Microbial synergy and stoichiometry in heap biooxidation of low-grade porphyry arsenic-bearing gold ore

Corrosion Characteristics of Typical Gangue Minerals in Biometallurgical Systems

Electrochemical and shake flask tests were used to examine the corrosion characteristics of typical gangue minerals in biometallurgical systems and their impact on microbial communities. The results show that the solubility order of the three gangue minerals is feldspar, mica, and quartz in descending order. Their corrosion processes are mainly controlled by cathodic electron-donating processes. They are subjected to triple resistance, which is defined as solution-resistant, colloidal silica passivation, and iron precipitation (ferric hydroxide or jarosite passivation). Fe3+ and microorganisms both greatly improve the corrosion capacity of the system for the three gangue minerals. The community diversity may rise to 9.3, 8.6, and 4.4 times that of the initial HQ0211 strain, respectively, in the presence of feldspar, mica, and quartz.. The proportions of autotrophic microorganisms Leptospirillum, Sulfobacillus, and Acidiplasma decreased significantly, and the mixed trophic archaeon Ferroplasma and heterotrophic archaeon Cuniculiplasma became the dominant microorganisms in the system. Finally, the dissolution mechanism of gangue minerals in biometallurgical systems is discussed. The results enrich the theory of the gangue mineral corrosion process, which can lay a foundation for the effective regulation of biometallurgical processes.

Leaching of Chalcopyrite under Bacteria–Mineral Contact/Noncontact Leaching Model

Bacteria–mineral contact and noncontact leaching models coexist in the bioleaching process. In the present paper, dialysis bags were used to study the bioleaching process by separating the bacteria from the mineral, and the reasons for chalcopyrite surface passivation were discussed. The results show that the copper leaching efficiency of the bacteria–mineral contact model was higher than that of the bacteria–mineral noncontact model. Scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier-transform infrared (FTIR) were used to discover that the leaching process led to the formation of a sulfur film to inhibit the diffusion of reactive ions. In addition, the deposited jarosite on chalcopyrite surface was crystallized by the hydrolysis of the excess Fe3+ ions. The depositions passivated the chalcopyrite leaching process. The crystallized jarosite in the bacteria EPS layer belonged to bacteria–mineral contact leaching system, while that in the sulfur films belonged to the bacteria–mineral noncontact system.