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By Michel Gauthier, Jacque Trottier

"ForewordA symposium on base metal deposits was held in Bathurst, New Brunswick, from June 10-13, 1990, sponsored jointly by the Geological Surveys Branch of the New Brunswick Department of Natural Resources and Energy, the New Brunswick Prospectors and Developers Association, and the Geology Division of the Canadian Institute of Mining, Metallurgy and Petroleum. Papers prepared for the symposuim are being published as a series of articles in the CIM Bulletin. This third paper (the first was by Fyffe, et al., in Vol. 83, No. 938, the second is in this issue) in the series presents an overview of the tectonic setting and geochemistry of base metal deposits in the Eastern Townships of Quebec.ABSTRACTIt is well known that the classification system of volcanogenic massive sulphides (VMS) is based upon their metal content. This metal content, the result of hydrothermal solutions circulating within strata underlying the deposits, is generally thought to be related directly to two parameters: (1) the nature of the underlying stratigraphic sequence; and (2) the physico-chemical conditions that existed at the time of the hydrothermal event. Furthermore, these two parameters are, in turn, related to the tectonic setting. One must bear in mind that these parameters are diachronous and evolve with time. These factors are considered in our analysis of the major VMS deposits of the southeastern Quebec Appalachians. This analysis will describe the time and environment of formation of these deposits and integrate them into an evolving paleotectonic model.VMS deposits in the southeastern Quebec Appalachians formed during three distinct metallogenic episodes. During the first episode, which involved early closing of the Iapetus Ocean and associated destruction of oceanic crust by subduction processes(Early Ordovician?), cupriferous VMS deposits hosted by pillowed, mafic (boninitic) lava flows were formed in immature island-arc systems (""Cyprus-type"", e.g. Huntingdon deposit).In the second episode, which also occurred during the closure of Iapetus but at a later stage (Early to Middle Ordovician), mature island-arcs formed and hosted polymetallic VMS deposits (""Kuroko-type"", e.g. Eustis deposit).Finally, during culmination of the Taconic and/or Acadian orogenies (Middle Ordovician and/or Devonian), transtensional basins, associated with tholeitic to transitional mafic volcanism began to develop. Major sedimentation occurred contemporaneous with volcanism, and within this framework polymetallic VMS deposits were formed (""Besshi-type"", e.g. the Memphremagog deposit).Although incomplete, the proposed paleotectonic model represents the sequence of the tectonic settings that prevailed during the formation of the VMS deposits of the southeastern Quebec Appalachians."

Jan 1, 1991

By A. A. Burgoyne

"The McDame chrysotile asbestos deposit located near Cassiar in northern British Columbia isfound at depth and on trend to the southeast of the currently mined open-pit Cassiar asbestos deposit. The ultramafic rock hosting the McDame is serpentinized peridotite of the Upper Paleozoic Sylvester Group contained in an ophiolitic sequence preserved within a lower thrust sheet of the Sylvester Allochthon. The Sylvester stratigraphic package is a series of thrust slices composed of argillite, tuff and volcanic flows, diorite and serpentinite. Contacts between units are often fault-controlled.The McDame asbestos-bearing ultramafite is considered to represent a separate interleaved fault-bounded slice of rock distinct from the Cassiar asbestos deposit.Asbestos mineralization of the McDame deposit was discovered in /978. Exploration during /980 and /98/ focused on extensive underground drilling of the deposit and in /983 on geological mapping, airborne and ground magnetic surveys. In /984 a 622.5 m borehole was drilled with a 242 m intersection of McDame ultramafite of which the lower 15/ metres contain potentially economic chrysotile asbestos. The McDame deposit averages 90 m thick, trends north-south, dips easterly and plunges southeasterly. The deposit is estimated to contain geological reserves in the order of 62 million tonnes containing asbestos fibre similar in value to the Cassiar deposit.The McDame is considered a major world-class asbestos deposit. A decision to develop and mine the deposit will require further substantial underground exploration and evaluation. A + 1200 m exploration adit driven to the hanging wall of the deposit was undertaken in 1985 in anticipation of bulk sampling and diamond drilling in 1986."

