The Ontario Ministry of Labour has charged Terrace Bay Pulp for an explosion that killed a worker in October 2011.
Charges have been laid against the company, Venshore Mechanical and two supervisors.
One count said a defendant failed to ensure that a tank or container was drained and cleaned of any explosive, flammable or harmful substances to which repairs or alterations.
One man was killed and two others injured when a large blow tank exploded on Oct. 31, 2011.
A court date is set for Nov. 23 in Thunder Bay.
The mill was owned at the time by Buchanan Sales of Thunder Bay. The operation was placed under creditor protection and subsequently purchased by the Aditya Birla Group of India. Refurbishments are underway to convert the mill into a pulp-dissolving operation for rayon manufacturing.