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By P. Keating, J. Goutier, J. Ayer

"New, high-resolution geophysical surveys were undertaken over parts of the Abitibi Subprovince, Canada, to help with geological mapping and to promote mineral exploration. Gravity surveys in the Rouyn-Noranda and Matagami areas (Québec) allowed better 3-D mapping of important geological structures, and a multiscale edge analysis of ground gravity data over the Blake River Group confirms that major faults behave at depth as predicted by surface geology. Airborne gravimetry west of Matagami (Québec) helped to identify a new trend south of Lake Grasset that is almost perpendicular to the assumed geological trend of the area. Electromagnetic (EM) surveys, flown in the Chibougamau (Québec) and Bartlett Dome (Ontario) areas, allowed new conductors to be identified at greater depths than were achievable with previously used EM systems. Airborne magnetic surveys were flown in the Burntbush area (Ontario), and other available high-resolution magnetic data were compiled to produce a continuous and homogenous magnetic grid of the Abitibi region.The resulting compilation map clearly shows the locations of dikes, faults, and shears zones, and reveals some fault extensions in areas of extensive overburden. This grid also allows the computation of enhanced maps, such as vertical derivative and tilt maps (e.g., a tilt map shows subtle magnetic features in the Blake River Group that are difficult to see in the total magnetic field or its first derivative). Results from these new surveys show there is considerable value in (1) resurveying areas covered by older surveys, and (2) recompiling data sets from these older surveys."

Jan 1, 2012

By Fidelis T. Suorineni

The Ashanti mine, located in Obusai, Ghana, West Africa, has been in production for over 100 years, and is currently the second largest single gold producer in Africa. The mine covers a concession area of 434 square kilometers with four main ore types: the quartz vein type, disseminated sulphide type, supergene sulphides and transition ore, and granitoids stock works (visible gold and quartz veinlets). Various mining strategies and methods have been employed for the mining of the narrow-vein ore at Ashanti. In recent years, the mine owner: Ashanti Goldfields Company Ltd. has embarked on a mine-wide expansion program to boost production to a target of one million ounces per annum. With the rapid depletion of its high-grade ore, a suitable mining method was required to produce a high tonnage at low cost to meet production objectives. This paper discusses how the Ashanti mine applied Canada experiences in mining technology to boost production, and the impact that the differing geological settings between the two countries had on the stope performance at the Ashanti operations. Experience developed at the Ashanti mine led to innovative modifications for stope layout and design methods in relatively poor ground conditions.

Oct 1, 2001

By J. O. Marsden

Over the past decade, the copper industry has been through an extended downturn followed by several years of sustained high copper price. A number of new technologies have been developed over the past 10 years aimed at reducing costs by decreasing energy, labor, and materials requirements, or by increasing metal recovery. The energy intensity of different copper extraction routes and different technologies varies considerably and this has a significant impact on the economics of extraction. Based on average ore grade materials, the total energy for the extraction of copper typically varies from about 24-26 MJ/lb (6.7-7.2 kWh/lb) for the mining, crushing, milling, flotation, smelting and refining route to about 14¬16 MJ/lb (3.9-4.5 kWh/lb) for the mining, crushing, heap leaching, solution extraction and electrowinning route. New technology developments are providing opportunities for significant reductions in energy consumption for copper extraction, representing energy savings up to 20-25% in some cases. In addition, in many cases, these new technologies have introduced environmental, safety and health benefits over the incumbent technology. Some of these technology developments have been more successful than others, and many hold great promise for application in the coming decade. This paper provides an overview of the technology developments that have occurred, and explores the underlying reasons behind successful implementation.

