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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 David J. McDougall

"IntroductionThe production of pig iron, wrought iron bars and castings in Quebec during the 18th and 19th centuries has been so closely identified by historians with the Forges du St. Maurice on the St. Maurice River a few miles north of Trois Rivières (Three Rivers), that one is sometimes left with the impression that it was the only iron works that ever operated in the province. There were however, about twelve others, one of which was so completely re-built that it should probably be considered as a separate entity. All but two were constructed after the midpoint of the 1800s, coinciding with the growing Canadian demand for ""charcoal pig"" for railway car wheels and castings for industry, and about half of them were technically, if not economically, successful. The misconception about the Forges du St. Maurice may have come about either because of its long history of somewhat less than continuous production over a century and a half, or a tendency of Quebec historians to concentrate on events in the French-Canadian rather than the English-Canadian milieu, but whatever the reason, the other Quebec iron work s have been generally ignored. All but one of the Quebec blast furnaces could be described as ""preindustrial"" with capacities ranging between three and ten tons per day, the exception being the Radnor furnace built in 1892 with a maximum production of about 35 tons per day and an alleged capacity of 50 tons per day.Until a railway network was completed in the 1880s, the location of all the Quebec iron works except the Grantham Iron works was dictated by close proximity to adequate ore reserves because horse transport was of little use beyond a ten-mile radius. The other essentials of forest resources (mainly soft woods) for charcoal, limestone for flux and water power, were generally available except within a few miles on either side of the St. Lawrence river. Among the dozen iron works established in Quebec between 1732 and 1880, seven used bog iron ore in charcoal-fired furnaces."

Jan 1, 1983

By R. F. Dawson, A. S. Bagnall, K. Barron

"At Smoky River Coal Limited (SRCL), economic occurrences of structurally thickened coal deposits form attractive surface mining targets. These steeply dipping, structurally complex deposits require that special attention be given to pit wall design and operational practices.Where anchor support is feasible, there is potential for reducing footwall waste requirements and/or increasing coal recovery. SRCL has used rock anchors to support footwall slopes since 1985. This paper outlines design considerations and performance of rock anchor support systems at SRCL.Three case histories are included that illustrate the design process for supporting steeply dipping footwall slopes using rock anchors.IntroductionWestern Canada contains vast reserves of high grade coking coal largely located in two belts within the Rocky Mountain Foothills straddling the Alberta/British Columbia border. There are about one billion tonnes of ""clean"" coking coal reserves (Romaniuk and Naidu, 1986) situated near existing mining infrastructure. Within the reserve areas shown in Figure I, a total of six producers operate 10 large mines linked with ports situated on Canada's west coast. Al! of the producers operate conventional shovel truck surface pits.Surface mineable reserves within some of the mountain coal mines are located on dip slopes or where the geologic structure has thickened the coal near the surface, creating low strip ratio targets. Footwall slopes in these mines are developed parallel to bedding, thus minimizing waste extraction and preventing undercutting of potentially unstable strata. The base of the mineable coal measures in both north and south regions is marked by massive quartz sandstone units (Torrens Member and Moose Mountain Member) which often form the footwall. Footwalls developed within this basal sandstone unit can attain very high unbenched heights often with little risk of instability. In cases where the footwall is developed on weaker strata above this basal unit, stability considerations control slope height when bedding dips exceed about 30°. In these situations it is desirable to assess the benefits of artificial support to increase the unbenched footwall slope height."

