Search Documents

By A. K. Croteau

"At Craigmont Mines Limited, Merritt, B.C., the mining practice of trackless sub-level caving was started in the latter part of 1966. This type of mining was new to the mine personnel and the mining industry of Canada as a whole. Sub-level caving has presented many old and a number of new problems in maintaining the equipment used in this method. This paper will deal with some of these problems as they affect this particular mining operation. It will be impossible to review all phases of the equipment, but an attempt will be made to cover the most pertinent aspects in maintaining the drilling, mucking and hauling, and auxiliary equipment."

Jan 1, 1970

By Gordon MacVean

The object of this paper is to present for your consideration some of the present-day trends of safety practice in the coal mines in the United States and Canada. Coal mining at its best is a hazardous occupation. Men must be experienced miners in order to appreciate the existing hazards and must remain ever conscious of them if they are to work safely. The question is often asked whether our efforts for increased safety are showing results. So often it appears that strides are made for a period of a few years in the reduction of fatalities and lost-time accidents only to have all ground lost by an unfortunate year, after which progress is commenced again only to have a repetition of the same thing. Table No. 1 is an answer to this question. It shows the fatality rates over the last two decades in the coal mines of the United States and Canada. These are given in divisions of five years. The general trend is noticeably downward, exceptions being due to explosions or disasters which claimed an unusually heavy toll of life. These last are certainly not as common today as they have been in the past. It is only reasonable to suppose that this trend towards a lower fatality rate is the result of well directed safety effort. Reliable statistical organizations have offered figures to the effect that only 15 per cent of all accidents can be eliminated by the use of mechanical safeguards. The state of mind of the man involved, or his attitude towards safety, commonly called 'safety-consciousness,' is the controlling factor in the prevention of 85 per cent of our accidents.

Jan 1, 1931

"The Companion Policy is guidance and not law. It sets out the views of the Canadian Securities Administrators (CSA) at to the manner in which the CSA interprets and applies certain provisions of NI 43-101 and Form 43101F1. The Companion Policy references the CIM Best Practice Guidelines for Mineral Exploration, and the Mineral Resources and Mineral Reserves, and that they should be followed by Qualified Persons.COMPANION POLICY 43-101CP TO NATIONAL INSTRUMENT 43-101 STANDARDS OF DISCLOSURE FOR MINERAL PROJECTS This companion policy sets out the views of the Canadian Securities Administrators (the “CSA”) as to the manner in which the CSA interprets and applies certain provisions of National Instrument 43-101 and Form 43-101F1 (the “Instrument”), and how the securities regulatory authorities or regulators (the “Securities Regulatory Authorities”) may exercise their discretion in respect of certain applications for exemption from provisions of the Instrument. PART 1 APPLICATION AND TERMINOLOGY 1.1 Supplements Other Requirements – The Instrument supplements other continuous disclosure requirements of securities legislation that apply to reporting issuers in all business sectors. 1.2 Evolving Industry Standards and Modifications to the Instrument- Mining industry practice and professional standards are evolving in Canada and internationally. The Securities Regulatory Authorities will monitor developments in these fields and will solicit and consider recommendations from their staff and external advisers as to whether modifications to the Instrument are appropriate. 1.3 Application of the Instrument -The definition of “disclosure” under the Instrument includes oral and written disclosure. The Instrument establishes standards for disclosure of scientific and technical information regarding mineral projects and requires that the disclosure be based on a technical report or other information prepared byor under the supervision of a qualified person. The Instrument does not apply to disclosure concerning petroleum, natural gas, bituminous sands or shales, groundwater, coal bed methane or other substances that do not fall within the meaning of the term “mineral project” in section 1.1 of the Instrument. 1.4 Mineral Resources and Mineral Reserves Definitions - The Instrument incorporates by reference the definitions and categories of mineral resources and mineral reserves as set out in the Canadian Institute of Mining, Metallurgy and Petroleum (the “CIM”) Definition Standards on Mineral Resources and Mineral Reserves (the “CIM Definition Standards”) adopted by the CIM Council on November 14, 2004, as amended. 1.5 Best Practices Guidelines for Mineral Resources and Mineral Reserves - A qualified person classifying a mineral deposit as a mineral resource or mineral reserve should follow the CIM Estimation of Mineral Resources and Mineral Reserves Best Practice Guidelines adopted by CIM on November 23, 2003, as amended. These guidelines are posted on www.cim.org."