Jan 1, 2007

By R. Lasmanis

"Washington State's diverse geological setting is reflected by its several types of porphyry Cu-Mo deposits. All are associated with calc-alkaline intrusions, and they range in age from Jurassic to Miocene.The largest is the Mount Tolman Mo-Cu deposit located in the Omineca Belt. It contains 2.18 billion tonnes of material averaging 0.093% MoS2 and 0.09% Cu. There are intermediate-size Mesozoic deposits in the Intermontane Belt. The Cascade volcanic arc hosts small- to medium-Tertiary deposits. Among these, of particular interest is the Sunrise breccia pipe, which has been explored over a vertical distance of 1000 m. It contains reserves of 64.6 million tonnes averaging 0.319% Cu and 0.071% MoS2 with significant tungsten values. The Glacier Peak deposits have potential resources of 1.7 billion tonnes averaging 0.334% Cu and more than 0.015% MoS2 and also contain tungsten. The Margaret deposit can be classified as a porphyry Cu-Au type; it has reserves of 200 million tonnes averaging 0.434% Cu, 0.0175% MoS2> 0.27 g!t Au and 1.92 g!t Ag. Drill intercepts of the North Fork deposit also show significant gold values.Mineralization and hydrothermal alteration of these deposits are typical of porphyry deposits, although some differences can be noted. The Mount Tolman molybdenum deposit contains topaz alteration zones and is transitional between a plutonic type and a Climax-type molybdenum system. Other deposits, such as the Kelsey, Mazama, North Fork, and Margaret, are low-sulphide systems that contain significant amounts of magnetite."

Jan 1, 1995

By K. Schrijver, G. Beaudoin

"Four occurrences of galena-cemented sandstones, exposed in the Lower St. Lawrence - Gaspésie area, are described. They constitute a new, insufficiently explored type of deposit in Quebec.One mineralized body, a minor occurrence, is hosted in Lower Devonian rocks deposited in an estuarine, intertidal river channel during a marine regression; major cements are dolomite and sulphides. Another occurrence, a drilled prospect, is hosted in Upper Silurian rocks deposited unconformably on Cambro Ordovician basement during a marine transgression. With galena and quartz as main cementing minerals, it is similar to some well-known, economic sandstone-lead deposits. A third and fourth, a drilled prospect and a minor occurrence, are hosted in Upper Cambrian rocks deposited on continental slopes. In both, sulphides mainly occupy a secondary porosity. The differences between the third and fourth occurrences are: (1) cementing translucent minerals (carbonates and barite in one; chlorite in the other); (2) chronology of final subsurface dissolution (prior and subsequent to sulphide precipitation, respectively); and (3) important fracture porosity only in the barite-bearing deposit.The diversity of the four occurrences, and the unequal geological knowledge of their respective features, prohibit the formulation of uniform guidelines for further exploration.IntroductionThe attention of the mineral exploration community is drawn to four occurrences of galena-cemented sandstones (Fig. 2A) in the Cambrian of the Taconian Orogen and in the Siluro-Devonian basin of the Lower St. Lawrence and Gaspésie area (Fig. 1). In view of the fact that sandstone-lead deposits (Bjerlykke and Sangster, 1981) are, or have been, mined in several countries (e.g . Laisvall in Sweden: see Rickard et al., 1979; Largentiere in France: see Foglierini et al., 1980), the mere presence of occurrences in Quebec indicates that the mineral potential of some parts of the Appalachians requires further evaluation.Exploration for the deposits considered here is essentially restricted to geological methods and drilJing (e.g . Mainguet Suares and Samama, 1969), since the response to geophysical methods is virtually nil, at least in the initial, surficial stage of an exploration program. As the particular disciplines of geology utilized in exploration depend a great deal on the geological setting of a mineral occurrence, the diversity of the Quebec deposits is of prime importance. Therefore, the four occurrences (Fig. I, Table 1) studied by the authors are herein briefly described with emphasis on their stratigraphic and tectonic setting, and on the evolution of pore space and sequential occlusion of pores and fractures. Prior to further research in and around the occurrences, now in progress (e.g. Beaudoin, 1987; Beaudoin et al., 1987), it is hoped that the following outline will be useful to the explorationist."

Jan 1, 1987

By Rayleen Riske

Why do we look for better reconciliation when times get tough? Why wait? Mine reconciliation should be a priority throughout the good times too. In fact, with good reconciliation, those good times are going to be even better and will help pave the way to success through those preventable bad times. Reconciliation throughout the entire mining value chain requires the capture, validation, and analysis of copious amounts of data. This task can be daunting for a team in a small mine, let alone reconciling across a suite of large mines. This paper will outline the different ways we can reconcile across the value chain, why we should reconcile over differing periods of time and how Snowden?s solution to proving reconciliation can be a simpler, reliable and transparent process. Snowden?s Reconcilor is proving to be a valuable tool on any mining scale, by capturing, validating, sorting and reporting data for timely decision making by the site geologist through to corporate management. By instigating vigorous reconciliation, you are setting your mine up for the future. Not only will you have the means to analyse your current processes and measures, but you will have the opportunity to identify and improve your mine?s performance from the resource model through to the final product.

