Search Documents

By Helmut Westermayr, Michael Tergl

DESCRIPTION OF PROJECT Geographic Setting The Kops II plant is a pumped storage scheme of the hydroelectric power producer ‘Vorarlberger Illwerke AG’ which is currently under construction in the Austrian Province of Vorarlberg. The plant is located at the end of the Montafon valley and will be fed with water coming from the Silvretta mountain range (Figure 1) Description of Plant The Kops II plant shall be operated as a pumped storage plant with three highly flexible and quickly controllable power generating units. Each unit shall have a capacity of 150 MW and shall be equipped for both turbine operation and pump operation. The Kops II plant uses the existing Kops Lake as upper storage reservoir and the existing Rifa balancing reservoir as lower storage reservoir. All major plant components of the Kops II scheme are located below ground. Total investment costs areapprox. 360 million Euro. Construction Lots The construction works for the Kops II plant, which were subdivided into three lots, were launched in September 2004. It is planned that the first power generating unit shall go on line in the year 2007. The completion of the overall project and the operation start-up of the second and third unit are envisaged for the year 2008. Lot 1—Pressure Tunnel. The 5.5-km-long pressure tunnel forms the connection between the Kops Lake and the beginning of the pressure shaft. The tunnel was excavated by the use of a double-shield TBM. Lot 2—Pressure Shaft and Surge Chamber. The approx. 1.1-km-long pressure shaft was excavated by TBM, advancing from bottom to top. Featuring an inclination of80%, the pressure shaft overcomes a difference in height of approx. 700 m. Lot 3—Power House Cavern and Tailrace Structure. The power house cavern, which is being built approx. 150 m inside the mountain, forms the core of this plant. The power house is designed to accommodate three power generating units, and the transformer cavern is forseen to accommodate three transformer units. The tailrace structure serves the purpose of conveying the water to the lower storage reservoir during turbine operation and as water intake during pump operation (Figure 2).

Jan 1, 2007

By D. M. Muir

Thiosulfate offers a non-toxic alternative to cyanide for processing gold ores. The mechanism of leaching gold using ammoniacal thiosulfate solution is driven by the Cu(II)-Cu(I) redox couple and is complicated by competing ligands such as NH3 and S2O32-. It is shown that an understanding of the copper speciation and sulfur speciation is required to optimise this system. This paper presents Eh-pH and speciation diagrams for varying concentrations of Cu(II), S2O32- and NH3 and discusses the conditions under which various copper and sulfur species are stable.

Jan 1, 2001

Gary R. Steele is vice president, corporate marketing with Energy Fuels Resources. As such, he knows the global uranium market. The following are some of his thoughts on uranium?s place in the global energy picture. ME: What are Energy Fuels Resources? thoughts on the global nuclear power industry? Steele: The global nuclear power industry is a major contributor to the electrical needs of the world. Though generation by nuclear reactors has primarily attracted attention through the reactor accidents at Three Mile Island and Chernobyl, nuclear power continues to quietly and safely provide power to a growing and power-hungry world population. As of March 2008, 30 countries were operating 439 nuclear power reactors. Nuclear power plants provided about 15 percent of the world?s electricity production in 2007. France leads the world in nuclear utilization, with 77 percent of its power coming from nuclear plants. And Lithuania, Slovakia and Belgium each derive more than 50 percent of their power needs from nuclear plants. For much of the developed world, nuclear generation has already been contributing significantly to the supply of electricity. Additionally, 34 new nuclear plants are under construction in 14 countries. Leading the rush to build new nuclear generating plants are China, Russia and India. Each of these countries is building six new nuclear power plants. These 18 plants, totaling almost 12,000 MW of generation capacity, will require about 7.25 kt (16 million lbs) of U3O8 for their initial fuel load and will consume about 2.45 kt/a (5.4 million lbs/year) for the rest of their operating lives. The rest of the world, outside of the United States, has used nuclear power as a viable and economic generation alternative since the commercialization of utility nuclear reactors. And current activity supports the strong future of the nuclear alternative internationally.

Jan 1, 2008

The schlieren technique describes an optical analysis method designed to enhance light distortions caused by air movement. The ability to visualize air flow has significant implications for analyzing underground mine ventilation systems, including the enhancement of surveys and models. Currently, traditional schlieren methods are impractical underground. Background oriented schlieren (BOS) provides a solution to this problem. BOS requires two primary components, a professional quality digital camera and a schlieren background. A schlieren background is composed of a varying contrast repetitive pattern, such as black and white stripes. This background allows the camera?s sensor to capture minor light diffractions, such as those caused by air flow. Although BOS shows great potential for ventilation analysis, sensitivity is an issue. This paper seeks to validate the BOS technique for imaging flow through a regulator by comparing BOS images with traditional schlieren images. This paper also outlines initial experimental efforts used for the validation.

