St Ives gold mine - Mining
Conventional drill and blast with truck and shovel mining techniques are employed at all open pits. Grade control is generally by way of inclined RC drilling on grids determined by the ore body characteristics. Load-and-haul is carried out by 90 to 180 tonne dump trucks and 150 to 350 tonne excavators in backhoe and/or face shovel configuration. Mining benches vary from 5m to 10m, and are excavated in passes (flitches) of 2.5m to 3m per flitch. Gold mineralisation is mined selectively to cut-off grades, and segregated into grade ranges to balance the ore production and processing capacities onsite and to maximise cash-flow.
Underground mines at St Ives are commonly extensions of open pit mines. Mines are accessed via declines, drives are developed to access the ore and future stoping production areas. Underground mining at St Ives is predominantly mechanised and conducted by long-hole open stoping (LHoS), with subordinate cut-and-fill and room-and-pillar stoping for the shallower dipping ore bodies. Paste fill and LHoS is used where mandated by geotechnical factors. Electric-hydraulic drilling jumbos and rubber-tyred diesel-powered load, haul, dump machine (LHDs) are used for development and stoping, while trucks are used for load-and-haul operations. Ore from both open pit and underground operations is transported with road trains from individual mining operations to the central St Ives RoM pad.