Jan 1, 1986

By W. Petruk, D. R. Morris

"The lead concentrate produced from the volcanogenic base metal ore of Brunswick Mining and Smelting in New Brunswick contains major to trace amounts of iron, zinc, cadmium, arsenic, antimony, copper, silver, selenium, tellurium, bismuth, sulphur, tin, indium, mercury and manganese as impurities. When the concentrate is sintered some of these impurities enter a variety of oxide phases, whereas others precipitate as metals. In the lead blast furnace the oxide phases decompose and the impurities recombine 10 form new phases, most are eventually discharged to the slag. The metals of the sinter remain as metals in the lead blast furnace where even more are produced, and are discharged largely with the lead bullion,IntroductionMany lead concentrates are produced from volcanogenic base metal ores . Such ores contain a wide variety of trace minerals and trace elements , therefore, concentrate s obtained from them will contain the trace elements as impurities . The impurities in the lead concentrate from one such ore, the Brunswick No. 12 deposit of Brunswick Mining and Smelting Corporation (BM S) in the Bathurst area in New Brunswick , were studied as pan of a larger investigation that was conducted to determine the extent of chemical reactions of the sinter within the lead blast furnace(1,2) The lead concentrate was investigated to identify the host mineral s for the impurities, the lead sinter was studied to identify the host phases, and frozen products from different depths within the BMS blast furnace at Belledune, New Brunswick were studied to determine the behaviour of the impurities.T he investigation was performed by pre pa ring polished sections o f the samples and studying them with a reflecting microscope, a scanning electron microscope (SE M) equipped with a Kevex energy dispersive X-ra y analysis system, a microprobe, and a Quantimet 720 image analyzer. The samples were also analyzed by X-ray diffractometer, and individual grains were analyzed by the Debye-Scherrer X-ray powder film method."

Jan 1, 1985

By Philip Peck

Mine closure issues ?Narrow issues: ?Environmental focus; ?Broad issues: ?Social issues and sustainability; ?Continued importance of mining; ?Historical legacies from closed mines; ?Barriers to development; ?Migration [ir]reversibility Dealing with closure issues ?A matter of choice ?Option 1: Engagein solving closure problems as best possible; ?Option 2: Exit, leaving the playing field to firms not interested in solving problems ?Option 3: Delay, till better time to enter or until early entry [by others] fails and pick property up cheap [?].

May 1, 2006

By Brian Mattie

Overview ?Overview of the mining area ?Description of the mining phases ?Risk assessment ?Design criteria and description for freeze drifts ?Freeze wall design ?Raisebore mining Four Main Phases: 1.Development of freeze drifts on the 520 and 590 levels 2.Freeze drilling and ground freezing to isolate the Zone 4 North ore body from water bearing sandstone. 3.Develop raisebore and extraction chambers including access drifts and ramps under freeze protection. 4.Start raisebore production mining of the Zone 4 North area.

Nov 1, 2011

By A. L. Mular

"IntroductionSince the mid -1960s, automatic control of grinding circuits has become the rule, to avoid losses attributable to frequent circuit upsets associated with uncontrolled disturbances such as ore hardness variations. Higher capital costs of grinding equipment and corresponding operating costs-especially with respect to energy consumption-are major factors that continue to stimulate interest in grinding control.Grinding circuit control strategies depend upon the control objectives defined by the processing plant and are subject to constraints such as: maintain final per cent solids within some range, do not transport steel ball s out of the discharge trunnion, or do not overflow or empty the pump box and so on. Constraints depend on the nature of equipment employed within the grinding circuit and may actually determine the characteristics of the control scheme. Typical control objectives are:1. Maintain final particle size at set point by ,a. manipulation of fresh feed rate with circulating load maintained by manipulation of pump box water addition rate, orb. manipulation of pump box water addition rate with circulating load maintained by manipulation of fresh feed rate, where the methodology utilized to accomplish either (a) or (b) is dependent upon equipment/circuit constraints such as the availability of a variable speed pump.2. Maintain circuit throughput at a maximum by,a. manipulation of fresh feed rate subject to constraints on final particle size and variables such as power draw, circulating load and mill overload.3. Maintain mill load at set point by a. manipulation of fresh feed rate subject to constraints such as on power draw.4. Maintain mill power draw at set point bya . manipulation of fresh feed rate subject to mill load constraints. Often, a grinding control objective is dictated by the recovery vs fineness-of-grind characteristic that exists for downstream separation circuits. When recovery is relatively insensitive to size, maximum throughput in the grinding circuit is advantageous.The purpose of this paper is to review control strategies for primary ball mill grinding circuits, rod mill/ball mill grinding circuits and semi-autogenous grinding mill circuits. Primary sensors employed are highlighted and modern trends are documented briefly."