Jan 1, 2011

By Steve Polegato, J. Coady Marsh, Gary Landry

The Donkin-Morien Mine in Cape Breton, Nova Scotia, has successfully completed the excavation of a 7.6m (25-ft) diameter access decline over a distance of 3.5km out under the Atlantic Ocean. The tunnel, completed in December 1984, was driven through a sedimentary sequence of sandstone, siltstone, mudstone and various gassy coal seams prior to intersecting the Harbour Coal Seam where development work will commence. The tunnel was driven by a Canadian prototype tunnel boring machine (TBM) manufactured by Lovat Tunnel Equipment, Inc., Toronto, Ontario. The 7.6m (25-ft) diameter full-face shielded TBM operated at various grades from 0-20%. This paper outlines the TBM design, excavation, support and backup system utilized in the drivage. Problems encountered and drivage rates will be addressed.

Jan 1, 1985

Sustainable development is at odds with reality in the minerals industry. Increasing world population and aspirations are leading to increased energy and mineral consumption. Non-renewable fossil fuels are being exploited at a much faster rate than they are being discovered. Mineral reserves are diminishing and of lower grade. Despite recycling, many of the economic reserves of the rarer metals on which technological society has come to depend are being depleted, and many of the bulk metals are being exploited at ever increasing rates. And yet, mining continues, with a long-term downtrend in commodity prices, matched by more efficient mining and processing. Will society turn to a low carbon economy before fossil fuels are depleted? Will prices come to better reflect the full cost of mineral production? Will technology save us, or is it at the root of the problem? The key drivers continue to be an ever increasing aspirational population and the law of supply and demand, rather than sustainability considerations. The paper illustrates this with examples of worldwide and Australian data.

Jan 1, 2011

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 T. Bajpayee, J. Ellenberger

Microseismic monitoring and evaluation is one aspect of the National Institute for Occupational Safety and Health (NIOSH) research program. Roof falls are often preceded by a period of elevated microseismic activity, but not all periods of elevated activity result in a roof fall, nor do all roof falls occur after some amount of elevated activity. The objective of this study is to review periods of elevated microseismic activity and determine whether fracture activity rate can be used to anticipate the initiation of roof falls. The study was carried out at an underground limestone mine where major roof falls are associated with excessive horizontal stress. The progression of roof falls was detected by the microseismic signature produced by the rock falling from the mine roof onto the mine floor, which is termed a roof fall impact event. A total of nine elevated fracture activity periods that resulted in seven major roof falls were examined. It was observed that elevated fracture activity preceded the initial roof fall impact event in three out of four major roof falls. The initial impact event was not identified for the remaining three roof falls. Fracture event rates were analyzed and a roof fall alarm trigger of five fracture events in a ten minute time period was established for this test case. The fall alarm trigger was tested against six of the elevated activity periods. Four roof falls occurred in the six periods of elevated activity, and two would have triggered the alarm before the roof fall occurred, while two false alarms were generated. The results show that limited success would have been achieved by the microseismic system as a roof fall alarm trigger. However, the trigger would have been successful at warning of the onset of elevated activity, allowing mine employees to respond appropriately. The study highlighted some issues with implementing such a system in an operating mine, including the need for real time identification of fracture related microseismic signals among mining induced signals, and accurate location and identification of fracture clustering.

Jan 1, 2007

By J. Bertisen, G. Davis

Previous analyses of small samples of mining projects have found that feasibility studies tend to well under-estimate the actual capital costs of the project. Our review of 63 mining and smelting projects completed over 4 decades confirms that as-built capital costs are, on average, 25% higher than as estimated at the bankable feasibility study stage. There appears to be little attenuation over time of this bias in capital cost estimation, at first appearing to reflect an absence of learning on the part of the consulting engineer. We instead argue that this persistence of bias is intentional, driven by a scarcity of project financing and the need to inflate the project economics in a bid to secure financing. Around this intentional bias is a considerable amount of scatter. Roughly half of all projects’ as-built capita costs fall outside of the expected ±15% of the feasibility study capital cost estimate, even after allowing for intentional estimation bias. Cost overruns of 100% or more happen in roughly 1 out of 13 projects. The data reveal that a shifted lognormal probability distribution should be used when modeling mining project capital costs in a Monte Carlo analysis.

