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By Sukru Sumer

East Pit Lake is an artificially created lake that resulted from the remediation and reclamation of surface coal mining operations at TransAlta Utilities' Whitewood Mine in the Wabamun area west of Edmonton, Alberta. The original excavation resulted from the creation of a mine end cut at the northern extent of the mining operation. The area of the surficial drainage basin that feeds East Pit Lake was relatively small. Therefore, most of the inflow and outflow from the lake would result from regional ground water flow. There was a concern about the lake's ability to provide a suitable habitat for a sportfish population. To determine the final recovered water level and rates of recovery, a two-dimensional ground water flow model was used. Data supplied by nested piezometers in and around the mine were used to calibrate the computer simulation and assess predicted recovery.

Jan 1, 1995

By Steve Kral

It seems that mining has been in the doldrums for awhile. Except for gold, metals prices remain depressed. And economic conditions in the United States and around the globe have put governments in a financial bind. This affects new building and infra-structure repairs, which, in turn, have a major impact the building materials industry. Add to that the severe environmental and regulatory restrictions placed on the mining industry in developing new mines and expanding existing ones. It’s enough to make a mining engineer/geologist/metallurgist go sell real estate. So why do those employed in the mining industry stay in the business and remain optimistic? Many of them will say that they have been through down cycles before and know that an upswing is in the offing. They also know that society will always need the commodities they produce. And they love the challenge. The challenge in mining’s case is producing commodities as cheaply as possible, in an environmentally sound manner and improving the quality of life in the communities where they work.

Jan 1, 2003

By F. Calizaya

This paper describes the basic requirements for the utilization of belt air to ventilate working sections at remote locations in relation to the main fans. It highlights the risks involved, potential problems, and the provisions that must be followed by mine operators for the safe use of belt air. The paper also presents a brief review of the current regulations, conveyor belting tests, atmospheric monitoring system requirements, and the experience gained by mine operators to utilize the belt entries to ventilate remote working sections or areas where mechanized equipment is being installed or removed. The paper concludes with a set of recommendations with respect to the utilization of belt air and the composition of belt material in under-ground coal mines.

Jan 1, 2008

By Thomas Gregor, Brian Garrod

As the popularity of precast concrete segmental linings for tunnels is growing in North America, some problems related to grouting of, and near, these linings are starting to appear. The installation of a segmental lining behind a TBM requires that the annular space around the lining be quickly filled with grout to prevent collapse of the ground. In practice, the filling of the annulus is frequently delayed and takes place a distance behind the machine typically via grout ports centrally located in the segments. If partial collapse of the annulus has occurred, it may become necessary to use higher grouting pressures in an attempt to distribute the grout. There have been several occasions where these increased pressures have caused damage to the tunnel linings. Similarly, compaction grouting adjacent to a tunnel lining can cause damage. This paper quantifies the effects of such grouting on a typical precast lining.

Jan 1, 2005

By Rajni Patel, John McDonald, Steve Dubnewych, Michael McKenna

The Upper Reach segment of the Northeast Interceptor Sewer (NEIS) is a3.2-km-long tunnel excavated in interbedded marine sedimentary deposits with approximately 40 m of cover. The tunnel was initially classified by Cal/OSHA as “potentially gassy.” During excavation, high levels of hydrogen sulfide and methane were encountered, prompting Cal/OSHA to reclassify the tunnel as “gassy.” In addition, the tunnel excavation encountered an abandoned, 100-year-old water tunnel known as the “Narrows Gallery.” This existing tunnel was completely full of water and under 30 m of hydrostatic head. This paper will discuss the unanticipated difficulties and design solutions implemented to construct a gassy tunnel exposed to high volumes of water.

