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By Chuck Edwards

"Milling operations in northern Saskatchewan’s Athabasca Basin have produced uranium continuously since 1975. Over that period, the Athabasca Basin has been one of the world’s premier uranium camps, yielding more than 660 million lb of U3O8. In this paper, the author describes former and current milling operations and discusses why and how the milling process has changed and developed over the past 35 years. The author’s considerations for the future of uranium extraction in the Athabasca Basin close out the paper.INTRODUCTIONThe roughly oval Athabasca Basin in northern Saskatchewan occupies nearly one third of the surface area of the Saskatchewan Shield. Its sandstone-like deposits lie unconformably on the older basement. The basin hosts many high-grade unconformity-type uranium deposits(Saskatchewan Energy and Resources, 2010) for which the Athabasca Basin is world famous. Uranium production in the Athabasca Basin has come from four mills. In the order of startup these are Rabbit Lake, Cluff Lake, Key Lake and McClean Lake. General data (AREVA, 2010; Cameco, 2010; Denison 2010) for each mill are shown in Table 1."

Jan 1, 2011

By Hal. Oliver

MR.]. G. TRAILL: My only excuse for contributing to the discussion on Mr. Hall's interesting paper is that I had the good fortune to be employed at Noranda during those romantic years, 1927 and 1928, when construction was at its height. The mine was in course of being rapidly prepared and brought into production, and the initial difficulties in crushing-plant and smelter were being met and overcome. They were stirring days, and perhaps those members who were with the second Empire Mining and Metallurgical Congress in 1927 sensed the atmosphere of excitement and activity that prevailed. Early History. Noranda must surely possess some of the most remarkable ore-bodies known to mining men, and the story of their development is pure romance. Ed. Horne's faith in the property, and the persistence of Thomson and Chadbourne, were richly rewarded in the end, but only after some very thin times had been experienced. In those early days access to the district was by the Kenojevis river and various portages to Osisko lake, on the shores of which the mine and smelter and the town of Noranda now stand. But all the early work was done on the Chadbourne claims, more than a mile to the west; through the b~sh. I have read a log of the events of that period, and through the whole tale of hard work, discouraging developments, occasional shortages of food, and constant danger from forest fires, can be read the faith and persistence of the men in charge. The Chadbourne ore was of that well-known type which, though just too low-grade to pay (with gold at $20 per ounce), is yet sufficiently encouraging to lead one on in the hope of striking something better. It was only as a last resort that work on the Chadbourne claims was suspended and a diamond drill brought to the gossan-covered hill beside the lake. The diamond-driller told me his version (it may be exaggerated) of how the position and direction of the first hole were decided on. He was told, "You might as well set up your drill here, and drill in, say, that direction". I believe that the first hole went through the richest ore ever found at Noranda. After the drill had gone through about 150 feet of solid sulphide ore running 17 per cent copper and 4 dwt. of gold per ton, it passed into barren rock, but the diamond-driller expressed the opinion (I wonder how he knew)) that the hole would come into ore again before long.

Jan 1, 1937

By Stephen A. Gasiorowski, Frank J. Hrach, James D. Bittner

Separation Technologies, LLC (ST) has developed a processing system based on triboelectric charging and electrostatic separation that provides the mineral processing industry a means to beneficiate fine materials with an entirely dry technology. The environmentally friendly process can eliminate wet processing and required drying of the final material. The process requires little if any pre-treatment of the material other than grinding and operates at high capacity - up to 40 tonnes per hour by a compact machine. Energy consumption is low, approximately 1 kWh/tonne of material processed. Since the only potential emission of the process is dust, permitting is typically relatively easy. In contrast to the other available electrostatic separation processes that are typically limited to particles greater than 75 µm in size, the ST belt separator is ideally suited for separation of very fine (<1 µm) to moderately coarse (500 µm) materials with very high throughputs. The triboelectric particle charging is effective for a wide range of materials and only requires particle-particle contact. The small gap, high electric field, counter-current flow, vigorous particle-particle agitation and self-cleaning action of the belt on the electrodes are the critical features of the ST separator. The high efficiency multi-stage separation through charging / recharging and internal recycle results in far superior separations and is effective on fine materials that cannot be separated at all by the conventional electrostatic techniques. Since 1995, this triboelectric process has been extensively used for the beneficiation of coal fly ash with eighteen separators in place and over 100 machine-years of operation at locations in North America and Europe. The technology has been also successfully applied to the beneficiation of a variety of minerals including calcium carbonates, talc, and potash.

