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By D. Song

In this paper, the differential equations governing the mass transport and the electrochemical reaction in a cathode catalyst layer of polymer electrolyte membrane fuel cells are solved based on the polynomial series expansion method. Explicit expressions for the polarization curve as well as for the distributions of oxygen, current density and overpotential are obtained when a quadratic, cubic or quartic polynomial is employed to approximate the oxygen concentration distribution. These kinds of explicit solutions are desirable for MEA design and diagnosis purposes. The comparison between the conventional numerical approach and the explicit solution approach proposed here shows that satisfactory accuracy can be reached by the first four terms of the polynomial series. The effect of the catalyst layer thickness on the accuracy of the obtained explicit polynomial solutions is also discussed.

Jan 1, 2005

By A. F. Banfield

"IntroductionELEMENTAL sulphur occurs in three types of deposits: in salt domes in the Gulf Coast region of the United States and Mexico, from which over 90 per cent of world native-sulphur production is obtained; in sedimentary deposits such as those in Sicily, which are thought by some authorities to contain the largest world reserves of elemental sulphur; and as surface deposits, associated now or in the past with some phase of vulcanism, the type which bas the greatest world-wide distribution.Deposits of the volcanic type are the subject of this paper.From antiquity until the successful development of the sulphur-bearing salt domes at the beginning of this century, important sulphur production for local needs was obtained from volcanic deposits in many parts of the world. Due to technical and economic factors, however, producers could not compete in price with sulphur from salt domes. •The result has been that, except in Japan and Chile, little sulphur was produced from volcanic deposits from about 1910 until the start of the Korean war in 1950. Shortly after the outbreak of the Korean war, an acute world sulphur shortage developed and prices skyrocketed in many countries up to several hundred dollars a ton. Interest in volcanic deposits was renewed and exploitation of many was undertaken. Few of these operations have been successful, mostly due to inability of management to solve technical problems.While important volcanic deposits of elemental sulphur have not been reported ( 1) in Canada, and it is doubtful that any will be found, data presented in this paper may be of interest to students of ore genesis.This paper is based on field examination of numerous deposits of the volcanic type in North and South America."

Jan 1, 1954

By W G. Forbes

SOME 20 years ago, upon finishing second year at the University of Manitoba, I was faced with the choice of whether I wanted to be a geologist or a chemist. Accordingly, I sought out Professor Brownell, Head of the Department of Geology, to ask him what a geologist did. His reply contained the statement that following graduation one went out into the field in northern Canada for 5 to 15 years to reduce to practice what had been learned at university. To a young man, very socially conscious, even one year, let alone 5 to 10, in a small mining community sounded like being banished to a monastery in the Himalayas and thus I turned to chemistry. Moving to the present, last month I asked a geologist, and then a mining engineer, what does the fresh graduate in their field do these days? The reply was: usually serve an apprenticeship for an indeterminate period either underground or in the field learning the job.

Jan 1, 1965

By A. C. Stevenson

"There are many critical application issues that affect all AC drives, but there are several that are absolutely mandatory for pulse width modulated (PWM) AC drives. If these rules are not followed, the drive system will have insulation, bearing EMI or noise problems. Pulse Width Output VoltageFigure 1 shows the output current of a typical pulse width modulated (PWM) drive. This is, of course, not a clean sine wave thus will have a lot of very significant harmonics. In fact, the harmonic spectrum is directly related to multiples of the carrier switching frequency plus side bands related to the basic output frequency. A typical spectrum for a PWM source bridge switching at 5 kHz is shown in Figure 2. Notice that the spectrum has multiples of the 5 kHz switching frequency and the number of side bands gets larger as the harmonic number increases.IGBT Switching TransientsWhenever we have PWM inverter switching, voltage transients are formed that propagate (usually at about half the speed of light) down the power cables to the motor just like in a radio frequency transmission line. If we do not terminate these transmission lines (motor cables) properly, the voltage pulses will be reflected when they reach the motor end and will be transiently increased up to twice their original amplitude.This transient voltage rise, shown in Figure 3, is important for three reasons:1. Insulation Voltage Stress — Higher voltage stress in the motor connecting cables and motor insulation will lead to a shorter insulation lifetime. If any of the voltage transient peaks exceed the insulation corona discharge level (partial discharge level), the insulation will gradually degrade with each voltage pulse. When it has been sufficiently degraded, it will then fail.Most new “inverter rated” motors have triple layer insulation which has a 1600 to 2000 volt partial discharge level. This will make them suitable to withstand the double voltage peak transient from a 600 volt inverter. It is wise to make sure of this fact, since a “standard” induction motor will only withstand about 1200 volts. Use of a standard motor in this application would shorten its life drastically. This can sometimes be as little as a matter of hours."

