The recovery and grade of concentrates obtained by flotation is partly dependent upon froth structure. The flotation froth structure can be modified, and hence the flotation performance modified, by the addition of reagents. A direct control system was developed which permitted pre-determined addition profiles of reagent and water to-be added to a cell. A series of experiments were performed using different strategies of reagent (Triton x-405) addition. for the flotation of Bickershaw coal. A transputer enhanced Micro-Vax Computer was employed to grab images of flotation froths and to process them quantitatively in a parallel procedure. Using image processing techniques characterization of froth structures was achieved. The image processing procedures that were intended to run on-line, were examined and developed using video tapes of experimental runs, off-line. An essential stage in the development of such a system is the understanding of the adsorption behaviour of the reagent in terms of the kinetics, the distribution of reagent between the solid and solution-phases, and the resulting effect on the froth structure. A, kinetic model was developed to describe the adsorption of the reagent ion the particles. The experimental recoveries and froth. structure were investigated in terms of reagent distribution and the froth structure. (C) 2004 Elsevier Ltd. All rights reserved.