Q. When copper pyrites is roasted in excess of air, a mixture of $CuO + FeO$ is formed. $FeO$ is present as impurities. This can be removed as slag during reduction of CuO. The flux added to form slag is
A) ${SiO}_{2}$ which is an acid flux
B) Lime stone, which is a basic flux
C) ${SiO}_{2}$, which is a basic flux
D) $CaO$, which is a basic flux
Explanation
(a)
The compounds which combine with impurities present in ore (at high temperature) and remove them as a fusible substance (slag), are known as flux. When basic impurities are present, an acidic flux is used and vice-versa.
$FeO\ \ \ \ \ \ \ \ \ \ \ \ \ + \ \ \ \ \ \ \ \ \ \ {SiO}_{2}\ \ \rightarrow \ {FeSiO}_{3}$
basic impurity acidic flux slag
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.