The depression mechanism of sulfite ions on sphalerite and Pb^(2+)activated sphalerite in the flotation separation of galena from sphalerite still lacked in-depth insight.Therefore,the depression mechanism of sulfite ...The depression mechanism of sulfite ions on sphalerite and Pb^(2+)activated sphalerite in the flotation separation of galena from sphalerite still lacked in-depth insight.Therefore,the depression mechanism of sulfite ions on sphalerite and Pb^(2+)activated sphalerite in the flotation separation of galena from sphalerite was further systematically investigated with experiments and density functional theory(DFT)calculations.The X-ray photoelectric spectroscopy(XPS)results,DFT calculation results,and frontier molecular orbital analysis indicated that sulfite ions were difficult to be adsorbed on sphalerite surface,suggesting that sulfite ions achieved depression effects on sphalerite through other non-adsorption mechanisms.First,the oxygen content in the surface of sphalerite treated with sulfite ions in creased,which enhanced the hydrophilicity of the sphalerite and further increased the difference in hydrophilicity between sphalerite and galena.Then,sulfite ions were chelated with lead ions to form PbSO_(3)in solution.The hydrophilic PbSO_(3)was more easily adsorbed on sphalerite than galena.The interaction between sulfite ions and lead ions could effectively inhibit the activation of sphalerite.In addition the UV spectrum showed that after adding sulfite ions,the peak of perxanthate in the sphalerite treated xanthate solution was significantly stronger than that in the galena with xanthate solution,indicating that xanthate interacted more readily with sulfite ions and oxygen mo lecules within the sphalerite system,leading to the formation of perxanthate.However,sulfite ions hardly depressed the flotation of ga lena and could promote the flotation of galena to some extent.This study deepened the understanding of the depression mechanism o sulfite ions on sphalerite and Pb^(2+)activated sphalerite.展开更多
Tetrasodium iminodisuccinate(IDS)was used as an inhibitor in the separation of sphalerite and pyrite in the EX−Cu(II)(ethyl xanthate and Cu2+)system.The flotation test results demonstrated that IDS can effectively sep...Tetrasodium iminodisuccinate(IDS)was used as an inhibitor in the separation of sphalerite and pyrite in the EX−Cu(II)(ethyl xanthate and Cu2+)system.The flotation test results demonstrated that IDS can effectively separate sphalerite and pyrite under low alkaline conditions.Furthermore,high-quality zinc concentrates with a Zn grade of 58.48%and a recovery of 91.24%through mixed mineral flotation were obtained.The fundamental mechanisms were investigated through surface wettability tests,adsorption capacity tests,LEIS,FTIR,and XPS.The results confirmed that IDS prevents the adsorption of EX on the surface of pyrite,thereby reducing the response and reactivity of pyrite.The introduction of IDS causes the detachment of Cu2+from the Cu-activated pyrite surface.This process allowed IDS to chelate with the Fe sites on the surface of pyrite through the-COO-and N-centered active groups.By contrast,IDS exhibits weaker adhesion on the surface of Cu-activated sphalerite,making it easily displaced by EX through competitive adsorption.展开更多
Herein,a first-principles investigation was innovatively conducted to research the surface oxidation of ZnS-like sphalerite in the absence and presence of H_(2)O .The findings showed that single O_(2) was preferred to...Herein,a first-principles investigation was innovatively conducted to research the surface oxidation of ZnS-like sphalerite in the absence and presence of H_(2)O .The findings showed that single O_(2) was preferred to be dissociated adsorption on sphalerite surface by generating SAO and Zn AO bonds,and the S atom on the surface was the most energy-supported site for O_(2) adsorption,on which a≡Zn-O-S-O-Zn≡structure will be formed.However,dissociated adsorption of single H_(2)O will not happen.It was preferred to be adsorbed on the top Zn atom on sphalerite surface in molecular form through Zn-O bond.Besides,sphalerite oxidation can occur as if O_(2) was present regardless of the presence of H_(2)O ,and when H_(2)O and O_(2) coexisted,the formation of sulfur oxide(SO_(2) )needed a lower energy barrier and it was easier to form on sphalerite surface than that only O_(2) existed.In the absence of H_(2)O ,when SO_(2) was generated,further oxidation of which would form neutral zinc sulfate.In the presence of H_(2)O ,the formation of SO_(2) on sphalerite surface was easier and the rate of further oxidation to form sulfate was also greater.Consequently,the occurrence of sphalerite oxidation was accelerated.展开更多
