Investigating the Flotation Behaviour of Chalcopyrite in the Presence of Sodium Sulphide under Controlled Electrochemical Pulp Potential

The flotation behavior of chalcopyrite in the presence of different concentration of sodium sulphide at pHs 7، 9 and 12 was investigated for both chalcopyrite single mineral and chalcopyrite flotation concentrate samples under controlled potential conditions. The surface analytical techniques of X-ray Photoelectron Spectroscopy (XPS) has provided information on the surface of chalcopyrite particles to identify surface species which are responsible for depression or flotation of chalcopyrite at different oxidation-reduction states of pulp. It was found that changes in pulp potential resulted in dual effects of sodium sulphide on flotation behavior of chalcopyrite. In other words، both flotation and depression of chalcopyrite could be achieved via controlling the pulp potentials. It was found that elemental sulphur and sulphoxy species resulted from electrochemical interactions between sodium sulphide and pulp contents and oxidation-reduction products of chalcopyrite، strongly affect the floatability of chalcopyrite. It was also found that maximum depression of chalcopyrite occurred at pH 12، Na2S concentrations about 10-1-10-2M and potential ranges between -200 mV to -100 mV (SHE). The optimum conditions for activation (sulphidisation) of chalcopyrite were found at pH 9، Na2S concentration about 10-3M and potential ranges between +300 mV to +400 mV (SHE).