Une nouvelle approche pour la determination de la constante cinetique dans les colonnes de flottation

The flotation rate constant is a key parameter for column scale-up. Presently, it is experimentally determined from concentrate recovery values at various flotation times obtained by varying the tailings flowrate. This method induces changes in the column hydrodynamics which could alter the evaluation of the rate constant.;In this research, a new experimental method has been proposed and evaluated, whereby, the flotation time is varied by changing the collection zone height via a movable sparger system. Moreover, the use of the particle residence time was adopted as a standard in this experimental procedure, regardless of its more complex calculation procedure.;A second objective of this work was the introduction of the bubble concentration into the rate constant determination procedure. The flotation process has consistently been modeled through a first order kinetic model, only based on the hydrophobic particle concentration. To consider the bubble concentration, the second "reagent" of the flotation "reaction", the bubble surface area flux (Sb) concept was used.;Results showed that the proposed experimental procedure solves most of the problems associated to the current method of rate constant determination. It was demonstrated that the gas hold-up and the bubble size remain constant throughout the experimental work, i.e. for the various flotation times, which was not the case for the previous method.;A linear relationship between the rate constant and the Sb was found from the experimental results. This finding allows the calculation of a "true" rate constant independently of both bubble and particle concentration. This concept will allow for a more realistic scale-up of flotation column.