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By M. D. Lawton, P. Steen

"Drilling results from the established levels at AngloRouyn Mines Limited had indicated inadequate tonnages to meet the planning schedule. It was decided to develop the main zone of the orebody below the bottom working level of the mine. The orebody dips north at an average of 50 degrees and plunges to the west at about 10 degrees. Due to the need for rapid development of this area, a decision was made to use trackless equipment.This paper describes the method used and highlights the use of small 5-ton diesel trucks as carriers for the 2-cu.yd LHD machine. The method achieved advances of about 1,000 feet per month, at a dip of 12 degrees over a length of close to 2,000 feet, using as few as 20 men per day."

Jan 1, 1971

By C. A. Pickles

Microwaves are being applied industrially in a number of fields and possess a number of potential advantages that could be applied in extractive metallurgy. Microwave heating has a number of unique characteristics, which distinguish it from the conventional heating methods. In microwave heating, the absorption of energy occurs at the molecular or atomic level and therefore the heat is generated within the material itself. In conventional heating, the exterior temperature is usually higher than the interior, but with microwave heating, the temperature gradient is inverted and thus the interior temperature can be much higher than that of the surface. The energy densities in microwave systems can be relatively high and this in combination with the low thermal conductivities of oxide ores, can lead to very high internal heating rates. In this research, the application of microwave energy for the reduction of a nickeliferous silicate laterite ore has been investigated. The real and imaginary permittivities are the two fundamental properties which determine the microwave absorption characteristics of a material and these were measured for the ore, both with and without carbon additions using the cavity perturbation technique. The microwave heating and reduction experiments were performed in a 0 to 2 kW CTC microwave system. The effects of power input, processing time, sample mass and charcoal additions on the microwave absorption were investigated. Then reduction experiments were performed and the nickel grade of the magnetic concentrate and the nickel recovery in the concentrate were determined.

Jan 1, 2005

By Penny C. Stewart

Narrow vein underground stope design engineers in Australia have expressed significant interest in the requirements and methodology for developing site-specific stability charts. This is largely due to a concern that existing stope stability charts inadequately take into account factors influencing narrow vein stope stability, such as the effect of backfill abutments and the effect of in stope pillars. This paper presents conclusions from a comprehensive statistical examination of case history requirements for a site specific stability chart and critiques literature arguments for site-specific charts. A new statistical analysis technique and a large comprehensive stability database enabled the authors to quantify case history requirements and any site-specific effects the model exhibits. The analyses indicated that a reliable stable-failure boundary requires at least 150 case histories, of which a minimum of 10 percent should be unstable stope surfaces. Marginal site-specific effects were observed for the operating conditions captured within the database. The authors conclude that the apparent site-specific effects noted in previous literature are attributable to operating conditions inadequately represented in the database. Such operating conditions could induce erroneous stability predictions at any site, and are therefore not truly site-specific. Following from these conclusions, a strategy for taking into account operating conditions particularly relevant to narrow vein mining has been proposed. In particular, the development of a chart that accounts for the effect of backfill abutments on stope stability. Backfill abutment effects are particularly relevant to mechanised narrow vein mining methods such as modified Avoca. Collaboration from at least five sites is required to obtain access to relevant data and underground drives for geotechnical mapping. Preliminary estimations indicate that approximately three months fieldwork is required to meet case history requirements. CMS data in conjunction with 3-dimensional design software will be used to calculate equivalent linear overbreak/slough (ELOS). In contrast to stable, failure, major failure and caving categorical variables, ELOS is an objective and continuous stability variable and is therefore, more conducive to mathematical modelling.

