- The Aluminium produced by the electrolytic reduction of alumina (Al2O3) dissolved in an electrolyte (bath) mainly containing cryolite (Na3AlF6) sinks to the bottom of the Cell from where it is collected and sent to a melting or holding furnace, that is used to hold the hot metal and maintain desired temperature for casting.
2 Al2O3 (dissolved) + 3C(s) ------> 4Al(l) +3CO2(g)
- The molten Aluminium is then mixed with desired alloys to obtain specific characteristic and cast into Ingots for transport to fabricating shops.
- In the Fabrication Shops, the molten Aluminium or Aluminium alloys are re-melted and poured into casts and cooled.
- Molten Aluminium may be further heated to remove oxides, impurities and other active metals such as Sodium and Magnesium, before casting.
- Chlorine may also be bubbled through the Aluminium to further remove impurities.