Jan 1, 2003

By D. W. Davis, P. Landais, L. J. Robb

Abstract -Nodules of carbonaceous matter have been observed in several Archaean peraluminous granites adjoining the gold- and uranium-bearing Witwatersrand Basin. These nodules, which resemble solid bitumen, usually replace uraninite or uranothorite and are paragenetically late. They show many similarities to kerogen seams and nodules associated with the conglomerate horizons in the Witwatersrand Basin, including composition, maturation, intimate association with uraninite, and a late paragenesis. U-Pb isotope ratios for granite-hosted and Witwatersrand kerogens define a single, albeit somewhat diffuse, Pb-loss discordia suggesting an upper intercept age of circa 2300 Ma. Carbon isotope analysis indicates lighter ?13C values for the granite-hosted nodules than for the sediment-hosted kerogen seams. Raman spectroscopy indicates that granite-hosted kerogen is more highly ordered than Witwatersrand seam kerogen. A model is presented which links the granitoid­ and sediment-hosted organic matter to an event of oil generation in the Witwatersrand Basin circa 2300 Ma ago. Light hydrocarbons migrated through the sediments and into underlying/adjacent granitic rocks, undergoing polymerization and accumulation in response to radiation accompanying the presence of high-uranium phases.

Jan 1, 1994

By F. Hampshire

"IntroductionThis paper is intended to cover questions raised by operating staff at various installations and is not intended to give comprehensive coverage of power plant and power system design. The paper is concerned mainly with the electrics , although a brief section gives the reasons for selection of diesels rather than other prime movers.The material is not new but brings out points which seem to be raised regularly during the design , commissioning and operation o f a new plant. Diesels versus other Prime MoversDiesel-electric plant for the mining industry falls into two major categories -emergency power and prim e power.1) Emergency power (for use only when the regular utility supply has failed) requires reliable starting and operation and reasonable first cost. Fuel economy and maintenance are of little importance as the machine(s) generate few kilowatt hours only. The diesel's competition in this field is the gas turbine, however diesels are more widely used than gas turbines in this application.2) Prime power is a different situation as the bottom line of total cost is highly affected by fuel costs.In general , mines which are within reasonable transmission distance of an existing utility find the lowest net cost result s from hooking up to the utility. If a min e is remote from an electric utility then the possible alternatives are:a) Hydro- electric power if there is a site capable of development at reasonable cost including the cost of transmission facilities. Such sites are not common, but brief and inexpensive considerationof this possibility is warranted .b) Diesel power with consideration of different grades of fuel.c) Thermal (steam) power generation from coal or oil.d) Gas turbines.In addition to the above there is the possibility of wind power (as a supplementary source) and a number of technologies which may become feasible in the future (e.g. small nuclear plants, fuel cells). For obvious reasons, small isolated generating systems required for remote mines, tend to lean to conservative technology.Among the fossil fuel plants, the diesel enjoys advantage on over-all costs as summarized in Table 1."

Jan 1, 1986

By L. Jiang

This report investigated the dynamic recrystallization (DRX) phenomenon in magnesium alloy AZ31 billets to understand the deformation mechanisms and microstructure evolution during extrusion and other metal forming processes, Compression tests of coarse-grained as-cast magnesium alloy billets containing lamellar Mg17Al12 eutectic phase and (Al, Mn) particles suggest that temperatures higher than 300°C, strains greater than 0,25 and strain rates above 0,l/s lead to the formation of fine DRX grains in the deformed samples. Microstructural observations also indicate particle-stimulated DRX nucleation (PSN) during hot deformation of the AZ31 alloy, facilitated by the presence of Mg17Al12 and (Al, Mn) particles, While the Mg17Al12 is dissolved into the matrix at about 350°C, (Al, Mn) particles may remain effective for PSN at temperatures up to at least 400°C, This study suggests that alloy design with a proper distribution of second-phase particles can provide the desired microstructure for improved properties and formability in wrought magnesium alloys.