Oct 1, 2001

By J. E. Udd, S. Bharti

"ABSTRACTMonitoring of stability conditions in underground mines permits management to assess the response of the rock mass to mining strategies. Monitoring of movements, if sufficiently early, may also permit operators either to avert potential failures or to develop alternative approaches to extraction.The Falconbridge organization has been a leader both in the uses of rock mass stability monitoring techniques and in the development of instrumentation.In this paper, the authors review the Falconbridge approaches to monitoring, and present case history examples to illustrate the application of the various instruments used.RESUMELa surveillance des conditions de stabilité dans les mines souter-raines permet aux chefs d'enterprises d'évaluer les réactions de la masse rocheuse aux méthodes d'extraction minière. Si le contrôle des mouvements du terrain est effectué assez tot, l'exploitant pourra prendre les mesures qui s'imposent, soit pour éviter les détériorations possibles ou pour mettre au point de nouvelles méthodes d'extraction.Le groupe de la Falconbridge a ére le premier a utiliser des techniques de vérification des conditions de stabilité de la masse rocheuse et a mettre au point l'appareillage requis.Ce document présente une revue des méthodes employées par la Falconbridge pour assurer la surveillance active de la stabilité de la masse rocheuse et illustre au moyen de cas concrets la manière d'utiliser les divers appareils."

Jan 1, 1987

By G. Graves, J. A. Walker

"Abstract - The Mount Fronsac North volcanogenic massive sulfide deposit is the most recently discovered massive sulfide body in the Bathurst Mining Camp. The deposit occurs within a sequence of intercalated fine-grained felsic tuff and sedimentary rocks (Little Falls member), at the top of the Nepisiguit Falls Formation. Aphyric to sparsely feldspar-phyric rhyolite and related volcanic rocks of the Flat Landing Brook Formation overlie the host sequence. The massive and semimassive parts of the deposit have a north-south strike length of 525 m and a dip of ~45°E; the deposit is continuous downdip for 600 m, and thickness varies from 2 to 20 m. The deposit contains an estimated geologic resource of 14 Mt of low-grade, semimassive (>60%) to locally massive sulfides, and includes a high-grade zone of 1.26 Mt grading 7.65% Zn, 2.18% Pb, 0.14% Cu, 40.3 g/t Ag, and 0.40 g/t Au. The semimassive to massive sulfide intersections occur in an envelope of quartz-sericite±chlorite schist, which is interpreted to be intensely deformed felsic tuff. This sequence has a maximum thickness of 140 m and contains significant (up to 50%) fine- to coarse-grained disseminated pyrite. The pyritic envelope has a strike length of 900 m and extends over 1000 m downdip. Massive sulfides are found throughout this alteration envelope, but more commonly occur at or near the upper contact. The significance of the discovery of this deposit is that it represents a near surface discovery of a large tonnage sulfide body in a mature mining camp, one in which the possibility of discovery of a new shallow deposit had been all but discounted. This opens the possibility for future discoveries in this part of the Bathurst Mining Camp. Sommaire - Le gîte de sulfures massifs volcanogènes du Mont Fronsac Nord est la découverte de sulfures massifs la plus récente dans le Camp Minier de Bathurst. Le gisement est situé dans une séquence de tufs felsiques à grains fins interlités de roches sédimentaires (membre de Little Falls, au sommet de la Formation de Nepisiguit Falls. La partie massive et la semimassive s’étendent du nord au sud sur 525 m et ont un pendage de ~45°E; le gisement est continu sur 600 m en angle de chute et son épaisseur varie de 2 à 20 m. Le gisement contient une ressource géologique évaluée à 14 Mt de sulfures semimassifs (>60%) localement massifs à basse teneur, incluant une zone à haute teneur de 1.26 Mt titrant 7.65% Zn, 2.18% Pb, 0.14% Cu, 40.3 g/t Ag, et 0.40 g/t Au. Les intersections de sulfures semimassifs à massifs se situent dans une enveloppe de schiste à quartz-sericite ± chlorite interprétée comme un tuf felsique intensément déformé. Cette séquence contient une quantité importante (jusqu’à 50%) de pyrite disséminée dont le grain varie de fin à grossier et son épaisseur maximale est de 140 m. L’enveloppe pyriteuse s’étend latéralement sur 900 m et a été tracée jusqu’à 1000 m en angle de chute. Des sulfures massifs sont trouvés partout à l’intérieur de cette enveloppe d’altération, mais ils sont plus fréquents près du contact supérieur. L’importance de cette découverte tient à ce qu’elle est un exemple d’un gisement à fort tonnage nouvellement découvert à une faible profondeur dans un camp minier mature, i.e., un camp ou l’on ne croyait plus qu’il était possible de trouver un gisement près de la surface. Ceci ouvre la porte à la possibilité d’autres découvertes dans cette partie du Camp Minier de Bathurst."

