Faculty of Engineering and the Built Environment (ETDs)

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Assessment of Quality Management in Major Projects in the Mining Industry in Botswana
(University of the Witwatersrand, Johannesburg, 2024) Pitswe, Odirile Boniface; Sunjka, Bernadette
While project performance is generally evaluated in terms of schedule, cost and quality performance, guidelines for project quality management are lacking, (Steyn and Nicholas, 2008). The Botswana mining industry is faced with problems of engineering projects which don’t meet the expected outcomes and most of the problems emanate around quality management and quality defects. This research project involved the assessment of quality management in major engineering projects in the Botswana mining industry by evaluating the level of adoption and implementation of quality management systems in major engineering projects, identifying the major causes of project failure, and evaluating the effectiveness of quality management system as employed in major capital projects. The research was focused mainly on Debswana Diamond Mining company as the major mining house in the country, with an objective to assess the maturity level of the company’s quality management system (QMS) and identify opportunities for improvement. A mixed method approach was used which involved archival research and survey research, the results of which were triangulated to corroborate the findings and remove bias. Archival research was conducted using the company document repository to review project retrospect reports, (Lessons learnt reports) and identify problems experienced during the implementation of different projects. These were correlated with common causes of project failures as identified in the critical literature review and cross referenced against survey results to further confirm them. The results indicated that the maturity level of the Quality Management system is at level 4 (quantitatively managed), where processes are measured and controlled. Gaps were identified that if rectified would move the maturity to level 5 (optimizing), where the focus would now be on process improvement. The gaps are mainly around operationalisation, lower-level employees training on quality management, optimisation of shared resources especially subject matter experts like project engineers, key stakeholder management, involvement and participation from end users and operational teams. The study came up with the top five (5) major causes of project failure being: 1. Shared resources and subject matter experts get overstretched between different projects and end up neglecting quality assurance. 2. Poor stakeholder management. 3. Lack of stakeholder involvement and participation in the project. 4. Inexperienced project team. 5. Unclear statements of expected quality outcomes.
A report on the investigation into factors that impact the replication of operational excellence programs across the global operations of a top global mining company: The Case of Rio Tinto
(University of the Witwatersrand, Johannesburg, 2024) Tsomole, Moleboheng; Sunjka, Bernadette
Achieving operational excellence in mining is fraught with challenges, including the lack of standardized procedures, misalignment with company strategy, and cultural disparities across global operations. This study investigates the strategies for efficient deployment of operational excellence programs, with a focus on Rio Tinto’s operational excellence framework, RTSPS (Rio Tinto Safe Production System). A mixed-methods approach was adopted, integrating qualitative data from semi-structured interviews with Rio Tinto managers and employees and an analysis of secondary data from company reports. This study combined deductive and inductive research approaches to provide a comprehensive exploration of operational excellence at Rio Tinto. The deductive approach involved testing specific hypotheses drawn from existing literature on operational excellence programs, such as the assumption that standardized systems like RTSPS would encounter difficulties in culturally diverse environments. Inductive reasoning complemented this by allowing themes and insights to emerge directly from empirical observations during interviews, thus offering an authentic view of the challenges and successes of RTSPS deployment. The qualitative component of the study was centered around 14 semi-structured interviews with key stakeholders across various regions, including operational excellence managers and improvement leads. These interviews were conducted virtually using platforms like Microsoft Teams and Zoom, enabling broad participation across geographically dispersed sites. The interview questions were meticulously crafted using Wengraf’s pyramid model, which starts with Critical Research Questions (CRQs) that are broken down into Theoretical Questions (TQs) and further refined into specific Interview Questions (IQs). This structured approach ensured that the interviews remained focused on uncovering detailed insights into operational challenges and strategic alignment. The questions were adapted to account for the contextual nuances of each participant's operational environment, and particular care was taken to avoid leading questions, thereby minimizing researcher