Search Documents

By W. D. Watson

"Early in mine development at Quintette Coal Limited major problems were encountered with the fleets of primary equipment which seriously hampered production. These major fleets (cable shovels, hydraulic shovels, hydraulic drills and electric trucks) have consequently been the focal point of maintenance efforts. Some were prototypes in the Canadian mining scene and brought with them new concerns to test their skills. The problems were studied and the category and areas which were having the greatest impact on the reliability of the equipment were determined. Once defined, priorities were established and a program was initiated which was designed to accomplish a resolution. Resulting from implementation of this systematic approach, over the past three and one-half years, the fleets are now giving good reliability and industry standard availabilities. Along with these significant achievements, cost per operating hour on some of the equipment fleets has decreased substantially and continue a downtrend through 1987. This paper identifies the problems and describes the resolutions. IntroductionIn the early years of the mine development, Quintette Coal Limited (QCL) experienced production shortfalls due to problems with the major excavator and haulage fleets. A large fleet of hydraulic excavators had been purchased, and QCL was among the first northern users of all hydraulic blasthole drills. They were also using some prototype equipment and encountered problems which were not common on other types of equipment or were unknown.Because of these unique problems and lack of experience from other mines to draw on, an analytical approach was taken to areas and associated causes of the delays affecting the availability and reliability of equipment. This was done by dividing the equipment downtime into seven classifications of delays, i.e. maintenance, electrical, hydraulic, mechanical, damage, service and preventative maintenance, and tires; and then each was expressed as a percentage of total downtime. Subsequently each of the delay classification was divided into categories e.g. electrical to six categories - wheel motors, main alternator, relays, cards, no propel, lighting and 24 V system. Then, the basis for further study had been established.From this preliminary analysis of historic records, it was possible to determine the areas which were causing the majority of the downtime. These areas were then analyzed to evaluate causes and to determine possible solutions to the problem s. This paper addresses the major fleets, their problems and eventual solutions. Plea se bear in mind that the over-all objectives were to increase physical availability and reliability."

Jan 1, 1988

By The Hollinger Mill Staff

ALTHOUGH cylindrical grinding mills have long been used, there is wide divergence of opinion as to what constitute best operating conditions. Questions such as mill diameter, diameter-length ratio, revolutions per minute, type and size of grinding media, volume of charge, circulating load, pulp level, pulp consistency, liner design, and size of feed, have all been given serious consideration by competent scientific investigators as well as by operators. While many laboratory and plant tests have been made that would seem to justify certain definite conclusions, there is a dearth of definite data giving actual results obtained when a grinding mill working between fixed limits is operated at its maximum capacity under varying conditions as to ball load, circulating load, speed, etc. In tests conducted recently at the Hollinger, extending over a period of thirteen months, to determine the best operating conditions for a ball-mill 6 ft. 6 in. diameter inside the liners, some very interesting facts have been ascertained. This paper is presented in the desire to make public the results of these tests and not with the idea that the last word has been spoken in regard to grinding. We feel, however, that these facts justify certain definite conclusions and hope that, by the fullest and frankest criticism and discussion, the essentials necessary for the correct design and operation of grinding mills will become better known.

Jan 1, 1937

By Cale J. Dubois

At Cameco Corporations' Cigar Lake Project, large excavations are developed on the 480 Level and 500 Level must remain stable for at least 15 years to host underground processing infrastructure. Following the successful dewatering of the mine in October 2009, subsequent internal rockmechanics investigations augmented by third party technical investigations; determined that to keep the back of the Water Flush Crusher/Run-of-Mine (WFC/ROMs) excavation stable; required a rehabilitation strategy to mitigate deterioration/deformation of the WFC walls and intersection pillars. The mechanism of failure propagating the movement of the excavation walls is understood to be controlled by the presence of a dominant E-W striking and steeply dipping foliation within a relatively weak and mildly altered rockmass sub-parallel in strike with 14 meters high walls and an intersection span approaching 15 meters. The application of open and resourceful communications between site mining engineers, geologists, contract mining staff, construction management experts, corporate mining and civil engineers, and third party technical experts resulted in a multi-faceted short-term ground support strategy consisting of standard bolting and screening, deep-seated modified-strand cable bolts coupled with heavy gauge mesh straps, rockmass reconditioning using low-pressure grout injection, and horizontal cable-lacing for the intersection pillars applied in lifts using a top-down methodology. The intention of the short-term strategy was to stabilize the excavation so that a long-term structural steel support installation - consisting of composite concrete walls, and arch support applied to the side walls and crown of the back - could be constructed safely. This paper summarizes the evolution of the short and long-term ground support strategy and criteria for the WFC/ROMs excavation developed using elements of civil, mining and hydrogeologic design.

