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By L. Nichols, H. Keele, K. Czajewski

"The oil sands industry in northern Alberta disposes of the by-products of bitumen extraction into tailings ponds. The mix of tailings sand and mature fines, with gypsum added as a flocculent, constitute a waste stream called consolidated tailings or composite tails (CT). The two main challenges of the tailings disposal process are a chronic shortage of economical containment and the potential mobility of CT deposits in the event of breaching by, for example, long-term erosion, which makes abandonment of tailings ponds more complicated. Thick deposits of CT do not consolidate in adequate time to provide reassurance for abandonment of the CT containment facilities and that is why the containment must be adequately robust or the properties of CT improved for long-term stability. This paper addresses potential solutions to these problems by applying the gravity drainage of CT and quasi-homogeneous construction for containment facilities.Gravity drainage is suggested as a mechanism to facilitate the consolidation of CT in critical areas of the ponds by inserting internal sand layers within the body of the deposit. Critical CT areas are defined as areas around the perimeter of containment. The advantages of this solution are longterm stability of the disposal area by creation of stiff deposits around its perimeter and facilitation of reclamation efforts on its surface.The present solution for containment of CT deposits is not favourable from a materials balance point of view. In general, sand has become a valuable resource as it both forms the primary component of the CT matrix and becomes the containment building material. If sand is required for CT, less is available for dyke construction. This puts additional pressure on the industry as a whole to maximize the use of overburden and interburden for construction of tailings containment structures. Typically, only 50 percent of dry mine waste (overburden + interburden) is incorporated into dyke construction. The remainder of dry waste is stored either in waste dumps or in tailings ponds, consuming valuable in-pond space originally allocated to CT material. Quasi-homogeneous dykes are proposed to contain CT deposits rather than traditional minimum cross-section dykes built of overburden and/or cell sand. The quasi-homogeneous dyke may change the unfavourable material balance and lessen the construction constraints that are presently imposed on the mine/waste disposal process."

Jan 1, 2008

By Will Callupe Arzapalo

The success of the minimization of blast induced-damage at Barrick?s Pierina Mine in Peru is the result of an effective working relationship between Mine Operations and the Geotechnical Services Department. A detailed design criteria manual is used to match the blast plan to the site?s varying rock types and slope designs. The Geotechnical Services Department has further developed a comprehensive pre- and post-blast checklist that is critical to the drilling and blasting process as it pertains to wall stability. Wall control blasts are evaluated with quality assurance field checks, vibration monitoring and frequency control, video assisted performance quantification and post excavation face profiling. These detailed observations are compiled and summarized in a blast performance evaluation that is considered to be an ?Industry Best Practice?. The information and detail provided by each performance summary allows accurate blast analysis and effective design refinement.

May 1, 2006

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'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 Dave Marsh, John Goode, Niels Verbaan, Kevin Bradley, Henrie Notzl

The mineralogy of the Avalon Nechalacho deposit is complex with significant fractions of HREEs, Zr, and Nb found in refractory minerals such as zircon and fergusonite. Sulphuric acid baking followed by water leaching can be used to extract REEs from flotation concentrates, but acid baking does not completely "crack" the zircon and fergusonite, so the extractions of Zr, Nb, and HREEs are not high. An alternative flowsheet has been developed that is able to obtain significantly improved extractions of HREEs, Zr, and Nb from flotation concentrates or acid bake residues. This is accomplished by cracking the zircon and fergusonite minerals with caustic soda at high temperatures, followed by water washing to recover excess caustic soda and soluble sodium silicates and phosphates. REEs, Zr, and Nb in the solid residue can then be solubilized with HCl or H2SO4. This paper highlights some of the findings from an extensive laboratory program and discusses several flowsheet implications.

Jan 1, 2014

By James Ransford Dankwah

This work investigates the effect of waste plastics addition on the reduction of iron oxide by sawdust. Composite pellets of iron oxide containing sawdust (SD), high density polyethylene (HDPE) and blends of SD/HDPE were fired under argon in a horizontal tube furnace at temperatures between 1300 and 1500 °C. Reduced samples were weighed after 10 minutes of reduction and the extent of reduction was calculated from the measured oxygen contents of the compact. The results showed improved extent of reduction when SD was blended with HDPE. The highest extent of reduction was achieved at SD:HDPE ratio of 2:3.

