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By Frank Martonhegyi

"The objective of this paper is to review the coal basins in the Canadian part of the Western Cordillera to aid their understanding, and to aid in finding and proving places of economic coal mining potential. Coal occurs in eugeosynclinal basins in the Western Cordillera which evolved through three stages: -from systems of volcanic arcs in the Late Jurassic to mid-Cretaceous; -through an intermediate stage with deposition in increasingly restricted successor basins in Jurassic to Early Tertiary; -to a continental stage by the Eocene. Minor coal seams occur usually in late volcanic arc stage sediments bur they can be locally thick as they are on Queen Charlotte Islands. Successor basins usually show a marine-paralic-limnic evolurion. Signijicanr coal deposits occur in the tarter two sequences in the Whirehorse (Tantalus) and Bowser (SkeenaSusrur) basins. Currenr activities are intensive in the more accessible Bowser Basin, for example at Telkwa, Susrut River and on the Groundhog coal field. On Vancouver Island major coal seams occur in cyclic sediments, but the more accessible deposits are mined our. Exploration renewed recently in the less accessible northern part of the Island, for example Quinsam, for surface mineable coal. The Western Cordillera is a mosaic of allochtonous tectonic blocks. They originated from the south and were displaced northward by several hundred kilometres. Many Tertiary coal basins are related to strikeslip transcurrent faults along which the later part of displacement took place, for example the Dawson coal area in the Tintina Trench. Tensional and dipslip normal faulting also created or enhanced sites for thick peat accumulation. For example at Hat Creek 280 m of coal occur in a 550 m section. Secondary structures are often better exploration targets than the main fault zones. Pluvial and alluvial fan environments away from the main drainage are usually the favourable sites for thicker and cleaner coal deposition."

Jan 1, 1985

By Georges Houlachi, Akram Alfantazi, Michael Mahon, Maysam Mohammadi

Corrosion resistance of the lead-based anodes directly influences the purity of the final product in the zinc electrowinning process. The anodic MnO2 layer that is electrodeposited on the anodes during this process can protect the anodes against corrosion. Sand-blasted anodes generate a uniform, adherent and shiny MnO2 layer, which gradually blisters and eventually sloughs off after several weeks. In this study, we attempted to develop a new method to stabilize the MnO2 protective layer on the anodes during the electrowinning process by providing suitable nucleation sites for electrodeposition of this layer. MnO2 particles (P80=40µm) were used as seed material for this purpose. Different techniques of galvanostatic and cyclic voltammetry polarizations, scanning electron microscopy (SEM) and atomic absorption spectroscopy (AAS) were employed to investigate the performances of the MnO2-seeded lead anodes. The experimental results showed that growth of the MnO2 layer is influenced by the MnO2 seed particles on the anode surface. The MnO2 layers electrodeposited on the MnO2-seeded lead anodes were uniform and strongly adherent to the substrate. This layer was more stable than those formed on the PbAg anode without MnO2 seeding. This could provide the anode with a higher level of corrosion protection. Moreover, formation of undesirable MnO2 mud in the electrolyte and the rate of manganese consumption were decreased when the MnO2-seeded lead anodes were polarized. These observations could be attributed to the different properties of the electrodeposited MnO2 layer on this anode in comparison with that formed on the PbAg anode.

Jan 1, 2016

By William A. Price

The objective of this paper is to outline the approaches used in British Columbia to address the challenges posed by metal leaching and acid rock drainage (ML/ARD). Challenges include the large financial costs, the need for site-specific assessments, the large information requirements, the need for mitigation measures to be designed and financed in a manner that permits long-term performance, the lack of long-term operating experience, the ongoing changes in many important processes, the need for pro-active detection and resolution of concerns, difficulties in predicting the potential for ARD or significant metal leaching, the need for new tools, and the multidisciplinary, highly specialized nature of the work. Consequently, mines must be planned, operated and closed in a manner that permits regular review, detailed monitoring and adaptive management. Proper consideration of the challenges involved, including a plan of how all outstanding concerns will be addressed, studies to address areas of significant uncertainty and caution in the absence of the required understanding, should ensure environmentally safe practices in the future.

