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By Malcolm Scoble

Process Technologies Suitable for Application Underground Design Criteria - coarse particle technologies - compact, robust, flexible - waste products suitable for use as backfill Process technologies identified: - Optical/conductivity sorting - Dense media separation - Coarse-particle flotation Process technologies supported by compact & efficient comminution stages Mineralogical evaluation to select process & estimate Performance Further Work U/G Plant Layout & Excavation Modelling Evaluate scenario at increasing depth Establish properties of waste as backfill Model impact of improved backfill quality Evaluate further case studies Evaluate further Environmental Health and Safety Issues Model impact of system development on inventory of national mineral reserves Conclusions Technologies exist for integrated underground mining and processing systems These technologies to be successfully integrated into underground mining system Positive economic and environmental benefits Technical issues to be resolved at depth System Development path identified

May 1, 2004

By A. I. A. Salama, M. W. Mikhail

"The existing methods of block diagram manipulation and vanishing variable for flowsheet simplification used in coal and mineral processing circuit evaluation and optimization cannot be easily implemented on digital computer.The signal flowgraph technique is proposed to represent and simplify determination of the relationship between intermediate or end variable and the feed in the flowsheet. Typical and existing circuits are used to demonstrate the application of the proposed technique which can easily be implemented on digital computers.IntroductionRecently there has been much interest in the analysis and optimization of coal and mineral processing circuits to assist in the pre diction of coal and mineral processing plant performance. The block diagram and the vanishing variable were introduced and utilized in the analysis of plant flowsheet. Although the block diagram approach is useful, it requires manual manipulation of the circuit block diagram which may present difficulties in the situation of complex circuits. Moreover, it may not be easy to implement on a digital computer.In this paper, the signal flowgraph technique is proposed to represent the circuit flowsheet and to simplify the determination of relationships between intermediate or end variables (fractional mass) and the feed for any coal and for any mineral processing circuit comprising size and density separators. These relationships are utilized in the analysis and/or optimization of the circuit. The proposed technique is illustrated by considering typical and existing circuits."

Jan 1, 1987

By David E. Pearson

"Western Canadian coking coals are located in the Rocky Mountains arid foothills of British Columbia and Alberta. They are typical of non-marine coals, characterized by total sulphur contents of less than one per cent and with ash contents of 10-30 weight per cent. This mineral matter is composed principally of kaolinite and quartz.The petrographic compositions of most of the coking coals which constitute the 2.065 billion tonnes of British Columbia's measured reserves, and the compositions of the metallurgical coal currently exported from Alberta, show them to be rich in the inertinite macerals, macrinite, fusinite and semifusinite. When the mean maximum reflectance of vitrinite in oil/Romax) is used as the coal rank parameter, this high inertinite content is reflected in the lower volatile-matter yields, but the relatively inert character is also displayed by lower free swelling indices (PSI), lower maximum dilatations, lower maximum fluidities and lower coke strengths than other coals of the same rank, but richer in the reactive macerals, vitrinite, exinite and semifusinite. Despite these reduced values in the so-called caking tests, inertinite-rich coals produce strong coke.A system of classification of coking coals is introduced which is based on rank, as indicated by Ro max, and either petrographic composition, maximum dilatation, maximum fluidity or, to a lesser extent, PSI and volatile-matter yield. Six principal coal groups can be distinguished among coking coals using this versatile classification. Inertinite-rich coals are assigned to the Keystone Group (GI), Balmer Group (G3) or Moura Group (G4), each group being named for a coal typical of that population ofcoals. Reactive-rich coals are assigned to the Pittston Group (G2), Kellerman Group (G5) or Big Ben Group (G6). A multiple-regression analysis of coal quality versus price shows how the value of coking coal in the Japanese market appears to be related to reflectance and the free swelling index, and confirms the economic viability of the classification.British Columbia's measured reserves of coking coal contain representatives of four of these groups; Balmer Group (73%), Moura Group (/6%), Pittston Group (3.4%) and Kellerman Group (7.6%).This analysis of the quality of Western Canadian coking coal indicates that despite the need for large proportions of inertinite-rich coking coal in blends produced in the Japanese steel industry, there is nevertheless a demonstrated overabundance of Balmer Group and Moura Group coals available to the international coking coal market."

