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RESEARCH IN ROCK ENGINEERING PAVES THE WAY
FOR SUSTAINABILITY IN THE MINING SECTOR
To mark his promotion to full professor, Prof Francois Malan discussed rock engineering research as a prerequisite for sustainability and growth in the mining sector during his inaugural address.
South Africa has a proud history of mining. In 2020, it contributed R361.6 billion to the country’s GDP and employed 451 427 people. The country’s huge mineral endowment is ranked very highly globally in terms of Platinum Group Metals (PGM), chrome and manganese reserves. This, however, represents a decline in terms of contribution to GDP, gold production and employment relative to the situation a decade ago. Prof Malan believes that rock engineering research can help turn this situation around, paving the way for sustainability and growth in the mining sector.
As a discipline in which Prof Malan is a renowned specialist, rock engineering examines the mechanical behaviour of rock in relation to the physical environment. It also focuses on methods to determine the strength of underground pillars, and hence ensure the safety of mineworkers. According to Prof Malan, South Africa’s economically viable underground ore bodies have a unique tabular structure. It has long been acknowledged that no other mining region of economic significance has ore bodies of a similar geometry, and no country outside South Africa can find a solution to this problem. Home-grown research is therefore essential to understand and improve the exploitation of the country’s mineral reserves.
Prof Malan’s areas of research expertise include numerical modelling, pillar behaviour and mine design criteria. His current research interests include the inelastic numerical modelling of tabular excavations, and simulating pillar behaviour and pillar strength. He is currently exploring the use of a limit equilibrium model to approximate the timedependent relationship between reefs’ normal stress and parallel stress components. This research emanated from the realisation that time-dependency could not be simulated using elastic theory, and even earlier attempts to simulate the fracture zone with viscoelastic theory only proved to be partially successful. Using the limit equilibrium model, Prof Malan was able to simulate closure data, which provided a much better approximation of actual underground closure. This method allows for the simulation of mining increment size and mining rate. However, it is difficult to calibrate the large number of parameters using this model. This highlights the need for ongoing closure monitoring in underground slopes. An important element of Prof Malan’s work is the development of a pillar strength formula that will be effective in South Africa’s bord and pillar mines as the depth increases. Several other studies are being undertaken by the Department’s Rock Engineering Research Group in close collaboration with industry stakeholders. “Everything we depend on in our daily lives is either made from minerals or relies on minerals for its production. Future innovations would not be possible without the support of the mining industry. From renewable energy to electric vehicles and commercial space travel, none of these initiatives would be viable without an increased source of materials, which need to be mined.”
MANDELA MINING PRECINCT SYMPOSIUM
As one of the prominent research partners in the Mandela Mining Precinct (MMP), two of the Department’s senior staff members delivered presentations at the entity’s virtual symposium, held on 21 and 22 June 2021. The symposium was held to celebrate the third year since the launch of the Precinct.
Under the theme “Beneficiating three years of research, development and innovation”, the symposium delivered a variety of presentations, panel discussions and lightning talks, which were intended to thread together the research taking place across the South African Mining, Extraction, Research, Development and Innovation (SAMERDI) initiative. In the process, it illustrated how far South Africa has come in its journey towards the modernisation of the mining industry.
Dr Bertie Meyer, a senior lecturer in the Department, delivered a presentation on achieving optimisation in mining, focusing on optimising both the production cycle and the shift cycle. On the first topic, he emphasised the importance of testing technologies to determine possible optimisation achieved in completing the production cycle, and made several recommendations. On the second topic, he reviewed some existing shift cycles and scenarios.
According to Dr Meyer, the challenges in the mining industry grow daily. These issues contribute to decreased productivity due to less time being spent on the working from where the main income stream is generated. He reported on research conducted to examine various technologies applied within the conventional mining for gold and PGM mines within the stoping production cycle, excluding drilling, but including support, cleaning, charging and tramming activities. The research entailed measuring the cycle time of each activity, capturing the costs associated with each activity, and establishing a baseline cost model from the data obtained to effectively apply this to the BluePrint Cost Model for evaluation purposes.
Prof Francois Malan, Director of the Mining Resilience Research Centre at the University of Pretoria, approached the topic of pursuing novel rock-breaking techniques. His talk focused on the impact of modernisation in rock engineering. In his presentation, he examined analyses of rock engineering formulae currently in use in the South African mining industry. He presented the advantages and disadvantages of each, and made recommendations on a way forward.
He focused particularly on the key aspects related to optimising the pillar design methodology for bord-and-pillar layouts, which included support design for mechanised mining, the effect of no blasting on seismicity and numerical modelling techniques. He also highlighted existing knowledge gaps, which would need to be investigated in order to improve the sustainability of South Africa’s hard rock mines.
With the establishment of the Mandela Mining Precinct’s SAMERDI Research Centre in Mechanised Mining Systems at the University of Pretoria, these two researchers are confident that the Department’s Mechanised Mining Systems Programme will lead the way for future industry success.
