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By Marc Bétournay

This article examines how fuel cell technology and related power distribution system fits within mine operating requirements. Considerations for improvement of power plant architecture and functions to yield production advantages are presented. Improvements to conventional mining approaches are also discussed.

May 1, 2007

Advanced high temperature electrochemical systems such as fuel cells, electrolyzers and ionic transport membranes are currently being developed for a wide variety of energy conversion, storage and gas cleanup applications. These systems offer high electrical efficiency, multi fuel capability, modular construction, no/negligible emissions (SOx, NOx, VOC, particulate matters) with capability to sequester green house gas emissions (GHG). Electrochemical processes and electrode reactions will be discussed. Cell and stack component materials and fabrication processes will be presented. Bulk, surface and interface degradation processes responsible for cell and stack performance degradation will be examined.

Jan 1, 2005

By O. Moselhi

This paper describes a method for selection of most suitable project delivery systems for capital projects. It expands upon the method advanced by the Construction Industry Institute (CII) in 2003, and incorporates additional decision criteria and project delivery systems in a multi-tier decision computational platform. The paper integrates the analytical hierarchy process to alleviate the inherent subjectivity associated with the assignments of relative weights to selection criteria used in the CII method. It also expands the range of project delivery options to include Public Private Partnership (PPP) and Integrated Project Delivery (IDP). The range of selection criteria was expanded by 60, beyond the 20 criteria of the CII method. Relative effectiveness values are proposed for the added project delivery systems making use of recent project cases in Canada and the USA. The method was implemented in a spreadsheet application. Multiple scenarios were considered for one of the cases presented in the CII study and a sensitivity analysis performed based on the developments made in this paper. The differences in outputs between the CII method and the proposed method are discussed. This is the first decision framework that incorporates both the presently used PPP and the recently introduced IDP, along with the widely used project delivery systems. The developed method allows users to filter out the factors and alternatives that do not apply to the case at hand, based on key inputs at the upper tier. The method is flexible and can easily be expanded upon and customized by the user.

Aug 1, 2013

By F. Urekar, R. B. Pankhurst

"Air spaces and air gaps in an explosives column are known to allow greater distribution and cushioning of explosive energy from the rock mass. This energy distribution is enhanced if the explosives ' gases can be confined in the borehole for as long as possible by plugging and stemming above the air space.Power Plug is an inflatable plug which can seal a borehole at any point to separate the stemming from an air gap and explosive toe load.IntroductionThis paper will discussion-going work by C-I -L Inc. and operators of two open pit mines to study the results of using Power Plugs:I. Pit wall stability - the authors have found the Power Plug effective for wall control blasting in open pit mines.2. Selective mining of coal seams - the authors work shows the Power Plug allows mining selective coal seams by predrilling underseam waste wedges.Pit Wall StabilityWall stability in an open pit mine is essential for safety. Good wall stability can be achieved with wall control blasting techniques which cushion the effect s of the explosives charge by decoupling the charges from the borehole wall. The usual method of decoupling a charge in a large-diameter rotary borehole is to load the explosives in tubes (Fig .I) . We now believe the air deck system is effective in sea ling a borehole above the explosive charge to create an air deck within the borehole which will cushion the blast.In a linear decoupled charge, an air annulus surrounds the explosives charge and cushions the effects of detonation genera ted gases on the pit wall. In an air deck, i.e. with the hole plugged at the collar, the gases genera ted by an explosive toe load are sealed in the empty borehole column. After a period of time, these trapped gases produce radial cracking between holes along the entire length of the borehole.It is common practice to employ de coupled explosive charge columns in the borehole to limit blast damage to surrounding rock. The exact mechanism of energy transfer in such blasts, however, is not well understood. Interruption of the continuous explosive column in a borehole by means of stemming, or air decks, may also be viewed as another form of decoupled blast. Decoupling of the explosive charge from the borehole wall affects both explosive energy release and explosion pressure developed in the borehole."

Jan 1, 1988

By R. Alarcón Sch., R. Abel F.