Jan 1, 1980

By J. C. O'Rourke

"Gibraltar Mines Ltd. has been operating its open pit copper mine for fifteen years. In that time, over 140 million tons of waste and low-grade material has been placed on the mine waste dumps. Laboratory and in situ testing indicated that enough leachable copper was recoverable from the dumps to justify a leaching operation which would include the construction of a solvent extraction-electro winning plant. The plant, which was commissioned in October 1986, was designed to process 3000 USGPM of dilute copper solution to produce 5000 tons per year of high-quality cathode copper.This paper deals with the start-up and initial year of operation of this plant. The three areas: leaching, solvent extraction, and electrowinning are presented with emphasis on the innovations which were made to help overcome the problems unique to the Gibraltar operation.The Leaching CircuitThe mine waste dumps are leached to produce a pregnant copper solution as feed to the SX-EW plant. To achieve this the dumps are sprinkled with a mildly acidic solution which percolates through the dumps. In travelling through the dumps the solution contacts the surfaces of the liberated copper minerals and dissolves the soluble copper into the form of copper sulphate. The leaching reaction is achieved by a combination of bacterial action to oxidize the sulphides and solubilization of the copper into the acid solution.For the bacterial action to occur the dumps must be near the ideal pH of 1.9 to 2.1 and the necessary elements of the reaction must be present. Because a bacterial reaction is involved there is a lag time between the time when the conditions for bacterial growth are achieved and when the bacteria are in their active growth phase. Laboratory leaching tests with Gibraltar ore indicated that bacterial action takes two to three months to reach its maximum rate (Fig. I).The expected lag time for the planned rate of bacterial leaching prompted Gibraltar to start irrigating the dumps in late June 1986 for a plant start in early fall. The lag time proved to be longer than expected and the dumps took until November to start producing copper at the expected rate (Fig. 2)."

Jan 1, 1988

By Bruce W. Downing, Philip G. Claridge

"The availability of environmental data is a major concern in the development of an exploration project through the permitting and feasibility stages. The collection of these data should ideally start very early in a major exploration program. Although a large proportion of the environmental data can also be used for exploration purposes, (e.g. stream-sediment, soil, and rock analyses), environmental sampling will rarely have been initiated at an early date. For the Windy Craggy project, a major environmental concern is the potential for generation of acid rock drainage from waste-rock piles. The project is reviewed with respect to the environment of the deposit, deposit geology, mineralization and reserves, the sequence of exploration activities to the present, the potential for the development of acid rock drainage, the geochemistry and water quality, and the integration of exploration and environmental databases and their application to environmental planning. IntroductionIn the classical sense of exploration of a mineral deposit, the efforts throughout exploration are routinely directed at confirming the existence of the deposit and defining its extent, grade and continuity. Environmental issues are usually tackled separately, possibly by different personnel at a later date. When that is the case, an opportunity is lost to build, from an early date , a comprehensive database that (I) will satisfy the needs of conventional exploration and environmental monitoring, and (2) is usable as a predictive tool for environmental impact assessment.The concept of environmental geochemistry is not complex. The availability of environmental data is a major concern in the development of an exploration project to the feasibility and permitting stages. The collection of data should ideally start very early in any major exploration program. In many cases a significant proportion of the geochemical exploration data gathered early in the life of a project will also be used later for environmental purposes (e.g. stream-sediment, water, soil, and rock analyses). Rarely, however, will the data gathered in a geochemical exploration program provide information as complete as that attainable if environmental objectives had been considered in scoping the work.A knowledge both of local and regional geochemical processes can lead to a better understanding of environmental impacts. This understanding is the basis upon which good environmental management practices may be built. Geddes Resources Limited has undertaken a major study of the natural environment in the Windy Craggy area which includes geology, surface and underground waters, soils, stream sediments, glaciers and geomorphology (Geddes Resources Limited, 1990). This paper deals with the building and integration of the exploration and environmental databases."

Jan 1, 1993

By M. Silver, R. H. McCorkell

The effects of covering materials on radon emanations from uranium mine mill tailings were investigated. Granular materials with air in the spaces allow radon to pass freely. Moist covers of compost or soil decrease radon emanation from tailings. Water-saturated covers were more effective, and freezing the tailings with these covers further decreased radon escape. Water itself is a poor radon barrier probably due to circulation. Plants had no effect on radon emanation through soil. Although radon diffusion through water-saturated powders appears to be very slow and inefficient, about 25% of the radon escaping from the grains in water-saturated tailings diffuse to the surface and emanate when no cover is present. The radon escaping from tailings through covers of water-saturated compost or soil is no more than could be accounted for by radon produced in the covers themselves.

