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By A. J. Paul Laprairie

The process for which it is to be used is too often the only consideration in the design of a vessel. A de-sign allowing for practical manufacture and erection, as well as for proper maintenance, can often give over-all economies. Most platework in-stalled today is of welded construction. Therefore, metallurgical control is important in its manufacture. Also, because many concentrating and re-fining processes tend to be corrosive, the subject of protective coatings as a part of the manufacturing process is extremely important. The plant de-signer should know how to evaluate and specify controls for the metallurgy and for the coatings. Mining operations are becoming more sophisticated in the field of mechanical engineering. More and more emphasis is being given to preventive maintenance. The first step in any maintenance program, however, is good inspection service. This paper will suggest methods for the inspection of platework, and outline methods for repair and replacement.

Jan 1, 1963

By Yihan Liu, Jintao Zhang, Chen Xiao, Xiaomeng Zhao, Guanglei Song

To estimate the performance of the inert anode materials based on NiFe2O4 spinel ceramic during it used for aluminum electrolysis, we investigated the wetting process of cryolite molten salt which is in composition of industrial aluminum electrolysis with carbon anode and NiFe2O4 based cermet materials, by means of determination the interface wetting angle between the molten cryolite electrolyte and the solid anodes interface. The results show that the wetting angle between the electrolyte and carbon anode is larger than 90 angulation, this means that they basically can not wetting; however the nickel ferrate spinel ceramics behaves much better. In regard to the NiFe2O4 matrix materials, their initial wetting angles is 76.9. The initial wetting angles for 1.0wt%MnO2, 2.5wt%TiO2 and 0.5wt%V2O5-doped samples are respectively 56.86°, 52.98° and 51.93°. However, after 50s later, all the wetting angles came down below 15°.

Jan 1, 2015

By P. R. Clark, M. D. Gleghorn

"IntroductionAt TransAlta Utilities Corporation's Highvale Mine, located west of Edmonton, Alberta (Fig. I and 2), dragline stripping has proved to be a practical and economical method of overburden removal and future plans have been based upon the continued use of draglines (Fig. 3) as the major stripping equipment (Williams, 1979, Nikols et al., 1986). However, long range planning has shown that the capacity of draglines alone will be exceeded in the early 1990s as mining progresses into deeper overburden cover (Tapics, 1983). Strip ratios will increase from I.3 bank m!/ t of coal in 1985to 4.5 bank m3 / t in 1995. During this period the depth of overburden will increase substantially and the areas to be mined will be characterized by weak soils including glacially displaced overburden. This increased overburden depth in relatively weak soils will make it impractical to _continue side casting by draglines without prestripping in advance. In 1983, a major investigation was initiated to determine what additional overburden removal equipment was appropriate to the Highvale operations, and recognizing the long delivery times of this major equipment. when it would be required. This paper describes studies and tests which were undertaken in 1983 and 1984 to select prestripping methods and equipment for the future operation of the mine.Previous planning studies have shown that with the current burn schedule and with the economies of progressing from low cover to high cover, as has been practiced in the past, overburden volumes will exceed the capacity of the existing draglines in the early 1990s (Fig. 4). These previous studies had placed reliance on (I tandem dragline operation for future overburden removal requirements up to a depth of 45 m throughout the Highvale Mine. New drilling together with the associated geotechnical studies and some detailed planning on the practicality of using tandem draglines, created concerns about their universal application. Even without considering geotechnical conditions there was a depth limitation to tandem dragJines and substantial prestripping would be required to achieve the ultimate depths."

