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By J. F. Dorion

This paper presents the results of on-going investigations on the performance of support systems in Québec underground mines. The focus of these investigations is on site observations complemented by laboratory investigations. Of particular interest is deducing the corrosion rate, at selected mine sites, as determined by the installation of monitoring coupons.

May 1, 2009

By Ming’an Wei, Qifu Duan, Chengtie Wang, Jianmin Wu, Erdenet Mining Corporation, Lusheng Zhou, Wenjian Wu

"The development and industrial applications of magnetic liners have been around for decades. A Swedish company SKEGA first introduced the rubber magnetic liner, and then followed by the Chinese metal magnetic liners. Traditionally, both liners were used in secondary and regrind ball mills, especially for ores containing magnetic materials. Mostly steel balls or equivalent forged balls, usually below 60 mm in diameter, were used as grinding media. With the development of mineral resources over the years, SAG mills and larger ball mills have become the dominating components for comminution circuit design globally. Due to the larger ball mills and thus larger grinding balls (up to 80 mm) especially in non-ferrous metal industry, the application of magnetic liners has been very limited. Based on the new development of materials, the HMR Group Limited has been exploring new designs of magnetic liners which led to the invention of the Nano Steel Magnetic Liner (NSML). Recently, NSML had a successful application in a 5.5m x 6.5m ball mill with 80 mm balls at the Erdenet Copper Mine in Mongolia. Although the first set of liner had a service life of 12 months, the design of the second set was modified and improved to accommodate the operating conditions, which is expected to reach least 24 months service life. The original manganese steel liner only had about 8 months liner life.1. IntroductionMineral processing is an essential operation for the development and utilization of mineral resources. The effective concentration of various useful minerals depends on sufficient liberation of the mineral particles in the ore. The crushing and grinding process such as ball milling are the most common way to achieve proper liberation size. Mill liner is an eternal topic for the operations, not only because it protects the equipment, but also affects the mill grinding efficiency and availability. In recent years, magnetic mill liners have been developed that can easily meet the production targets with numerous benefits, such as zero maintenance, reducing specific energy consumption and improving grinding efficiency."

Jan 1, 2016

By Mark Kennedy, Allan MacRae, Cameron Hams

New technology projects, particularly those involving first-of-a-kind metallurgical facilities, have a poor track record of achieving their overall financial targets, as they incorporate technological risks in addition to normal project risks. Traditional project management tools focus on risk from concept development through implementation, but typically fail to address the additional risks associated with a new technology project including slow start-up, slow ramp-up, and failure to achieve design performance (quality or throughput). These additional risks affect future cash flows produced by the project and hence its value, typically measured as net present value (NPV) or internal rate of return (IRR). Common accounting practice is to reduce the present value of future cash flows by applying a chosen discount rate, often reflecting the corporation's cost of capital. This discount rate does not contain an allowance for technological risk, which is often underestimated or misunderstood by both the financial and engineering project managers. This paper will focus on the topic of project risk and new technology, and how these play a role in the probability of achieving the predicted future cash flows. By properly addressing technological risk in the form of risk-weighted returns, marginal projects can be prevented from proceeding, while sound projects can be given the additional time and resources required to achieve the optimal level of front-end-loading (the level which returns the maximum risk-weighted net present value). A simple set of mathematical tools should enable engineers and financial professionals to establish a common level of understanding, thereby leading to a more accurate assessment whether a new technology project is ready to pass through its next level of approvals.

Jan 1, 2011

By W. G. McBride

THE present demand for men with engineering training exceeds anything in the history of the profession. Recent estimates indicate that mechanization of war has reached such a stage that at least twelve horsepower is required now for every one horsepower needed to run the machines of the first Great War. The scale of operations exceeds anything in the past, while more territory and people are involved than ever before. Many of our allies have inadequate or no facilities for producing the thousand and one articles absolutely necessary to the conduct of modern warfare. Lack of preparedness has made it necessary to produce at an unparalleled rate to gain parity with the enemy, while our losses have been so heavy that replacement, in itself, presents a task which might well stagger less courageous peoples. This means that not only is there an unprecedented demand for engineers to produce the machines, munitions, and supplies of war, but there is a correspondingly large need for men with engineering skill in the uniformed forces to operate and maintain the vast numbers of ships, 'planes, tanks, trucks, radios, and a myriad of other devices to carry on the varied activities of war. This abnormal demand came upon us after almost ten years of stagnation in the engineering industries. During this time many trained engineers drifted into other callings, while the lack of jobs for graduates caused a falling off in the number of men training for this profession. Consequently, the supply of well trained engineers was below normal when the madman of Germany precipitated us into the present turmoil. Added to all this, we in Canada are still suffering from governmental inefficiency in the utilization of the available supply of engineers. In the armed forces, engineers have been assigned to office and other work where their engineering training is not only wasted but for which men with more suitable training could be found. Mining engineers are debarred from service as aeronautical engineers, and students in mining engineering are denied the bursaries provided for aiding students in engineering. Mining and metallurgical engineers are both barred from the Ordnance department of the army. This arises from a misunderstanding in relation to engineering training. In Canadian engineering schools, all engineers are given a sound training in the branches of human knowledge which are fundamental to engineering: mathematics, physics, and chemistry. The basic difference between the several categories of engineers lies in the fact that training in the application of this fundamental knowledge to the solution of engineering problems is given in different subjects.

