Determination of recycle potential in waste green foundry sand through spatiotemporal analysis of sand mold

Abstract

Green sand is used for making molds to obtain the desired casting in foundries. The process is associated with solidification of molten metal that results in the evolution of the latent heat of fusion. The clay used for binding purpose is decomposed to various forms depending on the local temperature. It is thus necessary to determine temperature distribution in the molds such that much of the sand that is intact can be saved and recycled as it is. This paper studies the heat transport in the mold to obtain the spatio-temporal temperature profile in the green sand mold. Furthermore, the impact of the heat of molten metal on sand properties (loosely bound clay/oolitic deposits) was also quantified as it is known that clay decomposes at a temperature >773 K. The clay and oolitic content were found to be varying across the used mold. The values of loosely bound clay and oolitic content were found to be 1.8% and 9.2%, respectively, at a distance of 0.1 cm away from the casting face while at a distance of 12 cm they were 10.95% and 0.6%. It was observed that only 15% volume of the mold was affected owing to the heat of the molten metal for a 10 kg casting. COMSOL-Multiphysics software was used to predict and validate the temperature distribution in the mold. The results agree reasonably well with the experimental findings. A careful demolding process would thus prevent a huge amount of sand from going to dumping land. • Temperature and active clay concentration are measured across the green sand mold. • Effect of high temperature on the clay coating and oolitic deposits is quantified. • Experimentally validated 3-D model is proposed for temperature and clay profiles. • A significant portion of unaffected sand can be recycled to reduce dumping.