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By D. Raicevic

After more than 93% of the uranium is extracted from Elliot Lake uranium ores by a sulphuric acid leaching process, the leach residue (tailings) contains small amounts of uranium and radioactive isotopes, particularly radium-226, which is the most serious health hazard. Heavy metal components and pyrite are also present, along with the gangue minerals. Currently, over /000 acres of the Elliot Lake area are covered with these tailings, which contain over five million tons of pyrite. Because of constant oxidation of the pyrite by bacteria (thiobacillus) and the presence of moisture, pyrite slowly generates sulphuric acid, which steadily leaches the metal-bearing constituents from the tailings. The seepage-flows of the dissolved contaminants, although often quite low in volume, have an environmental impact on the Elliot Lake area. Although these seepages are treated and most of the contaminants removed and impounded, a small amount of the radioactive contaminants reaches Lake Huron via the Serpent River. This paper describes a flotation approach for treatment of the Elliot Lake uranium tailings to produce new, decontaminated tailings practically free of pyrite, with radium, thorium and uranium contents considerably reduced. The decontaminated tailing produced, which comprises about 75% by weight of the current uranium tailings, appears to be suitable for mine backfill. Because mine backfilling normally uses about 50% of the plant tailings, the surface storage of about half of the uranium tailings, therefore, would be eliminated by this process. Mine backfilling would also increase the mine production and thus enlarge the over-all uranium resources due to recovery of the ore from pillars. The pyrite concentrate produced from the current uranium tailings would be suitable for sulphuric acid production. The possibility of uranium recovery, and disposal of radium and thorium from the concentrates produced, is now being studied at CANMET.

Jan 1, 1979

By K. Fumimura, T. Nishimura, M. Kohno

When applying numerical techniques to problems of deformation of rocks, the body to be analyzed is divided into small portions and is represented by a system of points linked together with the neighboring points. In the so-called distinct element modeling, the particles in the system are directly connected by springs and a contact law is used to specify forces on the particles to simulate the mechanical behavior of the body. The relation between the spring stiffness and commonly measured material properties, such as the Young’s modulus and the Poisson’s ratio, should be known a priori. For the general case of a random packing of particles, the relation is found by means of a process in which a system of particles and set of parameters are prepared to simulate a set of specimen-size test and then the input parameters are chosen to match the measured material properties. The validity of the numerical result is only demonstrated by comparison model behaviors with the measured responses. The process includes trial-and-error manner, therefore, no model is complete to reproduce the mechanical properties. In this paper, a relation between the spring stiffness and the elastic constants; the Young’s modulus and the Poisson’s ratio, is introduced to a three-dimensional distinct lattice spring method. Two simple numerical examples will be presented to demonstrate the performance of the method with the procedure for the determination of the spring stiffness.

Jan 1, 2015

By Chris Brothen

The introduction of new technology in mine operations has provided real opportunities for increased efficiencies and production gains which translate into enhanced profits. Computing and network technology usage has become integrated into surface mining operations and on average these investments in technology have proven beneficial for efficiency and productivity improvements. Embracing new technologies however, does not guarantee positive results. The expectations or improvements derived through the technology must be confirmed and clarified well before implementation. Tire Pressure and Temperature Monitoring Systems are an excellent example of an existing technology that can provide full time automated performance measurements of tires operating under harsh conditions and environments. Prompt warnings or alarms signaling when a tire has exceeded operating capacities will provide savings through lowered maintenance costs and increased productivity. To truly quantify the projected savings in tire life, fuel consumption, and increased levels of production, all costs associated with the technology, both direct and indirect must be considered. Apart from the initial cost of the system implementation, ongoing maintenance and support costs must be considered as well as the costs of system integration into existing mine operations

