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By A. Rejeb

ABSTRACT: This paper contributes to the study of underground structures in argillaceous media, especially Tournemire argillites (Aveyron, France). The basic results obtained over six years in two experimental drifts at the Tournemire site are presented. In situ measurements cover drift wall temperature, humidity and convergence. Delayed convergence represents around 50-65% of the total measured convergence. Analysis of the measurements has shown that delayed convergence is explained by the viscoplastic behaviour of the argillaceous formations. Lemaitre’s rheological model has been extended to the orthotropic case, as Tournemire argillite is naturally anisotropic. The triaxial creep test results on samples at different orientations enabled the parameters of the Tournemire argillite to be identified in terms of orthotropic viscoplastic law. A plane deformation model, using this rheological law and the initial stress field in the site, was developed to interpret the convergence measurements in the drifts. The computed results match the measurements well, especially during the excavation phase. KEY WORDS: Argillite, convergence, time-dependent behaviour, creep, viscoplasticity, modelling. ZUSAMMENFASSUNG: Der vorliegende Artikel ist ein Beitrag zur Untersuchung der unterirdischen Strukturen tonhaltiger Milieus, insbesondere der Tongesteine von Tournemire (Aveyron, Frankreich). Die wichtigsten Ergebnisse, die in zwei Forschungsstrecken am Standort Tournemine über einen Beobachtungszeitraum von sechs Jahren zusammengetragen wurden, werden hier vorgestellt. Gemessen wurden in situ Temperatur, Feuchtigkeit und Streckenkonvergenz. Von der insgesamt gemessenen Konvergenz sind etwa 50 bis 65 % auf zeitlich verzögerte Konvergenz zurückzuführen. Die Auswertung aller Messungen hat ergeben, dass die zeitverzögerte Konvergenz mit dem viskos-plastischen Verhalten des Tonsteinmassivs zu erklären ist. Aufgrund der naturgemäßen Anisotropie des Tongesteins von Tournemine wurde das rheologische Modell von Lemaitre auf den orthotropen Fall ausgedehnt. Triaxiale Kriechversuche bei jeweils unterschiedlicher Ausrichtung dienten der Ermittlung der einzelnen Parameter des orthotropen, viskos-plastischen Gesetzes. Zur Auswertung der Konvergenzmessungen innerhalb der beiden Strecken wurde unter Beachtung dieses rheologischen Modells sowie des ursprünglichen Spannungszustands vor Ort ein flächiges Deformationsmodell entwickelt. Die Rechenergebnisse zeigen eine gute Übereinstimmung mit den Messungen, insbesondere während der Vortriebsphase. SCHLÜSSELWÖRTER: Tongestein, Konvergenz, zeitlich verzögertes Verhalten, Kriechen, Viskoplastizität, Modellbildung. RESUME : Cet article est une contribution à l’étude des structures souterraines dans les milieux argileux, notamment les argilites de Tournemire (Aveyron, France). Les principaux résultats obtenus pendant six années, dans deux galeries d’expérimentation au site de Tournemire, sont présentés. Ces mesures portent sur la température, l’humidité et la convergence des parements des galeries. La convergence différée représente environ 50 à 65% de la convergence totale mesurée. L’analyse de l’ensemble des mesures a montré que la convergence différée est interprétée par le comportement viscoplastique du massif argileux. Etant donné que l’argilite de Tournemire est naturellement anisotrope, le modèle rhéologique de Lemaitre a été étendu au cas orthotrope. Les résultats des essais de fluage triaxial, sur des échantillons à différentes orientations, ont permis de déterminer les paramètres de la loi viscoplastique orthotrope. Un modèle en déformation plane, utilisant cette loi rhéologique et l’état de contrainte initiale dans le site, a été développé en vue d’interpréter les mesures de convergence dans les galeries. Les résultats des calculs sont en bon accord avec les mesures et plus particulièrement durant la phase de creusement. MOTS-CLEFS : argilite, convergence, comportement différé, fluage, viscoplasticité, modélisation.

