When a hole is made underground, stress redistribution occurs in its vicinity. The resulting concentration of stress is highest at the boundary and approaches unity as distance from the hole increases. [...]

The gravity field of 300 sq. miles of the St. Lawrence Lowlands is investigated, particularly the anomalous gravity effect of the Delson and Tracy Brook faults. Theoretically this results from the mass distribution about the fault plane and is the difference between the observed gravity, corrected to sea level, and gravity according to the International Gravity Formula, at sea level and the latitude of the fault. [...]

This thesis is a report on the construction, calibration and use of the universal B.E.T. apparatus for the determination of the specific surfaces, and the adsorption-desorption isotherms of a vapour phase mercaptan on solid adsorbent systems. Examples are given for the determination of large (to 2000 m2jg) and small (200 cm2/g - 1 m2/g) specific surfaces. A gravimetric McBain-Bakr micro balance is incorporated in the B.E.T. apparatus for the determination of the adsorption isotherms of hexyl mercaptan vapour on synthetic sphalerite, zinc sulphide and zinc oxide. Adsorption isotherms are given for hexyl mercaptan on synthetic sphalerite at 25°C, 0.5°C and 50°C; on zinc sulphide at 25°C and 1.5°C and on zinc oxide at 25°C. All these isotherms are sigmoidal with a definite change in slope at the monolayero The amount of mercaptan adsorbed after the monolayer increases almost linearly with relative pressure to P/P0 = 0.8. Above this value the amount adsorbed increases very rapidly vrith relative pressure. Hysteresis loops appear in the isotherms for all adsorption-desorption cycles. These loops are completely reversible. It is not possible to desorb the mercaptan monolayer from any of the adsorbents even at elevated temperatures.

Over recent years, new methods have been developed to integrate uncertainty into the optimization of life-of-mine (LOM) production planning. This thesis makes use of two stochastic optimization methods: simulated annealing (SA) and stochastic integer programming (SIP); which are implemented in the context of the requirements of mining applications through the use of stochastic simulation to model uncertainty. For the case of SA, the second chapter of the thesis documents the case of a copper deposit where ten simulated realizations are sufficient to provide stable LOM optimization results. In addition, the study shows that the selected true optimal pit limits are larger than the ones derived through conventional optimization. Stochastically optimized pit limits are found to be about 17% larger, in terms of total tonnage, than the conventional (deterministic) optimal pit limits. The difference adds one year of mining and approximately 10% of additional net present value (NPV) when compared to the NPV of conventional optimal pit limits and a production schedule generated stochastically with the same SA algorithm. In the third chapter of the thesis, the SIP based optimizer is used with the purpose of integrating uncertainty into the process of pushback design. Results show the sensitivity of the NPV to the design of starting and intermediate pushbacks, as well as the pushback design at the bottom of the pit. The new approach yielded an increment of ~30% in the NPV when compared to the conventional approach. The differences reported are due to the different scheduling patterns, the waste mining rate and an extension of the pit limits which yielded an extra ~5.5 thousand tonnes of metal. / Depuis quelques années, de nouvelles méthodes ont été développées pour intégrer l'incertitude dans l'optimisation de la planification de la production de la vie-de-mine i.e. life-of-mine (LOM). Cette thèse se sert de deux méthodes d'optimisation stochastique : recuit simulé (RS) et programmation en nombres entiers stochastique (SIP); les deux méthodes sont programmées dans le cadre des besoins des applications d'exploitation de la simulation stochastique et modélisation d'incertitude. Pour le cas de RS, le deuxième chapitre de la thèse décris le cas d'un dépôt de cuivre où dix réalisations simulées sont suffisantes pour fournir des résultats stables d'optimisation de LOM. En outre, l'étude prouve que les véritables limites optimales choisies de mine sont plus grandes que celles dérivées par l'optimisation conventionnelle. Des limites stochastiquement optimisées de mine s'avèrent environ 17% plus grandes, en termes de tonnage total, que les limites optimales (déterministes) conventionnelles de mine. La différence ajoute un an d'exploitation et approximativement 10% de valeur nette additionnel (NPV) une fois comparée au NPV des limites optimales conventionnelles de mine et une cédule de production produit stochastiquement avec le même algorithme de RS. Dans le troisième chapitre de la thèse, l'optimiseur basé sur SIP est utilisé en vue d'intégration de l'inceritude dans le processus de la conception de fosses emboîtées. Les résultats montrent la sensibilité du NPV à la conception de fosses emboîtées de commencement et intermédiaires aussi bien que la conception de la fosse emboîtée du fond de la mine. La nouvelle approche a produit une augmentation de ~30% dans le NPV une fois comparée à l'approche conventionnelle. Les différences rapportées sont dues aux différents cédules de production, du taux de décapage du stérile et d'une extension des limites de la mine qui ont produit ~5.5 mille tonnes supplémentaires

