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By Karl Marquis

La Mine Mouska exploite depuis deux ans certains blocs de réserve à l?aide de la méthode long trou. Même si, à priori, la méthode long trou semble rentable, le contrôle de la dilution ainsi que le respect d?un échéancier serré s?avèrent primordiaux afin que cette méthode d?exploitation puisse être justifiable économiquement. La présentation suivante fera la comparaison économique entre cette méthode et celle de chambre-magasin.

Oct 1, 2001

By M. Doggett

All 231 Canadian primary gold mines that produced from 1946 to 2004 were analyzed with respect to their production and economic characteristics. Trend analysis revealed that the average annual capacity of Canadian gold mines, as measured by ore processed or gold produced, has increased over time. Conversely, the average grade of gold mines has decreased over time. The distribution of gold output is highly uneven: for example, the 22 giant mines producing more than 100 t (metric tonnes) of gold account for 62% of total output. Small mines producing less than 10 t Au account for 54% of total mines, but less than 4% of total gold. Each historical mine in the database was evaluated on the basis of a set of economic and technical assumptions to determine if it would be economic to develop today. Based on the net present value using an 8% discount rate, only 103 of the 231 mines were determined to be economic. About 80% of the uneconomic mines had less than 10 t of contained gold, and 63% had less than 5 t. It is concluded that these small mines would not be viable today due to a combination of real capital cost increases, and more stringent permitting and environmental regulations. The implication is that future gold supply in Canada will hinge on the discovery and development of a new generation of larger mines. Given that only one giant mine has been discovered in the past 20 years, it seems likely that gold output will decrease in the future.

Jan 1, 2007

By J. E. Nesset, L. S. Urbanoski, J. R. Goode

"The benefits and advantages of pre-competitive, collaborative industry/university research are not always well appreciated. This paper presents the case study of a current collaborative project between CAMIRO-Metallurgical Processing Division and McGill University that is investigating the understanding and prevention of sphalerite activation in lead and copper-lead flotation circuits. The benefits of the research findings to the sponsors can be maximized by an approach which links the researchers themselves with the sponsors at frequent, interactive project review sessions. Some examples of the findings and their application to industry are also presented along with a general update on CAMIRO-MPD.INTRODUCTIONThe history of Canadian efforts in the area of collaborative pre-competitive research is not long when compared to Australia (AMIRA) and Britain (MIRO). AMIRA (Australian Mineral Industry Research Association) began over 40 years ago and has had a well recognized role in bringing together industrial sponsors and researchers to fund a large variety of very significant development projects in that country, The total AMIRA funding effort for mineral processing work currently exceeds some $Aus 40 million with new projects valued at about $Aus 12 million initiated each year. This high level of commitment by industry has contributed to establishing Australian researchers and their facilities as among the best in the world.Canadian companies have traditionally funded much of their R & D in-house with extensive facilities and large funding commitments. The past 2 decades have seen most of these facilities disappear. The current situation is one in which only the largest integrated metal and mining companies have retained their own R & D groups (e.g. INCO, Falconbridge, Noranda). Industry-funded research at universities was primarily through individual efforts by the mining companies and rarely included collaboration with other mining companies, equipment or chemical suppliers, or engineering firms."