Nov 1, 2011

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 J. Stachulak, M. Scobie

"This paper addresses the occurrence and indicated causes of conveyor fires in North American and European underground mines. Some significant convey or fires which have been experienced in recent years in Canadian hardrock mines are then reviewed. The nature of existing conveyor monitoring technology is considered in the context of such fire hazards. Experiences with new monitoring technology recently installed at several conveyor sites at Inca Ltd. mines are then reviewed.IntroductionFires associated with conveyors have long been recognized as a serious hazard in underground coal mines. Recently, however, there have been some significant conveyor fires in Canadian underground hardrock mines. These offer important evidence as to the nature and causes of potential hardrock mine fifes. They also warrant attention with a view to improving over-all mine design, ventilation and emergency preparedness.In addition, a new era in mine communications and monitoring technology has been entered which should offer improved capability to protect against such fires. This paper was motivated by the need to understand the causes and mechanisms of conveyor fires in order to improve their safety. This should be possible through implementing more effective monitoring systems, as well as improving conveyor design. Underground mines are becoming more intensively mechanized, with less human surveillance of equipment and a greater dependency on remote monitoring systems."

Jan 1, 1992

By M. Beech-Jones

The increased emphasis on the efficient utilization of capital and mineral resources has led to several new advances in the science of mineral separation. One example of a recent development is the application of high-capacity high-intensity wet magnetic separators to fine hematit e recovery by a leading Canadian iron ore producer. The iron ore recovery feasibilit , flow-sheet development, circuit operation and metallurgical performance are reviewed.

Jan 1, 1979

By M. Souley, G. Armand, M. Ghoreychi, D. Seyedi, J. -B. Kazmierczak

"An anisotropic constitutive model is proposed in this paper accounting for both structural anisotropy and induced anisotropic plasticity. It is assumed that the rock is composed of a matrix and of potential planes of weakness. The matrix is assumed to be linear, transversely isotropic and the plasticity is described by a non linear yield function where the parameters are deduced from the nonlinear Hoek-Brown envelopes in pre- and post-peak, and derived from the laboratory characterization. A non-associated flow rule is used with a distinction between compression and extensional stress paths, as well as the absence of volumetric strain beyond large plastic distortion.The planes of weakness are considered as known a priori or assumed to be oriented perpendicular to the direction of the current minor principal stress. An elastic-perfectly plastic behavior according to the Mohr-Coulomb criterion is assumed in the planes of weakness; while the elastic part is considered as linear and transversely isotropic.Finally, the proposed model was implemented in FLAC3D and used to simulate triaxial compressions to provide a verification of the implementation. The applicability of the implemented model to reproduce damage (pre-peak) and/or failure developments around a circular opening is checked. The GCS drift, one of the mine-by experiments set up at the main level of the Meuse/Haute-Marne Underground Research Laboratory, is selected for this first application."

Jan 1, 2015

By Owsiacki. Leo

Both the 8 and A-C ore zones of the Heath Steele Mine contain extensive areas of brecciated ore. This texturally distinct ore type has been tentatively defined as a fragmental or conglomerate massive sulphide. It consists of subangular and round fragments of pyrite up to 30 em in diameter, smaller quartz clasts and chloritized, mineralized, lithic fragments in a faintly banded matrix of pyrrhotite and chalcopyrite. The chalcopyrite is concentrated in the pressure shadows of the fragments and appears to reflect remobilization and recrystallization during a deformation which postdates the formation of the clasts. A generally conformable relationship with the underlying banded pyrite-sphalerite ore, discordancy with the host banded argillites, spatial distribution and similarity to Kuroko ores suggest that the fragmental ore is of primary origin and that breccia formation is probably due to soft-sediment slumping or sliding initiated by volcanic explosions, as hypothesized for similar massive sulphides in various Japanese mines. It is nevertheless recognized that certain structural features in some clasts may result from deformation preceding the formation of the breccia, and at this stage a tectonic origin cannot be completely eliminated.

