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By Dave Rogstad

The DART NC-1B Tunnel Project consists of two 5,100 m TBM excavated tunnels, a principal underground station, a partially completed future station, a surface station, and eight associated ventilation shafts and exit tunnels. This paper presents a case history of the project's construction, and will focus on six topics that give this project a unique and unusual history; the TBM excavation, two major differing site conditions, roadheader excavation, polyfiber reinforced shotcrete lining, the NATM design geometry, and a design/build type of contract.

Jan 1, 1995

By Jeff Hussey

Since 1955, Gaspe Mines has produced 150 Mt (165 million st) of ore averaging 0.9% copper. The ore was mined from two open pits and from underground workings. In 1994, four exploration drill holes discovered a buried porphyry/skarn copper-molybdenum (Cu-Mo) deposit at depths of between 1,000 and 1,700 m (3,280 and 5,580 ft) below the top of Porphyry Mountain. The mineralization and alteration associated with the Porphyry Mountain quartz monzonite does not outcrop. Prior to 1997, about 19,500 m (64,000 ft) of drilling in 12 drill holes had outlined 200 Mt (220 million st) grading 0.73% Cu and 0.08% Mo. Mineralization occurs as veins and disseminations of chalcopyrite and molybdenite.

Jan 1, 1998

By C. Botha, M. J. Walls, C. T. O'Connor

The role of copper sulphate in the flotation of pyrite has been studied. A survey of a number of pyrite flotation plants using copper sulphate showed that in correct dosages, it was able to increase both grades and recoveries. This was confirmed in batch tests. Copper sulphate had no significant effect on the rate of adsorption of PNBX onto pyrite. Copper adsorbed irreversibly onto the pyrite when the latter was slurried in a copper sulphate solution. Copper sulphate had a significant effect on the maximum froth height obtained in static three-phase froth tests. Proposals to explain these observations are made.

Jan 1, 1998

By Kathleen S. Smith, Katherine Walton-Day, James F. Ranville

Four different scales of observation were used to evaluate the potential effects of a fluvial tailings deposit on water quality along the flood plain of the upper Arkansas River south of Leadville, Colorado. First, we collected surficial material and subjected it to batch water-leaching test. Second, we excavated and leached an intact eight-inch diameter core. Third, we examined the water quality of the shallow ground water beneath the fluvial tailings deposit, and fourth, we monitored water quality along a 5-km reach of the adjacent Arkansas River. Leaching of surficial samples indicates that there is a reservoir of readily water-soluble material yielding elevated metal concentrations and high acidity. However, there are minimal measurable water quality effects of the fluvial tailings deposit on the adjacent reach of the Arkansas River.

Jan 1, 2000

By R. Pazhianur

Many investigators conducted surface force measurements between hydrophobic surfaces in water, and observed attractive force that was substantially stronger than the van der Waals attractive force. The excess force was appropriately referred to as “hydrophobic force”, for which many different theories have been put forth by numerous investigators. In an earlier publication (Yoon and Ravishankar, 1996), it was suggested that the hydrophobic force maybe due to the interaction between the large dipoles created by the surfactants adsorbing on solid surfaces in patches (or domains). In the present work, a mathematical model has been developed to further elaborate the theory.

Jan 1, 2003

By M. Pantazidou

The wide use of chemical grouts, in combination with increasing environmental awareness, necessitates the evaluation of possible adverse effects if grout constituents may leak in groundwater. Acrylamide-based grouts are of particular interest, since the engineer has to balance the superior properties of these grouts and the known human health impacts of acrylamide. This paper identifies the properties of acrylamide that are required for the evaluation of its fate and transport in the subsurface and presents results of numerical simulations of acrylamide transport for a hypothetical tunneling application.

Jan 1, 2006

By T. S. Golosinski, J. Wolski

Procedures are presented for determining the hourly production rate, mechanical and physical availability, utilization, use of availability, and global performance factors for the bucket wheel excavator (BWE) itself, as well as for the system composed for the BWE, conveyors, and stacker. An example demonstrates the flow of calculations. Using available data from mines that use BWE technology, the ranges of values of the BWE performance factors are presented in tabular form. They can be used as a guide during mine planning as well as to evaluate existing systems.

