A crystallizer is a device commonly used for substance separation and purification. Its principle is to gradually crystallize the solute in a solution by cooling or evaporating it under conditions where the solute exceeds its solubility, thereby achieving the separation and purification of the target substance in the solution.

Preparation of saturated solution. Add the solute that needs to be crystallized to the solvent, stir or heat to fully dissolve it until it reaches saturation. In a saturated state, the solubility of the solute is high.

The generation of supersaturation. On the basis of a saturated solution, the solubility of the solute is reduced by lowering the temperature or increasing the concentration of the solute in the solvent, thereby forming a supersaturated state of the solution. Supersaturation refers to the actual concentration of solutes in a solution being higher than their solubility, which is an important condition for the formation of crystals.

The formation and growth of crystal nuclei. In supersaturated solutions, solute molecules aggregate to form small crystal nuclei. Over time, these nuclei gradually increase and combine with surrounding solute molecules to form stable crystals. The crystallization process can be adjusted by controlling parameters such as temperature, stirring speed, and solution concentration.

As a device for material separation and purification, the principle of a crystallizer is to achieve the separation and purification of target substances in a solution by controlling solubility, supersaturation, and the formation and growth of crystal nuclei. It is widely used in the fields of chemical engineering, pharmaceuticals, food, metallurgy, etc., mainly for the separation and purification of substances, concentration of solutions, control of crystal growth and crystal form, preparation of microcrystals and nanocrystals, as well as recrystallization and recrystallization.