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By Ben D. Thompson

Cemented Paste Backfill has proven to be of critical importance to the operation of a number of Canadian mines, primarily due to the rapid backfilling rate this method permits. In order to improve the efficiency of this backfill system (i.e. optimize binder contents, fill fence design, and the employment of two stage filling strategies) there is a requirement to better understand its geomechanical behaviour. In response, in-situ experiments have been conducted in long-hole stopes to quantify the evolution of total earth pressures and pore pressures at a series of instrumented points within both the core of the backfill and close to fill fences. The deflection of fill fences as a result of paste loading has been measured and additional instrumentation has also been employed to measure cement hydration, negative pore pressures, and blasting induced vibrations within fresh and cured paste backfill. Installing geotechnical instrumentation within an open long-hole stope can be an extremely complex procedure and this paper details the methods that have been successfully employed. Preliminary results are presented, and the pressures induced by backfill with differing binder contents, at a number of different in-stope locations are considered.

May 1, 2009

By A. M. L. Cushing, S. Kelebek

Presently, adsorption is one of the effective methods of removing toxic contaminants from waste waters. The contaminants from metal mining industrial operations include an effluent water containing various types of heavy metal species at concentrations beyond the maximum allowable limits, which are 0.5 ppm and 0.3 ppm for nickel and copper species, respectively. Adsorption behavior of copper ions pre-chelated with diethylenetriamine (DETA) and triethylenetetramine (TETA) onto natural bentonite and peat has been investigated. Both natural bentonite and peat was found to be capable of removing these copper-polyamine complexes from aqueous solutions relevant to process water effluents. However, the adsorption capacity of bentonite was significantly higher than that of peat. Two models were used to study the adsorption kinetics: a pseudo-first-order rate expression and a pseudo-second-order rate expression. For both adsorbents, the data conformed best to the pseudo-second-order rate expression. Representation of the experimental data through adsorption models was also investigated. Out of the four cases considered, namely, Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms, it was found that for both bentonite and peat, the copper polyamine adsorption data conformed best to the Dubinin-Radushkevich adsorption model. The Langmuir model also represents the bentonite-copper polyamine adsorption system reasonably well as the second best case, suggesting that the amount adsorbed on bentonite might be a monolayer with strong affinity.

Jan 1, 2015

By S. P. Cashin, D. Kashuba, W. Esplin

Barrick has had 6 autoclaves in operation at the Goldstrike Mine, North of Carlin Nevada, since 1993. The 6 autoclaves operate in parallel, processing slurry of gold ore. The gold in the ore is predominantly associated with, and encapsulated by, sulphide minerals. It is necessary to oxidize at least 90% of the sulphide mineral before the gold can be concentrated using a cyanide/carbon-in-leach (CIL) circuit. Sulphide oxidation chemical reactions occurring in the autoclaves are exothermic; however, the sulphide content in the ore is not high enough to operate the autoclaves in an auto-thermal mode. Heat from steam is added to the first 2 of 5 autoclave compartments to initiate the sulphide oxidation reactions. The steam used to heat the autoclaves is supplied by three boilers, which are fuelled with propane gas. The completion of a few operations and maintenance projects in the last 2 years has resulted in a 50% reduction in propane energy requirements. The autoclave operating temperatures were minimized. Excess oxygen addition was held as low as possible. The material of construction for the compartment walls inside the autoclaves was changed from brick to Titanium metal. And, the speed of the autoclave slurry agitators was increased. All of these activities had an impact on the propane energy requirements of the autoclaves. Presented below is a description of the autoclave systems, and a discussion of how the energy needs were reduced, resulting in significant operating cost savings.