May 1, 2008

By A. Liard, H. Sommelet, G. Sauriol

"Description des études qui ant conduit à la conception spécifique du système de drainage de la mine à ciel ouvert. Les approches différentes sont examinées ainsi que la valeur du système recommande.IntroductionLa Division Mines Gaspé de Mines Noranda Ltée exploite un gisement de cuivre par mine souterraine et mine à ciel ouvert à Murdochville, Québec. L'exploitation par mine aciel ouvert a commencé en 1965 avec une operation à flanc de montagne. Elle se poursuit actuellement sous Ie niveau de la vallée dans une fosse dont Ie diamètre est de I'ordre de 800 m (2,600 pi), et la profondeur de 150 m (500 pi) sou s Ie fond de la vallee. Elle doit atteindre une profondeur de 360 m (l, 180 pi) sous Ie fond de la vallee , avec des murs hauts de 360 à 490 m et des pentes moyenne de 44°. Le rythrne d'extraction est actuellement de 85,000 tonnes par jour.Dans Ie cadre des etudes entreprises par les Services Techniques de la Division Mines Gaspé, la compagnie Géomines Ltée a été consultée pour étudier les conditions hydrogéologiques et hydrologiques locales et participer a la conception d'un système de drainage superficiel et souterr ain. Un tel systerne de drainage visait: a éviter les importantes venues d'eau qu i affectent I'exploitation en periode de crue; amaintenir les pressions hydrostatiques au sein des parois de la fosse dans les limites imposees par les etudes de stabilite des pentes réalisees par la Mine.Les principales étapes de cette etude ont porté sur: la collecte et la compilation des données sur la géologie, l'hydrologie et l'hydrogeologie du site; . la détermination des caractéristiques hydrauliques du milieu rocheux à partir d'études structurales et de test s de perméabilité;"

Jan 1, 1981

"Technological innovation is an extremely complex activity. The author presents his interpretation of innovation and the innovative process. He reviews the strategy used by participants in coal mining innovation in the past and discusses changes required to meet the challenges of the future.Introduction if an industry is to be successful and viable in today's world, the companies active within the industry must remain close to the frontiers of knowledge. The coal mining industry is no exception. Technological problems facing the coal mining industry are basically economic and social. Economic problems are those concerned with the long-term growth and profitability and social problems, with the health and safety of the mine worker and the impact of the mining operation on the environment.Technological innovation can be a key factor in meeting these problems successfully. The general belief is that the information base for technological innovation exists within mining companies and governmental agencies but current industrial and governmental strategies and structures impede the transformation of this knowledge into the mining products and processes required for growth.The purpose of this paper is to determine where Canada is in terms of coal mining on the innovative ladder. The paper as presented: defines innovation and innovative process; gives an historical ""broad brush"" review o f innovation in the industry; and suggests the challenges to be faced in the future."

Jan 1, 1985

By Neal Harries

Ground movement is normal in open cut mining operations, mainly caused by excavation response and blasting. Movement of the ground can be acceptable provided it is not unexpected and catastrophic. However, in steep mine walls and the very large open pits being developed today the consequence of slope collapse can be catastrophic. Such risks can be minimized at the planning stage by reducing slope angles, but this carries a very high cost. Also, instabilities which develop whilst mining can lead to ore reserves being quarantined, which represent a high cost to the mining operation. In spite of such safety measures, unexpected failures have occurred in the past. These issues motivated the development and production of the slope stability radar (SSR). There are currently over 80 GroundProbe SSR systems deployed in metalliferous and coal mines in 17 countries. The unexpected failure of rock walls at mining sites is a major cause of death and serious injury. Slope failure is also one of the major causes of economic and production losses. An unexpected wall failure can bury critical equipment. It also disrupts the mine plan. It is common to cease mining for several days or weeks following a wall collapse due to uncertainty over stability. Direct economic losses in remediation alone can easily exceed $1,000,000 per incident. The economic costs of injury or fatality are much higher including closure of mines during the incident investigation process. Massive wall failure can result in direct and indirect costs measured in millions of dollars. This paper will present some recent case studies of the SSR operation in open cut mines in North America, including Thompson Creek Mining Company (Idaho), Smoky Canyon Mine (Idaho), and a general case study on extreme cold weather use of the SSR.

