submitted partial fulfilment of the requirements for the degree of MASTER OF SCIENCE in the Faculty of ENGINEERING in the University of the Witwatersremd, Johannesburg August 1991 \

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science in Engineering. Johannesburg, 2016 / Since mining platinum started at Unki Mine in 2005, large and small geologically controlled falls of ground (FOG) have been problematic especially in 2011 where a FOG caused a fatality. This study is about determining the rock properties at Unki Mine and then using the results to design and recommend robust support to reduce the FOG problems that are continuously happening. The study analysed all the FOG data from the mine database from 2010 to 2015 using statistical methods. Rock properties of the hangingwall, ore zone and footwall were determined from the laboratory tests. The geological structures were also mapped carefully. The results were then used as input data to the numerical modelling softwares Phase2 and J-Block. The J-Block program was used to determine the number of keyblocks that were stable, unstable and failed with support in designated and specified bords. A probabilistic approach was used to evaluate the stable span with special reference from small to large hangingwall instabilities for different mining scenarios. It was found out using Phase2 that large spans at Unki Mine are possible provided appropriate and robust support system is adopted. To fully address the issue of FOG problem at Unki Mine, a probabilistic approach is recommended as this is considered to be more appropriate than a deterministic approach that has been the traditional design approach so far. / MT2017

Sandsloot open pit mine extracts platinum, copper and nickel from the Platreef orebody in the Northern Limb of the Bushveld Complex. At present, it is the world's largest open pit platinum mine, but it is one of the smaller of six pits to be mined in this area by Potgietersrust Platinums Limited (PPRust). As mining progresses and the mine operations expand, sound knowledge of the subsurface ground, the orebody properties and their performance in the processing plant is imperative. An accurately characterised orebody, in terms of its geotechnical, geochemical and metallurgical properties, will facilitate the development of appropriate and cost effective mining practices and processing plant design. It will improve the prediction and performance of materials in each of the steps involved in converting the orebody rock mass into a concentrate /marketable product, which ultimately leads to mine-to-mill optimisation. This dissertation has focused on the geotechnical and metallurgical strength properties of the Platreef orebody at Sandsloot; the geochemical properties of the various lithologies and defined for each orebody rock type the associations and correlations within and between these properties. The petrography of the orebody material was studied to identify and classify the rock types. A rigorous testing programme was conducted and an extensive database of petrographic, geotechnical, geochemical and metallurgical information was assembled. The corresponding results within and across the different studies were grouped together and statistical analysis and interrogation of the data sets were performed. The research identified diverse rock types with contrasting physical properties in the Sandsloot open pit orebody. For each of the rock types the distinguishing characteristics and the variations in properties were identified. Significant differences and relationships between rock types for each property were assessed for predictability in mining. Statistical associations and correlations between the properties of each study were defined and models for predicting strength and rock type were developed. / Thesis (M.Sc.)-University of KwaZulu-Natal, Westville, 2008.

Thesis (M.Sc.(Earth Science Management and Practice))--University of Pretoria, 2007. / Abstract in English. Includes bibliographical references (leaves 95-99).

Thesis (M.Sc.(Mining))--University of Pretoria, 2001. / Includes abstract in English. Includes bibliographical references.

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

M.B.A. / To develop four Strategic Scenario's for Lonmin Western Platinum Mine ( WPM ) based on investigation into outsourcing, financial, productivity and technological aspects to enable Lonmin Western Platinum Mine management to refocus their operating strategies. 1.7 Objective of research 1.7.1 To analyse the current external and internal environment 1.7.2 To evaluate Lonmin Western Platinum Mines current situation 1.7.3 To utilize an appropriate research methodology 1.7.4 To provide strategic scenarios to top management 1.7.5 To evaluate the strategic scenario's and provide a recommendation to management

M.Sc. (Geology) / Please refer to full text to view abstract

The current weak state of the platinum market, as well as the large inventory of platinum group metals held by Russia, necessitates that the South African platinum mining industry must carefully evaluate the benefits and disadvantage of small-scale mining of shallow, open castable ore resources. Until the late 1980's, these resources were ignored due to the metallurgical complexities of treating oxidized ore, as well as the mind set that existed within the South African mining industry which militated against open cast mining in the Bushveld. During the latter part of the 1980's and early 1990's, advances in the metallurgical treatment of oxidized ore, specifically the UG2, as well as operational problems, created the impetus to begin the exploitation of these resources. Small-scale open cast mining has become viable due to the development of suitable mining methods that facilitate mining practices acceptable to the Department of Mineral and Energy Affairs, in terms of environmental legislation. Metallurgical advances and growing experience, especially with respect to the UG2, enables reasonable platinum group metals recovery from oxidized ore. The problems experienced in doing this can, and are being overcome. With growing public awareness of environmental issues, particularly related to the mining industry, the requirement to ensure that the small-scale open cast mine site is well managed is paramount. A methodology for the evaluation is presented along with a case study of a small-scale UG2 open cast pit. Evidence is presented that shows that these small-scale open cast mining operations are extremely profitable and require minimal capital expenditure. However, caution is advised when evaluating Merensky Reef open cast operations because of the problems that they present.

