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By Leon C. Botham

?? Review of Requirements ?? Components of Modeling ?? Water Management ?? Tailings Management ?? Primarily a water management problem ?? Solids relatively easily contained ?? Process flows and runoff a continuous stream over life of mine ?? Need to allow this to safely happen over wide range of conditions

May 1, 2008

By G. C. Milligan

"A regional mapping program, conducted by the Nova Scotia Department of Mines, has shown that the George River Group of pre-Middle Cambrian rocks consists of a wide range of sedimentary and volcanic rocks, intruded by syenite, granite, granodiorite and lesser amounts of gabbro and diorite. Together, these rocks support the high ground of northern Cape Breton Island. Over this large area, the metamorphic grade ranges from low to extremely high.The rocks were folded prior to emplacement of the intrusions in Middle Cambrian time, and there was also post-Mississippian disturbance and faulting, but the structural history and pattern are still only imperfectly understood.Sulphide mineralization is known at Meat Cove, Lime Hill and in a number of smaller deposits. The most Cavour-able host rocks appear to be magnesian Iimestone, or schists derived from shales. Ail known sulphide bodies have an associated halo of retrograde metamorphism; in some cases, this is extensive enough to be used as a prospecting aidA vein of nickel-bearing sulphides has recently been re-discovered in the former gold mine at Second Gold Brook-an association which appears to be unique."

Jan 1, 1971

By M. Pesowski

"Certain environmental problems can substantially alter the physical properties of the subsurface. In such cases, geophysical methods can be used to map the distribution of subsurface contamination or buried wastes prior to drilling or sampling. For example, inorganic contamination by acids, bases, salts, or metallic ions can be detected by instruments that measure ground conductivity; metallic objects such as buried drums, pipelines, etc. can be located by magnetic survey, and radioactive mine waste can be mapped by radiometric techniques. Geophysical methods can also be used to characterize site geology. If carried out prior to development, they can assist in identifying areas of high- and low permeability and sources of natural contamination. The methods can also be used to establish baseline values and to locate stable areas for development of environmentally sensitive facilities. Application of geophysical methods to environmental problems is illustrated with examples from base-metal mines, uranium operations, and potash and oil-sands operations. Particular attention is given to the problem of acid mine drainage. =IntroductionGeophysical methods have been used for many years by the mining industry in exploration and geotechnical investigations. The basic techniques for mapping variations in physical properties of the subsurface have been adapted to meet the special needs of resource exploration and development in the coal, potash , oil sands, industrial minerals, precious metals, and base-metal industries. Now the mining industry is facing another challenge: to operate the mining cycle, from discovery to closure, with minimum impact on the environment. This involves the rehabilitation of abandoned mining sites, the minimization and effective containment of pollutants at operating and developing sites, and the longterm containment and monitoring of sites after mine closures.Some of the most difficult aspects of environmental control and monitoring relate to the location of buried waste and contaminated fluids in the subsurface. As in the search for buried ore deposits or in geotechnical investigations, geophysics can be a valuable aid in subsur face environmental investigations. Investigations can be remedial , involving the location or monitoring of existing problems, or preventative, where problem areas are identified or background values are established before site development. In either case, geophysical methods should not be considered as a substitute for drilling. Geophysical interpretations in general do not provide the detail required for a complete environmental or geotechnical investigation. They are most useful as rapid reconnaissance methods for targeting subsequent drilling or for interpreting subsurface condit ions away from drill holes. Table I lists the common geophysical methods and the physical properties to which they are sensitive."

