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We report the studies of Proton-Exchange Membrane Fuel Cells (PEM FC) and hydrogen storage materials at McMaster University for the last 14 years. From the initial investigation of ionic conduction mechanism to the revelation of the origin of non-Arrhenius temperature dependence, as well as the synthesis and characterization of high temperature polymer electrolytes, both experimental and theoretical works have been compiled for the fuel cell membranes. In addition to the discovery of suppressed ionic conduction in Electrode-Membrane Assembly (EMA) and novel hydrocarbon PEMs based on micro-emulsion, the first evidence of hydrogen adsorption saturation by carbon nano-tubes was also achieved, which has been the bottleneck for the application of PEM FC. Prior to our study, a number of controversial publications have claimed the hydrogen capacity of these materials to be between 0.1 to 10.0 wt.%, and none demonstrated a plateau of adsorption with pressure that is consistent with monolayer saturation. Others suggested that the tube bundle structure is opened under high pressure to enable higher adsorption on newly uncovered surfaces, but received no confirmation. Using our home made high-pressure instrument with in-situ electrical probes, we found that a plateau is nearly achieved at about 300 atm in the room temperature isotherm, and that nanotube bundles actually compress with pressure instead of splitting, using in-situ electrical measurements.

Jan 1, 2005

By Richard Maurice

RÉSUMÉ La restauration du site minier Poirier, à Joutel s?est déroulée entre 1998 et 2001. Le principal élément des travaux a été la restauration du parc à résidus et des zones d?épanchement qui totalisaient 4,5 millions tonnes de résidus répartis sur une superficie de 74 hectares. Les résidus sont fortement générateurs de drainage minier acide. La première partie de la présentation consiste en un bref rappel du concept de restauration suivi d?une description des principaux éléments de travaux avec l?emphase sur les leçons apprises de l?exécution des travaux. La deuxième partie de la présentation est axée sur les résultats du programme de suivi en cours depuis la fin des travaux en 2001. Les éléments de suivi se rapportent à la baisse du niveau de la nappe phréatique à l?intérieur de la cellule, au tassement des résidus dans la cellule, aux mesures de température et d?oxygène à l?intérieur de la cellule et finalement à l?amélioration dans la qualité de l?eau de surface. ABSTRACT The reclamation of Poirier Mine, in Joutel, was carried out between 1998 and 2001. The main component of the works has been the reclamation of the tailings basin and tailings spill area which contained a total of 4,5 million tonnes of tailings and occupied some 74 hectares of ground surface. The mine tailings are highly acid-generating. The first part of the presentation will deal with a brief review of the reclamation plan followed by a short description of the main work components laying emphasis on experience gained during construction. The second part of the presentation will deal with the results obtained from the environmental monitoring program still in progress since the end of reclamation work in 2001. The aspects discussed include the drawdown of pore water inside the covered tailing pile, the settlement of mine waste material, the monitoring of moisture, temperature and oxygen underneath the liner and finally, the reduction of loadings in surface water.

Nov 1, 2002

By John Russell

"Faster, safer, grinding mill relining offers the obvious attractions of reduced mill relining times with the knock-on incentive to reduce all other maintenance down-time, opening the possibility for increased annual plant utilisation.Leading edge liner handler technologies by RME, focused toward even shorter relines for very large SAG and AG mills, have recently split into two quite distinct paths:•,?Single SAG/AG Mill Relining Machines (MRM’s) of very large capacity, such as Newcrest Cadia’s 40’ SAG MRM of 6000 kg capacity and P.T. Freeport’s 38’/34’ SAG MRM of 7250 kg capacity;•,?Twin-machine SAG/AG Mill Relining Systems of moderate to large capacity such as BHP Billiton’s Escondida Laguna Seca 38’ SAG MRM’s, each featuring 4500 kg capacity.RME, its customers noted above and their liner suppliers are providing leadership in this important annual utilisation advance.Once the 24 hour mill shell reline becomes reality, liners designed for maximum profit, not maximum life, albeit exchanged more frequently, become possible too.INTRODUCTIONAt most mineral grinding plants, mill relining activities dictate each maintenance shutdown’s critical path. When annualized, mill relining remains the largest, single influence in defining plant availability.Because of restricted access, both inside and outside the mill, increased application of manual labour has no effect on reducing relining downtime. The only answer for RME has been to develop and apply new relining technologies now known as RME’s Mill Relining System.RME’s primary focus for over twenty years has been the reduction of grinding mill relining times while simultaneously providing a marked improvement in relining safety. Our original (1990) target was to halve traditional (pre-RME) reline times and to eliminate accidents and injury by mechanizing all physical work."

