The elutriation of fine powders from a fluidized bed of a fine-coarse particle mixture was investigated in a transparent column with a diameter of 7.1 cm and a height of 102 cm at superficial gas velocities from 0.3 to 0.9 m/s. In the experiments, a silica sand (group B particle) was used as the coarse particles, whereas several kinds of limestone powder varying in Geldart's classification from A to C were used as fines. The elutriation rate constant of the powders was obtained by measuring the elutriation rate of the powders for a concentration of the powders in the bed at a steady state. Experimental results showed that the elutriation rate constant of powders reaches a maximum at the critical powder diameter d(p)* corresponding approximately to the boundary between group A and C powders, giving an indication of the different elutriation mechanisms between group A and C powders. This finding further confirms the discovery in recent work, contrary to the assumptions implicit in existing correlations for the prediction of elutriation rates of group A and B particles, that changes in the elutriation rate may be attributed to the interparticle adhesion forces. A new empirical correlation for the elutriation rate constant of cohesive powders smaller than the critical powder diameter in a fluidized bed of a binary particle mixture is therefore proposed based on the experimental results by taking into account the powder cohesiveness. Moreover, a critical cohesion number N-coh* corresponding to the critical powder diameter was also obtained by which the critical powder diameter can be predicted.