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By Peter Moon, Lloyd G. Campbell

"How well supervisors supervise, and are supervised determines whether management's goals will be reached and ...how effective the work force will be... Upper management must recognize the potential returns of viable training programs for both management and mine workers… The key to performance, from the standpoint of safety and productivity, is the ability of the line supervisor to manage(1).In this article, the authors will share their experiences in supervisor selection and development. They also draw on the work of two men in particular, Douglas Bray and William Byham, both of whom have contributed significantly to the understanding of supervisory development and training.IntroductionYears ago, there was not much training for supervisors. They worked under an authoritarian style of management and modelled themselves on it. They were generally selected for their skill as miners, mill operators or mechanics. Things have changed. Today, companies have different needs. The selection of supervisors is far too important to rely on guesswork. Progressive companies want supervisors who think like managers - supervisors who know how to plan and organize, set performance standards and monitor them, analyze problems, develop solutions, show sound judgment and deal effectively with people. The evaluation of these supervisory ""dimensions"" is best accomplished through the use of an assessment centre. The Assessment Centre Method increases the accuracy of predicting the future success of candidates being considered for promotion.Mining and other resource companies use assessment centres to select the most suitable people for supervision. The Assessment Centre Method is based on extensive research. It eliminates hit-and-miss selection methods by using several different exercises that simulate the problems and activities that candidates would face if they were promoted into supervision . In other words, they get a realistic "" sample"" of the supervisor's job and are required to deal with and manage interpersonal and problematic circumstances."

Jan 1, 1990

By I. Farr, P. Quinn, H. Mani

"Difficulties in the flotation of Inca's ultramafic ores at the Thompson Mill are related to the presence of serpentine slimes and some floatable rock minerals. Serpentine slime coatings depress pentlandite recovery while rock flotation decreases concentrate grade. Carboxy methyl cellulose (CMG) has been shown to promote sulphide flotation and to reject floatable rock.To improve ultramafic ore flotation, CMC addition in the rougher stage was studied in a laboratory scale column. Batch tests were conducted in the lab and followed up with continuous testwork at the Thompson mill. At 0.5-1.0 g CMG per kg ore, pentlandite recovery is increased by 5-10% in rougher flotation, pentlandite/rock selectivity is improved and pentlandite/pyrrhotite selectivity is unaffected.IntroductionAt Inca's Manitoba Division, two distinctly different sulphide ores are processed at the Thompson Mill, primarily by froth flotation. The sulfide ores are contained within the Thompson Nickel Belt and currently there are two operating mines, Thompson and Birchtree. Sulphide mineralization in both mines is simple, consisting of pyrrhotite (both monoclinic and hexagonal), pentlandite, and minor chalcopyrite. Both deposits are hosted by metasedimentary and metavolcanic rocks with variable ultramafic rock associations. Ultramafic rocks are mostly serpentinites: magnesium rich rocks composed predominately of serpentine. There is little serpentinite at the Thompson mine, while mineralization at Birchtree is closely associated with significant ultramafic rocks.Excellent recoveries of pentlandite (Pn) and chalcopyrite (Cp) are achieved at the Thompson Mill when processing ore from the Thompson mine. In treating the ultramafic associated Birchtree ore, nickel recoveries are some 6 to 8% below that achieved with Thompson ore. Furthermore, a typical concentrate from Birchtree ore contains more rock and is higher in MgO content. The presence of rock in the concentrate is related to free floatable rock species as well as rock locked with sulfides. The reason for the difference in flotation responses of these two ores has been the subject of on-going re-search."

