Search Documents

By J. A. Finch

Individual mineral cyclone performance curves were determined for the four major minerals at two lead-zinc concentrators. Sizing was by screen and cyclosizer down to approximately 10 um, with lead , zinc and iron as saying of each size fraction. The performance curves were similar in shape and located according to the mineral specific gravity, Pm. The curves displayed a discontinuity at the fine end and a magnitude of short-circuiting of fines to the underflow which increased with Pm. Mass fraction of water to the underflow was only a guide to this short-circuiting. Sharpness of separation seemed in dependent of Pm. An inflection in the over-all performance curve was shown to be a consequence of the individual component mineral performance. A general relationship was observed showing that the flow regime of classification changed from laminar/ intermediate to turbulent with increasing cyclone feed size. Individual mineral size reduction for the four major minerals at one of the concentrators was also determined. Size reduction of the silica was greater than that of the galena, in contradiction to their accepted relative grind-ability. The observation did correlate with silica being much coarser than the galena in the feed to the ball mill. It is suggested that the silica acted as a buffer to the galena.

Jan 1, 1977

By Charles Camsell

THE Northwest Territories covers a very large area-more than one-third of all Canada-and its most northern point, Cape Columbia in Ellesmere island, is distant only 500 miles from the Pole. Our first knowledge of the Arctic Archipelago, of which Ellesmere island forms a part, resulted from a gold-mining venture in Queen Elizabeth's reign. The English navigators of that time were eager to find a north-westerly and shorter and Jess hazardous route to the riches of China and Japan than that which Magellan had discovered, but they were unaware that the continent then known to bar a direct route extended in great width far to the north. Frobisher was one of these navigators. He reached in 1576 the bay in Baffin island now named after him, convinced that he had found a passage connecting the Atlantic with Asiatic seas. Forced to re-turn after ordeals in which ice, wind, and Eskimos flayed formidable parts, he brought back, among other novelties, a piece o black stone which had been picked up casually by one of his officers, and gave a little of it to the wife of one of the venturers, or financial backers of the enterprise. To quote now from Hakluyt: ? 'She by chance threw and burned it in the fire so long that , at length being taken forth and quenched in a little vinegar, it glistered with a bright marquesset of gold. Whereupon the matter being called in sorne question, it was brought to certain goldminers in London to make assay thereof, who indeed found it to hold gold and that very richly for the quantity." On the strength of this, the venturers, anticipating much profit, launched a second expedition to secure more of this stone, and 143 persons, including 14 miners and finers, set forth in 1577 and returned the same year, with, however, 200 tons of another mineral. Influenced by glowing accounts of veritable mountains of this mineral and by assays made after "additaments"-that is how "salting" in those days was described-the venturers, including Elizabeth, supplied funds for erecting a smelter and refinery at Dartford and outfitting a stilllarger expedition. And so, in 1578, fifteen ships departed with the Queen's blessing, for the same remote shores. After many mishaps, they returned with over 1,000 tons of the mineral, but when it yielded very little of value at the works in Dartford, the? Company of Venturers was forced into liquidation. Though our first prospector and miner was rather inconsiderate of the investors, he proved the existence of an archipelago, hitherto unknown, and secured much information about the new land and its dwellers.

Jan 1, 1938

By Ning Zhang, Yan Chen, Qikang Yi, Linjian Ma, Guoan Wang

Laboratory tests were performed to explore the effects of frequency on the deformation property of rock salt subjected to cyclic loading under confining stress condition. A two-stage (transient and steady) evolution law of axial cumulative strain was obtained through cyclic stress-strain curves complied from the loci of minimum load of each cycle. The unloading modulus decreases with loading cycles/time as a negative exponential function. The damage of rock salt under cyclic loading is reflected by the degradation of elastic modulus. A unified damage evolution equation considering the effects of frequency and time was established based on the experimental results. A new creep damage model for rock salt was proposed by introducing the non-stationary modular components in Burgers creep equation according to the Lemaitre equivalent strain theory. Comparative study indicates that the new model can accurately describe the creep deformation and damage evolution of rock salt under different loading frequencies. This paper provides a more reasonable model and relevant mechanical parameters for the stability analysis of compressed-air storage cavern in the injection and withdrawal durations.