May 1, 2009

By L. A. Homeniuk, R. Bonnar

"The Fond-du-Lac uranium deposit is located on the northern rim of the Athabasca Basin. The uranium mineralization is, for the most part, confined to the Athabasca Group, which is underlain by pre-Helikian metamorphic rocks of the Western Craton.The deposit is characterized by a remarkable train of mineralized glacial erratics which led to the original discovery. The mineralization is present as a ""high-grade"" core and a diffuse ""low-grade"" aureole. The ""high-grade"" core occurs as a stockwork of steeply dipping pitchblende veins which strike N 50°E. Hematite, siderite and secondary silicate are also abundant. The ""low-grade"" aureole contains uraniferous goethite, argillaceous material and rare carbon buttons. Recent alteration to coffinite has taken place along the margins of pre-existing ore minerals.The ""high-grade"" core is 390 m long and 10 to 40 m wide, and is surrounded by an irregularly shaped zone of ""low-grade"" mineralization with a similar length and a width of up to 350 m.Comparing the Fond-du-Lac deposit to other unconformity-type deposits, several important differences can be noted:1. Ninety per cent of the ore is above the unconformity, in the Athabasca sandstone.2. The deposit is not associated with underlying graphitic rocks or a major structure.3. The clay-rich alteration zone is not extensive around the Fond-du-Lac deposit.Although there are differences with other Athabasca unconformity-type deposits, the high-grade portion below the unconformity suggests a common origin.The ore deposit is postulated to have been formed from uranium-bearing solutions which entered the stockwork of fractures. Following the reduction in part of these solutions by pre-existing carbonaceous matter and pyrite and/or chemical reaction with pre-existing hematite, deposition continued as a result of decreasing temperature and pressure. Subsequently, minor supergene redistribution of the uranium has taken place."

Jan 1, 1982

By G. Ergin

The interactions taking place between Al-Mg alloys and the bed media during aluminum filtration are not yet well understood. These interactions were studied using the infiltration technique. The reaction interface was analyzed using different techniques such as SEM and TEM. Only spinel formation was observed at the interface regardless of the type of alumina and contact time. This paper discusses the results of the study.

Jan 1, 2004

By Rae Simpson

"This paper provides insight into the elements of computerized maintenance systems and identifies some of the factors which influence their effectiveness. The paper describes what to expect in terms of benefits and problems, the nature of effective computerized maintenance systems, some of the systems available and a process for selecting a system for your organization.The paper will be of interest to mining company executives and maintenance or computer personnel who are involved with, or contemplating, the introduction of computerized maintenance systems.IntroductionIn the drive to improve profits in an increasingly competitive world, mining companies are now using some of the most sophisticated equipment available. The introduction of large and complex equipment such as drag lines, haul trucks, and high-capacity milling equipment has resulted in order-of magnitude improvements in productivity. However, this productivity is now, more than ever, dependent on the continued operation of the equipment. A prolonged breakdown of a critical component can have a significant effect on companies' bottom-line results. As more technologically sophisticated equipment is introduced, maintenance costs become an increasingly important factor for mining companies.Fortunately, sound modern management principles are being used more often in maintenance departments. Progressive maintenance managers are turning to computers to help manage the myriad of details associated with running a maintenance organization.Some maintenance departments in larger mining operations would find it difficult, if not impossible, to operate at current productivity levels without their computer systems. Unfortunately, some other companies gain very little from their computerized systems and would probably be better off without them.How can you be sure that computerized maintenance will improve the maintenance picture for your company? What benefits can you expect to achieve? How do you go about selecting a maintenance system for your organization? These are some of the questions facing industry managers and executives today. In the following sections, we will provide some guidelines and insights to help address these challenges."