Jan 1, 2004

By George S. Rice

Foreword Explosion hazards differ widely in the mines of different fields or coal basins. They also differ as between different mines in the same basin or fold, because of variations in gas entering the mines, and because dust conditions and explosion hazards are affected by the mining methods employed and the organization of the work. It is unquestionably true, however, that there are greater differences in explosion hazards in mines of different coal fields or basins than between different mines of the same field or basin. In these respects, the coal fields and individual mines in Alberta are not exceptional. The same conditions obtain in various countries where coal is mined, and are found in single States, as for example in Colorado, where coals are mined ranging in character from sub-bituminous to anthracite, and in attitude from flat horizontal to steeply pitching beds. The U.S. Bureau of Mines, at its experimental mine near Pittsburgh, Pa., has made large-scale tests of the relative explosibility of dusts of coals, ranging in rank from Wyoming sub-bituminous coal containing 19 per cent moisture, to anthracite from Pennsylvania, and including samples from a mine in the Crowsnest Pass district, B.C., and from a Vancouver Island mine. The Bureau has also made similar tests of the dust of coal from a Yorkshire mine which the British Safety-in-Mines Research Board uses as standard.

Jan 1, 1927

By R. W. Lawrence

"The management of acid rock drainage( ARD) to prevent impact when tailings are disposed of in the environment requires understanding of the phenomena giving rise to acidic drainage, a rigorous evaluation of the weathering characteristics of the tailings, and the successful implementation of control measures that will be effective in the long term. This paper provides a brief theoretical background to the complex reactions taking place in mill tailings containing residual sulfide minerals which must be appreciated to enable waste characterization program to be effective in predicting the future behavior of the tailings and in designing control methods which will work. The principals and practice of prediction and control as part of an ARD management strategy will then be discussed.Paper Not Available at Time of Publication"

Jan 1, 1997

By F. Chiesa, Jeremy Carignan, B. Duchesne, D. Levasseur

"Aluminium A206 (AlCu4) is one of the strongest aluminium casting alloys with tensile properties approaching those of ferritic ductile iron. If the specification on the silicon content (< 0.05%) is easy to achieve during alloy ingot production, it is not the case in a foundry, where returns are used which are not perfectly cleaned from the silicate containing molding sand (Olivine). In alloy A206, the Si content is controlled in order to avoid the formation of a low melting point intermetallic phase (such as phase Q Al5Cu2Si6Mg2); these phases will melt during the solutionizing heat treatment to which alloy A206 must be subjected to develop its outstanding mechanical properties. This incipient melting may deteriorate the mechanical properties of Alloy A206 if the solutionizing treatment is applied at the standard temperature of 530°C.In the present study, a lower temperature solutionizing (520°C) was applied to a high Si content 206 alloy in order to reduce or eliminate the possible incipient melting. This was carried out on a complex shape industrial casting weighing 14 kg (31 lb) and 560x410x250 mm (22x16x10”) in size poured in aluminum 206 with a high silicon content (0.22% vs 0.05% max for alloy A206). Twenty ASTM E8 subsize tensile specimens were excised from two locations in the casting in order to compare the tensile properties for the two solutionizing temperature used (530 and 520°C). Optical and SEM microscopy allowed to investigate the causes of the differences in the properties observed between the 2 zones of the casting studied for 3 different heat treatments. INTRODUCTIONIn spite of their “textbook” outstanding mechanical properties (Up to twice the strength and elongation of the widely used A356 alloy), aluminum-copper alloys of the 2xx series are seldom used because of their propensity for hot tearing [Li, 2011], the segregation of copper [Cho, 2003], and their sensitivity to stress corrosion cracking [Jean, 2009, p. 113)]. Also, because of their wide freezing range and high thermal conductivity, a wide mushy zone makes feeding difficult, unless strong temperature gradients are created by liberal use of chills and risers in the critical zones of the part. Because they are prone to hot tearing, grain refining of Al-Cu alloys is particularly important, titanium playing a major role in the process [Sigworth, 2003]; grain refining has also been shown to be beneficial to fatigue strength [Jean, 2009, p. 103]. The practical basis of foundry practices pertaining to these alloys is outlined in an AFS webinar [Weiss, 2014]."

