Search Documents

By John Trefny

Although mining is currently one of the smallest academic units on the Colorado School of Mines(CSM) campus, it is alive and well, with nearly 100 undergraduate and graduate students. For many years, Mines has had undergraduate and graduate programs in hard-rock mining. The school has recently transferred its physical mineral processing activities to the Mining Department. The program has also expanded to include tunneling, underground construction and industrial minerals. There are current discussions about increased research activities on cement and other construction materials. The Mining Department also teaches its share of what is called the “distributed core” courses with curricular requirements common to related programs, as well as mining safety and health, in conjunction with our continuing education department.

Jan 1, 2002

By D. R. Wilburn

The worldwide budget for non fuel mineral exploration was expected to increase by 27 percent in 2003 from the 2002 budget, according to the Metals Economics Group (MEG) of Halifax, Nova Scotia. The increase comes after five years of declining spending for mineral exploration. For the first time in several years, all regional exploration budget estimates for 2003 as defined by MEG would increase from similar 2002 estimates. However, MEG included 193 more companies in its 2003 survey than in 2002. As with previous MEG survey reports, estimates reflect anticipated expenditures rather than actual dollars spent. Caution, therefore, must be taken when comparing 2002 and2003 estimates or evaluating the magnitude of regional changes from year to year. Sample variations and currency exchange rates may influence year-to-year variations of MEG data. Even so, it is likely that the general climate of improved metal prices in 2003 encouraged companies that had previously left the mineral exploration sector or reduced their exploration activity to once again focus on minerals exploration or increase exploration activity and budgets.

Jan 1, 2004

By N. Damiano, C. Zhou, B. Whisner, M. Reyes

"The Industrial Internet of Things (IIoT), a concept that combines sensor networks and control systems, has been employed in several industries to improve productivity and safety. U.S. National Institute for Occupational Safety and Health (NIOSH) researchers are investigating IIoT applications to identify the challenges of and potential solutions for transferring IIoT from other industries to the mining industry. Specifically, NIOSH has reviewed existing sensors and communications network systems used in U.S. underground coal mines to determine whether they are capable of supporting IIoT systems. The results show that about 40 percent of the installed post-accident communication systems as of 2014 require minimal or no modification to support IIoT applications. NIOSH researchers also developed an IIoT monitoring and control prototype system using low-cost microcontroller Wi-Fi boards to detect a door opening on a refuge alternative, activate fans located inside the Pittsburgh Experimental Mine and actuate an alarm beacon on the surface. The results of this feasibility study can be used to explore IIoT applications in underground coal mines based on existing communication and tracking infrastructure.IntroductionThe U.S. approach to health and safety in mining has historically been reactive in the sense that health and safety regulations and mandates have traditionally been passed as a result of tragic mining accidents. An example of this is the Mine Improvement and New Emergency Response Act (MINER Act) of 2006, which was passed as a result of several mining accidents where tracking of and communication with underground personnel were severely limited. While this reactive approach has led to the development and implementation of highly impactful safety interventions and safety practices, there exists a technological revolution that can shift the paradigm toward a proactive approach based on preventative methods: Internet of Things (IoT).IoT is the network of physical objects, or “things,” embedded with electronics, sensors and connectivity to enable that network to achieve greater value and service by exchanging data with the manufacturer, operator and/or other connected devices (Atzori, Iera and Morabito, 2010; Gubbi et al. 2013). It should be noted that IoT has been defined from various perspectives, and hence numerous definitions exist in the literature. The apparent ambiguity of the IoT definition might be due to the fact that IoT is syntactically composed of two terms: the Internet and things. The first word pushes toward a network-oriented vision, while the second tends to put the focus on generic objects. The traditional Internet can be viewed as an internet of computers, so things connected to the Internet are computers only. IoT extends the internet by allowing other generic things that are commonly found in daily life, such as refrigerators and cars, to be interconnected through the Internet, thus creating a bridge between the virtual world and the physical world"

Jan 12, 2017

By Peter Dowden, Trevor Carter, Allan Moss, Bruce Downing, Richard Beddoes

Traditionally (with a few exceptions) tunnel boring machines (TBMs) have been utilized on tunnel projects where the risks associated with deep tunnels (rock burst, squeeze, etc) are low (or expected to be low). This has generally been due to the extremely adverse consequences of entrapping or damaging a TBM under such conditions; but also due to the relative difficulty of dealing with these ground conditions in the confined working area of a TBM, in comparison to a drill and blast heading. This paper review the constraints of operating a TBM in a deep tunnel and discusses related project experience, particularly recent and current experience with TBMs in the deep Alpine Base Tunnels. Potential future applications of TBMs in the development of large, deep underground mines are also discussed.

