An investigation into froth zone recovery in a controlled plant environment is presented. The effect of operating conditions on the froth performance is given in our previous work (Rahman et al., 2015). This paper is primarily concerned with the influence of chemical properties such as frother and collector concentration on the froth behaviour. The results suggested that increasing the collector concentration gave expected results in the collection (pulp) zone, with a significant increase in coarse particle recovery. However, at high collector concentrations, it was observed that there was an increase in bubble coalescence and froth instability as well as a slight decrease in froth recovery. Increasing frother concentration gave a significant improvement in froth recovery and a slight increase in the collection zone recovery was also found. This was attributed to the formation of finer, more stable, bubbles and a corresponding increase in froth stability. Size and grade analysis of the samples suggested that the dropback particles were mainly composite or middling fractions. It appeared that particles whose grade was higher than the feed may be collected into the froth zone, but some particles with grades lower than the concentrate may detach from the froth. (C) 2015 Elsevier Ltd. All rights reserved.