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By R. Bridge

Mining companies are progressively finding themselves having to develop operations for more complex, deeper ore bodies, which require the use of more complicated mining and mineral processing methods. This coupled with the generally increasing trend of higher capital and operational costs have led to a need in the industry for improving ore body knowledge, mining and mineral processing. Geometallurgy is a relatively new concept that can link the three aspects, and when used effectively it is a method that can produce the necessary information for designing and building operations for reliable and optimum performance. Geometallurgy not only involves the integration of geological, mining, and metallurgical fields, but it can also be expanded to include environmental and economic information to produce a block model that can be used to obtain the best outcome in terms of plant response and plant sustainability. The geometallurgical program should not end once the block model has been populated. A detailed geometallurgical approach should be applied to all stages of the operation encompassing sample selection, through to equipment sizing and production forecasting. It can also become a useful optimisation tool thereby allowing the operation to be proactive rather than reactive against changes in the ore characteristics. With the development of metallurgical performance predictors it is possible to quantify how the ore will behave in the process plant in terms of throughput, recoveries, reagent consumption, etc. Therefore, in terms of responsible mining and sustainable resource development, a geometallurgical approach to operations is the logical step for plant development. In this paper we describe the state of the technology with respect to the application of geometallurgical modeling and its utilisation in the fields of design, forecasting and optimisation of mining operations.

Aug 1, 2013

By A. Dolatmoradi

Nanocrystalline structure formations produced by severe plastic deformation in Fe-0.15C with initial ferritic-pearlitic and IF steel with ferritic microstructures have been studied through microstructural observation and microhardness measurements. It was found that the nanocrystalline region first forms near the surface of samples due to localized severe deformation. It was also observed that the nanocrystallization rate of Fe-0.15C and IF steels and the deformed layer thickness in these two materials are different with similar milling conditions. The crystallite size and structural evolution of the samples during milling was studied by employing XRD and SEM.

Jan 1, 2010

By Elizabeth Edwards, Radhakrishnan Mahadevan, Vladimiros G. Papangelakis, Srinath Garg, Kurtis Judd

Mineralogical characterization of the tailings showed the deportment of Ni to be similar in the Vale and Glencore tailings, with 60% of the total Ni locked in pyrrhotite, and the balance 40% associated with pentlandite. The overall Ni dissolution was correlated with the individual dissolution extents of pyrrhotite and pentlandite as functions of four leaching regimes: ‘anoxic acid’ (with and without pH control), ‘oxic acid’ (oxygen sparging), ‘oxic acid’ (air sparging), and ‘oxic ferric’ (air sparging). The results showed that the maximum Ni dissolution was obtained during the pH controlled oxic acid leach with oxygen sparging at pH 1.5, while the anoxic acid leach at pH 1.5 resulted in minimum Ni dissolution (10–15%) from pyrrhotite. An overall Ni mass balance showed that pyrrhotite and pentlandite dissolve simultaneously in the presence of Fe(III) and oxygen, in contrast to the preferential dissolution of pyrrhotite in the absence of Fe(III). Sulphur mass balances revealed that the yield of elemental sulphur is maximized (65%) during the oxic Fe(III) leach at pH 0.6. Furthermore, the kinetics of Ni leaching and elemental sulphur formation from pyrrhotite tailings leached with ferric sulphate between 55–80°C was investigated at constant oxidation-reduction potential. Elemental sulphur yield increased with increasing temperature, but no observable trend could be linked to ferric or ferrous ion concentration.

Jan 1, 2017

By K. V. Gow, F. A. Jerabek

"THE NOVA SCOTIA TECHNICAL COLLEGE has been granting degrees in mining engineering since 1909. The college was established in 1907 to provide the final two years of the undergraduate program in engineering the earlier years of which are given at several small universities scattered around the Atlantic Provinces. Since the beginning of the program, 251 Bachelor of Engineering degrees have been awarded in mining engineering. Although the average class size has been small, increases in enrolment in the past few years have resulted in Nova Scotia Technical College being the second largest mining department in Canada, based on the number of graduates per year. This year 18 students received B.Eng. degrees, and next year 17 will graduate.In 1968, it was necessary to make a decision on whether or not to abandon, for economic reasons, the program in mining engineering. For several years enrolment had been very low and resignations among the mining engineering staff created a situation in which the program could easily have been dropped. However, it was decided to continue mining engineering, as it was the only such program in the Atlantic Provinces. New staff members with many years of practical experience in the mineral industry, not only in Canada but in the U.S.A., South America, Africa and the U.K., joined our department. At the same time the enrolment in mining engineering began to increase significantly."

Jan 1, 1972

By I. Filzwieser, S. Konetschnik, A. Filzwieser, A. Anzinger

Production in copper electrorefining tankhouses mainly depend on two factors: The deposition area, which is a result of the amount of installed cells and cathodes, as well as the current density - the amperage per square meter of deposition area. The present paper shows, that the most economical way of achieving a certain production is to maximize current density by using the METTOP-BRX-Technology - as building and infrastructure can be kept more compact. This industrial proven technology applies a parallel electrolyte flow in each electrolysis cell. In 2011, the first fully industrial applications started up: At the secondary smelter Montanwerke Brixlegg AG, 156 cells are equipped with the METTOP-BRX-Technology; this allows a current density of 390 A/m². Xiangguang Copper Co., Ltd. - a primary smelter and refinery - operates its new tankhouse (720 cells) at 420 A/m²; this stands for an production increase of 50% compared to the same sized ISA tankhouse which is limited to 280 A/m². The first part of the present paper gives a cost comparison between a conventional copper electrorefining tankhouse and a high current density tankhouse when assuming a Greenfield project. The second part describes the cost savings when installing the METTOP-BRXTechnology in an already operating tankhouse.

Jan 1, 2014

By E. Contestabile, T. R. Craig

"This report describes the development and effective use of shaped charges as part of the Elliot Lake Mine Roof Stability Project to remotely remove the heads from roof bolts. With a slight modification, these same shaped charges are being recommended f or use to the Brunswick Mining and Smelting Corporation Limited (Mining Division), to cut steel cable bolts.IntroductionThe Canadian Explosives Research Laboratory (CERL) often receives requests to cooperate in solving problems encountered in private industry or other sectors of the government. CERL is equipped to design and test explosive and pyrotechnic devices and the policy is to treat each case individually.The first case reported evolved from a request from a sister laboratory at Elliot Lake. The intent was to remotely remove the head s of roof bolts as part of a mine roof stability project. The device designed for this use was 1000,70 effective in the laboratory and 80% effective in the mine.The second case reported results from a request from a private mining company knowledgeable of the Elliot Lake Project. Their requirement was to remotely cut cable bolts. This request was first treated as presenting a new problem. The solution, however, proved to be very similar to the former."

Jan 1, 1985

By C. John Sullivan

Is there a relationship among the Sudbury nickel ores, the Cobalt deposits, and the Huronian, Athabascan and North Australian uranium provinces? All are within intracratonic basins, with ore near basal unconformities. There are similarities in the geochemical "fingerprints" pointing to basic igneous rock affiliations. Some show a time relationship to basic igneous activity and to great rift systems. Many basic dykes show radioactivity at their edges. A spatial relationship between the uranium-cobalt-nickel ore at Midwest Lake, Athabasca, and basic igneous rock is reported. These remarks are not meant to imply, necessarily, a direct genetic connection between the basic dykes, etc., and the ore. In some cases, the relationship may be similar to that noted between basic and ultrabasic intrusives and volcanic massive sulphide ore deposits. Crustal thinning in these areas, associated with graben, appears to have favoured volcanic activity, as well as basic intrusives. Probably, the potential of the Huronian should be re thought . Athabascan-type ore may be present . New data on mineralization in Turner Township, Ontario, suggest this. The mineral possibilities of other basins should be reconsidered. It is to be remembered that the Athabascan and Kombolgie basins were neglected for many years. Intracratonic sedimentary-igneous basins contain many of the greatest mineral fields of the world.

