The enhancement of chalcopyrite bioleaching with an enriched microbial community by acidified seawater was studied,and the enhancing mechanism was analyzed.The microbial community was enriched at the Dabaoshan mine si...The enhancement of chalcopyrite bioleaching with an enriched microbial community by acidified seawater was studied,and the enhancing mechanism was analyzed.The microbial community was enriched at the Dabaoshan mine site,and the treated ore sample had high concentrations of chalcopyrite and galena.The experimental results show that copper extraction from chalcopyrite with an enriched microbial community in seawater was promoted from 13.1%to 62.1%by acidification in comparison with that without acidification.Further analyses of the solutions,solid residues and microbial compositions by scanning electron microscopy,X-ray diffraction,Raman spectroscopy,Fourier transform infrared spectroscopy and 16 S rDNA sequencing revealed the promoting effects of acidified seawater.This acidification can increase the biodissolution of chalcopyrite to increase the concentration of iron ions and maintain the redox potential in the range of 360−410 mV.The latter produces an optimal redox environment conducive to chalcopyrite dissolution via Cu_(2)S.The adaptability of the microbial community to a high-salt environment is improved.Chloride ions at 580 mmol/L improve the leaching kinetics of chalcopyrite by increasing the porosity and noncrystallinity of the intermediate elemental sulfur.This study provides a promising way to bioleaching copper minerals using seawater for areas with freshwater shortages.展开更多
Mechanical activation (MA) is a significant pretreatment technique for enhancing the dissolution of mineral;however, its promotion effect on the role of pyrite during chalcopyrite bioleaching has not been elucidated u...Mechanical activation (MA) is a significant pretreatment technique for enhancing the dissolution of mineral;however, its promotion effect on the role of pyrite during chalcopyrite bioleaching has not been elucidated up to now. In this study, the effect of MA on the role of pyrite on chalcopyrite bioleaching mediated by Acidithiobacillus ferroxidans was investigated by X-ray diffraction, scanning electron microscopy, particle size distribution analysis, and electrochemical measurement. The results showed MA could significantly reduce the minerals particle size, and increase the specific surface area and surface energy of minerals. For example, the d50 of chalcopyrite reduced from 13.40 to 0.31 μm after MA. The copper extraction of mixed MA-chalcopyrite and MA-pyrite system was 63.4%, which exhibited a 51.8% enhancement compared to the non-activated mixed system. Electrochemical experiments identified that the strengthening effect of pyrite on chalcopyrite dissolution was negligible before MA. After MA, the dissolution mechanism of chalcopyrite was not changed, and pyrite could not only provide additional oxidants (acids and iron) but also act as the cathode in the galvanic couple. In this case, the bioleaching of chalcopyrite was accelerated. Therefore, a model of the promotion effect of mechanical activation on the role of pyrite on chalcopyrite bioleaching was proposed.展开更多
The changes of pH,redox potential,concentrations of soluble iron ions and Cu^2＋ with the time of bioleaching chalcopyrite concentrates by acidithiobacillus ferrooxidans were investigated under the different condition...The changes of pH,redox potential,concentrations of soluble iron ions and Cu^2＋ with the time of bioleaching chalcopyrite concentrates by acidithiobacillus ferrooxidans were investigated under the different conditions of initial total-iron amount as well as mole ratio of Fe（III） to Fe（II） in the solutions containing synthetic extracellular polymeric substances （EPS）.When the solution potential is lower than 650 mV （vs SHE）,the inhibition of jarosites to bioleaching chalcopyrite is not vital as EPS produced by bacteria can retard the contamination through flocculating jarosites even if concentration of Fe（III） ions is up to 20 g/L but increases with increasing the concentration of Fe（III） ions;jarosites formed by bio-oxidized Fe3＋ ions are more easy to adhere to outside surface of EPS space on chalcopyrite;the EPS layer with jarosites acts as a weak diffusion barrier to further rapidly create a high redox potential of more than 650 mV by bio-oxidizing Fe^2＋ ions inside and outside EPS space into Fe^3＋ ions,resulting in a rapid deterioration of ion diffusion performance of the EPS layer to inhibit bioleaching chalcopyrite severely and irreversibly.展开更多
The extracellular polymeric substances（EPS） of Acidithiobacillus ferrooxidans ATCC 23270,and iron and copper enclosed in EPS were extracted by ultrasonication and centrifugation methods to determine the interaction ...The extracellular polymeric substances（EPS） of Acidithiobacillus ferrooxidans ATCC 23270,and iron and copper enclosed in EPS were extracted by ultrasonication and centrifugation methods to determine the interaction mechanism of Cu2＋,Fe3＋ and EPS during bioleaching chalcopyrite.Generally,Cu2＋ ions can stimulate bacteria to produce more EPS than Fe3＋ ions.The mass ratio of Fe3＋/Cu2＋ enclosed in EPS decreased gradually from about 4：1 to about 2：1 when the concentration of Cu2＋ ions increased from 0.01 to 0.04 mol/L.The amount of iron and copper bound together by EPS in ferrous-free 9K medium containing 1% chalcopyrite was about 2 times of that in 9K medium containing 0.04 mol/L Cu2＋ ions.It was inferred that the EPS with jarosites on the surface of chalcopyrite gradually acted as a weak diffusion barrier for Cu2＋,Fe3＋ ions transference during bioleaching chalcopyrite.展开更多
