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By John Knox

The object of this paper is to present an analysis of the major problems encountered both in the design and application of downhole drills. Particular reference is made to design features governed by: physical size limitations; metallurgical material standards; physical operating environment; range of commercial materials to be drilled; high power output required, coupled with simplicity from the operating and maintenance viewpoint; and bit design. The history of attempts to develop downhole drills is discussed, and representative mechanical configurations are illustrated. The general design and application aspects of the different types are commented on. The application of this drill type in various commercial fields, such as (a) oil-well drilling, (b) open-pit mining and (c) underground mining, is discussed, along with the limitations presently imposed by the commercial state of the art in the manufacture of accessory equipment; e.g., drill rods, air compressors, mountings, etc. Suggestions on the possible future direction of the development and application of this tool are put forth.

Jan 1, 1965

By G. Danko, C. Lu

"High temperature and humidity at the working negatively affect safety and health in deep and hot underground mines. It is necessary to predict during design the dynamic changes in temperature with heat and moisture emitted into the mine ventilation-thermal-humidity (VTH) system from various sources such as auto-compression, wall of strata, mining equipment and workers. Currently available mine ventilation and climate models are either furnished with a simplified, step-change-type (SCT) model for thermal solver (such as in Climsim, VnetPC, Minevent, MFire, etc), or with more advanced models to account for the “thermal history effect” (also known as thermal flywheel effect), such as in Ventsim and MULTIFLUX. The goal is to quantify the modelling error caused by the lack of variable thermal history component in the SCT model. Two models are compared: one with and one without the thermal history component in long, single airway examples with long-term climate simulations for 20 years assuming an input air temperature with daily variation. The examples illustrate the magnitude and the time-lag phase of the variation of the modelling errors with space, time and model conditions. Large errors are shown in the order of +14°C and –7°C errors, persistent for long time periods, up to 20 days in one example.INTRODUCTIONIt is important to predict the heat and humidity distributions during the design of hot and humid underground mines for the safety and health of the workers. The feasibility of extracting a rich deposit in great depth may depend on the extent of ventilation and mine climatization for maintaining an acceptable working environment. The cost of ventilation and cooling may be substantial, up to 40–50% of the total energy cost of mining (Clausen, 2017). The accuracy of model solution is important in view of the low profit margin in mine feasibility for deep and hot mines. Safety and health of the miners, the primary concerns, are therefore inherently connected to finding ever better solutions in simulation methods and ventilation control techniques."

Jan 1, 2019

By David Thomas, Charles Harper, Brian Watters

The Star-Waddy Lakes area lies withjn the northeasterly-trending early- to mjd-Proterozoic volcanoseilimentary-pl utoruc belt referred to as the La Range Domllin. In the area investigated the domajn is composed of the Central Metavolcaruc Belt which is bordered by metasedimentary belts of the Crew Lake and MacLean Lake Belts to the northwest and southeast respectively. The boundaries between the Central Metavolcanic Belt and the flanking belts are generally marked by prominent zones of shearing. The volcanosed imentary succession is intruded by a variety of ultramafic to felsic plutons which, on the basis of lithology, field relations and geochronology, can be broadly subdivided into three groups or episodes. These are: a) an 'early' (ea. 1866 Ma), possibly subvolcanic, episode marked by composite intrusions ranging from gabbro-diorite to granite, b) an 'intermediate' (ea. 1854 Ma) plutonic event distinguished by more homogeneous felsic intru ions ; and c) a 'later' (ea. 1835 Ma) event characterized by leucocratic quartz-rich grani te intrusions. The La Range Domain has undergone polyphase deformation with a strongly developed northeast-trending structural grain. Large scale folding is manjfested by large regional sy nforms, arcuate and triangular patterns associated with many of the plutons and by tight to isoclinal folds within the adjacent metasedimentary belts. Inhomogeneous strain characterizes much of the Star-Waddy Lakes area. With strain gradients being typically very steep, zones of high strain consisting of zones of extreme extensional fabrics, discrete shearing, as well as broader zones of cataclasis and structural slicing, are often juxtaposed with areas of relatively minimal deformation . Dilation structures tend to favour these zones of highly contrasting strain. Late, brittle fractures, faults and shear zones are widespread and appear to be particularly important as loci for gold mineralization. Metan1orphic mineral assemblages indicate that upper greenschist to middle amphibolite facies conditions were attained. Geological and geochenucal evidence indicates that the Central Metavolcanic Belt evolved in an island arc environment. Metavolcanic rocks from both the Waddy and Star Lakes areas display similar characteristics on variation diagrams (e.g. AFM and the Jensen cation plot) in that the dominant trend is calc-alkaline with some basic to intermediate types having a mildly tholeiitic character. A few samples from the southern end of Lower Waddy lake display komatiitic to basaltic-komatiitic afl'injties. The relatively immobile minor and trace elements (e.g. Ti , Zr, Nb, Y, Cr) provide reliable characterization of the metavolcanics, particularly of the basalts, which have highly distinctive trace element properties. Geochemical patterns for the basalts are similar to those for modem volcanic arc basalts. Low initial 87Sr/86Sr ratios (0.7017 - 0.7019) are consistent with a subduction-related origin for the volcanics. The major plutons have chemical properties typical of volcanic arc granites and are largely calc-alkaline in character, showing little chemical variation from the volcanics.

