Mining contractor Murray & Roberts (M&R) Cementation has been awarded a contract by Palabora Mining Company for a 1 200 m deep ventilation shaft.
The shaft, with a lined diameter of 8.5 m, will reach a final blind sink depth of 1 190 m before a drop raise takes it to its final depth.
M&R Cementation project executive Braam Blom says the duration of the project is expected to be just more than three years.
“After mobilisation, site establishment and surface civils have been completed, we expect to conduct pre-sinking until the end of 2019, with the use of our special shaft sinking gantry to a shaft depth of 65 m.”
“A surface headgear and winder installation will then be constructed from January to March 2020. This will facilitate the slow sink to 200 m and the main sink until February 2022. Canadian shutter and lining methods will be employed. The team is expected to conduct shaft stripping by mid-April 2022 and to dis-establish the site by the end of May 2022,” he explains.
Blom adds that there will be no stations or other excavations required, so this will help keep the team in a sinking cycle and optimise production levels.
A relatively small labour force of 123 people will allow for steady main sinking conditions, with some subcontractors conducting surface piling and civil works for the winder and headgear and other site construction.
Shaft drilling itself will be done with two twin-boom Komatsu shaft drill rigs, and mucking by a Komatsu excavator with close to a ton of loading capacity.
“Ground conditions are expected to be a challenge in some areas, as profiled from the cover and core drilling. However, we have various ways of reducing the risk and downtime during these intersections – such as keeping the shaft lining as close as possible to the shaft bottom,” says Blom.
He highlights that the company continuously improves its performance based on lessons learnt from its previous projects. This allows for a constant focus on securing safe, sustainable and efficient shaft sinking, to deliver on the completion target.