Question

The slag formed in the extraction of iron and copper respectively are

• A. $CaSi{O}_3\text{and}Si{O}_3$
• B. $FeSi{O}_3\text{and}CaSi{O}_3$
• C. $MgSi{O}_3\text{and}FeSi{O}_3$
• D. $CaSi{O}_3\text{and}FeSi{O}_3$

Answer 1

The correct option is D $CaSi{O}_3\text{and}FeSi{O}_3$

In extraction of iron, limestone is also decomposed to CaO which removes the silicate impurity of the ore as slag. Heat furnace decomposes the limestone to give calcium oxide.
$CaC{O}_3\to CaO+C{O}_2$
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.
$Si{O}_2+CaO\to CaSi{O}_3$

In extraction of copper, concentrated sulphide ore containing iron as an impurity is mixed with silica and heated in a reverberatory furnace. During this process, most of the iron sulphide is converted into its oxide, which further reacts with silica to form a fusible slag of iron silicate.

$Si{O}_2+FeO\to FeSi{O}_3$