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By B. Das

"Computers have been used extensively in the mineral industry in exploration, reserves calculation, mining technology, mineral processing, etc. With respect to coal mining, there are also various applications for evaluating rock slope stability of open pits, design of open pits, underground operations, mine ventilation, ground control, data processing and management information, operations control and certain technological applications. Mine ventilation appears to be the field in underground coal mining touched on most; on the other hand, underground coal mining methods evaluation is represented only sparingly.It is therefore essential to review the status of the computer in underground coal mining methods evaluation in order to define its scope for further application. The paper discusses the roles of the mining engineer, programmer, computer operator and analyst as well as that of the computer. The important parameters will be identified and discussed along with their application for different underground coal mining methods, with their individual unit processes. Mainly, longwall face operations have been covered. Although many models have been of academic interest, they can be considered as important steps in a transition stage which will be followed by more practical applications for computers for underground coal mining method evaluations in the future. This calls for a coordinated effort from all concerned."

Jan 1, 1981

By A. A. Ruitenberg, C. J. Morrissy

"The Lake George antimony deposit comprises a system of stibnite-bearing quartz veins that cut Silurian greywacke and slate. The stibnite-bearing ore zone is in part enveloped by a uraniferous zone.The ore-bearing quartz vein system occupies an easterly striking, gently north-dipping fracture system that cuts across north-northeasterly trending gently southwest-plunging, tight Acadian (early Middle Devonian) folds. This vein system continues at depth into a siliceous skarn zone intruded by altered granite porphyry dykes, which constitute probably a late phase of the Hawkshaw granitoid intrusion to the north.Most of the ore occurs in a northeast-plunging, trough shaped vein structure that formed where the vein system (gently north-dipping) intersects the axial surf ace zone (steeply northwest-dipping) of an Acadian synform. The trough shaped structure resulted from deflection of the fracture zone (containing the vein system) by competent beds.Emplacement of the quartz-stibnite veins was preceded by, and is in part penecontemporaneous with, the formation ofa micaceous-argillaceous alteration halo, which in turn intersects a patchy biotite alteration zone.The hypabyssal intrusions associated with the Lake George deposit probably represent a late phase (early Carboniferousr) of the nearby Hawkshaw intrusive granitoid complex. IntroductionThe Lake George Antimony Mine is situated 40 km southwest of Fredericton and 2.5 kin north of Lake George, New Brunswick (Fig. 1). The mine is owned by Consolidated Durham Mines and Resources Ltd.Shaw (1940) described the early history and development of the mine. In subsequent years, available drill cores were relogged by several geologists. Much new information became available when an extensive diamond drilling program (Kidd , 1970) was started by Consolidated Durham Mines and Resources Ltd. in 1970. A study of the geology and economic potential of the deposit was made by Glover (1973). Abbott and Watson (1975) made a study of the ore mineralogy. Available drill cores were relogged and a preliminary study of the fracture system in the mine was made by G.A. Pierce and A.A. Ruitenberg during 1976. Outcrops in the area sur rounding the mine are extremely sparse.Between 1976 and 1979 the present authors made a detailed study of the mine workings, available drill core and regional structure in the vicinity of the mine, with results set forth in this paper. The regional geologic setting of the deposit, the geometry and structural controls of the ore zones, and the mineral zonation and rock alteration are emphasized."

Jan 1, 1980

By C. O. Aksoy

"Pillars left to ensure the stability of major underground coal mine infrastructure (shafts, drifts) often contain substantial quantities of coal. Recovery of this coal is an efficient use of the resource, but often presents safety hazards; pillar extraction destabilizes the protected structure, and can make its use dangerous. In this study, the stability of an active shaft at an underground coal mine situated in the Soma- Manisa region of Turkey was investigated during the recovery of the coal in the shaft safety pillar.A proprietary three-dimensional finite element analysis model (ANSYS) was used. An elastic-plastic material model utilizing the Drucker-Prager failure criterion was employed. The three-dimensional Drucker-Prager formulation was preferred over the two-dimensional Mohr-Coulomb model because it was thought to more accurately represent the strain hardening behaviour shown by most geologic materials.Stresses and deformations formed around the shaft support were estimated using the model and the results were verified by in situ observations. The results show that stress distributions around the shaft and the subsidence of the shaft support are influenced by the location location of the extraction front and the break angle of the overlying material."