For many years, copper cathode quality has been a priority for end consumers, since it affects the variety of products that can be obtained from them. From the beginning, physical and chemical quality of the wire bars was controlled, as this product was used to obtain wire rod and other forms of copper by wire drawing. At that time, all the electro refined cathodes were melted and casted as wire bars. Subsequently, in the 80’s, with the introduction of continuous casting furnaces, it was possible to directly produce wire rod from cathodes. From then on, cathodes quality standards were consistently increased, by the introduction of uniform criteria, among which we can identify ASTM and British Standards as well. Also, producers began to use more demanding internal standards than the existing specifications, in order to differentiate their cathodes as high quality products among customers. Today the physical aspect of cathodes, including nodules, cracks, sulfates, or others, is the first element used by end customers to assess their quality. This paper aims to show a brief vision of the evolution of quality specifications for products used to manufacture copper wire. INTRODUCTION From the beginning of refined copper production for industrial purposes, mandatory minimum quality conditions were established. These quality conditions were used as the main element to determine prices and discounts of the respective sales contracts. Reviewing the copper development history, we can appreciate that its quality requirements had been constantly evolved, so that currently refined copper has an extremely high quality standard, that allows its direct use in the production of ultra-thin cables and other products applied in the industry. In each stage, refined copper production has fostered the development of technology used in their treatment. Similarly, cathode processing technology has been evolving to minimize treatment costs in order to generate a wire rod for several uses, ranging from power cables to super conductors. In this sense, to the already known type of fusion processes of the Southwire or Asarco type (capacities over 80 kt / year), wire rod production processes of the Upcast or Rautomead type (capacities between 20-50k t / year) have been added. They immediately deliver oxygen-free wire rods. In both cases, we can conclude that the clients' requirement had evolved from a chemical criteria focus, to considering more subjective aspects, such as visual control as the first stage of inspection.

Jan 1, 2019

By John G. Henning

Low quality rock is encountered in many manifestations in underground hard rock mines, ranging from weak and poorly consolidated rock to highly altered or foliated rock. Lateral mine developments driven in low quality rock pose on-going challenges to a mine operator, as ground stability issues, such as caving of under-supported ground, drift closure due to surface deformation or buckling processes, and degradation of exposed rock surfaces are a persistent concern. For many operators, ground support design is an iterative process, as support practices are refined with time. Using case studies from a variety of underground hard rock mines, this paper reviews techniques for the classification of low range rockmasses and examines the rationale and effectiveness of adopted ground support systems.

Oct 1, 2010

By C. R. Edwards, D. R. G. Watt

"Equity Silver Mines Ltd. a member of the Placer Development group of companies operates Canada's largest silver mine near Houston in north-central British Columbia. Initially, the silver-gold-copper flotation concentrate contained excessive levels of antimony and arsenic, so a leach process was installed to remove undesirable metals and provide improved smelter terms for the leached concentrate. The leach plant which has been fully described elsewhere (1, 2, 3), was forced by deteriorating process economics to shut down in April 1984. Equipment was mothballed and alternate uses sought.The Endako Mines Division of Placer Development Limited, located some 150 kilometres east of the Equity mine site, shut down its molybdenite mining and milling facilities in the spring of 1982. Endako has continued to produce molybdic oxide (molybdenum trioxide or MTO) via intermittent roaster runs, and also a high purity, lubricant grade molybdenum disulfide in the Ultrapure Plant. With the steel industry in the doldrums, molybdenum chemicals present an alternate and growing potential for molybdenum sales. In 1982 Placer Development began testing this market. Molybdenum chemicals were produced in the United States on a toll basis using Endako MTO as process feed. The transfer of this production to Canada was being considered when Equity's leach plant shut down, and it was noted that most of the equipment and skills necessary could be provided by the leach plant. See Figure 1.A careful investigation of process requirements was completed by engineering and production staff at Equity and Endako. A provisional capital and operating cost estimate was made, and it was decided to perform a test run during July 1984. There were strong reasons to proceed with this project. A positive cash flow was expected for both Endako and Equity. Endako would have product to continue to expand in the molybdenum chemicals market with the added selling point that now the complete production process would be under direct control of Placer Development companies. Equity would further benefit since a portion of the leach plant would continue in operation thus maintaining and exercising our hydrometallurgical engineering and operating skills. Finally, Equity would have a base from which to search out other processes adaptable to the idled leach plant equipment."

Jan 1, 1986

By A. Kraly, M. Complojer, P. Paschen, K. Gamweger, H. Antrekowitsch

Increasing quality of aluminium alloys and continuous optimization of the production process leads to an improvement of the gas purging systems. The application of porous plugs for the treatment of liquid aluminum is nowadays not widely used in the aluminium industry especially in Europe. The Department of Nonferrous Metallurgy and the Christian Doppler Laboratory of Secondary Metallurgy of Nonferrous Metals intensified the research and development of refining and alloying processes by gas treatment during the last years. CFD-modeling supports these experiments, which should lead to lower hydrogen content, lower suspended particles and a better distribution of alloying elements in the melt. Different parameters such as temperature, bubble size, gas amount and which kind of gas is used influence the quality of the products.

