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By Franco Chiesa, David Levasseur, Bernard Duchesne

A 500kg aluminium AlSi7Mg03 casting has been poured and the metallurgical quality at different locations inside the casting has been thoroughly investigated. It included measuring the local tensile properties (YS, UTS, El) in the T6 condition, the dendrite fineness (DAS) and the level of microporosity. A correlation was found between the microporosity level, the local solidification time and solidus front velocity; this correlation allows to predict the porosity level in large aluminium castings (solidification times between 20 and 200 minutes). Quite expectedly, properties varied widely within the casting and the actual mechanical properties were much less than the "textbook values" based on measurements carried out on separately cast standard specimens. A correlation between the secondary dendrite arm spacing (DAS) and the local solidification time was in keeping with previously published data. Finally the conditions to obtain an acceptable finish on machined surface were determined.

Jan 1, 2014

By Z. D. Hora

has been no commercial production of either perlite or pumice in British Columbia. Several promising occurrences are known to exist but their development has been delayed due to difficult access and / or remote locations. The Empire Valley perlite deposit is located 120 km east of Clinton. The deposit appears to be a flat-lying volcanic flow 50 to 70 m thick that is part of an Eocene rhyolite and dacite volcanic assemblage. The Francois Lake perlite deposit occurs on the north shore of Francois Lake where perlite is part of a rhyolitic volcanic sequence. The exposure of perlite is about 13 m thick and is considered to be Eocene or Oligocene in age. The Uncha Lake perlite deposit is located about 5 km south Industrial Minerals in Canada of Uncha Lake. Perlite appears to be intercalated with porphyritic rhyolite flows that are comparable to those at Francois Lake. Showings are widespread but poorly exposed and thicknesses are unknown. The Mount Meager pumice deposit is located in the Lillooet River valley at the base of Plinth Mountain. Coarse pumice agglomerate forms a large talus slope that is undercut by the river. Unsorted, angular fragments up to 50 cm in diameter are intermixed with up to 30 per cent of sand and silt-sized particles. The exposed zone is about 200 m long and 50 m high; it is being considered as a source of lightweight aggregate.

Jan 1, 1984

By Alex Luyima, Michael Moats

"In the present work, the oxidation of manganous and chloride ions on a mixed metal oxide (MMO) anode from a 40 ºC electrolyte containing 160 g/L sulfuric acid (H2SO4) with various concentrations of Mn2+ and Cl- was studied using cyclic voltammetry. These results indicated that Mn2+ concentration does not affect Cl2 evolution on a non-MnO2 coated MMO anode. However once MnO2 deposits on the MMO anode, Cl2 evolution is inhibited. The effects of manganous concentration and chloride concentration on the amount of MnO2 deposited in one hour were also evaluated. Cl- concentration did not affect the amount of MnO2 generated. Increasing Mn2+ concentration resulted in an increase in the amount of MnO2 deposited.INTRODUCTIONThe electrolytic recovery of zinc (Zn) is a well-known process and is estimated to produce approximately nine million tons of Zn per year worldwide (Recendiz, Nava, Lartundo-Rojas, Almaguer, & Gonzaleza, 2009). The Zn produced by this process is of high purity and has a wide range of applications, such as galvanizing (car body parts, pipes, metal wires, etc.), sacrificial anodes in offshore industries, casting alloys, alloying of brass, primary and secondary battery industries, etc.The electrochemical production of Zn employs aluminum cathodes and lead-silver anodes (Pb- Ag) (Recendiz et al., 2009). The Zn containing mineral (ZnS) is usually associated with other elements such as Mn, Mg, Ca, Cd, Cu, Cl, Fe, F, Co, Ni, Al, As, Sb, Si, Sn, Ge, Hg etc. (Nijjer, 2000). After processing of ZnS concentrates, the electrolyte obtained still contains residual metallic and non-metal impurities. Some of these impurities can impact the corrosion rate of Pb-Ag anodes."