Jan 1, 2016

By M. Phylli Bray

"Concurrent with the continuing demise of many Canadian mining towns is the rise of a new method of providing remote mine sites with a workforce. This is the Long Distance Commute (LDC) which uses commuter labour and requires no permanent settlements to support the mine operation. It provides a flexible and cost effective method of operation to the industry and relieves both governments and industry of the expense of building and maintaining mining towns. However, little attention has been paid to the effect on workers or their families of the LDC work schedule whereby workers spend a fixed number of days at the site followed by a fixed number of days at home. Off-shore oil rig experience would indicate that negative social impacts may be expected. Research leading to an understanding of the problems involved seems to be indicated. One innovative suggestion has been to use already established but dying mining towns as workforce pick-up points for new LDC operations further north.BackgroundUntil recently, mine towns were considered as a necessary component of mine development. This was a natural symbiosis resulting from the need to provide workforce accommodation close to isolated mine sites. The early mine communities in Canada were often just a huddle of shacks around a head frame. Gradually mining companies began to provide housing which varied from basic duplexes and quads in grid pattern layout to professionally planned and designed towns, either model company towns or the more recent suburbs-in-the-bush, the so-called ""instant towns"" of the postWorld War II era of resource development. The improvement in accommodation reflected the need to attract a stable workforce as mine operations became more sophisticated. City amenities were expected and offered in these mine towns as a way of encouraging a permanent community of mining families. Indeed in towns like Manitouwdage, Schefferville, and others, it was not unusual to find a significant percentage of two- and three-generation families apparently providing the permanent mining communities so desired by mine operators."

Jan 1, 1991

By M. S. Badollet

"The study of the physical properties of asbestos minerals requires a careful isolation of the fiber from the wall rock and, at a later stage, a comparison of these physical properties with those of fibers that have passed through the milling and beneficiation processes.The effects of mineral impurities, loss of fiber length and the formation of extreme fines (asbestic and/or associated minerals) often show up in the formation of special asbestos products as well as in the commercial production of asbestos papers, mill-boards, asbestos cement products, plastics and insulation materials, and in the filtration of blood plasma and wines.Numerous test methods have been developed in Canada and in England for use in the asbestos industry. Special treatments of asbestos fibers have been used to improve their physical and chemical properties and to eliminate impurities.Numerous problems connected with the use of asbestos fibers are discussed, such as the effects of asbestos on filtration, surface area, surface treatments using organic or inorganic materials, the surface charge on the fiber, the presence of magnetite and air pollution elimination. Biological studies on finely ground asbestos, when dispersed in 0.9 per cent sodium chloride solution and then sterilized and injected into hamsters, show that by reducing the dose, the tissue damage can be largely avoided. In these experiments, Arizona asbestos fibers were carefully extracted from the wall rock, finely ground, and examined chemically and micros-copically for any mineral impurities that might be present so that any effect on the hamsters would be directly due to the presence of the asbestos. The harsh Arizona fiber induced more extensive tissue response than the soft fiber when tested in hamsters."

Jan 1, 1969

By A. Mitrašinovic, A. Wolf

"The aim of this investigation was to determine the most suitable additive for recovering metals from converter slags generated during Ni extraction. Fluxes analyzed were silica and lime and reductants included pig iron, ferrosilicon and copper-silicon compound. Slag was settled at 1300°C for one hour to simulate the smelting environment. The newly formed matte and slag were characterized by chemical composition and morphology. Microstructural studies showed that slag formed after adding reductants consisted of primarily fayalite, with traces of magnetite. Entrained matte was present in the slag mostly as prills of Ni3S2-FeS matrix and a Cu2S-FeS secondary phase below 10µm in diameter. Kinetic parameters of matte formation, valuable metal recovery rates and partition coefficients were deduced. Silica additions generated higher partition coefficients for copper and nickel than the addition of lime. Additives used as reducing agents had higher valuable metal recovery rates and partition coefficients. Silica additions favoured the formation a higher grade matte while lime additions will hinder metal recovery. Pig iron, ferrosilicon and Cu30Si were the most effective reductants for valuable metals recovery. Cu10Si and coke additions had little to no effect on valuable metals recovery."