Jan 1, 2004

By D. R. Derry

"IT WOULD TAKE a braver man than I to try to forecast the future of mining exploration far into Canada's second century. Even to look ahead ten or twenty-five years we must review the figures of the fairly recent past -and I have found this quite a time-consuming but interesting job -in order to find trends and project them into future years. The trends to which I will refer are: firstly, the annual expenditure on exploration and its relation to value of output; secondly, the discovery rate and its relation to production initiations; and thirdly, the methods by which discoveries have been, and will be, made. Exploration Expenditures Figures on the annual expenditure on mining exploration in Canada have been collected and published for some years by the Do-minion Bureau of Statistics. These have some unavoidable limitations; e.g., in the varying definition between one company and another of what comprises ""Exploration"" and in the difficulty of getting complete returns. However, although the actual figure for a given year may be subject to question, I believe that the relative figures from one year to another are reasonably reliable. There is also a lapse of time between the collection of data and publication -the last published figures are for the year 1963. In bringing the figures up to date to 1966 I have canvassed eight of the larger mining and exploration companies and obtained their figures for 1963 to 1966 inclusive, and then averaged these for each year and applied the progression to the 1963 figures."

Jan 1, 1968

By Takayuki Takasugi, Naoya Masahashi, Yasuyuki Kaneno, Satoshi Semboshi, Yusuke Kadoi

Cu–Ti alloy wires doped with and without a small amount of Ni were fabricated by over-aging and using intense drawing procedures. For both the Cu–Ti alloys with and without Ni doping, the over- aged microstructure was occupied fully with a coarse lamella of Cu solid solution and β-Cu4Ti plates precipitated discontinuously by grain boundary reactions. The full-lamellar microstructure was developed much more rapidly by aging in multi steps at 873 K to 723 K rather than by isothermal aging at 723 K. Ni doping in Cu-Ti alloy was also effective to accelerate the formation of the lamellar microstructure. When drawing the over-aged alloy with inferior hardness but superior electrical conductivity, the strength increased steadily and eventually exceeded that for the wires drawn from the peak-aged alloy. In addition, the electrical conductivity of the wires drawn from the over-aged alloy was always much greater than that from the peak-aged alloy. Eventually, the procedure of over-aging, followed by intense drawing, could enhance both the strength and electrical conductivity of Cu-Ti alloys, whichever they contain a small amount of Ni or not, rather than the conventional peak-aging and drawing process. INTRODUCTION Cu-based alloy wires, which have an excellent combination of strength and electrical conductivity, have attracted extensive attention for highly mechanically stressed electrical devices, such as conductive lead wires and wires in suspension springs. Cu-Be alloys are widely used for such electrical components owing to their combination of strength and electrical conductivity among industrial Cu-based alloys. However, since beryllium is potentially toxic and also a rare element, substitute materials for Cu-Be alloys have been searched for several decades. Age-hardenable Cu–Ti based alloys have been proposed as candidates because their mechanical and physical properties are comparable to those of Cu-Be alloys; however, their electrical conductivity is inferior (Datta & Soffa, 1976; Soffa & Laughlin, 2004). In order to satisfy the requirement of downsizing and streamlining electrical devices, further improvement of the mechanical and electrical properties of Cu–Ti alloy wires is needed. Age-hardenable Cu–Ti alloys, which contain approximately 3 to 6 at.% Ti, are typically prepared using a solid solution treatment above 1100 K and then aging at a moderate temperature of 700 K to 800 K. It has been revealed that the microstructural events during aging progress as follows (Soffa & Laughlin, 2004): (1) compositional modulation of the parent supersaturated Cu solid solution in an initial aging stage (Laughlin & Cahn, 1975), (2) continuous nucleation and growth of fine needle-shaped precipitates of metastable β’-Cu4Ti with a tetragonal structure in a peak-aged stage, and (3) discontinuous precipitation of cellular components laminating the plates of a terminal Cu solid solution and stable β-Cu4Ti with an orthorhombic structure at the grain boundaries in an over-aging stage. It has been also accepted that the highest number density of dispersed fine β’-Cu4Ti needles should contribute to maximal strengthening. On the other hand, decease of the strength in the over-aging stage occurs due to the replacement of the fine β’- Cu4Ti needles with cellular components containing coarse β-Cu4Ti plates, while the electrical conductivity is significantly enhanced due to the depletion of solute Ti in the Cu matrix. This suggests that a combination of strength and electrical conductivity for age-hardenable Cu-Ti alloys is in a trade-off relationship, and that innovative improvement of both properties might be limited to tuning the aging conditions.