Jan 1, 1998

By Brian Penney

"The Iron Ore Company of Canada (IOCC} has mined and processed an iron deposit in Western Labrador along the Labrador-Quebec border since the early 1960' s. Current capacity is approximately 19 million tonnes of concentrate, 70% of which is converted to pellets at these facilities.The ore deposits are located in hills rising 150 to 300 meters above the adjacent lakes, and most of them are covered by very little overburden. The iron minerals are mainly specular hematite and magnetite hosted in a quartz formation. Crude ore averages 40% Fe that is concentrated to 65.5% Fe. IOCC is an extensive operation extending from Labrador City NF to Sept-Iles Quebec. It consists of open pit mining, concentrating, pelletizing, railway, and dock loading facilities.The Concentrator liberates iron from the silica by crushing and grinding the ore to -14 mesh (-1190 microns}. Ground ore is concentrated in spirals and filtered for transportation. Spiral tailings are treated in a Magnetic Recovery Plant (Mag Plant} that recovers lost magnetite. Mag Plant tailings are treated in a Hematite Spiral Plant (Hem Plant} that scavenges fine iron remaining in this stream.This report deals with ongoing iron recovery initiatives within the ConcentratorIron Losses in the ConcentratorIron recovery at IOCC is approximately 70.5%. This compares with recoveries that range from 65% to 86% for other iron mines in our area. Other world large iron ore producers dig and ship concentrate quality ore directly out of the ground and have an effective recovery of 100%. With increasing costs for labour, equipment, and supplies an increase in iron recovery is required to keep the operation viable.More than 90% of our iron concentrate is produced by gravity separation using spirals. The physical characteristics of the iron minerals that most effect recovery are mineral grain size and degree of liberation. We divide ground ore into three size categories -coarse, intermediate, and fines. A brief description of each size fraction follows:"

Jan 1, 1996

By Alan R. Holt

"This paper provides an overview of the use of uranium and coal in Ontario Hydro's generation program. The dynamics of available supply sources including mining and transportation infrastructures and regional considerations are described. Included is a discussion of needed procurement strategies, both in place and planned, to meet fluctuating fuel requirements while ensuring adequate supply security and cost effectiveness. IntroductionDuring the first half of this century, Ontario Hydro or the Hydro Electric Power Commission of Ontario, as it was then known substantially supplied all of the province's electricity needs from a large number of hydraulic generating stations. Although hydraulic power still provides a very significant part of Ontario energy requirements, this paper will concentrate on the role of uranium and coal in their generation program. To provide a perspective on the importance of these two fuels, Figure I shows the approximate value of each for the past few years in relation to Hydro's total operating costs. The trend toward increasing nuclear output and a corresponding decline in coal use is also clearly illustrated.Figure 2 shows the currently installed capacity of their three main energy sources, hydraulic, nuclear and coal and the 1986 production totals for each, followed by Table I which compares the average operating or running cost on the basis of dollars per megawatt hour for each type of plant. It demonstrates dramatically why Ontario Hydro base load s its hydraulic and nuclear plants, and why coal has become the swing fuel on the system. Although they have a 1200 megawatt plant in Toronto with natural gas-burning capability, and a 2000 megawatt oil-fired station near Kingston, both are presently mothballed and have not been considered in this paper.This paper starts with a user's perspective of the nuclear fuel supply situation which will be discussed in relation to the usual considerations of security, flexibility and cost."

Jan 1, 1988

By Isabel F. Barton, Matthew J. Gabriel, Mark D. Barton

Process control, mine-to-mill optimization, and other mining operations depend on having robust, comprehensive mineralogical and chemical characterization. However, current characterization methods rely primarily on analyzing samples from trenches, channels, blast holes, and drill holes and interpolating between them, and are not always sensitive to some minerals (such as clays) that cause major problems for mining and mineral processing. Continuous characterization is possible with techniques such as hyperspectral remote sensing, which measures reflectance or absorption of light in the visible to near infrared (VNIR) and short-wave infrared (SWIR) regions of the electromagnetic spectrum. Absorption and reflectance features are characteristic of different chemical bond types, so each spectrum corresponds to a different mineral or material. In remote sensing, each pixel in the scanned area has both a location and a spectrum. This makes hyperspectral remote sensing potentially useful for characterizing mine site materials. In this study, we tested a hyperspectral remote sensing system as a method of characterizing the mineralogy and material types at mine and metallurgical sites. Our test site was a small open-pit copper mine and leach operation in the southwestern U.S. We scanned mine highwalls, dump piles, leach pads, and nearby rock outcrops with drone- and tripod-mounted VNIR-SWIR spectrometers. We collected ground-truth data through geologic mapping, sampling, and spot analyses with a portable short-wave SWIR instrument. The results show that the hyperspectral remote sensing system that we tested is capable of distinguishing the types and distribution of spectrally active minerals and other materials in diverse mining settings, including showing wet and dry areas of leach pads; clay and carbonate type and distribution on mine highwalls, leach pads, dumps, and rock outcrops; plant type and distribution; fault zones, bedding planes, and other geological features; and qualitative spectral matches between dump piles and areas of the mine highwalls. Hyperspectral sensing proved particularly sensitive to the presence and type of clay and carbonate minerals, which cause geotechnical and metallurgical problems such as highwall failure, gangue acid consumption, and flotation sliming. Examples will be presented and discussed at the conference. Areas of continuing research include automating and streamlining the data reduction process, integrating hyperspectral data with block modeling and mine planning software, and testing the results of hyperspectral sensing in different geological environments.