Jan 1, 2015

By Mike Johnson, Greg Andrews, Niels Verbaan, David Dreisinger

"The Search Minerals Foxtrot project in Labrador represents a significant Canadian resource of rare earth elements rich in the sought after heavy rare earth elements (19.8% HREE/TREE). A preliminary economic assessment of the project indicated that the project is technically feasible and economically attractive. A variety of metallurgical test programs have been undertaken which have led to significant streamlining and simplification of the process flowsheet. The improved flowsheet should allow Search to reach production earlier and will use conventional processing equipment. The results of these test programs are presented and discussed in this paper INTRODUCTIONSearch Minerals Inc. (Search) is exploring and developing a number of deposits for rare earth element (REE) recovery in Labrador, Canada. The Port Hope Simpson District is in the southeast of Labrador and is highly prospective for heavy and light rare earth elements. The Foxtrot deposit sits within the Port Hope Simpson REE District (Figure 1), which is 70 km long by up to 10 km wide. The infrastructure available at Foxtrot is excellent; a deep-water port, air strip, and road and power infrastructure are pre-existing at St. Lewis. The three communities of Port Hope Simpson, St. Lewis and Mary’s Harbour are in close proximity to the site."

Jan 1, 2016

By Art Hamilton

Abstract -The Zn-Pb-Cu-Ag ore deposits of the Boundary and N-5 zones near Bathurst, New Brunswick, occur in a polydeformed volcano-sedimentary sequence that is part of the Ordovician Tetagouche Group. Massive and disseminated sulfides are hosted by an argillaceous to cherty sedimentary sequence that is stratigraphically underlain by a siliceous fragmental unit and is overlain by a feldspar-rich crystal tuff and related tuffaceous rocks. The deposits have a low iron sulfide con­ tent relative to that of most stratabound sulfide deposits of the Bathurst-Newcastle mining district. The ore is commonly associated with chlorite- and talc-rich sediments. The N-5 deposit is considered to be the fault-displaced extension of the Boundary deposit. The Boundary deposit is estimated to contain 891 000 t grading 3.310Jo Pb, 7.96% Zn, 0.32% Cu and 44 g/t Ag; the estimate for the N-5 zone is 330 000 t grading 3.24% Pb, 7.15% Zn, 0.33% Cu, and 37 g/t Ag. The ore is processed at 1000 tpd at the Heath Steele mill.

Jan 1, 1992

By J. E. Udd

A core sample for this study was taken from the sulphide ore of the Geco Mine. The subsequent research was based on the assumption that a part of the scattering of strength-grade data could be correlated with variations in the chemical and/or mineralogical compositions of the samples. The results demonstrate clear relationships between strengths in tension and compression and the zinc-iron contents of the rocks.

Jan 1, 1977

By J. C. Marchand, M. A. Berube

"L'objectif principal recherché lors du broyage d 'un minerai est de libérer adéquatement ses valeurs utiles en vue de leur concentration ultérieure. La pratique courante consiste à tenter d'obtenir un produit de broyage d'une granulométrie constante. Malheureusement, les propriétés texturales des minéraux utiles varient naturellement dans un gisement et une telle stratégie n'entraine pas toujours pour ces minéraux un degré de libération constant. Pour un rendement optimal du procédé de concentration, cette variable très importante doit donc être périodiquement vérifiée.Jusqu'à maintenant, la plupart des études de libération des minerais se font en examinant des sections polies de particules du minerai broyé. Le GRAAIM a récemment assemblé un système modulaire d'analyse d'images qui servira en grande partie à des mesures automatiques du degré de libération des minéraux. Le système s'avère relativement peu coûteux comparativement à la plupart des analyseurs de texture conventionnels si l'on considère que plusieurs de ses composantes, par exemple le miniordinateur, sont utilisées à une foule d'autres applications, et il permet de plus une grande souplesse d'utilisation puisque l'on a qu'à construire des algorithmes de mesure et de calcul en fonction de l'objectif recherché. Des programmes particuliers permettant des études automatiques de libération sur des sections polies de particules ont ainsi été élaborés. Ils permettent également des mesures de teneurs et de distributions granulométriques apparentes des particules. Des résultats obtenus dans le cas de minerais de fer sont brièvement présentés afin d'illustrer la technique."