Jan 1, 2001

By Brad Thrall

"Viceroy Resource Corporation of Vancouver, B.C. has recently developed the Brewery Creek Mine, an open pit heap leach gold mine 55km East of Dawson City in Yukon, Canada. Mineable reserves are 17.1 million tonnes of ore grading 1.45 grams/tonne, containing 24.8 tonnes (797000oz) of gold. Ore processing employs the heap leach technology using run of mine ore. 1996 highlights included construction of 158,000 m2 of leach pad, placing 1.9 million tonnes of ore at a grade of 1.46 gpt on to the leach pad, construction and successful commissioning of the ADR plant, and pouring of the first gold bar on November 15th.Permitting this mine has drawn significant attention because the heap leach technology, while proven in other jurisdictions, has not been used in Yukon where winter site temperatures routinely reach -45 C for extended periods.IntroductionFollowing a comprehensive governmental and public review of the proposed project, a Class A Yukon Water license was issued in August, 1995. Construction started in 1995 and leaching commenced in October 1996. The Brewery Creek Mine is in Yukon, the home of the Klondike Gold Rush nearly 100 years ago. This is the only part of Canada not glaciated in the Wisconsin advance so there is oxide ore resulting from about 80,000 years of weathering -unique in Canada. Discontinuous permafrost is present on site and has required special consideration in the design. Winter temperatures dip below minus 50 C, demanding an approach to mining and leaching that is different than in more temperate climates.Project DescriptionThe mine comprises 8 shallow, largely oxidized gold deposits along a 7km corridor. An 8 year mining program will extract 17.1 million tonnes of ore grading 1.45 grams/tonne, containing 24.8 tonnes (797,000 oz) of gold. The strip ratio will be 1.35: 1. Overall gold recovery is projected at 78%. There will be 2.3 million tonnes of ore placed on the pad annually, with an average of 2.57 tonnes (83, 000 oz) of gold recovered per year. Because of the cold winters, the mine will operate approximately 210 days per year, while the leaching process will operate on a year round basis. Run of mine ore is placed on the heap 150 days per year. The recovery process utilizes conventional sodium cyanide leaching , carbon adsorption, caustic desorption, and on-site smelting. Peak employment during mining is 145 and winter staff is reduced to 45."

Jan 1, 1997

By J. R. Hart, V. C. Smith, V. P. Babarovich-Hansen, J. H. Schubert

"An introduction and case study of Mintek's latest generation of Milling Circuit controller, the MillStarTM with IES (Interpreting Expert System) is presented. This paper also describes as a case study its installation on a Southern African base metals concentrator plant which has demonstrated improved operation, greatly reduced variation in product quality, as well as increased capacity and availability of the circuit.In this case study, the MillStarTMw as installed along with several other enhancements, including hydrocyclone underflow monitoring, product particle size estimation and flotation circuit stabilisation. MillStarTM utilised the particle size measurement to control grind to within 2% of setpoint, all the while ensuring sump level control, density control as well as mill power optimisation. Mintek' s expertise in the modelling of tumbling mills allowed the development of a specialised optimising controller that ensured the mill was kept in the most efficient operating region.MillStarTM augments the automatic control with useful user interface features, such as on-line trends of any logged variables, historic data warehousing and retrieval and production summary reports.A novel feature that distinguishes the MillStarTMi s the IES (Interpreting Expert System). This is a feature of the software that works with the automatic control code to generate explanations for control actions made by the controller. Often complex control systems are mysterious in nature, reducing trust and eventually resulting in them being switched off. The IES method of exposing the heart of the controller has proved popular and is seen to have potential as a training tool. 314"

Jan 1, 2000

By C. J. Van Treeck

PGE concentrations of 18 g/t occur in the pyroxene rich rocks at the Union Bay Alaskantype complex. This PGE enrichment is hosted in magnetite veins. These veins cross magmatic layering and have an irregular morphology in both outcrop and thin section. Fe-Ti oxide geothermometry suggests that this mineralization took place between ~700-400°C. A variation in the amount of ilmenite and Mg- Al spinel exsolution in magnetite correlates with temperature estimates, lower temperature magnetite has less exsolution. Hydrous silicates form an alteration envelope around magnetite veins with a formation temperature of <575oC, vary with temperature, and contain appreciable amounts of Cl. Interaction of a PGE-Fe-Cl rich fluid with clinopyroxene increased the fluids pH and decreased PGE and Fe solubility depositing a PGE enriched magnetite within the Pyroxenites and Olivine Pyroxenites of the Union Bay complex.