Jan 1, 1986

By Yves Gagnon, Nicole Gauthier, Daniel Kelly, Michel Rocheleau

"The Larder Lake-Cadillac Tectonic Zone in Rouyn-Beauchastel area (a 20 km long segment) contains distinct lithotectonic units bounded by artastomosing or sub-parallel shear zones. The gold deposits in the area are located within highly strained portions of E-W striking shear zones. The ore-zones are structurally controlled disseminated and vein-type lodes. They are spatially related either to megascopic z-shaped folds which refold E-W shears, or to areas of intersection between E-W shear zones and late NE-striking faults. Several ore bodies are enclosed within ultramafic rock units or at their contacts with adjacent units. All the lenses are elongated down dip and distributed, both loterally and vertically, ""en echelon"" . The ore zones tend to decrease in size and number away from the hinge zone of the megascopic z-shaped folds.Two main styles of mineralization are recognized at the Astoria deposit and at for most of the deposits in the Rouyn-Beauchastel segments a discontinuous ""Carbonate Ore"" and a more continuous, albitic sulphide-bearing ""Flow Ore"" (terminology used at the Kerr Addison mine).The typical ""Carbonate Ore"" zones are found within strongly arbonatized blocks bounded by conjugate late NE or NNW-striking fralls. The carbonatized blocks display features characteristic of llrittle to brittle-ductile deformation developed in shear zone system. Vein systems in the ""Carbonate Ore"" occur within shear fractures(D R)tension fractures (T), or within brecciated rocks adjacent to NS llrilcing faults. The ""Carbonate Ore"" zones are displaced by numer IU lole E-W, NNE, NW and N-S faults.The ""Flow Ore"" zones are found within predominantly ductile portions of E-W shear zones. The sulphide mineralization is finely disseminated and regularly distributed within mylonitic foliation or associated with veins and veinlets sub-parallel or oblique to the mylonitic foliation, in which case the mineralization is coarser grained. The gold mineralization is a late Archean event postdating the formation of the penetrative fabric, and synchronous with the end of the dextral oblique-slip motion."

Jan 1, 1990

By X. -G. Chen, A. M. Nabawy

A novel manufacturing technique for Al-TiB2 nanocomposites has been developed, in which TiB2 nanoparticles were incorporated into liquid aluminum under mechanical stirring and in the presence of a K2ZrF6 flux-wetting agent. The microstructure of the Al-TiB2 nanocomposites was studied using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The microhardness test was conducted to investigate the strengthening effect of TiB2 on the aluminum matrix. The TiB2 nanoparticles were successfully incorporated and dispersed into the aluminum melt in the presence of the K2ZrF6 flux during mechanical stirring. In the as-cast microstructure, most nanoparticles segregated in the interdendritic regions as a result of particle redistribution during solidification. The addition of 2, 5 and 10 wt% TiB2 nanoparticles increased the composite hardness by 60, 90 and 150% respectively when compared to commercial purity aluminum, indicating that the TiB2 nanoparticles imposed a significant strengthening effect on the aluminum matrix. The role of K2ZrF6 flux agent on the incorporation of nanoparticles into aluminum melt was discussed.

