Blast furnace anatomy — name the portion above the widest cross-section In an iron-making blast furnace, the part located above the widest cross-section is called:

Introduction / Context:
A blast furnace is divided into distinct zones based on geometry and function: hearth, bosh, stack, and throat. Knowing these names is essential for understanding where reactions and heat transfer occur during ironmaking.

Given Data / Assumptions:

• The furnace has a characteristic “belly” or widest cross-section in the bosh region.
• Above this maximum diameter lies the tall, narrowing section.
• The very top opening is the throat, where burden is charged and gases exit.

Concept / Approach:
The hearth at the bottom collects hot metal and slag. The bosh, just above the hearth, flares outward to the maximum diameter and houses intense combustion and melting. Above the bosh is the stack: a long, tapering shaft where descending burden is preheated and partially reduced by rising gases. The throat is at the very top.

Step-by-Step Solution:
Identify the widest section: located in the bosh.Define the region immediately above the widest section: the stack.Select the correct term accordingly.

Verification / Alternative check:
Standard blast furnace schematics label the sections bottom-to-top as hearth → bosh → stack → throat.

Why Other Options Are Wrong:

• Hearth: the lowest part, below the widest section.
• Bosh: the region containing the widest section, not above it.
• Throat: the top opening above the stack.
• Breeze chamber: not a standard blast furnace section name in this context.

Common Pitfalls:
Mixing “bosh” and “stack” due to both being above the hearth; remember, the bosh holds the belly (maximum diameter), and the stack is above it.

Final Answer:
stack