Calcined alumina can be used in the polishing of different alumina products(mainly used in middle, fine polishing).It is also widely used in high-class aluminium refractory material, unshaped refractory materials, high aluminium ceramic product and advanced coating, etc, . Item Al2o3 % Na2o % Sio2 % Fe2o3 % D50 A4m 99.8 0.1 0.05 0.02 3.1