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By Peter Wells, Adrian Sabau, Turgut Yalcin

"The nickel ores of Sudbury contain substantial amounts of the gangue mineral pyrrhotite (Fe7S&) which causes certain diflculties in the milling of these ores. This paper proposes a process called “magnetoflotation” as an effective means of dealing with pyrrhotite. The method reduces the pyrrhotite content of concentrates by applying a magneticjield on the path product as it leaves the flotation cell.Successful performance of magnetoflotation requires the optimization of several variables. In this study, three of the variables (air flowrate, collector concentration, pother concentration) were investigated by Box- Wilson experimental design, and others (magnet speed, grind size, pulp density, flotation time) were examined individually. The process was tested on a Falconbridge nickel ore, assaying 1.92% Ni, and under the best operating conditions, a concentrate was obtained with 13.56% Ni grade and 74.32% recovery in a single step. Further improvements to grade and recovery were possible by cleaning and scavenging. The same ore was also tested with conventional methods for comparison, and results indicated that magnetoflotation performed better.INTRODUCTION“Magnetoflotation” refers to the process of carrying out magnetic separation and flotation simultaneously within the same device, and is intended to prevent magnetic minerals from reporting to the froth products while non-magnetic minerals are being floated. Typical cases where this method might be beneficial include the processing of magnetite and nickel ores. Its use on magnetite ores has been reported elsewhere [Yalcin, 1992; Yalcin, 19931. This paper describes its application to nickel ores, more specifically to the nickel ore of Falconbridge Limited in Sudbury."

Jan 1, 1999

By C. A. Rowland Jr

"I. INTRODUCTIONFred C. Bond's ""Third Theory of Comminution"" (1) was published in 1952. The mathematical statement of the Third Theory is the well-known Bond Formula:where W - Kw H per short tonWl - Work IndexP - Product size in microns which 80% passesF .. Product size in microns which 80% passesWork Index, as defined by Fred Bond, "" ... is the comminution parameter which expresses the resistance of the material to crushing and grinding. Numerically, the Work Index is the KwHrs per short ton required to reduce the material from theoretically infinite feed size to 80% passing 100 microns."" (2)Work indices for grinding can be obtained tram Bond grindability tests and can be calculated from plant grinding mill operating data when power consumed per ton of ore ground, the feed size analysis and the product size analysis are known.Work indices obtained tram Bond grindability tests, having been obtained from standard and controlled laboratory procedures, are reproducible and for the sample tested are accurate. The degree of accuracy relative to plant mill operation depends upon how representative the sample is of the total mill feed.The results of the Bond closed circuit rod and ball mill grindability tests (3) are given in grams of product sized material produced per revolution of the test mill. In developing a method to evaluate plant operating data and results from his grindability test, Fred Bond developed the ""Third Theory of Comminution."" In the process formulae were developed for converting grams per revolutionobtained from grindability tests to work index.The standard feed sizes for the Bond grindability tests are:Rod Mill Test ore crushed to minus 1ll inchBall Mill Test ore crushed to minus 6 mesh (Tyler)The formulae for converting grams per revolution to work index incorporate the 80% passing sizes for the feed to and the product produced in the specific test. Therefore, accurate work indices can be obtained from Bond grindability tests when the feed size is finer than standard. To obtain accurate test results, the ratio of reduction should be greater than 6 to 1."

