Current methods of solar-grade silicon (SG-Si) production are energy intensive and costly. The possibility of using metallurgical techniques for refining metallurgical-grade Si (MG-Si) to SG-Si has been investigated. The main steps in the metallurgical refining route include alloying with copper to produce a 50-50wt% Cu-Si alloy, controlled solidification, crushing, and acid leaching. The controlled solidification process involved 5 variations to determine the best process to maximize Si dendrite agglomeration in the sample and produce the purest Si. This was determined by using various techniques, such as: optical imaging, dendrite analysis, EPMA and SEM analysis and ICP analysis. The crushing and acid leaching steps were carried out to remove the unwanted Cu3Si eutectic from the pure Si dendrite phase. Upon completion of the analysis techniques, the optimal cooling method was determined to be the top cooled, 0.5°C/min sample.

No description available.

Of all coke properties the influence of the catalytic mineral matter on reactivity of metallurgical cokes is least understood. There is limited information about the form of minerals in the metallurgical cokes and no information about their relative concentration. A comprehensive study was undertaken for characterisation of mineral matter in coke (qualitative and quantitative), which enabled quantification of the effect of catalytic minerals on the reaction rate, and establishment of the effect of gasification on the mineral phases. Also, the relative importance of coke properties on the gasification reaction rate was determined. The reactivity experiments were performed at approximately 900??C using 100% CO2 under chemically controlled conditions. The mineralogical composition of the investigated cokes was found to vary greatly as did the levels of catalytic mineral phases. These were identified to be metallic iron, iron sulfides and iron oxides. The gasification reaction rate at the initial stages was strongly influenced by the content of catalytic mineral phases and also by the particle size of the catalytic mineral matter. The reaction rate increased as the contact surface between catalyst and carbon matrix increased. Catalytic mineral phases showed a strong influence on the reaction rate at early stages of reaction. But their influence diminished during gasification. At later stages of reaction the influence of micropore surface area became more important. The influence of the catalytic mineral phases diminished during gasification because the catalyst was inactivated to some degree and the contact surface between the catalyst and carbon matrix diminished due to the strong gasification of the carbon around the catalyst particles. The partial inactivation of the catalytic mineral phases occurred because metallic iron and pyrrhotite were oxidised by CO2 to iron oxide, and in turn iron oxide reacted with other mineral phases, which it is associated with, to form minerals that are not catalysts. It is noteworthy that a significant percentage of the mineral matter present in the investigated cokes was amorphous (44 - 75%). The iron, potassium and sodium present in the amorphous phase did not appear to catalyse gasification, but their potential contribution to gasification could not be completely excluded.

Thesis (MEng (Metallurgical Engineering))-University of Pretoria, 2008. / Includes bibliographical references.

Thesis (M.Eng.(Metallurgical Engineering))--University of Pretoria, 2008. / Abstract in English. Includes bibliographical references.

Thesis (M.Sc.)(Metallurgy)--University of Pretoria, 2004. / Includes summary. Includes bibliographical references.

The thesis deals with the project related to development of services on the market of metallurgical materials. It takes into consideration the possibility of implementation of the project and also proposes concrete actions and solutions. On the one hand it is based on the expert publication and statistical datas, on the other hand on the internal documents of the company XY and the own survey of customer's needs in the area of surface finish and working of steel tubes and hollow profiles. Justifiability of the main idea of the project is supported by four factors. Therefore, development of the market, competition, customer's demands and long-term strategy of involved company XY represent the basis for specifications of final form of the project. On the basis of the assessment of these factors the individual conclusions are worked out. It is case of business plan. Except for analyse of resources, budget and schedule the thesis is focused on the identification of main risks concerning the project. The final outcome of the thesis is represented by concrete proposal of the project.

