Name and Location
Cullinan C-Cut Phase 1 expansion programme, Gauteng, South Africa.

Client
Petra Diamonds (74%), Thembinkosi Mining Investments (14%) and the Itumeleng Petra Diamonds Employee Share Trust (12%).

Project Description
The Cullinan mine contains a world-class resource base of 199.6-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, comprising two-million carats run-of-mine (RoM) and 200 000 ct of tailings.

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, it will also involve a large tailings retreatment operation.

The development plan will enable the tonnage profile to gradually switch from the old mining areas, heavily diluted with waste rock, to the new mining areas, thereby providing access to undiluted ore. As a result, the RoM grade is expected to increase in future years from about 26 carats per hundred tonnes (cpht) to more than 50 cpht by the 2019 financial year, when the C-Cut Phase 1 block cave is in full production.

Petra’s current mine plan envisions a life-of-mine (LoM) to 2030, but the major residual resources at the mine indicate that the actual LoM could be more than 50 years.

Value
Not stated.

Duration
The plan is to increase production from 800 000 ct in the 2014 financial year to 2.2-million carats by the 2019 financial year.

Latest Developments
Petra Diamonds has reported that the C-Cut Phase 1 project is progressing well, with the first rings in the undercut having been blasted in June 2015, the deepening of the men and material shaft completed and the deepening of the ore shaft on track.

C-Cut Phase 1 waste development yielded 4 282 m for the 2015 financial year, compared with 5 597 m in the previous financial year, while raiseboring delivered 614 m, compared with 854 m in 2014.

Meanwhile, development work is transitioning from waste tunnelling in the host rock to tunnelling and undercut level development into the kimberlite, thereby delivering undiluted kimberlite tonnes, which is expected to lead to a further improvement in the RoM grade profile during the second half of the 2016 financial year.

Kimberlite development to prepare the new block cave yielded 2 285 m in the 2015 financial year, compared with  72 m in the 2014 financial year.

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?
The project is on time and within budget.

Contact Details for Project Information
Petra Diamonds, 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.