Jan 1, 2012

By G. Knight

"Results of a program of dust research carried out at the Mines Branch Laboratory, Elliot Lake, indicate that dust-concentration estimates vary greatly, depending on the sampling instrument, the assessment technique and the properties of the dust cloud. The wide range of the ratio between the estimates by any pair of instruments shows that the correlation between the health hazard and dust-concentration estimates by most existing sampling instruments must be questionable. Important studies are being carried out to permit the definition of mine environments in more precise technical terms. The influence of size selection, the physical property measured, composition and sampling period on the assessment of the health hazard are discussed."

Jan 1, 1969

By M. Tardif, F. L. -Lavoie, M. Ruel

"In mineral processing, it is often very difficult to reliably measure several key operation variables. The harsh environment and high temperature encountered in pyrometallurgy processes lead to some difficulties when selecting the instruments, valves and actuators. If an important variable cannot be measured or manipulated adequately, controlling it can really become a big challenge. Sometimes, it is simply impossible to find the perfect equipment for the task. To help overcome these difficulties, a different approach is required. This approach will not correct the inherent problems related to the instruments and valves, but will cope with these problems. This article will demonstrate how modern process control techniques can be used to solve complex problems while remaining easy to implement. In this article we will described how soft sensors and multivariable fuzzy logic control were implemented at Koniambo Nickel to stabilize the furnace feed and allow for safe and reliable operation of an 80 MW DC arc furnace.INTRODUCTION Process Overview The process plant at Koniambo Nickel SAS is located in the North Province of New Caledonia, 310 km north of Noumea. The nickel-bearing ore is mined in the nearby Koniambo massif. After being screened and crushed, the ore is transported to the processing plant using a 12 km conveyor. After stacking in two blending piles, the ore, containing 2.3% nickel, is fed to the processing plant where it will go through the NST process (Nickel Smelting Technology) before being sent to refining and shotting. This article will focus on the improvement to control of the NST processes. The first steps of this process consist of milling the ore and removing all moisture through calcining (Figure 1)."

Jan 1, 2017

By G. E. Rowan

"DURING the dark ages, the cherished dream of chemists was to find a process for converting base metal into gold. Many a wealthy-but-gullible patron lost a fortune in the search. Men who work with metals today are a bit more realistic. I haven't heard of a metallurgist who expects to develop any one alloy that will resist all corrosive media. In the field of stain-less steels, there are about forty different types of alloys that are used where corrosion is a •problem.A stainless product is ordinarily selected because it offers one or more of the following qualities:(1) Resistance to corrosion (2) Resistance to oxidation at high temperatures (3) Good mechanical properties at room temperature (4) Good mechanical properties at high or low temperature (5) Attractive appearance (6) Ease of maintenanceToday we are interested in discussing the stainless steel family of alloys because of their .ability to resist corrosion. We• will not try to explain the Theory of Corrosion. Let us assume that, when surface potential and oxide formations are properly controlled, iron will resist attack in various chemi.cal solutions. The addition of alloying elements to iron does this for stainless steels. The principal stainless alloys used by various Canadian industries are listed in the accompanying Table."

Jan 1, 1959

By N. Schmitt, E. Blond, F. Hild

Working linings of steel ladles progressively damage during the steel manufacturing process due to both severe thermomechanical and chemical stresses. In the framework of the coupling scheme proposed by Blond et al. (1), this study examines the effects of the thermomechanical loading on the onset of microcracking by considering that the complex microstructure of the slag-impregnated brick is fixed during the steelmaking process. The behaviour of the refractory is identified by using thermoelastic-(asymmetric)viscoplastic constitutive equations. Numerical simulations of a simplified geometry of the lining subjected to cyclic thermal loadings at the inner side are shown. Two cases are analysed, namely, i) the material is a homogeneous continuum with a thermoelastic-(asymmetric)viscoplastic behaviour, ii) the material is porous and saturated by liquid slag, and the skeleton has the previous non-linear behaviour. The stress and strain fields are shown, and for the porous medium the interstitial pressure of slag as well. Comparisons between these assumptions are made to assess the role of slag on the degradation of the working lining.