Jan 1, 1983

By D. C. R. Espinosa, P. Aliprandini, J. A. S. Tenório, M. M. Jiménez Correa

"Nickel and cobalt are the main value metals in nickel laterite ore. Cyanex 272 is an extractant used to separate nickel from cobalt present in leach solutions. Previous studies demonstrated the extraction of cobalt, magnesium and manganese at pH 5 using Cyanex 272 as extractant, while nickel remained in aqueous solution. However, it is difficult to separate cobalt from a solution containing magnesium and manganese. One possibility to change the metals’ behavior during the solvent extraction process is to change the mixture of extractants used. In order to study the solvent extraction of cobalt from a solution containing manganese, magnesium and nickel, a mixture of two extractants was investigated. Cyanex 272 (CY) and Versatic 10 (VC) were selected as extractants in the organic phase. The extractant concentrations used were: 20% CY; 15% CY, 5% VC; 10% CY, 10% VC; 5% CY, 15% VC; and 20% VC. In all cases, kerosene was used as a diluent, at 80 vol%. The synthetic leach solution used in this study was prepared according to the composition of a typical nickel laterite leach solution. The pH value of the solution used was 5, and the aqueous/organic ratio used in solvent extraction testwork was 1/1. The study has shown that the composition of the organic extractant mixture did not increase cobalt separation.INTRODUCTION Sulfide and laterite deposits are the main sources of nickel. However, production from nickel sulfide ores has been decreasing over the years, relatively speaking, increasing the focus on the exploitation of laterite nickel ores (McDonald & Whittington, 2008). Laterite ore deposits are found in tropical and subtropical regions. A characteristic of laterite ores is the presence of a complex and heterogeneous mixture of metals (Crundwell, Moats, Ramachandran, Robinson, & Davenport, 2011; Georgiou & Papangelakis, 1998; Gupta, 2003; Kesler & Simon, 2015; Moskalyk & Alfantazi, 2002; Oliveira, 1990). Nickel concentrations in laterite ores are typically 1–2% (Dalvi, Bacon, & Osborne, 2004)."

Jan 1, 2017

By A. H. C. A. Zimmerman

WE have just heard what must be regarded as a thoughtful, constructive and somewhat painful analysis of the financial function of our industry. While thinking about this, it is interesting to reflect on the conditions which have stunted the growth of the financial side of our affairs. Mining must be regarded as a wealthy business. •while immeasurable grub takes and development budgets have been lost, there can be little argument that a productive ore-body nearly always produces the type of wealth that breeds some extravagance. I recognize that this statement can be attacked from many sides, but an historical comparison with a commercial enterprise involving similar investment will demonstrate what I mean. However, these old times are be-ginning to disappear for a variety of reasons. High amongst these are: ( l) Increased costs of exploration. (2) Remoteness of many new finds. (3) Fixed or declining metal prices (particularly when expressed in constant dollars). ( 4) Constant demands for higher wages.