Jan 1, 1989

By R. Pelletier, Herny. E., C. Allaire

Corrosion of refractory linings by molten metals is controlled by interactions between penetration and chemical reaction. Corrosion of aluminosilicates by molten aluminium is no exception. The early stage of corrosion can be described as a particular case of reactive wetting over a porous medium. Although the reactivity between aluminium and silica is great, which should improve wetting and penetration, the presence of air and the formation of a protective oxide layer disfavours initial penetration. This paper presents the results of an exploratory study on the effect of some parameters on the initial stage of aluminium penetration. Penetration kinetics and metal intrusion tests have been performed on alumina and silica powders with pure aluminium and Al¬5%Mg. Capillary models are used as tools of interpretation. Penetration kinetics tests had a poor reproducibility and the kinetics itself can not be explained very well by the capillary-tube-bundle model. On the other hand, a capillary model initially developed for ice intrusion into freezing soils produced predictions in reasonably good agreement with intrusion pressure measurements. The effect of particle size and alloy composition can be predicted using this model. However, the effects of temperature and powder chemistry need additional interpretations to be rationalised. An unusual resistance to penetration of silica powder by molten aluminium have been observed in a series of experiments. This led the authors to the strange conclusion that oxygen should be seen as an excellent non-wetting agent and that there might be ways to use it in industrial applications.

Jan 1, 2004

By G. S. Dobby, J. A. Finch

"A significant development in froth flotation technology has been the emerging industrial acceptance of column flotation during the past few years. Flotation columns are being employed now in several Canadian base metal concentrators and they are being considered f or a wide range of flotation applications throughout North and South America. Since the operating principles of a column differ markedly from those of conventional flotation machines, and have been poorly understood, scale-up of columns has been difficult. This paper describes a methodology f or translating laboratory column data to industrial operation.The scale-up model utilizes kin etic data that is obtained from a series of laboratory column experiments; the laboratory column can be as short as 2 m. For modelling purposes the column is considered to consist of two zones: the collection zone, where particle recovery occurs, and the cleaning zone, a packed bubble bed generated by downward flowing wash water. Mixing conditions in the collection zone have been characterized using the results of tracer experiments on plant columns at Mines Gaspe. The same experiments demonstrated the nearly complete suppression of entrained gangue minerals that is attained in the cleaning zone. The model explicitly accounts for both the collection zone and cleaning zone recoveries and allows for the effects of bubble overloading. Results of column scale-up experiments at Gibraltar Mines are presented."

Jan 1, 1986

By Gene O. Cowie

"Zinc, which once enjoyed an unchallenged position in the field of decorative applications, has lost a substantial share of its markets to other materials, particularly plastics. This turn of events has led the zinc industry to explore new market areas, particularly those applications where the engineering properties of zinc can be utilized. This paper gives an overview of the zinc industry's efforts to develop the data base and product development technology which have enabled zinc alloys to emerge as engineering materials. It also indicates those areas in which the research facilities of the zinc industry must be employed to ensure that zinc alloys keep pace with developments in competitive materials and processes.The Materials RevolutionThe development and utilization of new materials and manufacturing processes progressed for centuries by evolution. Recently it erupted into a revolution, which may become as significant as the industrial revolution. The materials revolution has impacted upon many industries, but none has been affected more traumatically than the North American automotive industry. The plight of that industry is of great importance to us because their problems have, to a great degree, become problems to the zinc industry.Much of the impetus behind the automotive trauma came from the battery of motor vehicle regulations promulgated by the United States government in the 1970s. These regulations required that the efficiency of passenger cars, in terms of miles per gallon, be approximately doubled in ten years. In view of the fact that major changes in the automotive world require three years of lead time to implement, the industry was left with only seven years to perform the task. The automotive industry was simultaneously required to make progress in other areas, such as reduced emissions, reduced cost of repairs and increased levels of occupant safety. These added demands not only diverted some of the available resources away from efficiency goals, they often ran in direct conflict. For example, when you are required to provide a front bumper which will absorb the energy of a 5-mile -per-hour barrier collision, you must add both hardware and structure to the vehicle. This adds weight, and increased weight reduces miles per gallon."

