This work was aimed at modeling hydrodynamic characteristics of fluidization in conical beds using quartz sand as the inert bed material and air as the fluidizing agent. The minimum fluidization velocity, umf, and the minimum velocity of full fluidization, umff, were determined by Peng and Fan's models modified for conical fluidized bed. Meanwhile, the pressure drop across a bed, Δ p (including Δ pmax and Δ pmff corresponding to umf and umff, respectively), was predicted by using modified Ergun's equations for variable superficial air velocity at an air distributor, u0. The predicted results were validated by experimental data for some operating conditions. Effects of the sand particle size, cone angle and static bed height on the fluidization pattern and hydrodynamic characteristics are discussed. With the proposed models, the Δ p-u0 diagram were obtained with rather high accuracy for the conical air-sand beds of 30-45{ring operator} cone angles and 20-30 cm static bed heights, when using 300-1180 μ m sand particles. For the predicted umf and umff, the relative computational errors were found to be within 20% for wide ranges of operating variables, whereas Δ pmax and Δ pmff could be predicted with lower (10-15%) relative errors. With higher cone angles and/or bed heights, the computational accuracy was found to deteriorate. © 2007 Elsevier Ltd. All rights reserved.