Jan 1, 2014

By J. E. Dutrizac, J. B. O'Reilly

"Zinc is a relatively abundant element which occurs as both high-grade sulphide ores {sphalerite ZnS) and oxide ores which the ancients collectively termed ""calamine"" (smithsonite ZnC03 and/ or hemimorphite Zn4Si201(0H)2 - H20 and/ or hydrozincite Zn5(C03) 2(0H)6). Although oxidic zinc is readily reduced by carbon, the process becomes thermodynamically viable only at - 1000°C, and at this temperature the zinc is released as a vapour (B.P. 907°C). Casual cooling of the vapour results in its re-oxidation by excess combustion air or even the carbon monoxide product of the reduction reaction. ZnO + C = C09,, + Zn vapom Only fairly rapid quenching of the zinc vapour and the isolation of the reduction products from the combustion gases will yield metallic zinc; these conditions were not produced deliberately until the advent of distillation technology. Until quite recently, the principal use of zinc was in brass manufacture; galvanized iron was not discovered until the 19th century and zinc casting alloys are a relatively recent invention. As will be seen, brass could be produced without recourse to a pure zinc intermediary, and the discovery of brass preceded that of zinc by many centuries. The purpose of this paper is to outline the discovery and early development of both zinc and brass with special reference to the European scene."

Jan 1, 1999

By Gordon G. Duncan

Historical Sketch Occurrences of native copper have been known along the Arctic coast of Canada, especially in the vicinity of the. Coppermine river, since the early part of the eighteenth century (See map, Figure 2, insert). In 1769, Samuel Hearne, a clerk of the Hudson's Bay Company at Fort Churchill, was sent to explore the 'copper mines' from which natives had been reported to secure copper for tools, fishing spears, etc. After two successful attempts, he reached the Coppermine river in 1771, accompanied by Indian guides. This hazardous trip was indeed a remarkable feat when one considers the vast distance covered, a great deal of which was barren lands. At Bloody falls, (See Figure 1) on the Coppermine river, Hearne's Indians swooped down on a party of sleeping Esquimaux, who gathered there each summer to fish, and murdered the entire band encamped on that side of the river. Hence the name of the falls. Hearne's knowledge of minerals was undoubtedly limited. He reported having seen the copper mines from which the natives were securing the copper, but he failed to prove the economic possibilities of the copper occurrences or to give an accurate description of any deposit. Sir John Franklin visited the area in 1821. He and other members of his expedition, namely, Richardson, Back, Kendall, and Hood, reported native-copper float to occur in the vicinity of the Coppermine river and Bathurst inlet.

Jan 1, 1931

By D. Prince, G. Nollet

"Since 1994, Aur Ressources has operated Louvicourt mine, a zinc and copper mine close to Val d’Or, at a rate of 4300 t/d. Ever since the start-up of the plant, management has encouraged innovative approaches in reliability. The first of three papers will discuss the vibration monitoring program in place. The program will be described and two examples will be given: detection of a rolling bearing defect on a pinion driving the ball mill and identification of wear on the bearings of the flotation cells. Figures on the return on investment and the costs of a monitoring program will also be given.The second article will discuss the lubrication aspect. Since the establishment of a good monitoring and oil analyses, Louvicourt mine decreased its oil consumption by more than 38 000 L/yr. In addition, the company set up an oil regeneration system that restores the original properties of oil.The third article will cover the management aspect. Work organization as well as the management philosophy enabling the employes to push predictive technology to higher levels will be examined in detail. The key elements which made it possible for Louvicourt mine to position itself among world-class companies in the organization of maintenance will be discussed."

Jan 1, 2002

By S. W. Stogran

"A brief summary of the environmental testing and analyses required to ensure and maintain compliance of mining properties will be discussed. Programs for new and existing properties and for properties which may be purchased will be outlined and potential solutions to problems will be discussed. In addition to the compliance aspects of operations, due diligence will be discussed.1.0 INTRODUCTIONThe impact of mining projects on the environment is an area of major concern to the public, governmental agencies and mining companies. Due to the ever increasing pressure on the government by special interest groups and the public, governments have implemented legislation to control potential environmental impact of mining, from the exploration phase through to close-out. By not planning for environmental issues during all phases of a mining operation, unavoidable delays and retrofitted environmental programmes will be expensive and cause projects to be delayed, which, ultimately, may cause the abandonment of a mining prospect. Most jurisdictions require at least one full year of background environmental data. Therefore, many thousands of dollars are wasted as construction is interfered with or held up due to data collection. This may be avoided by a thousand dollars worth of sample being collected and analyzed early in the project."