The electrochemical oxidation behavior of pyrite in bioleaching system of Acidthiobacillusferrooxidans was investigated by cyclic voltammetry （CV）, polarization curve and electrochemical impedance spectroscopy （EIS...The electrochemical oxidation behavior of pyrite in bioleaching system of Acidthiobacillusferrooxidans was investigated by cyclic voltammetry （CV）, polarization curve and electrochemical impedance spectroscopy （EIS）. The results show that in the presence or absence of A. ferrooxidans, the oxidation reaction of pyrite is divided into two steps： the first reaction step involves the oxidation of pyrite to S, and the second reaction step is the oxidation of S to SO4^2-. The oxidation mechanism of pyrite is not changed in the presence of A. ferrooxidans, but the oxidation rate of pyrite is accelerated. With the extension of reaction time of A. ferrooxidan with pyrite, the polarization current density of pyrite increases and the breakdown potential at which the passive film dissolves decreases. The impedance in the presence ofA. ferrooxidans is obviously lower than that in the absence of A. ferrooxidans, further indicating that microorganism accelerates the corrosion process of pyrite.展开更多
Extracellular polymeric substances （EPS） produced by acidophilic bioleaching microorganisms play an important role in the production of acid mine drainage and metal sulfide bioleaching. EPS mediate the contact betwe...Extracellular polymeric substances （EPS） produced by acidophilic bioleaching microorganisms play an important role in the production of acid mine drainage and metal sulfide bioleaching. EPS mediate the contact between microbial cells and growth substrates, having a pivotal role in organic film formation and bacterium-substratum interactions. The production and chemical composition of EPS produced by seven bioleaching strains grown with different substrates were studied. Analysis of the EPS extracted from these strains indicated that the EPS consisted of carbohydrates, proteins and galacturonic acid. The contents of EPS, carbohydrates, proteins and galacturonic acid of EPS were largely related to the kind of strain used and culture condition. The results show that EPS productions of microbes grown with pyrite were significantly higher than those of microbes grown with sulfur or FeSO4·7H2O. The highest EPS production of the seven acidiphilic strains was （159.43±3.93） mg/g, which was produced by Leptospirillum ferriphilum CBCBSUCSU208015 when cultivated with pyrite.展开更多
Passivation is a common phenomenon on the surface of chalcopyrite in the process of bioleaching. The ordinary leaching and strengthening leaching by adding glass beads were carried out. The results show that the passi...Passivation is a common phenomenon on the surface of chalcopyrite in the process of bioleaching. The ordinary leaching and strengthening leaching by adding glass beads were carried out. The results show that the passivation of chalcopyrite was greatly weakened in strengthening leaching due to the change of leaching conditions. The copper leaching efficiency was increased from 50% to 89.8% through adding beads. The SEM and X-ray diffraction （XRD） analyses illustrate that there are few jarosite precipitates and weak passivation on the surface of chalcopyrite in strengthening leaching. In contrast, there are thick and compact jarosite precipitate and obvious passivation in ordinary leaching, which hinders further dissolution of chalcopyrite.展开更多
The variation of microbial community structure was investigated for the tank bioleaching process of Pb-Zn-Sn chalcopyrite concentrate in the presence of mixed moderately thermophilic bacteria. The parameters, such as ...The variation of microbial community structure was investigated for the tank bioleaching process of Pb-Zn-Sn chalcopyrite concentrate in the presence of mixed moderately thermophilic bacteria. The parameters, such as pH value, solution potential and concentrations of metal ions, were determined by the method of polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） to analyze the succession of microbial community. The results showed that a final copper extraction rate of 85.6% could be obtained after tank bioleaching for 30 d. The Acidithiobacillus caldus was the dominant population with abundance of about 73.80%in the initial stage, then Sulfobacillus thermosulfidooxidans dominated from the 18th day to the end of bioleaching, while the abundance of Leptospirillum ferriphilum changed slightly. A higher solution potential within a certain range and appropriate concentration of ferric ions were essential for this tank bioleaching of chalcopyrite.展开更多
The apparent sulfur oxidation activities of four pure thermophilic archaea, Acidianus brierleyi （JCM 8954）, Metallosphaera sedula （YN 23）, Acidianus manzaensis （YN 25） and Sulfolobus metallicus （YN 24） and the...The apparent sulfur oxidation activities of four pure thermophilic archaea, Acidianus brierleyi （JCM 8954）, Metallosphaera sedula （YN 23）, Acidianus manzaensis （YN 25） and Sulfolobus metallicus （YN 24） and their mixture in bioleaching chalcopyrite were compared, which were characterized indirectly by the evolution of the cells concentration, pH value and sulfate ions concentration in solution. The results show that the mixed culture contributed significantly to the raising of leaching rate, which suggests that the mixed culture had a higher sulfur oxidation activity than the pure culture. Meanwhile, the results also indicate that the changes of parameters characterizing the sulfur oxidation activity of thermophilic archaea are often influenced by many factors, so it is hard to reflect accurately the specific sulfur oxidation activities among the different sulfur-oxidizing microbes when bioleaching chalcopyrite at different conditions. Accordingly, an efficient method to characterize microbial sulfur oxidation activity appears to be desirable.展开更多
