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By R. Wirth, B. Orberger, C. Wagner, A. Tudryn, B. Baptiste, S. Miska, Université Paris-Sud

Banded iron formations (BIFs) comprise complex textures and mineralogy, which result from fluid-rock interactions related to high and low temperature alteration. The initial iron oxy hydroxide mineralogy and associated phases such as carbonates, quartz, apatite and phyllosilicates were transformed leading to an upgrading of these BIFs into the world’s largest source of iron ore. In low-grade BIFs, a large part of the iron is related to micro- and nano- metric iron-bearing inclusions within micrometric quartz and/or carbonates (mainly dolomite). We studied laminated jaspilitic BIF samples from a drill core containing 26.71 wt.% total iron, 0.2 wt.% SiO2, 0.32 wt.% MnO, 15.46 wt.% MgO, 22.32 wt.% CaO, 0.09 wt.% P2O5, < 0.05 wt.% Al2O3, 0.15 wt.% H2O and 34.08 wt.% CO2 (Aguas Claras Mine, Quadrilatero Ferrifero, Brazil). Bright rose coloured dolomite and quartz bands alternate with massive specular hematite bands. Raman spectroscopy, X-ray diffraction and FIB-TEM analyses reveal that the micro- and nanometric inclusions in dolomite are mainly hematite and minor goethite, partly occurring as clusters in voids. Curie Balance analyses were carried out at different heating steps and temperatures on whole rock samples and a synthetic mix of decarbonated sample and pure dolomite. X-ray diffraction on the products of the heating experiments shows that that hematite is stable and new phases: magnesioferrite (MgFe2O4), lime (CaO), periclase (MgO), portlandite (Ca(OH)2) and srebrodoskite (Ca2Fe2O5) were formed between 680°C and 920°C. These finding gives hints to optimizing the beneficiation process, as the presence of hydroxyl ions bearing goethite micro- and nanoinclusions lowers the sintering temperature. Prior separation of coarse hematite and barren dolomite and quartz, followed by lower temperature sintering of the inclusionbearing dolomite/quartz leads to transformations into phases with higher magnetic susceptibilities (such as hematite and magnesioferrite). The entire Fe and Fe/Mg oxide feed (the priorly separated fraction added to the sintered fraction) can then pass through wet-high intensity magnetic separation after crushing.

Jan 1, 2016

By G. S. Hume

Dr. K. A. Clark: No one will doubt the statement of fact that, during drilling operations through the bituminous sand beds in the Mildred-Ruth Lakes area, the core-barrel was found to contain bitumen with minor amounts of sand instead of bituminous sand. But many will doubt the interpretation of this fact as meaning that beds of bitumen occur interstratified with the bituminous sand beds. They will prefer to hold faith in the laws of physics, which deny that sand will float on oil or that fluid under pressure will not flow away through a permeable medium, until it is proved that the appearance of the oil in the core-barrel was not due to circumstances surrounding the drilling of the bituminous sand beds. The implication of the interpretation that sand is floating on oil is clear and it is unacceptable. Bituminous sand is unconsolidated sand more&apos; or less saturated with a viscous oil. It is as difficult to conceive of bituminous sand lying on top of a body of the viscous oil as it is to conceive of unconsolidated sand more or less saturated with water lying on top of a body of water. The only difference between the two concepts is that the oil is viscous whereas the water is fluid. Oil-soaked sand placed on viscous oil would, when released, sink through the oil slowly, whereas water-soaked sand would sink through the water quickly.

Jan 1, 1947

By Robert J. Maron, Mark Fernald, Alex Van der Spek, O’Keefe. Christian, Tim Bailey

"Sonar array-based non-invasive flow measurement technology is becoming an accepted and many times a preferred method of measuring challenging single and multi-phase flows in the mineral processing industry. This fundamental sensor and measurement technology has been extended to two developments that provide new measurement capabilities useful for monitoring and managing slurry flows and pipes.The first development is the non-invasive measurement of real-time velocity profile of slurry flow in horizontal pipes. Multiple non-invasive passive sensors measure localized velocities and are combined to provide a velocity profile measurement. This information can be used to determine the approach and onset of solid deposition on the bottom of the pipe. Having this information in real time can enable operation at lower velocities and/or higher solids concentration while avoiding solids deposition or plugging and its associated operational costs.The second development is the non-invasive measurement of pipe wear on slurry lines. Presently, such measurements are made by hand-held portable ultrasonic thickness gages. The numerous shortfalls associated with the manual method are overcome with a set of permanently or semi-permanently installed transducers clamped onto the outside of the pipe. This ring of sensors contains a series of conformable ultrasonic transducers spaced around the circumference, which are used to measure the thickness of the pipe under their respective locations. Compared to manual methods, this system and approach results in better repeatability and accuracy. It also decreases inspection labor costs and pipe access requirements. The minimal accuracy variations in the presence of varying environmental temperatures will be shown. Trending of pipe wall thicknesses in high wear pipelines will be illustrated. The benefits of significantly improved pipe wear monitoring in hydrotransport lines with abrasive solids, and associated improvement in the ability to insure safe operation and avoidance of costly environmental damage due to leaks caused by pipe wear will be discussed."

Jan 1, 2009

By R. L. Bruening, R. M. Izatt, N. E. Izatt, S. R. Izatt

"Molecular Recognition Technology (MRT) is a simplified, green chemistry process with applications in selective separations of Ni(II), Co(II), and platinum group metals in primary ore beneficiation processes and secondary recovery operations from spent products, scrap, and environmental waste solutions. Simplification in MRT processes is achieved by non-use of solvents, reduced space requirements, and a simple separation system involving columns packed with metal-selective SuperLig® resins. Minimal waste is generated and metal recovery is achieved at 99% levels from g L-1 to <mg L-1 concentrations. MRT systems are attractive technologically and economically compared with solvent extraction, ion exchange, and precipitation separation processes. Commercial examples of MRT use include removal of impurity metals Cd, Cu, Ni. Fe, and Pb to mg L-1 or lower concentration levels from Co streams to produce battery-grade Co. Highly purified Co is required for optimal function of lithium ion rechargeable batteries and superalloys associated with aerospace and gas turbine operations. Impurity metals are recovered for reuse or proper disposal rather than being discarded to landfill. Green chemistry processes, such as MRT, are needed in metal separations going forward into the 21st century to achieve global metal sustainability in processing of native ore and treatment of secondary sources.INTRODUCTION Maximizing efficiencies of metal separations and optimizing metal recovery rates during separation processes are important goals on the road to achieving metal sustainability. Achievement of these goals is consistent with stated principles of green engineering (O'Connor, Zimmerman, Anastas, & Plata, 2016) and green chemistry (Anastas & Eghbali, 2010). Molecular Recognition Technology (MRT) separation processes using SuperLig® resins have a 25-year record of performing competitive, commercial metal separations with metal recovery rates approaching 100% (Izatt, Izatt, Izatt, Krakowiak, & Bruening, 2017). SuperLig® resins are characterized by high selectivities for specific metals over concentration ranges from g L-1 to mg L-1 or lower. MRT systems use no solvents and are simple in design and operation resulting in reduced capital and operating expenses."

