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By Daniel Lachapelle, Nuri Hmidi, Turgut Yalcin

"Simulation can serve as a convenient tool in studying the behaviour and performance of grinding circuits by facilitating the evaluation of various scenarios and identification of optimum operating conditions. This technique was applied to the St Andrew Goldfields Ltd.’s Stock Mine Mill which is a 1300 tpd gold milling facility, offering custom milling services as well as processing the Company’s own ores. Lack of adequate instrumentation in the mill poses a challenge in attaining optimum performance especially with changing ore types and characteristics. The grinding process is monitored essentially by manual measurement and adjustment of pulp densities at various streams. A simulation program was designed to assist in the effective implementation of this mode of grinding control. Product sizes from both the primary and secondary grinding circuits were correlated empirically to relevant process variables using a database formed from the results of past sampling campaigns. The simulator was created in Microsoft Excel whose data analysis and optimization tools coupled with its Visual Basic Programming capabilities were found to provide an excellent environment for the development of a cost-effective, efficient and user-friendly simulation program.INTRODUCTIONGrinding is often a very costly unit process in milling operations, mainly due to the excessive energy consumption associated with it. For example, for a Canadian copper-zinc flotation mill, grinding was listed as being the most costly item taking up 30.4% of the total milling expenses, followed by the flotation cost at 2 1 .O% (Kidd Creek Mines Ltd., 1982). A survey on 45 copper flotation mills around the world showed the average grinding cost to be 34.5% of the total milling cost (Weiss, 1985).Overgrinding aggravates the cost issue, while insufficient grinding either causes loss of valuable minerals to tails or results in low-grade concentrates. Therefore, it is essential that grinding circuits be carefully controlled and monitored. To this end, a great deal of effort has been devoted over the years to the modelling and simulation of grinding systems in order to assist in the efficient running of these processes."

Jan 1, 2001

By Corrie Pitzer

Safety performance in many companies and even industries has stalled in the last decade. Accidents rates are improving but more slowly and yet, serious accidents and fatality rates are not: in fact, these rates of more serious incidents have plateaued or deteriorating. In more dramatic cases, organizations that had ?exemplary? safety statistics, suddenly had a catastrophic or multi-fatality event occurring. Popular books such as In Search of Excellence of Peters and Waterman or Good to Great of Jim Collins created many delusional ?secrets? or recipes, to achieve great performance and yet, most of those ?great? or ?excellent? companies have now declined in their performance, some dramatically and some have fallen from grace, like Fanny Mae, a company Jim Collins identified as a ?great? one, that had to be bailed out in the latest financial crisis. These organizations share several ?delusions? about managing a business, and often, these delusions are created by academics, consultants and authors of popular books about (safety) management. More damaging however is that safety management is defined by a set of key practices or axioms: a focus on human error, compliance to rules and regulations, creating consistency of systems and actions, reacting to accidents and incidents and on prevention of those, measuring safety with performance metrics and rewarding employees on those measurements. All of these axioms contain the seeds of destruction, and they create conditions and dynamics that precede the disaster - and ironically, they are all 'good things' we do in safety management. For example, a mere focus on safety in the business, and the measurement of it, create a culture of repression of mistakes and incidents, leading to a situation where the organization knows incrementally less and less of risks and risktaking behaviour - until the day it all coincides destructively! This paper discusses seven such safety delusions and how they impact on the views and safety management approaches. They are: ??The delusion of (risk) control, that risks can actually be identified, analyzed and mitigated. ??The delusion of compliance, that mere compliance to rules will safeguard the business ??The delusion of consistency, that standard operating procedures will ensure safe operations ??The delusion of predictability, that accidents and trends tell us everything about the risks of the future ??The delusion of human error, that people are the weakest link and that it can actually be dealt with through discipline and enforcement. ??The delusion of statistical trends, that safety is measurable with statistics ??The delusion of invulnerability, that we have achieved high levels integrity and capability to deal wit risks. Organizations that suffered catastrophes all share some or all of these delusions and this paper traces how these played a role in many disasters, ranging from the Titanic, Challenger, Piper Alpha, Bhopal, BP Deepwater Horizon and many more.