Jan 1, 2000

By Norman A. Jull

"IntroductionThe scope of this paper is intended to deal mainly with cyclones in grinding circuits. However, the section on Cyclone Equipment, contains more general descriptions, to cover most of the cyclones used in mineral separation plants.Cyclones as heavy media separation vessels are discussed by Mark Freberg (this volume). Their use in tailings deslirning is discussed by P.C. Lighthall, eta/. (this volume).Cyclone EquipmentCyclone TerminologyApexObviously, the apex of a cone is the smallest end. However, with cyclones the term is usually used for the fitting which is attached there to control discharge of the underflow stream.Note that the cyclone need not be so mounted that the apex is the lowest point, although that is the most common method. Keeping the apex below the rest of the cyclone helps avoid plugging when the underflow contains very large particles and the tonnage of underflow solids can fluctuate.Various devices for adjusting apex diameter or otherwise controlling the underflow are discussed later under ""Cyclone Construction"".BypassingThe transport of a portion of feed slurry directly to underflow so that classification is bypassed by that portion of feed.This action is fundamental in any hydraulic classification, whether gravity or centrifugal, because the large particles going to underflow have some void volume between them, which remains filled with feed slurry.D50By definition, D50 is that particle size which has an equal probability of going to overflow or to underflow.It is calculated by drawing a curve of recovery vs particle size and noting the size at which 500Jo recovery occurs.This may be done equally with corrected or with gross recovery (see below) and the resulting value should therefore be identified as d50c (corrected d50) or as d500 (gross d50).Note also that it is common in industry practice to plot size analysis data on the retained size rather than on the average of passing and retained (the middle of the size band). To portray sizing alone it makes no difference, but to read a D50 value off a curve of corrected or gross recoveries, it is essential to plot those values on the average size of each band."

Jan 1, 1989

By W. L. Goodwin

Twenty-five years ago mining engineering in Canada was not a profession. To-day the members of the mining fraternity can fairly claim for 10themselves the professional status. If their pretension is not fully warranted by fact it is not for lack of any technical attainment or service to the public but by reason merely of their neglect to cultivate the cohesion and consciousness that are the outward and visible signs of a professional body. This paper is an attempt, first to sketch briefly the course of the events during the past thirty-five years that have resulted in organizing the mining industry of this country in its present form; then to notice the principal features of the professional organization of this day; and finally to point out that an important part of the work of the mining engineer remains in the state of chaos that characterized the whole of it three or four decades ago, and to suggest a remedy. Thirty years ago there came a great wave of interest in mining in Canada, based principally upon the discovery of gold-quartz and gold-copper throughout wide areas in Nova Scotia, Ontario and British Columbia.

Jan 1, 1926

By W. J. Pearson

"""POTASH"" is a term applied to the compounds of the element potassium (K) and when used in agriculture and industry is ex-pressed in terms of potassium oxide (K2O), regardless of the actual com-position of the compound. When a chemical analysis is made of a fertilizer, the amount of K is deter-mined and then calculated to the equivalent amount of K2O. However, the compound K2O does not exist in nature. Most of the world's potash supply is derived from mineral deposits similar to those in Saskatchewan and New Mexico. However, there is some production from concentrated surface brines such as occur in Searles Lake, California; Salduro Marsh, Utah; the Dead Sea; and from well brines in Micl1igan."

Jan 1, 1960

By Link. Theo A.

