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By Kelly J. Driscoll

Impure zinc (98.5%) was electrorefined to high purity zinc (99.995%) using a fused salt electrolyte of molar composition 1: 1 : 1 :2 ZnCI2:KCl:NaCl:LiCl with a current efficiency of about 90% at 723 K. A recessed channel electrorefining cell was developed which achieved excellent mixing of both the metal and the electrolyte and by ensuring a very small anode to cathode spacing the voltage drop across the cell was 0.16 V and at a current density of 7kA m-2. The physical characteristics of the cell were observed using a low temperature model which showed the formation of droplets and rivulets which provided mixing. The application of this approach to the refining of other non-ferrous metals is discussed.

Jan 1, 1992

By K. Sun

The exothermic behavior of the intermetallic reactions inside an Al-Mn metallic powder compact and its assimilation fundamentals in molten aluminum were examined. In this study cylindrical compacts were manufactured and tested. The experimental work involved simultaneous temperature measurements of three thermocouples as well as detection of the apparent weight of the cylindrical specimen during its assimilation in liquid aluminum. The details of the intermetallic reactions prior to the compact complete disintegration were investigated by microscopically studying the morphology and local composition in a partially reacted compact. The variation of manganese concentration in the melt was determined by chemically analyzing the samples taken from the molten aluminum at specific time intervals. The exothermic reaction increases the compact's temperature above that of the liquid aluminum. In tandem with this exothermic reaction, the compact is suffering a swelling action. This swelling action disintegrates the cylindrical specimen, which is assimilated into the liquid aluminum. The intermetallic reactions proceed in a stepwise manner. Both the bath temperature and the compact composition impact on the exothermicity of the intermetallic reactions. However, when the amount of Mn in the compact is greater than 75-wt%, the maximum centerline temperature rise is slightly reduced as Mn amount increases.

Jan 1, 2004

By Chris Twigge-Molecey, John Peacey

To meet the business objectives of a metallurgical project, there is often a need for new and untried technology or equipment, whose very novelty can present serious risks to meeting those objectives. The key risk management approach is a rigorous stepwise progression from theoretical evaluations and laboratory tests to pilot plant trials. These must be followed by demonstration-scale trials before final construction of a commercial scale plant, paying particular attention to the magnitude of the scale-up between phases. Success depends on following a well-defined program, not eliminating any steps, and ensuring adequate resources are available to the development team. Chapter 6 discusses the nature of technology risks to metallurgical plant projects, and the rigorous management practices needed to identify, analyze, evaluate, and avoid or mitigate them.

Jan 1, 2015

By J. Kretschmann, A. Müterthies, T. Rudolph, C. Yang, P. Goerke-Mallet

Catastrophic failures of dams and tailing storage facilities (TSF) have triggered the development of integrated ground monitoring concepts for hazard assessment, risk management and public safety. These concepts are based on knowledge and expertise of persons technically responsible for TSF. The aim is to combine this implicit and explicit knowledge with the data of in-situ- and remote sensors. Risk management for TSF must include a comprehensive monitoring program that integrates data from ground based-, air-borneand satellite-based sensors. Researchers at Technical University Georg Agricola (THGA) in Bochum, and EFTAS, Muenster, Germany, are fusing a variety of sensor data to enhance the capability and performance of TSF monitoring to ensure public safety downstream of TSFs. This paper describes the variety of sensors implemented in numerous research projects. It gives an outlook in terms of planned satellite missions with innovative equipment like hyperspectral sensors. The implementation of the data of these sensors in the analysis will increase the understanding of spatio-temporal impacts of mining activities. Future opportunities are explained by a datacube approach.

Mar 2, 2022

By D J. Brake

Faced with the need to improve workplace conditions in both its development and production headings in its existing K1 orebody, as well as its new K Link and K2 orebodies, the Kencana mine in Indonesia took the novel approach of reversing the ventilation on most of its access ramp by outcasting up the ramp to the portal. Working levels were then fed with fresh air via auxiliary fans sealed into the current surface ‘egress’ intake raises (ladderways) or another small surface intake raisebore rather than from fans hung in the ramp as in the past. Outcasting the portal provided a substantial increase in the total mine exhaust capacity allowing fewer levels to be ventilated in series and significantly improving conditions, especially in the most difficult workplaces to ventilate. It also reduced the consequences if there was to be a fire on a vehicle in the ramp. The same system using the ramp as an exhaust is also intended to be used as part of the final ventilation solution for the new K2 orebody which also uses a novel single surface ventilation shaft that is vertically split into separate intake and exhaust compartments using a concrete brattice. Using the main ramp as an exhaust has potential application in many other operations in Australia using surface ramps which otherwise frequently suffer from overuse of series ventilation circuits and poor working conditions at the mine bottom.