Jan 1, 1988

By A. Otsuki

"This paper discusses the primary collector adsorption onto a sulphide mineral in mixed collector systems to understand its adsorption mechanism. UV-vis measurements were performed to identify the primary collector concentration adsorbed on pyrite, and the adsorption kinetics under different conditions were compared to distinguish their difference between single and mixed collector systems. Small amount of secondary collector addition prior to the primary collector addition significantly improved the adsorption kinetics of primary one. The result was explained by the combination of two previously proposed mechanisms (i.e., different adsorption site mechanism and multi-layer product mechanism). This study showed UV-vis measurement as an effective tool to study mixed collector adsorption behaviour.INTRODUCTIONCollectors are surfactants composed of heteropolar molecules with a non-polar and a polar group (Lotter & Bradshaw, 2010). In a froth flotation process, the function of collector is to improve the hydrophobicity of target minerals and selectively float them with the aid of gas bubbles. Because of the chemical or physical attraction between the polar group and the mineral surfaces sites, collector molecules adsorb on the particle surface with the non-polar group assigned towards the bulk solution (i.e., water), thus the mineral particle surface becomes hydrophobic (Wills & Napier-Munn, 2006).Thiol collectors are major collectors widely used in sulphide mineral flotation. Potassium amyl xanthate (PAX), dithiocarbamate (DTC), dithiophosphate (DTP), mecaptobenzothiazole (MBT) are some common thiol collectors. Previous studies reported that some mixed collectors systems enhanced the flotation performance (e.g., Bradshaw, 1997; Bradshaw et al., 1998; Rao & Forssberg, 1997). Thiol collector mixtures are often used in the flotation of sulphide ores, and discussed with the synergistic benefits (Bradshaw et al., 1998) which include lowering the total collector dosage requirements, improving the sulphide recovery and the rate of flotation as well as the improving the froth characteristics. The current paper mainly considered the mixture between two thiol collectors (PAX and DTC, considered as a weaker and selective collector, and stronger and less selective collector, respectively (Bradshaw, 1997)) to further understand their adsorption mechanism that should assist in improving the flotation performance of refractory gold ore."

Jan 1, 2016

By Yves C. Lizotte, Malcolm J. Scobie

Blast fragmentation is affected by the physical and mechanical characteristics of the rockmass as determined by geology as well as the explosive energy, the partition of this energy, the actual amount of energy transmitted to the rockmass, the blast geometry and the detonation sequence. This paper reviews studies of the influence of geology on blast fragmentation, particularly structure, i.e. the in situ or inherent fragmentation arising from rock discontinuities. Prior structural studies have mainly been limited to comparing equivalent diameters of the in situ blocks with the size distributions of the blasted material. No criteria exist to integrate structure into blast design. This paper reviews on-going studies of the blasted fragment shape and size observed in different rockmasses aimed at analyzing geological control over blasting. Digital photoanalysis was applied {o measure size and shape distributions, to correlate results with block size distributions and shape parameters of the inherent fragmentation. An integrated and comprehensive fragmentation assessment procedure which accounts for geological control is proposed. The potential of this research is to provide a greater understanding of the true contribution of explosives to fragmentation, the effects of fragment shape on system productivity and the reduction of blast-induced damage.

Jan 1, 1994

By Arthur Lieu

Outline Removal mechanisms of Se and Mo in the Key Lake Bulk Neutralization circuit Bulk circuit Detail process modification in the Key Lake BN circuit Process performance after commissioning Objective Legacy effects of Se and Mo from the historical operation of Key Lake mill were shown to have an negative effect on the regional biota in the downstream environment. The water treatment circuit was not designed to remove Se and Mo from the effluent. Reduce Se and Mo concentrations in final effluent under0.028 0.028 ppm ppm and 0.3 and ppm ppm(CNSC regulatory limits).(limits).??????

