Peak Gold Mines (PGM) has confirmed that a blasting event that occurred last Thursday at New Cobar, which was felt in town, was indeed bigger than normal.
The blast, which was detonated at 3.05pm last Thursday was in a stope approximately 600m below surface and was what the mine calls a “life of mine” blast.
Peak’s senior short term planning engineer Christine Miles explained the process.
“When we extract ore normally, we occasionally have to leave some ore behind for access or stability issues,” Christine said.
“The ore that is left for stability reasons will never be recovered, but if it was an access reason, we call this a “life of mine” (LOM) area. It doesn’t mean that we are at the end of the mine, just a particular region.”
She said quite often LOM stopes require some unique drilling and blasting techniques to extract, and due to their nature, are often very large in size (high tonnes).
“This one was 35,000t, which is big for PGM,” she said.
PGM’s environment and social responsibility supervisor Sophie Bereyene said the LOM blast was carried out in order for the New Cobar operation to continue.
“We were expecting this blast to be larger than our regular blasts, however mitigation measure were taken during the blast design process to ensure the impact felt in town was as low as possible,” Sophie said.
“The recorded blast vibration levels were within our EPL and development consent limits of 5mm/s. PGM have also installed further vibration monitors to get a better understanding of the vibration levels in town.
“It was approximately a 40,000 tonne stope.
“Our average is 9,000 tonnes,” Sophie said.
Remote operated loaders have now commenced taking the ore out.
“We don’t put people in the loaders when going into the stope,” Christine explained.
“When the ore is stockpiled safely, the loader operator gets back in the loader, puts it into a truck which is then taken to surface.
“These trucks can be seen from the lookout going up the pit. “