Jan 1, 2017

By Stephen L. Chryssoulis

"""Preg-robbing"" of gold by carbonaceous matter during the cyanidation of certain types of carbonaceous gold ores is well documented. Recent studies established that ""preg-robbing"" of gold is not limited to carbonaceous matter. Gold sorbed on the surface of pyrite grains was detected and quantified by TOF-LIMS (Time of Flight Laser Ionization Mass Spectrometry). Crystallites of pyrite from a number of ores from different geological environments have been shown to have gold on their surface apparently sorbed from the ore forming solutions. Surface gold accounts for significant fractions of the gold head assay. Preg-robbing of gold by pyrite from pregnant cyanide solutions was also documented, and accounts for significant losses to tailings. Preventative measures are discussed.1.0 IntroductionThe detection and subsequent quantification of gold sorbed on the surface of pyrite particulates came about during routine determinations of the deportment of gold employing the comprehensive mineralogical approach (Chryssoulis and Cabri, 1990). In some pyritic gold ores it was discovered that the sum of the various forms in which gold ""conventionally"" occurs, was short of the gold assay. The mineralogical procedure used involves the independent determination of each fraction of gold, in other words there is no form of gold which is calculated ""by difference"". The systematic shortfall after having added the forms of gold listed in Table 1 led to the inquiry for the 'missing' gold and its discovery on the surface of pyrite grains, such as crystal facets and fractured surfaces.Preg-robbing of gold by pyrite from pregnant solutions was first described by Lloyd. In his studies, preg-robbing was measured by changes in the solutions/solids gold assays. This paper describes the first application of a direct measurement method for surface gold on pyrite particles from untreated and processed samples, its impact on gold deportment and processing. The advantage of the direct measurement lies in the absence of interference from other forms of gold, leading to more accurate and precise determinations of this unconventional form of gold."

Jan 1, 1997

By David J. Kerr, Robert Mason

"From1927 to1989, the Hornemineproduced53.7 Mt of ore grading 6.1 g/t Au and 2.2% Cu from two large volcanogenic massive sulphide deposits composed primarily of pyrrhotite, pyrite and chalcopyrite. The ore bodies were hosted by a package of chlorite-sericitealtered epiclastic rhyolite tuffs which were deposited in a narrow palaeo-graben located on the flank of a major felsic volcanic centre. M ineralizingfluids percolated upward through the permeable footwall rocks and were further focussed along syn-volcanic, graben-bounding faults. Sulphides were deposited by a process of sub-seafloor replacement of the rhyolite tuffs.Gold-copper-(zinc) mineralization, including ore zones mined between 1985 and 1989 as the REMNOR ore zones, is present throughout the 900 m of felsic volcanic stratigraphy at the Horne. All the deposits were formed by syn-volcanic hydrothermal processes active during felsic volcanism. There is no evidence to indicate that any economic gold mineralization was introduced by a post-volcanic hydrothermal episode.RESUMEDe 1927 a1989, /amineHorneaproduit53.7 Mt de minerai avec une teneur de 6.1 g/t Au et 2.2% Cu provenant de deux grands amas de sulfures massifs volcanogeniques comprenant esentiellement de la pyrrhotite, de la pyrite et de /a chalcopyrite. Ces gites font partie d'une séquence de tufs rhyolitiques epiclastiques chloritises et sericitises qui ont ere déposes dans un paleo-graben étroit situe sur le flanc d' unimportant centre vo/caniquefelsique.Lesfluides mineralises ont circule de bas en haut a travers /es roches perméables sous-jacentes; ils ont été également canalises par les failles syn-volcaniques en bordure du graben. Les sulfures se sont déposes par remplacement des tufs rhyolitiques immédiatement et sous /e plancher océanique.Les zones minéralisées en or et cuivre (±zinc) - y compris celles qui ont ere exploitees au cours de l’opération Remnor (1985-1989) - se retrouvent, sans discontinuité, à travers les roches volcaniques felsiques dont l' epaisseur atteint 900 m. Ces gites se sont formes par le biais d' un processus hydrothermal qui ag issait pendant le volcanisme felsique. II n'y a aucune évidence de minéralisation aurifère d'importance économique qui soit postérieure a l' activité hydrothermale syn-volcanique."

Jan 1, 1990

By Terry Keough

Contents for discussion ?Current liner technology ?Innovation of magnetic products ?Development of magnetic wear liners ?Installation and change out method ?Uses and capabilities ?Internal wear liners ?Summary Vulcanized rubber ?Many of you are familiar with using vulcanized rubber to provide wear protection on mining equipment. For years, this was the standard for most mining equipment, and mines spent a lot of money fabricating and lining steel equipment.

