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By W. P. Tassie

"The location of Quintette Coal Limited's pit and geologic nature of the dedicated reserves combine to introduce a number of factors which can adversely affect waste dump stability. These factors include steep terrain, variable material type and particle size, and precipitation. This paper describes the solutions to related waste dump problems. A brief geotechnical review of the waste dumps is given and Quintette's operational strategies during periods of dump stability and instability are discussed. Despite best efforts, failures occasionally occur and discussion is included on Quintette's success at bringing failed dumps safely back into use. IntroductionQuintette Coal Limited (QCL) property is situated on the east slope of the Rocky Mountains near Tumbler Ridge, approximately 120 km southwest of Dawson Creek, British Columbia. This surface mine is located on mountainous terrain and is subject to climatic extremes of wind, precipitation and temperature.QCL has a current annual production of 4.75 million tonnes of metallurgical coal with a stripping ratio of 7: 1. This correctly implies the extraction of over 33 million bank cubic metres (BCM) of waste which is placed on numerous waste dumps at various locations adjacent to the pit.There are three active pits - Mesa, Wolverine, and Shikano (Fig. 1). Shikano is a newly developed pit located near the plant site. It is not subject to the unique dump management problems prevalent at the Mesa and Wolverine pits, therefore the Shikano waste dumps will not be discussed . The dumps for the Mesa and Wolverine pits, however, have been technically and operationally challenging since shortly after mining began in 1983. Their characteristics, associated site specifics and management, therefore, are the subject of this paper.Waste dump locations for the Mesa and Wolverine pits are shown in Figures 2 and 3 as is the relative waste distribution . Each sub-pit is connected to a principal waste dump in reasonable proximity and to an alternate dump should disposal of waste be necessary at that location. The waste dumps are constructed from the top elevations initially to coincide with subpit development. In the initial years (1-7) waste dump heights will be up to 250 m, then, as the mine matures (8-20 years), waste dump maximum heights will continuously decrease to coincide with lower bench elevations"

Jan 1, 1988

By Graham Davey

"Ultrafine grinding of minerals has been in wide spread use in the industrial mineral field for over 30 years. Within the last 10 years the metalliferous industry has shown interest in the ability to produce ultrafine particles, as chemical, physio-chemical and physical separation processes have advanced to be able to treat ultrafine metalliferous particles. Also as the primary mineral deposits are depleted, new more difficult deposits must be mined. Existing operations are also looking to maximize economic return from existing deposits, requiring new thinking and technologies.The recent development of industrially proven and cost efficient technologies for ultrafine grinding has opened up another processing option for the treatment of finegrained metalliferous and refractory gold ores. The current commercial designs are variations of stirred mills used in the industrial minerals sector for the past 30 years. For the purposes of this paper ultrafine grinding is considered to be P80 of less than 15 microns.Attrition milling to fine grind sizes presents some challenging issues relating to scale-up including the dearth of information on the quantitative impact of feed and operating conditions, as well as the precise and accurate measurement of particle size distributions. Two examples from recent installations will be analyzed including Thalanga Copper and Century Zinc Mines. Both have diverse grind size targets for the SMD, yet both have realized significant metallurgical gains."

Jan 1, 2002

By Sophia Wong

Nickel is used in a wide variety of applications from consumer goods to industrial uses. In many of these uses, nickel contributes to the environmental attributes of the product. The challenge, however, is measuring that contribution, comparing it to the environmental cost of production, and communicating the role of nickel to the customer in a way that is easy to understand. This paper presents the Nickel Institute?s approach to climate change as a global commodity industry association, and discusses where we stand with regard to some of these key questions. It also identifies issues for the nickel industry moving forward ? challenges that are likely to be common to other commodities.

May 1, 2009

By Jason J. Crowder

Presentation Outline ? Introduction ? Costs of ground support and rehabilitation ? Why post-failure rock mass properties are necessary ? The Rock Mechanics Problem ? Present State of Modelling and Instrumentation in Mining ? Case Study Background ??Williams Mine ? Deriving Parameters for Modelling from Instrumentation ? Results from Case Study ??Back Analyses ? Discussion of Research Impact t Summary