Jan 1, 2008

By Joël P. T. Kapusta

Back in 1995, Air Liquide and Union Minière presented a joint paper at the Copper 95 – Cobre 95 Conference in Santiago, Chile, describing the first full scale plant trials of shrouded sonic injection in a Hoboken converter at the Hoboken smelter in Belgium. Almost a quarter of a century later, the technology known as ALSI, or Air Liquide Shrouded Injection, has been tested or commercially implemented in several copper and nickel smelters. Despite these successes, the copper industry did not adopt it widely in the same manner the steel industry adopted the Savard-Lee tuyere in the 1970s and beyond, not even in the way the lead industry adopted it with the Queneau-Schuhmann-Lurgi, or QSL, process. The development and implementation of bottom-blowing smelting and converting technologies in China in the last ten years, however, changed the industry’s perception that high- and ultra-high oxygen injection in copper smelting and converting was indeed possible under specific process conditions. In this paper, I retrace the key learnings of my journey with sonic injection over the twenty five years from my humble beginnings in my early years with Air Liquide, through plant trials and technology implementation in the late 1990s and into the first decade of the new millennium, and ultimately, to the most conclusive proof that the sonic injection design methodology I established is valid, and the calculation tools I developed are accurate. I conclude by sharing my thoughts about whether the deployment of the Savard and Lee legacy within the nonferrous industry was just a pipe dream or whether it will become a reality. INTRODUCTION In the context of lower quality ores and changing economic markets, copper smelters need to continuously innovate and improve to remain competitive and respect their corporate social responsibility engagements. One avenue towards this business, social, and environmental goal is to increase process intensity while lowering fossil fuel consumption to lower greenhouse gas emissions and reducing process off-gas volumes to better capture As and SO2–laden emissions. I believe high oxygen sonic injection for submerged tuyere copper bath smelting and converting is one technology that can help smelters achieve that goal of higher business, social, and environmental performance. Twenty five years ago, when I discovered that the Savard-Lee tuyere had revolutionized the steel industry (Savard & Lee, 1966; Knuppel, Brotzmann, Fassbieder, Savard, & Lee, 1972), I had a dream — or was it a vision? — that within the first decade of the new millennium, modern copper smelters operating submerged tuyere bath smelting and converting vessels will have implemented high oxygen sonic injection and will be reaping the financial and environmental benefits that the steel industry enjoyed in the 1970s. As we approach the end of the second decade of the new millennium, I have to admit that my dream has been all but shattered as the majority of copper bath smelting and converting vessels today continue to operate under bubbling regime conditions. This mode of operation is archaic, still requires tuyere punching and blows at inherently low enrichment levels, particularly in converting, producing large volumes of process off-gases. Under such operating conditions, regulations and emission quotas for As, SO2, and particulate matter oblige smelters to use not just primary or secondary hoods, but sometimes even tertiary hoods. I vividly recall being told, fifteen or twenty years ago when visiting smelters to promote the application of the Savard-Lee tuyere in nonferrous processes, that implementing sonic injection was not economically viable due to the high cost of compressing air and oxygen. Some of the smelters I visited back then have since mandated their engineering partners to design and build secondary or even tertiary hoods. I cannot fathom how secondary and particularly tertiary hoods, with all of their auxiliary equipment and added ducting, could be more economically viable than purchasing and installing a few compressors, expanding the pipeline network for compressed air and oxygen, and installing a new control valve train to feed sonic tuyeres. Besides, adding hoods does not address the problem of As and SO2-laden fugitive emissions at its source but merely provides a costly mitigation for it by capturing larger volumes of process off-gases rather than reducing these large volumes in the first place. Moreover, hooding does not reduce energy consumption nor does it increase process intensity, two aspects that I believe are critical for smelters to remain competitive and sustainable in a deeply changing market environment.