Jan 1, 1987

By William F. Caley, A. MacKinnon, P. W. Kingston

"The purpose of this paper is to identify a number of currently available opportunities for exploration and/or mine development in the industrial minerals field in southeastern Ontario. The paper is not intended as a complete review of the industrial minerals industry in southeastern Ontario, but highlights what are seen by the authors as areas where there are immediate opportunities for investment and growth.Traditional exploration targets in the Grenville Supergroup in southeastern Ontario have been vein-hosted gold deposits, industrial minerals, and base metals. In recent years, emphasis has increasingly shifted to industrial minerals, in response to changing technologies in the minerals-consuming manufacturing industries, and to an increasing awareness of the industrial mineral potential in this area.This paper examines the resurgence of interest in exploring for and developing a wide variety of industrial minerals, and it examines the work the Ontario Ministry of Northern Development and Mines has done under the current Canada-Ontario Mineral Development Agreement. Specific development opportunities are identified in various commodity areas. Use oj the industrial minerals wollastonite and nepheline as substitutes for fluorspar in the formulation of synthetic steelmaking slags is also discussed."

Jan 1, 1990

By H. Scott Swinden

"ForewordA symposium on base metal deposits was held in Bathurst, New Brunswick, from June 10-13, 1990, sponsored jointly by the Geological Surveys Branch of the New Brunswick Department of Natural Resources and Energy, the New Brunswick Prospectors and Developers Association, and the Geology Division of the Canadian Institute of Mining, Metallurgy and Petroleum . Papers prepared for the symposuim are being published as a series of articles in the CIM Bulletin. This second paper (the first was by Fyffe, et al., in Vol. 83, No. 938) in the series presents an overview of the paleotectonic settings of massive sulphide deposits in the Dunnage Zone of Newfoundland with emphasis on volcanic geochemistry.ABSTRACTCambrian and Ordovician volcanic sequences of central Newfoundland, which record the history of the Iapetus Ocean, are prolific hosts to volcanogenic massive sulphide (VMS) deposits. Geochemical, isotopic and geochronological studies show that the vestiges of Iapetus in Newfoundland probably record a complex series of island arcs and back-arc basins that were marginal to, rather than part of, the main ocean basin of Iapetus. The geochemical and isotopic data provide a means of characterizing the tectonic environment of individual volcanic sequences, and allow us to identify a number of distinct tectonic environments in which VMS depositiontook place.Four tectonic environments have been identified as being associated with VMS deposition: (I) back-arc environments hosting VMS deposits include both N-MORB-type ophiolites (e.g. Skidder?) and volcanic sequences with oceanic island (or within plate) tholeiite characteristics (e.g. Great Burnt Lake); (2) primitive arc environments include both supra-subduction zone (SSZ) ophiolites (e.g. Betts Cove, Rambler) and volcanic/epiclastic sequences (e.g. Point Leamington, Duck Pond) and are characterized by abundant arc tholeiites, with lesser refractory lavas and rhyolites; (3) mature arc environments comprise dominantly thick felsic and mafic volcanic piles in the Buchans - Robert's Arm Belt (including the Buchans camp) and are characterized by dominantly calc alkalic basalt and andesite; and (4) continental rift environments occur in the Hermitage Flexure area (e.g. Strickland deposit) and are characterized by dominantly felsic volcanic sequences.Island arc environments are by far the most prolific hosts to VMS deposits. Patterns of VMS distribution in central Newfoundland show that similar tectonic settings may be recorded by very different stratigraphic sequences (e.g. both ophiolites and thick volcanic/ epiclastic sequences may record primitive arc rifting) and emphasize the importance of the rifting in VMS generation, irrespective of the details of the tectonic or stratigraphic setting. The ability to judge the prospectiveness of a volcanic sequence by using whole rock geochemistry to evaluate its tectonic environment may prove useful in area selection at the grassroots exploration level."