May 1, 2006

By Doug Smith, Gary Taylor, Paul Ogryzlo

"Uranium mining and processing typically requires large quantities of high-grade reactive quicklime for the neutralization and clean-up of contaminated mine water and mill process waste streams. Currently the Saskatchewan uranium industry’s lime requirements are being supplied from deposits located in Manitoba and Alberta, resulting in transportation costs, which equal or exceed the market value of the product. During the summer of 2001, the northern village of Pinehouse located 220 kilometers south of the Key Lake uranium mill, staked two previously discovered limestone deposits. The relatively shallow deposits, known as Missi Island and Sleeping Giant are located in close proximity to one another, approximately 35 km south of Pinehouse adjacent to highway 914. This paper describes the results of a scoping study carried out by AMEC for the development of the two deposits based on a seasonal limestone mine and a continuous 40,000 to 60,000 tpy wood fired calcining plant designed to supply all of the quicklime needs of the Saskatchewan based uranium industry. Also described are the results of calcining and customer acceptance testwork on samples of lime prepared from recent Pinehouse limestone drill core. The potential benefits of the project include a significant new source of revenue for the community of Pinehouse, lower lime costs for the Saskatchewan uranium industry and employment for northerners in the mining, processing and wood harvesting operations.IntroductionInterest in the Pinehouse/Massinahigan River area for limestone was precipitated by the results of a 1977 industrial minerals drill hole program by the Saskatchewan Department of Mineral Resources. These results led to the acquisition of land in the area by Missi Island Mines Ltd who carried out extensive exploration during the period 1978-1982. They discovered a deposit on the southwest side of the Massinihigan River thought to contain approximately seven million tonnes of limestone with an average grade of 94.5% CaCO3. Missi Island carried out preliminary feasibility studies and prepared an Environmental Overview Statement. However, in spite of positive recommendations, the project was dropped in the mid 1980’s."

Jan 1, 2003

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 Claude MacDonald, John H. Ashburn

"IntroductionIndustrial growth and technological change over recent years had been accompanied by two major sources of concern to management and employees: (a) increase in occupational injury and illness and the resultant costs involved; and (b) equipment damage and breakdowns in concentrated production lines causing more extensive loss potential.Due to economic factors, management attention has focussed more on production and quality than on safety, health and related loss potential sources. As a result , occupational safety and health activism has grown, government legislation of compensation and occupational safety and health standards have progressively developed and stronger liability attitudes have been taken by courts of law.To improve efficiency and allow development in more competitive markets, rising labour costs, equipment costs and safety related financial losses have dictated that attention be given to conservation of all resources. Conservation of resources, people, equipment, material and environment, can no longer be addressed in isolation but must be managed integrally with production and quality. To this end, systems have developed utilizing sound management principles applied with equal intensity to production, quality and loss potential"

Jan 1, 1987

By R. A. Ozerkevich, R. J. Voisey

"SherrGold's MacLellan V ne is located about five miles south east of Lynn Lake immediately to the east of the Keewatin River. (Figure # 1)The property is accessible by an all weather road, leading north from the provincial highway 391, which links Lynn Lake with the Town of. Leaf Rapids and the city of Thompson to the south.The MacLellan Mine (formerly the Agassiz property) was discovered in the early 1950's and optioned from Comiesa Corporation in 1979 by Sherritt. SherrGold Inc. was formed in September 1985. Sherritt then transferred the MacLellan Mine, 15 other gold prospects in the Lynn Lake area and the old Lynn Lake nickel-copper mill to SherrGold. At the same time Sherrgold entered into a management agreement with Sherritt whereby Sherritt would develop and operate the MacLellan Mine and conduct SherrGold's exploration activities.The ore body as outlined in the original feasibility study is expected to produce in excess of 300,000 ounces of gold and 450,000 ounces of silver over the next 5 years. However the deposit is open to depth and exploration is continuing on and around the main zone and the many satellite deposits.The start of construction of the MacLellan mine and mill was scheduled to phase in with the closure of the Fox copper-zinc mine located 30 miles west of Lynn Lake. The majority of the employees from the Fox Operation were either employed at the MacLellan mine or relocated to Sherritt's Ruttan Operation."

