1. AL2O3:40%-48%. 2. High refractoriness. 3. Physicochemical stability. 4. High quality refractory raw materials. Calcined kaolin clay Characteristics: 1. High refractoriness. ... 0.51.52.02.53.03.54.04.5Applications:Calcined kaolin clay is mainly used for manufacturing high-quality refractory products, ... crucibles, ceramic fiber, precision casting sand, ceramics products, etc. Calcined kaolin clay