Jan 1, 2005

By Roger J. Berdusco

Kaiser Resources Ltd. owns and operates a 5-million-tonper- year open-pit and hydraulic coal mine near Sparwood in southeastern British Columbia. Since 1969, Kaiser has maintained a field-scale reclamation program dedicated to the reclamation of disturbances associated with past and present mining and exploration activities . Since that time, over 1400 acres have been treated using modified forestry and agricultural techniques with encouraging results.

Jan 1, 1978

By J. H. Walsh

IN THE DEVELOPMENT of procedures for the separation of minerals, the choice of reagents for flotation is frequently determined by the extent to which a given mineral is wettable by water. Measurements of the contact angle of an air bubble on wet mineral surfaces are often used in the laboratory to estimate the wettability of the surface. For the results of these measurements to be reproducible, the surface of the mineral must be polished to a mirror-like smoothness and must be free from oily contamination. Elaborate procedures for preparing mineral surfaces have been developed by Wark ( 1) and Taggart (2), and these procedures have been generally accepted as adequate for their purpose. The polishing techniques, how-ever, have certain inherent disadvantages which make it impossible to assess the effects of polishing, entrained abrasive, and adsorbed gases on the wettability of the mineral surface.

Jan 1, 1957

By R. L. Brown

The burning sulphide ores in the Sullivan Mine generate sulphur dioxide gases. This paper is concerned with a description of the environmental impact of SO2 on air quality in the mine and on the surface in the vicinity of the mine. As a result of surface caving, SO2 has been able to vent to surface and winds have carried it into one residential area of Kimberley. Monitoring practices are described.

Jan 1, 1977

By Debasis Deb, Ankur Narang, G. P. Raja Sekhar, Kamal C. Das

"The stability of underground structures made (especially) in jointed rock mass is of the utmost important to designers, engineers and operators. Rock bolting is generally being practised to reinforce excavation walls and roofs by minimizing the movement of rock joints. This study proposes a new analytical model for the prediction of displacements, axial load and shear stress of a fully grouted rock bolt intersected by single or multiple rock joint(s). The governing equations for rock bolt are derived based on the assumption that shear force generated by slippage along the bolt-grout interface has a linear relationship with respect to the relative displacement at the interface. The proposed model is novel compared to the existing literature in the sense that it accounts for rock kinematics as an enriched sum of a continuous part (elastic) and a discontunous (jump) part due to the presence of joint planes. The complete solution of the bolt displacement, axial load and shear stress is derived as a function of the rock displacements, and, it comprises of Heaviside and/or Dirac delta functions in the solution space due to the jump at the intersection point(s) of bolt(s) and joint(s).Our novel solution is able to predict the elastic behavior of a grouted bolt, subjected to opening of the joint planes in pull-out test and also in excavated tunnel. These two cases also serve as benchmarks for grouted rock bolts with multiple joints and can be used for validation of numerical and experimental models. Further, the solution is applied to analyze the behaviour of grouted rock bolt as well as cable bolt installed in circular tunnel, with variations in rock joint(s) opening displacement, shear stiffness in the boltgrout interface and locations of the joint planes. Results indicate that for a specified grout stiffness, the maximum axial load developed in the bolt for discontinuous distribution of rock mass displacement is significantly higher than that of the continuous distribution of rock displacement. This paper provides an analytical interpretation of bolt beaviour considering multiple joint planes with variable joint opening displacements. The results obtained via the analytical method are in line with the corresponding investigation done by other authors. Thus, our analytical treatment can be used to understand bolt behaviour in realistic situations."

Jan 1, 2015

By D. R. Wright

"The modest thermal efficiency of the steam turbine cycle essentially determines the heat required and, therefore, the coal consumption and ash production of pulverized-coal-fired powerplants. This paper emphasizes how some properties of coal and its ash can crucially affect the operation of a steam generator and its flue gas cleaning equipment. A brief reference to some siting factors and economics reaffirms the all-pervasive influence of the properties of coal and ash and establishes the importance of a firm supply of cooling water. The economics of scale remains a compelling factor in selecting the size of units, despite disappointing performances by some of the larger units. Environmental considerations suggest that smaller units still have a role to play. IntroductionCoal fuelled one industrial and economic revolution, beginning two hundred year s ago . It was the precursor of competing fuels, notably natural gas, oil and uranium, which eclipsed it in terms of convenience and rate of growth.The turmoil that now exists because of rapidly dwindling supplies of no-longer-cheap oil and the concerns about nuclear energy-justified or unjustified-exacerbated by an operating incident at the Three Mile Island Nuclear Powerplant, prompt speculation for a resurgence of coal, especially where it cangenerate electricity to replace energy from imported oil.The world's reserves of coal are not inexhaustible, although they are ample for several decades. Of greater import is the fact that the world's coal reserve s are more widely distributed than its oil reserves, and they appear less convenient as instruments of economic and political persuasion by opportunist powers. The crux is whether or not the world will accept all that a massive, if temporary, return to coal implies.Combustion of pulverized coal in steam generators to pro duce electricity is a 50-year-old, well-understood technique; it is undergoing continuous refinement to meet evolving environmental and economic criteria and is not found wanting. It is certainly the only technique available and technologically advanced enough to replace oil immediately on a large scale. Although it may take a decade to bring a new coal-fired powerplant into service, this delay is a reflection on nontechnical and administrative processes. Capital and operating costs of coal-fired powerplants are significant and subject to inflation, but, because of the accumulated experience in this field, the ability to control costs is better than for those energy processes which are less mature or still in embryo form. More exotic, soft energy systems, touted as the panacea for world energy problems, have still to prove themselves on the scale they are needed and under the stringent climatic and operating conditions coal-fired powerplants have already mastered."

Jan 1, 1980

By Jean-Marc Simard, Richard Genest

"La mine Agnico-Eagle, localisée près de Joutel, a été découverte en 1962 par le forage d'anomalies électromagnétiques. Exploitée à partir de 1974, elle a déjà produit près de 30 tonnes d’or à partir de 2 puits, le puits Eagle et le puits Telbel, distants de 1,3 km.Le gisement est situé entre le sommet du complexe volcanique de Joutel, à dominante felsique, et la base de l'ensemble sédimentaire de la rivière Harricana. Ces deux unités ont une extension régionale; elles sont orientées NW-SE avec une polarité NE et des pendages subverticaux. Une faille majeure, la faille Harricana, passe de façon subconcordante au contact de ces deux ensembles.La minéralisation aurifère, de 2 à 5 m d’épaisseur moyenne, est liée a une zone carbonatée, comprise entre des tufs felsiques, argilites et sédiments chimiques (éponte inferieure) et des argilites carbonatées (éponte supérieure). Le minerai est constitué habituellement de 20% de fine pyrite disséminée. L’or est en fines particules associées directement à ces grains de pyrite de texture cataclastique.Deux modelés ont été for mules jusqu' a présent pour expliquer la genèse du gisement: une thèse syngenetique (Barnett et a/.1982) et une thèse épigénétique (Wyman et al. 1986). Cette dernière apparalt comme la plus probable du fait de la présence de la minéralisation dans les zones cisaillées a carbonates secondaires et pyrite cataclastique."

Jan 1, 1990

By Dennis V. Woods, J. Duncan Crone

"In order to determine its capabilities and to aid in the interpretation of fie ld results, a scale model study and field tests were carried out on the Crone borehole pulse electromagnetic (PEM) system. The model results indicate that if a borehole passes in the vicinity of a tabular conductive body, the system will not only detect the presence of the body, but will also return information as to its conductivity-thickness product, size, altitude and position.The effect of variation of these electromagnetic and geometric factors on the shape of the response curve from a borehole PEM survey is displayed by a number of suites of scale-model response curves. These model curves can be used directly as type curves in the interpretation of field results. Field tests of a prototype PEM system provide a check on the scale-model results and also summarize the procedure of interpreting field data using the model type curves.The borehole pulse EM system can be effectively used as a follow-up geophysical instrument for locating and delineating known conductive bodies. It can also be profitably utilized as a primary geophysical exploration tool in areas of deep mineralization below the depth limit of conventional airborne and ground geophysical systems. The probed area of a diamond drill hole in these cases is increased from a 1- inch drill core to a zone extending hundreds of feet from the hole."

Jan 1, 1980

By Ferrin Prince

New Gold?s New Afton mine is an 11,000 tonne per day block caving mine, located 8 km west of the city of Kamloops, British Columbia. The reserve is estimated at 52.5Mt with grades of 0.65 g/t Au and 0.93% Cu. Block caving requires a considerable amount of infrastructure development before production can begin. Each excavation had its own challenges, often further complicated by interactions with the caving stresses and fault structures. The main areas of interest were: the production crusher complex, the surface to underground infrastructure, and the footprint interaction with the faults. The ore zone at New Afton is bounded by two very weak fault zones, with large fault affected areas and associated splays. The resulting rock mass rating (RMR) is 35-50, with some areas significantly weaker due to clay infill. These conditions created a unique and decidedly difficult environment in which to develop New Afton?s infrastructure. Despite these difficulties, the mine began production on schedule in July 2012. The main production crusher for the mine is a gyratory crusher that allows for direct truck dumping, with a smaller jaw crusher in series to facilitate the initial development and production. The crusher chamber was redesigned several times to minimize the chamber volume, resulting in a 40% decrease in volume without losing functionality. After drilling and geotechnical testing, the location of the crusher was changed to eliminate the threat of fault affected ground in the area; the entire complex moved a short time before mining began on the chamber. The mining techniques used enabled tight control of the crusher pocket excavation, while also allowing for the timely completion of the chamber. The locations of the surface to underground infrastructure were tightly constrained by geology, surface infrastructure, and an existing open pit. The VR5 raise was drilled and abandoned part way through the reaming process when the drill string became stuck in fault gouge material. It was relocated and successfully completed. The VR7 raise hit a region of poor rock strength and deviated more than 11 m. Poor ground conditions caused a 130m section of the raise walls to fail. An innovative rehabilitation program was undertaken to re-establish the raise for ventilation. A surface to underground slick line was also installed to ease the material movement underground. A layout of the Extraction level was changed from herring bone to straight through drawpoints that resulted in a net reduction of 1.3 km of development. The Apex level was added to aid in the breakage over the major apex pillar and allow for geological mapping. A portion of the caving footprint is located within the footwall fault. The low strength, high clay content, and small joint spacing of the material resulted in blast-hole cut-off and drift deformation. Drift rehabilitation was a key factor in the successful development of the cave footprint. Innovative drilling and loading techniques were used to keep the holes open and to impede movement along the joint structures.

Aug 1, 2013

By Brian Mattie

Overview ?Overview of the mining area ?Description of the mining phases ?Risk assessment ?Design criteria and description for freeze drifts ?Freeze wall design ?Raisebore mining Four Main Phases: 1.Development of freeze drifts on the 520 and 590 levels 2.Freeze drilling and ground freezing to isolate the Zone 4 North ore body from water bearing sandstone. 3.Develop raisebore and extraction chambers including access drifts and ramps under freeze protection. 4.Start raisebore production mining of the Zone 4 North area.

Nov 1, 2011

By Jorgen Elbrond, Yve Lizotte

"A mine evaluation method based on the use of a computer program that models mining with an open-ended dynamic program is presented in this paper. It is demonstrated with an example how the method is applied, how some of the decision variables are related in the particular industrial environment and how these decision variables affect the economic benefits of mining.IntroductionTwo distinguishing characteristics make mining a particular industrial environment: exhaustible resources of a given ore deposit and heterogeneousness of the ore grade spatial distribution in the ore deposit. These characteristics, inflation, uncertainty and cyclical price variations which greatly affect estimated cash flows also contribute in rendering difficult the evaluation of the economic outcome of mining at the preliminary planning stage.Decision variables and their ranges are associated with the mine plan; basically, they include choices of the mine's nominal capacity (mining and milling), the sequencing of mining through the deposit, the ranges of possible production rates and cutoff grades, and the stockpiling policies. The mine's nominal capacity must be decided at the planning stage, but this capacity choice must take into account flexibility to modify other decision variables as mining commences and uncertainty resolves.Although it is generally accepted in discounted cash flow analysis that the sequence of mining must proceed from the richest to the lowest-grade stopes (with correspondingly ajusted cutoff grades), this may not produce optimum benefits when cyclical price variations are considered.Mining rates and cutoff grades can also be adjusted to changing economic conditions, taking into account the limited resources of the ore deposit. Thus, when prices are thought to be in the trough of a cycle, production can decrease to preserve ore for expected greater future profits. When prices rise, mining rates can increase possibly even over the mine's nominal capacity. In both cases, the machinery's effectiveness shall not be-optimally utilized; this will be reflected particularly by the variations in the concentrator's metal recovery and the concentrate grade output."

