Question

Which one of the following is gas based sponge iron making method?

• A. SL/RN process
• B. Rotary kiln process
• C. Midrex process
• D. Shaft furnace process

Hint:

For DRI processes, associate the reactor type with the typical reductant:

• Rotary Kiln \(\rightarrow\) Coal-based (e.g., SL/RN)

• Shaft Furnace \(\rightarrow\) Gas-based (e.g., Midrex, HYL)

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
Sponge iron, or Direct Reduced Iron (DRI), is produced by reducing iron ore in the solid state. The processes are broadly classified based on the type of reductant used (solid like coal, or gas like reformed natural gas) and the type of reactor (rotary kiln, shaft furnace, etc.).

Step 2: Detailed Explanation:
Let's analyze the given processes:

• (A) SL/RN process: This process uses a

rotary kiln and a solid reductant, typically non-coking

coal. It is a coal-based process.

• (B) Rotary kiln process: This is a general name for processes that use a rotary kiln reactor. The vast majority of these are

coal-based (like SL/RN, Krupp-Renn).

• (C) Midrex process: This is the most widely used DRI process globally. It uses a vertical

shaft furnace and the reducing agent is a

gas (a mixture of carbon monoxide, CO, and hydrogen, H\(_2\)) produced by reforming natural gas. This is a classic example of a gas-based process.

• (D) Shaft furnace process: This refers to the type of reactor. While the Midrex process uses a shaft furnace, this option is less specific. Other gas-based processes like the HYL/Energiron also use shaft furnaces. However, 'Midrex process' is the specific name of a gas-based method.


Step 3: Final Answer:
The Midrex process is the quintessential example of a gas-based method for producing sponge iron.