The sinking of the 1,200-metre deep ventilation shaft at Palabora Copper is proceeding apace, notwithstanding the Covid-19 shutdown and restrictions.
Work began on the 8,5 metre diameter shaft early in 2019; pre-sinking has reached a depth of 50 metres and the changeover from pre-sink to main sink is almost complete, according to Murray & Roberts Cementation project executive mine development Graham Chamberlain.
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As part of the development of Palabora Copper’s new LIFT II underground block cave mining area, the shaft will be developed to a final blind sink depth of 1,190 metres, with a drop raise to its final depth. Completion is expected in the third quarter of 2022.
“We were required by the client and national lockdown regulations to pause our work schedule, but operations resumed as planned when restrictions were relaxed,” says Chamberlain.
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“The priority is to ensure that safe working conditions are maintained, and the Covid-19 infections are avoided.”
The project is using automated machinery at the shaft bottom, removing employees from high risk contact areas. Modern, high-penetration rate hydraulic drills are deployed on robotic arms nested on the shaft-sinking stage. This allows operators to conduct drilling at any position in the shaft without physically being in contact with the drills.
“We shorten our cycle times with the use of explosive delivery pods containing sensitised emulsion,” he says.
“Electronic systems deliver real-time data on blast holes numbers, volumes and pressures, improving blasting efficiency and quality.”
To reduce potential disruption from the intersection of poor ground conditions, Murray & Roberts Cementation takes the shaft lining to the bottom of the shaft during sinking.
In the past, industry practice tended to carry this lining to about 20 metres from the bottom.
“Our lining approach is applied with the use of a modified version of the traditional shuttering, and our specialised concrete mixes which we design for this specific purpose,” he says.
“The mixes are prepared and delivered by our on-site batch plant.”
Chamberlain highlighted that the company’s focus on Zero Harm and a rigorous safety regime continues to deliver a high level of safety on the project.