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, u(mf), and the minimum velocity of full fluidization, u(mf f), were determined by Peng and Fan's models modified for conical fluidized bed. Meanwhile, the pressure drop across a bed, Delta p (including Delta(Pmax) and Delta(Pmf f) corresponding to u(mf) and u(mf f), respectively), was predicted by using modified Ergun's equations for variable superficial air velocity at an air distributor, u(0). 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 Delta p-u(0) diagram were obtained with rather high accuracy for the conical air-sand beds of 30-45 degrees cone angles and 20-30 cm static bed heights, when using 300-1180 mu m sand particles. For the predicted u(mf) and u(mf f), the relative computational errors were found to be within 20% for wide ranges of operating variables, whereas Delta(Pmax) and Delta(Pmf f) could be predicted with lower (10-15%) relative errors. With higher cone angles and/or bed heights, the computational accuracy was found to deteriorate. (C) 2007 Elsevier Ltd. All rights reserved.