Jan 1, 1983

By John De La Vergne, Morri Medd

"This paper describes the sinking of a circular concrete ventilation shaft through 110feet of water-bearing overburden. The brine circulation freezing method was used to stabilize the walls during excavation. In order to take advantage of the cold winter weather, a custom-built heat exchanger (natural radiator) was installed in place of the standard mechanical refrigeration plant.IntroductionIn the late fall of 1979, Les Mines Selbaie awarded a contract to the firm of 1.S. Redpath Limited to sink a ventilation shaft on its property in northwestern Quebec. The shaft was to be sunk through 110 feet of water-bearing overburden and approximately 90 feet of rock to a final depth of 200 feet below surface. The water table was measured at 16 feet below the surface elevation.After examining the soils report and diamond drill core from the shaft area, Redpath came to the conclusion that freezing was the best way to stabilize the overburden for sinking. LocationThe mine site is 420 statute miles due north of Toronto, just east of the Ontario/Quebec border (Fig. 1). Access to the site is provided by a development road built by the Quebec government from the Matagami/lames Bay Highway. History of Ground Freezing In the Mining IndustryIn 1862, shortly after the development of mechanical refrigeration, a mine shaft was sunk through an artificially frozen water-bearing formation in the United Kingdom. The first application of ground freezing in North America was for a Michigan iron ore shaft in 1888. Since that time, the freezing method has been used to sink hundreds of shafts throughout the world. Its best known application was to sink sixteen shafts through the Blairmore Formation in Saskatchewan.The same method has been used in every case. It involves chilling a calcium chloride brine solution and circulating the brine in concentric pipes, spaced between 3 and 6 feet around the shaft perimeter and usually 4 to 5 feet from the limits of the proposed shaft excavation."

Jan 1, 1982

By P. R. Goad

"Kidd Creek is a large volcanogenic base metal sulphide deposit, located near the west end of the Abitibi greenstone belt, 27 km north of Timmins, Ontario. The rhyolite geology is characterized by a NNE-striking and steeply east-dipping package of rhyolite volcaniclastics upon which has been imposed a strong ESE-striking and north-dipping structural fabric . Massive rhyolite units with grey-black. chloritic cores and yellow, sericitic margins intrude as dykes into the stratigraphic footwall and as sills higher in the stratigraphy. Massive rhyolite units positioned near the top of the felsic pile exhibit an extensive marginal development of hydraulic fracturing and are termed crackle-brecciated rhyolite.The stringer sulphide zone is positioned in a lobate blanket of crackle-brecciated rhyolite at the top of the felsic pile. The stringer sulphide zone is characterized by a mature chemical alteration, being specifically depleted in alkalis and enriched in iron-rich chlorite. with accompanying silica, sericite and carbonate alteration. A suite of trace elements characterizes this mature alteration. The massive rhyolite units, which intrude lower in the rhyolite volcaniclastics, exhibit a core of weak chlorite alteration and strong marginal sericite alteration. Tight or unfractured massive rhyolite units are essentially devoid of sulphide mineralization and exhibit a suite of trace elements characteristic of this immature alteration. It is interpreted that the massive rhyolite units intruded into an already evolving system and ""choked-off"" active conduits carrying hydrothermal fluids and subsequently acquired an immature alteration signature. Rhyolite units positioned higher in the pile developed intense hydraulic fracturing and a mature alteration coincident with the formation of the stringer sulphide zone. In summary, a model, based strictly upon the rhyolite geology, is reviewed to assist in the exploration for volcanogenic base metal sulphide deposits."

Jan 1, 1985

By J. Zollinger, J. R. Kennedy, E. Bouzy, B. Rouat, D. Daloz

"Ni-based superalloys have been replaced in the last low pressure stage of jet turbines for aircraft by titanium aluminides. In order to improve the properties of these Ti-Al alloys and extend their usage deeper into aircraft engines grain refinement by inoculation has been investigated. Borides are the most common inoculants for Ti-Al alloys, however they form brittle particles which are detrimental to the final properties of the alloy. Inoculants manufactured from a Ti-Al alloy with refractory metal additions were proposed to alleviate the issues arising from inoculation with brittle particles. An alloy was chosen which had less than 10% lattice mismatch with the alloy of interest (Ti-46Al) to maximize efficiency. Initial experimentation showed a decrease in as-cast grain size by a factor of 2 between the inoculated and non-inoculated samples along with an absence of the brittle particles found with boron inoculations. Investigations into the interaction between the inoculants and the melt were also carried out to better understand the inoculant size distribution and efficiency upon solidification.INTRODUCTIONTitanium aluminum alloys are an interesting material for aerospace applications. Their high temperature oxidation resistance and high specific strength make them particularly promising (Kim & Dimiduk, 1991). Recently, titanium aluminides have replaced nickel based superalloys in the last low pressure stage of the GEnx turbine engine. In order to increase their usefulness in turbines their properties must be improved for high temperature (>800oC) applications. Grain refinement is one method to improve the properties of a material, however current methods of grain refinement of Ti-Al alloys by inoculation have significant drawbacks. A new method of inoculating Ti-Al alloys by using Ti-Al alloys with small refractory metal additions (Nb, Ta) has been developed to avoid the drawbacks of current methods while still being effective grain refiners."

