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By Chas. L. Emery

"The laws of rock mechanics apply equally well to all rock structures, and open pits are not exceptions. The concepts and some arguments about the emphasis to be placed on various aspects of open-pit design are discussed in this article.RocksROCK can be described as a granular material consisting of grains and glue. The grains may be fragments of other rocks or polycrystalline aggregates. The glue may be ferruginous, calcareous, argillaceous, siliceous or other material connecting the grains. In a crystal intergrowth, the outer layers of the crystals in contact with each other may be considered to act as a glue. Water may be a glue in clay or a grain in a crystal structure. Air and other fluids or gases are grains if they occupy spaces in a granular mass. Such grains are functional either chemically or mechanically or both."

Jan 1, 1966

By H. L. Cheng, C. H. B. Leitch, C. T. Hood, A. J. Sinclair

"Epithermal Zn-Pb-Cu-Ag-Au quartz-carbonate-barite veins at the Silver Queen mine near Owen Lake, west-central British Columbia, are hosted by Late Cretaceous Tip Top Hill andesitic volcanic rocks. The veins form a rectilinear northwest-northeast pattern that differs slightly from regional structural trends. The main northwest-trending veins are oriented very close to the trend of regional northwest faults, but the crossing veins tend to be more east-north-easterly (070 degrees)compared to a regional north-easterly trend (040 degrees). The character of the veins suggests they are extensional features formed by dextral slip related to Paleogene oblique subduction, or intrusion of magma at depth, or both.In detailed exploration at the mine, the veins cannot be modelled as simple tabular sheet-like bodies. Instead, they are complex structures that divide and rejoin, forming multiple veins or stringers, or are found in shear zones as replacement features with quartzsericite- clay-carbonate-pyrite alteration haloes of variable width that make definition of vein margins and correlation from hole to hole ambiguous. In addition, individual veins within each of the main structures have en echelon characterboth along strike and down dip.Geological and assay data must be carefully studied to define the margins of these complex veins before any estimation of ore reserves may be made. Where multiple veins occur in a section, ore/gangue mineralogy, assays, character of wallrock alteration, and thickness of vein and mineralized hangingwall, median and footwall zones must be used to evaluate continuity of mineralized structures. Well-defined sections are projected into areas of increasing complexity. Once the vein boundaries are defined, metal concentrations, important metal ratios(Au/Ag, Pb/Zn, Cu/Zn), and true thicknesses of the vein provide the basic data for reliable ore reserve estimation."

Jan 1, 1991

By Kosta Fytas, Nour-Eddine Chaouai

"Selection of the appropriate kriging plan during indicator kriging estimations is of a paramount importance to the precision of ore reserve estimation. However, very little is known on the sensitivy of indicator kriging results when changing the kriging plan parameters (mainly search distance and number of samples). This paper evaluates the effect of the search distance and number of samples on indicator kriging results using a gold deposit as a case study.IntroductionBlock estimation using kriging is based on the autocorrelation function (variogram) on one hand and on the kriging plan on the other. As far as the variogram is concerned it is more or less subjectively adjusted and this is reflected on its parameters (range, sill, nugget effect and anisotropy). The effect of a poor estimation of these parameters on the kriging variance of ordinary kriging has been proven very important (Brooker, 1986). Choosing a kriging plan is generally a difficult matter depending on the estimation type (global or local). Generally there is not a unique kriging plan be cause there is not a unique structural analysis (variogram). There are no rules or dogmas in choosing a kriging plan but it is rather a function of the sampling pattern (David, 1982).Structural analysis requires the hypothesis of quasistationarity but very often either the data available within the zone of quasi-stationarity are too many so that the search distance is reduced during kriging or the data are too few to satisfy a stationary kriging system (Journel and Huijbregts 1978). As a rule, the larger the neighbourhood, the more precise the estimates should be , but for large neighbourhoods the hypothesis of stationarity does not always hold (Rivoirard 1987; Armstrong and Champigny 1989)."