Jan 1, 1972

By Ken Wood

"A reliable source of water of an acceptable quality is vital to the success of any mineral processing plant using wet methods. For Cerro Verde, a new 108,000 t/d copper mill in southern Peru, the main source of raw water is the Chili River. The Chili River is heavily contaminated with raw sewage, industrial wastewater and agricultural runoff, and can also receive high sediment loads during the rainy season. The initial water treatment plant could not supply design flows of water due to the exceptionally poor water quality. Problems with treated water quality caused significant difficulties with water consuming equipment, such as the plant cooling systems. This paper details the Cerro Verde water system and changes from design through to start up from a mineral processing perspective.INTRODUCTIONMining, and mineral processing in particular, is a water intensive activity. Improving water system design and practice are key strategic requirements in moving toward a more sustainable mining industry. This case study forms a basis for ongoing research into water use and reuse at mines and mineral process plants, conducted by AJ Gunson, under the supervision of Dr. Bern Klein and Dr. Marcello Veiga at the University of British Columbia. The case study material was gathered through involvement with the design, startup, and redesign of the Cerro Verde water system.Cerro Verde is a low-grade copper porphyry mine, located near the city of Arequipa in southern Peru, at an elevation approaching 2,800 m. In 1972, one of the world’s first copper Solvent Extraction – Electrowinning (SX/EW) facilities was built on the site, processing oxide ore from two main open pits. In 2004, the operator, Sociedad Minera Cerro Verde S.A.A. (SMCV), approved a 108,000 t/d expansion project to process sulfide ore reserves through a new concentrator plant. The plant was designed under extremely tight schedule and capital constraints, with a mandate to intentionally avoid any overdesign."

Jan 1, 2008

By J. C. Escobedo, J. M. Almanza, A. Flores, Cortés. D. A.

Secondary aluminum dross, which has been exposed for several years to atmospheric conditions, was characterized using chemical analysis, X-ray diffraction, optical and scanning electronic microscopy, and energy-dispersive spectroscopy. Based on the characterization, a method to purify the solids is presented. This method starts with the washing of the dross in boiling water to eliminate the soluble compounds like Na and K, followed by the physical separation of the metallic aluminum by milling and screening. Finally, an acid lixiviation process is applied using three different acid solutions, HCl, HNO3, and H2SO4. The best results were obtained using HCl. The main insoluble components of the dross after lixiviation were Al, SiO2, and Al2O3. MgAl2O4, AlN, Si, and Na2Al22O3·2H20 species were also found. Based on the alumina content, the solid product could be suitable as a raw material in the manufacture of castable refractories or metal matrix composites.

Jan 1, 2005

By P. P. Sinha, D. N. Bhatia, B. R. Ghosh, R. K. Gupta

Medium carbon, low alloy, high-strength steels containing Ni, Cr, and Mo are used for the fabrication of various types of high-strength fasteners required for launch vehicle structures. Cold heading properties and response to hardening and tempering are the essential requirements of the material for fabrication and application, respectively. Combining these two requirements is essentially warranted in high-strength fastener-grade steels. Cold heading properties require ductility, which can be achieved through spheroidizing treatments. In the absence of a suitable spheroidizing cycle for medium carbon 3.8 Ni, 1.8 Cr, 0.3 Mo steel, experiments were carried out with a theoretical understanding of the alloy system. This paper presents the experiments and results obtained after a spheroidizing treatment, which was carried out to optimize the process. Hardness measurements were carried out and microstructural studies were conducted to assess the spheroidization process and to determine the optimal spheroidization parameters.

Jan 1, 2007

By J. Coffin, R. Multani, C. Deredin

Glencore’s Strathcona Mill has recently evaluated a pyrrhotite depressant combination of diethylenetriamine (DETA) and sodium metabisulfite (SMBS) to improve its overall plant pyrrhotite- pentlandite (Po-Pn) selectivity, with the aim of producing a higher quality nickel concentrate. In a previous paper, key findings from a comprehensive lab-scale program (completed at the XPS Centre) were summarized where, of the depressants tested, DETA/SMBS combination was found to be the most effective in improving the Po-Pn selectivity. The present paper describes the metallurgical program recently completed at Strathcona Mill; DETA/SMBS evaluation on select plant “grab” samples as well as the major results of three DETA/SMBS plant trials conducted on several plant ore feeds (long-term testing). Interestingly, it was found that there was variable success in using DETA/SMBS depressants on the different plant ore feeds; DETA/SMBS (dosage: 25/50 g/t milled feed) on lower Cu feeds demonstrated a ~2% Ni recovery increase at the same Ni grade. On the other hand, higher Cu feeds demonstrated virtually no benefit from DETA/SMBS at the same plant dosage, suggesting that higher DETA/SMBS dosage (at specific locations) than that tested is required to overcome the increased Cu-DETA complexation for these particular feeds. Glencore Nickel – Sudbury Integrated Nickel Operations owns and operates Strathcona Mill which has been processing Ni-Cu ores from the Sudbury Basin since 1968. The valuable sulfides are pentlandite (Pn) – (Ni,Fe)9S8 and chalcopyrite (Cp) – CuFeS2, majority of the sulfide gangue is pyrrhotite (Po) – Fe(1-x)S [0 < x ≤ 0.125] which is present in two forms: hexagonal Po (Fe9S10) and monoclinic Po (Fe7S8) (Multani & Waters, 2017; Lawson et al., 2014). Currently Strathcona Mill processes ore mined from two primary sources from the Sudbury area and produces two concentrate streams: (1) nickel-copper concentrate that is sent to the Sudbury Smelter; and (2) copper concentrate that is shipped to the Fonderie Horne (Glencore Copper, Rouyn-Noranda).