Four Pb-Zn deposits,namely Bangpu(BP),Digei(DG),Nabuding(NB)and Cuoga(CG),are located within a 20 km distance of each other in the Gangdese porphyry copper belt(GPCB).The age and nature of the Pb-Zn mineralization,esp...Four Pb-Zn deposits,namely Bangpu(BP),Digei(DG),Nabuding(NB)and Cuoga(CG),are located within a 20 km distance of each other in the Gangdese porphyry copper belt(GPCB).The age and nature of the Pb-Zn mineralization,especially its relationship to magmatism,remain uncertain.In order to address this issue,mica from the four deposits was selected for in situ Rb-Sr dating,with sphalerite additionally being selected for in situ trace element analysis.Detailed geological research has revealed that the BP and NB deposits are primarily skarn-type Pb-Zn mineralization,while DG and CG are associated with magmatic hydrothermal breccia and are characterized by banded-type mineralization.The Rb-Sr isochron ages of syn-mineralization muscovite at the BP and CG deposits are 11±6 Ma and 19.7±0.7 Ma respectively.Fe,Cd,In,Mn and Sn occur as lattice substitutions in sphalerite from the four deposits.Cu exists as microinclusions in BP,but occurs isomorphically in the DG,NB and CG deposits.The formation temperatures of the four deposits,as calculated from sphalerite geothermometry,range from approximately 200℃to 300℃,indicating that they belong to medium temperature deposits.BP and NB are classified as skarn Pb-Zn deposits,while DG and CG are categorized as hydrothermal filled Pb-Zn deposits.These results suggest that,in addition to porphyry Cu mineralization,the GPCB also contains significant Miocene Pb-Zn mineralization.展开更多
The lime-Cu^(2+)-xanthate process is commonly used for the flotation separation of sphalerite from pyrite.In this process,lime is added to the pulp to inhibit the floatability of pyrite.However,the excessive use of li...The lime-Cu^(2+)-xanthate process is commonly used for the flotation separation of sphalerite from pyrite.In this process,lime is added to the pulp to inhibit the floatability of pyrite.However,the excessive use of lime can result in pipeline blockage and inadequate recovery of associated precious metals.Therefore,it is necessary to develop new flotation process that minimizes or eliminates the use of lime.In this paper,a novel Fe^(3+)-Cu^(2+)-butyl xanthate process was developed as an alternative to lime for separating of sphalerite from pyrite.The flotation results indicated that with the artificially-mixed minerals,the flotation recovery of pyrite was lower than 16%and that of sphalerite was higher than 47%at pH 5.0−10.0.The zeta potential measurements revealed that ferric ion preferred to adsorb on pyrite,and copper ion displaced with zinc ion from the lattice at the interface of sphalerite.The wettability analyses indicated that the hydrophobicity of sphalerite surface increased apparently after being treated with Fe^(3+)-Cu^(2+)-BX,while the hydrophobicity of pyrite surface remained nearly unchanged.With XPS analysis,Cu-S bond and hydrophilic ferric hydroxide were detected separately on the surface of sphalerite and pyrite after conditioning with Fe^(3+)-Cu^(2+)-BX,which facilitated the flotation separation of sphalerite from pyrite with butyl xanthate collector.展开更多
Infrared microthermometry allows direct measurement of fluid inclusions hosted in opaque ore minerals and can provide direct constraints on the evolution of ore-forming fluids.This study presents infrared microthermom...Infrared microthermometry allows direct measurement of fluid inclusions hosted in opaque ore minerals and can provide direct constraints on the evolution of ore-forming fluids.This study presents infrared microthermometry of spherite-hosted fluid inclusions from the Xinqiao deposit in the Middle-Lower Yangtze Metallogenic Belt and sheds new light on the ore genesis of the deposit.Considering that infrared light may lead to non-negligible temperature deviations during microthermometry,some tests were first conducted to ensure the accuracy of the microthermometric measurements.The measurement results indicated that using the lowest light intensity of the microscope and inserting an optical filter were effective in minimizing the possible temperature deviations of infrared microthermometry.All sphalerite-hosted fluid inclusions from the Xinqiao deposit were aqueous.They show homogenization temperature ranging from~200 to 350℃,but have two separate salinity groups(1.0 wt%-10 wt%and 15.1 wt%-19.2 wt%NaCl equivalent).The low-salinity group represents sedimentary exhalative(SEDEX)-associated fluids,whereas the high-salinity group results from modification by later magmatic hydrothermal fluids.Combined with published fluid inclusion data,the four-stage fluid evolution of the Xinqiao deposit was depicted.Furthermore,our data suggest that the Xinqiao deposit was formed by twostage metallogenic events including SEDEX and magmatic-hydrothermal mineralization.展开更多
Interaction mechanism of the collector,2-mercaptobenzothiazole（MBT）,with chalcopyrite and sphalerite surfaces were investigated by Fourier transform infrared（FTIR） and density functional theory,Results of FTIR sho...Interaction mechanism of the collector,2-mercaptobenzothiazole（MBT）,with chalcopyrite and sphalerite surfaces were investigated by Fourier transform infrared（FTIR） and density functional theory,Results of FTIR showed that some characteristic peaks of MBT were observed on the chalcopyrite surface,including C=N,C=N-S and C-S stretching vibration peaks,and the adsorption product was CuMBT.But there were no characteristic peaks of MBT on the sphalerite surface.The thione molecular form of MBT was the most efficient and stable,N and exocyclic S were the more favourable reactive sites for nucleophilic attacked by metal atoms.Compared with ZnS（110）,MBT is more readily adsorbed on CuFeS2（112）.Attachment of MBT occurs due to strong bonding through exocyclic S p and s orbits with Cu d orbit on CuFeS2（112） and electron transfer from Cu atom to S atom.Under the vacuum condition,MBT in the form of thione molecular cannot be adsorbed on ZnS（110） spontaneously.展开更多
Iron is an impurity widely occurred in sphalerite,and its effect on sphalerite flotation is complex.In this work,the effects of iron content and spin state on electronic properties and floatability of iron-bearing sph...Iron is an impurity widely occurred in sphalerite,and its effect on sphalerite flotation is complex.In this work,the effects of iron content and spin state on electronic properties and floatability of iron-bearing sphalerite are comprehensively studied using density functional theory Hubbard U(DFT+U)calculations combined with coordination chemistry flotation.The band gap of ideal sphalerite is 3.723 eV,and thus electron transition is difficult to occur,resulting in poor floatability.The results suggest the band gap of sphalerite decreases with increasing iron content.For low iron content,the decreased band gap facilitates electron transition;at this case,Fe^(2+)in a high-spin state possesses oneπelectron pair,which can form a weakπ-backbonding with xanthate,causing increasing floatability.However,for medium and high iron-bearing sphalerite,with the further decrease of band gap,Fe^(2+)is oxidized to Fe^(3+)due to electrochemical interaction,and henceπ-backbonding is eliminated,leading to lower floatability of iron-bearing sphalerite,which is consistent with the flotation experimental results.This work could give a deeper understanding of how sphalerite flotation behaviors are affected by iron content.展开更多
Dating of lead-zinc deposits is of critical importance for better understanding of ore genesis, but has long been a big challenge due to the lack of suitable minerals that can be unequivocally linked to the ore genesi...Dating of lead-zinc deposits is of critical importance for better understanding of ore genesis, but has long been a big challenge due to the lack of suitable minerals that can be unequivocally linked to the ore genesis and that can be used for tradition radiometric methods. This kind of deposits have simple mineralogy dominated by galena and sphalerite commonly associated with calcite and other gangue minerals. Both galena and sphalerite have low and high variable Re concentrations and thus Re-Os dating of these minerals have been less promising. In addition, the recovery of Re is extremely low for galena when conventional method was applied, lending additional difficulty in precisely dating galena. In this study, we investigate the recovery of Re using different media for anion exchange separation and reporte a revised preparation method for Re-Os dating of galena and sphalerite. By using the new protocol, two reliable Re-Os isochron ages of galena and sphalerite from the Fule（20.4±3.2 Ma） and Laochang（308±25 Ma） Pb-Zn deposits in Yunnan Province, SW China, are achieved.展开更多
The photocatalytic reductive capability of a natural semiconducting mineral, sphalerite has been studied for the first time. The sphalerite from the Huangshaping deposit of Hunan Province performed great photoreductiv...The photocatalytic reductive capability of a natural semiconducting mineral, sphalerite has been studied for the first time. The sphalerite from the Huangshaping deposit of Hunan Province performed great photoreductive capability that 91.95% of the Cr^6＋ was reduced under 9 h visible light irradiation, higher than the 70.58% under 9.5 h UV light irradiation. The highly reductive ability results from its super negative potential of electrons in the conduction band. Furthermore, Fe substitution for Zn introduces donor states, and the oxidation process of Fe^2＋ to Fe^3＋ makes it an effective hole-scavenger. Cd and Cu substitute for Zn also reduce the bandgap and help broaden the absorbing edge towards the visible light. These substituting metal ions in natural sphalerite make it a hyper-active photocatalyst and very attractive for solar energy utilization.展开更多