Jan 1, 1962

By L. C. So, S. Faucher, S. Mostaghel, D. Sauter, S. -Y. Oh, S. K. Lee

"Molten material from pyrometallurgical furnaces is tapped at high temperature, carrying a large amount of heat. Traditional handling methods of slow air cooling or water granulation do not allow for the recovery of heat from slag and matte. Furthermore, water granulation adds an inherent safety risk of explosions. Recently, there have been numerous studies into processes attempting to recover waste heat. However, most of them have never been commercialized due to numerous challenges including scalability, cost, low heat recovery efficiencies, and difficulties in heat utilization. Ecomaister-Hatch has recently developed and commercialized a reliable and simple dry atomization system that allows for heat recovery while eliminating the use of water. Comparisons of pilot and commercialized dry atomization and heat recovery technologies will be presented and challenges of these technologies will be highlighted.INTRODUCTION Slag has traditionally been regarded as an undesired waste product from smelting operations with slag management focused on removal and disposal of “waste”. Over 500 million tonnes of slag are produced per year, carrying with it ~220 TWh of energy (Barati, Esfahani, & Utigard, 2011). Depending on the process, the energy content of slag ranges from 10-90% of the total energy input (Barati, 2011, Rodd, 2010). There has therefore been great interest in recovering energy from slag. Slag handling methods can broadly be classified into three categories: (1) dumping and slow cooling, (2) wet granulation and (3) dry granulation. As discussed below, only dry granulation routes are amenable to heat recovery. Slag dumping involves the slow cooling of molten material and crushing of the resulting solid. In this process, slag is dumped on the ground directly from furnaces or transferred to slag pots that are moved by rail or haulers and then dumped on the ground. The molten material is left to cool and solidify until it can be broken and handled by heavy machinery."

Jan 1, 2017

By Ma Yuxin, Niu Fusheng, Yuan Zhitao, Bai Limei, Han Yuexin

"Using batch flotation experiment, contact angle measurement, particle size analysis, and scanning electron microscope (SEM), the influence and difference of pH value on the flotation rate of talc and chalcopyrite were investigate without collector at the pH range of 3~11. The results showed that, the flotation rate of talc decrease with the increasing of flotation time, while that of chalcopyrite hardly affect by flotation time, besides, the flotation rate of chalcopyrite is much less than that of talc, so the laws of flotation rate of the two minerals are independent of pH value. The flotation test data of two minerals are simulated with first order and multi-rate flotation kinetic model respectively. The simulation results showed that flotation of talc only meet the first order kinetic model, while chalcopyrite’s meet the both. In addition, According to test results of talc and chalcopyrite by the particle size distribution, SEM photographs and the contact angle measurement, the reason why talc did not conform to the first order kinetic model is not because of particle size distribution, but of particle shape. That is to say, because of sheet structure of talc, the contact angle of layers and sections are 74°and 52°respectively. At the same time, the contact angle of layers and sections are different between the particles. So flotation rates between talc particles are difference.INTRODUCTIONPossessing superior self-induced, collector-induced and sulfur-induced floatability, chalcopyrite exhibits good floatability at a wide range of pH values and potentials. Serpentine are regarded as the most difficult selected type in various chalcopyrite ore, and the predominant reason is that it contains talc. Talc, as a nonpolar layered silicate mineral, is one kind of common associated mineral in sulfide ores (Lu, 2010). Concentrate quality and flotation process of chalcopyrite are influenced as a result from the presence of talc. It is because that talc has inherent floatability which makes it readily mixed with the floated mineral and talc is easy to slime causing the slime coating of the valuable mineral (Beattie et al., 2006). Thus in order to improve the flotation effect of chalcopyrite, methods can be introduced from two respects. One method is that fast-floating talc mineral is floated preferentially, and the other is that sulfide mineral is floated prior to talc by depressing the flotation of talc mineral (Beattie et al., 2006), nevertheless, no matter with which the flotation effect of fine-sized chalcopyrite is not positive. Therefore, in order to realize the flotation separation of talc and chalcopyrite, the difference between the inherent floatability of fine-sized chalcopyrite and talc is researched and analyzed in terms of flotation dynamics in the absence of collector and frother."

