Smelting Alumina to Aluminum
Aluminum smelting is the process of extracting aluminum from alumina. Aluminum is usually extracted through the Hall–Héroult process, which is an electrolytic process that takes alumina and dissolves the material in an electrolyte consisting mainly of aluminum fluoride and molten cryolite. The alumina in this process is first extracted from bauxite through the Bayer process.
Smelting Alumina Steps
The alumina is dissolved in a molten cryolite bath that acts as an electrolyte, in which a powerful electric current wrests aluminum from the oxygen. Molten metal settles to the bottom of the pot.
Carried by crucible to a furnace, aluminum is alloyed with small accounts of other metals. Copper adds strength, magnesium imparts additional marine-corrosion resistance.
Molten aluminum is cast into various shapes, from 20-ton rolling ingots for sheet metal to four-pound alloy ingots for further casting.
Nearly indestructible, aluminum can be re-melted over and over. Depending on energy used to collect and transport cans and scrap, recycling saves up to 95 percent of the energy used to make aluminum from bauxite.