sulfuric acid method is divided into oil column forming and air granulation. the former is a gradual elimination method.
The process is basically the same as that of fine-porous spherical silica gel. The difference lies in the aging process. When preparing coarse-porous spherical silica gel, the hydrogel flowing out of the receiving tank is first aged with steam for more than 8 hours. After aging, it is soaked in 0.1%-0.2% dilute sulfuric acid in the washing tank for 12 hours, and then washed (except Na2SO4), dried, sieved and dried to obtain coarse-porous spherical silica gel.