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By J. E. Udd, S. Bharti

"ABSTRACTMonitoring of stability conditions in underground mines permits management to assess the response of the rock mass to mining strategies. Monitoring of movements, if sufficiently early, may also permit operators either to avert potential failures or to develop alternative approaches to extraction.The Falconbridge organization has been a leader both in the uses of rock mass stability monitoring techniques and in the development of instrumentation.In this paper, the authors review the Falconbridge approaches to monitoring, and present case history examples to illustrate the application of the various instruments used.RESUMELa surveillance des conditions de stabilité dans les mines souter-raines permet aux chefs d'enterprises d'évaluer les réactions de la masse rocheuse aux méthodes d'extraction minière. Si le contrôle des mouvements du terrain est effectué assez tot, l'exploitant pourra prendre les mesures qui s'imposent, soit pour éviter les détériorations possibles ou pour mettre au point de nouvelles méthodes d'extraction.Le groupe de la Falconbridge a ére le premier a utiliser des techniques de vérification des conditions de stabilité de la masse rocheuse et a mettre au point l'appareillage requis.Ce document présente une revue des méthodes employées par la Falconbridge pour assurer la surveillance active de la stabilité de la masse rocheuse et illustre au moyen de cas concrets la manière d'utiliser les divers appareils."

Jan 1, 1987

By A. Manohar Rao

Underground mining in general and more so the coal mining is a hazardous venture as it is a struggle against nature and natural forces. The stability of roadways has a direct impact on production and productivity. The roadway stability can be strongly influenced by the direction of the drivage. The stress studies are useful to provide a frame work for understanding the influence of drivage direction on roadway conditions, and to illustrate how mapping techniques can enhance this understanding. The act of mining can concentrate and re-orient the original stresses. Whenever coal is removed, the overburden weight that it carried is transferred. Vertical stresses are similarly affected when the roof is deformed or failed. The Singareni Collieries Company Ltd., a joint Public sector undertaking of the Government of Andhra Pradesh and India is conducting coalmining operations in the Godavari Valley Coalfield and is catering to the needs of a large part of South India. With the technology update, it is looking for safe mining and to achieve higher production. As a part of this, an attempt is made to understand the stress conditions prevailing on the mine blocks by different ways and means in terms of geology, structure and tectonics of the Godavari Valley coalfield, satellite imagery studies, cleat pattern, stress measurement studies conducted in different mine blocks, and stress mapping technique.

Aug 1, 2013

By Q. F. Wang, M. H. Lai, T. Q. Liu, G. G. Dong

Compared with the traditional pre-treatment process, biological oxidation process has many advantages including higher gold recovery, less cost, easier operation. The bio-oxidation reactor is the most important equipment for biological oxidation process. In this paper, the characteristics of biological oxidation are investigated, and the design principles are proposed based on laboratory tests. Both increasing the tank height and taking new inflation system can enhance higher dissolved oxygen. The new type of large-scale industrial bio-oxidation reactor is designed, which is 9.5 m in diameter and 10 m in height. The bio-oxidation reactor metallurgical performance has been tested by industrial-scale experiment. The slurry of flotation concentrate is divided into two parts to feed two bio-oxidation reactors. The feeding rates of two reactors are adjusted on the basis of getting the same content of S, Fe, As in overflow. The result shows that the feeding rate of the new type of 700 m3 bio-oxidation reactor is 3.72 m3 per hour, and the feed rate of the conventional 700 m3 bio-oxidation reactor was 3.23 m3 per hour. The processing capacity of the former is 15.2% higher than that of the later, which demonstrates the new type of bio-oxidation reactor has higher oxidation rate.

