Wits School of Mining
Professor Dick Minnitt, JCI Professor of Mineral Resources and Reserves at Wits educating students on the use of new software.
The University of the Witwatersrand’s School of Mining Engineering has seen another productive year with the graduation of five doctoral students.

The Wits School of Mining Engineering is building on its focus on high-level research and innovation for the mining sector in this way.

According to Professor Richard Minnitt, JCI Professor of Mineral Resources and Reserves, the range and depth of the research is an exciting contribution to some key challenges faced by South Africa’s mining sector.

“This sustained, high level of quality research puts the Wits School of Mining Engineering at the cutting edge of mining innovation – in line with the university’s Wits Vision 2022 to become a top-100 institution,” said Professor Minnitt. “It also reflects our close partnership with mining companies, working with them to resolve issues and pursue opportunities.”

Seismic instability under Joburg Central Business District

In his PhD, Sarfraz Ali highlighted the future risk to the safety and stability of surface structures in the Johannesburg central business district arising from mining-induced seismicity, said the Wits School of Mining Engineering.

Available methods for estimating this seismicity, said Ali, do not take into account the complexity of the many steeply-dipping geological formations under the CBD area, underlain by flooded and abandoned mines.

To address this, he applied advanced numerical modelling techniques such as 3DEC (the three‑dimensional distinct element method) and FLAC (the two‑dimensional finite difference method) to simulate various source mechanisms for estimating site-specific ground motions.

The research, said Ali, “has the potential to facilitate seismic micro-zonation, re-mining in the Central Rand and development of building standards for South Africa.”

Deregulating precious metals

Ashok Kumar Damarupurshad’s doctoral thesis is the first attempt to analyse the current debates on regulating the precious metals industries in South Africa. Noting that SA is the only country in the world – apart from the Russian Federation – that regulates the possession, trade and fabrication of gold and platinum group metals, Damarupurshad explores whether the local precious metals industry should be deregulated in the light of changed conditions.

He argues that recent proposals motivated by resource nationalism “are wanting in terms of cost-benefit” and “are problematic in terms of international agreements and trade and competition laws”. Any efforts to deregulate, however, could only be made after “the old problem of illegal mining and trading” is brought under control.

Air flow for safer coal mines

In his PhD research, Tariq Feroze aimed to enhance safety in coal mines by applying a mathematical model to air flow rates close to the face of a heading – where the majority of methane explosions have been found to occur.

Traditionally, this area of the mine is locally ventilated using auxiliary ventilation devices which, while subject to mine standards, is not well understood.

“The correct use of auxiliary ventilation devices can only be carried out once the effect of the system variables associated with each device is very well understood and can be calculated mathematically,” said Feroze. This is important because studying face ventilation systems experimentally is difficult, requiring a large number of experiments that disturbs the mine production cycles.

His research revealed that Computational Fluid Dynamic’s advanced numerical code ANSYS Fluent was an appropriate tool to evaluate the face ventilation of a heading in a three-dimensional environment using full-scale models.

“Ventilation engineers can now estimate the flow rates close to the face of the heading for different practical mining scenarios and ensure sufficient ventilation by using the appropriate auxiliary ventilation settings,” he said.

Diamond potential off Namibia’s coast

In her research, Jana Jacob focused on new methods of quantifying exploration risks in the absence of hard data, with reference to diamondiferous coastal deposits along the south‑western coast of Namibia.

“The submerged beaches within the 4 km coast parallel strip hold great potential for being highly diamondiferous; to date, however, hard data is not yet available to quantify or validate this potential,” said Jacob. “The question is how to obtain sufficient hard data within the techno‑economic constraints to enable a resource with an acceptable level of confidence to be developed.”

Her thesis illustrated how virtual ore-bodies can be created, based on geological proxies as a basis to assess and rank different sampling and drilling strategies.

Improving pillar design

Investigating the board and pillar design procedure in chrome and platinum mines, Rudiger Kersten concluded in his doctoral research that improvement is essential – as current methodologies “suffer from drawbacks that can be detrimental to the mining industry due to over-design or rendering an excavation unsafe.”

Kersten argued that the equations dealing with pillar strength evaluation require correction not only for squat pillars but also for pillars with layers of varying properties and planes of weakness. He proposed FLAC2D/Hoek-Brown simulations to develop full stress deformation curves for typical pillars – to predict the extent of the fracture zones and, to a certain extent, the pillar stresses.

His solution introduced the “mine stiffness” concept to determine the pillar load, “which automatically included the influence of the pillar and strata stiffness, excavation spans, pillar yield and failure”.