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By Richard Stewart

There are highly competitive world markets in most of the minerals being mined today. The high standard of living we enjoy in North America results in ever increasing productivity through mechanization and automation. Conventional underground and open-pit mining practices throughout the world are constantly changing to reflect the engineering advances of our technology. New records in tunneling, shaft sinking and excavating are being established. Larger and faster equipment is in production. Mining operations are being studied in detail to improve materials, methods and machines. Standards and controls are being established to measure the performance of people and equipment. These steps all tend to improve our present performance. In addition to these short-range improvements, however, there are the basic research and applied research studies which are aimed at developing entirely new approaches to our mining problems. Basic research in rock mechanics is coupled with applied research in rock penetration, fragmentation and stabilization.

Jan 1, 1963

By W. A. Gow, H. H. McGreedy

It is believed that many of the problems encountered in the operation of gold cyanidation plants are difficult to resolve due to the lack of sufficient and reliable in-formation regarding the variations and actual values of operating variables at any given time. The application of instruments to monitor the more important variables in the cyanidation process should result in more efficient plant operation and a better understanding of the process. The use of pH and conductivity sensing devices for alkalinity measurements, a monitor to determine the dissolved oxygen content of plant solutions, a continuous cyanide titrator and sonic control of grinding circuits are discussed. Although the discussion is oriented toward the cyanide process, much of the paper is applicable to other ore treatment operations.

Jan 1, 1966

"A 3-dimensional finite element model for stress/stability analysis of rock excavations in underground mines is presented. Developed for use on personal computer under OS/2 operating system, the model employs the 8-node isoparametric brick element and accounts for such loading conditions as in situ stresses and gravity loading of the rock mass. In addition, modelling of backfill in mine stopes as in situ stress-free material is incorporated. Material failure is assessed by Mohr-Coulomb or Hoek-Brown failure criterion. A mine design example is presented to illustrate the potential use of the model as a tool for stope design.IntroductionNumerical modelling of mine structures has become a vital tool for mine design in recent years. The need to maximize ore extraction ratio and to reach deeper mineral deposits underground has led the mining industry to employ numerical methods of analysis to undertake complex ground control studies in order to better understand the ground response to mining excavations and to evaluate the ground support requirements. Thanks to the rapid developments in computer technology, it is now possible to perform very comprehensive analyses including, but not limited to, 3-dimensional, elasto-plastic, or large deformation or time dependent nonlinear analyses on personal computer.During the past ten years or so, many researchers undertook 3-D finite element analyses of rock mechanics problems in mining engineering. The following is only a sample review. For example, Chan'!' used three-dimensional finite elements to study the mechanical response of jointed granite during shaft sinking at the Canadian Underground Research Laboratory. Wang et al.(2) performed 2-D and 3-D finite element analyses of room-and-pillar mining system with flat and rolling coal seams. Thatejatu used three-dimensional finite element method to examine the problem of branching tunnels. Dolezalovaw used three-dimensional finite elements for the analysis of tunnel-face advance with partial excavation as well as full-face excavation in combination with rein for cement of the face by long anchors. Peili (5) used three-dimensional finite elements for the simulation of rock-liner interaction near the tunnel face."

