The collection zone recovery of a flotation column was modeled using a rectangular distribution function for the kinetic rate constant and a tank in series model with different vessel sizes for the residence time distribution. It was demonstrated that an analytical expression can be obtained and that data from large industrial columns fits well, keeping the parsimony principle by using a simple and practical solution. An example for the estimation of the maximum kinetic rate constant, useful for sale-up purposes, is shown using data from industrial flotation columns. (c) 2005 Elsevier Ltd. All rights reserved.