To screen the high efficient mixed culture and understand the bioleaching behaviors of mixed culture for low-grade copper sulfide ore bioleaching,ten mixed cultures were collected and screened from different acid mine...To screen the high efficient mixed culture and understand the bioleaching behaviors of mixed culture for low-grade copper sulfide ore bioleaching,ten mixed cultures were collected and screened from different acid mine drainages obtained from sulfide mines of China.The leaching rate was set as criterion to screen the mixed culture and the metagenomic approach.Community genome array（CGA） was used for analyzing the mixed culture microbial community shift during the bioleaching process.The results indicate that the mixed culture obtained from Yinshan（YS） lead-zinc mine in Dexing of Jiangxi province in China reaches the maximum copper extraction（68.89%） during the one bioleaching period of 24 d.CGA results show that YS culture contains nine kinds of bacteria which are belong to six divisions,and the microbial community structure is changing during the bioleaching process.This provides a good way to accelerate the bioleaching process and reveals the microbial community shift during the bioleaching process.展开更多
Effects of initial pH, temperature, liquid volume, rotation speed, galvanic interaction （pyrite ratio） and pulp density on bioleaching of complex Cu-polymetallic concentrate were investigated. The results indicated ...Effects of initial pH, temperature, liquid volume, rotation speed, galvanic interaction （pyrite ratio） and pulp density on bioleaching of complex Cu-polymetallic concentrate were investigated. The results indicated that the copper extraction at pH 1.5 was 1.5 and 1.4 times that at pH 1.0 and pH 2.0 respectively. The copper extraction obtained at 45 ℃ was 1236.8%higher than that at 50 ℃. With the increase of rotation speed or the decrease of liquid volume, copper extraction was improved obviously. Copper extraction was improved gradually with the increase of pyrite ratio. However, when the ratio was higher than 20.0%, no further increase in copper extraction was observed. And the statistically significant interactive effects on copper extraction were found between temperature and pH, and temperature and pyrite ratio.展开更多
The formation and evolution of secondary minerals during bioleaching of chalcopyrite by thermoacidophilic Archaea Acidianus manzaensis were analyzed by combining synchrotron radiation X-ray diffraction（SR-XRD） and S...The formation and evolution of secondary minerals during bioleaching of chalcopyrite by thermoacidophilic Archaea Acidianus manzaensis were analyzed by combining synchrotron radiation X-ray diffraction（SR-XRD） and S, Fe and Cu Kα X-ray absorption near edge structure（XANES） spectroscopy. Leaching experiment showed that 82.4% of Cu2＋ was dissolved by A. manzaensis after 10 d. The surface of chalcopyrite was corroded apparently and covered with leaching products. During bioleaching, the formation and evolution of secondary minerals were as follows： 1） little elemental sulfur, jarosite, bornite and chalcocite were found at days 2 and 4; and 2） bornite and chalcocite disappeared, covellite formed, and jarosite gradually became the main component at days 6 and 10. These results indicated that metal-deficiency sulfides chalcocite and bornite were first formed with a low redox potential value（360-461 m V）, and then gradually transformed to covellite with a high redox potential value（461-531 m V）.展开更多
X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses were carried out to investigate the surface species and interfacial reactions during bioleaching of chalcopyrite by different strains of ...X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses were carried out to investigate the surface species and interfacial reactions during bioleaching of chalcopyrite by different strains of moderately thermophilic bacteria （45 °C）. Results show that monosulfide （CuS）, disulfide （S22？）, polysulfide （Sn2？）, elemental sulfur （S0） and sulfate （SO42？） are the main intermediate species on the surface of chalcopyrite during bioleaching byA. caldus,S. thermosulfidooxidans andL. ferriphilum. The low kinetics of dissolution of chalcopyrite inA. caldus can be mainly attributed to the incomplete dissolution of chalcopyrite and the passivation layer of polysulfide. Polysulfide and jarosite should be mainly responsible for the passivation of chalcopyrite in bioleaching byL. ferriphilumorS. thermosulfidooxidans. However, elemental sulfur should not be the main composition of passivation layer of chalcopyrite during bioleaching.展开更多
Bioleaching Xiangjiang River alkaline sediment contaminated by multiple heavy metals was investigated. Multiple metals in alkaline sediment possess significant toxicity to aquatic organisms or humans and will greatly ...Bioleaching Xiangjiang River alkaline sediment contaminated by multiple heavy metals was investigated. Multiple metals in alkaline sediment possess significant toxicity to aquatic organisms or humans and will greatly inhibit bioleaching. The bioleaching method using autotrophic bacteria mixed with heterotrophic bacteria can solve this problem successfully. The experiment results showed that bioleaching efficiencies of Zn, Mn, Cu, and Cd were 95.2 %, 94.2 %, 90.1 %, and 84.4 %, respectively. Moreover, the changes of heavy metal concentrations in different fractions in contaminated sediment before and after bioleaching were analyzed by selective sequential extraction, and it was discovered that the main fractions of Zn, Mn, Cu and Cd after bioleaching are Fe-Mn oxide, organic associated form and a residual form. Its biotoxicity decreased greatly. The bioleaching heavy metals from sediment using autotrophic bacteria combined with heterotrophic bacteria can effectively improve the bioleaching efficiency and reduce toxicity.展开更多
The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied....The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied. The results show that the extraction rates of Fe, Cu and Zn from the slag reach 86.7%, 90.3% and 66.7% after adsorbed bacteria sterilize, while those with adsorbed bacteria are 91.9%, 96.0% and 84.5% in conditions of pulp density 2%, pH 1.0, temperature 65 °C and stirring rate 120 r/min, respectively. Some stretching peaks of functional groups from bacterial secretes on the bioleached residue surface, such as 1007 cm-1 and 1193 cm-1, turn up through FI-IR analysis and indirectly reveal the presence of the adsorbed bacteria on the slag particles surface. Besides, the corrosion of zinc smelting slag is enhanced by bacteria according to the characteristics of cyclic voltametry and Tafel curves in bioleaching system.展开更多
