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please explain the extraction of iron from its ore?
Iron is extracted from its oxide ore called haematite .(Fe2O3 ) .This is based on the reduction of haematite with carbon .This process involves the following steps ,
      i) Concentration of ore
      ii) Calcination or roasting of ore
      iii) Reduction of ore
i) Concentration of ore  : In this process the ore is concentrated by removing impurities like soil etc .It involves crushing and washing of ore .
ii) Calcination /Roasting  : The concentrated ore is now heated in presence of air . This helps to remove moisture,CO2 ,impurities of sulphur ,arsenic .Ferrous oxide is also oxidised to ferric oxide .
iii)Reduction of ore : The process of reduction carried out in blast furnace .Roasted ore,core ,limestone which is collectively called the charge which is fed into the furnace from its top- .A preheated blast of air at 1500o c is blown into the furnace under pressure near to the bottom .The blast oxidises C to CO2 .
C +O2 ________> CO2 +heat 
Formation of CO2 is an exothermic reaction in which a huge amount of heat is liberated which rises the temperature to 1900oc  in this region .As the CO2 passes upwards ,it reacts more coke to form CO .
CO2 +C ________> 2CO+ heat
   Formation of CO is an endothermic reaction and the temperature in this region falls to 1100 0c .CO is the mask reducing agent in the upper portion of the blast furnace .
 Reactions in blast furnace .
Fe2O3 +3C    ________ >2Fe + 3CO
Fe3O4 +4CO _______> 3Fe +4CO2
CO2 +C         ______>    2CO

Overall reaction
The liquid iron runs down wards to the bottom of the furnace and is withdrawn through the tap hole .
 Slag formation
Limestone on heating decomposes to CaO and CO2
CaCO3 _________ CaO + CO2
Calcium oxide now reacts with impurities of ore called gangue to form slag .Slag is the mixture of calcium silicate and Ca(AlO2 )2 .The slag floats over the top of the molten iron. Slag is a useful bi product .It is used in road making ,manufacture of cement  etc .
flux   + gangue _________slag
CaO + SiO2 _________ CaSiO3
CaO + Al2O3  ________   Ca(AlO2)2


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