Jan 1, 1992

By K. Hasselwander, K. Knabel

"A significant area of Outotec’s business involves fluidized bed roasting. With several decades of experience, more than 300 reference plants and strong R&D capabilities, the company provides several industries with optimum processing solutions. Applications include oxidation and sulfation of sulfides found in copper, pyrite and zinc concentrates. Gold production and de-arsenifying roasting are also within this scope. This paper describes the latest furnace developments and includes novel trends. Moreover, hot and wet gas cleaning systems are examined focusing on unit operations related to the removal of components such as dust, SO2 for sulfuric acid production, fumes, halides, Hg, hydrocarbons, nitrous oxides and metals.INTRODUCTIONGenerally, when defining roasting processes, it can be stated that the respective primary pyrometallurgical reaction is exothermic, of gas-solid nature and relates to a value solid product. These processes are a key focus within Outotec’s scope and include: (i) dead roasting (ii) sulfating roasting (iii) partial de-arsenifying roasting and (iv) two-stage, de-arsenifying roasting.Dead roasting involves the oxidation of a given sulfide, thus allowing for a subsequent leaching process, and has been applied to producing ZnO. Dead roasting of pyrite has also been extensively utilized with a primary goal of producing sulfuric acid. In contrast, sulfating roasting involves converting a sulfide to its sulfate, enabling a selective sulfation of components, such as Cu or Co, and their separation from ferrous components during leaching (produced sulfates are soluble). Partial roasting involves partially oxidating the metal sulfide to its oxide with the simultaneous production of gaseous As4O6, which is handled during gas cleaning. The solid product, containing hardly any As, is rich in S and can be fed to a respective smelter (e.g. in the case of Cu). Alternatively, if the production of oxide is required, a dead roasting step is added after the partial roasting step, with the overall process considered as two-stage roasting."

Jan 1, 2012

By J. D. Wilkins

"Ore outcrops were first discovered in the area in 1911. Following various periods of exploration by private interests and Cominco Limited, the Coast Copper Company, Limited property was brought into production in August 1962. Subsequently, Cominco explored the adjacent Quatsino Gold Mines property and is currently developing, and producing from, what is now known as the Benson Lake Mine.The Benson Lake Mine was developed using a conveyor-equipped decline and trackless LHD equipment. The operation produces 800 tons per day of copper-iron ore, copper being the main product. Copper and iron concentrates are trucked 25 miles to storage and shiploading facilities near Port McNeill to await shipment to Japan."

Jan 1, 1971

By Nirmal Weerasekara, Lian X. Liu, The University of Queensland, Weiguo Xie, Benjamin Bonfils, Ping Yu

A mill model structure based on the population mass balance framework incorporating breakage characteristics, slurry and solids transport, product classification and discharge and energy consumption was reported in XXVII IMPC and named the Generic Tumbling Mill Model Structure Version I (GTMMS I). In this work, a new 4D (four dimensional) appearance function sub-model based on the experimental results of the JK Rotary Breakage Tester (JK RBT) was developed to describe the breakage characteristics and was applied to this new model structure. The newly developed 4D appearance function model has fewer fitting parameters and is more generic in nature. Most importantly, it is applicable to both high and low energy impact breakage. It is therefore much more versatile in comparison to the existing JKMRC t10- tn appearance function and the size-dependent JK M-p-q t10-tn appearance function. In addition, the Discrete Element Method (DEM) energy distribution model was integrated into the new model structure. With DEM results providing energy distribution information inside the mill directly, the selection function and the back-calculation method used in the existing JKSimMet modelling method are not needed in this model structure. With the above two revolutionary innovations, the previous model structure was upgraded to the Generic Tumbling Mill Model Structure Version II (GTMMS II). Furthermore, the new model structure is dynamic in nature with time-stepping technique for non-steady-state simulation. A case of the dynamic grinding of a SAG mill was studied to validate the GTMMS II. The model simulation results agreed well with the plant data. With the newly developed 4D appearance function model, the incorporation of DEM energy distribution and transport function, the GTMMS II is an important step forward towards mechanistic modelling of tumbling mills.

