The 25 year-old rigger was reportedly struck when a part of the lifting apparatus on a crane broke as a steel trailer was being unloaded from the back of a truck, hitting him in the head.

Sullivan worked as a contractor for Muswellbrook Crane Services, not the mine.

Anglo Coal issued a statement expressing their sympathy to the man's family.

"It is understood the man received fatal injuries as a result of being involved in the unloading of a trailer on the surface," said an Anglo Coal spokesman.

"Ambulance and other emergency services were immediately called to the site when the incident occurred."

Crime scene investigators, detectives and a mine inspector inspected the site and a report will be prepared for the coroner.

Kayuga is currently being developed as the new longwall district for the Dartbrook longwall mine.