High-Alumina Refractory Products

products that contain more than 45 percent alumina (Al₂O₃). The raw materials for such products are industrial alumina and electrolytically produced corundum, with the addition of refractory clay, as well as rock that has a high alumina content (cyanite, andalusite, diaspore, bauxite, and others). High-alumina refractory products are pressed from powders as coarse as 3 mm under a pressure of 60-120 meganewtons per sq m (600-1,200 kilograms-force per sq cm) and are fired at a temperature of 1500°-1750° C. In the USSR, massive highalumina refractory products are divided into classes according to alumina content and, within the classes, into groups, which are distinguished according to technical properties. Corundum refractory products have the highest properties.

High-alumina refractory products are used for walling thermal units (having temperatures higher than 1300°-1400° C) in blast furnaces, air heaters, and chemical reactors.