Jan 1, 2007

By Steve Skelhorn

Edmonton South LRT is the latest expansion of the Subway system in Edmonton, Alberta, Canada: Consisting of twin 5.8m segmental lined tunnels, 280m long, driven by a Lovat EPB machine. The key challenges were as follows. A 6% downhill grade. Tight radius curves of 250m.Overlying structures within 3m of the tunnel. Strata consisting of sand above the water table, glacial tills and bed rock below the water table. Located within The University of Alberta Campus and adjacent to a hospital. Northern Alberta climate with winter temperatures routinely falling below—minus 30 degrees Celsius. This paper provides a case history and outlines the challenges involved in completing this project.

Jan 1, 2005

By J. Brent Hiskey

Thiourea is a reagent capable of complexing gold and silver. With the proper oxidant, thiourea can effectively dissolve metallic gold and silver. A thiourea leaching system possesses potential advantages over conventional cyanidation including acidic solutions instead of alkaline, cationic complexes in contrast to metal-cyanide anoionic complexes, and faster leaching rates with acidic solutions of thiourea. Generally, the rate of metal dissolution in thiourea solution is fastest when ferric ion is employed as an oxidant. Acidic thiourea solutions for certain applications could offer a nontoxic and noncorrosive option for processing gold and silver. This paper provides information regarding the fundamental chemistry of the acidic thiourea system, and reviews the dissolution of both silver and gold in acidic solutions of thiourea. The recovery of gold and silver from acidic thiourea solution is discussed.

