Blast furnace anatomy — name the zone below the widest section In a conventional blast furnace, what is the name of the region located immediately below the widest cross-section (belly), where the furnace wall tapers inward toward the hearth?

Introduction / Context:
Identifying blast furnace zones is essential for understanding gas flow, heat transfer, and reaction progress in ironmaking. Each region has distinct geometry and functions that influence charging practice and tuyere operations.

Given Data / Assumptions:

• The widest section is called the belly.
• The region below the belly narrows toward the hearth.
• Standard blast furnace components include throat, stack, belly, bosh, and hearth.

Concept / Approach:
The bosh is the frustoconical section below the belly where the furnace tapers inward. It houses the tuyeres (through the bosh jacket) and endures intense thermal and chemical attack. Below the bosh lies the hearth, which collects molten hot metal and slag. Above the belly is the stack, and at the very top is the throat where burden materials are charged.

Step-by-Step Solution:

Verification / Alternative check:
Engineering schematics of blast furnaces consistently label the inward-tapered section below the belly as the bosh; tuyere level is associated with the bosh.

Why Other Options Are Wrong:

• Hearth: is the bottom reservoir for molten products.
• Stack: situated above belly/throat; not below the widest section.
• Throat: top charging area.
• Bustle: refers to bustle pipe (wind distribution ring), not a furnace zone.

Common Pitfalls:
Confusing the bosh with hearth because both are hot zones; misplacing the stack relative to the belly.

Final Answer: