Name and Location
Cullinan C-Cut expansion programme, Gauteng, South Africa.
Client
Petra Diamonds (74%), Thembinkosi Mining Investments (14%) and the Petra Diamonds Employee Share Trust (12%).
Project Description
The Cullinan mine contains a world-class resource base of 200.8-million carats, including 17-million carats in tailings. Petra plans to capitalise on this by undertaking an expansion programme to increase production to 2.2-million carats a year by the 2019 financial year (FY).
This expansion plan, known as C-Cut Phase 1, will establish a new block cave on the western side of the orebody, in the upper portion of the major C-Cut resource, which is estimated to contain 133-million carats and will also involve a large tailings operation.
The development plan will enable the tonnage profile to gradually switch from diluted to undiluted ore. As a result run-of-mine grade is expected to increase in future years to about 35 carats per hundred tonnes (cpht) by FY 2015, 37 cpht by FY 2016 and to more than 50 cpht by FY 2019, when the C-Cut Phase block cave is in full production
Petra’s current mine plan has a life of 17 years, but the major residual resources at the mine indicate that the actual life-of-mine could be more than 50 years.
Value
Not stated.
Duration
The plan is to increase production from one-million carats in 2011 to 2.2-million carats by FY 2019.
Latest Developments
C-Cut Phase 1 is on track, with the development of the declines, access tunnels and shaft deepening all progressing in line with expectations.
Tunnel development activity ramped up significantly in FY 2013 to 4 147 m, while raiseboring delivered 626 m.
During FY 2013, several refinements were approved to allow for increased flexibility in the delivery of Cullinan’s expansion project and to equip the mine’s infrastructure to handle tonnages from the whole footprint of the orebody – 16 ha versus the 5 ha block, which will be accessed for C-Cut Phase 1 – should there be a future decision to ramp up the underground operation above the current planned four-million-tonne-a-year rate.
These refinements followed progress with detailed planning, design and costing work, which resulted in additional capital requirements to cater for enhanced engineering requirements, specifically:
• the upgrade of support specifications to cater for the expected longer life of the block cave;
• the inclusion of a permanent batching plant to deliver concrete to shaft and production infrastructure, freeing up shaft time and reducing potential production disruptions; and
• the optimisation of the 880 mL ore-handling systems including crushers, conveyors and the shaft barrel, from 581 mL to 930 mL, allowing for potential future production ramp ups using the entire C-Cut footprint.
Key Contracts and Suppliers
Murray & Roberts Cementation (deepening of Shaft 1 and Shaft 3, as well as associated infrastructure and planned level development) and ABB (upgrade of the Koepe winder and ropes).
On Budget and on Time?
Not stated.
Contact Details for Project Information
Petra Diamonds, tel +27 11 702 6900, fax +27 11 706 3071 or email info@petradiamonds.com.
Murray & Roberts Cementation, tel +27 11 201 5000.
ABB (South Africa), tel +27 10 202 5000 or fax +27 11 579 8000.