extraction of metals
EXTRACTION OF METALS SUMMARY
Most metals exist in compounds in rocks in the Earth’s crust. Many of these ores contain oxides or sulphides of the metals. The compounds need to be reduced to produce the metals as elements. Metals are very useful to us because of their special properties.
Reduction means removal of oxygen or gain of electrons. Carbon is a good chemical reducing agent because it readily combines with oxygen, but it is only useful for the metals below it in the Reactivity Series. In the process of electrolysis, the positive metal ions in the compound gain electrons to become atoms of the elements.
METAL
METHOD OF EXTRACTION
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
K
Na
Li
Ca
Mg
Al
These metals are too reactive for ordinary chemical reducing agents like carbon to be used. They are obtained by electrolysing their molten compounds.
For aluminium, aluminium oxide (from the ore Bauxite) is used
For Group 1 and 2 metals, the metal chlorides are usually used.
Electrolysis is a very expensive process because of the cost of electrical energy.
Carbon
Zinc
Iron
Lead
Zn
Fe
Pb
Reduction of the metal oxides in a blast furnace. Carbon is used as the reducing agent. It is often in the form of coke (made from coal). Although this uses a lot of energy, this is cheaper than using electricity.
Hydrogen
Copper
Silver
Gold
Cu
Ag
Au
These metals occur “native” (as uncombined elements) in the Earth’s crust.
Copper also exists as compounds in ores. These can be reduced using carbon in a blast furnace.
Most metals exist in compounds in rocks in the Earth’s crust. Many of these ores contain oxides or sulphides of the metals. The compounds need to be reduced to produce the metals as elements. Metals are very useful to us because of their special properties.
Reduction means removal of oxygen or gain of electrons. Carbon is a good chemical reducing agent because it readily combines with oxygen, but it is only useful for the metals below it in the Reactivity Series. In the process of electrolysis, the positive metal ions in the compound gain electrons to become atoms of the elements.
METAL
METHOD OF EXTRACTION
Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
K
Na
Li
Ca
Mg
Al
These metals are too reactive for ordinary chemical reducing agents like carbon to be used. They are obtained by electrolysing their molten compounds.
For aluminium, aluminium oxide (from the ore Bauxite) is used
For Group 1 and 2 metals, the metal chlorides are usually used.
Electrolysis is a very expensive process because of the cost of electrical energy.
Carbon
Zinc
Iron
Lead
Zn
Fe
Pb
Reduction of the metal oxides in a blast furnace. Carbon is used as the reducing agent. It is often in the form of coke (made from coal). Although this uses a lot of energy, this is cheaper than using electricity.
Hydrogen
Copper
Silver
Gold
Cu
Ag
Au
These metals occur “native” (as uncombined elements) in the Earth’s crust.
Copper also exists as compounds in ores. These can be reduced using carbon in a blast furnace.