Jan 1, 2019

By D. Knuutila, G. Goyette, James A. Finch, G. Bartolacci, A. Fortin, Chi Ho Lau, A. Lockhart

"In a COREM-McGill collaborative research and development project, gas dispersion parameters and froth properties were manipulated in a copper flotation plant to study interactions between the collection and the cleaning zones. In this paper, specific work on developing some relationships between operating conditions and froth stability in a rougher column flotation cell of 125 m3 is reported. Froth stability, measured by image analysis, was related to the following process conditions for specific flotation machines in an industrial case study: Gas flow rate, collector dosage, pH, frother type and dosage. Across the range examined, froth stability was improved through a decrease in gas flow rate and/or increasing frother dosage. Metallurgical results (grade and recovery) showed that both gold and copper were dependent on froth stability.INTRODUCTIONMcGill and COREM have over the past two years collaborated in a research and development project to merge gas dispersion parameters, frother analysis (McGill technology), and froth properties (COREM’s imaging system) to study the interactions between the collection zone (pulp) and the cleaning zone (froth). The main goal is to increase knowledge of flotation cell hydrodynamics since it is known to govern the metallurgical performance of the flotation process (Power et al., 2000). In this paper, specific work on developing some relationships between operating conditions and froth stability in a copper flotation circuit is reported.The objective of this work is to study gas dispersion in a large volume flotation column (hydrodynamics) and to measure its impact on the froth. By froth imaging, it is possible to diagnose operational problems on the basis of froth characteristics (Bartolacci et al., 2005a) and consequently, to propose ways of improving process performance by froth analysis (Bartolacci et al., 2005b).Another approach to froth characterization is investigated in this paper. In the same flotation column, a froth stability apparatus (column) was included (Triffet and Cillers, 2004). The mechanical froth stability apparatus is used to link “hard” froth characteristic measurements to “soft” froth characteristic measurements (those obtained by imaging)."

Jan 1, 2008

By André van Wageningen

Long term mine scheduling is one of the most difficult optimization problems. The problem is said to be NP-complete in that the best possible solution cannot be found any quicker than checking all possible permutations and combinations. In current mining operations, it is important to report changes in long term plans as soon and as accurately as possible. Where geological data can change rapidly, such as in narrow vein deposits, the need to quickly identify and optimize different long term alternatives becomes a difficult task and can lead to many permutations of the long term mine plan. The question arises, is the new plan optimal or not? Can the company objectives be met while adhering to operational constraints? Although a number of optimization techniques have been used in the past, many include significant simplifications or fail to produce acceptable results within the required timeframe. Genetic Algorithms (GAs) are among the most promising optimization techniques within operations research. They are based on natural selection and evolution of solutions to complex problems. They have been known to quickly converge within a few percent of the optimal solution by examining only a fraction of the possible permutations. The GA itself contains very little problem specific information and, as such, in this study, has been linked to a discrete-event simulation (DES). The DES is able to evaluate each sequence proposed by the GA and determine the effectiveness and value of each schedule. The DES feeds information regarding the feasibility and quality of the solutions back to the GA during the optimization process. In this paper, GAs and DES are described and the coupling of the two methods is outlined. The GADES module is then used to ?optimize? a narrow vein theoretical case study and the results discussed in a broader mining context.