Jan 1, 1982

By Qian Liu

Mining in highly stressed ground conditions has been an increasing challenge at the Brunswick Mine. Two large regional pillars were established on the 1000 m Level to support the ground for safe extraction of the surrounding ore. The South Regional Pillar contains about 5 million tonnes of ore and the North Regional Pillar has about 3 million tonnes of ore. In the fall of 2000, mining activities were suspended following a series of ground movements around the South Regional Pillar along weak geological structures. After extensive geotechnical investigations, a decision was made to carry out a mass destress blast in the West Ore Zone (WOZ) to cut the principal stress across an area of 135 m along strike and 86 m high. At the end of July 2001, the WOZ mass blast was successfully initiated. Following this success the mine decided to take a similar approach to destressing the North Regional Pillar (NRP). The final mass blast was taken in early February 2003. Advanced blasting technologies, including state of the art electronic detonators and blast simulation, played an important role in achieving the successful blasts. The high precision of delay timing and long delay duration of the electronic detonators ensured accurate and reliable initiations of over 800 blastholes in the WOZ mass blast. Orica?s DMC_Blast (Distinct Motion Code) simulation code was used to study different blasting blocks for the desired timing in the initiation sequence. This paper describes the process of applying electronic detonators in complex blasts, and discusses how blast simulation results were interpreted to guide engineering design of the mass blasts.

May 1, 2003

By Stephen G. Hardcastle, Michel G. Grenier

"Safety and health issues are and have been in the last decade a very high priority item with all parties involved in the Canadian mining industry. As a result of this high level of concern for workers' safety and health, Canadian mines are at the leading edge of environmental control technology. For the most part, the occurrence of pollutants in mines is unavoidable. Dust from mining operations, airborne radiation, gases and heat from the strata as well as gases and particulate from diesel engine emissions will undoubtedly be found to some level in most Canadian mines. A lot of work remains to be done, however, in order to bring all Canadian mines at the same level of proficiency when it comes to safety and health. Also, more work is needed in order to maintain our status as world leaders in this field.CANMET's Mining Research Laboratories (MRL) in Elliot Lake and Bells Corners, Ontario, with the cooperation of the mining industry, have contributed to improving environmental conditions in underground and surface mining and milling operations. The extent of collaboration and efforts vary widely from long-term, multi-million dollar projects between several interested parties to smaller projects involving one laboratory and a single mining operation. This paper gives examples of such collaborative efforts and potential future directions as they apply to: mine ventilation analysis using tracer gas techniques, optimization of mine ventilation network efficiency using real-time monitoring and controlled recirculation (heat saving), respirable dust and radiation sampling and control techniques, diesel emission control using regenerative ceramic filters and, finally, the control of sulphide dust explosions and resulting sulphur dioxide production."

Jan 1, 1990

By Y. Huang

Corrosion of GaAs in aqueous electrolytes is a major limitation in implementing GaAs-based photoelectrochemical solar energy conversion systems, In this work, the corrosion behavior was investigated by electrochemical methods and surface analysis approaches, in both H2SO4 and NH3?H2O solutions, Open-circuit measurements showed that the cleaned GaAs surface was very sensitive to water/air, Impedance measurements for n-GaAs showed that an inductive loop only appeared at a high corrosion rate because a reaction intermediate is the oxidant for a further decomposition step in combination with chemical reaction with water, The results suggest that the same corrosion/decomposition mechanism occurred on n-GaAs in the two solutions, When the surface-hole concentration was low, the hole injection or generation process was the rate-determining step, At large reverse bias on n-GaAs, with high-hole concentration, the corrosion rate was limited by a Faradaic adsorption process, involving an adsorbed intermediate, The different surface compositions after corrosion in the two solutions can be explained by the dissolution of As(0), Further oxidation of As(0) to As(III) in NH3?H2O solution is still slow, as suggested from X-ray photoelectron spectroscopy (XPS) analysis,

