Question

Which of the following species is a desirable substance in the extraction of copper but not in the extraction of iron?
A.$CaSi{O_3}$
B.$FeSi{O_3}$
C.$Si{O_2}$
D.Coke

Answer 1

Hint: To answer this question, you should recall the concept of extraction of copper. The commonest ore used in the extraction of copper is chalcopyrite \[(CuFe{S_2})\] also known as Copper Pyrites and other such sulphides.

Complete step by step answer:
Copper exists in the form of sulphide in the ore. After concentration of the ore, it is heated strongly with silicon dioxide, calcium carbonate and air or oxygen in a furnace or series of furnaces. This results in the copper (II) ions in the chalcopyrite being reduced to copper(I) sulphide. The iron impurities in the ore get converted into an iron (II) silicate slag which is removed. The other Sulphur impurities are converted into Sulphur dioxide gas. This method is used to produce sulphuric acid via the Contact Process.
Hematite ore of iron contains \[Si\] as impurity where it reacts with \[{O_2}\] to produce \[Si{O_2}\] which is further used in the formation of slag. But in the extraction of copper \[Si{O_2}\] is needed to form slag.

Hence, the correct answer is option C.

Note:
You should know about the different types of iron and steel produced from the blast furnace. These include:
Cast iron: Primarily contains iron $({\text{Fe}})$, carbon $({\text{C)}}$ and silicon $({\text{Si)}}$but may also contain traces of sulphur, manganese and phosphorus. Its features are hard, brittle, non malleable and more fusible than steel. The structure is crystalline and fractures under excessive tension
Wrought iron: It is the highly pure iron with all the carbon impurities removed. Its structure is soft with less structural strength. Used to make decorative gates and railings.
Mild steel: Contains iron with about $0.25\% $ of carbon impurities. The presence of impurities makes this form of steel stronger and harder than pure iron. More the impurities, the harder the steel becomes.
High carbon steel: Contains the maximum amount of carbon impurities$(1.5\% )$. This presence of extra carbon impurities makes it hard but also gives it brittle characteristics.