The factors influencing the long term stability of mine workings at Sherburn-in-Elmet have been isolated and studied through laboratory experimentation and theoretical studies. A series of physical models were constructed and tested in order to appreciate the behaviour of the strata overlying the gypsum deposit in the event of a single or multiple gypsum roof beam failure. The effect of water on the long term stability of gypsum pillars was investigated through long term creep testing of gypsum specimens submerged in mine water. The time-dependent deformation of submerged gypsum was appraised mathematically and an empirical equation was developed for the description of creep behaviour. A procedure for the prediction of failure time of submerged gypsum specimens under a constant load was developed and graphical and computerised versions of solutions are presented. The influence of the satinspar bands on pillar degradation was investigated through servo-controlled testing of simulated pillars. A possible roof structure, a linear arch, was modelled photoelastically and the presence of tensile stresses in the structural elements was proved. Finite element modelling studies were carried out to demonstrate separately the change in the state of stress around the workings due to a roof beam failure and in the pillars due to the presence of satinspar bands.

Limiting the amount of ore dilution prior to entering the process stream is the goal of any mining operation. Narrow vein longitudinal retreating mining methods are especially susceptible to hanging wall and footwall dilution due to the wall overbreak. Understanding the factors which influence the stability of these walls can help a mining engineer design stopes that minimize dilution. This thesis presents the results of a study to examine these influential factors and reveals the process used to construct an empirical model capable of estimating dilution for a specific stope. This work is centered on a case study of Agnico Eagle Mines Ltd. Lapa mine located in Preissac, Quebec.Possessing a means to properly measure and quantify dilution is an essential part of this study. An in depth review of the various techniques is presented with the concept of Dilution Density being chosen as a means to quantify dilution. In order to determine which factors influence dilution, a review of existing literature, including modelling studies is undertaken. With careful review of the mining practice and geological environment, the most important of these factors are identified. One of these factors, stope strike length in narrow vein retreat mining, is not thoroughly explored by existing publications; and, in order to better understand this factor a numerical model is constructed.Before constructing this numerical model it is necessary to find an adequate means to organize and interpret the copious amounts of data retrieved from the mine site. Data such as geotechnical drill holes, stope reconciliation data, and stope construction details are integrated into a purpose-built geomechanical database. Named the "Data Integrator for Mine Analysis and Design (DIMAND)" the database software package provides easy access to important data and eases the construction of numerical models.In order to fully understand the influence of stope strike length on unplanned ore dilution, a numerical model is constructed. Due to the geometry of the problem, it is necessary to perform the analysis in three dimensions. The finite difference code FLAC3D is employed to construct a model based on rock mass properties and stope constructions present at Lapa mine. With strain softening behaviour common in rock masses and the Lapa rock mass being one regularly subjected to large strains, a strain-softening constitutive model is employed in the FLAC3D model. This model reveals that larger stope strike lengths are prone to generate larger volumes of dilution into a newly opened stope whereas shorter strike lengths are less prone to dilution. The model also explores the effects of a retreat sequence on overbreak; revealing that primary stopes are slightly more prone to overbreak than secondary stopes. These studies aided in the development of an empirical model that provides estimates for stope overbreak tonnages. The development of the empirical model is explored in detail from early models with small sample groups and simple mathematical constructions, to the final model which employed 86 stopes and statistical software to identify important relationships between seemingly independent factors. Through the use of this model engineers can now plan stopes with knowledge of how each parameter influences overbreak and production and scheduling personnel can plan production goals with increased confidence. / Limiter le montant de dilution dans le flux de processus est l'objectif de toute exploitation minière. Les méthodes d'exploitation minière en veine mince par retraite longitudinal sont particulièrement sensible à la dilution en raison de la forme élancée des chantiers. Comprendre les facteurs qui influencent la stabilité de ces murs peuvent aider un ingénieur des mines a réduire au minimum la dilution. Cette thèse présente les resultants d'une étude visant à examiner ces facteurs d'influence et révèle les processus utilizes pour construire un modèle empirique permettant d'estimer la dilution pour un chantier spécifique. Ce travail est centré sur une étude de cas de la mine Lapa de Agnico Eagle Mines Ltd, situé à Preissac, Québec. Avoir en sa possession un moyen de bien mesurer et de quantifier la dilution est une partie essentielle de cette étude. Un examen approfondi des différentes techniques est présentée avec le concept de Densité de Dilution choisi comme un moyen de quantifier la dilution. Afin de déterminer les facteurs qui influencent la dilution, une revue de la littérature existante, et les études de modélisation est effectuée. Avec un examen attentif de la pratique des mines et de l'environnement géologique, les plus importants de ces facteurs sont identifiés. Une de ces facteurs, la longueur du chantier dans le secteur minier veine mince retraite, n'est pas exploré par la publication en vigueur, en vue de mieux comprendre ces facteurs un modèle numérique est construit. Avant de construire ce modèle numérique, il est nécessaire a trouver un moyen approprié pour organiser et interpréter la grande quantité de données extraites de la mine. Les données telles que les trous de forage géotechnique, la réconciliation des données du chantier, et les détails de construction du chantier sont intégrés dans une base de données. Nommé le "Data Integrator for Mine Analysis and Design (DIMAND)" le logiciel permet d'accéder facilement à des données importantes et facilite la construction de modèles numériques.Pour bien comprendre l'influence de la longueur du chantier sur la dilution, un modèle numérique est construit. A cause de la géométrie du problème, il est nécessaire d'effectuer l'analyse en trois dimensions. Le code FLAC3D différences finies est utilize pour construire un modèle basé sur les propriétés de la masse rocheuse et constructions chantier présents à la mine Lapa. Avec des comportements adoucissement commune dans les roches et la masse rocheuse Lapa régulièrement soumis à une grande souches, une modèle d'adoucissement de comportement est utilisé dans le modèle FLAC3D. Ce modèle révèle que les grandes longueurs du chantier sont susceptible d'introduire des volumes plus élevés de dilution dans un chantier récemment ouvert alors que la grève des longueurs plus courtes sont moins sujettes à la dilution. Le modèle examine également les effets d'une séquence de retraite sur la profil du dilution, révélant que les chantiers primaires sont légèrement plus enclins au dilution que les chantiers secondaires.Ces études ont contribué au développement d'un modèle empirique qui donne des estimations de dilution. Le développement de ce modèle est étudié en détail à partir des premiers modèles avec des petites groupes de chantiers et des simples constructions mathématiques, le modèle final, qui employait 86 chantiers et des logiciels statistiques pour identifier les relations importantes entre les facteurs en apparence indépendants. Grâce à l'utilisation de ce modèle ingénieurs peuvent maintenant planifier les chantiers avec une connaissance de la façon dont chaque paramètre influence la dilution et de la cote production et planification ils peuvent planifier les objectifs de production avec une confiance accrue.

