Thesis (M.Sc.(Earth Science and Practice Management))--University of Pretoria, 2006. / Abstract in English. Includes bibliographical references.

Thesis (M.Sc.(Geology))--University of Pretoria, 2006. / Includes bibliographic references.

Prof Peter Alexander Mr Chris Bolsmann

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in fulfilment of the requirements for the degree of Masters of Science in Mining Engineering 2016/10/5 / Management does not have an efficient mechanism to test strategic and operational alternatives and to assess the impact of these on the value and underlying trade-off variables of the business. Techno-economic models can be applied for this purpose as they provide a framework for undertaking advanced process simulation and business valuation. The purpose of the research report is to identify key components, principles and best practice as applied in techno-economic models, to improve techno-economic modelling for the purpose of decision-making and business optimization. The integrated techno-economic model requires a mining model with production planning and scheduling abilities. The half-level system method can be applied to create production profiles for different mining options and only after optimisation the best option is taken forward for graphical design and detailed scheduling. A metallurgical model incorporates the logic and efficiencies of the treatment process into the techno-economic model from which the refined products are determined for revenue and costing purposes. The financial model integrates with the mining and metallurgical elements and uses detailed costing models and sound financial principles for operating and capital cost estimates. An accurate techno-economic model includes key cash flow components and applies rigorous valuation practice for investment analysis. Techno-economic models are extensively applied in business planning, major project valuations and stay–in-business project valuations. Learnings from the review of these case studies suggest best practice, which allows the models to be applied to different types of business entities and contributes to the accuracy, consistency and efficiency of techno-economic modelling. Integrated techno-economic modelling is also applicable in strategic planning and mine design optimization as it provides a powerful instrument for decision-making and business optimization. The future of the mining business depends on it as an invaluable direction steering tool. / MT2017

The platinum market is best understood through a comprehensive analysis of supply and demand. Supply is most significantly affected by production constraints and the erratic draw-down in Russian stockpiles. Total world supply of platinum for 1998 amounted to 5.915 Moz, 64% of which was produced from the Bushveld Complex in South Africa. The remainder emanated from Russia, Zimbabwe, the United States, Canada and the recycling of autocatalysts. Supply is forecast to drop by 320 000 oz in 1999 due to a lower Russian export quota and reduced Zimbabwean production. Demand for platinum is unusual, in that it is sought after both as a store of wealth, and has properties that make it irreplaceable in a host of industrial applications. Current world demand for the metal is driven by a growing Eastern jewelry market and increased use in autocatalysts due to vehicle emissions legislation. Total world demand for 1998 amounted to 5.755 Moz. A predicted steady growth in the consumption of platinum for jewelry and existing applications, together with development of new uses, is expected to result in an annual 250 000 oz increase in demand for 1999 and 2000. The derived supply and demand balance for 1998 shows a small excess in supply relative to demand. This will be absorbed by inventories and is likely to have little affect on price, A significant shortfall of 410 000 oz, however, is predicted for 1999. This is likely to be followed by a further shortfall in 2000 and will drive up prices, impel consumers towards substitution and thriving and encourage producers to expand.

Thesis (M.Eng.)(Metallurgical)--University of Pretoria, 2006. / Includes summary. Includes bibliographical references. Available on the Internet via the World Wide Web.

M.Sc. (Geology) / The study aims to provide a geometallurgical assessment, including an evaluation of the response of different facies types of the Merensky Reef to mineral processing, and the identification of critical characteristics that determine processing behaviour. This is accomplished by obtaining quantitative mineralogical information, combined with chemical assay, laboratory scale milling and flotation testing. Lonmin Platinum’s Marikana Mine is located on the Western Limb of the Bushveld Complex to the east of Rustenburg. Platinum group elements (PGE) occur in, and are mined from, a variety of facies types of the Merensky Reef, and the UG2. For the purpose of the present study, three facies types of Merensky Reef samples and one sample of UG2 were used. The Merensky facies samples comprise of the BK, RPM, and Western Platinum variants. The mineral assemblages of the various Merensky Reef facies types at this locality comprise varying amounts of orthopyroxene, clinopyroxene, plagioclase, olivine, talc, serpentine, chlorite, chromite, magnetite and sulphides (mainly pyrrhotite, pentlandite and chalcopyrite). Approximately 20 individual 10 cm channel samples were collected from each of the facies variants of the Merensky Reef, and the UG2. These are coarsely crushed, mineral modal abundances determined using the MLA, and then analysed for Co, Cr, Cu, Ni, S and 6 PGE. The samples were then combined per facies type, and each of these composites subjected to laboratory scale milling and flotation testing. Abundant sulphide typically occurs with (is associated with) thin chromitite stringers, as is commonly observed in the Merensky Reef throughout the whole of the Bushveld Complex. Chromitite stringers are characterized by high PGE concentrations. The milling behaviour of the various facies samples, as well as flotation behaviour, was observed to be a function of mineralogy. The influence of ore mineralogy on the various stages of flotation, the mineralogical makeup of the various flotation concentrates, and the level of recovery of the PGE’s during flotation, were also investigated. Ore facies having the most abundant anorthite required the longest milling time to achieve the target grind of 60wt.% passing 75μm; and the ore with the most abundant enstatite produced the largest mass pull on floating. The facies with higher PGE grade, modal abundance of base metal sulphides, higher degree of liberation of base metal sulphides and least enstatite abundance produced the most favourable set of characteristics for efficient PGE recovery.