Jan 1, 2004

By W. G. Millar

Until a fire occurs, insurance and prevention work are often looked on as unavoidable necessities, but as insurance is back of all business credit, it is essential to know that in case of damage money will be available to cover the loss; while the interruption of production, often caused by a fire, brings home the realization that if prevention work avoids such an interruption, it is well worth while. Fire insurance is a legal contract guaranteeing the payment of large amounts to an owner, but it is possible there is no other important contract that receives so little consideration. Although previously carried on elsewhere, it is only of recent years that insurance engineering has been actively followed up in Canada, with inspections of an owner&apos;s property carried out for his benefit. Now inspections of this kind are made, advice on fire prevention and protection work ?is available, reports with recommendations with regard to the above are furnished periodically, and with this method applied the owner receives the broadest possible cover and security at the lowest cost. Rates are set by the underwriters by rating schedules which charge for defects in a building and allow credits for protection and other favourable features . These schedules are based on the past record of loss of mining properties as a class, so that a fire in another mining property indirectly affects you, but the amount paid is reduced in proportion as your property is improved. The writer feels, from personal experience, that there is no industry where fire prevention receives more attention than the mining industry, and it is a pleasure to advise that, due to this co-operation, some reduction in the basis rates for mining risks is now being made by the underwriters.

Jan 1, 1928

By G. Cordingley, A. Mwanza

Lumwana is an open pit Copper mine located in the Northwestern Province of Zambia approximately 80 km west from the provincial capital of Solwezi, approximately 300 km northwest from the Copperbelt and 700 km northwest from the national capital of Lusaka. The mine has two major Copper deposits: Malundwe and Chimiwungo. Copper mineralization includes Chalcopyrite, Bornite and Chalcocite. In addition to Copper, these deposits also contain the undesirable element Uranium contained in vein hosted and disseminated Uranite. The processing plant was designed using conventional technologies: semi-autogenous grinding (SAG) and ball mill for grinding, and mechanical cells for rougher and cleaner flotation. Soon after commissioning in early 2009, it was recognised that two stages of conventional cleaning were unable to produce plant final Copper concentrates with the desired Uranium grades. Studies have shown that a significant quantity of liberated and fine Uranium particles (up to 80-90%) is recovered with the concentrate by entrainment. Lumwana Operations sought the use of the Jameson Cell technology after observing successful implementation at other sites in rectifying similar issues. In late 2009, Jameson Cell pilot-plant test work was conducted at the site and this quickly led to the installation of a full-scale B5400/18 model into the existing cleaner circuit. Inclusion of the Jameson Cell resulted in the plant being able to effectively produce clean and saleable concentrate with Uranium contents consistently below acceptable levels. Initially designed to be used as a cleaner scalper cell at the head of the existing conventional cell circuit, subsequent operational issues with the existing recleaner cells forced reconfiguration of the cleaner circuit and reintroduced the Jameson Cell for the recleaning duty. This paper reports the Lumwana Operation from the first two years of operation where it struggled to produce a saleable concentrate with Uranium grades below 150 ppm, which is the maximum allowable limit set out in the smelting contracts, to steps taken in the subsequent years to implement a satisfactory solution. The plant can now consistently produce a clean Copper concentrate with Uranium grades well below 130 ppm and the overall improvements implemented at site have seen the overall plant recovery improve by 1.3%.

Jan 1, 2014

By Robert B. Parsons

"This article is based on a paper presented by Jim Scott at the 1988 annual convention of the Prospectors and Developers Association of Canada. The paper suggests a number of factors that might be taken into account in negotiating royalty terms.IntroductionRoyal ties are a part of mining life in Canada. They are used by many kinds of individuals in many kind s of situations. Prospectors commonly take royalty interests back when they transfer claims to development companies. Mining companies disposing of undeveloped (or sometimes even developed) properties are often paid at least in part by royalties. Royalties are even used by institutional investors with no other connection with the resource industry.Such different royalty holders have different investment goals, different cash flow requirements, and different risk / return preferences. These differences have given rise to a number of different royalty type s. These types range from the simplest cents-per-ton royalty (where the operator pays a royalty at a fixed rate per ton milled) to net smelter return or ""NSR"" royalties (where the royalty is based on a percentage of the operator&apos;s NSR) all the way to net profit interest or ""NPI"" royalties (where the royalty is based on the operator&apos;s bottom-line net profit),The fundamental difference between the many royalty types is in the risk/ return relationship. The cents-per-ton royalty, for example, is relatively risk-free. Of the many economic factors which affect a mine, the only one which will affect the royalty holder is the amount of ore physically milled. On the other hand, the potential for significant gains under a cents-per-ton royalty is also very limited. The royalty holder will not share in any increases in the market price of the end product or any cost reductions achieved by the producer."