Jan 1, 2015

By Ajit K. Sinha

"Abstract - Electromagnetic surveys were conducted over the Yava sandstone-hosted lead deposit in Nova Scotia to evaluate the usefulness of such surveys for detecting and mapping sedimentary­ hosted metallic ore deposits. Both transient and multifrequency systems were used for that purpose. The deposit consists of three zones of disseminated galena which also contain minor amounts of pyrite and sphalerite filling the interstices of the sandstone grains. Each zone overlies a basement depression and is separated from the adjacent zone by an intervening basement high. A conductive shale layer underlies the galena-rich sandstone formation at all three zones.Because the concentration of galena (3% to 4% ) and other sulfides is too low to affect the resistivity of the sandstone formations for detection by ground electromagnetic (EM) methods, the strategy for our survey was to look for areas of basement depressions and the presence of conductive shale in those depressions by EM depth soundings. The presence of the galena-rich sandstone formations could be inferred because of the close association of these two features with the deposits in the Yava area. Both transient and multifrequency EM systems were successful in mapping the basement depressions and detecting conductive shale at the three known mineralized zones. The technique, therefore, seems to offer good prospects for mapping similar stratabound sedimentary-hosted sulfide deposits."

Jan 1, 1993

By R. Stauffer, S. Lindsay

"Sherritt Gordon Mines Limited utilizes pressure hydro-metallurgical techniques to recover nickel, copper and cobalt from su1phidic concentrates, mattes and various other metal-bearing materials.A brief description of the nickel refinery operation is given. In the nickel refinery process, an ammonia pressure leach is employed to treat the feed materials to dissolve the non-ferrous metals as their respective ammine complexes. The resulting leach solution goes through a series of steps which removes copper as copper sulphide and further purifies the solution prior to nickel precipitation by hydrogen reduction. The reduction end solution, containing the cobalt which was originally present in the leach solution as well as residual nickel, is treated with hydrogen sulphide. The resulting nickel-cobalt sulphide precipitate feeds the soluble cobaltic ammine process, which separates the nickel and cobalt and recovers the cobalt as a pure powder.A detailed description of the cobalt recovery process is given. Included are the various steps, comprising: acid leaching of the mixed sulphides, solution purification, ammine complex formation and cobaltous oxidation, two-stage nickel precipitation, cobalt conversion and reduction. A brief description of cobalt powder handling is included, along with typical physical properties and chemical analyses of the cobalt product. In general, the purpose of this paper is to describe the present plant practices employed in the recovery of cobalt as a by-product of the nickel refinery operations."

Jan 1, 1967

By K. Szczesny

This paper considers the integration of uncertain real-time logistics data for reactive construction scheduling. In order to manage a construction project efficiently, an accurate schedule representing the current project progress is inevitable. The quality and up-to-dateness of such a schedule depends on the availability of real-time data. Typically, real-time logistics data contain information about the availability of material, equipment and personnel as well as delivery dates and site conditions. The accuracy and inherent uncertainty depends on the location where the real-time data was acquired. Currently, the integration of such data into a construction schedule is a very time-consuming, manual and, thus, errorprone process. Therefore, this paper proposes a methodology that enables an automatic integration of such uncertain data into construction schedules. By integrating uncertainties into the existing schedule their impacts on the construction work can be evaluated. For this, discrete event simulation is applied. In order to model uncertain input parameters for simulation models this methodology applies the fuzzy sets theory. In combination with alpha-cut sampling technique, discrete model input parameters are obtained. By applying reactive scheduling with several discrete event simulation experiments, the results can be used to modify construction schedules according to agreed timeframes and costs. In order to demonstrate and validate the presented approach an example is conducted.

Aug 1, 2013

By T. H. Etsell, P. Kerr

Over the past 50 years, there have been a number of geological, mineralogical and metallurgical studies carried out on the Clear Hills ironstone deposits in northern Alberta, Canada. Due to the low grade and complex mineralogy, previous metallurgical studies have achieved limited success. After rejecting some of the more ‘conventional’ techniques for iron ore beneficiation, the authors chose to investigate the grain enlargement/iron segregation process for the beneficiation of the Clear Hills ironstone. The segregation reactions for iron have not been explored in as much detail as they have for copper and nickel. Iron segregation roasting involves the addition of a carbonaceous reductant and a chloride transport agent to an iron oxide ore, and heating the mixture to an appropriate temperature. The benefit of this process is that it allows ores in which the value minerals are intimately associated with gangue minerals to be processed in circumstances where conventional iron ore processing techniques are not suitable or capable of upgrading the material. As iron is one of the few elements that can be transported through this process, a clean high purity metallic concentrate can be achieved.Through the use of crucible testing followed by Davis tube magnetic separation, scanning electron microscopy, X-ray diffraction and atomic absorption spectroscopy analysis, characterization of the reaction products has been made with an improved understanding of the reaction mechanism.

