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By X. Wu, W. R. Chen, J-G. Legoux, B. R. Marple, E. Irissou

Cold gas dynamic spray (CGDS) has been considered a potential technique to produce the metallic bond coat for TBC applications, because of its fast deposition rate and low deposition temperature. This paper presents the influence of spray processes for bond coat, including air plasma spray, high velocity oxy-fuel, and in particular CGDS, on the oxidation performance of TBCs with a Co-32Ni-21Cr- 8Al-0.5Y (wt.%) bond coat. Oxidation behaviour of the TBCs was evaluated by examining the coating microstructural evolution, TGO growth behaviour, and crack propagation during thermal exposure at 1050°C. The relationship between the TGO growth and crack propagation will be discussed.

Jan 1, 2010

By M. Cimenti

Fuel cells have tremendous potential as power sources but much fundamental research is still required. One key component of the research is the experimental set-up used. In particular, the placement of the reference electrode is extremely significant in measuring the half-cell overpotential of solid oxide fuel cells, since differences in area, misalignments, and also differences in the kinetics of the working and counter electrodes can cause both scaling errors and frequency distortions of the measured impedance. The impedance of thin solid electrolyte cells of different electrode geometries has been calculated using the finite element method and the results compared to experimental values obtained for the oxygen reduction reaction on platinum.

Jan 1, 2005

By S. Brophy

Controlled Short Circuit ? Metal Inert Gas (CSC-MIG) welding is a process that can be referred as a "Cold Welding" technology. The CSC process is based on accurate control of the welding wire position, thus the mandatory requirement for the automation of the process. One of the main advantages of the CSC-MIG process is the rapid solidification of the deposited material, resulting in weldments displaying low porosity contents, and enabling the joining of thin sheet materials. These characteristics render this process an ideal one for freeforming of components, where rapid solidification would be efficacious. This presentation will focus on the progress made towards the freeforming of Al-based components in the NAIN laboratory at McGill University. The relationship between the filler metal used, freeforming (deposition) parameters, resulting microstructure and mechanical properties will be presented.

Jan 1, 2011

By K. Soldenhoff

Mantra Resources Ltd is developing the Mkuju River project is southern Tanzania. The uranium deposit, hosted in ?Karoo? sandstone, is surface outcropping with the majority of uranium mineralisation occurring in the finer clay component of the ore. A flowsheet, consisting of ore beneficiation, acid leaching, RIP uranium recovery and direct precipitation of the uranium product, was developed and successfully demonstrated in continuous mini-plant operations at ANSTO. The selected flowsheet overcomes the difficult slurry rheology, arising from the clay component of the ore, by eliminating the need for a CCD plant. The RIP process was found to contribute to a high uranium extraction, by eliminating ?preg-robbing?, at a relatively low acid addition in leach, with the potential to eliminate ferric ion and oxidant additions.

Aug 1, 2010

By Steven Dempsey

Overview What is Tubbing? A look at Cigar Lake Tubbing Design The Tubbing Installation Backwall Grouting

May 1, 2013

By Richard W. Hutchinson, Christopher Osterman

The Selebi-Phikwe deposits are hosted by amphibolite to granulite facies gneisses of the Limpopo belt. The sulfide orebodies are generally stratiform and conformable to the foliation of the wallrock gneiss. Sulfide remobilization has occurred during metamorphism and has produced discordant sulfide veins, called piercement structures, which project into the hanging wall and footwall gneisses. These piercement structures are compositionally similar to the stratiform sulfides, consisting mainly of pyrrhotite, pentlandite and chalcopyrite. However, texturally the piercement sulfides are coarse grained and inclusion-free, whereas the stratiform sulfides are fIne grained and packed with tectonically produced wallrock inclusions. The piercement structure sulfides and adjacent stratabound sulfides were sampled and analyzed for major base metals and PGE's for comparative purposes. Most of the piercement structures were enriched in Cu, Ag and Au, whereas they were generally depleted in Ni, Co, Fe and PGE's. Changing elemental associations were observed from the stratabound sulfides and along the length of the piercement structures. This and the degree of depletion or enrichment of various major and minor elements in the sulfide piercement structures may reflect the relative mobilities of metals under metamorphic conditions. The similarities between sulfIde piercement structures and the footwall Cu-PGE veins in some Sudbury deposits are reviewed.

