Thesis (Professional Degree)--University of Missouri, School of Mines and Metallurgy, 1926. / The entire thesis text is included in file. Typescript. Title from title screen of thesis/dissertation PDF file (viewed October 5, 2009) Includes index (p. [35-38]).

<p> Metal production in the United States contributes significantly to the national and global economies due to resource demands. As mineral reserves are becoming scarce, demand has driven mining companies to operate at increasing depths underground. Along with this, production has continued to increase year after year, as lower grade ores are excavated economically. However, the increased mining depths and increased production have resulted in enlarged heat loads in the underground mine environment. Increased heat loads can result in temperatures, which are too high for mine workers to safely work. This may cause heat related illness, injuries or even death. Mine operators must pursue heat reduction strategies in order to maintain safe temperatures to protect mine workers. </p><p> There are a number of heat mitigation methods and strategies which mine operators can implement. The most common means is through the use of ventilation to provide cool air volumes to reduce the heat load and dilute the contaminants generated in the production workings below their threshold limit values (TLV). This can be done by increasing the fresh air volumes through surface accesses such as shafts, raises, adits, ramps, or other mine entrances. When ventilation alone cannot provide acceptable climatic conditions in the production workings and throughout the mine, artificial cooling methods need to be used. These methods can be very effective, however, they require large capital investments, continuous maintenance, and additional operating costs. This includes central cooling, spot cooling, and micro-climate cooling systems. Though reducing the heat load is effective, another strategy is to reduce the source of the heat generation. One such source is the heat generated by diesel engine equipment fleet. This can be decreased by switching to a battery/electric engine equipment fleet. All of these strategies can be compared based off their heat reduction, temperatures, and operating costs. This study does exactly this by using an underground metal mine&rsquo;s ventilation system to compare various scenarios, and identify the most effective cooling method or system that can be used in deep and hot US mines.</p><p>

<p> Ground conditions at underground gold mines in Nevada range from good to extremely poor and implementing the most appropriate ground support can be challenging. Existing empirical ground support design methods were developed predominantly from experience in tunneling or more competent ground, making them less applicable to underground gold mining in Nevada. This research presents empirically derived support guidelines from experience at 5 underground gold mines in Nevada, including: discussions with engineers and miners, review of ground control management plans and consulting documents, and roughly 400 ground control case-studies. Support design recommendations are based on the Weak-Rock Mass Rating (W-RMR) which is a modified Rock Mass Rating (RMR) classification incorporating the Unified Soil Classification System (USCS) for very weak rock masses. Ground support recommendations include rock bolt pattern support pressure, rock bolt length category, excavation surface support, and excavation strategy.</p>

<p>The flow of thickened mine tailings within a tailings storage facility is a complex interaction between unconstrained viscoplastic free surface flow and possible coarse particle settling within the flow depth. The broad focus of this work is developing a robust framework for modelling tailings beach flows. Modelling tailings flow evolution in three dimensions within a storage facility will ultimately provide greater understanding of beach slope formation, as well as the ability to optimize deposition sequencing. This thesis focuses on the first step of developing a tailings model considering the transport and settling of mono-sized coarse particles within two dimensional (length and depth) laminar viscoplastic carrier fluid sheet flow. The 2D model consists of a semi-implicit finite difference shallow water sheet flow model for predicting the viscoplastic flow depth and discharge down the beach. The coarse particle transport and hindered settling within the flow are predicted using a scalar transport model. The scalar transport and shallow water flow model are coupled together using coarse particle rheology augmentation. Two key novel advancements were made through the model development. The first is coupling the coarse particle rheology augmentation within the free surface flow to the coarse particle hindered settling behavior with depth. This coupling allows for the rheology augmentation due to the coarse solid fraction to be incorporated seamlessly into both the fluid flow solver and the particle settling model. The second advancement is expanding the rheology augmentation and hindered settling coupling to particle flows beyond the Stoke?s flow regime. Ultimately, the 2D model results are compared against Spelay?s (2007) laminar settling experimental measurements for oil sand thickened tailings (TT) and composite tailings (CT) slurries, along with Spelay?s 1D settling model. The 2D model provides improved prediction of the particle concentration profiles within the fluid flow compared to the 1D model. The 2D model is also able to predict the increase in flow depth due to the particle accumulation on the bed, as well as the downslope particle transport and settling behavior.