Jan 1, 2019

By Toshiharu Teranishi

When we apply the Au nanoparticle superlattices to the future nanooptical and nanoelectronic devices, the control of not only the particle size but also the interparticle spacing and symmetry of superlattice are the essential problems to be overcome. First, we developed a novel synthetic procedure to precisely control the particle size of alkanethiol-protected Au nanoparticles in the range from 1.5 to 9.7 nm by the heat-treatment of the small Au nanoparticles in the solid state. Absorption and nonlinear optical properties of alkanethiol-protected Au nanoparticle superlattices were then elucidated. On the other hand, the hexagonal close-packed (hcp) 2D superlattices of small Au nanoparticles with the interparticle spacings from 1.9 to 3.6 nm were successfully prepared by using newly-synthesized ligand for single electron tunneling devices. Finally, various symmetric superlattices, such as chain (2-fold), quasi-honeycomb (3-fold), square (4-fold), etc., of Au nanoparticles could be produced by making use of interligand interactions or some templates.

Oct 1, 2003

Increasing depths and mechanization of underground mines have led to the production of large amounts of gaseous and particulate contaminants. Over 100 000 lives have been lost due to methane gas and dust explosions in coal mine workings in both the United States and Canada since 1900. There is, therefore, the need to constantly assess and evaluate the performance of existing mine ventilation systems to maintain safe and acceptable mine environmental conditions. This paper advances research initiatives in the control of methane gas in underground mine environments. It uses the results of continuous monitoring of methane gas concentrations conducted in selected coal mines in North America to assess the effectiveness of existing auxiliary ventilation systems to control methane gas concentrations. The results show that the average quantities of fresh air required to dilute, disperse and remove methane gas concentrations within set levels of one minute varied from 5.43 m3/sec. to 27.97 m3/sec. in the development headings. The average dilution times in the headings studied were less than eight minutes. The calculated dilution efficiencies of the auxiliary ventilation systems in the headings varied from 12% to 139%. These efficiencies ranged from poor to excellent. This implies that the auxiliary ventilation systems were capable of controlling the methane gas concentrations below statutory levels but may not be able to cope with large and unusual methane gas concentrations in the headings. This study is significant in the control of methane gas and coal dust explosions in coal mines.

Sep 1, 2001

By Kazutoshi Haga, Ariunbolor Narankhuu, Ariuntuya Battsengel, Yasushi Watanabe, Altansukh Batnasan, Akita University