Mining is one of the oldest industries, but it is only during the last 50 years that operations have been carried to depths where problems of temperature and ground pressure require special study. Temperature problems can be solved by increasing the now of ventilating air and or conditioning the air by refrigeration. Controls of this nature are limited only by economic factors. Pressure-increases with depth, however, present a far more complicated and difficult problem. The stress distribution can only be postulated since measurement of stresses in rock in situ is at present only in the initial stages of development.

The first part of this thesis reviews in detail the state of stress due to pore water pressure, and effective stress methods in wet grounds in an attempt to present a global perspective on the subject. Through the second part of the thesis, a 2-dimensional finite element program has been developed for stress and stability analysis of wet rock and soil masses. The program uses the effective stress method which allows for a unified approach for dry and wet analysis. It computes the displacements, effective stresses and excess pore water pressure. Safety levels are then calculated in the postprocessor using rock and soil ultimate strength parameters. Three failure criteria are available. These are: Mohr-Coulomb and Hoek-Brown. The effective stress method used allows for the computation of pore water effect due to both volumetric and deviatoric changes. A case study of an open mine slope has been carried out to demonstrate the application of the developed program to practical problems.

A model of the sequence of decisions required for mine development and production has been formulated and is operated as a computer-based game. The Mine Manager is an operations research game in which the user assumes the role of mine management in the exploitation of a mineral deposit. Potential applications of the game lie in experimentation, policy formulation and education in mine economics. The Mine Manager is described using the terminology of games. / The selection of parameters and of the level of detail in the model reflects a compromise between realism and simplicity. At the development stage, the selection of project specifications concerns the mining method and capacity installation. Decisions on cut-off grade and/or cut-off value, capacity utilization, the sequence of mining, stockpiling and expansion are made during the mine life. Decision making takes place within a framework provided by an abstraction of the operating environment of a mine, and must comply with a set of rules. These rules ensure that only feasible decisions are made. Within this constraint, the model offers a high degree of flexibility in setting the values of the decision variables. / The Mine Manager combines elements of geology, mining, management and gaming. Conditional simulation is used to generate grades of copper, zinc and gold in a massive sulphide deposit. Mining operations in both underground and open-pit mines are modelled, and hypothetical capital and operating cost functions are developed for the mine and mill. A pricing model generates new price series for each run of the game. / The Mine Manager is operated interactively on a microcomputer through the use of modular software. The user interface and a sample run of the game are described, and the information displays created by the game are presented.