Jan 1, 2019

By Champoux. G., E. Ghali, W. Zhang, G. Monteith, A. -M. Lafront, G. Houlachi

The efficiency of the electrowinning process of zinc depends on the performance of oxygen evolution reaction, anode quality and corrosion resistance of lead anodes. Original surfaces of rolled commercial lead-silver anodes were examined using conventional polarisation methods in acid zinc sulfate electrolyte with manganese sulphate at 38 °C. The self-discharge method (potential decay) following 5 h polarisation at 50 mA cm-2 was considered to evaluate electrochemical activity, oxygen overpotential and anode stability. The influence of silver content is compared to that of the microstructure, the fabrication process and the composition of the corrosion products. Polished anode samples have also been examined for microstructural and corrosion performance studies. The experiments show that the duration of the plateau at 1600 mV versus SHE, the potential level (active corrosion state/stationary state) and the rate AEco/At during the decay could be a good indicator to compare the corrosion rates of the anodes in industrial zinc electrolytes.

Jan 1, 2008

By H. W. Parsons

Several low-temperature, dry chlorination processes for the treatment of sulphide minerals are reviewed, in a chronological order. These processes include the following: the Swinburne-Ashcroft, Baker-Burwell, Maim, Comstock-Wescott (Aldermac) and the Mitterburg Mining Process. Dry chlorination investigations at the Canadian Mines Branch (now CANMET) and the U.S. Bureau of Mines are discussed, as is a proposed process by the South Africa National Institute for Metallurgy. The techniques used in the process are discussed, as are the shortcomings, problems and failures of the methods.

Jan 1, 1978

By Robin N. Adair

Abstract -The Halfmile Lake stratiform volcanogenic massive-sulfide deposit consists of pyrrhotite­ rich breccia-matrix sulfides and pyrite-pyrrhotite-rich layered sulfides that form a laterally continuous sheet stratigraphically underlain by an extensive pyrrhotite-chalcopyrite-quartz stringer zone. Mineralization is hosted by a sequence of felsic pyroclastics and volcanic-derived, fine-grained metasediments. The proportion of volcanic to sedimentary rocks indicates increasing vent proximity from southwest to northeast across the deposit area. Fine- to medium-grained felsic pyroclastics and roughly equal amounts of fine-grained metasediments comprise the stratigraphic footwall to the mineralization. Quartz-feldspar porphyritic bodies cut this sequence and may have provided the heat source for exhalite activity. Felsic tuffs, locally crystal-rich, and lesser amounts of metasedimentary rocks make up the immediate stratigraphie hanging wall. This sequence is stratigraphically overlain and locally interfmgered with matie volcanics that contain substantial proportions of felsic fragments. Deposition of sulfides post-dated the beginning of felsic volcanism, which places the deposit in the middle of the Lower Tetagouche Group. Compositions of the volcanic rocks range from basait to rhyolite and exhibit sub-alkaline affinities. Strongly overprinted whole-rock, trace-element, and REE geochemical signatures resulting from mineralizing hydrothermal activity confirm the genetic relationship be­tween the stringer zone and the mineralized sheet. Large-scale D1 folding has overturned the entire sequence. D1 thrust faults and related sheath-like folds have profoundly affected sulfide distribution. D2 is manifested by a penetrative S2 foliation, and D3 is represented by large-scale open folds.