Jan 1, 1979

By D. V. Dorling, J. T. Bowker, J. A. Gianetto

Over the last few years, interest in the development and construction of large diameter, high pressure pipelines from the Mackenzie Delta in northern Canada and Alaska's North Slope has steadily increased as a result of the projected decline in recoverable natural gas from existing reserves in western Canada. The success of such enormous pipeline projects, which will require utilization of a strain-based design approach, is largely based on successful application of high strength line pipe steels, such as X80 and X100. To fully realize the economic benefits of high strength steels, welding processes and procedures must be developed to ensure that the requirements for high strength and good low temperature toughness are confidently obtainable in field girth welds used in the construction of such pipelines. This study aims to provide a better understanding of the factors that control weld metal strength and toughness for a series of mechanized X100 girth welds produced using a range of narrow-gap gas-metal arc welding procedures. The attainment of high yield strength (> 810 MPa) is considered to be an important target to ensure overmatching strength relative to the longitudinal property distribution of X100 line pipe steel. Some factors that have been considered in this evaluation include influences of gas-metal arc welding process variants (single and multi-wire) and changes in welding procedure specifications, including joint preparation. Key components of this work relate to the reliable measurement of weld metal strength variation through-thickness and as a function of position around the circumference of a given girth weld.

Jan 1, 2005

By André Gobell

"La distribution des éléments majeurs dans une séquence de roches volcaniques felsiques, la formation de Waconichi, au sud de Chibougamau, indique que les roches pyroclastiques du secteur ouest de ce segment sont chimiquement anormales si on les compare à la composition moyenne des roches volcaniques de Chibougamau: elles sont caractérisées par une teneur anormalement élevée en f er, en magnésium et en potassium et une teneur anormalement basse en sodium et en calcium; ce chimisme caractérise les encaissants des dépôts de sulfures massifs d 'origine volcanique.Les coulées rhyolitiques massives sous-jacentes au gite de cuivre-zinc avec or et argent de Lemoine ne montrent pas ou très peu d’altération de ce genre. Le schéma de mise en place des dépôts de sulfures massifs d'origine volcanique et la nature des roches en présence permettent de croire que la zone d'altération mise en évidence à l'ouest de la mine Lemoine puisse être reliée à la mise en place de ce gisement d'ou l'im portance de tenir compte des caractères texturaux des roches lors de l'interprétation de données litho géochimiques."

Jan 1, 1980

By Ward E. Kilby, Bruce I. Mcclymont

"Data from the South Fork Pit Area of the Bullmoose deposit in northeastern British Columbia are used to demonstrate the usefulness of microcomputers to the on-site geologist. The technique utilizes a series of digital surf aces in the form of a network of points to define various geologic parameters such as seam positions, topography and coal quality characteristics. Manual digitizing, kriging and combinations of these techniques are used to calculate these digital surfaces, the best method depending upon the type and quality of the data in question. Digital surfaces, each modelling a specific feature when combined and manipulated with the computer form a powerful tool, the deposit model. The resultant model, containing all the surfaces, is used to examine seam and inter-seam thicknesses, deposit volumetrics, seam quality characteristics and the adequacy of sampling.IntroductionCoal deposit modelling using computer-based techniques has become routine. However, a geologist working in the field, without access to mainframe or minicomputer, ha s considerable difficulty implementing these procedures. However, microcomputers, which are portable and inexpensive can handle exploration data, perform various geological analyses, and produce deposit models virtually at the same time as the data is being collected. For the on-site geologist this means that quick access to the results of such modelling could point out inadequacies in deposit definition and trends in coal quality deserving investigation."

Jan 1, 1985

By David L. Anderson

This paper explores the financial impact of the initial version of the Saskatchewan Potash Reserve Tax; first, a one; and second, in conjunction with the other taxes affecting the industry's profitability. A though the introduction of the Reserve Tax is shown to lead to a substantia increase in a hypothetical firm's effective tax burden, the more unusual outcomes frequently attributed to this levy on y occur after the imposition of other non-provincial tax rulings. Despite this qualification, the results obtained suggest that the Reserve Tax undoubted y acted as a catalyst in the polarization of attitudes during the ear y period of industry/government confrontation

Jan 1, 1979

By H. K. Fredrickson

"Midwest Joint Venture (MJV) owns a high-grade uranium deposit in northern Saskatchewan. The deposit is located too deep below surface to be mined economically by open pit methods, and as a consequence, present plans are that it will be mined by underground methods. High-grade uranium ore of the type at MJV, encased in weak, highly altered ground and with radon-rich water inflows, has not before been mined by underground methods.The test mining phase of the project, completed in 1989, had three objectives: 1. to evaluate radiation protection requirements associated with the handling of large quantities of radon-rich water and mining highgrade uranium ore in an underground environment; 2. to investigate the quantity and quality of water inflows into the mine; and 3. to investigate ground conditions in and around the ore zone as an aid in determining the production mining method to be used.With information gained from the test mining project, a mining method for the production mine has been devised. Level plans have been drawn up, ventilation system designed, pumping arrangements made and methods of ore handling considered. All this is to be done in a manner that will be safe for those doing the work underground. Some of the mining methods planned are felt to be unique in that they are designed to cope with mining problems not known to have been encountered before. New problems underground have required new methods to handle them. Remote drilling, blasting, mucking and backfilling form the basis of the planned mining method."