May 1, 2010

By Gema Ribeiro Olivo

The hydrothermal Au-Pd deposits are hosted by the jacutinga in the Lake Superior-type iron-formation of the Itabira Group, Minas Supergroup. Jacutinga is a highly sheared, metamorphosed, hydrothermally altered iron-formation composed of hematite, magnetite, quartz, talc and phlogopite (Cauê) or muscovite (Conceição) and minor tourmaline, palladian gold, arsenopalladinite, mertierite II and palladeisite (hydrothermal) and native gold, native palladium Pd-Cu-oxides, and kaolinite (weathering products). The highest concentrations of Pd-Au occur in quartz and hematite veins parallel to the S1 foliation (Corpo Y, CorpoX, Aba Leste and Central orebodies, at Cauê and a single orebody at Conceição) or parallel to the S2 foliation (Aba Norte). The average ore grade is 30-40 g/t Au+Pd. The characteristics of the Au-Pd ore favor an epigenetic model for gold and palladium concentration in the iron-formation. During the D1 deformation and peak metamorphism, the oxiziding, acid and hot hydrothermal fluids transported Au and Pd preferentially as chloride complexes. The reaction of the fluid with the dolomitic carbonate (the probably protolith of the jacutinga) would have dissolved carbonate and K-feldspar to form muscovite or phlogopite and tourmaline, resulting in an increase in solution pH and a decrease of Cl concentration and subsequent deposition of gold and palladium minerals.

May 1, 2003

By B. G. Cousins, B. O’Rourke, C. Spence

"Some non-flotation chemistries are added to flotation circuits directly and indirectly to control issues such as scaling and dust. Since the dosage levels are generally not very large, a standard laboratory float test may not be able to determine the effect a specific chemical has on the productivity of the flotation circuit. Hudbay and Ashland Water Technologies developed a laboratory testing protocol that uses kinetic float studies to test the effect of normal to extreme doses of antiscalant and dust chemistries (5 ppm to 500 ppm). Laboratory results indicate that this protocol helps to predict the potential interference that a particular chemistry will have on the flotation circuit.INTRODUCTIONFrom a chemical perspective, flotation is a very complex system involving more than the reagents used for flotation. Along with collectors, frothers, modifiers, suppressants and activators, there can be antiscalants for water treatment, dust suppressants used in the mining process, residual flocculants from recycled thickener overflows, grinding aids, and many other types of chemicals that are added upstream of a flotation circuit. Although these other chemicals are usually used at very low doses, it is important to know if they affect the flotation process detrimentally in the event of a spill or a build up from recycled water.Laboratory flotation testing of these chemicals characterizes their effects, but testing at expected doses in the float can mask the effects of the chemicals in the plant. Also, simple tests that do not measure the kinetics of flotation do not reveal the effects the other chemicals have on the flotation circuit. Thus, a new flotation protocol was needed to expose the full effects of chemical additives and to assist in choosing the chemical with the lowest potential for a negative effect.FLOTATION KINETICSMeasuring recovery kinetics in a laboratory flotation cell is a well-established procedure: analyzing concentrates taken in a timed sequence to determine the recovery rate of individual cells in a flotation circuit. The recovery from the early flotation cells are a true measurement of how well a flotation chemical is performing. The principles of kinetics can be mathematically determined by the following functions (Houston, 2006):"

Jan 1, 2013

By D. M. Doyle

"In this paper I will summarized the Falconbridge Nickel Mines1) energy costs and consumption data by fuel, process, cost centre and estimate our future costs and consumption patterns 2) detail the distribution of electrical energy 3) distribution of other forms of energy 4) describe present and planned energy conservation schemes; and 5) discuss economic justification and responsibility.There is sufficient material in this presentation to warrant several technical papers, however we felt that an overview of all our data and endeavors on the subject, would be most beneficial to those companies formulating energy conservation plans. The data briefly referred to in this slide presentation can be found in the technical paper.Over a five year period, total energy costs will vary between $63 and $94 MM depending on the future rate of energy cost escalation. An unrealistic 32% reduction in energy consumption is required to hold our own in the years ahead whereas an attainable 10°;, reduction in energy consumption would save $9 MM over this five year period.Total energy consumption, tonnage of ore delivered to plants and their ration BTU’s per ton of ore, are graphed for the years 1973 through 1976 and forecasted for the 1980’s. In 1974 we along with other member companies of the Mining Association, determined our purchased energy per ton consumption rate and set, as our goal, a 20% reduction by 1980. The dotted lines calculated from the energy audit, based on 1976 data shows there is a potential for a 10% increase in energy per ton. This could result from a lower than forecasted mining rate and operation of the new roasting, electric furnace and acid recovery facilities installed for environmental considerations at designed capacity."

