Correct Option
In the blast furnace for the production of iron, coke serves two primary functions:
- As a reducing agent: Coke (carbon) reacts with iron oxides (e.g., Fe₂O₃) to reduce them to metallic iron. For instance, Fe₂O₃ + 3C → 2Fe + 3CO. It also produces carbon monoxide (CO), which further acts as a reducing agent.
- As a fuel: Coke burns in the presence of hot air (oxygen) to generate the high temperatures necessary for the smelting process. The combustion of carbon is an exothermic reaction, C + O₂ → CO₂, which provides the required heat.
Incorrect Options
- Statement 2 (remove silica associated with the iron ore): The removal of silica (SiO₂) and other acidic impurities is the function of a flux, typically limestone (CaCO₃). Limestone decomposes to calcium oxide (CaO), which reacts with silica to form molten slag (CaSiO₃), thus separating impurities from the iron. Coke does not perform this role.
- Statement 4 (act as an oxidizing agent): Coke acts as a reducing agent, meaning it donates electrons to reduce iron oxides. An oxidizing agent accepts electrons. Therefore, coke does not function as an oxidizing agent in the blast furnace.