Jan 1, 2016

Ni and samaria-doped ceria (Ni-SDC) cermet are desirable materials for making a solid oxide fuel cell anode working at intermediate temperature (800°C or lower) due to its good ionic/electronic conductivity at the reduced operating temperature. An advantage of the use of a Ni-SDC anode is the enlargement of the effective reaction zone in the interfacial area between the anode and the electrolyte. As a result of the mixed ionic/electronic conductivity of the anode, the electrode reaction rate is enhanced. Investigations into the properties of the ceria-based anode reveal that the performance of the anode is closely related to its microstructures, which are dependent on the composition and fabrication conditions of the ceramics. In this paper, a method for quantitative characterization and correlation of Ni-SDC cermet microstructures to the performance of an anode is investigated. A series of Ni-SDC anode samples are prepared by screen-printing (SP) and spin-coating (SC) techniques, and different microstructures of the samples are obtained through controlling the SP or SC conditions and the sintering temperature. Individual phases (Ni, SDC and pore) in the tri-phase boundary (TPB) microstructures in the electrode are differentiated and segmented from each other in optical and SEM images based on the differences in refractivity and atomic contrasts among the phases. The geometric properties of the segmented phases are characterized using image analysis methods, so that a quantitative skeleton illustrating the TPB microstructures of the Ni-SDC electrode is obtained. Statistical analysis of the distribution of the three phases in the TPB microstructures is performed and the relationship of the microstructures with the optimum electrode is interpreted in terms of the microstructure analysis data.

Jan 1, 2005

By Rodney S. Read

Both crystalline and sedimentary rocks are being considered to host a deep geological repository (DGR) for nuclear fuel waste in Canada. In the past several decades, considerable research has been conducted around the world to better understand geomechanical processes associated with development and long-term performance of a DGR. The Nuclear Waste Management Organization?s (NWMO?s) technical research and development program is examining a number of potentially suitable rock formations to support implementation of Adaptive Phased Management, Canada?s approach for long-term management of nuclear fuel waste. Rock engineering will play an important role in siting, design, and construction of a DGR for nuclear fuel waste. Post-construction activities such as excavation maintenance, monitoring, decommissioning, and closure will also involve rock engineering. The type of host rock selected for a DGR will influence the scope of rock engineering activities and related research requirements. This paper outlines key rock engineering aspects to be considered in developing a DGR in sedimentary rock.

May 1, 2009

By C. Sorel

The PAREX code has been developed since the nineties by CEA and AREVA to describe the PUREX process implemented in the French fuel reprocessing plants. It enables the calculation, either in steady or transitory states, of the behaviour of the different elements of interest at each process step. The high customized structure of the software allowed the implementation of various phenomenological models describing solvent extraction systems dedicated to uranium purification from crude ore to spent fuel. After qualification of the implemented models, the code was used to perform the design of flowsheets, for safety demonstration analysis or for operational assistance.

Aug 1, 2010

By T. S. Wanne

Tunnel sealing experiment (TSX) was conducted between 1997 and 2004 in the Canadian URL located in Manitoba. In the experiment, a tunnel was excavated parallel to the maximum principal stress direction, filled with sand and sealed with bulkheads at both ends. It was then pressurized and heated by injecting hot water. The rock mass response was monitored with seismic methods. The main interest in the numerical simulation was the damage formed during the heating phase. The large-scale PFC2D models replicated a central plane- strain section of the TSX chamber. The models captured the first-order phenomena observed in-situ displaying the difference in the damage in the roof and floor regions, respectively. This difference was due to the filling material confinement of about 100 kPa on the tunnel floor, which occurred in the course of the heated experiment.

