46%≥Al2O3≥42%,53%≥SiO2≥51%,1.2≤Fe2O3≤1.5%,Na2O+K2O≤0.3%,CaO+MgO2≤0.6%,TiO2≤0.1%。物理指标:密度≥2.5g/cm3,真比重 >2.6g/cm3,含水量< 0.03%,耐火度≥1750℃,灼减少量≤0.3-0.4%,含尘度≤0.01-0.03%,PH值 7-9,型壳硬度>8.0Mpa。