Aug 1, 2013

By Lachezar Tsotsorkov

Being a mining company, Assarel-Medet has a significant impact upon the environmental components. In order to meet the legal requirements and the requirements stipulated by the effective permits as well as to reduce the environmental imprint throughout the years, the policy of the company to implement a number of projects to improve the environmental components quality and the environmental state in the company?s region. The projects associated with atmospheric air quality management and reduction of the impact exercised by Assarel-Medet JSC by implementing various measures to eliminate the potential sources of the impact, preventive and rehabilitation initiatives as well as organizational and administrative activities are among the most important ones. A stable improvement of atmospheric air quality in the region and minimization of the company impact upon the ground air state in the region was observed in the period from 2005 to 2012 due to the applied measures. This project is a contribution to the environmental protection, in particular to atmospheric air protection, by applying integral monitoring and modeling methods to identify the negative impact by the mining companies and plan measures to reduce and restrict it as well as to improve the quality of the environment and living area of people working and living in the impact range as an element of sustainable development.

Aug 1, 2013

By Fred C. Bond

A study of the settling and thickening of finely divided pulps was undertaken with the object of obtaining certain fundamental relationships, with resulting improvements in the design and operation of mechanical equipment. The subject has been treated in two parts: testing and batch thickening, and continuous thickening, including calculations of capacity and dimensions. Part 1. ? Testing and Batch Thickening The usual method of making thickening tests is to agitate the pulp with a plunger in a graduated glass cylinder and let it settle, while recording the time rate of settling. The settling rates corresponding to different pulp dilutions are found, the ultimate dilution obtained is measured, and the necessary thickener area in square feet per ton of dry solids per 24 hours is calculated, for each pulp dilution. The largest area found is used in selecting the proper thickener size.

Jan 1, 1946

Cominco began investigations about ten years ago relative to noise abatement in underground operations. As a result of intensive research, this study has advanced so that the practice now has wide application. Automotive mufflers are used on vane-type blasthole diamond drills. Exhaust hoses are attached to longhole percussion drills. Hand-held drills, such as airlegs and stopers, are equipped with mufflers which are either part of the drill, as received from the manufacturer, or are light rubber de-vices developed, fabricated and installed by Cominco. Ear defenders are in general use. The paper reviews details of practices employed, and assesses the success achieved. Noise is generally associated with some of the basic equipment used in mining. About ten years ago, in order to improve on this situation. The Consolidated Mining and Smelting Company of Canada Limited began investigations relative to noise abatement in its underground operations. As a result of intensive research, this study has advanced to the point

Jan 1, 1964

By G. R. Elliott

Foreword The office of the Supervisory Mining Engineer, a branch of the l. Federal Government, is financially interested in no oil company and has no stock to sell. This office, however, is deeply interested in the proper and efficient development of Canada's natural resources. The people of Canada are interested in the petroleum development in Turner Valley for two principal reasons: As represented by the Department of the Interior, they are the largest owners of petroleum and natural-gas rights in the field; As a nation, they are vitally interested in the development of petroleum and natural gas as a national asset, and therefore, also, in all productive property, no matter who directly controls the leases. As has been stated by Mr. Charles C. Ross, Supervisory Mining Engineer, "The Department, being responsible for the administration of these public resources, necessarily requires regulations to protect them from abuse by lessees. Our portion of this responsibility is to record a complete history of all drilling operations and to see that proper drilling methods are adopted to prevent damage and wanton waste of the valuable natural resources under discussion." Not only does our position necessitate an impartial and a judicial viewpoint, but, being day by day in touch with all operations in the western provinces, we are uniquely situated to comprehend both individual and general problems.

