Portal de Periódicos da CAPES

Zeta potential study of the oxidation of copper sulfide minerals

1999; Elsevier BV; Volume: 146; Issue: 1-3 Linguagem: Inglês

10.1016/s0927-7757(98)00725-0

1873-4359

Damian Fullston, Daniel Fornasiero, John Ralston,

Extraction and Separation Processes

The zeta potential of the copper sulfide minerals, chalcocite, covellite, chalcopyrite, bornite, enargite and tennantite was measured as a function of pH and oxidising conditions. The changes in zeta potential observed in this study are consistent with the presence of a copper hydroxide layer covering a metal-deficient sulfur-rich surface and with the extent of this copper hydroxide coverage increasing with oxidation conditions. The existence of these surface species and their percentage were also confirmed by X-ray photoelectron spectroscopy. Analysis of the zeta potential data revealed that during the acid titration of the minerals, dissolution of the surface copper hydroxide layer occurs at pH values less than 8 while during the base titration, precipitation of copper hydroxide on the mineral surface is observed at pH values higher than 6. Hysteresis between the zeta potential acid and base titration curves was only observed in oxidising conditions and is attributed to the dissolution of the minerals at acidic pH values. The following ranking for the oxidation of these minerals is obtained: chalcocite>tennantite>enargite>bornite>covellite>chalcopyrite.