"Rare earth minerals are usually concentrated by flotation, magnetic or gravity separation methods to produce concentrates that are subsequently leached with hydrochloric (HCl), sulfuric acid (H2SO4) or nitric acid (HNO3). About 75 % REEs are lost in gypsum by-product when apatite is dissolved in H2SO4, whereas more than 80% of REE can be extracted from the apatite using HCl and HNO3 leaching processes, respectively. Therefore, the main aim of this study was to find an efficient process of dissolution of rare earth elements (REEs) from apatite ore by sulfuric acid solution due to its lower cost. In order to optimize the dissolution process, effects of different parameters, namely, concentration of H2SO4 (0.05 – 6 M), solid/liquid phase ratio (1:50 – 1:100), temperature (20 – 80 ºC), agitation speed (300 – 900 rpm), and leaching time (0.5 - 6 h) on the dissolution of REEs from apatite ore were examined in various intervals. The contents of main REEs in the apatite ore used in this study were (as % wt): 3 % La, 6 % Ce, 0.6 % Pr, 2.1 % Nd, 0.2 % Sm and 0.3 % Y. X-ray diffraction (XRD) analysis identified fluorapatite and phlogopite as main minerals in the ore. The results obtained from leaching experiments showed that more than 85% of REEs were dissolved from the apatite ore under the optimized conditions, which were: 1 M H2SO4, particle size of -150 + 100 µm, S:L phase ratio of 1:50, agitation speed of 500 rpm at 20 ºC for 1h. The XRD analysis revealed that main mineral compositions of the residues from 1M and 6 M H2SO4 leaching are gypsum (CaSO42H2O) and hemigypsum (CaSO40.5H2O), respectively.INTRODUCTIONThe term rare earth elements (REEs) denote the group of 17 chemically similar metallic elements consisting of the 15 lanthanides, plus yttrium (Y) and scandium (Sc) in the periodic table. These metallic elements are generally divided into two sub-groups; (1) the cerium sub-group, which is called “light rare earth elements” (LREEs), includes the elements from lanthanum (La) to europium (Eu), and (2) the yttrium (Y) sub-group elements, which are known as “heavy rare earth elements” (HREEs), are the remaining lanthanides from gadolinium (Gd) to lutetium (Lu) plus yttrium (Gupta and Krishnamurthy, 2005). The REEs occur together in the minerals due to their chemical and physical similarities, which cause problems of separating them from one another (Abreu and Morais, 2014). Although REEs are relatively abundant in the earth’s crust, they are typically dispersed and rarely occur in concentrated forms, making them economically challenging to obtain. There are a wide variety of rare earth minerals, however economic deposits of REEs in mining are bastnasite (La, Ce) FCO3, monazite (Ce, La, Y, Th) PO4, and xenotime YPO4 (Binnemans, 2013; Xie, et al, 2014). Due to the unique physical, chemical, catalytic, electrical, magnetic and optical properties of REEs, demand of these elements has increased dramatically with the advent of new technologies in electronics, communication, construction, energy and medicine (Jordens, et al, 2013). Since 1990, China has provided about 90 % of REEs worldwide. Japan and United States are the largest consumers of China’s REEs. In 2010, China announced to reduce REEs exports to Japan, as it tended to increase prices of REEs and to reduce a stable supply of REEs in the world market (Humphries, 2013). Therefore, there has been an increase in recent exploration activities intended to reveal new commercial sources of REEs and to bring them into production (Antico, et al, 1996). Apatite is an important host mineral for REEs in igneous and metamorphic rocks and can be used as an ore for those metals (Kanazawa and Kamitani, 2006). Apatite is also the main source of phosphate fertilizers and phosphoric acid (Habashi, 2013; Emsbo, 2015)."

Jan 1, 2016

By Jeffrey L. Pagnutti

Train derailment can lead to loss of capital, damage to the environment, and loss of life. Machinery condition monitoring techniques can be used to develop a structural health monitoring system for railway track to detect faults at the incipient stage, before catastrophic failure occurs. This study uses vibration measurements from a novel material haulage unit to develop a decision support system for railway track maintenance. A variety of feature sets and classifiers were compared to determine the optimal configuration for fault detection. The results highlight the shortcomings and advantages of certain methods and describe the process in which the optimal result was obtained. The Parzen data descriptor paired with a refined statistical feature set performed the task of fault detection with less than five percent false positive and false negative classification error. Overall, the outcome of these experiments indicated that condition monitoring of railway systems is a promising approach for fault detection and has the potential to avoid catastrophic failure.

May 1, 2013

By William Pitman

Ground instability and subsequent rock falls are a major concern in underground mines. As a result, several mining companies are conducting risk assessments of the ground support installed in their mines. Risk assessment is now commonly used to provide mine operators with a systematic process to assess the strategic risks that could lead to injury to personnel or loss of production, and evaluate possible risk control measures. Risk assessments can be carried out to identify major hazards, assess the likelihood of occurrence and consequences of each hazard and estimate the level of risk. This process allows assessment of possible remediation actions to minimize the risk and likelihood of occurrence or mitigation of the consequences to a level that is reasonable and practical. This paper presents two practical mine applications of qualitative risk assessment of ground support to highlight the benefits of this process. Yearly or bi-yearly risk assessment of mine excavations can assist mine operators in prioritizing resources and areas that require support remediation. In addition, it provides a mechanism for proactive response to reduce potential risks associated with personnel safety, equipment safety and environmental impact. It also provides a baseline against which changes in ground condition can be compared and quantified.