This thesis presents a novel application of structural reliability concepts to assess the reliability of mining operations. “Limit-states” are defined to obtain the probability that the total productivity — measured in production time or economic gain — exceeds user-selected thresholds. Focus is on the impact of equipment downtime and other non-operating instances on the productivity and the economic costs of the operation. A comprehensive set of data gathered at a real-world mining facility is utilized to calibrate the probabilistic models. In particular, the utilization of Bayesian inference facilitates the inclusion of data — and updating of the production probabilities — as they become available. The thesis includes a detailed description of the Bayesian approach, as well as the limit-state-based reliability methodology. A comprehensive numerical example demonstrates the methodology and the usefulness of the probabilistic results.

Multiple-point simulation (MPS) methods have been developed over the past decade as a mean to generate stochastic simulations while reproducing complex geological patterns, such as high-grade depositional veins, groups of high-grade lentil shaped orebodies, or the spatial geometries and patterns of diamond-bearing kimberlite pipes. This thesis compares two MPS methods by modelling the geology of a diamond pipe located at the Ekati mine, NWT, Canada. The single normal equation simulation algorithm SNESIM, which captures different patterns from a training image (TI), and the filter simulation algorithm FILTERSIM, which classifies the patterns founded on the TI, are considered in this study. Both methods are used to generate stochastic simulations of a four-category geology model containing crater, diatreme, xenoliths and host rocks. Soft information about the location of the host rock is also used. Both MPS methods reasonably reproduced the geometry of the pipe, as per the TI used (crater and diatreme rock units); however, the methods differed in the proportion and location of the xenolith bodies within the pipe. The validation of the simulated results provided by the above methods shows a reasonable reproduction of the data proportions for all geological units considered; the validation of spatial statistics, however, shows that although simulated realizations from both methods reasonably reproduce the fourth order spatial statistics of the TI, they do not reproduce well the same spatial statistics of the available data (when these differ from the TI). An interesting observation is that SNESIM better imitates the shape of the pipe, whereas FILTERSIM reaches a better reproduction of the xenolith bodies. / Les méthodes de simulation multi-points ont été développées au cours de la dernière décennie afin de générer des simulations stochastiques reproduisant des structures géologiques complexes, comme par exemple des dépôts en veines à hautes teneurs, des groupes de formations lenticulaires à hautes teneurs, ou les géométries spatiales et structures de gisements diamantifères de kimberlite.Cette thèse compare deux méthodes multi-points pour modéliser la géologie d'un gisement diamantifère situé dans la mine Ekati, dans les Territoires du Nord-Ouest du Canada. Les algorithmes de simulation SNESIM, capturant les structures d'une image d'entraînement, et FILTERSIM, classant les structures trouvées sur une image d'entraînement, sont considérés dans cette étude et utilisés pour générer des simulations stochastiques d'un modèle à quatre catégories : cratère, diatrème, xénolites et roches hôtes. On utilise aussi des informations qualitatives sur la position de la roche hôte. Les deux méthodes reproduisent la géométrie du gisement de manière satisfaisante, conformément à l'image d'entraînement utilisée (le cratère et les diatrèmes); cependant, les méthodes donnent des résultats différents quant à la proportion et la position des corps de xénolite dans le gisement. La validation des résultats des simulations par les méthodes mentionnées ci-dessus montre une reproduction raisonnable des proportions pour chaque catégorie considérée, mais la validation des statistiques spatiales montre que, même si les simulations produites par les deux méthodes reproduisent les statistiques d'ordre quatre de l'image d'entraînement, elles ne reproduisent pas celles des données disponibles (lorsque ces statistiques diffèrent de celles de l'image d'entraînement). Il est intéressant de noter que SNESIM reproduit mieux la forme du gisement, tandis que FILTERSIM permet une me

