Due to the economic realities of the world gold mining industry, there is greater pressure on mine owners and operators to achieve greater cost reductions over the entire operation without compromising safety. There has also been a change to a “Mine to Mill” approach with blasting so that more fragmentation is done through blasting in the pit. The path that explosives manufacturers are taking with this is to utilise new technology, not increased costs. It is proposed to use stemming in the upholes at Newcrest’s Ridgeway Gold Mine, near Orange in New South Wales, to augment the confinement and hence, the performance of the explosives. There is currently no stemming of upholes anywhere in the world.
The scope of this thesis is to evaluate the performance of the stemming product produced by Stemtite, known as the Stempac. To evaluate their performance, a number of different methods will be trialled. These include: far-field vibration monitoring, brow analysis and high speed digital photography. The majority of the trials will be conducted at the Ridgeway Gold Mine, owned by Newcrest, operated by EROC and located on the Cadia lease, near Orange, New South Wales. Ridgeway Gold Mine is a large, highly mechanised sublevel caving operation. It is proposed that stemming the production upholes with devices made by StemTite Australia, called Stempacs, will increase the fragmentation achieved in their blasts, as well as increase the safety of the miners through reducing backbreak therefore preserving more of the roof support system, namely primarily shotcrete
Stemming has been defined as “the inert material used to backfill a blasthole for the purpose of containing the explosive energy and reducing the unwanted effects of airblast and flyrock” (Eloranta, 1994). As it is impossible to backfill an uphole due to gravity, StemTite Australia have developed the Stempac. Stempacs contain three small mechanical stemming plugs that lock into the sides of the hole when the explosion gases try to eject the stemming out of the hole. These are the devices that will be trialled in this study.