Jan 1, 1991

By L. J. Bryson, C. A. Biley

"Anglo American Platinum’s Rustenburg Base Metals Refiners (RBMR) produces Ni and Cu cathode from slow cooled converter matte after Platinum Group Metals (PGMs) are magnetically separated for further processing. In 2010, execution of the RBMR expansion project was commenced to increase the production capacity to 33 ktpa Ni. The expansion, which is currently still in a ramp-up stage, brought about several fundamental changes to the circuit chemistry, including the installation of a dedicated Pressure Iron Removal (PIR) autoclave. This provided an independent outlet for iron from the refinery, which previously deported to the residue from the leach circuit and was toll refined. At the same time as changes in the circuit associated with the RBMR expansion were being made, the plant experienced a significant increase in iron and copper units per nickel unit in the feed. The decoupling of the leaching and iron removal process steps has had significant advantages for the robustness and control of the overall circuit, in particular pertaining to the preparation of a nickel electrolyte of sufficient purity to produce LME grade nickel. This paper details the primary changes to the RBMR circuit chemistry with a particular focus on iron deportment and the benefits derived from the installation of the PIR autoclave.INTRODUCTIONAnglo American Platinum mines and refines Platinum Group Metals (PGMs) through a complex processing pipeline in its South African operations. Mined ore is first treated through several mineral processing stages, geared to the recovery of base metals and associated PGMs, followed by smelting and refining operations that aim to separate base metals from PGMs and recover the value components to purified, saleable products. The focus of this paper is the Rustenburg Base Metals Refiners (RBMR) complex which receives a PGM-containing converter matte, then physically separates PGMs and base metals, and recovers nickel and copper to cathode by utilising leaching, precipitation and electrowinning processes.With new mining operations coming online and the continued increase in PGM ore arisings, it was necessary to undertake an expansion project at the Base Metal Refinery (BMR) to increase production capacity from 21 ktpa to 33 ktpa Ni. Complicating the expansion project was the requirement of continued production through all stages of design, construction and implementation and, due to stringent capital constraints, the utilisation of all existing equipment installed during a previous expansion in 1981. Against this backdrop, the expanded BMR flow sheet involved significant changes to the chemistry, especially iron management. These changes in iron management allowed for the separation of iron and copper residues and significantly increased the robustness of the plant to changes in feed mineralogy as well as the potential to increase production duties of the existing equipment."

Jan 1, 2016

By Robert B. Parsons

"The Department of Finance introduced draft amendments to the resource allowance regulations on July 23, 1992 that effectively nullify the decision in the Gulf Canada Limited case. Prior to the amendments it appeared that only ""directly"" related general and administrative, capital cost allowance and scientific research expenditures had to be deducted from resource profits. Now ancillary expenditures are required to be deducted. Consequently, the ability of taxpayers to claim the resource allowance is curtailed.IntroductionOn October 25, 1990 it was almost certain that taxable mines were going to get a break. The Federal Court-Trial Division had just decided in Gulf Canada Limited's favour to allow it to claim resource related tax benefits larger than what Revenue Canada evidently wished. Revenue Canada appealed first to the Federal Court of Appeal and then to the Supreme Court of Canada. On January 10, 1992 the Federal Court of Appeal agreed with the Federal Court decision and on July 2, 1992the Supreme Court declined to hear any further appeal. A mere three weeks later, on July 23, 1992, the Department of Finance issued draft ""clarifying"" measures to amend the calculation of the resource allowance. These measures effectively nullify the benefits that arose under the decisions of the Federal Court."

Jan 1, 1992

By T. Yalcin

"This paper describes a study carried out to determine the behaviour of Cu-Ni mill tailings during natural and flocculated sedimentations. Settling rates were examined under various conditions through standard laboratory batch settling tests. Flocculation was found to improve the sedimentation process significantly, but its effectiveness depended on several factors such as the pulp density of feed, the type and dosage of flocculating reagent, the pH of pulp, the intensity of mixing flocculant with tailings sand the use of stirring during compaction.It is shown that. for a sedimentation process taking place under given conditions, underflow pulp density (P) and sedimentation time (t) are related by the expression P = k.tn, where k and n are constants. A procedure is described for the use of this expression in thickener size estimations. IntroductionOften a considerable proportion of the mill feed is disposed as tailing, because the valuable mineral recovered usually forms a small fraction of the ore. Moreover, wet concentration processes result in liquid wastes that are several times more voluminous than the ore itself. Thus the handling and disposal of these wastes become an important cost item in most milling operations. The principal unit process employed in tailing disposal is solid-liquid separation which is traditionally carried out by gravity sedimentation in thickeners or tailing dams. Direct disposal of tailings into tailing dams is common practice where sufficiently large areas of land are available but it frequently becomes more economical or practical to densify the tailings in a thickener beforehand.Successful thickener operation depends essentially on correct thickener size which is in turn governed by the sedimentation characteristics of the tailings handled. Flocculation can aid the sedimentation process and bring about significant savings in thickener size, but its effective use requires a detailed study to identify the optimum conditions of application."