Jan 1, 2016

By G. Morin, F. Chiesa, B. Duchesne

The Quality index is a useful tool allowing to assess the metallurgical quality of aluminium AlSiMg foundry alloys (A356/357). Its value is calculated from the ultimate tensile strength and elongation; it increases with the metallurgical quality of the casting, i.e. with finer dendrites, lower microporosity and inclusion count and lower iron content. This Quality index does not depend on the degree of temper applied during the heat treatment (aging time and temperature). After defining the Quality index, it will be explained how it can be predicted from the knowledge of the local solidification conditions obtained from modelling. The paper will then present four case studies of castings for which the prediction of the Quality index by modelling was made. These case studies from different authors will involve the three most common casting processes used for producing high integrity aluminium castings, namely: sand casting, permanent mould casting and investment casting (lost wax). In all cases, the accuracy of the prediction will be assessed by comparing the predicted Quality index distributions to the experimental values based on the published measured values of the local tensile properties.

Jan 1, 2006

By A. H. Winckers

"The Sullivan Mine and Concentrator are owned and operated by Cominco Ltd. and are located in the Rocky Mountain Trench, in Kimberley, British Columbia.The Sullivan Concentrator commenced operation in 1923 at approximately 2,500 tons per day. The concentrator was enlarged in several stages and by 1945 was treating 8,500 tons of ore per day. In 1949, the capacity of the concentrator was expanded to 10,000 tons per day with the completion of the sink and float plant, the installation of the rod mill, an underground crushing plant and a 4-mile underground and surface electric railway from the underground crushing plant to the concentrator. Throughput now averages 7,000 tons per operating day, or 2,400,000 tons per year.The concentrator operates 7 days per week, 24 hours per day while the underground crushing station operates 5 days per week, 24 hours per day. The ore is essentially a replacement deposit in argillaceous quartzite of Precambrian age. The ore bodies are massive deposits consisting of fine grained mixtures of sulphides, sometimes interbanded with the country rock and varying widely in their content of lead, zinc, iron and silicates. The principal economic minerals are galena and marmatite (7 ZnS:FeS). Iron is mainly present as pyrrhotite, and to a much lesser extent as pyrite. The intimate association of these sulphides necessitated the development of a successful differential flotation process before the ore could be beneficiated profitably."

Jan 1, 1981

By J B. McConnell

The Thompson smelter has three unique features which form the basis ~f its design: fluid bed roasters which treat nickel concentrate filter cake from the mill, as well as the flux, in order to achieve partial desulphurization; the use of electric furnaces for the smelting of the partially desulphurized, preheated roaster product; and the disposal of slag by water granulation and slag slurry pumping. The installation consists of three fluid bed roasters, each feeding an electric furnace. Nickel concentrate is received at the smelter via pipe line. It is thickened and filtered, and the filter cake, together with siliceous flux, is fed through rotary bin feeders and reciprocating double-gate seals into the fluid bed roasters. Air injected into the roasters through club-head tuyeres oxidizes part of the sulphur and associated iron in the concentrate. The heat of reaction dries and heats the charge. Roaster product is recovered from the gas stream in cyclones and from the roaster bed through automatic valves.