Jan 1, 2007

By Greg Partington, Darryl Thorburn, Charlene Wildman, Elisa Puccioni, Connie Payne, Campbell McKenzie

"Mineral prospectivity modelling of polymetallic nodule deposits has been completed over the Cook Islands Exclusive Economic Zone (CIEEZ) using the GIS based Weights of Evidence modelling technique. Polymetallic nodules, also known as manganese nodules, have been explored as a possible resource for a number of metals including cobalt since the early 1970s. Recent data on the nodule composition and abundance in the CIEEZ has led to a renewed interest in the prospectivity for manganese nodules in the region. The predictive modelling has used the most recently accepted mineral model for polymetallic deep-sea nodule deposition to identify factors that are most likely to map the presence of this type of mineralisation in the CIEEZ.Manganese nodules form on the deep seafloor as concretions formed by concentric layering of iron and manganese hydroxides around a core and they grow at a very slow rate, on the order of millimeters per million years. The available data for the CIEEZ indicates a greater abundance in the area of nodules formed by hydrogenetic processes, which are the result of slow precipitation of metallic components from seawater. The environment in which the nodules are most abundant is at depths between 4,000 m and 6,000 m in areas of low sedimentation rate. Hydrogenous nodules commonly grow on siliceous and pelagic clay sediment, they are less common on other types of sediment."

Sep 1, 2014

By P. J. Bethell

Background Increasingly complex geological conditions, with the presence of high ash binders in the mining horizon were encountered at the A.C. I. Dugout Mine near Price, Utah. This led to the production of high ash coal from the Dugout Mine during 2003 and 2004. This material had poor marketability and posed operating issues for the utilities burning the coal. Ash levels increased from typical levels in the 9-12% range to between 15 and 25%. etween 15 and 25%. Reviews of the mine plan and expected geological conditions indicated that further periods of high ash production could be expected. Action Plan Detailed sampling of the mine high ash production was carried out. The majority of the coal from the Dugout Mine is trucked to the Savage Coal Terminal (SCT) at Wellington, Utah where it is stored in multiple piles by quality. Coal at the mine is segregated by a CoalScan 2600, on-line analyzer into high ash, low ash and rock chute (waste material). From these piles, the material is crushed prior to shipment to SCT. The samples obtained from the various high ash piles were subjected to detailed sizing and washability analysis. Once this information was obtained, alternative circuit configurations were evaluated to process this material into a salable product. Water supplies in the arid terrain where the plant is located are scarce. This factor played a part in the final circuit design.

Jan 1, 2008

By Mahiyar Nasarwanji, Jonathan K. Hrica, Jonisha P. Pollard, Lydia M. Kocher, Brianna M. Eiter

Within the metal/nonmetal mining sector, fall-related incidents account for a large proportion of fatal and non-fatal injuries. However, the events and contributing factors leading up to these incidents have not been fully investigated. To help provide a clearer picture of these factors, an analysis of imminent danger orders issued by the Mine Safety and Health Administration (MSHA) between 2010 and 2017 at both surface and underground metal/nonmetal mine sites revealed that most orders are associated with fall risks. Of these cases, 84% involved the workers not using fall protection, fall protection not being provided, or the improper use of fall protection. Fall risks for workers most frequently occurred when standing on mobile equipment, performing maintenance and repairs on plant equipment, or working near highwalls. In most cases, a single, basic, corrective action (e.g., using fall protection) would have allowed workers to perform the task safely. Overall, these findings suggest that a systematic approach is needed to identify, eliminate, and prevent imminent danger situations. Furthermore, to protect mineworkers from falls from height, frequently performed tasks requiring fall protection should be redesigned to eliminate the reliance on personal fall protection.

By E. Jackson

This paper describes highlights of the Placer Dome MiniMole project - the development and testing of a robotic machine for mining narrow ore veins. A prototype hydraulically controlled robotic machine was built and tested. The machine provided a platform for testing numerous cutters in the field. Other cutters, e.g. undercutting devices, were tested in the lab. Extensive analyses were done on specific energies and cutter penetration. Three sets of quarry trials were done, then the machine was tested in an underground mine. Rock UCS values varied from 180 MPa to 230 MPa. The paper includes lessons learned and recommendations based on the project findings.