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 David Young

This paper presents tunnel design considerations for the SR75/282 Transportation Corridor Project in Coronado, California. The project is managed by the City of Coronado in cooperation with Caltrans and the US Navy and may include a one-mile long twin-tunnel section with two options: a 36.5 foot diameter twin-bored tunnel or a twin cut-and-cover box. The alignment crosses the Coronado Fault, and design provisions were needed at the fault crossing to maintain life safety and prevent rapid inundation of the tunnel in the event of fault rupture. These provisions are discussed along with considerations related to liquefaction and ground shaking. The project is currently in the planning stage with construction to start around 2012.

Jan 1, 2008

By G. Biles, K. Loughran, R. Anand

The Eskay Creek Mine, a high-grade gold and silver underground mine in northwestern British Columbia started operations in late 1994. For the first three years of operation, ore was crushed to minus 2 inch; blended to satisfy smelter terms and direct shipped to smelters in Japan and Canada. Before commencing the above operations, preliminary evaluations had indicated that an extremely complex metallurgical facility, requiring a large capital investment, would be required to recover the precious and other economic metals. Subsequently markets for raw ore were identified and underground mining and ore transportation operations, at a nominal production rate of 300 tonnes per day, were commenced. Exploration diamond drilling in 1995 and 1996 discovered additional lower grade mineralised zones, which are less economic or uneconomic as direct shipping ore. Test work demonstrated that these lower grade zones could be upgraded to marketable concentrates in a simple flotation mill. The mill was built in 1997 and has been in operation since late 1997. The mining rate now has increased to 400 tonnes per day including 250 tonnes per day of the direct shipping ore and 150tonnes per day of the mill ore. Prime Resources Group Inc. wholly owns the Eskay Creek Mine. Homestake Canada Inc. owns 50.6% of Prime’s shares and manages and operates the mine on Prime’s behalf. This paper discusses the mining and milling operations as well as ore shipment and smelter contracts' administration.

Jan 1, 1999

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. K. Kawatra, A. K. Bakshi, T. C. Eisele

An on-line rheometer, suitable for use with slurries, has been developed at Michigan Technological University. This rheometer can be used with both Newtonian and non-Newtonian slurries, and produces complete shear-rate/shear stress curves which characterize the time-independent rheology of the slurry. The sensor utilizes the Hagen-Poiseuille equation and Boyle's Law to calculate the shear rate, slurry flowrate, and shear stress from a series of pressure measurements. The design of the unit allows the measurement sample to be continuously collected from operating process streams in the often-hostile on-line environment. The shear rate/shear stress curves can be used to conveniently calculate the apparent viscosity at any given shear rate, and also to measure any yield stress or other deviations from Newtonian behavior.

Jan 1, 1999

By Rodney K. Morrison

MARTA, The Metropolitan Atlanta Rapid Transit Authority, is building a 53 mile heavy rail transit system to serve the City of Atlanta. Phase A of the Rail System, consisting of approximately 14 miles of at-grade, aerial and subway construction is underway. Metropolitan Atlanta lies in the Piedmont Geologic province of Georgia and is underlain by rocks of essentially granitic and gneissic nature. The soils encountered are primarily silty sands which are in-place weathering products of the parent rock and exhibit their relic structure. In general, these materials have presented no unique construction problems other than those created-by proximity of manmade structures, local availability of ground water, and top of rock elevation. The subway sections of primary interest in this paper consist of hardrock and soft ground tunnels and extensive cut-and-cover sections. The cut-and-cover construction includes excavations as deep as 80 feet. Temporary support systems in these deep excavations consist of soldier pile-timber-lagging or soldier pile-tremie concrete (SPTC) walls with internal bracing or tiebacks. In shallow cut-and-cover sections, where right-of-way economics permitted, slopes were laid back partially or fully to reduce or eliminate the need for bracing systems. Dewatering systems were required in most open cut excavations. Due to the close proximity of utilities and existing structures to the MARTA