Nov 1, 2002

By V. Ramachandran

The successful advent of solvent extraction (SX) reagents for copper recovery and improvements in electrowinning of copper to produce LME grade A copper cathode have paved the way for the hydrometallurgical treatment of copper oxide and low grade sulfide ores. This has resulted in about 25-30% of the world's copper being produced today by the Leach-SX-EW process. The obvious next step was to develop processes for the hydrometallurgical treatment of copper sulfide concentrates, as an alternative to a typical smelter-refinery complex. The current paper updates the processes that have been developed to date with emphasis on processes that are being commercialized or that are seriously under consideration for commercialization. Most of the discussions relate to the hydrometallurgy of chalcopyrite concentrates, which account for about 70% of the world's known copper reserves. In summary, in the last thirty years, the hydrometallurgical treatment of copper sulfide concentrates has attained full maturity and will be a serious option to contend with while evaluating any future new copper plant.

Jan 1, 2007

By Melinda Bissinger, Frederic Berube

Environmental considerations are important in the aerospace industry. To that effect, several elements such as engine emission, noise and materials are identified by the industry and the society as requiring significant improvements for future and current products in order to be aligned with current expectations. In this context, the industry is addressing this opportunity by investing significantly in new engineering solutions that will meet greener targets. To this effect, the impact of material choice is significant and will make a difference in the forth coming solutions. Several opportunities to develop more efficient products, quieter aircrafts using materials and manufacturing processes that will be more respectful of environmental considerations exist. The presentation will cover those elements and provide an overview of the upcoming solutions.

Jan 1, 2010

In-Country Business Development Agenda ?Siting/Permitting/Operational Planning ?Securing, maintaining, enhancing social license to operate ?Biodiversity conservation and ecosystem services ?IFC Performance Standards ?Environmental, Social, Risk Governance (ESG) ?Climate change plan

Aug 1, 2013

By Jamel Sgaoula

During 1998 COGEMA Resources Inc. announced that operations at the Cluff Lake mine will be suspended indefinitely by the end of year 2000 as a result of deteriorating uranium market conditions. To remain profitable, Cluff Lake mine started an aggressive cost reduction program. A cost reduction team was formed to look for ways to lower production costs. The focus of this team was to screen all areas and to come up with ideas to improve the economy of the mine and ensure the viability of the operations over the remaining three years of operations. Among the areas where significant savings were achieved are: (1) replacement of portion of cement with fly ash in backfill; (2) backfill optimization; and (3) new shotcrete plant installation on site for bulk in-house shotcrete production. This paper details the research work carried out by Cluff Lake mine on these projects and results of its application.

May 1, 2001

By R. Browner, J. Collard, D. Ibana

The extraction of cobalt from synthetic pressure acid leach solutions of nickel laterite ores by the direct solvent extraction route using ESPLIM is reported. It first explored the use of gaseous ammonia as pH modifier and then the variables that affect the dispersion of the aqueous phase in the organic phase such as ionic strength, viscosity of the phases, initial droplet size, etc. were explored so that phase hold-up and thus extraction can be effectively controlled. The results show that the technique allows better control of phase dispersion circumventing one of the main weaknesses of conventional solvent extraction.

Jan 1, 2005

By L. Henry Smith, David C. Arthur

"The Williams Mine is Canada’s largest gold producer, with annual production of 450 000ounces from 2 300 000 tonnes of ore. Highly mechanized and automated underground mining practices are employed in order to achieve and maintain high levels of productivity and minimize costs.The mine ventilation system is modified to include a new vent raise and variable pitchvane-axial fan. This addition allows several fan installations underground to be decommissioned. A substantial net savings in installed horse power is achieved.Heating costs associated with under-ground ventilation air are a significant portion of mine operating costs. Air heating costs are substantially reduced by recovering heat from upcast exhaust air, minewater and compressor cooling circuits. This waste heat is used to supplement propane fired air heating systems for underground ventilation air. An additional benefit is the availability of a heat sink for summer cooling of the compressors.System design, energy savings data and payback calculations are presented."