Jan 1, 2006

By M. Gyenge, O. F. Coates, K. Barron

"It is suggested that artificial supports might be used to increase, with safety, the angle of hardrock open-pit slopes. Guidelines for designing such a support system, based on a simplified analysis, are given. The installation, construction and instrumentation of a trial support system is described and a breakdown of the construction costs is given. On the basis of this cost analysis, the economic benefits derived from reduced waste-rock excavation are compared with the support costs for a typical mine. In an example, it is shown that the slope angle in an open-pit mine 500 ft deep, with benches 50 ft high by 30 ft wide, could be safely increased from 37Yz degrees without support to an optimum of 53 degrees with support. In this case, the support costs would be approximately $900 per linear foot of pit wall and the savings due to decreased excavation of waste rock (at $0.34/ton) would be approximately $1,900 per linear foot, yielding an increased margin of profit of approximately $1,000 per linear foot of pit wall. This figure could be increased to $6,000 per linear foot if the steeper slope were used to extract more ore.More than 50 per cent of the support costs are accounted for by diamond-drilling the holes for the deep cable anchors. The use of percussion drills for this purpose would seem to offer a means of significantly reducing the support . costs and thus further increasing the profit margin available."

Jan 1, 1971

By Brian G. Pewsey

Located in the northern part of the Province of British Columbia, the Cassiar Mine started development of its asbestos orebody in 1952, and is currently producing 105.000 tons of asbestos fibre annually. The townsite is nestled in a beautiful valley and supplies more than average facilities. The fibre is shipped to more than 40 countries and is used in many industrial products.

Jan 1, 1978

By J. H. McMillan

Most of the recent papers read before the Institute have dealt with purely scientific matters, or with experiences in the various phases of mining operations. Very little, if anything, has been said concerning the part played by the human element in the industry. It is now opportune to consider this vital factor if we are to cope with the complex work of the present-day miner and, at the same time, meet the demands of the executive for greater efficiency. It is time we made an inventory of our knowledge to determine if we are absorbing the information so essential to modern mining practice. We must keep in close touch with all new ideas and developments in our chosen field and keep ourselves up-to-date in regard to everything pertaining to mining operations in general. The man who ceases to study ceases to advance. There are men who on attaining an executive chair give up all study, because they think they have reached the pinnacle of success. Modern industrial business, and coal-mining is no exception, demands that executive officers shall be 'live wires' -- men who are not only well-informed as to their immediate duties, but who are closely in touch with all matters of importance affecting the industry as a whole. We may be graduates of schools and colleges, but the training we receive in these institutions is only the foundation for our later work. Certainly no executive officer can know too much concerning the work he is engaged in, and the more he knows the more pleasure he will get out of his work.

Jan 1, 1925

By J. M. Wolverton

CONSIDERABLE interest has always been taken in Safety-First and First Aid at the Sullivan mine. Even during the early days of development, Safety-First committees periodically held meetings, while lectures in first aid were given to any employees interested in the work. In 1929, a Safety Department was organized, and all accident-prevention and first-aid work was put in charge of a full-time Safety Engineer. An extensive programme has gradually been developed, the value of which can best be indicated by the reduction of the accident rate from 18.4 shifts lost per 1,000 shifts worked for non-fatal accidents and two fatalities for 1927, to 3.24 shifts lost per 1,000 shifts worked and no fatalities for 1936. SUPERVISION All work connected with accident prevention or first aid is under the jurisdiction of a central committee, known as the Accident Prevention Committee, which meets regularly once a month. It consists of all superintendents, department heads, foremen, and shift bosses, and is presided over by the Safety Engineer. At these meetings, the accident records of the previous month are reviewed and all accidents carefully analyzed and discussed. All proposed changes in the safety rules or in the accident tprevention programme are taken up and passed upon. Complaints or suggestions from the Safety-First Committee and the Employees Co-operative Committee, dealing with safety, are discussed and passed upon or a subcommittee is appointed to investigate and take any action found advisable. The question of underground ventilation and dust control, which recently has become a very important problem, always receives considerable attention.