Jan 1, 2003

By A. McLean, M. Iwase, K. Wakimoto, K. Katogi, Y. Kikuchi

One of the greatest obstacles to the application of physical chemistry principles to the elucidation of slag-metal reactions is a lack of knowledge of activities of the reacting species. To a large extent, oxygen potential of the slag phase governs iron and steelmaking practice. Without oxygen control by means of appropriate sensors, the behaviour of the other elements cannot be managed. In this paper, measurements of the FeO activity with various types of electrochemical FeO sensors will be described together with examples of their applications for improved strategies toward better practice for ladle metallurgy and sulphur and manganese distributions between slag and metal phases during steelmaking. Measurements of FeO activity have also been made in order to improve dephosphorization reactions. This type of work has led to significant reduction in volume of slag generated within the steelmaking vessel, which in turn has important implications for refractory wear, metal yield, alloy recovery and improved productivity. Finally, an on-line sensor is described that permits the oxygen potential to be determined for both the metal phase and the slag phase during steelmaking in the BOF.

Jan 1, 2004

By Russell R. McLellan

As part of an effort to develop new or improved placer mining technology in the Tertiary gold-bearing channel gravel of northern California, the Bureau of Mines conducted investigations at the old Badger Hill placer mine in Nevada County, Calif., to collect data and information regarding drilling and sampling methods and deposit characteristics. Sampling studies involved the collection and processing of 400 tons of large-and small-volume samples from drill holes, underground workings, surface pits, and blasthole rounds. A total of 355 samples averaging 2,296 pounds per sample provided reasonably accurate data for analysis of the gold distribution. These studies indicated that the bulk of the gold is within 40 feet of bedrock in stacked, lenticular zones of cemented gravel that are largely confined to the relatively narrow, meandering course of the deepest portion of the bedrock channel. Drilling studies involved the testing of truck-mounted rotary, buckett and vibratory drills, none of which proved to be a completely versatile tool for sampling quickly and reliably both consolidated and unconsolidated gravel..

Jan 1, 1974

By B. P. Watson

Several large falls of ground occur annually in the narrow, tabular stopes mined in the Bushveld Complex. These falls comprise safety risks and cause substantial production losses and compromise efforts to increase productivity. Underground observations in conjunction with instrumentation sites were used to establish the strategic parameters required to describe the rock mass behaviour of shallow-dipping stopes on the Bushveld platinum mines. Existing rock mass rating systems were evaluated using the observations and instrumentation results. None of the current systems adequately described all the relevant geotechnical conditions. Thus a hybrid of several current systems was developed, and the proposed system is discussed in the paper. The new rock mass rating system is termed the ?New Modified Stability Graph? system and follows the method originally described by Mathews et al.1and revised by Hutchinson and Diederichs2.Changes have been made to some of the tables provided by Barton3and to the stress analysis suggested by Hutchinson and Diederichs2. In addition, the logistical regression analysis has been applied to databases, formed using the suggested analyses, for three support resistances and risk levels established.

Jan 1, 2004

With the dawning of a new century came the beginning of a new era in the coal industry. Instead of the traditional practice of only buying and selling produced coal in the United States, a coal futures market was established. The New York Mercantile Exchange began trading coal futures in July 2001. But, even in this new era, many of the old is-sues that have beset the coal industry still remain, as was evident in2001. Coal production increased to are cord level during 2001, according to preliminary data from the US Energy Information Administration(EIA). Production in 2001 rose by4% to 1.01 Gt (1.12 billion st), compared with 2000 (Table 1). This barely surpassed the previous record level of 1 Gt (1.11 billion st)set in 1998. Coal consumption remained unchanged. The additional production was used to replenish the depleted stockpiles that had resulted after two years of declining coal production and increasing coal consumption.