Jan 1, 1987

By Konstantinos Modis

According to recently established theoretical analysis and under certain conditions, a critical sampling density can be determined for an earth-related space-distributed natural variable. Sampling above this critical limit adds little to the mapping results. The objective of this paper is the application of the above theory to the Sesklo clay quarry in Greece, where Heracles General Cement Company had conducted a sampling campaign to estimate its reserves. The structural analysis of Al2O3 values generated a variogram model, from which the critical sampling density was identified. This critical number was by far lower than the existing sampling density. Clay reserves were then estimated using geostatistics and inverse distance squares in different data schemes with variable densities. The results of the comparisons between the various models revealed that, when the sampling density was greater than its critical value, geostatistics and deterministic interpolation gave similar estimations, which is also in agreement to the theory. The optimal sampling grid finally proposed here, will result to significant cost savings in the next drilling program which is now in plan by the company.

Oct 1, 2009

By Benoît Demers

Dans ses opérations de traitement de concentré de zinc, l?usine de Zinc Électrolytique du Canada à Valleyfield génère un résidu minier appelé « jarosite ». Jusqu?en 1998, le jarosite était transporté hydrauliquement dans des bassins construits en argile. Le jarosite sédimenté possède une consistance très molle (impossible de circuler à pied sur le résidu consolidé) avec une eau interstitielle acide contenant des teneurs élevées en métaux. Ces caractéristiques particulières au jarosite rendaient très coûteuses la construction et la fermeture des bassins de résidus. En 1998, Zinc Électrolytique du Canada a implanté un nouveau procédé, développé chez Noranda, dont le principal objectif était de stabiliser chimiquement et physiquement le jarosite. Un nouveau concept de déposition a été élaboré pour le nouveau résidu minier appelé « jarofix ». Les grandes caractéristiques du nouveau procédé et du concept de déposition sont : ? Le jarosite est lavé et déshydraté à l?usine avec un système de filtre; ? De la chaux, du ciment et de l?eau sont ajoutés pour former le jarofix; ? Le jarofix est transporté par camions jusqu?à l?aire d?accumulation; ? À l?aire d?accumulation, le résidu est géré selon un concept d?empilement. L?élaboration du concept d?empilement et de l?aire d?accumulation devait tenir compte des caractéristiques de déposition du jarofix, de sa résistance à l?érosion hydrique et éolienne, de la gestion de l?eau de ruissellement, de la faisabilité de construire les digues de ceinture en utilisant du jarofix durci et de la nécessité de restaurer progressivement l?aire d?accumulation. Le déchargement du jarofix se fait à partir d?une rampe qui progresse avec une pente ascendante pour développer un front de déversement de plus en plus haut. La hauteur du tas de jarofix atteindra 30 m au centre du site. L?aménagement initial de 1998 a inclut une digue d?amorce de 3 m de hauteur, une rampe de déversement de 8 m de hauteur et un bassin pour la gestion de l?eau de ruissellement. Les propriétés du jarofix consolidé dans l?aire d?accumulation sont déterminées annuellement. Le jarofix durci possède la consistance et la résistance d?une argile très raide. Sa conductivité hydraulique est similaire à celle d?un silt et il résiste bien à l?érosion éolienne. Après trois années de déposition, la température du jarofix au milieu du dépôt demeure élevée. Le jarofix durci est facile à excaver et à compacter, ce qui en fait un excellent matériau pour la construction des digues de ceinture en périphérie du site.

Nov 1, 2002

By Evelynn Stirling

Agenda ? Emissions legislation ? Cummins Tier 4 Technology ? Cummins Experience with Technology ? Operation and Maintenance Impact The Emissions Challenge ? The 2014/5 emissions regulations present the most significant challenge to our customer?s diesel powered equipment design and operation in recent history? ? ?and Cummins has the solution.