Jan 1, 1993

By Sukumar Bandopadhyay, Arunapuram Sundararajan

"Unique production and environmental problems are associated with multiple seam mining where dragfines are used for overburden and interburden removal. On the production side, the problems are decreased dragfine efficiency in chopdown operations, the general need for spoil rehandle, complications in sequencing stripping and coal handling operations, and potential stability problems in highly stacked spoil. Many variations of dragline methods have been reported in the literature to encounter these problems. Because of the physical properties and peculiar hydrology of sub-arctic region mining of multiple seams in such areas probably could not be done with the methods used in temperate regions.The properties of thawed material would make spoil hard to place in a stable manner and thus would influence the mini sequence. For instance, multiple seam mining which requires some rehandling of spoil and prolonged exposure of overburden and interburden material might be precluded by the instability of thawed spoil and therefore mining techniques have to be modified. Since the deployment and operation of a dragline in modes different from conventional schemes will affect productivity, it will be necessary to study the effects on production of changing the dragfine operational schemes. This paper presents a heuristic simulation model of multi-seam dragline operation of a sub-arctic mine that can be used to analyze the handling of overburden and detailed study of the dragfine performance."

Jan 1, 1986

By Sarah R. Hindle

Carbon capture and storage has jumped to the forefront of climate change mitigation efforts for its capacity to sequester large amounts of carbon. Mineral carbonation is one prominent option, mimicking and accelerating the natural weathering process of certain silicate minerals. This has the ability to produce stable carbonate minerals that can store carbon on geologic time scales with little to no risk of leakage. Commercialization of this process is ideally suited for integration into the proposed mining operations at the Turnagain Nickel site in Northern BC. This is due to the abundant supply of suitable ultramafic feedstock material, as well as the economic benefit of sharing costs while reducing net emissions and bringing value to otherwise valueless and costly waste rock. While studies have shown this process to be technologically viable on a laboratory scale, assessing the economic and financial viability of such a process on an industrial scale is necessary. An evaluation of the financial feasibility of integrating mineral carbonation into the mining cycle at Turnagain under a proposed cap-and-trade system is presented.

May 1, 2010

By V. Casaletto, L. Widdifield

"Equipment capable of higher production requires more sophisticated maintenance programs. Reduction in fleet size through use of modern technology requires higher utilization and greater availability.Caterpillar's maintenance control system program will display the capabilities of computer technology in a maintenance environment. Utilizing such resources will provide increased availability, lower inventory requirements, fewer last minute disasters, and lower cost per ton for maintenance. High production from premium quality equipment can only be realized by good planning and care, executed by maintenance and operating personnel acting cooperatively.IntroductionAccurate information is the key to accurate decision making. In today' s competitive industry, mines' teeter on the brink between profit and loss. Their survival will be predicated on their ability to retrieve, analyze, and formulate accurate information regarding the operating costs of mobile equipment. This paper deals with the impact of managing equipment operating costs and introduces a computerized control system designed for monitoring and controlling these costs.Caterpillar has produced several computerized modelling programs designed at taking the guesswork out of equipment selection and management. The most basic of these is Equipment Investment Analysis (E.LA.). This model compares two or more alternatives over the projected life of the machine. It deals with comparisons in the owning and operating costs of equipment, as well as, their productivity over a specified period of time.In order for a computer model to be credible as a decision making tool, it must be simple to use and the results measurable and accountable . Caterpillar has introduced several computer models to assist the industry in selecting and managing an equipment fleet. These programs allow the user to predict and monitor the operating costs and production capability of mobile equipment. They are often used in the machine selection process to select equipment which best suits a mine's long-term cost per tonne objectives. After the optimum selection is made, Caterpillar's Maintenance Control System provides an efficient management tool to monitor and verify the data used in the selection model."