Jan 1, 2007

By T. J. Lynch

A new class of polymeric dispersants for industrial minerals has been synthesized and evaluated. Currently available dispersants give initial low viscosities at high mineral loadings, however slurry viscosities can rapidly double or triple on standing over the first several days. The new dispersants give low initial viscosities that are more stable and maintain a lower viscosity for at least one month. The new dispersants are made possible by controlling the polymer molecular weight distributions during their manufacture such that essentially all of the dispersant is adsorbed onto the mineral surface, preventing depletion flocculation.

Jan 1, 2012

By Gordon T. Clark, James R. Struthers, Celal Kirandag

INTRODUCTION Project Background The Washington State Department of Transportation (WSDOT) hired the Seattle office of Parsons Brinckerhoff to lead a team of consultants to produce an Environ-mental Impact Study and perform conceptual and preliminary engineering. The pur-pose of the Alaskan Way Viaduct and Seawall Replacement project is to replace the existing earthquake damaged and aging viaduct and sea wall, adjacent the downtown waterfront of Elliott Bay, with structures that have improved earthquake resistance and that maintain or improve mobility and accessibility for people and goods along the existing corridor. With an estimated replacement cost over $4 Billion and construction duration exceeding 8 years, it is one of the largest transportation design projects on the West Coast of the United States today. Seattle, Washington is a city of over 2 mil-lion people in the Northwest corner of the United States. Ever since the Klondike Gold Rush in 1897, Seattle has been considered a departure point to Alaska. Because of this, the street along the waterfront was named the Alaskan Way in 1930. Alaskan Way Viaduct and Seawall The Alaskan Way Viaduct (AWV) carries State Route 99 along the shoreline of Elliott Bay through downtown Seattle and is a vital part of Seattle’s highway system. The viaduct carries approximately 110,000 vehicles per day or 25% of all north-south traffic through Seattle (Figure 1). It is 3.4 km (2.1 mile) long with 3 lanes in each direction and was constructed of cast-in-place reinforced concrete between 1952 and 1956. The wear and tear of daily traffic, salty marine air, and several earthquakes have taken their toll on the facility. Studies in the mid-1990s provided early evidence that the viaduct was nearing the end of its useful life. The viaduct’s increasing age and vulnerability was apparent by crumbling and cracking concrete, exposed rebar, weakening column connections and deteriorating railings. In early 2001, a team of structural design and seismic experts began work to determine whether it was feasible and cost-effective to strengthen the viaduct by retro-fitting it. In the midst of this investigation, a 6.8 magnitude earthquake shook the Puget Sound region (the Nisqually Earthquake, located 56 km (35 miles) from Seattle and deep below the surface) caused moderate damage to the reinforced concrete structure. WSDOT closed the viaduct for inspection and repairs intermittently for several days over a period of several months.

Jan 1, 2007

By J. Olsson

Introduction Stainless steel has by tradition been a common construction material for hydrometallurgy processes and the most common grades can be found amongst the ASTM 300-series, i.e. austenitic grades of type 304L, 316L and 317L. However, there are a number of new grades available today, which imply more cost effective solutions for those designing plants where good resistance to acids, containing the desired metal ions, often contaminated with chlorides and other halides, is the key issue. There are austenitic-ferritic or duplex grades having the same or even better corrosion resistance than the austenitic grades and approximately twice the strength, which enables design in thinner gauges, which in turn implies less weight and less cost. They have also excellent engineering properties, enabling fabrication of process equipment, machinery and different types of tanks. On top of that, they contain less nickel and molybdenum than their austenitic counterparts, which implies not only lower cost for alloying elements, but also a more stable price when considering the price fluctuations for these alloying elements during the last years. This paper describes briefly the family of duplex stainless steel and it presents a number of relevant corrosion tests where duplex grades have been compared with austenitic grades. The results have in several cases been verified by in-plant exposures in zinc and copper production plants. It also describes applications and experience of duplex grades within a variety of hydrometallurgy plants. Installations of highly alloyed austenitic grades will be described as well. The corrosion tests and service experience reported cover hydrometallurgical processes based on sulphuric acid.