Jan 1, 1991

By D. D. Hogarth

"IntroductionThe Hull iron range, comprising the Forsyth, Scott , Baldwin and Lawless properties (Fig. I), is in Gatineau Park, on the outskirt s o f the city of Hull , and about 6 miles (10 kilometres) northwest of the Federal Parliament Buildings.The deposits have been known many years and described numerous times, although the history has been treated lightly in former publications. Total ore shipments have been calculated at 122,700 long tons, of which over 80% were mined before 1900 and 74% in two brief periods: 1870-74 and 1880-82. It is surprising that the period 1870-74 has been overlooked by most authors and 1880-82 ignored altogether. More surprising, the essential data for these two periods are contained in manuscripts of the Robert Bell collection, which must have been available to officers of the Geological Survey o f Canada.The period 1801-1874 ha s already been covered by the writer in ""Pioneer mines”, but much information has come to light since publication. The present paper is therefore based o n new data and a fresh appraisal. However, little additional data were found for the early history (1801-1854) or for the legal cases involving A.H. Baldwin, and these parts were mainly summarized from the relevant sections of the above-mentioned publication.GeologyThe ore deposits are all situated somewhat below the middle of a graphitic, calcitic marble horizon, here folded into a northeast-plunging synform. The Forsyth, Scott and Baldwin deposits are on the south limb of the synform; the Lawless is on the north limb. The marble is underlain by three non-carbonate groups: biotite gneiss with interlayered quartzite (top), granite gneiss and skarn (middle), and biotite-garnet gneiss (bottom). Below these groups is a lower horizon of graphitic, calcitic marble. The whole sequence is Precambrian and has been subjected to high-grade (Grenvillian) metamorphism, but, in the north, is cut by an unmetamorphosed Cambro-Ordovician diabase dyke. For further information, the reader is referred to the summary by Baird."

Jan 1, 1983

By A. I. A. Salama, M. W. Mikhail, R. J. Mikula

"The Coal Research Laboratory (CRL) of CANMET along with other research organizations in coal-producing countries envisage major benefits from computer applications in coal preparation, Some of these benefits are greater system flexibility, improved coal preparation plant performance efficiency and efficient utilization of manpower, all of which result in economic benefits. Computers can be applied for both on-line and off-line purposes; this paper focuses on the on-line applications from the process control point of view.A critical discussion of the different analog and digital process control systems is presented. Recent developments in Great Britain, West Germany, Poland and Australia on automation and instrumentation using on-line measurements of coal ash and moisture contents are identified.The CRL research and development strategy aimed at achieving on-line computer control of an automated coal preparation plant is presented.IntroductionIn the past twenty years an enormous progress in the area of computer technology has been noticed. Computer applications in industrial processes offer greater system flexibility, improved plant performance efficiency and efficient utilization of manpower. Significant computer control development in mineral processing has already been achieved. Although progress has been made in the area of computer applications in coal preparation, more effort is needed to utilize the full potential.The computer applications in coal preparation can be viewed as off-line and on-line. Considerable progress has been reported in the area of off-line computer applications, especially in the areas of modelling, performance evaluation/prediction and statistical analysis. However, only modest progress in on-line applications has been reported(1-7). This paper will focus on: online instrumentation and process control applications, different analog and/or digital control systems, on-line automation and instrumentation in other countries and CRL strategy toward pilot plant automation."

Jan 1, 1985

By R. W. Zeindler, D. A. Fawcett

"A summary is presented of the report completed by the Coal Mining Research Centre in 1980. This report was of a cross-pit conveyor system applied as an auxiliary mining complement to the major stripping unit, a dragline. The purpose of the CMRC report was to evaluate selective mining and replacement of the upper horizons of the strata as an aid in reclamation. These strata were the topsoil, subsoil and glacial till.Past utilization of cross-pit conveyor systems and related engineering studies were assessed. The parameters of the study were based on the mining and geological conditions of the Alberta prairie coal mines. The principal excavator for stripping was a dragline. Excavation of the upper horizons was done by a bucket-wheel excavator discharging onto the crosspit conveyor. Alternative equipment applications were economically compared. Four cases or geological sections were evaluated in detail. The economics of the alternative mining systems for each of the cases were determined. In all instances, the most economical solution was a tandem system utilizing a dragline with a bucket-wheel excavator/ cross-pit conveyor system."