Jan 1, 2014

By C. E. White

The depletion of higher grade mineral reserves will accelerate the trend toward production from progressively larger and lower grade deposits. The discovery of adequate reserves of leaner ores will require the development of improved exploration techniques with a greater depth range. The principal challenges to the Canadian mining industry are to find the mineral resources required to meet fast growing world demand and to develop mining methods and equipment to ensure production costs which will strengthen our position in export markets in the face of in-creasing world competition. The challenges cannot be met without intensive efforts to attract more technical men to the industry and to improve their training.

Jan 1, 1967

By J. P. Morgan, D. B. Stewart

"AbstractLoad-haul-dump machines equipped with. a torque converter and hydraulic pumps have been field tested by means of an engine monitoring instrumentation package. It was found that owing to parasitic losses in the ancillaries and drivetrain, maximum available useable pourer may peak at less than full engine speed. Simple reduction of engine speed may save 15 to 25 percent on fuel consumption, with no significant loss of available power. On some machines, speed reduction will require modification of the torque converter . The cost of this modification, when necessary , would be offset by reductions in exhaust emissions, ventilation requirements, fuel consumption , heat, noise and hydraulic system maintenance, and by increased life of rotating components and filters and machine availability.IntroductionTHE CANADIAN EXPLOSIVES ATMOSPHERES LABORATORY, in conjunction with Deutz Canada Limited, has designed, constructed and field tested a portable instrumentation package. This package monitors diesel engine performance in underground mining machinery by continuously recording engine speed and volumetric fuel delivery. During tests designed to determine the engine load and speed conditions for the various segments which constitute actual underground operation of a Deutz F6L 714-powered 4-yard load-haul-dump machine, it was discovered that an unexpectedly large percentage of the engine power was required to overcome the ancillaries and drivetrain drag (1). That this large component of engine power is functionally related to engine speed rather than the operator's needs was verified by repeat tests of the used 4-yard machine and by testing of a new 5-yard machine powered by a Deutz F 8L 714."

Jan 1, 1977

By J. A. Muñoz

In this work, short and long-term tests were performed using different massive mineral sulfide specimens (chalcopyrite, pyrite, sphalerite, galena, covellite and chalcocite) of museum grade and quartz of analytical grade in an acid medium containing silver ions. After attack, the samples were observed by SEM and products characterized by EDS. Parallel, massive specimens of pyrite (FeS2) and chalcopyrite (CuFeS2) were embedded in an epoxy resin, either electrically isolated or in electrical contact, and treated with silver ions in the presence of bacteria. Finally, massive chalcopyrite and pyrite electrodes were subjected to electrochemical measurements in an acid medium under different experimental conditions (addition of silver ions and inoculation). The results showed that silver deposition takes place preferentially on specific mineral surfaces: chalcopyrite, galena, covellite and chalcocite. The chemical reaction of silver ions with pyrite and sphalerite was negligible at low silver concentration (8 ppm). But sphalerite reacted with silver ions at higher silver concentration (100 ppm). In a mixture of chalcopyrite and pyrite, silver was deposited on the former surface creating new cathodic sites which sped up the electrochemical reactions of chalcopyrite dissolution.

Jan 1, 2007

By Jehan Rondot

Les bancs de quartzite inhabituellement purs et epais decouverts lors de la cartographie geologique de la region de Charlevoix sont maintenant entres au stade de !'exploitation et se revelent etre une richesse naturelle durable pour cette region. Les etudes stratigraphiques effectuees dans cette partie (Quebecia) du bouclier canadien indiquent que la succession: lo. complexe a amphibolite et leptynite a la base, 2o. quartzite et gneiss a sillimanite, muscovite et gneiss calcosilicate et conglomeratique au sommet est constante sur de grandes distances (de Charlevoix a la Basse Cote Nord) et represente une sedimentation continentale et de plateforme, peu epaisse, du proterozotque inferieur. La purete et la grande epaisseur du quartzite s'expliqueraient par un processus de sedimentation continentale complexe ou se succedent climat tropical-humide et glaciaire-aride et transport fluviatile et eolien. Parmi la multitude de depots de quartzite qui existent dans le monde, peu sont de qualite superieure. Or, de par sa composition chimique, le quartzite de La Galette se compare avantageusement a ceux des meilleurs gisements des Etats-U ni s, de l'Europe de l'Ouest et de I' Afrique du Sud. D'acces facile pour l'exploitation, les gisements ne sont qu'a une quarantaine de kilometres de Baie Saint-Paul ou de La Malbaie, sur le SaintLaurent. L'utilisation en metallurgie du quartzite de La Galette comprend la production de silicium, de ferro-silicium et d'autres alliages de silicium . La composition du quartzite est en outre appropriee pour la production de carbure de silicium et de silicate de sodium. Les fines peuvent etre utilisees pour la fabrication du verre et comme matiere de charge.

