone formation. Permeability as high as 0.1 cm/sec has been identified. Its 41-ft outside diameter, if constructed, is the largest precast segment lining in the US. Besides its geological and hydro geological challenges and risks, local community influence and impacts have controlled the fate of this project. This paper describes its tender design enhancements and the evolving of its slow advancement in resolving local community issues.

By Clay Haynes

In 2005, Black & Veatch Corporation began designing a raw water conveyance system for San Luis Obispo County from Lake Nacimiento to the city of San Luis Obispo. The first element of the water transfer system will be a raw water pump station and lake tap. The wet well of the pump station will consist of a concrete lined shaft approximately 180 feet deep constructed in the very incompetent sandstone of the Vacqueros Formation. The lake will be wet tapped at approximately 172 feet below grade using a slurry earth pressure balance tunnel boring machine. The 48 to 72-inch finished diameter microtunnel will be approximately 500 feet in length. Construction is scheduled to begin in the winter of 2007.

Jan 1, 2008

By Robert Schnab

ASFINAG is responsible for the construction and operation of the Austrian highway system. It is approx. 2,400 km of highways and 65 tunnels with a total length of 200 km including the Tauern Tunnel. In order to improve the documentation of the tunnel construction, ASFINAG chose to use a state of the art tunnel scanning system to record the various stages of construction: excavation, initial shotcrete lining, smoothing layer and final cast in place concrete lining. The geometric and photogrammetric documentation is provided on a daily basis to all par-ties involved. This innovative concept provides accurate & complete information in real time. The tunnel scanner documentation of the 2nd tube at the 6.4 km long Tauern Tunnel will be presented in this paper as a part of the survey contract.

Canadian mining giant Teck Resources Ltd. will be the exclusive supplier of the metals used in the production of the more than 1,000 medals to be awarded at the Vancouver 2010 Olympic and Paralympic Winter Games. Teck, the diversified resource company headquartered in Vancouver, B.C., is providing 2.05 kg (4.5 lbs) of gold, 1,950 kg (4,300 lbs) of silver and 903 kg (2,000 lbs) of copper sourced from its operations around the world. In addition to the raw materials mines, this year?s medals will make Olympic history as they will be the first to contain metals recovered from processing the circuit boards from end-of-life electronics (e-waste) that would have otherwise been destined for a landfill. After mining or production through a variety of smelting and recovery processes, each metal has been refined to enhance the metal purity.

Jan 1, 2010

By Ray Brainard

The subsurface investigation for the Reach 4 Tunnel was expected to be completed in a single phase. This assumed that data from two nearby previous tunnels, combined with limited new subsurface information and surface mapping would be sufficient to characterize the rock behavior. Unforeseen rock conditions and complex faulting led to the recommendation for a second phase. This decision was not reached easily, as much of the follow-on work required helicopter support, and associated costs. The second phase of drilling found significantly more variability than the first phase and led to a very different and better understanding of the geologic and geotechnical conditions, and rock characterization.

The La Colosa, Colombia porphyry gold deposit is currently in the pre-feasibility stage. This large deposit has many types of gold mineralization: native gold, electrum, and tellurides. These variations in the gold mineralization lead to variability in the gold recovery. The final process flowsheet may include gravity concentration with cyanide leaching. Metallurgical testwork is utilized to identify the zones of ore that may be problematic to recover. To help select the samples that represent the fluctuating variability zones, geometallurgical models are constructed using mineralogy and geology data. These zones are then wireframed and compared to the geological and structural models for spatial correlation. Samples for the variability testwork will be selected from these different zones to identify and analyse the effect the different gold mineralization types have on the recovery. By using geometallurgy to aid in the sample selection for metallurgical testwork, the variability in the ore body can be understood and constrained to aid in process optimization.

Feb 27, 2013

By H. Y. Sohn, R. D. Hagni, M. K. Kojo

Reflected light microscopy was used to study the mineralogy and textures of experimental reactions of a nickel concentrate with a slag. Such an interaction is an important step in the bath smelting of nickel sulfide concentrate. Concentrate particles in the central portions of the pellets are rounded and develop vermicular SO2 gas porosity. In the outer portions of the pellets, the original minerals of the concentrate, pyrrhotite, pentlandite, pyrite, chalcopyrite, and violarite have agglomerated and reacted to form two intergrown phases: 1) pyrrhotite solid solution (Fe0.75Ni0.18Cu0.01S) and pentlandite solid solution (Fe0.58Ni0.51Cu0.03S). Magnetite formed euhedral crystals, skeletal crystals, and dendrites at the margins of the matte. Prismatic ferrohypersthene and octahedral Mg-Al-Fe spinel crystals and dendrites are present in the glassy slag.

