![]() ![]() Indeed, according to Recycling World: “This property of infinite recyclability has led to a situation where today around 75 % of the almost one billion tonnes of aluminium ever produced is still in productive use.” A bright shiny future?Īluminium can be infinitely recycled with limited materials loss. When Portland cement is hydrated with water to make concrete it produces very alkaline calcium hydroxide, which can cause the aluminium to crack,” Van der Eijk notes. “So it’s not suitable when combined with wet concrete. This, however, doesn’t make aluminium invincible.Ĭontact with salt water can result in small holes, known as pits, and it will corrode if exposed to alkaline environments, but is more resilient to acid, able to withstand soft drinks with a pH less than three. “Aluminium reacts very quickly to oxygen, creating a thin layer of aluminium oxide on its outer surface, which stops more oxygen from reaching the metal, so protecting it,” explains Van der Eijk. Think of the thin green layer that forms on the domes of buildings made from copper, brass or bronze. While other metals corrode when exposed to oxygen or water, they don’t actually rust. As steel is an alloy, with iron its principal ingredient, it also rusts. When iron is exposed to moisture and oxygen, it becomes caked in the brown-red brittle substance we call rust. It turns out that this is a misconception. It has been routinely used in packaging (in cans and for aluminium foil), consumer goods (such as phones and PCs), transportation (cars, planes, ships and trains) and power lines, being cheaper than copper and with a better conductivity to weight ratio. “It is also soft and malleable, so can easily be cast or formed into many different products,” adds Van der Eijk. It is lightweight – about a third the weight of steel. It wasn’t until towards the end of the 19th century that aluminium was produced at an industrial scale, and its properties proved invaluable. Then, the aluminium and oxygen are separated by an electric current passed through a molten solution of alumina and the mineral cryolite, which dissolves the oxide minerals.” After mining the bauxite ore, aluminium oxide is extracted. As Van der Eijk explains, “It takes about four kilos of bauxite to produce one kilo of aluminium metal. Our main source of aluminium is the sedimentary rock, bauxite. This is partly explained because pure aluminium doesn’t exist in nature as it binds easily with other elements like oxygen. Despite being the most abundant metal on Earth, constituting over 8 % of the Earth’s crust, aluminium was only discovered in the 1820s, by Danish physicist Hans Christian Ørsted. ![]()
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