Jan 1, 1988

By Robert B. Parsons

"This article is based on a paper presented by Jim Scott at the 1988 annual convention of the Prospectors and Developers Association of Canada. The paper suggests a number of factors that might be taken into account in negotiating royalty terms.IntroductionRoyal ties are a part of mining life in Canada. They are used by many kinds of individuals in many kind s of situations. Prospectors commonly take royalty interests back when they transfer claims to development companies. Mining companies disposing of undeveloped (or sometimes even developed) properties are often paid at least in part by royalties. Royalties are even used by institutional investors with no other connection with the resource industry.Such different royalty holders have different investment goals, different cash flow requirements, and different risk / return preferences. These differences have given rise to a number of different royalty types. These types range from the simplest cents-per-ton royalty (where the operator pays a royalty at a fixed rate per ton milled) to net smelter return or ""NSR"" royalties (where the royalty is based on a percentage of the operator&apos;s NSR) all the way to net profit interest or ""NPI"" royalties (where the royalty is based on the operator&apos;s bottom-line net profit),The fundamental difference between the many royalty types is in the risk / return relationship. The cents-per-ton royalty, for example, is relatively risk-free. Of the many economic factors which affect a mine, the only one which will affect the royalty holder is the amount of ore physically milled. On the other hand, the potential for significant gains under a cents-per-ton royalty is also very limited. The royalty holder will not share in any increases in the market price of the end product or any cost reductions achieved by the producer."

Jan 1, 1989

By Don Langlois, Udo Weber

"The effect of grinding media performance on milling and operational behaviour was demonstrated under different selected milling conditions of calcium carbonate. A variety of grinding media material and bead sizes, along with 2 different stirrer tip speeds, were used in the grinding process to generate a particle size reduction of the calcium carbonate (CaCO3). To determine the optimum milling parameters the collected test data was used to calculate and evaluate specific energy as well as stress intensity under different milling conditions.INTRODUCTIONAs a result of increasing energy costs and raw material prices it is important to look at the efficiency of the manufacturing process. Wet grinding and ultrafine wet grinding in stirred media mills are now a possible cost-effective production step for the processing of industrial minerals and precious metals. The generation of smaller particle sizes (down to micrometer scale) can be advantageous for further production steps – i.e. better liberation of precious metals or improved industrial mineral qualities.In the following, the wet grinding process is investigated under different milling conditions of calcium carbonate. Different grinding media materials varying in specific weight, bead size and stirrer tip speeds are used to determine optimal energy consumption for the milling process.DESCRIPTION OF TEST CONDITIONS AND PARAMETERSMill ParametersTests were performed in a Drais Laboratory Perl Mill PML H/V with an installed electrical motor power of 3 kW. The mill chamber is silicon carbide where as the stirrer and discs are made of yttria stabilised zirconia. The mill working volume is 0.9 l. A screen cartridge with a screen size of 0.2 mm is used to separate the beads and slurry at the outlet of the mill. All tests were performed with a grinding media filling grade of 80% (Mill working volume). The stirrer tip speed was set at 6 m/s and 10 m/s."