Nov 1, 2011

By Aysan Molaei, Kristian E. Waters

"Solvent extraction is the one of the most common techniques for recovering metal ions from aqueous systems. However, it is not efficient in the extraction of low concentration metal ions from aqueous solutions. Predispersed solvent extraction (PDSE) is an alternative method for solvent extraction which implies colloidal liquid aphrons as extracting agents in order to reach higher interfacial area and lower reagent consumption. This work investigated important parameters in PDSE of nickel ions from dilute aqueous solutions by fractional factorial design of experiments. Four experimental parameters, the initial extractant concentration, initial surfactant concentration, equilibrium pH and phase volume ratio (organic to aqueous ratio) were investigated. The important parameters were determined as well as important interactions between these parameters. It was found that extractant concentration, phase volume ratio, and equilibrium pH are the most significant experimental parameters. However, the interaction between surfactant concentration and other parameters was determined as significant interactions.INTRODUCTIONNickel is one of the key components found in cars, mobile phones, rechargeable batteries, kitchen appliances, and steel industry (Anyadike, 2002). It is one of the most important metals produced by Canada which is in the five top nickel producers in the world. Despite a 24% decrease in the nickel prices from 2011 to 2014 the nickel global mine production increased by 36% between these years (U.S. Geological Survey, 2015; Nickel - Statista Dossier, 2015), which shows the increasing demand for nickel. This high demand leads producers to consider the production of nickel from low grade ores and other secondary sources such as process wastewaters. The removal of nickel ions from process wastewater is also important due to environmental considerations. Nickel is known to be a human carcinogen and it may cause serious lung and kidney problems, pulmonary fibrosis, gastrointestinal distress, and skin dermatitis if it exceeds the critical level (Borba et al., 2006; Fu & Wang, 2011)."

Jan 1, 2016

By P. Mottahed, E. K. S. Passaris, J. Q. Ran

"The jointed roof of underground mine openings in stratified rock can be analyzed in terms of a voussoir beam. Because of the essential indeterminacy of the structure, previous attempts of theoretically solving the equilibrium equation have been unsuccessful. Numericalanalysisby the finite element method taking the geometrical and joint non-linearity into consideration combined with the experimental method has been adopted to study the performance isopara of the voussoir beam. Deformation and failure mechanism is analyzed in relation to the failure modes. Equations are proposed to estimate the elastic buckling strength and the crushing strength of the voussoir beam and to verify the failure mode of shear sliding. For application of the mechanism of the voussoir beam in mining operations, methods are described to predict the stability of a jointed roof and to design the dimensions of mining openings.IntroductionThe roof stability of an underground mine opening has direct effects on the selection of support methods, opening dimensions and, more importantly, on the safety of mining personnel. The prediction of the roof stability can be of importance in the design of a mining method and in mining operations. The jointed roof of mine openings in stratified rock can be stable under transverse load depending on the roof geometry and properties of the roof material and joints. The stability of this type of roof can be analyzed in terms of a voussoir beam which was introduced by Evans (1941) to study the strength of underground strata. Brady and Brown (1985) analyzed the voussoir beam and suggested that the mechanism of the voussoir beam could be used in the design of underground mine openings in stratified rock instead of the traditional continuous beam theory."

Jan 1, 1993

By Friedrich Benthaus

"The natural and man-made realities on either side of the Atlantic are different. Therefore, a large part of the other side' s knowledge and experience cannot be transferred easily. In the following, the author will attempt to describe some of those developments in the German hard coal industry which may be of particular interest to readers on this side of the Atlantic.The area of the Federal Republic is quite small, especially if compared with a country as large as Canada. On a territory the size of the maritime provinces of New Brunswick and Nova Scotia, Germany holds coal reserves roughly corresponding to the total Canadian reserves. More than 20 billion tons of hard coal down to a depth of 1500 m, and more than 30 billion ton s of brown coal of lignite are technically and economically extractable acording to current technology.However, not only are Germany's coal resources more concentrated; the country is also densely populated, and there are dense networks of railroads and highways All components of the so-called infra-structure are available everywhere, be it electricity, any machinery or personnel. Public opinion is likely in favour of an increased utilization of coal.The coal industry is well developed through a long evolution covering centuries. As a consequence, there is an effective and intensive cooperation of numerous bodies and institutions concerned with coal mining, from government agencies including the inspectorate to suppliers, trade union s, producing companies, to jointly operated management and research organizations. In the Federal Republic, hard coal is mined in deep mines only, and lignite in general, only from open-cast pits. There is a complete organizational and geographic separation of hard and brown coal in Germany. Because the Federal Republic holds only insignificant mineral oil and very little natural gas deposits, coal is essentially the only and consequently the most valuable source of energy."