Jan 1, 2015

By B. Chambers, M. Yunovich

"Corrosion monitoring is commonly used in a variety of industries as a means of effective corrosion control programs to extend the life of the asset and ensure safe operation of the facilities. The majority of the monitoring tools have limitations and tradeoffs – e.g., sacrificing the longevity of the probe for higher measurement resolution. Linear polarization resistance (LPR) probes have the advantage of providing the operator with accurate, real-time corrosion rate data; however, the probes can only be deployed in conditions where the measured environment possesses certain minimal conductivity. In many instances, utilization of LPR probes in conditions with intermittent wetting (for example, conditions where the temperature fluctuates above and below the dew point) presents a challenge. To address this limitation, a special-design cooled corrosion probe has been developed, commercialized and integrated into the distributed control system in the plants. In addition to high-accuracy measurement of corrosion rates, the probe allows for monitoring of pitting corrosion. The most innovative feature of the probe is the cooling circuit, which brings the temperature of the sensors below the dew point, forcing precipitation of moisture and thus permitting corrosion measurements. Additionally, the probe was found to be well-suited for monitoring corrosion in crude distillation unit (CDU) overhead space, where condensation of hydrochloric acid may take place at relatively high temperatures, which would require relatively moderate amount of cooling to be imparted to the probe sensors. This paper presents laboratory-based data from a test simulating CDU refinery environment. A case study is presented to demonstrate how the cooling probe can be effectively used in the plants for corrosion monitoring.INTRODUCTIONConventional corrosion-monitoring techniques such as weight-loss coupons to assess corrosion damage are commonly used in plants1. However, the use of coupons is not only labor-intensive, but also does not deliver real-time corrosion data, thus effectively serving as a “backwards-looking” monitoring tool. Linear polarization resistance (LPR) probes have the advantage of providing the operator with accurate, real-time corrosion rate data; however, the probes can only be deployed in conditions where the measured environment possesses certain minimal conductivity."

Jan 1, 2012

By P. Mundell, R. Torbin

"There are many physical and operational obstacles in pipelines that make the passage of inspection robots impossible including:•,Small radius bends•,Low operating pressure•,Plug valves•,Large changes in pipe size•,No permanent access to the pipeline.The inspection of unpiggable pipelines requires the marriage of a highly agile robotic platform with NDE sensor technology operating as an integrated system. Foster-Miller and GE/PII are developing a robot that is essentially a battery powered, train-like platform. Both front and rear tractors propel the train in either the downstream or upstream direction. Like a train, the platform includes additional ""cars"" to carry the required payloads. The cars are used for various purposes including the NDE sensor module(s), the power supply, and data acquisition/storage components. The robot is designed with a slender aspect ratio and the ability to change shape as required by the physical obstacle presenting itself. The MFL sensor module must also morph itself through the physical obstacles, and thus, will require some level of segmentation. The segmented MFL magnetizers and transformable sensor module represent a major advance in the science of sensor technology and pipeline inspection."

Jan 1, 2005

By J. B. Morrow

Methods of Coal Preparation Fundamentally, the object of coal preparation is to increase, economically, the value of a fuel by making it more suitable to the uses of the consumer. This can be accomplished in three major ways: 1.Screening or sizing 2.-Mixrng or blending 3.-Cleaning By combinations of any or all of these methods we can prepare coal to meet standard specifications-a process of standardization which is the more desirable the more nearly it approaches the unvarying quality of packaged goods, where the package you buy today and tomorrow is the same as that you bought yesterday. It should be noted that it is readily possible to get good cleaning and still have poor preparation because of faulty screening and mixing, and, on the other hand, it is possible to get a passable grade of cleaning, combined with good screening and mixing facilities.