Jan 1, 2016

By David L. Anderson

"The objective of this paper is to describe the potential impact of inter-provincial competition f or new output capacity on the Canadian potash industry. It will be shown that the ramifications of such actions are potentially severe, especially since the potash industry is one of the few non-fuel minerals in which Canada purportedly possesses a significant degree of market power. More specifically, the paper addresses the impact of possible expansions in New Brunswick, Manitoba and, perhaps, Saskatchewan. The findings suggest that such initiatives could result in substantial excess capacity and the dissipation of monopoly rents. In summary, given the market structure of the industry, it is unlikely that the employment and economic effects associated with industry expansion will offset the loss in national welfare attributable to rent dissipation.IntroductionThe objective of this paper is to discuss the potential impact of inter-provincial competition for new output capacity on the Canadian potash industry. The ramifications of such competition are potentially severe: given that the potash industry is one of the few non-fuel minerals in which we purportedly possess a significant degree of market power(1), it is important that sound supply management practices are followed. However, possible initiatives by New Brunswick, Manitoba and, perhaps, Saskatchewan may initiate an inter-provincial competition which could result in substantial excess capacity and the dissipation of economic rents(2). Given the market structure of the industry, it is not intuitively obvious that the employment and economic effects associated with industry expansion will offset the loss in national welfare attributable to rent dissipation."

Jan 1, 1985

By D. M. Ward, J. H. Ahrens

"The Fond-du-Lac uranium deposit was delineated primarily by percussion drilling and a small program of diamond drilling. Drillcore samples from three diamond drill holes as well as digitized gamma logs from percussion and diamond drill holes were utilized to define and implement an algorithm for the conversion of gamma-log data to equivalent-grade data. The procedures and detailed analysis for the provision of assay data for uranium reserve estimation are documented.IntroductionThe Fond-du-Lac uranium deposit is on the south shore of Lake Athabasca, approximately 2 km southeast o f Fond-du-Lac , northern Saskatchewan. It is on the northern rim o f the Athabasca sandstone basin.A train of mineralized glacial erratics was discovered in 1967 by Farnok, Limited by means of a helicopter-borne radiometric survey. In 1969, a program of diamond drilling by Famok was successful in locating in-situ mineralization in the Athabasca sandstone at the apex of the mineralized boulder train. Since 1974, exploration and development work have been performed under a joint-venture agreement between Eldorado Nuclear Limited and Famok Limited, with Eldorado acting as operator.From the discovery drill hole to the development of the gamma-log to equivalent-grade con version algorithm, the deposit had been tested by a total of 222 drill holes, 210 of which were percussion holes and 12 of which were diamond drill holes. The holes are generally vertical and collared at 10-metre centres on fences spaced 20 metres apart. The deposit is approximately 390 metres long, 10 to 40 metres wide and up to 45 metres deep, and is generally confined to the Athabasca sandstone. Uranium occurs as pitchblende, coffinite and uraniferou s goethite."