Jan 1, 1992

By Christopher Andreae

"Years before the present iron and steel works were established at Sydney, several thriving although short-lived iron work s operated in Nova Scotia. These furnaces reflected the general nineteenth-century North American experience with iron work s. At the beginning of the century, small furnaces struggled to supply local needs. Charcoal was the principle fuel and water powered most furnace equipment. By the end of the century, a few huge primary iron and steel work s dominated production for Nova Scotia and the rest of Canada.Two sites achieved prominence in the nineteenth-century Nova Scotia iron industry: Londonderry and Ferrona. Londonderry, the larger and longer-lasting of the two sites, is today a small village on the south flank of the Cobequid Mountains, about 30 km west of Truro. Prior to the establishment of an iron works in 1849, no community existed. At the peak of operation in the 1880s, however, over 2,600 people were located there. The second site, Ferrona, today is a mere crossroads on the map, about 10 km south of New Glasgow. Following the construction of a blast furnace there in 1892, a small village grew up around the furnace, but once the furnace was blown out in 1904, the population gradually drifted away.Early HistoryThe history of Nova Scotia's iron industry began in 1604 when Samuel Champlain became the first European to identify iron ore in the future province. Despite this early acknowledgment, iron was not smelted commercially in Nova Scotia for another two hundred years. Although primitive smelters of the period produced more iron than could be used locally, early settlers depended on imports of iron from Britain and the United States."

Jan 1, 1983

By V. Prodanovic, M. Militzer

Production of advanced linepipe steels with strength levels of 685MPa (100ksi) and higher requires excellent control of runout table cooling to produce the desired final fine-grained microstructures, which may include acicular ferrite. Cooling is exerted on the runout table by applying water jets onto the hot surface of the strip and heat is removed from the steel by forced convective boiling. The associated boiling mechanisms are complex and include film, transition and nucleate boiling. A pilot-scale runout table test rig has been built to systematically study boiling heat transfer from a moving steel plate by employing industrial scale headers. Experiments were conducted using test plates moving at speeds between 0.3 m/s and 1.4 m/s. The plates were cooled down from 850°C to temperatures below saturation by a single water jet supplied through an industrial size circular nozzle. Based on these experiments heat fluxes were determined and further used to develop improved runout table cooling models.

Jan 1, 2005

By Donald E. Archibald, Gerald A. Allcott

"Noranda's Heath Steele Mine is located 35 miles north of Newcastle in northern New Brunswick. Blasthole open stoping with partial delayed filling is the major mining method in use. The selection of stope and pillar dimensions to ensure mine stability was originally subjective. This paper describes the progress made in attempting to rationalize design.One major feature is the fracture pattern. The main orebody now being mined, the B zone, has undergone five periods of folding and each period of folding developed a family of fracture planes which are axial planar to that particular fold pattern.The other major features considered are the calculated increase in stress due to mining and depth and its relationship to measured strain. Experience has shown that ground problems affecting production have usually originated in rib pillars. Field observations of ground deterioration and multi-wire extensometer measurements of strain are tabulated together chronologically for each pillar.A factor representing stress and a common plane of weakness are identified. Graphical analysis is used to determine the effect of the plane of weakness on a typical stress/strain curve and provides a base for the design of pillars."

Jan 1, 1981

By Z. Trojanová

The deformation behaviour of ternary magnesium alloys AJ (Mg-Al-Sr) and AX (Mg-Al-Ca) were investigated in tension as well as compression tests. The samples were deformed at temperatures between 20 and 300 °C and at an initial strain rate of the order 10-4 s 1. The flow stress decreases with increasing temperature. The macroscopic work hardening rate decreases with increasing flow stress and temperature. The stress and temperature dependence of the work hardening rate is a result of the hardening and softening processes. Stress relaxation experiments were performed in order to reveal features of the thermally activated dislocation motion. Internal and effective stress components of the applied stress were estimated. A decrease in the internal stress was observed at elevated temperatures, which indicates recovery process (-es). A more detailed analysis of the estimated values of the activation volume and activation energy helped to interpret the thermally activated processes during plastic deformation. It is concluded that the deformation behaviour of the alloys depends on the activity of non-basal slip that is strongly influenced by temperature.

