The electrochemical dissolution process of chalcopyrite and bornite in acid bacteria culture medium was investigated by electrochemical measurements and X-ray photoelectron spectroscopy（XPS） analysis. Bornite was mu...The electrochemical dissolution process of chalcopyrite and bornite in acid bacteria culture medium was investigated by electrochemical measurements and X-ray photoelectron spectroscopy（XPS） analysis. Bornite was much easier to be oxidized rather than to be reduced, and chalcopyrite was difficult to be both oxidized and reduced. The relatively higher copper extraction of bornite dissolution can be attributed to its higher oxidation rate. Covellite（CuS） was detected as the intermediate species during the dissolution processes of both bornite and chalcopyrite. Bornite dissolution was preferred to be a direct oxidation pathway, in which bornite was directly oxidized to covellite（CuS） and cupric ions, and the formed covellite（CuS） may inhibit the further dissolution. Chalcopyrite dissolution was preferred to be a continuous reduction-oxidation pathway, in which chalcopyrite was initially reduced to bornite, then oxidized to covellite（CuS）, and the initial reduction reaction was the rate-limiting step.展开更多
In this paper,the effect of sodium butyl xanthate(NaBX)adsorption on the surface of bornite at different pH on flotation was studied by adsorption kinetic and thermodynamic.The flotation results demonstrated that the ...In this paper,the effect of sodium butyl xanthate(NaBX)adsorption on the surface of bornite at different pH on flotation was studied by adsorption kinetic and thermodynamic.The flotation results demonstrated that the recovery was the highest when pH was 9 in NaBX solution(4×10^?5 mol/L).The adsorption kinetics showed the reaction of NaBX on the bornite conformed to the second order kinetic equation;it belonged to the multimolecular layer adsorption of Freundlich model;the maximum adsorption rate constant was 0.30 g/(10^?6 mol·min),and the equilibrium adsorption capacity was 2.70×10^?6 mol/g.Thermodynamic calculation results indicated that the adsorption process was spontaneous chemisorption,and the adsorption products of NaBX on bornite surface were cupric butyl xanthate,ferric butyl xanthate and dixanthogen,which were confirmed by infrared spectrum measurements.展开更多
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 leach...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.展开更多
The existence and release of fluid inclusions in bornite and its associated minerals, namely, quartz and calcite were investigated and confirmed. The structures, forms, and phases of these large quantities of fluid in...The existence and release of fluid inclusions in bornite and its associated minerals, namely, quartz and calcite were investigated and confirmed. The structures, forms, and phases of these large quantities of fluid inclusions were also studied. A mass of fluid inclusions with various sizes, distributions, shapes, and phases exist in bornite and its associated minerals. Their sizes vary from a few micrometers to tens of micrometers, and the forms appear as negative crystals, or elongated, elliptical, and irregular. At room temperature, fluid inclusions were mainly characterized as gas-liquid two- phase. However, small amounts of fluid inclusions with pure gas phase and pure liquid single-phase were also observed in quartz and calcite. These fluid inclusions initially broke during the ore crushing and grinding process and then released into the flotation pulp in the flotation process. The quantitative analysis of fluid inclusions in the solution and the comparisons of mineral dissolution show that the amount of copper and iron released by fluid inclusions in the bornite sample is higher than the amount dissolved by the mineral; fluid inclusions in the associated gangue minerals, quartz, and calcite also make contribution.展开更多
Interactions between chalcopyrite and bornite during bioleaching by moderately thermophilic bacteria were investigated mainly by X-ray diffraction, scanning electron microscopy, and electrochemical measurements perfor...Interactions between chalcopyrite and bornite during bioleaching by moderately thermophilic bacteria were investigated mainly by X-ray diffraction, scanning electron microscopy, and electrochemical measurements performed in conjunction with bioleaching experiments. The results showed that a synergistic effect existed between chalcopyrite and bornite during bioleaching by both Acidithiobacillus caldus and Leptospirillum ferriphilum and that extremely high copper extraction could be achieved when chalcopyrite and bornite coexisted in a bioleaching system. Bornite dissolved preferentially because of its lower corrosion potential, and its dissolution was accelerated by the galvanic current during the initial stage of bioleaching. The galvanic current and optimum redox potential of 390-480 m V vs. Ag/Ag Cl promoted the reduction of chalcopyrite to chalcocite(Cu2S), thus accelerating its dissolution.展开更多