Introduction Since the discovery of a major oil pool at Leduc, Alberta, on February 13th, 1947, the long spell of 'oil drought' in Western Canada is now being turned into an oil and gas flood which requires immediate action to obtain the optimum economic benefits. The Woodbend, Section 9, and Okalta extensions of the Leduc field itself have been established; the Redwater pool, lying thirty-seven miles northeast of Edmonton, has been discovered and is being drilled up, and the Imperial Schoepp No. 1 or Golden Spike discovery holds promise of something phenomenal in view of the 500 feet of oil-saturated coral-reef porosity whose areal extent is not known. Imperial Stanolind Barrhead No. 1, northwest of Edmonton, revealed the presence of oil in the Madison, and just recently Gulf N.J. Ellis No. 1, some sixty miles southeast of Leduc, found commercial production in the Leduc D-2 discovery zone. In addition to these Paloeozoic discoveries, gas and oil reserves have also been established in the Upper and Lower Cretaceous, which must be penetrated by all tests on the way through the geological column to the Devonian. If ever there appeared to be an index of 'things to come' in the oil industry, this is it. However, without these recent discoveries the picture in Western Canada does and always did, look very promising indeed. A brief survey of the geological setting in Western Canada is the object of this contribution.

Jan 1, 1949

By P. Czaja

The paper presents a patented and copyright protected concept of constructing a shaft lining that goes through rock masses having strong rheological properties and being susceptible to leaching. In the case of salt layers, especially at significant depths (over 900 m) the relative convergence of the heading contour may amount to 40 ?/year. That results in the fact that any other method of securing the shaft lining, e.g. by making it flexible, will not be sufficient to ensure the stability of the shaft reinforcement geometry. In the new shaft lining concept the excessive rock creep into the outbreak inside the shaft diameter will be removed by local and controlled leaching of the shaft cheeks by means of fresh water directed through a porous medium at the contact layer behind the watertight tubing lining. The paper presents the structure of such a lining and an outline of the construction technology. In order to implement such a lining, a typical tubing will be applied. Separate design and manufacturing will be required for the technological rings used to control the leaching process behind the lining.

Aug 1, 2013

By A. McLean, Q. R. Yang, Y. D. Yang, G. F. Zhang, P. Wu

A considerable amount of waste slag from the pyrite roasting process is discharged every year. Recovery of iron from the waste slag is of great interest for comprehensive use of mineral resource, reduction of environment impact and improvement of economical benefit to related companies. The objectives of the present work are focused on: (1) Compare various procedures for recovery of iron from the waste slag and select a best procedure for industrial trial which is roasting of the waste slag under reducing condition followed by magnetic separation; (2) Investigate the optimum conditions for maximum recovery of iron from the waste slag. The experimental result shows that under the treatment condition found in this work about 36 to 40% of the iron oxide was recovered from the waste slag, where the iron content in the concentrate is 57%. The total recovery ratio of iron, up to 70%, from the waste slag was achieved. After the treatment, sulphur content in the waste slag was reduced significantly and gangue materials, such as SiO2, Al2O3 and TiO2, were reduced effectively.

Jan 1, 2011

By F. H. Edmunds

I N presenting this paper, the writer wishes to point out some of the difficulties and problems of geological work in that part of Saskatchewan in which outcrops are few. These problems are well known to all geologists who have made investigations in this region, but may not be so well known to those outside. A table of the strata as known in certain areas of Saskatchewan and the adjacent provinces is given, with a brief discussion of some of the formations and beds about which there is little knowledge due to their being deeply buried and not exposed in the region. Comment with regard to possible oil and gas structures is made and some features of the structures in the Battleford and Simpson districts are described. The writer wishes to make acknowledgment to members of the Geological Survey of Canada to whose work in Saskatchewan and the adjacent provinces reference is made, and to others who have made, or are making, valuable contributions to the stratigraphy of Saskatchewan. Mr. G. C. Webb has kindly furnished information regarding and materials taken from a well bored recently in the Paynton district. Special thanks are due to the Simpson Oil and Gas Company for permission to use much valuable information with regard to their wells and for the generous way in which the officials and staff co-operated with the writer. The opportunities the writer has had to visit many parts of the Province have been in connection with investigations for the Provincial Department of Natural Resources and through facilities provided by the Department of Soils of the University of Saskatchewan. To these Departments the writer accords his thanks. For the purposes of this discussion, Central Saskatchewan may be considered as that portion of the Province extending from Township 16, with Regina, Moose Jaw, and Swift Current situated on or near the southern boundary, to Township 48, with Prince Albert and Lloydminster on the northern boundary. This region includes territory underlain by Cretaceous sediments and excludes the southern portion of the Province, where Tertiary beds underlie the surface and are exposed to an extent sufficient to permit a measure of systematic mapping.