Jan 1, 1995

By G. R. Davidge

"Falconbridge Mine has a history of significant microseismic activity dating back to 1955. Since mid-1981, a microseismic monitoring system has been operating in the area around the No .9 Shaft hoist room located 25 m from the are zone at a depth of 1200m. Several mine wide faults dissect this area and have been shown to be microseismic-active due to mining. The microseismic monitor has been interfaced with a small dedicated personal computer and a communications device to perform routine data evaluation and to produce graphical output. The programs are described and selected result s from the monitoring program are presented.IntroductionFalconbridge Mine is located on the southeast rim of the Sudbury Basin. The nickel-copper sulphide ore zone is essentially a tabular orebody striking approximately east-west and dipping at 80 degrees north near surface and rolling to 75 degrees to 80 degree s south by the 1000 level. (Mine level number s represent the approximate depth in feet below ground surface .) This dip is maintained down to the 6000 level. The north wall is comprised of jointed norite and a faulted contact up to 1 m thick exists between the ore zone and the norite. The south wall rock is a greenstone with highly siliceous lenses and often has a faulted contact with the ore zone. No less than five mine wide faults exist, as shown in Fig. I.Mining ha s been carried out from virtually the bedrock contact to depths of 1830 m although the majority of current activity is between 900 and 1500 m below surface. A winze provides access below the 4025 level and the cage hoist room is located on the 3850 level in the north wall 25 m from the contact. Because of concern for the stability of this hoist room, there has been no mining activity within 60 m of the hoist room and by 1980 this block of ore was one of the major blocks of high-grade ore remaining in the mine . Mining of this block was originally scheduled for very late in the decade.Prior to a six-month shutdown in 1982, this mine produced approximately 450,000 tonnes of ore annually, mainly by cut and- fill techniques. Following the shutdown, annual production has been reduced to approximately 200,000 tonnes and production is now mainly by undercut and fill techniques .Mining-induced seismicity has occurred at Falconbridge Mine since at least 1955 and reviews of the microseismic problems for the periods from 1965 - 1970 and from 1971 to 1979 were made by Singh (1971) and Vongpaisal et al. (1980), respectively. The need for instrumentation was addressed by these authors. Following several large events during the spring of 1980, a decision was made to investigate existing microseismic monitors and to apply micro seismic monitoring techniques in Falconbridge Mine. Application of microseismic monitoring to Falconbridge Mine was to concentrate on the No . 9 Shaft hoist room area of the mine, particularly around the 4025 level where a large mechanized cut-and- fill stope was approaching this level. By mid - 1981, the microseismic monitor was fully installed and with in a year , a short-period seismograph and a personal computer had been added to the system."

Jan 1, 1984

By T. C. Crosby

"Grinding has a marked effect on concentrator recovery and operating cost, and improved operation through automatic control can enhance plant performance. The correct application of automatic control can only be accomplished after the basic process variables and their effect on mill operation have been defined. This paper develops a control system for a closed circuit grinding system. Typical control systems, such as those for feed, water flow, level and circulating load, are discussed. A method of determining controllability, using the calculated reaction curve technique, is outlined. Various successful automatic grinding control applications are discussed and future possibilities are outlined. Although this paper primarily deals with closed wet grinding• circuits, the principles involved can be readily applied to other processes."

Jan 1, 1967

By G. G. Manekar

MOIL Limited (formerly Manganese Ore India Limited), a Government Enterprise, under the Ministry of Steel, Government of India, produces about 1.1 million tonnes (T) of manganese ore annually from three opencast and seven underground mines. The underground operations are mining using an overhand cut and fill method. The orebody is too narrow for the use of larger equipment and the poor to fair rock mass quality limits the size of stable excavations. Prior to the 1990s underground support consisted primarily of timber square sets in tandem with timber chocks and props. As mine production requirements increased throughout the 1990s led to larger opening sizes and more modern support practices. Research was conducted on ground support design based on rock classification and empirical techniques for designing ground support. Based on the findings and field trials, the Company adopted full column cement grouted cable bolts for back support. Instrumented field trials, using extensometers and load cells on the cable support confirmed the support effectiveness. Stope design was based on two and three dimensional stress modeling which resulted in a significant increase in stope dimensions. The rock mechanics studies for safe stope design were carried out using numerical modeling tool in two and three dimensions for the analysis of stresses. Based on the findings, the safe stope geometry with new stoping parameters was introduced. The earlier stope length of 30 mtrs were changed to 60 mtrs with in situ rib pillar at the cross cuts and in situ post pillars to be left-out in the stope. This leads the formation of of panel comprising of three stopes, for production, supporting and filling. For mechanical handling of ROM in stopes Side Discharge Loaders (SDL) were introduced. The above changes have improved the face productivity from 2?3.5 T with manual operation and 9 T with SDL. The above rapid mining operations has improved the stope productivity but reduced the stope life from 6 to 3 years. For the improvement of the stope availability, further studies were conducted by numerical modeling of stress analysis. The related studies confirmed that with the existing supporting system and proper instrumentation, level interval could be increased up to 45 mtrs from the existing 30 mtrs at deeper levels. At present below 12th Level interval is 45 m at Balaghat Mine. For future mechanization program for introduction of Single Boomers, LPDT, Cutting Machines etc for the development headings rock mechanics studies are underway. The paper provides details of rock mechanics studies that were carried out to study efficacy of the cable bolt support, safe stoping parameters and increased level interval for the improvements in safety, production and productivity at Balaghat Mine.