The function of microorganism and dissolution reaction pathway of carrollite in the bioleaching process were investigated. The results showed that both indirect and contact mechanisms influenced the leaching process. ...The function of microorganism and dissolution reaction pathway of carrollite in the bioleaching process were investigated. The results showed that both indirect and contact mechanisms influenced the leaching process. The dissolution of carrollite was significantly accelerated when bacteria were adsorbed on the mineral surface, indicating that the contact mechanism significantly affected the dissolution of carrollite. During bioleaching, the sequence of oxidation state of the sulfur moiety of carrollite was as follows： S？2→S0→S＋4→S＋6. Elemental sulfur precipitated on the mineral surface, indicating that the dissolution of carrollite occurred via the polysulfide pathway. The surface of carrollite was selectively corroded by bacteria, and oxidation pits with different sizes were observed at various sites. Elemental sulfur, sulfate and sulfite were present on the surface of carrollite during the leaching process, and may have formed a passivation layer on mineral surface.展开更多
Leptospirillum ferriphilum YXW was isolated through serial dilution from mixed microorganisms enriched in AMD from Dexing copper mine in Jiangxi Province, China. It was mutated by ultrasonic, UV and microwave to colle...Leptospirillum ferriphilum YXW was isolated through serial dilution from mixed microorganisms enriched in AMD from Dexing copper mine in Jiangxi Province, China. It was mutated by ultrasonic, UV and microwave to collect more efficient strain for bioleaching of gold ore. Physiological and biochemical characteristics indicate that strain YXW is a strict chemoautotrophic microorganism, and the optimal condition for its growth is temperature of 40 °C and pH 1.5. After mutation by ultrasonic, UV and microwave, the density of bacterial cells reached 9×109, 8.4×109 and 4.3×108 mL-1, increased by 291%, 265%and 87%, respectively, compared with the original culture. The bacterial total protein activity was improved by microwave and UV mutations, but was reduced by ultrasonic. Mutations had effects on bioleaching of gold ore in sequence of microwave〉UV〉ultrasonic. During gold ore bioleaching, the bacterial mutant after mutation by microwave had the best effect on the extraction rates of arsenic and iron, which were 19.6%and 17.7%higher than that of the original strain after bioleaching for 10 d, respectively. The results suggested that the effects of mutation on bioleaching of gold ore may not be mainly due to increase of bacterial cells density, but may be mainly attributed to the improvement of bacterial total protein activity.展开更多
The effect of pH values on the extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans was comparatively investigated in different phases of bacterial growth during chalcopyrite bioleachi...The effect of pH values on the extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans was comparatively investigated in different phases of bacterial growth during chalcopyrite bioleaching. The results indicate that the extracellular protein is always more than the extracellular polysaccharide secreted by attached cells on the chalcopyrite, on the contrary, and is always less than the extracellular polysaccharide secreted by free cells in the solution at bacterial adaptive phase, logarithmic phase and stationary phase whenever pH value is at 1.0, 1.5, 2.0 or 2.5; free cells are mainly through the secretion of extracellular polysaccharide rather than the extracellular protein to fight against disadvantageous solution environment, such as high concentration of metal ions and unsuitable pH solution; both amounts of polysaccharide and protein secreted by attached cells are mainly positively related to the solution acidity rather than the total concentration of soluble metal ions. The experimental results imply that bacteria are mainly through secreting more extracellular polysaccharide to fight against disadvantageous environment and the extracellular protein perhaps plays an important role in oxidation？reduction reactions in the bioleaching system.展开更多
基金Project(2022YFC2105300)supported by the National Key Research and Development Program of ChinaProjects(41802038,51774342)supported by the National Natural Science Foundation of China。
文摘The enhancement of chalcopyrite bioleaching with an enriched microbial community by acidified seawater was studied,and the enhancing mechanism was analyzed.The microbial community was enriched at the Dabaoshan mine site,and the treated ore sample had high concentrations of chalcopyrite and galena.The experimental results show that copper extraction from chalcopyrite with an enriched microbial community in seawater was promoted from 13.1%to 62.1%by acidification in comparison with that without acidification.Further analyses of the solutions,solid residues and microbial compositions by scanning electron microscopy,X-ray diffraction,Raman spectroscopy,Fourier transform infrared spectroscopy and 16 S rDNA sequencing revealed the promoting effects of acidified seawater.This acidification can increase the biodissolution of chalcopyrite to increase the concentration of iron ions and maintain the redox potential in the range of 360−410 mV.The latter produces an optimal redox environment conducive to chalcopyrite dissolution via Cu_(2)S.The adaptability of the microbial community to a high-salt environment is improved.Chloride ions at 580 mmol/L improve the leaching kinetics of chalcopyrite by increasing the porosity and noncrystallinity of the intermediate elemental sulfur.This study provides a promising way to bioleaching copper minerals using seawater for areas with freshwater shortages.