Jan 1, 1981

By J. C. Kurnia

Presence of fine dust in air causes serious health hazard for mine operators resulting in such serious problems as coal workers? pneumoconiosis and silicosis. Major sources of dust appear of course along the mining face where the minerals are extracted. Proper control and management are required to ensure safe working environment in the mine. Presented here is the use of a computational fluid dynamic (CFD) approach to investigate the flow and dust behaviour in mining tunnels. The objective of this study is to propose and examine various strategies to mitigate dust dispersion from the mining face and reduce dust concentration to a safe level for the operator. In a companion study, the authors investigated various methods for mitigating dust dispersion from the mining face to ensure safe dust concentration levels in the mine tunnel. Among the examined methods, implementation of brattice to direct the flow from the main airway to the mining face is the most effective method to disperse dust particles away from the mining face. The installation of brattice, however, will limit the movement of mine operators and vehicles in the tunnel. Hence, application of a hybrid brattice which is a combination of a physical brattice along with suitable directed and located air curtains is proposed and examined. Based on the CFD simulation results, over a range of parameters of interest, it was found that the physical brattice blocks the ventilation air and directs it to the mine face while an air curtain located along the brattice outlet offers flexibility in keeping the dust away from the operator allowing more freedom for the operator and the equipment. Results of the modelling over a range of parameters of interest are presented and discussed with the goal of managing dust concentrations within safe limits for the operator.

Aug 1, 2013

By M. S. Badollet

Introduction Very little fundamental research has been done on asbestos fibre to cake maximum advantage of its properties and to determine in what commercial products it can best be utilized. For the research chemist who is associated with asbestos development work, a thorough study of mineralogical information on asbestos deposits would furnish reliable information on the rock formations and the mineral impurities closely associated with the asbestos. Furthermore, ?he must have an intimate knowledge of the uses of the fibre in various products so that he can visualize the importance of the fibre and the role it plays in industry. Some of the properties of asbestos fibres such as strength, composition, length, harshness or softness, and mineral associates are of considerable importance to the manufacturer because they are responsible for many production difficulties. Fibre Strength It has been known for some time chat asbestos filaments have considerable tensile strength. These strengths have been referred to merely as 'weak' to 'very strong'. Not until recently have numerical values been applied to the strengths of asbestos fibres. But today we can take a thin fibre filament and mount it between two holders and apply a gradually increasing load or pull until the fibre breaks. By measuring the cross sectional area of the filament and the amount of load applied, we can calculate the tensile strength of the fibre in terms of pounds per square inch. This type of test is slow and rather difficult, but the fundamental data obtained furnish important basic information that can be applied to mechanical processing equipment and to certain asbestos products.

Jan 1, 1948

By H. Yasuhara, N. Kinoshita, S. Nakashima, K. Kishida

"In this study, flow-through experiments in fractured rocks have been conducted under different stress, temperature, and pH conditions so as to understand the evolution of permeability induced by these conditions. Throughout the experiments, the confining pressures and temperatures are well-controlled. Effluent concentrations are also measured for the ten elements of Si, Al, K, Fe, Ca, Na, Mg, Ti, S, and Cl that are included mainly in the targeted rocks. In the early stage of the experiments, the fracture permeability measured abruptly decreases with time, and subsequently reaches quasi-steady state within a relatively short period. In contrast, the permeability in the intact rocks monotonically increases with time. The permeability increase and decrease are attributed likely to the relative dominance of mineral dissolution in the pore spaces and to that of mineral dissolution/crushing at the propping asperities within the fracture and/or mineral precipitation onto the free surfaces, respectively. The evolving rates and magnitudes of the permeability are likely to be controlled by the stress exerted over the contacting asperities, temperatures, and pH of the permeant. Thus, this complicated behavior should be attributed to the coupled chemically- and mechanically-induced effects, which should be examined in more detail for longer period to contribute to the safe entombment of radioactive wastes. INTRODUCTIONUnderstanding of the flow and transport characteristics of porous/fractured rocks is required for the safe and long-term geological isolation of energy-related by-products (i.e., high level radioactive wastes and anthropogenic CO2). Notably, under relatively high temperature and stress conditions, mechanically- and chemically-mediated processes may alter the pore structures in rocks, resulting in an irreversible evolution of the flow and transport behavior. Augmentation in permeability may result from mechanical dilation due to shearing and mineral dissolution within the pore spaces, while reduction may result from reversible or irreversible mechanical compaction, mineral dissolution at the contacting areas, and clogging of pore spaces by precipitation of secondary minerals."

