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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 D. Simon

This paper studies the effect of binder type and content on the early age development of cemented paste backfill (CPB). The early age development of the mixtures is analyzed using scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDX). These tests show that the early age development of CPB is sensitive to changes in the paste composition. The properties of the CPB depend on the cement content and hydration time. The quantity of hydration products increases with hydration time for all of the mixtures containing cement. However, the high cement content pastes (at least 50% PC) exhibit complete coverage of the PC grains and mine tailings by C-S-H, while the low cement content paste shows scattered coverage of the PC grains and mine tailings and a higher void ratio.

May 1, 2007

By Daniel N. Adams

The University Link project extends Seattle?s light rail from downtown to University of Washington (UW). It includes 5.0 kilometers (3.15 miles) of twin-bored, 6.4 meters (21 feet) excavated diameter tunnels, and two cut-and-cover stations. The Capitol Hill Station (CHS) requires an excavation 170.7 meters (560 feet) long, 22.6 meters (74 feet) wide, and 22.9 meters (75 feet) deep. The University of Washington Station (UWS) requires an excavation of about 238.4 meters (782 feet) long, 21.3 meters (70 feet) wide, and 33.5 meters (110 feet) deep. The project is within the glacially diverse soils of the Puget Sound region, below groundwater. This paper highlights major station and tunnel design elements, including the approach to support of excavation at both station boxes, and the site staging requirements.

Jan 1, 2008

Australia's iron ore industry is entering a challenging period with the development of new orebodies, the introduction of new products and the push for further downstream processing. In addition, the recent price reductions for iron ore exports have intensified the focus on reducing capital and operating costs. To assist in these areas, CSIRO is expanding its research capabilities, including the incorporation into CSIRO of the Mineral Processing Laboratories in Perth, which were previously managed by the WA Department of Minerals and Energy. In addition, a large part of the $24.4 million expansion of CSIRO's Pinjarra Hills laboratories in Brisbane will be devoted to enhancing iron ore processing research, providing purpose built laboratories and large process bays.

Jan 1, 1999

The Greymouth Coal field is situated on the West Coast of New Zealand's South Island and has been mined for coal for more than 120 years. The area covered in this paper is within the Rapahoe Sector of this field and contains >200 million tonnes of low ash, low sulphur, bituminous rank coal. Paper No 6, presented to the 19th Annual Conference of the New Zealand Branch of The Australasian Institute of Mining and Metallurgy in Christchurch in August 1985 by R G Bowman, explained 'A Geologist's View' of the 'Economic Potential of the Greymouth Coalfield', and describes previous geological assessments of the Rapahoe Sector.

Jan 1, 1989

By Barun Gorain, Andy Stradling

"The traditional metallurgical scale-up techniques for flotation plants are based on lumped flotation rate constants, dimensionless hydrodynamic numbers and the use of safety factors. Once the plant has been designed, the flotation principles that govern scale-up play almost no role in the optimisation of the circuit to meet its metallurgical targets. This deficiency can potentially lead to a plant design incapable of meeting its targets, especially when circuits incorporate large flotation cells. This paper demonstrates the application of the k = PSbRf model in providing a suitable framework for flotation modelling, scale-up and circuit optimisation, thus presenting an integrated approach to the problem. Studies were conducted at Teck Cominco’s Red Dog concentrator to characterise cell hydrodynamics, gas dispersion properties, fioth flow behaviour, entrainment and ore floatability to obtain the key data necessary to develop a model for the flotation circuit. The findings of these studies are presented in this paper, which provide valuable insights into the modelling and optimisation of the Red Dog flotation circuit.INTRODUCTIONThe traditional methodology for flotation scale-up and plant design is based on the rule-of-thumb with safety factors, dimensionless hydrodynamic group similitude considerations, etc. With the recent trend towards larger flotation cells with volumes of 150 m3 and greater in concentrators, the problem of scale-up has become even more acute. The scale-up factors that may have been tolerated on smaller cells are not applicable to larger cells. The transportation of froth in these large cells adds further complexity to the problem. Arbiter et al. (1980) foresaw this problem and pointed out that if scale-up were attempted by rule-of-thumb and trial-and-error, then the probability of failure would increase with scale. This problem is confounded by the fact that the design and scale-up considerations used for a new flotation circuit play almost no role in optimisation of the circuit to meet its metallurgical target. This results in a plant design incapable of meeting its metallurgical targets. There have been several instances where new concentrators have required significant circuit modifications and additional capacity to achieve design targets."

