Question

In the metallurgy of iron, limestone is added along with haematite ore and coke. What is main use of limestone?

• A. Limestone decomposes to $CaO$ and $C{O}_2$ which reacts with coke to produce CO which is used to reduce haematite directly to iron
• B. Limestone on decomposition produce $CaO$ which is used to react with $F{e}_2{O}_3$ to form slag of $CaFe{O}_4$
• C. Limestone on decomposition produce $CaO$ which is used to react with $F{e}_2{O}_3$ to form slag of $CaFe{O}_3$
• D. Limestone on decomposition produce $CaO$ which is used to react with $Si{O}_2$ to form slag of $CaSi{O}_3$

Answer 1

The correct option is D Limestone on decomposition produce $CaO$ which is used to react with $Si{O}_2$ to form slag of $CaSi{O}_3$

(a) Haemetite is never converted directly into iron.
(b) $CaO$ reacts with acidic impurity of $Si{O}_2$, and the formation of slag can be given as:
$CaO+Si{O}_2\to CaSi{O}_3$
So, option (d) is correct.