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The purpose of this dissertation is to evaluate the feasiblity of alumina production in Ghana to replace imported alumina for the production of aluminum. It spells out the conditions which led to the existing bauxite-alumina-aluminum trade in the country. The structure of the economy of Ghana is examined to show the contributions of the important sectors to the total income of the country, and its dependence on a few export commodities for revenue. The plan to build a dam for the generation of hydroelectric power was linked to the establishment of an integrated aluminum industry based on the exploitation of domestic bauxite reserves. As the country could not finance the project alone, foreign assistance was sought. VALCO, a subsidiary of Kaiser and Reynolds, was formed to undertake the project. The agreement reached with VALCO was that a smelter would be built to use imported alumina for ten years, during which time a refinery would be built to feed the smelter from domestic sources. However, after ten years this could not be achieved, and the smelter continues to use imported alumina. A model of the world aluminum economy is used for analyzing the sensitivity of price to production and consumption expansion. The results show that industry demand is sensitive to the level of industrial activities in the developed countries, and less sensitive to the own price and cross price variables of aluminum in both the short and long run. On the other hand, supply is inelastic to the own price and the rate of capacity utilization in the short run, but elastic to both variables in the long run. An appraisal of opening a bauxite mine and an alumina refinery at Kibi is undertaken. The results show the levels of bauxite and alumina prices and the costs of construction at which the project is feasible. The shadow values and weights used are permittd to vary with changes in the economy's foreign trade and the balance of payments.

A graph theory oriented algorithm for optimal ultimate pit limit design is developed. Mathematical proofs of optimality and convergence are given. The algorithm works on a 3-D block mine model and formulates the model into a directed graph consisting many trees. The vertices in the graph are identified with the blocks in the model and the imposed arcs in the graph represent pit slope constraints. The formation of each directed tree is based more on the ore-waste support concept than geometric constraints alone. The algorithm efficiently handles the joint support and re-allocation problems. The theoretical proof shows that the new algorithm is consistently faster than the well known Lerchs-Grossmann's (LG) algorithm, which is the only algorithm developed in the past one-quarter century capable of producing a true optimum pit limit. The case study results show that the new algorithm is able to generate the optimal ultimate pit limit for a model with 80 columns x 80 rows x 40 levels on an IBM PC AT 80286 microcomputer in 115 minutes. The indirect comparison was made between the results of the new algorithm and the results obtained by P. Huttagosol (1988, 1989) using the LG algorithm. P. Huttagosol optimized a smaller mine model than the one optimized by the new algorithm in 535 minutes of VAX8600 CPU time. The comparison between 535 minutes of VAX8600 CPU time for a smaller model with 115 minutes PC AT processing time for a bigger model clearly indicates that the new algorithm is significantly faster than the LG algorithm. This study also investigates both proposed mathematical optimization approaches and the popular trial and error "pushback" approach to long range mine planning. Both the theoretical analysis and numerical examples demonstrate it is impossible to obtain the optimal solution to mine production scheduling by the approach combining the Lagrangian relaxation with the ultimate pit limit algorithm. The non-convergence due to redundant optimal solutions and the non-convergence due to the requirement of advanced stripping are identified with the proposed approach. The investigation clarifies the long-time misunderstood concept and proves the impossibility of such a research direction itself. Finally, some problem solving techniques which play important roles in the computerized mine planning and grade control are developed and discussed. Specifically, they are: (1) point-in-polygon algorithm, (2) polygon area algorithm, (3) polygon clipping algorithm, (4) blast hole data collection, validation and database maintenance, and (5) the interactive graphics ore-waste delineation.

A statistical model for assessing the risk of subsidence in abandoned mines is presented. The model is based on the relationship that exists between the frequency and location of subsidence events and the physical conditions of the ground. These conditions are described by geological, mining, and physical variables. The model suggests the existence of regions in the multi-dimensional space of variables which can be associated with increases, or decreases, in the frequency of subsidence events. Regions associated with an increase in the frequency of subsidence events correspond to regions of higher risks, and vice versa. Risk is assessed by expressing the limits of these high and low risk regions in the space of variables, and by expressing the degree of membership of blocks of land within any of these regions. The theoretical framework for the model is extracted from discriminant analysis. The high and low risk regions are associated with two populations: (1) blocks which according to their ground properties are not likely to develop subsidence, and (2) blocks which are likely to develop subsidence. Risk is quantified by the probabilities of membership of blocks of land into any of these two populations. These membership probabilities are computed using discriminant functions which use geostatistical estimates of the ground's properties and the number of subsidence events registered in each of the blocks. Risk maps are produced by displaying membership probabilities contoured in appropriate levels. The model was applied in two urban areas: Penn Hills, near Pittsburgh, and Scranton/Wilkes-Barre in northeastern Pennsylvania. At Penn Hills, the risk maps generated were sensitive to the equal-covariance and multi-normality assumptions of the model. The risk map generated under a non-parametric approach resulted in closer agreement and comparable to an independently generated risk map. Both maps succeed in locating recent subsidence events inside medium and high risk zones in seven out of eight cases. In the Scranton/Wilkes-Barre area, the risk maps generated under the equal-covariance and the multi-normality assumptions, as well as that generated under the non-parametric approach, reproduce well the present degree of subsidence in the area.