Aug 1, 2013

By D. Sediako

Excessive residual stress in Al engine blocks may result in cylinder distortion which reduces engine operating efficiency. As such, neutron diffraction was used to measure residual strain along the Fe liners and Al, in the hoop, radial and axial orientations with respect to the cylinder axis, at the cylinder interbore region. Residual stresses were subsequently calculated using generalized Hooke's law and related to the microstructure along the cylinder bridge. The results suggest that the residual stresses in the Al interbore region are tensile and increased with depth in the axial direction of the cylinder. The increase in residual stress at the bottom of the cylinder coincides with a finer and more uniform microstructure in this region of the cylinder. The refinement in microstructure at the bottom of the cylinder likely increased alloy strength, thereby decreasing this section's susceptibility to distortion. This study successfully quantified the residual stress profiles in a heat treated engine block and related the stress profiles to an as-cast engine block.

Jan 1, 2011

By R. W. Thompkins

"PREFACEPart 1 of this paper, published in the September issue, covered the occurrence of uranium, radiation from uranium ores, the uranium series, radioactive theory, radioactive equilibrium and application to the radon series, the working level, the theory of emanation and diffusion, transport by thermal diffusion of radon emanating from porous rocks, and definitions.The October issue carried Part 2, which dealt with radiation theory applied to uranium ores, other radon migration factors, factors affecting the radon gas release rate, the measurement of radon gas emanation rates, the tunnel concept, variation of emanation rate with grade and estimating radioactivity from grade analysis.Part 3, in this issue, concludes the series by discussing the techniques for controlling radiation and providing some example calculations.17.0. Techniques for Controlling Radiation17.1. Altering the Factors In the Diffusion EquationIt has been noted that radon gas emanates from the surfaces of exposed ore to the mine atmosphere. The diffusion laws establish the rate of this flow. The fundamental relationship is that the rate of flow (J) is a function of the pore concentration and the distance from the surface. It is expressed as: []If any of these terms is varied, either naturally or artificially, the rate of gas emanation will be altered.Altering the Diffusion CoefficientThe literature describes many ways to lower the radon gas emanation rates which are dependent on changing the diffusion coefficient:1. A layer of ice on top of a tailings dam or on a soil.2. Humid clayey materials and swamped soils over a radon source."

Jan 1, 1982

By Jorgen Elbrond, Yve Lizotte

"A mathematical procedure for determining the underground mining level layout which minimizes the total costs of excavation and haulage is described. This procedure has the advantage over previous graphical procedures of being easily amenable to microcomputers. The paper demonstrates through examples how the procedure can be applied to minimizing discounted costs of level layout as well as providing the optimal location of a production shaft.IntroductionIn recent years there have been numerous publications in mining journals concerning the minimization of mine haulage costs. With the rapid escalation of energy costs during the last decade it is not surprising that several studies applying queuing theory, simulation and mathematical programming to mining related transportation problems have been successfully undertaken. Because of the increasing availability of various sizes of computers these techniques have gained considerable popularity as evidenced by the numerous commercial packages presently being marketed.The publications concerned with haulage cost minimization are generally concluded along the lines of ' ... haulage costs at production rate x will be minimized by assigning y units to location z...'. Details about the route followed and whether it guarantees a minimization of costs are seldom considered. Route data has to date been manually resolved and used for input to developed programs. It would appear that no program has been developed to date which simultaneously minimizes costs by both fleet assignment and routing network resolution.Another important factor in transportation problems is the investment cost associated with the routes; road construction costs or, in the case of underground levels, drift excavation costs. Except for special cases the transport network which minimizes haulage costs only will not provide a minimum excavation cost solution.Zarnbo(1) illustrates by graphical and mathematical procedures how central 'facilities' can be located to simultaneously minimize investment in the transport network and haulage costs. Unfortunately these procedures and others recently applied to mine haulage problems do not provide solutions to the generalized problem. Also because these procedures are geared to graphical solutions and hand computations whereby certain possibilities can be 'visually' eliminated, they can be tedious to program and present storage capacity constraints with current microcomputers."

