Give the reactions taking place in the blast furnace, when haematite, coke and lime stone are added to it.

Question

(i) Give the reactions taking place in the blast furnace, when haematite, coke and lime stone are added to it. 

(ii) What is the purpose of adding lime stone in the extraction of iron from haematite? 

(iii) What is the use of galvanized iron ? 

(iv) Which two products are taken out from the blast furnace during the extraction of iron?

Answer 1

(a) Carbon burns in the presence of oxygen of air to form carbon dioxide which is reduced to carbon monoxide in the presence of coke. 

C + O₂ ⟶ CO₂ 

CO₂ + C ⟶ 2CO 

(b) Carbon monoxide so produced, reduces haematite ore [Ferric oxide] to metallic iron. 

Fe₂O₃ + 3CO » 2Fe + 3CO₂↑ 

(c) Lime stone, at a higher temperature of blast furnace; decomposes into calcium oxide and carbon dioxide. 

CaCO₃ ⟶ CaO + CO₂↑ 

(d) Calcium oxide so formed reacts with sand [silicon dioxide] to form calcium silicate, the slag and thus the impurity of sand is removed. 

CaO + SiO₂ ⟶ CaSiO₃ 

(ii) Lime stone is added to “blast furnace” in the extraction of iron to remove the impurities of silicon dioxide, i.e., the sand. 

(iii) Galvanized iron is used in making different varieties of tools for industries, scientific apparatus, and household fittings.

(iv) Pig iron and slag are the two products, which are taken out from the blast furnace during the extraction of iron.