Jan 1, 2001

By H. S. Rathor

NTPC (National Thermal Power Corporation), a multi-unit organization, is generating 26% of India’s total power. This power is produced from its 14 coal based stations and 7 gas based stations. NTPC is entering into the business of power-distribution, power-trading, setting up of coal mines and diversification in non-conventional energy sector as well. For achieving the goal of the country “Power for All” NTPC has taken a giant stride by entering into Hydro Power generation which is also the cheapest and the cleanest renewable source of energy. In its pursuit for excellence, 800 MW Koldam Hydro Power Project is NTPC’s first venture in hydro sector. In Koldam, hydropower potential will be harnessed by constructing a 163m high earth and rock fill dam in a narrow gorge at upstream end of Bhakra reservoir. The river diversion is envisaged through two parallel, 14m finished diameter ‘horseshoe’ tunnels of length 901m and 934m at village Kian on the right bank, where the river forms a 180° loop. The diversion tunnels are designed to accommodate a flood of 6500m3/sec, taking into account the maximum probable discharge of 200 years return period. The tunnels pass through dolomite and limestone rock formations. The excavation of tunnels was done with drill and blast method. The excavation was attempted from both inlet and outlet faces. During geological investigation a rock fault was located at the outlet area. The location of the fault was such that it was passing through the edge of the Tunnel-1portal and around 30m away from the face of the Tunnel-2 portal. The quality of the rock at Inlet was also poor. To save the portals from slips, excavation of the tunnels was planned to start after the completion of the open excavation and its support system both at inlet and outlet. The tunnel excavation at inlet was envisaged by approaching the tunnels’ portal by constructing a road through 540EL bench and meeting the inlet portals on the upstream end, which would have been ready by mid2003, only after completion of the open excavation and its support system. To save time and cost, it was felt necessary to modify the planning by starting the tunnel excavation simultaneously along with open works both at inlet and outlet. The excavation at the inlet face of the tunnels started in December 2002 after rerouting the approach road to inlet portals through haulage road on the downstream and similarly Tunnel-1 at the outlet was started in the low cover area before completion of open area works. Thus the tunnel—heading excavation was started nearly 06 months early with the change of methodology.

Jan 1, 2005

In this study, a 3D model of the shovel motion based multi-body system dynamics in the Automatic Dynamic Analysis of Mechanical Systems (ADAMS) environment was developed. The kinematics model of the shovel was modeled as a multi-body system, which comprises the lower, upper, and the attachment mechanisms. The Euler-Lagrangian equations were employed as the computational framework to describe the dynamic behavior of the model. A virtual prototype of the shovel was built in the ADAMS software environment. This environment allows the visualization of a 3D motion of the general mechanical system and the prediction of interference of the moving components of the shovel. The numerical analysis and animation of digging, swinging and dumping motions for the shovel were performed. The superimposed display of the deployment for the shovel in three phases allows a detailed examination of the dynamic interference among assembly components. This research provides a solid foundation for further shovel dynamics performance studies. Keywords: Shovel, Spatial Kinematics, Virtual Prototype, Visualization

Jan 1, 2009

By M. L. Harris

In underground mines, coal dust explosions are prevented by the addition of rock dust sufficient to render the coal dust inert. The National Institute for Occupational Safety and Health (NIOSH) has developed a hand-held instrument that uses optical reflectance to measure the explosibility of a rock dust and coal dust mixture. This instrument is called the Coal Dust Explosibility Meter (CDEM). In this study, NIOSH personnel accompanied Mine Safety and Health Administration (MSHA) inspectors on their routine band surveys in five and three underground coal mines in MSHA District 2 (PA) and District 11 (AL), respectively. While underground, NIOSH personnel and MSHA inspectors used the CDEM to assess the explosibilities of the dust samples. The values of percent incombustible content (% IC) determined by the CDEM agreed well with those obtained later by low temperature ashing (LTA) in both MSHA and NIOSH laboratories. Further, the meter identified some samples as potentially explosible that LTA analysis had found to possess sufficient rock dust for inerting. The CDEM provides more information on the hazards in the mine. Rapid identification of areas with explosible dust mixtures using the CDEM allows for immediate intervention rather than a wait of several weeks for laboratory analysis.