Jan 1, 2002

By S. O. Choi, H. -S. Shin, W. -K. Song

Nuclear waste should be disposed with the best warranty for the national health and welfare. Among the several repository systems, the deep underground disposal is considered to be a most suitable system in Korean peninsula. However it demands basically the comprehensive stability analysis such as the behaviour of discontinuities in rock mass, the behaviour of ground water, and the reaction of rock stress according to the heat from the nuclear waste. For these purposes, the underground nuclear waste disposal repository was simulated in two- and three- dimensions. It shows that emphasis will be given to the thermal conductivity of discontinuities and the thermal convection of ground water as well as the thermal stress generated by the nuclear waste for design and construction of repository system, and they should be obtained from the field measurements. Déchets nucléaires devront tre déposés avec la meilleure garantie pour la santé et le bien public. Parmi les plusieurs systèmes de dépôt, la disposition en souterrin profond est considérée au système le plus approprié en Corée. Pourtant ce système demande essentiellement l’analyse éten-due de stabilité comme le comportement des discontinues en masse rocheuse, le comportement de l’eau souterrin et la réaction des contraintes de roche selon la chaleur depuis les déchets nucléaires. Pour ce but, le dépôt des déchets nucléaires en sous-sol a étè simulé en deux et trois dimensions. Il montre que l’accent sera donné à la conductivité thermale des discontinues et la convection thermale de l’eau souterrin aussi bien que la contrainte thermale générée par les déchets nucléaires pour le plan et la construction du systèmes de dépôt, et ils devront tre obtenus depuis les mesures sur place. Die Kernwüste muß mit der besten Gewähr für die nationale Gesundheit und die Wohlfahrt angeordnenet werden. Unter einigem Fundgrubesystem, das tief unterirdisch Wegwerfen werde in Betracht das passendest System in der koreanisch Halbinsel gezogen. Jedoch, es verlangt grundzätzlich die umfassend Stabilitätsberechnung so wie das Behnehmen mangelnder Konti-nuität in der Felsmasse, das Behnehmen des Grundwasser, und die Reaktion der Felsenbelastung nach der Hitze von der Kernwüste. Für diesen Zwecke, die unterirdische Wegferfenfundgrube der Kernwüste wurde in der zwei und drei Dimensionen gesimuliert. Es beweist daß die Betonung wird zur thermisch Leitfähigkeit mangelnder Kontinuität und thermisch Konvektion des Grund-wasser sowie die thermisch Belastung ergezeugt durch die Kernwüste für den Entwurf und die Konstruktion des Fundgrubesystem gegeben werden, und sie müssen von den Feldmaße ergelangt werden .

Jan 1, 2003

By Peter Grandstone, D. A. Jessup, D. B. Taliaferro

"INTRODUCTION Water flooding of oil sands in Texas as a means of secondary recovery of oil has been practiced mainly in the north-central part of the State, which includes the old shallow fields in eight counties, extending south through Wichita and Clay Counties on the Red River into Brown County.The Texas Railroad Commission, is empowered ""to promote conservation and prevent waste in the drilling, completion, operation, and abandonment of oil wells"" and ""to issue regulations necessary for fulfillment of these ends,"" granted The Texas Co. the first permit to inject water into the oil-bearing sand on December 7, 1935. The permit was granted after the Commission had conducted a number of hearings, which were attended by many operators interested in that method of secondary recovery. Through December 31, 1944, the Commission had granted 50 permits for water flooding. Of that number, 45 permits were issued for projects in north Texas, the remaining 14 being distributed throughout west and south Texas. By the end of 1944, there were 33 active and 5 abandoned water-flooding projects in the North Texas area, as is in figure I.Oil production in the North Texas area started in 1904 from the shallow sands (ranging from 100 feet to 800 feet in depth) of the Petrolia (or Henrietta) field in northern Clay County. Development was rapid and unrestricted during the boom period from about 1911 to 1918, and considerable waste of both produced oil and reservoir energy resulted."

Jul 1, 1946

The only economically significant deposit of dolomite in New Zealand is at Mount Burnett, in north-west Nelson. The dolomite, associated with marbles and schists, is complexly deformed, and is of Paleozoic age.A very large quantity is present, although the recoverable amount is to some extent limited by the difficult terrain.Physically the quality of the dolomite is excellent. It is a tough, durable, fine grained rock. Chemically it is a little more variable. The range and frequency o~ the more important impurities are illustrated by hlstograms, as is the "dolomite factor"-a measure of the amount of the mineral dolomite in the rock. lbe dolomite factor averages 84 per cent, the remainder of the rock consisting largely of calcite. Quarrying, milling, production, and uses are described. In 1966 production reached 13,250 tons.

