Effect of Fe²⁺ and Cu²⁺ Ions on the Electrochemical Behavior of Massive Chalcopyrite in Bioleaching System

Abstract

The electrochemical behavior of massive chalcopyrite in presence of Acidithiobacillus caldus, Acidithiobacillus ferrooxidans, Leptospirillum ferrooxidans and Sulfobacillus thermosulfidooxidans has been studied by cyclic voltammetry. The effect of Fe2+ and Cu2+ ion addition on the electrochemical behavior of massive chalcopyrite in bioleaching system were also investigated. The voltammograms illustrated that current densities of peaks were obviously increased with adding Fe2+ into the electrolyte. A series of anodic peaks were observed at more than 0 V when adding Fe2+ and Cu2+ ions, and these peaks are similar to the peaks of the step oxidation of chalcocite, thus proving that the formation of intermediate CuS2. Especially, the 9 g/L Fe2+ and 1.5 g/L Cu2+ were added. Therefore, appropriate ferrous and cupric ions concentration could enhance the formation of intermediate CuS2 leading to accelerate dissolution of chalcopyrite.

Flotation Separation of Chalcopyrite and Molybdenite Assisted by Microencapsulation Using Ferrous and Phosphate Ions: Part I. Selective Coating Formation

“…Figure 3 shows the cyclic voltammograms of chalcopyrite (Figure 3a) and molybdenite (Figure 3b) in the absence and presence of 1 mmol/L Fe 2+ . The current density was continuously increased as the applied potential increased, which means that chalcopyrite as well as its oxidation products (e.g., Fe 2+ ) were oxidized (Equations ( 1) and ( 2)), as shown in the first anodic scan of chalcopyrite in the absence of Fe 2+ (Figure 3(a2)) [30][31][32]. When 1 mmol/L Fe 2+ was present, the current density was apparently increased as compared to that without Fe 2+ .…”

“…Thus, the appearance of C 1 and C 2 can be explained by the reduction of Fe 3+ to Fe 2+ at 0.3-0.4 V (Equation ( 3)) and the formation of covellite (CuS) at 0.1-0.2 V (Equation ( 4)), respectively. At the applied potential between −0.4 and −0.7 V, two additional peaks (C 3 and C 4 ) were observed (Figure 3(a1)), which resulted from the reduction of CuS to chalcocite (Cu 2 S) and S 0 to H 2 S, as illustrated in Equations ( 5) and ( 6) [30][31][32].…”