Jan 1, 1930

By M. Al-Khawaja, F. Hassani, F. Mucciardi, N. Razavinia

"In today’s economy many industries are becoming aware of the need to recover some of the waste heat they create. Industrial processes release, on a global scale, over 100 tera-Joules (i.e. 1014 J) of waste heat annually. The recovery of waste heat can lead to a reduction of greenhouse gas emissions and it can also provide a financial benefit which can be obtained by converting some of this excess heat to electricity. At McGill, a research program has been initiated so that low grade waste heat (temperature between 100ºC and 300oC) from process off-gases found in pyro-metallurgical industries is captured and concentrated by using heat pipes and then converted to electricity by a mechanical engine. This paper illustrates the 3 C’s process (capture, concentrate and convert waste heat to electricity). It also provides some preliminary experimental data. INTRODUCTIONThe problematic climate change caused by the use of fossil fuels, the rapid depletion of global reserves and the catastrophic consequences of nuclear power generation call for renewable and safe, resources of energy, for both man and the environment. Extensive researches in the production of energy from renewable sources and improvements in efficiency of current technologies can help us to reverse this trend.The greatest advantages of using renewable energies are that they don’t deplete and they also contribute to a green environment. On the other hand the disadvantage of using these resources is that the energy available from renewable sources is much less concentrated than that provided by fossil fuels and nuclear energy. This makes renewable energy less attractive for large scale industrial uses in most cases. A key target for society for the 21st century is the production of energy from renewable sources at a cost that is competitive with fossil fuels. Fossil fuels represent a concentrated form of energy; usually it is referred to as high grade energy. Nonetheless, there is a vast supply of alternative energy. The sun, wind, water and biomass were the first to be explored. While these are all valid options that warrant concerted efforts and large investments, there is another source of energy that typically is produced by manufacturing industries. This energy is often referred to as low grade waste heat. Most of this energy is simply vented to the environment through the stream of off-gases. In the future it will be necessary to capture and convert some of the low grade heat to a valuable form such as electricity if we are to improve on the efficiency of energy usage."

Jan 1, 2012

By Jun Wang, Bo Zhang, Wenqing Qin, Guanzhou Qiu, Xiaozhen Ma, Key Lab of Biohydrometallurgy of Ministry of Education, Fen Jiao, Central South University, Yansheng Zhang

"Arsenic contained in minerals sulphides such as enargite and tennantite can represent not only a significant penalty element in base metals production, but also a disadvantage to the environment through producing the toxic emissions to the atmosphere. The achieving separation of arsenic bearing minerals either at an early stage in floatation or from the floatation concentration is significantly beneficial to the economic. However, there was no feasible commercial method of separation at the flotation stage because of its similar flotation properties with many other copper sulphides. In this work, the selective floatation of enargite from copper sulphide concentrate containing maily covllite, chalcoctie, bornite and enargite was investigated. A low arsenic concentrate with As 0.2%, Cu 22% and a high arsenic bulk concentrate with As 7.65%,Cu 33.65% were obtained. It was indicated that Ca(ClO)2 is the effective depressor and the optimum floatation condition was obtained. Most enargite could be floated at pH 11 and controlling the pulp potential at 290 mV SHE. Furthermore, the arsenic removal from the high arsenic bulk concentrate by hydrometallurgy methods was study. The results showed that the reaction temperature and the concentrations of NaOH were the most important variables affecting the rate of arsenic removal. A low arsenic concentrate with As 0.24%, Cu 37.80% was obtained in the optimum leaching condition.INTRODUCTIONArsenic is mainly produced as a by-product of base metals smelting, in particular copper concentrate. China has imposed an upper limit of 0.50% arsenic for concentrates entering (Long et al., 2012). Arsenic amount of copper concentrate within 0.40% has also been imposed in China, and above which will be introduced about 50 RMB penalties per ton for each 0.10% increasing by smelters now. Therefore, it is necessary to remove arsenic from the copper concentrate.In copper concentrate, arsenic is mainly in the form of arsenopyrite (FeAsS), enargite (Cu3AsS4) or tennantite (Cu12As4S13). There are two types of arsenic in the separation of copper and arsenic: arsenopyrite and arsenic bearing copper mineral. It is easier to separate arsenopyrite from the copper sulphide by flotation in comparsion with the separation of enargite or tennantite from non-arsenic copper minerals (Pineda et al., 2015). The main difficulty in the separation of arsenic copper mineral from non-arsenic copper sulphides is their extremely similar floatability, which depends on the fact that tennantite and enargite contain high copper content (Pineda et al., 2015)."

