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Ngom B.,Central South University | Ngom B.,Key Laboratory of Biohydrometallurgy | Liang Y.,Central South University | Liang Y.,Key Laboratory of Biohydrometallurgy | And 2 more authors.
BioMed Research International | Year: 2014

A cross-comparison of six strains isolated from two different regions, Chambishi copper mine (Zambia, Africa) and Dexing copper mine (China, Asia), was conducted to study the leaching efficiency of low grade copper ores. The strains belong to the three major species often encountered in bioleaching of copper sulfide ores under mesophilic conditions: Acidithiobacillus ferrooxidans, Acidithiobacillus thiooxidans, and Leptospirillum ferriphilum. Prior to their study in bioleaching, the different strains were characterized and compared at physiological level. The results revealed that, except for copper tolerance, strains within species presented almost similar physiological traits with slight advantages of Chambishi strains. However, in terms of leaching efficiency, native strains always achieved higher cell density and greater iron and copper extraction rates than the foreign microorganisms. In addition, microbial community analysis revealed that the different mixed cultures shared almost the same profile, and At. ferrooxidans strains always outcompeted the other strains. © 2014 Baba Ngom et al. Source


Li S.,Central South University | Li S.,Key Laboratory of Biohydrometallurgy | Zhong H.,Central South University | Hu Y.,Central South University | And 5 more authors.
Bioresource Technology | Year: 2014

This study investigated thermophilic bioleaching of a low grade nickel-copper sulfide using mixture of four acidophilic thermophiles. Effects of 0.2. g/L l-cysteine on the bioleaching process were further evaluated. It aimed at offering new alternatives for enhancing metal recoveries from nickel-copper sulfide. Results showed a recovery of 80.4% nickel and 68.2% copper in 16-day bioleaching without l-cysteine; while 83.7% nickel and 81.4% copper were recovered in the presence of l-cysteine. Moreover, nickel recovery was always higher than copper recovery. l-Cysteine was found contributing to lower pH value, faster microbial growth, higher Oxidation-Reduction Potential (ORP), higher zeta potential and absorbing on the sulfide surfaces through amino, carboxyl and sulfhydryl groups. X-ray Diffraction (XRD) patterns of leached residues showed generation of S, jarosite and ammoniojarosite. Denaturing Gradient Gel Electrophoresis (DGGE) results revealed that l-cysteine could have variant impacts on different microorganisms and changed the microbial community composition dramatically during nickel-copper sulfide bioleaching. © 2013 Elsevier Ltd. Source


Zhou S.,Central South University | Zhou S.,Key Laboratory of Biohydrometallurgy | Gan M.,Central South University | Gan M.,Key Laboratory of Biohydrometallurgy | And 11 more authors.
Bioresource Technology | Year: 2015

The influence of visible light exposure on chalcopyrite bioleaching was investigated using Acidithiobacillus ferrooxidans. The results indicated, in both shake-flasks and aerated reactors with 8500-lux light, the dissolved Cu was 91.80% and 23.71% higher, respectively, than that in the controls without light. The catalytic effect was found to increase bioleaching to a certain limit, then plateaued as the initial chalcopyrite concentration increased from 2% to 4.5%. Thus a balanced mineral concentration is highly amenable to bioleaching via offering increased available active sites for light adsorption while eschewing mineral aggregation and screening effects. Using semiconducting chalcopyrite, the light facilitated the reduction of Fe3+ to Fe2+ as metabolic substrates for A. ferrooxidans, leading to better biomass, lower pH and redox potential, which are conducive to chalcopyrite leaching. The light exposure on iron redox cycling was further confirmed by chemical leaching tests using Fe3+, which exhibited higher Fe2+ levels in the light-induced system. © 2015 Elsevier Ltd. Source


Wang J.,Key Laboratory of Biohydrometallurgy | Wang J.,Central South University | Zhao H.-B.,Key Laboratory of Biohydrometallurgy | Zhao H.-B.,Central South University | And 4 more authors.
Journal of Central South University | Year: 2014

Bacterial leaching of single sulfide minerals and polymetallic sulfide ores was operated in shake flasks and small-scaled columns. The results show that bioleaching of jamesonite is not accessible, the iron extraction rate of pyrrhotite bioleaching reaches 98.2% after 26 d, and the zinc extraction rate of marmatite bioleaching reaches 92.3%, while the corresponding iron extraction reaches only 13.6% after 29 d. Pulp density has a significant effect on metal extraction of pyrrhotite and marmatite bioleaching. The corresponding metal extraction rate decreases with the increase of pulp density. For the polymetallic sulfide ores, zinc extraction of 97.1% is achieved after bioleaching in shake flasks for 10 d, while only 7.8% is obtained after bioleaching in small-scaled column. Analytical results of scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX) reveal that large amount of calcium sulfate is formed on the mineral surface. © 2014 Central South University Press and Springer-Verlag Berlin Heidelberg. Source


Qiu G.,Key Laboratory of Biohydrometallurgy | Liu X.,Key Laboratory of Biohydrometallurgy | Shen L.,Key Laboratory of Biohydrometallurgy | Zeng W.,Key Laboratory of Biohydrometallurgy
26th International Mineral Processing Congress, IMPC 2012: Innovative Processing for Sustainable Growth - Conference Proceedings | Year: 2012

The status of utilization of copper ore resources, and the application and development of biohydrometallury technology in the world is reviewed. Based on the characterization of Zambia's copper resources, biohydrometallurgy technology is shown to be a practical approach to extract and utilize the enormous low grade copper resource, such as ore tailings and low grade copper ore in this country. Through the cooperation of CSU, China and MMMD, Zambia, "CNMC-CSU Demonstration Base of Biohydrometallurgy Technology in Zambia" was launched and several biohydrometallurgy plants are being constructed. This indicates that the biohdyrometallurgy technology would be applied soon in Zambia and in the whole Africa. Biohydrometallurgy technology stands as an efficient alternative to the traditional pyrometallurgy process and it can be the key to unlock mineral resources value. Source

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