Jan 1, 2006

By M. R. P. Snow

"This paper outlines geotechnical conditions that commonly exist in underground, hardrock mines and the challenges posed for ground-support steel, specifically rockbolts, used in these environments. A model is proposed whereby the in-situ stress and rock-mass classifications (based on Bieniawski’s rock mass rating) form the basis of determining the desired steel properties of the rockbolts used. Based on the ASTM F432 bolting specification, recommended minimum steel properties are defined for three ranges of in-situ stress levels, each with their own six ranges of RMR values. Heat treatment for the steel can be specified once these minimum steel properties are known.RÉSUMÉ Le présent article décrit les conditions géotechniques qui existent fréquemment dans les mines souterraines de roches dures et les défis que cela pose pour le soutien de terrain en acier, plus spécifiquement les boulons d’ancrage utilisés dans ces environnements. Un modèle est proposé dans lequel les contraintes in situ et les classifications de la masse rocheuse (selon la classification de la masse rocheuse de Bieniawski) servent de base pour la détermination des propriétés désirées pour l’acier des boulons d’ancrage utilisés. En se basant sur les spécifications de boulonnage de l’ASTM F432, les propriétés minimales recommandées pour l’acier sont définies pour trois plages de niveaux de contraintes in situ, chacune avec sa propre plage de six valeurs de classification de la masse rocheuse (RMR). Un traitement thermique pour l’acier peut être spécifié une fois que ces propriétés minimales pour l’acier sont connues."

Jan 1, 2016

By Dirk van Zyl

The world is consuming more and more electronic products every year. This has caused a dangerous explosion in electronic scrap (e-waste) containing toxic chemicals and heavy metals that cannot be disposed of or recycled safely. But this problem can be avoided. We are pressing leading electronic companies to change; to turn back the toxic tide of e-waste. Every year, hundreds of thousands of old computers and mobile phones are dumped in landfills or burned in smelters. Thousands more are exported, often illegally, from the Europe, US, Japan and other industrialized countries, to Asia. There, workers at scrap yards, some of whom are children, are exposed to a cocktail of toxic chemicals and poisons.

May 1, 2008

By K. Mayhew, A. Lossin, H. Salomon-de-Friedberg

"The proportion of arsenic-bearing copper concentrates that supply the copper industry is on the increase. The current strategy of miners and smelters to blend feeds to reduce average arsenic levels is rapidly becoming unsustainable as more concentrates with even higher arsenic levels enter the marketplace. In addition, the capability of smelters to manage increasing arsenic levels to more stringent and restrictive environmental standards is limited by available process technologies.CESL Cu-As Technology is a viable technical and economic alternative to traditional smelting. It offers the advantage of simultaneous leaching and precipitation of the arsenic in a single processing step while achieving high copper extractions. The process has been piloted in six separate, fully-integrated pilot campaigns for feeds ranging from ~1% to 12% arsenic in concentration. This paper will focus on the behaviour of arsenic in CESL’s leaching/precipitation step and operational factors that influence it, and on the chemical and physical characteristics of the subsequent iron-arsenic residue that represents today’s best available technology from a long-term sustainable (capital/operating costs, metal recovery, safety, environmental) perspective.The examples provided will demonstrate copper extractions approaching 99% and arsenic deportment to residue of 99%. Instantaneous settling rates of the residue were measured at 15+ m/hr. Data from subsequent short and long-term stability testing of the residue confidently support the view that the scorodite-bearing residues from the process will be stable and provide an acceptable arsenic management practice. The technology offers increased revenue and environmental certainty for miners, smelters & refiners to support the development of metallurgically challenged copper-arsenic deposits. Furthermore, results will be presented demonstrating the technology’s ability to successfully incorporate hazardous arsenic containing smelter by-products such as dust into the process feed and simultaneously extract copper value while fixing the arsenic in a stable residue."

Jan 1, 2016

By H. K. Olsen, B. Thomassen, H. K. Schønwandt, L. Grahl-Madsen, H. Stendal

Abstract-The central part of the early Proterozoic Ketilidian orogen in South Greenland consists of an I-type granitoid batholith transected by four regional NE-SW-trending shear zones. The batholith was probably emplaced during subduction, from the south toward the Archaean craton in the north, in a sinistral transpressional system. A regional sediment sampling program covering 5000 km2 shows a close connection between a gold-mineralized trend and one of the major shear zones within the epizonal facies of the batholith. The gold mineralization is not directly related to the major shear zones, but occurs in quartz-veined and silicified second-order structures. High-grade (up to 114 ppm Au over 6 m) low-tonnage mineralization is found within these second-order structures cutting both amphibolites and granitoids. The mineralization is characterized by negligible or small alteration halos. Gold is associated with various element combinations of enhanced As-Bi-W- Cu, which indicate that the mineralization is mesothermal in origin.

