Refractory selection in steelmaking: dolomite bricks (CaO–MgO based) have comparatively good chemical resistance against which of the following attacks in basic steelmaking service?

Introduction / Context:
Dolomite refractories are basic bricks composed primarily of calcium oxide and magnesium oxide. They are widely used in steelmaking vessels that work with basic slags rich in CaO. Knowing what dolomite resists best is essential for choosing the right lining in converters, ladles, and refining units where slag chemistry drives wear.

Given Data / Assumptions:

• The brick type is dolomite (CaO–MgO systems, often pitch- or resin-bonded).
• Operating environments include molten steel, iron-oxide-bearing phases, and lime-rich (basic) slags.
• “Resistance” means lower corrosion/erosion rate at service temperature.

Concept / Approach:
Basic refractories show best compatibility with basic slags. Dolomite is chemically similar to lime and magnesia phases, so lime-rich slags are comparatively non-aggressive. In contrast, acidic or FeO-rich oxidizing slags can dissolve basic bricks more readily. While molten steel itself can cause mechanical/thermal wear, the dominant chemical corrosion driver is generally slag composition; matching basic bricks to basic slags reduces dissolution.

Step-by-Step Solution:
Identify brick chemistry: CaO–MgO → “basic” refractory.Match to slag type: basic bricks best resist basic (lime) slags.Compare other environments: FeO-rich conditions are more corrosive to basic bricks; molten steel contact alone is not the primary compatibility advantage.Therefore, the attack against which dolomite bricks have comparatively good resistance is lime slag.

Verification / Alternative check:
Refractory selection charts for steelmaking show dolomite in desulfurizing, CaO-rich refining, and BOF applications where lime-saturated slags prevail. Lab corrosion cups likewise show reduced dissolution rates in basic melts for CaO–MgO bricks.

Why Other Options Are Wrong:
Molten steel: mechanical/thermal issues exist; chemical “advantage” is not specific.Iron oxide: FeO-rich slags intensify corrosion of basic bricks.None of these: incorrect because lime slag is indeed the most compatible.

Common Pitfalls:
Ignoring slag chemistry and focusing only on metal contact; assuming all basic refractories resist FeO equally well despite its fluxing effect.

Final Answer:
lime slag