As near surface deposits are depleted, it becomes increasingly apparent that we will have to mine deeper in order to meet future world demand for metals. / Along with deeper mining comes its associated challenges: increased stresses and seismicity, increased heat load and increased inefficiencies due to hoisting constraints and travel time. All of these challenges, and more, contribute to safety concerns, higher initial capital costs and higher operating costs, which combined, can make deep reserves uneconomic. / In order to meet these challenges, we must closely examine present deep mining infrastructures and operating practices with a view to learn and enhance upon "Best Practices". / This thesis will examine the challenges of providing ventilation within deep, hot mines. Specifically, we will examine Inco Limited's Creighton Mine. A current expansion at Creighton will see mining progress to the 7660 level within the next few years. A key issue, which arises, is the question as to whether Creighton will need a refrigeration system or can it continue to rely on its natural heat exchange capacity.

Spatiotemporal processes occur in many areas of earth sciences and engineering. However, most of the available theoretical tools and techniques of space-time daft processing have been designed to operate exclusively in time or in space, and the importance of spatiotemporal variability was not fully appreciated until recently. To address this problem, a systematic framework of spatiotemporal random field (S/TRF) models for geoscience/engineering applications is presented and developed in this thesis. / The space-tune continuity characterization is one of the most important aspects in S/TRF modelling, where the space-time continuity is displayed with experimental spatiotemporal variograms, summarized in terms of space-time continuity hypotheses, and modelled using spatiotemporal variogram functions. Permissible spatiotemporal covariance/variogram models are addressed through permissibility criteria appropriate to spatiotemporal processes. / The estimation of spatiotemporal processes is developed in terms of spatiotemporal kriging techniques. Particular emphasis is given to the singularity analysis of spatiotemporal kriging systems. The impacts of covariance, functions, trend forms, and data configurations on the singularity of spatiotemporal kriging systems are discussed. In addition, the tensorial invariance of universal spatiotemporal kriging systems is investigated in terms of the space-time trend. / The conditional simulation of spatiotemporal processes is proposed with the development of the sequential group Gaussian simulation techniques (SGGS), which is actually a series of sequential simulation algorithms associated with different group sizes. The simulation error is analyzed with different covariance models and simulation grids. The simulated annealing technique honoring experimental variograms, is also proposed, providing a way of conditional simulation without the covariance model fitting which is prerequisite for most simulation algorithms. / The proposed techniques were first applied for modelling of the pressure system in a carbonate reservoir, and then applied for modelling of springwater contents in the Dyle watershed. The results of these case studies as well as the theory suggest that these techniques are realistic and feasible.

One of the challenges mine operators have to face in large surface tailings disposal projects is to keep high tailings deposition rates under allowable values, while ensuring a sound and stable surface impoundment This is particularly important in the case of the upstream method of construction, in which perimeter dikes overlay soft unconsolidated deposits of fine materials (usually silts and days), where loss of shear strength could develop due to excess pore water pressure build-up. / This study offers a new approach for investigating the influence of tailings deposition rate over the structural behavior of upstream tailings dams, and its relation to the construction sequence and pond operation. A complex, yet practical method uses a nonlinear numerical algorithm, integrating a 1-dimensional self-weight consolidation model for fine grained materials, with a 2-dimensional stress-deformation finite element program for consolidation of earth structures. A beach profile equation is used to complete the structural geometry of the dam at various operating stages. The dam behavior is evaluated based on excess pore water pressure profiles, principal effective stress levels, and mobilized material strength. The time-dependent pond filling operation process and staged dam construction are simulated. / A case study from a large operating South African gold mine is used to perform simulations and parametric analyses. The behavior of the upstream tailings dam is assessed under both normal and increased slurry discharge rates. It is shown that under variable deposition rates, the present approach can help identify weak structural zones, and hence, improve the assessment of the structural dam safety. From such analyses, adequate tailings deposition rates conditions could be determined in advance for a variety of mill or pond operating conditions.