Jan 1, 1981

By Jerry T. Shelby

Surface and underground mining operations require equipment with high power output ratings. Haul trucks, loaders, dozers, and other equipment need increasing horse-power to meet production demands. To get more horsepower out of the engines driving the equipment, most manufacturers use turbocharging. Detroit Diesel puts the number at about 90% turbocharged, while Caterpillar estimates 75% to 80% of all its equipment is turbocharged. Turbocharging increases the power output and overall engine efficiency. But it presents some maintenance and operational problems that were not factors when only naturally aspirated engines (nonturbocharged) dominated the scene. A turbocharger is an exhaust-driven air compressor. Using the waste energy in the engine exhaust, a turbine wheel is driven. This wheel is connected by a common shaft to a compressor wheel. The shaft is supported by two plain bearings, or bushings. As the turbine wheel is rotated, the compressor wheel continually compresses the intake air to the cylinders. Compressing the intake air means that more air can be put into the cylinder to burn more fuel. The more fuel the engine can completely burn or combust, the more horsepower the engine can produce. Even though the turbocharger is a relatively simple device, it is a sensitive engine component. It requires special consideration at engine start-up and shutdown. Being freewheeling and exhaust driven, turbochargers can experience temperatures of 540°C 1000°F) and rotational speeds of more than 100,000 rpm. Due to those temperatures and speeds, lubrication is critical to the operation and life of a turbocharger. The turbo is located high on the engine, with the oil supply running through an external line from the sump. The recommended practice is to start the engine and allow it to idle for a few minutes before any revving or loading. This allows the oil to reach the turbo and properly lubricate the bearings before high rotational speeds are seen. Turbo oil supply lines can be as long as 1.5 m (5 ft). Depending on ambient temperatures and oil viscosity, it can take as long as 30 seconds for oil to reach the spinning turbo. However, as little as five seconds without oil can damage the turbo's bearings, reducing its life and overall efficiency. Lubrication problems seen at shut-down can also significantly affect turbo life and efficiency. Manufacturers recommend an idling period of five to seven minutes before engine shutdown. This allows the turbo to slow down and cool off somewhat to help prevent oil coking and bearing damage. When the engine stops, so does the oil supply. There is very little oil left on the bearing surfaces and in the turbo oil supply passages. The immediate heat transfer from the turbine wheel to shaft, bearings, and turbo body literally cooks what is left. This high heat without oil flow can cause bearing deformation by actually melting some of the bearing material. The rapid oil oxidation and coking will restrict oil passages, damage bearings and shaft. Besides heat soaking, there is another problem. If the turbo is spinning at high speeds when the engine is shutdown, the turbo must spin-down to a stop without oil flow. With the large size of turbos used on mining equipment, this spindown time without oil can be for as long as 10 to 20 seconds. Fortunately, lack of lubrication at start-up and shutdown and the subsequent bearing damage can be prevented by oil injection devices. These devices hold a reservoir of engine oil. The oil is injected to the turbocharger bearings immediately on start-up and for several minutes after shutdown. Oil injection devices are spring loaded, hydraulic accumulators. They are actuated at start-up by a solenoid wired to the starter motor. Engine oil pressure charges the accumulator during normal operation. Upon shut-down and loss of oil pressure, the device provides oil to the turbo for about two or three minutes. With an oil injection device, the engine can be started and immediately driven without fear of turbo damage. Also, an abrupt shutdown will not damage the turbocharger since the device will continue to lubricate for two or three minutes. A word of caution. Be sure the oil injection device provides positive oil displacement (pressurized oil flow). Do not use a gravity-flow device. Unless it is a true accumulator, the device could starve the turbo for oil on start-up, Ask for start-up and shut-down pressures and delivery times before considering installation. Keep the oil clean, and follow the manufacturer's recommended oil change intervals. These intervals are usually shorter than with naturally aspirated engines. Use oil with a CD rating designed for diesel applications. A multiviscosity oil is preferable. Use a synthetic engine oil, such as Mobil's Delvac 1, Gulf's Super Duty II, or Chevron's Sub-zero Fluid. Synthetics have much better flow properties at low temperatures. They also have greater oxidation stability (they can take the high heat of turbo-bearing lubrication. And they produce fewer deposits because they are more thermally stable. But synthetic oils do cost more - two or three times more. One additional point - maintain the air intake system. Since all mining is usually in a dusty environment, air filters should be changed regularly and intake systems should be checked for leaks. All intake air passes through the turbo. Any dirt or abrasives entering the turbo will damage the unit and shorten its life. While mining is a heavy duty business with severe operating conditions, you can get the life from your turbocharger that you expect by following a few simple steps: • equip the turbo with an oil-injection device to provide lubrication on start-up and shutdown; • change the oil and filters regularly; and • use the proper oil-synthetic, if possible.

Jan 3, 1987

By T. Hawthorne, H. Barnes

Homestake Mining Company has developed an estimating model, based on other closed projects, to audit and prepare new estimating plans. The results of recent closure audits reveal that the original budgets were often insufficient to cover the present expected expenses. Some of the major areas where technical challenges and costs are increasing include heap leach pile detoxification and rinsing, tailings dam closure, water management and treatment, abatement of contaminated soils, and many others. Risk and sensitivity analysis of each category will develop a level of confidence in the estimate and allow management to focus on the pertinent issues. Periodic audits of closure plans and costs throughout the life of mine serves to focus management attention on the complete costs of production. This will result in improved overall planning and management, and reduce the number of missed opportunities for savings.

Jan 1, 2000

By P. Perruzza, R. Grandori, A. De Biase, A. Ciamei, A. Busillo

The Turin metro alluvium soil is mainly made of large boulders, cobbles and gravel , few sand and almost no fines. This grain size curve is out of the range of application for EPB and Slurry TBMs. In order to bore 5 of the total 7,5 kms of Line 1 tunnel, two specially designed Lovat EPB TBMs were utilised in combination with a systematic non structural pre-grouting of a small volume rectangular slab just above the tunnel section. The same pre-grouting was not however applicable for lack of access on surface in some sections of the remaining 2,5 km of tunnel that had to be bored below important buildings/structures, with under ground water pressure up to 1,5 bar, with curves radius of 180 m only. For these more critical sections it was necessary to study and implement a new technical solution and improve the capacity of the TBM to work efficiently in EPB mode even in this unsuitable ground and overall conditions. After months of studies the selected and adopted solution has been to inject inside the cutterhead chamber, in addition to the almost standard foams & polymers additive mixes, a suspension of limestone powders. This with the scope of compensating the lack of fines of the natural ground with rock powders.

