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
|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|