BALCO has been closely associated with the Indian Aluminium Industry since its inception, playing a pivotal role in making Aluminium a leading metal with myriad uses. Alumina is also used in abrasive, ceramics and refractory industries. BALCO is a partially integrated operation with its own Captive Bauxite Mines, Refinery and Smelters, producing primary Aluminum and also has 810 MW captive power plants.
Aluminium is the most abundant metallic element (8.1 mass %) in the earth’s crust. Due to its strong affinity to Oxygen, Aluminium does not occur in nature in its pure elemental state and is found in combined forms such as oxides and silicates. In order to produce the pure metal a Reduction reaction must take place.
Most smelting processes involve direct reduction of the ore by Carbon to metal and Carbon dioxide. The process of extracting a metal from its oxide is in general referred to as smelting. Some of the subsequent steps involved have been outlined below -
- 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.
For detailed information on Aluminium Production Technology, click here.