Polysilicates, hydrous sodium

Cogranules of Hydrous Sodium Polysilicate and Sodium Carbonate.398... 

Hydrous sodium polysilicate granules Hydrous sodium polysilicate granules Cogranules of hydrous sodium polysilicate and sodium carbonate... 

Hydrous sodium polysilicate powder Sodium silicate solutions... 

Hydrous sodium polysilicates are available as powders with bulk densities from 80 to 650 g/L and compacted granules with bulk densities in the range 750-950 g/L. Particle sizes are between 80 and 700 pm [2,11,65]. Made from sodium silicate solutions, they may contain 16-22 wt% moisture [1,5,7,11]. Water uptake is generally limited by their tendency toward caking at higher moisture levels. They are x-ray amorphous and have no defined stoichiometry [19,65]. The composition is... 

Hydrous sodium polysilicate powders are manufactured by removing a part of the water content of the corresponding silicate solutions through drum or spray drying (see Table 22.1) [1,7,8,17-19,21,49]. 

FIGURE 22.5 Spray drying process for the production of hydrous sodium polysilicate powders. 

Crystalline layered sodium disUicates are the most recent development in the field of detergent silicates. In contrast to hydrous sodium polysilicates and metasilicates, they display a three-dimensional crystal lattice characterized by corrugated silicate layers, which are separated by sodium ions. The chemical formula is NajSijO,. This reflects that the material is anhydrous and has a formal molar ratio of 2. Several crystal phases differ in the kind of corrugation of the silicate layers [3,21,66,86-88]. 

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