bias.The analysis of data employed thematic coding, revealing key insights into behavioural adaptability, cultural diversity, and the influence of leadership on the adoption of standardized processes. Themes were generated from the qualitative data and cross-referenced with secondary data sources, including integrated annual reports that provided a broader organizational context and corroborated the findings. Secondary data analysis allowed for a deeper understanding of Rio Tinto’s strategic objectives and how these aligned or conflicted with ground-level practices. Using qualitative data from interviews with 14 participants, the research highlights key themes identified through thematic analysis, focusing on the complexities of implementing RTSPS across diverse cultural and operational landscapes. Sentiment analysis conducted via ATLAS.ti software provided additional insights into participants' attitudes and emotional responses, shaping the creation of a comprehensive codebook that guided systematic data analysis. The findings reveal that RTSPS faces significant deployment challenges, including the integration of a standardized system across culturally varied sites, a need for a more people-centric approach, and issues with communication, resource allocation, and adaptability. Participants with experience outside of Rio Tinto provided unique insights into alternative deployment strategies that could enhance replication and adaptability across different industries and operational settings. The study also identifies the foundational elements critical to RTSPS, such as standardized processes, robust training programs, and a centralized knowledge- sharing infrastructure. These components were highlighted as essential for fostering a culture of continuous improvement and ensuring successful replication across Rio Tinto’s operations. Rio Tinto's annual reports from 2018 to 2022 emphasize RTSPS's role in enhancing safety, efficiency, and sustainability, with impacts on the triple bottom line of people, planet, and profit. However, the challenges identified through this research include cultural integration, resource constraints, and the need for local adaptability, mirror broader issues documented in the literature on operational excellence in the 7 mining sector. The study concludes that while RTSPS holds significant potential, its success hinges on balancing standardization with the flexibility to accommodate local conditions and prioritizing employee engagement throughout the deployment process.
Financial Evaluation of Implementing In-Pit Crushing and Conveying Systems for Waste on Open Pit Mines
(University of the Witwatersrand, Johannesburg, 2024) Serepa, Ikaneng; Emwanu, B.
The South African mining industry has faced mounting challenges, especially rising expenses that threaten profitability. These escalating costs, driven by various factors including operational expenses such as mining costs, are critical. The distribution of mining costs across activities within the production cycle is crucial, with hauling operations in open pit mines representing a significant portion, as noted by Paricheh et al (2017) at 49%. Due to the substantial economic impact of hauling expenses on mining expenditures, there's a strong incentive to streamline these operations to lower overall costs effectively. Current research highlights a noticeable transition in the mining sector towards embracing in-pit crushing and conveying (IPCC) systems in open pit mines, acclaimed as a cost-effective substitute for conventional truck and shovel (CTS) systems (Awuah-Offei et al, 2009). This research assessed both the integration and financial viability of implementing a waste IPCC system in the loading and hauling operations of an open pit mine. A mixed-methods approach, combining quantitative data from production records and costs with qualitative insights from expert interviews was used. The findings of this research indicate that while the IPCC system can be integrated, there remains a degree of reliance on the CTS system for material transportation from the pit to the IPCC system. For the CTS system, 55 rigid dump trucks (RDTs) are required, constituting 57% of the initial capital expenditure of R1.27 billion. Conversely, the IPCC system requires only 31 RDTs, accounting for 29% of the initial capital costs of R1.37 billion. However, despite the substantial reduction in RDTs, the IPCC system requires significant investment in a crusher and conveyor belt system for waste management, which constitutes 32% of its capital costs. Examination of the operating costs over the life of the mine indicates that there are no cost advantages associated with operating an IPCC system compared to the CTS system. Operating expenses for the IPCC system exceed those of the CTS system by 58%, predominantly driven by the operational costs of the crusher and belt system, contributing to 67% of the IPCC system's costs. The financial assessment results show a positive and acceptable net present value (NPV), internal rate of return (IRR), and payback period for both systems. Nevertheless, the CTS system exhibits superior financial performance, with a NPV of R7.45 billion, an IRR of 83.1%, and a shorter payback period of 1.2 years, and is recommended as a viable option for the mine.
