Which of the following is used in the production of steel?

Coke

The correct answer is option 1. Coke.

Coke is a crucial material in the production of steel, and its role is closely associated with the process of smelting iron ore in a blast furnace. Here's an explanation of how coke is used in the production of steel:

1. Coke Formation: Coke is derived from coal through a process called coking. In this process, coal is heated in the absence of air to drive off volatile components and leave behind a porous, carbon-rich material known as coke.

2. Blast Furnace Operation: In the production of steel, iron ore (usually in the form of iron oxide, such as hematite or magnetite) is smelted in a blast furnace. The blast furnace operates at high temperatures and relies on a series of chemical reactions to extract iron from the iron ore.

3. Reduction of Iron Ore: Coke serves as a reducing agent in the blast furnace. It reacts with the oxygen in the iron ore, reducing the iron oxide to molten iron. The chemical reaction involving coke can be represented as: \( Fe_2O_3 + 3CO \rightarrow 2Fe + 3CO_2 \)

4. Formation of Liquid Iron: The molten iron, separated from impurities in the ore, collects at the bottom of the blast furnace.

5. Slag Formation:  Impurities in the iron ore combine with limestone (added to the furnace) to form a liquid slag, which floats on top of the molten iron.

6. Coke Combustion: The combustion of coke also provides the necessary heat for the overall process. The carbon in Coke burns with the oxygen in the air, producing carbon dioxide and releasing heat.

In summary, coke plays a dual role in the production of steel: it acts as a reducing agent, facilitating the extraction of iron from the ore, and it provides the heat necessary for the entire smelting process in the blast furnace. The resulting liquid iron can then be further processed to obtain the desired steel products.