This paper gives a brief description of a fundamentally based model for the behaviour of a flotation froth. It includes descriptions for all three phases present in a flotation froth. The model for the gas motion uses either the simpler Laplace equation for describing the gas motion, or a more complex model for froths in very complex geometries or with very high flow rates. A methodology for predicting coalescence in a flowing foam or froth is included together with some theoretical forms for the coalescence frequency function. The liquid motion is predicted as the result of a force balance that includes gravity, viscosity and surface tension, acting by means of gradients in the curvature of the Plateau border interface. The solid motion model include the effects of liquid motion, particle settling and two types of dispersion, Plateau border and geometric. Lastly, the model is used to predict the performance of three different froth handling designs. The simulations compare the performance of each of these designs as the air rate into the cell is varied, and gives some experimental verification. (C) 2003 Elsevier B.V. All rights reserved.