Measurement of combustion airf low into burners in coal fired plants
(University of the Witwatersrand, Johannesburg, 2024) Manqele, Gladwell Sizwe; Schmitz, Walter
This research study is aimed at achieving accurate measurement of mass flow rates in large square industrial square ducts at Eskom’s boiler plants. For safe and efficient operation of Fossil Fuel Firing Boiler Plants, the utility has put in place the Fossil Fuel Firing Regulation Standard which requires that the Total Combustion Air flow be measured at exit from the air heaters, into the ducts. In this study, a sophisticated airflow measuring probe was acquired, herein the current study referred to the 14-hole Omniprobe. The accuracy was found to be within 5% in a free stream flow field. A Five-hole probe was calibrated in the free-stream wind tunnel. The calibration process enabled the derivation of the probe specific polynomials of Pitch, Yaw, Total Pressure, Static Pressure coefficients and velocity components. A prototype air duct was designed for the study to simulate air flow through square ducts with a 90⁰ bend as an abrupt flow disturbance. To achieve the objectives of the study, 6 planes were identified where air flow velocity profiles were generated using the equal area method. The modeling of the velocity profiles was conducted numerically, using CFD (Ansys Fluent), and experimental, using Pitot-static probe, Omniprobe, and a Five-hole probe. The mass flow rates as measured by the Pitot-static tube were found to be consistent at planes 1, 2, 5, and 6. The mass flow rate as calculated from the Pitot-static probe varied by 2.1% through the duct. This justified the selection of the Pitot-static probe as the reference for this study. The velocity profiles generated from the traverse measurements using the 14-hole Omniprobe showed an error in velocity measurements which are in the proximity of the wall. This can be attributed to the the wall effect. The mass flow rates of air calculated from the Five- hole probe measurements were found to be within 4% of the mass flow rate as calculated from the results of the reference probe in the 1st and 2nd planes upstream of the bend. After the 90⁰ flow disturbance bend, the accuracy drops to 13% at plane 5 and improved slightly at plane 6 to 11.7%. This is attributed to complex flow pattern at these planes. The study concludes that the Pitot-static tube remains the preferred instrument for use in measuring flow rates using the equal area method in large square ducts. The Five-hole probe can be applied where the flow field is not distorted in conjunction with CFD. The Omniprobe’s accuracy in measuring the velocity magnitude, and the angularity of the flow field was verified in an open stream wind tunnel. This study recommends exploring the use of an L-type 14-hole Omniprobe for application in large square industrial ducts.
Distributed Electric Propulsion on a Joined-Wing Air-Taxi
(University of the Witwatersrand, Johannesburg, 2024) Brand, Darren Mark; Schekman, S.
Urban Air Mobility (UAM) is a form of aerial transportation within urban areas with the main intention of easing traffic congestion. Electric Vertical Take-off and Landing (EVTOL) air-taxis are currently in development, but no single configuration has been identified as superior for UAM. There is still scope for alternate designs to be explored. A major obstacle to successful UAM operations is the combination of high energy requirements for VTOL and low battery energy densities, thereby affecting operational aircraft range. Aerodynamic efficiency has been identified as a critical factor for achieving maximum flight range while electric battery technology is matured. It is proposed that an air-taxi which combines Distributed Electric Propulsion (DEP) with a joined-wing may achieve superior aerodynamic efficiency compared to other air-taxi designs. A joined-wing air-taxi capable of carrying four passengers and a pilot has been developed with four alternative DEP configurations. These aircraft are herein investigated and compared against one another. A computational approach was followed using STAR- CCM+ to evaluate the flow characteristics and forces around the aircraft for both climb and cruise conditions. It was found that a “Non-DEP” configuration with four proprotors can achieve up to 5% higher aerodynamic efficiency than a DEP variant. However, this configuration suffers with poor lifting capability at high angles of attack. The sensitivity of aerodynamic efficiency to changes in the number of proprotors and their spacing was seen to be negligible according to this investigation.
Investigating Design Parameters for Practical Load Forecasting of Grid-Interactive Buildings Using LSTM
(University of the Witwatersrand, Johannesburg, 2024) Simani, Kyppy Ngaira; Yen , Yu-chieh; Genga , Yuval
The dissertation presented contributes to research in residential load forecasting using machine-learning (ML) models to optimise energy management within grid- interactive efficient buildings (GEB) and addresses the challenge of implementing forecasting models for practical applications. The use of accurate load forecasting ML models has been shown to extend and im- prove the field of energy management towards the resource coordination of GEB. Developing these models is a time-, data- and compute-intensive process that re- quires selection and tuning of various design parameters. In practice however this has costs and limitations: collection and storage of real-time data, measurement device costs and finite compute power. To simplify model development and reduce these costs, this dissertation investigates to what extent the relationships between model parameters and performance can inform ML design decisions. In the research presented, 3 experiments are performed to investigate the relation- ships between training data size, prediction horizon length and data resolution and their impact on the predictive model fidelity. Several prediction models are devel- oped using various parameter settings. The accuracy and compute intensity are measured to evaluate the influence of each parameter on the model performance. A dataset of 3 years and 11 months of residential power consumption measure- ments at a one-minute resolution is used as the load profile for this investigation. For this load profile it is found that increasing training data size increases compute time linearly, with an exponential decay in model prediction error. This results in a maximum, resource-efficient training data size of 450 days. In addition, the effec- tive prediction (i.e prediction models with R2 scores greater than 0) horizon length is found to be 3 hours. At this length the load profile is suited for short-term load forecast applications such as distributed energy resource (DER) and real-time pric- ing (RTP) management. Furthermore, models trained on low-resolution data (up to 30 minutes) can achieve comparable performance to higher-resolution models with at least 3 additional months of training data. The findings of this investiga- tion therefore represent a contribution towards the development of a ML design tool for more efficient design parameter tuning considering practical load forecast- ing conditions. This shows potential to enable more efficient implementations of load forecasting systems for GEB environments.