基金Project(GZC20233199) supported by the Postdoctoral Fellowship Program of CPSF,ChinaProject(2022YFC2105300) supported by the National Key Research and Development Program of China。
文摘Mechanical activation (MA) is a significant pretreatment technique for enhancing the dissolution of mineral;however, its promotion effect on the role of pyrite during chalcopyrite bioleaching has not been elucidated up to now. In this study, the effect of MA on the role of pyrite on chalcopyrite bioleaching mediated by Acidithiobacillus ferroxidans was investigated by X-ray diffraction, scanning electron microscopy, particle size distribution analysis, and electrochemical measurement. The results showed MA could significantly reduce the minerals particle size, and increase the specific surface area and surface energy of minerals. For example, the d50 of chalcopyrite reduced from 13.40 to 0.31 μm after MA. The copper extraction of mixed MA-chalcopyrite and MA-pyrite system was 63.4%, which exhibited a 51.8% enhancement compared to the non-activated mixed system. Electrochemical experiments identified that the strengthening effect of pyrite on chalcopyrite dissolution was negligible before MA. After MA, the dissolution mechanism of chalcopyrite was not changed, and pyrite could not only provide additional oxidants (acids and iron) but also act as the cathode in the galvanic couple. In this case, the bioleaching of chalcopyrite was accelerated. Therefore, a model of the promotion effect of mechanical activation on the role of pyrite on chalcopyrite bioleaching was proposed.
基金Project(2010CB630904) supported by the National Basic Research Program of ChinaProject(50621063) supported by the Chinese Science Foundation for Distinguished Group
文摘The changes of pH,redox potential,concentrations of soluble iron ions and Cu^2＋ with the time of bioleaching chalcopyrite concentrates by acidithiobacillus ferrooxidans were investigated under the different conditions of initial total-iron amount as well as mole ratio of Fe（III） to Fe（II） in the solutions containing synthetic extracellular polymeric substances （EPS）.When the solution potential is lower than 650 mV （vs SHE）,the inhibition of jarosites to bioleaching chalcopyrite is not vital as EPS produced by bacteria can retard the contamination through flocculating jarosites even if concentration of Fe（III） ions is up to 20 g/L but increases with increasing the concentration of Fe（III） ions;jarosites formed by bio-oxidized Fe3＋ ions are more easy to adhere to outside surface of EPS space on chalcopyrite;the EPS layer with jarosites acts as a weak diffusion barrier to further rapidly create a high redox potential of more than 650 mV by bio-oxidizing Fe^2＋ ions inside and outside EPS space into Fe^3＋ ions,resulting in a rapid deterioration of ion diffusion performance of the EPS layer to inhibit bioleaching chalcopyrite severely and irreversibly.
基金Project(50621063) supported by the National Natural Science Foundation of ChinaProject(2010CB630903) supported by the National Basic Research Program of China
文摘The extracellular polymeric substances（EPS） of Acidithiobacillus ferrooxidans ATCC 23270,and iron and copper enclosed in EPS were extracted by ultrasonication and centrifugation methods to determine the interaction mechanism of Cu2＋,Fe3＋ and EPS during bioleaching chalcopyrite.Generally,Cu2＋ ions can stimulate bacteria to produce more EPS than Fe3＋ ions.The mass ratio of Fe3＋/Cu2＋ enclosed in EPS decreased gradually from about 4：1 to about 2：1 when the concentration of Cu2＋ ions increased from 0.01 to 0.04 mol/L.The amount of iron and copper bound together by EPS in ferrous-free 9K medium containing 1% chalcopyrite was about 2 times of that in 9K medium containing 0.04 mol/L Cu2＋ ions.It was inferred that the EPS with jarosites on the surface of chalcopyrite gradually acted as a weak diffusion barrier for Cu2＋,Fe3＋ ions transference during bioleaching chalcopyrite.