Jan 1, 1984

By K. A. Hildebrant, J. R. Norgate

"Synthetic lubricants have for many years documented extended service life and provided superior performance in temperature extremes. Increasing interest in synthetics' ability to reduce energy costs has resulted in laboratory and industry application evaluations. These tests have documented savings in functions such as worm gear drives, spur gears and in compressors. Energy savings data are presented as well as payback calculations as low as thirty days.The National Research Council of Canada has estimated that the Canadian economy loses over five billion dollars per year in friction and wear. Figures quoted were for 1986 during which it was estimated that nine hundred and forty million dollars were lost in the mining industry alone"" It has been further estimated that about 115 million dollars can be immediately recovered through improved tribology practices (Table I).The purpose of this paper is to present results and savings opportunities through the use of synthetic lubricants in various but common applications. Many other areas exist with the opportunity for energy savings such as in the use of more efficient drive equipment, reduced contact seals, spray mist lubrication systems and reduced friction coatings on rotating equipment such as pump impellers"

Jan 1, 1994

By Pierre St-Julien, Réjean Hebert, M. Racine, Roch Gaudreau, Pierre Lacoste, Michel Rocheleau

"Les unités volcano-sédimentaires de la ceinture de l'Abitibi à l’est de Val-d' Or ont été regroupées en quatre domaines litho tectoniques. Du nord vers le sud, nous reconnaissons les domaines d'Assup, de Garden lsland de Val-d' Or, de Trivio et de Villebon. Deux de ces domaines (Garden Island et Trivio) correspondent à des couloirs de déformation, d’envergure régionale et d’orientation approximative E-W. Les trois autres domaines sont caractérises par des volcanites defond océanique de type MORB (tholéiites et komatiites) qui sont en position inferieure; ces volcanites sont surmontées par des sédiments marins de type turbidite (domaine de Ville bon) ou évoluent dans le temps, soit vers un volcanisme bimodal d'affinités tholéiitique et calco-alcaline ( domaine d'Assup), soit vers un volcanisme d'arc insulaire (domaine de Val-d'Or). Il n'existe aucune certitude de corrélation litho stratigraphique entre les différents domaines et l'on doit considérer la possibilité que ceux-ci représentent l'accolage tectonique de terranes de nature et d'origine différente.Les principales caractéristiques structurales de la région sont regroupées en quatre étapes de déformation dont trois sont archéennes et la quatrième attribuée à l'orogenèse grenvillienne. Au moins cinq facies métamorphiques ont été reconnus: I) un facies régional faible propre à la province du Supérieur, 2) un facies de cornéennes a amphibole en périphérie du pluton de Pershing, 3) un facies hydrothermal dans la zone tectonique de Cadillac, 4) un facies régional moyen dans la zone de bordure de la province de Grenville, et 5) un facies régional élevé a l'intérieur de la zone structurale du front de Grenville.Le front de Grenville est défini dans la région par l’apparition subite des ortho gneiss au faciès métamorphique élevé et par la disparition du grain tectonique E-W. Le contact brusque entre les deux provinces pourrait correspondre à une zone de chevauchement de la province de Grenville sur la province du Supérieur. La région étudiée est l’hôte d’un gite majeur de sulfures massifs et de plusieurs gites et indices aurifères; elle présente des cibles favorables pour l’exploration minière dans le contexte tectonométa-morphique de l'influence grenvillienne. L'intérêt de la Formation de Val-d' Or pour les métaux de base et le potentiel aurifère des couloirs de déformation d'orientation approximative E-W, sont bien connus. Les structures grenvilliennes NE-SW, qui se développent vers l'est, représentent aussi des cibles intéressantes, en particulier dans les secteurs ou elles intersectent des cisaillements E-W kénoriens."