Jan 1, 2019

By Robert Voisey, Robert J. Spencer

"LynnGold's MacLellan Mine is located about 8 km south east of Lynn Lake immediately to the east of the Keewatin River (Fig. I). The property is accessible by an all-weather road, leading north from the provincial highway 391, which links with the Town of Leaf Rapids and the City of Thompson to the south.The ore body, as outlined in the original feasibility study, is expected to produce in excess of 9.3 x IQ6 gm of gold and silver over the next 5 years. However, the deposit is open to depth and exploration is continuing on and around the main zone and the many satellite deposits.The start of construction of the MacLellan Mine and mill was scheduled to phase in with the closure of the Fox copper-zinc mine located 48 km west of Lynn Lake. The majority of the employees from the Fox Operation were either employed at the MacLellan Mine or relocated to Sherrin's Ruttan Operation.GeologyThe MacLellan gold ore deposit is located on the northern section of the Lynn Lake Greenstone Belt known as the Rainbow Trend. This Trend is a 40 km gold bearing rock sequence extending both east and west from the MacLellan Mine. The southern section of these two east-west trending structures is known as the Johnson Shear, this is also gold bearing."

Jan 1, 1990

The concept and practices of co-extraction of coal and methane have emerged in recent years to improve coal mining safety and productivity, utilise methane resources, and reduce fugitive emissions in environments that involve multiple coal seams with low gas permeability. The system of co-extraction integrates two previously separate operations of coal extraction and methane drainage. The coal mining operation reduces the coal seam gas pressure and creates strata fractures that enhance gas migration and capture from mine workings and surrounding coal seams. An effective methane drainage operation produces a consistent and quality clean energy product and, at the same time, reduces the methane concentration in underground workings and the methane content and pressure in the adjacent coal seams. This is a significant benefit in preventing gas explosions and outbursts, and promotes a safer and more productive coal mining environment. In addition, the co-extraction with enhanced utilisation of coal mine methane directly leads to a reduction in greenhouse gas emissions. Presented in this paper are key results and outcomes of a major Asia Pacific Partnership project carried out from 2008?2012 by the Commonwealth Scientific and Industrial Research Organisation in collaboration with Huainan Mining Industry (Group) Co. Ltd., to develop and demonstrate advanced technologies at Pansan mine, Huainan, that promote the concept and practices of co-extraction of coal and methane. A comprehensive approach was adopted to assess fundamental strata and coal seam methane conditions during mining, and optimise mining sequences and coal mine methane capture systems. The project has not only demonstrated a practical approach and procedures of advanced co-extraction of coal and methane systems but also delivered significant benefits and outcomes in improved mining safety and efficiency, increased methane capture and utilisation, and reduced fugitive methane emissions at the Pansan mine. The total mine gas drained increased from 25.36 Mm3 in 2007 to 47.0 Mm3 in 2011, and the mine gas utilisation increased from 4.94 Mm3 in 2007 to 21.15 Mm3 in 2011. The improved methane capture resulted in reduced coal and gas outburst risks and methane concentration levels at the mine workings, provided a safe working environment for coal production, boosted the mining efficiency, and eliminated methane related incidents over the last few years at Pansan mine.

Aug 1, 2013

By J. Karonen, M. Tiihonen, J. Guentner, L. Haavanlammi, Outotec GmbH, E. Kolehmainen