Oct 1, 2004

By Tapio Leskinen

"l. IntroductionA reliable sampling system is the basis for an on-stream analyzer. This was realized in Outokumpu company when the development work of the Courier 300 On-Stream X-ray analysis system was started. Because Outokumpu Oy is a mining and mineral processing company, its engineers have been able to thoroughly test sampler prototypes in actual operating situations. The sampler development has been going for several years in close co-operation between company's concentrators, the Institute of Physics and the Instrument Division of Outokumpu Oy. The most active part of the work was done between 1969- 1972. Besides the reliable operation of a sampler special attention was paid to the representatively of the samples taken by the samplers. 2. The Courier 300 Sampling SystemThe sampling system comprises up to fourteen sampling circuits in one Courier analysis system. Each circuit consists of the following components:1. Primary sampler 2. Secondary sampler 3. Cleaner screen 4. Feeding tank5. Sample cell6. Timer-controlled sampler7. Pumps, sumps and pipesSecondary samplers, cleaner screen and feeding tanks are included in the secondary sct1npling system. The sample cells are located in the spectrometer cabinet of the analyzer."

Jan 1, 1976

By C. Pelley, A. Piche

"The Canadian mining industry faces the prospects of a severe shortage of graduate mining engineers over the next decade. This arises from three factors: first, a growth in industrial activity; second, the average age of company engineering and management staff; and third, the reduced number of students in engineering faculties around the world. This paper aims to identify the critical factors underlying the trend of inadequate recruitment into higher education for mining and to examine means of alleviating the problem.This paper is based upon surveys of potential and current students and graduate mining engineers from four mining schools. An attempt is made to understand institutional and industrial images, career prospects and what is required to attract enough high-calibre young people into mining education over the next decade.IntroductionThe mining industry has started to experience a severe shortage of graduate mining engineers which is likely to persist and even worsen in the short- to medium-term.This arise s from three principal factors:1. a recent and strong growth in mining activity, which surpasses that experienced through the 70s, before the recent international industrial recession; .2. an increasingly older average age of mine engineering employees, at least in the industry's larger companies; and3. problems associated with maintaining adequate mining undergraduate recruitment levels ."

Jan 1, 1989

By J. Abrahams, A. Nesbitt

Over the past half-century, researchers have commented on the complexities of ion-exchange processes, but have been forced to use gross assumptions to simplify the associated mathematics sufficiently for mathematical models to be of practical use, given the available computational power. This paper reviews the development of increasingly complex models as computational power has increased over the past half-century, from the direct application of Fick's Law in 1947, through to today's models requiring finiteelement methods. The assumptions required for and the associated limitations of the various models are presented and the associated computational complexities are discussed. A case study is presented in which a continuous loss of capacity in an acid resin was observed over about sixty cycles of loading and elution. Resin poisoning does not explain this observation. This paper presents the capacity loss data, speculates on possible causes of the phenomenon, discusses why conventional kinetic and equilibrium mechanisms cannot explain it and concludes that the need to develop a more rigorous model is apparent. The significance of this observation is that standard tests done for a new resin application could significantly overestimate the commercial performance of the resin concerned, highlighting the importance of computer simulation in this field of process engineering.

Jan 1, 2005

By R. Pelton, Z. Dai, S. Yang

ABSTRACT Hydrophobic polystyrene nanoparticles were evaluated as potential flotation collectors for pentlandite. The flotation of hydrophilic glass beads demonstrated the nanoparticles’ ability to induce flotation. Deposition of nanoparticles on glass surfaces increased the contact angle and enhanced adhesion of the beads to air bubbles. High flotation recoveries were achieved when 5–10% of the bead surfaces were covered with nanoparticles. Surface functionalization—the addition of vinylimidazole to polystyrene nanoparticle surfaces—caused the nanoparticles to selectively deposit onto pentlandite surfaces in the presence of Mg-Si slimes. Ongoing work includes attempts to identify specific applications where nanoparticle collectors might be cost effective. _ KEYWORDS Flotation, Nanoparticle collector, Coverage

