Yancoal has restarted longwall production at its Austar mine after two workers were killed by an underground wall collapse in April.
Yancoal said while investigations are continuing, longwall mining has been moved to Panel 8, which will provide production for up to 12 months.
The company said it had redeployed around 70 workers to other sites.
Around 35 have been sent to work at Abel underground mine near Beresfield, while the remaining 35 are working at Ashton underground mine near Singleton.
Mitchell and Grant were working about 500 metres below the surface when the wall collapsed, trapping both men.
CFMEU district president Peter Jordan said the accident occurred while the men were operating a continuous miner.
"There was a massive rib failure where a burst of coal came out from the rib – the wall of the mine – and buried part of the continuous miner and in doing so, buried two of the mine workers," Jordan said.