"Rare earth elements have obtained significant attention during the last few years due to predicted increase in their demand. Several projects worldwide are at pre-feasibility or feasibility stage aiming to commence production. Deposits of rare earth elements are typically complex and multi-metallic of nature. This means that production processes are often also complex and therefore, various metallurgical unit processes are needed. Outotec’s equipment and technology portfolio is very comprehensive and includes hydrometallurgical and pyrometallurgical apparatus and processes applicable to the efficient exploitation of rare earth deposits. Outotec has gained useful experience relevant to the processing of rare earths through several assignments including those for Alkane Resources Ltd. (Dubbo Zirconia Project), Greenland Minerals and Energy Ltd (Kvanefjeld Project), Frontier Rare Earths Limited (Zandkopsdrift project), Tantalus Rare Earths AG (Madagascar), Quest Rare Metals (Strange Lake project) and Orbite Aluminae Inc. (HPA project). The hydrometallurgical test work of two process flowsheets is presented in the paper. A roasting or acid baking step is common to several proposed rare earth projects. In the past, rotary kilns have been used, but Outotec has developed a new process concept to handle the rare earth material in fluid bed reactors. The basis for this development is long experience in fluid bed technology of Outotec in Germany. One advantage of fluid bed roasting is the higher throughput per unit. In combination with the roasting and baking, Outotec offers the gas cleaning and acid plant and provides a complete and closed concept.INTRODUCTIONRecovery of rare earth elements (REE) has obtained significant attention during recent years. It has been estimated that their demand will be boosted because of their need in many technology areas. REE can be utilized in magnets, batteries, displays, catalysts, optical devices etc. (Jordens, Cheng, & Waters, 2013; Zhang & Edwards, 2013). The production of REE is focused in China, which means that production outside of China is very scarce. However, there are multiple active development projects worldwide working towards production of REE containing products outside of China (Chen, 2011)."

Jan 1, 2016

By Andrew Artzer, Michael Moats, Jack Bender

Antimony and bismuth in copper electrorefining electrolytes can cause cathode contamination, leading to the careful control of their concentrations. This study examined the laboratory scale removal of bismuth and antimony from an electrorefining electrolyte using a solvent extraction mini-pilot plant. The ability of a proprietary phosphonic acid ester extractant (REX-2) in a commercial diluent was studied in a simulated commercial setting. Antimony and bismuth were both extracted effectively from the electrolyte (72% Bi and 70% Sb removed) and Bi was effectively stripped (92% Bi recovered) with 400 g/L sulfuric acid. A final strip solution was obtained from the SX circuit containing 0.36 g/L Bi, 0.043 g/L Sb, 1.3 g/L Cu, and 0.18 g/L As. Unfortunately, most of the extracted Sb remained in the organic phase. Following the pilot study, experiments were performed to examine the precipitation of bismuth from the aqueous strip phase and the removal of antimony loaded on to REX-2. INTRODUCTION For many years, antimony and bismuth have been some of the most problematic impurities in copper electrorefining (ER) (Bardwell & Lapee, 1933). Along with surface roughening, high concentrations of Sb and Bi can contaminate the copper cathode and precipitate at the copper grain boundaries. This drastically reduces the drawing ability of the metal (Bender & Emmerich, 2016). For these reasons, it is necessary to control Sb and Bi concentration in the cathode, which is done by controlling their concentration in the electrolyte. Conventionally, Sb and Bi concentrations are controlled by maintaining a proper As/(Sb+Bi) molar ratio in the anode and arsenic concentration in the electrolyte. Antimony and bismuth are removed during electrolyte purification using liberators (electrowinning cells) and/or ion exchange. Liberators treat an electrolyte bleed stream from the ER circuit and electrodeposit increasingly impure copper as the copper concentration of the solution decreases. Traditionally, first stage liberators reduce the copper concentration from ~45 g/L to ~15 g/L and produce saleable copper. Second stage liberators decrease the copper concentration to ~8 g/L (Biswas & Davenport, 1980) which results in contaminated cathode that is returned to anode production (Biswas & Davenport, 1980; Wang, 2004). Further electrolyte purification is not always required but third stage liberators can be used to reduce copper concentration below 2 g/L which results in significant removal of As, Sb and Bi and very impure deposits which are recycled to a smelter or used for As production. However, liberators do not have very high energy efficiency (Acharya, 2014; Ando & Tsuchida, 1997) and below 0.5 g/L copper, highly toxic arsine gas may form (Biswas & Davenport, 1980).

Jan 1, 2019

By Makarinskym F. M.

