The study of drying of red alga (Gelidium sesquipedale, Rhodophyta), with initial sample masses varying from 1 to 10 g, was carried at different temperatures 30 -80 °C. The experimental drying curves show a slight effect of the initial mass. Two types of curves are obtained: those at temperatures below 50 °C are fitted into straight line according to an interfacial progression process in cylindrical symmetry. Those of high-temperature drying (50 < θ < 80 °C), are perfectly parabolic and show that the kinetic regime is controlled by the three-dimensional diffusion according to the Jander equation. The two types of water molecules identified were also highlighted during the drying kinetics process. The apparent activation energy of the strongly bounded water (20%) is about 36.25 kJ·mol -1 , and that of the wetting water is in the range of 47.68 kJ·mol -1 .

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This paper concerns the study of the phosphate ore and a coke of solid combustible. The determination of their physicochemical characteristics and the study of their structural, textural and morphological aspects before and after thermal treatment are important and necessary for understanding of the reaction mechanisms and of the modelling of the processes of combustion and calcination.The characterization of these materials was accomplished according to various experimental techniques such as: X-ray diffraction; infrared spectroscopy, scanning electron microscopy, porosimetry and the BET method. The results obtained show that the X-ray diffraction pattern of the coke presents only the crystalline phase of the graphite. The diffraction pattern of the raw phosphate as well as the crystallographic parameters at 25°C (a = 9.36 Å, c = 6.90 Å) are consistent with those given in the literature and indeed correspond to those of the crystal lattice of pure fluorapatite. The specific surface of natural phosphate is in the range of 13.36 m² .g -1 and that of the coke is 0.361 m² .g -1 . The total pore volume of the phosphate ore measured by the condensation of nitrogen adsorbed was 0.178 mL and the mean opening diameter of the pores is 0.029 m. The real density of the phosphate (2.96 g.cm -3 ) and that of the coke (1.36 g.cm -3 ), were determined using an ultra pycnometer. Morphological observation of the grain surface shows fairly homogenous areas and a porous structure in the phosphate ore. The coke grains show on the contrary a difference in the grain size and a non-porous structure.