Jan 1, 2009

By D. E. Smith, M. K. Murthy

"The commercial potential of a silica-kaolin deposit that occurs on the banks of and close to the Missinaibi River in the District of Cochrane, Ontario, is under evaluation by Algocen Mines Limited. The geological features of the deposit, as well as its probable origin, are described. Mineralogical analysis of the deposit samples indicates that the principal minerals are quartz and kaolinite clay; it is estimated that about 20 per cent of the deposit is kaolin clay. The impurity minerals present are: a slightly magnetic Fe-Ti oxide mineral, goethite, muscovite mica, tour-maline, staurolite, anatase and zircon. Laboratory research studies are in progress to develop and evaluate suit-able methods for the separation of silica sand from kaolin. Results to date indicate that good-quality silica sand with an Fe,03 content in the range of 0.012 to 0.025 per cent can be produced. It appears that the clay portion can also be beneficiated to yield products meeting commercial requirements. It has been possible to beneficiate a portion of theetlay to obtain the particle size distribution now specified by industry. However, research is continuing to develop suitable separation and beneficiation methods which can produce kaolin clay meeting all the commercial requirements."

Jan 1, 1970

By Gobbs C., J. Lam

"The Eagle East project, accessed from the existing and operating Eagle Mine in the Upper Peninsula of Michigan, is an underground base metal project currently in execution by Lundin. This paper will provide an update on several aspects of ventilation including use of a twin-decline access, innovative airflow crossover arrangement and construction ventilation methodology. Integration into existing mine ventilation systems including construction methodology will also be covered. Performance benchmarks and lessons learned are discussed across these topics.INTRODUCTIONLundin has owned and operated the Eagle Mine since 2013. This hard rock underground mine is located in the upper peninsula of Michigan, USA. High-grade nickel ore is mined using sublevel open stoping mining methods and trucked to surface via haul ramp. The mine, having been in production for four years, is nearing the completion of the initial orebody. A satellite orebody 2,000 meters East of the current workings and approximately 900 meters below surface, was identified that could extend operations until 2023. In 2016, Lundin approved the Eagle East project and construction began in 2017 (Lundin Mining Corporation, 2017).Due to proximity to the existing mine, Eagle East will be both accessed and serviced from the existing Eagle Mine. Ventilation at the Eagle Mine uses two fresh air intakes with direct fired combustion heaters; one at the mine portal feeding fresh air into the ramp and one at a fresh air raise located near the Eagle deposit. The primary ventilation circuit is powered on the exhaust air side, with two 700 hp exhaust fans located at a single return air raise. Underground, fresh air is distributed through the main access decline and fresh air raise (FAR) to the production levels and controlled with mechanical regulators on the exhaust side. The exhaust air is collected through return air raises with a collector/transfer drift on 250 Level and then to the surface through a return air raise (RAR)."

Jan 1, 2019

By Brad Hewitt, Jeff Belke

"Murrin Murrin Operations has not had a successful beginning. Numerous reliability and operability issues many of which are the result of design decisions have been addressed through mechanical and operational changes and the CCD circuit is no exception. Four design aspects of the CCD circuit that have caused and continue to cause operational problems are:1. the inclusion of solution neutralisation gypsum in the CCD circuit feed which was designed solely for HPAL residue without proper investigation of its impact on the achievable underflow density and resulting wash efficiency;2. the decision to construct the thickener base from thickened solids;3. the lack of redundancy in the overflow, underflow and tailings pipe work; and4. the lack of thickener operational flexibility in the central rake-lift and feedwell dilution system.In November 2002, the lack of operational flexibility in the rake-lift and the feedwell dilution system through mechanical modification as follows:•, CCD1 has a modified rake mechanism that now allows central vertical lift of 600 mm;•, CCD1 has forced dilution using the Outokumpu Turbodil® technology and replacing the E-Duc® technology of Eimco;The decision to install, the installation and the results of the CCD1 rake-lift mechanism and feedwell dilution system are discussed in this paper. The installation was justified on improved operational robustness and an increase in the in the underflow density of 1 per cent (per cent w/w). At approximately the same time process modifications in the solution neutralisation circuit were implemented and these changes altered the rheology of the slurry reporting to CCD1. Since the modifications to CCD1 and the solution neutralisation circuit, the CCD circuit has averaged a 2 per cent improvement in the circuit underflow density.The CCD1 modification was completed on time and mechanically has performed well. From a risk point of view, the central rake-lift and Turbodil®dilution system add a degree of freedom and robustness to CCD1 operation that has extended the range of operational confidence. In this respect, the modification has been a success and is complementary solution neutralisation improvements."

