LSE-listed diamond miner Petra Diamonds’ R4.6-billion C-Cut Phase 1 expansion programme at its Cullinan mine, in Gauteng, is three months ahead of schedule.
This is according to Petra Diamonds mining executive Teon Swanepoel, who spoke at an event hosted by the Southern African Institute of Mining and Metallurgy held in Johannesburg last month.
He highlighted that, as of May, the project was 89% complete.
The C-Cut project will increase production at the mine from 729 496 ct to 2.2-million carats by the 2019 financial year and could extend Cullinan’s life-of-mine (LoM) to 2030.
This could be extended even further if the remnant tons of the areas above the C-Cut are included.
“At acquisition, the LoM was [extended to] 2014, so it was critical that we accessed the ore at a deeper elevation and start a new mine.”
The personnel and material shaft has been deepened from 805 m to 885 m, while the rock shaft has been deepened to 934 m.
Swanepoel noted that the initial dimensions of the rock shaft were 12 m by 2.8 m, but had reached its design limit as the shaft was deepened. Subsequently, the dimensions were reduced to 9 m by 2.8 m from 580 m to the final depth of 934 m.
Cullinan first started production in 1903 as an openpit operation to 1946, when the mine changed to underground operations. Petra Diamonds initially acquired a 37% stake in the mine from De Beers in 2008 and increased its share to 74% the following year.
Petra re-established the economics of the mine and broke away the decline in January 2010, marking the start of the C-Cut project. In June 2015, Petra started undercutting and the mine is expected to reach steady state in 2019. “By the first half of 2019, we should be hitting the full four-million tons,” Swanepoel concluded.