Jan 1, 1931

By H. A. Hamza, J. Visman

"This is a report on the combined application of ""long-chain"" flocculants and classifier cyclones in the field of slimes treatment, with emphasis on the simultaneous thickening and clarifying of industrial effluents, at low cost. The principle of the process described below involves: (1) the formation of small floes of relatively great strength, by sequential dispersion and conditioning, with average floe size of about 1501 microns; (2) the floes being of sufficient strength to withstand the shearing forces operating within a cyclone and consequently behaving as solid particles with an equivalent diameter (Stokes) that exceeds the size cutpoint of the classifier cyclone; (3) the removal of flocculated solids by means of a classifier cyclone the size cutpoint of which permits effective separation of these solids from the water. Results of test work to date indicate that a broader use of cyclones in industry is possible with the above types of flocculants because the submicron particles and colloidal material are readily collected and clear water is produced, with the attendant advantages of compact construction and low cost that are characteristic of centrifugal separation. The process generally permits classifier cyclones of medium throughput capacity (e.g. 12-in. diam.) to be used for clarifying effluents that contain minus 10-micron particles."

Jan 1, 1973

By C. R. Edwards

"Equity Silver Mines Limited, Canada&apos;s largest silver mine, has designed, built and operated a leach plant to reduce the levels of antimony and arsenic in its silver-gold-copper flotation concentrate. The orebody contained deleterious antimony and arsenic minerals in such proportions that the economic long-term sales contracts necessary to obtain project financing could not be procured. Construction of the leach plant therefore allowed development of the mine to proceed. Although the plant took some time to reach design throughput and product specifications, due to the complex and unique nature of the operation, these goals were successfully met and surpassed. This paper describes the physical plant and/or process technology modifications made to mold the main processes-concentrate leaching and filtering, autoclaving and filtration of by-products, and crystallization of salt cake-into an effective, economic operation.IntroductionEquity Silver Mines Limited, a member of the Placer Development Group, owns and operates an open-pit silver mine and related facilities located 37 kilometres southeast of Houston in north-central British Columbia. The mine occupies a 44 I-hectare (1089 acre) site at an elevation of 1300 metres (4265 feet) on the Nechako Plateau. Producing a copper concentrate containing high values of silver and gold, it is the largest silver mine in Canada and one of the largest in the western world. Equity stresses open communications, positive motivation, and production with safety, and achieved the best mine safety record in western Canada in 1984."

Jan 1, 1985

By L. V. Bell

THE object in prospecting is to find ore. With the exception of certain discoveries of more or less accidental nature, intelligent prospecting as conducted today is, whether consciously or not, based upon a process of elimination. In the following discuss on it is proposed to evaluate those factors that enter into the eliminating of certain tracts of ground and, conyersely, the concentrating of attention upon others. The danger of generalizations as to the barrenness of cer.ain areas, without having due regard for all such factors, is emphasized. The fact that our conception as to what areas or rock formations are to be regarded as favourable or unfavourable is, in some measure at least, changing with new discoveries under diverse and unexpected circumstances, adds more point to the discussion. The criticism might be raised that the subject is treated largely from the standpoint of geology, but that may be met by stating that it is, and must continue to remain, precisely from this standpoint that the prospecror directs his activities. Briefly, the geologist may render the greatest service to the prospector in the early steps of selecting (a) the general territory in which to prospect; (b) the area to be intensively prospected; and, finally, (c) those parts of the claim or claims to be prospected in detail. Although certain phases of the discussion will be, in some measure, of general application, we shall here concern ourselves essentially with prospecting in the pre-Cambrian shield. Furthermore, the subject is so large that it has been decided to limit it to a consideration of that portion of the pre-Cambrian rocks in which is situated the mining district of western Quebec, of which the writer can speak with more personal knowledge. This limitation need not, however, seriously detract from whatever merit the discussion may possess, since the deposits concerned cover a fairly wide range of metallic ores, including gold, copper with associated zinc, and, lastly, molybdenum.