May 1, 2003

By Arun .. J. Basu

The paper introduces Intelligent Air Management (IAM) as the core activity of M&I Group of Companies (M&I) for providing a total solution to any air management problems for mining and mineral processing operations implementing a comprehensive systems approach through a world-wide network of strategic alliance partners and in-house engineering team and manufacturing facilities in Mississauga, Ontario, Canada. Recommendations for energy-efficient ventilation in a vibration and noise free environment are made with the patented and innovative solutions supported by extensive computational fluid dynamics (CFD) studies. The solution scope extends from an intelligent and integrated exhaust silencer to a complete ventilation sys-tem solution including inlet and outlet control design and ducting for diffusers and silencers.

Apr 1, 2005

By E. Engelbrecht

"A pressure non-oxidative leach is employed at Anglo American Platinum Base Metal Refiners to extract nickel from a slow cooled matte. The design base requires two 80 m3 autoclaves in parallel to achieve a nickel extraction of 60% at the nameplate capacity of 32.4 ktpa nickel plated. Isothermal modelling of mineralogical and chemical concentration profiles, through a reactive mass balance, permitted rate constant parameter estimation and selection of the most probable reaction pathway. The model was validated with plant data up to a capacity of 26 ktpa Ni plated and suggested by extrapolation that nameplate capacity may be viable through one 80 m3 autoclave.INTRODUCTION Anglo American Platinum Base Metal Refiners is situated on the outskirts of Rustenburg in the North-West province of South-Africa. The refinery produces nickel cathode, copper cathode, cobalt sulphate powder, covellite rich copper pressure leach residue and bulk sodium sulphate through an integrated circuit that refines slow cooled converter matte. The converter matte is milled, non-magnetics are separated as solid nickel copper matte (NCM), and the magnetics are leached yielding a pressure vessel liquor (PVL). The remaining solid platinum group metals (PGM) concentrate after leaching is sent for downstream processing in the Precious Metals Refinery (Hofirek & Kerfoot, 1992). The work presented here is applicable to the base metals refinery which receives the two base metals feed stocks NCM and PVL. In 2009 the capacity of the refinery was upgraded from 21 ktpa nickel cathode plated to 32.4 ktpa. This paper deals with evaluating the capacity of the pressurised non-oxidative nickel leach (NOX) process which accounts for at least 28% of the nickel leached from NCM by design. The NOX design base requires two 80 m3 autoclaves divided into four compartments operated in parallel at 155°C and 600kPa(g). Elevated temperature is required to speed up the leach kinetics of particularly nickel and iron which are trapped in slow leaching mineralogical phases namely millerite and bornite, (Dinham, 2006). The stated equivalent capacity for the NOX configuration was 32.9 ktpa nickel plated at first pass nickel and iron leach efficiencies of 60% and above 80% respectively and is a key step for the selective removal of iron (Bryson, Hofirek, Collins, Stiksma, & Bereaowsky, 2008)."

Jan 1, 2017

By J. Andrew Cornier, Mike Cooper

"Upon successful completion of the AG/SAG Mill project (Cooper et al., 2001) the Brunswick Mine concentrator was configured with single line processing through the AG/SAG mill, followed by two parallel ball mill and flotation circuits. The Stage Grinding project was undertaken to utilize a pre-flotation stage on the AG/SAG mill primary cyclone overflow and simplify the flowsheet by consolidating the two ball mill and flotation circuits, resulting in single line processing fi-om AG/SAG mill to final concentrate. Concurrently, the reclaim water supply capacity was increased to enable flotation cleaning at lower percent solids.Benefits from the Stage Grinding project include revenue enhancement from increased zinc grade and recovery combined with additional lead recovery. Further benefits included a reduction in the number of process pumps, reduction in loss associated with spillage to sumps and process simplification through efficient use of equipment layout.The Stage Grinding project was implemented in six phases over a period of seven months in 2000. Each phase was commissioned during scheduled concentrator shopdays with minimal additional downtime required. One year after project approval the Stage Grinding project was completed at a total cost of $1 1.8 million.INTRODUCTIONThe Noranda Inc. Brunswick Mine, located near Bathurst, New Brunswick, is one of the world’s largest leadzinc mines. Milling of ore began in 1964 from the No. 12 orebody, with an expansion in 1966 to accommodate ore fkom the No. 6 open pit located several kilometers away. In 1980 the pit was exhausted and the concentrator rationalized to accept a design feed rate of 10,500 tomes per day from the No. 12 mine. In excess of 100 million tomes have been milled to date, representing over three-quarters of the known reserve. The concentrator employs differential froth flotation to produce lead, zinc, copper and leauzinc bulk concentrates. The ore is massive sulphide, with approximately 20% valuable minerals, 60% pyrite and 20% silicates."

