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By C. A. Sutherland

"Smelting of copper-gold ore from nearby Rossland mines started at Trail in the 1890s. As ore from the Rossland mines became exhausted, lead smelting offhand-sorted galena orefrom other British Columbia mines was initiated. With the development of flotation technology for the separation of lead, zinc, and iron sulphides in the first two decades of this century, the large Sullivan orebody at Kimberley, British Columbia, became the foundation for the growth of a major zinc and lead smelter at Trail. Lead smelting began in 1901, electrolytic zinc in 1916, and by 1984, the Trail metallurgical complex had produced 10 million tons of each metal. Its present capacity is 270000 tonnes per year of zinc and 110 000 tonnes/year of lead.This paper reviews the history of technological changes in the Trail production plants, emphasizing the zinc plant modernization program started in the 1970s, and also the planned introduction of the QSL oxygen lead smelting process in the late 1980s. Lead modernization will increase production capacity to a maximum of 160000 tonnes per year.IntroductionCopper-gold ore was discovered at Rossland, British Columbia, in the year 1890, starting a mining industry that was to last over three decade s. Selected ore was at first transported at high cost to distant U.S. smelters, so there naturally followed a decision to construct a small copper smelter to process the local ore to matte. It was built in 1896 at the mouth of Trail Creek on the Columbia River, about 10 km from Rossland. This little smelter was to develop and diversify in the next 90 years into the world's largest lead-zinc produce.The mining boom that occurred in the northwestern United States and southeastern British Columbia in the period of 1890 to 1910 saw the brief operation of many small local smelters. The only one to survive was the smelter at Trail. The circumstances that permitted its continued life and subsequent growth, form a fascinating history of business deals, litigation, and steady technical progress.Early investment in local railway transportation and options by F.A. Heinze, the smelter' s founder, attracted the attention of the Canadian Pacific Railway Company, which purchased Heinze' s assets in 1898. This provided the capital base for survival and growth of the smelter, which remained and prospered under the Canadian Pacific umbrella for almost ninety years. It was registered as the Consolidated Mining and Smelting Company of Canada Limited in 1906; in 1966, this name was shortened to Cominco Ltd."

Jan 1, 1988

By R. H. Chambers, L. Alderman

"The paper is introduced by an examination of the factors which have led to the present world-wide interest in charging preheated coal to coke ovens. Various possible methods of preheating and charging the coal are considered and reasons are given for the adoption of the methods chosen. The design of the pilot preheating plant for the British Coke Research Association is discussed and its influence on the design of the commercial units for the South African Iron and Steel Corporation's plant at Pretoria and the British Steel Corporation's plant at Beighton are explained. Operating procedures on the pilot plant are described, particularly with regard to the charging of the preheated coal. Design features of the commercial installations, engineered by Simon-Carves Ltd., are explained with emphasis on the built-in safety of the control system of the preheating plant, and the particular problems associated with the erection of such plants on working coke oven batteries. Commissioning and operating procedures are described and the problems associated with the integration of the preheating plant into the normal pushing schedule of the plant are discussed. Preliminary operating results with regard to the effect of preheating on coal throughput on the commercial plants and on the properties of the coke produced are given."

Jan 1, 1972

By P. Karimi, G. Mollataheri, A. Amini, H. Abdollahi, A. Mirzaeian

"Chah-Palang tungsten deposit is one of the two tungsten indexes in Iran. Based on ore characterization techniques (including optical mineralogy and XRD analysis), quartz, chlorite, atacamite, azurite, malachite, ferberite, illite, goethite and calcite were distinguished as major minerals. The representative sample was analyzed qualitatively by using X-ray fluorescence and chemical assay. Results showed that grade of tungsten oxide and copper were 1.76 and 7%, respectively. Also precious metals such as gold with grade of 1 ppm was reported in the sample. By using the mineralogical studies on the prepared sample, the liberation degree of tungsten minerals in –0.6 mm size fraction was obtained 80%. Several tabling tests were carried out on the original sample which at the optimum conditions and as a result, the grade and recovery of tungsten in concentrate reached to proximately 23 and 59%, respectively. To increase the grade of tungsten in the final concentrate, acidic leaching were performed on the tabling concentrate and its appropriate results indicated that the grade of tungsten increased to 27%. Also more than 90% of copper was extracted as a byproduct in the fallowed process.INTRODUCTIONTungsten, a unique hard, heavy heat-resistant metal, is distributed erratically in economic concentrations throughout most continents, occurring mostly as small irregular deposits that are not readily adaptable to large-scale, low-cost mining methods. The diverse physical characteristics and mineral composition of tungsten ores also present problems in beneficiation, requiring complex hydro- and pyrometallurgical treatment to yield high-purity concentrates suitable for the production of ferro alloys, carbides and super alloys in the steel industry (Hausen, 1989; Kholmogorov & Kononova, 2005). Tungsten is most frequently used as tungsten monocarbide, which has hardness close to diamond, in cemented carbides. The most well-known use of tungsten is in lighting filaments, and other important applications include improving steel properties and use in tungsten alloys, electronics, and chemical products (Hausen, 1989; Kholmogorov & Kononova, 2005)."

