Ironmaking practice: Which fuel is predominantly used in the blast furnace to produce pig iron from iron ore?

Introduction / Context:
The blast furnace reduces iron oxides to iron using a carbonaceous fuel that also supplies both heat and reducing gases. Industrial practice relies on a specific metallurgical fuel for permeability, strength, and reactivity under furnace conditions.

Given Data / Assumptions:

• Operation at high temperatures with strong gas flow and burden load.
• Need for stable furnace permeability and minimal fines generation.
• Fuel must provide both carbon (as CO generator) and structural support.

Concept / Approach:

Hard coke (metallurgical coke) is the standard blast furnace fuel. Its high carbon content, mechanical strength, low volatile matter, and porosity allow it to support the burden while reacting with oxygen and CO2 to form CO, the principal reducing gas. Alternatives such as soft coke or raw coals lack the necessary strength and would degrade, impairing permeability; limited pulverised coal injection is used as a supplemental reductant/energy source but does not replace coke's structural role.

Step-by-Step Solution:

Verification / Alternative check:

Modern furnaces employ pulverised coal injection rates but still maintain a substantial coke rate to preserve furnace permeability and hearth conditions.

Why Other Options Are Wrong:

Soft coke and raw bituminous coal disintegrate, causing channeling and pressure drop issues.Pulverised coal is an auxiliary injectant, not the sole bed-supporting fuel.Charcoal can be used in small/experimental furnaces but is not predominant industrially.

Common Pitfalls:

Assuming coal injection replaces coke entirely; structural and permeability requirements prevent full substitution in conventional blast furnaces.

Final Answer:

hard coke