Jan 1, 1990

By T. T. Wang, T. H. Huang, S. S. Zhan

"Fractures with diverse features dominate the hydraulic behavior of fractured rocks and are one of the major subjects for hydrogeological characterization of a site. This study investigates curve patterns obtained by packed tests, and as well the influence of fracture features based on 59 sets of in situ packer tests with different fracture combinations and fracture features. The result shows that, in the example of Heshe site, neat and tidy fractures usually provide stable channel for water flow during testing, and the hydraulic properties of fractures infilled with breccia and mud may change during testing because of leaching and/or washed out of infilling breccia and mud. Different combinations of fractures with diverse features in packed test sections lead to different curve patterns for in situ hydrogeological tests. For groundwater flowing predominately through neat and tidy fractures, the pressure-discharge curve of modified Lugeon tests are usually linear curve pattern, and the pressure decrease while the discharge increase in pressure-discharge-time curves of single-hole double packer tests, which benefit statistically determining the transmissivity of dominant fracture sets. INTRODUCTIONFractures interlaced in rock masses are major channels for groundwater flow and generally account for the anisotropic and heterogeneous characteristics of permeability for fracture rocks. To describe reasonably the permeability of a fracture rock, the Discrete Fracture Network (DFN) approach and others with similar ideals have been developed. Many methodologies and associate equipment, for instance, the televiewer and the in situ hydrogeological test, have been proposed to investigate the spatial distribution and the transmissivity for different fracture sets, which are two main parameters necessary for the DFN or similar model simulation (Pearson & Money, 1977; Barker & Black, 1983; Hsieh et al., 1985; Bernard et al., 2006; Quinn et al., 2012). However, diverse outlooks for the pressure-discharge curves and the temporal pressure and associate temporal discharge curves often confuse the investigation results by significant deviations on derived permeability (Houlsby, 1976; Zlotnik, 1994; Royle, 2009; Camilo, 2010).Aiming on technical development for in situ hydrogeological tests and fracture investigation, an experimental well site with 10 wells has been established in Heshe in central Taiwan since 2011 (Wang et al., 2011; Song, 2012; Zhan et al., 2013). Extensive geological survey and well-hole scanning by a televiewer provide spatial distributions and outlooks of fractures in detail. Additionally, a series of Lugeon tests, double packer injection tests and pumping tests have been performed to investigate the permeability of fracture rocks, and dominate fracture sets as well. Based on the results obtained from the Heshe site, this study classifies the curve patterns of hydraulic packer tests. The features of fractures involved in packed sections for packer tests are then inspected in detail. Relationship between the curve patterns of hydraulic packer tests and associated features of corresponding fractures in rock are discussed and addressed accordingly."

Jan 1, 2015

By K. Svens, M. Lahtinen, L. Lehtinen

"Outotec's direct leaching process is an atmospheric leaching process for sulphidiczinc concentrates. The direct leaching process, based on special leaching reactors developed by Outokumpu and leaching know-how, is the most economical way to produce electrolytic zinc. The newest industrial-scale application of Outotec's direct leaching process will be started up in 2008 in China at Zhuzhou smelter. The process isintegrated to the existing production plant, replacing part of the old production facilities by modern technology and increasing the production capacity significantly. The process equipment supplied by Outotec includes also tailor-made reactors designed on the basisof the work and experience of Outotec Research Centre."

