Minimum and full fluidization velocity for alumina used in the aluminum smelter

Abstract

Fluidization is an engineering unit operation that occurs when a fluid (liquid or gas) ascends through a bed of particles, and these particles get a velocity of minimum fluidization Vmf enough to stay in suspension, but without carrying them in the ascending flow. As from this moment the powder behaves as liquid at boiling point, hence the term "fluidization". This operation is widely used in the aluminum smelter processes, for gas dry scrubbing (mass transfer) and in a modern plant for continuous alumina pot feeding (particles' momentum transfer). The understanding of the alumina fluoride rheology is of vital importance in the design of fluidized beds for gas treatment and fluidized pipelines for pot feeding. This paper shows the results of the experimental and theoretical values of the minimum and full fluidization velocities for the alumina fluoride used to project the state of the art round non-metallic air-fluidized conveyor of multiples outlets.