Jan 1, 1987

By J. M. Barker

Formation of commodity agreements depends mainly on the economic instability and associated mitigation measures inherent in the economic conflict between more developed and less developed nations. Five types of possible agreements exist: futures market, buffer stock, restrictive agreement, multilateral contract, and compensatory finance. Lack of market separation between sulfur consumers and producers coupled with large world production and highly concentrated export production in theory suggest a restrictive agreement as most likely. In practice, stockpiling of sulfur, an informal buffer stock, as done in Canada and perhaps the Middle East, has been the main sulfur price-supporting mechanism in the past two decades. No commodity agreements involving sulfur now exist except for multilateral contracts. Sulfur agreements apparently have existed rarely, if at all, in the past. Law (1975) refers to sulfur as one of a group of commodities where "there have been additional control efforts of various types." Clearly, sulfur was a candidate, at least conceptually in the past, for some form of commodity agreement. The following discussion centers on the world sulfur market from 1976 to 1985 in this context.

Jan 1, 1987

By M. E. Poad, W. G. Pariseau, M. A. Laurenti

In 1986, a cooperative effort by Homestake Mining Co., the US Bureau of Mines and the University of Utah was initiated to determine shaft stability while recovering high-grade ore in a nearby pillar. Premining finite element simulations indicated the shaft would remain in elastic ground. Six years have elapsed and, despite some initial concern during the first lifts, it appears that the bulk of the original reserve will he safely and profitably recovered. An integrated application of rock mechanics tools from laboratory testing through numerical modeling to mine measurements and observations contributed substantially to the operational success of the project.

Jan 1, 1996

By Edward S. Plotkin, Thames F. Peyton, Gary A. Almeraris

This paper describes high speed tunneling by drilling and blasting in a heavily populated urban area. The project consists primarily of mining 2500 m (8237 ft.) of tunnel through mica schist, excavating three shafts approximately 200 m (650 ft.) each and concreting lining 5300 m (17,400 ft.) of 7.34 m (24 ft.) inside diameter tunnel. The techniques developed and equipment utilized to ensure a high rate of tunneling advance are described. Extensive planning and good communications were especially essential in maintaining production on this project since tunnel mining, tunnel concreting, and shaft excavation all proceeded simultaneously from one common work shaft and a single heading.

Jan 1, 1985

By Janine L. Beazley, James H. Kyle

The effects of pH, pH modifier (lime or caustic soda) and cyanide on the pulp rheology of a number of ore types ranging from highly siliceous to highly kaolinitic has been investigated. All experiments were performed in fresh water at solids concentrations of 25 and 45% solids and in the pH range 6 to 11. The kaolinitic ores exhibited greater changes in rheology with pH and calcium ion concentration than did the siliceous ores.

Jan 1, 1989

By Betty L. Gibbs

Computer software for mining applications has been in development since before 1970. These packages cover tasks from exploration data management through final reclamation planning. These programs were originally written in Fortran and have evolved into colorful, user-friendly packages. Programs that produced printed symbol maps now show color, three-dimensional image of an ore deposit on a computer screen. Pictures can be rotated and looked at it from all directions and layers can be peeled off to show other parts of a model. Computer users have also evolved. In the early Fortran days, users had to learn computer operating systems, have someone punch data cards, set up run files and wait a day or so to find out if there was one little mistake somewhere that caused the program not to run. With today's technology, users sit at their desks in the office, key in some data, read other data from digital files and build a model within days, rather than weeks or months.

Jan 1, 1999

By Charles F. Herbert

Placer mining in Alaska had a desultory inception at Sumdum in 1869 and, during the years 1880 to 1896, received thin nourishment from the readily exhausted gold placers at Juneau and the longer- lived deposits in the Circle, Fortymile, and Rampart Districts. Finally, in 1897, the great Klondike discovery in Canada's Yukon Territory brought thousands of gold seekers to the Far North. These men, in successive, far-reaching gold rushes, found the large, rich gold deposits at Nome, Fairbanks, and Iditarod, as well as many smaller placers. The hectic rushes during the years from 1898 to 19 10 were comprised of hundreds, sometimes thousands, of "stampeders," as they were called. Since very many Alaskan creeks, from the crest of the Brooks Range in the north to the Pacific Ocean in the south, carry at least a few flakes of gold, there was ample seed to start a new stampede. Of the 100s of reported "strikes," nearly 50 became more or less important placer mining districts; by 1910 they had produced about 184.2 fine Mg (6.5 million fine oz) of gold; the all- time peak production year was 1906. A few of the miners and prospectors prospered, but the total value of all gold produced failed, by a wide margin, to cover the aggregate costs incurred by them in the undeveloped Territory of Alaska. On the other hand, the traders with their readily salable supplies of food, tools, and hardware and the freighters with their teams of dogs or horses and boats of all kinds profited throughout the era of stampede.