Jan 1, 1979

By Frank W. Luerssen

Introduction "Austerity" is perhaps an overly generous description of the past three years in the American steel industry. Steel plants operated at an average of only 57% of their capability in 1982-84. The dismal losses for last year are still being totaled. But during the two years before this period, American steelmakers recorded an aggregate net loss of a staggering $6.8 billion. Steelmakers responded by closing numerous marginal facilities. And production capability was cut by 13.6 Mt (15 million st). Capital expenditures still averaged $2 billion annually. But this was inadequate to maintain the existing base of steelmaking facilities. The general economy experienced a satisfactory recovery during this period. American steel, however, continued to suffer from a lagging recovery in the capital goods sector. This was due to record penetration of its domestic market by imports and from very weak realizing prices on the volume that was available. In addition to the direct influx of offshore steel products - which itself depressed prices - the industry also became painfully aware of the growing importance of "indirect" imports. These came in the form of steel-containing producer and consumer durables. Industrial equipment and autos fabricated from foreign steel accounted for the equivalent of 6 Mt (6.5 million st) of lost market opportunity for domestic steel-makers last year. That is over and above the 23.5 Mt (26 million st) of direct steel imports. Given these factors, Inland Steel was not spared from the threeyear downpour of red ink. Despite its record of continuing modernization in steel, our single-plant location in the world's best steel-consuming market, and the high proportion of consumer durables related products, such as cold rolled and coated sheet in our mix, Inland suffered aggregate losses of $277 million during the 1982-84 period. Strategic Planning The foregoing establishes a perspective - a base from which we have restructured our view of the steel industry, and of our own role within that picture. Until possibly two years ago, this present weakness in steel demand was viewed around the world as an aberration, eventually to pass. By contrast, it is now recognized that austere times are the normal steel environment. The topic here is management of resources. This implies an emphasis on strategic planning. It is worthwhile to examine some of the more critical assumptions that were driving strategies among a number of steel companies just before the 1980s. Those projected characteristics of the future steel environment were arrived at through painstaking analysis. They were carefully and heavily quantified and were generally shared by outside observers and our peers within the steel industry. • First, the assumption was made that domestic steel demand would continue to grow at an average rate of 2% per year. • Second, it was assumed that this growth in the American market would continue to be filled predominantly by US mills. It was believed that increases in steel and steel-related demand overseas would absorb much of the ominously growing capacity of third

Jan 6, 1985

By Clair Murdock, David Heath

The 1,280 MW Sir Adam Beck II Hydroelectric Project was constructed in the1950s, at Niagara Falls, Ontario, Canada. The twin intake tunnels total over 17 kilometers in length and pass deep below the City of Niagara Falls. The tunnels were excavated using drill and blast methods, with a top heading and bench approach. The shot rock was loaded with electric shovels and transported to the five shafts with off-highway trucks. The tunnel muck was hoisted to the surface by skip and transported by truck to disposal areas. The volume of underground excavation for the 15.55 meter diameter tunnels and the shafts exceeds 3,500,000 cubic meters, then and now the largest underground civil works excavation by drill and blast in the Western Hemisphere. The lining required over 900,000 cubic meters of concrete. All of this work was completed in three years, remarkable progress, considering the technology of the day, comparing very well with the rapid excavation and tunneling methods of the twenty-first century. Big, fast, and deadly—at least 20 lives were lost in construction accidents.

Jan 1, 2007

By J. E. Kulas

Red Dog is a Mississippian to Permian aged sulfide deposit located in the western Brooks Range north of Kotzebue, Alaska. It belongs in the family of black Shale hosted sedimentary exhalite deposits but lacks classic sulfide sedimentary textures. Pervasive silicification, and a significant portion of the mineralization, is replacement in nature. An extensive feeder vein system cuts the footwall and the exhalite package. A Jurassic to cretaceous age compressional event has repeated the ore section through thrust faulting and folding. The orebody contains 77,000,000 metric tons averaging 17.1% Zn, 5.0% Pb and 82 g per metric ton of Ag. Weathering has locally altered the sulfides to sulfates and formed elemental sulfur.

