Underground mining contractor Murray & Roberts Cementation and its client Palabora Mining (PMC) celebrated the last blast at the new ventilation shaft, which took its depth to a final 1,200 metres below surface on 9 January.
The 8.5 metre diameter upcast vent shaft – which holed through to an already developed return air way at depth – is vital to PMC’s Lift II project. Lift II will develop access to ore resources sufficient to extend the life of this copper mine beyond 2040.
Senior project manager Fred Durand says a key achievement was the project’s fatality-free record, earned over more than a million hours worked.
“The achievement of a million fatality free hours – reached in November 2023 – is more than just a number,” Durand said. “It reflects the deep-rooted safety culture that has permeated every aspect of the project.”
The innovative sinking methods, used for the first time in South Africa, were also carefully focused on achieving zero harm. Murray & Roberts Cementation employed its Canadian shaft sinking methodology, adapted to what became called the PMC way. This method included an innovative solution to poor ground conditions, where the sidewall of the shaft was closed up within 48 hours by means of the shaft concrete lining after every three metres of advance.
“Among the improvements that this facilitated was the removal of the hazardous work by rock drill operators at the shaft bottom, who would traditionally have to install temporary support,” he explained. “We also decided not to conduct concurrent work in the shaft, so there was no risk of danger to anyone below when work was carried out from the stage.”
He emphasised the close collaboration between the two companies to ensure success and safety. The project was significant insofar as there were many lessons learnt which could be taken forward into future projects, he says, further improving the safety record of shaft sinking practice.
“We are already looking ahead to two more important shaft sinking projects within the South African mining sector, where there is potential for certain of these learnings to be applied,” Durand said.
To facilitate streamlined programming on the project, the work ran on continuous operations with two 12-hour shifts.
The vent shaft will replace the two existing vent shafts from the Lift I project, which are likely to be affected as they are in the Lift I zone of influence. In the final stages of the project, Murray & Roberts Cementation will strip out its services from the shaft, lift out the stage and dismantle the headgear.
Final demobilisation of the company’s infrastructure will be carried out during the first quarter of 2024.