Jan 1, 2015

By J. U. MacEwan

Introduction The equilibrium between copper, zinc, and chlorine may be considered as the simultaneous equilibrium of the two separate chemical reactions of formation of the stable chlorides of copper and zinc at the temperature of the reaction i.e., l440°K. (1,167°C., 2,133°?F.)§ [Zn(g) +Ciz(g) ZnCl2z(g). ... (1) ] [2Cu(l)+Cbi'g) Cu2Cl2(l 1 ....... (21 ] Subtracting, [Zn(g) +Cu2(Clz(l i ZnClz(g) +2Cu!l) ... . (3) ] If this reaction is carried out with a copper-zinc alloy at some constant temperature above the melting point of brass, and at a total pressure of one atmosphere, the equilibrium concentrations obtained will depend on the free energy decrease .of the reaction as written in (3) and on the activities of the various components in. the reaction mixture. If the equilibrium is examined from the point of view of the phase rule, it is a three-component system, and if it exists in two phases (liquid and gas) it will have three degrees of freedom. If the restrictions of constant temperature and pressure are imposed, the degrees of freedom are reduced to one. This means that, in a two-phase system under these conditions, each different alloy phase will be associated with a gas phase of constant composition.

Jan 1, 1951

By J. Cayouette, . Blatter, P. Cousin

The Laronde mill was commissioned in 1988 and has been treating the Laronde Perim ore since 2000. The Laronde plant, situated in the Abitibi region of Quebec, has experienced mill expansions to accommodate 7500 mtpd and to recover gold and silver as well as important amounts of base metals (Cu, Zn, Pb). Ten sequential metallurgical and environmental processes are responsible for metals recovery and process viability. Over 200,000 ounces of gold, 4,5 million ounces of silver, 7000 tonnes of copper, and 78,000 tonnes of zinc are produced annually. In 2008, the Goldex plant began trucking high wade (35-45 Wt Au) pyrite sulphide concentrate (TCGO) for gold extraction at a newly constructed treatment plant, increasing gold output at Laronde by 40,000 ounces. In 2009, the high gold wade Lapa ore processing facilities were annexed to the Laronde plant increasing output by 120,000 ounces of gold. TCGO and Lapa productions are forecasted until 2018 and 2015 respectively, with known reserves of each mine. Today, up to 140 permanent employees run and optimise the Laronde plant operation. As a result, Laronde has intricacies intrinsic to a large and varied operation. The paper will outline the metallurgical highlights, challenges, and future outlook related to the treatment of each ore type (Laronde, TCGO, and Lapa)

Jan 1, 2011

Arsenic bearing minerals such as enargite (Cu3AsS4) and tennantite (Cu12As4S13), which may associate with major copper minerals such as chalcopyrite (CuFeS2), chalcocite (Cu2S) and bomite (Cu2FeS4), usually report to the copper concentrate in conventional flotation due to their similar flotation properties. Arsenic in a copper concentrate causes environmental problems and also problems in the subsequent pyrometallurgical process. Voltammetric studies were carried out to investigate the oxidation characteristics of enargite, tennantite, chalcopyrite, chalcocite and bomite. Contact angle measurements and micro-flotation tests were conducted to examine the flotation characteristics of enargite and chalcopyrite under controlled pulp potentials. Selective flotation of enargite from chalcopyrite under varied pulp potentials was conducted to investigate the feasibility of arsenic removal from a copper concentrate. The test results indicate that the non-arsenic bearing copper minerals ( chalcopyrite, chalcocite and bornite) were easier to oxidise than arsenic bearing minerals ( enargite and tennantite) in an alkaline solution. Enargite floated well at a potential as high as +0.45 V vs. SCE while chalcopyrite was completely depressed at a potential higher than +0.43 V vs. SCE. Selective flotation revealed that enargite can be successfully removed from chalcopyrite through controlling the pulp potential at +0.30 ~ +0.50 V vs. SCE.