Jan 1, 2008

By Stephen C. Tadolini

"The use of a torque wrench to establish the amount of actual load developed on an expansion anchor bofting system dates back to work completed in the early 1950s. The advent of ultrasonic measurement systems and hydraulic torque wrenches has made it possible for the U.S. Bureau of Mines to perform torque-tension measurements in the laboratory and the field much more accurately. The results indicate that the amount of initial boft preload may be overestimated by amounts in excess of 45% of the expected load using torque wrenches. This inaccuracy is primarily due to the friction that occurs between the bearing plate and the head of the boft. These parameters become extremely important when the support system is being used to prevent joint members from slipping relative to each other or when the boft acts as a heavy spring to clamp two or more sections together. Methods to overcome the frictional losses are presented in conjunction with a laboratory method to determine the actual torque-tension ratios for expansion anchor and combination bolting systems.IntroductionMechanically anchored roof bolts have been widely used in the mining industry since their introduction in 1947. Estimates made in 1989 indicate that out of 85 million fixtures, approximately 49 million bolting fixtures still use applied tension to complete the reinforcement necessary to maintain stable openings. Nearly 85 million bolts are used yearly. The most widely used bolt is the resin-anchored headed rebar, followed by standard mechanical roof bolts, specialty bolts (mechanically anchored, resin enhanced fixtures) , and combination bolts . Po st-tensioned resin rebars, combination systems, and friction stabilizers make up the remaining 10% of the units used (Fig. I).For mechanical, combination, and tension rebar bolts, the bolt tension is the primary means of reinforcing the roof, but in many cases, because of poor installation procedures, the bolts are ineffective. Mine operators recognize the importance of proper installation procedures. Long-term bolt tension measurements are required in the Code of Federal Regulations (CFR)In each bolting cycle, the actual torque or tension of the first tensioned bolt installed with each drill head shall be measured immediately after it is installed. Thereafter, for each drill head used, at least one roof bolt out of every four installed shall be measured for actual torque or tension. If the actual torque or tension of any roof bolts measured is not within the range specified in the roof control plan, corrective action shall be taken."

Jan 1, 1991

By P. Mišcevic, B. Kavur, I. Vrkljan, N. Štambuk Cvitanovic

It is known from earlier and recent research that mechanical properties of intact rock like uniaxial compressive strength (UCS), Young's modulus (E) and Poisson's ratio (?) are influenced by shape deviations of test specimens as deviations from the ideal cylinder. That impact can be significant at certain level of inaccuracy of specimen preparing, and it should be objectively evaluated and controlled in testing. The effects of intact specimens side straightness, ends flatness, ends parallelism and perpendicularity to the specimen axis, on UCS, E, and ?, measured in several actual ways during laboratory compression tests, were determined by previous research on 90 homogeneous specimens of limestone. In this paper, we subject these new experimental results to Response Surface Methodology (RSM) to model the mentioned dependence, to identify significant connections of variables and to evaluate the conclusions obtained directly from experimental phase. This study indicates how the responses of the model (outputs) – parameters UCS/E/??of limestone rock depend on factors (inputs) – parameters of specimen shape deviations like flatness R, parallelism P and perpendicularity O, assuming modern test machines with spherically seated upper platen. Starting from general RSM model with three factors (R, P, and O), we investigated the multiple linear regression models of specific mechanical property (UCS, E, and ?). Using the NCSS program ("NCSS 2004 and PASS 2005") in several steps, final models with very high coefficients of determination were developed for properties with the most evident effects of specimen shape deviations: nine models for strength UCS and UCS50 (equivalent UCS for specimen with 50 mm diameter), and three models for ?L (Poisson's ratio calculated from axial deformations measured on the entire specimen length). These statistical models with their response surfaces further strengthen and confirm the results and conclusions from the experimental phase. The critical values of R, P, and O are established using an additional statistical analysis to determine the lower and upper engineering limits. These findings set the basis for the new eligibility criteria for specimens of limestone (and similar rock with UCS about 100-150 MPa) in further testing of strength and deformability.