Mar 21, 2011

By Jeffrey C. Schuh, Logan Bloemer, Daniel P. Dietzler

Over the past 30 years, the authors have encountered numerous projects where recognizing the geology, soil properties and groundwater conditions, and considering alternative construction techniques have promoted efficient and cost-saving construction. The construction documents for these projects, produced by various engineering firms, provided basic information on geotechnical conditions. The authors became involved in each project either because there was a problem during design or construction or, as a contractor, won the project because they saw a value engineering opportunity to take advantage of the geologic setting of the project to design and build alternatives to what the designer depicted. Understanding the geologic setting is critical before planning and designing begins. Being able to work with the geology and the materials on site is preferred before specifying more costly and complex solutions, which often require the importing of materials and adherence to unnecessary and/or inappropriate specifications. Failing to understand the geology or not knowing all the techniques available for construction can lead designers to develop solutions that could be inappropriate. This paper presents several examples of value engineering and project performance enhancements developed through knowledge of basic soil mechanics and implementing innovative solutions. History and Background Most people attend DFI meetings, present their experiences, listen to others, and read articles and papers with the hope they can learn from others. Geotechnical engineers and contractors often interface with others in the execution of projects who have, at best, a rudimentary knowledge of geology and soil mechanics. Of course, there is a need for architects, bankers, and regulators, etc., but they typically do not have much interest in the nuances of geotechnical engineering, which relies on both art and science. Thus, significant time is spent educating counterparts in the need for comprehensive subsurface investigation programs and the intricacies of construction in the “dirt,” as they typically refer to soil and rock.

Jan 1, 2019

By Mike Dry, Rod Dry

If humanity is truly serious about reducing emissions of carbon dioxide into the atmosphere, today’s power plants burning fossil fuels will have to be replaced by power plants that do not emit CO₂. Unless carbon capture/sequestration becomes practical, the new power plants will be hydroelectric, wind, solar or nuclear installations. Hydroelectricity requires the appropriate geography. Solar installations can only deliver power as and when sunshine is available, and wind installations when the wind blows. Therefore, power from these sources will be intermittent, but the demand for electricity does not follow the patterns of sun and wind. That will require large-scale electricity storage and/or load following by the remaining power suppliers, increasingly so as the use of fossil fuelled power generation declines. Modern nuclear power plants are designed for demand following. However, operating at lower than design output has a negative impact on the economics of nuclear power plants because the overall cost of the electricity they generate is dominated by capital cost. Primary (blast furnace) iron smelting is responsible for a significant part of global CO₂ emissions because the reagent used is carbon. Were it available in sufficient quantity (and at a low enough cost), hydrogen could replace carbon in the manufacture of raw direct reduced iron (DRI), using technology such as modified HYL (Tenova Hyl, 2018) or Midrex (Ravenscroft, 2017). This paper examines a scenario in which, instead of demand following, nuclear power stations are operated at their design capacities and surplus power is used to generate hydrogen in off-peak periods. This hydrogen is then used to replace carbon in the manufacture of raw steel.

Jan 1, 2020

By Gregg W. Davidson, J. Andrew McGlenn, Frank Huber

The Second Narrows Water Supply Tunnel will ensure system reliability in the event of a major earthquake and increase the Greater Vancouver Water District’s capacity to meet the long-term needs of a growing population. The tunnel will be 1,100 m long and 6.5 m in diameter (3,610 LF × 21.3 ft), constructed under Burrard Inlet between North Vancouver and Burnaby in British Columbia. It will be excavated through mixed ground conditions under high groundwater pressure, using a slurry TBM, between a 72 m (236 ft) deep shaft in soil and a 110 m (361 ft) deep shaft in rock. The completed tunnel will accommodate three large-diameter water mains that will be installed as part of the tunnel contract. This paper presents the project from design and contractor procurement, into the current construction stage describing some of the unique challenges encountered during the project development to date.

