- The feed to a crystallizer should be slightly unsaturated.
- Complete recovery of dissolved solids is obtainable by evaporation, but only to the eutectic composition by chilling. Recovery by melt crystallization also is limited by the eutectic composition.
- Growth rates and ultimate sizes of crystals are controlled by limiting the extent of supersaturation at any time.
- Crystal growth rates are higher at higher temperatures.
- The ratio S 1⁄4 C=Csat of prevailing concentration to saturation concentration is kept near the range of 1.02–1.05.
- In crystallization by chilling, the temperature of the solution is kept at most 1–28F below the saturation temperature at the prevailing concentration.
- Growth rates of crystals under satisfactory conditions are in the range of 0.1–0.8 mm/hr. The growth rates are approximately the same in all directions.
- Growth rates are influenced greatly by the presence of impurities and of certain specific additives that vary from case to case.
- Batch crystallizers tend to have a broader crystal size distribution than continuous crystallizers.
- To narrow the crystal size distribution, cool slowly through the initial crystallization temperature or seed at the initial crystallization temperature