May 1, 2010

By S. A. Vazhnov, A. G. Kalimov, A. A. Potienko

In this paper we describe a mathematical model of the magnetic field and magnetohydrodynamic processes simulation in aluminum reduction cells developed in St. Petersburg State Polytechnic University, Russia. The model includes: (a) calculation of the currents in the busbar system and inside the aluminum cell construction elements including cathode and anode structures, aluminum and electrolyte layers; (b) magnetic field simulation using the integral equation method; ( c) investigation of the magnetohydrodynamic characteristics on the basis of a shallow-water approach. The developed model was used to investigate operational characteristics of the different industrial aluminum cells. Calculated magnetic field distributions and MHD stability parameters were compared with the available experimental information; the comparison demonstrated a reasonably good agreement.

Jan 1, 2006

By Rodrigo Serna-Guerrero, Ted Nuorivaara

"As the demand of raw materials increases in a global scale due to demographic and economical changes, it is necessary to find technological solutions that improve current production processes in an efficient and sustainable manner. The main objective of this preliminary study is to evaluate the properties of foam produced with a cellulose-based molecule as an alterative to commercial frothing agents in flotation operations. There are two potential advantages identified with the use of cellulose-based additives for the proposed application: i) these chemicals can be produced from sustainable sources (i.e., non-edible crops), and ii) cellulose can be functionalized with chemical groups, in order to rationally modify its behaviour. In previous studies dealing with foam stabilization, it has been proposed that some functionalized cellulose species present a self-assembly mechanism at gas-liquid interfaces. Unlike typical surfactant-based frothers, cellulose molecules form networks around the bubbles that act as protective layers to the mechanical stress and to the occurrence of ionic species. This work studied the properties of foams produced in the presence of a partially hydroxylated cellulose molecule (i.e., hydroxypropyl methyl cellulose; HPMC) under various concentrations in a laboratory-scale column. A comparison with a commercial surfactant frother (i.e., Nasfroth 240) is presented, and a rationalization of the behaviour of HPMC in terms of foam properties (i.e., surface tension, bubble size, foam depth) is proposed. INTRODUCTIONThe search for green alternatives to chemicals produced from non-renewable sources has become a topic of major relevance in industry (Choi et al., 2015). As a chemical consuming industry, the mining sector faces now the challenge of adopting new processing technologies and strategies in order to achieve the future demands of sustainability. Evidently, a move towards green chemistry can only take place by identifying substitute molecules offering potential advantages in terms of recovery and grade."

Jan 1, 2016

By Lionel A. York

THE first application of the cementation process took place in the year 1864, according to H. Standish Ball, when a break in the brickwork lining at a depth of 270', in one of the Rhine Preussen pits near Homburg, was sealed by running in milk of cement from the surface by means of a small hand pump. At about the same time Monsieur Portier adopted the method in France for repairing breaks in shaft lining. Figure 1 is descriptive of the Portier system and is of interest when compared with modern practice. During the next thirty years numerous attempts were made to improve the process; the general method used in sinking being to put clown bore holes outside the perimeter of the shaft for the purposes of injection. The cementation process was first recognized as an important as-set to mining in 1896 when Monsieur A. Francois developed his method of boring and injecting inside the shaft below the permanent water level. The Francois cementation process rapidly attained fame on the Continent and many shafts were sunk by its use in France, Belgium and

Jan 1, 1961

By A. R. Turner

AERIAL survey methods have made enormous technical advances and gained new recognition since World War II. Before enlarging on this statement and reviewing some of the uses of aerial survey in industrial development it is important to de-fine what is meant by "aerial survey". The subject will be discussed in the broadest sense and references will be made to the four sections that compose the overall field of surveying operations from the air. These are: 1. Aerial photography and photo-graphic mapping. 2. The use of airborne electronic instruments for geodetic distance measurement and the determination of ground elevations. 3. Airborne geophysical surveying. 4. The extraction of qualitative and quantitative information from aerial photographs through the processes of "reading", analysis and interpretation. Many sciences and techniques are combined in aerial survey operations. The tools of the business include aircraft, finely engineered cameras, elaborate film processing and printing equipment, ground survey instruments, precision stereo-plotting instruments, map -

