Question
Write down the reactions taking place in different Zones in the blast furnance during the extraction of Iron.
Solution
In the blast furnace, reduction of iron oxides takes place in different temperature ranges. Coke is burnt to get the required temperature upto about 2200K. The temperature is lower in the upper part. Hence, the reduction of iron oxides take place at lower portion.
The higher temperature range, depend on the points of corresponding intersections in the ΔrG0 vs T plots. (Given in ncert book)
These reactions are as follows:
At 500 – 800 K (lower temperature range in the blast furnace)–
3Fe2O3 + CO → 2Fe3O4 + CO2
Fe3O4 + 4CO → 3Fe + 4 CO2
Fe2O3 + CO → 2FeO + CO2
At 900 – 1500 K (higher temperature range in the blast furnace):
C + CO2 → 2CO
FeO + CO → Fe + CO2
The silicate impurity of the ore is removed as slag by calcium oxide (CaO), which is formed by the decomposition of limestone (CaCO3).
CaCO3 → CaO +CO2
CaO +SiO2 → CaSiO3
flux impurtiy (slag)