Jan 1, 1996

By Luis Bergh, Juan Olivares, Juan Durán, Juan Yianatos

"In the last decades heuristic approaches based on logic rules have been one favored tool to control flotation units and plants on top of distributed control systems. Fundamental knowledge on flotation processes, expressed in reliable models, and programs to assure the quality of the information, contained in available measurements, are still insufficient to develop robust predictive control strategies. In this paper the idea of using simplified models, when a known disturbance is coming into the process, is explored. As a first approach, the set points of the froth depth and air flow rate controllers are estimated based on this model. Since these target predictions are only approximate, a conventional feedback expert system, based on logic rules, continues the task of calculating the set points of the distributed controllers, in order to decrease the gap between actual and desirable metallurgical targets. This combined actions permitted a fast response of the process to change the operation of the circuit when a measured disturbance is detected. This control system was implemented and experimentally evaluated in a pilot rougher flotation circuit, with three pneumatic cells, with froth depth and air flow rate controllers in each cell. Since the circuit is operated for the air-water system, a phenomenological model, with parameters estimated from industrial data, is fed on-line with real operating variables and virtual values, characterizing the feed (grades, solids%, particle size distribution), in order to predict the metallurgical targets (recovery and concentrate grade). Several cases are discussed showing the benefits of this control system and the possible improvements to work on. INTRODUCTIONToday, large size mechanical flotation cells of 100 to 300 m3 are used in rougher operation in different flotation industrial plants, in Chile and worldwide. However, in spite of the advances in fundamental research and the notable growing in equipment size, with more complete instrumentation systems, there are still a lack of reliable data for industrial flotation modeling and simulation to advance in better control systems design."

Jan 1, 2016

By Robert J. McCarthy

There are two things on everyone's lips when mining folks gather these days - one is the exciting business opportunities that now exist for mine development and expansion, and the other is the dire shortage of human resources needed to design, manage, and even operate the mines. Years of stagnant industry growth, limited employment opportunities, and unwarranted perceptions of remote and harsh working conditions have caused mining to be a less than desirable career choice. Attrition and reduced entry to the workforce has resulted in shortages for not only mining professionals, but also skilled trades people and operators. Consequently, to survive, let alone grow, mining companies, suppliers, and educators are all pursuing innovative solutions with technology, inter-industry recruiting, centralized services, and strategic partnerships. This paper describes some of these initiatives and proposes others, now that the people are gone!

May 1, 2008

By D. H. Schwarz

The performance of proton exchange membrane (PEM) fuel cells depends on catalyst layer composition and structure. Experimental observations reveal that state-of-the-art catalyst layers consist of microporous agglomerates of carbon-supported catalyst sites bound together by polymer electrolyte. In between the agglomerates are macropores which provide pathways for the transport of gaseous reactants. In this work, three-dimensional, multicomponent and multiphase transport computations are performed using a computational fluid dynamics (CFD) code (FLUENTTM) with a new PEM fuel cell module, which has been further improved by taking into account the detailed composition and structure of the catalyst layers using a multiple thin-film agglomerate model. In this model, it is assumed that thin films of polymer electrolyte and liquid water surround the catalyst sites. The results of CFD computations show that transport limitations associated with the thin film of polymer electrolyte and the presence of liquid water in the catalyst and gas diffusion layers have substantial negative effects on PEM fuel cell performance. Also, the results of computations with variable distributions for a given precious metal loading show that, in general, uniform catalyst loading provides the best fuel cell performance.

