In order to investigate the effect of Thiobacillusferrooxidans on the oxidation of pyrite, two parallel experiments, which employed H2SO4 solutions and acidic solutions inoculated with ThiobaciUus ferrooxidans, were d...In order to investigate the effect of Thiobacillusferrooxidans on the oxidation of pyrite, two parallel experiments, which employed H2SO4 solutions and acidic solutions inoculated with ThiobaciUus ferrooxidans, were designed and carried out at 30℃. The initial pH of the two solutions was adjusted to 2.5 by dropwise addition of concentrated sulphuric acid. The surfaces of pyrite before exposure to leaching solutions and after exposure to the H2SO4 solutions and acidic solutions inoculated with Thiobacillus ferrooxidans were observed by scanning electron microscopy （SEM）. There were a variety of erosion patterns by Thiobacillusferrooxidans on the bio-leached pyrite surfaces. A conclusion can be drawn that the oxidation of pyrite might have been caused by erosion of the surfaces. Attachment of the bacteria to pyrite surfaces resulted in erosion pits, leading to the oxidation of pyrite. It is possible that the direct mechanism plays the most important role in the oxidation of pyrite. The changes in iron ion concentrations of both the experimental solutions with time suggest that ThiobaciUus ferrooxidans can enhance greatly the oxidation of pyrite.展开更多
To determine the efficacy of chalcopyrite bioleaching using pure cultures of Thiobacillus ferrooxidans or Thiobacillus thiooxidans and a mixed culture composed of Thiobacillus ferrooxidans and Thiobacillus thiooxidans...To determine the efficacy of chalcopyrite bioleaching using pure cultures of Thiobacillus ferrooxidans or Thiobacillus thiooxidans and a mixed culture composed of Thiobacillus ferrooxidans and Thiobacillus thiooxidans, experiments were carried out in shake flasks with [Fe^2＋] 4 g·L^-1 and S 1 g·L^-1 at pH=1.80, 130 r/min and 30℃. The tests showed that the copper extraction in a mixed culture composed of Thiobacillusferrooxidans and Thiobacillus thiooxidans is higher than that in a pure culture. On the other hand, an important potential of Thiobacillus thiooxidans to leaching chalcopyrite was indicated. Thiobacillus thiooxidans can prevent jarosites accumulating on the substrate and allow further copper to dissolute through the action of ferric ion. The selection of the suitable pH in a leaching solution would be significant. Thiobacillus thiooxidans and Thiobacillus ferrooxidans play an important role in the bioleaching process. Finally, the mechanism and the reason for iron precipitation were also discussed in detail.展开更多
A desulfurization strain that belongs to the thermophilic alkaline desulphuricant is designated as strain GDJ-3 and isolated from Inner Mongolia, China. The colony of the strain shows tiny, yellow, or white-yellow, an...A desulfurization strain that belongs to the thermophilic alkaline desulphuricant is designated as strain GDJ-3 and isolated from Inner Mongolia, China. The colony of the strain shows tiny, yellow, or white-yellow, and it becomes henna with the protracting of cultivated time. The cells are bacilliform (0.3?0.6 × 1.0?1.2 μm), motive, and Gram negative. The strain GDJ-3 is able to utilize respectively the thiosulphate, sulfate, sulfite, or sulfide as sulfur source, utilize the carbon dioxide as the carbon source, and utilize the ammonium or nitrate as the nitrogen source. According to GenBank data, 16s RNA results of GDJ-3 are in good agreement with Alpha proteobacterrium sp. (97%) and Ochrobactrum sp. (98%). For GDJ-3, the optimum growth temperature is at 45°C, the optimum pH is at 8.5–8.8, and the optimum rocking speed of sorting table is at 150 r/min. Under the optimum culture condition, the cells of the strain can live for about 18 h. In the desulfurization solution, which is prepared according to the composition of DDS solution, the objectionable constituents of sodium thiosulphate and sodium sulfide were added factitiously, and the bacterial cell concentration was set at 107/mL. After the regeneration of the above desulfurization solution by the strain cells, the concentration of sodium thiosulphate was decreased by 14.75 g/L (percentage loss of content 13.21%), the concentration of sodium sulfide was decreased by 0.76 g/L (percentage loss of content 87.36%) in the desulfurization solution in 9.5 hours, and sulfur appeared. Maybe, this kind of strain can be used as the regeneration’s bacterial source of DDS solution.展开更多
Thiobacillus denitrificans, a kind of autotrophic facultative bacteria, can oxidize sulfide into elemental sulfur or sulfate when nitrate was adopted as its electron accepter and carbon dioxide as its carbon resource ...Thiobacillus denitrificans, a kind of autotrophic facultative bacteria, can oxidize sulfide into elemental sulfur or sulfate when nitrate was adopted as its electron accepter and carbon dioxide as its carbon resource under anoxic or anaerobic environment. In this way, nitrate is converted into nitrogen. In addition, ThiobaciWus denitrificans can accumulate sulfur extracellularly. In this study, in a process of simultaneous desulfurization and denitrification, a strain of Thiobacillus denitriificans is employed as sulfur-producer in the treatment of wastewater containing sulfide and nitrate. The key factors affecting this process are investigated through batch tests. The experimental results indicate that the sulfide concentration and the ratio of sulfide to nitrate (S2-/NO3-) in the influent are the key factors, and their suitable values are suggested to be 5/3 and no more than 300mg·L-1, respectively, in order to achieve high conversion of sulfur.展开更多