Jan 1, 2016

By S. Banisi, J. Marois, A. R. Laplante

"This paper compares the behaviour of gold and ore in the grinding circuit of Hemlo Mines Ltd. Particular attention is given to grinding kinetics, classification behaviour, and liberation. For grinding kinetics, laboratory grinding of gold flakes and silica, 840 µm to 1200 µm in size (14/20 mesh), was also performed to provide a standard for comparison and to study in a controlled environment the mechanisms of breakage, folding , smearing and impacting.Grinding kinetics were characterized at laboratory scale with breakage and selection functions. The breakage function showed that 75% of gold disappearing from the 840 µm to 1200 µm class reported to the 600 µm to 840 µm; this figure is much higher than for silica (46%) or most other minerals, and implies that comparatively fewer fine fragments are produced from the breakage of gold flakes, on account of gold's malleability. The selection function of silica was four times that of gold. At plant scale, the ratio of the selection function of ore and gold increased from 6 for at 50 urn to JOO pm to 20 at 500 um to 1000µm.Observation of original flakes and their fragments with the scanning electron microscope showed that the main mechanism of ""grinding"" from the 840 µm to 1200 µm to the 600 µm to 840 µm class was folding rather than actual breakage. This was confirmed by a measure of individual flake weight. The postulated breakage cycle is that relatively globular flakes become increasingly serrated through grinding; they can then regain their original shape through folding and reflattening into cylindrical and spherical shapes, as the majority does; however, some fragments will at this point undergo actual breakage. Photograhic evidence is presented to support the proposed mechanisms.Smearing of gold unto silica was observed when silica was ground after a gold, and embedding of silica into gold flakes when gold was ground after a silica. Both mechanisms occur whenever gold and harder minerals are jointly ground, and result in ""unliberation"" of gold. It is postulated that smearing of gold onto other minerals plays an important role in explaining how gravity recovery can increase over-all gold metallurgy, especially when used ahead of flotation.Classification of gold in the primary hydro cyclones takes place at a much finer cut-size than ore, 20 µm vs 57 µm. This and the slower grinding kinetics result in high gold circulating loads in the primary loop, 6700%, and a gold content in the primary cyclone underflow (PCUF) is twenty-four times that of the ore. The gold size distribution for primary cyclone overflow is much finer than that of the ore, although they are essentially similar in the PCUF.Liberation, or more accurately ""gravity recoverability"", was assessed with a 7.5 cm (3 in.) Knelson concentrator. It varied between the thirties for the primary mill discharge and two cyclone overflows, to highs of 89% and 92% for the PCUF and secondary mill discharge."

Jan 1, 1991

By M. S. Greenfield, E. Cocchiarella, S. Chubbs

"At Dofasco sNo.4furnace a variation of the basic oxygen steelmaking process, Klockner Oxygen Bottom Maxhutte (K-OBM), is used to produce steel. Large amounts of hot gases and particulate are evolved during the oxygen blowing phase. A quencher and a venturi scrubber are used to collect over 99.5% of the particulate. In 1990, the authors investigated the effect of foamy slag on the particulate emissions from the furnace. The amount of lime added early in the oxygen blowing cycle was reduced, making the slag more viscous and foamy for a six minute period. Instantaneous particulate emissions were monitored throughout the blow by analyzing quencher and venturi scrubber water samples. Particulate emissions were reduced up to 59% during the foamy slag period.IntroductionThe reduction of the amount of waste generated or control of emissions at source is at the top of the ""3R"" hierarchy of waste management (Reduce, Reuse, Recycle). Process and operating practice changes are often the most economical ways to control emissions. At Dofasco, they investigated the effect of operating practice changes, specifically the formation of a foamy slag, on particulate emissions from steelmaking furnaces. They wanted to determine if a foamy slag changed the quantity and nature of the fume evolved from the K-OBM furnace over the oxygen blowing phase.The Basic Oxygen Steelmaking ProcessesThe basic oxygen steelmaking process (BOP) generates large quantities of very fine metal oxide fume during the production of steel. In this process, scrap steel and molten iron (hot metal) from blast furnaces are charged into a steelmaking furnace. Then pure oxygen is injected and a lime flux added . The oxygen reacts with carbon dissolved in the molten iron to form carbon monoxide. Oxygen lances can have secondary nozzles which introduce oxygen above the bath. This secondary oxygen, known as post-combustion, bums some of the carbon monoxide radiating the heat back to the bath. Particulate and gases rich in carbon monoxide are ejected from the furnace during the oxygen blowing phase and are collected by a gas cleaning system. Typically, more than 99.5010 of the particulate is scrubbed from the gases by high energy venturi scrubbers or electrostatic precipitators. The oxide sludge or dust collected may have elevated zinc and lead which is unsuitable for recycle to blast furnaces. Due to the presence of these undesirable elements, treatment and disposal of steelmaking oxide dust is difficult and costly."