Jan 1, 1937

By R. W. Coburn

The results of field experiments on wells which required stimulation indicated that engineered well-completions will cause an increase in ultimate recovery at reduced costs. Techniques and tools have been developed which can be used to establish well conditions most conducive to successful stimulation. Cementing, perforating and treating are bound together so completely that the success of one phase is completely dependent on the .effectiveness of the preceding phase. A method of determining the efficiency or effectiveness of any given well-stimulation treatment has been derived. Pressure behaviour during a treatment can be analyzed to yield the total percentage of the formation which has been treated.

Jan 1, 1960

By Mahmoud Ahmed

Three-dimensional models are in increasing demand for design, maintenance, operations and construction project management. Point-clouds are the main output of automatic data collection using laser-scanners and photogrammetric technologies. Pipe-works may comprise 50% of the value of important construction projects such as industrial and research facilities. We have developed a practical and cost-effective approach, based on the Hough-transform and judicious use of domain constraints, to find, recognize and reconstruct/model 3D pipes within point-clouds fully automatically. The developed approach allows pipe growing within a 3D point-cloud. It samples the point-cloud to sequential orthogonal slices, detects pipe?s cross-sections within sampled slices and grows the pipe along the cross sections centerlines. It is validated using laser-scanner data from construction of the Engineering-VI building on the University of Waterloo (UW) campus. The system works on a typical laptop. Recognition and localization results are within a few millimeters. The presented approach opens the gate to broad applications of pipe-network modeling.

Aug 1, 2013

By Syamujulu. M

Subsequent to the unbundling of the Zambia Consolidated Copper Mines (ZCCM) and the privatization of its constituent parts, the Konkola Copper Mines (KCM) represents a third of the original conglomerate. Now run by private hands as a sub group of Vedanta Resources Plc of India, KCM is strategizing on how best to deal with the operational issues of the organisation to resolve some of the difficult, logistical, environmental, mineralogical and metallurgical problems being encountered to tum them into opportunities as the company turns around. This paper reviews the options being put in place to provide appropriate solutions and strategies including the treatment of the highly siliceous low energy copper belt concentrates in its mining operations in Zambia.

Jan 1, 2007

By C. J. R. Braithwaite, Giancarlo Rizzi

"The Navan zinc-lead ore deposit (70 million tonnes) is hosted principally (97%) by the Meath Formation (Lower Carboniferous, Courceyan, Navan Group), comprising a lower, mainly carbonate mudstone unit, the Stackallan Member, and an upper grainstone-dominated unit. TheStackallan Member, about 60 m thick, comprises about 35 peritidal cycles including an oolitic grain-stone interval. Grainstones forming the upper part of the formation, about 150 m thick, comprise at least six shallowing-upward ramp cycles. Emergence horizons are indicated by subaerial dissolution surfaces, in situ breccias, and a single palaeosol.Most dolomitization at Navan is con?ned to the Meath Formation. The linear dolomite body,trending NE-SW, has a ?attened, laterally limited, tabular geometry in cross-section, suggesting that dolomitizing ?uids initially rose vertically, cross-cutting stratigraphic and sedimentological bound-aries, although ?uid ?ow was subsequently controlled by these features.Three stages of dolomitization are indicated by textural relationships, cathodoluminescence (CL),oxygen isotopes, and ?uid inclusion data. Stage 1 crystals, with generally dully luminescing cores and up to six overlying subsidiary zones, are the main replacive phase. Crystal surfaces are commonly corroded and overlain by bright stage 2 rhombs (which also form new nuclei lining molds and fractures). Three subsets of zones are present in stage 2 crystals: bright, non-luminescent, and dull; these are locally separated by additional corrosion surfaces. Stage 3 comprises relatively large baroque crystals, generally dully luminescent but with up to seven sub-zones. Isotopic and ?uid inclusion data suggest growth of successive stages from waters which became progressively hotter(60°–160°C).The distribution of the ores follows the dolomite trend. Ores were precipitated between Stages1 and 2 of dolomite growth, following Stage 2, and also during the nucleation and growth of Stage3 crystals. Dolomitization and mineralization appear to have been temporally and genetically related. The cyclic sedimentation of the host rocks, which accentuates lithological and petrographical contrasts between depositional units, controlled dolomitization. The relationship between dolomitization and mineralization, which is closely associated with faults, provides powerful exploration criteria. The recognition of these features in limestones elsewhere in the Irish ore ?eld may point toward unrecognized zinc-lead prospects."