Acid mine drainage(AMD)has become a widespread environmental issue and its toxicity can cause permanent damage to the ecosystem.However,there are few studies focusing on the formation of AMD under moderately thermophi...Acid mine drainage(AMD)has become a widespread environmental issue and its toxicity can cause permanent damage to the ecosystem.However,there are few studies focusing on the formation of AMD under moderately thermophilic conditions,hence we employed X-ray diffraction(XRD),scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS)and 16S rRNA sequencing to study the dissolution of pyrite and bornite by a moderate thermophilic consortium,and explored the role of free and attached microorganisms in the formation of AMD.The consortium mainly comprised Acidithiobacillus caldus,Leptospirillum ferriphilum and Sulfobacillus thermosulfidooxidans.The results indicated that total iron in pyrite solution system reached 33.45 g/L on the 12th day,and the copper dissolution rate of bornite dissolution reached 91.8%on the 24th day.SEM results indicated that the surfaces of pyrite and bornite were significantly corroded by microorganisms.XRD and XPS results showed that ore residues contained jarosite,and the dissolving residue of bornite contained elemental sulfur.The dominant bacterial genus in pyrite dissolution was A.caldus,and L.ferriphilum in bornite dissolution.To sum up,microbes significantly accelerated the mineral dissolution process and promoted the formation of AMD.展开更多
Chalcopyrite and bornite are the main Au-bearing minerals at Cu porphyry deposits,volcanogenic massive sulfide(VMS)deposits,Cu-Ni deposits of the mafic magmatic complexes,and ores of submarine sulfide edifices.Bornite...Chalcopyrite and bornite are the main Au-bearing minerals at Cu porphyry deposits,volcanogenic massive sulfide(VMS)deposits,Cu-Ni deposits of the mafic magmatic complexes,and ores of submarine sulfide edifices.Bornite and intermediate solid solutions with wide compositional variations(bnss and iss–high-temperature chalcopyrite,correspondingly),which can scavenge economic concentrations of Au,appear in the Cu-Fe-S system at ore-forming conditions.However,the state of Au in bnss and iss is yet unknown.To solve this conundrum,we synthesized samples with net chemical composition of bnss and iss,studied them by in situ X–ray absorption spectroscopy(XAS),and used the experimental data to explain the Au distribution among natural ore-forming minerals.The sulfide samples were obtained at 495–700℃ in Au-saturated system by means of salt flux method.The bnss contained1.2–1.6 log units more Au than iss:up to 18 wt.%Au in bnss vs 0.4 wt.%Au in iss at 700C.An increase of temperature resulted in the sharp increase of Au concentration in both phases,1 log unit per 100℃ at f(S2)close to S_((l)) saturation.Analysis of Au L_(3)-edge spectra recorded at 25–675℃ revealed that at 25℃ Au exists mainly in the metallic state.At t>500℃ the spectral features of Audisappear,and “chemically bound”Au predominates.The Au form of occurrence in the iss field is interpreted as Au-bearing clusters with a stromeyerite-like(CuAgS)structure.Digenite Cu_(2–x)S and bnss contain Au in a mixture of stromeyeritelike and petrovskaite-like(Au_(0.8)Ag_(1.2)S)clusters.The chemical composition of both forms is close to CuAuS,where the nearest Au neighbors are two S atoms at R_(Au-S)=2.34–2.36Å.Results of the present study allow to determine the state of Au and its concentration in the main Cu-bearing minerals of sulfide ores as a function of the T-f(S_(2))-compositional parameters.Due to the sharp increase of the CuAuS clusters stability with increasing temperature,in high-temperature ores formed at t>350℃ Au enriches Cubearing minerals in comparison with Cu-free or Cu-deficient ones.As a result,in these ores native gold,being a product of decomposition of the Au-bearing clusters,is associated with Cu-rich minerals–chalcopyrite,bornite,digenite,chalcocite.展开更多
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(CX2014B091)supported by the Hunan Provincial Innovation Foundation for Postgraduate,China
文摘The electrochemical dissolution process of chalcopyrite and bornite in acid bacteria culture medium was investigated by electrochemical measurements and X-ray photoelectron spectroscopy（XPS） analysis. Bornite was much easier to be oxidized rather than to be reduced, and chalcopyrite was difficult to be both oxidized and reduced. The relatively higher copper extraction of bornite dissolution can be attributed to its higher oxidation rate. Covellite（CuS） was detected as the intermediate species during the dissolution processes of both bornite and chalcopyrite. Bornite dissolution was preferred to be a direct oxidation pathway, in which bornite was directly oxidized to covellite（CuS） and cupric ions, and the formed covellite（CuS） may inhibit the further dissolution. Chalcopyrite dissolution was preferred to be a continuous reduction-oxidation pathway, in which chalcopyrite was initially reduced to bornite, then oxidized to covellite（CuS）, and the initial reduction reaction was the rate-limiting step.