Jan 1, 1985

By Greg Yuriy

This paper discusses research carried out by the Laurentian University Mining Automation Laboratory (LUMAL) in the field of discrete-event simulation of mine equipment systems and reliability assessment of these machinery using genetic algorithms. The AutoMod simulation package, from Brooks-PRI Automation Inc., is used in this research. It is a 3-D discrete-event simulation/animation software tool for creating realistic depictions of manufacturing and materials handling systems. Discrete-event simulation involves modeling of real-life systems based on variables and events which occur or change at distinct points in time. In our case, a two level, multi-drift sublevel stoping model was created in AutoMod for the simulation of the equipment fleet employed in the development cycle (drilling, explosives loading, blasting, materials hauling, ground support) of a typical underground mine in the nickel mining region of Sudbury in Ontario, Canada. The equipment primarily considered in the simulation is Load-Haul-Dump (LHD) vehicles (scooptrams), drills, explosives-loaders and roof bolters. The purpose of the simulation study is to assess the impact of equipment failures to mine?s production throughput. In more detail, using Mean Time Between Failures (MTBF) data of scooptrams derived from a reliability assessment model based on genetic algorithms, LHD failures are incorporated into the simulation model. These failures cause production interruptions to the development cycle and consequently loss of hauling capacity. This paper will indicate the significance of equipment failures to a mine?s production and suggest a methodology based on the combination of discrete-event simulation and a predictive reliability assessment model using genetic algorithms for the study and analysis of mine equipment systems.

May 1, 2003

By Helge B. Wurst, Michael P. Cipold, Jan F. Bachmann, Claus C. Bachmann

"In washability, the objective is to establish the set of maximum possible separation performance criteria for a given mineral feed. The method of choice for this has been the conventional sink-float analysis. Time, cost and safety aspects of the sink-float method have prompted the search for a new approach for establishing separation performance criteria, especially as performance levels of separator plants can be maximized if reliable information based on an analysis of washability in conjunction with particle size distribution, elemental constituency becomes readily available. The new method to establish washability and associated performance information utilizes at least two measurement technologies concurrently: single energy x-ray transmission and image processing. For porous or very inhomogeneous materials the results can be refined further by using dual energy x-ray transmission and image processing. The value of the collected data increases considerably if the washability data were additionally available in time to be considered in the control of the process plant. The incorporation of an automated washability monitor gives near real-time data that would impinge positively on the profitability of the plant operation. The method was extensively tested with a range of sample with different densities, varying from 1 g/cm³ (coal) to 5 g/cm³ (iron ore).INTRODUCTIONWashability of minerals like coal and iron ore is expressed by a curve or graph showing the results of a series of float-and-sink tests. Several of these curves are drawn to illustrate different conditions or variables, usually on the same axes, thus presenting the information on one sheet of paper. Washability curves are essential not only for the design but also for the operation of preparation plants.In determining the washability analysis, particle density is the underlying feature of all washability curves. Conventionally, the particles are separated into density fractions by immersing them in fluids of a predetermined density followed by skimming of those particles that stay afloat. The particles remaining afloat thus have a density lower than that of the fluid they were subjected to. The particles that remained at the bottom of the fluid container thus had a higher density higher than that of the fluid. By progressively increasing, for example, the density of the fluid and immersing the remaining particles so as to be able to skim the next density fraction, the particles would be fractionated into density groups. The liquids used range from aqueous solutions to organic liquids to suspensions. Unfortunately the liquids used for this separation process are often toxic and expensive. It stands to reason that a new method of determining washability is sought."

