Modern Mining November 2016

DIAMONDS

advanced stage. The company also facilitated the engineering for the Koepe winder upgrades. The two winder upgrades were completed in December 2014 and December 2015 respec- tively, taking advantage of the holiday breaks so as to minimise disruption to operations. Murray & Roberts Cementation deployed around 380 people on its contract at peak but this has now reduced to about 60 people as the contract draws to a close. Says Duyts: “This has been a very successful contract from our point of view and we’re very proud of the fact that we’ve managed to meet all key dates and maintain a safety record that is ahead of indus- try norms. Factors contributing to our success have included the excellent relationship we developed with the Petra team and the inten- sive planning we put into every stage of the work. It also goes without saying that you need to have the right people on the job and this was certainly the case here.” Commenting on the overall state of progress on the C-Cut project, Cloete says the project is running within schedule and budget. “The first undercut rings were drilled and blasted during June 2015 and the first draw bell drilled and blasted during January this year,” he states. “In terms of waste and blue (kimberlite) develop- ment, we’ve completed approximately 22 km of the nearly 27 km required. Of the total capital budget of R4,2 billion, around R3,4 billion has

been spent – which is over 80 %. The first ore from the C-Cut was delivered a year ago and we’re expecting the project to contribute 1 Mt of the total ROM production of 2,8 Mt planned for our 2017 financial year, which runs to 30 June 2017. “Full production will be achieved in FY2019, by which time carat production will have increased from 0,68 Mct/a currently to around 2,2 Mct/a, with all of this – other than about 200 000 carats from the reprocessing of tailings dumps and around 120 000 carats from the upper levels – being derived from C-Cut ore. The project is transformational for Cullinan and will ensure that the mine remains Petra’s flagship for many years to come.” 

Draw point on the extrac- tion level.

State of-the-art plant under construction The C-Cut project is not the only major capital investment in prog- ress at Cullinan. Petra Diamonds is also in the process of replacing the present sprawling treatment plant, originally commissioned in 1947, with a state-of-the-art processing facility, which will have a compact footprint, a high degree of energy efficiency and feature modern technologies – such as autogenous milling – designed to increase dia-

mond liberation and minimise breakage of the large gem-qual- ity stones for which Cullinan is celebrated. The plant, which will deliver a R20 to R25 saving per tonne in processing costs, is expected to be fully operational by the end of Petra’s 2017 financial year. The capex for the project is R1,65 bil- lion with payback anticipated in just three years. 

November 2016  MODERN MINING  33