Jan 1, 2002

By Michael B. Cortie

The young field of nanotechnology has as its objective the design and construction of useful devices made of nanoscale materials. Objects or structures which have at least one important dimension in the range 0.5 to perhaps 50 nm may be considered to be in the nanoscale domain. These sizes lie far below the 200 nm or so that can be resolved with an optical microscope, and are closer in size to the 0.3 nm diameter of individual atoms. Nanotechnology, which is the study and exploitation of these tiny structures, is attracting keen interest at present. The excitement is motivated by the observation that control of matter at the nanoscale holds the promise of faster computing, better medicines, and smarter materials. In this paper, the physical phenomena on which this optimism is based are broadly discussed and explained. Where appropriate, examples of the rather different and curious properties of gold at the nanoscale are used to illustrate the points covered.

Oct 1, 2003

By S. R. Knowles, R. J. McDonough

"The purpose of this paper is to introduce to the minerals processing marketplace a viable alternative to conventional mechanical agitation and pachuca airlift agitation. What follows is a brief introduction to the Atara Corporation and the fundamentals of how an Atara ""cannon"" mixer operates. The main body of the paper is concerned with the results of a study to evaluate the cannon mixer for a gold cvanide leach application. A brief summary of research and testing for other metallurgical applications is also presented.1. 1 THE COMPANYThe Atara Corporation is a privately owned Canadian company, headquarted in Dorval, Quebec. Its subsidiary, Atara Incorporated, located in Paramus, New Jersey services the municipal wastewater treatment market in the United States. Dorval focuses on industrial mixing applications in Canada and the US. The Atara Corporation provides design, engineering and specifications of agitators for mineral land other) processing applications. Fabrication of mixers is pursued in either Canada or the US, depending on the ultimate destination.Although Atara and its unique static in-tank mixer are relative newcomers to the mining industry, the cannon mixer has demonstrated its value over the past 20 years in municipal wastewater treatment services. In the past four years the Atara unit has been developed for industrial applications; the bulk of the development work has been for metallurgical applications. To-date the cannon mixer has been evaluated for mixing slurries in the following applications: nickel-copper concentrate storage, copper concentrate storage, coal slurry storage, gold cyanide leaching, uranium acid leaching, silver leaching and zinc acid leaching. Atara mixers have been installed with successful performance in full scale tanks containing nickel-copper concentrate slurry (Falconbridge) and gold cyanide leach pulp (Dome"

Jan 1, 1984

By Jim Wickens, Andy Cole, John Pekrul

"The roaster facility at Barrick Goldstrike Mine treats double-refractory sulfidic/carbonaceous gold ore. Prior to oxidation in the roasters, the ore is ground in two parallel dry grinding circuits utilizing 19’ Ø x 75’ double rotator mills. The design plant throughput was 12,000 dstpd. However, process improvements have significantly increased throughput rates by 25-50%. The current daily throughput record is 20,078 dstpd. Grinding circuit improvements contributing to this success include feed size reduction, ball size optimization, automatic ball charging optimization, and operating strategy changes. In addition to the changes already made, this paper discusses future optimization initiatives including on-stream particle size analysis and “real-time” ore hardness determination techniques.INTRODUCTIONBarrick Goldstrike Mines is located 29 miles Northeast of Carlin, Nevada, USA. Through 2001, the property has produced over 23 million ounces of gold making it one of the premier gold operations in the world.Prior to Barrick’s ownership, the property began producing gold from a small heap leach operation in 1975. The small-scale heap leach production continued through 1986, and in January 1987, Barrick acquired the property. Increased exploration activity by Barrick significantly increased gold reserves. In August 1988, a 4,500 dstpd mill facility was commissioned to treat high grade oxide ore. Also, heap leach operations had significantly expanded. In 1990, the mill was expanded to 6,000 dstpd, and the first autoclave was commissioned to treat refractory sulfide ore. By the end of 1996, the mill and pressure oxidation facility had expanded to 16,000 dstpd and heap leaching had ceased as oxide reserves were exhausted. In 2000, a roaster facility was commissioned to treat double-refractory sulfidic/carbonaceous ore."

