Usage: As high quality refractory materials for making fire bricks, etc. Specifications: Al2O3: 53~55% SiO2 38~40% Fe2O3 1.1~1.4% Refractoriness °C: 1790 Loss of Ignition: 0.54~0.89% Hardness: 7% Density: 3.1~3.2g/cm3 Size: 0~3mm Output: 200t/m.