Jan 1, 2016

By China University of Mining & Technology, Yuemin Zhao, Bo Zhang, Liang Dong, Zhenfu Luo, Chenlong Duan

"In China, approximately 65% of coal reserves are in the west region, where water shortage is a serious problem: high-efficiency dry coal beneficiation technology is desired. Using magnetic powder and fine coal as heavy medium, and using air as the fluidizing agent, a novel air dense medium fluidized bed separator is proposed for coal preparation. Coal can be efficiently separated according to density in the fluidized bed, where bed density is steady. The separator is highly reliable, the circulation quantity of heavy medium is low, and the gas distributor cannot be easily easily. The world’s first industrial modularized dry coal preparation plant was built by China University of Mining and Technology. Dry coal beneficiation technology was first used to produce low-ash coal. Results of industrial production show that the ash content of clean coal is 3.46%, the probable error E value is 0.055 g/cm3, and the organic efficiency is over 90%. The advantages of the modularized dry coal beneficiation system are the high separation accuracy, the simple process flow, the low operation cost, low energy consumption, and so on. This technology provides a new effective method for coal separation in acid region and coal tending to sliming.INTRODUCTIONCoal is the most important primary energy source in China, where coal output reached 3.68 billion tons in 2013 and represents approximately 68% of the primary energy consumption. Coal has made a great contribution to the development of the Chinese national economy, but it also brings serious environmental pollution. However, approximately 65% of coal reserves are in the arid west region in China where water shortages present a challenge for wet coal preparation technology. In addition, the abundant lignite resource, because it is easy to mud in the water, should not be treated with the wet separation method. Therefore, it is critical to develop highly efficient dry coal preparation technology to meet the demand in arid areas. Further, water resource shortages are a global problem, thus the development of efficient dry coal preparation technology in has potential application in other water-short countries like South Africa, Brazil, India and Turkey."

Jan 1, 2016

By R. L. Veenstra

This paper explores the connection between the stresses observed and the failure mechanisms present in the modelled cemented paste backfill. In order to look at this connection, the authors have used a previously developed model to conduct a sensitivity analysis of the model?s strength and permeability input parameters. The results from the sensitivity analysis were then compared to determine what causes modelled stresses and failure mechanisms to vary. Increased insight into the behaviour of the modelled paste will help clarify how paste behaves in the field.

Aug 1, 2013

By E. C. Sanford

A laboratory-scale batch extraction unit and operating procedure for studying the hot-water separation of bitumen from Athabasca tar sands are described. The extractor evolved from earlier units and has been in use by Syncrude Research for the past 10 years. By using a unit such as this, it is possible to study tar sand feed quality and the effects of chemicals on the hot-water extraction process, while process variables are held constant. Data are presented to demonstrate the importance of surfactants to the process and the interrelated role of inorganic bases and surfactants.

Jan 1, 1979

By P. Bacher, L. Dubourg, M. Jahazi, G. Dezaise

Effect of friction stir welding parameters and natural ageing on weld properties are reported. Using a Taguchi design of experiment, attempt is made to systematically examine the influences of the welding speed, tool rotation speed, forge force, tilt angle and pitch ratio on the weld size and ultimate tensile strength of FSWed joints. One millimetre thick plates of AA7075-T6 were welded in lap joint configuration. Samples were characterized by optical microscopy, hardness and tensile measurements. Trends suggested by the results and directions for further investigation are discussed.

