3. Electronic Theses and Dissertations (ETDs) - All submissions
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Item A systems approach to improved safety in the South African gold and platinum sectors, post 2006(2019) De Jager, Ernst JakobusThe safety performance in the South African mining industry has been a contentious issue for decades when compared to international benchmarks. Although mining safely has always been part of the mining business proposition, a step change was required after 220 fatalities occurred in 2007, which were unacceptable and threatened the sustainability of mining (COM 2017). A holistic safety and health approach is necessary for a company to succeed in achieving ‘Zero Harm’. It is imperative to understand the interdependencies of various leadership aspects in dealing with the achievement of ‘Zero Harm’, a safety culture which is evolving in the South African mining industry. Safety cannot be synthesised out of leadership, management, supervisory acts or executing work as it remains as an integral part of all these activities. Leadership from a safety perspective can become very sophisticated in the minds of some, so much so that some become confused what to do. However, the essentials of leadership boil down to Plan, Do, Check and Act, which is not a new concept (Moen, 2009). The South African Mining Industry fatalities reduced from 220 in 2007 to 73 in 2016 as shown in Chapter 1-Figure 3. The improved safety performance is viewed as a business imperative to ensure long term sustainability, however the industry recognises that much remains to be done as one fatality is one too many (COM 2017). Research was conducted at six major South African gold and platinum deep level mining companies for the period 2007 to 2016 to determine the emerging themes that resulted in the improved safety performance. The companies concerned were responsible for on average more than 50 percent of the fatalities in the South African mining industry. It was found that the leadership of the mining companies had been following a multi-tiered approach in order to reduce safety related incidents in mines. One of the most important drivers of the company’s safety performance is for the company’s leadership to take heed of the broader society’s expectation that mining must take place safely. This awareness must subsequently be institutionalised to articulate the company’s approach to ‘Zero Harm’ and by creating an enabling environment to achieve ‘Zero Harm’. All the activities required to achieve ‘Zero Harm’ should be systemised and enable the transfer of relevant knowledge to employees and establish the required behaviour of all individuals throughout the organisation in order to operationalise the safety management system and by actively reducing workplace risks. The successful implementation of the aforementioned holistic approach will dictate the company’s safety outcomes which should be continuously improved to achieve ‘Zero Harm’.Item Closure estimations from underground observations and their comparison to closure from elastic numerical modelling(2017) Rakumakoe, ObakengThe gold reserves in South Africa have been mined for decades, depleting all the easily accessible reserves. In pursuing the deeper reserves South African mining industry has for many years led the development of mining and particularly rock engineering. Various design criteria and tools have been developed and used by South African rock engineers in different mining environments. It must also be understood that these criteria were developed decades ago in different mining environments compared to where mining is currently taking place. In using these design criteria one needs to look at the relevance of such criteria and question if they are still applicable or if new criteria are required. Scheepers et.al, (2012) reviewed the design criteria used in designing ultra-deep narrow reef stopes in the West Wits and identified that there was no clear correlation between the design criteria used and the seismicity which is the highest FOG risk in ultra-deep mines. They then decided to use modelled elastic closure as design parameter which can be correlated to seismicity. This report details an investigation into the correlation of the modelled elastic closure to the estimated closure from underground and how modelled closure can be adjusted to better reflect the anticipated closure underground. The investigation was conducted using underground observations and stoping width estimations using installed timber support and numerical modelling results (MAP3D). Before correlating the modelled closure and the estimated closure, it was critical to understand the basis of the work done by (Scheepers et.al, 2012) in correlating the modelled closure to seismic hazard. McGarr, (1976) introduced the concept of correlating seismic energy to volume changes in stope. However this correlation was on the basis that the closure in the stope is only as a result of seismic failure. This was the basis of work done by (Scheepers et.al, 2012) in correlating volume change due to seismicity (seismic potency) to modelled closure. It must be understood that (Scheepers et.al, 2012) aim was not for the modelled closure to reflect underground closure, however was to give an indication of the anticipated seismic activity relative to closure. This report further looks at what would the underground closure be relative to the modelled closure which has been used as a design parameter against seismicity. This report showed no correlation between the 0.27m modelled closure determined by Scheepers et.al, (2012) for Mponeng mine to the estimated