Types of Extraction
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Types of Extraction
Many metals are found in the Earth's crust as ores. An ore is usually a compound of the metal mixed with impurities. When the metal is dug up, a method must be used to separate the metal from the rest of the ore. This is called extracting the metal.
The method of extraction depends on how reactive the metal is. The more reactive the metal, the more difficult it is to extract from its compound.
Electrolysis is the most powerful extraction method. But it takes a lot of electricity and that makes it expensive. Hence, electrolysis is only used for the most reactive metals.
|Metal:||Method of extraction:|
|Zinc||Heat with carbon or carbon monoxide|
|Iron||Heat with carbon or carbon monoxide|
|Lead||Heat with carbon or carbon monoxide|
|Copper||Roasting in air|
Electrolysis: Used in extracting aluminium and extracting sodium from rock salt.
In the case of the rock salt, it is first melted in giant steel tanks:
The extraction of aluminium is dealt with in a separate learn its within this topic.
Heating with Carbon monoxide: Used for extracting iron from iron ore using the blast furnace.
Roasting in Air: Used in extractingcopper from copper (I) sulphide (copper pyrites).
The copper is extracted by roasting the ore in air.
Metals are non-renewable resources. This means once dug up it cannot be replaced. Hence, the supply will eventually run out.
For example: it is expected that tin will run out within the next 15 years and copper in the next 40 years! Therefore,the recycling of these two useful metals and others such as iron and aluminium is most important.
In recycling, metals are melted down before reshaping into their new use. However, this can be costly. Recycling companies will only recycle if it is economical!