Mining at Dugald River is underground with the long-hole open stoping method favoured. Currently the deposit is accessed by two declines.
Dugald River is transitioning to an owner miner model for production activities, which will partially mitigate cost escalation.
The orebody access is split into a north and south mine, due to its 2 km strike length and a low-grade zone at the extremities of the orebody.
The north mine is narrow (average ~5 m true width) and sub-vertical. The south mine is wider than the north mine with a flexural zone in the centre. The south mine is narrow and steep in the upper zone (~top 200 m from surface) and lower zone (~below 700 m from surface). The central zone is flatter and thicker than the upper and lower zones.
Mining methods for the mine are Sub-Level Open Stopes (SLOS) both Longitudinal and Transverse in the South Mine and modified Avoca stoping or Core & Shell stopes with rib pillars in the North Mine. Level intervals occur every 25m and stopes have a strike length of 15m.
The stopes are broken into the following categories:
- Longitudinal SLOS, for stopes upto 10-15m wide horizontally. (Where the orebody has thickened adjacent stopes are mined in sequence after paste filling);
- Transverse SLOS, for stopes where the orebody thickness lends itself to sequential stope extraction retreating along cross-cuts;
- Crown pillar SLOS, for the top level of each panel where stoping ........