Aug 1, 2013

By Francis Breton, Daniel Larouche, Pierre Heugue, Rémi Martinez

"Nowadays, in order to fit environmental restrictions, automotive markets are demanding cast aluminum alloys working at high temperature (180–300°C). New generations of alloys are required for higher strength components in engine downsizing or start-stop systems which lead to higher loading and higher specific power and stretch current materials to their limits. Recently, transition metals, such as zirconium and vanadium, have been added as alloying elements into an AlSi7Cu3.5Mg0.1 alloy to improve physical, mechanical, thermodynamic properties with the aim of increasing service life of parts. In such alloys, the best mechanical properties are associated with the formation of precipitates through an optimum heat treatment sequence, including: solutionizing, quenching and artificial aging. This study is focused on the modified AlSi7Cu3.5Mg0.1 cast alloy with Mn, Zr and V additions for high temperature application. The characterization of the cast alloy in this study, firstly, helps to evaluate and understand its performance both chemically and structurally according to their physical state: as-cast or as-quenched. Comparison of precipitation kinetics between a binary Al-3.5%wt.Cu alloy and the AlSi7Cu3.5Mg0.1 (Mn, Zr, V) alloy has been characterized by differential scanning calorimetry, TEM observations and micro-hardness testing. The Kissinger analysis was applied to extract activation energies from non-isothermal DSC runs conducted at different stationary heating rates. The study focuses on the impact of the chemical composition such as Si content on the kinetics parameters.INTRODUCTION Pure metal Aluminum shows poor mechanical properties and its malleability is high, that is why alloying elements are added to the mixture before casting to improve physical, mechanical and thermodynamic properties (Javidani, 2015); such as Silicon (Si) for casting properties (castability, cold crack capability, wear resistance, shrinkage behavior), Magnesium (Mg) and Copper (Cu) to generate precipitation hardening systems. Aluminum hypoeutectic alloys (<12% Silicon) with Cu, Mg additions used in the automotive industry for manufacturing mechanical parts (Larouche & Javidani, 2014) are mostly subject, after casting, to precipitation hardening heat treatment (Mohamed & Samuel, 2012) according to specifications and associated standards. The best mechanical properties are associated with the formation of precipitates through an optimum heat treatment sequence, generally including: solutionizing, water quenching and artificial aging (Manente & Timelli, 2011). Hypoeutectic aluminum-copper alloy with amount of Cu around 1 to 4.5wt% is an elementary case for precipitation in heat treatable aluminum alloys. Researchers essentially focused their work on the full precipitation sequence of binary Al-Cu alloy during aging which is presented below."

Jan 1, 2018

By Gordon E. Agar, Brian Lyons, Gregory H. Styles, William B. Kipkie

"Rock rejection during the flotation of a copper-nickel ore was improved by adding carboxymethyl cellulose to both a rougher and cleaner flotation stage. The selection of the rock depressant was based on laboratory rates studies. Plant operating results are presented which confirm the laboratory selection of two particular brands of carboxymethyl cellulose.The rock assay of the concentrate was reduced from more than 40% to less than 15%.IntroductionThe traditional method of selecting flotation reagents relied upon batch bench scale tests, conducted under arbitrary conditions, to identify the effect of the reagent under examination. Too often these were ""one-off"" tests with little or no regard paid to the reproducibility of the results. Sophisticated researchers used statistical methods to design and evaluate the experiments but they were still obliged to rely on the arbitrary and often unreliable batch tests to generate the numbers that were analyzed statistically. An interesting side-effect of the enhanced sophistication of the statistical analysis was often that no significant effects would be uncovered in a series of experiments that would have generated many positive conclusions and much further experimentation if the same results had been evaluated by the traditional method.In the recent past, at least two groups of researchers a have directed their attention to the reliability of the batch experiments with a view toward improving the reproducibility of the test data. In this work the best of the improvements advocated by both of these groups have been adopted in order to generate kinetic data from batch tests that are as reproducible as possible.The objective of the work was to reduce the rock content of a bulk sulphide concentrate produced at Inco&apos;s Shebandowan mill. During 1982 the Shebandowan concentrate analyzed 3.5% Cu, 7.4010 Ni, 25% pyrrhotite and more than 40% rock, which resulted in an MgO content of 10.4%. Besides the expense of shipping all of this rock to Sudbury, the rock also contributed to the poor filterability of the concentrate. On favourable occasions the moisture content of the filter cake was slightly over 20% by weight. The magnesia content of the concentrate was deleterious to the reverberatory furnaces used by Inco for smelting nickel concentrate because the slag viscosity increased as the magnesia content increased, and the nickel lost in the slag went up."

Jan 1, 1987

By H. Sahay

This paper summarizes the history and ore-grade statistics of mining the Ming orebody, and then details the mining methods. Included are raising, stoping, drilling and blasting techniques. Particular attention is paid to ground support, ventilation and pumping requirements.