Jan 1, 2016

By S. R. Stopic

The EU-financed INTREAT Project (Integrated treatment of industrial wastes to¬wards prevention of regional water resources contamination) addresses the environmental pollution associated with solid and liquid wastes/effluents produced by complex sulphide ore mining and metallurgical activities. The results concerning the electrolytic recovery of cop¬per from effluents formed after mixing of streams from Copper Refining, Precious Metals Plant and Electrolyte Regeneration in the Balkan Area will be shown. The waste water is characterized by low pH values and high contents of heavy metals, such as Cu, Ni, Bi, As, Sb. The majority of these waste water flow untreated into the natural water streams and through the network of existing rivers, which end up in the river Danube. The influence of current density and flow rate on the deposition rate, the quality of copper and the process efficiency will be presented. The full continuous process is based on cells with rotating disc cathodes and represents a pre-treatment step before common neutralisation in a cascade line

Jan 1, 2007

By Z. Luo, China University of Mining & Technology, C. Duan

"The magnetic separation removal rate of pyrite could be improved effectively by increasing the susceptibility of pyrite. The electromagnetic characteristics and absorption response performance of high-sulfur fine coal were studied in strengthening the susceptibility of pyrite. In the process of treating the sample through the microwave, electromagnetic energy could be converted into heat energy due to dielectric loss and magnetic loss. The RL(dB) was evaluate the performance of absorption response of coal. The microwave improved the susceptibility was in ultra-high frequency region, which is the most natural resonance. The absorption fine coal to microwave was strengthened and microwave energy was improved by adding the magnetite powder with double loss characteristics as the microwave absorber. The dielectric properties and permeability characteristics of the fine coal trend were investigated by maxing magnetite powder. The microwave absorption in different coal thickness was surveyed through the reflection of energy loss.INTRODUCTIONMicrowave desulfurization is one of the most important research directions (Haque, 1999; Makul, Rattanadecho, & Agrawal, 2014; Su, Tang, Zhang, Jing, & Bai, 2014). The working principle of microwave absorption response can be briefly described as the interaction of the sample with microwave energy, which will result in the microwave energy converting into heat energy loss (Keangin & Rattanadecho, 2013). For specific samples, the polarization effect includes multiple polarization mechanisms(Meikap, Purohit, & Mahadevan, 2005). Different polarization mechanisms have different occurrence time and dominant mechanisms. Meantime, energy consumption will be occurred during the process of polarization effect (Chelgani & Jorjani, 2011; Rowson & Rice, 1990) . The absorption of microwave energy in the fine coal is a process of electromagnetic response (Znamenácková, Lovás, Mockovciaková, Jakabský, & Briancin, 2005). Microwave transfers the electromagnetic waves into the heat energy by microwave dielectric loss and magnetic loss for achieving the absorption of microwave energy in the treatment of samples (Lee, Kim, Kim, Chung, & Kim, 2004). The additive magnetic medium is Fe3O4 belonging to microwave energy absorber of double loss medium (Uslu, Atalay, & Arol, 2003)."

Jan 1, 2016

By L. K. Daneshmend

The mine of the year 2020 will need to be based on a new way of mining. It will employ technology in a paradigm that assumes responsibility for sustainable development: taking account not only economic but also ecological and social issues. This will require a holistic approach to mine design and planning, considering all controlling factors and impacts (technical, economic, environmental and social). A national collaborative strategy is required to address the several options that exist for the development and application of 2020 mining technology. Key issues in implementing 2020 mining technology will also relate to human resources, in terms of employment, skills and education. A need exists to proactively prepare for 2020 through development of a comprehensive education and training strategy.