"This paper describes mechanical and operating modifications that were and are being made to current on-line flotation cells at Falconbridge Nickel Mines concentrators. Improved metallurgical performance and metal recoveries of some 3·4% over the past ten years are the end result of the modifications made. The paper acknowledges the contribution of operating, technical and maintenance personnel and the Company ""suggestion plan"" program. 1. INTRODUCTIONFalconbrirdge Nickel Mines Limited, incorporated in 1928 is a major product of nickel, copper,coba1t and other metals and minerals. The Canadian Nickel Division operating facilities in the Sudbury Area currently includes seven mines, two concentrators, and a smelter.For many years at all concentrators, improv0mcnts in metal recoveries have been continually under investigation. One area was to improve the flotation cell performance. This paper will deal with mechanical and operating modifications to the cells at the Strathcona and Falconhridge Ni-Cu sulphide concentrators, at the Sudbury Operations.One of the prime means to mineral beneficiation processing has been, and will continue to be, the basic froth flotation cell. The efficient operation of a flotation cell is the key to satisfactory metal selectivity and recovery. The essence of good design is simplicity. Changes to cell design can contribute to a significant improvement in metal recovery.Over the past 10 years, modifications to the flotation cells have contributed to an improvement of some 3-4” in mineral recovery. Providi11g tl1c initiative for improvements include operating, maintenance and technical personnel, as well as the employee suggestions submitted th1·ough the Suggestion Plan Program."

Jan 1, 1982

By K. E. Waters, C. Marion, T. Grammatikopoulos, A. Jordens

"The Nechalacho deposit, located in the Northwest Territories, Canada, is a heavy rare earth element (REE) deposit. The main REE-bearing minerals in the deposit are zircon, allanite, bastnäsite, synchysite, columbite (Fe) and fergusonite. Previous work investigated the use of gravity and magnetic separation in the processing of this ore and showed that coarse particles following grinding were enriched in zircon, suggesting the potential for selective comminution. The current work investigates the possibility to selectively comminute gangue minerals and concentrate REE-bearing zircon into coarser size fractions. The ore was ground wet in a laboratory rod mill for various lengths of time (0, 10, 20, 30, and 40 min). The resultant products were analyzed using ICP-MS, to determine the distribution of zirconium and REEs in the different size fractions produced after grinding, and QEMSCAN, to identify mineral phases, mineral liberation and the distribution of minerals. Optimum grind sizes for the upgrading of zircon due to selective comminution were then proposed, and dense medium separation was investigated as a means to further concentrate zircon.It is important to note that this process is not representative of the currently selected process design or recovery for the Nechalacho deposit. Any application of this process to this deposit would require optimization in order to ensure appropriate grade and recovery targets are met.INTRODUCTIONThe rare earth elements (REEs) are the fifteen elements in the lanthanide series of the Periodic Table, as well as yttrium (scandium is excluded in this work). Traditionally, REEs are categorized into two groups: the cerium sub-group of “light” rare earth elements (LREEs); and the yttrium sub-group of “heavy” rare earth elements (HREEs) (Golev et al., 2014). The LREEs comprise the first six lanthanides (lanthanum through samarium) and the HREEs comprise the remaining nine lanthanide elements (europium through lutetium) coupled with yttrium (Golev et al., 2014). HREEs are much less abundant in the earth’s crust and on average are more expensive than LREEs (Seredin, 2010). Of the fifteen REEs, the production of neodymium, europium, terbium, dysprosium and yttrium has been determined to be most critical due to their scarcity, high demand and criticality in many high-technology and clean energy applications, such as in illuminated screens for electronic devices and permanent magnets in wind turbines (Seredin, 2010; U.S. Department of Energy, 2011). These five elements are classified as critical rare earth elements (CREEs) (U.S. Department of Energy, 2011)."

