The accident took place at the longwall face 7km from the mine entrance. The 41 year old mine worker was working as part of a six man crew commissioning the longwall after the recent move.
He was pulling a chain attached to mining equipment when the chain snapped, striking him on the head.
He was airlifted to St George Hospital with serious head injuries and he underwent surgery. The mine was closed while investigators from WorkCover and the Department of Mineral Resources examined the accident scene.
Colliery general manager Tony De Santis told the Illawarra Mercury that the accident happened at the longwall face of the mine, which was not operating at the time.
"The injured employee is an experienced miner, having worked in a number of mines in the Illawarra," he said. "He was working as part of a crew of six employees who were commissioning the longwall following a recent longwall move.
"Work has been suspended in the section of the mine where the incident occurred while the investigation proceeds."