closure. Through (Scheepers et.al, 2012) work, it was also shown that the correlation of potency to modelled closure was only in the first 10000m2 of mining a new raise line. Seismic potency is highly dependent on the seismic moment of a seismic event and the larger the event, the larger the seismic potency without any consideration to the mining layout. The elastic modelled closure was found to be on average only 55.3% of the estimated closure. The MAP3D model only considered the elastic properties of the rock and did not take into account any discontinuities or non-homogeneity in the rock mass, hence the large difference to the measured closure. It is important to note that seismic potency and elastic closure modelled do not take into account critical factors that contribute to both rock mass deformation and seismicity in deep mines. More work is required to gain a better understanding on the correlation of rock mass deformation in ultra-deep mines to seismicity. Of importance from the research is to acknowledge that the use of modelled elastic closure should always be supported with a good understanding of the actual rock mass behaviour. The elastic properties used in numerical modelling programs could be varied in such a way that the elastic modelling results can closely depict the actual rock mass behaviour in terms of closure. Accurate estimation of closure would be useful in the design of support systems and mining layouts in ensuring the stability of excavations for the required periods. Closure can be estimated by conducting underground measurements and calculated by running numerical modelling programs. Better correlations between the two results would be possible once the elastic properties used in a model are varied until the results obtained from the model are similar to the underground measurements. The inclusion of the backfill material into the elastic model has significant influence on the resultant closure. This was shown by varying the stoping width used in the model. In a pure elastic model without backfill the stoping width has no influence on the resultant modelled closure as it is evident in the elastic closure formula by (Malan, 2003) which does not take into account stoping width. Varying the poison’s ration has very little influence of the modelled closure while the adjustments to the young’s modulus has a significant influence to the modelled closure.Item Autonomous 3D mapping and surveillance of mines with MAVs(2017) Edwards, Stuart RobertThe mapping of mines, both operational and abandoned, is a long, di cult and occasionally dangerous task especially in the latter case. Recent developments in active and passive consumer grade sensors, as well as quadcopter drones present the opportunity to automate these challenging tasks providing cost and safety bene ts. The goal of this research is to develop an autonomous vision-based mapping system that employs quadrotor drones to explore and map sections of mine tunnels. The system is equipped with inexpensive, structured light, depth cameras in place of traditional laser scanners, making the quadrotor setup more viable to produce in bulk. A modi ed version of Microsoft's Kinect Fusion algorithm is used to construct 3D point clouds in real-time as the agents traverse the scene. Finally, the generated and merged point clouds from the system are compared with those produced by current Lidar scanners.Item A spatio-temporal modelling and analysis of digital sensor data for underground mine health and safety(2017) Opiti, Calvin OduorHealth and safety of employees within their work environment is critical. In the mining industry and especially in underground mines, monitoring and management of health and safety of employees is particularly important Most underground mines today are not fully mechanized, except for coal mines. The industry thus still relies on and employs human personnel. Monitoring and managing these mines and hence personnel health and safety as they undertake their trade is therefore a necessity. Implementation of technology, especially in digital sensor systems and real-time spatial analysis systems, provides a means by which health and safety risk factors can be monitored and information gathered to facilitate determination of prevailing risks or prediction of such risks. Technology therefore can be used to make better decisions and implement specialized emergency response to avert or reduce the extent of injuries, casualties and damages in an underground mine. This research project looks into determination of prominent risk factors in an underground mine, determination of parameters for modeling of such risk factors and the implementation of ESRI’s ArcGIS platform for the retrieval and analysis of streaming sensor data about this parameter from an underground mine. A proof of concept (POC) system is developed that analyses streaming digital sensor data and determines the status of the underground mine environment. The results from this analysis are displayed in a dashboard application for a control room environment. The results and achievements of this research project, especially from a dashboard system perspective, show the possibilities of an integrated GIS-based solution for real-time data processing and determination of the prevailing conditions in an underground mine. This solution also opens up a wide pool of possibilities through which systems integration and its benefits can be achieved, especially in underground mines and focusing on health and safety, as previously silo systems can be integrated at data levels, enabling data sharing, analysis, predictions and making of informed decisions.