Jan 1, 1942

By Michel Noël

This paper presents a partial compilation of adopted measures of waste rock dump closures at mine sites located in Canada and Alaska, where the climate includes cold winters. The paper also presents the selection process that was followed for some of those mine sites. Mining operations usually generate waste rock that can sometimes result in very large quantities. Additionally, the nature of the ore body and the host rock will often introduce environmental impacts. These impacts need to be managed not only during the operations but also in the long term. Mine closure plans consequently have to address the long term issues that sometimes require perpetual treatment. Closure planning often involves the evaluation of risks associated with environmental and financial liabilities. It needs to consider the science, some common definition of objectives, and there will be a need to manage resources and schedules. Closure planning is essentially an exercise in constrained decision making. A performance and risk based ranking matrix is often developed during this selection process to identify the preferred option(s). The case studies presented in this paper provides a few examples. The level of knowledge on acid rock drainage from waste rock dumps has increased considerably over the past decades. It did not necessarily increase the level of complexity of the adopted closure methods, as the selected closure methods are often kept simple. A common approach consists of stabilising the slopes of the waste rock dumps material by resloping and then covering the waste rock with a growth media to support vegetation. Such covers prevent direct contact of animals with the waste rock material, minimise erosion and reduce infiltration to various degrees. The inclusion of water treatment is obviously dependent on the water quality being released.

Nov 1, 2008

By M. G. Lipsett

One challenge in applying information technologies in Mining is building a business case. In Mine Maintenance, there is a complex flow of information that contributes to making informed business decisions. By understanding those information relationships and the cost of wrong decisions, analysts can estimate the value of information flow. Developers can then ensure that systems deliver key information in an accurate and timely way. In this paper, general maintenance decision-making is discussed, with examples of how model-based analysis can improve the information delivered to decision makers.

May 1, 2001

By H. J. Chalmers

"Since the advent of large volume flotation machines, Cominco Ltd. has actively studied possible application of such machines to their various milling operations. A number of installations have been made and more are on the drawing board. This paper gives a description of these units, information as to choice of equipment, and information as to operating experience. Mechanical and operating details of six installations are summarized. Three different types of machines are discussed.Pine PointThe original Pine Point zinc flotation circuit comprised conventional roughing with two stages of cleaning. Over the years with increase in feed tonnage there have developed two adverse conditions; namely, a reduction in zinc concentrate grade coupled with an increase in MgO in the concentrate. This resulted in higher freight payments along with more severe smelter penalties. An intensive test program, in 1971, showed that the concentrate grade could be raised by 1.5 units of zinc along with a reduction in MgO from 0.8% to 0.47.. Subsequently this was done by adding two additional stages of cleaning using 16 cells of Denver 200-V's. The project was completed in January 1973 at a cost of $510,000 to give an estimated annual savings of about $390,000.Selection of the Denver Model 200-V was based on minimum floor space requirement, availability, and favourable operational and maintenance experience with Denver 100’s. As it happens it was possible to ""shoe-horn"" the 16 cells into place with a minimum of plant alteration. Some problems have been encountered with a tendency to ""sand up"" at high pH, particularly at the corners. Otherwise operational service has been very good."

