A model is developed for calculating solid-liquid phase equilibria of compound-forming systems. The method treats the compound as a new component containing stoichiometric amounts of the constituent species. The overall method is quite easy to implement and successfully reproduces the phase diagrams for a variety of complex mixtures, including organic melt systems and compound semiconductor systems. This technique is used as the basis for calculating crystallization path maps for ternary equilibrium crystallizers in which both compounds and eutectics occur. Crystallization path maps are similar to residue curve maps in VLE systems, and help to determine overall system behavior especially with regard to feasibility and design of melt crystallization processes.