Jan 1, 1993

By A. G. Spencer, A. D. Taylor

This paper discusses some of the advantages and problems associated with the selection of large unit equipment for a metallurgical plant. A given flowsheet and material balance for an iron ore concentrator is assumed. Then two plant designs are developed, one utilizing a number of smaller-size equipment units and one utilizing the largest available equipment units. The mechanical and electrical problems are discussed and a comparison of capital costs is made. Finally, brief consideration is given to a plant de-sign using units larger than those which are currently available.

Jan 1, 1968

By E. Topuz, C. Duan

"INTRODUCTIONOperations research (OR) applications have experienced a substantial growth within the mining industry during the last three decades. The purpose of this paper is to present a summary of the results of a comprehensive survey of the application of various OR techniques to the major mining activities. It is hoped. through this sur vey , that the most widely used OR approaches, the important areas of application, and future trends have been identified.This survey included more than 500 articles published in this field in English since the late 1950s. Most of the relevant literature was found in mining publications, but, in terms of quality and originality, important applications were also found in literature not related to the mining industry. The sources constituted periodicals, proceedings research reports, and a few books. A listing of selected publications from which three or more articles reviewed in this survey appear is given at the end. Operations Research MethodologiesOperations research is concerned with optimal decision making in, and modeling of, deterministic and probabilistic systems that originate in real-life situation s. One basic feature of the OR methodologies is the attempt to optimize certain design parameters, subject to a set of constraints. This distinction has been employed in the survey as a guideline for selection of the techniques covered under the title "" OR methodologies"". The methodologies thus encountered in the literature are listed below. In a few cases, simulation has not been considered because it is not an optimization method per se."

Jan 1, 1989

By Silvana Costa

The quality of life in remote mining communities is a significant factor that impacts the mining industry?s ability to attract and retain high quality workers in remote areas. The rapid growth of mining development, along with the shortage of skills and training globally are reflected in an increasing need to identify the ideal conditions for employee wellbeing and investigate ways to improve quality of life of miners and their families in remote locations.

May 1, 2007

By R. N. Chakravorty

Environmental monitoring plays a key role in coal mine safety. In recent years, significant advances have been made in the development of systems suitable for monitoring air in underground coal mines. Because of intensive mining and large capital outlay, the need for higher productivity consistent with safety is well recognized and it appears that environmental monitoring may help achieve this objective. This paper reviews the state-of- the-art in the monitoring technology with particular reference to hazardous gas detection in underground coal mines. The preliminary results obtained from ongoing studies, with regard to continuous monitoring of methane and carbon monoxide in mine air in some of the operations in Western Canada, are discussed. The inadequacies of the methods using spot samples are examined and the need to supplement the present practice with continuous monitoring systems is emphasized.

Jan 1, 1979

By L. M. Lowe, D. B. Chambers, D. G. Feasby

"Potentially economic deposits of rare earth elements (REE) often contain elevated levels of naturally occurring radioactive materials (NORM), primarily thorium and uranium and their associated radioactive decay products. The concentrations of NORM usually exceed typical background levels of natural radioactivity, sometimes by factors of ten or more, and can be of concern relative to occupational radiation protection and the management and disposal of REE mineral processing and metallurgical wastes. This paper provides a summary of the radiological issues normally encountered in the REE concentrate production industry. In addition to an introduction to background radiation and radioactivity, including the thorium and uranium radioactive decay series, radiation levels expected to be encountered in REE concentrate production are outlined. The occupational, environmental and regulatory aspects of REE production related to NORM, including radiation dose limits, radioactive waste disposal guidelines, and threshold VALUES (for the application of transport regulations, are presented.INTRODUCTIONConcurrent with the increasing demand for new sources of rare earth elements (REE) to meet modern industrial needs, there is also an increasing awareness of the radioactivity associated with the REE ores and resources. This is an especially important consideration in addressing questions from the public and local communities who are often concerned about “radiation” and “radioactivity”. Public concern is heightened by reference to legacy issues that arose during times of less regulatory oversight; as well, the benefits of modern technologies, practices and regulation are overlooked. Such concerns are also often inflamed by unfounded claims by non-governmental organizations (NGO’s). Thus, it is important that all concerned have a full understanding of just what the potential risks from radiation associated with REE are, or are not. This paper provides an overview of the sources of radioactivity, the potential implications of radiation and radioactivity in the REE industry, and a brief discussion of established and reliable methods of managing exposure to radiation and radioactivity."

