Restarting Electrochemical Cell with Cold Metal (D18 Cell)

Aluminum is produced by electrical electrolysis in molten electrolyte by passing electrical current. The main part of aluminum production operation is performed in reduction pots at 960 °C. If power cut-off lasts longer than 3 h, most probably the pots will get cold so continuing the process will be impossible. In this case cut out pots from the production cycle will be urgent and removing the electrolyte and molten metal will be impossible because of the number of pots. The reasons of power cut-off can be failures that take place in power supply; rectifier department or electric network. The process of restarting these pots with cold metal layer, called Cold Metal Method, is very complex and needs fast reaction in operation, experience and safety precautions, especially at the first 24 h. In this method of restarting pots, at first the electrolyte and metal is removed from the pot completely, then preheating is done by a resistance layer (resistor). The pot is then returned to the producing cycle. 87 pots were restarted by this method. The average cell life of restarted pots was more than 738 days. About 15 pots are still in operation after the restarting cycle.