Solid Energy has confirmed the West Coast's largest underground coal mine has been closed for almost six months for a safety upgrade.
The Spring Creek mine is about to re-start production after changes prompted by a series of explosion at the Pike River mine which began on 19 November when 29 men were killed.
The Engineering, Printing and Manufacturing Union says the company has now lifted the mine to the standards used in Queensland.
Assistant secretary Ged O'Connell says it is now clear that the safety systems in place at the time of the disaster at Pike River were appalling.
Solid Energy says the upgrade has meant the loss of about $30 million worth of production.