Jan 1, 1997

By C. J. R. Braithwaite, Giancarlo Rizzi

"Abstract-The Navan zinc-lead ore deposit (70 million tonnes) is hosted principally (97%) by the Meath Formation (Lower Carboniferous, Courceyan, Navan Group), comprising a lower, mainly carbonate mudstone unit, the Stackallan Member, and an upper grainstone-dominated unit. The Stackallan Member, about 60 m thick, comprises about 35 peritidal cycles including an oolitic grainstone interval. Grainstones forming the upper part of the formation, about 150 m thick, comprise at least six shallowing-upward ramp cycles. Emergence horizons are indicated by subaerial dissolution surfaces, in situ breccias, and a single palaeosol.Most dolomitization at Navan is confined to the Meath Formation. The linear dolomite body, trending NE-SW, has a flattened, laterally limited, tabular geometry in cross-section, suggesting that dolomitizing fluids initially rose vertically, cross-cutting stratigraphic and sedimentological boundaries, although fluid flow was subsequently controlled by these features. Three stages of dolomitization are indicated by textural relationships, cathodoluminescence (CL), oxygen isotopes, and fluid inclusion data. Stage 1 crystals, with generally dully luminescing cores and up to six overlying subsidiary zones, are the main replacive phase. Crystal surfaces are commonly corroded and overlain by bright stage 2 rhombs (which also form new nuclei lining molds and fractures). Three subsets of zones are present in stage 2 crystals: bright, non-luminescent, and dull; these are locally separated by additional corrosion surfaces. Stage 3 comprises relatively large baroque crystals, generally dully luminescent but with up to seven sub-zones. Isotopic and fluid inclusion data suggest growth of successive stages from waters which became progressively hotter (60°-160°C).The distribution of the ores follows the dolomite trend. Ores were precipitated between Stages 1 and 2 of dolomite growth, following Stage 2, and also during the nucleation and growth of Stage 3 crystals. Dolomitization and mineralization appear to have been temporally and genetically related. The cyclic sedimentation of the host rocks, which accentuates lithological and petrographical contrasts between depositional units, controlled dolomitization. The relationship between dolomitization and mineralization, which is closely associated with faults, provides powerful exploration criteria. The recognition of these features in limestones elsewhere in the Irish ore field may point toward unrecognized zinc-lead prospects."

Jan 1, 1997

By A. Haldar

This study focuses on the flow characteristics of hypereutectic Al-Si alloys in thin sections. The pattern assembly consisted of spiral horizontal patterns, 6.25 mm (0.25 inch) and 12.50 mm (0.50 inch) in thickness with a common sprue. Al-Si alloys with silicon levels of 14%, 18% and 22% were poured with superheats of 60°C, 115°C and 170°C. It was observed that metal fluidity (in terms of flow length and metal velocity) increased with increase in silicon levels and superheat for both section thicknesses. It was also observed that, for a section thickness of 6.25 mm (0.25 inch), silicon level had more pronounced effect on the metal fluidity. For 12.50 mm (0.50 inch) thickness, both silicon level and superheat affected the metal fluidity. The surface hardness of the castings increased with an increase in silicon level of the alloys at the gate and the flow tip. Detailed study of the flow tip was also carried out with a view to understanding the effect of silicon level and superheat on undulated flow length, surface hardness and microstructure.

