DRYING OF CLAY. I MATERIAL CHARACTERISTICS.

In this study, one got involved in the thermodynamic characterization of two types of clay to be dried. It concerns the determination of the chemical composition through X-ray diffraction, index of plasticity, volumic mass and especially the determination of the sorption isotherms of water vapor on these products at three different temperatures 30, 50 and 70°C. The isosteric enthalpy of adsorption is calculated by the Clapeyron equation it varies from 0 to 2k J/mol for Tunisian clay G, and from 0 to 3 k J/mol for French clay R. Four models provided by the literature i.e., Chung-Pfost, Henderson, Halsey and Guggenheim-Anderson and de Boer (GAB) have been tested and evaluated (correlation factor, standard deviation) to determine the best possible fitting, allowing for the interpolation of experimental results. From the comparison of the results, one noticed that both the Henderson and the GAB models perfectly described the experimental measures for the two types of clay with factors of correlation situated around one and standard deviations tending towards zero. This set of characterizations will allow us at a later stage to understand the drying process of these two types of clay. [ABSTRACT FROM AUTHOR]