May 1, 2004

By Maureen E. Lipkewich

Education builds long term awareness, acceptance and support for responsible mineral resource development. The MABC Education Program is an award winning education partnership with British Columbia classroom teachers that has helped over 5400 teachers with resources and other learning opportunities. Each year, thousands of students begin, and continue, to learn about our modern mineral industry as a result of this teacher-written program. The CIM network has an integral role in the future of mineral education in today?s classrooms in Canada and programs of this caliber are vital to our future. The industry needs help in raising awareness of the benefits of modern mining and teachers need help in acquiring that information.

May 1, 2002

By R. H. Batey

"The process control and cost of monitoring mining slurries is normally accomplished using a continuous mass flow system, conventionally embodying a volumetric magnetic flow meter and nuclear density meter. DuPont’s Maxville Mine at Starke, Florida, USA was chosen to examine costs associated with performance of a nuclear density meter. Since it is typical of many mid-sized establishments and has a long history in their use. The published accuracy under ideal conditions of a nuclear density meter is ± 1.0%, but in practice considerable ambiguity of cost in annual production implies ± 2% at best. Using such accuracy in a 400mm (16”) pipe carrying zircon slurry at 75,000 tons/day, the cost of ambiguity, together with initial and running costs, amount to nominally $962,000 per year.Such cost leaves much to be desired. This paper describes an unique continuous, direct mass per unit volume Density Meter used for mining slurries in pipe sizes up to 1000mm (40”), which significantly reduces the cost of ambiguity of measurement and running costs. At the same time the disadvantages of nuclear devices are obviated.In an effort to reduce costs, a 400mm non-nuclear Density Meter was installed at the DuPont Maxville mine. A typical on-site accuracy can be shown to be ± 0.285%, whereby the cost of ambiguity, initial and running costs in the example above shows an annual improvement of $78,660, a reduction of over $880,000 per year.Even higher cost savings may be demonstrated with mass flow systems having gas entrainment compensation. Unlike nuclear and other inferential density meters, the signal quality of this non-nuclear Density Meter is totally unaffected by entrained gas found in mining slurries. This non-nuclear density meter is then ideally used with a vortex velocity domain sonic flow meter, and provides for the first time compensation in wet density or dry % solids, as well as wet or dry mass flow of mining slurries with entrained gas, resulting in enormous reductions in cost ambiguity."

Jan 1, 2013

By Richard Burt

"In seeking to supply the ever increasing needs for raw materials, the mining industry has been required to develop lower grade resources in increasingly remote regions of the world. This has resulted in the extension of many frontiers, both technologically and geographically.The accent of mineral processing research over the last few decades has been to “do existing things better”. There have been many breakthroughs in equipment and processes; however in general the accent has been to increase capacity of existing unit processes, often by orders of magnitude, or to refine the process itself by basic research and development. This has lead to added sophistication, enabling the process engineer to maintain optimum performance of his equipment while reducing the cost, and the amount of labour needed to operate the plant.While much of the increased requirement for resources is handled by the development of ever larger, lower grade orebodies, a significant portion still comes from the small miner - even the artisanal miner - operating in remote and often politically sensitive parts of the world. For them, innovation and simplicity are the keys, not sophistication.The tension between sophistication and simplicity - or research and reality - is specially evident in the area of gravity concentration of rare metals, such as tin and tantalum. This paper looks at this tension, primarily from the eyes of an operator and seeks to put into perspective the two paradigms."