The electronic properties of sphalerite(110)surface bearing Fe,Mn and Cd impurities were calculated using density-functional theory,and the effects of impurities on the copper activation of sphalerite were investigate...The electronic properties of sphalerite(110)surface bearing Fe,Mn and Cd impurities were calculated using density-functional theory,and the effects of impurities on the copper activation of sphalerite were investigated.Calculated results indicate that both Fe and Mn impurities narrow the band gap of sphalerite surface and lead to the Fermi level shifting to conduction band.Impurity levels composed of Fe 3d and Mn 3d orbital appearing in band gap are beneficial to electrons transfer from the valence band to the conduction band and promote the surface conductivity and the electrochemical activity.The results show that Fe and Mn impurities cannot be replaced by Cu atom,which reduces the exchange sites(Zn)for Cu atom,hence Fe-and Mn-bearing sphalerites are hard to be activated by copper.Cd impurity has little effect on electronic structure of sphalerite surface;however,Cd atom is easily replaced by Cu atom,and this is the reason why the Cd-bearing sphalerite can be easily floated.展开更多
Environmentally friendly flotation reagent,polyaspartic acid(PAPA),was tested as a potential selective depressant in the flotation separation of chalcopyrite and Cu-activated sphalerite.The depression mechanism of PAP...Environmentally friendly flotation reagent,polyaspartic acid(PAPA),was tested as a potential selective depressant in the flotation separation of chalcopyrite and Cu-activated sphalerite.The depression mechanism of PAPA was revealed by contact angle measurements,Zeta potential measurements,Fourier transform infrared spectroscopy(FT-IR)analysis and inductively coupled plasma(ICP)measurement.The micro-flotation tests with single minerals showed that PAPA selectively depressed Cu-activated sphalerite,while chalcopyrite remained floatable.Moreover,a concentrate containing 31.40%Cu with a recovery of 92.43%was obtained in flotation tests of artificially mixed minerals.Results of contact angle measurements,Zeta potential measurements and FT-IR spectrum revealed that PAPA exerted a much stronger adsorption on Cu-activated sphalerite surface than on chalcopyrite surface,preventing the further adsorption of sodium diethyl dithiocarbamate(DDTC)on its surface.ICP measurements indicated that PAPA had an excellent complexing ability with Cu^(2+)in flotation pulp,weakening the activation of Cu species on sphalerite surface and producing selective depression.展开更多
The depression mechanism of zinc sulfate(ZnSO4)and sodium dimethyl dithiocarbamate(DMDC)as the combined depressant on sphalerite was investigated by micro-flotation experiments,ion complexing tests,contact angle tests...The depression mechanism of zinc sulfate(ZnSO4)and sodium dimethyl dithiocarbamate(DMDC)as the combined depressant on sphalerite was investigated by micro-flotation experiments,ion complexing tests,contact angle tests and X-ray photoelectron spectroscopy(XPS)analysis.The micro-flotation tests revealed that ZnSO4+DMDC had a better selective depression effect on sphalerite than using single ZnSO4 or DMDC.Ion complexing tests confirmed that DMDC had a strong complexing capacity with lead ions or hydroxy complexes.Contact angle tests illustrated that ZnSO4+DMDC makes the sphalerite surface more hydrophilic than ZnSO4 or DMDC.XPS analysis indicated that the combined depressant could prevent collector adsorbing on the Pb-activated sphalerite surface by a competitive adsorption method,while the combined depressant and collector were co-adsorbed on galena surface.展开更多
The electronic properties of sphalerite(110) surface with Zn-vacancy and S-vacancy were calculated by using density-functional theory,and the effects of vacancy defect on the copper activation of sphalerite were inves...The electronic properties of sphalerite(110) surface with Zn-vacancy and S-vacancy were calculated by using density-functional theory,and the effects of vacancy defect on the copper activation of sphalerite were investigated.The calculated results indicate that surface state occurs in the band gap of Zn-vacancy sphalerite,which is from the contribution of S 3p orbital at the first layer of the surface.The presence of S-vacancy results in surface state appearing near the Fermi level and the bottom of conductor band,which are composed of S 3p and Zn 4s orbital,respectively.The surface structure of Zn-vacancy sphalerite is more stable than S-vacancy surface due to the occupation of Zn-vacancy by Cu atoms;hence,the substitution reaction of Cu for Zn vacancy is easier than the substitution of Cu for Zn atoms with S-vacancy surface.展开更多
