A "minor explosion" at Queensland Nickel's Yabulu refinery has forced the closure of one of the embattled facility's roasters.
A spokesman for the company's administrators, FTI Consulting, said no one was injured in the incident, which happened in one of 12 roasters about 9.30am on Tuesday.
He said the explosion was caused by a build up of unexploded "hydrocarbon" which was ignited when staff fired up the roaster after a period of shutdown.
Workplace Health and Safety has confirmed it is aware of an incident at the refinery and is making preliminary inquiries.
The spokesman told AAP the area around the roaster has been isolated and would not be turned on until after investigations by authorities and administrators.
He says the explosion was fully contained and pressure release mechanisms were in place.
The damage is understood to be minimal and the refinery's 11 other roasters are still operational.
The Australian Workers Union and administrators have previously raised the issue of safety at the refinery.
AWU Queensland secretary Ben Swan said the union expected to be briefed on investigations into the explosion.
"Any issues like this are always a concern," he told AAP.