Search Documents

By G. Pouskouleli, T. A. Wheat

"The role and benefits of using statistical methodology in the development and optimization of materials and processes is examined. It is shown that considerable benefits accrue from the use of an appropriate design in which a number of factors (process parameters) are varied simultaneously while the system response such as percent recovery, degree of separation, purity, etc. is monitored and ultimately optimized.Compared with the commonly encountered one-factor-at-a time approach, this schema exploits reduced experimentation (thereby requiring reduced resources [staff, time, dollars, etc.]) yet yields quantitative information on the significance of each factor and their combinations on the measured response."

Jan 1, 1992

?NWCC has the highest number of Aboriginal students of any post secondary institution in BC and the region served includes 25 bands ? Chair of the Board of Governors is Irene Seguin (Hagwiloo K?am Saxwhl Giis) from Gitwinksihlkw ? FN council ? 39 First Nations Members * focus is to develop policy recommendations to increase student success rates

May 1, 2009

By P. K. Kaiser, S. Maloney, S. Yazici

"This paper focusses on the strength or capacity of cable bolts and introduces a new perspective for cable bolt design by demonstrating that mining-induced stress changes may affect cables in a detrimental manner. The concept underlying a novel cable bolt pull-out resistanceor bond capacity model is described and its practical significance is demonstrated by application to a simple two dimensional scenario of a fall-of-ground.A number of practical implications emerging from the application of this model are discussed to provide guidance to ground control personnel jar improving cable bolt support systems in mining applications. These include cable layout optimization, use of cable pre-reinforcements, assessment of embedment length requirements, need for plated cables (or straps), use of bird-caged cables (or buttons), and grout quality issues.IntroductionDuring the last decade, cable bolting has become a standard support technique in mining for handling wide spans, reinforcing are passes, preventing or reducing dilution of ore in marginally stable stopes, and for many other rock support need s.In its infancy, many deficiencies in cable bolt supports resulted from improper installation techniques and, in particular, grout quality control problems and the use of empty breather tubes (Goris, 1990). The development of special grout pumps and fail proof placement procedures (Oliver, 1992; Bourchier and O'Flaherty, 1992) have eliminated many of these early problems. Nevertheless, there are still situations where cables seem to lose their capacity during mining, and in these cases the cables do not provide the expected and needed ground support. In some instances, cables perform extremely well, whereas in others the same support layout and quality of support installation seem to be insufficient, allowing falls-of-ground or progressive cavings to occur."

Jan 1, 1992

By S. S. Rahman, A. Gholami, M. A. Aghighi

"This paper provides a foundation for studying the growth of fractures in presence of other discontinuities and different anisotropies of low permeable hydrocarbon formations and helps to improve the design strategies for multistage fracturing.The multistage fracturing technology has recently been used to exploit low permeable hydrocarbon reservoirs. However, the mechanism of hydraulic fractures interaction and the impact of local heterogeneities on ultimate trajectory of the growing hydraulic fractures are not yet understood in depth. A fully coupled poroelastic Finite Element based model is developed to investigate the mixed mode propagation behaviour of growing hydraulic fractures. This model takes advantage of an explicit representation of the fracture which enables us to take the effects of rock and fluid related parameters into account. Moreover, impact of fracture geometry and leak-off phenomenon is investigated. The refined mesh around the crack provides the added advantage of more detailed stress distribution, pore pressure change and back stress in the vicinity of the fracture and in particular at the fracture tip. The potential deviation propensity of the fractures is evaluated based on the fundamental rule that fractures propagate perpendicular to the direction of the minimum horizontal stress.This study shows that pressurization of transverse hydraulic fractures results in the reorientation of local principal stresses, particularly in vicinity of fracture tips. Variation of flow patterns clearly influences the evolution of shear stress around the fracture tips which will potentially lead to mixed-mode I and II fracturing and consequently, fracture deviation. The presence of local heterogeneities such as preexisting fissures and/or fractures is a main source of such pore pressure induced stress redistribution and reorientation and potential deviation of hydraulic fractures.Most existing models ignore or simplify the effect of pore pressure/stress coupling as well as the fracture geometry and fluid flow within the fracture. Also, the fluid leak-off from the hydraulic fracture into the formation, which is a controlling factor in fracture growth, is often considered using analytical models. Taking advantage of a fully coupled porelastic model along with an explicitly discretized fracture, this study provides a more realistic insight into the complex fracture propagation processes of multistage fracturing operations particularly in presence of reservoir geo-mechanical complexities."