May 1, 2009

By Mohammed Rachek

Résumé : la mine d?Elhammam, opération du groupe minier Marocain Managem, est située au sud de la ville de Meknes à 63 km, elle exploite un gisement de fluorine depuis 1974. La minéralisation se présente sous forme de deux filons principaux orientés N45° avec un pendage variant de 65 à 90° NW, entre ces deux filons on note la présence d?une succession de filons satellites sécants. La méthode d?exploitation pratiquée depuis le démarrage de la mine est celle des chambres magasins, elle assure une cadence d?extraction annuelle de 250000 tonnes. Cette méthode favorisée par une très bonne compétence mécanique des épontes de la minéralisation a offert à l?exploitation une rentabilité très satisfaisante grâce à son faible coût mine. Les travaux de recherche géologique menés en parallèle à l?exploitation ont permis la découverte d?un nouveau secteur ?K-Est Gouaïda? (KEG) qui fait l?extension nord-est du gisement principal, la minéralisation de ce secteur se présente sous forme de deux filons très étendus latéralement (900 m d?extension) et présentant une puissance minéralisée irrégulière et très faible 1.2 m en moyenne, les épontes de la minéralisation sont constituées de schistes de qualité mécanique très faible. Vers la fin des années 1990, l?exploitation s?est orientée vers le développement minier du secteur KEG. Ce développement consiste à faire le choix adéquat de la méthode et de l?infrastructure minière pour l?exploitation de ce nouveau secteur, KEG. La méthode des chambres magasins, pratiquée dans le gisement principal avec un faible coût mine, n?est pas praticable dans le nouveau secteur à cause de la qualité de ses terrains, l?irrégularité de la morphologie de sa minéralisation et de la faible puissance des ses filons. Seule la méthode des tranches montantes remblayées (TMR) peut être applicable techniquement vu les spécifications suscitées de la nouvelle minéralisation, la TMR doit être appliquée sous sa variante mécanisée pour faire face au niveau exigé de la production. Après le pilotage de l?exploitation par TMR mécanisée dans le secteur KEG, il a été confirmé que cette méthode donne une grande satisfaction en matière de stabilité des terrains, sécurité, sélectivité, productivité et récupération du gisement, néanmoins elle reste pénalisée par un coût mine trop élevé pour garder le niveau de rentabilité recherché par l?exploitation d?un produit de faible valeur marchande telle que la fluorine. Dans l?objectif de rentabiliser l?exploitation du secteur KEG qui représente en réserves l?équivalent d?une durée de vie de 4 à 5 ans et d?assurer la pérennité de l?activité, l?exploitation en collaboration avec Reminex, la filiale d?ingénierie de Managem, a adapté une nouvelle variante de la TMR mécanisée dite TMR avec plan incliné sur remblai. Cette nouvelle variante de la TMR consiste à réduire au maximum les travaux dans le stérile en reconstituant un plan incliné sur le remblai à l?intérieur des filons pour faire évoluer en vertical l?exploitation des tranches en montant vers la tête d?un panneau de minerai. La variante des tranches montantes remblayées mécanisées avec plan incliné sur remblai a été imaginée et appliquer en 1978 dans la mine de fluorine de Burc située au Sud-Ouest de la France (Sicard et Mailloux, 1983). Imaginée pour une cadence annuelle de 30000 tonnes et une mécanisation très modérée cette variante a été adaptée par l?exploitation de la mine d?Elhammam en 2002 pour un haut degré de mécanisation et une cadence d?extraction annuelle de 250000 tonnes de minerai. Cette variante de la TMR est appliquée depuis le début de 2003 dans les chantiers du secteur KEG, elle présente les mêmes avantages techniques que la TMR mécanisée classique et elle a permis la réduction du volume des travaux d?infrastructure de 17.65 m à 6.25 m de travaux par 1000 tonnes de minerai. Ceci s?est traduit par une baisse du coût technique de la mine de 34% ce qui a donné un nouveau souffle à la mine pour assurer sa production et pour poursuivre la recherche géologique d?éventuelles zones à mettre en valeur.

Oct 1, 2004

By J. B. De Hart

In the September issue of the Bulletin, 1923, there is a paper by J. A. H. Church on "The Spontaneous Combustion of Coal in Mines", which is more or less a general discussion of the subject. Mr. Church gives a list of mine fires which have occurred in Alberta. Of the total of thirteen fires, six are attributed to spontaneous combustion. Of these six fires, it will be noted that five are in thick pitching seams. These fires occurred in the following mines during the years shown, at Frank in 1909; at Lovett in 1916; at Cadomin in 1920; at Yellowhead in 1922, and at Cadomin in 1923. Every one of these fires has occurred, as Mr. Church points out, in a seam of over 12 feet in thickness, and furthermore not one of these fires has been extinguished, although in every case large sums of money were expended and considerable risks . taken in fire fighting. Now it is quite evident from these facts that mines working seams of this nature are faced with a very grave danger and it behooves us to study the matter and endeavor to arrive at some practical method of preventing the loss of our coal mines from this cause.