Jan 1, 2008

By Colin Lawrence

The Port of New York and New Jersey is one of the most heavily used transportation arteries in the world, handling nearly 40 per-cent of the North Atlantic shipping trade and directly providing nearly 230,000 jobs to the local economy. In 2004, $100 billion worth of consumer goods moved through the port. To accommodate future cargo volumes in the port, which are expected to double over the next decade and possibly quadruple in 40 years, deeper shipping channels are needed to provide access for a new generation of cargo mega-ships with drafts exceeding 13.7-m (45-ft) when loaded. Current channels within the harbor range in depths up to 13.7-m (45-ft), thus preventing carriers from using these larger ships, or requiring significant reductions in cargo to achieve lesser drafts to operate safely within the harbor. As part of the Harbor Deepening Project, the Anchor-age Channel would be deepened to 15.2 m (50 ft) below mean low water (MLW), for a length of 5,790 m (19,000 ft). The New York City Department of Environmental Protection (NYCDEP) owns, operates and maintains two existing water siphons in the harbor. Due to their shallow depth, both existing siphons must be relocated before dredging of the Anchorage Channel can be completed. Tom Costanzo, manager of capital programs for the Port Authority of New York and New Jersey (PANYNJ), says that ?While the re-location of the existing siphons under the Anchorage Channel is vital to the success of the deepening program, it is also a story of cooperation among key agencies at different levels of government resulting in improvements that will benefit the people of this region greatly.?

Jun 1, 2010

According to the previous research, it is found that the thickness of cover is mostly less than 100 m for highwall mining system. However, for most of the Chinese surface coal mines, the mining depth is over 150 m; on the other hand, the shovel-truck is the most common mining technology. As a result, a lot of residual coal will be remained around end-walls. Considering these facts, the calculated methodology of highwall mining system under thick cover is presented in this paper. Meanwhile, numerical simulation of highwall mining system under thick cover was carried out. The outcome shows that the calculated methodology for pillar stability of highwall mining system under thick cover presented in this paper is acceptable. In other words, the highwall mining system is feasible to extract the residual coal around end-walls in Chinese surface coal mines. Thus, not only coal recovery ratio can be improved, but also can increase the production life of surface coal mines in China.

Jan 1, 2012

By Steve Skelhorn

Over the recent years, major advances have been made in design of precast concrete segmental tunnel liner. Starting from basic, parallel sided rings, we now have state of the art, universal rings incorporating custom tapers to suit individual requirements. At planning stage, the ring diameter is normally fixed and the ring geometry is one of the first items to be assessed. Obvious factors such as TBM layout and curve radius can constrain geometry; however, there others factors that should be considered in order to optimize production. This paper takes a look at the history of the segmental rings and criteria for ring selection, including: general ring geometry;; individual segment geometry; ring taper, and ring width. This paper also explores optimization of ring with a focus on constructability.

By M. Schafer

The 20 foot diameter cast-in-place tunnel lining for Phase 3 of the Mill Creek Tunnel (MCT-3) has been completed. This paper will summarize aspects of liner design and address the construction approach in placing the liner in areas of tunnel that experienced crown overbreak. Tunnel lining production rates, installation procedures and form buoyancies experienced during concrete placement will also be presented.

Jan 1, 2008

By James M. Harrington, A. Azra Bilgin, JoAnn Silverstein

The prevention of AMD in situ is more attractive compared to subsequent downgradient treatment alternatives that do not involve source control. AMD source control can be achieved by shifting the microbial activity in the sulfidic rock from pyrite oxidation to anaerobic heterotrophic activity. This is achieved by adding biodegradable organic carbon amendments to the sulfidic rock. This technique was applied in an abandoned mine pool with a pH of 3-3.5. Following treatment, near-neutral pH and decreased effluent heavy metal concentrations were achieved. In situ bioremediation by enhancement of bacterial iron and sulfate reduction is a promising technology for AMD prevention.

Jan 1, 2005