Jan 1, 2002

By Theresa M. Bodus

The strength of roof shales is, in part, a function of the preferred orientation of clay minerals within them. Therefore, analysis of clay fabric under both air-dried and hydrated conditions should be helpful in understanding roof shale failure. Core samples were collected from the Energy, Anna, and Lawson shales, which are locally present as roof shales of the Herrin No. 6 coal of southern Illinois. The Clay Fabric Index (CFI) was measured for thirty core samples, using X-ray diffractomtry, to investigate the relationship between clay fabric and roof collapse in coal mines. Greater CFI values indicate a weaker preferred orientation among clay minerals, which generally results in a weaker inter-grain bond. Average CFI values for air-dried samples were: 0.15 for Anna shale; 0.20 for Energy shale; and 0.37 for Lawson shale, .After the introduction of water, average CFI values increased to: 0.28 for Anna shale; 0.22 for Energy shale; and 0.43 for Lawson shale. The laboratory results indicate the following: [l] under air-dried conditions, Anna shale is the most stable, followed by Energy and Lawson shales; and 121 under hydrous (mine) conditions, Energy shale is the most stable, followed by Anna and Lawson shales. In mine environments where roof failures involving Energy shale have occurred, planar trends delineated by a relatively high density of small (0.2-4 cm diameter) iron concretions have been reported along the failure surface. Radial cracks have been observed around unsealed anchor bolt holes in the Anna shale. Instability of the Lawson shale is ubiquitous in coal mines. In the laboratory, similar physical changes were noted in the shale samples after the introduction of water, including [l] increased hydration around the perimeter of iron concretions in Energy shale, [2] radial extension cracks in Anna shale, and 131 extreme slaking of Lawson shale. Measured increases in the CFI reflect the observed physical changes of the samples upon the introduction of water, which probably reflect changes in strength that may result in roof failures in hydrated mine environments.

Jan 1, 1989

By Charles L. Kimbell

Although virtually every available indicator of world mineral industry activity demonstrated a gain in 1983 relative to the 2 very poor years of 1981 and 1982, the overall prospects for future years seemed far from bright. There were significant upturns in the quantity and value of mineral commodities produced, traded, and consumed in 1983, and many nonfuel mineral prices advanced, although the price advances in current dollars in most instances barely compensated for inflation. The pattern of investment in exploration and development of new mining ventures and new plant construction reflected virtual industry-wide concern that substantial upturns in demand for mineral commodities in the near future were unlikely, at least for most large volume products. The world oil glut continued despite cutbacks in production, and substantial stocks of many other mineral commodities mitigated against growth in total productive capacity, at least among market economy nations. In these countries, development activity at both mines and plants was confined largely to programs aimed at substituting new, more efficient installations for old, uneconomic or marginally economic plants. Among the centrally planned economy countries, the pattern was somewhat different on the whole, but even there, growth in total productive capacity was evidently somewhat restrained, although it seemed questionable whether the restraint was a function of intentional planning or simply an inability to accomplish planned programs on schedule. International political events, particularly the Iran-Iraq war and the unstable situation in the eastern Mediterranean countries (Lebanon, Israel, and Syria), continued to adversely affect mineral industry activities in those areas. Similarly, the internal and international conflicts in Central America negatively influenced mineral industry operations there. In Afghanistan, it appeared that there was some upturn in the very modest mineral industry operations, but industry activities there undoubtedly continued to be affected by confrontations between the Soviets and the local citizenry.