Jan 1, 2015

By Tim J. Carew, Dennis C. Martin

"One approach to stabilization of rock slopes is to place a buttress at the toe of the slope to provide additional resisting forces and increase the length and strength properties along the failure surface. This paper describes the rock mechanics and mine planning aspects of incorporating a buttress of intact rock in the lower part of the slope as part of the slope design for the south wall of the final pit at Cassiar Mine. Stability analysis techniques and results are described. Analyses results have indicated that, in order to maintain steep over-all slopes in the final pit, a buttress of intact rock shoud be incorporated into the lower section of the slope until late in mine life. The effect of the buttress is to flatten the slope and reduce the slope height thereby improving slope stability. The mining plans would be such that the buttress would be mined out during the last four months of mining when the consequences of instability would be least severe.IntroductionThe concept of using a buttress to stabilize slopes has been used in mining and civil engineering construction in may locations (Richards and Stimpson, 1977). Most buttresses involve placement of coarse rock fill timber cribs or other material as a load at the toe of an already unstable slope to provide forces which resist failure by counteracting driving forces and increasing the length and strength of the failure path.This paper describes the geotechnical and mine planning aspects of incorporating a buttress of intact rock in the design of the south wall of Cassiar Mine. The effect of an intact rock buttress is to flatten the slope and reduce the slope height, thereby improving slope stability. No actual construction is required other than normal excavation of the slope. The ""mine plans would be such that the buttress would be mined out at the end of mine life when the impact of instability would be less severe and additional ore might possibly be recovered from the slopes. Mining of the buttress could induce instability at the very end of mine life at a time when maximum ore extraction has been achieved."

Jan 1, 1986

By M. A. Bérubé

Le but principal de cette étude était de vérifier certaines hypothèses de nature minéralogique susceptibles d'expliquer en tout ou en partie les variations importantes observées au concentrateur no 1 de Mines Gaspé quant aux performances du circuit B de broyage et de flottation. A cette fin, nous avons examiné six séries d'échantillons prélevés lors d'une campagne de mesures effectuée au cours de l'été 1980. Ainsi, la capacité du circuit de broyage semble dépendre principalement devariation s dans les caractéristiques minéralogiqu es et texturales du minerai, par exemple du rapport grenat/quartz, le grenat ayant une influence néfaste sur le rendement de cette étape, contrairement au quartz . Quant au processus de concentration, la fraction du cuivre sous f orme de minéraux difficilement récupérés par flottation, en particulier des carbonates de cuivre, varie de façon significative dans le minerai, et cela peut certes expliquer en partie des récupérations parfois plus basses. Malgré ces variations important es de la composition minéralogique globale du minerai et de sa broyabilité, le degréde libération des sulfures de cuivre dans le produit de broyage dépend presque seulement de la granulométrie de ce produit. Afin de garantir des performances égales à l'étape de concentration, il est fortement suggéré de contrôler cette granulométrie à un niveau constant.

Jan 1, 1984

By Andrew Popko

Introducing EnCana ?? A leading North American Oil and Gas company ?? Focused on natural gas and oil sands development in 12 key resource play areas across North America ?? In 2007, over 4300 wells drilled, producing about Enterprise value of approximately $50 billion ?? Invest between $5.8 Billion in 2007 ?? Over 7500 employees ?? Headquarters ? Calgary, AB

May 1, 2008

By Patrick J. Williams

Outline -An Australian View On: ?IOCG defining features and occurrence ?Variable exploration characteristics ?Extracting value (gold metallurgy) ?Recent exploration experience(case study)

