Crystallization of Sodium Chloride with Amines as Antisolvents

The suitability of the amines diisopropylamine (DiPA) and dimethylisopropylamine (DMiPA) as antisolvents for the crystallization of sodium chloride from its aqueous solution has been demonstrated. Both amines decreased the sodium chloride solubility substantially. The presence of a two liquid phase area offered the opportunity to separate the amines from the mother liquor after crystallization by a temperature increase. In the two liquid phase area the mutual solubilities of the water and the amines were low, so the separability was good. Continuous crystallization experiments were carried out at temperatures below the liquid-liquid equilibrium line in the single liquid phase area. The product consisted of cubic agglomerated NaCl crystals with maximum primary particle sizes of 10-70 μm.