Jan 1, 1992

By Z. Bibak, S. Banisi, A. Ghasemi, E. Nematollahi

"The major importance of liners in grinding is their role in providing an appropriate trajectory for the charge. Since it is not possible to study the charge movement by direct observation in operating industrial mills, this task is accomplished by physical (laboratory), and/or, mathematical (software) methods. Because of the high cost and a longer time required for a physical analysis, mathematical simulations have become more common. Simulation of the effect of liner shape on the charge movement has provided a means to select a proper design based on the operational objectives and conditions. Furthermore, the liner shape changes due to wear and impact during operation, which will influence the charge trajectory. This adds more of an incentive to use simulation. These changes in liner could be predicted through liner profile measurements during operation and/or simulation. In this research, an inhouse developed DEM software called KMPCDEM © was used to simulate the charge movement in industrial plant SAG mills. A geometrical method of implementing the shell liners on SAG mills at the Sarcheshmeh (9.75×4.87 m) and the Gole-E-Ghohar (9×2.05 m) operations facilitated the software simulation. Point by point implementation of the measurements of liner profiles of these mills enabled the study to trend the change in the charge movement as the liners wear. Comparison of the simulation to a laboratory mill (1 m diameter) showed that the difference between the measured and predicted charge impact point, shoulder angle and toe angle were 6, 4 and 3°, respectively.INTRODUCTIONComminution is the most energy intensive operation constituting the major portion of operating and capital costs of a mineral processing plant. In the last decade, a vast number of research was aimed at studying various aspects of grinding with the aim of performance improvements (Davis, 1919; Mishra & Rajamani, 1990; kalala, Breetzke, & Moys, 2008). Mill liners transfer the input power to the charge and play a significant role in affecting the motion of the charge (Mclvor, 1983; Mishra & Rajamani, 1990; Radziszewski, 1997; Van Nierop, Glover, Hinde, & Moys, 2001; kalala et al., 2008). Lifters are usually used with mill liners to extend their life and to enhance the grinding and impact breakage efficiency. Mill lifters are used to raise the grinding media and ore to transfer the energy from the mill to the load (Rezaeizadeh, Fooladi, Powell, & Weerasekara, 2010)."

Jan 1, 2016

By D. M. Slavich

"In today's operating and investment climate, project evaluation is both more important and more difficult. It is more important because economic and financial analyses of a proposed project provide a basis for judgment of a project's commercial viability by equity participants, lenders and, in some cases, other participants such as off takers and governments. It is more difficult because these analyses must, of necessity, be based on estimates, projections and evaluations which must be made in a period remarkable for its economic and political uncertainty.Project evaluation starts with the analysis of the engineering, commercial and financial information available. Beginning with the preliminary design and capital cost estimates, alternative financing plans can be developed outlining possible sources of funds, terms and security arrangements. Pro-forma financial statements can also be developed, including sources and uses of funds, cash flow schedules, income statements and balance sheets. With these results, various profitability measures can be determined.Subsequently, in an effort to deal with uncertainty, these results can be tested by measuring the impact on project viability and profitability of changes in project and external variables such as product process, mining and processing rates, operating and financing costs, currency exchange rates and other factors.The results are a number of financial projections reflecting different assumptions for key project parameters. The projections can be used to structure the project to achieve the maximum financial performance. Projects, the financial viability and profitability of which can be demonstrated under varying market conditions, will be the most competitive in capital markets."