Jan 1, 2006

By M. Nzotta, L. Teng, S. Seetharaman, A. Chychko

The objective of the present work is to optimize the EAF practice towards Mo alloying with maximum retention of the alloying element in molten steel. During Mo additions, there were significant losses to the dust (ca 7 %) and to the slag phase (ca 2 %), which had serious economic and environmental impacts. The present work was aimed at designing a suitable Mo precursor, an alternative to ferromolybdenum, as the Mo source and a process sequence for optimal retention of Mo in the steel. The design of the Mo source should be in such a way that low cost raw materials such as MoO3 concentrate have to be used, stable during the addition so that the vapour phase losses as MoO3 are kept minimum and the dissolution of the precursor in molten steel is easy without loss to the slag phase. After thermodynamic considerations, three precursor materials were chosen, viz. CaMoO4, MgMoO4 and Fe2MoO4. Synthetic mixtures of the component oxides in each case as well as pure MoO3 were investigated by TGA and high temperature XRD in order to find out the temperature range in which the compounds were formed. Experiments were also conducted separately where the evolved gases were analyzed. All the three precursors were formed easily and the loss of MoO3 to the vapour phase was found to be extremely low. Addition of the oxide mixtures to steel melts were conducted in three different scales, viz. 16 g, 500 g and 3 tons (induction furnacle). Initial experiments showed that MgMoO4 was not suitable since the Mo yield in the steel melt was not very high. Fe2MoO4 was found to perform best, the Mo yield reaching 98 %. Further trials were conducted in the 65 ton Electric Arc Furnace (EAF) at Uddeholms AB in Hagfors. Mixtures of mill scale, MoO3 and carbon in suitable proportions were added in a pre-determined addition sequence. It was found that, in the actual practice, the Mo yield reached 99 %, equaling in performance the addition of ferromolybdenum. The process offers an effective use of cheaper raw materials and very high Mo yield avoiding a pre-treatment step like the production of ferromolybdenum. This is both cost effective and environmentally advantageous. The process has been patented and is being currently implemented at Uddeholms AB, Hagfors, Sweden.

Jan 1, 2011

By J. J. Denny

IN November, 1932, an investigation of silicosis was undertaken at the Mcintyre Porcupine mine, Schumacher, Ont., after a discussion of the p"roblem with Sir Frederick Banting and his staff. As a result, it was decided to carry on dusting experiments with animals at the mine in a manner that would duplicate as far as possible actual industrial conditions. At that time 50 guinea pigs were placed in the crusher house tunnel of the mill where a considerable quantity of fine dust, containing approximately 35 per cent of free silica, was being constantly produced. These animals lived in this atmosphere for periods up to one year, and, while on autopsy large amounts of dust were found in the lungs, not a single case of silicosis had developed. These negative results suggested, among other things, that the mine gases might be a predisposing factor in the production of silicosis, and the results of this investigation (1) led us to undertake the study of the hydrogen-ion concentration of the condensate of the atmosphere, both in the mine and in various sections of the mill. The CO, combining power of blood serum on a series of 400 miners was also studied at this time. While these results were inconclusive, the variation in the hydrogen-ion concentration of the condensate between the surface and underground atmospheres encouraged us to investigate the effect of neutral, weak acid, and alkaline solutions on the solubility of siliceous materials. Gye and Purdy (2) were the first to point out that the chemical reaction, and not the physical presence of siliceous material, was responsible for the production of the fibrosis in silicosis. This work was investigated by Gardner and Cummings (3), who showed that the tissue reaction to quartz was definitely proportional to the size of the particle. They found that 1-3 micron particles of quartz produced an acute proliferative fibrotic response, while the 10-12 micron particles produced only a foreign-body reaction up to a period of three years. It is accepted that the dangerous silica particles retained by the lung are under 5 microns in diameter.