Jan 1, 2015

By C. H. Bertoni

"The Superior Province of the Canadian Shield is the largest gold producing area within Archean greenstone rocks in the world, with total production of over 140 million ounces of gold. One hundred and fifty-five mines have individually produced more than 8,000 ounces, although only a relatively limited number of deposits (33) produced more than one million ounces of gold. The output from these 33 deposits accounts, however, for 85% of total gold production. The majority of grades (68%) ranges between 0.10 and 0.30 ounce per ton, and there is no linear relationship between grade and tonnage.Development of new gold mines reflects the history of gold prices. However, the response to the latest increase in gold prices was not as marked. It is concluded that gold deposits are becoming increasingly more difficult to find and new exploration techniques are urgently required.IntroductionWith most of its production coming out of the Superior Province, the Canadian Shield is the largest producer of gold from Archean greenstone rock s in the world. In total gold production, the Superior Province is surpassed only by the paleo-placers of Witwatersrand and the placers of the USSR (Anhaeusser, 1976). There has been no attempt so far to compile the historical production of the Province as a whole in a single document. The aim of this work is to fill this gap, not only for the convenience of having a complete list of gold producers, but, more importantly, as a basis on which to study the tonnage and grade characteristics of these deposits."

Jan 1, 1983

By S. I. Vobnout, J. Wm. White, J. P. Olson

"Mine management now recognizes the value of computer-based truck-shovel dispatching in open pit mines. The key tangible benefits are substantial productivity increases with a given fleet of equipment or, alternately, significant reductions in equipment required to meet production quotas. In this paper, the authors review the literature, report on efficient, optimal algorithms for haul truck dispatching in real-time, and briefly discuss methods used by various mines to evaluate productivity improvements over manual methods. Actual results obtained at thirteen mining operations around the world are also presented.IntroductionModular Mining Systems manufactures, installs, and supports its computer-based DISPATCH system at mines worldwide. DISPATCH is a large scale, computer-based mine management system which controls the dispatching of all haul trucks in any open pit mine (Fig. 1). When increased production is important, DISPATCH gets the needed production increase with fewer new or recommissioned trucks. DISPATCH also helps operations meet its blending objectives while minimizing rehandle and maintaining production. Furthermore, DISPATCH includes a powerful, eventdriven simulation subsystem. With the simulator mine management can pose ""what if' situations and see the predicted effect on production"

Jan 1, 1993

By McGill Metals Processing Centre, S. Chang, L. Calzado, X. K. Cao, C. H. Hsin, M. Isac

"Due to the increasingly stringent cleanliness requirements for final steel products, there has been a growing interest in the possible use of micro-bubbles for the removal of inclusions with diameters smaller than ~50µm, present within the steel passing through a steelmaking tundish. However, several technological barriers have prevented the adoption of this technique in industry. These are related to a) the generation of micro-bubbles in liquid steel, b) the measurement of bubble size distributions, and c) the optimization of bubble injection conditions to create micro-bubbles. In the present study, a novel Aqueous Particle Sensor (APS) system was developed for the in-situ, on-line, detection of micro-bubbles in water, generated by a newly designed full-scale ladle shroud, located at McGill Metal Processing Centre (MMPC). Measurement results from the sensor were validated against bubble size data collected through a high speed camera and post-processed through the commercial software, Image J.Control variables and orthogonal experiments were designed to assess the dependence of average micro-bubble sizes and bubble size distributions on key experimental parameters. Those chosen were the air inlet flowrate, the distance of the gas injection port from the slide gate, and the number of injection ports used. The investigation demonstrated that the APS system can be successfully adapted to detect micro-bubbles up to ~800 micron diameters. Using this novel sensor, it was shown that multi-port injection using low air inlet flowrates, closer to the slide gate, were useful in forming small micro-bubbles within the flow through the ladle shroud. The results from the APS system were compared and validated against data resulting from an optical technique. INTRODUCTIONModern industry expects increasingly stringent cleanliness requirements for final cast products. Therefore, the numbers and sizes of inclusions need to be strictly controlled in steelmaking operations. Thus, the cleanliness of steel products depends on the amount, morphology and size distributions of nonmetallic inclusions in steel (Zhang L. & Thomas B., 2003). Since large, deep, tundishes provide longer nominal residence times for liquid steel passing through it to the exit SEN’s, this can provide the ideal place to separate inclusions, and bubbles can assist by removing help attach inclusions and float them to the top surface."