Jan 1, 1994

By Erol Yilmaz

This poster presents results obtained from an experimental test set-up called CUAPS (curing under applied pressure system) allowing to assess the performance and quality of cemented paste backfill (CPB) materials. CUAPS can be used for carrying out a series of tests: one-dimensional consolidation, saturated hydraulic conductivity, pore-water pressure dissipation, and curing under uniaxial stress. The poster presents CUAPS testing preliminary results including uniaxial compression tests (UCS) and mercury intrusion porosimetry (MIP). It was demonstrated that CUAPS-consolidated CPB materials cured under time-dependent stresses provide higher UCS values than standard mould (undrained and unconsolidated) CPB samples. This may be explained by the release of excess pore water within backfill that gives rise to a significant reduction in the total porosity of fresh CPB materials prior to hardening and thus, to higher mechanical strength (UCS) gain. The results obtained from MIP highlighted a good correlation between CUAPSconsolidated and mould-unconsolidated CPB samples. MIP results were also related to UCS values in order to predict the final CPB mechanical strength.

Nov 1, 2008

By S. Knapp

Inconel 600 pipes welded to Carbon-Steel are used in CANDU nuclear reactors. Fracture of these welded tubes would have important consequences in term of safety, and therefore their mechanical properties need to be better understood. In this study, the weld region was analyzed at various length-scales using optical microscopy, micro hardness testing, small and large scale tensile testing and digital image correlation (DIC). Large grains were observed in the weld region and smaller grains in the Inconel and carbon steel base metals. Micro-hardness profiles showed variations across the weld and through thickness and were justified in terms of residual stresses in the sample. Large tensile samples were extracted from the welded pipe and were used to identify the material in which fracture initiates. In addition, the local strains in each material were obtained using digital image correlation. Local stress-strain curves were built from the DIC data and compared to stress-strain curves obtained from miniature tensile samples extracted from the carbon steel, Inconel and weld regions. The results demonstrate the advantage of using DIC for extracting local material properties in dissimilar weld systems. Variations in the materials stress-strain curves thought thickness are also presented and emphasize the need for obtaining a complete map of the mechanical properties in the weld region for predictive models to be accurate. Preliminary fracture studies will also be presented.

Jan 1, 2011

By Michel Aubertin

Using mine wastes as backfilling material for underground stopes has been a common practice for more than 60 years. Waste rock and tailings are used as filling materials because they are available at a reasonable cost to support the rock walls. Backfilling is also very advantageous because it reduces the amount of mine waste disposal on the surface. In underground mines, the backfill must first ensure stability of the opening, while increasing recovery of ore and minimising dilution. It is thus critical to accurately evaluate the pressures exerted on the walls and on the barricades placed near the base of the stope. In this presentation, existing solutions for evaluating the stresses on stope walls and barricades are briefly reviewed. The authors then present recently developed analytical solutions that take into account the stress transfer from the backfill to the walls in the stope and access drift. The stress state solution, which is based on arching theory, considers the influence of the stope geometry and barricade position within the drift. The method gives the pressure generated by partly or fully submerged backfill. The solutions apply shortly after backfill deposition, when the effect of pore water pressure cannot be neglected, and also for long term conditions under a fully drained state. Experimental testing and numerical modelling results are used to validate the proposed equations. Both numerical and analytical results show that the total pressure on barricades can be significantly increased by water pressure, while the effective stress is decreased (compared to dry or drained conditions). A discussion follows on the implications of the results for backfill applications.

Nov 1, 2008

By K. Karan

Oxygen reduction reaction in PEM fuel cell cathodes involves participation of three reactants - oxygen, hydrogen ions, and electrons. Electrochemical reaction in the catalyst layer is, therefore, influenced by how these species are transported to the reaction site. The two-phase boundary locations at which percolating networks of ionically conducting electrolyte and electronically conducting Pt/C meet are feasible reaction sites. The electrolyte phase also provides pathway for the transport of dissolved oxygen. Most of the 3-D models describe the catalyst layer as an ultra-thin layer, thereby, losing useful information on the distribution of electrochemical reaction rate. In this paper, we extend our previous work on 2-D cross-the-channel modeling of PEMFC cathode based on agglomerate catalyst layer. In particular, we take a closer look at the influence of proton conductivity on the reaction rate distribution in the catalyst layer. As well, we re-examine the role of anisotropic transport coefficient of the porous transport layer (PTL), commonly known as the gas diffusion layer, on the current density distribution under the channel and the rib of the flow-field plates. Results from both a 2¬D and a 3-D models will be presented.

