Common Type: Item SD522 SD523 SD521 SD520 Appearance White Powder White Powder White Powder White Powder SiO2 (dry basis) % �90 �90 �90 �90 Heating Loss(105, 2h) 4.0-7.0 4.0-7.0 4.0-7.0 4.0-7.0 Ignition Loss (dry, 1000, 2h) �7 �7 �7 �7 pH Value 6.5-7.5 6.5-7.5 7.0-7.5 6.5-7.5 Superfine Type: Item SSD-627 SSD-727 SSD-527 Appearance White Powder White Powder White Powder SiO2 (dry basis) % �90 �90 �90 Heating Loss(105, 2h) 4.0-7.0 4.0-7.0 4.0-7.0 Ignition Loss (dry basis, 1000, 2h) �7 �7 �7 pH Value 6.5-7.5 6.5-7.5 7.0-7.5 Specific Area (m2/g) 180-220 180-220 200-400 Absorption (cm3/g) 2.6-3.0 2.6-3.0 3.4-3.7 Total Fe (mg/kg) �300 �300 �300 Total Cu (mg/kg) �10 �10 �10 Total Mn (mg/kg) �40 �40 �40 Matter on Sieve (45μm) % �0.5 �0.5 �0.5 D50 (μm) 13+/-0.5 9+/-0.5 9+/-0.5 D90 (μm) 18+/-0.5 17+/-0.5 17+/-0.5 D97 (μm) 22+/-0.5 20+/-0.5 20+/-0.5