Aluminium & non-ferrous


Aluminium & non-ferrous

Non-ferrous metals, those without iron, are not magnetic, are more malleable and are more resistant to corrosion than ferrous metals. Aluminium is the most important of this group. It is the third most abundant element in the earth's crust and is found in over 270 different minerals.

Various compounds containing aluminium were used for making pottery, developing dyes and in medicine for several thousand years before the metal was isolated in pure form. During the first half of the nineteenth century scientists managed to produce only small amounts of aluminium, which was then regarded as a precious metal alongside gold and silver. The processes that made large scale aluminium production commercially viable were not developed until the 1880's. The first stage was to produce alumina, or aluminium oxide, from the mineral bauxite and the impetus for this was to assist with fixing dyes in textiles. Alumina has several uses in its own right but can be smelted into aluminium using the Hall-Héroult electrolytic process, named after the American and Frenchman who came up with the same idea at the same time.

Aluminium is lightweight, is a good conductor of electricity, does not give off sparks when struck and resists corrosion. These characteristics have made aluminium the second most widely used metal after steel. It replaced copper and cast iron in cookware, is used for the bodies of aircraft and cars, in construction and in electrical applications, as well as in beverage cans and other food packaging.

The other non-ferrous metals used in significant quantities in industry are copper, zinc, lead, nickel and tin. These are described as base metals. Copper is well known for its conducting properties and so around two thirds of all copper goes into electrical applications. A further quarter is used for pipes, as copper inhibits the growth of bacteria in water. Zinc is used for adding a non corrosive coating to steel and combined with copper it makes brass. It also appears in such products as sunscreen and deodorants. Lead is extremely soft, easy to work and was once widely used for pipework and in paints but has now been replaced. About 80% of lead is used in batteries. Other applications include protection against radiation, optics and roofing. The majority of nickel goes into stainless steel. It is also used in batteries and magnets. Tin is used for soldering and as tin plate for protecting steel and other metals susceptible to corrosion.

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