Jan 1, 1982

By K. Parameswaran

This paper builds on presentations made at the Conference of Metallurgists (COM) 2015, COM 2017 and Extraction 2018 and associated papers published in the respective conference proceedings. Based on the classic Brundtland Commission definition of sustainable development as “development that meets the needs of the present without compromising the ability of future generations to meet their own needs,” the paper describes how metal mining can be compatible with sustainable development and how sustainability considerations have been applied in the primary copper industry, using several examples of sustainable mining practices from ASARCO LLC operations. Finally, the paper discusses how these considerations might be used in the future by discussing the need for developing a sustainable development strategy and how this strategy can be aligned with the United Nations Sustainable Development Goals. INTRODUCTION The primary copper industry comprises: mining (also referred to as “extraction”); mineral processing (also referred to as “beneficiation, “milling” or “concentration,”) which includes leaching, solvent extraction (SX), crushing, grinding, froth and flotation operations; and metallurgical processing which includes smelting and converting; refining, which includes fire-refining or anode refining and electro-refining; and electrowinning (EW). There are two routes for producing refined copper: hydrometallurgical and pyrometallurgical. The hydrometallurgical route comprises mining (open-pit and underground), mineral processing (crushing and grinding — for heap leaching only; leaching and SX) and metallurgical processing (EW). The pyrometallurgical route involves mining, mineral processing (crushing, grinding and froth flotation) and metallurgical processing (smelting, fire refining and electro- refining). The primary copper industry is capital, water, resource and energy intensive with the potential for significant environmental impacts, if the environmental aspects are not properly managed. ASARCO LLC (Asarco) was organized in 1899 as the American Smelting And Refining Company. Originally a consolidation of several lead-silver smelting companies, it evolved over the years into an integrated producer of primary non-ferrous metals, including copper, lead and zinc and associated co-products. Grupo México, S.A.B. de C.V (Grupo México) acquired Asarco in 1999. Today, Asarco is a vertically integrated producer of primary refined copper and associated co-products such as gold, silver, selenium and tellurium. Asarco operates three open-pit mines and mills, two leach, SX-EW plants, a copper smelter in Arizona and a copper electrolytic refinery in Texas.

Jan 1, 2019

By T. Holmes, S. Davison

"The Special Standard Surge bin at Agrium’s Vanscoy Potash Operations (VPO) has been plagued with flow problems and wear, and corrosion issues for it’s entire working life. Investigation showed that the carbon steel construction, bin geometry, and resultant funnel-flow pattern were directly responsible for production losses and disproportionate maintenance and capital costs. Potash enters this bin at between 140°C and 165°C, but the stagnant potash outside the active flow channel was much cooler, allowing moisture to migrate toward the outer regions, which caused corrosion of the walls and reduced live capacity as the potash in this area hardened and built up on the walls over time.A 2013 inspection revealed holes and paper-thin areas in the lower cylinder wall sections and in the conical hopper. The only thing preventing major leaks and even a potentially catastrophic failure was the buildup of stagnant hardened product on the cone walls. It was concluded that the cone had reached the end of its life and required replacement. VPO’s original plan was to replace the cone in kind and repair the cylinder as necessary; however, a failure-mode and bin-performance investigation combined with a lifecycle- cost analysis indicated it would be better to redesign the hopper.For success in retrofit projects, it is essential at the design stage to consider the bulk solid flow properties and the operating environment involved. Because education in this area is not offered at a university level, engineers often do not fully appreciate the effects of the flow properties of bulk solids on bulk material handling equipment.Jenike & Johanson conducted flow properties tests on samples of potash and using the data, redesigned the bin and the feeder. After the modifications, VPO’s surge bin provides safer, more reliable operation with a much longer predicted working life. Using this retrofit as an example, we aim to provide a general understanding of bulk solids flow theory and highlight the importance of customizing the design to the appropriate flow properties in the cost effectiveness, reliability, and safety of a bulk material handling system."

Jan 1, 2016

By Robert B. Parsons

"This article addresses the relationship between mine evaluation, the tax system, and economic risk. It is based on a paper presented by the author at recent seminars in Moscow and Tashkent on the subject of mine evaluation.IntroductionTaxation can have a strong influence on the feasibility of a mining project. For the most part, because metal prices are determined on a global basis, the mining concern is not able to pass on to its customers any portion of taxes which the concern has to pay. Taxes are a direct charge against the project. The purpose of the article is to highlight the various ways whereby different taxes can affect the financial viability of a mining operation.The first part of the paper identifies different forms of taxation, and the second part of the paper addresses the different forms of taxation in terms of risk analysis and impacts on the mining project. Finally, the third part of the paper makes brief mention of using the taxation system to provide incentives with respect to investment in mining activities."

