"Waste rock" is the term given to either rock that does not contain gold or contains gold in such low concentrations that it cannot be economically processed. Typically waste rock surrounds the higher concentration economic rock, known as ore, and must be removed for access. Waste rock from open pit mining is trucked to and stacked in areas referred to as waste rock "dumps".
At Mt Charlotte the tunnels or "drives" and areas around the ore are dug out by the process termed "development". Development generates waste rock. Underground the waste rock is put to use by backfilling old underground caverns or "stopes" from which ore has previously been mined. Mt Charlotte receives extra waste rock from the Super Pit to add to stope backfilling.
KCGM undertakes continual review and optimisation of waste rock dumping plans and trucking routes to keep the dumps at short distances from the open pit mining. By optimising haul routes we envisage making substantial reductions to energy use and thereby lowering our greenhouse gas emissions.
Waste rock is used for:
- rehabilitation (to increase the effectiveness of revegetation programmes, particularly for tailings storage facilities); and
- aggregate (to be crushed and used as concrete aggregate and as road pavement material for re-supply to KCGM operations or for sale to third parties).
KCGM waste rock dumps are a significant feature of the surrounding landscape and are very visible. KCGM continues to work on designing the final form of the waste rock dumps to ensure they are properly integrated into the landscape. The best design for the waste rock dumps is one that can be gradually built over the life of the mine but once in final form will have the characteristics of other landforms in the region and provide a variety of habitats for plants and animals.