Jan 1, 2016

By R. K. Borden

Rio Tinto is committed to proactive mineral waste and acid rock drainage management. Corporate requirements are closely aligned with the GARD Guide principles of early geochemical characterization and prediction followed by selection and implementation of management strategies to prevent or minimize ARD. Each operation is required to design and implement an ARD and Mineral Waste Management Plan. Successful implementation of the plan requires commitment at all levels of the company, from senior management, to geologists, mine planners, environmental staff and equipment operators. Examples of the successful integration of ARD management strategies into mine operations are cited from several mines.

Jan 1, 2011

By C. S. Gibson

"MOST of the mines in the Province of Ontario in Canada are multi-level operations in steeply dipping veins; yet there is an appreciable number whose de-posits are relatively flat-lying, ranging up to 45° inclination.The veins vary in width up to several hundred feet and may or may not be branching systems. The depths of mines range from a few hundred to 8,000 feet, approximately. The primary products of the underground group are asbestos, gold, silver, cobalt, copper, nickel, iron, uranium, talc, fluorspar, gyp-sum and salt.There are a few open-pit mines. The majority are temporary in type because, as the outcrops are removed, mining is continued be-low surface. Primary products of the open pits are copper, nickel, iron, magnesium and nepheline syenite.The industry as a whole employs about 50,000 persons, approximately 60 per •cent of whom have dust-exposure occupations. The definition of a dust-exposure occupation and the requirements for •dealing with same are set forth in The Mining Act of Ontario.Results of extensive and continuing studies on the incidence and progression of silicosis have been reported periodically for years past, in annual reports of the Mines Accident Prevention Association of Ontario and in papers presented at Conferences sponsored by Mcintyre Research Foundation of Toronto, all of which have been published. The information provided therein proves the effectiveness of the means being used to prevent silicosis and allied disorders."

Jan 1, 1960

By C. H. Hopper

DIAMOND drills have played an important part in the development of mines for many years. Recently. they have also entered the production field arid the use of diamond drills m the primary breaking of ores has become a big branch of the industry. The writer has estimated roughly that the total diamond drilling in Canada during 1942 was 5,625,000 feet, of which 2,250,000 feet, or 40 per cent, was for blast-holes. This accounts for 6,750,000 tons of ore broken, using the conservative factor of 3 tons per foot of hole. Many consider that the use of diamond drills for blast-holes is the most important advance in mine practice of the past decade, and the industry owes a great deal to the staff of Noranda Mines, Limited, for the pioneering they have done in the development of long-hole mining methods and for publishing their results. A great many mines have followed Noranda's lead. At the Waite-Amulet, Aldermac, Flin Flon, Canadian Malartic, Hoyle, and Matachewan Consolidated mines, most of the ore is broken by long-hole blasting. While the mines were developing new methods, the diamond-drill industry was developing mechanically-set bits and better machines. Through the effective use o smaller, cheaper diamonds, as well as more efficient setting, bit costs per foot are only one-half what they were ten years ago. Few people realize that a diamond bit is relatively inexpensive. The common EXT coring bit, for example, contains some 200 small diamonds, weighing altogether about 2.70 carats which, at $3.40 per carat, cost $9.20. After use, the equivalent of about 100 of these diamonds may be recovered. Therefore the true cost of the bit is only $7.00, made up of $4.60, the cost of the diamonds lost, $2.00 for setting, and $0.40 tax. The trend in machines has been toward specialization for the different classes of rock in blast-hole work. Light, high-speed machines have been developed for soft ores and higher powered machines for hard ores.