Jan 1, 2012

By T. Güyagüler, U. Y. Önder

"This study investigated the psychrometric properties of ventilating air in GAL coal mines. Related measurements were done in underground openings and have been arranged as input data for computer programs prepared for ventilation network and psychrometric analysis.Results obtained from network analysis have been used for psychrometric analysis of ventilating air. Changes in heat and moisture content of air in two major path s between entry and discharge of ventilating air have been investigated. Psychrometric processes occurring in the mine were determined and are shown graphically in Figures 1 and 2. Special attention has been given to determine the changes in psychrometric properties and processes involved in the faces. Results are outlined in this paper.IntroductionThe psychrometric properties of mine air are important factors to mine productivity and efficiency. Therefore, psychrometric analysis should be made for all underground mines; any undesired situation observe d could be corrected by taking the necessary precautions.The analyses were done as a case study for GAL mines, the only mechanized lignite coal mine in Turkey. In this mine, workable reserve is about 300 million tons of coal and yearly planned production is 2.2 million tons. Production is continuing from a coal measure-bed having two coal seams with average thicknesses of 1.52 m and 1.72 m respectively. A 0.85 m shale band exists between these two seams.Two full y-mechanized faces, approximately 220 m long, usually work simultaneously. All measurements, including mine gases and air velocity, are done by sensors connected to a control room by a monitoring system.In the analysis, a line diagram is utilized to described the mine on which every junction and branch is numbered."

Jan 1, 1992

"This paper describes an alternative method of vehicle control which uses a micro-processor to control the field current and armature voltage concurrently. The field tests carried out and the conclusions drawn from the basis of the paper.IntroductionIt is generally accepted that the main obstacle to a greater use of electric vehicles is the relatively poor range and performance when compared to alternatives such as diesel and petrol-engine vehicles. Much effort has been applied to the problem of increasing the energy storage density of batteries and considerable improvements are now being reported.Improvements in the efficient use of the stored energy, although unlikely to achieve the necessary increase in range and performance for a widespread acceptance of electric vehicles, can nevertheless make a useful contribution. Because the improvement in efficiency is achieved by a reduction in losses, it follows that the temperature rise in drive-train components is reduced. These advantages, coupled with the increasing cost of energy, make improvements in the efficient use of the stored energy desirable, if not absolutely necessary. To achieve this with the large and rapidly varying loads encountered during the operational use of a vehicle will require a more flexible system of control than that provided by the current limit. This paper describes an alternative method of control which uses a micro-processor to control the field current and armature voltage concurrently.The value of these parameters is selected to supply the power demand at the motor shaft, with the minimum losses in electrical transmission, thus increasing the efficiency with which the stored energy is used."

Jan 1, 1982

By P. -M. Tardif, S. Outalha, R. Le

"This paper proposes a new direction to implement an underground mine communication system. It presents actual underground communication systems and discusses their technological limits. A new system based on a wireless local area network (WLAN), together with its main systems characteristics, is then proposed. This paper also presents an experimental protocol for radio frequency propagation measurements. Finally, the paper describes the projected implementation of a WLAN in an experimental mine. IntroductionDuring the last decade, a number of Canadian mining companies have invested in modern communications systems in order to automate processes and reduce operational costs. Safety of miners is also a concern, regulated by health and safety regimes.Underground communication systems rely mainly on analog technology (especially the leaky feeder). Digital upgrades have been made to modernize this technology using a coaxial or fibre optic cable to transmit voice, documents, commands, controls, and video. Therefore, all wired equipment can benefit from an increase in efficiency from the digital technology.However, when it comes to mobile equipment, the only medium was, and is, still radio waves. With the advent of the wireless local area network (WLAN) standard, one can use a technology similar to that of the cellular phone to connect transparently different equipment. WLAN enables the transmission at rates higher than 2 M bits of voice, documents, commands, controls, identification, and of course, digital video. This technology was developed with inbuilding use in mind. Now, one can try to adapt it to underground mines."

