Extraction of Aluminium (Aluminum)
Please note that this article uses the British English spelling of aluminium, but this is exactly the same as aluminum - this is simply the North American English spelling.
Aluminium has a very high melting point and strong bonding between atoms, so it doesn't readily dissolve in water. Instead, molten cryolite (Na3AIF6) is used.
The pure aluminium is attracted to the cathode, which is a lining of graphite. The oxygen is attracted to the anode, and bubbles through the solution.
At the cathode, reduction takes place as electrons are gained:
Al3+ + 3e- ® Al
At the anode, oxidation takes place as electrons are lost:
2O2- ® O2 + 4e-
At the anode also, the oxygen formed will react with the anode (which is made of carbon) to form carbon dioxide. This means, the anodes must be frequently replaced.
This process uses ALOT of electricity and is expensive. Therefore, aluminium is much more expensive than other metals that are easier to extract (like iron). But its desirable characteristics mean that it is still widely used.
Aluminium is the most widely used metal after iron, it is mostly used in an alloy with another metal, this means it is mixed with another metal to produce another compound that has a certain desirable characteristic - like stainless steel.
Some uses of aluminium are in making cars, trains, and bicycles because it is reasonably strong but not too heavy so your aluminium bicycle won't break and won't be too difficult to ride. Some packaging like foil and cans is also made from aluminium - this is especially important in recying since many drinks cans are made from steel - but this can be sorted using magnets. And cooking utensils because it is very good at conducting heat so will evenly warm the food.