Jan 1, 1987

By H. F. Maulson

For the benefit of those who are not familiar with the history of the western Provinces-Manitoba, Saskatchewan, and Alberta-as regards our natural resources, a few words of explanation may be in order before taking up the consideration of the Mines Act of 1930. In 1867, The British North America Act was passed by the Imperial Parliament. That Act, which is our constitution, created a union between the provinces of Nova Scotia, New Brunswick, and Upper and Lower Canada (now known as Ontario and Quebec respectively) under the name of the Dominion of Canada. Provision was made therein for embracing other parts of Canada from time to time. That portion of Canada which today comprises the Provinces of Manitoba, Saskatchewan, and Alberta and the lands to the north of them, was then known as Ruperts Land and the North West Territory. In the year 1670, King Charles II had granted by Letters Patent to Prince Rupert and his associates, known as ?The Governor & Company of Gentlemen Adventurers of England, Trading into Hudson's Bay?, commonly known as the Hudson's Bay Company, the lands and territories therein described, being roughly all the lands adjacent to and west of Hudson's bay; also the gold and silver to be found or discovered therein and other rights as more fully described in said Letters Patent. The land so granted was called 'Ruperts Land'.

Jan 1, 1930

The Cooperative Research Centre for Mining Technology and Equipment (CMTE) is funded by the Commonwealth Government, by its mining research members Ñ the Universities of Queensland and Sydney and the CSIRO1, and by its industry members Ñ BHP Coal, RioTinto R&TD, Hamersley Iron, Mining Technologies Australia, Pasminco, Shell Coal, WMC Resources, Advanced Mining Technologies, and Aberfoyle. The Centre conducts work aimed at improving the competitiveness of the Australian mining industry. The current work is focused in four areas: new mining and drilling systems, geological sensing, automation, and equipment maintenance and reliability. This paper describes much of the work in these program areas that relates to metalliferous mining.

Jan 1, 2001

By K. H. Concannon, K. I. Hindle

"The use of simulation modeling in the primary metals industry (including mining, smelting, and metals processing) is expanding as significant cost-benefits can be realized by companies employing capital intensive processes. The economic scale and complexity of operations found in this industry is well-suited to applications using this ""what-if' computer modeling technique, ranging from proof-of-concept projects to testing facility design or configuration, and determining resource requirements. More recently this technique is being used to support on-going planning and scheduling for operations using the simulation as the engine to derive the best schedule. With increased computer processing capability, deterministic models are now being developed to capture the workings of a production system or conversion process, allowing real-time monitoring and scheduling of these operations. This paper presents a sample of some recent discrete-event simulation modeling applications that demonstrate the capability and benefits of this technique in the primary metals industry. These include the use of simulation to support the long-range planning of underground mining operations; the modeling of a metals supply chain network that employs a multi-modal distribution system; the scheduling of a metals coil finishing process using a deterministic simulation model; and a more detailed description of the use of simulation to model furnace and converter aisle activities within a smelter operation in Northern Canada."

Jan 1, 2007

By Maurice Séguin

The primary aim of all ground geophysical work has been, of course, to locate orebodies. As with any geo-physical method, its success depends on a proper mastering of the types of surveys and equipment used and their application to the physical properties associated with the orebodies. The Schefferville deposits are iron ores subjected to enrichment by the process of leaching. Although some ore types are porous and low in demiity, most of the ore zones have had a net increase in density brought about by enrichment. In the course of their formation, the magnetic characteristics of the rocks have usually changed, as much of the magnetite was altered to relatively non-magnetic iron oxides and hydrous iron oxides. Ali drift-covered areas underlain with iron-formation are potential ore-producing areas. From these first two physical proper-ties and a determination of the thickness of the over-burden, a combined gravity-magnetic-seismic and/or resistivity survey allows for the detection and sorting out of iron-formation and potential ore zones from the country rocks. If the iron-formation possessed relatively uniform physical and chemical properties, the problem of locating areas underlain with ore, using geophysical methods, would be greatly simplified. Unfortunately, the iron-formation is a complex assemblage of rock types, each having different physical and chemical characteristics. In spite of this, qualitative and semi-quantitative correlation between the results of the surveys and the geology and structure of the area could be established. In addition, a semi-quantitative to quantitative correlation of the values of the residual gravity anomalies with the specific gravity, the iron content, the porosity factor, the dimensions of the under-lying orebodies and the values of the ground magnetic intensity above a reference lithologie unit, with the per cent weight Fe304 recovery and the susceptibility, led to the discovery of a direct-shipping iron ore deposit in the Schefferville mining district of Canada.