Jan 1, 1992

By Mehmet Canbazoglu, Kaarlo Haavanlammi, Hannu Laitala

Cobalt is currently a critical metal because of the increasing number of electrical vehicles forecast for production. Copper and zinc are base metals that are used in many everyday applications, including vehicle production. Eti Bakir Co. Mazidagi Phosphate Plants in the Mazidagi district of Mardin, Turkey is a multi-product facility that produces cobalt, copper, and zinc, as well as fertilizers, from the roaster calcine. Roaster off gas is treated in a sulfuric acid plant (SAP) and the acid itself is utilized in fertilizer production. The comminution circuit, roaster, SAP, and calcine leaching process were developed by Outotec and integrated with the fertilizer production process implemented by Eti Bakir A.Ş. This paper describes the hydrometallurgical calcine leaching process used at the plant, with a focus on the oxidative pressure leaching of the cobalt, zinc, and copper-containing calcine. The cold and hot commissioning phases of the pressure leaching autoclave start-up are discussed together with experiences from the ramp-up period. The production processes of the copper cathode and cobalt and zinc-containing salts are also presented together with some of the plant’s operating parameters. INTRODUCTION The ETI Bakir A.S. fertilizer plant, Turkey, is located in Mardin Province near the border with Syria, (Figure 1). The leaching plant project was started in 2012. The purpose of the plant is to separate the valuable metals from the calcine produced by the pyrite roasters, which are used to produce a SO2 containing gas for the new sulfuric acid plant. Fertilizer production requires sulfuric acid, and for this reason a sulfuric acid plant was built; customer already had access to pyrite concentrate, which is used as the roaster feed. During the engineering phase of the roaster and acid plants it was noticed that the roasted calcine contained considerable amounts of valuable metals like cobalt, copper, and zinc. To recover these metals, a calcine leaching process was developed at the Outotec Research Center in Pori, Finland. The main process connections of the Mazidagi site are shown in Figure 2.

Jan 1, 2019

By J. P. Harrison, M. Grenon

"This paper summarizes the results of numerical studies on drift stability in moderately jointed rock masses. It investigates the relative pertinence of geomechanical factors such as joint orientation, spacing and stress regime. This is undertaken using a distinct element model and a series of parametric studies. IntroductionIn evaluating the stability of drifts in jointed rock, it is often necessary to compromise by employing models that capture the complexity of the rock mass, but which are still simple enough to allow for their routine implementation. The distinct element method can arguably provide an eloquent method to accomplish this. This paper explores the applicability of the method by means of a parametric study aiming to identify the dominant factors that influence the stability of drifts in moderately jointed rock. To this end a commercially available 2D distinct element numerical model was used. A series of techniques are presented in an effort to quantify the results of any instability predicted by the model.This paper also demonstrates a case study where a 3D joint network model was integrated into the distinct analysis software package. The advantages, as well as the current limitations of this approach, are discussed."

Jan 1, 2001

By Zetti Gavelán

Lack of skilled workforce in mining industry during the current decade has been a serious concern for most mining organization globally. At the beginning of this decade the major envisioned difficulty was related to generational breach of mining professionals. By 2003, mining industry recover from a low metal prices cycle following by a worldwide mining investment boom in 2005 that triggers a talent war among mining companies that was not only limited to professional level but skilled operators as well. Despite world?s economy collapse in October 2008, impact on mining industry was small comparing to other industries and appears to show evidence of healing. Under this context, fundamentals that have been driven lack of skilled workforce for the mining industry in previous years still valid. Starting in 2007, Minera Argentina Gold SA - Barrick Veladero, subsidiary of Barrick Gold, initiated an innovative selection and training program for candidates without exposure to mining. Following our corporate social responsibility mandates, Barrick Veladero decided to change its hiring process entirely, concentrating on selection and training of local people with no experience rather than hire experienced mining operators. This paper shares Barrick Veladero experiences on its hiring program, challenges faced, and current results.

May 1, 2010

By Douglas Macaulay

"The Work contains the personal views and opinions of the Author and in no manner should it be construed as reflecting the official position of Export Development Canada. The Author makes no representation or warranty with respect to the accuracy or completeness of the contents of the Work and specifically disclaims any implied warranties, merchantability or fitness of use for a particular purpose". Export Development Canada ?Canada?s official export credit agency, established 1944 ?Mandate to support export and foreign investment ?Financially self-sustaining, AAA rated borrower ?Services include: Financing (FIN), Political Risk Insurance (PRI), Contract Insurance & Bonding (CIB), Accounts Receivable Insurance (ARI) ?A trusted partner in troubled times