Jan 1, 1974

By A. C. Gagnon, H. Saroglou

"The focus of this paper is on the analysis of geometrical discontinuity properties for the rock mass located within an open pit mine located in Western Africa. Discontinuity data were collected using various techniques including oriented core logging, borehole televiewer surveys, surface pit wall mapping and photogrammetry. The geological setting was initially studied prior to the data analysis to produce threedimensional ground models of the regional and mine site geology along with block diagrams illustrating predicted fracture patterns. Stereographic and statistical discontinuity data analysis of the geometrical properties of the rock mass was subsequently performed to identify unique structural domains throughout the open pit area. The discontinuity data collected throughout the studied open pit area were primarily discontinuity orientation, frequency and spacing and the investigation focused on the reasons for observed differences between the various data collection techniques. Stereographic analysis was used to assess the preferred geometry of discontinuities filtered by lithology, data collection technique, borehole, discontinuity type and pit wall (footwall or hanging wall). The observed fracture pattern is explained adequately by the geological setting. The need for accurate ground models for the design of open pit slopes is highlighted.INTRODUCTIONThe Tasiast Mine is an open pit operation located in north-western Mauritania, approximately 300 kilometres north of the capital Nouakchott. The Tasiast mine, which is owned and operated by Kinross Gold Corporation (Kinross), began commercial operations in 2008. The Tasiast mine is located in an area characterized by flat desert terrain within the western reaches of the Sahara Desert region. The current mine site includes mill buildings, shop facilities, waste dumps, tailings facilities and two main open pit operations (Piment and West Branch). The West Branch pit is the focus of this paper. The current open pit plan for West Branch indicates a final pit measuring approximately 2.5 km long by 1.4 km wide and 510 m deep."

Jan 1, 2015

By G. Goodlad

This paper describes some of the main aspects involved in implementing the European “Equipment and Protective Systems for Use in Potentially Explosive Atmospheres” (ATEX) Directive (No.94/9/EC) in the British mining industry by the year 2003. It provides a brief background to the Directive and considers its main objective of removing all barriers to trade in Europe. It outlines the need for the European Standards making bodies to write new editions of the ’explosion protection concept standards’ and for manufacturers to adopt new quality management procedures and develop new versions of equipment in conformity with the ATEX categories of “M1” or “M2.” Finally, it assesses the possible future relationship between the European enforcing authorities, manufacturers and users of explosion protected equipment.

Jan 1, 1999

By Michael Bauer

Increases in productivity and improvements in mining occupational safety and health are intrinsically linked. Over the past years, the German Hard Coal Mining Industry has been able to accomplish both: an increase in coal production and, at the same time, a significantly reduction of accidents. This success has been achieved by advances in technology, better organization and investment in people. Since 1990 productivity has more than doubled, while the total number of accidents has been reduced by more than 90%. Further development started initially with the mechanisation of the winning and drivage technology. Innovative technology and standardisation of the mining equipment were one reason for the increase in productivity and reduction of the accident rate. Therefore this technical development was not only one important pillar of the TOM model explicated later but also the requirement for the successful development of the other pillars. In addition to further developing this innovative technology it was possible to realise procedural and organisational improvements. As a result, the above achievement is based on implementing the three pillars of the so-called "TOM" model (technology, organization, ?Mensch? = human). To increase safety, improve performance, raise awareness and change of employees? attitude, the following technical and organizational requirements have been introduced: ??New innovative technology and procedures, standardized techniques and better equipment. ??Measures to revise or redefine the organizational structure, processes and systems of work, which were then integrated into the company policy and procedures as a company management tool. ??Personnel measures (investment in people). These include, improving motivation and behaviour, training, communication to raise and to change awareness of safety issues. Success in Occupational Health and Safety is not an automatic or self-regulating process. It needs hard work to make improvements and it must be treated as a recurring cyclic process. As a result of the above, occupational health and safety has become a natural part of daily work in the German Hard Coal Mining Industry. This could only be achieved by the unconditional "commitment" of all managers and employees to the issues, coupled with discipline and responsible action. Further improvements towards the ultimate aim of "zero" accidents are only possible by mutual involvement in implementing the ?TOM? (technology, organization and ?Mensch? human) model.

