Extraction of metals from their respective ores. In this method we can get metal oxides again we adding some reducing agent and heated up. It will give pure metals.
Smelting:
Smelting is a process of reduction of metal oxide to metal by carbon, carbon monoxide, or aluminum. In this metal oxide is heated above the melting point of the metal.
Example:
Oxide of ion can be reduced by carbon monoxide.
Fe2O3 + 3CO ———> 2Fe + 3CO2
Limestone ( CaO ) is a basic flux. Silica gangue present in the ore in its acidic nature. The limestone combines with silica gangue to form calcium silicate( slag ).
CaO + SiO2 ———> CaSiO3
(Flux) ( Gangue) (Slag)
The concentrated ore ( copper pyrite ) heated in a reverberatory furnace. It will form metal sulphides FeS and Cu2S. Both are soluble and form a copper matte.
2CuFeS2 + O2 ———> 2FeS + 2Cu2S + 2SO2
FeS oxidized to FeO.
FeS + O ———> FeO + SO2
Now the ferrous oxide ( flux ) reacted with the silica ( gangue ) to form ferrous silicate ( slag ).
FeO + SiO2 ———> FeSiO3
(Flux) ( Gangue) (Slag)
The remaining copper sulphide is further oxidised to its oxide to form the metallic copper.
Cu2S + 3O2 ———> 2Cu2S + 2SO2
2Cu2O + Cu2S ———> 6Cu + SO2
This metallic copper has blistered appearance due to the evolution of SO2 gas. This copper is called Blistered copper.
Reduction By Carbon:
In this method oxide ( ZnO ) ore is mixed with coal ( Coke ) and heated strongly in a furnace. This process only applied to the metal which do not form carbides with carbon.
Examples :
ZnO + C ———> Zn + CO
Mn3O4 + 4C ———> 3Mn + 4CO
Cr2O3 + 3C ———> 2Cr + 3CO
Reduction Of hydrogen;
This process only applied to the metal which have less electro -positive character than hydrogen.
Ag2O + H2 ———> 2Ag + H2O
Fe2O4 + 4H2 ———> 3Fe + 4H2O
Reduction By Metal:
B2O3 + 6Na ———> 2B + 3Na2O
Rb2O3 + 3Mg ———> 2Rb + 3MgO
TiO2 + 2Mg ———> Ti + 2MgO
In this process metal oxides reduced by metal.
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