Jun 13, 2021

By S N SHEARD

The use of geophysics in mineral exploration in Australia, and overseas, has increased dramatically over this century. This paper shows that using simple equipment with clever interpretation that the foundations of modem geophysics were laid, using all the same principles. The plethora and diversity of mineral exploration geophysical techniques does not allow a full description of their evolution to be given in such a paper. To convey this evolution, however, the progress of two different geophysical methods, magnetics - a potential field (passive) method, and electromagnetics - an electrical (active) method, are described. Examples of magnetic survey data from the 1920s and more recent vehicle home and airborne surveys are given to show the increase in data quality through technological improvement. A set of four airborne electromagnetic data sets spanning three decades is used to indicate the improvement in electromagnetic techniques. It is argued, that considerable progress is still required in the electromagnetic field to increase its interpretability.

Jan 1, 1992

By C. A. Gibbons

AFTER nine years of extremely de- pressed business, marked mostly A with red ink on the balance sheets of most coal companies and with an increasing internal competitive struggle for diminishing markets, somewhat of a change appeared during 1939. Shipments increased and prices generally firmed, giving the coal industry increasing optimism and encouragement for the future. Specifically, it now appears that bituminous coal production for 1939 will approximate 378,000,000 tons, and anthracite production will approximate 47,500,000 tons, bituminous production being around 14 per cent ahead of 1938 and anthracite production 12 per cent better. The curve on p. 31, showing both bituminous and anthracite production, furnished by the bituminous coal division of the Department of the Interior, shows graphically most of the 1939 monthly production and clearly illustrates the increased production.

Jan 1, 1940

By Eugene Larochelle

The serpentine of the Eastern Townships of Quebec is more or less seamed and impregnated with chrysotile asbestos, of which we note two types: the cross-fibre and the disseminated fibre. The cross-fibre type always appears in fibres or crystals arranged parallel to one another, and disposed at right angles to the walls of the matrix serpentine. The length of fibre of these veins, which run in every conceivable direction, even crossing ?one another, varies from microscopie dimensions to three and sometimes four and even five inches. It is the principal form of asbestos found in the serpentine of Thetford Mines, Black Lake, Coleraine, and Asbestos. The disseminated-fibre type, which is the main product of the serpentine of Broughton township, in which ate located the mines at East Broughton, does not form veins, but occurs in the serpentine without any definite arrangement. There is a difference in the toughness and hardness of the rock of the two types, the Broughton serpentine being softer than that at Thetford. The disseminated-fibre section of the serpentine belt is probably more regular in its content than is the cross-fibre section. Nevertheless, it contains no 'crude,' which is the most valuable of asbestos, and the fibre is usually shorter than the cross-fibre average.

Jan 1, 1928

By Martin D. Larisch, Ronald Damen

The design and construction of temporary working platforms for cranes and piling rigs is a high-risk activity. It requires the careful selection of the appropriate input parameters to obtain the correct load cases, as well as the application of robust and reliable design methods to assess the required thickness and stiffness of the working platform. The document introduces some of the most common and most relevant guidelines for working platform design which are currently used in Australia and New Zealand. The authors will also discuss the basic assumptions and considerations about load transfer from construction plant, debate ground risk, compare the applicability of different design methods for various ground conditions and suggest some common verification methods for working platform certification.

May 1, 2022

By E. Goris Cervantes

"A theoretical framework based on a detailed analysis of mine operations data from an oil sands mine in northern Alberta and the static simulation of truck cycle times are developed, verified, and validated in this paper. Implementation of this framework provides better results than existing tools that rely solely on manufacturer data. This, therefore, aids in efficient equipment planning for the life of the mine. The use of this framework to modify existing productivity curve estimation methods currently in use at the mine site is also proposed. This method replaces “loaded flat haul” with “loaded effective flat haul” in the productivity estimation. Validation of the model results in a 4% overestimation of productivity, versus an underestimation of more than 10% when using the existing in-house method. ¦ KEYWORDS Equipment planning, Life-of-mine (LOM) planning, Oil sands, Productivity, Truck cycle times RÉSUMÉ Un cadre théorique fondé sur une analyse détaillée des données relatives aux activités minières d’une exploitation de sables bitumineux dans le nord de l’Alberta et la simulation statique des temps de cycle des camions sont développés, vérifiés et validés dans cet article. La mise en oeuvre de ce cadre offre de meilleurs résultats que ce que proposent les outils existants, lesquels se basent uniquement sur des données des constructeurs. Ceci contribue donc à une planification efficace de l’équipement pour des projets relatifs à la durée de vie de la mine. On propose également de se servir de ce cadre pour modifier les méthodes d’estimation de la courbe de productivité actuellement utilisées sur le site minier. Cette méthode remplace le concept de loaded flat haul (la distance parcourue par des camions avec un chargement du point de collecte jusqu’au point de déchargement des résidus miniers) par celui d’effective loaded flat haul (la distance relative parcourue par des camions avec un chargement du point de collecte jusqu’au point de déchargement des résidus miniers) dans l’estimation de la production. La validation du modèle résulte en une surestimation de 4 % de la productivité, par rapport à une sous-estimation de plus de 10 % avec la méthode actuellement utilisée en interne. ¦ MOTS CLÉS planification de la durée de vie de la mine, planification de l’équipement, productivité, sables bitumineux, temps de cycle d’un camionINTRODUCTION One aspect that differentiates oil sands mines in northern Alberta from conventional hard-rock mining is the environment in which they operate. Due to ground characteristics, producers in the region experience roads with very high rolling resistance (RR) that, in turn, negatively affect haul-truck performance and greatly increase fuel consumption and emissions. Oil sands mining companies use some of the largest haul trucks in the world. In addition, oil sands mines cover more extensive areas than hard-rock pits, resulting in longer haul distances on roads made of comparatively more viscous material."

