macajm
Mining
- Jun 5, 2001
- 26
Has anyone had experience in open-pit production drilling/blasting of previously broken ground?
We are working down to expose old, pillar-extracted coal seam workings. The sandstone overburden for about 15metres above the seam is severely fractured due to highly variable subsidence, and has significant voids. Our objective is to fill any major open voids to enable trucks & excavator to work on benches above. However we are having trouble drilling blastholes (100mm holes) due to lack of air return clogging holes with cuttings, and also broken ground jamming drill and holes collapsing. We can probably use bottom plugs/stemming & liners to contain the explosive - it is mainly a drilling rather than blasting problem.
Any advice would be appreciated.
We are working down to expose old, pillar-extracted coal seam workings. The sandstone overburden for about 15metres above the seam is severely fractured due to highly variable subsidence, and has significant voids. Our objective is to fill any major open voids to enable trucks & excavator to work on benches above. However we are having trouble drilling blastholes (100mm holes) due to lack of air return clogging holes with cuttings, and also broken ground jamming drill and holes collapsing. We can probably use bottom plugs/stemming & liners to contain the explosive - it is mainly a drilling rather than blasting problem.
Any advice would be appreciated.