Apr 1, 2005

By Nigel J. Cook

"Detailed mineralogical examination of gold-bearing rocks, ores, concentrates and other samples should be considered an integral part of any study of a deposit for which exploitation is being planned. Adequate mineralogical study, although time consuming and often costly, can significantly improve understanding of the mineralization, can help to optimize the results of any metallurgical testing and can be of great value in case of potential trouble-shooting. The advantages and disadvantages of various examination techniques are discussed with reference to a number oj mineralogical studies oj Canadian gold-bearing samples.IntroductionVarious authors, notably Gasparrini (1983), Harris (1989) and Henley (1990), have stressed that mineralogical study of gold ores is critical to successful and efficient beneficiation. Only in cases where diagnostic cyanide leach testing is successful can detailed mineralogical examination be disregarded. Such examination of gold-bearing rocks and metallurgical products is all too often neglected because the methods involved are believed to be time-consuming, costly, and may carry a considerable degree of inaccuracy. Commonly, bulk metallurgical testing is, carried out without prior or concurrent mineralogical examination, causing the results of the testwork to be difficult to interpret, or in some cases, misleading. This, in turn, may lead to> significant delays to the project at the feasibility stage or mean that understanding of the sample is limited, preventing the introduction of prudent modifications at a later stage if problems arise. Mineralogical studies may guide the successful implementation of a metallurgical test program."

Jan 1, 1990

By Bill Dupley

We believe that the inability of employees to effectively manage information has reached an epidemic problem throughout the corporate world. ? All the available knowledge in the world is accelerating at a phenomenal rate. ? The whole world's codified knowledge base (all historical information in library books and electronic files) doubled every 30 years in the early 20th century. ? By the 1970s, the world's knowledge base doubled every seven years. ? Information researchers predict that by the year 2010, all the world's codified knowledge will double every 11 hours.

May 1, 2003

By P. Mottahed, E. K. S. Passaris, J. Q. Ran

"The jointed roof of underground mine openings in stratified rock can be analyzed in terms of a voussoir beam. Because of the essential indeterminacy of the structure, previous attempts of theoretically solving the equilibrium equation have been unsuccessful. Numericalanalysisby the finite element method taking the geometrical and joint non-linearity into consideration combined with the experimental method has been adopted to study the performance isopara of the voussoir beam. Deformation and failure mechanism is analyzed in relation to the failure modes. Equations are proposed to estimate the elastic buckling strength and the crushing strength of the voussoir beam and to verify the failure mode of shear sliding. For application of the mechanism of the voussoir beam in mining operations, methods are described to predict the stability of a jointed roof and to design the dimensions of mining openings.IntroductionThe roof stability of an underground mine opening has direct effects on the selection of support methods, opening dimensions and, more importantly, on the safety of mining personnel. The prediction of the roof stability can be of importance in the design of a mining method and in mining operations. The jointed roof of mine openings in stratified rock can be stable under transverse load depending on the roof geometry and properties of the roof material and joints. The stability of this type of roof can be analyzed in terms of a voussoir beam which was introduced by Evans (1941) to study the strength of underground strata. Brady and Brown (1985) analyzed the voussoir beam and suggested that the mechanism of the voussoir beam could be used in the design of underground mine openings in stratified rock instead of the traditional continuous beam theory."

Jan 1, 1993

By Steve Forgeron, Brendan MacKenzie, Kevin MacPherson

"The geological composition of strata immediately adjacent to coal seams has a significant effect on the safe and efficient extraction of coal from underground mines of the Sydney coalfield. Geological features such as paleo-sandstone river channels, seam splits, floor rolls, paleo-soils and stone-filled rupture features can rapidly alter the competency of immediate roof and floor strata, significantly reduce the height of the coal seam, cause rapid variations in seam gradient and influence the in situ and run-of-mine quality of the coal.The impact of these features on the over-all mining operation can be significantly reduced if mine management can be for-warned of their impending occurrence. Using the information acquired from boreholes, geological mapping, x-ray diffraction analyses, microscopic studies, geophysical logs and seismic surveys, sedimentary models have been constructed which enable the mine geologist to predict, with increasing accuracy, the future occurrence of deleterious geological features ahead of the working face."

Jan 1, 1986

By P .. D. Vaillancourt, D. F. Sangster

Several occurrences of disseminated galena, including a former producing mine, are found in Pennsylvanian fluviatile sandstone of the Salmon River Basin, Cape Breton Island, Nova Scotia. Detailed study of the distribution of these occurrences has revealed that highest galena concentrations are found in sandstone overlying channel-shaped depressions in felsic basement rocks. These buried depressions, in turn, correlate in position with modern streams in areas of basement exposure. This correspondence suggests that the latter are at least partially controlled by an exhumed Pennsylvanian topography. If this is correct, then several other streams in the area, lying on basement, may be used to locate possible undiscovered lead deposits in sandstones of the Salmon River Basin.

Jan 1, 1990

By Young C. Kim

A proper economic analysis of pit slope design must reflect the trade-off between the benefits and the increased risk of slope failure inherent in steeper slope angles. However, no formal framework for a proper analysis has existed to date. This paper summarizes the material contained in the Design Chapter Supplement (5-3) of the Pit Slope Manual. The supplement describes the results of the research effort in which a formal economic analysis framework was developed and tested through a case study. The case study results have demonstrated the practicality of the developed procedure and the availability of required data under "real-life" conditions.

Jan 1, 1979

By Ö Yilmaz

In this study, the behaviour of rock mass subjected to blasting load is investigated using three dimensional finite difference numerical modelling. In the analyses, Mohr-Coulomb failure criterion has been used for the characterisation of the rock mass strength. Stresses acting on the borehole boundary have been simulated by an exponential function which reaches its maximum within a short time and then falls to zero value in a considerable time period. The strain rate effect on the mechanical properties of rock material has also been taken into account in the analyses. Four different explosive-rock mass combinations have been studied to investigate blast induced damage zone. It has been observed that proposed equation for the dynamic compressive strength of rock material fits very well to general suggestions. Results have shown that blast damage analysis model recommended with this study is successful.

Aug 1, 2013

By K. Poorhaydari, B. M. Patchett, D. G. Ivey

In this paper, some applications of carbon extraction replicas, as samples for transmission electron microscopy (TEM), are discussed. Modern high strength microalloyed (HSMA) steels, used as structural or pipeline materials, have very small grains with substructures. Replicas used in TEM can resolve the grain boundaries and can be used for grain size measurements in cases where the small size of the grains pushes the resolution of conventional optical microscopes. The grain size variations obtained from replicas correlated very well with mechanical property variations, indicated by hardness, in the fine-grained heat-affected zone and base metal of some welded HSMA steels. Replicas are also very suitable samples for precipitate examination with analytical TEM. Advantages and limitations of the application of replicas, as well as some corrections for the estimation of the volume fraction of fine precipitates, are discussed.

Jan 1, 2005

By Jorgen Elbrond, Yve Lizotte

"A mathematical procedure for determining the underground mining level layout which minimizes the total costs of excavation and haulage is described. This procedure has the advantage over previous graphical procedures of being easily amenable to microcomputers. The paper demonstrates through examples how the procedure can be applied to minimizing discounted costs of level layout as well as providing the optimal location of a production shaft.IntroductionIn recent years there have been numerous publications in mining journals concerning the minimization of mine haulage costs. With the rapid escalation of energy costs during the last decade it is not surprising that several studies applying queuing theory, simulation and mathematical programming to mining related transportation problems have been successfully undertaken. Because of the increasing availability of various sizes of computers these techniques have gained considerable popularity as evidenced by the numerous commercial packages presently being marketed.The publications concerned with haulage cost minimization are generally concluded along the lines of ' ... haulage costs at production rate x will be minimized by assigning y units to location z...'. Details about the route followed and whether it guarantees a minimization of costs are seldom considered. Route data has to date been manually resolved and used for input to developed programs. It would appear that no program has been developed to date which simultaneously minimizes costs by both fleet assignment and routing network resolution.Another important factor in transportation problems is the investment cost associated with the routes; road construction costs or, in the case of underground levels, drift excavation costs. Except for special cases the transport network which minimizes haulage costs only will not provide a minimum excavation cost solution.Zarnbo(1) illustrates by graphical and mathematical procedures how central 'facilities' can be located to simultaneously minimize investment in the transport network and haulage costs. Unfortunately these procedures and others recently applied to mine haulage problems do not provide solutions to the generalized problem. Also because these procedures are geared to graphical solutions and hand computations whereby certain possibilities can be 'visually' eliminated, they can be tedious to program and present storage capacity constraints with current microcomputers."

Jan 1, 1985

By Fadi Layyous Gedeon, David Hatton, Solomon Mogashoa, Tuhin Banerjee, Faisal Aljohani

The adoption of innovative technologies in mineral processing often raises concerns about complexity and integration. However, Woodgrove’s Direct Flotation Reactor (DFR) technology at Barrick’s Jabal Sayid copper concentrator provides a different perspective. This paper outlines the smooth integration of DFR technology from piloting to full-scale commissioning, showcasing how easily the cells were brought online. Installed in a cleaner scalper role, DFR cells at Jabal Sayid upgrade re-ground rougher concentrate to final concentrate in one stage. Despite processing challenging ore, the DFR cells delivered concentrate grades that consistently exceeded expectations. The commissioning process was straightforward with minimal hurdles, highlighting the technology's user-friendly nature. This paper advocates for a shift in perceptions about new technologies in mineral processing. The success of DFR technology at Jabal Sayid demonstrates that “different” doesn’t mean “difficult.” By focusing on ease of commissioning and operational integration, innovative solutions can enhance processes, improving efficiency and productivity in the mining industry.