Jan 1, 1995

By H. K. Olsen, B. Thomassen, H. K. Schønwandt, L. Grahl-Madsen, H. Stendal

The central part of the early Proterozoic Ketilidian orogen in South Greenland consists of an I-type granitoid batholith transected by four regional NE-SW-trending shear zones. Thebatholith was probably emplaced during subduction, from the south toward the Archaean craton in the north, in a sinistral transpressional system. A regional sediment sampling program covering5000km2shows a close connection between a gold-mineralized trend and one of the major shearzones within the epizonal facies of the batholith. The gold mineralization is not directly related to the major shear zones, but occurs in quartz-veined and silicified second-order structures. High-grade(up to 114 ppm Au over 6 m) low-tonnage mineralization is found within these second-order structures cutting both amphibolites and granitoids. The mineralization is characterized by negligible or small alteration halos. Gold is associated with various element combinations of enhanced As-Bi-W-Cu, which indicate that the mineralization is mesothermal in origin.

Jan 1, 1995

By K. Sawamukai, S. Ogasawara, D. Umenai, T. Tsuruta

"Removal of cobalt, strontium or cesium ion from the aqueous solution containing each metal ion only using microorganism was examined. Arthrobacter nicotianae which had a high ability to remove cationic metal ion was used for the removal of each metal. The removal of cobalt, strontium or cesium using A. nicotianae cells was affected by the solution pH, concentration of metal ion, and cell amount. The effects of above mentioned factors on the removal of each metal and time course of strontium from the solution containing each metal only using A. nicotianae cells were reported in this paper. INTRODUCTIONRadioactive elements, such as cesium, iodine, strontium, plutonium, barium, cobalt, lanthanum, yttrium, and tellurium, were detected around Fukushima Daiichi nuclear power plant, which was damaged by the magnitude 9.0 earthquake and the tsunami followed.The removal of radioactive elements from contaminated sources is a worthwhile subject to investigatein terms of environmental control. Research efforts have been especially concentrated on studying microorganisms that remove uranium including bacteria (Andres et al, 1993, Hu et al, 1996, Marques et al, 1991, Strandberg et al, 1981), actinomycetes (Byerley et al, 1987, Friiss and Myers-Keith, 1986, Golab et al, 1991), fungi (Byerley et al, 1987, Galun et al, 1983a, Galun et al, 1983b,Tsezos and Volesky, 1981, White and Gadds, 1990) and yeasts (Strandberg et al, 1981, Schmate II et al, 1978).We have investigated removal and recovery of uranium from aqueous systems using microorganisms isolated from uranium mines. We identified some strains of bacteria with extremely high uranium removing abilities (Sakaguchi et al, 1996), and thus, the microbial biomass may be considered as an adsorbing agent for the removal and recovery of uranium and heavy metals present in aqueous systems around Fukushima Daiichi nuclear power plant.In the present study, we screened various species and strains of bacteria, actinomycetes, fungi, and yeasts for their ability to adsorb uranium (Tsuruta, 2002). Basic features affecting uranium adsorption?co-existing cations and anions, cell amounts, pH, and the adsorption time course?by Arthrobacter nicotianae cells, which adsorbed the largest amount of uranium, were also investigated. In addition, we examined the removal of an other actinoid element, thorium ion, which may be present with uranium in refining effluents.In this paper, the removal of cobalt, strontium, or cesium from the solution containing each metal ion using A. nicotianae cells is discussed."

Jan 1, 2012

By Zia Pirzada

"Time is of the essence" and "Time is money" These are powerful and true statements during a project life cycle and have far-reaching implications on the success and failure of the project Time and progress management is crucial to the project success. Project delays may increase the cost to an unacceptable level and may render the project as economically unfeasible. On the other hand, if the project is completed on time or earlier than as planned, it may generate economic benefits greater than what had been envisioned To take advantage of the financial opportunities and to improve the cash flow as well as Return On Investment (POI), project schedule can be accelerated to complete the project earlier than planned Project schedule acceleration can be achieved by using analytical tools, such as "Schedule Optimization", "Schedule Reduction", "Schedule Compression" or a combination of any of these concepts along with the "Planning for start up". Schedule optimization does not entail any extra cost, however, other acceleration methods, such as Schedule Reduction and Schedule Compression, may require extra expenditures from the owner. Based on the forecasted early start of the revenue stream, the extra expenditure could become a worthwhile venture with a very high rate of return To accelerate the schedule, all aspects of the project should be reviewed with acceleration costs calculated. All risks and opportunities should be evaluated and taken into consideration to determine if the acceleration is feasible and advisable and will provide definite financial advantages Sometimes schedule acceleration may be desired to prevent the company from paying liquidated damages. This is especially true when the project is not expected to complete on the contractual completion date and when the cost of acceleration is less than the liquidated damages that may accrue against the company.

