Question

Although there are several ores, 80% of the world copper production comes from the ore chalcopyrite ($CuFe{S}_2$). The extraction of copper from chalcopyrite involves partial roasting, removal of iron and self-reduction. Partial roasting of chalcopyrite produces:

• A. $C{u}_{2}S$ and $FeO$
• B. $C{u}_{2}O$ and $FeO$
• C. $CuS$ and $F{e}_2{O}_3$
• D. $C{u}_{2}O$ and $F{e}_2{O}_3$

Answer 1

The correct option is A $C{u}_{2}S$ and $FeO$

After the ore is crushed and ground into a fine powder, it is concentrated via froth-floatation.
Post dressing or concentration of the ore, it is subjected to partial roasting. Iron has a greater affinity for oxygen
as compared to copper.
During roasting:

$2CuFe{S}_2+O_2\to C{u}_{2}S+2FeS+S{O}_{2}2FeS+3O_2\to 2FeO+2S{O}_{2}2C{u}_{2}S+3O_2\to 2C{u}_{2}O+2S{O}_2$

But this is a minor side reaction since Fe has greater affinity for oxygen and hence the following happens:

$C{u}_{2}O+FeS\to C{u}_{2}S+FeO$

of $C{u}_{2}S$ and $FeS$, only $FeS$ is largely oxidized to $FeO$.