Jan 1, 1992

By P. C. Lighthall, D. W. Zandee, W. Shukin

"IntroductionThis chapter deals with the on land disposal and storage of fine tailing in slurry form behind dams. Other types of tailing, such as coarse dry cobbs from magnetic separation of iron ores and other dry materials, have special problems and are not addressed in this paper. The disposal of mine waste is not included, except as such materials may be of value in the construction activities related to tailing disposal.In earlier North American mining, mines were smaller and frequently disposed of their tailing by direct discharge into neighbouring streams or bodies of water. Where that was not practical or not permitted, the solids were collected in tailing ponds and only the effluent liquids were released or decanted. The dams used for these early impoundments were fragile structures and failures were common. With the advent of large, low-grade open pit mines, and increasing awareness of environmental and safety considerations, recently established mines have carefully-designed tailing disposal systems, with wellconstructed dams and attention given to protection of the environment. Older mines are being improved or at least being examined critically with a view to upgrading as necessary to meet the new standards.Modern tailing disposal systems are highly variable and unique to each mine. Tailing pond selection and design is dependent on available topography as also is the design of transport and water reclaim systems. Suitable sites that are at higher elevations than the mills or distant from them may require that the tailings be pumped. Dams, either earth or rock structures built of the most convenient and economic material, are usually a suitable mix of local borrow, mine waste and coarse tailings. The most economic structures are those built mostly of coarse tailing."

Jan 1, 1989

By Brian L. Beninger

This paper discusses the application of the computer to coal preparation process predictions. In broad terms, the computer is used to perform two main functions. Firstly, the given float-sink analysis is interpolated and extrapolated to cover the entire actual range of raw coal specific gravity. Assumptions based on historical data must be made at times. Secondly, the partition curve, which, from historical data, defines the efficiency of a specific coal washing process, is applied to the washability data in order to determine the expected clean coal yield and quality. The vast amount of numerical work which is required to make a prediction of this type exhibits the need for computer methods in this area.

Jan 1, 1979

By C. E. Smith, R. J. Inglis, M. I. Brittan, J. H. Schoeman

"AbstractA number of plant-scale cyanidation tests were carried out in an attempt to uncover the causes of fluctuations in gold recovery efficiency. Computer analysis of the results verified that the treatment of reclaimed waste rock material along with normal run-of-mine ore was having an adverse effect on metallurgical efficiency. Mineralogical examinations showed that the free gold particles in the dump material were heavily tarnished or coated (predominantly by hydrated iron oxide), accounting for the lower recoveries. The indications were that the effect could be counteracted somewhat by using higher than normal cyanide and lime reagent concentrations and adequate leaching times. Analysis of the results showed further that leach pulp density was an important operating parameter affecting extraction efficiency. A variable activation energy leaching model provided an extremely good characterization of individual batch leach runs.IntroductionFLUCTUATING METALLURGICAL EFFICIENCY at the gold concentrator of the S.A. Land and Exploration Company Limited (""Sallies"") prompted some plant-scale cyanide leach studies in an endeavour to uncover the causes of the variations in gold recovery."

Jan 1, 1977

By E. Heikkinen, J. Suikkanen, T. Siren, J. Valli, M. Hakala

Diametrically faced borehole breakout observations are a fairly good indication of magnitude of the secondary stresses acting perpendicular to the borehole. In cases of low in situ stresses, where borehole breakouts are not observed naturally, it is possible to increase the prevailing stress state around the borehole by increasing the rock temperature. When the temperature is increased sufficiently, thermally induced borehole breakouts will occur. By implementing the temperature increase in boreholes located at excavated tunnels, it is also possible to study the effect of the near-field stresses caused by the excavation. The near-field stress state changes as a function of borehole depth, thus increasing the information available from experiment. To study the feasibility of this proposed low cost method, a Borehole Thermal Spalling (BTS) experiment was executed in ONKALO Underground Rock Characterization Facility, in Western Finland in 2014. The first borehole pilot test with the method was conducted in ONKALO at the POSE niche in already at May 2010, with the second pilot test following in August 2010 at Äspö HRL. The major objective of the experiments was to define the trend of the maximum in situ stress component, while also providing knowledge of the in situ spalling strength of the ONKALO rock mass. The stress state in ONKALO is nearly isotropic in horizontal layer, causing problems for the use of more traditional stress measurement methods. With boreholes heated over long interval, the weakest rock parts are observed to fail, thus providing statistical confidence. For these reasons, continuous test sections have an advantage in ONKALO, compared to spatially limited stress measurement methods such as overcoring and hydraulic fracturing. The BTS experiment is conducted in 9 meter deep vertical boreholes located at the POSE niche, situated -345 m depth below the ground surface. The boreholes used within the BTS experiment are located in migmatitic granite, in an experiment area where the surrounding stress state and the rock strength are fairly well known. The prior knowledge of the stresses is favourable for the experiment, as it requires careful planning and iterations to determine the appropriate heating power domain. Too low heating power will not be sufficient to cause borehole breakout, while too high heating power causes breakout in all directions thus making determination of stress direction hard or impossible. The initial state of the borehole and induced borehole breakouts will be monitored using acoustic televiewer logging (ABI) and optical borehole logging (OBI) imaging techniques. Fracture mechanics modelling is used in planning of the experiment, also in back-analysis to link the observed breakout angle to stress state. Both the pilot test in 2010 and BTS test in 2014 resulted in similar borehole breakout direction. The results are in line with so called EDZ & VT1 stress interpretation, revealed the maximum horizontal component bearing the magnitude of 21.5 MPa, with the trend of 166°.