Jan 1, 1998

The integration of mining and mineral processing technologies into new advanced mining systems is considered to offer several benefits, including selective mining, reduction in waste, increased productivity, flexibility, and improved resource utilization. This paper focuses on underground hardrock mining and the integration of pre-concentration technologies into future mining systems as representing realistic, shorter-term integration options. Control of fragmentation to optimize grinding, pre-concentration of ores, in situ leaching, and modular mining/mineral processing systems are possible with existing technology. Current research is directed toward development of integrated underground systems that minimize surface activity and minimize or eliminate surface waste disposal. Results from a simulation model of an integrated underground pre-concentration system are presented.

Jan 1, 2002

By Vladislava A. Ignatkina, Fillip O. Milovich, Vladimir A. Bocharov

"Complex research of flotation concentrates of monomineral fractions of chalcopyrite, sphalerite, galena, pyrite, pyrrhotite included methods of adsorption of collectors, surface compounds by IR ATR, and surface films of flotoreagents by TEM. They revealed that the proportion of the parts of thionocarbamate (TC) and dithiophosphate had an effect on the adsorption rate of the components of minerals, on the presence of characteristic bands, and, what is an important, visualized surface film of organic flotation reagents on the particles of concentrates by TEM. The predominance of thionocarbamate in a composition selectively increases the adsorption rate constant of the components and recovery of chalcopyrite compared with sphalerite and galena. The highest flotation rate using TC is characteristic for chalcopyrite (0.62 min- 1) in case of individual use, and it's in combination with butyl xanthate (25% butyl xanthate or 3:1) 0.89 min-1 too. We studied the ternary blend - dithiophosphate: thionocarbamates: butyl xanthate. The increase of the proportion of butyl xanthate in combination reduces the contrast of the flotation rate among all sulfides.Practice flotation of refractory sulfide copper-zinc ores of the Urals (content sulfide iron - 75- 95%) confirmed that the use of a combination of selective collectors increases selective recovery of copper sulfide minerals up to 50% at the first fraction that is the conditioned copper concentrate. New selective sulfhydryl collectors resulted in high levels of recovery of copper into a concentrate - more than 90% - against 70-72% (butyl xanthate) from copper-pyrite ore. Low floatability of iron sulfides has been obtained by selective sulfhydryl collectors. Using weak selective sulfhydryl collectors can reduce pH into collective or selective flotation from pH 10-10.5 to pH = 7.2-7.5, which improves the quality of individual concentrates of nonferrous metals and their recovery. The same is true for polymetalic sulfide ore. The volume of gold recovery also increased."

Jan 1, 2016

By The Mill Staff

Introduction The Hollinger cyanidation mill commenced operating in June, 1912, and 49,779,978 tons of solids had been discarded by the end of 1950. The present tailing disposal plant has been in operation since 1924 and holds 39,762,250 tons. The tailing disposal plant is on the property of Kayorum Gold Mines, Limited, about a mile and a quarter south of the mill. The area available for tailing covers 640 acres and is roughly l ¼ miles long by ¾ mile wide. Tailing was first deposited on the McKay veteran claims, l mile long by 1/2 mile wide, which were later included in the Kayorum property. This site sloped from northeast to southwest, the slope amounting to 106 feet between the northeast corner and the low land to the southwest. The low land was wet and a considerable area was covered with muskeg up to 17 feet deep. It was drained by a brook running across the property in a southwesterly direction. Later, when more ground was needed, the low-lying mining claims adjacent to the south and west boundaries were acquired to allow for the extension of the plant. This entailed some extra difficulties and expense that would not have been encountered had the whole of the present site been acquired with the original purchase. At the present time, the top of the tailing deposit stands at two elevations, but eventually the tailing deposited on the extension to the original plant will be raised to the same height as the older deposit. Previous to 1924, all of the tailing was deposited on Low land and in lakes near the mil1. Between 1924 and 1926 an increasing tonnage was sent to the McKay claims until, in 1926, all of it was being sent there. In 1936, the area of the deposit was extended and shortly afterwards all of the tailing was deposited on the new site.