Jan 1, 2005

By F. Andrieux

"Extruded aluminum profiles are increasingly used for lightweight vehicle construction. Since fracture strains of aluminum profiles are relatively low, damage modeling is crucial for reliable crash simulation. For aluminum profiles, not only the stress state but also the orientation influenced both the deformation and damage behavior. For the material characterization smooth tensile tests were performed in six orientations, both stress-strain curves and r-values were registered. Moreover notched tensile and shear-tension tests were performed in three directions. Finally punch specimens were tested to investigate biaxial loading. Digital image correlation (DIC) analyses were performed to determine local strain values such as critical values at failure. Numerical investigations were conducted with the strain based damage model GISSMO, which is well suited and widely applied for crash simulation. For a strain based failure model the choice of the deformation model is crucial. Deformation models with increasing complexity were investigated to find the best compromise over all experiments. It was found that there is still a great requirement on development of a material model which describes the orientation dependence of the hardening behavior over all stress states in order to be able to use a strain based failure model reliably.INTRODUCTION Weight reduction is an important step for less energy consumption and as a consequence aluminium is increasingly used in automotive parts. An important field of application is the well-established aluminium extrusion which allows the realisation of quite complex shapes of profiles required for an innovative lightweight design with integrated functions. Typical applications are chassis parts, bumpers, crash elements, air bags, etc. Especially the Al–Mg–Si medium strength alloys of the 6000 series can be easily extruded to form complex profiles and prevail for extrusion. Since fracture strains of aluminum profiles are relatively low, damage modeling is crucial for reliable crash simulation. For aluminum profiles not only the influence of the stress state but also the orientation with respect to the extrusion direction have an influence on both the deformation and damage behavior and need to be characterized. The effect of orientation on deformation behavior has been intensively investigated in the last decades and material models haves been proposed (e.g. Barlat & Lian, 1989; Barlat, Lege, & Brem, 1991; Barlat et al., 2003) to describe accurately anisotropic behavior. However it can be noticed that the parameters of anisotropic material models often rely on the yield stress in different directions, which means that the effect of strain hardening is not automatically accounted for. The accuracy of the models at large deformation is not guaranteed and has to be verified. In contrast to deformation models both the characterisation and the modeling of anisotropic damage behavior are not systematically studied. Isotropic failure models based on a critical strain as function of stress triaxiality (ratio of the hydrostatic stress to von Mises equivalent stress) are widely used for crash application (e.g., Bai & Wierzbicki, 2010; Sun, Andrieux & Feucht, 2009; Sun et al., 2013). The mechanisms of failure are manifold and not fully understood; to develop an anisotropic failure model it is mandatory to also have experimental data in different orientations for loading scenarios other than uniaxial tension, e. g. shear, biaxial tension, which implies an extensive experiment plan. This makes the development of failure models more challenging than deformation models for which it is possible to develop a reasonable anisotropic model using the framework of yield function and calibrate the material parameters based on results of tensile tests in different directions. Moreover the development of deformation and failure models are intricate as the variables governing the damage evolution are predicted by the def"

Jan 1, 2018

By Derek E. McBride

"Exploration work in the Beardmore - Tashota area has led to a reinterpretation of relationships between gold mineralization and the geologicalevolution ofthe area. The host volcanic rocks form two parallel volcanic belts connected by a much smaller cross-cutting band, which trends northeast from Beardmore to Tashota. This connecting band consists of mafic and felsic volcanic, plus clastic sedimentary rocks in a sequence conformable with the contact of the Onaman Lake Batholith to the east. A metamorphic aureole or incorporated xenoliths are lacking along this major contact and the only intrusive relationship observed is chilling between mafic dikes and a cold host granite in proximity to it. Granite dikes are totally lacking in the volcanic succession, or the overlying sedimentary sequence. A major part of this sequence consists of a polymict basal conglomerate with granite boulders and volcanic clasts in a fine-grained chloritic matrix. The nearest source for these boulders is the Onaman Lake batholith.Gold mineralization in significant economic quantities (+ 50 000 ounces) occurs at the top or above the mafic volcanic succession as quartz bands. In the Northern Empire Mine, the band is conformable, folded, boudinaged and the mineral zoning shows a relationship to variations in the host rock, not structural overprinting. In general, where the host mafic tuff is medium-grained, the quartz band is thicker, up to a metre wide, and carries economic grade; where the tuff is finer-grained and bedded, the band is very thin and low grade.Stratigraphic control and metal zoning shows that the mineralization formed as part of the development of the volcano- sedimentary succession. The other major deposits in the area (Leitch and Sturgeon River) have a similar structural history suggesting that they are also syngenetic in terms of the stratigraphic development. Regionally, these deposits were emplaced prior to any significant tectonic deformation but at the end of the mafic volcanic event.The mafic activity was related 10 a period ofextension which caused the volcanic troughs to develop along centres of rifting. The hiatus at the end of this event permitted extensive hydrothermal systems to form and deposit siliceous exhalite bands within sedimentary or terminal mafic volcanic environments in promixity to major thermal sources. Subsequently, the Kenoran Orogeny deformed the entire succession into upright folds with a sub-vertical schistosity. Evidence shows that the deposits have remained intact since deposition."