Jan 1, 1991

By A. D. Davis, C. J. Webb

Brohm Mining Company's Gilt Edge Mine in the northern Black Hills was a surface heap-leach operation that was active from the 1980s until 1999. Financing problems and acid drainage concerns at the mine were reported in the late 1990s. In February of 1999 the Governor of South Dakota announced plans to request the U.S. Environmental Protection Agency to help clean up acidic water at the mine and reclaim the site. In July 1999 the parent company of Brohm, Dakota Mining, filed for bankruptcy in Canada. Because of the bankruptcy and environmental problems, the State of South Dakota intervened and began water treatment. The mine was declared a Superfund site in 2000. Hydrologic issues include the potential for acidic drainage from the site. The mine is at the headwaters of Strawberry Creek, which drains into Bear Butte Creek. About four miles downstream, Bear Butte Creek loses its discharge to swallow holes in the karstic Madison Limestone aquifer, a regionally extensive and valuable ground-water reservoir. Other concerns at the site include treatment of acidic water in mine pits and a waste rock dump.

Jan 1, 2002

By S. K. Kawatra, R. A. Seitz

Nonpolar hydrocarbon oils are commonly used in the flotation of minerals to fulfill a number of roles. These roles include reducing overall reagent costs by replacing part of the collector addition, improving coarse particle recovery without reducing selectivity, as well as several others. This paper will cover the types of oils which are available, their physical and chemical characteristics, and the effect of these characteristics on the function of hydrocarbon oils in flotation. In addition, techniques for improving the behavior of oils will be discussed.

Jan 1, 1986

By Keith G. Wallace, Daniel J. Brunner

The traditional approach to mine ventilation planning involved making estimates of airflows, including leakage routes, and summing the corresponding pressure drops along consecutive paths in order to determine the fan pressures required. This methodology changed completely with the availability of computers. Mainframe digital computers began to be used for mine ventilation network analysis in the mid-1960's. Their use spread rapidly throughout the world in the 1970's. Mainframe machines were employed owing to the need for high speed numerical procedures and substantial storage requirements. However, during the past decade, the growing availability of low cost but powerful microcomputers has allowed the development of net- work analysis programs that can handle ventilation systems of hundreds of branches, and which can produce results within a few minutes. This paper discusses recent advances in software and hardware development specific to mine ventilation planning. Software developments include interactive data and output manipulation, graphical representation of output, internal checks on input parameters to preset ranges and subroutines which calculate the gas distribution throughout the network from known gas sources. Hardware advances have led to significant increases in memory to facilitate the analysis of large ventilation models, math co-processor chips which greatly shorten run times, and plotter hardware for graphical output displays. Recent software developments make it possible to graphically display output on printers faster than on standard plotters.

Jan 1, 1989

By A. G. Journel

Few Earth Scientists realize fully the assumptions they are making, willing or not, when pooling into a same histogram data coming from different locations and considering such histogram as an estimate of a probabilistic distribution. First they need the hypothesis of stationarity in space; second the presence of spatial auto-correlations implies that data be unequally weighted according to their relative locations and the degree of spatial continuity of the underlying phenomenon. The novel technique of indicator kriging allows construction of local or global histogram which can be considered as unbiased estimators of precisely defined probabilistic distributions, full account being given to the underlying continuity. Such estimates of local distributions can be used in mine planning for estimation of local recoverable reserves.

Jan 1, 1982

By R. J. Gochin, M. A. Diaz, M. L. Court

Single impact breakage tests have been carried out on samples of alumina in carefully controlled atmospheres consisting solely of nitrogen gas and water vapour. The results indicate a statistically significant increase in the surface area of the progeny particles as relative humidity rose to 50%. The majority of this increase was found to occur under conditions when adsorption was a monolayer or less. The results are consistent with the theory of surfactant-induced strength reduction of materials proposed by Rehbinder and Westwood. There are important implications where single impact tests are used as part of a design methodology for comminution machines. In most procedures relative humidity has not been a controlled variable.

Jan 1, 1995

By Jim Jonas

The Berkeley pit-lake was sampled during two seasons, fall 1997 and spring 1998, from the surface to the bottom. Various parameters were measured to determine what effect the seasons had on the water column. It was determined that a seasonal turnover did occur between the fall and the spring sampling; however, the depth of mixing due to turnover could not be established. Trends were observed which suggested that microbial activity was altering the iron speciation at depth, and subsequently masking the extent of mixing. Various trace metals were removed from the surface water by either co-precipitation with schwertmannite or adsorption.

Jan 1, 2000

By R. Brough, T. K. Moller

There are differences in design aspects between steel and rubber linings in grinding mills. This paper describes the basic design rules for rubber liners for different grinding applications. When converting a mill from steel to rubber liners, the design must be changed from such familiar steel liner shapes as wedge bars and plates, wave liners, and ship-lap, to take advantage of the characteristics of rubber. Very little of the knowledge of the wear properties of steel can be used for the design of rubber mill liners.

Jan 1, 1990