Refractory classification: which of the following is a basic refractory material suitable for service with basic slags?

Introduction / Context:
Refractories are commonly categorized as acidic, basic, or neutral according to their chemical behavior with slags and atmospheres. Correct identification is essential when lining furnaces, ladles, and converters to minimize chemical attack and extend lining life. This question asks for the basic refractory among common options.

Given Data / Assumptions:

• Acidic refractories: silica and fireclay (alumino–silicate family).
• Basic refractories: magnesia, doloma, and chrome–magnesite compositions.
• Neutral refractories: alumina, chromite, graphite, silicon carbide (context dependent).

Concept / Approach:
Chrome–magnesite refractories incorporate magnesia (MgO) with chromite/spinel phases, providing strong resistance against basic slags rich in CaO and FeO. Fireclay (alumino–silicate) and silica are attacked by basic slags and thus are classified as acidic. The correct selection for a basic refractory is chrome magnesite.

Step-by-Step Solution:
Review each candidate’s primary chemistry.Match chemistry with slag compatibility (basic vs. acidic).Identify chrome magnesite as the basic refractory.Confirm others are not basic.

Verification / Alternative check:
Steelmaking handbooks and supplier datasheets list chrome–magnesite bricks specifically for basic oxygen furnaces and other basic environments, validating the classification.

Why Other Options Are Wrong:
Fireclay: alumino–silicate, acidic behavior.Silica: strongly acidic; unsuitable with basic slags.None of these: incorrect because chrome magnesite is a standard basic refractory.High-alumina: often treated as neutral, not basic.

Common Pitfalls:
Confusing chromite (neutral) with chrome–magnesite (basic due to MgO).Assuming “high-alumina” implies basicity; it does not.

Final Answer:
Chrome magnesite