Sodium silicate solution (water glass) and mineral acid are reacted in an agitated vessel to produce a slurry of amorphous silica particles. The critical physical properties of precipitated silica, such as particle size and porosity, are controlled during this stage of the process by manipulating, among other things, the composition, concentration, and ratio of reactants in the precipitating solution; the speed of agitation; the reaction time; and the reaction temperature.

he precipitated silica slurry is then concentrated to form a filter cake. The product filter cake is washed to remove the salt byproduct that is produced during precipitation.

The silica filter cake is then dried to the desired final product moisture content.

The dried silica is then finished to achieve the desired final product form. This can include: agglomeration or compaction into a low-dust form, or milling and classification to the required particle size distribution.