Jan 1, 1985

By Manish Uttarwar, Rajendra Yerpude

India is the third largest producer of coal and the fourth largest in terms of coal reserves in the world. However, new research quite ironically projects that despite the continuing growth in domestic coal production, the country’s exploding economic growth will position it to be the biggest coal importer by 2020. India’s inability to meet the domestic coal demand is mainly attributed to low rate of production, increasing stripping ratio, non use of appropriate technology etc. of coal mining operations here. Presently Indian surface mines which have to shoulder the onerous responsibility of augmenting the coal extraction rate at an even brisker pace are mulling bigger, better and more efficient operations ensuring commensurate rise in stripping work as well. This mammoth task can be accomplished only by deploying smart technologies. In this perspective, cast blasting of overburden emerges on the horizon as a promising alternative for enhancement of the production and productivity of Indian open-pit coal mines.

Jan 1, 2009

By Terry S. Cory

This report covers magnetic field strength measurements vs range and frequency In low-medium coal mines. Both quasi-conductor-free and conductor-proximity areas were Investigated. The program covered 5 mines, 4 seams, 6 measurement sets, and 3 geographic areas, The results have been summarized In terms of maximum communication range expected per seam and noise condition. Scatter gain Is further explored as a simple measure of energy coupled to conductors.

Jan 1, 1978

By J. E. Chilton, T. Mal

Methane monitoring at the mine face is essential to assure a safe work environment in underground coal mines. Machine-mounted methane monitors must be used to continuously monitor methane levels during mining. Monitors used on mining machines must be approved by MSHA and properly maintained to provide protection for workers (30 CFR 75.342). To provide protection the instrument must give accurate readings of current methane levels. Accuracy is maintained by calibrating the instrument with a standard gas at least once every 31 days. Instrument “response time” determines how quickly measurements will change to reflect current concentrations. At present there are no criteria for measuring the response time for a ma-chine-mounted methane monitor while underground. This study examined a procedure for measuring the response time of a machine-mounted methane monitor. Response times were measured using methanometers obtained from three different manufacturers. The effects of the measurement technique and methanometer sensor head design on response time measurements are investigated. Techniques for reducing variation in response time measurements are discussed.

By Jon C. Volkwein

In This Chapter [Instruments for measuring dust How to calculate the amount of dust from a source How to get a valid concentration measurement Sampling to assess control technology effectiveness] When there is more than one source of dust, sampling may be required to find which dust sources are most significant. Then, efforts to reduce dust can be concentrated where they will have the most impact. This chapter explains how to perform dust source sampling. It describes two kinds of instruments that are available and discusses their limitations. It explains how environmental variables such as concentration gradients, dust dilution, and production changes can impact dust measurements. It also suggests practical ways to improve the validity of dust source measurements under adverse conditions, such as high-velocity airflow or the presence of water mist in the air. [Dust source sampling at coal mine longwalls and at tunnels is more complicated. Chapters 3 and 7 have more information on sampling in those circumstances.] TWO KINDS OF INSTRUMENTS FOR MEASURING DUST Gravimetric samplers. The conventional gravimetric sampler is a good device for measuring dust because it is the instrument used for compliance measurements. This dust sampler consists of an air pump, a small cyclone that separates out the respirable size fraction of the dust cloud, and a filter to collect the respirable dust. In coal mines, the Mine Safety and Health Administration (MSHA)-approved gravimetric sampler uses a 10-mm Dorr-Oliver cyclone operating at an airflow of 2.0 L/min [30 CFR78 74 (2002)]. A correction factor of 1.38 is applied to make the results consistent with the U.K. MRE sampler, the instrument on which the 2.0 mg/m3 coal dust standard is based.

Jan 6, 2003

By J. R. Thoenen

[For several years the Bureau of Mines conducted tests on ground vibration t emanating from quarry blasting in an effort to determine an index of destruction for different types of structures. Results of these studies have been published in four Bureau of Mines Reports of Invitations as well as in several articles in the trade and technical press.5/ The first paper (3)6/ discussed the subject in general and gave results s of a few blasting records. Some tentative theories also were advanced. The second paper (4) discussed results s of records made from blasting in a number of quarries.]