Jan 1, 1979

The properties required for a com-pound to form useful thermoelectric materials are described. Uranium compounds which might have these properties are reviewed. Several of these compounds have been prepared and fabricated into compacts. The apparatus used for hot pressing, and for the measurement of thermoelectric power, electrical conductivity and thermal conductivity, is described. Detailed attention has been given to the properties of the nitrides. Preliminary studies on a number of other uranium compounds are reported. The figures of merit of the best materials so far examined are one-tenth of those necessary for a useful thermo-electric material. THE efficiency of thermoelectric materials for power generation and cooling is determined by their figure of merit, Z = a2 a/K, where a, a and K are thermoelectric power, electrical conductivity and thermal conductivity, respectively. It is well known that the largest values of Z are achieved with semiconductors (1). High mobility of charge carriers is necessary for simultaneously high thermoelectric power and electrical conductivity.The properties required for a com-pound to form useful thermoelectric materials are described. Uranium compounds which might have these properties are reviewed. Several of these compounds have been prepared and fabricated into compacts. The apparatus used for hot pressing, and for the measurement of thermoelectric power, electrical conductivity and thermal conductivity, is described. Detailed attention has been given to the properties of the nitrides. Preliminary studies on a number of other uranium compounds are reported. The figures of merit of the best materials so far examined are one-tenth of those necessary for a useful thermo-electric material. THE efficiency of thermoelectric materials for power generation and cooling is determined by their figure of merit, Z = a2 a/K, where a, a and K are thermoelectric power, electrical conductivity and thermal conductivity, respectively. It is well known that the largest values of Z are achieved with semiconductors (1). High mobility of charge carriers is necessary for simultaneously high thermoelectric power and electrical conductivity.

Jan 1, 1963

By Peter Makuvise, Alain M. Bantshi

"The Mazowe Gold Mine is managed by Metallon Gold (Zimbabwe) and is situated in the west-central part of the Harare greenstone belt. Orebodies here generally comprise shear zones which are in-filled with gold-bearing sulphides and quartz. The mineralised zones are up to 1 m in width, have average grades of 4 to 5 g/t, and mostly dip between 10º and 60º to the north.Mazowe Mine is one of the oldest mines in Zimbabwe, and exploration and development in this region dates back to 1890, with over 1.4 million ounces of gold produced to date. Mazowe mine comprises two underground operations, Mazowe and the BSV sections. Ore is processed in a single plant which consists of conventional crushing and milling and carbon-in-leach facility.Baldmin Projects was awarded the contract for the design, construction and commissioning of the 60,000 tonnes per month plant at Mazowe mine in 2014 for the processing of sand and slimes tailings from previous operations at Mazowe mine. The average grade of the tailings is 1.1 g/t. The plant consists of feed preparation, grinding, flotation, thickening of flotation concentrate, and carbon in leach (CIL). A pump station for hydraulic mining of the slimes tailings dam also part of the plant.Key features of the Mazowe sands Plant are described and include:• Hydraulic mining of gold tailings dump.• Feed preparation section that includes a (W x L) 2.4 m wide x 4.8 m trash screen, 250 m3 surge tank, a cluster cyclones with 2 x 500 mm diam. Cyclone.• Comminution circuit designed for a bond work index range of 10-12 kwh/tonne. comminution circuit is constituted with 3 ball mills, 1.83 m diam. X 6.71 m Long, 280 kW.• Flotation circuit comprising rougher bank, scavenger bank and cleaner bank. Rougher Scavenger bank is constituted of 6 x 6m3 flotation cells and 3 x 30 m3 flotation cells and the cleaner is constituted of 3 x 6 m3 flotation cells.• Concentrate Thickening with 6 m diam. Thickener.• Concentrate CIL (carbon in leaching): CIL circuit is comprised of 7 tanks with 2 leach tanks and 5 Carbon in leach."

Jan 1, 2017

Located in Timmins, Ontario the Porcupine Joint Venture, a pooling of assets between two existing operations (the Dome Operation of Placer Dome (CLA) and the Hoyle Pond Operation of Kinross Gold Corporation) came about on July 1st, 2002; Placer being the manager of the Joint Venture with 51% ownership and Kinross with 49%. The formation of the Joint Venture was the realization of the dream of many who could envision the benefits of the whole area being operated as one entity ? the combination of the majority of assets in the Porcupine Camp into one venture containing tremendous synergistic potential of manpower, infrastructure, land tenure and exploration development. The name Porcupine in the gold mining industry brings with it the legacy of world class gold mines; the Hollinger, McIntyre and Dome with a proud tradition of excellence. The name Porcupine brings with it the legacy of over twenty individual mining companies in operation at any one time, producing over 65 million ounces of gold.

