Aluminiu

Aluminiu, also spelled aluminium in some varieties of English, is a chemical element with symbol Al and atomic number 13. It is a silvery-white, soft metal that is the third most abundant element in the Earth's crust and the most widely distributed metal. It is lightweight, with a density of about 2.70 g/cm3, and melts at 660.3°C. A key property is its natural oxide film, which forms rapidly in air and provides corrosion resistance while allowing good electrical and thermal conductivity relative to its weight.

Most commercial aluminum is extracted from the ore bauxite. The Bayer process produces alumina (Al2O3) from bauxite, and the Hall-Héroult electrolytic reduction converts alumina to metallic aluminum in a molten cryolite bath at around 950–980°C. The process is energy-intensive and heavily dependent on electricity. Aluminum is highly reactive but protected by the oxide layer, which gives it corrosion resistance and enables versatile engineering uses.

Applications and alloys are wide-ranging. Aluminum is used in pure form or as alloys, notably the 6000 series (Al–Mg–Si) and 7000 series (Al–Zn–Mg–Cu), which balance lightness with strength. Common applications include beverage cans, packaging, aircraft and automotive components, building facades, electrical conductors, and consumer electronics.

Recycling plays a major role in the aluminum supply chain. Recycled aluminum requires only a fraction of the energy of primary production and can be re-melted with minimal loss of properties. Environmental considerations include energy use in smelting and the ecological footprint of bauxite mining and refining residues such as red mud.