Aluminium

Aluminium (chemical symbol Al, atomic number 13) is a lightweight metal with a silvery-white colour. It is the most abundant metal element in the Earth's crust, and the third most abundant element overall after oxygen and silicon. It does not occur as a pure metal in nature, but exists in compounds with oxygen and other elements.

The main properties of aluminium are its low density compared to steel, excellent electrical and thermal conductivity, and resistance to corrosion. This corrosion resistance occurs because a thin layer of oxide forms rapidly on its surface, preventing air from reaching the underlying metal.

Physical and chemical properties

Aluminium is a ductile metal that can be easily shaped, making it suitable for producing lightweight foils and sheets. Its density is approximately one-third that of steel. It has a melting point much lower than that of steel, which facilitates casting. When other elements such as copper, magnesium, silicon, or zinc are added, the result is an alloy that is both strong and lightweight.

Sources and production

The main commercial source of aluminium is bauxite ore, which contains aluminium oxides. Production involves two major steps: first, bauxite is processed chemically to extract aluminium oxide; second, the oxide is separated into pure metal through electrolysis in molten salt, which allows the metal to be released. The second step requires large amounts of electricity, which is why aluminium smelters are typically located near abundant and inexpensive power sources.

Uses

Aluminium is used in aircraft, ships, and trains because of its low density. It is also made into drinking vessels, food containers, window frames and building materials, high-voltage electrical cables, and household tools. Its compounds, such as aluminium oxide, are used in water treatment and other industrial processes.

Recycling

Aluminium can be recycled completely without loss of quality. Melting recycled metal requires significantly less electricity than extracting it from bauxite, which is why recycling represents a major part of the global market.