Miners go hi-tech to extract last ounces from SA’s pillars of gold
WITH gold mines closing down and ore bodies being depleted, South Africa’s accessible gold deposits are coming to an end — just over 100 years after their discovery.
All that is left is for mining companies to find new ways, through technological innovation, to get to gold-bearing ore that was not humanly possible to reach before.
AngloGold Ashanti, the thirdlargest gold producer in the world, has launched a new reefboring system. It extracts only the gold ore before filling the hole with cement and chemicals that strengthen the rock to prevent it from collapsing.
AngloGold Ashanti CEO Srinivasan Venkatakrishnan said recently that 40% of the company’s mines consisted of pillars for the safety of miners.
These pillars became broader as the mine penetrated deeper.
“So we’ve left 40% of the gold behind,” he said. This increased as you went deeper.
The new technology would enable the company to exploit these pillar areas.
Venkatakrishnan said the device would not replace conventional mining, nor was it a form of mechanisation. But it would give South Africa’s gold mines more time to retrieve what was previously inaccessible.
“We see this as a potential game-changer and potentially something which could arrest the rate of decline in gold production, but not enough to completely transform it [production],” Venkatakrishnan said.
He said conventional mining, which was yielding less gold, was already shedding jobs and it was essential for the industry to modernise.
The Chamber of Mines said technological innovations were modernising the industry.
“If we don’t modernise our mines, jobs will be lost,” the chamber said.
“If we do modernise, we have the opportunity to sustain our mining industry for longer, ensuring more skilled and satisfying jobs, and creating additional jobs in downstream and upstream industries.”
AngloGold Ashanti started testing the new device in 2013, producing about 3 000 ounces during the initial phase at Tau Tona mine in western Gauteng.
Last year the system at Tau Tona produced about 13 000 ounces. The company said it aimed to increase this to about 20 000 ounces this year.
Venkatakrishnan said the company had invested more than $100-million (about R1.4billion) in the project and the results were finally showing, especially because Tau Tona produces the highest grades.
Conventional mining requires blasting after drilling whereas the new device needs no explosives because it targets the gold ore directly, which is another safety advantage.
However, Venkatakrishnan said South Africa needed about four more years for the device to achieve good production scales. It would also need to operate at two mines producing significant quantities of gold.
The project was still in its testing stage and the design could be changed if necessary.
South Africa, which was once the leading gold producer in the world, is now in sixth place, behind China, Australia, the US, Russia and Peru.
Venkatakrishnan said: “If we get this right in the longer term we would [become the leading gold producer in the world again] because the gold reserves would be depleting everywhere else.
“But it is a tough technology to roll out on scale.”
He said South Africa still had the largest gold reserves in the world.
A gamechanger which could arrest the decline in gold production