Jan 1, 2003

By Bernard Dallaire, Jean Cayouette, Sylvain Duchesne

"Louvicourt Mine's concentrator, located near Val d'Or, Quebec, treats an average of 4,300 tonnes of ore per day composed mainly of copper, zinc, gold and silver. An analysis of concentrator revenues and metallurgical losses shows a potential for additional gain, particularly in regards to precious metals (kustelite) where recovery is usually around 67 -70 %. The planning, installation and trial operational period of two Outokumpu SK-240 flash cells at the underflow of the primary cyclones took two years. The use of (( flash flotation )) technology has made it possible to exploit the favourable conditions at the underflow of the primary cyclones such as precious metal concentration and the presence of liberated coarse chalcopyrite. These conditions permit early flotation (fresh surfaces) of the kustelite and the liberated copper. Since the start-up of the flash cells, the metallurgical gains have turned out to be very positive with increases in metal recovery reflected in appreciable NSR gains. Also, significant savings in reagent consumption and a coarser copper concentrate have made it possible to reduce the drying cycle of the Larox filter presses since the cells were put into operation.BACKGROUNDLouvicourt Mine is operated by Aur Resources Inc. (30% ownership) on behalf of its partners Novicourt Inc. (45%, subsidiary of Noranda Inc.) and Teck Corp. (25%). The mine is located in northwestern Quebec about 600 km north of Montreal and about 25 km east of the mining town of Val d'Or. The mine commenced commercial production in July 1994.The massive sulphide ore deposit lies at depths varying between 450 m and 900 m. Mining reserves (2% Cu equi. cut-off) as of Jan. Is', 2000 are estimated at 7.5 million tonnes of ore averaging 3.4% Cu, 1.8% Zn, 28.0 g/t Ag and 0.9 g/t Au. Delineated ore reserves permit the use of a mechanized transverse blasthole mining method. The extraction order is a typical 1.3.5 mining sequence. Primary and secondary stopes are 15 m wide, 15 to 70 m long (25 m long average) and 30 m high. Backfilling for pillar recovery and regional stability is required."

Jan 1, 2001

By Jean G. Fortin

The manufacturers&apos; proposed technology has been a key factor in selecting production, mobile and fixed equipment in order to achieve the targets set in our 2026 mining plan. This paper will present an overview of the most recent technologies adopted by Québec Cartier Mining Company for communications, power supply, dewatering, drilling, loading, hauling and processing. All these new technologies contribute to the improvement of our day to day operations while operating with a state of the art asset reliability program.