基金Project (2010CB630903) supported by the National Basic Research Program of China
文摘The electrochemical oxidation behavior of pyrite in bioleaching system of Acidthiobacillusferrooxidans was investigated by cyclic voltammetry （CV）, polarization curve and electrochemical impedance spectroscopy （EIS）. The results show that in the presence or absence of A. ferrooxidans, the oxidation reaction of pyrite is divided into two steps： the first reaction step involves the oxidation of pyrite to S, and the second reaction step is the oxidation of S to SO4^2-. The oxidation mechanism of pyrite is not changed in the presence of A. ferrooxidans, but the oxidation rate of pyrite is accelerated. With the extension of reaction time of A. ferrooxidan with pyrite, the polarization current density of pyrite increases and the breakdown potential at which the passive film dissolves decreases. The impedance in the presence ofA. ferrooxidans is obviously lower than that in the absence of A. ferrooxidans, further indicating that microorganism accelerates the corrosion process of pyrite.
文摘Extracellular polymeric substances （EPS） produced by acidophilic bioleaching microorganisms play an important role in the production of acid mine drainage and metal sulfide bioleaching. EPS mediate the contact between microbial cells and growth substrates, having a pivotal role in organic film formation and bacterium-substratum interactions. The production and chemical composition of EPS produced by seven bioleaching strains grown with different substrates were studied. Analysis of the EPS extracted from these strains indicated that the EPS consisted of carbohydrates, proteins and galacturonic acid. The contents of EPS, carbohydrates, proteins and galacturonic acid of EPS were largely related to the kind of strain used and culture condition. The results show that EPS productions of microbes grown with pyrite were significantly higher than those of microbes grown with sulfur or FeSO4·7H2O. The highest EPS production of the seven acidiphilic strains was （159.43±3.93） mg/g, which was produced by Leptospirillum ferriphilum CBCBSUCSU208015 when cultivated with pyrite.
基金Projects (51174062, 51104036, 50874030) supported by the National Natural Science Foundation of ChinaProjects (2012AA061502) supported by the High-tech Research and Development Program of ChinaProjects (N100602007) supported by the Fundamental Research Funds for the Central Universities, China
文摘Passivation is a common phenomenon on the surface of chalcopyrite in the process of bioleaching. The ordinary leaching and strengthening leaching by adding glass beads were carried out. The results show that the passivation of chalcopyrite was greatly weakened in strengthening leaching due to the change of leaching conditions. The copper leaching efficiency was increased from 50% to 89.8% through adding beads. The SEM and X-ray diffraction （XRD） analyses illustrate that there are few jarosite precipitates and weak passivation on the surface of chalcopyrite in strengthening leaching. In contrast, there are thick and compact jarosite precipitate and obvious passivation in ordinary leaching, which hinders further dissolution of chalcopyrite.
基金Project (51374248) supported by the National Natural Science Foundation of ChinaProject (NCET-13-0595) supported by the Program for New Century Excellent Talents in University,China+3 种基金Project (2012AA061501) supported by the High-tech Research and Development Program of ChinaProject (2010CB630905) supported by the National Basic Research Program of ChinaProject (20120162120010) supported by the Research Fund for the Doctoral Program of Higher Education of ChinaProject (CSUZC2012020) supported by the Open-End Fund for the Valuable in Central South University,China
文摘The variation of microbial community structure was investigated for the tank bioleaching process of Pb-Zn-Sn chalcopyrite concentrate in the presence of mixed moderately thermophilic bacteria. The parameters, such as pH value, solution potential and concentrations of metal ions, were determined by the method of polymerase chain reaction-restriction fragment length polymorphism （PCR-RFLP） to analyze the succession of microbial community. The results showed that a final copper extraction rate of 85.6% could be obtained after tank bioleaching for 30 d. The Acidithiobacillus caldus was the dominant population with abundance of about 73.80%in the initial stage, then Sulfobacillus thermosulfidooxidans dominated from the 18th day to the end of bioleaching, while the abundance of Leptospirillum ferriphilum changed slightly. A higher solution potential within a certain range and appropriate concentration of ferric ions were essential for this tank bioleaching of chalcopyrite.
基金Project(50974140) supported by the National Natural Science Foundation of ChinaProject(20090162110054) supported by Specialized Research Fund for the Doctoral Program of Higher Education of China
文摘The apparent sulfur oxidation activities of four pure thermophilic archaea, Acidianus brierleyi （JCM 8954）, Metallosphaera sedula （YN 23）, Acidianus manzaensis （YN 25） and Sulfolobus metallicus （YN 24） and their mixture in bioleaching chalcopyrite were compared, which were characterized indirectly by the evolution of the cells concentration, pH value and sulfate ions concentration in solution. The results show that the mixed culture contributed significantly to the raising of leaching rate, which suggests that the mixed culture had a higher sulfur oxidation activity than the pure culture. Meanwhile, the results also indicate that the changes of parameters characterizing the sulfur oxidation activity of thermophilic archaea are often influenced by many factors, so it is hard to reflect accurately the specific sulfur oxidation activities among the different sulfur-oxidizing microbes when bioleaching chalcopyrite at different conditions. Accordingly, an efficient method to characterize microbial sulfur oxidation activity appears to be desirable.