Jan 1, 1937

By Derek E. McBride

"Exploration work in the Beardmore - Tashota area has led to a reinterpretation of relationships between gold mineralization and the geologicalevolution ofthe area. The host volcanic rocks form two parallel volcanic belts connected by a much smaller cross-cutting band, which trends northeast from Beardmore to Tashota. This connecting band consists of mafic and felsic volcanic, plus clastic sedimentary rocks in a sequence conformable with the contact of the Onaman Lake Batholith to the east. A metamorphic aureole or incorporated xenoliths are lacking along this major contact and the only intrusive relationship observed is chilling between mafic dikes and a cold host granite in proximity to it. Granite dikes are totally lacking in the volcanic succession, or the overlying sedimentary sequence. A major part of this sequence consists of a polymict basal conglomerate with granite boulders and volcanic clasts in a fine-grained chloritic matrix. The nearest source for these boulders is the Onaman Lake batholith.Gold mineralization in significant economic quantities (+ 50 000 ounces) occurs at the top or above the mafic volcanic succession as quartz bands. In the Northern Empire Mine, the band is conformable, folded, boudinaged and the mineral zoning shows a relationship to variations in the host rock, not structural overprinting. In general, where the host mafic tuff is medium-grained, the quartz band is thicker, up to a metre wide, and carries economic grade; where the tuff is finer-grained and bedded, the band is very thin and low grade.Stratigraphic control and metal zoning shows that the mineralization formed as part of the development of the volcano- sedimentary succession. The other major deposits in the area (Leitch and Sturgeon River) have a similar structural history suggesting that they are also syngenetic in terms of the stratigraphic development. Regionally, these deposits were emplaced prior to any significant tectonic deformation but at the end of the mafic volcanic event.The mafic activity was related 10 a period ofextension which caused the volcanic troughs to develop along centres of rifting. The hiatus at the end of this event permitted extensive hydrothermal systems to form and deposit siliceous exhalite bands within sedimentary or terminal mafic volcanic environments in promixity to major thermal sources. Subsequently, the Kenoran Orogeny deformed the entire succession into upright folds with a sub-vertical schistosity. Evidence shows that the deposits have remained intact since deposition."

Jan 1, 1987

By R. R. Rogers

Abstract The degree of cathodic protection of steel and the anode corrosion rate were determined when anodes and waters of different compositions were used at temperatures similar to those in domestic hot water tanks. Twenty different anode materials, sixteen of them magnesium-zinc-aluminium alloys, were immersed in six different synthetic waters resembling those to be found in various parts of Canada. The results showed that (1) both the degree of cathode protection and the average anode corrosion rate are affected materially by the composition of the anode material and of the water; (2) poor cathode protection is associated with low anode corrosion rate; (3) when the cathode is fully protected, the anode corrosion rate may be comparatively low or comparatively high, depending upon the composttion of the water; (4) an important relationship exists between the magnesium content of the preferred anode and the composition of the water; (5) the degree of protection is increased as the SO4 + Cl concentration of the water is increased and thus as its specific resistance is decreased. Introduction Fairly recently, the use of the active metal magnesium for the cathodic protection of less active metals has received a considerable amount of attention. This interest has been stimulated by the fact that the wartime demand for magnesium was greatly in excess of the present peacetime demand and there is a natural desire to continue operating the large magnesium plants which were built during the war. Information regarding the use of zinc and aluminium for this purpose also has been published. There is a great demand for domestic hot-water tanks which will resist corrosion satisfactorily. This problem is rather complex in view of the fact that the composition of the water used in such tanks varies greatly and depends upon the locality. The present investigation deals with the effect of water composition and anode composition on the cathodic protection of steel under conditions approaching those which exist in hot water tanks.

Jan 1, 1948

By P. Diehl, M. David

"As shortage in the supply of mineral commodities become more probable, there is an increasing need for reliable and comparable reserve/resource data. It is therefore necessary to standardize the traditional classification procedure by quantifying the three basic criteria in resource evaluation: economic feasibility, geologic assurance and recovery. For the portion of fairly well documented deposits and as far as their geologic parameters are concerned, geostatistical methods can considerably improve the quality of ore classification. In respect of economic feasibility and recovery, approved geostatistical methods can be introduced directly into the classification procedure. The concept of geologic assurance, however, requires a new interpretation in terms of geostatistical error spread. As the ""risk"" in estimating an ore parameter is also a function of the respective block size, it is reasonable to define not only upper limits for the risk intervals for each class of uncertainty, but also block dimensions which reflect the typical stage of planning associated with the different ore categories. An algorithm has been developed to block out areas inside a mine or a large panel which satisfies the constraints of an ore category in respect of the risk intervals of a parameter and in respect of their size. The method has been computerized and is demonstrated on a massive copper-nickel deposit.IntroductionFacing an uncertain future with respect to the demand and supply of mineral commodities, both governmental authorities and the mining industries show an increasing interest in a useful framework for the assessment and classification of the remaining mineral resources"". This is reflected by the recently published appraisal and classification scheme of the United Nations as well as by the new or revised classification systems of the USA; Canada or Australia. Moreover there are various classification schemes which are currently discussed in major mining companies."

Jan 1, 1982