The Extraction of Copper from its Sulphide Ore

The extraction of copper from its sulphide ore involves several steps, which are carried out in a series of chemical reactions. The final step in this process is the reduction of cuprous oxide (Cu2O) to obtain the pure copper metal.

Step 1: Concentration of the Ore
The sulphide ore is first crushed and then concentrated by froth floatation process. In this process, the ore particles float on the surface of a liquid bath, while the gangue particles sink to the bottom. The froth is skimmed off, and the concentrated ore is obtained.

Step 2: Roasting
The concentrated ore is then roasted in the presence of excess oxygen at a high temperature. This converts the sulphide ore into copper(I) oxide (Cu2O) and sulphur dioxide (SO2) gas.

Step 3: Conversion to Copper(I) Sulphide
The copper(I) oxide obtained from the roasting step is mixed with the remaining sulphide ore and heated in a furnace. The copper(I) oxide reacts with the remaining sulphide ore to form copper(I) sulphide (Cu2S) and further sulphur dioxide gas.

Step 4: Smelting
The copper(I) sulphide obtained from the previous step is then mixed with silica (SiO2) and heated in a furnace. This process is known as smelting. During smelting, the copper(I) sulphide reacts with silica to form slag, which is a mixture of impurities and waste materials, and copper(I) silicate.

Step 5: Conversion to Copper Metal
The copper(I) silicate obtained from the smelting step is then reduced to obtain the pure copper metal. This is done by mixing the copper(I) silicate with coke (a form of carbon) and heating it in a furnace. The carbon in the coke acts as a reducing agent, which removes the oxygen from the copper(I) silicate, leaving behind pure copper metal.

Answer: Reduction with Copper (I) Sulphide (Cu2S)
In the final step, the cuprous oxide (Cu2O) is reduced to obtain the pure copper metal. The reduction is carried out by mixing cuprous oxide with copper(I) sulphide (Cu2S) and heating it in a furnace. The copper(I) sulphide acts as a reducing agent, removing the oxygen from the cuprous oxide and converting it into pure copper metal.

Therefore, the correct answer is option 'A' - Copper (I) sulphide (Cu2S).