Extraction of metals
Introduced| English | Meaning |
|---|---|
| ores/ɔːz/ | ores |
| extraction/ekˈstrækʃn/ | The process of getting the metal out — and the method depends on reactivity. |
| reduction/rɪˈdʌkʃn/ | A chemical change involving a gain of electrons or a decrease in oxidation state. |
| electrolysis/ɪlekˈtrɒləsɪs/ | The decomposition of an electrolyte by an electric current passing through its molten form or a solution. |
| blast furnace/blæst ˈfɜːnɪs/ | A furnace in which hot air is blown through a charge of materials, commonly to extract iron from its ores. |
Getting metals out of rocks
- Most metals are found combined with other elements in ores 矿石, not as pure metal.
- Extraction 提取 is the process of getting the metal out — and the method depends on reactivity.
A rock containing enough of a metal compound to extract is called an:
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Metals are extracted from their ores.
Reactivity decides the method
- Less reactive metals (below carbon) can be extracted by heating with carbon (reduction 还原).
- More reactive metals (above carbon) must be extracted by electrolysis 电解.
The reactivity series, and how a metal's position decides its extraction method
Extracting iron in the blast furnace
Iron is below carbon in reactivity, so carbon can reduce its ore to the metal.
Iron is extracted by heating its ore with:
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Iron is below carbon, so carbon reduces it.
Removing oxygen from a metal oxide using carbon is an example of ______.
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Reduction is loss of oxygen.
Extracting iron
- Iron is extracted in a blast furnace 高炉 by reduction with carbon.
- The carbon (from coke) removes the oxygen from iron oxide, leaving iron.
In the blast furnace, carbon monoxide reduces the iron ore and limestone removes sandy impurities as slag
Aluminium is extracted by electrolysis because it is:
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Metals above carbon need electrolysis.
The method used to extract a metal depends on its reactivity.
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Reactive metals need electrolysis; less reactive ones use carbon.
Extracting aluminium
- Aluminium is too reactive for carbon, so it is extracted by electrolysis of molten aluminium oxide.
- This uses a lot of electricity, making aluminium expensive to extract.
Reactivity decides the extraction method. Metals more reactive than carbon (like aluminium) need electrolysis; those less reactive (like iron) can be reduced by carbon. Very unreactive metals (gold) are found native.
Metals above carbon need electrolysis; those below are heated with carbon
You've got it
- metals are found in ores; extraction gets the pure metal out
- less reactive than carbon → reduced by carbon (e.g. iron in a blast furnace)
- more reactive than carbon → extracted by electrolysis (e.g. aluminium)