Kinetics of moisture absorption in mixtures for iron foundry

The moisture absorption in granulated materials used in foundry technologies is analyzed. The absorption process has a diffusive behavior mainly. A simple experimental technique, in which the wet weight increment was recorded as the experimental parameter and an analytic method with computing procedure to find the parameters characterizing the process was used. The determination of these parameters by traditional methods is a very difficult task so, very refined and expensive trials are needed. The fitting of the model permits to determine the diffusion coefficient and the moisture concentration in the separation surface between the sample and the environment. The concentration profiles are established for different times. Finally, the possibility of occurrence of superimposed diffusive processes in some materials is analyzed and the diffusion coefficient and the amount of moisture incorporated by each process are calculated.