Jan 1, 1999

By K. Morin

"Silver and gold leaching by cyanidation is a well-known process used around the world. This reaction is often accompanied by the leaching of other species throughtout the cyanidation circuit that causes the diversion of cyanide towards non valuable by-products (SCN-, Cu(CN)x, Fe(CN)x, etc.). One of the detrimental impacts of the formation of these by-products is the precipitation of silver-cyanide complexes that occurs when cyanide concentration is too low. Without any extra-addition of free cyanide, the precipitated silver is lost and cannot be recovered causing an important economic loss. To overcome silver precipitation, cyanidation circuits are often operated at higher cyanide concentrations. Recently, COREM’s research team has been working on a technology to measure and control silver precipitation during the cyanidation process. Moreover, a methodology has been elaborated in order to evaluate threshold cyanide level which corresponds to the cyanide concentration at which silver starts to precipitate. This technology has been tested on site on a real cyanidation circuit at Agnico Eagle’s LaRonde mine."

Jan 1, 2014

By M. C. Harris

The past twenty to thirty years have seen unprecedented research activity aimed at understanding the performance of flotation froths. In 1990, Finch and Dobby coined the term froth recovery factor, Rr, to represent the efficiency of the froth in delivering particles from the pulp-froth interface to the concentrate. Originally defined for flotation columns, Rr has also been found useful in modeling mechanical flotation cells, and a number of techniques, based on quite different approaches, have been developed for measuring the froth recovery in industrial flotation cells. None of these techniques is universally successful. This paper reviews the concept of the froth recovery factor, and the basis of each of the techniques that have been proposed to measure Rr, and examines the reasons for this parameter being so difficult to pin down. Advances in Mineral Processing Science and Technology Proceedings of the 48th Annual Conference of Metallurgists of CIM Sudbury, Ontario, Canada Edited by

Jan 1, 2009

By Mohsen Amir-Rahmat

The ore of Sarcheshmeh copper deposit that has been located in the south ?east of Iran, contains four type of rock that they have their specific hardness and strength according to their alteration type and mineralization. Blasting of these various types of mine rocks prepares various types of size for the product of mine as the feed of concentration. Along the crushing of this feed a few factors effect on the efficiency of the crushing unit. The aim of this project has been the consideration of the effect of ore size on the efficiency of crushing unit. For this investigation along the year 2000 A.D., six sample from feed and six sample from product of crushing unit have been prepared. The results of the screen analyze of these samples has shown that the size of feed has been lesser than the primary plan and the size rate of the product has been bigger than the primary plan. Also in this research the effect of feed size on the quality of product size has been considered.

May 1, 2003

By Paul Hosford, Tim Haldane

"The paper describes the fast-track development of the project from feasibility study through to detailed design and construction, highlighting the process adaptations for handling sticky ore and water management in a tropical environment, and subsequent commissioning and operating experience of the mine. The paper discusses the geological setting, the environmental and socioeconomic considerations in developing and operating a mining operation in an underdeveloped country and the logistical challenges involved in bringing a large capital investment into Central America.INTRODUCTIONGlamis Gold Ltd. acquired the San Martin project in Honduras as a result of its merger with Mar-West Resources in late 1998. Despite the prevailing low gold price environment at the time of acquisition, Glamis anticipated rapid development of the San Martin project due to the quality of the deposit and other positive factors.Following favorable exploration and permitting activities in the first half of 1999, Glamis prepared a Feasibility study. In October 1999, Glamis decided to proceed with the development of the project and selected Hatch to provide the engineering, procurement and construction management services for the project. The San Martin project was in full-scale commercial operation approximately 14 months after the receipt of Board approval, and by July 2001 the San Martin project was operating at approximately 150% of its feasibility design capacity."