Jan 1, 1937

By A. S. Nortjé

At South Deep Gold Mine longhole stopes are backfilled using a cemented Cyclone Classified Tailings in its hydraulic state. The need to contain the hydraulic fill until cured requires a barricade. Due to the massive size of the stopes, the tailings can exert enormous forces on any such barricade. Barricades have long been in use, but recent failures in Australia and the large rate of filling required at South Deep solicited a robust design. A robust design must examine all foreseeable failures and the barricade must be able to resist all expected and, within limits, unexpected loads. The design should also be simple to construct and cost effective, limiting the impact of construction errors and unnecessary delays to production.

May 1, 2007

By N. Erarslan, M. Ghamgosar

The size of rock fragments depends on the nature of the loading applied the strength of the minerals and the texture of the rock. Research in the literature demonstrates that there is a distinct difference in the rock fracturing process for static and cyclic loading. The tensile strength of brittle rocks is also one of the most significant parameters influencing the rock fracturing process and the propagation of micro-fractures on the crushing, blasting and cutting of rock. The Brazilian indirect tensile test, one of the methods approved by the International Society for Rock Mechanics (ISRM), has been used to determine rock fracture behaviour under different cyclic loading modes. In this study, the dimensions of Brisbane Tuff specimens have been selected according to the method outlined by the ISRM. The main aim of this study is to evaluate the effect of cyclic loading amplitude and frequency on the Fracture Process Zone (FPZ) at the micro-, meso- and macro-scales. The post-failure behaviour of the Brisbane Tuff specimens was obtained under cyclic loading with frequencies varied from 1 to 10 Hz. The amplitude was varied from 10% of Ultimate Tensile Strength (UTS) up to 80% UTS. Laboratory investigations of rock fragment size revealed that different loading frequencies and amplitudes produce different FPZ dimensions. Multivariate Analysis of Variance (MANOVA) results demonstrated that the FPZ dimension is relatively sensitive to the frequency change. Fragment size analysis showed that the FPZ is a consequence of the initiation, propagation and coalescence of micro-fractures and depends on the nature of the loading. Laboratory evidence showed that the FPZ dimension, for the cyclic tests performed on Brisbane tuff, is ranged from 0.07 to 20 mm. The achievement of this study highlights a key finding in the understanding of fracture patterns and propagation models in the FPZ under cyclic loading, which is the dominate mechanical action in the oscillator disc cutter (ODC).

Jan 1, 2015

By Arthur Notman

In view of the alarm expressed in many quarters over the increased production of copper to come from Canada and Africa in the future, it is of interest to study the history of the principal producing districts of the world and to attempt to forecast the future part to be played by them. Tables 1 and 2 record the world production and that of the United States, together with their respective rates of increase, both in percentage and actual amounts. The important point in this record is the decline in rates of increase for both the world and the United States, but more particularly in that of the latter, since 1881. The increase for the United States in the last decade is less than that for any decade since 1881, and is only 20 per cent of that for the decade 1911-20. The increase for the world is less than that for the two preceding decades, and is only about 65 per cent of the war decade 1911-20. Referring to Table 1, the decade 1871to1880 showed an increase of 32.l per cent in the world's production, which was the low until the last decade, ending 1930, which shows an increase of only 24.5 per cent. These decades both represent periods of economic stress following wars. In the first case the recovery was very sharp, the percentage increase in 1881-90 reaching a high of 86.4 per cent. It would seem dangerous, however, to assume that a similar high will be reached in the next ten years, because of the severity of the depression brought about by the Great War and the probability of its influence extending well into the next decade.

