This article is about how Iron is extracted from its ore and all the relevant processes are explained in detail.

The blast furnace

This diagram shows the blast furnace used for extracting iron from its ore. It is an oven shaped like a chimney, at least 30 meters tall.

diagram showing the blast furnace for extraction of iron


A mixture called the charge, containing the iron ore, is added through the top of the furnace. Hot air is blasted in through the bottom. After a series of reactions, liquid iron collects at the bottom of the furnace.


What’s in the charge?

The charge contains three things:

1 Iron ore. The chief ore of iron is called hematite. It is mainly iron(III) oxide, Fe2O3, mixed with sand and some other compounds. 

2 Limestone. This common rock is mainly calcium carbonate, CaCO3.

3 Coke. This is made from coal, and is almost pure carbon.


Reactions, products, and waste gases

Stage 1: The coke burns, giving off heat

The blast of hot air starts the coke burning. It reacts with the oxygen in the air, giving carbon dioxide: 

carbon + oxygen → carbon dioxide

   C (s)      +       O2 (g) →  CO2 (g)

Stage 2: Carbon monoxide is made

The carbon dioxide reacts with more coke, like this:

carbon + carbon dioxide carbon monoxide 

   C (s)    +         CO2 (g)  → 2CO (g)

Stage 3: The iron(III) oxide is reduced 

This is where the actual extraction occurs. Carbon monoxide reacts with the iron ore, giving liquid iron: 

iron(III) oxide +  carbon monoxide → iron + carbon dioxide 

Fe2O3 (s)         +         3CO (g)  →    2Fe (l)    +    3CO2 (g) 

The iron trickles to the bottom of the furnace.

What is the limestone for?

The limestone breaks down in the heat of the furnace: 

CaCO3  → CaO (s) + CO2 (g) 

The calcium oxide that forms reacts with the sand, which is mainly silicon dioxide or silica: 

calcium oxide + silica → calcium silicate 

CaO (s) + SiO2 (s)  →  CaSiO3 (s) 

The calcium silicate forms a slag which runs down the furnace and floats on the iron.


The waste gases: hot carbon dioxide and nitrogen come out from the top of the furnace. The heat is transferred from them to heat the incoming blast of air.

Where next? 

The iron from the blast furnace is called pig iron. It is impure. Carbon and sand are the main impurities. Some are run into moulds to make cast iron. This is hard but brittle, because of its high carbon content – so it is used only for things like canisters for bottled gas and drain covers. But most of the iron is turned into steel.