Jan 1, 1951

By E. S. Malloch

THE Great War forced the peoples of the world to recognize the importance of the wise development and use of the world's natural resources. Not the least, and perhaps the most, important, is the world's fuel supply- solid, liquid, and gaseous. Without fuel our civilization would be impossible, and mankind would of necessity have to congregate in the torrid zones of the earth's surface for at least six months of every year. Of the three classes of fuels the solid ones are the most plentiful, as well as being the most widely distributed, since few countries are entirely devoid of solid fuels of one kind or another. Until a hundred years ago wood was the fuel most generally used in this country, but since then coal has supplanted wood as a fuel in all its uses, except in the outlying districts and among the farming communities. For many years the supply of coal was thought to be unlimited, but as years went by more thought and study were given to the world's coal resources, until today not only are the limits known, but in one instance at least their depletion is predicted to be almost within the age of living men, unless more provident methods are put into practice for their winning and utilization.

Jan 1, 1928

By E. B. Wilson

"Although the Operations Research technique of Reliability Theory has been applied with marked success in many fields, including the Apollo spaceship programs, the concept of reliability has not been generally adopted in mining and other heavy industries. Of course, reliability, or the probability that a system will be able to operate without a failure for a given interval of time, does not require the same emphasis in mining as in the aerospace industries. Nevertheless, certain aspects of Reliability Theory can be followed advantageously. For example, reliability calculations can determine the best time to overhaul and whether to retain stand-by units.The usefulness of the pseudo-operations research technique known as Replacement Theory is more readily re-cognized by the maintenance engineers in mining and other heavy industries. One of the least complex models enables the optimum Lifetime of an asset to be determined."

Jan 1, 1970

By A. W. Davis

Sapping and mining have constituted an important part of siege operations ever since powder came into general use in Europe. Before this period, famine was the main weapon in the hands of the besiegers, and the history of the middle ages is replete with accounts of sieges lasting two and three years. With the advent of explosives, a position impregnable to assault might be readily won by mining under, and blowing up, its defences. The natural offensive against this method of attack is to countermine and stop the attackers underground before their objective is reached. Thus developed the art of military mining. The French and British, in the Peninsular war, were adepts at this method of warfare, and the explosion of a mine and the formation of a breach were the usual preludes to the general assault of a position. In the Crimea, at Sebastopol, the British and Russians did a lot of underground fighting, as the old maps of their galleries, now in the museum at Chatham, will testify. In the siege of Port Arthur, in still later times, the Japanese and Russians were hard at it as well.

Jan 1, 1926

By J. Desroches, J. Burghardt, B. Lecampion, A. P. Bunger

"We present detailed comparisons between theoretical predictions and experiments for the initiation of radial hydraulic fractures transverse to a wellbore. Most of these experiments provide a measure of the time evolution of pressure, length, opening and flux entering the fracture during the test. We compare all these measurements simultaneously to our theoretical predictions, thoroughly testing hydraulic fracture initiation theory, which is shown to be predictive. These comparisons notably emphasize the difference between the initiation pressure (the wellbore pressure for which the fracture initiates) and the breakdown pressure (a misnomer which simply corresponds to the maximum pressure recorded during the test). INTRODUCTION In this paper, we will compare hydraulic fracturing laboratory experiments performed in different tight materials (PMMA, cement, shale) with the predictions from a numerical solution of the governing equations of hydraulic fracture mechanics (e.g. Geerstma & de Klerk, 1969; Detournay & Peirce, 2014). We focus on transverse radial hydraulic fractures initiating from a radial notch at the wellbore wall (see Figure 1). In particular, we will clarify the difference between the initiation pressure (the wellbore pressure at which the fracture initiates) and the breakdown pressure (a misnomer which simply corresponds to the maximum pressure recorded during a test, usually carried out at constant pump rate). This difference stems from the strong viscous effects at play during wellbore pressurization, fracture initiation and early propagation (i.e. fluid entrance in the newly created fracture). It has been observed on a number of experiments (e.g. Weijers, 1995; Zhao et al., 1996) and has a strong practical application, first because the maximum pressure is the most obvious value to report and second because that maximum value is necessary to specify injection systems."