Jan 1, 1931

By D. J. M. Farnsworth

Since the 1.940's, the bulk of the ore production from the Sullivan Mine has come from pillars. These pillars, located from 100 to 2000 feet below surface, have been subjected to considerable ground pressure. Mining techniques were adopted to minimize the problems of deteriorating ground conditions. These techniques included an orderly sequential blasting of pillars along a retreat front, stage blasting of tall pillars in horizontal slices and utilization of broken pillars as "buffers". The latter two techniques involved leaving substantial tonnages of broken ore in place for as long as 4 years. Rapid oxidation of metal sulphides, with attendant heat and noxious gas generation, had occurred in a few very localized areas of the mine associated with a major water course. However, in a very short period starting in 1972, sulphide fires spread to several of the large blocks of broken ore that had been left inactive for lengthy periods. There proved to be no feasible method of extinguishing these fires, except by complete removal of the burning ore. The attendant problems of handling large tonnages of burning ore have had considerable negative impact on the mine operation. The chemical reactions involved in these sulphide fires have been studied by the mine staff to determine the conditions necessary for' initiation and propagation of the tires. Techniques to safely and efficiently handle hot ore have been implemented and refined. Lastly, and most important, mining methods at the Sullivan Mine have been revised to ensure that additional fires do not occur.

Jan 1, 1977

By D. M. Maijer, S. L. Cockcroft, A. B. Phillion, P. Fan, C. Reilly

"A numerical model has been developed to study macrosegregation associated with liquid feeding in the Low Pressure Die Casting of A356 aluminum alloy wheels. The model of the wheel casting process has been implemented within the commercial CFD software package, FLUENT, using a User Defined Function (subroutine) to account for Si rejection based on the Scheil approximation. The model has been validated against temperature and microstructural data taken from a commercially cast wheel. The amount of segregation in the wheel has been shown to be significant in a couple of key areas. The implications of accounting for segregation include an improved ability to predict shrinkage porosity, fatigue performance and potentially also hydrogen porosity.INTRODUCTION The aluminum alloy A356 is widely used in the automotive and aerospace industries for various components. Examples include automotive wheels, automotive suspension components and airframe castings. Focusing on automotive wheels, Low-Pressure Die Cast (LPDC) A356 wheels offer significant design freedom and are far more aesthetically appealing to consumers than conventional stamped steel wheels. A356 wheels now dominate the market, appearing in all but the entry level offerings of the OEM manufacturers. However, they are typically over-designed to allow for the various casting related defects that degrade their mechanical performance. Thus, their potential to save weight has not been fully realized. Wheel manufacturers are under constant pressure to ensure their products meet strict mechanical requirements (ductility, fatigue, vibration), tight geometric tolerances and high aesthetic quality. The mechanical properties of the final product are determined by the microstructure – e.g. SDAS – and the defect population (porosity and oxides). Depending on their size and location, both porosity and oxides, can act as crack initiation sites reducing fatigue life (Caton, 2001; Jordan, 2010; Wu, 2015). There are a number of examples appearing in the literature (Atwood, 2000; Carlson, 2007; Lee, 2001; Yao, 2011) of numerical models that have focused on hydrogen-based pore formation that have demonstrated an ability to predict porosity formation and pore size distributions in geometrically simple castings. These models assume that the local gas species diffusion through the liquid metal to the pores is the rate-controlling factor of pore growth. Another common source of porosity is liquid encapsulation (Dantzig, 2009). As the pressure within the isolated liquid drops, pores form first due to the pressure dropping below the equilibrium partial pressure of hydrogen in solution and then second grow substantially as the pressure continues to drop falling below the vapour pressure of Al. One factor that can affect both mechanisms of pore formation is species macrosegregation, which has received comparatively little attention in die-casting."