Jan 1, 2005

By A. Montini, M. H. Moys

"A conductivity probe mounted in the shell of the mill has been used to measure the behaviour of the load in the mill as a function of operating variables. It was found that certain properties of the conductivity signal correlate strongly with the per cent solids of the slurry passing through the mill; in particular the angular location ?D of the shoulder of the load is an increasing function of the per cent solids. A method for measuring the viscosity of the pulp discharging from the mill has also been developed. The use of the measurements in mill control is illustrated by simulating various control strategies for open circuit milling. It is shown that the use of ?D allows very tight but imprecise control of the slurry rheology in the mill, while the use of viscosity is subject to severe limitations in speed of response. A cascade control system involving both measurements provides adequate control of slurry rheology within the mill. Applications to closed circuit milling are discussed.IntroductionMultivariable control of milling circuits continues to receive a lot of attention in the literature. Hulbert and co-workers and Niemi, et al. have described the use of Inverse Nyquist Array (INA) techniques while Herbst has recently described the use of Optimal Control. It is significant that in neither of these three projects was any variable associated with the grinding mill itself (e.g. power or properties of the mill discharge) used in the control strategy. Pauw, et al.do, however, use mill power in their multivariable peak-seeking controller for pebble-mill control. Little work has been published on the use of measurements of the properties of the slurry being discharged from grinding mills, in spite of the fact that milling efficiency is known to be strongly affected by slurry rheology».Moys has recently developed a technique for measuring the dynamic behaviour of the load in the grinding mill. This method involves the monitoring of the response of a conductivity probe mounted in the shell of the mill which gives a measurement of the orientation of the load inside the mill. It was found that the load behaviour was strongly influenced by slurry rheology. In this project a technique was also developed for the measurement of the viscosity of the slurry in the mill discharge. It was, thus, decided that it would be worth investigating the use of these measurements in mill control schemes since direct control of the slurry rheology in the mill must inevitably increase the efficiency and productivity of the grinding circuit as a whole.This will be done by using the dynamic responses measured by Moys and Montini to simulate the behaviour of an open circuit ball mill. While the control of open circuit mills is of little interest, this simulation provides a simple but powerful demonstration of the advantage provided by these measurements, advantages which should apply to closed circuit operation of any mill type (including autogenous milling). Investigations into multivariable control of a closed circuit ball mill are currently nearing completion and will be published soon."

Jan 1, 1987

By J. C. Moreno, G. Rios, M. Palacios

The Huelva smelter was commissioned in 1970 coinciding with the shutdown of the old smelter in the Rio Tinto mine site. That new smelter consisted of two Momoda blast furnaces with a capacity of 500 dmtpd of concentrate. Nevertheless, soon after their start-up, it was clear that an increase in the smelting capacity was needed. After an analysis of the existing alternatives at that time, the flash smelting technology was chosen. The new Outokumpu Flash Smelting Furnace (FSF) came into operation on 18 September1975, with an initial capacity of 900 dmtpd of concentrate, using four Venturi-type burners and preheated atmospheric air. Since that date the Huelva Smelter team, together with Outokumpu (now called Outotec), have continuously improved our FSF design, process conditions and operational practices, leading to a present capacity of 3,500 dmtpd of concentrate. Since 1975, five smelting campaigns have been completed, the last ending in November 2013 with the rebuilding of the original FSF hearth. This paper describes the history of these improvements and the lessons learned.

Jan 1, 2014

By L. Treadgold

The KOV, Kananga and Tilwezembe copper-cobalt deposits in the Democratic Republic of the Congo have lain dormant for over ten years due to lack of funding by the State-owned mining company, Gecamines. Nikanor Pic through its operating company DCP has secured the mining titles from the DRC government and has commenced redevelopment of these large copper deposits. DCP plans to produce 250,000 tonnes per annum of LME Grade "A" copper cathode and up to 30,000 tonnes per annum of cobalt salts. This paper describes the geology, re-development of the KOV mine and the two smaller mines, Kananga and Tilwezembe, the design of a new copper-cobalt processing facility and the challenges in refurbishing the associated infrastructure.

Jan 1, 2007

By Martin Irving

Adding Value to Canadian Diamonds - A Changing Diamond Industry - Diamond Mining - Diamond Manufacturing - Diamond Jewellery Markets - NWT Diamonds Changing Diamond Industry - De Beers ? privatization - Oppenheimers (45%), Anglo-American (45%), Botswana (10%) ? going retail - LVMH joint venture - New Players ? jurisdictions - Canada ? companies - BHP-Billiton - Aber Diamonds