Jan 1, 2002

By Richard Dahl, Richard P. Taylor, David H. Watkinson

"Abstract - Detailed mapping of the Eastern Gabbro, Coldwell Complex, Ontario, revealed that the copper and platinum-group-element deposit on the Marathon property is confined to a coarsegrained to pegmatitic gabbro-diorite intrusion, the Two Duck Lake intrusion (TDLI). Exposed along the eastern boundary of the Coldwell Complex, the TDLI was emplaced as a sill whose orientation is slightly oblique to the general structure of the Eastern Gabbro. The TDLI has been subdivided into lower, middle and upper sub-units on the bases of lithological, textural, mineralogical, and geochemical criteria. Both border sub-units are sulfide-, base- and precious metal-enriched, and exhibit abundant evidence of host-rock assimilation. The primary mineral assemblage in the TDLI is plagioclase, olivine, clinopyroxene, Fe-Ti oxides, with accessory orthopyroxene, biotite, apatite; this primary mineral assemblage is essentially preserved in the core of the intrusion (i.e., the middle subunit). The Cu-PGE Marathon deposit, delineated mainly in the upper sub-unit of the intrusion, consists of disseminated Fe-Cu-Ni sulfides, and platinum-group-minerals derived by hydrothermal remobilization from primary magmatic sulfides. Enrichment in Cu and PGE resulted from partial replacement of original Fe-Ti oxides and pyrrhotite in the primary mineral assemblage by reaction with (a) residual magmatic fluid, and (b) fluids derived from the breakdown of host rock xenoliths and hydrothermal alteration along the lower contact of the TDLI. Résumé - La cartographie détaillée de l’Eastern Gabbro, Complexe Coldwell, en Ontario, révèle que le gisement de cuivre et éléments du groupe du platine de Marathon est confiné à une intrusion gabbro-dioritique, de grain grossier à pegmatitique, l’intrusion Two Duck Lake (TDLI). Cette intrusion s’est mise en place sous la forme d’un filon-couche légèrement discordant sur la structure de la bordure orientale de l’Eastern Gabbro. On y distingue trois sous-unités, inférieure, centrale et supérieure, sur la base de zonations lithologique, minéralogique et géochimique. Les sous-unités marginales sont enrichies en sulfures, métaux usuels et précieux, et montrent de nombreux indices d’assimilation des roches hôtes. La paragenèse minérale primaire inclut le plagioclase, l’olivine, le clinopyroxène, les oxydes ferro-titanés et accessoirement et localement, l’orthopyroxène, la biotite et l’apatite : cet assemblage est surtout préservé au coeur de l’intrusion (sous-unité centrale). Le gisement de Cu-EGP de Marathon, situé principalement dans la sous-unité supérieure, comprend une minéralisation disséminées à sulfures de fer, cuivre, nickel, et minéraux du groupe du platine, dérivés de sulfures magmatiques primaires par remobilisation hydrothermale. L’enrichissement en Cu et EGP résulte du remplacement d’oxydes ferro-titanés primaires par réaction avec des fluides tardi-magmatiques, et des fluides assimilés le long de la bordure inférieure de l’intrusion, dérivés de la fusion partielle des xénolites et de remobilisations hydrothermales."

Jan 1, 2001

By E. Fried

Cemented paste backfill (CPB) is an innovative tailings management method that consists in returning considerable amounts of mine tailings into the underground mine openings. The filled stopes thus participate to the ground support that allows maximizing orebody extraction and a safer environment for the mine workers. There are also significant environmental advantages of using CPB. Indeed, up to 50% of the concentrator tailings can be backfilled, leading to a smaller volume of problematic waste materials to be managed at the surface. Once the CPB is placed, or when the mine is flooded at its end-life, the backfill is subjected to underground water flows that may leach and spread the pollutants (mainly metals, sulphates, and acidity) which can contaminate the underground waters. The aim of this study is to characterize the leaching properties of CPB material and to identify the cement phases that ensure the metal fixation. A laboratory procedure was implemented consisting in the preparation of various paste backfill mixtures using sulphide-rich and sulphide-free materials, different types of binder, and mixing waters having various sulphates, copper and zinc concentrations. After 90-days curing time, the samples were submitted to column leaching tests. The CPB materials were flushed each day with 100 ml of deionised water during 100 days. The collected leachates were then analyzed for pH, Eh, electric conductivity and chemical composition. For some samples, a differential acid neutralisation test was carried out. The objective of this experiment is to dissolve selectively the hydrated phases by adding incremental acid concentrations. By analyzing punctually the equilibrated solutions, the composition of the dissolved phases and their metal content can be estimated. The leaching test results showed that the pH of the leachates remains alkaline during the test period. When the pH decreases under 10 (after 30 days), different behaviours in terms of chemical element release (especially for zinc) were observed. During the test, the oxidation of pyrite seems to slow down, probably due to passivating phenomena. Moreover, the differential acid neutralisation test results allowed a better understanding of the CPB mineralogy and the Zn-bearing cement phases. Zinc and the other metals seem to be fixed within a calcium-magnesium silicate.

May 1, 2007