Jan 1, 1983

By R. L. Armstrong, C. I. Godwin, V. M. Kruan

"The Scheelite Dome tungsten-bearing skarn property, central Yukon Territory, is in metasediments in contact with a quartz monzonite intrusion. Contact metamorphism to biotite-muscovite- andalusite hornfels and calc-silicate hornfels is superimposed on low-grade regionally metamorphosed rocks represented by quartz-mica pelitic schist and muscovite-biotite pelitic schist.Metasediments are likely Precambrian in age, even though Rb-Sr whole-rock analyses indicate an early Paleozoic age (511±41 Ma); this apparently too young radiometric age is due to partial loss of radiogenic strontium during regional metamorphism. The minimum age of the quartz monzonite intrusion is Cretaceous at 90.4±2.6 Ma (K-Ar on biotite) and its initial 87Sr/86Sr ratio is 0.7121. The high initial ratio of the intrusion is due to the addition of radiogenic strontium from the metasedimentary country rocks and perhaps an underlying older basement.Scheelite-pyrrhotite-chalcopyrite mineralization occurs in diopside-zoisite skarn pods within the calc-silicate hornfels near the quartz monzonite intrusion. The source for lithophile tungsten is probably the same as for the granitic magma, namely Precambrian sialic basement.IntroductionThe Scheelite Dome tungsten skarn property is within the Mc-Questen map-area (NTS: 115P/16),28 km northwest of Mayo, Y.T., at latitude 63°47' north and longitude 136°15' west. The property can be reached by helicopter or by four-wheel- drive vehicle from Mayo.This paper summarizes the geology of the Scheelite Dome property, which has been described in a general way by Little (1959) and Cathro (1969). Geological mapping and sampling were done by the first author (nee Steffler) during June 1979. Field work was supplemented with detailed work at the Department of Geological Sciences of The University of British Columbia during 1979 and 1980 (Steffler, 1980). Whole-rock chemical analyses were done by Cominco Ltd."

Jan 1, 1982

By M. J. Michaud, M. J. Lavigne

"Abstract - North American Palladium Ltd. operates its Lac des Iles open pit palladium mine 85 km north of the city of Thunder Bay, Ontario. The Roby Zone deposit occurs within the mafic/ultramafic Lac des Iles Intrusive Complex (LDI-IC), which was created by multiple pulses of magma of varying composition within several closely spaced chambers. Chaotic lithological distribution, the presence of magmatic breccias, and the rarity of rhythmic layering suggest a dynamic intrusive environment with disruptive magma pulses. As of December 31, 2001, measured and indicated resources for the 950 m long by 815 m wide Roby Zone deposit totalled 159 Mt grading 1.55 g/t Pd, 0.17 g/t Pt, 0.12 g/t Au, 0.05% Cu, and 0.05% Ni at a palladium cut-off grade of 0.7 g/t. The Roby Zone contains an additional 73 Mt of inferred resources at similar grades.The Roby Zone is dominated by varitextured gabbro containing pipes and pods of breccia, and large blocks (~60 m across) of varying lithology. Mineralization at Lac des Iles occurs as: (1) a PGEand base metal-rich magmatic matrix of breccia (breccia ore); (2) mineralized dikes or sills (gabbronorite in North Roby ore); (3) lower-grade mineralization in varitextured units that are host to the distinctive breccia ore and envelope the North Roby ore; and (4) high-grade mineralization associated with strong silicate alteration exemplified by high-grade ore.The close spatial association of the mineralized breccias with both varitextured units and silicate alteration leads to an interpretation that the energetic magma that created breccia was charged with a dissolved fluid, and that this deuteric fluid exsolved at high temperatures to migrate through crystal mush, enhancing crystallization along its pathways, resulting in variable grain size. This transformation occurred at high temperature and produced sulfide-poor, varitextured gabbro-hosted mineralization exemplified by some of the mineralization in the North Roby Zone, and also found throughout the Roby Zone. The association of hydrous silicate alteration with mineralization can be explained by continuing fluid migration during cooling and continued metal transport. Résumé - North American Palladium Ltd. opère la mine à ciel ouvert de Lac des Iles située à 85 km au nord de Thunder Bay, Ontario. Le gisement Roby Zone est encaissé dans le complexe mafique/ultramafique de Lac des Iles (LDI-IC), lequel représente une intrusion polyphasée créée par plusieurs pulses magmatiques de différente composition à l’intérieur de chambres magmatiques fermés. La distribution chaotique des lithologies, la présence de brèches magmatiques, et la quasi-absence de litage rythmique suggèrent un environnement magmatique dynamique perturbé par l’introduction de nouveau magma. Au 31 décembre 2001, les ressources mesurées et indiquées s’élevaient à 159 millions de tonnes titrant 1,55 g/t Pd, 0,17 g/t Pt, 0,12 g/t Au, 0,05% Cu, et 0,05% Ni, pour une teneur de coupure de 0,7 g/t Pd. De plus, la Roby Zone contient 73 millions de tonnes de ressources inférées à une teneur similaire.La Roby Zone est principalement encaissée dans un gabbro de texture hétérogène (varitextured) caractérisé par des cheminées et des lentilles de brèches et des énormes blocs (environ 60 m de diamètre) de plusieurs lithologies. Au Lac des Iles, la minéralisation en EGP et en métaux de base se retrouve dans la matrice magmatique de brèches (breccia ore), dans des dykes ou des sills minéralisés (gabbronorite dans la zone North Roby ore), comme minerai de basse teneur encaissant le minerai de brèche (breccia ore) et enveloppant la zone North Roby. Du minerai de haute teneur est également associé avec une forte altération en silicates dans la zone high-grade ore.L’étroite association spatiale entre les brèches minéralisées et les unités de texture variée (varitextured) et l’altération en silicate suggère que le magma énergique qui a causé la bréchification était chargé de fluides. Ces fluides deutérique"