Jan 1, 1961

By A. A. Beland, R. J. Dawson, S. Shewchuk

"Shovel buckets, scraper blades, dipper teeth, mine car wheels and hammermills are examples of equipment which require routine maintenance due to abrasion. Service life can be extended by the use 0/hard/acing and buildup materials. Mining and milling applications are described and field welding procedures discussed.A high-stress abrasion test used to select hard/acing and buildup materials/or hammers in a hammermill is described in detail. Field tests of the selected alloys confirmed their performance, and maintenance records showed a significant saving in down time and cost.The relationship between the abrasion resistance of the alloys and their hardness, work hardening, composition and microstructure is summarized. IntroductionLarge volumes of ore are handled daily by the mining industry. The abrasive nature of most ores results in extensive wear to both handling and processing equipment. If such wear is neglected it may cause lost production time and also, in extreme cases, require the complete replacement of expensive equipment. The well-planned maintenance of components subject to abrasive wear by means of buildup materials and hard facing can result in substantial economic benefits. Such benefits can , however, only be realized through the correct choice of welding process, consumables and deposition methods available to maintenance personnel. Hardfacing MethodsHardfacing is applied by a variety of methods; the three most widely used being arc welding, oxyfuel gas and thermal spraying. Table 1 summarizes the major processes used within each method. Filler metals in the form of rod, wire or powder are necessary to fulfill the individual requirements of each process. The filler rods are available in the cast form or, in the case of ductile metals or alloys, as wrought rod or tube. All types are supplied bare or flux covered. Wire is supplied in two forms, drawn flux cored and drawn solid. Powder filler metals are available in many metals or alloys; they may be simple mechanical mixtures or prefused and atomized alloys made to a specific size range and shape for optimum results for each applicable process."

Jan 1, 1980

By Bruce Regensburg

As trucks become larger and larger, haul roads take on a more significant role in mining costs and economics. The School of Mining at the University of Alberta has compiled a design manual for haul roads using both empirical and theoretical information. One section of this manual deals with the economics of haul road construction. While many mines look only at the construction costs of haul roads, this paper looks at all associated parameters including construction costs, removal costs, timing, truck productivity and width implications. The authors demonstrate the method to determine the most appropriate quality of road for different road conditions and life spans.

May 1, 2001

By S. J. Prout, J. M. Lang, D. Lascelles, K. Sarinas

"There is a growing demand for ore characterization methods to support metallurgical development programs from a true geometallurgical perspective. Today, there are multiple automated mineral analysis systems on the market, many of which are based on conventional mineral liberation data. However, liberation data can be limited when assessing the floatability of a mineral to predict its recovery as it doesn’t consider the surface area available for collector absorption and bubble attachment; whereas mineral exposure measurements can. Using the First-Order Rate equation to predict the recovery versus time of variously exposed particles, a model has been developed to predict the recovery of copper sulphides at a particular grind size. This model provides the opportunity for the prediction of copper recovery and grade from multiple, small-scale samples. These predicted values can be imported into resource modeling software, and guide the domaining of geometallurgical units within the ore body. Data has been analyzed from various global copper porphyry systems and compared with actual flotation testwork.IntroductionAs part of the development of a mining project, resource estimation primarily focuses on the definition of the quantity and grade of the ore in the deposit; as the project evolves from preliminary economic assessment through to feasibility, the geological model is usually further populated with hardness and recovery data.The CIM Definition Standards (2011) identifies measured mineral resource as the part of a mineral resource for which quantity, grade or quality, densities, shape, and physical characteristics are estimated with confidence sufficient to allow the application of “modifying factors” to support detailed mine planning and final evaluation of the economic viability of the deposit as an asset. The modifying factors include, but are not restricted to, mining, processing, metallurgical, infrastructure, economic, marketing, legal, environmental, social and governmental factors.With market fluctuations, many investors in the mining industry have become more and more risk averse which has increased the demand for more reliable data to support these modifying factors. This has led to the widespread use of geometallurgy and statistical analysis to better inform the resource estimation. Geometallurgy is used to characterize ore variability and is especially useful for highly variable or strongly zoned deposits, several close deposits that will be milled together, projects requiring complex or new metallurgical approaches, brownfields or sight-of-mine exploration, expansion projects that exploit new, deeper or adjacent reserves, and projects with significant legacy drill core that are being re-evaluated due to new economic circumstances."