Jan 1, 2019

By F. T. Cawood, C. C. Birc

The South African mineral resource royalty system, initiated in 2010, employs a hybrid ad valorem approach tied to profitability ratios. This rate is then applied to the total revenue from mineral sales. In this article we explore how the profitability ratio in the mineral resource royalty formulae interacts with the gold tax formula as applied to South African gold mines, devising a strategy for cut-off grade optimization. The study focuses on nine narrow, tabular-reef (Witwatersrand) gold mines. The approach involves a mixed-integer cut-off grade optimizer utilizing Excel Solver, incorporating relevant royalty and income tax formulae. Different mineral resource royalty cost scenarios were examined. Ignoring these costs in the break-even analysis lowers the cut-off grade but slightly boosts profits compared to considering expected costs. The developed optimizer model, recognizing the profitability aspect of the mineral resource royalty and income tax formulae, yielded a 6% lower cut-off grade than the base case. This is significant for increasing mine life. While the profit differences are marginal (0.2% compared to the break-even base case), substantial improvements were noted: a 6% increase in stope tons above cut-off grade, and a 4% rise in total revenue. Enhanced resource utilization (3% extra gold kilograms) reduces necessary development and overall costs, allowing for a reduction in the cut-off grade and ultimately, more profit.

Aug 8, 2024

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 A. Hartikainen, M. Rinne, F. Johansson, R. Yorke, L K. T. Uotinen, E. Korpi, J. Antikainen

"In order to determine the in-situ shear strength of rock joints, large scale testing is required. However, this is both expensive and difficult to execute. One possible method to overcome this may be to use photogrammetry to capture large joint surface roughness in-situ and downscale it to replica samples, which could be sheared in laboratory. In this paper, as a first part in such a method, a technique to digitize surface roughness and to produce replica samples for laboratory shear testing from a larger joint sample are presented. First, a thin granitic rock slice with dimensions of 1.75 m x 0.95 m of granitic intact rock was chosen for the study. The joint surface is fresh and created through tensile induced splitting. The large joint sample is digitized using photogrammetry. Then, one fullscale 1.7 m x 0.6 m geometry is cropped from the digitized joint geometry and then subsamples at 10x, 7.5x, 5x, 2.5x and 1x scales. All sub-geometries are scaled down digitally to produce 0.17 m by 0.06 m geometries. The geometries are used to make casting molds both positive and negative to produce samples with perfect matedness. The casting molds are 3D printed in polylactic acid plastic and C60/75 concrete is cast to produce a replica series. In addition to the creation of this replica series, two pilot replicas are also tested using a portable shear box with a 0.5 MPa normal pressure. The results from the pilot rounds are presented and discussed. Finally, suggestions for future research are given.INTRODUCTIONThe rock mass strength is in many cases controlled by the shear strength of rock joints, especially in hard rock masses. The shear strength is generally found to be influenced by several parameters, including normal stress, the basic friction angle of the intact rock, the joint surface roughness, the joint wall compressive strength, the matedness of the joint surfaces, weathering and infilling. The effect of these parameters for the joint shear strength can be evaluated in laboratory scale. However, the shear strength is known to be scale dependent. How the scale effect influences the strength is not fully understood. The general consensus is that the shear strength decreases when sample size increases, i.e. a negative scale effect (Bandis et al. 1981). However, some studies have presented contradictory results, see for example Hencher et al. (1993) and Kutter & Otto (1990). The extent and nature of the scale effect is still a question of debate (Tatone & Grasselli 2013)."