Jan 1, 1988

By Simon B. Blancher, Malo Rousseau, Renato Contessotto, Thomas Wallmach

The Manganese division of the ERAMET group extracts manganese ore in Gabon and produces manganese alloys for the steel industry. ERAMET has an economic interest to maximize the ore throughput without reducing the lifetime of its manganese mines. This can be achieved by means of research and development leading to innovative ore beneficiation processes. For this purpose, the ERAMET research center has designed and constructed a new pilot plant for ore beneficiation by physical separation processes. This pilot facility was erected within an infrastructural and synergetic framework, including competencies in hydrometallurgy, pyrometallurgy, numerical modelling, analyses and mineral characterization that provide ideal research conditions. After laboratory scale tests, a pilot operation of beneficiation of low grade Mn ore (around 35% Mn) was carried out by jigging of the 1-10 mm fraction. This gravity separation process exploits density differences between the various Mn-bearing minerals such as pyrolusite and lithiophorite as well as gangue minerals such as silicates and iron-hydroxides. Enrichment leads to the production of a marketable product associated with a high mass recovery (53% for the jigging step). However, 20% of pyrolusite and 30% of lithiophorite are lost in the waste. Mineral characterization has shown microtextural complexities, but grinding the ore to approach the liberation mesh was not an option due to commercially defined constraints given by the ferro-alloy industry. Recovery of the Mn-bearing minerals or adjustments of the feed grain size (6.3-10 mm) are two potential areas of process improvements identified by means of Qemscan® mineral characterization. This paper details the process tested on a pilot scale (0.5 t/h), which has led to a significant increase in the beneficiation of a low grade Mn ore.

Jan 1, 2016

By J. W. Reynolds

"The use of approved fire-resistant hydraulic fluids in equipment operating underground was made mandatory in British Columbia by amendment to the Provincial Mines Regulation Act effective January 1, 1975. This paper covers the action taken to achieve this, in the largest underground metal mine in British Columbia. Some evaluation of costs and effects based on experience to date is included.BackgroundAn amendment to the Mines Regulation Act of the Province of British Columbia was passed in July 1974 as follow s: "" Rule 111 (b) Hydraulic Fluids. After the first day of January 1975, all hydraulic fluids used in equipment operating underground shall be of a fire-resistant type accept able to the chief inspector.""Unquestionably, its intent was justified as a safety improvement measure. The list of fires in mines involving machinery where hydraulic fluid was a factor in the fires is long and sobering. In British Columbia, in a 22-month period from 1972 to 1974, there were six fires in metal mines resulting in extensive equipment damage and injury to four workmen. Nevertheless, no provision was made for research or development of systems modifications compatible with conditions encountered in B.C. and, as late as June 1977, the Mining Association of British Columbia continued to argue that fire suppression systems should be considered sufficient until a universal suitable hydraulic fluid could be developed. The sole concession was to issue permits for continued use of mineral oil in equipment bought prior to 1975 in order to allow producing operations to continue. The burden of developing the necessary technology was laid on the industry.The Sullivan Mine at Kimberley, the largest and longest established underground mine in the province, and Cominco's most important source of ore s for its smelter at Trail, B.C., was at the outset of a conversion from conventional to trackless mechanized mining methods in pillar recovery operation s. Introduction of fire-resistant hydraulic fluid s had to be done in a period of change, in many instances on equipment for which no data existed, and called for research which had to be done while retraining the work force.The introductory phase is complete. All equipment is on FRF, the requirements of Rule 111(b) are being satisfied, and a number of research and development programs continue."

Jan 1, 1980

By T. Alan O'Hara

"Annual mining revenue can be computed by formulae relating metal prices, smelting schedules, concentrate grade and recovery to known ore grade and an assessment of core samples. Operating costs at different daily tonnages are related to orebody shape, mining method, milling process and general plant services. Capital costs are related to sizing of mining equipment, mine development, plant-site topography, climate and accessibility, plant services and personnel housing. IntroductionA crude guide to the average 1978 cost of mine projects is shown in Figure 1, but the costs of many mine projects have differed widely from the graphed average costs of $800,000 T0.6 for underground mine/mill projects and $400,000 T 0.6 for low-grade open-pit mine/mill projects.High mine project costs and high operating costs are characteristic of open-pit mines with high stripping ratios, underground mines with thin orebodies, mills with complex metallurgy, and projects located in isolated regions with severe climate, mountainous topography, and lacking access to existing roads, towns and electric power. When none of these adverse conditions prevailed, the mine project cost was typically much less than the graphed average cost. Virtually all the conditions likely to cause high capital and operating costs are known from knowledge of the local topography, climate or accessibility, or can be assessed by tests on core samples, as soon as the orebody has been outlined by drilling .A more accurate estimate of over-all project capital cost and operating cost can be made from a summation of items of cost after judging the effect of specific local conditions on each item of capital and operating cost. This paper offers guides in judging the effect of local conditions on the sizing and 1978 cost of specific items of capital cost and operating cost and operating cost of mine projects. When the specific items of capital cost and operating cost are totaled and measured against expected net revenue and taxes over the life of the mine using the net-present-value or discount-cash-flow methods, the result should show whether the mine project development is clearly feasible, doubtfully feasible or clearly uneconomic. If the development of the mine project is clearly feasible, or probably feasible, a detailed feasibility study by experienced consulting engineers should be commissioned before any financial commitments are made; but if project development appears to be uneconomic, the time and cost of a detailed feasibility study is not warranted."