Due to the combined influences such as ore-forming temperature,fluid and metal sources,sphalerite tends to incorporate diverse contents of trace elements during the formation of different types of Lead-zinc(Pb-Zn)depo...Due to the combined influences such as ore-forming temperature,fluid and metal sources,sphalerite tends to incorporate diverse contents of trace elements during the formation of different types of Lead-zinc(Pb-Zn)deposits.Therefore,trace elements in sphalerite have long been utilized to distinguish Pb-Zn deposit types.However,previous discriminant diagrams usually contain two or three dimensions,which are limited to revealing the complicated interrelations between trace elements of sphalerite and the types of Pb-Zn deposits.In this study,we aim to prove that the sphalerite trace elements can be used to classify the Pb-Zn deposit types and extract key factors from sphalerite trace elements that can dis-criminate Pb-Zn deposit types using machine learning algorithms.A dataset of nearly 3600 sphalerite spot analyses from 95 Pb-Zn deposits worldwide determined by LA-ICP-MS was compiled from peer-reviewed publications,containing 12 elements(Mn,Fe,Co,Cu,Ga,Ge,Ag,Cd,In,Sn,Sb,and Pb)from 5 types,including Sedimentary Exhalative(SEDEX),Mississippi Valley Type(MVT),Volcanic Massive Sulfide(VMS),skarn,and epithermal deposits.Random Forests(RF)is applied to the data processing and the results show that trace elements of sphalerite can successfully discriminate different types of Pb-Zn deposits except for VMS deposits,most of which are falsely distinguished as skarn and epithermal types.To further discriminate VMS deposits,future studies could focus on enlarging the capacity of VMS deposits in datasets and applying other geological factors along with sphalerite trace elements when con-structing the classification model.RF’s feature importance and permutation feature importance were adopted to evaluate the element significance for classification.Besides,a visualized tool,t-distributed stochastic neighbor embedding(t-SNE),was used to verify the results of both classification and evalua-tion.The results presented here show that Mn,Co,and Ge display significant impacts on classification of Pb-Zn deposits and In,Ga,Sn,Cd,and Fe also have relatively important effects compared to the rest ele-ments,confirming that Pb-Zn deposits discrimination is mainly controlled by multi-elements in spha-lerite.Our study hence shows that machine learning algorithm can provide new insights into conventional geochemical analyses,inspiring future research on constructing classification models of mineral deposits using mineral geochemistry data.展开更多
The contents of Fe and Zn in natural sphalerite samples were determined by chemical titration and spectroscopic techniques(portable X-ray fluorescence(P-XRF) spectrometry, electron probe microanalysis with energy disp...The contents of Fe and Zn in natural sphalerite samples were determined by chemical titration and spectroscopic techniques(portable X-ray fluorescence(P-XRF) spectrometry, electron probe microanalysis with energy dispersive spectroscopy(EPMA-EDS), electron probe microanalysis with wavelength dispersive spectroscopy(EPMA-WDS), and time-of-flight secondary ion mass spectrometry(To F-SIMS)). Besides, the distribution of Fe and Zn in sphalerite samples was analyzed by imaging EPMA-WDS and imaging To F-SIMS. The results show that Fe and Zn contents determined by each spectroscopic technique have good linearity with those determined by chemical titration(R^2>0.77), and the R^2 values of Fe are generally greater than those of Zn. The imaging analysis results revealed that Fe and Zn are not uniformly distributed in the sphalerite.展开更多
Different natural sphalerites have a range of photocatalytic properties that can potentially be exploited for environmental remediation purposes.To develop value in the exploitation of sphalerite,samples were collecte...Different natural sphalerites have a range of photocatalytic properties that can potentially be exploited for environmental remediation purposes.To develop value in the exploitation of sphalerite,samples were collected from 19 ore deposits in China and characterized for their mineralogical and photocatalytic properties.X-ray diffraction(XRD) and electron probe micro analysis(EPMA) measurements indicated that all the natural sphalerites from various localities crystallized in cubic phases with various chemical compositions.The substitution of Fe for Zn ranged from 0.235% to 14.826% by weight,Mn from 0.004% to4.868%,Cu from 0.009% to 5.529% and Cd from 0.133% to 1.576%.As Fe became more abundant,the color of natural sphalerite darkened,becoming almost black;and higher Fe content was associated with stronger visible light absorption.Photoluminescence