A method to determine the amount of gravity recoverable gold in an ore sample with a 7.5 cm (3 inch) Knelson Centrifugal Concentrator is presented. The method is based on sequential comminution and recovery steps, the first at 100% $-$841 $ mu$m, the second at approximately 50% $-$74 $ mu$m and the third at final grind (typically 75 to 90% $-$74 $ mu$m). The mass processed depends on the gold grade and particle size, and commonly varies from 25 to 100 kg. / The method was used to determine the gravity recoverable gold in nine different ore samples. The grade of these ores ranged from 3 g/t to 45 g/t. Both massive sulfide and silicate ores were tested. Gold in the ores ranged from fine (90% $-$210 $ mu$m) to coarse (60% +841 $ mu$m). The amount of gravity recoverable gold ranged from 29 to 93%. Results from the proposed test compare favorably with mineralogical studies and data from industrial gravity recovery circuits. Some problems arose while testing the various ores; minor adjustments to the procedure were made to correct these. These corrections and other caveats for the test procedure are discussed. / This test yields an essential component of an algorithm that can be used to predict the amount of gold that can be recovered by installing a gravity circuit. This algorithm is referenced and an example of its use is included. Information from the test can be used to evaluate circuit performance and indicate if the performance is equipment or process limited. The test will quickly indicate if a gravity circuit is an option. / Results indicate that sizing material before it is processed with a Laboratory Knelson Concentrator leads to significant increases in recovery (48% without screen to 64% with). Industrial results are not yet available to verify this.

Pickforce sensing is a method demonstrating a promising future in automating coal mining machines. The method is based on the ability to determine the vertical location of a rotary cutting machine from the force measured at the point of contact between the machine and the coal seam. A major problem that may degrade the reliability of the pickforce data is vibration and is the major concern of this study. To analyze the effects of vibration on pickforce sensing, a vibration model of the cutting process is first developed. Then, a stochastic model of the coal seam is constructed. Subsequently, the vibration model is simulated in three stages. In these stages, the machine is assumed to be cutting through three types of coal seam: homogeneous, predetermined heterogeneous, and heterogeneous stochastic model. The first stage is conducted to prove that pickforce data always contains a degree of phase shift between successive half revolutions. This eliminates the effect of repetitive or orderly vibration that may mask the pickforce data. In addition, both the first and second stages are conducted to find ways to improve the reliability of pickforce data by adjusting a few parameters within the machine. The third stage is conducted to prove that the chaotic appearance of the pickforce data does not eliminate the features that are used to determine the vertical location. The present study concludes that vibration has a minor effect, and that pickforce sensing can be improved by adjusting some parameters of the cutting machine.

A new approach to underground excavation design at INCO's Manitoba Division was undertaken by incorporating ground and support monitoring, and numerical modelling into an empirical framework. / In the first phase of the study, a field measurement geomechanics guideline was developed for the Manitoba Division. Work in instrumentation led to the development of a new cable bolt monitoring device by INCO Ltd. and McGill University. This device has the ability to measure cable bolt performance reliably and at a low cost. As a result, a cost efficient and effective program is being implemented to monitor cable bolt layouts representatively. / The second phase of the project utilizes the computational power of numerical modelling to aid mine design of stope backs. Results from numerical modelling, presented in the form of stress signatures, suggest that there might be a correlation between back surface stability and calculated values of major and minor principal stresses. / By adding the tools of numerical modelling and instrumentation to traditional rock characterization data, a new data base for empirical modelling is established. The continual expansion of this database will lead to a more comprehensive approach to stope back design in the future.

This thesis reports the formulation and implementation of a finite element model, which is based on the so called Hybrid Stress Finite Element Method. The proposed formulation is based on stress as the primary unknown and is radically different from displacement-based finite element models. / Among the special features of the model are the casting of the element stiffness equations in terms of local rather than global coordinate system, the use of the active column method known as the "Skyline technique for the solution of equilibrium equations", and the use of fast and efficient mesh generation and alteration routines developed specially for geotechnical applications. / Verification tests carried out on problems in elasticity with closed form solutions show that the proposed method is accurate and that it requires relatively fewer elements than displacement-based finite element method to achieve the same accuracy. Results of case history studies done on two mine design problems matched those from other numerical modelling procedures within acceptable limits and showed that the proposed method can be used to solve geomechanics problems efficiently and realistically.