Jan 1, 1978

By V. Dinesen

"Grinding is simply the function of reducing particles in size or creating new surface areas. This may be accomplished by many means but we will only concern ourselves with the continuous grinding process as performed in a revolving drum or mill, containing a grinding media. Such a mill consists essentially of a feed head, a cylindrical shell section and a discharge head. To prevent internal wear of these parts it is customary to attach replaceable linings over the wear areas. The specification and design of these mill liners is more important than generally conceded. As they reduce the effective internal volume of the mill, they will consequently affect the whole mill ·design and operation.A number of mill designs of various sizes are available for combined crushing and grinding of materials within a wide size range. For simplif1cahon purposes we will refer 1n particular to conditions relating to standard mill shapes having a length which is greater than the diameter. Such mills usually rotate at speeds between 60% to 85% of the critical speed and may, depending on the grinding media used, be classified as rod mills, ball mills and pebble mills.LINER MATERIALSA great variety of materials have been and are being used for mill linings. These include wood, ceramics and cements, rubber and plastic compounds, rolled and forged steels, cast steels and cast irons, both plain, alloyed and specially treated.The choice of a liner material depends on many factors. In both dry and \\.:et grinding, it may be necessary to consider product purity, colour, chemical reaction etc. but for our purpose we \viii refer to wet grinding operations as generally used within the mining industry."

Jan 1, 1972

By D. Schleiss

Reduced access to knowledgeable workers is creating challenges for operations. We are doing more 4D Operations - dirty, dull, dangerous, and distant. Personnel costs in these environments are high, and it is not always possible to get the people where you need them. Integrated Operations is a strategy to integrate people, process, and technology for faster and better decision making. Adopting an integrated operations approach can help to relocate personnel, improve collaboration, and align objectives to deliver reduced costs and improved performance. In this paper, the authors will highlight the required infrastructure to enable an Integrated Operations platform. Key decision points for enabling this technology for both Greenfield projects and existing mines will be discussed. Furthermore, the benefits and improved return on investment that result from deployment of an Integrated Operations strategy will be presented.

Jan 1, 2014

By Derek H. C. Wilton, David T. W. Evans

"Abstract - The Midas Pond gold prospect, central Newfoundland, is hosted by sheared and altered felsic and mafic pyroclastic rocks of the Tulks Hill volcanics, Victoria Lake Group, and has been trenched and tested by 19 diamond-drill holes. Gold values are sporadic, with the best diamond-drill intersection assaying 7.3 g/t over 0.9 m, and the highest grade channel sample containing 14.7 g/t over 1.15 m. Alteration and mineralization are confined to a 200 m wide brittle-ductile shear zone. This shear zone formed in response to regional D1 deformation, and the shear zone fabric parallels the regional S1 foliation. D2 deformation resulted in broad Z-shaped flexuring of the shear zone. The deformation was probably related to the ca. 396 Ma to 420 Ma Salinic Orogeny.Advanced argillic alteration and an extensive halo of Fe-carbonate and pyrite surround the gold mineralization. Alteration minerals include pyrophyllite, paragonite, quartz, plagioclase, chlorite, fluorite, Fe-carbonate, and pyrite. As such, the alteration seems to reflect combined epithermal (argillic) and mesothermal (carbonate) mineralizing environments. The argillic alteration and fluorite represent a regional hydrothermal effect on the felsic volcanic rocks; whereas, the Fe-carbonate and pyrite represent a mesothermal alteration associated with auriferous quartz veins. The Au, which is spatially associated with pyrite, occurs in three structurally-controlled vein sets. These veins are confined to the contact between a highly deformed breccia (the banded mafic tuff) and structurally overlying, altered felsic tuffaceous rocks. The vein sets include: V1 boudinage veins that parallel the shear-zone fabric (C-shear veins), and V2 and V3 extensional fracture veins which are controlled by an S2 fracture cleavage. V1 veins are the earliest and contain the lowest concentrations of Au. V2 and V3 veins are concentrated within the hinges of the D2 flexures.Pb isotope data for galena separates indicate that the Pb in the vein systems was probably of local derivation. Sulfur, C, and O isotope data for mineral separates are similar to data for typical mesothermal lode gold deposits. Fluid inclusion data suggest the presence of at least three hydrothermal fluid types in the region, viz., (1) an early saline fluid which produced the argillic alteration, (2) a CO2-bearing fluid directly related to the auriferous mineralization, and (3) H2O-NaCl fluids which flowed through the Midas Pond shear zone at a lateral distance from the zone of mineralization. The mineralizing fluids are interpreted to have been CO3 -2-rich types which originated through metamorphic dehydration and decarbonation of mixed island-arc and continental crustal rocks. Gold precipitation resulted from the reaction of these fluids with the Fe-rich breccia unit. Pre-existing and simultaneously crystallizing pyrite served as loci for Au precipitation."