Jan 1, 2001

By D. E. M. Plaumann

"The wet grinding of asbestos has attracted the attention of engineers for many years as a means of improving fibre liberation from the ore. Today, added impetus for wet grinding has resulted from a need to minimize worker exposure to asbestos dust in conventional dry mills using air, as well as a need to provide a cleaner, technically superior fibre for use by product manufacturers. However, high viscosities of asbestos slurries create transport and grinding difficulties which have been a factor impeding use of a wet grinding process.Laboratory evaluation of reagents to reduce viscosities of asbestos slurries found that one reagent, XFS-4272.00, reduced the viscosity of a 35% (by weight) slurry by 75%. The impact of XFS-4272.00 on actual grinding parameters were evaluated using a pilot plant rod mill. Slurries containing 78% solids and XFS-4272.00 were successfully milled and asbestos fibres from that milling compared favourably in liberation and relative surface area to asbestos fibres obtained from milling a 4% slurry without additives. IntroductionAlthough the use of asbestos has been declining over the last few years, the large deposits of chrysotile in eastern Canada (Quebec in particular) remain very important. Asbestos production in Canada stands ninth in volume for mineral production with over 740 000 tonnes produced in 1985. Of this quantity, 722000 tonnes were exported with a value of $446 million. Canada is second in world production of asbestos behind the U.S.S.R. The milling of asbestos ore has been done primarily by a series of steps involving crushing, dry-grinding and aspiration using large quantities of air to release the fibres. Contrast this process to those practiced in the purification of virtually every other mineral. Ores other than asbestos are crushed and milled using an aqueous slurry in rod, ball or pebble mills. The finely ground mineral, still as a slurry, undergoes beneficiation by froth flotation, heavy media separation, hydrocyclones or any of the other aqueous techniques currently employed in mineral processing.One of the driving forces behind the use of air instead of water as a means of separating asbestos is the nature of the aqueous asbestos slurry. While most slurries of minerals contain as much as 80070 solids and can still be pumped and transported, asbestos slurries become highly viscous with as little as 10070 solids. These high viscosities reduce the pumpability of the slurry and create severe handling problems. Mills become prohibitively large and uneconomical due to having to handle slurries containing only 10% rock and 90% water.Health-related issues have affected the use of asbestos in many countries. In Canada, the asbestos-producing provinces have introduced stricter occupational legislation to improve safety in the workplace. This primarily means strict control minimizing release of air-borne asbestos fibres . Quebec and Ontario have set limitations of airborne asbestos at 2 (2) and 1(3) fibre per cubic centimetre of air. With present milling technology, maintaining these low levels in the workplace requires constant vigilance."

Jan 1, 1988

By A. P. Annan, C. Vaughan, J. L. Davis

"The increase in the price of gold in the last decade has led to a significant increase in placer gold exploration around the world. Placer deposits occur in depressions along ancient river and stream channels. In many instances these channels have been covered with materials from subsequent erosion or glacial activity. Use of high resolution geophysical techniques to map the bedrock and soil strata can improve the probability of finding the placer deposits. The buried bedrock surface is often the factor controlling deposition. Ground probing radar (GPR) and seismic sounding are complementary high resolution techniques which can be used to map bedrock topography and soil stratigraphy. Current radar instrumentation operates best in coarse grained soils. Penetration depths of up to 30 m have been attained, and stratigraphic horizons have been mapped with spatial resolutions of better than 0.5 m. Although its spatial resolution is considerably lower than radar, seismic refraction achieves superior penetration in electrically conductive environments such as clay and silt soils. The seismic refraction method thus proves to be complementary to the radar method. The seismic reflection technique is analogous to the radar method. Current seismic instrumentation and energy sources however, provide limited spatial resolution and do not permit the use of seismic reflection for reflecting horizons lying at depths of less than 20 m to 30 m.This paper discusses the use of both radar and seismic methods for placer exploration. The radar and seismic techniques, the field methods, equipment, and data displays are presented. Field examples illustrate the high resolution mapping capabilities of the techniques. The radar data agree very well with the borehole data, and in fact they sometimes detect subtle soil strata variations associated with changes of permeability that were not initially observed in the borehole logging. The radar method can give a continuous profile of water table and bedrock in sandy soils. Seismic soundings are necessary to differentiate between the bedrock and water table reflections observed by the radar."