Stable mine backfill is necessary for safe working conditions, maximum ore recovery and underground and surface stability. Due to the fact that cement costs can be a significant part of the operating costs in large underground mines, the consumption of cement (or binder) should be minimized. Therefore, developing a safe and economical backfilling method for the large underground mining operations is very significant. / In this thesis, first laboratory tests and in-situ tests are implemented to determine backfill material properties and backfill stress distribution. The laboratory tests include high sulphide paste fill property tests and layered backfill tests. Second, a backfill finite element model is presented and it is validated by the results of laboratory tests and in-situ tests. Finally, by using this model, the following subjects are studied, (1) backfill stress distribution; (2) influences of backfill material properties and dimensions on backfill stability; (3) stress distribution of layered backfill; (4) optimum layered backfill. The results show that: (a) The variation of backfill material properties is quite large, the compressive strength of the layered backfill model is much higher than that of the non-layered backfill model, and the backfill vertical stress is much less than that anticipated by the formula, rhogH; (b) During the process of adjacent pillar recovery, the minor principal stress inside a backfill is tensile, and this tensile principal stress causes backfill failure and spalling near the exposed surfaces. The spalling size progressively increases with the height of the exposed surface, and a sliding zone creates and leads to backfill collapse; (c) Optimum backfill material should be high elastic modulus, high Poisson's ratio and low density. Optimum backfill size should be large depth and small width; (d) For layered backfill, no sliding zone occurs during the process of adjacent pillar recovery, so layered backfill can improve backfill stability. The optimum layered backfill should consist of strong layers distributed evenly with thicknesses of 1~2m and weak layers 2~2.5 times the thickness of the strong layers. This can save binder consumption by about 11%.

Haulage drifts are used for the transportation of blasted ore from the draw point to nearby ore pass or dumping point in sublevel mining systems. During production, haulage drifts are occupied by mine operators and haulage equipment. Therefore the stability of haulage drifts is important to the safe and uninterrupted production of a mining operation. It would be advantageous to know a priori how drift stability is influenced by mining activities in the proximity of the drift. This thesis presents the results of a study to examine drift stability and rock support system performance of a haulage drift, based on a case study of Garson mine from Vale Inco, Sudbury, Canada. The Mohr-Coulomb and Hoek-Brown models are the most widely used constitutive laws to describe the elastoplastic behaviour of rock materials under load. They are available in many numerical modeling codes including Phase2 and FLAC, which were selected to perform the numerical modeling analyses in this thesis. Consequently, the Mohr-Coulomb and Hoek-Brown constitutive models are reviewed in the first place. The finite element method is selected, together with Hoek-Brown model, to study the influencing factors of stability of haulage drift; finite difference method is chosen, along with Mohr-Coulomb model, to examine the performance of rock support system design. Much information is gathered from the mine site to help understand the entire mining environment. Parameters like rock mass character, mining plan and stress environment need to be known ahead of time in preparation for building the numerical model. Consequently, a geomechanical database named “Data Integrator for Mine Analysis and Design (DIMAND)”, including the most important features related to mining activities, has been developed. Numerical modeling results reveal that there is a dominant trend of low stress regime (postpeak) in the drift back, which results from the stoping activities in both cases of low and high horizontal to ver / Dans les opérations de minage en vrac, le minerai est transporté des points de soutirages aux chûtes à minerai grâce aux galeries de halage. Ces galeries de halage sont utilisés par le personnel quotidiennement. Donc, la stabilité des galeries de halage est primordiale pour garantir une production constante et sécuritaire. Il serait avantageux de savoir a priori comment la galerie de halage sera affectée par l'activité minière avoisinante. Ce mémoire décrit les résultats d'une étude qui examine la stabilité et la performance du soutènement d'une galerie de halage de la mine Garson, Sudbury Ontarion, Canada, propriété de Vale. Les critères de Mohr-Coulomb et de Hoek-Brown sont les plus utilisés pour décrire le comportement du massif rocheux soumis à des contraintes. Les logiciels Phase 2 et FLAC ont été retenus pour compléter l'analyse numérique de ce travail, car les critères de Mohr-Coulomb et de Hoek-Brown y sont intégrés. Pour étudier les facteurs influençant la stabilité de la galerie de halage, un code avec éléments finis (Phase2) utilisant le critère de Hoek-Brown a été choisi. Pour évaluer la performance du soutènement, un code avec différences finis (FLAC) utilisant le critère de Morh-Coulomb a été choisi. Beaucoup de données ont été obtenues de la mine Garson afin de comprendre entièrement la zone étudiée. Des paramètres tel les caractéristiques du massif rocheux, les plans miniers, le régime de contrainte, etc. sont requis pour construire le modèle numérique. Donc, une base de données géomécanique intitulée ‘Data Integrator for Mine Analysis and Design (Dimand)' répertoriant les caractéristiques critiques de l'activité minière a été développée. Les résultats de l'analyse numérique montrent un état de relaxation dans le toit de la galerie créé par l'extraction des chantiers dans les deux cas de faible et de fort rapport de la contrainte horizontale sur la contrainte