Jan 1, 1943

By A. G. Doll

The Bond low energy impact (crushing) work index test is specified to be performed on rock specimens between 50 mm and 75 mm in effective diameter. NQ-diameter drill core, frequently used in mineral exploration programs does not meet that specification, it being 45 mm diameter or less. This paper reports the effect of performing the impact test on contiguous sections of HQ diameter and NQ diameter core, exploring the hypothesis that the contiguous intervals give equivalent results in spite of the core diameter difference.

Jan 1, 2012

By D. M. Ziebarth

"Normal sequence of operations to develop a new underground mine is: construct and outfit headframe for shaft sinking, sink shaft, construct and outfit shaft sump, develop shaft station and shaft bottom steel. In an effort to reduce the overall project schedule, an innovative plan was developed to install service shaft steel below station level, prior to the completion of the shaft sinking effort. To better evaluate the construction of this substantial steel tower, a preliminary constructability evaluation was conducted, including the best method of supporting the main tower; from the bottom, middle or top of the tower. The design criteria and plan involved: •,Develop access from existing service shaft, 25 km underground •,Use of materials to maximize strength while minimizing corrosion exposure •,Estimating the location of the shaft centerline •,Over excavating the station and shaft below station to allow future shaft steel repositioning •,Designing the tower steel for modular installation •,Incorporate commissioning considerations, such as suspension of the cheese weights during steel installation •,Provision for covered stair access to shaft bottom •,Enclosed shaft envelope with open panels to allow visibility and ventilation The design approach was innovative and this paper will describe the design principles and challenges encountered while providing insight into the solutions developed and implemented; especially the modular construction and installation methodology. INTRODUCTION In an effort to expand the mining operations, a plan was developed to construct a new service shaft closer to the new mine workings and convert the existing service shaft to a production shaft at the Potash Corporation of Saskatchewan Inc. (PCS now Nutrien) Rocanville Potash mine in southeast Saskatchewan. The new service shaft required a multi roped friction hoist operating a cage / counterweight, rope guided conveyances to support the operational requirements. The service shaft is an integral part of the mining infrastructure as it provides access to the underground workings, transport personnel and materials underground for operation and maintenance of the mine. The shaft also allows for services required for safe operation of the underground mine, power supply, controls, communication, dewatering and fresh water supply."

Jan 1, 2019

By N. Aslin, G. Heferen, H. DeWaal

"Mount Isa Mines (MIM) acquired a reputation for the successful application of R&D to develop break-through technologies for the mining industry starting in the 1978’s through until the early 2000’s. The ISAPROCESSTM tank-house technology has been licensed to copper refineries throughout the world, and a significant per cent of the world’s copper is refined using this technology. Since development in the late 1980’s more than 20 ISASMELTTM copper and lead smelting furnaces are now installed in countries around the world. Jameson Cell flotation technology developed jointly by Mount Isa Mines and Professor Graeme Jameson is widely used in the Australian coal mining industry and increasingly in the base-metal and gold industry. The IsaMillTM’s developed at Mount Isa and McArthur River made it possible to develop the McArthur River and George Fisher orebodies and has been successfully implemented into base metal fine grinding applications around the world. The most recent commercialised innovation is the atmospheric leach Albion ProcessTM with its supersonic HyperSpargeTM gas sparger, is being adopted as a solution to the increasing complexity of orebodies. MIM’s contribution to the industry was significant given the size and the remote location of its operations with Townsville Copper Refineries more than 1350 km and Mount Isa 1800 km from the nearest state capital of Brisbane. This paper will briefly discuss the development of each of these technologies and why MIM – now owned by Glencore - was so successful innovating and developing such technologies over a period of nearly 40 years.INTRODUCTION Mount Isa is located in the Gulf Country region of Queensland about 1800 kilometers North West of Brisbane (see Figure 1). It came into existence because of the world class mineral deposits found in the area. In 1923 the orebody containing lead, zinc and silver was discovered by the miner John Campbell Miles. Mount Isa Mines Limited (MIM) was founded in 1924 to develop the minerals discovered by Miles, but production did not begin until May 1931. It paid its first dividend in 1947 after 16 years of troubled production. In 1954 the 1100 copper orebody was discovered and with rapidly rising reserves during the 1950’s and 1960’s led to the construction of new concentrators to treat lead/zinc/silver ores in 1966 (#2 concentrator) and copper ore’s in 1973 (#4 concentrator). The difficult nature of the Mount Isa lead-zinc orebodies has meant that the company had always needed to be at the forefront of mining technology. In the 1970’s through to the 1990’s, it became a world leader in developing new mining techniques and processing technologies as a response to declining metal prices and rising costs. Mount Isa has been smelting copper since 1953 and lead since the early 1930’s. Copper Refining at Mount Isa’s fully owned subsidiary of Copper Refineries Proprietary Limited (CRL) had commenced operations in 1959."