Jan 1, 1968

By M. J. Latva-Kokko, T. J. Riihimäki

"Oxidation autoclaves are normally operated at elevated temperature and pressure. The improvement in kinetics is due to combined effect of temperature and partial pressure of oxygen. In this paper exclusive effect of pressure has been studied with a low grade sulphide ore at below 100 °C temperature. These studies are related to development of a novel tower-like reactor that utilizes hydrostatic pressure. Technology is designed to generate high amount of effective fluid volume for high solid content slurries with lower energy consumption and improved kinetics compared to normal atmospheric operation.INTRODUCTIONEconomical utilization of low-grade ores requires handling of enormous amount of material. This sets new requirements for process equipment in terms of size and energy efficiency. For example on the field of mineral processing this has lead to a six fold increase in the operating volume of mechanical flotation cells over the past two decades. Ore beneficiation methods like flotation greatly reduce amount of material that needs to be further processed in smelters or hydrometallurgical refineries. However with some ore types, such as nickel laterites and refractory gold ores, traditional concentration technologies cannot be utilized. Thus direct leaching of ground ore could be an attractive option. In many cases normal atmospheric tank leaching has traditionally been a non-feasible option mainly due to high capital and operational expenses induced by large amount of stirred reactors required. Main restriction for increasing reactor size to beyond 500 m3 has been mechanical load and power requirements set by mixing in cases when high dispersion efficiency of gas is required. THEORETICAL BACKGROUNDIn hydrometallurgical industry autoclaves are typically operated at elevated temperature and pressure. In many cases increase in operating temperature is the desired phenomena and improvements in kinetics are strongly related to that. Thus increase in pressure might be induced solely by water vapor pressure. However when gaseous feed is present, pressure itself has a strong effect on leaching kinetics for various reasons and its role should not be neglected."

Jan 1, 2012

By A. Khan, C. Ciriello

The purpose of this paper is to demonstrate the value of constraint modelling in optimization of mineral processing systems. This will be achieved by first understanding the overall concept of variation and constraints present in any system. Next, the value of using a Constraint Model in optimization is demonstrated through comparison of business cases. The benefit of understanding the severity of constraints and movement of the bottleneck within a mineral processing system will be understood through the use of a case study. Paper will conclude with a summary of all optimization benefits that utilization of a constraint model can bring.

Jan 1, 2015

By Michael Boyle, John Zeni

"The Blind shaft boring method is a mechanised process of excavating large diameter vertical shafts downward from the surface. It is a rotary drilling technique eliminating any requirement for personnel to enter the shaft or access underground workings during drilling and lining phases. Excavated material is delivered to surface carried by a flow of circulating fluid through the centre of drill rods. The drill assembly is suspended from a large A-frame rig and powerful winch at ground level providing vertical thrust to a hard rock cutter head. INTRODUCTION The Southern Coalfields Ventilation Shaft was constructed at a mine, 45 km north-west of Wollongong. The 5 m finished diameter (6.2 m drilled) shaft reaches a final drilled depth of 517 m, the deepest, fully lined blind bored vent shaft to date in Australia. Operated by a mining company in the Southern Coalfields, the expanding mine required a new ventilation shaft and associated surface infrastructure to service future operations. An assessment of future ventilation requirements for the coal seam operations identified a need to improve the capacity and reliability of the existing underground ventilation system in order to ensure a safe and efficient underground working environment. Installation of the new upcast ventilation shaft was determined to be the most cost effective and reliable solution to provide adequate ventilation for underground operations. The completed shaft is smooth and fully lined with steel/concrete composite liners that are hydrostatically sealed. The shaft lining is designed to meet the mine ventilation requirements for a service life of 20 years. The shaft intersects the top of the working section of the coal seam at approximately 513 m of depth. This includes the shaft collar depth and shaft bottom profiled intake section.PROJECT METHODOLOGY AND INDUSTRY BEST PRACTICE The shaft was drilled using the blind bore method, an innovative construction technique and an alternative to the traditional methods of sinking deep and large diameter shafts, such as raise boring and conventional drill and blast shaft sinking. The blind bore method allows the shaft to be drilled from the surface down without anyone having to enter the shaft or the mine during the construction process. This is by far the safest method of shaft construction and is especially suitable for difficult ground conditions where there may be unstable or water-charged strata. As this method involves drilling from the surface downward, shafts can be completed ahead of the underground mine development. Thus, allowing underground operations to focus on development and production without the conflicts of managing ventilation priority for underground contractors and mucking out spoil from excavation workings."

