Question

In iron metallurgy, lime stone is used :

• A. to obtain heat energy
• B. to reduce iron oxide into iron
• C. as an iron ore
• D. to remove sand ($Si{O}_2$)

Answer 1

The correct option is D to remove sand ($Si{O}_2$)

In the extraction of iron, the roasted ore is mixed with coke and limestone (flux) and is then heated in the presence of air at high temperature in a furnace. Impurity of $Si{O}_2$ is removed as calcium silicate $\left(CaSi{O}_3\right[slag\left]\right)$.

$CaC{O}_3\to CaO+C{O}_2$

$CaO+Si{O}_2\to CaSi{O}_3$