Making iron in the blast furnace

Blast furnace in a modern steel works

Iron is extracted from iron ore in a huge container called a blast furnace. Iron ores such as haematite contain iron oxide. The oxygen must be removed from the iron oxide to leave the iron behind. Reactions in which oxygen is removed are called reduction reactions.

Carbon is more reactive than iron, so it can push out or displace the iron from iron oxide. Here are the equations for the reaction:

iron oxide + carbon    →    iron + carbon dioxide

2Fe₂O₃ + 3C    →    4Fe + 3CO₂

In this reaction, the iron oxide is reduced to iron, and the carbon is oxidised to carbon dioxide.

In the blast furnace, it is so hot that carbon monoxide can be used to reduce the iron oxide in place of carbon:

iron oxide + carbon monoxide    →    iron + carbon dioxide

Fe₂O₃ + 3CO    →    2Fe + 3CO₂

Raw materials for the reaction

The raw materials for extracting iron and their function in the process

Raw material	Contains	Function
iron ore (haematite)	iron oxide	a compound that contains iron
coke	carbon	burns in air to produce heat, and reacts to form carbon monoxide (needed to reduce the iron oxide)
limestone	calcium carbonate	helps to remove acidic impurities from the iron by reacting with them to form molten slag
air	oxygen	allows the coke to burn, and so produces heat and carbon monoxide