Jan 1, 1963

By P. M. Tyroler, W. J. Thoburn, M. R. Alberty

"An initial test of this unique application demonstrated that hot gunned refractory would adhere satisfactorily. Subsequently, it was found that the proportion of material sticking during application increased with increased vessel temperature and when a mix containing pitch was used. About 75 per cent of the latter type adhered when it was applied at 1600°C.TBRC availability increased from an historical average of 62.5 per cent to 64.7 per cent during four campaigns when hot gunning was routinely practiced. Refractory cost was about 20 per cent less than that anticipated without gunning. Average parameters per campaign with gunning ranged as follows: 90 to 108 heats, 10 to 37 applications and 1.4 to 2. 7 hours per application. Prior to gunning, the average number of heats per campaign was 73.IntroductionThe Top Blown Rotary Converter process at Inco's Copper Cliff Nickel Refinery converts copper-nickel-sulphur concentrates to a material suitable for carbonyl refining (1),(2).Operating conditions are particularly hard on refractory. Batch cycles finish at temperatures up to 1650°C, with occasional excursions over 1700°C. New heats are then usually initiated immediately and the refractory is subjected to intense thermal shock from the cold feed. Temperature cycles are also introduced three to four times during a heat when the process is interrupted for scrap charging, temperature measurement or sampling.Abrasion wear results from rotation of the converters at speeds up to 15 RPM and from agitation of the bath with supersonic-velocity oxygen. Mechanical damage also occurs when chunks of scrap or solid matte are processed. Chemical corrosion is also present, as we know from our own laboratory work(2) and reports of operations elsewhere. As a consequence, refractory material and installation form a very large proportion of the converter plant costs. Equally important is the loss of converter availability during rebricking; this significantly reduces plant capacity."

Jan 1, 1981

By M. H. Leite, R. Corthésy, D. E. Gill

"La connaissance des contraintes naturelles qui prévalent dans les massifs rocheux est un prérequis indispensable pour la conception sécuritaire et économique des excavations comme on en retrouve dans les exploitations minières souterraines. Certains chercheurs se sont attardés à colliger les résultats de mesures de ces contraintes et les ont utilisés pour produire des modèles de prédiction basés sur leur traitement statistique. Ces modèles de prédiction sont très populaires auprès des exploitants miniers puisqu’ils permettent, du moins dans les étapes préliminaires de design, d’obtenir de façon s’apéconomique mais approximative, une partie des paramètres dont ils ont besoin. Dans le cadre d’un projet initié en 1994 avec la collaboration de l’IRSST, il a été décidé de produire un modèle de prédiction englobant une partie de la zone périphérique de la faille de Cadillac, soit une zone plus restreinte que le Bouclier Canadien utilisé jusqu’ici comme région pour l’élaboration de tels modèles. Pour produire ce modèle de nouvelles données obtenues avec une technique permettant d’exercer un excellent contrôle de qualité ont été ajoutées à celles déjà disponibles. Une telle régionalisation des données de base permet d’obtenir un modèle où les intensités et les orientations des contraintes principales sont beaucoup moins dispersées que ce que rapportent les modèles publiés jusqu’à ce jour. Enfin, il est démontré que le modèle proposé pour la région étudiée est en toute probabilité plus sécuritaire que les modèles plus généraux publiés à ce jour. Knowledge of the in situ state of stress existing in a rock mass is essential to the safe and economical design of underground mining excavations. Prediction models have been published, based on the statistical treatment of stress measurement results. Such prediction models are very popular among mine operators because they allow them, at least at a preliminary design stage, to economically obtain part of the information needed, even if this information is approximative. In 1994, a research project financed by IRSST was initiated aiming to produce a prediction model that would comprise a peripheral zone around the Cadillac fault. This region is more confined than the Canadian Shield on which the existing prediction models have been based up to now. In order to produce such a model, existing stress measurement results have been used in conjunction with new stress measurements that have been performed based on a technique which allows full control of the quality of the measurements. Restricting the data upon which the model is based to a more specific region gives a model in which the intensities and the orientations of principal stresses are far less scattered than the results published to date. Finally, it is shown that the proposed model is probably safer for the studied region than the models previously published."

