A report from the Department of Mines and Petroleum has shown a man killed at the Nifty Copper Mine last month was struck by a rock weighing 700 kilograms.
The bogger operator, who remains unidentified, was on foot in front of the loader bucket at the time of the accident, with the bogger parked in front of a stope draw point.
The worker was hosing down the rill when a large rock rolled down the rill, striking the worker.
Direct causes of the incident include the large open stope with a falling rock hazard, and the fact that the operator was working outside the cabin of his machine.
It was identified that loading operations were nearly over for the day when the operator chose to leave the cab and hose down the rill while the brow was open.
It was also shown there was no written procedure for clearing stope draw points if blocked or hung up.
Written procedures for such activities are required by r.10.31 of the Mines and Safety Regulations 1995.
The existing procedure for loading at stope draw points allowed free bogging to a location where the top edge of the loader bucket was below the stope brow, allowing a gap of several metres between the brow of the draw point and the rill.
The DMP recommended that mine managers ensure written procedures are available for clearing of any chute, pass, millhole or stope draw point.
Detailed risk assessments are also required to determine rockfall hazards from the backs or walls of open stopes, which can roll and hit workers at the draw point.
Bunds are required to be designed to catch any rocks ejected from the stope where workers might be present, and a procedure should be developed to protect workers at such points.
The department recommended that where a large open stope has a history of rock falls, free bogging should cease when the brow cracks and free rilling ceases, with operations then moving to remote bogging or the next ring should be blasted.