Jan 1, 1969

By A. J. Basu

New technologies, such as computer based learning, wireless computing, internet2, online courses, distance learning, and in general multimedia applications are being implemented in the higher education sector in an increasing manner. However, these implementations are not coherent, and lack standards. However, one example of the existing standards is the development and implementation of the virtual learning environments. These technology tools help in delivering the eLearning objectives. There is a major initiative in Europe (eEurope action plan) in promoting eLearning towards creating a knowledge-based society. Technology implementation is the major driver for achieving the eLearning objectives. A two-year pilot project on implementing technology tools including virtual learning environment (VLE), video-conferencing, and simulation and visualization was carried out for providing a blended learning environment for undergraduate and graduate students in Mining Engineering (undergraduate) and Mineral Deposit Evaluation (M.Sc.) course at the Imperial College London. The pilot project was funded by the Imperial College Centre for Educational Development (ICCED). The project did contribute towards activities for creating an institute-wide eLearning strategy in line with the eEurope action plan.

Jan 1, 2003

The French research institute, INERIS, requested the assistance of the CSIR?s Division of Mining Technology in developing further precautionary measures against explosions in their collieries. In response to this approach, an on-board active suppression system was adapted to meet their mining requirements. This system is used on tunnelling machines in Germany where the machine is positioned in the middle of the tunnel, which is therefore not much wider than the machine itself. With this configuration, the machine is never away from the tunnel face during the cutting cycle. As a result, the possible volume in front of the machine of combustible gas requiring suppression is less than 50 m3. In South Africa this technology has been adapted to suit a two-cut mining method which entails greater distances from the face and thus much larger volumes of methane mixtures requiring suppression. The particular configuration of the Explo-Stop® system being investigated required the suppression of possible methane ignition volumes of up to 180 m3of a 9% per volume methane/air mixture. The volume is a consequence of the large cross-sectional area of French underground workings and of the two-cut mining method used in France. In order to take the second cut in the coal seam, the machine is pulled back a maximum distance of 4 m, leaving an air pocket in which gas can accumulate. The machine-mounted system is required to effectively suppress any flame ignited by such a large accumulated volume of methane. The results of the protocol tests done at Kloppersbos showed that the system was capable of suppressing all simulated methane ignitions for the prescribed conditions. This was achieved with a temperature increase of less than a 100°C at the operator?s position and without any flame being detected at this position.

Jan 1, 2001

By Charles H. Jacoby

The solution mining of evaporites has a history of approximately 5,000 years. The insitu leaching of metalliferous ore will have many of the same characteristic problems which have confronted industry for years in the production of evaporite minerals. Basically we will be converting the less soluble forms of valuable metals into their more soluble salts and producing these in much the same manner as, for example, sodium chloride. There are a number of problems which we are faced with that are more complex and complicated and, therefore, will require a higher degree of sophistication than previously employed. One of our most important undertakings will be the clearcut definition of the problems involved. While a great deal of expertise can be drawn from the solution mining of evaporites and the oil industry, problems peculiar to the hydrometallurgical field will need to be solved. One of these is the introduction of permeability into an impermeable rock so as to expose the sought after values of metals which by volume are infinitesimal when compared with sodium chloride, potash or other type water soluble mineralization. After establishing this permeability which will be miniscule when compared to a solution cavity, there will be the maintenance of this permeability. In general, salt deposits are of a somewhat uniform chemical composition and thus their chemistry was relatively simple. Each metalliferous ore body is somewhat unique in its chemistry and will need to be treated accordingly.

Jan 1, 1974

By Gray Mullins

A post grouted drilled shaft foundation system was successfully used in place of the specified driven pile foundation system as a Value Engineering Cost Proposal (VECP) for the new PGA Boulevard Grade Separation Project. Pressure grouting the cohesionless sandy soils at the drilled shaft base significantly increased the end bearing capacity and stiffness allowing drilled shafts to be the more cost effective foundation system. The post grouted drilled shaft option also provided other benefits including reducing owners risk normally associated with pile driving vibrations and offered a high level of quality assurance for the drilled shafts. This paper discusses the implementation of post grouted drilled shafts from design to completion of construction. A design procedure for post grouted drilled shafts developed by the University of South Florida was used for initial VECP evaluation. Prior to construction, two instrumented test shafts were installed and load tested, one of which was post grouted. Therein, the design procedure was calibrated, tip elevations for production shafts were refined, drilled shaft construction and grouting procedures were demonstrated, and a grouting criteria was developed for the project.