Jan 1, 2015

By G. Stafford Whitby

N ATURAL gas is found in several provinces of Canada, particularly Ontario, New Brunswick, and Alberta. The largest producer is Alberta, and there the most important field is the Turner Valley, where some low-gravity crude oil and naphtha are associated with the gas. Last year there was produced from the Turner Valley field an average of 3,462 barrels, or about 450 tons, of oil a day. The gas flow from the wells in this field bears such a high ratio to the oil which comes from them that, despite the enforcement of a measure of conservation, it amounted to the vast quantity of 6,000 tons a day, or more than 2,000,000 tons a year. Prior to the application of any conservation measures, the gas flow was at one time of the order of 12,000 tons a day. The heat content of one ton of the gas is almost equal to that of two tons of coal. A certain amount, say, 10 per cent," of the gas is used in Calgary and surrounding towns and in re-pressuring the Bow Island gas field, but the greater part of it goes to waste. What are the possibilities of making use of this waste gas, in whole or part? The possibilities of using it profitably as fuel for domestic and industrial purposes have undoubtedly been carefully considered by the Company which now distributes a part of the gas to cities and towns in Alberta. But the relative sparness of the population and the cost of pipe lines makes such possibilities strictly limited. There are, however, distinct possibilities of making use of at !east a part of the gas for the production of a variety of chemical products and of liquid motor fuel. The present paper is devoted to outlining some of these possibilities. About three-quarters (by weight) of the Turner Valley waste gas consists of methane, the lightest and, chemically speaking, the simplest of hydrocarbon gases. The remaining quarter consists of heavier hydrocarbon gases-ethane, propane, and butane. Formerly, naphtha was separated from the well gas by a simple process of self-refrigeration. The gas coming from the wells at a pressure of, say, 1,200 to 1,800 lb., was passed through simple cylindrical vessels fitted with baffles and known as 'separators'. The pressure was allowed to drop to, say, 300 lb. in the separators, and the cooling effect secured by this expansion brought about separation of the naphtha. The naphtha thus obtained was 'wild', that is, it had a high vapour pressure owing to the presence in it of dissolved and liquefied gas. In order to reduce the vapour pressure to a level at which the naphtha could be shipped, this gas was removed either by distilling it out through a 'stabilizing' column or, according to the practice at many wells, merely by allowing the naphtha to 'weather' in open tanks (heated by coils if necessary) until the gas had been driven off in to the air.

Jan 1, 1936

By S. Esfahani, M. Barati, Y. Kauwachi

"Heat recovery from slag has gained attention due to its high potential in lowering energy intensity of metal extraction processes. A direct method to recover the thermal energy of slag is to use countercurrent air flow that extracts the heat from falling droplets. Often, the solidified slag is aimed to be used as a substitute for Portland cement, thus high cooling rates are required to form an amorphous slag with sufficiently strong hydaulicity. Rapid cooling however involves using large gas flow rates that in turn lower the thermal efficiency of the process. This article presents a mathematical model that was developed to determine the optimum conditions in the heat recovery process and to investigate the effect of the air flow and granule diameter on the cooling rate of the droplets as well as the thermal efficiency of the heat recovery system. INTRODUCTIONMetallurgical slags are the largest by-product of high temperature materials refining and extraction processes. The total amount of metallurgical slag produced in the year 2008 has been estimated at up to 422 million tonnes containing up to 222 TWh/y (Barati and Esfahani, 2011) of thermal energy. Over the past four decades attempts have been made to recover this substantial amount of energy as heat, electricity, or fuel, while none of the proposed method has been commercialized yet.During slow cooling the slag tends to crystallize the constituents (CaO, SiO2, Al2O3, etc.) into a hard, heavy solid. In the past, over 90% (Bengt, 1983) of the molten waste was discharged onto heaps and allowed to cool slowly, then crushed and used in road construction or land filling or as coarse aggregate for concrete. However, later it was found if cooled rapidly, the slag can be used as a substitute for Portland cement. As a result, processes such as wet granulation were created in which molten slag is fragmented with water, forming amorphous (glassy) phases. Despite its effectiveness in producing a suitable material, heat would not be recovered through this process. Thus, dry granulation was introduced in 1930’s and was developed further in 1970 – 1980’s."

