Scattered mining was practised on Kusasalethu Mine (previously Elandsrand Gold Mine) prior to 1998, but as mining proceeded deeper, it was no longer a feasible option. The scattered mining method would have resulted in unacceptably high stress levels and energy release rates on the active mining faces. Longwall mining was considered as it was practiced on neighbouring mines. This would have ensured that energy and stress levels remained within acceptable limits and avoided the formation of remnants at depth. Kusasalethu Mine required a more flexible mining method owing to the highly variable grade, the presence of multiple faults and dykes and the high production rate required. A mining method was therefore developed that consisted of dip stabilizing pillars for regional support as well as bracket pillars to support geological structures. This was called the Sequential Grid mining method. Sequential Grid mining addressed two main problems, namely, negotiating the adverse geology and the erratic grade of the VCR orebody. However, a recent drop in production resulted in the need for alternatives and improvements to the original mining layout. This involved modifications to the design in order to increase production rates without any compromise to safety. An investigation to modify for the Sequential Grid mining method was therefore conducted by the author in order to determine the consequences for layout stability. A few alternatives were investigated to determine the best possible solution for the Sequential Grid design. As a result, the modified Multi-raise mining method was introduced to address the problems that were experienced with the original design. This study compared the original mining method and the Multi-raise mining with regards to layout stability. Investigation of the seismic data showed no significant differences between the original Sequential Grid mining and the proposed Multi-raise mining. The numerical modelling of the mining layouts showed slightly higher interim Energy Release Rates (ERR) and Average Pillar Stress (APS) levels during the extraction process. The final values for these parameters are nevertheless similar to the original Sequential Grid mining method. It is therefore concluded that the Multi-raise mining method will not have adverse effects on the mine stability. It is concluded that changes to the original Sequential Grid mine design are possible without influencing the seismic hazard. In addition the anticipated interim increases in ERR and APS levels could be kept within acceptable levels through slight decreases to the extraction ratio. The concept of an average value for the stress distribution in a remaining portion of solid rock (pillars) surrounded by underground mining excavations is used as the rock engineering design parameter called average pillar stress (APS). Although averages are generally simple to calculate given the availability of appropriate data, average values for the stress distributed with pillars is somewhat more complex especially when working in MINSIM 2000 is proposed to ensure that the calculation of APS is done appropriately. The study also investigated the use of the Modelled magnitude method to analyse future seismic trends. The study illustrated that the expected seismic trends will be very similar for the Multi-raise method compared to the original Sequential Grid mining method. / Dissertation (MSc)--University of Pretoria, 2013. / gm2014 / Mining Engineering / unrestricted

Countries and governments around the world have accepted the scientific argument on the prevalence and the possible effect of global warming and climate change on the environment, world economy and ultimately human life (Nhamo, 2011). Amongst all industrial corporations, the mining industry is the biggest environmental polluter due to its extractive nature and energy intensive operations. However because of its economic importance, it cannot be abandoned, instead it needs to find a win-win situation, where it continues to succeed but minimizes environmental damage. This thesis aims to examine the possible impact of clean technology on the sustainability of South African gold mining sector. Specifically, the study aims to determine the drivers behind the move towards clean technologies and methods, identify challenges and opportunities associated with this transition at Harmony Gold’s Kusasalethu mine. This was achieved through using Kusasalethu as a case study to which investigations of the effectiveness of clean technology and methods were carried out. The case study was multidimensional; exploring the effect of clean technology on energy consumption, greenhouse gas emission (GHG), water consumption, cyanide management and Kusasalethu’s financial performance. While the case study was largely qualitative it involved quantitative data analysis that had to be triangulated with other data sources and data gathering instruments to achieve legitimacy. This meant that the study had to adopt the mixed research methods. The instruments used included; key informant interviews, and document analysis, structured questionnaire and a set of open ended questions that served as interview guide. The qualitative data were analyzed by means of coding, descriptions, typologies, taxonomies and