Jan 1, 2017

By Ki-Bok Min, Seokwon Jeon, Seung-Beum Choi, Taehyun Kim

"In order to investigate anisotropic characteristics of Boryeong shale in Korea, which clearly shows transverse isotropy, a series of experimental tests were carried out. Using Brazilian test, five elastic constants and tensile strength of the shale were evaluated. Elastic constants were determined by iterative procedure and in order to perform this procedure, constitutive model was modified to fit the experimental condition. The anisotropic ratios of elastic constants were evaluated and the applicability of the methodology was assessed. Apparent Brazilian tensile strength profile was investigated and the ratio of the maximum to minimum tensile strength was estimated. Results showed that the tested rock type had low to moderate anisotropic characteristics.INTRODUCTIONMechanical, thermal and hydraulic characteristics of many rocks vary according to direction, which is known as inherent anisotropy, and it is originated from stratified and/or foliated structure of intact rock and discontinuity of rock mass. Anisotropy is one of the long standing issues of rock mechanics field and it has to be taken into account in several engineering fields such as civil, mining and petroleum engineering. An anisotropic medium has 21 independent elastic constants without any assumption of symmetry. If a material has any symmetry, the number of elastic constants required to define its behavior reduces and eventually two constants are necessary if it has complete symmetry, which is known as isotropy. An anisotropic medium that has remarkable planar structure due to its stratification and foliation such as bedding is often called as a transversely isotropic medium. Transversely isotropic model is frequently adopted in many applications especially for sedimentary rock formation and five elastic constants are required to establish the constitutive model."

Jan 1, 2015

By Christian Bourcier

La méthode d?exploitation traditionnelle de la mine est le chantier chambre-magasin. Cependant, lors de l?exploitation d?un chantier, nous avons été confrontés à un problème de soutirage. Le minerai abattu est resté accroché à l?intérieur du chantier ce qui nous obligea à soutirer environ 200 wagons, représentant 700 tonnes. Suite à l?ampleur de la situation, nous avons décidé de finir l?exploitation du chantier par la méthode sous-niveau long trou retraité. Cette première expérience de récupération de piliers ayant été réalisée avec succès, nous avons décidé de continuer avec deux autres récupérations de piliers afin de pouvoir augmenter notre expertise autant au niveau technique qu?au niveau économique.

Oct 1, 2001

By Will S. Pettitt

Fracture Network Engineering (FNE) is the engineering design of rock mass disturbance through the use of advanced techniques to model fractured rock masses numerically, and then correlate field observations with simulated fractures generated within the models. Microseismic (MS) monitoring is a standard tool for evaluating the geometry and evolution of the fracture network induced during a hydraulic treatment, principally by source locating MS hypocenters and visualizing these with respect to the treatment volume and infrastructure (Figure 1). The integrated use of Synthetic Rock Mass (SRM) modeling of the hydrofracturing with Enhanced Microseismic Analysis (EMA) provides a feedback loop in which the SRM is constrained by the information provided by the MS data and the in-situ behavior of the fracture network is better understood, leading to informed decisions on future field operations. This paper discusses the technologies used in FNE and some of the developmental challenges we face in order to provide a more efficient and robust application of the approach. One particular challenge is the accurate representation of MS source data within the models (locations, magnitudes and mechanisms), and the ability to correlate these data effectively with field results. This challenge is being overcome by the development of more efficient numerical modeling algorithms, providing simulations in three dimensions at reservoir scale, combined with validation of these algorithms using laboratory and field case studies.

Jun 1, 2012

By Geology Staff, C. H. Stockwell

"The Flin Flon base metal mine, owned and operated by the Hudson Bay Mining and Smelting Company, is on the Manitoba-Saskatchewan interprovincial boundary at a point 400 miles north of the International boundary. The deposit was discovered in 1914 by Thomas Creighton and the Mosher and Dion brothers. Since production commenced in 1930, 25,000,000 tons of ore have been mined. On January 1st, 1946, reserves were estimated to be 26,000,000 tons, averaging 2.99 per cent copper, 4.i4 per cent zinc, and 0.089 oz. gold and 1.25 oz. silver per ton. In addition to the four metals named, others recovered from the ore include- cadmium, selenium, and tellurium. The mine workings extend to the 3,750-foot level, but little development work has yet been carried on below 3,250 feet.The known ore occurs in six lenticular to irregular bodies within a zone 500 feet wide. These bodies average 900 feet long, 70 feet wide, 1,500 feet in vertical depth, and 2,500 feet in length along the plunge. They were formed by replacement of the country rock and include ore of two types, solid sulphides and disseminated sulphides. Seventy per cent of the total known ore is of the solid sulphide type. This consists essentially of metallic sulphides- chiefly pyrite- with included remnants of the host rock, and additional quartz and carbonate. In places, the ore exhibits banding, inherited from pre-existing structures. The disseminated ore occurs usually on the footwall side, and along the bottom of the plunge, of the solid sulphide bodies."

