Name of the Project
Cullinan C-Cut Phase 1 expansion programme.

Location
Gauteng, South Africa.

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

Project Description
The Cullinan mine contains a world-class resource base of 195.4-million carats, including 17-million carats in tailings as of June 30, 2015. Petra plans to capitalise on this by undertaking an expansion programme to increase production to an estimated 2.2-million carats a year by the 2019 financial year, comprising 2.0-million carats run-of-mine (RoM) and 180 000 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 allow for 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  to 38 to 40 carats per hundred tonnes (cpht) in the 2017 financial year to about 49 to 51 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.

Jobs to be Created
Not stated.

Net Present Value/Internal Rate of Return
Not stated.

Value
Not stated.

Duration
The plan is to increase production from 643 724 ct in the 2016 financial year to 2.2-million carats by the 2019 financial year.

Latest Developments
The C-Cut Phase 1 project is progressing well and in line with expectations, with the first drawpoints in the new C-Cut block cave starting production in the fourth quarter of Petra’s 2016 financial year.

The C-Cut Phase 1 block cave production ramp-up will continue during the 2017 financial year, and is expected to contribute an estimated one-million tonnes to 2017's planned RoM throughput of 2.8-million tonnes.

The remainder of RoM tonnes will consist of pillar and reclamation mining of one-million tonnes (providing access to largely undiluted areas) and old, diluted mining areas of 800 000 t. This increase in tonnage throughput of undiluted ore is expected to increase the RoM grade to between 33 cpht and 35 cpht in the first half of the 2017 financial year and between 42 cpht and 44 cpht in the second half of the 2017 financial year, resulting in a planned average RoM grade of about 39 cpht in the 2017 financial year.

RoM grade is expected to increase further to an estimated 47 cpht by the 2018 financial year and to about 50 cpht by the 2019 financial year, when Cullinan's C-Cut Phase 1 block cave is in full production (yielding undiluted ore) and the new Cullinan processing plant is in operation (providing improved diamond liberation).

Two major components of the Phase 1 project, the new ore shaft and the new plant, are expected to be completed in the second half of Petra’s 2017 financial year.

The plant configuration has been altered to use slotted screens, resulting in an effective bottom cut of 1.1 mm to 1.2 mm (up from the previous 1.0 mm). This change has resulted in lower RoM grades being guided for the 2018 and 2019 financial years, owing to a reduction in the planned recovery of finer diamonds, while maintaining the average value per tonne at levels commensurate with previous guidance.

Key Contracts and Suppliers
MDM Engineering (the South African division of Amec Foster Wheeler) Cullinan plant contract and Murray & Roberts Cullinan shaft contract.

On Budget and on Time?
The project is on time and within budget.

Contact Details for Project Information
Petra Diamonds, email info@petradiamonds.com.