Blast furnace operation — temperature zoning: In the middle region of a blast furnace (often called the zone of absorption or indirect reduction), the typical bulk temperature range is approximately:

Introduction / Context:
The blast furnace has distinct thermal and chemical zones that govern ore reduction, softening, melting, and final hot-metal collection. Recognising the characteristic temperature ranges helps explain where particular reactions and phase changes occur within the shaft.

Given Data / Assumptions:

• “Middle part / zone of absorption” refers to the shaft region of indirect reduction where CO and H2 reduce iron oxides.
• We consider steady operation with typical burden and hot blast conditions.
• Temperatures cited are bulk-zone averages, not local raceway peaks.

Concept / Approach:
In the upper stack, gases preheat and dry the burden at roughly 400–700°C. Moving downward into the middle (indirect-reduction) zone, endothermic reduction of Fe2O3/Fe3O4 to FeO and Fe progresses vigorously at about 800–1000°C. Below this, the cohesive and fusion zones approach 1200–1700°C, culminating in the hearth where fully molten iron and slag collect. Therefore, the middle absorption zone aligns with temperatures near 800–1000°C.

Step-by-Step Solution:
Identify each major zone and its reactions.Map reaction energetics to temperature tiers.Associate the mid-stack reduction regime with 800–1000°C.Select 800–1000°C as the correct range.

Verification / Alternative check:
Standard ironmaking texts depict the indirect-reduction zone around 700–1100°C, overlapping strongly with the 800–1000°C band.

Why Other Options Are Wrong:
400–700°C corresponds to drying and preheating at the top.

1200–1300°C and 1500–1700°C are typical of softening/fusion/hearth regions lower down.

1800–2000°C exceeds normal bulk temperatures and risks refractory damage.

Common Pitfalls:
Confusing raceway flame temperatures with bulk region averages; overlooking that the cohesive zone sits below the indirect-reduction zone.

Final Answer:
800°C to 1000°C