Jan 1, 1979

By A. Mykytiuk, I. E. Puddington, W. D. Macleod, F. W. Meadus

"A laboratory-scale continuous procedure for the up-grading of naturally occurring tin ores, based on the principle of spherical agglomeration, is described. High recoveries are indicated. A proposed second stage suggests useful fractionation steps.IntroductionA LABORATORY-SCALE batch process for the upgrading of a tin ore using the principles of spherical agglomeration has already been described (1). This procedure consisted of milling, for about an hour, a precrushed ore with at least 200 per cent water, 0.2 per cent of a reagent such as tall oil (to render the de-sired ore particles hydrophobic) and about 3 per cent of a viscous petroleum oil. The feed material passed an 8-mesh Tyler sieve, and the percentages of re-agents are based on the dry weight of the feed. Du-ring the grinding, the hydrophobic particles transfer into the oil phase to produce coherent semi-solid bodies while the gangue stays preferentially in the aqueous phase. The concentrate can be separated from the gangue easily by a mechanical operation. Using an ore containing about 0.3 -0.5 per cent tin, grades of from 1.5 to 7.0 per cent were obtained by varying the pH of the system. Recoveries fell from about 80 per cent to as low as 50 per cent as the grade in-creased."

Jan 1, 1966

By K. Ohto, B. B. Acihikari, H. Kawakita, M. Gurung, S. Alam

Two kinds of adsorbents were prepared from persimmon tannin extract to investigate their adsorption behavior of metal ions from hydrochloric acid solution; one was prepared by treating with concentrated sulfuric acid while another was prepared by immobilizing functional groups of quaternary amine. The former adsorbed only gold(III) and its maximum adsorption capacities was evaluated as high as 1510 g/kg while the latter adsorbed not only gold(III) but also palladium(II) and platinum(IV), the maximum adsorption capacities of which were evaluated as 820, 89 and 101 g/kg, respectively. For both adsorbents, practical adsorption of base metals was not observed.

Jan 1, 2011

By W. A. Grell

"The oxygen meter has been in use at MacLeod Cockshutt Gold Mines for over a year, At MacLeod about 200 tons per day of reground concentrate containing roughly 10% pyrrhotite and 20% pyrite is cyanided in four 181 x 18' Dorr agitators. A survey by the Department of Mines showed that oxygen content of some of the agitators was rather low. Experience with our oxygen meter indicates that the oxygen content must at times have been too low for good gold dis solution.We have found that in winter, when pulp temperatures drop to about 50° F, oxygen saturation in the agitators is not difficult to maintain. In summer, however, when pulp temperatures rise to 70or 75°F, the oxygen content will drop very readily. It was found that a high oxygen content can be maintained readily if the pulp is sufficiently dilute. Thus at 50° F, a pulp of specific gravity 1. 75 i.e., about 55% solids, will saturate; but at 70 or 75° F, the specific gravity must be decreased to 1 .45, equivalent to about 40% solids, in order to maintain saturation. Very thick pulps, such as thickener underflows, are noticeably difficult to saturate in the laboratory, and lose their oxygen rapidly.Clear solutions, on the other hand, absorb oxygen readily and hold it. The primary thickener overflow, before agitation, is 100% saturated; after storage of 3 to 4 hours it is still 100% saturated at re clarifier tank. Barren solution after spraying in a launder is 100% saturated.We have not yet attempted to determine what percentage saturation is necessary for good extraction, but it is known that there is a point at which extraction decreases rapidly. So far, the measures required to maintain over 80 or 90% saturation have coincided with measures required to hold the reducing power to the point believed necessary."

Jan 1, 1964

By C. R. Edwards

"Equity Silver Mines Limited owns and operates an open pit silver 111ine located 37 km southeast of Houston in the Omineca District of British Columbia, Figure l. The property is approximately 300 km west of Prince George and 417 km east of the Port of Prince Rupert. This is the largest silver mine in Canada and one of the five largest silver producers in the western world.Equity is a subsidiary of Placer Development Limited, which owns 70 of Equity's issued and outstanding Common Shares. Placer was responsible for financing and developing the property and now provides general management and administrative services.All mining is by open pit methods, using three 1600 P&H shovels, eight 45 t Caterpillar and three 77 t Wabco trucks, three 40R rotary drills, two D8 dozers, one 9888 front-end loader and other ancillary equipment. We are now phasing out the Southern Tail pit and bringing the Main Zone into productior; see Figure 2.Comminution in the concentrator is achieved via primary, secondary, and tertiary crushers followed by rod and ball mills. The flotation circuit, with Southern Tail ore, produces a concentrate containing between 3 000 and 6 500 g of silver per tonne, 201 copper, and 25 g of gold per tonne. Running Main Zone ore, concentrate grades will decrease to about 4 500 g of silver per tonne, 17% copper, and 18 g of gold per tonne. Design milling capacity is 5 300 tpd, which is often exceeded.The flotation concentrate contains relatively high levels of antimony and arsenic. Because of these impurities Equity was unable to obtain economically acceptable long-term sales contracts for flotation concentrate. For this reason a leaching process was developed, and a plant designed, built and placed in operation. Due to the complex and unique technology involved, many start-up problems were encountered but by March 1983 the leach plant was considered ""fully operational."" This paper describes some of our progress and problems in bringing the Equity leach plant through its start-up period."

Jan 1, 1984

By A. Fyson, M. P. Smith, Margarete Kalin

"Drums containing 0.07 m3 of pyritic waste rock from a zinc/copper mine, with and without Natural Phosphate Rock (NPR) additions (40 kg/t waste rock) were set up outdoors. The effluent chemistry has been monitored over a period of 709 days. In the presence of NPR, the cumulative acidity discharged from 7 out of 8 drums was 80 % less than that discharged from drums without NPR. Mixing NPR throughout the drums was more effective in reducing acidity than placement of the NPR in a layer in the drum. NPR treatment was more effective for 'fresh' waste rock than for material which had weathered for more than 4 years. It is concluded that application of NPR to pyritic waste rock could greatly reduce acidity generated.IntroductionWaste rock dumps are significant sources of acid, generated by the oxidation of sulphides. Oxygen and water supply are oxidation rate-controlling factors, and oxygen supply is the reaction-limiting component. If secondary minerals can be formed on the surface of the rocks, pyrite oxidation and therefore acid generation may be reduced or inhibited. Neutralizing agents such as limestone do not prevent the oxidation of pyrite but treat the resultant acid mine drainage (AMD) or acid rock drainage (ARD).Meek et al. (1991) determined in pilot scale experiments that apatite mixed with tailings was more cost effective than liming or use of PVC liners to reduce oxygen and water penetration into the tailings. Phosphate is not acting as a neutralising agent but it creates a chemical condition on pyritic surfaces which prevents reactions of the oxidising agents. Precipitation of principally iron phosphates physically isolates the pyrite surfaces from further oxidation (Ziemkiewicz 1990; Evangelou 1994). The chemistry of the phosphate effects has been described by Spotts and Dollhopf (1990). Secondary mineral formation was evident in the leach pile at Gibraltar when leaching was impaired (Scott, 1991) indicating a link between oxidation and the mineral-formation process. This paper reports on effluent characteristics when waste rock is generating acid in the presence of NPR."

Jan 1, 1995

By Maurice Hall Haycock

ONE result of the higher price of gold has been the exploitation of many low-grade deposits, the successful treatment of which depends upon obtaining high recovery of the contained gold. Modern methods have made it possible to recover gold from many ores formerly regarded as impossible to treat economically, but in order to apply these methods efficiently it has become desirable, and indeed in many cases indispensable, to gain precise information concerning their mineralogical and physical character. The most successful means of doing this is the use of the reflecting microscope. Reflecting microscopes had long been employed by metallurgists for studying polished surfaces of iron and steel when, thirty years ago, Dr. W. Campbell, of Columbia University, advanced the idea of using similar methods for studying opaque minerals (1). The immediate result was the completion of two microscopic studies, the first on Cobalt silver ores (2) and the second on Sudbury nickel ores (3). The idea was surprisingly slow in being adopted, and not until 1911 did it begin to spread through the universities of this continent. From then on, ore microscopy, or 'mineragraphy', made rapid progress, and, during the next fifteen years, research in universities of North America and Europe led to the development of somewhat specialized apparatus and technique. This phase of development, which resulted largely in contributions of a descriptive nature, furnished a mass of data from which the possibility of economic applications was soon recognized. Ore microscopy became an aid to the mining geologist in solving many problems of ore deposition. This soon led to its application in the study of ores and mill products in connection with their treatment. Its usefulness in this latter field has been very marked and has led to its widespread adoption by the mining industry.