Jan 1, 1993

By T. Alan O'Hara

"Annual mining revenue can be computed by formulae relating metal prices, smelting schedules, concentrate grade and recovery to known ore grade and an assessment of core samples. Operating costs at different daily tonnages are related to orebody shape, mining method, milling process and general plant services. Capital costs are related to sizing of mining equipment, mine development, plant-site topography, climate and accessibility, plant services and personnel housing. IntroductionA crude guide to the average 1978 cost of mine projects is shown in Figure 1, but the costs of many mine projects have differed widely from the graphed average costs of $800,000 T0.6 for underground mine/mill projects and $400,000 T 0.6 for low-grade open-pit mine/mill projects.High mine project costs and high operating costs are characteristic of open-pit mines with high stripping ratios, underground mines with thin orebodies, mills with complex metallurgy, and projects located in isolated regions with severe climate, mountainous topography, and lacking access to existing roads, towns and electric power. When none of these adverse conditions prevailed, the mine project cost was typically much less than the graphed average cost. Virtually all the conditions likely to cause high capital and operating costs are known from knowledge of the local topography, climate or accessibility, or can be assessed by tests on core samples, as soon as the orebody has been outlined by drilling .A more accurate estimate of over-all project capital cost and operating cost can be made from a summation of items of cost after judging the effect of specific local conditions on each item of capital and operating cost. This paper offers guides in judging the effect of local conditions on the sizing and 1978 cost of specific items of capital cost and operating cost and operating cost of mine projects. When the specific items of capital cost and operating cost are totaled and measured against expected net revenue and taxes over the life of the mine using the net-present-value or discount-cash-flow methods, the result should show whether the mine project development is clearly feasible, doubtfully feasible or clearly uneconomic. If the development of the mine project is clearly feasible, or probably feasible, a detailed feasibility study by experienced consulting engineers should be commissioned before any financial commitments are made; but if project development appears to be uneconomic, the time and cost of a detailed feasibility study is not warranted."

Jan 1, 1980

By R. I. Grauch, Michael D. Glascock, Chen Nansheng, Jr Coveney, James B. Murowchick

"Unusually rich molybdenum ores (cutoff grade = 4.10/0 Mo) hosted by Lower Cambrian black shales have been mined since 1985 near Zunyi in the province of Guizhou in China. Similar ores were once worked for Mo and Ni near Dayong in the province of Hunan. In both mining areas, mineralization occurs in Lower Cambrian black shale (Niutitang Formation and stratigraphic equivalents) as a single sulfide bed or lens with exposed thicknesses up to 15 cm and reported thicknesses up to 35 cm. In addition to high Mo values (4% to 7%), ore samples contain up to 7% Ni, 2% Zn, 2.5% As, and several hundred ppb Au and Pt-group elements, but the precious metals have never been recovered from the ores. Sporadic occurrences of Mo-Ni sulfide ore beds are found in at least five provinces stretching approximately 1600 Ian from Yunnan to Zhejiang. None of the Mo-Ni ore-bed occurrences has any obvious connection with mafic or ultramafic source rocks. Similar occurrences containing elevated values for Ni, Mo, and PGE exist in Devonian black shale in the Yukon. Future exploration for Pt, Au, Mo, and Ni deposits should consider this previously unknown type of sediment-hosted mineral deposit.Sommaire - Des minerais anormalement riches en molybdène (teneur-limite = 4.1% Mo) provenant de schistes argileux noirs du Cambrien Inferieur ont été exploites depuis 1985 près de Zunyi dans la province de Guizhou en Chine. Des minerais semblables ont déjà été traire pour Mo et Ni près de Dayong dans la province de Hunan. Dans ces deux régions minières, la minéralisation se présente dans le schiste argileux noir du Cambrien Inferieur (Formation Niutitang et équivalents stratigraphiques) sous forme de couche ou lentille unique de sulfures avec des épaisseurs exposées de plus de 15 cm et des épaisseurs rapport6es de plus de 35 cm. En plus des fortes teneurs en Mo (4%-7%), des échantillons du minerai contiennent jusqu’ à 7% de Ni, 2% de Zn, 2.5% d'As, et plusieurs centaines de ppb d'or et d'éléments du groupe du platine; toutefois, les métaux précieux n'ont jamais été récupérés des minerais. Des présences sporadiques sous forme de couches de minerai sulfure de Mo-Ni se retrouvent dans pas moins de cinq provinces s'etendant sur 1600 km de Yunnan a Zhijiang. Aucune de ces présences de minerais, sous forme de couches, ne semble associée a des roches du type mafique ou ultramafique. Des présences similaires contenant des teneurs élevées en Ni, Mo et EOP se retrouvent dans le schiste argileux noir Devonien du Yukon. L'exploration future pour des gisements de Pt, Au, Mo et Ni doit prendre en considération ce type de gisement encore inconnu précédemment."