Jan 1, 2005

By Thomas C. Shapiro

Introduction In recent years - even months - the number of articles on computers has increased rapidly. One can hardly pick up a newspaper or magazine without seeing a computer-related article. The article usually explains how the computer will change our lives. Many of us have some concern about the nature and type of change. For most of us, though, the problem is lack of information and understanding about how computers work. In other words, how do we make cost-effective decisions about computers? This three-part series will explain, simply, what a microcomputer is, how it works, and how to decide if you need one. This first article will define terms and briefly discuss areas where computerization might be economic. The second article will discuss geology and mining applications. The third article will discuss plant, administrative, and geotechnical areas as well as the future of software development in the minerals industry. Terms and Concepts All computers have input and output devices and a central processing unit (CPU). Information - instructions and data - is communicated to the computer by means of input devices. These instructions to the computer are converted into language that the computer understands. This causes the instructions to be carried out in the CPU. The result of these operations is translated back into language that we understand. This information is then sent to output devices such as printers and video display tubes. Traditionally, peripherals were devices separate from the main-frame (the CPU and memory) and were used to input, output, and store information or instructions. Today, peripherals perform the same functions though they may be housed in the same cabinet as the CPU and memory. Historically, peripherals included all input and output devices not part of the mainframe. Input devices include keyboards, magnetic tape, and card readers. Tapes and disks are input as well as output devices. Output devices are printers, CRTs (Cathode Ray Tubes), and any mass storage device capable of storing data when directed to do so by the computer or the program. In fact, any mass storage device that can give the computer data when requested is an input device. Mass storage devices include floppy disks (thin, round sheets of plastic covered by metal particles), and hard disks. The latter are thicker and more densely coated with metal particles. This allows much more information to be stored. Another type of mass storage is magnetic tape. Its type and size varies widely. Processing and Storage Any computer understanding must include how instructions and data are processed and stored. Information is stored as a positive or a negative field known as a "bit." There are eight bits in a byte. The bits can be represented as either a one or a zero. Thus the code for a byte representing the numeral one is 00110001. The byte representing the letter A is 01000001. These codes are from the American Standard Code for Information Interchange (ASCII). ASCII defines the standard set of characters including alpha, numeric, and special characters. The computer's memory has allocated locations where instructions as well as incoming information can be stored. All information and instructions are stored as binary numbers bit by bit - zeros and ones. The amount of data that can be stored is referred to as either thousands or millions of bits or bytes. The letter "K" is used to designate one thousand units. The letter "M" is used to mean one millon units (one meg). Disks Thus, a 113-mm (5 1/4-in.) floppy disk - double sided and double density (DSDD) - contains 320,000 bytes (characters) or 320K. This is about 164 double-spaced, type-

Jan 2, 1984

By J. Wagner, P. Eger, G. Melchert

In 1991, LTV Steel Mining Company decided to close an open pit taconite mine in northeastern Minnesota, using a passive treatment approach consisting of limiting infiltration into the stockpiles and wetland treatment to remove metals. Over 50 million metric tons of sulfide-containing waste had been stockpiled adjacent to the mine during its 30 years of operation. Drainage from the stockpiles contained elevated levels of copper, nickel, cobalt and zinc. Nickel is the major trace metal in the drainages, and prior to closure annual median concentrations ranged from 1.5-50 mg/L. Copper, cobalt and zinc are also present but are generally less than 5% of the nickel values. Median pH ranges from 5.0 to 7.5, but most of the stockpile drainages have pH greater than 6.5. Based on the chemical composition of each stockpile, a cover material was selected. The higher the potential a stockpile had to produce acid drainage, the lower the permeability of the capping material required. Covers ranged from overburden soil removed at the mine to a flexible plastic liner. Predictions of the reduction in infiltration ranged from 40% for the native soil to over 90% for the plastic liner. Five constructed wetlands have been installed since 1992, and have removed 60-90% of the nickel in the drainages. Total capital costs for all the infiltration reduction and wetlands exceeded $6.5 million, but maintenance costs are less than 1% of those for an active treatment plant. Since mine drainage problems can continue for over a hundred years, the lower annual operating costs should pay for the construction of the wetland treatment systems within seven years.