The development of decision support systems for equipment diagnosis has been found to be an iterative process whereby functionality and knowledge are continually added to a prototype until satisfactory performance is achieved. In order to reduce both the dependency on compiled knowledge sources and the number of prototype stages necessary to develop diagnostic decision support systems, this thesis examines, adapts and applies a set theoretical approach to mechanism diagnosis first developed in the field of Artificial Intelligence. The approach does not require the development of computational models to simulate equipment behaviour. / The set theoretical approach was applied to the development of a diagnostic decision support system for a semi-automated Atlas Copco Wagner ST-8B Load-Haul-Dump vehicle. Hypothesis sets were generated for the vehicle's hydraulic circuit and Deutz FL-413-FW diesel engine. A high level of diagnostic resolution was achieved for the hydraulic circuit, but limited resolution was achieved for the diesel engine. This was postulated to be due to the ratio of observable system outputs to input sub-systems, and the number of least repairable units making up each system. / Manual knowledge acquisition was undertaken in an underground mine to refine the diagnostic knowledge developed from the hypothesis sets and to add knowledge to discriminate between competing failure hypotheses. Heuristic failure likelihoods were used to rank hypotheses in order of frequency of occurrence. The knowledge base was implemented as a hypertext decision support system using HyperText Mark-up Language (HTML). The resulting decision support system is platform independent, upgradeable and able to be maintained by site personnel. The system is currently installed at surface level and at 1800 level at INCO Limited's Stobie Mine in Sudbury, Ontario. / The thesis makes a number of original contributions, the first two of which are of generic significance. It is the first work to apply set theoretical concepts to structural models of mobile mining equipment in order to diagnose faults. A number of modifications are advanced to the conventional trace-back analysis technique for generating contributor and normality sets, and heuristic guidelines are provided for estimating the costs and benefits of developing, implementing and maintaining diagnostic decision support systems. It is also the first work to formalise a decision support system in HTML and to suggest the application of company-wide internets ("intranets") to disseminate maintenance knowledge within mines.

Acoustic Emission (AE) techniques under laboratory testing conditions are used in order to understand the mechanical behavior and deformational processes of uniaxially compressed potash rock. Results obtained from the acoustic emission measurements are compared to crack development at preselected stress levels up to specimen failure. / It is observed that the fracture processes, mechanical behavior and acoustic emission response are dependent on the physical properties of potash rock. The mechanical behavior of potash rock displays two stress-strain trends under the same load conditions. Based on the acoustic emission rate, it was possible to delineate an approximate yield point of potash rock. However, a more detailed study of the acoustic emission amplitude and energy distributions showed that high amplitude events with long event durations are initially observed to occur near the yield point of the stress strain curves. These events are present prior to the yield point in specimens containing a high proportion of sylvite and after the yield point for monomineralic, halitic specimens. Finally, a classification scheme of crack morphology and systematic charts displaying the history of progressive crack development for all potash rock types has been developed.

This thesis deals with the problem of applying computer vision techniques in an underground mine environment. In particular, the problem of the localization and identification of oversized rock fragments prior to secondary breakage, following the initial drilling and blasting operation is addressed. The strategy employed is based on the methodologies developed for reconstruction and interpretation of range image data. Discrete rock pile images acquired using the NRCC/McGill laser rangefinder were used in this study. The main contribution of this thesis is the complete study of the paradigm which involves: range data acquisition, surface reconstruction, segmentation, and fitting of parametric shape models. The final representation obtained from the model, describing the spatial and geometric properties of each rock fragment and can be used to control an automated rock-breaking mechanism. To support the strategy developed, a number of experimental results at different processing stages are presented.

The modulus of deformation is undoubtedly the geomechanical parameter that best represents the mechanical behavior of rock mass. In particular, when it comes to underground excavations, this modulus becomes indispensable---whatever the type of design approach to be developed. / A literature review was conducted to explain the use of different types of rock mass classifications, as well as different types of in situ and dilatometer testing techniques for estimating and determining of modulus of deformation in the rock. / Series of in situ dilatometer tests were conducted to determine the modulus of deformation of the rock mass and to compare them with the physical properties results obtained by static and dynamic laboratory testing on core specimens. / The major goal of the work presented here is to find a correlation between in situ modulus of deformation with different type of rock mass classifications, physical properties of the rock and static and dynamic modulus of elasticity determined by laboratory testing.

