Acidic vs basic refractories: identify the option that is not an acidic refractory material in standard classification used for furnace linings.

Introduction / Context:
Refractories are classified as acidic, basic, or neutral according to their chemical behavior toward slags and fumes. This classification guides selection for steelmaking, non-ferrous processing, and glass furnaces to avoid chemical dissolution or rapid wear.

Given Data / Assumptions:

• Acidic refractories resist acidic slags but are attacked by basic slags.
• Basic refractories resist basic slags but are attacked by acidic slags.
• Neutral/high-alumina materials can show amphoteric/neutral behavior depending on composition.

Concept / Approach:
Silica and fireclay are classic acidic refractories. Magnesia (MgO) is the archetypal basic refractory used against basic steelmaking slags. High-alumina (bauxite) bricks are often classed as neutral to slightly acidic/basic depending on Al2O3 content, but they are not “acidic” in the strict silica-rich sense. Among the options, magnesia is unambiguously not acidic; it is basic.

Step-by-Step Solution:
List acidic materials: silica, fireclay.Identify MgO as basic; Al2O3-rich bauxite tends toward neutral behavior.Choose the clearly non-acidic option: magnesia bricks.Confirm compatibility logic with basic slags in steelmaking practice.

Verification / Alternative check:
Steel converter linings commonly use magnesia or magnesia–carbon to withstand basic CaO-rich slags, confirming MgO’s basic classification.

Why Other Options Are Wrong:
Silica/Fireclay: quintessential acidic refractories.Bauxite: generally neutral; the question seeks a clearly “not acidic” choice → magnesia is best.Siliceous ramming mixes: silica-rich, hence acidic.

Common Pitfalls:
Assuming all alumina refractories are acidic; many high-alumina compositions are neutral or amphoteric in service.

Final Answer:
Magnesia (periclase) bricks