As the world's most widely used non-ferrous metal, it's remarkable how little the average person knows about aluminium. Important in so many areas including transportation, construction, packaging and everyday household items, being taught how and why it's so vital is something we feel could hugely benefit the engineers and metallurgists of the future. If you were lucky enough to get a basic understanding of Aluminium production at school, then great, but if not here's the process broken down into its 3 key steps:
A series of flash tanks are then used to heat and subsequently cool the liquor, with the remaining caustic soda, reserved from earlier in the process, then recycled and added to the digestion process. The hydrated alumina is roasted at a heat of up to 1100°C, driving off free moisture and chemically-connected instances of water. This produces alumina solids, which is shipped to smelters.
An electric current of up to 600 Ka is passed through the bath. Ka, short for kiloampere, is a measure of flow rate of electric charge. For comparison's sake, a starter motor requires 80-160 A to power it, so the high significant amount of energy needed here is generated in power stations. Large carbon blocks are used to conduct electricity in the cell, reacting with the oxygen in aluminium oxide to produce liquid aluminium. Carbon is also used to form the negative electrode in this process by using it as lining for the pot, causing the liquid aluminium to be deposited at the bottom of the cell, where it can be 'tapped' when needed so it may be casted into solid, metal products.
Ingot casting - The liquid aluminium is poured into moulds, which are then cooled, allowing the aluminium to solidify before being shipped out in its new, desirable shape. Casts can also be made with other metals, or sand, resin, plaster, graphite and even wax.
Rolling - Slabs of casted aluminium are heated to approximately 525°C, and are worked through a series of 'rollers' until they reach either their desired level of plate thickness, or they are thin enough (normally 3mm) for something called 'cold rolling'.
Extrusion - The cast aluminium is heated in billets and forced through a steel die. The aluminium is cooled as it is extruded, before it is cut to size in the processes we've more than covered before.