Jan 1, 1998

By T. W. Sullivan

"This paper explores the history of AC static variable frequency control drive systems on open cast mining machinery, in particular electric mining shovels and electric walking draglines, over the past ten years. It critiques the peformance of these drive systems from a productivity and operating cost standpoint and evaluates the over-all success of the original design concepts as they were envisaged in the 1970s. The paper details the state-of-the-art as it exists today as well as design improvements contemplated for the immediate future.IntroductionConsidering the fact that the very first successful application of an alternating current electrical distribution system occurred at the Gold King gold mine near Ames, Colorado, U.S.A., in the year 1891, it seems somewhat ironic that almost 100 years later, AC excavator drive systems are just now becoming commonplace in the mining industry.If one were to read the biography of Lucien L. Nunn, the first person to successfully install a commercially viable alternating current power distribution system, one would quickly visualize a parallelism between his fight to achieve acceptance of his new lower cost technology and that of those commissioned with the belief that AC static variable frequency control drive systems are not only a better performing, lower cost drive system for mining excavators today, but moreover, the drive systems of the future in our industry.This paper will deal with the evolution and incorporation of AC static drive systems on open cast mining excavators. It will trace the history of the development of these drive systems in the mining industry, the current state-of-the-art concerning these systems, and what the future holds for these excavators in our industry."

Jan 1, 1990

By T. H. Janes

"IntroductionSULPHUR is a constituent of many industrial products. It is part •of almost anything we eat, wear, or use. In fact, sulphur is so important that there has been an increasing tendency in recent years to measure industrial growth in terms of sulphur consumption.The uncertainty of obtaining adequate supplies •of elemental sulphur from the Frasch-mined domes. of Texas and Louisiana in the United States led all countries in 1950 to seek alternative sources of supply of this necessary element.Canadian industry has been supplied, for many years, with most of its sulphur requirements by United States Frasch-mined sulphur. World demand for this sulphur has necessitated the imposition of controls on its distribution, as production has not kept pace with demand. Until the third quarter of 1950, Canadian manufacturers of pulp and paper, heavy chemicals, explosives, and textiles •experienced little difficulty in obtaining their needs of elemental sulphur from the United States. However, at that time, low producers' stocks and declining reserves threatened to reduce shipments from producers, with the prospect of a continuing shortage for some time. These conditions, together with higher prices, stimulated the search for alternative sources of supply in Canada."

Jan 1, 1952

By Finley A. Campbell

THE Quemont and Horne mines are located at Noranda in north-western Quebec. As shown in Figure 1, the Noranda area lies between the Cadillac-Bouzan fault zone on the south and the Porcupine-Destor fault zone to the north. Both of these major structural lineaments appear to be geometrically, and possibly genetically, related to the Grenville Front. The regional geology has been discussed by Wilson (12), Cooke et al. ( 2), and others. The geology in the Noranda vicinity, as compiled by Dugas and Gilbert ( 3), is shown in Figure 2. The Cadillac-Bouzan fault zone separates the dominantly Temiskaming-type sediments in the south from the Keewatin-type canic rocks to the north. These volcanics, which vary in composition from rhyolite to andesite, form a broad anticlinorium with a general eastward plunge. A succession of dioritic stocks, sills and dikes have been mapped in the area. The principal granitic rock masses include the Powell, Flavrian and Dufault stocks.

Jan 1, 1962

By W. T. Robson

LAKE Shore Mines, Limited, with property at Kirkland. Lake, Ontario, was incorporated m 1914 and commenced product10n m March, 1918, with an initial capacity of about 60 tons per day. Since that time a gradual expansion has taken place until a present capacity of approximately 2,300 tons per day has been reached, giving a total annual gold production valued at approximately $16,000,000. At the time of incorporation of the Company, the Lake Shore property consisted of four mineral claims and four fractions, totalling 171.05 acres. In 1934, four claims belonging to the Minaker Kirkland Gold Mines, Limited, were acquired and a controlling interest purchased in the Kirkland Hudson Bay Gold Mines, Limited. Both these properties adjoin the Lake Shore claims on the south. From the accompanying compilation of the world's largest gold mines for 1934 (1), it will be seen that, while Lake Shore holds sixth position in respect to the number of ounces produced, there are twenty-five gold mines which treat a greater tonnage of ore. This is an indication of probably the most unusual feature of the Kirkland Lake deposits, namely, the high aver-age tenor of the ores. coupled with the comparatively large tonnages available.

Jan 1, 1936