Question

In the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with:
(A) copper(I) sulphide
(B) sulphur dioxide
(C) iron(II) sulphide
(D) carbon monoxide

Answer 1

Hint: Recollect the concept of metallurgy and extraction of copper. Think about the steps involved in the extraction of copper. In the question, copper is extracted from sulphide ore, that is, copper glance. Write the final reaction in which copper metal is obtained and then identify the reactants to get the answer.

Complete step by step solution:
- Copper exists in the form of ores in nature. Some of the ores from which copper is extracted is copper glance, copper pyrites, cuprites, malachite and azurite. Copper ores are generally oxides or sulphides.
- In the extraction of copper (I) sulphide, there are mainly five steps involved. But depending on the type of ore used, steps may be reduced to four.
- According to the question copper is extracted from its sulphide ore so copper is extracted from copper glance which is copper (I) sulphide ore.
- First, the powdered ore is concentrated by the froth floatation process. Then, the concentrated ore is roasted in a limited supply of air in a reverberatory furnace. In this step, the impurities present in ores that is, arsenic and antimony get converted to volatile oxides and are removed.
- Then the process of smelting is carried in which the ore is mixed with sand and coke and then heated strongly in a blast furnace. If there is any iron present in the ore then it gets converted to iron oxide which then combines with silica and is removed as slag. The molten material obtained from blast furnaces consists of sulphides of copper along with sand and coke which is collectively known as matte.
- Next, in the process of bessemerization, the molten matte is added to a Bessemer converter and blast of air is blown which converts copper sulphide, $C{{u}_{2}}S$ to copper oxide, $C{{u}_{2}}O$ which then reacts with more copper sulphide to form copper metal in a process called auto-reduction.
\[\begin{align}
  & 2C{{u}_{2}}S+3{{O}_{2}}\to 2C{{u}_{2}}O+2S{{O}_{2}} \\
 & 2C{{u}_{2}}O+C{{u}_{2}}S\to 6Cu+S{{O}_{2}} \\
\end{align}\]
- After the reduction is complete, the metal is poured into sand moulds. As the metal solidifies, sulphur dioxide escapes leaving blisters on the metal surface and the solid metal thus obtained is called blister copper and is about 99% pure. Then blister copper is electrolytically refined to get 99.95% to 99.99% pure copper metal.
- Therefore, in the extraction of copper from its sulphide ore, the metal is finally obtained by the reduction of cuprous oxide with copper(I) sulphide.

- Therefore, the correct answer is option (A).

Note: Remember, in the extraction of copper, there are five steps involved namely, concentration, froth floatation, smelting, bessemerization and refining. Bessemerization is the process in which copper sulfide is converted to copper oxide which then reacts with copper sulphide again and gets reduced in the process called auto-reduction to form copper metal.