Jan 1, 1984

By L. A. Homeniuk, R. Bonnar

"The Fond-du-Lac uranium deposit is located on the northern rim of the Athabasca Basin. The uranium mineralization is, for the most part, confined to the Athabasca Group, which is underlain by pre-Helikian metamorphic rocks of the Western Craton.The deposit is characterized by a remarkable train of mineralized glacial erratics which led to the original discovery. The mineralization is present as a ""high-grade"" core and a diffuse ""low-grade"" aureole. The ""high-grade"" core occurs as a stockwork of steeply dipping pitchblende veins which strike N 50°E. Hematite, siderite and secondary silicate are also abundant. The ""low-grade"" aureole contains uraniferous goethite, argillaceous material and rare carbon buttons. Recent alteration to coffinite has taken place along the margins of pre-existing ore minerals.The ""high-grade"" core is 390 m long and 10 to 40 m wide, and is surrounded by an irregularly shaped zone of ""low-grade"" mineralization with a similar length and a width of up to 350 m.Comparing the Fond-du-Lac deposit to other unconformity-type deposits, several important differences can be noted:1. Ninety per cent of the ore is above the unconformity, in the Athabasca sandstone.2. The deposit is not associated with underlying graphitic rocks or a major structure.3. The clay-rich alteration zone is not extensive around the Fond-du-Lac deposit.Although there are differences with other Athabasca unconformity-type deposits, the high-grade portion below the unconformity suggests a common origin.The ore deposit is postulated to have been formed from uranium-bearing solutions which entered the stockwork of fractures. Following the reduction in part of these solutions by pre-existing carbonaceous matter and pyrite and/or chemical reaction with pre-existing hematite, deposition continued as a result of decreasing temperature and pressure. Subsequently, minor supergene redistribution of the uranium has taken place."

Jan 1, 1982

By Wenbin Zhang, George W. Poling

"Prior or simultaneous addition of ammonium sulphate can, not only enhance the activating effect of hydrosulphide ions on xanthate flotation of malachite but it can also eliminate possible detrimental or depressing effects of excess residual hydrosulphide . Use of relatively inexpensive ammonium sulphate appears to reduce the consumption of the much more expensive sulphidizing agent for optimal flotation recovery INTRODUCTIONOxidized copper minerals float poorly with conventional thiol-type collectors. This is believed to be due to the nonadherent character of the collector coating, which is readily re- moved by particle abrasion. Rosas and Polingr reported emulsion flotation seemed capable of resisting abrasion during the flotation of non-sulphide copper ores. It appears that the most common flotation technique for oxidized copper minerals comprises sulphidization with Na .S and subsequent treatment by sulphydryl collector. The principles of this method are available . Malghan recently reviewed the studies on the role of sodium sulphide in the flotation of oxidized copper, lead and zinc minerals.It is well known that in the sulphidized flotation of malachite, the activation process depends strongly on the concentration of the sulphidizing agent, i.e., insufficient sulphide gives poor recoveries because of inadequate sulphidization; excessive sulphide also causes poor recoveries due to the depressive effect of the residual hydro-sulphide ions in solution. A major difficulty in sulphidization, especially with a varying feed nature, is to establish and maintain the optimum sulphide concentration in solution. In plant practice, vigorous control of sodium sulphide is required and stepwise addition of the reagent is recommended to improve the efficiency of the process. Soto and Laskowskim have found that malachite, depressed by an excess of sulphide ions, can restore its floatability if air or oxygen is introduced to the pulp. They attributed this to the oxidation of the HS - ions on the surface of the mineral. Jones and Woodcockuvi showed that a sulphide ion selective electrode could be used to optimize the conditions (e.g . amount of hydrosulphide, sulphidization time, flotation time) more readily and precisely than existing methods in the flotation of oxidized copper ores."