visual representations, whilst quantitative data were processed through Microsoft Excel to generate various forms of descriptive statistics. The findings indicate that resource consumption (energy, water, cyanide) depends on the mine design and gold output rate. Clean technology implementation at Kusasalethu helped the mine reduce energy consumption and GHG emissions. However scope 2 (indirect GHG emissions associated with energy consumption) is also determined by coal production technologies and methods used by coal mines. Although data on Kusasalethu water and cyanide management and related technologies was not available, the aggregate data for all Harmony Gold mines indicated higher annual water and cyanide consumption during 2010 and 2012. In terms of Kusasalethu’s financial performance and clean technology adaptation, acquisition of clean technologies increased capital expenditure temporarily. However, the positive effects of the clean technology transition and implementation minimized operational cost and increased operational profit greatly. Although adopting clean technologies calls for increased capital expenditure, this study reveals that this expenditure pays off in lower operation costs for the mine and the environment benefits through lower GHG emission. However, clean technologies are yet to impact significantly in lowering water and cyanide consumption levels as they do with energy consumption. The study concluded that clean technology and methods played a positive role on Kusasalethu’s environmental impact and financial performance by reducing energy consumption and GHG emissions. Though, more need to be done in terms of water and cyanide management. / Environmental Sciences / M. Sc. (Environmental Management)

Countries and governments around the world have accepted the scientific argument on the prevalence and the possible effect of global warming and climate change on the environment, world economy and ultimately human life (Nhamo, 2011). Amongst all industrial corporations, the mining industry is the biggest environmental polluter due to its extractive nature and energy intensive operations. However because of its economic importance, it cannot be abandoned, instead it needs to find a win-win situation, where it continues to succeed but minimizes environmental damage. This thesis aims to examine the possible impact of clean technology on the sustainability of South African gold mining sector. Specifically, the study aims to determine the drivers behind the move towards clean technologies and methods, identify challenges and opportunities associated with this transition at Harmony Gold’s Kusasalethu mine. This was achieved through using Kusasalethu as a case study to which investigations of the effectiveness of clean technology and methods were carried out. The case study was multidimensional; exploring the effect of clean technology on energy consumption, greenhouse gas emission (GHG), water consumption, cyanide management and Kusasalethu’s financial performance. While the case study was largely qualitative it involved quantitative data analysis that had to be triangulated with other data sources and data gathering instruments to achieve legitimacy. This meant that the study had to adopt the mixed research methods. The instruments used included; key informant interviews, and document analysis, structured questionnaire and a set of open ended questions that served as interview guide. The qualitative data were analyzed by means of coding, descriptions, typologies, taxonomies and visual representations, whilst quantitative data were processed through Microsoft Excel to generate various forms of descriptive statistics. The findings indicate that resource consumption (energy, water, cyanide) depends on the mine design and gold output rate. Clean technology implementation at Kusasalethu helped the mine reduce energy consumption and GHG emissions. However scope 2 (indirect GHG emissions associated with energy consumption) is also determined by coal production technologies and methods used by coal mines. Although data on Kusasalethu water and cyanide management and related technologies was not available, the aggregate data for all Harmony Gold mines indicated higher annual water and cyanide consumption during 2010 and 2012. In terms of Kusasalethu’s financial performance and clean technology adaptation, acquisition of clean technologies increased capital expenditure temporarily. However, the positive effects of the clean technology transition and implementation minimized operational cost and increased operational profit greatly. Although adopting clean technologies calls for increased capital expenditure, this study reveals that this expenditure pays off in lower operation costs for the mine and the environment benefits through lower GHG emission. However, clean technologies are yet to impact significantly in lowering water and cyanide consumption levels as they do with energy consumption. The study concluded that clean technology and methods played a positive role on Kusasalethu’s environmental impact and financial performance by reducing energy consumption and GHG emissions. Though, more need to be done in terms of water and cyanide management. / Environmental Sciences / M. Sc. (Environmental Management)