Jan 1, 1924

By P. R. Stephenson

Mining projects depend on the amount and quality of the mineral reserves, which in turn depend on the amount and quality of the mineral resources. Only Measured and Indicated Resources may be converted to mineral reserves and Inferred Resources may not, with certain exceptions, be used in economic studies. Responsibility for the estimation of mineral resources rests with the Qualified Person (QP) and there is a wealth of literature, text books and case studies to guide the QP. Responsibility for the classification of the mineral resources also rests with the QP. While there is some industry guidance and common practice on approaches to resource classification on which the QP can draw, the process is (or should be) heavily dependent on the exercise of judgement by the QP. However, this inevitably leads to situations where, for example, one QP?s Inferred Resource is another QP?s Indicated Resource. If the QP?s judgement is poorly reasoned or illogical (as is sometimes the case), it can have a major impact on the project, often with substantial cost or value implications. Project managers and company executives should not unquestioningly accept QP?s classification decisions and should apply the same intensity of due diligence that they apply to other critical elements of the project.

May 1, 2011

By A. Probst, J. A. Finch

"Solids concentration (weight % solids) profiles and the clear liquid/slurry interface level (mud-line) were determined from conductivity measurements in thickeners at Falconbridge's Strathcona mill (Ni concentrate and non-mag thickeners) and Kidd Creek Division (Cu, Zn concentrates and final tails in the concentrator and a jarosite thickener in the Zn plant).The conductivity measurement system consisted of a probe 1.5 m in length with 23 electrode cells, a 24-channel relay, a conductivity meter and a computer. A conductivity profile is collected which locates the mud-line by a sharp change in conductivity. The conductivity measurements are readily converted to solids concentration profiles using a model due to Maxwell.The results from conductivity measurements were compared with direct measurements on local samples obtained using a modified Noranda sampler.It is concluded that the conductivity technique is applicable to locate the mud-line and to estimate the solids concentration profiles in thickeners. This on-line informnation could improve the operational efficiency of industrial thickeners."

Jan 1, 1994

By P. Amelunxen, E. Herrera, L. Hill, J. Vanderbeek

It is well-known that the particle breakage mode that occurs in a semi-autogenous mill is significantly different from that which occurs in a ball mill, enough so to warrant very different lab scale breakage tests and scale-up models. This phenomenon, at the plant scale, leads to changing process constraints depending on the particular properties of the ore. For example, hard or coarse ores might bottleneck the SAG/AG mill throughput, while the ball mills might constrain throughput when milling soft or fine ores. Because the power draw of a ball mill is fairly constant compared to that of a SAG/AG mill, periods of SAG/AG mill bottlenecks lead to increased ball mill circuit specific energy consumption and a finer grinding circuit product size, which together constitute a loss of efficiency of the overall process. Because HPGR circuit throughput is less sensitive to changes in ore hardness, this situation is less common or severe in those circuits. Furthermore, the ball mills are somewhat decoupled from the upstream crushing circuits through the use of surge bins, which also helps to mitigate this effect. As a result, ore hardness variability constitutes a significant cost penalty that should be applied to SAG mill/ball mill/pebble crusher SABC circuits when evaluating the relative economics of different grinding circuit configurations. Nevertheless, the issue is by-and-large ignored, because most current HPGR trade-off studies are based on averaged ore hardness parameters. This paper provides an estimate of the magnitude of this penalty for a typical operation by using Monte Carlo simulation methods and plant data from Freeport-McMoRan’s autogenous, semi-autogenous, and HPGR-based comminution circuits. A case study from an in-house 96K t/d sulphide project is presented to illustrate the concept. It was found that by including variability effects, the trade-off NPV of the HPGR circuit over that of the SAG mill circuit increases to $84 million from negative $33 million, effectively reversing the original decision of selecting a SAG mill circuit for the fixed hardness case.