Jan 1, 1989

By Seungwoo Park, Whuisu Shim, Roe-Hoan Yoon, Kaiwu Huang

"A comprehensive froth model has been derived from first principles. It is based on predicting the kinetics of film thinning in the presence of particles of varying sizes and surface hydrophobicity. According to the Reynolds lubrication theory, the thinning of a horizontal film is driven by the excess film pressure (p), which is determined by the capillary pressure (pc) and the disjoining pressure (II). In the presence of particles, macroscopic capillary pressure (pc) is affected by the local capillary pressure (pc,local) in the vicinity of a particle and the number of particles in the film (N1,film), which in turn vary with the hydrophobicity and size of the particles. The Reynolds equation corrected for pc,local and N1,film is then used to predict the time (or froth height) at which a film is thinned to a critical rupture thickness (hcr), which in turn can be predicted using the Vrij’s capillary wave model (1966) after a modification to incorporate the contributions from hydrophobic disjoining pressure (IIhp). The model can predict bubble coarsening represented by the bubble size ratio between the top (d2,t) and bottom (d2,b) of a froth as functions of particle size and hydrophobicity, ? -potentials, frother dosages, froth height, gas flow rate, salt concentration, etc. The model predictions have been verified in experiments.INTRODUCTIONFroth flotation is regarded the best available technology today for upgrading minerals and coal fines. In the pulp phase of a flotation cell, air bubbles collect hydrophobic particles dispersed in it and rise to enter the froth phase on the top. Once in a froth phase, the bubbles coalesce with each other and become larger, resulting in a decreased bubble surface area. Under conditions of limited surface area, less hydrophobic particles drop off the bubble surface and return to the pulp phase. Thus, bubble coarsening provides a useful mechanism of increasing product grades. On the other hand, uncontrolled coarsening results in a decrease in bubble carrying capacity and hence throughput."

Jan 1, 2016

By P. W. Percival, J. J. Janssens

"Whitehorse Copper is a 2600-ton-per-day underground copper mine located within the city limits of Whitehorse, Yukon . In early 1978, due to increasingly difficult ground conditions. it was decided to investigate the conversion from longhole open stoping to vertical crater retreat mining. On-site crater testing by C-I-L demonstrated the feasibility of V.C.R. mining at Whitehorse Copper.After some investigation. a down-the-hole drilling rig was chosen and drilling began in November /978. Blasting began in June /979. and to September 1980 approximately one million tons of ore had been blasted. In-field changes to both drilling and blasting techniques have been implemented. Some of these changes were dictated by problems encountered; others were made to improve efficiencies.To date. V.C.R. mining has proven successful from a drilling and blasting aspect.IntroductionWhitehorse Copper Mines Ltd ., a division of Hudson Bay Mining and Smelting Co., Limited , is a 2600-Lp.d. underground copper mine. The plant site is located I mile west of the Alaska Highway, and approximately 7 miles south of Whitehorse city center. Production is from the Little Chief orebody, and total output is from vertical crater retreat stopes.The Little Chief and Middle Chief orebodies at Whitehorse Copper had original reserves in excess of 6 million tons, most of which graded 2.00/0 copper or higher . The orebodies are typical skarn deposits that have developed along the contact between an intrusive diorite and a limestone-quartzite flank pendant. The limestone has been metasomatized to form a calcium-magnesium skarn which, along the limestone / quartzite contact, has locally further developed into a mineralized magnetite-serpentine skarn. The principal copper minerals are bornite and chalcopyrite, with minor chalcocite and valleriite. Skarn gangue minerals are serpentine, diopside, garnet, epidote, calcite and wollastonite. Appreciable values in gold with some silver are present and recovered as well."

Jan 1, 1981

By R. Ghomashchi

Wear, fatigue and corrosion are the most widely encountered modes of failure in materials used in engineering applications, including aero-gas turbines. Although wear is distinctly classified as adhesive, abrasive, erosive, fretting and so on, there are usually more than one wear mechanism involved in the failure of components in service because there are many systems and materials variables active in materials wear that makes it more difficult to study. This is further complicated by the discrepancies between the results of laboratory tests and field data. The present investigation was set up to examine the wear characteristics of M50 and T1 high-speed steels at both room and elevated temperatures to draw a thorough understanding of the wear behavior of this class of high-speed steels. This article focuses on the mechanical and microstructural characterization of wear for T1 and M50 high-speed steels using a pin-on-disk wear machine.

Jan 1, 2005