Use of Electrical Contact Fundamentals in the Aluminium Smelting Industry - A Case Study

Primary aluminium production is an energy-intensive process. About one quarter of the production cost for primary aluminium is electrical energy. Minimising the losses associated with electrical conductors and connections should play an important part of both aluminium smelter design and ongoing plant optimisation. Literature pertaining to the specific application of high amperage DC electrical connections in the aluminium smelting industry was not readily available and it was necessary to draw upon material from other disciplines and study the most appropriate variables for this application. A number of learnings were achieved relating to suitable clamping pressures and surface preparations for the aluminium smelting industry, with the main conclusion being that a welded connection should be performed where possible. However, if a bolted or clamped connection must be made, then it can be done so effectively. A case study is presented to demonstrate what has been achieved in practice. A clamped aluminium-aluminium bus connection was designed to overcome access constraints for the reinstallation of an aluminium reduction cell. The connection operates safely at approximately 150°C and 29 kA DC. Electrical savings were achieved to offset modification cost through careful consideration of contact losses, clamping configuration and conductor cross section.