“…Theoretical studies on the effect of liquid film cohesive forces on SBDI and fluidized beds was conducted using the concepts of soil mechanics and mixture theory (Passos et al, 2000) and the agglomeration tensile strength theory (Spitzner Neto et al, 2001). The effect of paste presence on key spouting features like the minimum spouting velocity, maximum and spouting pressure drop has been studied using glycerol (Schneider and Bridgewater, 1993;Passos et al, 2000;Spitzner Neto et al, 2001), but also aqueous alumina suspension (Schneider and Bridgewater, 1993) as model pastes for batch operation and egg homogenate, animal blood, and xantham gum (Spitzner Neto et al, 2001) as models for continuous operation. In batch operation studies the SBDI were loaded with different saturation indexes, that is, volumetric ratios of paste model to inert bodies, and as saturation is increased the spouting pressure drop decreases (Schneider and Bridgewater, 1993;Passos et al, 2000;Spitzner Neto et al, 2001) but contradictory results were found for minimum spouting velocity (Schneider and Bridgewater, 1993;Passos et al, 2000;Spitzner Neto et al, 2001, 2002 which is supposed to depend on paste nature (Schneider and Bridgewater, 1993) and the type of bridges it forms between particles.…”