The variation of main parameters including ion concentration, pH value, potential and biomass was examined in bioleaching pyrite. The pH value of the solution decreased obviously. Most of T.ferrooxidans adhered to the...The variation of main parameters including ion concentration, pH value, potential and biomass was examined in bioleaching pyrite. The pH value of the solution decreased obviously. Most of T.ferrooxidans adhered to the surface of pyrite. The surface properties of pyrite and leached products were determined by SEM, EDS and XRD. Pyrite was corroded selectively by T.ferrooxidans and sulfur in pyrite was leached preferentially. The primary product for bioleaching pyrite was jarosite. Based on these results, it can be found that pyrite is oxidized mainly through the direct role of T.ferrooxidans . A band model for bioleaching pyrite was built, by which the bioleaching process was explained theoretically. The model shows that the holes, which are injected into the valence band of pyrite through adhered T.ferrooxidans , result from dissolved oxygen in the solution.展开更多
Besides the physical and chemical machining methods, a biological machining method has been presented. The experimental results show that machining of pure iron, pure copper and constantan by a special bacterium, Thio...Besides the physical and chemical machining methods, a biological machining method has been presented. The experimental results show that machining of pure iron, pure copper and constantan by a special bacterium, Thiobacillus ferrooxidans , was possible. A micro gear and grooves on pure copper piece were bio machined. The depth of the groove so bio machined was directly dependent on the machining time. The biomachining mechanism has been analyzed from the electron transport chain (ETC) in the T. ferrooxidans membrane, and its developing direction has been also discussed.展开更多
Thiobacillus ferrooxidans might be the most important bacteria used in biometallurgy. The foundation way of its growth process is oxidizing ferrous in order to obtain energy needed for metabolism, but the variation of...Thiobacillus ferrooxidans might be the most important bacteria used in biometallurgy. The foundation way of its growth process is oxidizing ferrous in order to obtain energy needed for metabolism, but the variation of ferrous concentration and mixed potential of the culture media would have crucial effect on the bacteria growth. Based on the characteristics of Thiobacillus ferrooxidans growth and redox potential of ferric and ferrous, an electrochemical cell was designed conventionally to study growth rule and the relationship between redox potential and bacteria growth was built up, and some growth kinetics of Thiobacillus ferrooxidans were elucidated. It demonstrates that the variation of open potential of electrochemical cell Δ E shows the growth tendency of Thiobacillus ferrooxidans , at the initial growth stage, the value of Δ E increases slowly, when at logistic growth stage, it increases drastically, and the growth rate of bacteria is linear with the oxidation rate of ferrous. The bacteria growth kinetics model is proposed using Monod and Michealis-Menten equation, and the kinetics parameters are got. The consistence of the measured and the calculated results proves that it is proper to use the proposed kinetics model and the electrochemical cell method to describe the growth rule of Thiobacillus ferrooxidans .展开更多
The bioleaching of a low grade Ni Cu sulfide ore from Jinchuan Mine with Thiobacillus ferrooxidans (TF5) and Thiobacillus thiooxidans (TT) was investigated. The effect of pH, the initial cell numbers of bacteria, the ...The bioleaching of a low grade Ni Cu sulfide ore from Jinchuan Mine with Thiobacillus ferrooxidans (TF5) and Thiobacillus thiooxidans (TT) was investigated. The effect of pH, the initial cell numbers of bacteria, the pulp density and the ratio of TF5 and TT on leaching was described, and the favorable bioleaching conditions for the ore were experimentally confirmed. The aeration leaching, agitation leaching with air bubbling, and column leaching were respectively tested. The highest recovery was achieved in the aeration leaching. After leaching for 20?d with pulp density of 15%, the extractions of Ni, Cu and Co were respectively 95.4%, 48.6% and 82.6%.展开更多
基金supported by the National Natural Science Foundation of China(grant 40573001)the Specialized Research Fund for the Doctoral Program of Higher Education(No.20050284043 and No.20050284044).