Jan 1, 2000

By Liu Yulin, Zhao Yi, Tan Qi, Liu Lei

"Hydrotalcite is one kind of layered double hydroxides, and has special crystal chemical characteristics. Due to its good thermal stability, hydrotalcite used as the PVC heat stablier has attracted scientists’ attention. In this study, nano-hydrotalcite was synthesized by the method of mechanochemistry/crystallization, using brucite, Al(OH)3 and Na2CO3 as raw materials, and added into PVC to investigate the effect of hydrotalcite on thermal stability of composites. The synthesis mechanism was suggested by virtue of XRD, FE-SEM, FT-IR. It has been indicated that at the first of dry milling process, the parical sizes of brucite and Al(OH)3 decrease, while specific surface areas of them increase by the action of mechanical force, until produced amorphous particles. In the process of wet milling, metal ions in the amorphous body, which has high surface energy, can easily react with H2O, and produce the precursor of Mg6Al2(OH)18•4.5H2O, which has the same crystal structure as hydrotalcite. Under the hydrothermal condition, anions of OH- in the interlamination of precursor are exchanged by CO32- in the solution and nano-hydrotalcite is generated at last. The thermal stability was characterized by Congo red method. The results have revealed that hydrotalcite is one kind of long-term heat stabilizer, and residual stability time increase with the rise of added hydrotalcite amounts.INTRODUCTIONHydrotalcite, one kind of anionic clays, has been attracted a great interest for researchers because of their unexpected physical and chemical properties. The general formula is Mg6Al2(OH)16CO3·4H2O, where Mg2+ and Al3+ occupy octahedral positions in the brucite-like layers, and CO32- is an interlayer anion (Hoyo, 2007). Hydrotalcite is widely used in the fields of chemical engineering, materials engineering, environmental protection, medicine, and so forth, owing to its unique capability of adsorbability, ion exchange and thermal stability (Rozov, Berner, & Taviot-Gueho, 2010; Iwasaki, Yoshii, & Nakamura, 2012; Ay, Zümreoglu-Karan, & Temel, 2011; Cavani, Trifiro, & Vaccari, 1991; Li & Duan, 2005; Lin, Wang, & Evans, 2006). As a result, the study on synthesis and application of hydrotalcite has received considerable attentions."

Jan 1, 2016

By S. L. Chen

The Kumera Technology Center developed a unique type of steam dryer for drying copper concentrate in the mid 1990s. The dryer has been chosen in several copper smelter projects since 1999. To expand production capacities, the Norddeutsche Affinerie smelter, the Pirdop smelter of Cumerio, the Toyo smelter of Sumitomo Metal Mining and the Tamano smelter of Hibi Kyodo Smelting have carried out projects in which Kumera Steam Dryers were installed. The capacity of a single steam dryer varies from 70 t/h to 160 t/h. This article summarizes the latest operation results of the Kumera Steam Dryers in these smelters and introduces the progress of the ongoing projects in Yanggu Xiangguang Copper, Guixi smelter of Jiangxi Copper, Jinlong Copper, Boliden Harjavalta, and Onsan smelter of LS-Nikko Copper.