Jan 1, 2016

By G. Danha, S. Wabula, D. Glasser, D. Hildebrandt, N. Hlabangana

"Impact tests on single particles or a bed of particles are used to determine the fracture characteristics of particles. Many different techniques have been adopted in comminution in order to find ways of optimizing energy consumption in the size reduction process. In this paper, we apply one such method called the Attainable Region (AR) analysis technique to optimize the impact energy on a bed of silica particles. The attainable region is a fundamental approach that is equipment-independent and can be used to analyze breakage processes. The AR is defined as a set of all possible outcomes, for the system under consideration that can be achieved using fundamental processes operating within the system.INTRODUCTIONThe energy crisis in Southern African has reached such critical levels, that most cities in countries like Zambia, Zimbabwe, Lesotho, Swaziland and even South Africa are experiencing load shedding challenges lasting sometimes up to 18 hrs a day. Southern Africa is well known for its riches in mineral resources, and the economies of most states in this region are driven by the mining & mineral processing sector. With the emergence of small scale miners due to government empowerment policies, national energy providers have had to resort to power cuts mainly to domestic users in a bid to cope up with the huge industrial electricity demands.It has been estimated that about 4% of the total energy used in the world is consumed by the mineral processing sector (Fuerstenau & Lutch, 1999). Tomanec and Milovanovic (1994) estimated that milling alone accounts for more than 50% of the total power used in mineral processing, but this can rise to as high as 70% for hard or finely dispersed and inter-grown ores. Today, the greatest challenge in mineral processing is how to optimize energy input to the size reduction process (Dey & Das, 2013; Nomura & Tanaka, 2011), where it has been observed that only a small percentage (1.5%) of the total energy input really does the breaking (Khumalo et al., 2008) while the rest is consumed by the equipment concerned and lost to contacts that do not result in breakage. The immediate benefits of focusing research on the optimization of energy in size reduction operations in the mineral processing sector lies in potential savings on industrial electricity usage that may then be directed towards domestic users."

Jan 1, 2016

By V. G. Minenko, A. L. Samusev

For efficient leaching of gold from sulfide ores and the oxidation of sulfides into sulfates, it is necessary to introduce a substantial amount of oxidant - atomic oxygen, hydrogen peroxide, ozone, potassium or sodium hypochlorite. In this paper, hypochlorite electrochemical treatment is proposed as an effective method of intensification of refractory ore leaching. The objective of the study is to increase the gold recovery from refractory ores with the application of chlorinated solutions that are modified by chemical or electrochemical treatment. The advantages of the use of the modified chlorinated solutions instead of cyanide for gold-sulfide leaching are considered to be the following: a high concentration of the oxidizing agent (hypochlorite ions) in solution helps to achieve a high speed of gold dissolution in the form of chloride complexes; the possibility to produce hydrochloric acid solutions that may be used for the recovering gold by electrolysis; the possibility of the processing of carbonaceous, arsenic-bearing and others kinds of refractory gold ores. The mechanism of the interaction of the modified chlorine solutions with gold-bearing sulfides (pyrite and arsenopyrite) was investigated. The efficiency of the application of chemical and electrochemical leaching method was proved. The main factor that limits the rate of gold dissolution is a high concentration of sulfate ions (SO4 2-) formed in the solution by the oxidation of sulfide minerals. The optimal parameters of chemical and electrochemical leaching method and effective ways to remove sulfate ions were determined. The method helps to increase the level of the gold recovery up to 87% from refractory ores. The intensification of leaching by chemical and electrochemical treatment opens up opportunities for the creation of modern efficient and environmentally-friendly technologies that may be applied for gold extraction from refractory gold ores.

Jan 1, 2016

By P. R. A. Andrews, R. K. Collings

"SUMMARYIn cooperation with the Ontario Ministry of Natural Resources, selected deposits of Potsdam sandstone in the Ottawa-Kingston area were core-drilled and evaluated by CANMET as potential glass and foundry sand. Analyses of cores ranged from 84.6 to 98.5% Si02, 0.09 to 0.65% Fe203' and 0.07 to 2.10% A12°3' The cores were largely composed of white to grey, relatively tough sandstone. Impurities included iron as pyrite, iron oxides and staining on the quartz grains; carbonates as calcite; and aluminum oxide as feldspar. Beneficiation included size reduction to grain size, about 600 um, by jaw, roll and cone crushers, and grinding in a muller-mixer. Removal of fines was achieved by attrition scrubbing and washing. Further removal of impurities was achieved by reverse flotation of pyrite, iron oxide, feldspar, and carbonate minerals employing both anionic and cationic collectors. Flotation resulted in a substantial improvement in the quality of most samples; analyses of quartz concentrates showed 98.5 to 99.7% Sial> 0.022 to 0.156% Fe203' and 0.07 to 0.62% A1203. Further reduction of the iron content by wet magnetic separation and acid leaching also was investigated. On the basis of the samples submitted, sands/ones from six of the seven deposits studied have potential as sources of glass sand. Foundry sand tests were inconclusive because of the small quantities available for study."