Jan 1, 2019

By N. A. Duke, R. L. Carpenter

Abstract - The West Meliadine area is underlain by structurally interleaved panels of mafic and minor ultramafic metavolcanic rocks and metasedimentary rocks that occur along the northern margin of the Neoarchean Rankin Inlet greenstone belt. Three structural and metamorphic domains are recognized: (1) the easterly Wesmeg domain; (2) the central Barracuda-Ridge domain; and (3) the westerly Peter Lake domain. The Wesmeg domain is characterized by a series of southeast-trending, north-dipping, foliation-parallel panels of greenschist facies mafic metavolcanic and metasedimentary rocks. The Barracuda-Ridge domain is comprised of greenschist to amphibolite facies mafic metavolcanic rocks that define an east-northeast-trending structural grain. The Peter Lake domain consists of amphibolite facies mafic metavolcanic rocks and minor metasedimentary rocks intruded by a monzonite pluton. West Meliadine hosts the economically significant Wesmeg gold deposits, as well as other important gold showings across the Barracuda-Ridge and Peter Lake domains. The geological setting of the Wesmeg gold deposits resembles that of a break or fault zone. The Pyke Break is a major geophysical discontinuity (>65-km strike length) and is the first-order structural control on gold mineralization at West Meliadine. It is several kilometers wide and characterized by polyphase deformation and shear zone development accompanied by lode-gold mineralization. In general, gold concentration is related to quartz and iron-carbonate veining, iron sulfides (mainly arsenopyrite and pyrrhotite), and accompanying silicate alteration minerals that overprint favorable chemical and structural traps late in the history of deformation.

Jan 1, 2004

By C. Samson, R. S. Smith, S. W. Hefford

"Abstract - Time-domain electromagnetic systems are most sensitive to highly conductive targets during the transmitter on-time. Data collected during the on-time is highly influenced by the geometric relationship between the transmitter and the receiver. Unless corrections can be applied for these geometric variations, the ability to correctly detect and identify highly conductive targets can not be fully realized. Variables affecting the relative position between the transmitter and receiver include changes in the position of the receiver with respect to the transmitter, variations in transmitter attitude, and transmitter loop deformation. The level of accuracy in the determination of the relative geometry required to permit complete removal of the effects due to geometric variations is different for each of the variables and is dependent on the depth of the target. The most influential geometric variation involves changes in the relative position of the receiver with respect to the transmitter along the direction of flight; this variable, therefore, requires the highest degree of accuracy. The accuracy required for receiver motions along the vertical direction is roughly one order of magnitude less, and in the lateral direction, several orders of magnitude less. The objective of this paper is to relate the sensitivity of the response to transmitter-receiver geometry to the ability of an airborne, time-domain electromagnetic system to resolve a highly conductive vertical target. This is achieved by a detailed analysis of the effect of the individual x, y, and z distances between the transmitter and the receiver, the transmitter attitude (roll, pitch, and yaw), and transmitter deformation.Sommaire - Les systèmes électromagnétiques en domaine temporel sont particulièrement sensibles aux cibles à forte conductivité durant le temps d’excitation. Les données collectées durant l’émission du transmetteur sont fortement affectées par les relations géométriques entre le transmetteur et le récepteur. Si un facteur de correction n’est pas introduit pour tenir compte de ces variations géométriques, la capacité de ces systèmes à détecter et identifier correctement les cibles fortement conductrices ne peut pas être pleinement réalisée. Les facteurs affectant les positions relatives du transmetteur et du récepteur comprennent les changements de position du récepteur relativement au transmetteur, les changements d’altitude du transmetteur et la déformation de la boucle du transmetteur. Le degré de précision requis pour déterminer la configuration nécesaire pour compenser complètement l‘effet des changements géométriques est différent pour chacune des variables et dépend de la profondeur de la cible. Les changements géométriques qui ont le plus d’influence sont ceux qui font varier la position du récepteur relativement au transmetteur dans l’axe de la ligne de vol; c’est donc cette variable qu’il faut contrôler avec le plus de précision. La précision requise pour le suivi des mouvements du récepteur le long de l’axe vertical est moindre d’environ un ordre de grandeur, tandis que selon l’axe latéral elle est diminuée de plusieurs ordres de grandeur. Le but du présent article est d’établir comment la susceptibilité de la réponse à la géométrie transmetteur-récepteur affecte la capacité d’un système électromagnétique en domaine temporel aéroporté à reconnaître une cible verticale fortement conductrice. Cet objectif est atteint par l’analyse détaillée de l’effet individuel des distances x, y, et z entre le transmetteur et le récepteur, l’attitude du transmetteur (lacet, roulis, tangage) et la déformation du transmetteur."