Jan 1, 2003

n the early days of the Hauraki goldfield (1866 to 1889) almost the only system of ore treatment was wet crushing followed by copper plate amalgamation. A further saving of bullion was in most cases obtained from the tailings by means of pans or berdans. Though this system was not always as efficient as might have been desired it answered fairly well for the bulk of the gold-bearing quartz of the Thames and Coromandel districts, where the gold occurs chiefly in the form of visible particles, and there is not a great deal of silver. It failed, however, with most of the ore found in the Upper Thames or Ohinemuri district, especially in the Karangahake and Waihi portions of the field. In those days the cyanide process was not, and the usual prescription of the mining " expert" was smelting. At Karangahake, many attempts were made to discover a payable method of treatment for the so-called" refractory" ore, but on thewhole with very 'little success, and the district struggled along for a number of years without adding very materially to the production of gold in New Zealand. At Waihi, the Martha Co.'s stamp battery treated by wet crushing and copper plate amalgamation some 18,000 tons from the Martha Reef, worth probablyat least £4 per ton, but the average return was considerably less than £1 per ton, a sum which barely paid working, expenses, and consequently the shareholders were glad...

Jan 1, 1903

"The link between ore texture and mineral liberation has previously been established at a microscopic scale. To construct ore texture models that can be used in mining applications requires this relationship to be retained at a significantly larger scale. This is initially dealt with by finding a basic set of microtextures that form the elements of the ore textures at the next larger mesoscopic scale, simulating these mesotextures at a fine scale, then changing the support of the mesotexture simulations to generate the expected mining block/stope mesotexture distributions. Thus, a mutually exclusive and exhaustive set of spatially locatable mesotextures can be used to fully characterize the metallurgical properties of in situ material.A method that generates expected distributions of mesotextures for any mining block size or shape is proposed, and includes: (1) characterizing the spatial correlation of the set of mesotextures with a single covariance function; (2) generating multiple simulations of mesotextures at a fine scale; and (3) using the simulations at a fine scale to generate the expected mining block/stope mesotexture distributions. A case study, using the George Fisher sediment-hosted base metal deposit in Queensland Queensland, Australia, is developed to demonstrate the proposed methodology as well as show the inadequacy of off-the-shelf approaches.Mining-scale texture models can be used to improve the in situ discrimination of ore from waste by exploiting the joint spatial variability of grades and textures to quantify the expected metal recovery of in situ material, then calculate local marginal cut-off grades. An artificial case study is presented to demonstrate the changes in ore/waste selection when considering ore texture models compared to constant metal recoveries."

Jan 1, 2005

By S. L. Huang

The location and shape of potential failure surfaces in soil slopes were directly determined based on the stresses induced in the soil mass and the strength of the soil itself. Stress calculations were carried out by the finite element method with the Drucker-Prager nonlinear material model. The Mohr-Coulomb failure criterion and Mohr's circle stress analysis were then applied to the calculated stresses to determine the characteristics of the failure surface.

Jan 1, 1989

By Nicholas G. Theofilos

The Bahamian economy weathered the worldwide recession of the last few years better than most developing countries. This was mainly owing to the ties between the tourist industry of the Bahamas and the U.S. economy. The mineral industry played a minor role in the country's economy. The chief mineral exports included an increasing amount of petroleum products horn the country?s 500,000-barrel-per-day refinery, steel pipe, salt, and aragonite. A 60,001)-barrel-per-day desulfurization facility was completed by Bahamas Oil Refinery Co. (BORCO) in Freeport. The project included vacuum gas oil desulfurization, hydrogen and sulfur recovery, steam generation, water desalinization, and offsite facilities.

Jan 1, 1980

By K. V. Raj

In the mining industry, computational fluid dynamics (CFD) modeling is used extensively to simulate air flow in underground mines. CFD modeling of pollutant transport in open-pit mines is relatively new. Modeling the actual pit geometry of an open-pit mine and the open domain is complex. The complexity is primarily due to the faceted geometry of an open-pit mine with its numerous associated sharp features. Important issues that are not considered carefully at the geometry level are generally propagated to the subsequent processes. Several challenges and pitfalls are encountered in modeling pollutant transport in open-pit mines. These challenges and pitfalls are related to the geometry, meshing, boundary conditions, and turbulence modeling parameterization. An appropriate mesh selection is critical. A detail discussion of the meshing of the domain of an open-pit mine is presented in this paper. The selection of an appropriate turbulence model, such as kappa-epsilon (?-e), large eddy simulation (LES), Reynolds stress model (RSM), etc., to obtain the best possible solution is equally significant. This paper discusses the various challenges in modeling the pollutant transport process in an open pit and some of the approaches adopted to address these challenges.

