Question

Which of the following slags is produced during extraction of iron?

• A. $CaSi{O}_3$
• B. $FeSi{O}_3$
• C. $MgSi{O}_3$
• D. $ZnSi{O}_3$

Answer 1

The correct option is A $CaSi{O}_3$

Limestone is also decomposed to $CaO$ which removes silicate impurity of the ore as slag. The slag is in a molten state and separates out from iron. Here, limestone acts as a flux.
Heat furnace decomposes the limestone to give calcium oxide.
$CaC{O}_3\to CaO+C{O}_2$
This is an endothermic reaction, absorbing heat from the furnace.It is therefore important not to add too much limestone because it would otherwise cool the furnace. Calcium oxide is a basic oxide and reacts with acidic oxides such as silicon dioxide present in the rock. Calcium oxide reacts with silicon dioxide to give calcium silicate.
$CaO+Si{O}_2\to CaSi{O}_3$
The calcium silicate melts and runs down through the furnace to form a layer on top of the molten iron.