Jan 1, 2012

By G. B. Bosworth, M. J. Lake, J. W. Hogg

The Quintette Coal operation in northeastern British Columbia has one of the world's largest Preparation Plants, with a design capacity of 6.5 million tonnes per year of clean coal.This paper will discuss several innovative aspects of the flowsheet and plant design with particular reference to the selection of process equipment, materials handling and control systems.The operations and maintenance experience during the first two years of production will be described and discussed in relation to the design objectives.

Jan 1, 1987

By P. Mottahed, J. Ran

Mining practice and research have shown that the jointed roof in stratified rock behaves like a voussoir beam structure with strength greater than that determined by the continuous beam theory. Previous studies have demonstrated the voussoir beam mechanism and developed methods to estimate the crushing and buckling strength of voussoir beams. However, research on voussoir beams with multiple mid joints has not been suffICient and problems such as the voussoir beam support and applications of the voussoir beam mechanism to the mining environment have not been addressed. In this paper, mechanism of voussoir beams containing multiple mid joints and truss support are studied and applications of the voussoir beam mechanism to underground mine openings are discussed based on the numerical and experimental results.

Jan 1, 1995

By Emmanuel Henry

The Kiruna Mine, operated by Luossavaara-Kiirunavaara AB (LKAB), is a large-scale sublevel caving operation located in Arctic Sweden. Iron ore is extracted at a rate of 60 000 tpd from a four-kilometre long, 80-100 m thick and 60-degree dipping orebody. Actual production depth is 800 m under the top of the footwall and about 550 m under the average regional ground level. Because no support is left between the footwall and the hanging wall and despite the relatively low mining depth, extraction results in the formation of a huge stress shield modifying the original stress field and concentrating it just beneath the mining level. Effects of stress concentration on the rock mass are monitored through field observations and a seismic system. Severe stress-induced deterioration of openings is visible to a certain radial distance from the mining level: pillar crushing and fault slips are more and more common and extended. The seismic system, installed in collaboration with CANMET, confirms the field observations and completes them in the rock mass: fault slips and major seismic events are recorded. The system proves its effectiveness to outline the extension of the dynamic response of the rock mass, which actually seems much larger than field observations let think.

May 1, 2001

By Richard P. Taylor, Rod Henham

Abstract - Newly discovered pegmatites distributed throughout the sub-surface environs of the Musselwhite Archean gold deposit occur as narrow dikes that intrude most of the major lithological units. The mineralogy and textures of the pegmatite dikes are characteristic of granitic pegmatites of the "Rare-Element Class"; more specifically, they closely resemble varieties of the "Complex-type" granitic pegmatites that are commonly associated with zones of tantalum mineralization. The essential minerals in the dikes comprise albite, quartz, and K-feldspar, together with lesser amounts of mica (including lepidolite), spessartine, tourmaline, and locally, spodumene. Fine-grained (30 µm to 300 µm), tantalum-bearing minerals occur in the quartzo-feldspathic matrix of the dikes as disseminations, in interstices, and in small vugs. The nature of the tantalum-bearing mineral assemblage present in individual pegmatite dikes varies from a simple mineral assemblage composed of ferrocolumbite (with around 39 wt% Ta2O5) in the most northerly dike, to more complex assemblages comprised of manganotantalite (with up to 75 wt% Ta2O5), ferrotapiolite (with up to 79 wt% Ta2O5), and microlite (with up to 76 wt% Ta2O5) that are present in dikes located several kilometers to the south and southwest. The compositional characteristics and textural relationships of the tantalum-bearing minerals in the dikes provide evidence of igneous fractionation trends that are typical of rare-element granitic pegmatites. Such trends suggest that the newly discovered pegmatites represent part of a more extensive group of cogenetic, tantalum-mineralized dikes.

