Determination of growth and breakage kinetics of l-threonine crystals

The crystal growth and breakage kinetics of l-threonine by evaporation crystallization were studied at the laboratory scale using a 1200 ml crystallizer with draft tube. Evaporation experiments were carried out at three different temperatures and three different stirrer speeds. Crystal breakage phenomena were demonstrated by image analysis and evolution of crystal size distribution. Breakage of binary uniform distribution and volume-independent growth kinetics were extracted by moment method. Moreover, the breakage and growth kinetics were proved to be appropriate for l-threonine/water evaporation process using numeric simulation. The growth kinetic parameters indicated that diffusion should be the rate-controlling step of crystal growth, and higher temperature higher growth rate. The higher exponent of agitation speed for breakage kinetics indicated that the removal of fragments stimulated by stirring should be the main breakage mechanism.