Jan 1, 2018

By David R. Winfield

I would like to thank you for spending the time with me today to review the FLIR PathFindIR thermal imaging camera system: It is truly an innovative safety system that has the added benefit of offering increased efficiency Our company the Winsted Group, specializes in mobile video systems that are fully customizable to address standard and unique operational requirements in a variety of industries from heavy equipment cameras to police and military digital recording systems, high end video camera systems are a hallmark of Winsted?s product line. The use of thermal imaging camera systems to enhance mobile safety is a relatively new concept as it relates to their use in both transportation and heavy equipment operation. This technology, like so many before it, has been adopted for civilian use from its military roots. The identification of enemy combatants through their heat signature has given our troops a decisive edge in military operations in total darkness Likewise, the ability to discern people and objects that give off heat is a significant step forward in collision and accident avoidance. The PathFindIR camera system that I am demonstrating today is so advanced that it cannot be exported outside of continental North America without a US government approved export license I would like to commence my presentation with a short video clip that discusses the technology associated with the FLIR PathFindIR Thermal Imaging camera systems. The video demonstrates the operational effectiveness of thermal imaging camera systems installed on a vehicle operating on the roadway at night, of course there are definite parallels to use in a mining environment, primarily the fact that lighting is limited and the chance for vision limiting dust is ever present. We are, of course more concerned with personnel safety in our mines than encountering wildlife on the roadside. From the same perspective, the transport driver is just as concerned with encountering a stalled vehicle as our mine truck operators are with other mine traffic.

Feb 1, 2008

By G. F. Liu, S. Owada

Platinum Group Metals (PGMs), Pt, Pd, Rh, have been widely used as a three-way catalyst to clean discharged gas from automobiles and therefore a considerable amount of the spent catalysts is generated annually. This paper proposes a novel concentration technology of PGMs by utilizing the double-deck structure of PGM bearing alumina-ceria and cordierite phases. The applied technologies are a combination of heating-quenching, selective grinding and screening for separating alumina-ceria phase from cordierite. Temperature change as a function of quenching time and the thermal stresses applied to both phases were simulated and calculated by FEM, and it was clarified the mechanism of micro-cracks generation at the phase boundary and micro-cracks in alumina-ceria phase, which indicated that separation of alumina-ceria phase from cordierite and selective breakage of alumina-ceria phase could be achieved in the subsequent selective grinding with an attritor. This process could concentrate 46 wt% of alumina-ceria phase into fine fractions with 86 % recovery efficiency. The remaining alumina-ceria phase can be further recovered by applying flotation and so on.

Jan 1, 2015

By Staff, G. M. Hogg

"The eastern portion of the Late Precambrian geosynclinal structure known as the Labrador Trough comprises a 16,000-square-mile sulphide-bearing belt of good potential as a base metal exploration area. Hollinger and Hanna mining interests have carried on exploration in the region since 1953, with encouraging results. This program has been considerable in terms of both effort and expenditure, and has resulted in an apparently successful primary evaluation of the entire belt.Much detailed work remains to be done in the area. Exploration to date has been largely of a reconnaissance nature, employing various methods in common use in Canada today. In the course of this work, several deposits of promise, containing near-economic quantities of copper, zinc, nickel and other metals, have been located. A broad classification of these deposits is proposed.Exploration in the sulphide belt was started on the basis of partial control of the area under mineral exploration concessions. This was necessary to justify operations in an area of difficult access and high operating costs. The results of this now-terminated arrangement are regarded as being of benefit to those directly concerned as well as to the mineral industry in general."

