Comparison of leaching of bornite from different regions mediated by mixed moderately thermophilic bacteria

Bioleaching experiments combined with X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM) were conducted to investigate three kinds of bornites from different regions leached by moderately thermophilic mixed bacteria of Leptospirillum ferriphilum YSK, Acidithiobacillus caldus D1 and Sulfobacillus thermosulfidooxidans ST. The results of bioleaching experiments showed that the leaching efficiency and the redox potential were significantly increased. The copper extraction efficiencies of three kinds of bornite maintained rapid growth until around the 12th day and no longer increased after the 18th reaching 83.7%, 96.5% and 86.6%, respectively. The XRD results of the leaching residue indicated that three kinds of bornites all produced jarosite in the late stage of leaching, and the leaching residues from of Daye Museum and Yunnan Geological Museum contained a mass of elemental sulfur. XPS analysis and scanning electron microscopy experiments showed that the surface of mineral particles was jarosite and the copper in the leaching residue was almost dissolved.