The Voerde smelter, which makes about 10% - or 115,000 tonnes - of Germany's yearly aluminium output a year, declared insolvency in May 2012. The plant in the state of North Rhine-Westphalia employs about 280 staff.
Germany's metals industry association WVM has said the Voerde case illustrates the danger to metal output from high electricity prices, which are among Europe's most expensive partly because of green schemes to promote renewable energy.
The insolvency process could be concluded in March 2014.
US metals group Aleris bought Voerde's cast house last August. Buyers are now being sought for the separate electrolysis and anode production units at the plant.
Voerde Aluminium's creditors had agreed on Sept 27th to continue production until at least the end of this year.