Effect of pyrite on the electrochemical behavior of chalcopyrite at different potentials in pH 1.8 H₂SO₄

Abstract

Chalcopyrite is the most abundant, but also one of the most refractory, copper sources. One way to enhance chalcopyrite’s electrochemical dissolution is by mixing it with pyrite. To understand how and to what extent pyrite affects chalcopyrite’s electrochemical dissolution at different potentials, the electrochemical behaviors of chalcopyrite, pyrite, and chalcopyrite–pyrite couples in pH 1.8 H2SO4 were studied by potentiodynamic and electrochemical impedance spectroscopy. Potentiodynamic curves showed their different electrochemical reaction states and electrode surface characteristics. From open-circuit potential to 470 mV (vs saturated calomel electrode), chalcopyrite–pyrite was passivated with Cu1− xFe1− yS2 [Formula: see text]; from 470 to 580 mV, trans-passive dissolution occurred, and in the passive region, Cu1− xFe1− yS2 transformed into Cu1− x− zS2; from 580 to 700 mV was an active region; and a pseudo-passive region was formed with CuS when the potential was above 700 mV. The smaller charge transfer resistance and passive resistance, as well as the smaller inductive relaxation, revealed how and to what extent the coupled pyrite accelerated the electrochemical dissolution of chalcopyrite.

Enhanced Chalcopyrite Dissolution in Acidic Culture Medium: The Impact of Arsenopyrite Presence

“…Based on the linear relationship between reaction rate and current density, the galvanic coupling electrode promotes the cathodic reduction of chalcopyrite. The anodic oxidation process around ~600 mV of the galvanic couple represents possible reactions, as shown in Equations ( 26)-(28) [24], which reflect the release of Cu 2+ :…”

“…When two minerals exist simultaneously, owing to the difference in potential, a galvanic effect occurs, and the mineral with lower potential becomes the anode part, enhancing its oxidation ability and improving the kinetics of leaching [4,20,23]. In nature, pyrite is usually associated with chalcopyrite and exists in natural sulfide copper ores or flotation copper concentrates [24,25]. Therefore, one of the most studied galvanic interactions with chalcopyrite is the pyrite−chalcopyrite interaction.…”