Particle aggregation can be induced by adding salts or another chemical referred to as coagulant or flocculant. The term ”Flocculation” is commonly used when aggregation is induced by addition of polymers or polyelectrolytes.

Indeed, the addition of salt can promote flocculation, but not in all clays. In fact, in kaolin the effect can be quite the opposite. If you work with kaolin, you should know that pH is the strongest control on its behaviour, more than the saline concentration. On the other hand, adding salt to a suspension of montmorillonite in water will make it settle much faster. Depending on the dominant cation in the montmorillonite you are using, you will notice different behaviourw with sodium, potassium, calcium or magnesium chlorides.

Salt don't usually have much effect on kaolin as it does on montmorrrillonite.