A major power outage on December 29, 2011 forced the closure of two of the plant's four production lines.
The process of gradually restarting the 280 cells that were shut down will begin over the coming days and should be completed in Q2 2012.
The power cut was caused by a circuit breaker failure leaving Shawinigan without the power needed to operate at full capacity.
The Shawinigan smelter was commissioned in 1941 and employs 450 people. It uses Söderberg technology, which is to be phased out of all Quebec primary aluminium smelters by December 31, 2014 at the latest, in compliance with Quebec environmental regulations.