Jan 1, 2016

By T. Lamb, T. Aston

"The Gays River Mine is located within a complex hydrological regime and underground mining environment. Early in the mine history, the operation was' affected by an inability to control mine water inflows. More recently, the reopened mine operation had been unable to maintain consistent drainage of groundwater to the mine workings and sustain low groundwater levels.In 1992, a series of investigations were completed, which in part Were funded under the Canada-Nova Scotia Mineral Development Agreement. The studies undertaken included: hydrochemical and drainhole well screen assessments, an air photo study of sinkhole features, numerical modelling studies and a major piezometer installation and overburden soil study. The results indicate that the water draining to the underground workings is comprised of two distinct components: precipitation over the drawdown cone catchment area and seepage from the nearby Gays River. In addition, a third ""balance"" component was' also found, which represents uncertainties in the areal extent of the drawdown cone and river seepage components.After outlining the history of the groundwater problems experienced at the Gays River Mine, this paper examines the various studies undertaken during 1991-1992 and concludes that control of groundwater levels in the mine area is achievable. A number of recommendations are also proposed for future study ."

Jan 1, 1993

By H. Stocker, C. E. Makepeace

"This paper presents the statistical analyses of several sets of data acquired in several programs of sampling of radon daughters in uranium mines. The measurements were taken over periods of days or weeks for given locations or location occupations within these mines. Because the sampling applies to specific intervals of time and specific locations, a method is suggested f or the eventual application of a monitoring program which would be suitable on an annual basis for these locations. The present data and analyses thereof are not justifiably applicable to a monitoring regimen on an annualbasis, without a number of additional assumptions.The aim of the present analyses of concentration measurements is the determination of the minimum number of measurements required to achieve an annual radon daughter exposure estimate, for individual workers, having an error no greater than 50% at the 95% confidence level. The criterion of accuracy is taken from a statement in the American National Standard, Radiation Protection in Uranium Mines (ANSI NI3.8-I973), and is currently used, in somewhat modified form, as a guide to uranium mining licensees in Canada. Uncertainties associated with occupancy time are ignored in the present analysis. IntroductionOne of the principal aims of any scheme of radiation protection is that of improving the accuracy of exposure estimation for workers. The example presented here is from the area of radon daughter exposure estimation for uranium miners. The conventional means of estimating workers' exposures is grab sampling of radon daughter concentrations combined with occupancy time weighting in the various work and travel locations. Uncertainties exist in each of these components, and in an environment of highly variable radon daughter concentrations (such as an active uranium mine) one is always uncertain as to the representativeness of the grab sample (compared to the average concentration) unless a sophisticated monitoring scheme has been implemented based on previous experience in such an environment.Improvements in the accuracy and precision of employee radon daughter exposure records depend, primarily, on three factors;"

Jan 1, 1980

By J. R. Morris

"A hoisting plant design should satisfy two basic requirements:1. to provide the necessary materials handling capacity, including ventilation where applicable, while meeting the requirements of good practice and, as a minimum, government regulation; and2. to optimize the economics of the project. Selection of hoisting equipment to meet the first objective is a complex but logical engineering process. The necessary calculations of payloads, accelerations, speeds, rope strength, hoist size, and power requirements are very readily carried out on computers or programmable calculators. A variety of hoist options can be quickly examined to assess the effects of changes in design parameters.Meeting the second requirement involves balancing the costs of various hoist arrangements and shaft designs, together with the time cost effects of differing shaft sinking rates and potential advances to be gained by concurrent level development. The proposed mine layout is significant here, as is the possibility of future shaft deepening and/or production increase. The availability of used equipment may be significant, both as regards first cost and delivery time. The factors are interactive, with their relative effects .varying from project to project. This paper sets out the primary factors to be considered."