May 1, 2007

By Sunil Koppalkar, Guillaume Noel, Ahmed Bouajila, Makni Sami, Claude Gagnon

"Gold gravity recovery circuits utilizing enhanced gravity separators have become an integral part of many of the modern gold processing plants. Thus, efforts to improve the operating efficiency have been a topic of interest for metallurgists for many years. As part of this endeavour, a methodology to estimate the portion of gold in the ore that could be recovered by gravity separation (gravity recoverable gold or GRG) was developed at McGill University. It has been reported in the literature that the gold content estimated with this methodology is the theoretical maximum that is available for gravity recovery that could only be approached but never achieved. A comparison of GRG recovery obtained in the laboratory with the actual recovery in the plant shows that plants recover between one-third to two-thirds of the value predicted by the laboratory test.Research conducted at COREM shows that particle shape transformation during grinding is a major cause of the discrepancy (even though the bleed percent processed, the quality of cyclone classification and the operating conditions of the gravity separator also contribute to the difference). To analyze the gold particle shapes and their deportment, samples were collected from different streams of a grinding-gravity circuit in a gold plant and compared to a concentrate sample from the standard GRG test. A particle characterization methodology based on gold morphology was developed. GRG mapping in a conventional grinding-gravity circuit and the transformation of GRG into non-GRG, as mainly explained by gold particle reshaping, will be discussed. The knowledge gained from the shape analysis will be used to develop shape distributions and partition curves for the classification of shapes.INTRODUCTIONGravity concentration using centrifugal concentrators has gained increasing popularity since the invention of the enhanced gravity concentrators in the nineteen eighties. Among these, the semicontinuous centrifugal gravity concentrators are most commonly used for recovering gold and platinum group minerals (PGM) from grinding circuit streams. The benefits of gold gravity recovery are now well understood and the acceptance by the mining industry is overwhelming. The occurrence of reasonable amounts of gravity recoverable gold (GRG) in an ore prompts gold mills to install gravity circuits. Thus, the increased use of gravity concentration has necessitated a better understanding of the behavior of gold in grinding circuits and of the factors affecting the performance of the gravity concentrator (Laplante et al., 1995). Due to its high density (19.3 g/cm3 when pure) and malleability properties, gold tends to accumulate in circulating streams making it attractive for gravity recovery. The gravity recovery units are typically installed on a bleed stream of the cyclone underflow, mill discharge or cyclone feed."

Jan 1, 2011

By Nicholas Macrae Steven

Abstract - The Shaba-type Luamata Cu-Co(-Ni) deposit (11°50_S, 24°28_E) is located in a tectonic slice of Katangan Roan Supergroup (Mines Group) sedimentary rocks, surrounded by younger Kundelungu Supergroup lithologies in the external fold and thrust belt of the Lufilian Arc. Luamata is a classic central African copper clearing in dense woodland, visible as a tonal botanical anomaly on Landsat imagery. Supergene Cu-Co mineralization (especially malachite and subordinate chalcocite, digenite, covellite, and copper and cobalt oxides) and, probably hypogene, bornite, and chalcopyrite are hosted by altered, but essentially unmetamorphosed, moderately dipping, dolostones and dolomitic shales. Alteration products include talcose dolomite, sericite rocks and intense silicification and brecciation. Friable yellow shale is best mineralized with cobalt (up to 0.43 wt%), whereas, highest copper grades occur in brecciated, silicified shale (up to 13.5 wt% CuO). Soil copper and cobalt contents are up to 2.2 and 0.6 wt%, respectively. A newly identified nickel zone (where soil contents exceed 0.1 wt% Ni) fringes the Cu-Co deposit. Polymictic, matrix-supported breccias with a calcareous matrix that underlie the Cu-Co deposit are interpreted to be fluidization breccias related to thrust tectonics and the emplacement of the Mines Group slice. Although small compared to the Kolwezi district Shaba deposits in the Democratic Republic of the Congo, Luamata exhibits all the classic features of an ore deposit type (with low calcite contents), whose high metal concentrations could potentially be very profitably exploited by low-cost opencast mining and hydrometallurgical recovery methods.

