A new relationship for the prediction of the apparent minimum fluidization velocity of polydisperse systems of scrap-wood particles is proposed. This method takes into account the relationship between the shape factor and the bed porosity with the minimum fluidization velocity. The equation proposed by Otero and Corella [A.R. Otero, J. Corella, An. Sec. Esp. Fis. Quim. 67 (1971) 1207.] has been generalized for mixtures with more than two components and then combined with the Ergun equation for the system under study. The hydrodynamic behavior observed for all types of particles corresponds to Geldart C-type powders. The nature of the particle has remarkable influence on such behavior.