基金Projects(51504053,51374079)supported by the National Natural Science Foundation of ChinaProject(2015M571324)supported by the Postdoctoral Science Foundation of China
文摘In this paper,the effect of sodium butyl xanthate(NaBX)adsorption on the surface of bornite at different pH on flotation was studied by adsorption kinetic and thermodynamic.The flotation results demonstrated that the recovery was the highest when pH was 9 in NaBX solution(4×10^?5 mol/L).The adsorption kinetics showed the reaction of NaBX on the bornite conformed to the second order kinetic equation;it belonged to the multimolecular layer adsorption of Freundlich model;the maximum adsorption rate constant was 0.30 g/(10^?6 mol·min),and the equilibrium adsorption capacity was 2.70×10^?6 mol/g.Thermodynamic calculation results indicated that the adsorption process was spontaneous chemisorption,and the adsorption products of NaBX on bornite surface were cupric butyl xanthate,ferric butyl xanthate and dixanthogen,which were confirmed by infrared spectrum measurements.
基金Project(51974363)supported by the National Natural Science Foundation of China。
文摘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.
基金financially supported by the National Natural Science Foundation of China(Nos.u0837602,51204078,and KKGE201121001)the Natural Science Foundation of the Education Department of Yunnan Province,China(No.2012J085)the Excellent Doctoral Dissertation Foundation of Kunming University of Science and Technology(No.41118011)
文摘The existence and release of fluid inclusions in bornite and its associated minerals, namely, quartz and calcite were investigated and confirmed. The structures, forms, and phases of these large quantities of fluid inclusions were also studied. A mass of fluid inclusions with various sizes, distributions, shapes, and phases exist in bornite and its associated minerals. Their sizes vary from a few micrometers to tens of micrometers, and the forms appear as negative crystals, or elongated, elliptical, and irregular. At room temperature, fluid inclusions were mainly characterized as gas-liquid two- phase. However, small amounts of fluid inclusions with pure gas phase and pure liquid single-phase were also observed in quartz and calcite. These fluid inclusions initially broke during the ore crushing and grinding process and then released into the flotation pulp in the flotation process. The quantitative analysis of fluid inclusions in the solution and the comparisons of mineral dissolution show that the amount of copper and iron released by fluid inclusions in the bornite sample is higher than the amount dissolved by the mineral; fluid inclusions in the associated gangue minerals, quartz, and calcite also make contribution.
基金financially supported by the National Natural Science Foundation of China (Nos. 51374248 and 51320105006)the Program for New Century Excellent Talents in University (No. NCET-13-0595)the China Postdoctoral Science Foundation (No. 2014T70692)
文摘Interactions between chalcopyrite and bornite during bioleaching by moderately thermophilic bacteria were investigated mainly by X-ray diffraction, scanning electron microscopy, and electrochemical measurements performed in conjunction with bioleaching experiments. The results showed that a synergistic effect existed between chalcopyrite and bornite during bioleaching by both Acidithiobacillus caldus and Leptospirillum ferriphilum and that extremely high copper extraction could be achieved when chalcopyrite and bornite coexisted in a bioleaching system. Bornite dissolved preferentially because of its lower corrosion potential, and its dissolution was accelerated by the galvanic current during the initial stage of bioleaching. The galvanic current and optimum redox potential of 390-480 m V vs. Ag/Ag Cl promoted the reduction of chalcopyrite to chalcocite(Cu2S), thus accelerating its dissolution.