Jan 1, 2005

By Damian Connelly

The option to leach iron from low grade copper concentrates could reduce transport costs and significantly improve the saleability of the concentrate. In addition, it reduces smelting costs and can remove undesirable impurities. The trend to produce cleaner and higher grade copper concentrates is very appealing to the smelters. A recent copper project came on line and there were three serious deficiencies which were not identified in the feasibility study. This came as a surprise and resulted in a number of projects to investigate ways of rectifying the problems in the shortest timeframe possible and using minimal new capital. The first serious issued not identified when commissioning was the lower than expected copper recovery, which was 70% compared to a predicted recovery of 80% to 87% in the feasibility study. This required investigating new flotation reagents and incorporating controlled potential sulphidisation. The second serious issue overlooked is the presence of significant amounts of talc minerals (insol) in the ore which are naturally floatable. This leads to lower concentrate grade and attempts to remove the talc resulted in lower copper recovery. Smelters have limits on the amount of talc in concentrate because it produces viscous slags and difficulties for the smelter. It also incurs higher transport costs. The third serious issue not identified in the feasibility study was the high arsenic reporting to the concentrate. Arsenic is a penalty element for smelters and at levels exceeding 0.3% the smelters may reject the concentrate. Arsenic is a problem environmentally for copper smelters and penalties apply when it is high. This paper describes the options for penalty element removal and suitability to incorporate into the modified flowsheet. It also highlights where the geometallurgy was not properly addressed and how these surprises could have been avoided. INTRODUCTION From 1970 to 1985, a copper company undertook metallurgical testwork on the Peruvian project copper ore. The ores were mined underground and treated over many years previously. Various other groups undertook studies and work until Aker Kvaerner undertook a feasibility study in 2006. Three ore composites were tested and grind-recovery relationships were developed. The feasibility study testwork identified that talc was a possible concern and will have an impact on copper concentrate grade. This was to be managed by blending. The current operating reality is that there is so much talc in the ore body it is not possible to blend it out. There was far more emphasis on molybdenum recovery. No mention was made of arsenic issues other than blending. There was a Concentrate Leach Study and a Molybdenum Hydrometallurgical Plant Study but these options did not proceed to a final flowsheet. A Scoping Study in 2006 looked at a Heap Leach project. The heap leaching gave very poor copper recovery on the sulphide ore. Heap Leaching was evaluated and tested for the high talc and high arsenic ore but recoveries were poor. The Aker Kvaerner feasibility study opted for a simple primary crush SAG/ball grind followed by flotation and sale of a concentrate. This is the current flowsheet utilised and the scale of the project is very large based on processing 117,200 tonnes of ore per day. A feasibility study does not guarantee success and the deviations from the feasibility study suggest there is a lot of technical work required to improve the current metallurgical performance.

Jan 1, 2019

By W. H. Mathews

"The Hardie group of cinnabar claims is in the interior of British Columbia; 25 miles northwest of the city of Kamloops. It is one of a number of mercury; properties scattered along a north trending belt 20 miles long and up to 5; miles wide. In all but one of these properties cinnabar is associated with; dolomite veinlets in zones of carbonate alteration in bedded rocks of Triassic; and Cretaceous (?) age; or in intrusives cutting these bedded rocks. No dolomite alteration or cinnabar mineralization is known in the undoubted Tertiary rocks adjacent to the mercury belt.The mercury showings of the Hardie group lie for the most part in a granitic stock cutting Cretaceous (?) volcanics. The rock in this intrusive shows marked variations in texture and has been described in earlier reports as granite and granodiorice, granite porphyry, and trachyte or dacite porphyry. At Hardie mountain the cinnabar mineralization, unlike that of the other properties, is associated with a fine-grained, almost chalcedoni c, quartz; carbonates, though present, are of minor importance. Some of the most interesting showings are found in an adit in the southeastern part of the property where cinnabar mineralization shows a very distinct structural but not a genetic relationship to a brown porphyry dyke 2 to 8 feet wide cutting a phase of the stock that may best be described as aplitic"