Oct 1, 2010

By J. Bhattacharya, S. K. Mukhopadhyay, S. K. Pal

"While time and again many authors have categorically stressed the restoration of the environment, very little effort has been made in the mineral industry to develop the economy of environmental control. There are many abatement procedures that search a maze of variants. Among them pricing environmental damage seems to be more logical and easily implementable.IntroductionMining as an operation has a severe impact on the Earth's natural resources. While economical environment control is much sought after, solutions are often varied and complex, and can differ in the problems of single or multiple mine sites.Determination of Optimum use LevelsIn “mining environmental control"" it is required to strike a balance to find optimum use levels. The solution is to find where the welfare benefits equal the cost involved to curb the degree of environmental damage (Fig . I) . In the mining industries this can be done by modifying the production/extraction process itself. For most pollutants, the marginal costs of control will exceed the benefits from further reduction of damage long before the zero pollution damage point is reached (Fig. I). From an economic perspective the optimal alteration of environment by mining would occur at z; pollution continues to be caused by ""zy"" control units, but it would be inefficient to pursue the redemption efforts further because the marginal cost involved would exceed marginal welfare benefits."

Jan 1, 1992

By R. D. MacEchern, M. C. Rockwell

"This paper describes the research and tests carried out to recover the readily available barite from the tailings produced by the Nystone Chemical Ltd. operation at Debert, N.S. The tailings comprised 70-80% of the original feed and contained about 20-25% Baso4 .The objective of the research, undertaken during 1982, was to produce a barite concentrate which would meet the American Petroleum Institute (API) barite requirements for use in drilling mud. Samples from the tailings pond were examined and analysed to determine the tailings characteristics.Preliminary test work was performed on the tailings samples using a Haultain Superpanner, Wilfley tables and Humphrey's spirals. The grade of the barite concentrate retrieved did not satisfy the API barite requirements.The fineness of the tailings and the fact that approximately 80% of the barite was contained in the -200 mesh (0.074 mm) size fractions, indicated that flotation of barite from the tailings might be successful."

Jan 1, 1984

Terrane?s Canadian Assets Mt. Milligan, British Columbia Copper, gold (100%) Berg, British Columbia Copper, molybdenum (100%) Howards Pass, Yukon/NWT border Zinc (Option payments, and Royalty interest) Maze Lake, Nunavut Gold (Joint venture with Laurentian Gold Fields)

May 1, 2010

By J. Olaf Sund

"THE November issue of the Bulletin carried in it ""Origin of the New Bruns1viclc Gypsum Deposits"" by J. Olaf Sund. This paper was a digested account of a Master's thesis at the University of New Brunswick which was a very useful compendium of information of gyp-sum in New Brunswick. It was a warded the President' s Gold .Medal and the First Prize in the Graduates' Section of the Students' Essay Competition. The present writer presents his congratulations to the winner of the competition. At the same time he must comment on the use of certain terms and on certain conclusions presented in the paper.The term ""unconformable"" has been used in several places in the paper to describe the relationship of gypsum to anhydrite in various deposits in New Brunswick in a sense which is quite alien to the accepted meaning. It has long been known tl1at the gypsum at the surface or near the surface in deposits in the Atlantic Provinces has come from hydration of anhydrite by surface and ground waters. The gyp-sum must be looked upon then as an alteration or even a weathering product. It cannot in this sense be called ""unconformable"" and thus arguments using the word in the accepted sense are invalid."

Jan 1, 1960

By Pierre Labrecque

Dispatch systems have been used for open pit mining since the early 1980?s but similar systems do not widely exist for underground mining. There is a need for developing dispatch systems for underground mines, particularly highly automated operations such as block caving. An innovative method, Agent Based Modeling (ABM) for a dispatch system for a block caving operation, is proposed in this paper. The model is based on a particular behaviour observed in social insects. The focus of the ABM dispatch system is adaptability with respect to changing operational conditions and effective integration of maintenance modules with the operation. The paper will show the advantages of this innovative method compared to existing similar systems. Furthermore, the preliminary approaches for developing an agent based modeling system for block caving operations are highlighted and discussed in this paper. 1. Introduction In social

May 1, 2008