Why are chromite ores high in alumina useful for making refractory brick?

Chromite ores high in alumina are preferred for the production of refractory bricks because they contribute to the material's overall performance in high-temperature environments.1

While the usefulness of chromite as a refractory is primarily attributed to its high melting point (2,180 °C), moderate thermal expansion, and neutral chemical behavior, the inclusion of alumina enhances these properties. Specifically, mixtures of chromite and other materials—such as those containing alumina—are utilized to improve refractoriness, volume stability, and resistance to spalling. For instance, certain fused-cast refractories composed of 80 percent alumina and 20 percent chromite are noted for being highly resistant to the corrosive action of various fluxes, slags, and glasses.2

By incorporating alumina, manufacturers can produce more robust bricks that maintain structural integrity under the demanding conditions found in industrial furnaces.23