Jan 1, 2015

By M. Lindgren

"Hydrometallurgical processing involves process stages, like leaching, that create harsh environment for stainless steels. High acidity, the presence of chlorides and oxidizing ions combined with relatively high temperature create risk for both uniform and localized corrosion. Advanced electrochemical techniques were employed to study uniform and pitting corrosion of two stainless steel grades 316L and 2205. Results obtained with the linear polarization resistance technique combined with the harmonics distortion analysis, electrochemical noise and coupled multielectrode array systems are compared to the results of conventional electrochemical techniques and immersion tests.INTRODUCTIONHydrometallurgical processing has become favoured in metals production in recent years due to energy costs, leaner ore bodies and environmental factors. Because the hydrometallurgical processing route is flexible, various types of secondary raw materials, like flotation tailings, dusts, sludges and slimes can also be treated in addition to conventional mineral concentrates (Sarveswara Rao & Acharya, 2008).Hydrometallurgical processing relies on aqueous chemistry, usually acids, at temperatures around 100°C for the recovery of metals from ores, concentrates, recycled or residual materials. The processing route can typically be divided into three stages: leaching, solution concentration/purification and metal recovery. The processing environment is aggressive, especially in leaching. High acidity, relatively high temperature together with impurities, like chloride ions, place high demands on the corrosion resistance of construction materials. The dominant corrosion mechanism may be uniform corrosion or localized corrosion depending on the process conditions (Ekman & Torsner, 2010). This complicates the prediction of corrosion rates and, consequently, cost effective material selection.Traditional means to evaluate uniform corrosion resistance of stainless steels are immersion tests and the results are published in the form of iso-corrosion diagrams (Outokumpu Stainless, 2010). For the localized corrosion, namely pitting and crevice corrosion, immersion tests can be used but the duration of the test is rather long because an incubation period takes place prior to the occurrence of the actual localized corrosion damage. Electrochemical techniques, traditionally in the form of cyclic polarization scans, have been employed to assess the susceptibility of a material to pitting corrosion (Papavinasam, 2008). They cannot, however, give any indication of the pitting corrosion rate and lack potential for on-line measurements."

Jan 1, 2012

By J. Fellowes, V. Landais, J. Robson, J. Carr

"Aerospace Al-Zn-Mg-Cu (7xxx) alloys are known to be susceptible to environmentally assisted cracking (EAC). This phenomenon has been studied intensively for many decades, leading to empirically adopted methods to mitigate this problem through overaging and composition design. In parallel, many theories have been developed to explain EAC in 7xxx, but none is yet universally accepted. Today, a number of emerging techniques offer potential to shed new light on EAC in 7xxx. The purpose of the present paper is to demonstrate how X-ray tomography (XCT) combined with electron microscopy can be used to identify the true crack path in 3-dimensions, and hence identify material for site specific electron microscopy analysis. Composition mapping over large areas to high accuracy has been performed using a modern electron microprobe analysis system. This has been combined with transmission electron microscopy to investigate local composition in matrix and precipitates at high resolution. This combination of techniques across length scales offers the potential to provide new insights into the links between local composition, microstructure, and EAC resistance.INTRODUCTION Environmentally-assisted cracking (EAC) is a phenomenon which dramatically decreases the performance of metals and can cause premature failure of large structures. Observed in situations where components were not subjected to critical loads and no widespread corrosion was involved, this type of brittle failure is extremely difficult to predict. The EAC designation covers a number of phenomena, e.g. stress corrosion cracking (SCC), hydrogen embrittlement (HE), corrosion fatigue (CF), etc. Initially identified in steels, EAC can also affect other metals such as high-performance aerospace aluminium alloys, and this phenomenon has been a concern for industries for decades. Extensive research has been conducted on the effects of various environments (moist air, saline water, dry hydrogen gas, etc.) on microstructures and crack propagation, however no consensus has been reached and the exact nature of the mechanisms that control EAC is still being debated (Birnbaum & Sofronis, 1994; Gangloff, 2007; Holroyd & Scamans, 2013; Lynch, 2012; Oriani, 1972; Scamans, Alani & Swann, 1976, Young & Scully, 2002)."