Jan 1, 2018

By Mehmet Guney

This article is based on a detailed heat investigation conducted at the Rokana Division of Nchanga Consolidated Copper Mines Limited while both authors were employed in Zambia. Mindola Mine is one of the three underground mines comprising the Rokana Division on the Copperbelt of Zambia, producing about 270,000 tons of ore per month at 1.9% Cu and 0.14% Co. The total volume of air being circulated by means of five primary fan installations slightly exceeds 1,000 m3/sec at standard density. Sectional bulk cooling is practised where air cooling coils are installed at primary splits some considerable distance from the stoping operations. Total capacity of the refrigeration complex is 10,500 kw (3,500 R. tons), of which about 7,000 kw is available as effective cooling power after losses, but the heat removed from the coifs is about 3,500 kw with 61% over-all plant performance. An extension program is planned for a further five production levels with the re-deepening of a sub-vertical shaft. Thermal heat will become a major problem at increased depth associated with higher rock temperature, higher thermal conductivity of the rock groups encountered and fissure water flowing into working areas through the strata with increased rock temperature. This paper describes the ventilation and refrigeration practices in Mindola Mine, with special reference to future thermal heat problems. These are discussed with a view to mining at depth.

Jan 1, 1979

By C. Kunze

ABSTRACT Although closure sureties cover works that are carried out during the existence of a mining company, certain liabilities are not known when the surety is established and become apparent only in a late stage of the closure phase, or even after the site has been relinquished. This paper supports the concept that these financial risks lend themselves to insurance solutions. Making insurance for unknown liabilities mandatory while defining unambiguous legal conditions could create a viable market for insurance products, provide a sufficient statistical basis for the calculation of premiums, and reduce costs.

Jan 1, 2013

By G. J. Biefer

"Fatigue and corrosion fatigue measurements were carried out on five commercially available metals -four steels and an aluminum alloy -which are used as structural materials in mine shaft conveyances. In the corrosion fatigue measurements, drain waters collected in the shafts of three different Canadian mines were used as corrodents. The mine waters had been selected on the basis of their relatively large differences in acidity and/ or composition.It was found that the corrosion fatigue strengths of the four steels were similar, despite their differences in tensile properties, and that the type of water used in the tests had little effect on the results. Mild steel showed the highest and most consistent values of the damage ratio (ratio between the corrosion fatigue and the plain fatigue strengths at 107 cycles). The corrosion fatigue behaviour of the aluminum alloy (ASTM Type 6061-T6) was found to differ markedly in the three mine waters. A high damage ratio (i.e., superior performance) was shown in a mine water in which the corrosion attack was uniform; much lower damage ratios were shown in waters which produced localized corrosion attack. Corrosion rates were too low to be deter-mined conveniently by conventional weight-loss methods, but calculations from polarization curves provided a rapid demonstration that corrosion rates were distinctly lower in the mine water which produced high damage ratios."