Estimating Resistance and Performance of Earthing Systems Electrode in Variably Saturated Soil Conditions
(University of the Witwatersrand, Johannesburg, 2024) Nnamdi, Onyedikachi Samuel; Gomes, Chandima
The design and determination of post-installed resistance of earthing systems are significantly influenced by subsoil resistivity profiles, which are prone to seasonal variations due to environmental and climatic changes. These fluctuations can compromise operational safety and reliability of transmission systems, necessitating periodic monitoring of earthing installations as recommended by national and international standards. However, compliance with these recommendations is often impractical due to the vast number of earthing installations and associated costs. To address this challenge, this thesis proposes a novel multiphysics earthing model that integrates hydraulic and electrical properties of subsoil and earthing enhancement materials (EEMs) with climatic parameters to predict earthing resistance under varying conditions. The model, developed by coupling partial differential equations governing electric current dispersion and fluid retention in porous media, is validated through COMSOL Multiphysics® simulations of vertical earth rods in single and double subsoil layers. The results demonstrate that earthing resistance variation is dependent on subsoil texture, water content, and distribution of soil water potential, which determines subsoil resistivity. The proposed method achieves a relative error range of 2.72% to 6.53% and 1.47% compared to analytical and finite element method solutions, ensuring accuracy and validity. This innovative approach enables site-specific and climate-adaptive assessments of EEM effectiveness, facilitating informed decisions for earthing improvements in diverse conditions, and ultimately optimising material selection and recommendation for various soils and climates.
Simulation of a Wet Flue Gas Desulphurization (WFGD) plant in support of continuous grid supply of electricity and compliance to SO2 emission limits
(University of the Witwatersrand, Johannesburg, 2024) Lekhuleni , Tsholofelo Bernice; Mulopo, Jean
The wet flue gas desulphurization plant is susceptible to attrition and corrosion due to the corrosive nature of its operation. It is crucial to prevent plant downtime at any cost, as a plant failure in the WFGD could disrupt electricity supplies to the national grid. Plant failures can be avoided by using models to optimize plant operations and assure higher system performance. In this work, the Aspen simulation was used to forecast the following parameters for a wet flue gas desulphurization process: • Lowest limestone concentration or quality as absorber feed, • Highest volume of gas that can be treated, • Maximum sulphur content that could be treated in the absorber tower. Various reactions such as limestone dissolution, SO2 absorption and crystallization were simulated in Aspen. An equilibrium relation was established where the SO2/SO3 relationship in the absorber reaction could be used to predict the lowest concentration of limestone slurry and the highest volumetric flowrate that could be treated in the absorber. The pH drops in the absorber and the formation of gypsum (CaSO4) also supported the findings of the equilibrium relationship. The lowest limestone concentration limit is 16% compared to a design base of 31%. The maximum volumetric flowrate is in the range of 4,0-4.5 x 106 m3/h. The maximum sulphur content that could be treated is 1.6% S on a mass basis compared to a design base of 0.9%. However, the maximum sulphur was reduced to 1.41 % due to the limestone control dosing valve which can only supply 90000 kg/h instead of the maximum requirement of 94315 kg/h. The equilibrium relations, pH, and gypsum production can all be used to establish safe operating regimes for the WFGD plant.
