Reactions in the furnace
Four reactions take place inside the blast furnace during the extraction of iron. Let us take them in order.
1 — the coke burns
Coke burns in air and forms carbon dioxide.
C + O2 → CO2
2 — making the reducing agent
Carbon dioxide (CO2) reacts with coke and forms carbon monoxide gas (CO).
CO2 + C → 2CO
3 — the reduction
Carbon monoxide (CO) reduces the haematite (Fe2O3). Here molten iron is formed.
Fe2O3 + 3CO → 2Fe + 3CO2
4 — the limestone decomposes
Calcium carbonate (CaCO3) decomposes to form calcium oxide (CaO) and carbon dioxide (CO2).
CaCO3 → CaO + CO2
What each one is for
1 and 2 together make CO, the reducing agent. 3 is the reaction that yields the iron. The CaO from 4 removes the impurities on the next page.
CO<sub>2</sub> appears twice
CO2 is a product of reactions 1 and 4 and a reactant in reaction 2. So inside the furnace it is continually being formed and consumed.