Jan 1, 2007

By P. Kolodziejczyk

Mining seismicity can be harmful both under and on the surface. ? Tremors are not totally damaging, but destructive to buildings and infrastructure, especially in highly urbanized regions, such as Upper Silesia in Poland ? Destroy the social appreciation, trust and support for mining industry ? To prevent or reduce these effects, engineers and scientists develop methods allowing prediction of ground shaking intensity near buildings and various losses that can result from it Evaluation and prediction of mining tremor?s damaging influence on buildings is usually solved with two steps: ? Estimation of local ground shaking intensity (based on known attenuation relation) and classification into one of several predefined intensity intervals ? Apply supposed relation between the shaking intensity interval and qualitatively defined damaging effects to express predicted effects This makes a mixed quantitative/qualitative procedure, difficult to analyze or optimize

Aug 1, 2013

By B. W. Raymond, D. W. Zandee

"IntroductionCoal deposits are found in many regions in Canada and vary widely in their age, quality and rank. All classifications of coal except anthracite are found in significant quantities in this country.Deposits in the Maritimes are mainly bituminous; Lignite is found in Saskatchewan and Ontario and sub-bituminous coal in the plains region of Alberta. The Rocky Mountain coalfields of Alberta and British Columbia contain low and high-volatile bituminous coal and, in a few places, semi-anthracite. The British Columbia interior contains deposits of semi-anthracite, bituminous, sub-bituminous coals and lignite. The Yukon and Northwest Territories also contain substantial deposits of bituminous coal and lignite.Currently Nova Scotia produces both thermal and metallurgical coal, Saskatchewan produces lignite and Alberta produces both sub-bituminous and bituminous coal for thermal purposes. Large deposits of metallurgical coal are now being exploited in the Rockies arefl of British Columbia and Alberta by open pit methods. The raw coal is treated in large capacity preparation plants to remove refuse and upgrade the product to a consistent metallurgical quality with respect to ash, moisture, volatile matter and coking properties.The treatment of coal involves crushing, screening and cleaning by dense medium, jigs, water-only cyclones, tables and froth flotation to produce a diverse range of coal products differing in quality and size for various end uses.The chapter on Crushing and Screening Circuits was concerned mainly with crushing of metalliferous ores to produce a concentrate of one or more valuable minerals which normally constitute a small portion of the original mass of the material treated.Coal differs physically from ores in many ways such as lower specific gravity, relatively large volumes but low tonnage of product, and its habit of absorbing moisture requires extensive dewatering processes more complicated than settlement and filtration. Most significant, for this paper at least, is the fact that crushing coal is not as energy intensive and much smaller equipment is applicable.Crushing and screening of ores is intended to reduce the size of all constituents as quickly and efficiently as possible to allow liberation of the mineral particles. The crushing of coal is different in that the coal is not the minor constituent and the production of fines, in the initial stages at least, is highly undesirable. The basic objectives of crushing coal are the reduction of run-of-mine material to sizes suitable for cleaning or further reduction of coal to market sizes."

Jan 1, 1989

By B. Stettner, J. Asante, S. Abraham

The levels of nitrogen in steel produced in various metallurgical vessels vary significantly. For example, the tap nitrogen levels in steel produced in the BOF are around 4Oppm, as compared to 70-100ppm in both DC and AC electric arc furnaces. Given the pressing need to reduce nitrogen levels in steel to satisfy customer demand, IPSCO Inc. has gained considerable experience in controlling nitrogen levels in steel over the course of the last three years. Hence, a cost effective process has been developed through an intensive nitrogen control program from steel melting in the EAF through to the continuous slab casting stage. This paper describes the practices employed at each stage of the steelmaking process that have enabled IPSCO Inc. to reduce and control nitrogen levels in steel.

Jan 1, 2004