Blast furnace practice — primary fuel used for smelting iron ore In ironmaking, which fuel is charged and blown with hot air to provide both heat and reducing conditions inside a modern blast furnace?

Introduction / Context:
The blast furnace reduces iron oxides to molten iron using a counter-current flow of hot gases and descending burden. The fuel must supply high temperatures, structural support to the burden, and a controlled source of carbon monoxide for reduction reactions.

Given Data / Assumptions:

• Traditional large blast furnaces with hot blast stoves are considered.
• Auxiliary fuels (pulverized coal, oil, natural gas) may be injected, but the core solid fuel in the burden remains crucial.
• Stable furnace permeability and strength are required.

Concept / Approach:
Metallurgical coke (calcined, strong porous carbon made from select coals) is the standard fuel. It provides: (1) heat by combustion to CO and CO2, (2) a permeable skeleton that supports ore and flux, and (3) carbon for direct and indirect reduction reactions. While pulverized coal injection can partially substitute fixed carbon, coke’s mechanical strength at high temperatures and its role in maintaining bed permeability make it indispensable in conventional practice.

Step-by-Step Solution:

Verification / Alternative check:
Operating data from integrated steelworks universally list coke rate (kg/t hot metal) as a key performance indicator; other fuels are “injected,” not the main solid burden fuel.

Why Other Options Are Wrong:

• Raw coal: lacks required strength and devolatilizes, damaging permeability.
• Wood: insufficient strength and energy density.
• Producer or natural gas alone: used as injectants or in other furnaces, not as the primary solid burden fuel.

Common Pitfalls:
Assuming fuel injection replaces coke completely; underestimating the structural role of coke.

Final Answer: