Cohesive systems have been largely investigated; however, the capability to predict their characteristics is still limited. A cohesive powder (air pollution control residue, or fly ash) from waste incineration could potentially be treated in a fluid bed unit. The capacity to fluidize this powder with a second fluidizable solid is assessed and the possibility to describe the system with a model is evaluated. A generalized Richardson and Zaki correlation is tested. The form of the correlation is seen to be still valid but with lower values of the exponential index. The experimentation conducted in this work needs to be extended to substantiate preliminary findings and a research path to develop the work further is proposed.