Jan 1, 2000

By Alain Dorval

"''Purification of marine sands from Les Iles-de-la-Madeleine''This paper presents the results of the work that has been done at CRM pilot plant for «Les Silices du Golfe Inc.». Essentially the purpose of this piloting was to demonstrate, on a semi-industrial scale, the process of purification of marine sands from Les Iles-de-la-Madeleine; that had been developed by CRM Process Development Service. This purification is necessary to produce silica suitable for the glass sand and the foundry sand markets.Introduction«Les Silices du Golfe Inc.» is a company who intends to dredge marine sands around the «Les Iles-de-la-Madeleine» coasts. The material will be transported to Gaspesia where electricity, water supply, and a convenient site is available to treat it. A high purity silica intended for glass sand and foundry sand markets will be produced. The objectives of this purification process are to remove organics, calcium, feldspars and iron.Material ReceivedCRM received 50 tons of sand with Si02 varying between 80,6 and 99,3 % (see Figure.1). The highest variations in impurities were the calcium and lost on ignition. We notice direct relation between% SiO2, % CaO and % L.O.I. as you can see on the following Figures 2, 3 and 4."

Jan 1, 1994

Ion Exchange is finding a greater role in copper processing, and hydrometallurgy in general, both as a technique for removing impurities and as a means of adding value through the recovery of secondary metals. Both the gold and uranium industries use resin adsorption as a primary production technique. While hydrometallurgical processes predominantly rely on solvent extraction as the mainstay of copper recovery there are a number of projects, in particular polymetallic deposits, which are considering the use of resin recovery as an alternative or supplemental production technique. A number of applications have been developed and proven at commercial scale for the removal/control of impurities (iron, antimony and bismuth) from copper electrolytes. These are well documented ion exchange applications. Increasing metal values and scarcity of certain metals are focusing companies to look at secondary metals recovery rather than losing these often highly valuable metals to tails residues. Bleed streams are being seen as valuable opportunities to recover contained metals; iron, copper, nickel, cobalt, bismuth, antimony and rhenium are all metals being targeted for removal or recovery from process solutions, electrolytes and bleed streams. An overview of currently applied techniques as well as some developmental technologies for impurity removal and secondary metals recovery is presented to provide insight into the advantages and flexibility of ion exchange applications in metals processing.

Jan 1, 2007

By P. Kolodziejczyk

Mining seismicity can be harmful both under and on the surface. ? Tremors are not totally damaging, but destructive to buildings and infrastructure, especially in highly urbanized regions, such as Upper Silesia in Poland ? Destroy the social appreciation, trust and support for mining industry ? To prevent or reduce these effects, engineers and scientists develop methods allowing prediction of ground shaking intensity near buildings and various losses that can result from it Evaluation and prediction of mining tremor?s damaging influence on buildings is usually solved with two steps: ? Estimation of local ground shaking intensity (based on known attenuation relation) and classification into one of several predefined intensity intervals ? Apply supposed relation between the shaking intensity interval and qualitatively defined damaging effects to express predicted effects This makes a mixed quantitative/qualitative procedure, difficult to analyze or optimize

