Simulation of Crystallisation and Precipitation Processes. The various processes of crystallisation and precipitation lead to a wide variety of particle size distributions, which are also subject to the influence of the specific properties of the material systems. It was examined whether and to what extent these processes can be described in process engineering terms by a consistent simulation with a unified basic model of crystallisation. The basic model corresponds essentially to known concepts : it is based on the law of mass action but purposely omits ad hoc proposals found in the literature in the formulation of nucleation/nucleus decline kinetics. The results of simulation obtained for various material systems and processes demonstrate considerable adaptability of the basic model. It appears to be suitable for uniform description and to serve as an adequate basis of development of crystallisation-specific properties of material systems.