Jan 1, 1954

By L. Rao, P. Carabin

"Advances in thermal plasma torches have resulted in this technology becoming a commercially viable solution for chemical and metallurgical processes. The main advantages of plasma are its ability to control process chemistry and to build small footprint reactors due to its high energy density and reactivity of the free radicals that are produced. This paper focuses on thermal plasmas produced by DC torches and their applications for waste treatment, production of high purity metals, and nanomaterials. Both transferred and non-transferred torches have been used as either a source of heat or as a reagent in various industrial processes. INTRODUCTIONPlasma technology has become an ideal solution for many industrial chemical, metallurgical and mechanical processes (Venkataramani, 2002). Thermal plasma powered systems are typical used for their unique characteristics such as high energy densities, high temperatures, small installation sizes, rapid startup and shutdown features, controlled process chemistry and use of electrical energy as a heating source resulting in decoupling the heat source from the oxygen flow rate (Heberlein et al., 2007). Depending on the nature of the main plasma forming gas used, thermal plasma systems offer a high temperature heating source coupled with a highly reactive plasma plume rich in free radicals and ions which promote otherwise hard to drive chemical reactions, as well as high heat transfer rates.Industrial plasmas can be broadly classified as thermal plasmas and non thermal plasmas. Thermal plasmas are atmospheric pressure plasmas characterized by local thermodynamic equilibrium (Boulos et al., 1994). Thermal plasmas are typically established between any two current conducting electrodes separated by an insulator. A plasma forming gas is blown between the two conducting electrodes resulting in a high temperature plasma plume. A plasma torch generates and maintains an electrically conducting gas column between the two electrodes; a cathode (negative electrode) and an anode (positive electrode) (Camacho, 1988). If both electrodes are housed in a single housing, resulting in an arc enclosed inside the plasma torch, then such plasma generating torches are termed as non-transferred (NT) plasma torches, whereas, if the second electrode is external to the torch, creating an arc transferred between the cathode and the working piece, then such plasma torches are termed as transferred (T) plasma torches. Depending on the source of the electricity which can be either direct current (DC), alternating current (AC) at main network frequency or at radio frequency (RF), the plasma torches are classified as DC, AC or RF plasma torches (Venkataramani, 2002)."

Jan 1, 2012

By Guy Demers

"This paper defines the responsibilities and functions of the Maintenance Department, and its organization, physical and human assets, highlighting the unique operating problems. Due to the self-sufficient aspect of the Asbestos Hill Deception Bay project, the Maintenance Department cover-s fields that are numerous and very dissimilar: production, mobile, processing, service, power generation, fire protection, heating, water and sewage disposal equipment. Added to this, buildings, plant and camps, wharves and communications equipment all demand versatility, adaptability and expertise from maintenance personnel. Good maintenance practices are a necessity in this environment and are more critical than at southern locations; that is, high-quality replacement material, complete and well-controlled preventive maintenance, major repairs on a component-replacement basis, updated inventory, efficient training and permanent contacts with suppliers, combined with an equipment improvement program, updated specifications on lubricants, hoses, seals, filters, etc., are mandatory. The seasonal aspect of the operations applies a great deal of pressure on the maintenance team, as the production months do not permit major repairs. Short- and medium range planning and accurate evaluation of equipment conditions highly influence production efficiency. Maintenance control, planning and scheduling do not follow the accepted standard routines, as personnel turnover normally does not permit an accumulation of knowledge of the equipment history and condition by the •individual tradesman."

Jan 1, 1976