Aluminium is produced by using anodes and cathodes in the aluminium smelter. It is produced electrolytically using the Hall-Heroult process. Alumina (Al2O3) powder is dissolved in a molten bath of sodium aluminum fluoride known as cryolite. The temperature of operation in modern cells is ~950-960˚C. Electrical current is passed between carbon anodes and a carbon cathode in the cell, reducing alumina to aluminum metal that deposits on the cathode surface. Carbon anodes are consumed in this process, generating CO2 gas.

The general chemical reaction： 

   2 Al2O3 (dissolved) + 3 C (s)  =  4 Al (liquid) + 3 CO2 (gas)

Cathode reaction:

  4 Al³⁺ (bath) + 12 e^-   =  4 Al (liquid)

  or AlF4 ^-(bath) + 3 e^-  =   Al (liquid) + 4F^-

Anode reaction:

  3 C (solid anode) + 6 O^2-  =   3 CO2 (gas) + 12 e^-

Alumina (Al2O3), aluminium fluoride (AlF3) and baked anodes are the key inputs to the smelting process; other strategic input materials include pot lining materials (cathode carbon), refractory items and steel. The steel is reused and recycled rather than consumed in the process. The cathode carbon and refractory materials are also recycled to a given degree at the end of their life.