基金Project(50774102)supported by the National Natural Science Foundation of ChinaProject(2004CB619204)supported by the National Basic Research Program of China
文摘To screen the high efficient mixed culture and understand the bioleaching behaviors of mixed culture for low-grade copper sulfide ore bioleaching,ten mixed cultures were collected and screened from different acid mine drainages obtained from sulfide mines of China.The leaching rate was set as criterion to screen the mixed culture and the metagenomic approach.Community genome array（CGA） was used for analyzing the mixed culture microbial community shift during the bioleaching process.The results indicate that the mixed culture obtained from Yinshan（YS） lead-zinc mine in Dexing of Jiangxi province in China reaches the maximum copper extraction（68.89%） during the one bioleaching period of 24 d.CGA results show that YS culture contains nine kinds of bacteria which are belong to six divisions,and the microbial community structure is changing during the bioleaching process.This provides a good way to accelerate the bioleaching process and reveals the microbial community shift during the bioleaching process.
基金Project (2012zzts026) supported by the Fundamental Research Funds for the Central Universities,ChinaProject (201205020) supported by Scientific Research Program of Marine Public Welfare Industry of China+2 种基金Project (51074195) supported by the National Natural Science Foundation of ChinaProject (CX2012B123) supported by Research Innovation for Graduate Student of Hunan Province,ChinaProject (12C517) supported by Education Department of Hunan Province,China
文摘Effects of initial pH, temperature, liquid volume, rotation speed, galvanic interaction （pyrite ratio） and pulp density on bioleaching of complex Cu-polymetallic concentrate were investigated. The results indicated that the copper extraction at pH 1.5 was 1.5 and 1.4 times that at pH 1.0 and pH 2.0 respectively. The copper extraction obtained at 45 ℃ was 1236.8%higher than that at 50 ℃. With the increase of rotation speed or the decrease of liquid volume, copper extraction was improved obviously. Copper extraction was improved gradually with the increase of pyrite ratio. However, when the ratio was higher than 20.0%, no further increase in copper extraction was observed. And the statistically significant interactive effects on copper extraction were found between temperature and pH, and temperature and pyrite ratio.
基金Project(U1232103)supported by the Joint Funds of National Natural Science Foundation of China and Large Scientific Facility Foundation of Chinese Academy of SciencesProject(51274257)supported by the National Natural Science Foundation of China+2 种基金Project(CX2014B092)supported by Hunan Provincial Innovation Foundation For Postgraduate,ChinaProject(VR-12419)supported by Beijing Synchrotron Radiation Facility Public User Program,ChinaProjects(13SRBL15U13024,13SRBL14B13023)supported by the Open Funds of Shanghai Synchrotron Radiation Facility,China
文摘The formation and evolution of secondary minerals during bioleaching of chalcopyrite by thermoacidophilic Archaea Acidianus manzaensis were analyzed by combining synchrotron radiation X-ray diffraction（SR-XRD） and S, Fe and Cu Kα X-ray absorption near edge structure（XANES） spectroscopy. Leaching experiment showed that 82.4% of Cu2＋ was dissolved by A. manzaensis after 10 d. The surface of chalcopyrite was corroded apparently and covered with leaching products. During bioleaching, the formation and evolution of secondary minerals were as follows： 1） little elemental sulfur, jarosite, bornite and chalcocite were found at days 2 and 4; and 2） bornite and chalcocite disappeared, covellite formed, and jarosite gradually became the main component at days 6 and 10. These results indicated that metal-deficiency sulfides chalcocite and bornite were first formed with a low redox potential value（360-461 m V）, and then gradually transformed to covellite with a high redox potential value（461-531 m V）.
基金Projects(51374248,51320105006)supported by the National Natural Science Foundation of ChinaProject(NCET-13-0595)supported by the Program for New Century Excellent Talents in University,ChinaProject(2014T70692)supported by China Postdoctoral Science Foundation
文摘X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） analyses were carried out to investigate the surface species and interfacial reactions during bioleaching of chalcopyrite by different strains of moderately thermophilic bacteria （45 °C）. Results show that monosulfide （CuS）, disulfide （S22？）, polysulfide （Sn2？）, elemental sulfur （S0） and sulfate （SO42？） are the main intermediate species on the surface of chalcopyrite during bioleaching byA. caldus,S. thermosulfidooxidans andL. ferriphilum. The low kinetics of dissolution of chalcopyrite inA. caldus can be mainly attributed to the incomplete dissolution of chalcopyrite and the passivation layer of polysulfide. Polysulfide and jarosite should be mainly responsible for the passivation of chalcopyrite in bioleaching byL. ferriphilumorS. thermosulfidooxidans. However, elemental sulfur should not be the main composition of passivation layer of chalcopyrite during bioleaching.
基金Projects(51174239,30700008)supported by the National Natural Science Foundation of ChinaProjects(20090461028,201003526)supported by China Postdoctoral Science Foundation
文摘Bioleaching Xiangjiang River alkaline sediment contaminated by multiple heavy metals was investigated. Multiple metals in alkaline sediment possess significant toxicity to aquatic organisms or humans and will greatly inhibit bioleaching. The bioleaching method using autotrophic bacteria mixed with heterotrophic bacteria can solve this problem successfully. The experiment results showed that bioleaching efficiencies of Zn, Mn, Cu, and Cd were 95.2 %, 94.2 %, 90.1 %, and 84.4 %, respectively. Moreover, the changes of heavy metal concentrations in different fractions in contaminated sediment before and after bioleaching were analyzed by selective sequential extraction, and it was discovered that the main fractions of Zn, Mn, Cu and Cd after bioleaching are Fe-Mn oxide, organic associated form and a residual form. Its biotoxicity decreased greatly. The bioleaching heavy metals from sediment using autotrophic bacteria combined with heterotrophic bacteria can effectively improve the bioleaching efficiency and reduce toxicity.
