Question

The 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

Hint: Roasting is a process of heating of sulphide ore to a high temperature in presence of air. It is a step of the processing of certain ores. Partial roasting of sulphide ore is carried in order to convert it to the oxide form. The oxide form then reduces the remaining sulphide ore to the metallic form. This is called auto reduction.

Complete step by step answer:
Chalcopyrite is a brass-yellow mineral with a chemical composition of$CuFe{{S}_{2}}$. It occurs in most sulfide mineral deposits throughout the world and has been the most important ore of copper for thousands of years. The surface of chalcopyrite loses its metallic luster and brass-yellow color upon weathering. Chalcopyrite is often confused with pyrite and gold since all three of these minerals have a yellowish color and a metallic luster.

Partial roasting of Chalcopyrite follows given reaction:
\[2CuFe{{S}_{2}}+{{O}_{2}}\to C{{u}_{2}}S+2FeS+S{{O}_{2}}\uparrow \]
\[2C{{u}_{2}}S+3{{O}_{2}}\to 2C{{u}_{2}}O+2S{{O}_{2}}\uparrow \]
\[2FeS+3{{O}_{2}}\to 2FeO+2S{{O}_{2}}\uparrow \]

Thus, partial roasting of chalcopyrite produces $C{{u}_{2}}O$ and FeO.
More specifically, roasting is a metallurgical process involving gas–solid reactions at elevated temperatures with the goal of purifying the metal component(s).
So, the correct answer is “Option B”.

Note: Copper metal can be extracted from the open air roasting of a mixture of chalcopyrite and silica sand, as shown in the following reaction:
\[2CuFe{{S}_{2}}~\left( s \right)+5{{O}_{2}}~\left( g \right)+\text{ }2Si{{O}_{2}}~\left( s \right)\rightleftharpoons 2Cu\left( l \right)+4S{{O}_{2}}~\left( g \right)+2FeSi{{O}_{3}}~\left( l \right)\]

Often before roasting, the ore has already been partially purified, e.g. by froth flotation. The concentrate is mixed with other materials to facilitate the process. The technology is useful but is also a serious source of air pollution.