The New South Wales Resources Regulator has revealed new information from an investigation to determine the cause of a roof collapse that occurred at Appin Colliery last month.
Appin Colliery is operated by Endeavour Coal, a subsidiary of GM3, and uses the longwall method of mining.
A suspected gas and rock burst occurred on April 6 while workers operated a continuous miner underground. Four workers were in the vicinity, with three were partially buried by the fallout.
All workers were safely removed from the mine and taken to hospital for treatment.
The NSW Resources Regulator launched an investigation at the time, which is still underway. However, more details have been revealed around the circumstances of the incident.
“Four mine workers were operating a continuous miner about 133 metres in bye of 11 cut-through at B heading in the Razorback Mains development panel. The heading runs parallel to a known geological structure,” the NSW Resources Regulator said.
Earlier, sections of the heading were developed using a grunching mining method, which is an outburst mining control method that removes persons from the face in identified high-risk areas, by progressively advancing the mining face using shotfiring.
At the time of the incident the development of the heading had returned to normal mining methods using a continuous miner under the approved authority to mine.
At 2:15am workers were positioned on the platforms of a 12CM30 continuous miner. They had completed mining the cut-out sequence and were preparing to position mesh and bolt up to the mining face. The roof and ribs in the vicinity of the workers was supported by installed bolts and mesh.
An estimated 100 tonnes of sandstone roof material and gas then abruptly ejected above the coal seam in the heading roof, hitting and partially burying the continuous miner and three of the four workers.
The Regulator’s investigation will continue to assess whether the incident was caused by geology or gas, and the adequacy of the site’s safety protocols and safety management plans.
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