Jan 1, 1966

By W. Bullen

A hypothetical economic model has been developed for diamond projects in the Canadian Arctic using data from recent exploration and mining projects. The model reflects economic conditions applicable to the diamond mining industry in the Canadian Arctic at the present time. The economic model captures pre-production expenditures, production data, and post-production costs. Before- and after-tax cash flows are derived from the data along with the relevant economic criteria. From the corporate perspective, the model provides guidance concerning the minimum size and/or in situ value per tonne requirements of targets being sought in order to ensure economic success and predict exploration and development expenditures. From the government perspective, the model provides an indication of income and mining tax revenues that can be expected from a particular diamond project. The model shows, on average, diamond projects in the Canadian Arctic are expensive to explore for and develop, but are economically robust under the present conditions. They generate great economic return for mining companies and significant amounts of tax revenue for governments. The fact that diamonds can be transported directly from the minesite by air makes them particularly attractive targets for mining companies that operate in the Canadian Arctic.

Jan 1, 2006

By V. Thangadurai

The critical problems in commercialization of the present solid oxide fuel cells (SOFCs) and useful electrical and physical properties of IT-SOFCs electrolytes are discussed briefly. The conductivity behavior of the perovskite-type and perovskite-related structure metal oxides are summarized. Perovskite-type La0.9Sr0.10ao.8Mgo.203_8 (LSGM) exhibits high ionic conductivity of 0.1 S/cm at 800 °C. In order to improve the electrical conductivity of LSGM and the In analogue of LSGM, substitutions have been made at the A-and B-sites. Substitution of trivalent La3+ by isovalent Pr3+ in LSGM and La09Sro ilno.sMgo.202.85 (LSIM), yield new mixed conductors. Among the investigated compounds in the present study, La0APro.4Sro.21no sMgo.2028 exhibits the highest total electrical conductivity of 3.2 x 10-5 S/cm at 200 °C in air with the lowest activation energy of 0.44 eV (200-700 °C). LSIM and Pr-substituted LSGM and LSIM perovskites show p-type electronic conductivity in the oxygen partial pressure range 10-5 ? 0.21 atm at 750 °C. The perovskite-type solid solution SrSn1-xFex03 exhibits compositionally driven phase transitions. For example, compound of the composition x = 0 to 0.3 crystallizes in an orthorhombic GdFeO3-like perovskite structure, where as that of x = 0.4-0.9 crystallizes in simple cubic SrTiO3-like, and that of x = 1 in orthorhombic structure. The electrical conductivity of SrSn1_xFex03 increases with the increasing Fe content and reaches a value of about 10-1 S/cm at 25 °C in air for x = 1. Compounds with low Fe content exhibit both ionic and electronic conductivity, while the higher Fe content 0.5) perovskites are electronic conductors over a wide range of oxygen partial pressure of 10-22? 0.21 atm at 750 °C.

Jan 1, 2005

By P. Botane, A. Cailleau

"Compagnie Miniere Esperance operates a gold primary ore body. The ore is processed through crushing, grinding and gravity concentration generating tailings with remaining fine gold. Analyses of the tailings proved a residual gold grade sufficient for a chemical treatment.As lab tests proved the technical feasibility of a pre-concentration using flotation, an on-site pilot operation has been carried out to assess the continuous circuit performances, define the best configuration and obtain enough data for the industrial circuit sizing.Data collected during the pilot campaign have been used for calibrating a process simulator built with the USIM™ PAC software. The simulator validated the feasibility of upgrading the existing plant, including the reprocessing of tailings to obtain a good fine gold recovery in a small amount of concentrate. A preliminary capital cost has been achieved to assess the flotation workshop profitability.INTRODUCTIONCompagnie Miniere Esperance (CME), a mining company based in French Guyana, operates a gold primary ore body in open pit. The ore is processed through crushing, grinding and gravity separation in two stages: a top plant and a bottom plant. A “coarse” pond contains tailings of the top plant; this product feeds the bottom plant. Tailings of the bottom plant are stored in the “fine” pond.Analyses of the fine ponds proved a residual gold grade sufficient for a chemical treatment. However, direct cyanidation would require a too large installation, regarding the local conditions (accessibility, supplying and meteorological conditions).It has been then decided to test the feasibility of a pre-concentration using flotation. Lab tests have been carried out by SGS Lakefield (Canada) in March 2007, which proves the technical feasibility."

Jan 1, 2009