Near-net-shape casting technology is an important research area in the iron and steel industry today. Various processes for near-net-shape casting of steel are currently being developed around the world. of these processes, twin-roll casting represents a major area of concentration. The main issues concerning design and operation of twin-roll casters are the metal-mould heat transfer, the metal delivery system and their possible effects in the homogeneity of solid shell formation and characteristics of the strips. / In the present work, interfacial heat fluxes between the roll and the solidifying metal have been evaluated in a pilot twin-roll caster used in the production of strips of low-carbon steel. This evaluation was based on an inverse heat transfer analysis and on readings of thermocouples inserted at different positions of the roll sleeve. / The variation of the roll-melt interfacial heat fluxes with time exhibited two different patterns, with single and double peaks, depending on the casting conditions. These interfacial heat fluxes were not uniform across the roll width. This result was consistent with predictions of a fluid flow, heat transfer and solidification model. / Computational fluid dynamics has been used to study different metal delivery systems for twin-roll casting. The in-house METFLO code has been adapted to simulate three-dimensional turbulent fluid flow, heat transfer and solidification in this type of process. The enthalpy-porosity technique was used to couple fluid flow and solidification phenomena. Different configurations for metal delivery systems have been studied. / This study has been applied to a pilot caster with a roll radius of 0.30 m, producing steel strips with thicknesses ranging from 4 to 7 mm, at relatively low casting speeds in the range of 4 to 12 m/min. The numerical predictions indicated that an extended nozzle, covering the full width of the caster and with horizontal inlets in the direction of the rolls surfaces, seems to be the best alternative for delivering liquid steel into twin-roll casters. / The solidification structures of strips produced in the pilot caster have also been studied. Their characteristics were analysed in terms of fluid flow and heat transfer inside the caster.

Recirculation of air is a widely used technique in general ventilation and air conditioning practise. / Interest in the application of controlled recirculation of ventilation air in mines has grown considerably in the last decade. This is evident by the number of controlled recirculation schemes which have been implemented or are being considered or planned in several countries and in different types of mines. / A detailed description is given of the operating and proposed schemes in South African gold and U.K. coal mines. This includes safety, dust filtration and blast contaminant removal systems. / The monitoring and feasibility methodology required to evaluate controlled recirculation for heat reclamation, and thus cost saving, in Canadian hard rock mines, is then examined. / Experimental work pertaining to air quality study, carried out at three mines, is described in detail, and backed up by extensive appendices. / The observed deposition of dust and reduction in gaseous pollutants concentration in exhaust shafts are analyzed and depicted in several figures and tables. / Simplified theoretical aspects of dust deposition, and statistical analysis of the obtained results, are outlined.

A 7.6 cm Laboratory Knelson Concentrator was used to evaluate the performance of one jig circuit (Snip Operation), four Knelson Concentrators circuits (Meston, Est Malartic, Aurbel and Hemlo) and one classification circuit (Agnico-Eagle). To determine the size-by-size unit performance of all units, total and gravity recoverable gold contents were measured in the feed, concentrate, tails, underflow and overflow. Sample dilution with silica was used as a tool to enhance LKC recovery in samples with a high sulphide content. / The data generated from the Knelson and the jig was used in a model designed to simulate an actual grinding and gravity circuit, and to predict its GRG recovery. It describes gold liberation, breakage and classification behaviour, and the GRG recovery performance curve of the chosen gravity unit. The simulation of the Snip circuit reproduced the recoveries obtained at the plant, and predicted that the use of a 20" Knelson, replacing the jig, would bring the recovery from 3 3% up to 43%. (Abstract shortened by UMI.)