Jan 1, 1936

By Anton Gronningsater

AT the present time we hear a great deal about organization of labour, collective bargaining, workmen&apos;s councils, and company unions; about C.1.0. with its principle of vertical unions and A.F.L., largely based on craft unions; and about provincial and federal laws for protection of labour&apos;s right to collective bargaining. What we perhaps hear too little about is corresponding organization of the employers, although it recently is mentioned more frequently. I will only mention W. H. Davis, Chairman of the United States War Labour Board, who has had and is having plenty of experience in this field and has also studied labour conditions in Europe-in Sweden for instance. He has repeatedly expressed the opinion that where employer-employee problems are involved, a thing badly needed in America is organization of employers as well as employees to get some order in the present chaos. With this I agree. I believe a strong organization on one side necessitates a correspondingly strong organization on the other side; that has at least been the experience in the industrialized countries in Europe. I happen to be fairly familiar with conditions in Norway, where they have struggled with these problems for fifty years, and a talk on the history, development, and present state of employer-employee relations in that country might perhaps be of interest as giving a general picture of the development of such relations in the northwestern European countries as a whole. The talk was originally given to the Fourth Year students in Mining and Metallurgy at the University of Toronto. I have changed it somewhat to fit a different audience, but I hope you will make allowances if you now and then are reminded of the school auditorium. I will try to be as objective and factual as possible, but it is probably unavoidable that some of what is said is coloured by personal opinion.

Jan 1, 1943

By R. N. Chakravorty

Environmental monitoring plays a key role in coal mine safety. In recent years, significant advances have been made in the development of systems suitable for monitoring air in underground coal mines. Because of intensive mining and large capital outlay, the need for higher productivity consistent with safety is well recognized and it appears that environmental monitoring may help achieve this objective. This paper reviews the state-of- the-art in the monitoring technology with particular reference to hazardous gas detection in underground coal mines. The preliminary results obtained from ongoing studies, with regard to continuous monitoring of methane and carbon monoxide in mine air in some of the operations in Western Canada, are discussed. The inadequacies of the methods using spot samples are examined and the need to supplement the present practice with continuous monitoring systems is emphasized.

Jan 1, 1979

By S. Manning, W. Morris

Mineral exploration assessment file information has long been considered a useful resource for developing mineral exploration strategies, and one of the most common data sets fled in assessment reports is ground magnetic surveys. The new Earth Resources and Land Information System database (ERLIS) now provides a method for rapidly accessing all references to a specific area through a series of raster images. The ERLIS provides access to the Assessment File Research Imaging (AFRI) database which comprises geo-science mineral exploration assessment file data, Mineral Deposits Inventory (MDI), together with provincial aeromagnetic data from the Ontario Ministry of Northern Development and Mines(MNDM). Conversion of the raster images of ground geophysical data to vector data files together with the concatenation of grids from adjacent claims provides a method for constructing high resolution magnetic regional images. The value of this resource is demonstrated through the construction of a single composite magnetic image derived from eight assessment file grids for an area south of Kirkland Lake, Ontario, within Pacaud and Catharine Townships. The composite grid of magnetic data provides a map with resolution that is not achieved by currently available Ontario Geological Survey airborne data sets. Details contained within the new high resolution image, permit the differentiation of lithologies and their boundaries, fault orientations and the location of alteration zones with magnetic response.