Jan 1, 2012

By W. A. Padgham, H. Helmstaedt

Field evidence for current hypothe e about age and kinematic ignificance of gold-bearing hear zones in the Archean Yellowkni fe greenstone belt is reviewed , and it is concluded that major disagreements between previous workers are a direct result of differences in stratigraphic and tructural in terpretations of the Yellowknife Supergroup. Although goldbearing hear zone appear to be confined to the mafic volcanic pile of the Kam Group. it can be shown that shearing affected all supracru tal rocks, including the Jackson Lake Formation. now con idered to represent the youngest unit of the Yellowknife Supergroup. tructural ob ervations are incompatible with the hypothe is that the hear zones represent loci of ynvolcanic gravity sliding but are consistent with earlier conclu ions that shear zone development commenced with rotation of the volcanic pile and continued as re ult of lateral shortening broadly overlapping with the emplacement of granitoid batholiths. Shear Zones are common throughout the entire green tone belt. yet productive zone are confined to the Yellowknife Bay Formation of the Kam Group and localized where flow abut with a high angle again t the contact of the We tern Plutonic complex. However. no obvious tructural and lithological features have been recognized that are more favorable for gold deposition and distinguish the shear zones and flows of the area around the mines from those of other parts of the greenstone belt. The model that gold wa transported by metamorphic solutions and that hear zones were the firs t-order control for gold deposition provides no explanation for the trong localization of the depo it . As porphyries with elevated gold contents are present in and near ome of the mines. the possibility that gold was deposited from hydrothermal system around fel ic intrusion representing early phases of the Western Plutonic complex should be given erious consideration.

Jan 1, 1986

By Z. S. Shao, X. Z. Li

"Sub-critical crack growth plays an important role in long-term creep failure in brittle rock. Based on micromechanics established by using relationship between micromechanical wing crack growth model and macroscopic strain, and comparing theoretical model with testing results, a method, which applies the theory to real rock, is suggested in this paper. Using this method, properties of creep, damage and progressive failure in brittle rock are investigated. Effects of stress state on creep failure time and steady-state creep rate are analyzed and graphically presented. The results are helpful to support structure design and service life evaluation of underground structures with high geostatic stresses. INTRODUCTIONDuring the long-term operation in underground space with brittle surrounding rock, due to chemical action between pore water and rock, the failure of rock often occurs at stresses below its short-term failure strength, which brings serious effect on the long-term stability of underground structure. Thus, the long-term strength of brittle rock attracted wide interests of scholars around the world. The static fatigue limit was predicted by exponential function that is derived from abundant experiment data of stress level and failure time(Schmidtke & Lajtai, 1985), and similar result by relationship between stress state and failure time was also suggested (Lau & Chandler, 2004; Aubertin et al., 2000; Sangha & Dhir, 1972). According to relationship between steady creep rate and stress state during creep, a critical stress that transforms steady-state creep to accelerated creep was studied and the long-term strength was suggested (Tsai et al., 2008; Ma & Daemen, 2006; Lajtai et al., 1991). Based on the results of experiment in compression, the long-term strength of rock was defined by stress at volume strain reversal. When applied stresses are larger than the long-term strength, the microcracks in the rock will grow constantly, damage of rock will increase and failure of rock will occur finally (Chandler, 2013; Bieniawski, 1967; Brace et al., 1966)."

Jan 1, 2015

By Rob Boom, Yasuyuki Tozaki, Greg Traquair

The objectives of the business case are to examine a proposed metallurgical project and answer fundamental questions about project feasibility, risks, opportunities, and value. A business case fulfills these basic functions: estimates economic value; helps to understand competitiveness; serves as a risk management tool; and serves as a communication tool. A business case evolves with the project life cycle, and supports the gate reviews at the end of each phase of engineering, through to project construction and operations. A business case must be holistic, including all elements of scope that can impinge on project risk and value.

Jan 1, 2015

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 Alfred E. Pugsley

PAYMASTER CONSOLIDATED MINES, LIMITED, began an investigation into the economy and use of detachable bit drill-steel in June, 1937. This investigation has continued to the present time, and was made necessary by transportation and distribution difficulties that had arisen through the use of standard steel in three widely separated mine areas serviced by a central steel-sharpening shop. Detachable bit drill-steel performance was first studied in the workings of No. 2 mine, where the rock being drilled was composed mainly of porphyry or tourmaline, and where standard drill-steel transportation costs had been excessive. The results obtained in this early work definitely established the economy of detachable bit drill-steel at No. 2 mine. This conclusion was reached when the 're-grind' system of re-sharpening dulled detachable bits was 1n use. Preliminary observations on the performance of detachable bit drill-steel in the quartz-carbonate veins of No. S and No. 6 mines gave encouraging results, and warranted a large-scale investigation under practical mining conditions. All drilling operations were gradually changed over to use of detachable bit drill-steel. This change was completed by February, 1938.

Jan 1, 1939