Basic open-hearth furnace roof linings: which brick family is typically used for the roof (crown) despite the furnace handling basic slags?

Introduction / Context:
Historically, basic open-hearth furnaces handle basic slags, yet the roof choice does not always mirror hearth chemistry. The roof endures radiant heat and specific thermal gradients, favoring particular materials.

Given Data / Assumptions:

• Roof experiences high temperatures and thermal cycling with limited slag contact.
• Silica bricks offer excellent creep resistance and integrity in hot crowns.

Concept / Approach:
Silica bricks are time-tested in crowns/roofs for many furnaces because they hold shape at high temperature and have acceptable expansion behavior for arch stability, even if the bath/slag below is basic. Hearths/slag lines may be basic refractories, but roofs can be silica based on structural performance needs.

Step-by-Step Solution:
Separate roof requirements from slag-contact requirements.Match silica brick strengths (creep resistance, high-temperature stability) to roofs.Choose “Silica bricks.”

Verification / Alternative check:
Classical lining schedules for open-hearths report silica crowns with basic hearths/sidewalls.

Why Other Options Are Wrong:
Basic bricks dominate slag-contact zones, not necessarily roofs.

Common Pitfalls:
Assuming uniform refractory chemistry throughout the furnace; different zones have different demands.

Final Answer:
Silica bricks