This thesis presents a study conducted to investigate the feasibility of using the existing Les Resources Camchib mill facilities to treat a new gold--copper ore called S-3. Analysis of the S-3 ore indicated that copper exists as chalcopyrite and that gold as free gold or in association with sulphides. The S-3 ore typically contains 0.3% copper and from 3.0 to 5.5 g/t gold. / The study involved both laboratory and plant testing. Four routes were investigated to treat the S-3 ore: flotation with the present circuit and reagents, flotation with the present circuit and new reagents, flotation at natural pH in a slightly modified circuit, and direct cyanidation. Alkaline pH flotation in the existing mill circuit with Aero 3477 and Xanthate 343 as collectors (the second route) gave the most promising copper and gold recoveries. A Laboratory locked cycle test indicated that a copper concentrate grading 18.4% Cu with 89.4% gold and 94.9% copper recovery can be obtained. Plant flotation test yielded a copper concentrate grading 16.9% Cu with 82.0% gold and 95.7% copper recoveries. The plant results were obtained using gravity circuit tail as the flotation feed. If recovery of coarse free gold in the gravity circuit is taken into account, the overall gold recovery is 87%.

This thesis is based upon field studies of automation research in Inco mines of the Ontario Division. It considers the advancement of technology and practice for underground hardrock mining automation, emphasizing the Load-Haul-Dump machine and its evolution and automation. It attempts to define the requirements for future mining processes, including the potential for extended teleoperation and autonomous operation of machines from safe vantage points. / Design issues including effective underground communications, automation amenable equipment, and process and workplace suitability are analyzed in detail and then related to solutions in design and practice. / This thesis concludes with discussions and recommendations towards solutions for future autonomous haulage for extreme long distance situations. Conclusions will highlight the successes the LHD has enabled in Canadian underground hardrock mines and its suitability to the task of optimizing automated haulage for use in safe, higher productivity automated processes that will optimize underground hardrock mining in Canada.

Cemented rockfill, CRF, is comprised of sized aggregate mixed with various types and amounts of binder materials. This type of fill with closely controlled specifications is employed for subsequent pillar recovery and improved ground support. / The goal of this study is to improve consolidated rockfill design for bulk mining methods, with Kidd Creek Mines, KCM, as a case study, from a functional and cost point of views. Cemented rockfill at KCM represents approximately 20% of the total extraction costs. Cost cutting initiatives however have to be mindful of the negative if not disastrous effects on grade, recovery, and ground stability that a decline in fill quality can produce. This dictates that any attempt to cut operational costs should be approached in a scientific and orderly fashion. This thesis describes consolidated rockfill improvement steps taken at Kidd Creek to obtain the highest quality fill at the lowest possible cost. / The main trust and achievements in this thesis include: (1) Extensive site investigation and mapping in drift driven through backfill have resulted establishment of four distinct zones in a typical rockfill mass. Structural rockfill design steps using the information obtained from field mapping are then established and implemented at KCM with great success which will be described during this thesis. (2) The main body of this thesis contains significant amounts of laboratory test work, 1750 test specimen, on lower cost binder alternatives. Some of the results obtained from the test work have been implemented at Kidd Creek since late 1992 and have resulted in considerable savings and improved dilution control. (3) Quality control measures and techniques in three main stages, surface plant, during transportation, and most importantly during placement are also established. (4) CRF structural design optimization steps are identified through extensive site observation and consultation with other operations. This covers all the steps that should be taken from start to finish to achieve the highest quality rockfill at the lowest possible cost. (5) Extensive field experiments are also carried out to obtain in situ mechanical and dynamical properties of a typical rockfill mass. / This work is based upon field and laboratory studies undertaken within the KCM over a 5 year period. The work has resulted in establishing quality control measures, mix design improvement, and structural design implementation at KCM to achieve the required physical characteristics at the lower operational cost. The in situ and laboratory test resulted in 35% unit cost reduction for KCM rockfill system within last 3 years and a saving of around $4 million on binder cost alone at a rate of $1.3 million/year. The total unit cost has dropped from $12/tonne in 1991 to around $7/tonne in 1995.