Jan 1, 1980

By D. Beneteau

Plotting sets of data collected over time using a frequency-magnitude distribution is common with both earthquake and mining seismology. A Time-Between-Events (TBE) analysis technique simply makes use of the inter-event times and b-values (slopes of the best fit lines on the frequency-magnitude charts) from the same set of data. Four distinct patterns in TBE versus Event Magnitude have been found which suggest whether there are constant seismic sources causing populations of data, or if the smaller and larger events, within the population represent varying seismic sources. Different rates of events, identified as TBE-rates in this study, may suggest whether the events are blast induced, or not. This study was done using actual seismic datasets from hardrock mines in Canada and Australia. This was to verify the applicability of the method to multiple mining environments and to determine the practicality and implications of this methodology to enhance the interpretation of seismic source mechanisms The results of the TBE technique and other proven techniques are combined into a Seismic Mechanism Assessment Worksheet. This is a tool that allows operators to compare trends within seismic datasets with assessments of in-situ rock conditions. The goal is to enhance the understanding of rockmass failure mechanisms.

Nov 1, 2011

By Michael L. Free, Zongliang Zhang, Joshua M. Werner

In the copper electrowinning process, short-circuiting between the anodes and the cathodes is a critical problem that changes the current allocation among local electrodes and reduces the current efficiency significantly. Possible reasons for the short-circuiting include the improper alignment of the electrode, bent electrode, and nodules on the cathode surface. In typical tankhouses, there is often a time between shorting and harvesting as well as between shorting and clearing. Therefore, it is inevitable to have short-circuiting affect the operation performance in practical electrowinning operations. However, one key piece of missing data is the actual measurements of the current efficiency as short-circuiting is approached and allowed to continue. Consequently, short-circuiting tests that allow tracking of electrowinning parameters before and after short-circuiting were performed in a laboratory scale Cu electrowinning cell. In the tests, the electrode spacing change, the mass of electrodeposited Cu, the deposition morphology, and the current allocation as well as the current efficiency before and after short-circuiting were studied. Results show that the short- circuiting affects the current allocation and the current efficiency significantly. Moreover, it changes the Cu deposition on the short-circuited cathode and therefore causes problems for Cu electrowinning. INTRODUCTION Electrowinning (EW) is commonly used for copper production around the world, with a rated production from 120,000 to 200,000 tons per year per operation (Wiechmann, Aqueveque, Henríquez, Muñoz, & Morales, 2014). In Cu electrowinning, Cu ions in the electrolyte are reduced on the cathode surface as metallic copper with a DC current, while on the anode, a counter anodic reaction occurs with oxygen gas generation (Werner, Zeng, Free, Zhang, & Cho, 2018; Zhang, Werner, & Free, 2018; Zhang, Werner, & Free, 2018). In copper electrowinning, an average current density of 200 to 400 A/m2 is applied to the electrowinning cell (Wiechmann et al., 2014). As the Cu deposits on the cathode, the distance between anode and cathode reduces and most of the time, short-circuiting forms between some anodes and cathodes in a large tankhouse containing thousands of electrodes, reducing the current efficiency and increasing the energy consumption significantly. The current efficiency in well-run copper EW operations is typically above 90 %. Most of the unused current is wasted through short circuits, stray currents, and by-byproduct formation (Davenport, King, Schlesinger, & Biswas, 2002; Wiechmann, Vidal, Pagliero, & Gonzalez, 2002; Wiechmann, Morales, & Aqueveque, 2010). Usually, in the tankhouse, the short-circuiting increases the current in the involved cathode by up to 1500 A (Wiechmann et al., 2010). Multiple reasons can cause the short-circuiting in the cell, and the most common reasons include the uneven current distribution among cathodes, tilted electrodes, bent electrodes, and nodules formed due to the large deposition roughness. Recognition of this challenge in the Cu electrowinning process has led researchers to perform many investigations on approaches to avoid and reduce the short-circuiting in the cell. A series of research investigations have been conducted to develop and improve a new type of intercell bar for Cu electrowinning (Wiechmann et al., 2002; Wiechmann, Morales, Aqueveque, & Burgos, 2007; Wiechmann, Morales, & Aqueveque, 2009; Wiechmann et al., 2010; Wiechmann et al., 2014). The associated test results show that this new design limits the occurrence and magnitude of short circuits and allows operation at higher current densities. Sandoval, Clayton, Dominguez, Unger, and Robinson (2010) stated several keys to control short circuits, such as maintaining the straightness of the cathode, removing “edge hair” from the cathode starter, and maintaining electrode alignment in the cell. Prengaman and Siegmund (1999) from RSR technologies developed a new Pb-Ca-Sn anode to prevent the anode deformation, thereby reducing the short-circuiting in the Cu electrowinning cell. Although the negative effects of short-circuiting on the Cu electrowinning have been recognized, and various investigations have been conducted to address this issue, the actual measurements of the electrowinning behavior and performance as short-circuiting is approached and allowed to continue are seldom reported. However, in typical tankhouses, there is a time between when shorting occurs and harvesting/clearing are performed. One key factor in determining the harvest time is the frequency of shorting. Consequently, we have performed short-circuiting tests that allow us to track electrowinning parameters before and after short-circuiting.