基金Projects(51934009,52074353)supported by the National Natural Science Foundation of ChinaProject(2019YFC1803600)supported by the National Key Research and Development Program of ChinaProject(2021JJ30855)supported by the Natural Science Foundation of Hunan Province,China。
文摘Acid mine drainage(AMD)has become a widespread environmental issue and its toxicity can cause permanent damage to the ecosystem.However,there are few studies focusing on the formation of AMD under moderately thermophilic conditions,hence we employed X-ray diffraction(XRD),scanning electron microscopy(SEM),X-ray photoelectron spectroscopy(XPS)and 16S rRNA sequencing to study the dissolution of pyrite and bornite by a moderate thermophilic consortium,and explored the role of free and attached microorganisms in the formation of AMD.The consortium mainly comprised Acidithiobacillus caldus,Leptospirillum ferriphilum and Sulfobacillus thermosulfidooxidans.The results indicated that total iron in pyrite solution system reached 33.45 g/L on the 12th day,and the copper dissolution rate of bornite dissolution reached 91.8%on the 24th day.SEM results indicated that the surfaces of pyrite and bornite were significantly corroded by microorganisms.XRD and XPS results showed that ore residues contained jarosite,and the dissolving residue of bornite contained elemental sulfur.The dominant bacterial genus in pyrite dissolution was A.caldus,and L.ferriphilum in bornite dissolution.To sum up,microbes significantly accelerated the mineral dissolution process and promoted the formation of AMD.
基金the ESRF for the beamtime allocation under proposals No.ES-184(ID26 beamline)and ES-703(BM20 beamline)study was supported by the Russian Science Foundation grant No.20-17-00184(XAS experiment,interpretation,geological application)Grant of the President of the Russian Federation for the state support of the leading scientific schools of the Russian Federation No.NSh-2394.2022.1.5(synthesis experiments,analysis of the synthesis products)support by the Russian Ministry of Science and Education under grant No 075-15-2022-1107(XAS experimental setup).
文摘Chalcopyrite and bornite are the main Au-bearing minerals at Cu porphyry deposits,volcanogenic massive sulfide(VMS)deposits,Cu-Ni deposits of the mafic magmatic complexes,and ores of submarine sulfide edifices.Bornite and intermediate solid solutions with wide compositional variations(bnss and iss–high-temperature chalcopyrite,correspondingly),which can scavenge economic concentrations of Au,appear in the Cu-Fe-S system at ore-forming conditions.However,the state of Au in bnss and iss is yet unknown.To solve this conundrum,we synthesized samples with net chemical composition of bnss and iss,studied them by in situ X–ray absorption spectroscopy(XAS),and used the experimental data to explain the Au distribution among natural ore-forming minerals.The sulfide samples were obtained at 495–700℃ in Au-saturated system by means of salt flux method.The bnss contained1.2–1.6 log units more Au than iss:up to 18 wt.%Au in bnss vs 0.4 wt.%Au in iss at 700C.An increase of temperature resulted in the sharp increase of Au concentration in both phases,1 log unit per 100℃ at f(S2)close to S_((l)) saturation.Analysis of Au L_(3)-edge spectra recorded at 25–675℃ revealed that at 25℃ Au exists mainly in the metallic state.At t>500℃ the spectral features of Audisappear,and “chemically bound”Au predominates.The Au form of occurrence in the iss field is interpreted as Au-bearing clusters with a stromeyerite-like(CuAgS)structure.Digenite Cu_(2–x)S and bnss contain Au in a mixture of stromeyeritelike and petrovskaite-like(Au_(0.8)Ag_(1.2)S)clusters.The chemical composition of both forms is close to CuAuS,where the nearest Au neighbors are two S atoms at R_(Au-S)=2.34–2.36Å.Results of the present study allow to determine the state of Au and its concentration in the main Cu-bearing minerals of sulfide ores as a function of the T-f(S_(2))-compositional parameters.Due to the sharp increase of the CuAuS clusters stability with increasing temperature,in high-temperature ores formed at t>350℃ Au enriches Cubearing minerals in comparison with Cu-free or Cu-deficient ones.As a result,in these ores native gold,being a product of decomposition of the Au-bearing clusters,is associated with Cu-rich minerals–chalcopyrite,bornite,digenite,chalcocite.