Aug 1, 2013

By R. Le Houillier, M. Nagamori, A. J. Plumpton

"Asbestos tailings are a typical serpentine, hydrated magnesium silicate, consisting primarily of antigorite and a few per cent of unrecovered fibrous chrysotile. Serpentine has unique thermal properties in that dehydroxylating calcination at 600 to 700°C can yield an amorphous structure in which most of the magnesia is liberated from the original bond with silica and thereby rendered chemically active. The amount of activated magnesia can be quantified by selective leaching with a weak acid such as acetic acid. Many wet processes have been proposed to extract magnesium values from calcined or natural serpentine by means of various acids and their ammonium salts. However, the only commercial utilization of serpentine today is found in dry processes such as the production of fused magnesium phosphate fertilizer .The present paper reviews the physical chemistry of the dehydroxylation of serpentine and also various wet and dry processes in order to provide a general view regarding the chemical transformation of asbestos tailings.IntroductionAsbestos fibers occur as chrysotile, a serpentine polymorph. More than nine tenths of mined asbestos ores consist of massive non-fibrous serpentine, primarily the polymorph antigorite, which is discarded as tailings after fiber extraction. For many decades, Quebec has been a world leader in the production of asbestos fibers. As a result, colossal tonnages of serpentine have accumulated in the Eastern Townships'!'. Serpentine minerals are found in large deposit s throughout the world, and significant research efforts have been made, particularly in Japan and the USSR, mostly in attempts to extract magnesia or silica values therefrom.The chemical composition of serpentine (chrysotile and antigorite) may be ideally expressed as Mg3Si2Os(OH). which corresponds to 43.7% MgO and 43.3% SiO2. Natural serpentines often contain a few per cent of Ni-bearing magnetite and other impurities, and therefore the contents of MgO and Si02are both about 40% or lower.Serpentine (hydrated magnesium silicate) is virtually insoluble in weak acids. However, when dehydroxylated under controlled conditions, ' it decomposes to an amorphous state in which magnesia and silica are isolated and chemically active. The magnesia so activated is readily soluble in weak acids. This unique characteristic of calcined serpentine, first discovered in 1942,, has since attracted the attention of innumerable researchers, whence many processes have been proposed."

Jan 1, 1980

By W. Pawlak, J. Janiak, C. Rodkiewicz, B. Ignasiak

"There is a general consensus that, in order to widen the utilization of Western Canadian coals, a major effort must be devoted to their transportation, utilization of fines, beneficiation and mining techniques. It is postulated that the concept studied extensively over the last four years at Alberta Research Council (ARC), and based on a combination of hydraulic mining, selective agglomeration with bitumen and/ or heavy oil, pipeline transportation and oil recovery from agglomerates, offers a particularly attractive solution to the problems associated with extraction, beneficiation, transportation and utilization of Western bituminous and subbituminous coals. Results of preliminary experimental work on the feasibility of pipeline agglomeration of metallurgical coal and hydraulic transportation of agglomerates are presented and discussed in the context of conventional agglomeration techniques in stirred tanks. IntroductionAlberta is endowed with enormous reserves of low-sulphur coals which could attract considerable attention of potential customers, but the remote location of this province handicaps its competitiveness on the world market. It is known that Alberta's Cretaceous, particularly metallurgical, coals differ significantly from their Carboniferous counterparts; current R&D work on indigenous coals should continue to expand in order to encourage overseas client s to use these coals more extensively.There is a genera l consensus that, in order to widen the utilization of Western coals, a major effort must be devoted to their transportation, utilization of fines, beneficiation and mining techniques."

Jan 1, 1986

By C. Bazin, D. Hodouin

"A flexible model involving perfect mixers, stagnant zones, plug flow, material bypassing and recycling zones has been developed for interpreting mixing phenomena in mineral processes. The mixing properties are described by the residence time distributions which can be subsequently interpreted by the flexible model. User-friendly computer programs (for 1MB-PC or compatible) have been developed for simulation and modelling of RTDs using the proposed model. Seven mineral processing case studies are discussed in terms of experimental procedure, model calibration results and application of the estimated mixing model to process modelling, diagnosis, and performance evaluation. IntroductionIn any mineral processing plant there are continuous-flow machines that transform or separate the ore components. Grinding mills, flotation cells, conditioning and leaching tanks are examples of such machines. The performances of these vessels or reactors are controlled by the rate at which the reaction proceeds and the time spent in the environment where the reaction occurs. This paper deals with the latter aspect of mineral processes operation.Since most of the reactions occurring in mineral processing units are time dependent, knowledge of the residence time of the material in process vessels is important for modelling and diagnosis purposes. Due to the random mixing phenomena involved in the process equipment, there is a distribution of the residence time of the ore particles and the fluid in the vessel. The probability density function E(t) that a micro-element of the material flowing through a processing unit stays a time t in the vessel, is the residence time distribution (RTD) of the corresponding component."