<p> Unstable failure in underground mining occurs when a volume of material is loaded beyond its strength and displaces suddenly. It is recognized on various scales, from small rock bursts to the collapse of pillars or entire sections of a mine. The energy that is released during smaller scale events is manifested through the ejection of material, which can pose a hazard to the safety of miners. Larger scale events generate seismic waves as mine workings are damaged and may entrap miners or terminate production. </p><p> This dissertation focuses on the analysis of unstable failure in an underground room and pillar mining environment. The potential for violent pillar failure is assessed using numerical modeling techniques and a parametric approach to loading conditions and material strength properties. The magnitude of instability is quantified by calculating the release of kinetic energy that occurs as failure progresses in each simulation. </p><p> Fundamental mechanisms associated with the release of kinetic energy are analyzed in a series of finite difference models, and the results are compared with analytical solutions to illustrate the applicability of the energy calculations to increasingly complex modes of failure. Back analyses are performed on two room and pillar mine collapse events from the western United States by constructing large-scale models and reproducing widespread failure. The values of energy released in two-dimensional models are extrapolated by assuming a depth of failure in the third direction, and the total energy values are compared to the documented seismic magnitudes from each collapse through empirical equations. With further development of this numerical modeling approach, energy consideration may be used to study the potential for instability in a wide variety of mining excavations and identify the associated range of hazards.</p>

<p> This research shows that worst-case methane-air detonation loading on coal mine seals could be more severe than the design loads required by federal regulations, and therefore mine seals should be designed with sufficient ductility beyond the elastic regime. For this study, reinforced concrete mine seals were designed according to traditional protective structural design methods to meet the federal regulation requirements, and then the response to worst-case loads was analyzed in a single-degree- of-freedom model. Coal mine seals designed to resist the regulation loads elastically experienced support rotations up to 4.27 deg when analyzed with the worst-case loads. The analysis showed that coal mine seals designed to satisfy the federal regulations can survive worst-case methane-air detonations if they have sufficient ductility, but will undergo permanent, inelastic deformation.</p>

<p>In order to better inform and train industry professionals, as well as engineering students and new users, an electronic user's manual and comprehensive online training course for LaModel has been developed in an open online learning environment. The online user?s manual provides widespread access to detailed information on the installation, proper use, and troubleshooting procedures through a combination of: written documentation, voiced-over and captioned software simulations and slide presentations, and relevant academic articles. Some of the online LaModel material has also been organized into a set of progressive, self-paced training modules using a number of the slide presentations and software demonstrations, with the addition of pedagogically designed learning activities and proficiency quizzes. These training modules are designed such that a new user can complete the sequence of three learning tracks (novice, intermediate, and advanced) to become a proficient user of the LaModel program. This thesis reports on the development and implementation of the new LaModel user's manual and training course. Currently, the on-line material includes 84 pages of technical notes and 6 hours of slides and hands-on learning activities. In this thesis, the overall layout and format of the user's manual, training modules, and proficiency quizzes are presented along with samples from specific manual sections and classroom lessons. With an increase in operational difficulties, geologic intricacies, and regulatory review, this generation of mining engineers require complex analyzes to determine the integrity of underground mine works. Through access to the new online user's manual and training modules, novice LaModel users can be effectively trained on the correct operation and analysis techniques for using the LaModel program, while experienced users can quickly access detailed information on the newer and/or more complex LaModel functions. The development of both the user's manual and online training course will ultimately increase the effectiveness of mining engineers within the industry, leading to more productive and safer mine designs.