May 4, 2025

By Roger J. Goodman

"Major industrial restructuring, which started to manifest itself in the mature economies of the Western World and Japan in the 1970s, will accelerate in the 1980s and 1990s. Conventional heavy manufacturing industries will continue to lose ground to lighter processing/assembly operations and the new wave of high technology, information and service sectors. The decline in heavy manufacturing has severely impacted on the steel industries of Western Europe, the U.S.A . and Japan.World trade in metallurgical coal has shifted correspondingly, with declining demand in the mature developed countries being only partially offset by large increases in the steel intensity of the newly-industrialized countries (NICs) of the Far East, Latin America and, to a more limited extent, the Middle East and Africa. These trends will be accentuated in future years with direct implications for the distribution of metallurgical coal trade. This paper discusses, in quantitative terms, such changes in the 1980s and 1990s, and examines the implications for, and impacts on, Canadian metallurgical coal exporters.IntroductionThe twenty-year period from the early 1950 s to the early 1970s was characterized by inexorable growth in consumer demand and industrial expansion in most of the advanced countries of the western world. Long- term forecasting during this period typically used linear extrapolation techniques which , despite their simplicity, invariably ended up predicting future demand and production level s with uncanny accuracy. Times have changed!The last decade has been characterized by a n abysmal failure of our economies to respond to simple long-term, linear growth patterns. We appear to have entered a new world in transition, where we can observe a wave of dying or sunset industries reluctantly being submerged by a wave of emerging or sunrise industries.This paper is aimed a t examining the evidence for long-term industrial restructuring trend s. For want of a better word, these so -called, megatrends are then used to predict future demand level s and spatial distribution of steel development and , hence, metallurgical coal trade. It is tempting to correlate the decline in economic activity in the western world with the first Organization of Petroleum Exporting Countries' (OPEC) crisis of 1973. This crisis was probably no more than the straw that broke the camel's back, as the megatrends and embryo s of major industrial restructuring were already evident. Today these megatrends are merely more apparent and transparent than they were ten years ago.While the concept of industrial restructuring is the new economic buzz word, the process was at work, to a lesser degree even throughout the period of strong economic growth of the post-Second World War boom. Many people still remain convinced that our present-day sluggish economy is just part o f the typical , though rather more prolonged, recessionary cycle. Yet, we have always been part of a dynamic economic system and industry throughout history has been the subject of a continuous process of evolution, restructuring and reconstitution . Now the time is ripe to examine the evidence for such restructuring in order to develop coherent policies of adjustment in this transition from one industrial regime to another."

Jan 1, 1985

By L. I. Kiss, S. Perron, S. Poncsák, A. Perron

Aluminium industry has an increasing interest in the diminution of the energy consumption of the Hall-Heroult process by the reduction of the anode bottom covering with gas. Electrically isolating carbon-dioxide bubbles, produced at the anode, increase the ohmic resistance of the cell. As the gas production rate is determined by the applied current density, anode covering can be decreased only by a faster evacuation of the gas from the inter-electrode space. Among others, the inclination and curvature of the anode bottom promotes the release of the bubbles and thus decreases the mean value of the covering. Indeed, anode, insert in the molten cryolite bath has a square shape with horizontal bottom. However, inhomogeneous anode consumption, electro-erosion, bath circulation and the inclination of the bath-metal interface modify this shape gradually during electrolysis. Anode bottoms become inclined with rounded comers. This concentrates the gas generation to the center zone of the anode. As the bubble layer cannot be observed directly because of the hostile environment and the opacity of the bath, real scale air-water systems are used to study the impact of the anode geometry on the anode covering and the bubble induced flow. However, the physical properties of such a system are different than that we can found in the real cells. A simulator using the Lagrangian description of the bubble layer has been built and presented in earlier papers. This tool was used to investigate the effect of the anode inclination on gas covering and bath velocity, for both C02-cryolite and air-water system. Results obtained for the second system were compared to experimental data .

Jan 1, 2006