Jan 1, 2019

By Richard Samson

"RésuméComme l'exploitation d'un gisement à grande profondeur représente un défi de taille et que la profondeur à laquelle se situe celui d'Ansil varie de 1200 m à 1460 m, nous avons dû mettre en place une infrastructure de surface d'envergure incluant un treuil de production et un chevalement d'une très grande capacité. De même, l'infrastructure sous terre a été proposée en tenant compte de ce fait important; d'ailleurs, l'excavation de deux puits circulaires dont l'un est en beton et acier et l'autre exclusivement en béton en témoigne. De plus, la plupart des cheminées principales qui furent excavées sous terre sont de forme circulaire.L 'exploitation du gisement s'effectue par une méthode chantier ouvert (abattage par longs trous), remblaye immédiatement âpres avec un mélange de roche stérile et ciment. Un taux de minage de 1750 tonnes par jour est requis pour assurer la production.L 'utilisation d'une technologie de pointe tels: les ventilateurs et les portes de ventilation sous terre contrôlées de la surface, un système de relèves macroséismiques, de chargeuses-navettes contrôles à distance, en passant par le dessin et la planification assistes par ordinateur nous permet d'optimiser l'exploitation du gisement Ansil.IntroductionEtant donne la grande profondeur a laquelle le gisement Ansil se situe, no us avons à mettre en place une infrastructure souterraine et de surface d'envergure pour nous permettre d'atteindre nos objectifs d'exploitation.Infrastructure de surfaceLa mine Ansil dispose d'une infrastructure de surface d'importance possédant une grande capacité (Fig. I). Les deux facteurs qui furent déterminant pour le dimensionnement des infrastructures furent le taux d'extraction de 1990 t/jour et la profondeur a laquelle I 'exploitation s'effectue, puis que cette dernière affecte le temps de cycle et la capacité de hissage.La première composante principale de I 'infrastructure de surface est un treuil de production a 2 tambours de 3.65 m de diamètre et de 2.0 m de largeur chacun. Ce treuil de marque Fullerton, Hodgart & Barclay construit en 1970, opère avec 2 moteurs de 930 kW a une vitesse de 700 m/min. et il a une capacité maximale de 32000 kg. Deux câbles d'acier de 45 mm de diarnètre et de 160 000 kg de résistance a la rupture servant au hissage des bennes d'une capacité de 12 tonnes. De plus, un moteur/générateur de 3000 kW (M.G. Set) raccorde au treuil de production sert a stabliser son alimentation électrique."

