Process for the preparation of crystalline sodium silicates

摘要

A process for the preparation of crystalline sodium silicates with a molar ratio SiO2/Na2O of 1.9:1 to 3.5:1 from amorphous sodium silicate is described. To water-containing amorphous sodium silicate with a molar ratio SiO2/Na2O of 1.7:1 to 3.75:1 and a water content of 5 to 95% by weight is added 0.01 to 30 parts by weight of the crystalline sodium silicate to be prepared (per 100 parts by weight of Na2O+SiO2 in the water-containing amorphous sodium silicate). The reaction mixture is dehydrated by heating. The dehydrated reaction mixture is kept at a temperature of at least 450 DEG C., but below the melting point, until the sodium silicate has crystallized.