Modern Mining August 2015

MINING News

The existing processing plant at Cullinan, which was commissioned over 60 years ago. The new plant will be much more efficient, feature AG milling and have a very compact footprint (photo: Petra Diamonds).

Bulk earthworks underway for new Cullinan plant

In its latest trading update, LSE-listed Petra Diamonds says that the bulk earthworks for its new R1,65 billion processing plant at the Cullinan mine near Pretoria have started and all long-lead items have been ordered. The plant is scheduled to be fully operational by the end of FY2017. MDM Engineering has been contracted to deliver the plant. The project has an IRR

of 25 % and a payback period of approxi- mately three years. The new 6 Mt/a ROM capacity plant will utilise gentler processing methods (comminution via attrition) instead of extensive crushing, which is expected to reduce diamond breakage and increase revenue from larger/exceptional dia- monds. This will be achieved through the use of AG (Autogenous) milling (a method

of comminution using attrition to enable self-grinding of ore) and high pressure grinding rolls (HPGR) technology, the lat- ter representing a move away from high impact cone crushing. The new plant will feature enhanced utilisation of XRF X-ray technology to replace conventional DMS processing when treating coarser +12 mm material. Petra says the new facility will result in

Simplified flowsheet of the new Cullinan processing plant.

10  MODERN MINING  August 2015