文摘In order to investigate the effect of Thiobacillusferrooxidans on the oxidation of pyrite, two parallel experiments, which employed H2SO4 solutions and acidic solutions inoculated with ThiobaciUus ferrooxidans, were designed and carried out at 30℃. The initial pH of the two solutions was adjusted to 2.5 by dropwise addition of concentrated sulphuric acid. The surfaces of pyrite before exposure to leaching solutions and after exposure to the H2SO4 solutions and acidic solutions inoculated with Thiobacillus ferrooxidans were observed by scanning electron microscopy （SEM）. There were a variety of erosion patterns by Thiobacillusferrooxidans on the bio-leached pyrite surfaces. A conclusion can be drawn that the oxidation of pyrite might have been caused by erosion of the surfaces. Attachment of the bacteria to pyrite surfaces resulted in erosion pits, leading to the oxidation of pyrite. It is possible that the direct mechanism plays the most important role in the oxidation of pyrite. The changes in iron ion concentrations of both the experimental solutions with time suggest that ThiobaciUus ferrooxidans can enhance greatly the oxidation of pyrite.
文摘To determine the efficacy of chalcopyrite bioleaching using pure cultures of Thiobacillus ferrooxidans or Thiobacillus thiooxidans and a mixed culture composed of Thiobacillus ferrooxidans and Thiobacillus thiooxidans, experiments were carried out in shake flasks with [Fe^2＋] 4 g·L^-1 and S 1 g·L^-1 at pH=1.80, 130 r/min and 30℃. The tests showed that the copper extraction in a mixed culture composed of Thiobacillusferrooxidans and Thiobacillus thiooxidans is higher than that in a pure culture. On the other hand, an important potential of Thiobacillus thiooxidans to leaching chalcopyrite was indicated. Thiobacillus thiooxidans can prevent jarosites accumulating on the substrate and allow further copper to dissolute through the action of ferric ion. The selection of the suitable pH in a leaching solution would be significant. Thiobacillus thiooxidans and Thiobacillus ferrooxidans play an important role in the bioleaching process. Finally, the mechanism and the reason for iron precipitation were also discussed in detail.
文摘A desulfurization strain that belongs to the thermophilic alkaline desulphuricant is designated as strain GDJ-3 and isolated from Inner Mongolia, China. The colony of the strain shows tiny, yellow, or white-yellow, and it becomes henna with the protracting of cultivated time. The cells are bacilliform (0.3?0.6 × 1.0?1.2 μm), motive, and Gram negative. The strain GDJ-3 is able to utilize respectively the thiosulphate, sulfate, sulfite, or sulfide as sulfur source, utilize the carbon dioxide as the carbon source, and utilize the ammonium or nitrate as the nitrogen source. According to GenBank data, 16s RNA results of GDJ-3 are in good agreement with Alpha proteobacterrium sp. (97%) and Ochrobactrum sp. (98%). For GDJ-3, the optimum growth temperature is at 45°C, the optimum pH is at 8.5–8.8, and the optimum rocking speed of sorting table is at 150 r/min. Under the optimum culture condition, the cells of the strain can live for about 18 h. In the desulfurization solution, which is prepared according to the composition of DDS solution, the objectionable constituents of sodium thiosulphate and sodium sulfide were added factitiously, and the bacterial cell concentration was set at 107/mL. After the regeneration of the above desulfurization solution by the strain cells, the concentration of sodium thiosulphate was decreased by 14.75 g/L (percentage loss of content 13.21%), the concentration of sodium sulfide was decreased by 0.76 g/L (percentage loss of content 87.36%) in the desulfurization solution in 9.5 hours, and sulfur appeared. Maybe, this kind of strain can be used as the regeneration’s bacterial source of DDS solution.