Jan 1, 1937

By Carmen M. Neculita

Optimizing the long-term efficiency of passive systems for the treatment of highly contaminated acid mine drainage (AMD) is still a challenging issue. The optimization lies, among others, on improving the understanding and quantification of metal removal mechanisms in order to predict and enhance the stability of neo-formed minerals in secondary phases. Sorption, and precipitation as oxides-hydroxides, carbonates and bio-sulfides are likely the most important metal removal mechanisms involved in passive biotreatment of both slightly and highly contaminated AMD. In the same time, the preferred mechanism is precipitation of metal sulfides that are more stable and less pH dependent than carbonates and oxides-hydroxides. However, results of relatively recent research studies performed at laboratory scale showed that sulfides accounted only for up to 15% of total metals removed in passive bioreactors treating highly contaminated AMD dominated by iron (around 500 mg/L). Several approaches were used in the aforementioned studies to understand and quantify metal removal mechanisms in spent reactive mixtures collected from long-term (12-15 months) operating column bioreactors. These included: thermodynamic equilibrium modeling and various chemical extractions and mineralogical analyses (such as single and sequential extractions, acid volatile sulfides-simultaneously extracted metals determination, scanning electron microscopy, X-ray diffraction, and thermo-gravimetric analysis). The large proportion of metals (85%) removed by sorption and precipitation as oxides-hydroxides and carbonates suggests a relatively high mobility of the neoformed minerals, especially in low pH conditions. However, no data is available on the long-term stability of spent reactive mixtures and, on the implications for the sustainable management of this type of solid waste. Lately there is almost a consensus that the efficiency of highly contaminated AMD treatment is warranted by the use of multi-step passive systems, including both chemical and biological units, installed sequentially. However, very few well-documented studies are available on the design, construction, operation and long-term efficiency of these multi-step systems. A leading example is the tri-unit passive system installed on the abandoned Lorraine mine site (Québec) to treat a highly contaminated AMD dominated by iron (about 2,500 mg/L). This tri-step system (160 m3), consisting in two bioreactors separated by a unit filled with wood ashes, achieves to date a satisfactory removal of iron (up to 99%). Moreover, based on the data collected during laboratory testing, iron was mainly removed in the wood ashes unit (from around 3,200 mg/L to 10 mg/L) by precipitation of oxides-hydroxides as predominant mechanism and only partially by sorption. However, no data is available on the actual metal removal mechanisms in the field. Overall, theses multi-step systems are more complex and their long-term performance is even less predictable than the single unit systems. This paper presents the current knowledge and the research needs on metal removal mechanisms in passive bioreactors and multi-step systems for the long-term treatment of highly contaminated AMD. KEYWORDS

Aug 1, 2013

By K. S. Coley, M. A. Rhamdhani, G. A. Brooks

Interfacial phenomena in high temperature reactions such as between iron alloy and slag is well documented but not fully understood. It is believed that a gradient of oxygen concentration plays an important role to the occurrence of such phenomena. This article describes the results from the continuation of the study of interfacial phenomena between Fe-Al alloy droplets and CaO-SiO2-Al2O3 slag. Materials characterization techniques involving microscopic observations, depth profiling, bulk, point analysis and were carried out. The roles of oxygen as well as other factors that contribute to the interfacial phenomena were evaluated. The results and their implications to steelmaking will be discussed.

Jan 1, 2004

Heap leaching accounts for around 20% of the global production of copper. In heap leaching coarsely crushed ore particles are contacted with an aqueous lixiviant percolating through large packed beds (heaps) of the ore particles, with the loaded solution collected at the foot of the heap for metal recovery, solution make-up and recycle. While dominant for copper oxide acid leaching, it finds application also in copper sulphide (bio) leaching. Despite their apparent simplicity, heaps are in fact complex chemical reactors in which a number of competing sub-processes determine the overall rate of metal extraction. Therefore, meaningful prediction of copper production rates from heaps, as well as operational optimisation and control, all hinge on a comprehensive and quantitative understanding of these complexities. The paper gives a comprehensive overview of the various sub-processes in copper heap leaching and their interactions, including those relating to mineral-particle-solution-gas phase interactions at the micro-scale bulk transport and distribution of solution in unsaturated dense beds at the macro-scale. On the basis of a more fundamental understanding and modelling, the potential for optimized operation offers new opportunities for the extraction of value from both low-grade and complex polymetallic ores. INTRODUCTION Heap leaching is one of the percolation leaching technologies, which includes in situ leaching, dump leaching, heap leaching and vat leaching (Bartlett, 1998). The common phenomenon in all these technologies is the transport of leach solution through a fixed bed of ore particles, which interacts with the solid as it migrates along its path. The target minerals are released into solution and with its flow are carried out of the bed. The targeted dissolved metal species are recovered from solution through various hydrometallurgical techniques, especially solvent extraction (SX), before the barren solution is returned to the leach process. Heap leaching is practised in three main types of applications: sulphuric acid leaching of copper oxide ores, cyanide leaching of gold ores as well as the oxidative acid leaching of secondary copper sulphide ores, usually with the assistance of certain microorganisms and, more recently, in the presence of chlorides (CaCl2, sea water). While gold heap leaching dates back to the 1960s, large scale copper heap leaching commenced in Chile from the 1980s, and sulphide heap leaching emerged essentially as a consequence of acid leaching from mixed oxide/sulphide ores from the 1990s (Watling, 2006).