May 1, 2003

By A. Sheikh, S. Hardcastle

"Various methods of leaching are being used by Denison Mines Ltd. Uranium Operations. This study was designed to investigate the flood leaching operation of two parallel inter-connected stopes contained by pressure bulkheads. The teaching muck piles, created from large scale uppers production blasts, are aerated by compressed air lines laid beneath the pile prior to blasting.A SFr, tracer gas, injection technique has been employed to determine the post-blast integrity of the single-ended air distribution system. SF6 was injected into the compressed air line feed to the stopes and collected at borehole exhausts from the stopes in grab-sampling bags. Analyses of the air samples were performed with a gas chromatograph.The system was designed to give a sufficiency of oxygen to sustain bacterial activities used to enhance the leaching recovery in the muck piles. The results obtained indicated that there is a minor anomaly in the distribution system that may not be critical to the operation. Compared to an idealized case, the over-all efficiency of aeration throughout the muck is estimated at over 85%."

Jan 1, 1988

By M. Beth McClenaghan

This paper summarizes diamond exploration techniques used in glaciated terrain, focusing on indicator mineral and geochemical methods applied to glacial sediments. Understanding the ice flow history, depositional history, and stratigraphy of glacial sediments are essential to successful sampling, interpretation and follow-up of indicator mineral and geochemical anomalies related to kimberlites. Kimberlite indicator minerals survive glacial transport over long distances and the relative abundance of each mineral in till is a function of the primary mineralogy of individual kimberlites. Indicator mineral distributions observed at a regional scale define the net effect of glacial dispersal, often along different ice flow directions. Local-scale distributions define individual dispersal trains. The medium sand (0.25 to 0.5 mm) fraction of heavy mineral concentrates prepared from glacial sediment samples is best suited for indicator mineral surveys. The application of till geochemistry to diamond exploration is increasing because it is significantly cheaper than indicator mineral analysis and it can be performed quickly. The <0.063 mm (silt+clay) and 0.5 to 2.0 mm (coarse sand) fractions provide the best geochemical contrast between background and kimberlite-rich till. Kimberlite pathfinder elements that provide good contrast include Ni, Cr, Ba, Co, Sr, Rb, Nb, Mg, Ta, Ca, Fe, K, Ti and REE, the relative importance of which will depend on kimberlite composition as well as that of the surrounding bedrock.

May 1, 2002

By Keila Gonçalves, Aline Tavares, Danielly Couto

"The sulphide copper deposits from the Carajás area (North region of Brazil) were generated by the percolation of hydrothermal fluids in volcanic and granitic rock and are denominated as IOCG deposits (iron oxide copper-gold deposits). During these hydrothermal events a wide variety of gangue minerals such as amphiboles, biotite and fluorite were formed. These gangue minerals are enriched in fluorine and chlorine which are deleterious elements in the copper concentrate. Chalcopyrite and bornite are the main copper-bearing minerals and they can occur in veins, in brecchia or disseminated in gangue.The study, which included bench scale flotation tests and minipilot plant tests was aimed at improving the fluorine rejection in the flotation process during the flowsheet design for one of these Carajás sulphide copper deposit. All of the study was supported by quantitative mineralogical techniques such as QEMSCAN and the use of a scanning electron microscope (SEM).This paper describes and discusses the results obtained in the metallurgical tests and emphasizes the importance of the quantitative mineralogical characterization during the process conditions optimization and flowsheet design.INTRODUCTIONIron oxide copper-gold (IOCG) deposits encompass a wide spectrum of sulphide-deficient low-Ti magnetite and/or hematite ore bodies of hydrothermal origin and normally have important copper sulphide reserves. In the Carajás mineral province, located at the southeast part of the Amazon Craton in Pará State (Brazil), there is a variety of world-class (>200 million tonnes) Fe-oxide Cu-Au deposits (e.g. Salobo, Cristalino and Sossego), whose genesis has been assigned to hydrothermal fluid percolation in volcanic and granitic rocks. Figure 1 displays the location of the Carajás area.The hydrothermal thermal fluid composition was extremely variable. It may have contained gases, salts (brine) and metals. The metals were carried as various complexes and it is thought to have involved sulphur, chlorine and fluorine containing species. This resulted in some minerals formed during the hydrothermal alteration having high fluorine and chlorine contents. These elements result in smelter penalties in a copper concentrate because they cause the smelter off-gases to be more corrosive."

Jan 1, 2011