Jan 1, 2007

A direct comparison has been undertaken between laboratory wind tunnel experimentation and computational fluid dynamics simulation of a 3D manufactured analogue for a body of fractured broken rock, created with CAD/CAM techniques. Detailed descriptions of the ?design? of the analogue (using a discrete element analysis multi-body simulator), its manufacture (using computer aided design and 3D printing technology) and the laboratory experimentation (inserting the physical analogue into a laboratory scale wind tunnel) are presented. The agreement of the results of direct experimental observations on the manufactured analogue with the values from CFD simulations of those experiments justifies the utilization of a CFD environment for the practical investigation of geometric factors controlling air flow and heat exchange in complex assemblages of broken rock blocks. The ultimate goal is described, that of developing functional relations between bulk properties of such assemblages (such as their porosity and bulk density) and the low-level geometric factors that dictate the air flow behaviour, such as the equivalent perimeter length of the cross-sectional area available for flow, or average flow path tortuosity. A practical application area of the work in the mining context is also described; equivalent continuum air flow and heat transfer constitutive models developed on the CFD tool from such functional relations are useful in characterization of seasonal heat storage in large scale bodies (approximately 1 km3) of broken rock.

Aug 1, 2013

By K. Heid

"Although concentrated efforts have been made to deplete PCB transformers from the Canadian environment, numerous transformers (as well as ballasts, capacitors and magnets) continue to exist throughout the Canadian mining industry. The existing installed base is slowly being phased out as environmental issues come under increasingly high profile. The following article identifies the potential problems of owning PCB transformers and offers some solutions for their removal, disposal and replacement. IntroductionPolychlorinated Biphenyls (PCB) are synthetic chemical compounds consisting of chlorine, carbon and hydrogen. PCB was widely used in transformers due to its physical properties, including stability, low flammability and non-conductivity. Use of PCB in electrical equipment has been banned since 1977 when the extent of environmental contamination was discovered.Although PCB’s have been outlawed for use in electrical equipment since the late 1970s, safe storage regulations were not addressed until 1988 when a major spill prompted the federal government eventually to issue the storage of PCB Material Regulations in 1992. These regulations replaced the Interim order of 1988 under the Canadian Environmental Protection Act.PCB transformers are usually referred to as askarel filled transformers or as PCB contaminated mineral oil transformers. Askeral transformers were designed to contain high concentration PCB fluids, referred to as askarel. Mineral oil transformers were not designed to have PCB concentrations but were inadvertently contaminated during manufacture or maintenance activities."

Jan 1, 1998

By D. J. MacDonald

UNDERGROUND development at the Lynn Lake property of Sherritt Gordon Mines, Limited, was begun in 1948 with the sinking of the A shaft in the area of the A orebody. By June, 1949, the shaft was completed to a depth of 1,024 feet. Twelve stations were cut, with the bottom level at 992 feet below the collar. Since completion of the shaft, lateral work has been carried out on the 12th level in order to expose the known orebodies and to provide openings from which deeper exploration could be conducted. Dur¬ing the change-over from sinking to lateral work, preliminary diamond drilling was done from the 12th level station to locate the A? ore-body. Later, drilling was carried out from the 5th and 9th level sta-tions, where, also, the outline of the A orebody was established. As the work progressed on the 12th level, and with the commence-ment of drilling below that level, the geological picture was found to be complicated by numerous faults. Instead of operating two drills it became necessary to use at least four. The original plans had provided air sufficient to drive two headings and to operate two diamond drills. The addition of two more air-driven drills resulted in a serious shortage of power.