Jan 1, 1940

By Chris Fleming, John R. Goode, James Brown

"Data will be produced from two uranium feasibility studies that were conducted in 2008, both involving uranium recovery from leached slurry by resin-in-pulp (RIP) with strong base resins. Excellent metallurgical results were produced in RIP pilot plants in both studies, and the loaded resins were eluted with strong sulphuric acid and recycled to RIP in an integrated process. Resin losses by either abrasion or mechanical breakage were immeasurably low.Metallurgical results from these two campaigns will be presented, along with an economic analysis of RIP versus the alternative process of CCD or filtration and solvent extraction.INTRODUCTIONThe recovery of uranium directly from pulp with strong base resins in RIP contactors was practiced commercially in the USA in the 1960s, but the process never established itself as a viable alternative to solid/liquid separation and solvent extraction. This was due mainly to the necessity to do a sand-slime separation partially resulting from the unavailability of coarse resin beads, inadequacies in the design of the RIP contactors and screens to separate resin from pulp, as well as problems with the strength and durability of resins in agitated pulps.There have been significant advances in the last 30 years in each of these areas. All the commercial resin manufacturers are now producing very tough, durable, strong base resins, and are manufacturing them in a large bead size that is better suited to RIP applications. In addition, with the emergence and wide spread implementation of the carbon in pulp process in the gold industry in the 1980s, many innovative techniques for preparing leached slurries and separating carbon from pulp have become firmly established. These techniques have proven to be equally applicable to resin separation from pulps in RIP contactors."

Jan 1, 2010

By H. Sahay

This paper summarizes the history and ore-grade statistics of mining the Ming orebody, and then details the mining methods. Included are raising, stoping, drilling and blasting techniques. Particular attention is paid to ground support, ventilation and pumping requirements.

Jan 1, 1979

By Steven R. Munts

The U.S. Bureau of Mines investigated mines, prospects, and mineralized areas in the South Providence Wilderness Study Area (WSA) in 1982. No mines are currently operating in the WSA, however, the Golden Gift Mine in the southeastern part of the WSA produced $6,800 1/ worth of gold and silver and five mines adjacent to the east boundary of the WSA had a total production of about $3,500,000 1/ in gold, silver, lead, and copper. There is no recorded placer gold production. Over 350 lode and placer mining claims are in and immediately adjacent to the WSA. Of these, 74 were actively held (1982) and at least one area, which is partly within the northeast portion of the WSA, was being actively explored by private industry in 1982. Adjacent to the southeastern border of the WSA the Big Horn Mine contains an estimated 200,000 tons of indicated and inferred marginal reserves averaging 0.25 oz/ton gold; and the Hidden Hill Mine has 550 tons of subeconomic resources averaging 0.60 oz/ton gold. An additional 11,000 tons of marginally economic gold-bearing dump reserves average 0.17 oz/ton gold at the Bighorn, Hidden Hill, and the Buena Vista Mines and the Midas Touch Prospect. Sample analyses indicate eight mines and prospects in, and five adjacent to the WSA may have additional gold-silver-lead-copper vein-type resources. Five of these prospect areas may have a disseminated gold resource and one may have gold resources in a skarn. One prospect may have a porphyry-type copper-molybdenum resource. Although gold placer claims were filed sporadically throughout the WSA, none appears to have placer gold resources. Likelihood for mining is greatest at the Big Horn Mine; if a mill is built there, it could process Big Horn Mine ore, ore from the Hidden Hill Mine, and gold-bearing dumps at the Big Horn, Hidden Hill, and Buena Vista Mines and the Midas Touch Prospect. All of these resources are adjacent to the WSA; however, their development would increase likelihood for development of resources in the WSA. Two major fault zones (the Hidden Hill, and the Big Horn) appear to have controlled the mineralization at many of the prospects and mines. All of the prospects or mines with vein-type occurrences and resources are on or adjacent to one of these fault zones. Veins throughout the eastern half of the WSA contain various amounts of gold, silver, and copper; only veins near the Big Horn Mine and in the northeastern corner of the WSA contain lead. Some veins are as thick as 6 ft, are traceable intermittently for over 2 mi along strike, are sporadically mineralized, are encased in prophylitic, argillic, and phyllic altered host rock, contain pyrite, chalcopyrite, galena, specularite, barite, or fluorite, and display multiple stages of quartz veining and (or) brecciation. Sample analyses at five prospects (map nos. 3, 18, 23, 24, and 31) indicate they may have disseminated gold resources. To date no oil or gas has been discovered within the WSA. However, some oil and gas leases are currently (August 1982) held within this study area.

