Copper activation of sphalerite and its reaction with xanthate in relationto flotation: an X-ray absorption spectroscopy (reflection extended X-ray absorption fine structure) investigation

The technique of fluorescence REFLEXAFS was used to examine the activation by copper of sphalerite, ZnS, and the subsequent interaction with a xanthat e collector at pH 10 and 12. ZnSe was used as an isostructural analogue of ZnS to avoid the contribution from the xanthate S on the mineral surface be ing swamped by that from the substrate S. On activation, the copper interac tion with the Se or S atoms is clearly seen and Cu-O bonds are formed. On t he addition of xanthate, the oxygen is displaced by sulfur and a covellite- like species develops at the surface. The iron at the surface in natural sp halerites is bonded to oxygen, inhibiting initial copper activation but app ears to catalyse covellite formation on xanthate addition. The technique su cceeds in producing direct structural information, providing information co mplementary to other investigative techniques. (C) 1999 Elsevier Science B. V. All rights reserved.