Jan 1, 1951

By Bertrand Quiniou, Pierre Amadieu

Ion exchange technologies and processes are proven and established technologies widely used in numerous industries including hydrometallurgy for metal separation and recovery from metal bearing solutions. They have evolved through innovation which includes the development of countercurrent multistage (or multivessel) ion-exchange contactor systems with the benefit, for industrial operations, of greatly reduced footprints and ion-exchange media inventories, as compared to more traditional fixed bed contactor systems. Information on procedures for design and sizing of countercurrent multistage ion-exchange contactor systems is not readily available since it is most often proprietary know-how. The purpose of the present work is to develop a simple and innovative approach for the sizing and modeling of industrial countercurrent multistage ion-exchange contactor systems. The suggested approach builds upon published results and upon the following observation: in an industrial setting, knowledge of how component concentration or load on a contactor output streams vary with time t within a cycle duration (0 < t < T) is generally of little interest, only knowledge of time average of such concentration or load over a cycle duration T is sought for. The presented approach will be tested against current or past performances of industrial countercurrent multistage contactors of Orano Mining operations such as SNK‑3M moving packed bed contactors in Kazakhstan and NIMCIX fluidized bed contactors in Namibia.

Jan 1, 2020

By V. K. Karra

A mathematical model for the performance of a vibrating screen is developed in terms of an oversize partition curve. This is a normalized curve for any assemblage of particles presented for screening when their size is normalized with respect to the 50 per cent passing size (d50 ) under the prevailing screening conditions. Based on the throughfall aperture (hT) of the wire mesh on the deck, the effects of oversize (% >hT), half-size under (% <0.5 hT), deck location and feed rate were evaluated using the existing screen sizing information. All these variables and also the near-mesh (1.25 hTx 0.75 hT) content (%) of the feed affect the d50. Performance data from different decks of a double-deck screen with various feed rates, size distributions and screen apertures were used to evaluate the near-mesh factor. Effects of wet screening and material bulk density are also incorporated in the model. This generalized model is useful for the simulation of a multiple-deck screen. It furnishes the sieve analysis information of all the deck output streams and therefore has a potential use in the over-all circuit evaluation when used in conjunction with relevant crushing and grinding performance models. An example illustrating the prediction capabilities of the model is given.

Jan 1, 1979

By A. M. Elmahdy, T. Hirajima, M. Farahat

"Separation of molybdenite from chalcopyrite is mainly achieved through flotation technique to raise their grades up to 25% to be extracted in smelters. However, molybdenite recovery and grade obtained from this process is not satisfactory in most cases due to the natural hydrophobicity of both minerals. The influence of conventional heat treatment on pure chalcopyrite and molybdenite minerals was investigated. X-ray diffraction, TG-DTA and XPS techniques were applied before and after heat treatment. The results showed phase changes for both minerals. Magnetic separation experiments of single and mixture of both minerals at several magnetic intensities were made. For single mineral experiments, 100% molybdenite recovery was obtained at all experimental conditions as non-magnetic fraction whereas ca. 100% chalcopyrite recovery was achieved under certain conditions. In case of 1:1 binary mixture, 87% and 83% molybdenum and copper recoveries, respectively, were obtained. The increase in chalcopyrite magnetic recovery is related to the formation of more magnetic phases as confirmed by characterization techniques.The objective of this study is to increase the magnetism of chalcopyrite to make its separation from molybdenite by magnetic separation possible and to understand the mechanism behind it. These results indicate that it may be possible to upgrade molybdenite ores using heat treatment followed by magnetic separation to the required grade by smelters which is difficult to attain by froth flotation and the other techniques."

Jan 1, 2016

By A. C. Stevenson

"The most common theory is that, since thyristors, diodes, and insulated gate bipolar transistors (IGBTs) are “solid state” they will live forever. This is not so. They have wear-out mechanisms (e.g. insulation) and other mechanical parts such as motor bearings. These wear-out phenomena can be easily calculated. In this paper we will look at some of the failures and the failure rate of thyristors in power converters to see what affects them and to see what improvements can be made. If converter failures do occur, some simple forensic engineering steps will show if this is the root cause of the problem.IntroductionLook at the general failure rate curve for thyristors, diodes, gate turn off devices (GTOs) and IGBTs shown in Figure 1. We see that there is an initial high failure rate due to manufacturing defects, application problems, and drive start-up stresses that lasts for a few weeks. This is followed by a long period of (hopefully) several years with a relatively low but very slowly rising failure rate. At the end of this period, the devices start to wear out and the failure rate suddenly starts to increase rapidly over a few months. This signals the end of life for the devices in the system. We will start by looking at this end of life area."