Trithiocarbonates (TTCs) with less than six carbon atoms per molecule historically have proved to be better bulk sulphide mineral collectors than conventional dithiocarbonates (DTCs). However, high vapor pressures of the short-chain mercaptan decomposition products prevented them from general industrial use. Impala’s commitment in TTC development changed in 2002 when the nC12-trithiocarbonate indicated strong synergism when added to their existing flotation suite. A concerted research effort at the University of Utah followed, and in particular on their surface chemistry. To compliment current research and development at Impala, fundamental work regarding the surface hydrophobicity of pyrrhotite under electrochemically controlled conditions was undertaken at Utah University. Controlled contact angle measurements showed that the surface hydrophobicity of pyrrhotite can be increased by small additions of nC12-trithiocarbonate to SIBX. It was also found that this improvement in the surface hydrophobicity with the SIBX-TTC mixture was more significant at lower oxidation potentials. Work at Utah University further showed that a C12 decomposition product may or may not be present with an adsorbed TTC molecule. External reflectance infrared spectroscopy in the mid infrared region suggested a “crowding” of the collectors at the surface when SIBX and TTC are combined. This was based on an increase in the absorbance of the -CH2- peaks in the mixed collector system. In bench scale flotation tests on PGM bearing samples from the Merensky reef, it was found that a 5 molar percent replacement of SIBX with nC12-trithiocarbonate improved the flotation activity relative to the standard SIBX-DTP mixture. Improvements were in the recoveries of PGMs, copper and nickel. The addition of TTC also increased the flotation rates of both slow and fast floating valuables as is predicted by the Kelsall equation. The optimum mixture for the pilot plant trials was thus a 5 molar percent replacement of the current collector suite with nC12-TTC. Based on the bench flotation results, research was extended to a pilot plant trial. At a depressant dosage of 100g/ton, the PGM concentrate grades from the first rougher cell improved from 120g/ton to 175g/ton when the TTC was introduced. This was achieved without any effect on the recovery from the first cell. This increase in concentrate grade is believed to arise from the nature of both: <ul> <li>The mineral-collector surface state, and</li> <li>The bubble surface interaction.</li> </ul> Overall, the standard SIBX-DTP collector combination and the new SIBX-DTP-TTC collector combination (both at 100g/ton depressant) was also compared to pilot plant tests with SIBX-DTP at high (350g/ton) depressant dosages. The latter suite forms the currents reagent suite at Impala Platinum. When comparing the first two trials, at 100g/ton depressant, the addition of TTC as a ternary collector resulted in a recovery improvement of approximately 2.2% with a simultaneous increase in final concentrate grade from 57g/ton to 73g/ton. The result was a reduction in solids recovery from 5.3% to 4.1%. When comparing the TTC trial to the standard collector suite at high depressant dosages, only a small reduction (3.6% vs. 4.1%) in solids recovery was achieved with a final concentrate grade of 85g/ton. The PGM recoveries were very similar. Based on current Merensky milling rates, depressant and TTC costs, and calculated replacements based on the pilot plant tests, a projected cost saving on chemicals is R9.6 million per annum. Financial impacts on processing, grade and kinetics have not been made. It was also concluded that the detrimental effect of mild steel milling on the flotation activity of SIBX-DTP was diminished with the addition of the long-chain TTC with SIBX and DTP. As part to this research, a preliminary plant trial on UG-2 underground material showed a reduced primary rougher chromite grade as well as a significant increase in PGM concentrate grade for the first two primary rougher cells. This is an important finding, especially for the melting process. In this final study a partial (5 molar percent) replacement of the standard collector used was also made. What was further realised was a significant increase in the final concentrate grade when compared to the standard conditions. / Dissertation (MEng (Metallurgical Engineering))--University of Pretoria, 2007. / Materials Science and Metallurgical Engineering / MEng / unrestricted