Chromite refractories (FeO·Cr2O3 spinel family) are classified as which type based on their chemical behavior toward slags?

Introduction / Context:
Chromite refractories are widely used in non-ferrous metallurgy and certain steelmaking zones because of their balanced chemical resistance. Classification guides where they can be placed in contact with acidic or basic slags without severe corrosion.

Given Data / Assumptions:

• Chromite is primarily FeO·Cr2O3 spinel or related compositions.
• Question asks for the chemical classification: acidic/basic/neutral.
• Firing temperatures for industrial bricks are far higher than 600 °C.

Concept / Approach:
Chromite refractories are considered neutral, meaning they possess reasonable resistance to both acidic and basic slags compared with strictly acidic (silica) or basic (magnesia) bricks. This neutrality makes them versatile for certain transition zones. They are not fired at as low as 600 °C; industrial firing/sintering is much higher to develop strength and bonding.

Step-by-Step Solution:
Review classification definitions.Assign chromite to neutral behavior based on service record.Reject incompatible statements (e.g., 600 °C firing).Select “Neutral refractories.”

Verification / Alternative check:
Application guides list chromite bricks for zones where both silica and magnesia would face selective attack, underscoring their neutral classification.

Why Other Options Are Wrong:
Acidic/Basic: too one-sided; chromite is classified as neutral.600 °C firing/Ultra-insulating only: factually incorrect or incomplete.

Common Pitfalls:
Assuming “chromite” implies “chrome-magnesite” (which can be basic); pure chromite compositions are neutral.

Final Answer:
Neutral refractories