Jan 1, 1986

By R. L. Guerguerian, Eugene Bercel

"Grinding mill hydrostatic trunnion bearings require an external pumping source to provide and maintain the oil film between the bearing members. In order to guarantee a predetermined minimum film thickness, the lubrication system tends to be oversized. The oil film is ""indirectly"" controlled by flow, pressure and temperature monitors with fixed settings on the conservative side. This can lead to excessive maintenance and abbreviated life for the lubrication system components. A reliable method of monitoring actual film thickness would not only provide greater mill availability, but also minimize maintenance costs.This paper describes the instrumentation installed in Dominion hydrostatic bearings, and presents results of field tests where the output of that instrumentation was recorded under various operating conditions.IntroductionThe trend toward larger and more sophisticated grinding mills has made the operators of these machines increasingly vulnerable to financial loss, as the cost of downtime and repairs has increased directly with machine size. In order to guard against such losses, it is becoming imperative that large, sophisticated grinding mills be equipped with protective instrumentation to monitor some of the critical operating parameters and to identify events and trends which, if they go unnoticed, can lead to excessive maintenance costs and machine downtime. The idea of protective monitoring systems is not new. The operators of certain types of machinery where a high degree of safety is required or where machinery health can deteriorate very rapidly, as in the case of high-speed turbo-machinery, have long been using protective instrumentation on their machines. The increased awareness of the benefits of monitoring machinery conditions and the availability of reliable and relatively low-cost instrumentation of a large range of sophistication is making the practice now widespread. Traditionally, grinding mills have not been considered as high-risk machinery requiring instrumented protection. However, the trend, mentioned earlier, toward employing fewer, but larger capacity, mills increases the risk of significant disruption of production, and therefore measures to minimize the risks are desirable."

Jan 1, 1981

By Norman M. P. Low

"IntroductionIndustrial applications of mica utilize two commercially important varieties of mica: muscovite and phlogopite. Muscovite mica is a potassium mica with a general chemical formula, H2KA1(Si04)3 h, and is sometimes referred to as a potas hsilicate. Phlogopite is a magnesium mica having a general chemical formula, H2KMgSi(Si04)3, and is distinguished from the muscovite mica by its decomposition in sulphuric acid.Canada is one of the major natural mica producers in the world. A large tonnage of the mica powders is at present mined and processed in the Eastern Townships of Quebec. This Canadian mica is of the phlogopite type. A closely related mineral of the mica family which is widely used in the construction industry is vermiculite. It is a dehydrated magnesium-aluminum-iron silicate characterized by a foliated structure. Expanded vermiculite, which is often referred to as exfoliated mica, is used as many types of thermal and acoustic insulation, as loose fill in buildings, as an aggregate in concrete, as an ingredient in plaster and insulating concrete , and in fire-proofing compositions. Natural phlogopite and muscovite mica powders are used extensively as reinforcing agents in organic polymers. They also have a wide range of applications in commerical products. For example, dry-ground mica powders are used in large tonnage as a surface finish in roofing materials and as a bonding agent in wallboard joint cement. Common products such as paint, rubber, plastics and welding rods contain mica. Recent studies have also shown that mica powders can be added to portland cement in the preparation of concrete products, as they could improve the tensile strength of the concrete products. The potential and possible"

Jan 1, 1982

By Mike Anderson

The annual budget for the repair and maintenance of equipment at Syncrude Canada Ltd is in excess of 450 million dollars. Of this amount, a significant portion can be attributed to the loss of material on various pieces of equipment throughout the operation. In order to effectively battle the different wear and corrosion mechanisms that lead to material loss, it is important to understand how materials behave in the environments in which they are used. Through the work carried out at Syncrude, and work conducted with various external collaborators, significant improvements in both equipment reliability and productivity have been achieved. This paper will review some recent field trails where materials research has demonstrated the potential for significant improvements in equipment run life and reduced maintenance costs. These field trails will demonstrate the need for understanding the interaction between various damage mechanisms and the materials used in different services. The paper will also discuss current areas of focus along with future directions for further work.

