The circumstances of the accident have been detailed in a safety alert by the Mine Safety Operations Branch in New South Wales.

“Pillar extraction operations were being conducted employing a remotely controlled continuous miner and breaker line supports,” the branch said.

“The second lift in the extraction cycle for the pillar was being undertaken when a portion of unsupported rib fell from the solid side without apparent warning. The victim had his back to the rib and was substantially covered by the fallen coal.”

Underground mines in the state also received the following recommendation this month: “Operators of underground coal mines should review the existing assessment of the stability of coal ribs at the mine as required by clause 32 of the Coal Mine Health and Safety Regulation 2004 and ensure support measures are provided, so far as is reasonably practicable, to protect the people who work at the mine.”

The Chain Valley mine was sold by Peabody Energy to well-established contractor LD Operations in 2009.

The continuation project of the mine, currently under exhibition, aims to extend the life of the mine by 21 years to 2030.

The continuation project is based on bord and pillar mining along with mini-wall extraction.