The Western Australian Department of Mines and Petroleum has issued a safety alert after misfired explosives were detonated during waste bogging operations.
According to the report, two pieces of cord-based explosives were found in the waste that had already been bogged from the face.
The detonator cord had a nominal core charge of 70 g/m pentaerythritol tetranitrate (PETN), which can be initiated by significant impact, friction or heat.
This type of explosive is typically used for perimeter blasting in development headings, the report noted.
The explosives were detonated when the loader bucket contacted a piece of cord that had misfired during the face blast.
According to the Department, it was fortunate that there were no injuries from the incident.
Misfired explosives can easily be hidden in waste piles and only exposed during bogging operations, the report said.
The alert recommended that loader operators should be trained to identify explosives and possible misfire locations as well as the appropriate action to take.
It also recommended that blast management plans and procedure audits are rigorously applied to each specific blasting application.