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
The grown conditions of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were investigated,and then experiments were conducted to research the bioleaching behaviors of crude ore of copper sulfide and h...The grown conditions of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were investigated,and then experiments were conducted to research the bioleaching behaviors of crude ore of copper sulfide and hand-picked concentrates of chalcopyrite by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans.The experimental results show that the bacteria grow best when the temperature is(30±1) °C and the pH value is 2.0.The bacteria concentration is 2.24×107 mL-1 in this condition.It is found that the copper extraction yield is affected by the inoculum size and the pulp density and the extraction yield increases as the inoculum size grows.The bioleaching rates reach their highest point in sulfide copper and chalcopyrite with a pulp density of 5% and 10%,respectively.Column flotation experiments of low-grade copper sulfide ores show that the bioleaching recovery reaches nearly 45% after 75 days.展开更多
Microbiologically-induced concrete corrosion(MICC)refers to chemical reactions between biologically produced sulphuric acid and with hydration products in the hardened concrete paste,resulting in an early reduction of...Microbiologically-induced concrete corrosion(MICC)refers to chemical reactions between biologically produced sulphuric acid and with hydration products in the hardened concrete paste,resulting in an early reduction of strength,deterioration,and very severe circumstances,structural failure.This paper explores the bactericidal characteristics of cementitious materials with surface coated with modified zeolite-polyurethane.The zeolite-polyurethane coating incorporated with silver was studied in environments inoculated with A.thiooxidans bacteria for 8 consecutive weeks.The antibacterial characteristics were evaluated in terms of pH,optical density(OD),sulphate production and bacteria count to determine the effectiveness of the zeolite-polyurethane coatings in environments inoculated with A.thiooxidans bacteria producing the sulphuric acid.The results revealed that the samples incorporated with silver modified zeolites generally showed antibacterial performance(regardless of the zeolite type)compared with unmodified polyurethane coating.This was evaluated by the lack of bacteria attachment and the deformed microcolonies on the sample surface,lag in pH reduction,increase in OD,and sulphate production.The silver zeolites gained their antibacterial performance from the release of silver ions(Ag^(+))when the sample comes into contact with aqueous solutions.This results in the inhibition of cell functions of the bacteria and subsequently causes cell damage.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
The bioleaching of chalcopyrite was investigated using a pure and mixed culture consisting of iron-oxidizing Leptospirillum ferriphilum （L. ferriphilum） and sulfur-oxidizing Acidthiobacillus thiooxidans （.4. thioox...The bioleaching of chalcopyrite was investigated using a pure and mixed culture consisting of iron-oxidizing Leptospirillum ferriphilum （L. ferriphilum） and sulfur-oxidizing Acidthiobacillus thiooxidans （.4. thiooxidans）. The electrochemical tests were conducted to investigate the bioleaching behavior of chalcopyrite by various bacteria. Bioleaching efficiency of chalcopyrite in mixed culture is higher than that in the pure culture of L.ferriphilum alone. The iron-oxidizing L.ferriphilum plays a dominant role during bioleaching of chalcopyrite in the mixed culture of L. ferriphilum and A. thiooxidans. During bioleaching, certain values of redox potential are beneficial to the decomposition of chalcopyrite. Jarosite and sulfur are observed as products of bioleaching. The addition of A. thiooxidans during leaching by L. ferriphilum can change the electrochemical control steps of leaching. The corrosion current density is substantially promoted in the culture involving bacteria, especially in the mixed culture.展开更多
Three kinds of autotrophic bioleaching bacteria strains,including mesophilic and acidophilic ferrous ion-oxidizing bacteria Acidithiobacillus ferrooxidans(A.ferrooxidans),mesophilic and acidophilic sulfur-oxidizing ba...Three kinds of autotrophic bioleaching bacteria strains,including mesophilic and acidophilic ferrous ion-oxidizing bacteria Acidithiobacillus ferrooxidans(A.ferrooxidans),mesophilic and acidophilic sulfur-oxidizing bacteria Acidithiobacillus thiooxidans(A.thiooxidans),and moderately thermophilic sulfur-oxidizing bacteria.4cidianus brierleyi,were cryopreserved in liquid nitrogen and their ferrous ion-or sulfur-oxidizing activities were investigated and compared with the original ones.The results revealed that ferrous ion/sulfur oxidation activities of the strains were almost equal before and after cryopreservation.Glycerin was used as cryoprotective agent.In conclusion,liquid-nitrogen cryopreservation is a simple and effective method for autotrophic bioleaching microorganisms.展开更多
A dual cell system was used to study the electrogenerative leaching sphalerite-MnO2 in the presence and absence of Acidithiobacillus thiooxidans (A. thiooxidans). The polarization of anode and cathode, and the relatio...A dual cell system was used to study the electrogenerative leaching sphalerite-MnO2 in the presence and absence of Acidithiobacillus thiooxidans (A. thiooxidans). The polarization of anode and cathode, and the relationship between the electric quantity (Q) and some factors, such as the dissolved rate of Zn2+ and Fe2+, and the time in the bio-electro-generating simultaneous leaching (BEGL) and electro-generating simultaneous leaching (EGL) were studied. A three-electrode system was applied to studying anodic and cathodic self-corrosion current, which was inappreciable compared with the galvanic current between sphalerite and MnO2. The results show that the dissolved Zn2+ in the presence of A. thiooxidans is nearly 43% higher than that in the absence of A. thiooxidans; the electrogenerative quantity in the former is about 150% more than that in the latter. The accumulated sulfur on the surface of sulfides produced in the electrogenerative leaching process can be oxidized in the presence of A. thiooxidans, and the ratio of biologic electric quantity reaches 27.9% in 72 h.展开更多
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.