Jan 1, 1990

By F. Rosenblum, P. Spira

"Self-heating of broken sulphide ore or waste rock underground can lead to ignition and cause serious problems in a mine operation. An extensive study has demonstrated that it is caused by oxidation of certain species of pyrrhotite. Self-heating was found to take place in two stages, first progressing from ambient temperature to 1000C with exothermic formation of elemental sulphur in the presence of moisture and oxygen, and proceeding to a second stage in which the sulphur oxidizes to SO2. Ignition may eventually follow. An apparatus was developed to assess the propensity of sulphide rock to self-heating and the potential for hazardous behaviour. The effect of temperature, time, rock size, and surface treatment with chemicals is presented. On the basis of these results, possible approaches for preventing a runaway reaction are suggested for further investigation.IntroductionThe oxidation of sulphide ore, waste rock or tailings backfill, which may cause hazardous conditions underground through heating, oxygen depletion and, in some cases, fire, is well documented (Farnsworth, 1977; Ninteman, 1978; Rosenblum et al., 1982; Reimers, 1987). The self-heating mechanism, nevertheless, has not been satisfactorily explained. The onset of heating from ambient temperature, in particular, has not drawn the attention of researchers. In the course of a previous study (Rosenblum et al., 1982) aimed at finding a method to assess the hazard from using sulphide tailings as backfill, the authors developed an apparatus to measure self-heating rate under controlled, near ambient conditions. This has since provided decisive information in backfill investigations in the Noranda Group.The test methodology devised for tailings failed to predict self-heating in a broken waste rock known to be active. Upon repeated testing, however, a freshly crushed sample began to exhibit appreciable heating and oxygen uptake (Fig. I). After 14 tests, the self-heating rate reached a plateau of about 4O°C/h and then fell progressively to < 5°C/h after 30 tests. It was hypothesized that weathering in the presence of moisture and oxygen during testing had caused the onset of self-heating. Active tailings, on the other hand, are exposed to natural surface oxidation and need not be weathered to show heating. Based on this finding, a new apparatus was developed capable of simultaneously weathering a sample of rock and monitoring its self-heating behaviour."

Jan 1, 1995

By T. Alan O'Hara

"Annual mining revenue can be computed by formulae relating metal prices, smelting schedules, concentrate grade and recovery to known ore grade and an assessment of core samples. Operating costs at different daily tonnages are related to orebody shape, mining method, milling process and general plant services. Capital costs are related to sizing of mining equipment, mine development, plant-site topography, climate and accessibility, plant services and personnel housing. IntroductionA crude guide to the average 1978 cost of mine projects is shown in Figure 1, but the costs of many mine projects have differed widely from the graphed average costs of $800,000 T0.6 for underground mine/mill projects and $400,000 T 0.6 for low-grade open-pit mine/mill projects.High mine project costs and high operating costs are characteristic of open-pit mines with high stripping ratios, underground mines with thin orebodies, mills with complex metallurgy, and projects located in isolated regions with severe climate, mountainous topography, and lacking access to existing roads, towns and electric power. When none of these adverse conditions prevailed, the mine project cost was typically much less than the graphed average cost. Virtually all the conditions likely to cause high capital and operating costs are known from knowledge of the local topography, climate or accessibility, or can be assessed by tests on core samples, as soon as the orebody has been outlined by drilling .A more accurate estimate of over-all project capital cost and operating cost can be made from a summation of items of cost after judging the effect of specific local conditions on each item of capital and operating cost. This paper offers guides in judging the effect of local conditions on the sizing and 1978 cost of specific items of capital cost and operating cost and operating cost of mine projects. When the specific items of capital cost and operating cost are totaled and measured against expected net revenue and taxes over the life of the mine using the net-present-value or discount-cash-flow methods, the result should show whether the mine project development is clearly feasible, doubtfully feasible or clearly uneconomic. If the development of the mine project is clearly feasible, or probably feasible, a detailed feasibility study by experienced consulting engineers should be commissioned before any financial commitments are made; but if project development appears to be uneconomic, the time and cost of a detailed feasibility study is not warranted."