Investigating flood prevention measures adopted in flood-prone areas of centurion, city of Tshwane metropolitan municipality
(University of the Witwatersrand, Johannesburg, 2024) Kutumela, Ofentse Annah; Leuta, Tsepang
Globally, many countries such as Mozambique, Afghanistan, India, Brazil, the United States (US) and China among others continue to face the persistent challenge of climate change aftermaths, such as rising temperatures, extreme weather patterns and floods. South Africa is no exception, and similar to other countries, especially in the African continent, they lack strategy on how to respond to climate change impacts owing to continuously changing environmental patterns and trends. Therefore, the United Nations (UN) has drafted and implemented the Sendai Framework since 2015 to address disaster risk reduction worldwide, which goes concurrently with the Sustainable Development Goals (SDGs), in particular Goal 13 that deals with a call to Climate Action. The aim of this research was two-fold – first, to investigate prevention measures related to urban planning and land use management regulations that prevent flooding through disaster risk reduction. For instance, interrogating various policies, legislations, plans and programmes that have been sourced to prevent flooding in Centurion such as the Disaster Management Act, City of Tshwane (CoT) Disaster Risk Mitigation Plans, City of Tshwane Flood Incident Management Plan, Water Use Licence Policy, Flood Mitigation Plan and City Support Programme that are categorised as non-structural measures Secondly, to review flood risk reduction and the impact prevention measures that have been adopted in urban flood-prone areas in the CoT, particularly Centurion. The methodology used during this research was the qualitative approach. With this approach, I followed mixed methods research, where in the first stage, I collected primary data through one-on-one interviews through semi-structured interviews, while in the second stage, I conducted site visits as part of my observation. For sampling, I applied non-probability sampling technique known as purposive sampling to select research participants. In analysing the collected data, I adopted inductive thematic analysis to identify, interpret and report the existence of patterns in the data. The aim was to provide meaning to the findings and recommendations of the research. The findings reveal that protection of blue infrastructure is important as encroachment of wetlands continues to be a challenge. Nonetheless, this protection remains preventative measures in the lower catchment. Also, the integration of transboundary municipalities is important as it is not only the town planners' responsibility as professionals to implement disaster risk management but also all internal departments within a municipality. vi Failure to implement urban planning and land use management regulations, policies and or plans within the municipality, especially in Centurion, will potentially lead to significant implications, which may manifest themselves through an increase in debris, sinkholes, more deadly floods along the Hennops River, and adverse impacts as a result of changes in the environment.
Alternative Energy Generation in Public Health Facilities (Hospitals): An analysis of the coal-fired to the natural gas-fired central generating system
(University of the Witwatersrand, Johannesburg, 2024) Nsimbini, Ngcebo
Coal boilers have historically been a significant source of energy generation in industries. However, their use is associated with substantial environmental impacts that are increasingly untenable in the context of climate change. This research examines the challenges and opportunities associated with transitioning from coal-fired to natural gas-fired central generating systems at Helen Joseph Hospital. The researcher chose to focus on natural gas because it is a cleaner and more efficient alternative to coal, making it a viable transitional energy source for decarbonisation in hospital central generating systems. Natural gas functions as a transitional or “bridge” fuel in the global energy landscape. Its relatively lower carbon intensity compared to coal positions it as an intermediate solution that facilitates a gradual shift toward renewable energy sources. This role is critical in mitigating greenhouse gas emissions in the short to medium term, thereby contributing to environmental sustainability and the reduction of public health risks associated with air pollution. The research looks at the low adoption of alternative energy sources in these systems despite their critical role in supporting essential functions such as heating, ventilation, sterilisation, water, and heating. By focusing on energy transition and decarbonisation, the study aims to identify barriers to adoption and propose strategies for implementing more sustainable energy solutions within healthcare facilities, which are among the highest energy consumers in the built environment and are categorised as part of the commercial sector. Focusing on energy transition and decarbonisation, this study employs a case study approach centred on the Helen Joseph Hospital central generating system. Primary data was gathered through 15 in-depth interviews with purposefully selected key informants. The research methodology used qualitative approaches. The interview data were thematically coded and analysed to address the research questions effectively. The findings stress the importance of a multi-faceted, collaborative approach to improve the transition from coal-fired boilers to gas-fired systems in hospitals, with a strong emphasis on minimizing environmental impacts. The study highlights that calculating an organisation's carbon footprint, including emissions from boiler operations, can pinpoint opportunities for energy transition and emissions reduction. Additionally, this approach allows for progress tracking over time and contributes to achieving broader sustainability goals.

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