Wet Chemically Manufactured Silicas and Silicates

The wet chemical manufacturing proces.ses can be divided into precipitation processes, gel processes and hydrothermal proces,ses, of which the precipitation processes are the most important. 

In precipitation processes acid is added to a water-glass solution and acid, generally H2SO4, simultaneously with water in a large agitator vessel. 

Silica gels dried under supercritical conditions are called aerogels 

If the water-glass solution is reacted with alkaline earth or aluminum salts, silicates are obtained instead of silicas. 

In the hydrothermal process, aqueous suspensions of quartz sand and chalk are heated under pressure  

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