基金Supported by the National Natural Science Foundation of China (No. 50208006).
文摘Thiobacillus denitrificans, a kind of autotrophic facultative bacteria, can oxidize sulfide into elemental sulfur or sulfate when nitrate was adopted as its electron accepter and carbon dioxide as its carbon resource under anoxic or anaerobic environment. In this way, nitrate is converted into nitrogen. In addition, ThiobaciWus denitrificans can accumulate sulfur extracellularly. In this study, in a process of simultaneous desulfurization and denitrification, a strain of Thiobacillus denitriificans is employed as sulfur-producer in the treatment of wastewater containing sulfide and nitrate. The key factors affecting this process are investigated through batch tests. The experimental results indicate that the sulfide concentration and the ratio of sulfide to nitrate (S2-/NO3-) in the influent are the key factors, and their suitable values are suggested to be 5/3 and no more than 300mg·L-1, respectively, in order to achieve high conversion of sulfur.
文摘The variation of main parameters including ion concentration, pH value, potential and biomass was examined in bioleaching pyrite. The pH value of the solution decreased obviously. Most of T.ferrooxidans adhered to the surface of pyrite. The surface properties of pyrite and leached products were determined by SEM, EDS and XRD. Pyrite was corroded selectively by T.ferrooxidans and sulfur in pyrite was leached preferentially. The primary product for bioleaching pyrite was jarosite. Based on these results, it can be found that pyrite is oxidized mainly through the direct role of T.ferrooxidans . A band model for bioleaching pyrite was built, by which the bioleaching process was explained theoretically. The model shows that the holes, which are injected into the valence band of pyrite through adhered T.ferrooxidans , result from dissolved oxygen in the solution.
文摘Besides the physical and chemical machining methods, a biological machining method has been presented. The experimental results show that machining of pure iron, pure copper and constantan by a special bacterium, Thiobacillus ferrooxidans , was possible. A micro gear and grooves on pure copper piece were bio machined. The depth of the groove so bio machined was directly dependent on the machining time. The biomachining mechanism has been analyzed from the electron transport chain (ETC) in the T. ferrooxidans membrane, and its developing direction has been also discussed.
文摘Thiobacillus ferrooxidans might be the most important bacteria used in biometallurgy. The foundation way of its growth process is oxidizing ferrous in order to obtain energy needed for metabolism, but the variation of ferrous concentration and mixed potential of the culture media would have crucial effect on the bacteria growth. Based on the characteristics of Thiobacillus ferrooxidans growth and redox potential of ferric and ferrous, an electrochemical cell was designed conventionally to study growth rule and the relationship between redox potential and bacteria growth was built up, and some growth kinetics of Thiobacillus ferrooxidans were elucidated. It demonstrates that the variation of open potential of electrochemical cell Δ E shows the growth tendency of Thiobacillus ferrooxidans , at the initial growth stage, the value of Δ E increases slowly, when at logistic growth stage, it increases drastically, and the growth rate of bacteria is linear with the oxidation rate of ferrous. The bacteria growth kinetics model is proposed using Monod and Michealis-Menten equation, and the kinetics parameters are got. The consistence of the measured and the calculated results proves that it is proper to use the proposed kinetics model and the electrochemical cell method to describe the growth rule of Thiobacillus ferrooxidans .
文摘The bioleaching of a low grade Ni Cu sulfide ore from Jinchuan Mine with Thiobacillus ferrooxidans (TF5) and Thiobacillus thiooxidans (TT) was investigated. The effect of pH, the initial cell numbers of bacteria, the pulp density and the ratio of TF5 and TT on leaching was described, and the favorable bioleaching conditions for the ore were experimentally confirmed. The aeration leaching, agitation leaching with air bubbling, and column leaching were respectively tested. The highest recovery was achieved in the aeration leaching. After leaching for 20?d with pulp density of 15%, the extractions of Ni, Cu and Co were respectively 95.4%, 48.6% and 82.6%.