May 1, 2010

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

By J. D. Bliss, G. J. Orris, W. O. Menzie

"Analysis of gold placer data from gold placers throughout the world suggests that gold grades and volumes cannot be used to distinguish between most types of gold placers. Only the alluvial plain and fan placers are significantly different among the types of gold placers considered. Gold grades and volumes change when working gold placers go from small-volume methods to large-volume methods. The small-volume methods are either of the surface or subsurface (drift mining) type. The odds that a gold placer will be dominantly worked using small volume methods at the surface are about 5:3. Once small volume mining has occurred, the odds against subsequent large-volume mining are about 4:1. If a placer deposit is suitable for large-volume mining, and the amount of gold produced from small-volume mining was reported, an estimate of the remaining gold (log10kg) can be made using the following equation:The relationship shown by this equation suggests that very large gold placers have over half their total gold content in the rich gravels appropriate for small-volume mining. These relationships in conjunction with other data and computer simulation can be used to estimate placer gold resources for an area targeted for mineral resource assessment. IntroductionGold placers have been an important source of gold throughout man's history and may have been one of the first sources-dating back to around 6000 B.C. (Gregory, 1980). From the primitive basket to the modern floating dredge, a variety of methods have been used to work gold placers. Placers are found in a wide spectrum of geologic and climatic settings. They have been classified by using a mixed set of criteria including age (Recent, Tertiary), climate (desert), fluvial position (modern channel, bench, alluvial fan), environment of deposition (eluvial, alluvial, residual, beach), type of transport (stream, wind, glacier), and whether the placer is buried or at the surface (Boyle, 1979; Wells, 1969). Several mining methods have usually been used to extract gold from anyone placer."

Jan 1, 1987

By J. Molgaard, J. Masounave, J. Prinsen, P. Beaulieu, G. Huard

"A study carried out on behalf of the National Research Council (NRC) indicates that economic losses due to wear in the Canadian mining industry are in excess of $700 million annually. Severe wear, mainly by abrasion, was identified as the most important wear mechanism in terms of possible savings. One way to reduce losses would be the proper use of databases. A joint project of The Canadian Institute of Mining and Metallurgy (CIM) and NRC (Tribology laboratories at IMRI) has been initiated to create a factual database containing all relevant experience in the area of wear in the Canadian mining industry. As a first step, a prototype covering slurry pumps is being built. This should help to answer many questions, such as the number of people involved, interest from industry, cost vs benefits, etc.IntroductionTribology is concerned with the understanding of the mechanisms of friction, wear, and lubrication.Tribology is concerned with the correct use of materials for interacting solid surfaces, with the interaction of those surfaces with lubricants, with the chemistry, physics and use of lubricants and their additives. It is concerned with the reduction of friction and wear (or, in the case of belts, brakes, clutch plates, and similar devices, in achieving optimum friction with minimum wear) and is concerned with the avoidance of associated failures in machinery.Lubrication is usually the solution to a problem of friction and wear. Yet far from all the problems of friction and wear are solved by lubrication. The wear of grinding rods or shovel track pads can hardly be solved by lubrication, to name just two examples with which mining engineers will be familiar. There are indeed many situations of wear and friction where the surfaces in contact are unlubricated.In part, tribology is a matter of design. A major aspect, however, has to do with the choice of materials, to satisfy external constraints upon the component design or choice. The operating conditions for much industrial equipment, particularly in mining are, often very severe. The development of wear resistant materials, including materials which are applied as coatings, is clearly an important technology from the point of view of tribology."

Jan 1, 1987

By Richard Klimpel

"Over the last 15 years, there has been a number of plant scale sulfide mineral flotation tests organized by this author specifically aimed at understanding how flotation rate varies with reagent type and dosage. With regard to the Interaction of collector dosage, particle size, and frother type, the eight specific trends listed in the paper (Illustrated with data from two specific case studies) are qualitatively the same for almost all plants studied in some depth. The Interaction of flotation rate K and equilibrium (Infinite time) recovery R in the plant has been denoted as the R/K trade-off. The effect of collector dosage on the rate of flotation of specific particle size intervals is particularly interesting and once understood, is quite useful In understanding how industrial flotation plants respond to changing reagent type and dosage. The location and magnitude of the R/K trade-off can be different for various ores and various plant configurations, but the RIK trade-off is almost always present. The purpose of this paper is to clearly describe and illustrate the nature of this very Important flotation system Interaction so that operating engineers have a starting reference point for beginning successful plant Improvement studiesIntroductionIt is well recognized by industrial froth flotation plant operators that improving existing sulfide circuit performance is often difficult due to the self-compensating systems nature of the froth flotation system, e.g. Klimpel (1988, 1989, 1995). Extensive plant testing with existing and new reagents by this author throughout the world has clearly shown that one of the more important self-compensating mechanisms is the Interaction between collector dosage, frother type, and particle size. The term self-compensation in flotation simply means that as the plant operator consistently changes one parameter in the same direction, the nature of the froth flotation system Is such that the circuit will eventually begin to resist this controlled parameter change by automatic (uncontrolled) changes In other parameters and the overall circuit performance will go through a maximum or minimum (hence causing the operator to stop the parameter change)."