Jan 1, 2006

By K. D. Genn, A. Mucha

This paper deals with Hilton Mines' approach to the maintenance of wear items such as truck boxes, shovel buckets, tractor pads, crawler sprocket idlers and the drop-ball. Each will be given a brief. description as to application, design, kind of materials involved and type of wear. The maintenance procedure is then outlined in terms of materials used, preliminary preparation, and welding and machining practices. The service history of new and re-paired items and the relative economics of repair vs replacement will then be presented.

Jan 1, 1969

By A. Ignatow

"A review is made of some of the principal factors and conditions that are, and will be, important to the over-all market climate for asbestos fibre and for the future of Canada's asbestos industry: - health hazard associated with asbestos exposure;- uncertain international regulatory environment for continued asbestos use;- adverse public reaction to asbestos;- product liability/litigation costs (U.S.A. primarily);- promotion of substitution by governments and asbestos user industries; and- minimal product and market development efforts by asbestos producing and consuming industries.In addition, Canadian producers, who export some 95 per cent of their production, face additional constraints:- dramatically reduced integration with asbestos-consuming industries;- 60 per cent of exports to most rapidly declining markets (U.S.A., Europe);- increased competition from offshore producers favourably located to growth markets in developing countries;- increasing production costs;- a strong dollar;- disadvantageous freight rates; and- loss of price leadership and price erosion.Future market trends, as well as prospects for Canada's asbestos industry, will be projected in this paper.Economic FactorsTable 1 presents asbestos fibre production in all countries for the period 1980-82. In certain instances, e.g. U.S.S.R. and China, these are capacity estimates as production statistics are not officially published. The U.S.S.R, by far, is the world's largest producer accounting for some 50 per cent of world production, though most production is consumed internally or by COMECON countries. It is estimated that some 700 plants produce asbestos-containing products within the U.S.S.R.Canada accounts for some 25 per cent of world production though it ranks first in world trade. Other important producers are South Africa Zimbabwe, Brazil and Italy. Since 1979, Canada's asbestos mining industry has experienced a dramatic drop in production and exports of asbestos fibre, as demonstrated in Table 2."

Jan 1, 1985

By Stephen Mullowney

Outline ? Setting the stage ? Deal activity ? Q1 2013 update ? Key deal sectors ? Deals by geography ? Outlook for 2013 Key Observations 2012 ? Major retreat in M&A activity ? Glencore-Xstrata deal dwarfs all other deals ? Gold & copper dominate deal activity

