- Iron is extracted from its ore, that is hematite (Fe2O3) and magnetite (Fe3O4 ) through reduction by carbon in the form of carbon in a blast furnace.
- The mixture of iron ore, carbon, and limestone is entered into a blast furnace through the top of the furnace.
- Hot air is then put in through the lower part of the furnace
- Limestone (calcium carbonate) is disintegrated by hot air into calcium oxide and carbon dioxide gas.CaCO3 (s) → CaO (s) + CO2(g)
- Carbon also burns in hot air to produce carbon dioxide gasC (s) + O2 (g) → CO2 (g)
- Carbon dioxide that is produced reacts with excess carbon to produce carbon monoxide gas which is a type of reducing agent.
CO2 + C → 2CO
- Carbon and carbon monoxide then reduces the iron ore to melted iron which flows to the lower part of the furnace.
2Fe2O3(s) + 3C(s) → 4Fe(s) + 3CO2(g)
Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g)
Fe3O4 (s) + C(s) → 3Fe(s) + 2CO2(g)
Fe3O4 (s) + 4CO(g) → 3Fe(s) + 4CO2(g)
- In the blast furnace, calcium oxide that is produced from the disintegration of calcium carbonate, reacts with foreign matter such as sand (silicon dioxide) in the iron ore to form slag.CaO (s) + SiO2 (s) → CaSiO3 (s) (slag)
- The melted dross flows down to the bottom part of the furnace and floats on the layer of melted iron.
- The melted iron and dross then are taken out from the furnace separately.
- The melted iron is cooled in a mould to form cast iron, while the dross is used to make the foundation for roads and houses.