Jan 1, 2019

By A. Hartikainen, M. Rinne, F. Johansson, R. Yorke, L K. T. Uotinen, E. Korpi, J. Antikainen

"In order to determine the in-situ shear strength of rock joints, large scale testing is required. However, this is both expensive and difficult to execute. One possible method to overcome this may be to use photogrammetry to capture large joint surface roughness in-situ and downscale it to replica samples, which could be sheared in laboratory. In this paper, as a first part in such a method, a technique to digitize surface roughness and to produce replica samples for laboratory shear testing from a larger joint sample are presented. First, a thin granitic rock slice with dimensions of 1.75 m x 0.95 m of granitic intact rock was chosen for the study. The joint surface is fresh and created through tensile induced splitting. The large joint sample is digitized using photogrammetry. Then, one fullscale 1.7 m x 0.6 m geometry is cropped from the digitized joint geometry and then subsamples at 10x, 7.5x, 5x, 2.5x and 1x scales. All sub-geometries are scaled down digitally to produce 0.17 m by 0.06 m geometries. The geometries are used to make casting molds both positive and negative to produce samples with perfect matedness. The casting molds are 3D printed in polylactic acid plastic and C60/75 concrete is cast to produce a replica series. In addition to the creation of this replica series, two pilot replicas are also tested using a portable shear box with a 0.5 MPa normal pressure. The results from the pilot rounds are presented and discussed. Finally, suggestions for future research are given.INTRODUCTIONThe rock mass strength is in many cases controlled by the shear strength of rock joints, especially in hard rock masses. The shear strength is generally found to be influenced by several parameters, including normal stress, the basic friction angle of the intact rock, the joint surface roughness, the joint wall compressive strength, the matedness of the joint surfaces, weathering and infilling. The effect of these parameters for the joint shear strength can be evaluated in laboratory scale. However, the shear strength is known to be scale dependent. How the scale effect influences the strength is not fully understood. The general consensus is that the shear strength decreases when sample size increases, i.e. a negative scale effect (Bandis et al. 1981). However, some studies have presented contradictory results, see for example Hencher et al. (1993) and Kutter & Otto (1990). The extent and nature of the scale effect is still a question of debate (Tatone & Grasselli 2013)."

Jan 1, 2015

By Jakob Janzen

This paper demonstrates that the introduction of a Battery Energy Storage System (BESS) into an isolated diesel generator based grid has the potential to reduce the electricity cost and deliver a good return on investment. Energy storage also allows for increased renewable energy penetration, into the isolated grid, that further reduces the electricity cost. The isolated power system studied includes several diesel generators of different sizes. The typical operating pattern is for the generators to be run at 80% to 85% of their power rating to deal with load fluctuations. Operating the diesel generators near their full power rating, however, improves their efficiency, in this case, while the frequency and load control can be carried out by the BESS. Operating the diesel generators near their full power rating reduces the number of generators which need to be operating to support a given load. As a result, the improved efficiency of the diesel generators and reduced maintenance cost, for operating fewer machines, are the reason for the savings.

