How a rock and gold-plated watch swayed a research career

12 February 2019 | Story Munyaradzi Makoni. Photo UCT. Read time 9 min.

Professor Aubrey Mainza’s career has shifted from thoughts of studying medicine in Zambia to becoming a renowned researcher in mineral processing and metallurgy in South Africa. Now his work focuses on improving the efficiency of major mining operations around the world.

As a young person, Mainza saw himself as a medical doctor – with a white coat and stethoscope in hand. But in 1993, when he was among the students invited to visit the University of Zambia’s medical school after a first year of introductory courses, he had a change of heart.

“The first thing that they showed us was the mortuary and the dead bodies,” recalls Mainza. The guide for these prospective medical students also explained the primary role of a doctor is to prevent premature death. Although he considers medicine a noble career, Mainza did not want to be involved with death and dead bodies, and he closed the door to this career before it started.

While considering other options for his studies, he spoke to Professor Stephen Simukanga, who was then the head of metallurgy and mineral processing at the University of Zambia.
 

“What do you do?” Mainza asked Simukanga, who took a piece of malachite – a gemstone – from his desk and lifted it to his gold-plated wrist watch. “We turn rocks into metal,” he replied.

“What do you do?” Mainza asked Simukanga, who took a piece of malachite – a gemstone – from his desk and lifted it to his gold-plated wrist watch. “We turn rocks into metal,” he replied. Simukanga’s response left an indelible impression on Mainza.

“That was it. He did not need to say anymore.”

Making the move

Mainza went on to study mineral processing and metallurgy. After graduating in 1998, he worked at Zambia Consolidated Copper Mines, one of the largest copper producers in the world at the time.

A silver jubilee at the organisation in 1998 was to change Mainza’s fortunes. At the event, he gave a presentation on the use of reagents in processing copper and cobalt. Three important men from UCT were in the audience: Professor Peter Gaylord, Martin Harris and Professor Malcom Powell. Immediately after the conference, they offered him a scholarship to pursue his postgraduate research at UCT: an offer which he accepted.

Unlike some researchers who struggle to find support early in their careers, Mainza had a different experience. For instance, applying for his first postgraduate grant, he says, was “not difficult at all. The Centre for Minerals Research at UCT has a good support structure. When I applied for my first grant, there was an internal review of my application, which contributed to making it a success.”
 

Unlike some researchers who struggle to find support early in their careers, Mainza had a different experience.

Mainza was awarded a grant by the Technology and Human Resources for Industry Programme from the Department of Science and Technology, and he has since moved up the ranks to become a professor in the UCT Department of Chemical Engineering.

Mainza has supervised more than 35 postgraduates, published more than 60 papers in international peer-reviewed journals and refereed conference proceedings, reviewed more than 25 papers himself, and last year he was appointed a UCT Fellow.

Research with real-world application

Mainza’s research revolves around improving the efficiency of the first step in extracting metals from ore, called comminution. Comminution processes reduce the size of ore particles to expose minerals of interest. Developing more efficient methods for grinding ore into finer particle sizes is a growing area of research because the energy requirements of the process are very high.  
 

Mainza’s research revolves around improving the efficiency of the first step in extracting metals from ore, called comminution.

Mainza is developing mathematical models to improve processes in plants for crushing and grinding, as well as in the accompanying devices that sort particles by size. The aim of these models is to improve the processing of the ore by reducing expenses both in the design of new systems and running of current systems.

“I don’t just develop these models, but I actually test them in plants to see what their limitations are,” says Mainza. “If the process is not efficient, the energy and water requirements will be very high and various minerals will be lost to tailings [mine waste].

“This represents a loss of important resources that should be conserved or used more efficiently.”

Mainza adds that his work is not only aimed at mining companies but also at helping communities. He notes that if the cost of production per tonne were lower, it would mean room to employ more people.
 

“If we improve the technologies, we will be able to recover more from the ore and from old tailings dams.”

“Most mines now are processing low-grade materials. If the cost of production is high, there will be no incentive to invest in opening new mines,” he says.

When mining started, many years ago, the technology was poor. Now, most of the same equipment acquired in the 1970s is still in use.

“If we improve the technologies, we will be able to recover more from the ore and from old tailings dams,” he says. “In future, we must aim not to throw away anything.”

Mainza has applied some of the models developed from his research to local mines. His research on fine grinding supports Anglo American Platinum, which has installed 23 fine-grinding units, and Lonmin, which has installed five such units. Other mining companies are in the process of introducing these technologies.

A wish to focus on Africa

Mainza, whose work has taken him around the world to a variety of mines, says his wish is to focus more on Africa, particularly southern Africa where mining is a significant contributor to national economies.

All this work comes to nothing if the knowledge is not passed to future generations and taken up by operating companies, says Mainza, who is supervising four doctoral and five master’s students.
 

Mainza, whose work has taken him around the world to a variety of mines, says his wish is to focus more on Africa, particularly southern Africa where mining is a significant contributor to national economies.

Mainza is the current chairperson of the Global Comminution Collaborative, a group of international experts in the field of comminution. The collaborative has been very good for developing students because they can learn from the various eminent professors who are members.

“Students are the future of our country. We should nurture them well,” he says. “When you have good students, they are able to own their research projects while developing themselves as experts in the field.”

“As a collection of people at UCT, we can share ideas about how we can make this institution better,” Mainza concludes.


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