Jan 1, 1997

By David Thomas, Charles Harper, Brian Watters

The Star-Waddy Lakes area lies withjn the northeasterly-trending early- to mjd-Proterozoic volcanoseilimentary-pl utoruc belt referred to as the La Range Domllin. In the area investigated the domajn is composed of the Central Metavolcaruc Belt which is bordered by metasedimentary belts of the Crew Lake and MacLean Lake Belts to the northwest and southeast respectively. The boundaries between the Central Metavolcanic Belt and the flanking belts are generally marked by prominent zones of shearing. The volcanosed imentary succession is intruded by a variety of ultramafic to felsic plutons which, on the basis of lithology, field relations and geochronology, can be broadly subdivided into three groups or episodes. These are: a) an 'early' (ea. 1866 Ma), possibly subvolcanic, episode marked by composite intrusions ranging from gabbro-diorite to granite, b) an 'intermediate' (ea. 1854 Ma) plutonic event distinguished by more homogeneous felsic intru ions ; and c) a 'later' (ea. 1835 Ma) event characterized by leucocratic quartz-rich grani te intrusions. The La Range Domain has undergone polyphase deformation with a strongly developed northeast-trending structural grain. Large scale folding is manjfested by large regional sy nforms, arcuate and triangular patterns associated with many of the plutons and by tight to isoclinal folds within the adjacent metasedimentary belts. Inhomogeneous strain characterizes much of the Star-Waddy Lakes area. With strain gradients being typically very steep, zones of high strain consisting of zones of extreme extensional fabrics, discrete shearing, as well as broader zones of cataclasis and structural slicing, are often juxtaposed with areas of relatively minimal deformation . Dilation structures tend to favour these zones of highly contrasting strain. Late, brittle fractures, faults and shear zones are widespread and appear to be particularly important as loci for gold mineralization. Metan1orphic mineral assemblages indicate that upper greenschist to middle amphibolite facies conditions were attained. Geological and geochenucal evidence indicates that the Central Metavolcanic Belt evolved in an island arc environment. Metavolcanic rocks from both the Waddy and Star Lakes areas display similar characteristics on variation diagrams (e.g. AFM and the Jensen cation plot) in that the dominant trend is calc-alkaline with some basic to intermediate types having a mildly tholeiitic character. A few samples from the southern end of Lower Waddy lake display komatiitic to basaltic-komatiitic afl'injties. The relatively immobile minor and trace elements (e.g. Ti , Zr, Nb, Y, Cr) provide reliable characterization of the metavolcanics, particularly of the basalts, which have highly distinctive trace element properties. Geochemical patterns for the basalts are similar to those for modem volcanic arc basalts. Low initial 87Sr/86Sr ratios (0.7017 - 0.7019) are consistent with a subduction-related origin for the volcanics. The major plutons have chemical properties typical of volcanic arc granites and are largely calc-alkaline in character, showing little chemical variation from the volcanics.

Jan 1, 1986

By Dean L. Millar

Measures taken by mining companies around the world to reduce their carbon footprints are becoming increasingly important in the sector securing its social licence to operate. The options for measures reduce to three categories of activity: i) demand reduction by avoiding unnecessary waste of supplied energy, ii) improving the utilization of energy that does have to be consumed and iii) adopting low carbon energy production options?including renewable energy. As well as the environmental imperative, as the prices of electricity, gas and liquid fuels increase, so the economic case for activities i) to iii) gains higher priority, especially in such an energy intensive industry. The specific energy consumption for certain upstream minerals industry operations in Canada is reported to be as follows: underground mining: 99.5 kWh/tonne mined; surface mining: 11.7 kWh/tonne mined; base metal processing: 81.4 kWh/tonne milled; gold processing: 99.6 kWh/tonne milled. Around 508 kWh/tonne (slag) of heat is reported to be available in cooling slag from 1500°C to 25°C; an amount that is simply indicative of the energy intensity of downstream smelting and refining operations. Low carbon, energy saving technology options that are available to mining industry companies lead to projects with return rates that must compete alongside other capital intensive projects considered by mining company boards. Energy projects frequently involve longer payback periods and lower rates of return than those of competing bids for capital, such as those for development of new mineral properties. For energy services companies (ESCOs) that specialize in the financing, construction, and the efficient operation and maintenance of energy projects, the same returns and payback periods may be considered acceptable or even attractive. For the ESCO, the key commercial risk mitigating factor is a securing a long term contract for the supply of energy.

May 1, 2011