MULLITE BRICKS The glass and steel industries are two main markets for mullite bricks. The steel industry is the largest user, where refractoriness, high resistance and thermal shock resistance are important. The main use of high-mullite based products is in hot blast stove checker bricks. Many refractories in use in the steel industry have varying amounts of mullite based aggregates in them. Steel ladles, lances, reheat furnaces and slide gates are examples of mullite aggregate based products with various almina contents . The use of monolithic and precast shapes is increasing with the use of bricks declining. The glass industry uses mullite based refractories in burner blocks, ports and in checker bricks as well as in the upper structure of the tanks where the glass is melted and in the drawing chambers.