Jan 1, 2007

By Ross L. Sherlock, David J. Scott, Gordon MacKay, Wayne Johnson

"Abstract - The demographics of Nunavut indicate a very young and poorly educated population spread over wide areas in small isolated communities. The current economic sectors will be unable to expand and meet the demands of this emerging workforce. Given the realities of Nunavut, the most promising direction in which the economy may expand is through mineral development. The Nunavut Land Claims Agreement (NLCA) has established the legislative framework for sustainable development in Nunavut through mineral development. The NLCA has transferred ownership for much of Nunavut’s potential mineral resources to beneficiaries of the lands claim. Royalties generated from mining operations on subsurface Inuit-owned lands, and to a lesser extent on Crown land, will flow back to beneficiaries of the lands claim through their administrative company, which may then be invested in the communities. Additional benefits of mineral resource development in Nunavut will be realized through impact and benefit agreements.To realize the benefits from mining operations, Nunavut has to be able to attract and support exploration and development companies through the release of high-quality geoscience data. However, due to Nunavut’s isolation and the expense of conducting geoscience fieldwork, the jurisdiction lags far behind the rest of Canada in terms of quality and quantity of government geoscience. About 70% of the territory is inadequately mapped to attract exploration companies or to make informed land-use decisions. The role of government-funded geoscience in Nunavut is to stimulate exploration and discovery through new framework mapping and focused thematic projects. The timely delivery of high-quality geoscience products will attract exploration companies to Nunavut and further their efforts to discover and develop mineral resources in order that the subsequent benefits of this activity may flow to the beneficiaries of the NLCA as well as all other residents of Nunavut."

Jan 1, 2003

By W. B. Morrey

"In recent years, the major effort in detonator development has been concentrated on ""non-electric"" systems. Existing types all involve some form of explosive reaction to transfer ignition energy from outside the borehole to the pyrotechnic delay element contained within the detonator. These may be based on low-energy detonating cords having grained or plasticized explosive cores, shock tube energy transmission principals and explosive gas ignition systems. Each has properties of internal and external effects not present in electric conductors.The MAGNADET System introduces transformer coupling into electric blasting circuits. Safety features with respect to current leakage, stray currents of AC or DC source, electrostatic energy and radio-frequency radiation are comparable to ""non-electric"" systems, with advantages in simplicity, speed of hook-up and range of application.The transformer device used is a small ferrite ring or toroid which is an integral part of each specialized detonator. The detonator legwires form the secondary side of the transformer winding. The primary side is a single wire loop common to all units within the circuit. Power is supplied from a frequency-tuned portable exploder with unique circuit-sensing features.The MAGNADET System is expected to have particular application to shaft sinking, raising and tunnelling where the protective features as well as speed and efficiency are critical factors. Applications of the 'MAGNA' booster in quarries, open pits and longhole deck charges offer control over vibration problems and elimination of surface noise.IntroductionFor many years, electric detonators and electric blasting systems dominated surface and underground applications where controlled delay times were required. Control over the instant of detonation by blasting machines or power-line switches is the major safety feature.Electrical energy exists in many forms. It may originate from many sources. Electrical energy can be difficult to contain. It may enter or escape through a variety of conductive paths. It may fluctuate, concentrate or dissipate to pose a most elusive potential hazard."

Jan 1, 1982

By David A. Grieve, David E. Pearson

"A rank-map of Crowsnest coalfield, showing the distribution of the bituminous coal measures and the locations of major structures, has been produced from vitrinite reflectance measurements on over600coal samples. The timing of coalification in relation to these major structures has also been determined.In the west-central portion of the coalfield a complete stratigraphic succession of coal measures which rides on major thrust surf aces is all of high-volatile bituminous rank, but despite the structural discordance no break in rank is discernible across these structures. The thrust faults therefore predate much of the coalification.Three major valleys expose cross sections of the folded coal measures and in each an increase invitrinite reflectance is demonstrable as individual seams are traced from ridge crest to valley floor. Thus, in these sections, a significant amount of coalification post-dates folding. The proportion of this post-folding coalification is found to increase toward the south of the coalfield.A late gravity-fault, exposed along the east crop of the coalfield, places high-volatile coal-bearing successions in contact with low-volatile coal and demonstrably is a reactivated thrust fault. Coalification at this locality occurred between these two different ages of faulting.The variations in rank and the subtleties of the coalification pattern have, together with systematic changes in the maceral composition of coal seams, had a profound effect on coal quality in the coalfield. Coking coals with a variety of properties occur together with some coals that have no caking capacity."

Jan 1, 1985