Jan 1, 2014

By Sergei Decterov, Peter Hayes, Evgueni Jak, Taufiq Hidayat, Denis Shishin

Copper smelter operations around the world are under sustained pressure to reduce costs and increase output. Through the provision of reliable data on fundamental properties of the chemical systems the opportunities for improvements of industrial copper production can be identified. Experimental and modelling studies on phase equilibria, thermodynamics of copper slag/matte/metal/gas systems have been combined into an integrated research program undertaken at PYROSEARCH. Experimental phase equilibria studies involve high temperature equilibration in controlled gas atmospheres, rapid quenching and direct measurement of compositions of equilibrium phases with electron probe X-ray microanalysis (EPMA). Thermodynamic databases development and modelling is undertaken using the computer package FactSage in conjunction with advanced models used for complex solution phases. Progressive development of these research methodologies has brought significant advances in characterisation of these complex systems, including a new optimised thermodynamic database for the copper-containing slag system Cu2O-Al2O3-CaO-FeO-Fe2O3-MgO-S-SiO2.The new data and models can now be applied to assist in improvements of the processes. The effects of changes to chemistry and process conditions within the smelting reactor can be examined. Several examples of new descriptions of the phase chemistry of the Cu2O-CaO-SiO2 and Cu2O-FeO-Fe2O3-SiO2 systems in equilibrium with metallic copper showing calculated and experimental data are presented.

Jan 1, 2014

Brunswick Mine employs an ore and waste pass system for material transfer. This paper reviews the evolution and performance ore pass systems at the mine. It presents the range of selected configurations, inclination, dimensions etc. Select case studies are used to address the influence of structure, stress and materials handling on the longevity of the employed ore passes.

Feb 1, 2008

By R. G. K. Morrison

By arrangement between the Ontario Mining Association and Messrs. John Taylor & Sons, Mining Engineers, 6 Queen Street Place, London, E.C.4, the writer was engaged for a period of not more than three months to report on the rockburst situation in Ontario mines. This was later amplified, by mutual agreement, to include, at the expense of detail, visits to the larger camps where rockbursts had not occurred, to get a general picture of conditions and to discuss the subject with operators in their respective areas. Scope of Activities Visits were paid to the following properties for the purpose of enquiry and discussion; the underground workings of those mines marked with an asterisk were visited on one or more occasions: KIRKLAND LAKE * Macassa Mines, Limited * Kirkland Lake Gold Mining Co., Ltd. * Teck-Hughes Gold Mines, Limited * Lake Shore Mines, Limited * Wright-Hargreaves Mines, Limited Sylvanite Gold Mines, Limited Toburn Gold Mines, Limited EAST KIRKLAND & LARDER LAKE Upper Canada Mines, Limited Chesterville Larder Lake Gold Mtng Co., Ltd. Kerr-Addison Gold Mines, Limited Omega Gold Mines, Limited PORCUPINE * Hollinger Consolidated Gold Mines, Ltd. * Mcintyre Porcupine Mines, Limited * Dome Mines, Limited * Buffalo Ankerite Gold Mines, Limited Paymaster Consolidated Mines, Limited Preston East Dome Mines, Limited Pamour Porcupine Mines, Limited Broulan Porcupine Mines, Limited Hallnor Mines, Limited Naybob Gold Mines, Limited Delnite Mines, Limited Moneta Porcupine Mines, Limited DeSantis Porcupine Mines, Limited Coniaurum Mines, Limited SUDURY lnternational Nickel Co. of Can., Ltd. * Falconbridge Nickel Mines, Limited LITTLE LONG LAC AREA * Little Long Lac Gold Mines, Limited MacLeod-Cockshutt Gold Mines, Ltd. Hard Rock Gold Mines, Limited Bankfield Consolidated Mines, Limited Magnet Consolidated Mines (1936), Ltd. à PICKLE LAKE AREA * Central Patricia Gold Mines, Limited * Pickle Crow Gold Mines, Limited UCHI LAKE * Uchi Gold Mines, Limited McKENZIE ISLAND AREA Gold Eagle Gold Mines, Limited * McKenzie Red Lake Gold Mines, Ltd. * Cochenour Willans Gold Mines, Limited RED LAKE * Howey Gold Mines, Limited Hasaga Gold Mines, Limited Madson Red Lake Gold Mines, Limited

