The fine was part of the convictions concerning the death of Barry Edwards at the Awaba mine, south of Newcastle. Charges against former mine manager Peter Lamont Foster were dismissed.

The convictions have been challenged by Centennial, which lodged an appeal last month.

The appeal was aimed at overturning criminal liability for workplace death and injury. Defendants currently face criminal liability, but Centennial said if an offence carried criminal liability then the defendant must get the same rights as would apply in a criminal case.

Centennial argued the NSW Industrial Relations Commission had no jurisdiction to find employers criminally liable for workplace death or injury.

The Construction Forestry Mining and Energy Union is opposed to the appeal and warned, if successful, Centennial could expect a significant industrial backlash.

Coal miners' union national president Tony Maher told ABC news Centennial had a moral obligation to drop the appeal.

"Workers and their families don't need laws to be tested. The Government makes the laws; we've just got to deal with the consequences of tragedy," he said.