... insoluble substance,%,≤0.30.51.0PH value(1% aqueous solution)3.5-5.0SO2-,%, ≤ 9.8Ammoniacal nitrogen,%, ≤0.01---As,%, ≤0 ... Roller dried process: AppearanceLight yellow powderRelative density( 20 )-AL 2 O 3, ≥, %30.029.028.0Basicity,%40-90Water insoluble substance,%,≤0.51 ... .01.5PH value(1% aqueous solution)3.5-5.0SO 2- ,%, ≤9.8Ammoniacal nitrogen,%, ≤0.01-As ...