Numerical mold and core sand simulation

The life cycle of mold and core sand extends from core blowing and gassing through to the complex physico-chemical processes involved in the formation of lustrous carbon and the thermal degradation of the binder material during casting and solidification. Although different processes are at work they share the common feature of a sand environment, which implies that their simulation may be based on a reactive porous media description. The present work describes a multi-component gas phase model of reactive transport in mold and core sand. Rate equations for sand material degradation and retention are combined with a general porous media model to provide a flexible framework for detailed process modeling. The 3D-model is implemented in a simulation code for use during mold filling and solidification. The generation, transport and evolution into the environment of sand gases are simulated providing a quantitative assessment of emissions. The processes of thermal degradation of sand material components, gas component retention and/or condensation and kinetic reactions in the gas phase are described. The description is applied to the thermal degradation of binder material, moisture transport in green sand molds and the formation of lustrous carbon during casting and solidification.