Jan 1, 2000

By F. Awotwe-Appiah, P. Koshy, A. Y. Fosu, J. Dankwah, J. R. Dankwah

Ghana currently exports its bauxite raw without any value addition. Gradual depletion of high grade bauxite (with high alumina content) and the emergence of low grade bauxite (with high iron oxide content) calls for novel and inexpensive ways to recover alumina from these low grade ores. Bauxite users have indicated their willingness to pay 10% to 50% higher for a corresponding reduction in impurities by a similar amount. This project therefore investigates the carbothermal upgrading of the Ghana Awaso bauxite using waste polypropylene as reductant in a locally designed gas-fired furnace. Composite pellets of low grade bauxite sample (assaying 45% Al2O3) containing pulverised waste polypropylene were formed, oven dried, placed in fireclay crucible and fired for 30 minutes. The magnetic fraction after reduction was separated by a Low Intensity Magnet and weighed. It was observed that up to 97% of the iron oxides (occurring as hematite and goethite) could be separated into the magnetic fraction as magnetite leaving a nonmagnetic fraction with over 98% Al2O3 as opposed to the 45% Al2O3 in the as-received bauxite sample. This research direction provides yet another simple but effective way for simultaneously upgrading low grade bauxite and recycling waste polypropylene, whilst at the same time decreasing the amount of waste material generated as red mud after the Bayer process.

Jan 1, 2015

By R. W. Watson, H. D. Peer

"This paper outlines the history of steel linings in the Autogenous Mills, the factors influencing the decision to convert to rubber lining, and the operating and cost experience with the rubber liners to date. INTRODUCTIONSherman Mine is an open pit iron ore mining, concentrating and pelletizing operation located at Temagami, Ontario. The operation employs 392 hourly employees and 81 salaried employees and has an annual capacity of over one million L.T. of high quality iron ore pellets produced from low-grade magnetite ore.The Sherman Mine is a joint venture; 90% owned by Dominion Foundries and Steel Limited (Dofasco) of Hamilton, Ontario, and 10% owned by the Tetapaga Mining Company, a wholly-owned subsidiary of the Cleveland Cliffs Iron Company of Cleveland, Ohio. The operation and management of the mine is by Cliffs of Canada, Limited. Development of the property was started in 1965, with pellet plant production beginning on March 17, 1968. At the present time, the orebodies contain sufficient reserves to sustain operations at current production levels for 30 years. Mining was originally carried out in three orebodies, the North, South, and West pits. The North Pit has been exhausted and mining operations ceased in the spring of 1980. A fourth pit, the East Pit, will be developed during the early 1980's."

Jan 1, 1981

By Bruce Mennie

PT Freeport Indonesia (PTFI) operates copper and gold mining operations in a mountainous area of the Mimika regency, near Tembagapura, Papua (formerly, Irian Jaya), Indonesia. The mining and concentrating operations typically produce 240,000 metric tonnes per day of Copper and Gold ore from the combined mining of an 80,000 tonne per day (ore) block cave operation (DOZ Mine) and a 160,000 tonne per day (ore) open pit mining operation (Grasberg Open Pit). The Grasberg Open pit mine will be complete in 2016 at which time PTFI?s operations will convert to Underground. Mining operations will transition from today?s mixed surface and underground operation to full underground mining over the next 6 years. This paper reviews the history of Redpath?s relationship with PTFI, beginning with a raiseboring contract in 1981 and evolving into vertical and horizontal development contracts of up to 37,700 equivalent metres of lateral development and 4,000 metres of vertical development in 2011. An overview of the current operations (PTFI?s Grasberg Open Pit and DOZ Underground Mines) and transition period (challenges for the transition from current to future underground mines) is presented with details of development of common underground infrastructure and future mines; Big Gossan Mine, DMLZ Mine, Grasberg Block Cave Mine, and the Kucing Liar Mine.

Oct 1, 2010