May 1, 2003

By Bennett McLaughlin, Gille Brousseau, John F. Cook

"La Mine Bousquet commenced operations in October 1979. Mining has been by underground methods from two main zones which dip steeply to the south , Sub-level stoping methods with following fill are used.The orebody and immediate country rocks are sericitic and highly schistose. The intensity of schistosity varies significantly and poor ground conditions prevail, especially within the orebody,Initially few mining problems were encountered but in May 1981, significant damage occurred. A system of stabilizing pillars was introduced with improved support systems. Predevelopment in ore and pre-drilling of blastholes were reduced with extra footwall development.Damage has continued to occur on a regular basis particularly during the spring thaw. Generally, the adverse conditions have been successfully overcome.IntroductionMost of the mining problems that have been experienced at Bousquet have been caused by poor ground conditions . This pa per describes these conditions, considers the cause and describes the ways in which the conditions have been dealt with . Despite the problems, Bousquet is a successful operation which in 1983 produced 95,000 ozs of gold from 514,000 tons of ore."

Jan 1, 1985

By Pura Alfonso, Sarbast Hamid, Hernan Anticoi, Eduard Guasch, Josep Oliva

"Av. Bases de Manresa 61-63, Manresa (08242) Barcelona, SpainTantalum is a strategic metal and an improvement of the mineral processing is an important issue. The main objective of this work is to optimize the grinding technologies for tantalum ores with high pressure grinding rolls. The selected ore for this study was an altered leucogranite from the Penouta Open Pit Mine (NW Spain). In the present work mono-size experiments have been carried out using grinding rolls with controlled pressure. The particle size distribution has been monitored in the input and output of the high pressure grinding rolls for each experiment. The cylinder pressure that is transmitted to the particles has been determined. New population balance models are presented for high pressure grinding rolls with parameter adjust for tantalum ore. The obtained model uses the physical description of particles under the comminution action of the grinding rolls. The obtained results are in agreement with other models and the errors in the adjustment are low. The selection function proposed for this model describes adequately the breakage probability of the particles inside the high pressure grinding rolls. The presented model can be a good alternative for simulating a high pressure grinding roll process. INTRODUCTIONTechnology for grinding have been improved for many years, introducing new variables and parameters involving energy consumption, mechanical stress analysis of the compression particles or pressure application for optimizing the comminution (Morrell et al, 1997). High pressure grinding rolls is a modern technology that is proven to reduce the operating costs in full scale plants when compared with other milling technologies. Its benefits on energy saving and simplicity in the process have been studied and applied, first in the cement clinker industry (Abouzeid & Fuerstenau, 2009) and after in mining activities, especially in metallic ore deposits (Austin et al, 1991; Guevara & Menacho, 1992; Morrel et al, 1997; Torres & Casali 2009; Numbi & Xia, 2015). Many author structures of the High Pressure Grinding Rolls modelling in three main branches; (a) throughput modelling, (b) Power and energy model and (c) particle size distribution modelling (Austin et al, 1991; Guevara & Menacho, 1992; Austin & Trubelja, 1994; Morrel et al, 1997; Torres & Casali, 2009)."

Jan 1, 2016

By M. Lahtinen, B. Saxén, M. Latva-Kokko

The conventional jarosite precipitation process with neutralization by zinc calcine is widely utilized in the zinc industry. However, it has a significant drawback of causing losses of valuable metals like zinc, lead and silver to the jarosite. This comes mainly from the content of these metals in the calcine used for neutralization. As the zinc plants today want to maximize metal recoveries and minimize the amount of residues, this matter has become more and more relevant for zinc producers. Outotec developed and patented in early 2000 an improved version of the jarosite precipitation process in which the need for neutralization can be minimized, thus the metal losses to the jarosite also can be minimized. At the same time, the iron content of the jarosite increases and the amount of produced jarosite is smaller. The main feature of this process is to start the precipitation from ferrous iron after having reduced all the iron by zinc concentrate in a separate step before jarosite precipitation. Iron is then oxidised back to the ferric form simultaneously with jarosite precipitation. By this method, the formation of sulphuric acid is only half that compared to the conventional method and the need for calcine for neutralization can be avoided. High mixing and oxygen dispersion capability are needed in this jarosite precipitation process. Such capabilities are found in the Outotec OKTOP® reactor series. High performance reactors are not only needed to generate high quality precipitates, but also to maximize oxygen utilization; i.e., to minimize operation costs. Outotec’s latest development in this area is the OKTOP® plant product in which not only the reactors, but also all the accessories are designed, manufactured and delivered by Outotec. One responsible supplier ensures efficient and fast delivery and can provide mechanical and performance guarantees for the entire plant unit.

Jan 1, 2016