Aug 1, 2013

By Candido Bariáin

A new vapochromic material of formula [Au2Ag2(C6F5)4(bipy)2]n (bipy = 2,2´ bipyridine) has been developed and used for the detection of some volatile organic compounds as acetone either in vapour or in water solution. The material is presented in the form of powders which colour changes with acetone vapours turning from bright yellow in the absence of vapour to white in the presence of vapour. By using the sol-gel technique, the powder ? dispersed in tetraethyl orthosilicate- was easily deposited on optical fibres. In order to study experimentally the behaviour of this material for construction practical optical fibre sensors, a sol-gel material doped with the vapochromic material is deposited onto an extreme of a monomode fibre connected to a coupler. The behaviour of the material was studied for different wavelengths and concentrations of acetone vapours and acetone/water solutions. Changes up to 4dB in the reflected optical power were detected. Optical fibre sensors have many advantages over conventional ones, such as electromagnetic interference immunity, passivity behaviour, possibility of using multiplexation techniques, low weigh and little size, etc. Actually, there is an increasing interest in developing optical fibre sensor for vapour detection in the chemical industry and in fact many sensor had been developed [1]. Some are based on the deposition of a sol-gel-based material either over the core of an optical fibre [1] or onto the thinner zone of a biconically tapered optical fibre [2]. Others are based on Fabry-Perot interferometers [3]. Also there are sensors based on the reflection of the light on films, on the fluorescence of dye-doped polymer cladding in fibre, on colorimetric reagents in the core of a silica fibre or on surface plasmon [4]. The possible materials for the construction of such sensor should be colorimetric reagents able to change the colour or refractive index in the presence of same organic vapours. There are not many metallic complexes with these properties, although same interesting examples have been reported in the chemistry of palladium and platinum as [Pt(p-R-C6H4NC)4][Pd(CN)4] described by Nagel [5] and Mann [6], which reported the construction of some LEDs. We recently reported the preparation of a novel vapochromic material (Fig 1) [7] which can be used for the construction of optical fibre tapered environmental sensors [8,9] of vapour organic compounds (VOC´s). Also we reported other nickel and palladium derivatives which present this type of behaviour [10]

Oct 1, 2003

By A. Coulombe

"RésuméL’analyse des séquences d’exploitation, actuellement en usage pour les gisements très inclinés, a démontré qu’elles ne sont pas toujours optimales du point de vue du contrôle des terrains et de la concentration des travaux d’abattage (nombre de chantiers simultanément en opération). Effectivement plusieurs séquences sont très propices à la création des nombreuses zones de hautes contraintes, qui sont à l’origine des effets de pilier. L’étude de cas de la mine Lac Shortt a démontré que certaines séquences d’exploitation, actuellement en usage, ne sont surtout pas adéquates dans le cas d’un état élevé des contraintes naturelles. En effet la mine a eu de sérieuses problèmes avec le contrôle des terrains (coups de terrains et les effondrements des épontes). Ces effondrements étaient responsables de la dilution excessive et des pertes importantes des réserves minières. Les deux nouvelles séquences proposées, visent la meilleure redistribution des contraintes d’exploitation en vue d’éliminer la création des effets de pilier. En plus elles permettent une concentration plus élevée des travaux d’abattage.À notre avis les séquences proposées pourraient améliorer substantiellement la stabilité des chantiers d’abattage et par la suite les performances technique et économique des opérations souterraines. ABSTRACTThe planning of underground mining sequences represents an important aspect of the mining operation. The analysis of mining sequences actually in use for very steep orebodies has demonstrated that they are not always optimal, considering ground control and the number of stopes simultaneously in extraction. These sequences are conducive to the creation in the rockmass of several stressed zones caused by pillar effects. The case study of Lac Shortt mine showed that the sequences of exploitation currently in use are not adequate especially in the case of a high state of the natural constraints. Indeed, the mine had serious problems with ground control (rock bursts and collapse of walls). These collapses were responsible for excessive dilution and significant losses of mining reserves. The two new sequences suggested aim for the best redistribution of exploitation constraints in order to eliminate creation of pillar effects. Moreover, they allow a higher number of stopes to be extracted simultaneously. In the opinion of the authors, the sequences suggested could substantially improve the stability of working areas and, thereafter, technical and economical performances of the underground operations."

Jan 1, 1998

By R. S. Jr. Stronach

"IntroductionThe property of Campbell Red Lake Mines, Limited, is in Balmer township, Red Lake area, Patricia portion of Kenora district, Ontario. It consists of a group of twelve claims which had been staked and re-staked a number of times before George W. and Colin A. Campbell staked them in 1944. Messrs. Brewis and White incorporated Campbell Red Lake Mines, Limited, in July, 1944, to acquire these claims from the Campbell brothers, and in November of the same year re-assigned their option on the controlling interest of the treasury shares to the Dome Exploration Company (Quebec), Limited, a wholly owned subsidiary of Dome Mines, Limited.A long known exposure of sulphides on the northeasterly portion of the property, which returned low gold assays, on sampling, was the only showing of interest at this time. However, Dr. H. C. Horwood's report and map of the district had recently been published and favourable structure W3.S indicated in Balmer township. It was on the strength of this showing and Dr. Horwood's report that Dome Exploration became interested in the property.Between. January, 1945, and April, 1946, a diamond drilling programme was carried out, with completion of sixty-one holes. Five holes proved the surface showing to hold no commercial interest, so routine cross-sectioning of the property from north to south was started. The fourth hole of the series returned excellent ore intersections and from that time on the programme changed to one of extending these values. The final results of the drilling showed that what is now known as the A zone has a continuous length of some 1,200 feet, a width of 4½ feet, and an overall grade of about 0.5 oz. gold per ton. There were many other intersections of ore grade outside this A zone which could not be successfully correlated .at that time, but underground work has opened many of them. It may be said here that practically all the work to date has been confined to the southeast claims of the property."

