On the basis of the experimental study of air velocity profiles in a pilot plant scale unit, the validity of the hypotheses of the gas flow model proposed for conical spouted beds, that is to say, flow rate conservation along each streamtube and plug flow in the spout zone, has been proven. A correlation has been obtained for calculation of the local velocity as a function of the contactor geometric factors (angle, inlet diameter) and of the operating conditions (solid density, particle size, relative air velocity). The validity of the gas flow model has been proven in a wide range of operating conditions and a correlation has been obtained for calculation of the dispersion coefficient as a function of the following moduli : bed upper diameter/contactor base diameter, Archimedes number, tangent of the angle, relative air velocity.