Jan 1, 2018

By D. H. Schwarz

The performance of proton exchange membrane (PEM) fuel cells depends on catalyst layer composition and structure. Experimental observations reveal that state-of-the-art catalyst layers consist of microporous agglomerates of carbon-supported catalyst sites bound together by polymer electrolyte. In between the agglomerates are macropores which provide pathways for the transport of gaseous reactants. In this work, three-dimensional, multicomponent and multiphase transport computations are performed using a computational fluid dynamics (CFD) code (FLUENTTM) with a new PEM fuel cell module, which has been further improved by taking into account the detailed composition and structure of the catalyst layers using a multiple thin-film agglomerate model. In this model, it is assumed that thin films of polymer electrolyte and liquid water surround the catalyst sites. The results of CFD computations show that transport limitations associated with the thin film of polymer electrolyte and the presence of liquid water in the catalyst and gas diffusion layers have substantial negative effects on PEM fuel cell performance. Also, the results of computations with variable distributions for a given precious metal loading show that, in general, uniform catalyst loading provides the best fuel cell performance.

Jan 1, 2005

By W. A. Lang

"I.-IntroductionAn attempt bas been made in this paper to provide a basis for appraisal of the future of the coal briquetting industry in Alberta by outlining the processes used for briquetting various ranks of coal, by specifying the requirements of a briquetted fuel, by indicating .the status of the industry in the United States, by giving developments in Western Canada, by assessing costs of processing, and by discussing briquetting researches in progress. Much of .the detail bas been omitted since this might mask, rather than reveal, the more important phases of the problem. Reference will be made when possible to published articles where many of the details can be obtained.It should be stated at the outset that, in the writer’s opinion, there are three possible developments in Alberta as regards briquetting: (a) an expansion of the briquetting of the fines of • non-coking and coking coals of semi-anthracite, and of low and medium volatile bituminous rank; (b) the processing of the fines of high-volatile C bituminous coals; and (c) the upgrading of the lower rank high-moisture sub-bituminous coals. Details of the chemical and physical properties of these coals can be obtained in publications of the Research Council of Alberta (1, 2), and of the Fuel Research Station, Bureau of Mines, Ottawa (3).Semi-anthracite and low and medium volatile bituminons coals occur in the mountain areas of Alberta, where, during the upthrust of the Rocky mountains, the coal beds served as the sliding surface. This resulted in the coals being; crushed and consequently they contain a h1gh percentage of fines. In some cases they are high in mineral matter and require to be cleaned before being processed. However, the cleaning of fine coal is both difficult and costly. Both the amount of fines present in the mine-run coal and the amount of mineral matter associated with the coal have increased through the introduction of mechanized mining and through the recovery of coal by stripping operations."

Jan 1, 1950

By R. J. Craig

Introduction All mining operations produce rock dust. Inhalation of rock dust, particularly if it has a high silica content, causes silicosis. Silicosis is, therefore, recognized as a hazard of the mining industry and has been made compensable throughout most of Canada. Most of the dust in any mining operation is caused by rock drilling and blasting operations and the movement and transportation of broken rock. Dust from blasting cannot be eliminated, but it can be controlled by means of increased ventilation, the use of water sprays, and the control of blasting hours. Dust from ore movement can be reduced by keeping the broken rock in a moist condition at all times. The dust from the rock drilling operation has been found to be the most difficult to control. Concentrations of dust caused by rock drills in stopes can usually be reduced to the safe minimum of 300 particles per cubic centimeter (p.p.c.c.) by diluting the air with increased ventilation. In development headings, where the machines are more confined, this is not always practicable. Therefore, the dust must be eliminated at its source. This paper deals with the reduction of dust from Leyner machines by adopting improved designs.

Jan 1, 1947