Aluminum Electrolytic Process

Alumina is a compound of aluminum and oxygen. To obtain metal from the alumina, these elements must be separated by electricity in the smelting process. This reaction takes place in large, carbon-lined steel cells, or pots, through which a direct electrical current is passed.

The bottom of each pot acts as a cathode, or negative electrode. Carbon blocks are suspended in the pot to serve as an anode, or positive electrode. Inside the pot, alumina is dissolved in a molten electrolyte, composed mainly of the mineral cryolite. The electrical current passing from the anode to the cathode causes the oxygen in the mixture to react with the carbon anode to form carbon dioxide, while the aluminum settles to the bottom of the pot to be siphoned off to Casting and Fabricating.