ETD Collection

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    Improving reconciliations through geostatistical resource model updates of Phoenix deposits, Tati Nickel mine
    (2019-09-27) Ntshole, Mothusi
    Periodic resource model updates are necessary to bridge the reconciliation variances between the resource model estimates and actual ore mined. As a tool, Mineral Resources reconciliation focuses on identifying, analysing and managing variance between estimated Mineral Resources and actual ore mined. The aim is to minimize the business risk associated with poor resource model estimate performance against actual ore mined at Phoenix Mine. The Phoenix Mine Mineral Resource model update research project incorporates historical and recently acquired drillhole data, other relevant geological information in the form of geological pit floor and face maps to update the Phoenix Mineral Resource model. Employing appropriate geostatistical estimation methods and improved modelling procedures can highlight and overcome some of the causes of observed reconciliation variances. Each of the five domains of the Phoenix resource was estimated through ordinary kriging and indicator kriging as principal methods. Nearest neighbour (NN) and inverse power of distance (IPD) methods were used as a check and where the above geostatistical methods proved inappropriate. The comparison between model estimates from these various estimation techniques and raw drill hole data was undertaken. The results indicate areas of both good and poor correlation across the different methods and sections of the resource. Areas where there is good correlation coincides with good sampling coverage where as poor correlation coincides mostly with portions of the resource where there is paucity of sampling data. Subjecting the individual domains’ resource estimates from the various estimation methods to a validation check against the sampling data assisted in selecting the estimate that honours the sampling data the most. Such Estimate was selected as the most suitable and reported as the Estimated Resources. Indicator Kriging produced better results compared to the rest of the techniques. In domain four geostatistical methods were unsuccessful thus Inverse power of distance method was used.
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    A spatial mine-to-plan compliance framework for open-pit iron ore mines
    (2019) Otto, Theunis Johannes
    A major assumption underpinning this PhD thesis work is that the actual financial returns realised by open-pit mines are not only dependent on agreed upon mine plans but, are also dependent on the level of spatial execution of the mine plans. To ensure the sustainable success of a large open-pit mine two major areas need to be effectively managed namely the quality and integrity of the mine planning process and the spatial execution of the “best” mine plan. Existing literature describes improvements in the mine planning process and the development of more robust and optimised mine plans. Despite improvements in the quality and integrity of mine plans, open-pit iron ore mines often struggle to achieve the targets set in these mine plans, especially from a spatial point of view. Existing literature recognises the value of spatial compliance to a mine plan, but the processes and systems associated with spatial mine-to-plan compliance reconciliation are not adequately addressed. References to practical and integrated approaches for measuring and managing spatial compliance against the approved mine plans are very limited. Where compliance to the mine plan is mentioned, the research has mainly focussed on temporal compliance metrics and have not proposed a comprehensive framework focused on spatial mine-to-plan compliance for open-pit iron ore mines. This thesis took steps towards filling the identified knowledge gaps in existing literature. The purpose of the thesis was to answer the research question on whether spatial compliance can be improved. This was done through the development, implementation and validation of a spatial mine-to-plan compliance framework for open-pit iron ore mines. The framework defines the components and relationships between the components that determine the level of spatial compliance against the tactical mine plan. This allows measurement and ensure effective management of spatial mine-to-plan execution at open-pit iron ore mines. The research methodology followed during the execution of this research thesis was to review existing literature with the aim of establishing the extent and depth of current published information. The thesis then conceptualised and developed a spatial mine-to-plan compliance framework. The approach for the measurement and reconciliation of the spatial mine-to-plan compliance at open-pit iron ore mines was defined. This was followed by the development and application of spatial mine-to-plan compliance driver trees (CDTs). Methodologies were defined for determining, quantifying and interpreting the impact of spatial mine-to-plan compliance performance on the achievement of operational targets and mining flexibility. The research developed the concept of the next best action (NBA) leading to effective decision making. Technology solutions were evaluated and applied to enhance the effectiveness of the framework. Finally, the research was validated through the implementation of the framework at the Kolomela open-pit iron ore mine in South Africa. The Kolomela spatial mine-to-plan index improved from 74% in 2013 to 99% in 2017, confirming that the adoption of the framework led to a significant improvement in the spatial mine-to-plan compliance to the business plan (BP). Insights gained through the application of the CDT contributed to the improvements. Areas that were planned, but not mined at the time of the assessment were targeted through the NBA methodology and the root causes of adverse spatial mine-to-plan reconciliation performance were addressed. Remotely piloted aircraft systems (RPAS) and high precision global positioning systems (HP-GPS) technologies were implemented, thereby enhancing the effectiveness of the spatial mine-to-plan compliance reconciliation process at Kolomela. This was achieved by utilising the technologies to assist with the visualisation of the actual areas mined in relation to the areas planned for mining. The results obtained during the validation illustrated the positive relationship between achieving targeted spatial mine-to-plan reconciliation results and the achievement of budgeted total exposed ore (EO) levels. This confirmed the critical role that spatial mine-to-plan compliance performance plays to ensure the sustainability of the mining operation in the longer-term through maintaining the planned level of mining flexibility. This is achieved by generating the budgeted EO levels which are a proxy for mining flexibility. This thesis contributes to knowledge as a reference based on empirical research validated at Kolomela. The research represents applied knowledge with a significant value contribution that has potential to fundamentally improve open-pit iron ore mining reconciliation practices. The thesis contributes to knowledge in three key areas. Firstly, it developed an integrated spatial mine-to-plan compliance framework for application at open-pit iron ore mines. The framework defined various metrics including a spatial mine-to-plan index. Secondly, it developed and applied spatial mine-to-plan CDTs that provide the ability to drill-down into selected spatial areas within the larger iron ore mine and enable understanding of the root causes of deviations. Lastly, it employed technology solutions (RPAS and HP-GPS) in a novel way to enhance the effectiveness of the spatial mine-to-plan compliance framework.