Jan 1, 1992

By Desmond M. Levins, Reginald K. Ryan

"Removal of radium from uranium tailings would substantially lessen their environmental impact because it would eliminate, or greatly reduce, the hazards arising from radon emanation, leaching of radium, dust dispersal and gamma radiation. A process is described to extract radium from tailings by leaching in 3M Nael solution. The radium can be rapidly leached at ambient temperatures by either multi-stage contact in agitated vessels or washing on a tailings filter cake. Extraction efficiencies ranging from 80 to 94% have been measured for tailings derived from a number of Australian ores.Methods for radium recovery from the leach solution by precipitation, ion exchange and adsorption have been examined. Precipitation as barium/radium sulphate appears to be the most suitable approach. A possible flow diagram for the process is proposed which involves recycle of the saline leach liquor.IntroductionDisposal of mill tailings is the most contentious environmental issue facing the uranium mining industry. The conventional approach to managing tailings is to store them in a dam above ground. Attempts have been made to stabilize some tailings piles by physical or chemical methods. In a few cases, the tailings have been covered with earth and revegetated. However, most tailings piles from abandoned mills are in a neglected state and subject to the erosive and dispersive forces of nature. The cost of remedial action is high. The United States Department of Energy (DOE) has estimated that it will cost up to $130 million to rehabilitate abandoned mill sites in the U.S .A..Environmental authorities are now insisting that uranium mining companies improve their methods of tailings disposal. In the United States, the preferred approach is burial, either in mines or in specially excavated pits. Tailings retention systems as operated in Canada are regarded as storage facilities until an acceptable method of disposal is found. In Australia, the Fox Commission recommended that tailings from the Ranger project should be returned to the open-cut mine. Returning tailings to the mine has considerable merit, but it is not always a viable option. In many underground operations, it is not physically possible to fit all the tailings in the worked-out mine. In other cases, the groundwater hydrology of the mine may be unfavourable."

Jan 1, 1980

By Robert Marchand

_ North-western Quebec _ Bousquet mining district _ 21 M oz mining camp _ 100,000 t/yr (400 t/d) _ Shrinkage : 52 % _ Longhole : 40% _ Development : 8% _ 5 days/week _ 120 employees _Discovered in 1936. _12 changes of ownership. _Exploration & development : 1987 _Commercial production : 1990 _Shaft deepening : 1995 _Internal shaft : 1999

Oct 1, 2001

By A. G. Darnley

"The Geological Survey of Canada is devoting consider-able effort to finding ways to make airborne radiometric measurements both quantitative and reproducible. Equipment has been designed by Atomic Energy of Canada Ltd. to provide high count rates in order to minimize statistical uncertainty, this being essential to justify applying terrain clearance and Compton scattering corrections to the data. Correction factors have been determined experimentally and can be applied automatically. Considerable ground work has been undertaken in parallel with equip-ment development in order to determine field parameters.Two airborne gamma-ray spectrometers are described. One is based on three 5-by 5-inch Nal(Tl) detector crystals and is used in a helicopter; the other employs twelve 9-by 9-inch detectors and is used from a Skyvan aircraft. The former is being used to investigate the range of radiometric response from specific rock types, and for the correlation of ground and air measurements; the latter has completed initial trials and will be commencing experimental surveys during 1969.Results are given to show the comparative sensitivities of the various detector sizes, and operational requirements for a gamma-ray spectrometer survey are discussed briefly."