Jan 1, 1984

By Muhannad T. Suleiman

Temperatures below freezing significantly enhance the soil shear strength and stiffness and to a lesser extent increase the compressive strength of concrete as well as the yield and ultimate strength of reinforcing steel. Consequently, the lateral load resistance of bridge columns supported by drilled shafts becomes dependent on seasonal weather conditions. To investigate the effects of seasonal freezing on the behavior of bridge columns supported by drilled shafts, large-scale field lateral load tests were conducted at 23°C (73.4°F) and -10°C (14°F) on two identical units at an field test site, which consisted of glacial till soil classified as low plastic clay. The bridge column-drilled shaft systems were subjected to cyclic lateral load with the maximum lateral column top displacements reaching approximately ±30 cm (±11.8 in.). The soil at the test site was characterized at different temperatures using unconfined compression tests in the laboratory as well as in-situ Cone Penetration and Pressuremeter Tests. Using these test results, the lateral load behavior of the column-drilled shaft systems were analyzed utilizing numerical models that consisted of beam elements representing the concrete column and the shaft and lateral springs representing nonlinear p-y response of soil. This paper focuses on comparing the calculated responses of test units with different p-y curves that were developed for the soil near the ground surface using the laboratory and in-situ tests. From the experimental study, the response of the unit tested at -10°C (14°F) was found to show 44% increase in lateral force resistance and 0.84 m (2.76 ft) upward shift of the maximum moment location compared to the response of the identical unit tested at 23°C (73.4°F). Theoretical behavior that included the temperature effects on soil, concrete and steel properties provided good correlation with the measured responses when the soil near the ground surface was modeled using the unconfined compression test or the Cone Penetration Test data, but not the Pressuremeter test data.

Jan 1, 2006

The project to reopen the Tasmania Mine has centred around efforts to reopen the Hart Shaft to access the high grade reef remaining below the old workings, which extend down to 457 in. Efforts in 1982 and 1987 were frustrated by unstable clay ground around the shaft, which resulted in significant subsidence of the shaft collar and lining. A successful program has since been implemented to solve the problems, stabilize the collar and recover the upper shaft which had collapsed down to 90 m.

Jan 1, 1989

By Martin Herrenknecht

After the successful breakthrough at the end of 2006 of both TBMs into the multifunctional site Faido (MFS), in the middle of 2007 the two tunnel boring machines resumed the 12 km long section between Faido and Sedrun. In the roughly a 10 month interval both approximately 465 m long tunnel boring machines were partly dismantled, pushed through the 2.5 km long MFS, rebuilt for the new larger diameter of 9.5 m and reassembled to be ready for operation. In the rebuilding phase, improvements were made to the equipment, especially as a result of experience gained from the previous 14 km long drive in the section Bodio and taking into account the latest information regarding the upcoming 14 km section Faido. Both TBM drives are currently in the rock formations of the Lucomagno gneiss, which stretch over a section of 3.5 km from the MFS Faido to the predicted Piora Syncline. This section is divided into two fold axes of the Chièra Synform, where the Lucomagno gneiss pass from a sub-horizontal into vertical bedding. The drives, with current rock overburdens exceeding 1,500 m and, as known from the excavation phase of the MFS, in part highly disturbed rock formations, are characterized by the locally intense rock squeezing conditions with large convergences in the vicinity of the driving TBM as well as backwards due to the interaction of the two drives. High expenditure for the support measures, reduced driving performances together with extensive extra work associated with deadlines and increased costs are the result. In the paper the previous experience with the TBM drives in the section Faido and the challenges still awaiting us are presented and discussed.

By J. R. Thoenen

[For several years the Bureau of Mines has conducted tests on ground vibration emanating from quarry blasting in an effort to determine Fin index of destruction for different types of structures. Results of these studies have been published in four Bureau of Mines Reports of Investigations as well as in several articles in the trade and technical press.5/ The first paper (3)6/ discussed the subject in general and gave results s of a few blasting records. Some tentative theories also were advanced. The second paper (4) discussed results s of records made from blasting in a number of quarries.]

Jan 1, 1940