One of the major problems in the flotation of fine particles is the decreased probability of collision between particles and bubbles, which can be improved by a reduction in bubble size. Additionally, smaller particles, having lower momentum, may not be able to break through the liquid barrier surrounding a bubble. in order to overcome this limitation, flotation exploiting electrostatic interactions has potential. Colloidal gas aphrons (CGAs) are charged microbubbles generated using a high speed impeller, typically of the size 50 mu m. In this work, CGAs generated using the anionic surfactant sodium dodecyl sulphate (SDS) have been used to separate copper oxide and silica powder (-10 mu m). By the manipulation of pH (therefore zeta potential), particles can be recovered by bubbles of opposite charge. Agglomeration between particles of different charge is a potential problem, however, initial results indicate a good separation using a novel system of froth recovery. (C) 2008 Elsevier Ltd. All rights reserved.