May 1, 2013

By A. D. Misener, L. G. D. Thompson

"IntroductionIt was shown by work previously reported that reliable geothermal gradients representative of various regions of the earth's, surface could he obtained from extended surveys of the rock temperatures in operating mines. These surveys showed the presence of anomalies in the isothermal levels and the existence of regions of regular behaviour. Below about 3,000 feet the temperature gradients became quite regular over the areas stud1ed. It is these regular gradients which are taken as representative of the region, wherever possible.The present paper describes the extension of this work which was undertaken to obtain further temperature gradients with a view to correlating them to other geophysical properties determined for the same regions. The additional data obtained have indicated possible reasons for the temperature anomalies. The experimental procedure was similar to that already described and was again made possible through the wholehearted co-operation of the management and the assistance of the personnel of the mines concerned. The research was entirely supported by a grant from the Research Council of Ontario.The equipment was a distinct improvement over that previously used and made it possible to take many more accurate temperature readings in a given time. Thermistor resistance thermometers were used, encased in silver sheaths and protected against damage by heavy copper casings. These were calibrated with a standard platinum resistance thermometer.The bridge used with these thermometers was one of a number designed and built by the Meteorological Service and designated M.S.C. Thermometer Indicator Type C-3. This very convenient and portable instrument operated from batteries in the instrument case. Multiple thermometer connections were provided so that rapid readings• of a number of thermometers was possible to accuracy of the order of 0.1°F. All electrical connections on the panel are covered with Dow-Corning ignition compound to prevent; electrical leakage due to moisture condensation. This, together with the high resistance of the thermometers and components of the bridge, gave much more reliable results than previously obtainable."

Jan 1, 1950

By K. D. Bulin

"An interesting brief history review of shovels as the primary excavating tool will permit the reader to see that immeasurable development and resources have preceded the shovel excavators which today are used extensively throughout the mining industry. With this as a background, the shovel manufacturer has the ability to utilize his resources best in those areas of shovel development in which the maximum benefits of increased reliability, performance and ease of maintenance will improve the operating rewards to the user of the equipment. The author explains the function of the shovel as a part of the material handling system. A detailed description of those areas of the shovel in which the most recent developments and major improvements have been implemented in the manufacture of the shovel excavator arc included."

Jan 1, 1973

By D. G. Tisdale, W. Curlook, J. M. Toguri

"In this study, the vapour phase reduction of titanium tetrachloride conforms to the traditional Kroll chemistry, but employs argon as an inert carrier gas and requires a higher reaction temperature of 1150°C to 1250°C. A vapour phase reaction is advantageous because titanium is the only condensed phase present, and the metal can be collected free of magnesium or magnesium chloride, in marked contrast to the titanium sponge produced by the conventional Kroll process. The yield of metallic titanium from the reaction was determined as magnesium additions ranged from 36% to 168% of the stoichiometric requirement. Yields of over 99% were obtained when an excess of magnesium was present. Although the collection efficiency was low, metallic titanium was collected at the reaction site, where all other species were present as vapours. Magnesium and chlorine concentrations in the collected titanium were less than 0.3%.IntroductionA proposed method (Curlook, 1987) for titanium production has been investigated as an alternative to the conventional Kroll process (Kroll, 1940). The advantages of the new process include a simplified means of recovering the product metal, and a potential for lower overall energy consumption and greater product purity. A higher reaction temperature for the reduction of titanium tetrachloride results in a vapour phase reaction, rather than the conventional liquid phase reaction. This is the major conceptual difference between the proposed and the established (Kroll) processes.This study focussed on optimization of the process chemistry and briefly examined the issue of product deposition and collection. The reduction of titanium tetrachloride with magnesium, to produce metallic titanium and gaseous magnesium chloride:"