Jan 1, 1967

By M. E. Hurst

Introduction Between 1903 and 1905, W. Mclnnis, of the Geological Survey of Canada, made a micrometer traverse of the Kawinogans (Crow) river from Kapkichegimaga lake to its junction with the Otoskwin river. He reported that a belt of Keewatin rocks, 1 to 4 miles wide, was exposed along the course of the river for 17 miles east of Kapkichegimaga lake. Prospectors and exploration companies paid little attention to the mineral possibilities of this belt until the summer of 1928 when, with the adoption of airplane transportation, the area became readily accessible. Within a short time widespread interest was aroused by the announcement of attractive finds, and a mild rush followed. During the winter months, hundreds of claims were staked on either side of Crow river for 12 miles east of Pickle lake. In the summer of 1929, much of this ground was systematically explored and a considerable amount of development work was done on the known deposits.

Jan 1, 1930

By D. Milne, G. Snell

"A new method to predict stope hangingwall failure in underground excavations is proposed. This method compares movement rate for stope hangingwalls, determined from changes in strain or deformation, with changing opening geometry. This geometry is represented by the effective radius factor (ERF), a measure of relative distance to supporting abutments from an opening surface point. This strain-ERF (SERF) approach is applied to an instrumentation program for Brunswick mine near Bathurst, New Brunswick. The SERF method for this case study predicted failure at an ERF of 13.9 m and hangingwall failure actually occurred at an approximate ERF of 12.4 m.RÉSUMÉ Cet article propose une nouvelle méthode permettant de prévoir la rupture de l’éponte supérieure des chambres d’abattage dans les excavations souterraines. Cette méthode compare la vitesse de mouvement des épontes supérieures des chambres d’abattage, déterminée à partir des changements aux niveaux des contraintes ou de la déformation, à la géométrie variable de l’ouverture au jour. Cette géométrie est représentée par le facteur du rayon effectif (ERF, de l’anglais Effective Radius Factor), une mesure de la distance relative jusqu’aux appuis latéraux de soutènement à partir d’un point de la surface d’ouverture au jour. Cette approche contraintes-ERF (SERF, de l’anglais strain-ERF) est appliquée à un programme d’instrumentation pour la mine Brunswick située près de Bathurst, dans le Nouveau-Brunswick. Pour cette étude de cas, la méthode SERF prévoyait une rupture à un ERF de 13,9 mètres (m); la rupture de l’éponte supérieure s’est effectivement produite à un ERF d’environ 12,4 m.INTRODUCTIONUnderground stope design can be improved with the installation of field instrumentation. The most commonly used instrumentation for monitoring rock mass behaviour around open stopes is extensometers. The y-axis of Figure 1 represents how the changing rate of movement, measured using either displacement- or stress-type instruments, can be observed over time. The magnitude of movement measured by extensometers can give an approximation of the load on installed support (Milne, Pakalnis, & Lunder, 1996) and a changing rate of movement can indicate approaching instability."

Jan 1, 2018

By M. Boher, J. Lehmann, M. C. Kaerlé

"In the production of high quality steel, the understanding of the interactions between liquid steel and refractories and of their effect on steel purity and cleanness are becoming more and more important.An experimental study has been per-formed in order to estimate the importance of the reaction between a MgO-based tundish refractory and an Al-killed steel. The results show a pollution of the liquid steel:•the silicon content of the liquid steel increases due to the reduction of the silica of the refractory by the aluminum contained in the steel; and•a reoxidation of the steel occurs and the formation of an oxide layer on the refracto-ry, mainly composed of spinel crystals and of Ca-aluminates is observed.The transfer mechanisms of the various elements are analyzed."

Jan 1, 1997