Jan 1, 1992

By L. P. James, W. W. Atkinson

Utah has produced about one billion troy oz. (31.7M tonnes) of silver, more than any U.S. state except Idaho. Several very high grade ore systems, now closed, occur within large polymetallic limestone-hosted districts related to plutonic complexes. These Utah mines fed several major lead smelters for nearly a century. Interaction of magmatic chloride-rich fluids with carbonate rocks localized significant bonanzas within these districts. A low sulfidation state was produced in the fluids by their passage through limestones. The Bingham porphyry mine has also yielded more byproduct silver than other porphyry copper-gold systems. Away from exposed intrusive rocks, some large silver-only systems occur in Mesozoic sandstone and in caldera-related veins in volcano sedimentary rocks. Thick permeable latest-Proterozoic basement meta quartzite sequences present beneath western Utah may have been important, as perhaps they were in the Coeur d’Alene district of Idaho, in providing chloride and silver-rich ore fluids. However, it is clear that specific Tertiary magmatic events played an essential role in the evolution of the Utah silver-rich metallogenic province. The largest silver districts in the state are genetically related to porphyritic plutonic rocks.

Jan 1, 2000

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 W. A. Wilkinson

In creating a surface mine design, a complicated series of events may be required to meet both mining and environmental objectives. Envisioning the mine at every step of the operation can greatly assist the engineer to identify design and operational problems that might otherwise go undetected until the field operations reach the problem. Providing operations a visual progression of the mine ensures that critical designs generated by the engineer are understood and effectively communicated to operations. Providing the plan as electronic data to the surveyors and/or on-board GPS systems can ensure successful implementation of the design. This paper discusses using computer technology to generate a virtual mine plan and strategies to consider when communicating a virtual mine plan through electronic and paper formats.

Jan 1, 2002

By Tim Q. Haldane

The ability to efficiently process lowgrade ores has allowed the Gold Fields Mesquite Mine in Imperial County, CA to expand from a 2.1 Mt/a (2.3 million stpy) rate in 1986 to its present 7.3 Mt/ a (8 million stpy) processing rate. Increased tonnage demands led to the 1989 construction and startup of a dump leach pad to supplement the existing heap leach operation. This resulted in an excellent opportunity to compare the two processes at the same operation. Additional operating costs associated with the crushed ore heaps are justified through enhanced recoveries, even at very low ore grades. Gold Fields' Mesquite Mine is a gold heap leach facility located about 55 km (35 miles) east of Brawley in southeastern California. Five open-pit mines will be developed over the projected life of the property, covering a total area extending to a maximum of 5.5 km (3.4 miles) to the east and west, and 2.4 kin (1.5 miles) to the north and south. Mesquite will process 7.3 Mt (8 million st) of ore and produce more than 6.2 t (200 000 oz) of gold in 1990.

Jan 1, 1990

By D. C. Dahlin, W. K. O’Connor, G. E. Rush, C. A. Summers, S. J. Gerdemann

The Albany Research Center (ARC) conducted studies of mechanical activation by conventional and ultra-fine grinding techniques to enhance olivine reactivity in mineral carbonation reactions. Activated olivine is one of several solid feed materials used at ARC in reactions with carbon dioxide to form carbonate minerals. This paper compares grinding techniques via energy demand data and product characteristics, including particle size distributions, surface areas, full width at half maximum (FWHM) XRD analyses, and particle morphology by SEM analyses. Reactivity was gauged by percent conversion to carbonate in subsequent carbonation tests.

Jan 1, 2004

By R. P. Sloan, A. S. Whitford

In November 1999, CCI's Empire Iron Mining Partnership and MinnovEX Technologies Inc. developed an expert system for advanced control of their Empire IV Grinding Section. Empire IV is comprised of three autogenous Primary Mills and six autogenous Pebble Mills, with a single Pebble Crusher and high pressure Roll Press. The challenges of controlling and optimizing three distinct grinding lines that are inter-woven by a pebble crushing circuit were met with innovative and unique solutions. This paper will detail the approach employed at Empire and will focus on the aspects that make this application unique.

Jan 1, 2001