Jan 1, 1997

By J. G. Kelly

"IntroductionOver the past twenty-five years of improvements to scooptrams In the Ontario Division of Inco Ltd., records indicate that on average, an 8 yard capacity machine at 80% availability will load, haul and dump about 100TPH from an average stoping area. This, essentially, means that Inco mines are limited to 2000 TPD as an approximate maximum production cap per minute. Some of the improvements made to scooptrams over this period have been:• dry disc and oil immersed brakes on larger loaders;• to replace air over hydraulic systems;• modulated shift transmissions;• greater breakout and tramming capacities by using larger engines and buckets;• operators' compartments have been enlarged and better seats,• joystick controls and air-conditioned cabs have been utilized'• major cost savings have been realized through tire maintenance improvements; and• major savings, safety improvements and increased ore recovery by using remote controls.After reciting the improvements listed above, and the list is by no means exhaustive, it is quite obvious that scooptrams are a mature product and that major design or performance improvements will not occur in the futre. Any futher improvements will be incremental in nature. Loading, hauling, and dumping with scooptrams is a batch process and as such is limited in its total output.Continuous Load/Crush/Convey Systems:In order to improve productivity, a radical new system was required. The target was 2000 tons per shift. In 1984, to meet the goal, Inco acquired the rights to a contiunous loader from Canadian Mine Services. Inco made modifications to the original prototype machine, such as: (I) conversion from rail mounted to crawlers for increased mobility; (2) a hydraulic cooling system was added; (3) flight bars were changed from cast to forged; (4) motor horsepower increased to 200 hp from 150 hp. Emerging from these modifications came a machine known as the CL-looo Oscilloader (Fig. 1).The CL-looo Oscilloader is an electric hydraulic 35-ton machine which is crawler mounted and has a drawbar pull of 30 tons. It has an adjustable frequency, oscillating lip which simulates the digging action of a manual .shovel. This action agitates and lifts the muckpile enough to allow it to settle by gravity onto the chain and flight conveyor table which then removes the ore to the tail end for discharge into either a crusher, a conveyor, a truck, or a combination of these.Late in 1985, six oscilloaders were fabricated and put into Inco mines for field trials. At Creighton Mine some early field trials were conducted with a rail mounted continuous loader loading directly into 140 cu.ft. Granby cars. Much of the field testing was in VRM drawpoints with the Oscilloader loading into 20-ton trucks or into Teletrams . At Levack Mine, by puttmg the truck on remote control, it was possible to have the operator run the Oscilloader and load his own truck (Fig. 2). At McCreedy West Mine, Copper Cliff North Mine, and Copper Cliff South Mine, the Oscilloaders discharged directly into 26-ton trucks."

Jan 1, 1988

By A. P. Yovanovic, P. Bonadia, M. N. Moraes, C. F. Matos

"The magnesite flotation operation of Magnesita Refractories, in Brumado – Brazil, has four parallel ball mills working in closed circuit with hydrocyclones to grind the ore for the reverse flotation of silicates in mechanical cells. The modification proposed here opens the circuit for three of the ball mills so that their products are collected together to feed a high frequency screen. The oversize of the screen feeds the fourth ball mill in closed circuit for secondary comminution. The product reports to dewatering and flotation. The undersize undergoes desliming and subsequent flotation operation. According to pilot tests performed, the modification on the magnesite flotation operation will promote a 20% increase in the productivity, 8.5% increase in mass recovery and a 26% reduction in water consumption. The gains are due to the fact that the silicates in the feed are concentrated in the smaller particles (<100µm) with over grinding in the existing closed comminution circuit, making it impossible to take advantage of this natural selectivity. The combination of open circuit, more selective milling, and the high frequency screen, ensures high efficiency particle size classification. This renders the process more effective, both to the screen undersize with its high contents of silicates and fines, and to the screen oversize, which is almost without fines and has a higher magnesite grade. This situation allows for the setting of specific parameters for the flotation of both the primary milling undersize and the secondary milling product.INTRODUCTIONMagnesita Refractories, with its operations site in Brumado, is the largest producer of high purity dead burned magnesia (DBM) in Latin America. The magnesite ore is extracted from an open pit mine, named Pomba, after which it is crushed and handpicked. Due to the presence of disseminated silicate the ore has to be ground and concentrated by means of reverse flotation, before feeding the high temperature kilns for sintering and conversion to DBM.The magnesite flotation unit has an impact crusher to reduce the size of the feeding ore, which is transported to the mills by conveyor belts. The milling operation is composed of four ball mills in closed circuit with hydrocyclones. The closed circuit generates a high circulating load with excess fines, which is detrimental to the selectivity of the desliming and flotation operations, reducing both mass andmetallurgical recovery.In the current scenario, the capacity of the flotation plant is insufficient to meet the demand of the DBM kilns, forcing the operation to work with high purity ores in order to attain the highest possible mass recovery in the concentration process. This is not an ideal situation as it requires the mining site to work with higher stripping ratios.The objective of this work was to improve the magnesite flotation unity to increase its productivity. After a detailed analysis, the milling was identified as the limiting process, which made the authors to focus on this operation."

Jan 1, 2016