Jan 1, 1942

By Fabien Miller

Automation technologies are increasingly envisaged to improve underground mining productivity. However, the technologies need to be used and adopted gradually in order to get the best benefits. This paper presents the technical and operational aspects of autoguided production vehicles at Brunswick Mine. During 2001 Noranda?s Brunswick Mine has successfully commissioned an automated haulage zone where two optically guided trucks transport ore from a remotely operated chute to two orepasses. Operational advantages include increased system capacity and enhanced safety and comfort for the operator. The data obtained up to now indicate that the system can operate reliably in mine production

May 1, 2002

By Vincent Roy

Numerous on going activities at the Daniel-Johnson Dam : ? Surveillance / monitoring ; ? Structural investigations & evaluation ; ? Injection work ; ? Crack mapping ; ? Instrumentation management (drawings & inventory) ; ? Drainage system state ; ? Foundation evaluation

Aug 1, 2013

By K. Lundholm, M. Andersson, L. Nevatalo, Å. Holmström, L. Hedström

"Several copper deposits have the arsenic bearing minerals enargite (Cu3AsS4) and tennantite (Cu12As4S12). Since this mineral contain both arsenic and copper, it is not possible to remove the arsenic by selective flotation. Partial roasting is a method to clean the concentrate from arsenic and thereby produce a suitable raw material for the copper smelter. Also mercury is commonly found in copper bearing minerals. In the partial roasting process both arsenic and mercury are volatilized, while part of the sulphur is used as energy during the roasting. This gives a calcine suitable as feed to a smelter, much like an ordinary copper concentrate. A typical analysis of calcine would be: S content 18–22%, As content below 0.3%, Cu content – not affected, grain size – not affected. However, if the concentrate contains mercury, the mercury will be volatilized during the roasting process. This will lead to very high mercury contents in the subsequent process of sulphuric acid, unless the SO2-rich process gas is pre-treated by the Boliden/Norzink process that recovers mercury as calomel, Hg2Cl2. The volatilized arsenic in the gas phase can be recovered either by dry or wet methods. However, one problem is that arsenic also contaminates the fine grained calcine dust that is captured downstream in the gas cleaning system. The calcine dust contains valuable metals such as copper, gold and silver that needs to be separated from the arsenic. The ultimate aim is to stabilize the recovered arsenic as a compound with minimum impact on the environment and recover the valuable metals. By using wet recovery methods it is possible to selectively precipitate copper, gold and silver as sulphides while arsenic is kept dissolved in the liquid. The precipitated metal sulphides can be mixed with the calcine and sent to the copper smelter. The dissolved arsenic is sent to effluent treatment and is further treated in Outotec ferric arsenate precipitation process, where arsenic is precipitated as the stable compound basic ferric arsenate, formula FeAsO4·xFe(OH)3. All concentrates containing arsenic are unique and the process design of a roaster plant must be based on relevant process data. The process data is collected during tests in lab scale and pilot scale, where the influence of critical process parameters on the quality of calcine is studied. The ability to run tests both in lab scale and pilot scale is crucial to the development of the correct roasting process. Outotec is well equipped for this."