Jan 1, 1997

By J. Ran

Ground instability is among the major causes of serious incidents and production disruptions in the mining industry and has a significant impact on safety. Mining companies may have operations in a number of jurisdictions with varied regulatory requirements for ground control management. As these companies expand into countries where mining regulations are formative or lacking clear definition, ground control practices are usually developed by local mine personnel based on their experience. In many cases, inconsistent procedures and standards are generated, which can lead to an increase in occurrence of underground incidents due to difficulties and confusion in implementation. This situation has forced some mining companies to standardize their ground control practices by geographic regions or divisions. Though this approach is an improvement, it may not lead to effective management of ground control issues across all operations of a global mining company. Barrick Gold Corporation, with operations in North and South America, Australia and Africa, decided to adopt a global approach to ground control management. This global approach requires all Barrick operations to prepare and implement an effective ground control management plan (GCMP) based on site specific conditions and company guidelines. It is also required that the GCMP be developed through application of sound geotechnical engineering practices and be consistent with local regulatory requirements and Barrick safety policies. All Barrick underground operations have GCMPs in place, and its surface operations are now involved in the initiative. This paper presents Barrick?s global approach to underground mine ground control management and outlines the content and process for the development of a GCMP.

May 1, 2006

By A. Himsley

"There is an ever-increasing demand these days for efficient methods of removing metals from solutions especially for selectively recovering a particular metal from a mixture of metals in solution.Up until the mid l 930's the only methods widely practiced for such separations involved precipitation techniques or electrolysis. Both these methods have limitations and indeed can only be used for certain metals.It is only within the last 40 years or so when synthetic ion exchange materials became available that chemists in industry and universities have been able to apply ion exchange techniques to a wide variety of separations that not only would be impossible by precipitation methods but which are now achieved with much greater efficiency.Ion Exchange TechniquesIon exchange is a unit process that can be applied using either liquid ion exchangers or solid resin particles. Liquid ion exchange - or solvent extraction as it is often referred to - is used in a number of special areas dictated mainly by the nature of the separation.On the other hand, ion exchange resins are much more widely used and consequently a great deal more is known about their application to a variety of metal separations.In both systems there is a loss of the ion exchange material which in the case of solvent extraction results in hydrocarbons going to waste. The ion exchange resin systems lose resin in the form of small particles, referred to as ""resin fines"", and these are insoluble.The loss of liquid ion exchanger is due to the fact that it is slightly soluble in water and consequently the loss is a function of the volume of liquid with which it comes into contact and is not related to the amount of metal processed."

Jan 1, 1975

By Dan Marshall, David H. Watkinson

Abstract - Cobalt, Ontario, is renowned for the 12.6 billion grams (445 million ounces) of silver produced from the area since discovery in 1903 by workers of the Timiskaming and Northern Ontario Railway. Native silver generally occurs with cobalt arsenides and sulfosalts in near-vertical carbonate veins cutting the Huronian sedimentary rocks of the Gowganda Formation, the Archean metavolcanics and/or the Nipissing diabase. All major deposits have been found within a few hundred meters of the unconformity between the Archean and Huronian rocks in general proximity to the Nipissing diabase and volcanogenic sulfide mounds within the Archean meta-volcanics. Silver has been mobilized from one or more of the local country rocks by hyper-saline brines and deposited in or near zones of mixing where the saline brines encounter paleometeoric water transported to depth along the unconformity or local structures. Previous work has shown that chloride complexes are the dominant ligands responsible for silver transport. These hypersaline brines, represented as halite-bearing fluid inclusions at room temperature, have been trapped as primary fluid inclusions within vein minerals. Pressure-temperature conditions of vein formation have been derived from mineral equilibria, maximum lithostat and fluid-inclusion studies. These data are consistent with vein formation occurring over the temperature range 300°C to 350°C, with pressures constrained between 60 Mpa and 136 Mpa (600 bars and 1360 bars).

Jan 1, 2000