Prebake potline restart after power supply interruption

Abstract

In early January 2011 the decision was taken to perform an emergency shutdown of the newly converted prebake potlines of Kubikenborg Aluminium AB (Kubal). This was due to power interruptions that resulted in bath shrinkage, which was followed by the onset of random anode failures in numerous cells when attempts were made to re-energize the potline. The present paper covers the methods for restarting the potline. These methods were first considered and tested on one or two pots to evaluate the individual method, taking into consideration the availability of trained personnel; cell limitations and logistics; metal purity for existing customer supply commitments; environmental regulations; and speed of restart. In addition, the paper will provide the criteria used to select the appropriate re-start procedure for different cell conditions and the results obtained by each of the methods used.