This paper presents results of an experimental study concerning the hydrodynamic behaviour at incipient fluidization and expansion of fluidized beds of large particles of category D of Geldart’s classification. The effect of the physical properties of the solids and of the column geometry was analysed particularly with air at room temperature and atmospheric pressure. Relationships have been derived to predict the gas velocity and the voidage at incipient fluidization and expansion of the beds. These correlations take into account all the literature data relative to this kind of particle.