Jan 1, 2001

By Kernaghan Webb

Organization of Presentation ?Genesis, Premise, Hypothesis ?Background ?Methodology ?Key research questions ?Research Team to Study Kinross Maricunga ?Research Milestones ?Chilean context ?Chilean Legal Framework ?Kinross Gold the basics, CR approach, Maricunga ?Issues, Perspectives ?Concluding remarks

May 1, 2010

By Pierre Laliberté

Objectifs ?Quantifier les économies d?énergie potentielles liées àl?utilisation de différentes technologies ?Créer un modèle permettant d?évaluer les économies possibles d?énergie en combinant plusieurs technologies ?On ne peut simplement additionner les pourcentages d?économie individuels pour en évaluer le total.

Feb 1, 2008

By Behzad Vaziri Hassas, Firat Karakas, Esra Tanisali, Mehmet S. Çelik, Ahmad Hassanzadeh

Coagulation is basically an aggregation process where particles settle under the influence of interfacial forces with electrostatic forces playing a governing role. Although particle morphology consisting of shape and roughness dictates the physical encounter of two particles, their eventual coagulation is not only influenced by columbic forces but also other interfacial forces such as hydrophobic interaction, which affects the extent of aggregation of particles through increasing the distance of interaction. Roughness is well known to increase the effective contact angle on hydrophobic surfaces and also enhance interfacial forces. In this study, the effect of morphology of particles and particularly roughness on the settling velocity and in turn coagulation tendency was investigated. Batch settling tests (BSTs) of different particle morphologies were investigated as a function of pH. Two different morphologies of silica particles were utilized with the same particle size distribution (PSD) including smooth-spherical and rough-spherical (Etched). Rough particles were prepared by acid etching technique using hydrofluoric (HF) at different time intervals (15-300 sec). Etched samples were identified and quantified by optic profilometry. Settling test results showed that the settling velocity of particles in a suspension of 2% solids in the massive settling region is significantly affected by particle morphology of the suspension. Coagulation results further revealed that aggregation of rough particles is faster than smooth-spherical particles. Coagulation results are elucidated on the basis of particle morphology and its effect on distance of separation through hydrophobic forces.

Jan 1, 2016

By R. Bruce Ferguson

"The Kettle River Operation of Echo Bay Minerals Company is located about thirty kilometers north of the town of Republic in northeastern Washington State. In tum, Republic is about a hundred and seventy kilometers north and a little west of the city of Spokane, Washington. It is also about fifty kilometers south of the town of Grand Forks, BC, Canada. At this time it is the only gold mining and milling operation in the State.Tailings are stored in a double lined, zero discharge facility. It became evident in mid 1996 that the rate of free water accumulation in the tailings pond was going to result in the level in the pond reaching its permitted freeboard elevation long before the solids plus pore water capacity was reached.We then embarked on a mission to manage tailings pond water on several fronts: reduce fresh water usage in the process, divert spring seeps and surface runoff and install a system to enhance evaporation.IntroductionThe Republic area is an historic gold mining district. Hecla operated its Republic unit from 1892 until closure in 1994. The Kettle River Operation processing plant is located in the San Poi! river valley at an elevation of just under a thousand meters. The facility consists of a ninety thousand ton ore storage pad as the mines are remote and truck haulage is subject to interruption due to weather and road restrictions, jaw and cone crushing with screening, rod and ball milling to an eighty percent passing size of seventy five microns. This is followed by preaeration with high purity oxygen supplied by a vacuum pressure swing adsorption plant plus lead nitrate addition to achieve passivation of the sulfide mineralization such as chalcopyrite, pyrite and pyrrhotite. Conventional cyanide leaching and carbon in pulp adsorption completes the loop. Tailings are treated with air/S02 to achieve cyanide destruction. Plant capacity is 1,815 tons per day. Our license requires that there be no detectable free cyanide in the tailings pond water and a maximum of forty parts per million weak acid dissociable cyanide. The operation started in 1989 with production from the Overlook Mine located about five kilometers further up the same valley at an elevation of twelve hundred meters, hence the location of the mill. Current mine production comes from Lamefoot in the Curlew Lake valley, about ten kilometers distant, and K2 in the Kettle River valley about fifty kilometers away. Both are at an elevation of about 800 meters. Lamefoot produces 1,360 tons per day and K2, 455. Both are underground operations."

Jan 1, 1998