![]() Here, the anodes are placed in a furnace at a temperature of 1120☌ for a period of up to two weeks. Once formed, the anodes are transferred to a “bakehouse”. These materials are mixed together in heated containers and poured into moulds. Prebake anodes are produced in an area of the smelter called a “green mill” and are made from petroleum coke, pitch and recycled anode butts (the ends of the consumed anodes remaining at the end of their life) returned from the smelting process. The efficiency of this technology compared to Søderberg, combined with its lower environmental impact, means that prebake smelters predominate (representing over 90% of worldwide aluminium production), with all new facilities built today utilising this technology. Prebake technology utilises anodes which are baked in very large gas-fired ovens at high temperature before being lowered into the pot. The heat generated by the reduction process is used to bake the pitch into the carbon form required for reaction with alumina, thus recycling the waste energy in the pot. ![]() Søderberg smelters use a continuously created anode, made by the addition of pitch to the top of the electrolytic cell or “pot”. ![]() The two families of smelting technology in operation today – Søderberg and prebake – are characterised by the types of anode employed. Extremely dangerous in an aluminum smelter facility, changing anodes.Īnodes are large carbon blocks which are used to conduct electricity during the aluminium reduction process.Īs they do so they are consumed, at a rate of around 450 kg per tonne of aluminium produced.
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