Jan 1, 1980

By Kurt D. Mitchell

"This paper discusses general application for A C variable frequency drives in the mining industry. A review of induction motors characteristics, adjustable frequency controller fundamentals, and three commonly used controllers is presented. General application guidelines for the three different types of controllers; variable voltage input , current source input and pulse width modulated are then reviewed in detail, and an example of the economic benefit of this technology is discussed. IntroductionSoon after static DC variable speed drives were well established in industry, a need for static AC variable speed drives was seen. The first technical papers describing possible systems appeared in the mid-1960s, with commercially available units arriving in the early 1970s. Without exception, static AC drives are substantially more complex than their DC counterparts, but they have some very desirable properties. As compared to DC motors, AC motors are less costly, physically smaller, more reliable, require less maintenance , easily sealed, have good load regulation, are able to run at higher operating voltages, and have little danger of over-speed runaway . These properties are particularly desirable in explosion-proof, submersible or difficult accessibility applications.Variable speed AC drives are now a proven technology. available in packages from Sub-horsepower to hundreds of horsepower, from 115VAC to 4160 VAC. This paper covers the principles of operation of three common types of controllers, application criteria, motor consideration and finally an example of how an AC variable speed drive can pay for itself in terms of energy savings."

Jan 1, 1986

By J. B. Hinzer, J. D. Harvey

"Noranda&apos;s Lyon Lake property in the Sturgeon Lake area of Northwestern Ontario was staked by Mattagami Lake Mines Limited in May 1969 to cover airborne Input anomalies. Subsequent ground geophysical and diamond drilling programs resulted in the disco very of the Boundary Extension, Lake and Creek ore zones. As of December 31, 1978, ore reserves were estimated at 3,945,000 tons assaying 6.53 per cent Zn, 1.24 per cent Cu, 0.63 per cent Pb, 3.42 oz/ton Ag and 0.010 oz/ton Au.These deposits are hosted within the South Sturgeon Lake volcanic pile of Archean age, which consists of several cycles of basic intermediate and felsic volcanic materials overlain by a sedimentary iron formation and built upon a plutonic base (Franklin , &apos; 1975). The top 50 m of the second felsic cycle, according to mine terminolo gy, contains the mineralization within Quartzphenocryst- bearing felsic lapilli tuff and underlying thin discontinuous graphitic sediments and altered coarse pyroclastics. The basal andesitic member of the overlying cycle forms the hanging wall to the ore deposits.Although there is no alteration pipe below the deposits, the coarse footwall rocks are permeated by chlorite, garnet, carbonate, iron sulphide and magnetitie-bearing veins intensifying from west to east.Immediate host rocks are alkali depleted and MnO, FeO, Zn and Cu enriched compared to Goodwin&apos;s (1972) average Archean rhyolites. Bedded pyrite-pyrrhotite-chalcopyrite lenses with sphalerite-rich tops are underlain by weakly developed stringer mineralization.Traversing eastward from the Lake Zone to the Creek Zone and toward the Sturgeon Lake Mine deposit, more rapid facies changes, more pronounced chloritic and carbonate alteration, the presence ofgarnets, greater MnO, FeO, CaO and Ag abundances, and increasing Zn/Cu and MnO/FeO ratios are apparent."

Jan 1, 1981

By W. E. Cockfield

"The Stump Lake mining camp is in Nicola mining division of southern British Columbia. It lies about halfway between the cities of Kamloops and Merritt.The deposits at Stump Lake are among the earliest lode discoveries of British Columbia, many of the claims having been staked between 1882 and 1885. A considerable amount of work was done prior to 189Cl, after which very little was done until 1916. Since that time mining has been carried on at intervals, much of it on the same deposits, by a number of companies, including the Donahue Mines Corporation, the Planet Mines and Reduction Company, the Nicola Mines and Metals Company, the Consolidated Nicola Goldfields, Limited, and others. According to the British Columbia Department of Mines, total production from the area has been: gold, 8,520 oz.; silver, 259,413 oz.; copper, 40,822 lb.; lead, 2,208,859 lb.; and zinc, 367,869 lb. Most of the production has come from the Enterprise vein and a branch of the Enterprrsethe King William vein."

Jan 1, 1954