Feb 27, 2013

By A. R. Miller, G. Desrivières, T. MacKinnon, H. Bursey, M. C. Bétournay, B. Replogle, D. L. Barnes, P. Laliberté

"A mine production locomotive, the world’s first applied industrial fuel cell vehicle, has been designed and tested in the context of a number of proof-of-concept projects supported by the Fuelcell Propulsion Institute, an international consortium of stakeholders dedicated to facilitate the commercialization of fuel cell vehicles.The locomotive’s simple electric-powered motor and controller system was ideal to study a number of requirements related to fuel cell power application: hydrogen power plant operation, underground hydrogen use, risk and regulatory requirements, production performance versus the conventional battery- powered locomotive version under measured duty cycles and production requirements, power plant design improvements for other fuel cell vehicles, and cost benefit aspects.This article will focus on the design and testing aspects of this project which has led to successful performance demonstrations of the vehicle under surface and underground conditions at two mines. It will also present information on the creation of a safe, reliable, and efficient power plant that fulfilled its design objectives, including longer productivity time for a given vehicle fill-up."

Jan 1, 2004

By W. D. Monaghan

Flame cutting and welding is one of the major causes of fires and explosions in underground U.S. coal mines. On May 20, 2006, a flame cutting operation at the Darby Mine No. 1 led to an explosion that resulted in five fatalities. On January 22, 2003, another explosion caused by flame cutting at the McElroy Mine resulted in three fatalities and three serious injuries. On June 22, 1999, a flame cutting and welding operation at the Loveridge Mine caused a fire that resulted in sealing of the mine for an extended period. Finally, on March 19, 1992, an explosion at the Blacksville No. 1 Mine that was caused by welding resulted in four fatalities. The National Institute for Occupational Safety and Health (NIOSH) conducted a study on fires and explosions in underground U.S. coal mines that were caused by flame cutting and welding operations to determine the root causes of these types of fires and explosions. The methodology included interviewing mining personnel who perform flame cutting or welding operations in underground U.S. coal mines and visiting mines to observe these operations, and MSHA reports of investigations and accidents statistics were analyzed. The results were used to identify and compare differences between flame cutting and welding practices and techniques in small and large mines, Eastern and Western mines, low seam and high seam mines, room and pillar and longwall mines, and between experienced miners and new miners. As a result of this study, best practices and interventions were developed to reduce the number of fires and explosions caused by flame cutting and welding. This paper provides a summary of this work. Disclaimer: The finding and conclusion in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupation Safety and Health.

Jan 1, 2009

By A. L. Williamson, G. Savci

Hydrologic assessments of existing and proposed waste rock stockpiles (WRS) are typically required for application of operating and closure permits at mine sites. The results of these assessments can be used to determine the applicability of the state groundwater permit program requirements to the operation and closure of these stockpiles. The objective of this hydrologic assessment was to ascertain whether or not the WRS at the Ajo Mine have a reasonable probability of discharging potential pollutants to the underlying aquifer under the operational mine conditions. The hydrologic assessment was performed based on an evaluation of climatic data, prediction of the net infiltration rate through the WRS and prediction of additional hydrologic factors such as the time required to deplete available moisture storage in WRS. The predicted net infiltration rates ranging from 0.13 inches/year (1.1x10-8 cm/s) to 0.24 inches/year (1.9x10-8 cm/s) are below the threshold value of less than 10-7 cm/s recommended by Hutchison and Ellison (1992) as being characteristic of conditions that produce no or negligible quantities of seepage. In addition, the total time required to deplete available moisture storage within the Ajo Mine WRS and for any potential seepage from the WRS to reach the underlying aquifer is estimated to range from 260 years to 1,950 years. Collectively, the climatological and geotechnical investigations and the hydrologic predictions demonstrate that the WRS at the Ajo Mine hydrologically do not have a reasonable probability of discharging pollutants to the underlying aquifer. As a result of this prediction, the stockpile will not be regulated under the state groundwater permit program and operational and reclamation requirements will be limited to managing surface water runoff.

Jan 1, 2002