CULLINAN (miningweekly.com) – Raise boring and drilling services group MasterDrilling is nearing completion of a 220 m horizontal raise bore (HRB) trial project atSouthern Africa-focused miner Petra Diamonds’ Cullinan diamond mine, in Gauteng. On Thursday during a site visit to the mine, Petra miningmanager Steven Klopper highlighted that the HRB method of developing access points to the kimberlite orebody had recorded significantly faster development rates […]