Jan 1, 1999

By F. Freme

Coal production in the United States reached a record level in 2005, ending the year at 1.03 Gt (1,133.3 million st) according to preliminary data from the U.S. Energy Information Administration (Table 1). Production in 2005 was 19.2 Mt (21.2 million st) higher than the 2004 level of 1 Gt (1,112.1 million st) and surpassed the prior record set in 2001 by 5.1 Mt (5.6 million st). Although total U.S. coal consumption rose in 2005, not all coal-consuming sectors had increased consumption for the year. Coal consumption increased in the electric power sector by 2.2 percent and declined in the other industrial sector, while coking coal consumption decreased slightly.

Jan 1, 2006

By Rolland R. Mates

This paper describes the use of post- tensioned rock anchors to reduce the risk of future damage to a residential structure as a result of coal mine subsidence. The project described in this paper was performed by the Office of Surface Mining Reclamation and Enforcement (OSMRE) of the U. S. Department of the Interior. The OSMRE was created to administer Public Law 95-87, the Surface Mining Control and Reclamation Act of 1977. The responsibilities of OSMRE include "reclamation and restoration of land and water resources, adversely affected by past coal mining including prevention, abatement, control of coal mine subsidence. ?('l) Consequently, OSMRE has been addressing mine subsidence problems since its initial subsidence stabilization project in 1979. Stabilization activities have primarily consisted of supporting the overburden material by injecting materials through drilled bore holes into the underground mine voids. Injection of various materials into mine voids, including fly ash mixtures, coal refuse, cement grout, and gravel has proven to be a successful method of reducing mine subsidence-related surface movements, and has been extensively utilized in mitigating mine subsidence problems. However, the cost of drilling for injection can be extremely high in areas where the depth to the coal seam is great.

Jan 1, 1986

By L. W. Saperstein

Public Law (PL) 95-87 contains explicit demands for land use planning in its reclamation and designation sections. Both sections require recognition of local land use plans; however, they are not well integrated. Accommodation to these planning requirements affords an opportunity to create better links among local land use planners, the state's permitting authority and designation office, and mine designers. Mining companies should take a more positive interest in local land use plans and in resource inventories. States should consider handing down to local government the responsibility for accepting mine permit applications and designation of unsuitability petitions.

Jan 12, 1983

By Rajive Ganguli

There are several elements of online pedagogy and information technology that are being used in the University of Alaska Fairbanks’(UAF) course “ES 201: Computer Techniques,” to enhance classroom teaching. The use of information technology in this class grew from a desire to make lecture notes available to students. This has grown to include a sophisticated, online delivery software package. It provides chat rooms, discussion groups, and online testing and grading. Online delivery aside, the class uses the telnet, e-mail and C++/FOR-TRAN compiler facilities of the university server during class to enhance learning. During class, for example, the students read the lecture notes on the Web browser, telnet to their university Unix accounts, check their e-mail and download programs (to be covered in class) sent by me, and then compile, run and modify the programs. The class, therefore, requires students to be active most of the time. This ensures their full attention and better learning due to the hands-on experience (Fig. 1).

Jan 1, 2000

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 Y. Nien Wang, Moe Amini, Heiner Sander, Max John