Jan 1, 1987

By J. Bouchard, R. del Villar, A. Vazirizadeh

"Industrial flotation is a continuous and often multistage process, where particles of a given mineral species (usually the targeted one), present in different sizes, encounter a large amount of gas bubbles (normally air) to produce mineral–bubble aggregates, which are removed from the flotation device (cell or column) as a valuable product (concentrate). The bubble content inside the cell is characterized by the prevailing hydrodynamic conditions (known as gas dispersion variables), which in turn are known to influence the flotation performance. Although most researchers and practitioners agree that the relationship between the hydrodynamic variables and flotation performance exists, the lack of an adequate method foronline measuring the average bubble diameter has prevented such studies.The aim of this study is to apply appropriate hydrodynamic variables for flotation kinetic modeling (as a key feature of flotation performance) for a given introduced particle size distribution (PSD). In this regard, experiments were conducted in a laboratory flotation column (5.6 cm internal diameter for a total height of 650 cm), and mixtures of quartz (hydrophilic gangue) and talc (naturally hydrophobic mineral), classified in four different size fractions. The correlation between the flotation rate constant and given hydrodynamic variables were analyzed. Results suggest that the relative importance of hydrodynamic variables for flotation rate modeling depends on the PSD. Finally the suggested hydrodynamic variables for each of the various particle size-classes considered were used to produce single variable models for the flotation rate constant. INTRODUCTIONIndependently of the prevailing flotation conditions, the mechanisms for bubble-particle aggregation and the residence time of the phases inside the device must also be considered. In this regard, one of the most used approaches to represent the overall flotation process is as a pseudo-chemical reaction between a particle and a bubble, whose rate (at a given time) is proportional to the amount of remaining floatable species. The proportionating constant is called the kinetic constant or the flotation rate constant."

Jan 1, 2016

By M. Fujikawa

The Kamioka Zinc Smelter was converted from the jarosite process to the goethite process in the year 2000. The reasons for the conversion of the process were that the silica content of the raw material increased and the iron content decreased. The silica easily turns to a gel in sulfuric acid solutions and this causes the solid-liquid separation characteristics to deteriorate. The basic behavior of silica in sulfuric acid solution was investigated and it was found that the goethite process is the most suitable to effectively separate and remove silica from solution. Furthermore, Fe has the capability to remove elements such as Ge that have an adverse effect on zinc electrolysis. This means that, when the Fe content of the raw material decreased, the impurity removal capability also decreased and there was a risk of a build-up of impurities in the process. Iron precipitates in many forms in sulfuric acid solutions. The capability to remove elements such as Ge differs depending on the compound precipitated. Goethite has a higher capability than jarosite to remove elements such as Ge. In this report, the results of applying the process established by investigations of the basic behavior of Fe, silica and Ge in the zinc refining plant are presented.

Jan 1, 2006

By Samuel Nunoo

Gibraltar Mine is an open pit copper-molybdenum mine in central British Columbia. The stability and potential failure modes of pit walls in the Granite Pit are controlled by the orientations of joints and faults. The structural geology also has an impact on as-mined bench geometries. Geotechnical mapping and surveying were conducted using stereo photographs and photogrammetry software. Detailed digital terrain models were constructed to determine the pit wall geometry and the locations and orientations of larger structural features. The pit wall geometry is compared to conventional survey results and the mapped structures are compared to results from a nearby geotechnical borehole.

Aug 1, 2013