Jan 1, 1991

By R. D. Brown

"Concerns over possible additional involvement of governments in Canada's mining industry and its adverse effects on the industry 's growth were a frequent topic of conversation at the recent Annual General Meeting of the CIM.Still painfully fresh in the minds of industry leaders are the disastrous results of the federal/provincial scramble over resource revenues which followed the relatively high metal prices witnessed in 1973/1974. At current metal prices, it is not surprising, then, that a nagging fear persists that these governments may once again restructure tax and other rules to the detriment of the industry and the country.This month, Tax Notes recalls some of the progress which the industry and governments have made in 1979 in the taxation of the resource sector, and urges that higher metal prices be viewed in light of the costly exploration, development and production efforts which will be required for the industry to continue to play its important role in our economy.IntroductionAt the Annual General Meeting of The Canadian Institute of Mining and Metallurgy, held in April, 1980, it was abundantly clear that there is widespread concern in Canada's mining industry that this country's tax regime may once again be blasted by ill winds of change.A stable and more favourable tax climate, as well as higher metal prices and profits, made 1979 almost a golden year for Canadian mining. However, from the tax viewpoint at least, there are some spots on the silver lining as apprehensions grow that the well-heralded battle between federal and provincial governments over oil and gas may spread to the mining sector, with serious damage to the industry and its newfound federal-provincial cooperation."

Jan 1, 1980

By H. N. Tran, D. Barham

"A systematic survey of the appropriate literature in terms of phase equilibria and possible reactions involving deposits in Municipal Solid Waste (MSW) incinerators are analyzed particularly with respect to the theoretical first melting points of typical ashes and the possible presence of a liquid phase at the temperature of ash-metal interface. Conclusions are drawn on the basis of the possible presence or absence of various metal chlorides and sulphates in such situations, and their effects on the problems of fouling and metal corrosion. From preliminary results, it would appear that ZnCl2 is unlikely to be present in any molten phase which causes corrosion because it evaporates rapidly from such liquids. It would also appear that PbCl2 and, by inference, ZnCl2 will sulphate at relatively low temperatures if the flue gas contains SO2 and O2.IntroductionMunicipal Solid Waste (MSW) incinerators produce fly ash which deposits on heat transfer surfaces throughout the furnace, leading to corrosion and loss of energy recovery efficiency. Despite a massive amount of research carried out on the subject of corrosion in MSW incinerators, the problem of corrosion of heat transfer metal is still with us, and no definite over-all cause and effect relationship has yet been identified. In order to make a contribution to the eventual solution of this problem, the authors have examined the problem from the beginning, using their knowledge of fouling and corrosion problems in black liquor recovery boilers as a starting point.The incineration of MSW has been used for many years to reduce the volume of material sent to landfill (ash volume compared to raw waste volume), and, in most cases, to recover energy at the same time by raising steam The steam may be ""low- or high pressure/ temperature"" depending on its end use. The higher the steam pressure and temperature, the greater seem to be the problems with corrosion of heat exchanger metal, presumably because the metal must withstand higher surface temperatures.The chemical and physical composition of MSW is extremely variable, not only on a regional basis, seasonal basis, and day-today basis, but also on a minute-by-minute basis, due to the inhomogeneity of MSW. This makes it extremely difficult to define cause and effect relationships, because both cause and effect are transient in nature."

Jan 1, 1991

By M. L. Jeremic

"The syngenetic and epigenetic mechanics of sedimentation and deformation of coal seams resulted in various types of internal structure, as listed below:TYPE I-massive structure with evenly distributed coal constituencies of integrated mechanical properties.TYPE II-broad-banded structure, with bright and dull coal bands of differential mechanical properties.TYPE III-heterogeneous structure, with sheared coal bands and partings of sectional mechanical properties.TYPE IV-contortional structure, with refolded coal layers and deteriorated mechanical properties.TYPE V-porous structure of orogenically crushed and pulverized coal, with disintegrated mechanical properties.The study suggests criteria for the estimation of coal seam internal structure (gamma-gamma density log and cracks density log), which might be related to the evaluation of strata stability and coal mineability.IntroductionIt is common knowledge that coal seams have various internal structures due to different syngenetic and epigenetic events. Investigations of the internal structure of coal seams have been carried out in the coal fields of Western Canada, as follows: geological field studies of coal-bearing strata;?,geophysical borehole surveying studies;?,geological borehole logging and crack density;?,underground phenomenological studies of mine structure;?,chemical coal analysis; and?,mechanical testing of coal samples.These investigations eliminated a large number of criteria previously established for the estimation of coal seam internal structure and indicated that, from an engineering point of view, only two of them are sufficient:(I) density of seam profile (inferred from gamma-gamma log);(2) density of crack s (inferred from geological log).On the basis of these criteria, five main structural types of coal seams have been classified, which might be related to mechanics of deformation and ' failure of mine structures."

Jan 1, 1982