Jan 1, 1987

By G. A. Kosick, M. Freberg, L. A. Kuehn

"Highly variable and higher than forecast lead miff feed grades were problems experienced at the Polaris Concentrator. Limited flotation capacity and poor operating flexibility prevented the plant operators from overcoming these difficulties, and resulted in grades and recoveries which were lower than necessary.Two column cells were integrated into the lead circuit in an effort to give the operators the tools they required to achieve the best grades and recoveries possible, regardless of the miff feed grade. Installation of the column cells increased lead concentrate grade from 76% to 79.3% Pb, and increased lead recovery from 9/% to 91.3% Pb.This paper reviews the design, development and operation of column flotation cells in the lead circuit at the Polaris Mine.IntroductionThe Polaris Concentrator was constructed in 1980 on a barge in Trois Rivieres, Quebec, and towed to its pre sent location on Little Cornwallis Island, Northwest Territories, about 1450 km from the North Pole. The plant presently treat s about 2800 mtpd of new feed with average feed grades of 3010 Pb, 13% Zn and 5% Fe. Current production averages 36 000 tonnes of lead concentrate and 220 000 tonnes of zinc concentrate annually.The barge design and min e location dictated that the concentrator .be compact with very little unused floor space. As a result, flexibility was limited in terms of expanding the plant.Mill feed grades were highly variable and above forecast and the lead flotation circuit was found to be under capacity. This caused continued overloads in the lead cleaning circuit, resulting in low concentrate grades and recoveries. It was evident that an increase in lead flotation capacity and flexibility was necessary. The existing floor space did not allow for the installation of additional conventional flotation cells, but one alternative was the installation of column cells."

Jan 1, 1988

By Hajime Miki, Gde Pandhe Wisnu Suyantara, Ahmed Mohamed Elmahdy, Hidekazu Matsuoka, Kyushu University, Tsuyoshi Hirajima

"Selective flotation of chalcopyrite and molybdenite was studied using various surface treatment methods such as electrolysis, ozone treatment, and plasma. Oxidation via electrolysis method indicated that only chalcopyrite surface is affected by electrolysis due to conductivity difference with molybdenite. Oxidation treatments and XPS analyses indicated that chalcopyrite became hydrophilic due to deposition of oxidized iron on its surface. Various oxidizing methods also showed that chalcopyrite was selectively oxidized and this can apply selective flotation of chalcopyrite and molybdenite. The possible mechanisms are proposed in this work based on surface analyses and thermodynamic calculations.INTRODUCTIONCopper sulphide minerals often associate molybdenite (MoS2) which is one of the most important by-products (Wills, 2006). It is important to recover molybdenite perfectly not only since molybdenite is valuable mineral, but also contamination of molybdenite into copper concentrate or contamination of copper mineral into molybdenite concentrate indicates penalty for both concentrate values (Wills, 2006). Conventional separation of copper sulphide and molybdenite has been achieved with sulphide bulk flotation followed by selective molybdenite flotation with NaHS addition since NaHS works as a depressant for copper sulphide. However, this current process shows imperfect molybdenite recovery and depressant such as NaHS needs to be used under specific flotation plant since it might be environmental contaminant. Hirajima et al., (2014) have been studied selective flotation of molybdenite and chalcopyrite (CuFeS2), which is the most important copper mineral, with plasma pre-treatment. They reported that plasma pre-treatment process followed by washing treatment can improve molybdenite floatability and depress chalcopyrite. This result is attributed to surface oxidation and selective conversion of chalcopyrite and molybdenite wettability. It may be hypothesized that another surface oxidation methods could give a similar result as plasma treatment process. To test this hypothesis, in this study, as comprehensive study of oxidation effect, various oxidation methods such as electrolysis, ozone, and plasma were investigated. Electrochemical measurements, thermodynamic calculations to predict the chemical reactions happened during the process, various surface analyses, and flotation experiments were carried out."

Jan 1, 2016