基金Project(2012AA061501)supported by the National High-tech Research and Development Program of ChinaProject(20120162120010)supported by the Research Fund for the Doctoral Program of Higher Education of China+2 种基金Project(NCET-13-0595)supported by the program for New Century Excellent Talents in University of ChinaProject(51374248)supported by the National Natural Science Foundation of ChinaProject(2010CB630905)supported by the National Key Basic Research Program of China
文摘The grown conditions of Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans were investigated,and then experiments were conducted to research the bioleaching behaviors of crude ore of copper sulfide and hand-picked concentrates of chalcopyrite by Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans.The experimental results show that the bacteria grow best when the temperature is(30±1) °C and the pH value is 2.0.The bacteria concentration is 2.24×107 mL-1 in this condition.It is found that the copper extraction yield is affected by the inoculum size and the pulp density and the extraction yield increases as the inoculum size grows.The bioleaching rates reach their highest point in sulfide copper and chalcopyrite with a pulp density of 5% and 10%,respectively.Column flotation experiments of low-grade copper sulfide ores show that the bioleaching recovery reaches nearly 45% after 75 days.
基金Project(J130000.2524.04H87) supported by the Ministry of Higher Education of Malaysia and Universiti Teknologi Malaysia。
文摘Microbiologically-induced concrete corrosion(MICC)refers to chemical reactions between biologically produced sulphuric acid and with hydration products in the hardened concrete paste,resulting in an early reduction of strength,deterioration,and very severe circumstances,structural failure.This paper explores the bactericidal characteristics of cementitious materials with surface coated with modified zeolite-polyurethane.The zeolite-polyurethane coating incorporated with silver was studied in environments inoculated with A.thiooxidans bacteria for 8 consecutive weeks.The antibacterial characteristics were evaluated in terms of pH,optical density(OD),sulphate production and bacteria count to determine the effectiveness of the zeolite-polyurethane coatings in environments inoculated with A.thiooxidans bacteria producing the sulphuric acid.The results revealed that the samples incorporated with silver modified zeolites generally showed antibacterial performance(regardless of the zeolite type)compared with unmodified polyurethane coating.This was evaluated by the lack of bacteria attachment and the deformed microcolonies on the sample surface,lag in pH reduction,increase in OD,and sulphate production.The silver zeolites gained their antibacterial performance from the release of silver ions(Ag^(+))when the sample comes into contact with aqueous solutions.This results in the inhibition of cell functions of the bacteria and subsequently causes cell damage.
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%.
基金Project(2010CB630903) supported by the National Basic Research Program of China
文摘The bioleaching of chalcopyrite was investigated using a pure and mixed culture consisting of iron-oxidizing Leptospirillum ferriphilum （L. ferriphilum） and sulfur-oxidizing Acidthiobacillus thiooxidans （.4. thiooxidans）. The electrochemical tests were conducted to investigate the bioleaching behavior of chalcopyrite by various bacteria. Bioleaching efficiency of chalcopyrite in mixed culture is higher than that in the pure culture of L.ferriphilum alone. The iron-oxidizing L.ferriphilum plays a dominant role during bioleaching of chalcopyrite in the mixed culture of L. ferriphilum and A. thiooxidans. During bioleaching, certain values of redox potential are beneficial to the decomposition of chalcopyrite. Jarosite and sulfur are observed as products of bioleaching. The addition of A. thiooxidans during leaching by L. ferriphilum can change the electrochemical control steps of leaching. The corrosion current density is substantially promoted in the culture involving bacteria, especially in the mixed culture.
基金Project(50621063)supported by Chinese Science Foundation for Distinguished GroupProject(2004CB619201)supported by the National Basic Research Program of China
文摘Three kinds of autotrophic bioleaching bacteria strains,including mesophilic and acidophilic ferrous ion-oxidizing bacteria Acidithiobacillus ferrooxidans(A.ferrooxidans),mesophilic and acidophilic sulfur-oxidizing bacteria Acidithiobacillus thiooxidans(A.thiooxidans),and moderately thermophilic sulfur-oxidizing bacteria.4cidianus brierleyi,were cryopreserved in liquid nitrogen and their ferrous ion-or sulfur-oxidizing activities were investigated and compared with the original ones.The results revealed that ferrous ion/sulfur oxidation activities of the strains were almost equal before and after cryopreservation.Glycerin was used as cryoprotective agent.In conclusion,liquid-nitrogen cryopreservation is a simple and effective method for autotrophic bioleaching microorganisms.
基金Project(50874119) supported by the National Natural Science Foundation of ChinaProject supported by the Post doctoral Program of Central South University, China
文摘A dual cell system was used to study the electrogenerative leaching sphalerite-MnO2 in the presence and absence of Acidithiobacillus thiooxidans (A. thiooxidans). The polarization of anode and cathode, and the relationship between the electric quantity (Q) and some factors, such as the dissolved rate of Zn2+ and Fe2+, and the time in the bio-electro-generating simultaneous leaching (BEGL) and electro-generating simultaneous leaching (EGL) were studied. A three-electrode system was applied to studying anodic and cathodic self-corrosion current, which was inappreciable compared with the galvanic current between sphalerite and MnO2. The results show that the dissolved Zn2+ in the presence of A. thiooxidans is nearly 43% higher than that in the absence of A. thiooxidans; the electrogenerative quantity in the former is about 150% more than that in the latter. The accumulated sulfur on the surface of sulfides produced in the electrogenerative leaching process can be oxidized in the presence of A. thiooxidans, and the ratio of biologic electric quantity reaches 27.9% in 72 h.