Jan 1, 2000

By Manqiu Xu, Glen Robertson, Steve Wilson, Pete Quinn

"The middlings circuit, once called the pyrrhotite rejection circuit, at Inco’s Clarabelle mill was a single flotation stage. It used to process a combined feed consisting of the main flotation scavenger concentrate and the non-magnetic portion of the magnetics flotation circuit tails. The typical circuit metallurgy was 55% nickel recovery at 6.5% Cu+Ni concentrate grade. In the past few years, a research project with the objective of improving the circuit metallurgy was initiated between Inco’s research laboratory and the Mill’s Process Technology group. This project has gone through three steps: a) initial laboratory studies, b) on-site pilot plant investigation, and finally c) full plant implementation.The present paper describes the initial laboratory test work. The development of a two-stage circuit consisting of separate rock and pyrrhotite rejection stages to replace the simultaneous rejection of both rock and pyrrhotite in a single stage is discussed. A two-stage circuit simulation based on batch laboratory flotation data is also presented. Further development work, including the on-site pilot plant test work and the plant implementation of the new circuit design, will be described in a later publication.INTRODUCTIONThe milling operation at Inco’s Clarabelle mill, Copper Cliff, Ontario processes a rich complex sulfide ore from several large production mines around the Sudbury basin (Agar, 199 1). The sulfide mineralization is simple, consisting of chalcopyrite (Cp), pentlandite (Pn) and pyrrhotite (Po). The main gangue minerals are pyroxene, feldspar and quartz with minor amphibole and talc. Estimates of mineral composition are routinely calculated from Cu, Ni and S assays. In the mineralogical calculations, all gangue minerals are conveniently grouped and treated as rock (Rk)."

Jan 1, 2000

By K. D. Hester

"1.0 INTRODUCTIONThe uranium industry started in Canada with the reopening of the gravity concentrator at Eldorado's Port Radium mine in the North West Territories in 1942. In 1948, uranium exploration and processing was opened to the private sector, and the Federal government offered special pricing incentives to the industry. Eldorado explored the Lake Athabaska deposits in northern Saskatchewan, and in 1953 opened the Beaverlodge mine. Other mines in the area soon followed. In 1953 also, the deposits in the Blind River - Elliot Lake area and in the Bancroft area of Ontario were discovered. Mines and mills were quickly developed in these areas.Canadian uranium production peaked at 15,900 short tons of U3O8 in 1959. In that year, uranium exports at $300,000,000 exceeded those of all other minerals in value. On October 1, 1959, Canadian uranium operations employed 13,900 people.Up to 1956, it was a seller's market. By 1958, world production of uranium was far ahead of requirements. Accordingly, in November of 1959, the USAEC announced it would not renew it's options for continued delivery of uranium from Canadian mines. This led to the ""stretchout"" of existing uranium contracts, and many mines were shut down (see Table 1) .In the early 1970's, a commercial uranium market seemed to be developing. In Ontario, at Elliot Lake and Bancroft, mines reopened. But competition was coming from the Athabaska basin of Saskatchewan. Currently it is these high grade, open pit deposits of northern Saskatchewan which are in the forefront of Canadian uranium developments. Canadian developments since 1942 reflect the political and market forces, as well as metallurgical progress and changes in environmental standards. This paper attempts to show these process changes in broad perspective."

Jan 1, 1987

By R. D. Lawrence

"Comparable transaction analysis is the best known of the market approaches to valuation of exploration-stage mineral properties. The analysis of option and farm-in agreements can also provide useful guidance to valuators. While such approaches can be distorted by incomplete analysis, market-based methods are capable of providing consistent, credible results when carried out carefully with due consideration paid to all factors which buyers and sellers consider when dealing in the real market. IntroductionMineral properties without defined resources present one of the most challenging tasks to the mineral valuator. This paper will concentrate on market-based approaches to valuation of such properties. Other authors at MM2000 presented papers on cost and income approaches. Sorentino (2000) also provides a useful overview with some provacative commentary on methods.Market based-approaches are based on the principle of substitution and include such techniques as: comparable transaction analysis (sometimes referred to as sales comparison analysis); farm-in commitment (or option agreement) analysis; rules-of-thumb; and comparable market value analysis.Are there any valuation standards available to assist the valuator? In Canada there are none that apply to the valuation of mineral assets or securities. This problem is being addressed, at least in part, by the CIMVal Committee of the Canadian Institute of Mining, Metallurgy and Petroleum (CIM)1. Further, the recently established Canadian Association of Mineral Valuators will be giving consideration to the adoption of valuation standards."

Jan 1, 2002

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