The purpose of this study is to determine whether all costs over the life cycle of metallurgical research projects are included in the initial cost estimate, whether these costs are estimated accurately and whether they are managed throughout the project’s life cycle. The impetus for this study came from the observation that costs in metallurgical research projects are often not accurately estimated and are not managed over the entire life cycle of these projects. Cost estimation and cost management over the life cycle of a project were an integral part of the project and crucial to its success. The initial cost estimate can seal a project’s financial fate. Projects often overrun estimated costs because the costs are not estimated accurately enough and not well managed. The project leaders of metallurgical research projects are engineers and not always trained to estimate and manage costs effectively. Project management textbooks are of little assistance in this regard because they tend to focus on timeous delivery, and fail to include enough information on cost estimation and cost management. To facilitate an effective and objective analysis of the survey, an extensive literature review was conducted. Life cycle costing, methods of cost estimation and cost management techniques were examined in detail. An empirical study was conducted to determine whether these methods of cost estimation and cost management are being used over the entire life cycle of metallurgical research projects, and whether all costs are being included in the initial estimates of costs. It was deemed that results of the empirical study would provide useful information on the factors contributing to the success, failure or early termination of these projects. This study is a descriptive research study. The research methods used in the research design were structured and quantitative. A survey was used to gather information by way of face-to-face and telephonic interviews as well as an e-mail questionnaire. The population was small and consisted of the entities involved in metallurgical research projects in South Africa. There were only 12 entities in the population. The 10 largest entities in terms of project size were selected. A nonprobability sampling approach was used. The e-mail questionnaires were analysed manually by means of spread sheets to obtain graphical information. The processed data were used to draw conclusions. The answers to the questions were linked to the theoretical framework by means of interpretation. It was concluded that all costs over the life cycle of metallurgical research projects are not taken into account in the initial cost estimate of a project, and the cost estimates may therefore not be accurate. The final costs, including discontinuation costs, are often not included in the cost estimates. The costs are mainly managed during the growth phase of a project and not during the introduction phase when 80% of the costs are normally committed. This study emphasises the importance of including all costs during a project’s life cycle, and introduces engineers to modern cost management techniques. Copyright / Dissertation (MCom)--University of Pretoria, 2009. / Financial Management / unrestricted

Please read the abstract in the section 00front of this document / Dissertation (M Eng (Metallurgical Engineering))--University of Pretoria, 2007. / Materials Science and Metallurgical Engineering / unrestricted

A sequence of 3250 m of the Rustenburg Layered Suite and its associated mineralization south of Potgietersrus was investigated. Four episodes of faulting have deformed the area. This resulted in very early differentiates, not seen elsewhere in the Bushveld Complex, to outcrop together with economic concentrations of the best metallurgical grade chromite presently being mined in the Republic. The Mg:Fe:Ca ratio of theCa-poor pyroxenes varies from 89,5:8,8:1,6 in the lower zone to 44,2:52,3:3,37 in the upper zone. The latter composition demarcates the Fe-rich end of the two pyroxene limit. Textural evidence implies that there is a peritectic reaction between the ironrich Ca-poor pyroxene and the melt and that this may account for the termination of the two pyroxene field. A significantly higher mean Ko~~~F~p; for the study area (0,822) than for the other sectors of the Bushveld Complex (0,782) suggests that the pyroxenes of similar composition crystallized at higher temperatures in the Potgietersrus limb. Examination of the Al :Si ratio in Ca-rich pyroxenes from a variety of magmatic environments confirms that this variable can be used to monitor relative changes in the a ~~~t. Chemical data of the Ca-rich pyroxenes suggest that this phase define~ an Fe enrichment - Ca depletion trend during differentiation uhlike that for most other tholeiitic intrusions. The V205 content of the main magnetitite layer and the cr203 and the Cr/Fe2++Fe3+ values in the upper and lower chromitite layers in the study area are the highest encountered in the Bushveld Complex. Textural evidence in these layers show that they have been up-graded to dense monomineralic layers by postcumulus sintering. Calculated intensive parameters for the Potgietersrus magma suggest that it crystallized over a temperature interval from 1276°C in the lower zone to 1022°C in the basal portion of the upper zone. Oxygen fugacity conditions for the lower zone ranged from 10-6,21 to 10-4,98 atm whereas lower values of 1o-11 to 1o-9 atm were operative in the upper zone. The study area contains abundant concentrations of sulfides at several levels in the sequence. The separation of the sulfide liquid is related in most cases to new influxes of metal-rich magma and mixing with the residual magma in the chamber. Several definite sulfide facies occur in the layered sequence. Sulfur isotope investigations indicate that all the sulfur in the study area is mantle derived and that the isotopic composition of the sulfur was controlled by the prevailing fo2, which in turn controlled the partitioning of S02 and HzS between sulfide melt and magma. / Thesis (PhD)--University of Pretoria, 1983. / gm2014 / Materials Science and Metallurgical Engineering / Unrestricted