Jan 1, 2014

By Lawrence Winter

why are these deposits significant? (i) economically and (ii) in a VMS/geological context. ?Significance of the tectonic setting. ?New understanding of the regional geology: volcanic stratigraphy, first geochronologic data. ?Deposit geology: paleomorphologyof the seafloor setting. ?Lessons and conclusions ?Regional Potential

May 1, 2006

By Anna M. Ferrero

Stability condition of underground excavations have to be assessed to guarantee safe operations within the quarrying working areas. This objective requires a reliable assessment of the rock mass natural state of stress and of the stress redistribution induced by the excavations. This goal is often complicated by difficult geological conditions induced by tectonic stresses, complex topographies and large and irregular excavation geometries. Consequently, the acting state of stress needs to be measured by specific in situ measurement devices. This work refers on an in situ measurements campaign carried out by CSIRO tests in an underground quarry located in the Carrara marble basin. The difficult path carried out for interpretation of the measurements is described in this paper. In particular, the numerical modeling performed using the Boundary Element Method (BEM) first, to study the influence of both surface topography and excavation geometry and then the Distinct Element Method (DEM) to evaluate the influence of rock discontinuities in the measurement zone are illustrated in this work. Parametrical analysis of the rock mass mechanical features is also described in order to calibrate the numerical models and analyze the experimental results. The work has been carried out trough several phases, which are: characterization of the rock mass through geostructural surveys: this allowed us to classify the rock mass and determine the mechanical and physical parameters necessary for modeling; on-site measurement of stress levels through the application of over coring techniques; numerical analyses for the simulation of excavation phases, using the Examine3D (BEM) engineering analysis code. comparison between the measured stress levels and those numerically calculated and subsequent calibration of the BEM model; Numerical model of the forecasted excavation based on the calibrated (BEM) model.

May 1, 2009

By Frank van der Meer, Jorge Portocarrero, Alexandra Gruendken

"The number of High Pressure Grinding Rolls (“HPGRs”, also called Roller Press) installations instead of tertiary crushers is rapidly increasing. The technology has been largely accepted in the minerals industry and benefits, such as superior energy efficiency and a lower overall operating cost compared to alternative technologies, have been demonstrated at a number of operations throughout the world.This paper focuses on coarse hard ore operations and reviews the successful installation of the first Roller Press installed instead of a tertiary crusher at the Los Colorados Plant of CMH (Chile) in 1998. It details the experience obtained over the past ten years of operation from commissioning to the present day. It highlights examples of further developments made in the design to improve machine maintainability and availability as well as wear life of the grinding surfaces.A second focus lies on procedures to derive from small scale testing material properties such as wear life, flake formation and strength and their application to industrial size machines to optimize circuit design, especially when Roller Presses are used in closed circuit with screening.INTRODUCTIONRoller Presses (also known as HPGR, High Pressure Grinding Rolls) are considered today state of the art for the preparation of pellet feed. They are also gaining wide acceptance in coarse ore operations. One of the first successful operations in which a roller press was used to replace a conventional tertiary and quaternary crusher is the Los Colorados plant of CMH in Chile.When the Roller Press at Los Colorados was commissioned in 1988, there were 169 Humboldt Wedag roller presses in operation throughout the world. Of these, 14 were installed in the minerals industry. However, these were installed mainly for grinding pellet feed to increase the Blaine value. Up to that time, only three KHD roller presses had been applied for crushing coarse ore in specialized circuits. Moreover, the installation at Los Colorados was the first Roller Press ever to replace a conventional tertiary and quaternary crusher in a hard ore application."

Jan 1, 2009

By J. -C. Sztuke, M. Cao

ABSTRACT The correlations between froth recovery of coal and air recovery were investigated using a hybrid mechanical flotation column. The particle slurry was fed onto the surface of air-water two phase froths to carry out the tests. Froth recovery was taken as the recovery of particles into the froth product, whereas air recovery was determined by the froth height method. The relationships between froth recovery and air recovery were nearly linear, with greater slopes for more hydrophobic particles. Inside the froth phase, the particles were stratified, with hydrophobic particles concentrated in the upper region and hydrophilic particles in the lower region.

Jan 1, 2013