Blast Furnace Applications
The andalusite-containing products have the letter "A" as part of the suffix. These brands also have an "A" rating in the Carbon Monoxide disintegration test. The Resco brand Rescal 90XD is a mullite bonded 90% alumina brick. Because of this mineralogical make-up and extremely high purity, Rescal 90XD is best characterized by exceptional refractoriness and high temperature strength. These properties translate to good mechanical stability of the Rescal 90XD in blast furnace bottoms.
The manufacturing and formulation of Krial blast furnace brick is engineered to resist alkali attack (soda and potash). VIA high firing which reduces porosity and makes the brick less permeable to help prevent alkali penetration. In addition, stable, alkali-resistant materials (mullite) are present after high firing to further resist rapid alkali wear. The chemical compatibility of mullite to alkali attack is well documented.
Creep Resistance/Thermal Shock Resistance
Increased thermal shock, alkali attack and high temperature loading cause accelerated wear. In the blast furnace, such conditions require higher resistance than Krial 60. To meet these needs, the Krial family was expanded to include brick using andalusite to increase resistance to creep, spalling and alkali attack. Andalusite is a naturally occurring high alumina raw material that converts to mullite crystals when heated. In-situ mullite formation is noted by volume growth; products containing andalusite have always been characterized by excellent resistance to subsidence under high temperature loading. The andalusite mineral occurs naturally as a blocky character. In the brick these blocks act as crack disruptors which improves spall resistance.