Jan 1, 2015

By J. Fuchs

This paper describes the mechanized narrow vein cut-and-fill approach used for the Deep Copper orebody at Falconbridge Limited's Strathcona Mine. Strategies for achieving high productivity while maintaining ground stability at depth and controlling dilution are discussed, including the use of mini-electrohydraulic drilling equipment, containerized truck haulage, consolidated rockfill placement techniques, and a miners' incentive system.

Jan 1, 1992

By B. S. Agbenuvor, R. Morrison, V. Jokovic, C. Antonio

Body breakage usually involves breakage of particles by compression between two surfaces or impacted against a rigid surface, with the latter of interest in this current study. This mode of breakage has been identified to be the most elementary size reduction process and the most effective breakage process in comminution devices. It has been found in the literature that the progenies produced from this form of breakage possess a residual velocity at which they move, after the breakage event. In the pursuit of efficiently utilising applied comminution energy, a laboratory-scale breakage device has been developed to deliver precise specific impact breakage using the concept of a fast-moving hammer and a slow-moving particle to effect breakage. The residual velocities of the progenies from the breakage event may be used to generate secondary breakage without further addition of energy if the particle encounters a stiff obstacle such as a steel plate at right angles to its path. To measure the extent of secondary breakage, the steel wall of the device was lined with a rubber material to suppress the second set of breakage events. The performance of the new device is analysed, based on calculated t10 values and measured residual velocities of the moving daughter particles. Testing involving anvils showed a much finer PSD and higher t10 compared to the test involving rubber lining. This finding is corroborated by the measured residual velocities of the progenies. The resulting energies calculated from the measured residual velocities of the progeny were found to be approximately 42-88% of the primary specific impact energy. This retained energy was found to be sufficient for secondary breakage. Keywords: Impact breakage, residual velocity, secondary breakage, energy utilisation

Jan 1, 2020

By Constantine C. Popoff

During 1946 several high-grade limestone deposits in western Washington were examined by the Bureau of Mines. This report presents the data obtained from investigation of the Sauk Mountain deposits in east-central Skagit County, Washington, The investigation consisted of transit and topographic surveys and sampling. The areas selected for sampling were first cleaned by blasting; channel samples up to 40 pounds Were cut where practical. Chip samples averaging 30 pounds were taken where channel samples could not be cut. A total of 21 samples in the Sauk Mountain area were taken and analyzed. The locations of the samples are shown in figures 2 and 4, and the analyses are listed in tables 1 and 2. This investigation is a part of a long-range program of general investigation of mineral resources for future industrial development of the Pacific Northwest. The Sauk Mountain deposits were investigated for the purpose of disclosing new sources of high-purity limestone, which could be mined and shipped at low cost to Seattle and other industrial cities in the Pacific Northwest.

Jan 1, 1948

By D. A. Elkins

Design plans and detailed cost estimates of mining and treating ore from Maggie Canyon deposit by two alternative methods which can be used in the event of a sudden need to exploit this resource are given . Lower costs are estimated for the operation employing oil - emulsion flotation . The total capital investment required for this operation is estimated at $ 11,750,000 . Assuming an 85 percent recovery in mining , 55.6 pct of the manganese in the ore reserve would report in 153,333 tons of ferromanganese containing 75 pct manganese . The production cost for the 5 - year operation would be about $ 245 per ton of ferromanganese . The total annual operating cost would be approximately $ 7.5 million , distributed , in pct , as follows : Mining 11.9 , milling 24.4 , sintering 9.9 , smelting 47.2 , hauling ore and sinter 2.8 , and general offices 3.8 . Recovery and costs are both higher for the operation employing dithionate leaching . In this operation the required investment is about $ 17,220,000 . Manganese recovery would be 67.6 pct in 186,160 tons of ferromanganese . Production cost would be about $ 284 per ton of ferromanganese . The total annual operating cost would be about $ 10,575,000 , distributed , in pct , as follows : Mining 8.4 , milling 44.4 , sintering 7.4 , smelting 34.7 , hauling ore and sinter 1.3 , and general offices 3.8 . Potential process modifications might reduce the operating cost of the first operation by as much as 7 pct and that of the second operation by as much as 9.5 pct , but exploitation of the deposit by the techniques studied is not economical today .

Jan 1, 1964