Jan 1, 1950

By Dwayne D. Tannant

This paper presents a summary of results from a questionnaire sent to surface mines in western Canada seeking information on haul road design, construction, and maintenance. There has been a marked increase in the size of the trucks used over the last decade with some mines now using trucks with a payload capacity of 360mt. Consequentially, geometrical elements of haul roads, such as width, have been enlarged to accommodate larger trucks. Most haul roads are constructed on the basis of past experience without use of formal design procedures. With the introduction of larger haul trucks, problems related to rolling resistance, deterioration, and maintenance of the haul roads have become more important. This has lead to adoption of more rigorous design methods for roads at some mines, most notably for the oil sand mines operated by Syncrude Canada Ltd. A summary of the evolution of haul road designs implemented at Syncrude Canada Ltd. is presented.

May 1, 2001

By K. Swedburg, M. Samuels

"The expansion of the concentrator at New Gold’s New Afton copper-gold mine in British Columbia, Canada, completed in 2015, included an increase in the required retention time of the cleaning circuit. On site pilot testing of a Woodgrove Staged Flotation Reactor (SFR) had shown that a high grade copper concentrate would be produced with excellent recovery. The SFR was selected rather than conventional tank cell technology based on the much smaller footprint (which rendered a separate and expensive building extension unnecessary), high concentrate grades demonstrated in testing, and the lower energy requirement. Three SFRs, each capable of taking a nominal feed of 700 cubic meters per hour were installed and commissioned 10 months after the receipt of order. The SFRs operate in series and all of the cells produce a final concentrate typically grading 32% Cu, while the overall SFR stage recovery averages 55%. The tailings from the SFRs are treated in the original conventional three-stage cleaner circuit where the remaining values are recovered in a concentrate grading 28% Cu. Design production was achieved within days of the initial start-up of the SFR circuit.INTRODUCTIONThe New Afton concentrator, located near Kamloops, British Columbia, Canada processes a copper-gold ore with a designed head grade of 0.96% Cu, 0.72 g/tonne Au, and 2.22 g/t Ag.The New Afton Mine is a block cave mining operation. Ore is undercut from the bottom up and removed at the extraction level from a grid of draw points. Ore is trammed to the ore passes by underground loader and dropped to a haulage level for transport by trucks to the gyratory crusher. From the crusher, the ore is conveyed to the mill via a 4.5 kilometre long conveyor system. Block caving was chosen for the New Afton deposit because the underground infrastructure could be built below the historical open pit of the Afton Mine (a previous operation of Teck Resources) and this method is favorable to large-scale low-cost mining.The New Afton deposit is a copper-gold, alkalic porphyry system. Hypogene mineralization is characterized by discontinuous copper sulphide veinlets and disseminations, principally chalcopyrite and minor bornite, along with pyrite as the second most dominant sulphide. Gold particles vary in size from 5 µm to 40 µm and occur as native gold and electrum, associated mostly with the chalcopyrite grains and never with the pyrite. In some instances, a second alteration phase has resulted in the copper sulphides being replaced by tennantite-tetrahedrite locally and along faults that transect the mineralized body. The design head grade of arsenic is 244 PPM, although the presence of tennantite is inconsistent and can vary from trace levels to 15% of the total copper. No arsenopyrite is present in the hypogene ores. Supergene mineralization, consisting of native copper with accessory chalcocite occurs in minor amounts along faults and highly oxidized near-surface portions of the deposit."