Jan 1, 2015

By P. Simon, G. Falkinger, G. Angerer, B. Gerold

"This contribution presents an investigation of the evolution of shrinkage pores during hot rolling with a special focus on the microscopic mechanism. The reliable closure of pores, which inevitably occur during the casting process, is of crucial technological importance for high-quality hot rolled plate products. Therefore, lab-scale tests were carried out under different typical thermomechanical loadings. Extensive data from optical microscopy was collected before and after deformation. The analysis shows that the average volume of pores evolves similar to the volume of an idealized arrangement of voids in an ideally plastic matrix. The average shape of the shrinkage pores, however, was found to be almost constant during deformation. Even though individual pores exhibit complex morphologies far from any idealized geometries, the overall evolution of a large number of pores is well captured by simple assumptions. In addition to the quantitative analysis, a schematic representation of this counter-intuitive behavior is provided. A simple ‘Gurson’-type void evolution equation was implemented in a three-dimensional Finite-Element model of the industrial hot rolling process. With the help of this mechanism-based process simulation the thermomechanical closure of shrinkage pores during the rolling process has been optimized for a variety of plate products.INTRODUCTION Aluminum alloys of the 7xxx series are widely used in the aircraft industry. They have to meet high quality standards regarding microstructure as well as mechanical properties. For hot-rolled aircraft plates, one of the most important quality requirements is that they are free from pores. Pores, however, are inevitably created during the casting process either due to shrinkage or due to the dissolution of gas from the melt. The pores have to be closed mechanically during the hot-rolling process. Therefore, the mechanism of so-called pore closure or void closure has a high technological relevance for the production of aircraft plates. The behaviour of voids in a ductile matrix subjected to mechanical deformation has been extensively studied, especially in the context of damage mechanics. A recent review (Besson et al., 2010) on modeling methods for ductile damage gives a good impression on how much experimental as well as theoretical effort has been dedicated to the problem of void evolution under mechanical loadings. Although void closure has been studied to a far lesser degree, it obeys to the same general theoretical evolution laws as void growth. The most basic theoretical result is that hydrostatic pressure drives void closure, while hydrostatic tension leads to void growth. The mechanism of void closure depends on the void shape. This is illustrated by the example of a flat penny-shaped void, which under compression obviously closes much faster than a sphere with the same volume. Theoretical models have been developed for the evolution of simplified void geometries, such as spheres or cylinders (e.g. Gurson, 1977), spheroidal (Gologanu et al., 1997) and ellipsoidal voids (Ponte-Castaneda, 1994). In industrial cast ingots, however, the pores exhibit very complex morphologies, which are far from any idealized geometry. X-ray tomography revealed ‘tortuous’ voids in a 5xxx aluminium alloy (Chaijaruwanich et al., 2006)."

Jan 1, 2018

By T. Johnson, D. Kelley, J. Graham

"Hydrometallurgical processes can be exceptionally corrosive. Conditions associated with metal extraction and refining require materials of construction that can withstand process acids and acid chlorides at temperatures up to 90°C (194°F). Process vessels, piping, scrubbers and ducting can be rapidly compromised in these aggressive environments if not designed with care. Design engineers are challenged to find materials that can stand up to hydrometallurgical processes especially for copper, zinc, nickel, cobalt and uranium. This paper will evaluate material solutions to determine which provides attractive economics for initial procurement as well as high durability for reasonable life cycle costs.INTRODUCTIONMining activity in a number of metal ores has been running quite high over the last few years. In particular, those metals that employ acid functional extraction processes such as copper, nickel cobalt and uranium have been particularly active.The world’s largest nickel mine – the massive $4.76 billion Ambatovy nickel mine on the African island nation of Madagascar is nearing completion. When it reaches its full production capacity in 2013, the mine will produce 60,000 MT/yr of nickel and 5600 MT/yr of cobalt. Coming on the heels of the Ambatovy project is the Long Harbour Processing Plant in Newfoundland, Canada which will process the ore from Vale’s Voisey Bay mine in Labrador. Voisey’s Bay is expected to generate more than 50,000 MT/yr of nickel ore when it starts up in 2013. Next up will be the Boleo project in Mexico on the Baja peninsula. When commissioned in 2013, the $858 Million Boleo project is expected to produce 60,000 MT/yr copper, 3100 MT/yr cobalt, 36,000 MT/yr zinc and 100,000 – 250,000 MT/yr manganese carbonate.High nickel alloys and rubber lined steel have been used for decades to design corrosion resistant equipment for mineral processing environments. These materials demonstrate reasonable resistance to corrosion for most environments. Unfortunately, higher nickel alloys are quite expensive. Rubber lined steel is a bit more affordable but requires continuing service over time which ultimately drives up its cost as well. FRP (Fiberglass Reinforced Plastic) has also been used extensively in mineral processing for tanks, piping and ducting employed in aggressive environments. Today, more and more design engineers and material specifiers are calling for FRP composites for both new and replacement equipment used in the refining and processing of a variety of metal ores."