Aug 1, 2013

By T. Robson

"A multi-seam underground mining operation employing mechanized room-and-pillar methods provides 35 per cent of Smoky River's annual ROM coal production (2 million tonnes) from the Smoky River coal field. Surface mines provide the balance. Tectonic activity, which has resulted in deformed coal seams and a rugged relief to the area, has provided natural boundaries to discrete mining areas. Coal transportation to the central preparation plant incorporates a 3 km long underground conveying system. The company is committed to efficient resource recovery and a safe and healthy working environment. Introduction The Smoky River Coal operations (SRC) are centered in the Smoky River coal field located in west central Alberta, some 360 km west of Edmonton and 20 km from the Town of Grande Cache (Fig. 1). Combined mining operations produce 2 million tonnes per year run-of-mine coal from which 1.65 million tonnes of high quality, low volatile, coking coal are obtained. The underground mining operation, employing mechanized room-and-pillar methods, provides 35 per cent of SRC's annual ROM coal production (2 million tonnes). Surface mines provide the balance. Tectonic activity has resulted in deformed coal seams and a rugged relief in the area. This has provided natural boundaries to discrete mining areas. Background Exploration of the Smoky River coal field took place over four decades commencing in 1926. McIntyre Mines Limited (parent to Smoky River Coal Ltd.}, commenced development of the property in 1968 having secured a long-term contract for the delivery of coal to Japan. Production of underground coal at Smoky River commenced toward the end of 1969 and has been continuous on the property since that time. Originally, two underground mines were opened. Original planning envisaged the use of room-and-pillar techniques to develop blocks of coal for subsequent extraction by longwall retreat mining. Following initial development, two longwall units were established, the first in November 1970 in No. 5 Mine and the second in February 1971 in No. 2 Mine. Difficulties were experienced on both units, and production commitments could not be achieved. The longwalls were discontinued, and mechanized room-and-pillar was subsequently used for all underground mining."

Jan 1, 1985

By M. Hozayen, Q. Ni, E. S. Radwan, P. Nawrocki, A. Jebbouri

"A major geomechanical study was conducted for one of the UAE onshore oil fields with the purpose of studying reservoir rock properties and stress distribution, based on which a 3D coupled reservoir geomechanical model was built. This model was later used for wellbore stability analysis and for analyzing the effect of fractures on future reservoir production performance, including fracture deformation and permeability evolution occurring due to reservoir depletion and resulting changes in local stress field. The subject of this study was a complex fractured Upper Cretaceous carbonate reservoir characterized by high degree of heterogeneity, both vertically and laterally. Wellbore instability related drilling problems were encountered while drilling the wells in this field. The problems were mainly in drilling the horizontal wells, including breakouts and mud losses. Experimental results of laboratory tests used in this study are summarized in Part I of this paper whereas wellbore stability analysis and formulation of a3D geomechanical model that was built for that purpose is summarized herein.A 3D geomechanical reservoir model was developed, which included natural fractures. The mechanical properties of the reservoir rock, such as Young’s modulus, Poisson’s ratio, UCS, friction angle and tensile strength were populated based on the correlations established in Part I of this paper and the developed model was then used to simulate the 3D mechanical-property distribution and the evolution of the in situ stresses in the field due to depletion from 1983 to present-day. Based on the full field model, mud weight cubes were developed to predict the safe mud weight windows in different drilling directions. In addition, well stability prediction for two planned wells was performed using a 3D near-borehole model. Firstly, the computed stress state and mechanical properties simulated in the full field model were extracted along the well trajectory of an existing horizontal well which was drilled recently and then, a3D near-borehole model was constructed along the well trajectory. The wellbore stability analysis along the well trajectory, including stress state, strain distribution and displacements, was performed to identify the instability events along the well trajectory. It has been seen that the presence of natural fractures is closely related to the recorded borehole instability incidents. The computed plastic strains which indicate the wellbore failure were consistent with the recorded wellbore instability events in the FMI image logs, what provide further verification of the developed model. Then, this 3D near-borehole model was applied to two planned horizontal wells and the wellbore stability analysis for the two wells was carried out.The results showed that drilling vertically in the reservoir is safer than drilling horizontally. However, the drilling mud weight window in the vertical direction is narrow, being as narrow as 18.7 pcf or 0.299 sg locally. Drilling horizontally is less stable towards the maximum far field stress direction than towards the minimum far field stress direction. The mud weight cubes were used to identify the optimal well placement and well trajectory. For planned well trajectories, this technology can also be used to determine the optimal mud weight."

Jan 1, 2015