Question

In the commercial extraction of iron, roasting is adopted because :

• A. it removes impurities of $S$, $As$, and $Sb$ in the form of their elemental vapor
• B. it prevents slag formation by $F{e}_2{O}_3$
• C. it prevents slag formation by $FeO$
• D. limonite is converted into its anhydrous form

Answer 1

Answer: (C), (D)

The correct options are
C it prevents slag formation by $FeO$
D limonite is converted into its anhydrous form

A) (a) During roasting S, As, and Sb will be oxidized into their volatile oxides $S{O}_2.A{s}_2{O}_3$ and $S{b}_2{O}_3$, respectively. It does not remove impurities of S, As, and Sb in the form of their elemental vapor.
B) Roasting: The process of conversion of the ore into its oxide by heating it below its melting point in the presence of oxygen. So It does not prevent slag formation by $F{e}_2{O}_3$.

C) During roasting, $FeO$ is oxidized into $F{e}_2{O}_3$ which does not form slag with silica.

D) $F{e}_2{O}_3.3H_{2}O\left(Lemonite\right)\stackrel{\Delta }{\to }F{e}_2{O}_3\left(Anhydrousform\right)+3H_{2}O\uparrow$.

Hence options C & D are correct.