Jan 1, 1970

By J. A. Folinsbee, Andre Robitaille, Tony Y. Chong

"Conventional crushing and grinding is followed by gravity concentration to recover free milling gold. Refractory gold, finely disseminated within the pyrite and arsenopyrite matrix, is recovered by flotation followed by pressure oxidation, cyanidation, and cementation. Non-refractory gold is recovered by cyanidation/CIP processing.A comprehensive test program aimed at improving flotation recovery was initiated in June 1995. Plant testing indicated that flotation tails value could be significantly reduced using mechanical flotation cells. Based on these test results, a flotation circuit that incorporates one of the three existing flotation columns followed by mechanical scavenging and cleaning was developed. Detailed engineering was completed in September 1996. Construction started in February 1997 and was completed in 3 months at a cost of $3.2 million. An on-stream X-ray analyzer was installed to provide real-time arsenic and iron analyses and inferred sulphur value on some of the flotation streams.The new flotation circuit proved to be an instant success. Flotation tails values were reduced by 27%. Final tails solids and solution was reduced from 0.035 to 0 023, and 0.0014 to 0.0006 oz/ton Au, respectively. Based on a mill throughput of 1,620 stpd this decrease in tails value will result in an increased gold production of 7,500 ounces per year. The payback for the project is estimated to be around one year.This paper describes the evolution of the project from bench scale testing to commissioning. Also, the operational and economic impacts on down stream processing are highlighted"

