Building on its focus of high-level research and innovation for the mining sector, the University of the Witwatersrand (Wits) School of Mining Engineering has had another productive year, with five doctoral students graduating.

According to Wits School of Mining Engineering JCI Mineral Resources and Reserves professor Richard Minnitt, the range and depth of the research are 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 global top-100 institution,” he says, adding that it also reflects the school’s close partnership with mining companies, which involves working with them to resolve issues and pursue opportunities.

One of the students, Sarfraz Ali, detailed in his PhD thesis the seismic instability below the Johannesburg central business district (CBD), highlighting the future risk to the safety and stability of surface structures in the CBD.

Ali’s research notes that available methods for estimating this seismicity did not take into account the complexity of the many steeply dipping geological formations under the CBD area, where there are flooded and abandoned mines.

To address this problem, he applied advanced numerical modelling techniques, such as the three-dimensional distinct element method and the two-dimensional finite difference method, to simulate various source mechanisms for estimating site-specific ground movement.

Ali’s research has the potential to facilitate seismic microzonation, remining in the Central Rand basin and the development of building standards for South Africa.

Ashok Kumar Damarupurshad’s doctoral thesis focused on an analysis of the current debates on regulating the precious metals industries in South Africa. Noting that South Africa 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 explored 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. Damarupurshad notes that any efforts to deregulate, however, could be made only after “the old problem of illegal mining and trading” is brought under control.

Air flow in underground coal mines is adjusted to make such mines safer and Tariq Feroze argues in his PhD research that a mathematical model can be applied to air flow rates close to the face of a heading, where the majority of methane explosions occur, to ensure better ventilation.

Traditionally, this area of a mine is locally ventilated using auxiliary ventilation devices which, while subject to mining standards, are generally suboptimally understood, according to his research.

Feroze notes that auxiliary ventilation devices can be used correctly only once the effect of the system variables associated with each device is well understood and that can be calculated mathematically. Owing to physical analysis, this traditionally requires a large number of experiments that disturb mine production cycles.

His research revealed that computational fluid dynamics’ 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.

In her research, Jana Jacob focused on new methods of quantifying the exploration risks associated with diamondiferous coastal deposits along the south-western coast of Namibia, where a 4 km stretch of submerged coastline is likely to be highly diamondiferous, in the absence of hard data.

Jacob noted that, to date, hard data is not yet available to quantify or validate this potential. “The question is how to obtain sufficient hard data within the technoeconomic constraints to allow for a resource with an acceptable level of confidence to be developed.”

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

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