This thesis reviews, analyses and classifies extraction methods and sequences used in steep, tabular orebodies in Ontario hardrock mines and how new bulk mining techniques have affected them. / The thesis examines, as a case study, the complexities of sequencing the extraction of the Hemlo orebody through three adjacent mines and details the planning and monitoring of extracting one section of the David Bell orebody. It examines the use of numerical modelling as a tool in extraction sequence planning and demonstrates how, in conjunction with an instrumentation program, the results assist successful completion of the plan. / The thesis concludes that bulk mining sequences have increased resource extraction and productivity, lowered costs and improved ground control aspects of extraction planning; but have compromised grade control. This aspect should be improved to maximize the economic benefits. In addition, as automated or continuous mining methods are developed, their benefits should be analyzed in the context of overall sequence planning objectives.

This thesis addresses those mine design considerations applied to mining with backfill at Denison Mines Ltd., Elliot Lake, Ontario, and reviews the specific circumstances of pillar recovery during 1985 to 1988. The rock mechanics elements of the project are presented with a case history of pillar recovery in a specific stopping district (cost center). / The use of hydraulically placed cemented tailings to recover additional ore reserves from rib pillars in a room and pillar mine required a design rationale beyond the traditional empirical approach. / The work undertaken to achieve this improved design includes both the study of the physical properties of the backfill, and its overall support characteristics. Design techniques involving analytical and numerical methods were coupled with ground behaviour data from daily monitoring and rock instrumentation. / The backfill cost center used as a case study is back analyzed with reference to a new proposed pillar strength classification system. Improvements in ground stability are assessed and comparisons with rock burst alleviation studies are made. The geomechanical parameters involving pillar design are discussed at length in the context of rock mechanics theory. This thesis attempts to demonstrate the manner in which an integrated design rationale may be employed in a room and pillar mining environment.

This thesis presents a research program designed to evaluate the performance of the gold gravity circuit at Les Mines Camchib Inc. / A detailed sampling program was conducted on the grinding and gravity circuits. Samples were screened and each size class was processed on a Mozley Laboratory Separator to determine free gold content. The performance of pinched sluices, Knelson concentrators, and a riffleless table is characterized on the basis of particle size, shape and liberation of gold. The amount of total gold and free gold in each size class of grinding circuit streams was also determined. / The pinched sluices recover from 8 to 17% gold in 4.8 to 7.3% of the mass. The double sluice recovers slightly more gold at a higher yield than the single sluice. In addition, the double sluice performed better at a higher feed density. / The 76 cm (30") Knelson recovers 62 to 71% of the feed gold, at very high upgrading ratios (326 to 480). Free gold recovery is high, generally above 90% for all size classes. Gold recovery decreases when wash water pressure is lowered from 100 to 40 kPa; a 90 minute cycle time does not cause concentrate overload, i.e. decreased gold recovery. / The 19 cm (7.5") Knelson used in the gold room yielded 90% recovery. Reprocessing the tails in the same unit give only a marginal gold recovery, suggesting that a single pass is adequate. Fine gold losses on the riffleless table are significant, especially in $-$38 $ mu$m (400 mesh).

This thesis examines rock mass characteristics of the Bousquet 2 mine, and reviews ground reinforcement practices applied to tunnel and stope hanging-wall support. The effectiveness and suitability of the installed support elements is examined through numerical modelling techniques and instrumentation. / The second part of the thesis examines mechanisms influencing stope hanging-wall stability. Through a case study incorporating hanging-wall instrumentation, numerical modelling, and laser survey of the mined stope profiles, the extent of hanging-wall over-break in both primary and secondary stopes is studied.

For centuries human society has relied on coal as a principal source of fuel for heat and power. Extraction of this valuable fuel has always been influenced by control over hazards such as water inflows and potentially explosive dust and methane gas. A major focus of the research has been on methane including: methane properties of seams, insitu and laboratory testing; methane emissions; investigation of operational issues (e. g. Phalen 7 East); and refinement of prediction models. / This thesis gives an overview of methane and ventilation research covering the following aspects: Defining coal seam characteristics: specific emissions---the relationship between methane content, coal 'rank' and depth; the geothermal gradient; insitu gas pressure; and associated hydrocarbon content of mine air samples analyzed. Defining the performance of Sewergate ventilation, particularly on Phalen 7 East. Sewergate ventilation is a marriage between a typical 'U' and a bleeder ventilation system. Underground measurements including a novel use of 'tubebundles', have provided a clearer understanding of factors affecting Sewergate performance. (Abstract shortened by UMI.)