Jan 1, 2007

By Helen Morrison, Chris Staun, James Vaughan

"Mercury is introduced into the Bayer refining process as a trace element in bauxite. During the digestion stage, a portion of the mercury is extracted which partitions between the flash tank off-gas, vapour condensate and bauxite residue streams. A technology or treatment that stabilises mercury in the solid phase during digestion would prevent environmental management issues that may arise from the presence of mercury in condensate and non-condensable gases. This study examines the effect of process additives on the deportment of mercury under Bayer digestion conditions. Bauxite digestion experiments were conducted in batch autoclaves in the presence of additives. Process liquor was analysed for mercury content using a thermal desorption technique. Pyrite and copper hydroxide were evaluated for their suitability as additives.INTRODUCTIONMercury is an ancient metal characterised by electrochemical nobility, volatility, low solubility in water and a liquid state at room temperature (Holleman and Wiberg, 2001). The biogeochemical cycle of mercury is complex. Elemental mercury may enter the atmosphere due its volatility, where it can be transported long distances. After settling and adsorption to sediments, methylation is catalysed through microbial metabolism (Qureshi et al., 2009). Methylated mercury species are potent neurotoxins, and bioaccumulation of mercury is well documented, particularly in seafood (Kozin et al., 2013, Pan et al., 2014, Pollman, 2014). Environmental regulations for mercury emissions are becoming increasingly stringent (UNEP, 2015). Considerable research has already been performed and technologies developed for the remediation of mercury in wastewater and the trapping of mercury from industrial stack emissions. Wastewater technologies usually target ionised mercury using adsorbent, ion exchange and complexation mechanisms (Krishnan and Anirudhan, 2002, Li et al., 2015a, Chiarle et al., 2000), while stack emission technology is dominated by impregnated activated carbon adsorbents (Gao et al., 2013, Zheng et al., 2012). Related developments include piezoelectric amalgamating sensors for in line detection of gaseous elemental mercury in industrial stack emissions (Kabir et al., 2015, Sabri et al., 2011). There is a paucity of research regarding removal of mercury from the Bayer process."

Jan 1, 2016

By R. M. Clowes

"As part of LITHOPROBE's multidisciplinary earth science research program to understand the evolution of the North American continent, studies have been undertaken in a number of key areas in Canada. In the Trans-Hudson Orogen of Manitoba and Saskatchewan, LITHOPROBE results require re-evaluation of tectonic models related to its origin. In the Abitibi greenstone belt of Quebec and Ontario, results indicate a more complex evolution for the southern Superior province, one that links with the development of gold and massive sulphide deposits. As part of the program, the seismic reflection profiling method is being adapted for the mining industry. Three examples demonstrate the subsurface information that can be obtained. In Noranda, the base of the volcanic Blake River group is imaged and reflectivity is tied to geology through well logs; in Matagami, the zone of mineralization is shown to be downdropped along a majorfault; in Sudbury, a new structural model is developed, one that shows marked asymmetry at depth and indicates that some ore-bearing units on the margins of the igneous complex may be repeated at depth. IntroductionLITHOPROBE is Canada's national, collaborative earth science research project, established to develop a comprehensive understanding of how the North American continent has evolved. Ten transects, or study areas, were chosen to investigate pivotal geological features to their deep lithospheric roots. They span the country from the Pacific to the Atlantic Oceans and from the U.S. border to the Yukon and Northwest Territories, and geological time from four billion years ago to the present. A multidisciplinary approach, which is spearheaded by seismic reflection techniques, is essential to developing complete interpretations and outstanding scientific results. LITHOPROBE also has pioneered the use and demonstrated the value of using reflection technology to determine subsurface geology in mining camps.This paper provides an overview of the transects and their significance for the tectonic evolution of North America. Two specific examples demonstrate how we detennine present three-dimensional lithospheric structure and past geotectonic processes which formed it. The application of the reflection method to imaging complex structures in ""shallow"" crystalline rocks has been developed with funding and other support from the mining industry and provincial geological surveys. Sustaining funds, however, are derived from the Natural Sciences and Engineering Research Council and Geological Survey of Canada. Emphasis has been placed on developing deeper penetrating tools for exploration of deeply buried, but economically retrievable, mineral resources near existing mines, where an expensive infrastructure already is in place. Three examples, Rouyn-Noranda in western Quebec, Matagami in northwestern Quebec and Sudbury in northeastern Ontario, illustrate these developments."

Jan 1, 1994