Shafts excavation below 50m have been started in February, 2005.
We adopted a two step method on the shaft sinking operation with 2 or 3 consecutive drill, blast and mucking steps (1.3m + 1.3m) and 1 shaft-lining step (2.6 m) per cycle to optimize cycle time for shaft excavations.
There are three hours allotted for geoscience investigations such as geological mapping, photography of shaft walls, etc., in the excavation cycle time.
This method will provide an average rate of 1.3m/day. And the shafts are expected to reach 500m depth by 2009.
The flow of the shaft sinking operation