Many rocks and minerals contain aluminium. The concentration of the metal is usually so low, that industrial mining is not worthwhile. The only exception is bauxite, an inconspicuous ore which has a sufficient aluminium content to be suitable for industrial extraction of aluminium.
Aluminium is one of the metals that has been used by humans only for a very short time. Compared to iron and copper, which have been used for several millennia, aluminium has only been known for about 200 years.
There are several reasons for this fact. Solid aluminium only forms extremely small crystals and is a very reactive metal. That is why it is almost never found in its pure form. The metal, bound in bauxite ore, looks inconspicuous and has no metallic shine. Aluminium is not visible to the naked eye.
Australia is the largest bauxite mining country in the world. However, the ore is found practically all over the world, but in very different concentrations.
The production of aluminium
Metal-containing ores are normally crushed and melted after extraction. By melting and the different melting points, the individual metals can be separated from each other. With bauxite this does not work so easily. Bauxite is an ore which contains iron, titanium and gallium compounds in addition to aluminium silicates.
The chemical bonds cannot be separated from each other by simple melting. Because the aluminium cannot be melted out, the unwanted substances are separated out chemically with caustic soda. The silicate is then burnt, forming aluminium oxide. In the next step, the aluminium and oxygen are separated from each other by electrolysis. An enormous amount of energy is required for this process.
Due to this high energy input, the production of new aluminium is not environmentally friendly. However, if the entire material cycle is taken into account, the energy-intensive extraction of aluminium is compensated for by the worthwhile recycling of the scrap metal. The recycling of aluminium only requires about 5% of the energy needed for new production. Aluminium can be recycled very well and doesn't loose it's typical properties.
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