Jan 1, 1998

By G. Roy, D. R. Lentz, A. O. Wills

"Abstract - Diamond-drill hole DDH-B357, located 1.5 km north of the Brunswick No. 6 Zn-Pb- Cu-Ag volcanic-sediment-hosted massive sulfide (VSHMS) deposit, intersects three exhalative horizons within variably altered felsic volcanic rocks of the Nepisiguit Falls and Flat Landing Brook formations. These three petrographically indistinguishable iron formation intervals (Fe2O3T = 21.4 wt.%) likely represent cogenetic hydrothermal sedimentary units because they display a common geochemical signature: Fe2O3T = 42.9 ± 10.5 wt.%, MnO = 5.4 ± 3.1 wt.%, elevated base metal values (Zn+Pb = 1999 ± 1091 ppm), strong enrichment in additional exhalative components (CaO = 5.3 ± 3.9 wt.%; P2O5 = 1.43 ± 1.00 wt.%), oxidized signature (Fe/Mn = 10 ± 6), as well as a common immobile element signature (Zr/TiO2 = 0.025 ± 0.007) representative of a pelagic source. The calc-alkaline to transitional host volcanic rocks can be discriminated by Zr/TiO2, and to a lesser extent by Th/Nb: Nepisiguit Falls Formation: Zr/TiO2 = 0.053 ± 0.004, Th/Nb = 1.08 ± 0.37; Flat Landing Brook Formation: Zr/TiO2 = 0.107 ± 0.043, Th/Nb = 0.86 ± 0.17. A symmetrical repetition of the footwall-iron formation-hanging wall stratigraphic sequence is observed in DDH-B357, with distinct felsic volcanic rock domains separated by the three iron formations. This is best explained by parasitic F2 folds on the west flank of the south-plunging Brunswick antiform, similar to the fold closures known to host massive sulfide accumulations in the Brunswick No. 6 and No. 12 mines. Iron formation geochemistry and felsic volcanic rock chemostratigraphy from drill core sampling can provide an effective mineral exploration tool for the structurally complex rocks of the Bathurst Mining Camp. Sommaire - Le forage au diamant DDH-B357, situé à 1.5 km au nord du gisement de Sulfures Massifs à Encaissant Volcanique et Sédimentaire (SMEVS) de Zn-Pb-Cu-Ag Brunswick No. 6 recoupe trois horizons exhalatifs au sein des roches volcaniques felsiques diversement altérées des formations de Nepisiguit Falls et de Flat Landing Brook. Ces trois intervalles de formation de fer, impossibles à distinguer pétrographiquement les uns des autres, représentent vraisemblablement des unités sédimentaires hydrothermales cogénétiques sur la base de leur signature géochimique commune: Fe2O3T = 42.9 ± 10.5 % poids, MnO = 5.4 ± 3.1 % poids, des teneurs élevées en métaux usuels (Zn+Pb = 1999 ± 1091 ppm), un fort enrichissement en composantes exhalatives additionnelles (CaO = 5.3 ± 3.9 % poids; P2O5 = 1.43 ± 1.00 % poids), une signature oxydée (Fe/ Mn = 10 ± 6), ainsi qu’une signature d’éléments immobiles communs (Zr/TiO2 = 0.025 ± 0.007) indicative d’une source pélagique. Les roches volcaniques encaissantes calco-alcalines à transitionnelles peuvent êtres reconnues par leur rapport Zr/TiO2, et à un moindre degré par leur rapport Th/Nb: Formation de Nepisiguit Falls: Zr/TiO2 = 0.053 ± 0.004, Th/Nb = 1.08 ± 0.37; Formation de Flat Landing Brook: Zr/TiO2 = 0.107 ± 0.043, Th/Nb = 0.86 ± 0.17. Une répétition symétrique de la séquence stratigraphique Mur-Formation de Fer-Toit a été observée dans le forage DDH-B357, avec des domaines distincts constitués de roches volcaniques felsiques séparés par les trois formations de fer. La meilleure explication est que le flanc ouest de l’anticlinal Brunswick à plongée sud est affecté par des plis parasites F2, similaires aux zones de charnière contenant les sulfures massifs des mines Brunswick No. 6 et No. 12. La géochimie des formations de fer et la chimiostratigraphie des roches volcaniques felsiques en forage peuvent fournir un outil d’exploration minérale efficace dans les roches structuralement complexes du Camp Minier de Bathurst."

Jan 1, 2006

By M. Pierce

Empirical relations exist for the estimation of rock block strength at scales larger than standard core sizes. Two recently published relations account for the significant impact that microflaws (pores, open cracks, veins) and weathering/alteration can have on scale effect. These relations were used to estimate the rock block strength of heavily microfractured quartzite from the Bingham Canyon Mine. Predictions were compared to the results of Uniaxial Compressive Strength (UCS) tests conducted on cylindrical core samples of varying microfracture intensity and diameter. The comparison confirms the sensitivity to microfracturing suggested by existing relations and suggests that they would benefit from more detailed consideration of microfracture strength, density and persistence over a range of scales. The results of a numerical study illustrate how Synthetic Rock Mass (SRM) modeling techniques could be used to complement empirical data in the development of such relations.

May 1, 2009

By A. P. Williams

"This paper presents an overview of plant electrical systems in general, a discussion of the problems that may occur due to plant growth, the maintenance required to maintain the reliability and safety of the electrical system, and the selectivity of the relay protection system. It is divided into two main areas: short circuit levels within the plant electrical system; and relay protection systems.This information is directed at maintenance supervisors, mine managers and electrical superintendents who have been away from detailed short circuit and relay coordination calculations for some time. It points out the potential problem areas within an operating plant electrical system. Short Circuit LevelsTheoryThe electrical equipment in a plant such as breakers, switches and starters has two short circuit ratings, the momentary rating and the interrupting rating. These ratings may be given in MVA or current (amperes) depending on the equipment and manufacturer's preference. Since for a three-phase system MVA and amperes are related by the formula"

Jan 1, 1987