Jan 1, 2012

By Max W. Ball

YOU have been kind enough to ask me to speak to you on "The War and Anglo-American Relations." A speaker always takes the liberty of putting his own interpretation on the scope of his subject. I am going to exercise that privilege, and try to look back over a generation of Anglo-American relationships and forward beyond the present war. I should like particularly to consider responsibilities as well as relationships. A more accurate caption for what I am going to say would be "Anglo-American Responsibilities.?? THE WAR WILL BE WON I am assuming that sooner or later we shall win this war. History and economics point to the same conclusion, that Germany has attempted the impossible and that the seeds of defeat are already sown. As to one ecof1:omic factor, I am already on public record as believing that Germany's oil supply is inadequate for the war she has launched. That opinion is unchanged. Aside from such tangible factors, moreover, I am convinced that the spirit of freedom is unquenchable, and that no combination of powers will be able to rout it from the British Commonwealth of Nations and the United States. Stronger even than this conviction is my faith in a God who will not suffer the defeat of man's aspiration to be master of his own soul. I am sure that all of you share that faith, and that we need not argue it. We can start with the assumption that the war will end in victory. The subject we are to consider, then, is the relationship of the English-thinking peoples during the conflict, and their joint responsibilities in the difficult days that will follow it. A CANADIAN-AMERICAN No talk on such a subject is worth listening to unless the audience knows the background and fundamental beliefs of the speaker. No human statement stands alone; behind and beside and within it are the ideals and the bias of the man who makes it. Because I am a stranger to most of you, I am constrained to talk about myself before I talk about more important matters. The review may be profitable, not because of the subject, but because it may illustrate the evolution of an attitude toward England.

Jan 1, 1941

By T H. Clark, R P. Doig, V. A. Saull, R B. Butler

Terrestrial heat flow has been determined for four boreholes in the Montreal area. The mean value of the results (uncorrected for glacial effects) is 0.790 ± 0.053 x 10-6 cal/ cm2/sec (95 per cent confidence limits). Thermal gradients were determined using a thermistor probe and d-c bridge, and also by a new method using a probe-contained phase-shift oscillator, the output frequency of the oscillator being a function of probe temperature. Thermal conductivity determinations were made on core from the boreholes, using a divided bar apparatus. INTRODUCTION T HIS paper concerns the terrestrial heat flow in the St. Lawrence lowland of Quebec, as determined from measurements on four of the numerous boreholes drilled in this region for gas and oil. The work has been supported by Geological Survey of Canada Re-search Grant 3-58, awarded to T. H. Clark and V. A. Saull. This sup-port is hereby gratefully acknowledged.

Jan 1, 1962

By N. J. Bunce, B. Vollick, A. F. Souza, D. Bejan, P. Maharaj, C. Shamshoom

"Copper electrodeposition from synthetic and authentic acid mine drainage (AMD) is inhibited by ferric iron (Fe(III)), through re-oxidation of copper. Polarization to –2.5 V versus standard hydrogen electrode prevents the dissolution of predeposited copper from the cathode. Above pH 1, copper deposition is independent of Fe(III) concentration to approximately 25 g/L. Fe(III) is reduced to ferrous iron (Fe(II)), with a high combined current efficiency for iron and copper reduction. In a divided cell, the conversion of Fe(III) to Fe(II) is almost quantitative, with efficient transfer of acidity from catholyte to anolyte. Prospects for developing electrochemical technology for complete remediation of AMD are discussed.RÉSUMÉ En raison de la réoxydation du cuivre, le fer ferrique (Fe(III)) nuit à l’électrodéposition du cuivre à partir de drainage minier acide (DMA) véritable et synthétique. Une polarisation à -2,5 V par rapport à l’électrode standard d’hydrogène empêche la dissolution du cuivre déjà déposé de la cathode. À un pH supérieur à 1, la déposition du cuivre est indépendante de la concentration en Fe(III) jusqu’à environ 25 g/L. Le fer ferrique est réduit en fer ferreux (Fe(II)) avec une efficacité combinée élevée pour la réduction du fer et du cuivre. Dans une cellule divisée, la conversion de Fe(III) en Fe(II) est près de la quantité théorique, avec un transfert efficient de l’acidité de catholyte à anolyte. Les perspectives de développement d’une technologie électrochimique pour la remédiation complète du DMA sont discutées."

Jan 1, 2016