Most metals are found in the Earth's crust as Minerals.
- Minerals are ionic compounds.
- If there is a sufficient amount of a mineral contained within a rock then it is known as an ore. Most metals are extracted from oxidic ores.
To obtain the pure metal the oxygen must be removed. There are two main ways to extract metals:
- Blast Furnace
The method depends on the position of the metal in the reactivity series. Metals above zinc are usually produced by electrolysis.
Electrolysis of Aluminium Oxide
- Aluminium is too high in the reactivity series to extract it from its ore using carbon reduction.
- Instead, it is extracted by electrolysis using carbon (graphite) electrodes.
- The ore is first converted into pure aluminium oxide.
- The aluminium oxide has too high a melting point (2000C) to electrolyse on its own, as it would melt the steel container where the electrolysis happens.
- The aluminium oxide is electrolysed in molten cryolite, which acts as a solvent and lowers the operating temperature (about 1000C).
- Aluminium is extracted from purified aluminium oxide by electrolysis.
That is all!