Jan 1, 1988

By A. Dunnett, N. J. Turner, J. Koyanagi, M. Ji

The analysis of rare earth element (REE) samples is a necessary part of the metallurgical process for rare-earth bearing ores, providing invaluable information during testing procedures. This requires a fast, multi-element technique, capable of analyzing a variety of matrices for all rare earth elements. X-ray Fluorescence spectrometry and Instrumental Neutron Activation Analysis are typically used for high concentrations of REE, but they have limitations for some process work applications due to an inability to measure all elements, longer analysis times, significant interferences and elevated detection levels. The work reported here uses new approaches with Inductively Coupled Plasma Mass Spectrometry (ICP-MS) in order to achieve high precision and accuracy within acceptable timeframes. A combination of aerosol dilution and Kinetic Energy Discrimination (KED) produce a process solution assay method that is robust enough to deal with changing sample matrices and concentrations, whilst maintaining low reporting limits and precisions of less than 5% Relative Standard Deviation (RSD). For high concentration metallurgical and geological samples, a sodium peroxide fusion digestion procedure was used, followed by ICP-MS analysis using extended dynamic range (EDR) and KED. Using these technologies, it has been demonstrated that the necessary support can be given to metallurgical process work for REE extraction.

Jan 1, 2014

By T. R. Raponi

"The Williams Mine, Canada's largest gold mine, processes over 6,000 t/d of ore utilizing SAG/ball milling, leaching and CIP, carbon stripping, electrowinning and refining to produce gold dare bullion.Grinding accounts for over 50% of milling costs with grinding media, power and mill liners making up over 75% of grinding costs. Since 1991, several changes in these areas have been made which have significantly reduced costs, while fineness of grind and mill recovery have both been increased.This paper discusses the changes made in the grinding circuit over the past few years and assesses their impact on operating costs and mill operations.IntroductionThe Williams Mine is located in the Hemlo area of northwestern Ontario, about 40 km east of Marathon. It is operated by the Williams Operation Corporation, which is equally owned by Teck Corp. and Homestake Canada Inc. Canada's largest gold mine, the Williams Mine commenced operation in October 1985 at a rate of 3, 000 t/d. Mill throughputs have typically exceeded design, averaging 3, 397 t/d in 1986, and 3,380 t/d in 1987. In August 1988, production was increased to 6,000 t/d. Throughput averaged 4,212 t/d in 1988. Production increased over the next few years averaging 5,477 t/d in 1989, 6,248 t/d in 1990, 5,987 t/d in 1991, and 6,283 t/d in 1992. With a recovery of over 95.5%, production for the first three quarters in 1993 is averaging 6,408 t/d.GeologyThe main ore body is a steeply dipping conformable zone of microcline-quartz-muscovite rock. It occupies the contact zone between hanging wall metasedimentary rocks and foot wall felsic quartz feldspar porpyritic rocks of possible volcanic or subvolcanic intrusive origin. The ore body is enveloped by muscovite schists which are thickest on the footwall side. The schist is enriched with tourmaline, pyrite, and green mica containing vanadium and barium. The ore body contains pyrite and barite which occurs mostly in laminae and bands to veinlets and breccia fillings. The gold occurs as free (native) grains, 20 to 30 µm in size at grain junctions of the microcline and quartz. Visible gold is rare in the main zone. There are commonly two or more discernable layers of economic value which are separated by weakly gold mineralized material which usually consists of muscovite schist, barite rich zones or sulphide poor-microcline-quartz rock and in the upper and western fringes by biotite rich schist with feldspathic fragmental characteristics. Molybdenite is a common constituent as very fine disseminated grains in the microcline-quartz rock and is most prominent with gold enrichment. Stibnite and realgar are two of the more common accessory sulphides."

Jan 1, 1994