Rock density is critical for determining the tonnage of an orebody and therefore impacts on the total resource of a deposit. Density is defined as the concentration of matter, and is expressed as mass per unit volume (g/cc; g/cm3 or t/m3). The density that is calculated will depend on the nature of the rock, and whether the volume calculated includes the open and/or closed pore volume of the rock. The pore volume will depend on the rock’s internal and external characteristics. This study looks at two methods commonly used to determine the rock density of samples taken from boreholes drilled for platinum mines on the North Eastern limb of the Bushveld Complex, South Africa. The first method is a gas pycnometer, which is almost exclusively used by laboratories. A Grabner Minidens air gas pycnometer was used. The second method is a hydrostatic immersion method, using water as the Archimedean fluid. An adapted Snowrex NH – 3 scale that can weigh a rock sample in air and in water was used. The first part of the study investigates the possible differences between conducting rock density measurements on finely milled core in the Grabner Minidens air gas pycnometer or on solid halved core samples using a hydrostatic immersion method, and the implications thereof. The second part of the study, not only investigates the differences between conducting density measurements on solid core samples or on milled core samples, but also looks at how the type of method used and how location affects the density measurement obtained. The location is important because changes in temperature and atmospheric pressure have been shown to produce small, but measurable changes in density. The density of pure water at 4 °C is approximately 1 g/cm3, increases or decreases in temperature will marginally decrease the density of water. The density of pure water at room temperature (21 °C) is 0.998 g/cm 3. Changes in atmospheric pressure have been shown to have a negligible effect on the density of most solids. The diamond drill core samples were taken from boreholes targeting the platinum group element (PGE) rich Merensky reef (MR) and Upper Group 2 (UG2) chromitite layer of the Upper Critical Zone. Samples were taken from the hangingwall (HW), reef and footwall (FW) of the MR and UG2. These rocks are made up of closely interlocking minerals, typical of cumulates. There are generally no visible pore spaces apart from highly fractured and altered samples. In part one of the study, 18,430 samples were used. The halved core samples were first measured using the hydrostatic immersion method at the exploration offices close to where the boreholes were drilled, referred to as the “Driekop” method. The samples were then sent to a laboratory in Johannesburg. Each sample was first milled to a fine powder (40 μm), and then a small portion of the milled sample (4 cm3) measured using the Grabner Minidens air gas pycnometer, referred to as the “Grabner Milled” method. For quality control, 811 of the remaining halved core samples were re-measured using the hydrostatic immersion method.The Grabner Milled results were found to be consistently higher than the Driekop results, with a mean average relative difference (AVRD) of approximately 5 % for all stratigraphic units. The difference observed can be accounted for, from the way in which the sample is prepared and the type of density that is measured. The Driekop method calculates the bulk density of the solid halved core sample, which includes all the open and closed pores of the rock. The Grabner Milled method calculates the true density of the finely milled sample, which through comminution, has excluded all open and closed pores that were in the rock. The quality control repeat measurements on the remaining halved core samples showed a good correlation with the original measurements, with a mean AVRD of only 0.33 %. In part two of the study, 82 randomly selected samples were used. The density of each solid sample was first determined using the hydrostatic immersion method. The same hydrostatic immersion method used in part one was applied at the same location; therefore it is also referred to as the “Driekop” method. The same hydrostatic method was then conducted on the samples at the laboratory in Johannesburg, referred to as “Lab water solid”. The gas pycnometer method was only conducted at the laboratory. The samples were first measured as a solid, referred to as “Grabner solid”. The samples were then milled to 40 μm and remeasured in the Grabner Minidens, referred to as “Grabner Milled”. The three solid methods results showed good correlation, with an average AVRD of only 0.01 % for the two hydrostatic immersion methods. On the other hand, there was a marked difference in results between the solid methods and the Grabner Milled method, the most significant difference being between the Grabner Milled and Grabner solid method (AVRD = 3.42 %). The resource model parameters for a project within the study area were used to illustrate the effect of density on resource planning. The average density used in the resource calculation will depend on what density method is used. The AVRD between the two methods for the mining cut density was approximately 5 %. The resource calculation showed that the difference in tonnage and 4E ounces between the two methods was also approximately 5 %. Changes in density result in equal changes in tonnage and metal content (4E ounces). Increases in dilution or overbreak from 10 to 30 cm above the optimal mining cut showed increases in tonnage and decreases in metal content. Due to similarities in rock composition between the HW, reef and FW of the MR, further dilution caused only a marginal decrease in density. The UG2 was found to be much more sensitive to dilution because of the distinct differences in rock composition between the reef, which is a chromitite layer and the HW and FW, which are both made up of plagioclase pyroxenite. Emphasis is commonly placed on the effect of dilution on grade; however this shows that the effect of density can be as important. The hydrostatic method of density determination is a very practical way of determining rock density at a remote exploration site. The whole sample can be measured and it is not restricted by the size or shape of the sample. Modern gas pycnometers have a higher degree of accuracy and precision, but need to be operated in a laboratory controlled environment, and are only capable of measuring a small amount of sample. With the correct application of quality control, both are suitable methods of density determination. The selection will depend on what type of density is required, the nature of the rock and whether the method must include or exclude pore spaces in the rock. Copyright / Dissertation (MSc)--University of Pretoria, 2012. / Geology / unrestricted