Jan 1, 1954

By W. B. Boggs

This is a rather comprehensive subject and cannot be thoroughly covered in the short rime allowed for its presentation. This article will touch only upon a few of the chief points of the difficulties encountered in recovering copper from brass shell cases in a primary smelter which was not designed to treat scrap metals. Owing to the fact that the plant is at present (Dec., 1946) closed, and our tests were not completed, full details of the results are not available. As is well known, most primary smelters are situated near the mines in the interior of various countries and are not close to seaports or large industrial and railway centres. Consequently, iris unusual for a primary smelter to be asked to treat scrap metal of any kind. When so required, iris obvious that the primary smelter is at a great disadvantage, for the simple reason that it probably has to pay the freight on the scrap from the seaport or industrial centre to the smelter and then also pay the freight on the recoverable metal from the smelter to the refinery, or seaport or industrial centre. Another disadvantage is that a primary smelter is not equipped to sample and unload the scrap nor bas it usually the equipment adaptable for treating the scrap efficiently, as the plant bas been designed to handle large tonnages of ores and concentrates. This short paper will describe some of our difficulties> and how they were corrected. However, it might be advisable to state briefly some of the methods used in treating brass shell cases in other plants. In the first place, a brass plant producing new brass- especially those producing brass billets for extrusion to make brass tubes or rods, or to be drawn into wire, or making brass cake to roll into brass sheets- generally insists upon using new electrolytic copper and zinc and is opposed to using any scrap or secondary brass . Consequently, such a plant usually will not treat brass shell cases. Therefore, the usual procedure is to ship brass shell cases to a secondary smelter, where it is generally sorted, melted, fire-refined, and returned to the market in the form of a high or low brass ingot which can be sold to brass foundries for making brass castings. This evidently is the cheapest and simplest method. Another method is to ship to a smelter which is a combination of a primary and secondary smelter attached to or near an electrolytic refinery. In plants of both these types, that is a primary smelter with Cottrell dust collectors or a combined primary and secondary smelter with Cottrells or a bag house, the zinc may be wasted. However, if a bag house is used, some of the zinc is recovered, but it is usually contaminated with other metals and further processing is required to recover it.

Jan 1, 1947

By E. Ettles

This paper features some of the spectacular new advances in the fields of fluorescent penetrant inspection and magnetic particle concentration. Casting fractures in the various stages -before the repair, during the repair and in the completed repair -using the cold process method will be discussed. This cold method of repair eliminates problems of pre-heating and cooling and the stress factors that are involved in any heat repair.

Jan 1, 1971

By W. L. Stuewe

For the purpose of this paper I shall, in order to limit myself, define the words 'Maintenance' and 'Equipment' as follows: Maintenance shall mean the 'care of or 'the sustaining of equipment in as nearly perfect condition as possible. Equipment shall mean any item of a mechanical nature entering into the production of coal; it will be seen that unless one limits the use of this word it could take in administration as well as operative equipment, and include metal mines, mills and smelters, and manufacturing plants. In any industry the first consideration is the proper operation of all units entering into the production of the article manufactured or produced. I wish to quote here what a man, well known internationally in financial circles, told his operators at the time a large expansion programme was under consideration. His exact words were: "I do not care how much it is going to cost. What I want to know is how much it is going to cost to operate and maintain. It is the continuous drain for repairs that costs us the most money." The truth of this statement has been proved time and again, and many companies have found the cost of maintenance to be the balance between profit and loss-so much so that, in two instances with which the writer is familiar, the mechanical equipment was practically replaced throughout. I bring this point out here to emphasize the value and necessity of keeping abreast of the times, and obtaining maximum efficiency with the minimum outlay. Time is indeed money where delays occur due to defective or poorly kept equipment, and it is absolutely necessary to prevent machinery from becoming defective or inefficient.

Jan 1, 1930

By A. L. Irwin

THE disposal of tailing or waste material, which is generally a very large proportion of the ore treated, is a major problem in the location and operation of any concentrating enterprise and especially so where the life of the operation is expected to continue for many years. Many factors need to be taken into consideration in the selection of a tailing site, chief among which are economical handling of the material, subsequent re-treatment of the tailing, and precaution against stream pollution by waste water. The final location of many mill sites bas been governed largely by the selection of a sui table area for tailing storage. The Sullivan concentrator of the Consolidated Mining and Smelting Company is situated about three miles from the Sullivan mine at Kimberley, B.C., and one of the deciding factors in its location at this distance from the mine was the availability of a suitable area in which tailing could be deposited. In view of the indicated long life of the property, a far-sighted policy bad to be adopted in the matter of tailing storage, for not only would it be necessary to accumulate a huge tonnage of finely ground material, but also reclamation for iron recovery at some future date bad to be considered. Some idea of the extent of the problem may be grasped when it is noted that, by the end of 1938, over 18,000,000 tons of tailing bad been impounded in an area of some 200 acres.