The process of filling the void created by underground mining activities with waste materials is defined as mine backfilling. Mine backfill has progressively integrated into underground mining operations to increase ore extraction, improve underground stability, and finally, to dispose of waste material. The high stresses associated with mining at depth in the Canadian Shield require innovative approaches to mine backfilling so as to permit structures to withstand the stresses both during and after mining operations. Not only are new or modified mine fill systems required, but also new techniques are needed to increase the speed of the mining cycle to optimize the mining operation. Over the last 5 years, in-depth research has been carried out to investigate the mechanical properties of gelfill and find out its advantages over cemented hydraulic backfill (CHF). Gelfill is an underdeveloped mine backfill material which uses an alkali activator such as sodium silicate in its binder. In this research the mechanical and physical properties of gelfill were studied by conducting a series of laboratory experiments such as uniaxial and triaxial compression tests, moreover, the microstructures of gelfill and CHF were analyzed by employing mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM).Tests were conducted to determine the strength evolution of cemented hydraulic backfill and gelfill prepared with various sodium silicate concentrations, and the mechanical behaviour of gelfill and cemented hydraulic backfill in various conditions was investigated and compared. These conditions were:•Sodium silicate concentration•Binder dosage•Pulp density•Mixing time•Curing temperature The results demonstrate that the rate of strength acquisition of gelfill samples containing an appropriate amount of sodium silicate is faster than that of CHF samples over a 28-day curing period. This leads to a 28-day higher mechanical strength in gelfill samples in comparison to CHF samples. The results also showed that the rate and total amount of drainage water of gelfill specimens is smaller than that of the CHF. The MIP test showed that the pore structure of CHF was altered by the addition of sodium silicate, and this alteration can contribute to better physical properties observed in gelfill specimens. The SEM pictures taken from gelfill and CHF samples revealed that the addition of sodium silicate can accelerate the formation of the hydration of binders, leading to better mechanical strength of gelfill specimens in comparison to CHF specimens.The results indicate that there is potential to improve the stability of the U/G mines and improve hydraulic fill economics. / Le processus de remplir le vide par du matériel stérile dans les activités minières souterraines est défini comme étant du remblai. Le remblai a commencé progressivement à intégrer les opérations minières souterraines pour augmenter l'extraction du minerai, pour améliorer la stabilité des souterrains et finalement pour se débarrasser du stérile. Les contraintes associées aux minages en profondeur dans le Bouclier Canadien requièrent de nouvelles approches pour le remblayage afin de supporter les contraintes pendant et après les opérations minières. Il n'est pas seulement requis d'avoir de nouveaux systèmes ou bien de les modifiés, mais aussi de nouvelles techniques pour optimiser les opérations et le cycle de la mine.Au cours des 5 dernières années, de profondes recherches ont été réalisées pour investiguer les propriétés mécaniques du remblayage par gel et de trouver ses avantages face au remblayage hydraulique cimenté. Le remblayage par gel est un matériau sous-développé du remblai qui utilise un activateur alcalin tel que du silicate de sodium dans son liant.Dans cette recherche, les propriétés mécaniques et physiques du remblai par gel ont été étudiées en effectuant une série d'expériences de laboratoires tels que des tests de compression uniaxiale et triaxiale, d'ailleurs, les microstructures du remblayage par gel et du remblayage hydraulique cimenté ont été analysées en utilisant la porosimétrie au mercure et la microscopie électronique à balayage.Les tests ont été effectués pour déterminer l'évolution de la résistance du remblai hydraulique cimenté et du remblai par gel préparé avec diverse solution de silicate de sodium, le comportement mécanique du remblai par gel et du remblai hydraulique cimenté a été comparé et étudié dans différentes conditions. Les conditions étaient les suivantes :•Concentration de silicate de sodium•Le dosage du liant•La densité de la pulpe•Le temps de mélange•La température de durcissement Les résultats démontrent que le taux d'acquisition de force des échantillons de remblai par gel contenant une quantité appropriée de silicate de sodium est plus rapide que celle des échantillons CHF sur une période de durcissement de 28 jours. Cela conduit en 28 jours à une résistance mécanique plus élevée dans les échantillons de remblai par gel en comparaison à des échantillons de CHF. Les résultats ont également montré que le taux et le montant total des eaux de drainage des spécimens de remblai par gel est plus petite que celle de CHF. Le test MIP a montré que la structure des pores de CHF a été modifiée par l'addition de silicate de sodium, cette altération peut contribuer à des meilleures propriétés physiques observées dans les échantillons de remblai par gel. Les photos MEB prises à partir d'échantillons de remblai par gel et de CHF a révélé que l'addition de silicate de sodium peut accélérer la formation de l'hydratation des liants, conduisant à une meilleure résistance mécanique des spécimens de remblai par gel en comparaison aux spécimens de CHF. Les résultats indiquent qu'il existe un potentiel pour améliorer la stabilité des mines U/G et d'améliorer l'économie hydraulique de remplissage.