Jan 1, 2016

By Sylvain Castonguay, Sylvain Pilon

"Operator competency is an important factor in the safe and successful operation of today’s complex processes. Competent process unit operators deliver superior performance and results. In greenfield projects, operator competency is particularly critical, as the lack of specific operations experience must be offset with proven practical knowledge and skills to avoid mistakes that can cost millions in terms of start-up delays, production losses and equipment damage. It is, therefore, important to know precisely what competencies are required for a project or site, and what any gaps in operator competency need to be addressed and improved. The success of plant commissioning, start-up and sustainable operations is directly tied to operator competency. The significant investments required for new projects, the exploitation of more challenging ore bodies, and the increasing complexity of plant operations have placed renewed emphasis on the need for competent operators. Furthermore, many large capital projects are being developed in remote regions, often with ties to the delivery of social benefits for the local population in terms of jobs, training and other development opportunities. While automation and processing technologies have helped do more with less, indicators now point to a bottleneck in human performance limiting operational results.Automation industry development in managing abnormal situations, including solutions for simulation and operator training, has produced applications to provide customized and flexible training methods. This paper will discuss tools to automate the operator competency process in order to guide trainers to effectively teach, measure, control, provide feedback, and monitor operator skills. Today’s competency management solutions can be effectively applied throughout the course of an operator’s professional life, as a guide to hiring new operators, for developing competencies to support operations, and also to develop and refine best practices and share lessons learned."

Jan 1, 2016

By J. G. MacGregor

At this, the opening meeting of the Western Quebec Branch of the Institute, it seems fitting that the first paper presented should embrace a survey of the known mineral deposits occurring in the area, and also a review of ?the exploration methods that have brought about their discovery. And since the study of geological structures must always be the guiding principle of an intelligent exploration campaign, it also seems to be the appropriate occasion to review the geological situation from the economic angle, in an attempt to arrive at a re-statement of the known facts governing the deposition of the mineral bodies . . It is not my intention to confine my remarks entirely to the geological problems involved, but rather to pass under review the exploratory methods that have been employed in the past and that are presently being used, and to offer a forecast of the type of exploration campaign that will be largely adopted in the future search for ore.

Jan 1, 1929

By F. P. Hassani, J. F. Boily, A. M. O. Mohamed, M. Hossein

The optimal geochemical parameters required to form ellringite in a lime-remediated site have been investigated with the use of thermodynamic modelling. The speciation of sulphate and 10 metals analyzed in samples of a mine tailing from northern Quebec was calculated with a computer model. The model also includes calcium, which would result from the addition of lime to the system. Two speciation calculations were done. The first one is a hypothetical speciation before the onset of precipitation and was used to devise the stability fields of minerals susceptible of forming in high pHs. The stability fields were determined by building activity ratio diagrams with sulphate, aluminum and calcium species concentrations for pHs ranging from 4 to 14. The investigation was carried out for a 25°C solution with an ionic strength less than 0.12. Thermodynamics predict that an optimal stability field for ettringite in the mine tailing samples containing 10-3 mol/L SO4-2,10-2 mol/L of AI(OH)4 requires at least 10-2mol/L of Ca+2 and a pH larger than 11.6. The sulphate contents of the mine tailing samples, however, limit the precipitation of ettringite and monosulphate could be an end-precipitate. The second speciation is in equilibrium with precipitates and provides information on the speciation of the residual metals. If ellringite could be precipitated as a stable form, it could serve as a sorptive agent for residual metals, and, due to its binding properties, consolidate tailings.

Jan 1, 1995

By P. H. Shipway, D. G. McCartney, H. Saghafifar

The microstructural changes during thermal ageing at 650ºC in the interfacial region of Alloy 625 weld overlay on a 2.25Cr-1Mo steel was evaluated. Optical microscopy, scanning electron microscopy in SE and BSE modes, electron probe microanalysis and hardness mapping were used to characterize as-welded microstructure and its changes during thermal ageing and precipitates of interfacial region. Carbon migration across the interface was recognised as a major issue. A region of 300 µm wide adjacent to the fusion line, which was found harder in the as-welded condition decarburized during thermal exposure. Studies revealed that this region transformed to a soft region containing large ferrite grains and micron-sized carbides. In the weld overlay, a 50 µm wide hard band (over 650 Kgf mm-2) adjacent to the fusion line formed and carbide precipitates were observed along grain boundaries. Carbide precipitation mostly occured in the 150 µm wide region close to fusion line.

Jan 1, 2017

By F. E. Goodwin

Since the last CIM Zinc and Lead Conference ten years ago, significant technical and market forces have influenced how these metals are used, and the geographic distribution of their uses. Unprecedented price fluctuations have opened competitiveness issues, while the rapid growth of the Chinese market has created challenges both inside and outside China. Recent technical developments in battery energy storage, coatings, castings and chemical applications of lead and zinc will be reviewed together with the influence of these trends on end use markets.

Jan 1, 2008