INTRODUCTION As the population increased along the coast route (California Route 1), and the people’s need to have guaranteed access increased, the landslides and related road closures began to have serious adverse economic impacts. Landslides were causing major long-term road closures about every 10 years on average. In 1983, ground movement at Devil’s Slide caused Highway 1 to be closed for an extended period of time which caused significant economic loss to the surrounding coastal communities. A number of options for bypassing the slide area were considered, and the Martini Creek inland bypass was selected for design. Subsequent litigation led to the creation of the Devil’s Slide Tunnel Study in 1996. The results of this study indicated that a tunnel alternative would be competitive with the inland bypass. The final decision was left to the citizens of San Mateo County, who approved the tunnel alternative in the November, 1996 election After completion of environmental studies and the processing of legal challenges, the final environmental document was finished in 2001. The preferred tunnel alternative was designated to proceed for final design and construction. PROJECT DESCRIPTION The Devil’s Slide Tunnels consists of a separated two-lane road, one lane in each direction, which passes through twin tunnels and over twin bridges and then connects with the existing non-separated, two-lane road at each end. The total length of the project is approximately 1900 meters consisting of four main project divisions, which are described below, going from south to north. 1.Operations and Maintenance Center (OMC) area, 2.Southern approach roadways to the South Portals (250 meters), including the South Rock Cut,

Jan 1, 2005

By Harvey W. Parker

Our industry has developed to the skilled, experienced and productive industry that we now enjoy as a result of the visions of great engineers throughout history, but, in particular for their visions in the last 1 centuries. Unfortunately for our forefathers, the technology lagged so far behind that these exceptional visions could not be realized for decades, sometimes for a century. All that has changed in recent time and many bold and visionary projects can now be constructed and operated because of dramatic advances in technology. Before, say, 1950, tunnel technology developed very slowly. However, technology is now developing at such a fast rate that planners and decision makers are challenged to stay ahead. Moreover, new technology will develop during the lifetime of any project that can dramatically improve under-ground space projects. One of the best examples of this technological advancement is that of closed-face TBMs which now make tunneling feasible in previously impossible ground conditions. Since it usually takes a decade or more to plan, overcome environmental and political issues, construct, and put into service major projects, planners and designers are challenged by the changes in technology that occurs during the long time span of planning and construction. This is particularly true of large infrastructure projects such as transportation, water and wastewater systems and other major underground schemes. Also, since the serviceable life of many of these tunnels is often over one century, planners must consider not only lessons learned from the past but also what new concepts and innovations may develop over an extremely long time. These and other issues create a great challenge to planners and illustrate the great importance of careful but creative vision and flexibility during planning of long-term tunnel and underground space projects.

Jan 1, 2008

By Wern-Ping Nick Chen

Durability risks for underground facilities can be underestimated during design phase as compared to well-known geological risks. However, unclear durability requirements can result in construction schedule delay and change orders. Unlike bridges or buildings, a unified underground durability code or standard does not exist. This paper will provide a durability approach for underground facilities, including degradation modes, mitigations, and compliance measures during construction. In addition, this paper will address how to clearly specify durability requirements in a contract document to reduce disputes during construction and discuss key durability tests that are time consuming and will impact construction schedule if not timely planned.

Jun 23, 2024

By M. I. Al-Wakeel

Nile sediment was collected as a waste from one of the water treatment plants in Cairo, and subjected to petrographical investigation and granulometric, chemical, and mineralogical analyses. It was expected to find diatomite in that sediment but it was a surprise to find that the diatomite content amounted to about 52.01% by volume in addition to quartz, orthoclase and clay minerals. The latter are represented by montmorillonite and illite minerals. The sediment is light gray in color, soft and has low density and high surface area, such density and surface area generally decrease with temperature. The sediment absorbs 317% of its weight in water. The diatomite skeletons are the main factor responsible for its high porosity producing microporosity and low density, and these particles are concentrated in the very fine silt size fraction (11x2µm). The common diatoms in such sediment include Cyclotella ocellata Pant, and Melosira granulata (Ehr.) Ralfs. It seems that this Nile diatomaceous sediment has many advantages over the fossil diatomite, such as Fayium diatomite in Egypt, with the absence of carbonate minerals that require grinding and calcination those cause destruction of the cellular structure and energy consumption. This Nile diatomaceous sediment can be processed using sequential classification to obtain diatomite concentrate of 88.8% grade at 90.6% recovery, and a middling product of 19.4% grade and 5.8% recovery. The suggested flow sheet is quite simple to produce diatomite product for different industries at a low cost. The unusual particulate structure and chemical inertness make diatomite an ideal mineral to be used as functional filler in a wide range of industries, and as catalyst carriers and insulating material. Key words: Egypt, Nile sediment, Diatomite, Beneficiation, Sedimentation, Classification.

Jan 1, 2008