When manufacturing aluminum, you must first create alumina. Alumina comes from bauxite ore, and it takes a special process called smelting to turn alumina into aluminum metal. Materials like graphite blocks, anodes, cathodes, and electrolytes make it possible to free aluminum from alumina. Here is more about smelting and how it works.
Location is Important
Most aluminum smelting facilities are near power plants because they need a great deal of electricity. Because most raw materials come in from specific regions of the world, smelting plants are often in cities close to the ocean to make it easier to transport goods. This helps to lower production costs.
Electrolysis
An electrolysis method creates chemical reactions by passing current through an electrolytic solution via cathode and anode connections. A typical smelting process uses electrolysis cells made from brick with an inner layer of carbon or graphite blocks (cathode blocks). The top lining forms the cathode when molten electrolyte enters the cell. Suspended in the electrolyte, (dissolved alumina) carbon blocks form the anode connection.
The Smelting Process
By dissolving alumina in cryolite, it creates an electrolyte. This takes a temperature of at least one thousand degrees Celsius. The electrolyte is then poured into vats lined with graphite blocks. The vat is the cathode. Anodes (made from carbon) go into the electrolyte, and a large amount of electricity enters the vat and passes to the anode.
The cathode connection turns aluminum ions into aluminum metal. The anode produces CO2 because it oxidizes the carbon in the anode. Since molten aluminum is heavier than the electrolyte, it falls to the bottom of the vat and leaves through a drain hole.
This is basically how aluminum smelting takes place and gives you a general idea of how the process works and why graphite blocks play a major role in smelting.