May 1, 2002

By J. Manchisi

This study has investigated the use of blast furnace slag as functional adsorbent for metal ions in acid mine drainage treatment. This opportunity has not yet been developed into a practical process partly because of limited understanding of rates and mechanisms of adsorption process and inconsistency in interpretations of adsorption data. The overall objectives were to determine the efficiency and mechanisms of sorption process of metal ions in a multiadsorbate system. We employed standard materials characterisation techniques to analyse composition, structure and surface morphology of the slag. Batch adsorption experiments were then conducted to study the mechanisms, kinetics and efficiency of metal sorption as a function of pH, phase ratio, mixing time, mass and particle sizes of slag. Both XRF and adsorption data suggested the slag to possess acid neutralising capacity. This slag is non-crystalline based on XRD pattern, has adequate porosity and pore volume comparable to similar commercial adsorbents but it has inferior pore structure, pore size distribution and BET surface area to be effective under wide applications. Metal sorption increased with decrease in slag particle diameter, decrease in initial metal concentration and increase in the mass of slag. Although slags have demonstrated to efficiently treat low concentrations of single and multiadsorbate effluents using fine particle sizes, they have limited capacity to treat multiadsorbate systems for some metal ions. This is probably due to low affinity, competitive adsorption or limitation in material?s adsorptive properties. Sorption mechanisms probably involve precipitation and ion exchange on the basis of alkaline pH and exchangeable slag surface ions. Sorption preference is proposed as Fe2+>Cu2+>>Cd2+>Co2+>Mn2+. Despite these limitations, deeper understanding of sorption behaviour of metal ions by slags for application in dilute and large volumes of effluents is necessary where precipitation and other standard techniques are either inefficient or uneconomic. Thus, this study has established that sorption capacity of slag to remove metal ions from acidic effluents is selective, limited to certain metal ions and for other ions only at low concentrations. Further adsorption studies in multiple solutes under various experimental conditions or those that can propose an economic slag activation process are needed that improves or widens adsorption window.

Aug 1, 2013

By R. A. Mantz, V. N. Balbyshev, A. N. Khramov, N. N. Voevodin

Corrosion protection properties of the hybrid organo-silicate coatings on aluminum substrate can be significantly improved by means of encapsulation of organic corrosion inhibitors within the coating material. In order to achieve sustained release of corrosion inhibitor and long-term corrosion protection, a secondary chemical equilibrium of either ion-exchange interaction with the coating matrix or cyclodextrin-assisted molecular encapsulation of the inhibitor has been employed. Several organic corrosion inhibitors, such as mercaptobenzothiazole, mercaptobenzimidazole, mercaptobenzimi¬dazolesulfonate, and thiosalicylic acid have been examined by a group of electrochemical methods including potentiodynamic scan, electrochemical impedance spectroscopy, and scanning vibrating electrode technique. It has been found that the formulations that contain ß-cyclodextrin demonstrate superior corrosion protection capabilities as the complexation equilibrium results in a continuing delivery of inhibitor to corrosion sites. The approach is considered a promising way for active corrosion protection of high-strength aluminum alloys when integrity of barrier coating is compromised.

Jan 1, 2004

By A. M. L. Cushing, S. Kelebek, A. Ghahreman

Iron sulfides are part of many ore deposits affecting flotation separation of non-ferrous base metals from them. Open-circuit potential (OCP), potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) measurements were carried out with pyrite and pyrrhotite electrodes to investigate their reactivity under various flotation conditions, which involved the use of TETA, SMBS, and their combination. TETA was found to adsorb on the electrode surfaces causing a significant increase in charge transfer resistance of the product formed, which was most significant at OCP. This effect is much less with SMBS, indicating its greater surface reactivity compared to TETA. The combined use of these reagents decreases charge transfer resistance to a greater degree than that experienced with their individual uses. Addition of Cu2+ as a potential activator to this system nearly eliminates the action of TETA on the electrode surface, which can be attributed to sequestration/chelate formation in liquid phase. The relative effects of these reagents on pyrrhotite electrode are similar to that of pyrite. The main difference between the pyrite and pyrrhotite electrodes is that the observed charge transfer resistance on the pyrrhotite surface with each reagent case is significantly lower by 3 to 4 fold. This is compatible with its anodic nature and ease of oxidation since the OCP value of pyrrhotite is lower than that of pyrite. Results are discussed in relation to flotation/depression behavior of these iron sulfide minerals in mineral separation processes.

Jan 1, 2017

By I. Govender

Positron-Emission-Particle-Tracking (PEPT) has enabled the non-invasive observation of charge and slurry transport in model mills under operational conditions. We use high quality PEPT data to infer that the charge motion can be effectively described by a non-Newtonian granular fluid. An improved theory for slurry transport, including inertial effects, is presented.

Jan 1, 2012