<p> Changes in milling technology at the Cortez Mining District, a gold and silver mine located in a remote area of central Nevada, are examined through the study of five mills that were active between 1864 and 1944. Each mill is analyzed through documentary and archaeological sources in order to understand how different forms of technology were implemented and modified to most effectively treat ores over time. Locally, this process of technological adaptation was influenced by changing environmental knowledge. On a larger scale, the milling technology is contrasted against global trends relating to a second wave of industrialization, such as the use of engineering and scientific knowledge in industrial pursuits, and the increasingly systematic deployment of capital. </p>

This thesis tells the hitherto neglected story of onshore oil exploration in the British East Midlands from 1908 to 1964. Drawing on a series of case studies it provides a regional historical geography, connecting science and industry to the exploratory field science of geology. During the period examined, two low key discoveries – Hardstoft, in Derbyshire (1919), and Eakring, in Nottinghamshire (1939) - altered Britain’s energy prospects, supplementing coal with liquid mineral oil. Using archival research methods and oral testimonies, the thesis reveals how a diverse assemblage of earth scientists, oilfield technologies and techniques, institutions and private companies developed a regional laboratory for oil exploration. Liquid energy fuelled heated political debates over land nationalisation and private ownership rights, the science of subsurface quantification and governance, and the role of industry in exploration. Though small when compared with global consumption and production figures, oil discovered in the British East Midlands provided a time critical supply of oil during World War Two. It also facilitated technological advances in oilfield development, contributed towards a new arm of economic geology (geophysics) and encouraged earth scientists to think of territory as a three dimensional entity, extending beneath, as well as along the land surface.

An investigation was undertaken to examine the performance of a Fresnel reflection sensor (FRS) incorporated into a differential scanning calorimeter (DSC) to track the cross-linking of epoxy resins. The initial design used a micrometer translation stage to lower the FRS through an orifice in the DSC platinum lid and onto the pan containing the sample. During exothermic cross-linking experiments, the resin refractive index and the heat evolved were measured simultaneously, allowing for direct comparison between the data. Combining the two measurement techniques produced a powerful hyphenated analytical procedure that demonstrated the feasibility of using the FRS for in-situ cure monitoring of epoxy resin systems. During the cross-linking of specified resins, the sensor revealed optical phenomena throughout the latter stages and was shown to be sensitive to the glass transition temperature, nano-particulate movement, nano-particulate concentration and phase separation. Therefore, the introduction of the FRS to the DSC provided valuable cross-linking information. A second modification to the DSC permitted the accommodation of an optical fibre probe, which facilitated simultaneous DSC/FRS/Fourier transform infrared spectroscopy (FTIRS) analysis. Good correlation between the cross-linking kinetics of an epoxy resin system was demonstrated using the hyphenated techniques and hence alleviated the issues of cross-correlation between individual experiments.

This thesis details work that was carried out to optimise the fracture toughness and thermal stability of a new maraging steel called F1E. This steel was designed to precipitate Laves phase to improve the creep properties, and it was initially found that this was detrimental to toughness properties, and that further precipitation occurred during extended time at desired operating temperatures, embrittling the alloy. Initial work focussed on development of a heat treatment to stabilise the Laves phase, using a slow cool to the service temperature to fully precipitate the equilibrium volume fraction of Laves phase at this temperature without nucleating fresh particles, as it was believed that it was fresh particles forming during service which led to the loss of ductility after thermal exposure. This heat treatment process successfully stabilised the properties. Modifications were then made to the composition in an attempt to improve the ductility and toughness without losing strength or creep performance. Two changes were made - an increase in the nickel content, as increasing the concentration of nickel in the matrix of maraging steels has been shown to improve toughness; and a decrease in molybdenum and tungsten content to reduce the Laves phase volume fraction by 25%. These changes, along with further optimisations of the heat treatment used and refinement of the prior austenite grain size, were successful in improving the fracture toughness of F1E (or RR9922 as the modified composition is known) by a factor of 2, from 23 MPa m\(^0\)\(^.\)\(^5\) to 46.9 MPa m\(^0\)\(^.\)\(^5\).