BALCO has its operations at Korba in the state of Chhattisgarh with a smelter capacity of 345 ktpa with capabilities to produce ingots, wire-rods, billets, busbars and rolled products. The Company is also setting up a new project with smelting capacity of 550 ktpa.
The Hall-Heroult process is the method by which Aluminium is produced industrially. The steps involved in the process are-
- The process involves electrolytic reduction of Alumina (Al2O3) dissolved in electrolyte (bath) mainly containing Cryolite (Na3AlF6).
- The mixture electrolysed causing the Oxygen ion of the dissolved Alumina to discharge on positive electrode where it reacts with Carbon anode to form gases like CO2 and CO.
- The Al3+ ion deposited at the negatively charged cathode converts into liquid metal which sinks to the top of cathode from where it is periodically collected and sent to casthouse or fabrication for further processing.
- Electrical resistance within the bath provides sufficient heat to keep the Cryolite molten.
- The pot is thermally insulated from side and bottom to maintain the optimum heat balance and sufficient ledge (frozen electrolyte) on the side of the shell.
- A crust of bath and Alumina covers the anode to avoid anode oxidation.
Carbon Plant – Prebaked Technology
In prebaked technology the anodes used are termed as prebaked anodes which are made from a mixture of petroleum coke aggregate, coal tar pitch binder, butts and green scraps moulded into blocks and baked in separate anode baking furnace at about 1100±20 °C. An Aluminium rod with iron studs is then cast into grooves on the top of the anode block as a support to the anode and which when positioned in the pot conducts the electric current to the anode.
Prebaked anodes have to be removed at regular intervals, when they have reacted down to one third or one fourth of their original size. These remaining anodes are termed as butts and are usually cleaned at rodding shop. The cleaned butts are then crushed and used as a raw material in the manufacture of new anodes.
The technology employs -
Salient Features of Balco Plant II potline-
- BALCO, Plant II potline works on Prebaked technology
- A total of 288 electrolytic cells are installed with potline current of 320 kA
- All 288 pots are connected in a series circuit
- The name plate capacity of potline is 245 ktpa