Jan 1, 1939

By Irvine J. Berscheid

This paper describes a rock drill bit which, although conventional in the processes of manufacture and use on the job, has incorporated into the outer wall or periphery of the insert, where wear is always the greatest, a variable amount of extra metal, distributed in units of height of insert to withstand this excessive wear. Explained are variations of construction, how the extra metal enables the bit to drill more footage, prevent antitaper and the need to gauge grind, increase penetration rate and the length of run per regrind, reduce shank breakage and ma-chine costs, and permit increased production per man-shift, without requiring any change in equipment already on the job. F OR purposes of clarity, reference to bits here means integral rods or multi-winged bits which have their inserts sharpened to a conventional shape. When dull, the insert has worn, on its face, a flat which increases in width as we progress from near the center of the bit toward the outer edge. Very

Jan 1, 1965

By J. A. H. Church

MR. J. A. H. CHURCH: The salient feature would seem to be that the thickness of the seam, in our coals at any rate, is the main factor in predisposition to spontaneous ignition. The evidence, incomplete it must be admitted, in the Saskatchewan and British Columbia fields, and complete in the Alberta field to my mind, shows this up very strongly. The German report on the upper Silesian coal fields definitely fixes the critical thickness at 13 feet, the British report goes far beyond this figure by stating that liability to ignition increases with the thickness of the seam over four feet. Before discussing the Alberta fires it would be well to note an error on page 12 -the probable cause of the fire in the Frank Mine should read "Spontaneous near fault. Heating first discovered 1909". Of the six fires attributed to spontaneous ignition all the seams were identical or in excess of the critical thickness mentioned in the German report. If there be any reason in the foregoing it is high time some forethought were taken to adopt some definite system of laying out the workings of such seams not so much on the outcrop districts as with a view to the future operation to the dip. Seams approaching 13 feet in thickness which to date have shown no disposition towards heating during the extraction of the outcrop areas may well cause infinite trouble or indeed total loss when the ventilating pressures increase as increase they must to the dip. This state of affairs can be combatted only by the adoption of a correct system of working and the provision of numerous airways of as large an area as may be compatible with the physical characteristics of the particular seam.

Jan 1, 1923

By K. Iturralde

The topic of this article is the automation and robotization in refurbishment processes of industrial buildings. The need to mold these production spaces is quite universal. Particularly in the regions with a high industrial development and with a lack of buildable land, there is a need to convert this kind of spaces into an improved production system. The latest developments can be a useful tool for achieving a more efficient way of reforming this type of construction. On the one hand we have the digital or computerized 3D Laser Scanning (Computer Aided Measurement) that allows an accurate 3D modeling of the entire building. On the other hand, the project management using BIM (Building Information Modeling) could provide an easy design of each of the elements of the refurbishment. Finally, through the production of construction elements using robotics as jig or for CNC (Computer Numerical Control) we achieve a neat production of each element. How can be all those technologies applied in the refurbishment or expansion of industrial buildings? The research takes a first approach and analyzes industrial buildings that can be called generic or not specialized. To narrow the field of refurbishment, three major factors are defined. The first is to minimize the bill of the energy consumption of the buildings. This could be done either insulating the envelope, reducing the waste-volume to be conditioned climatically or creating facilities for energy production. The second is that the refurbishment or expansion of industrial buildings should try not to interfere on the production process that takes place in the building. In other words, the assembly of the elements in the construction site should be quick and easy, causing the least of disturbance at the workplace. Finally, the research makes an approach towards a robot integrated industrial or productive building .

Aug 1, 2013

By Richard Wells

Peabody Energy is the largest pure-play publicly traded coal company in the world. We have been in business 129 years and like most of the coal mining companies in the United States, since 1969 the majority of our safety improvement efforts had been driven by compliance with the various versions of the Federal Mine Safety and Health Act and the supporting federal regulations. In 2004 Peabody Energy management came to the understanding that in order to achieve our goal of zero incidents, that focus must change. This paper will describe the elements of the journey we began at that point to make the transition to a behavior and systems-based approach to safety management and our efforts to win the minds and hearts of our employees. This journey is undertaken with the goal of making safety truly a way of life for all Peabody Energy employees.

Aug 1, 2013