基金Project (41271330) supported by the National Natural Science Foundation of China
文摘The effects of moderately thermophilic bacteria on the extraction of metals from zinc smelting slag and electrochemical characteristics of zinc smelting slag carbon paste electrode in bioleaching process were studied. The results show that the extraction rates of Fe, Cu and Zn from the slag reach 86.7%, 90.3% and 66.7% after adsorbed bacteria sterilize, while those with adsorbed bacteria are 91.9%, 96.0% and 84.5% in conditions of pulp density 2%, pH 1.0, temperature 65 °C and stirring rate 120 r/min, respectively. Some stretching peaks of functional groups from bacterial secretes on the bioleached residue surface, such as 1007 cm-1 and 1193 cm-1, turn up through FI-IR analysis and indirectly reveal the presence of the adsorbed bacteria on the slag particles surface. Besides, the corrosion of zinc smelting slag is enhanced by bacteria according to the characteristics of cyclic voltametry and Tafel curves in bioleaching system.
基金Project(2012AA061502)supported by the National High-tech Research and Development Program of ChinaProjects(51374066,51304047)supported by the National Natural Science Foundation of ChinaProject(2012223002)supported by Industrial Research Projects in Liaoning Province,China
文摘The function of microorganism and dissolution reaction pathway of carrollite in the bioleaching process were investigated. The results showed that both indirect and contact mechanisms influenced the leaching process. The dissolution of carrollite was significantly accelerated when bacteria were adsorbed on the mineral surface, indicating that the contact mechanism significantly affected the dissolution of carrollite. During bioleaching, the sequence of oxidation state of the sulfur moiety of carrollite was as follows： S？2→S0→S＋4→S＋6. Elemental sulfur precipitated on the mineral surface, indicating that the dissolution of carrollite occurred via the polysulfide pathway. The surface of carrollite was selectively corroded by bacteria, and oxidation pits with different sizes were observed at various sites. Elemental sulfur, sulfate and sulfite were present on the surface of carrollite during the leaching process, and may have formed a passivation layer on mineral surface.
基金Project(41073060)supported by the National Natural Science Foundation of ChinaProject(12ZR1440400)supported by the Shanghai Natural Science Foundation of Youth,China+1 种基金Project(B604)supported by the Shanghai Leading Academic Discipline,ChinaProject supported by the State Environmental Protection Engineering Center for Pollution Treatment and Control in Textile Industry,China
文摘Leptospirillum ferriphilum YXW was isolated through serial dilution from mixed microorganisms enriched in AMD from Dexing copper mine in Jiangxi Province, China. It was mutated by ultrasonic, UV and microwave to collect more efficient strain for bioleaching of gold ore. Physiological and biochemical characteristics indicate that strain YXW is a strict chemoautotrophic microorganism, and the optimal condition for its growth is temperature of 40 °C and pH 1.5. After mutation by ultrasonic, UV and microwave, the density of bacterial cells reached 9×109, 8.4×109 and 4.3×108 mL-1, increased by 291%, 265%and 87%, respectively, compared with the original culture. The bacterial total protein activity was improved by microwave and UV mutations, but was reduced by ultrasonic. Mutations had effects on bioleaching of gold ore in sequence of microwave〉UV〉ultrasonic. During gold ore bioleaching, the bacterial mutant after mutation by microwave had the best effect on the extraction rates of arsenic and iron, which were 19.6%and 17.7%higher than that of the original strain after bioleaching for 10 d, respectively. The results suggested that the effects of mutation on bioleaching of gold ore may not be mainly due to increase of bacterial cells density, but may be mainly attributed to the improvement of bacterial total protein activity.
基金Project(31200382)supported by the National Natural Science Foundation of China
文摘The effect of pH values on the extracellular protein and polysaccharide secretions of Acidithiobacillus ferrooxidans was comparatively investigated in different phases of bacterial growth during chalcopyrite bioleaching. The results indicate that the extracellular protein is always more than the extracellular polysaccharide secreted by attached cells on the chalcopyrite, on the contrary, and is always less than the extracellular polysaccharide secreted by free cells in the solution at bacterial adaptive phase, logarithmic phase and stationary phase whenever pH value is at 1.0, 1.5, 2.0 or 2.5; free cells are mainly through the secretion of extracellular polysaccharide rather than the extracellular protein to fight against disadvantageous solution environment, such as high concentration of metal ions and unsuitable pH solution; both amounts of polysaccharide and protein secreted by attached cells are mainly positively related to the solution acidity rather than the total concentration of soluble metal ions. The experimental results imply that bacteria are mainly through secreting more extracellular polysaccharide to fight against disadvantageous environment and the extracellular protein perhaps plays an important role in oxidation？reduction reactions in the bioleaching system.