The underground hard rock mining industry in South Africa is faced with the challenge of simultaneously delivering both safety and productivity excellence. Frontline supervisors need to manage the inherent trade-off between safety and productivity to achieve excellence in both. Previous research suggests that supervisors with a transformational leadership style have delivered safety and productivity in separate studies. This study examined the relationship between the transformational leadership style of underground mining supervisors at Impala and the simultaneous delivery of both safety and productivity. It also investigated the mediating effect of group safety climate on the relationship between transformational leadership and injury rate, and the mediating effect of group cohesiveness on the relationship between transformational leadership and productivity. The relationship between transformational leadership and the perception of leader effectiveness was also investigated in the study context. The research design was a case study using mixed methods in the form of a sequential explanatory design. In the first quantitative main phase of the study, survey questionnaires were completed by respondents to determine the leadership style of the mine overseers who were the unit of analysis. Data was also collected using survey questionnaires for group safety climate and group cohesiveness. The injury rate and productivity data for the mine overseer sections was recorded for a one year period prior to the survey. In the second qualitative phase of the study selected mine overseers were interviewed and a focus group of mine overseers was conducted. Also, underground observations were carried out and documents were scrutinised. The focus of the qualitative research was to interpret and explain the results that were obtained in the quantitative first phase of the study. The results indicate that transformational leadership is related to the perception of supervisors’ effectiveness. This relationship is partially mediated by group safety climate and group cohesiveness. The relationship between transformational leadership and the objective measures of injury vi rate and productivity were not supported in the quantitative results. This may indicate that these measures were too narrow to determine supervisors’ leadership effectiveness, and/or were contaminated by confounding variables as was suggested in the qualitative phase of the study. The qualitative findings indicated that supervisors’ perception was that transformational leadership style is effective in delivering safety and productivity excellence. The overall conclusion of this study is that in the context of Impala or similar operations, that the effective supervisor should employ the full range of leadership. This behaviour includes maintaining discipline and using contingent reward to motivate the achievement of goals. The effective supervisor also uses the transformational leadership style giving meaning to work and creating a feeling of team membership. Transformational leadership inspires the diverse workforce to deliver safety and productivity excellence in the difficult and risky mining conditions. Furthermore, supervisors’ behaviour is greatly influenced by management’s priorities. / Business Management / D. B. L.

The underground hard rock mining industry in South Africa is faced with the challenge of simultaneously delivering both safety and productivity excellence. Frontline supervisors need to manage the inherent trade-off between safety and productivity to achieve excellence in both. Previous research suggests that supervisors with a transformational leadership style have delivered safety and productivity in separate studies. This study examined the relationship between the transformational leadership style of underground mining supervisors at Impala and the simultaneous delivery of both safety and productivity. It also investigated the mediating effect of group safety climate on the relationship between transformational leadership and injury rate, and the mediating effect of group cohesiveness on the relationship between transformational leadership and productivity. The relationship between transformational leadership and the perception of leader effectiveness was also investigated in the study context. The research design was a case study using mixed methods in the form of a sequential explanatory design. In the first quantitative main phase of the study, survey questionnaires were completed by respondents to determine the leadership style of the mine overseers who were the unit of analysis. Data was also collected using survey questionnaires for group safety climate and group cohesiveness. The injury rate and productivity data for the mine overseer sections was recorded for a one year period prior to the survey. In the second qualitative phase of the study selected mine overseers were interviewed and a focus group of mine overseers was conducted. Also, underground observations were carried out and documents were scrutinised. The focus of the qualitative research was to interpret and explain the results that were obtained in the quantitative first phase of the study. The results indicate that transformational leadership is related to the perception of supervisors’ effectiveness. This relationship is partially mediated by group safety climate and group cohesiveness. The relationship between transformational leadership and the objective measures of injury vi rate and productivity were not supported in the quantitative results. This may indicate that these measures were too narrow to determine supervisors’ leadership effectiveness, and/or were contaminated by confounding variables as was suggested in the qualitative phase of the study. The qualitative findings indicated that supervisors’ perception was that transformational leadership style is effective in delivering safety and productivity excellence. The overall conclusion of this study is that in the context of Impala or similar operations, that the effective supervisor should employ the full range of leadership. This behaviour includes maintaining discipline and using contingent reward to motivate the achievement of goals. The effective supervisor also uses the transformational leadership style giving meaning to work and creating a feeling of team membership. Transformational leadership inspires the diverse workforce to deliver safety and productivity excellence in the difficult and risky mining conditions. Furthermore, supervisors’ behaviour is greatly influenced by management’s priorities. / Business Management / D. B. L.