This work develops a backfill design procedure aimed to facilitate the optimization of an available mine material in order to meet target objectives in a particular mining role. This required the compilation and analysis of data on fill usage, established design procedures, physical and geomechanical properties, testing techniques and procedures, as well as behavioural modelling methods. / A backfill classification system is proposed based upon size distribution. A series of design equations are presented which relate to this system. These equations represent the means by which backfill geomechanical behaviour can be related to physical properties. This is considered to be fundamental to an effective backfill design procedure. Derivation of the equations has been based upon analysis of data from a program of laboratory and in situ testing conducted in ten operating Canadian mines by the author, together with other published work. / The in situ testing required the development of a pressuremeter testing procedure novel to underground mining. The theoretical basis for the employment of pressuremeter data has been examined and behavioral equations have been developed to describe the deformation and stress history during a backfill material test. In addition two new equations have been developed for the analysis of pressuremeter data. The in situ data collected has been correlated with laboratory derived geomechanical data for the same backfill materials. / The geomechanical properties associated with the proposed backfill classifications have also been related to their influence on backfill behaviour in three mine backfill roles: free standing stability during pillar recovery in bulk mining methods; dynamic interaction with stope walls in rockburst prone ground; and ability to reduce stresses in highly stressed rock masses. This work has been based on new and established modelling methods and aims to provide insight into the effectiveness of the backfill classes in these roles of growing practical significance.

In order to develop a philosophy and set of methods which would allow mines to be operated more effectively, a study was initiated to determine how time-based methods used in manufacturing could be adapted to mining. The study was done in collaboration with Inco Ltd. A review was made of both lean manufacturing and time-based competition methods. In addition, continuous programs such as Total Quality Management and Total Preventive Maintenance were studied. This study showed that time based principles, cellular mining, and total preventive maintenance had the most promise for adoption in mining. Simulations of three different mining methods under different scenarios and cost analyses were done to demonstrate the viability of these methods. The conclusions were the following. (1) Time based principles lead to greater profitability, and thus, should be used to drive mine planning and production. (2) Cellular mining leads to more efficient mining production. (3) The adoption of a comprehensive Total Preventive Maintenance program is needed to improve equipment availability and to complement cellular mining.

This thesis proposes a morphological complexity index for use in classifying orebodies. Formulated and tailored for application on underground steep clipping narrow base metal orebodies from Inco Limited's Manitoba Division, the complexity index was proved transferable to the base metal deposits of Inco Limited's Ontario Division. Thus it appears that the index could be applied to various styles of mineralization and orebody morphology. / The complexity classification was designed to aid in geologic control and subsequently improve mining method performance. Motivated by an industry wide move from selective mining to bulk mining, to increase productivity and improve safety. It is intended that development and application of an orebody complexity index will increase the understanding of geology and prevent the sacrifice of selectivity, minimizing dilution and ore loss. With the advent of automation, simplification in mining is necessary and thus more intelligent design and control vital. This thesis offers one means by which MDPPC (Mine Design, Planning and Production Control) could be further integrated with geological understanding to achieve such an end. / The thesis provides explanation of how such a complexity index can be used to understand mining method performance and be used for more successful mine design.

Acid mine drainage (AMD) is one of the largest problems facing the mining of base metals in Canada today. It results in the leaching of toxic heavy metals from waste rocks and tailings into the environment. Solidification/stabilization is a process whereby hazardous wastes are chemically stabilized and their handling properties improved. The objective of the project was to stabilize two tailings obtained from base metal mines in Quebec by adding varying proportions of lime and fly ash to them. The fixing capabilities of the two additives were tested by a modified Toxicity Characteristic Leaching Procedure (TCLP) test after 1, 14 and 35 days of curing. Mineralogical changes were monitored by the x-ray diffraction (XRD) analysis of 6 selected samples. / Results indicated the capability of lime-fly ash binders in the immobilization of heavy metals. XRD analysis showed the formation of gypsum and the gradual decline in pyrite content in most of the samples. The mineral ettringite was not detected, probably due to the relatively low pH of the samples and a deficiency in reactive aluminum. Hence, the results suggest the existence of other phases, possibly amorphous calcium silicates, which were responsible for the reduction in leachability.