The mechanism of copper-activation of sphalerite was studied at pH 9.2. The
study was conducted using a carbon matrix composite (CMC) electrode contai
ning sphalerite particles. Rest potential measurement and voltammetry exper
iments conducted on the CMC electrodes showed that a Cu2S-like activation p
roduct was formed when the electrode was activated in 10(-4) M CuSO4 soluti
ons at open circuit. When the electrode was activated at lower potentials,
a CuS-like activation product was formed. Sphalerite activated under slight
ly oxidizing conditions produced hydrophobic species on the surface, possib
ly copper polysulfides. (C) 2000 Elsevier Science B.V. All rights reserved.