Jan 1, 2005

By A. V. Tarasov

There are still a number of copper smelters in the world using the roasting and smelting process flow diagram for treating sulphide raw materials. The technical, economic and environmental performance indicators of such operations are inferior to the respective indicators of advanced processes. First of all with respect to copper and sulphur recovery: 95% and 75% as compared with 98% and over 90%, respectively. Based on the studies of the single-stage smelting process to produce white metal and blister copper conducted during recent years an analysis of the feasibility of roastingsmelting technology improvement was carried out in the Gintsvetmet Institute to substantially increase the copper and sulphur recoveries. On the basis of this analysis, it was proposed to modernize the technology and equipment within the framework of the existing process flow-sheet. The proposed modernization implies an increase in the roasting temperature; higher desulphurization degree in the process of roasting; a number of modifications in the roaster design depending on the particular conditions of a given operation; addition of lime flux to the feed charge to roasting; and transition to combined calcium-silicate smelting slags. The metallurgical and energy computations made have indicated that the proposed modifications of the technology will improve the copper and sulphur recovery up to 98% and 90%, respectively. The required capital investments have been estimated using as an example a particular copper smelter, the payback period determined taking into consideration additional output, fuel saving and a reduction in fines for sulphur emissions. For comparison, the capital cost of a smelter modernization is given for change-over to basically new autogenous Ausmelt, Outokumpu and V anyukov smelting technologies.

Jan 1, 2007

By Ben Sheneider

AT THE Flin Flon plant of the Hudson Bay Mining and Smelting Co., Limited there are two types of multiple hearth furnaces used in the roasting of sulphides. This pa-per will deal primarily with the wedge-type furnace in the roasting of zinc concentrates. The other furnace, the Nichols-Herroshoff type, is used in the copper smelter and is described in the papers given by (1) J. H. Ambrose in 1935 and (2) R. E. Mast and G. H. Kent in 1954. The design and operation of these roasting furnaces at the present time is essentially the same as given in the write-up in 1954. No at-tempt will be made here to describe these furnaces, except to mention that there are five Nichols-Herreshoff multiple-hearth furnaces, four of which are used to roast a dried mixture of copper concentrate, zinc plant residue, and flux, before this material is fed to the reverberatory furnace.

Jan 1, 1961

By M. L. F. Gameiro

The aim of this study was to check the feasibility of non-dispersive solvent extraction to recover copper from ammoniacal solutions using hollow fibres as contactors. Data of mass transfer using the B3-diketone LIX 54 as extractant was obtained. The influence of tube and shell hydrodynamics on the extraction rate of copper was studied. The overall mass transfer coefficient of copper was calculated from the experimental data by performing steady state material balance. Simultaneous extraction and stripping experiments were carried out using different volume ratios of feed phase to stripping phase. The results obtained showed that practically all the copper content was removed from the ammoniacal feed solutions. The recovery of copper reached nearly 100% in several extraction-stripping experiments.

Jan 1, 2007

By T. Saksala

In this paper, the embedded discontinuity approach is applied to finite element modeling of rock fracture. A rate-dependent constitutive model based on the embedded displacement discontinuity theory is developed to describe the mode I, mode II and mixed mode fracture of rock in tension and compression. The bulk material is described as linear elastic until reaching the elastic limit. Beyond this limit, a ratedependent exponential softening law governs the evolution of the embedded displacement jump. The present approach incorporates the rock heterogeneity by random description of the mineral texture of rock. Moreover, the inherent initial microcrack populations of natural rocks are accounted for as randomly oriented embedded discontinuities. Numerical examples demonstrate the model behavior in uniaxial compression and tension. The effect of loading rate and confining pressure is tested as well in 2D numerical simulations. These simulations show that the model captures the main features of rock in confined compression and uniaxial tension. The developed method has the computational efficiency of continuum plasticity models. However, it has an important advantage of accounting for the orientation of introduced microcracks.

Jan 1, 2015