Insights into the Surface Transformation and Electrochemical Dissolution Process of Bornite in Bioleaching

Abstract

In this work, density functional theory (DFT) calculations, X-ray photoelectron spectroscopy (XPS) and electrochemistry analysis were combined to analyze the electrochemical dissolution process of bornite during bioleaching. DFT calculations showed that bornite was a conductor with metallic conductivity. The formula of bornite may be (Cu +) 5 Fe 3+ (S 2−) 4 and the surface reconstruction of (111)-S surface was discussed. Electrochemistry and XPS analysis showed that bornite tended to be directly oxidized with high conductivity when the potential was higher than 0.3 V vs. Ag/AgCl. Elemental sulfur (S 0), FeOOH and CuS were the main intermediate species on the bornite surface during the oxidation process. The production of S 0 and FeOOH on bornite surface can be significantly accelerated with increased redox potential, but no insoluble sulfate (SO 4 2−) formed on bornite surface in 0.3-0.65 V vs. Ag/AgCl. The oxidative dissolution of bornite was significantly accelerated with increasing redox potential, which was one important reason why mixed culture was more effective than single strains of A. caldus and L. ferriphilum in bornite bioleaching. The insoluble SO 4 2− was formed mainly through the chemical reactions in solution and then covered the bornite surface in bioleaching. Based on the obtained results, a model for interpreting the dissolution process of bornite in bioleaching was proposed.

Intermediates Transformation of Bornite Bioleaching by Leptospirillum ferriphilum and Acidithiobacillus caldus

“…The Cu LMM peak of the ore is located at 569.2 eV (Figure 9b). On the 7th and 21st day, the Cu LMM peaks of the leached residues are located at 568.9 eV and 568.5 eV, respectively, which is also consistent with the binding energy value (568.5 eV) of the previously reported CuS LMM peak [20,38,39].…”

“…Yang et al [19] used XRD and XPS to characterize the intermediary species during bornite bioleaching by mixed moderately thermophilic culture, which suggested that bornite can be transformed into chalcocite, chalcopyrite, and covellite. Furthermore, Zhao [20] found that bornite tended to be directly oxidized to CuS, FeOOH, and S 0 on the surface in bioleaching by using moderately thermophilic culture.…”

Remarkable Electrical Conductivity Increase and Pure Metallic Properties from Semiconducting Colloidal Nanocrystals by Cation Exchange for Solution‐Processable Optoelectronic Applications

“…the electrical properties of the a‐NC‐A and a‐NC‐F films are presented in Figure S29, Supporting Information). We note that owing to the increase in S by a slight decrease in σ, which is due to the creation of less conductive iron oxide or iron oxide hydroxide by partial oxidation of NCs after storing in ambient condition, [ 99–102 ] the maximum PF and ZT of a‐NC‐C films improved over 1.2 mW m −1 K −2 and 0.042, respectively. Subsequently, we investigated the applicability of highly conductive a‐NC‐C films to conducting films.…”

Electrochemistry of Sulfides: Process and Environmental Aspects

“…In a recent article by Chinese researchers, based on the cyclic voltammetry and XPS data, it was shown that the oxidation of bornite proceeds intensively at a potential of more than 0.3 V relative to the silver-silver chloride reference electrode [50]. The main intermediate phases on the surface of bornite during oxidation are elemental sulfur, FeOOH, and CuS.…”