Jan 1, 2007

By Alfred Weiss

Selecting a minicomputer is not unlike selecting a costly piece of mining equipment such as a truck, shovel, crusher, or conveyor belt system. A marked difference might lie in the frequency at which such selection takes place; another difference might be mine management's familiarity with mining equipment vis a vis a minicomputer. These basic differences might prompt a mining company to seek the aid of a consultant when selecting a minicomputer system. Advantages and Disadvantages The fundamental advantage of employing an independent consultant is that it provides management with a source of knowledge and breadth of experience not readily available within the organization. If the consultant has a minerals background, such knowledge and experience are further enhanced by actual experience in exploration, mining, and mineral processing. If the consultant has worked within a mining company, such hands-on experience is supplemented with a meaningful understanding of the client's business; this facilitates communication between the consultant and members of the client organization. The consultant has been, so to speak, "in the client's shoes." There are several other advantages. Since computer systems cut across organizational boundaries, the independent consultant may be able to move within the organization more easily than an inside staff person to collect necessary information. Also, detachment from any manufacturer should provide the client with an objectivity and a set of recommendations as near optimal as feasible. The principal disadvantages lie in the area of continuity and accountability. Once the consultant's report has been submitted and his recommendations implemented, a discontinuity might occur. Also, if implementation does not provide the desired results, the consultant might not be available to correct the situation or account for actions taken. Proper selection of consultant services, relative to kind and duration, and the consultant's method of operation, will often prevent many of these aftereffects. Services Offered The professional consultant can help a client: •Define and summarize information systems technology* needs; • Evaluate alternatives such as in-house capability and capacity, time-sharing, or service bureaus; • Prepare a formal request for proposal (RFP) to be submitted to vendors; •Evaluate vendor proposals; •Evaluate the economics of lease vs. purchase; and •Assist in the conversion and installation. Thus, consulting services may range from evaluating an existing system and upgrading to a larger piece of equipment, to selecting a new first-for-the-organization computer. First, Define and Summarize Needs Regardless of circumstances, the most valuable document required before equipment selection is the information system plan (I/S plan). It helps insure that the company's information needs are met in a cost-effective manner. An I/S plan is usually a comporient of the mining company's overall business goals. Since an I/S plan is a formal vehicle for establishing and communicating the direction the organization intends to take to satisfy information requirements needed to achieve goals and objectives, most initial systems services are likely to center around creating such a document or updating an existing document. The trend toward company-wide I/S planning is increasing in the mining industry; however, smaller scale efforts focused at the information systems needs to support an individual

Jan 11, 1981

By M. Javier

This concept paper is presented in the hope of raising the awareness of mankind on the necessity for its peaceful coexistence with nature. It is a food for thought. It takes compromise and sacrifice of people, who will have to learn to curb their greed and move toward a more organic form of prosperity. A nature-friendly sustainability is first step toward the protection of nature that is critical to the mutual survival of mankind and nature. People need the resources from the finite earth to survive and nature needs the prevention of human destruction in order to continue to regenerate and provide. The contemporary notion of sustainability is self-serving. It serves the interest of industry by camouflaging itself to look like nature?s protector. The ?sustainability? concept presented in this paper aims to extend the longevity of the utilization of the limited natural resources for many generations to come. It is an important, responsible first step in creating a healthy sustainability concept that, when implemented, extends the longevity of mankind by the most efficient use of the finite resources on this limited Planet Earth, all the while taking into consideration the increase in anthropogenic activities due to exponential human population growth. This new definition of ?sustainability? has completely different characteristics than its contemporary versions. Nature has its own destiny, rules and principles. Being a part of nature, human society depends on it for survival and must play by its rules and never the other way round as in its initial pretensions. Society should not try to humanize nature, but rather to respect the rule of the nature in a peaceful way of co-existence. When implemented, this new concept of sustainability aims to affect the designs of engineered structures and revolutionize the recovery methods and processing of natural resources, such as mineral resources in the most efficient manner. Finally, this paper intends to stimulate critical thinking and initiate serious discussions aiming at producing a general consensus for the best definition for human society to not only enrich, but to extend its existence. Thus, the spirit of this new definition is pro future generations and environment. KEYWORDS: Sustainability Definition, Nature, Geomímic, Deproduction.

Feb 27, 2013

By Bhaskar B. Thapa, Michael T. McRae, Johannes V. Greunen

This paper describes the preliminary design of the fourth bore of the Caldecott Tunnels along State Route 24 in Oakland, California. The paper focus is on two major aspects of the project: initial support system design and seismic design. The initial support system was designed based on the New Austrian Tunneling Method (NATM).NATM provides the required flexibility to accommodate the variable ground conditions in the weak, folded, and faulted rock along the alignment. The seismic design provides a final lining system that meets serviceability requirements for a 1,500 year seismic event with an estimated peak ground acceleration of 1.2g.

Jan 1, 2007

By Troy Holm, Matthew L. Fuller, Frederick H. Earnest

Virtual Reality Animation Of The Proposed El Dorado Mine In El Salvador Assists Regulators In Reviewing An EIA

Jan 1, 2005