Direct modeling of structures and segregations during industrial casting processes is made difficult due to the need for coupling intricate phenomena occurring at multiple length and time scales. Its outputs are, however, required for modeling of further thermomechanical treatments as well as for prediction of in-service properties. The present article presents recent efforts made to integrate microscopic scale concepts taken from physical metallurgy into a macroscopic model. This new model includes macroscopic solution of average conservation equations, mesoscopic scale description of the development of the grain structure, together with microscopic scale consideration for the kinetics of the solid-liquid interfaces and the chemical segregation taking place between phases. Simulations are presented for directional solidification of a cylindrical ingot, a benchmark experiment for macrosegregation in a rectangular cavity, and a surface treatment that mimics the gas tungsten arc welding process. The difficulties of transforming the model into a tool applied for industrial castings are discussed.