spectra showed emission mainly related to S-vacancies and progressively decreasing fluorescence intensity with increasing Fe content.Tests of the photocatalytic degradation of methyl orange indicated that the sample with the highest Cd content but moderate Fe content had the highest photocatalytic activity.Specifically,the degradation of Methyl Orange(30 mg/L)attained 82.11% efficiency under visible light irradiation for 4 hr of natural sphalerite with4.262% Fe and 1.576% Cd.Overall,the Fe content in sphalerite was found to contribute to the visible light absorption ability and the recombination rate of photo-generated electrons and holes,while substitution by Cd was observed to have a greater effect on the photocatalytic properties.These findings provide a scientific basis for the profitable utilization of base metal resources like sphalerite.展开更多
This study reports the sphalerite Rb-Sr age and LA-MC-ICP-MS in situ sulfur isotope analysis results of the Daliangzi Lead-Zinc Deposit in the Sichuan-Yunnan-Guizhou （SYG） triangle. Sphalerite Rb-Sr dating yields a ...This study reports the sphalerite Rb-Sr age and LA-MC-ICP-MS in situ sulfur isotope analysis results of the Daliangzi Lead-Zinc Deposit in the Sichuan-Yunnan-Guizhou （SYG） triangle. Sphalerite Rb-Sr dating yields a Mississippian age of 345.2±3.6 Ma （MSWD=I.4）, which is older than the published Late Triassic mineralization ages （230-200 Ma） of some other deposits. This indicates that at least two stages of lead-zinc mineralization have occurred in the SYG lead-zinc triangle. The first stage occurred in the Mississippian under an extensional environment, while the second stage occurred in the Late Triassic under a compressional environment. In situ sulfur isotope analysis of sphalerite growth zoning presents relatively large δ^34S values of 11.3‰-15.2‰ with small variations. The large δ^34S values indicate a reduced sulfur source of thermochemical reduction of seawater sulfates. Abundant organic matter in the black fracture zone possibly supplied reductants for thermochemical sulfate reduction （TSR） at the mineralization site. The small variation of δ^34S values suggests a slow and stable TSR process that could prevent the sudden supersaturation of sphalerite in the fluid and the resulting of fast participation. This is consistent with the well-crystallized characteristic of the sphalerite of the Daliangzi Deposit.展开更多
This work presents a study for chemical leaching of sphalerite concentrate under various constant Fe3+ concentrations and redox potential conditions. The effects of Fe3+ concentration and redox potential on chemical l...This work presents a study for chemical leaching of sphalerite concentrate under various constant Fe3+ concentrations and redox potential conditions. The effects of Fe3+ concentration and redox potential on chemical leaching of sphalerite were investigated. The shrinking core model was applied to analyze the experimental results. It was found that both the Fe3+ concentration and the redox potential controlled the chemical leaching rate of sphalerite. A new kinetic model was developed, in which the chemical leaching rate of sphalerite was proportional to Fe3+ concentration and Fe3+ /Fe2+ ratio. All the model parameters were evaluated from the experimental data. The model predictions fit well with the experimental observed values.展开更多
The flotation tests and XPS analyses on galena,sphalerite and pyrite have been carried out in a collecting-depressing-reactivating system(hereafter referred as the CDR system).In this system,sulfide minerals were firs...The flotation tests and XPS analyses on galena,sphalerite and pyrite have been carried out in a collecting-depressing-reactivating system(hereafter referred as the CDR system).In this system,sulfide minerals were first collected and activated by the collector,and then depressed strongly by Ca(OH)2 in the strong alkaline solution,and finally reactivated by H2SO4.The flotation tests of pure minerals show that in this system the flotation behaviors of sphalerite and pyrite present irreversible characteristics along with the change of pulp potential.Furthermore,through the CDR system,considerable differences in the flotabilities between galena and sphalerite/pyrite are also observed.The XPS analysis results for galena,sphalerite and pyrite in a CDR system show that in the strong alkaline solution,some of the collectors,that have been already adsorbed on the mineral surface in the collecting process,are desorbed by Ca(OH)2.The XPS analysis results also show that in H2SO4 reactivating process,the surface hydroxides of galena are desorbed again by H2SO4 and replaced by diethyl dithiocarbamate,but those of sphalerite and pyrite are not desorbed.This flotation system may be applied to the bulk-differential flotation process of sulfur-bearing low-grade lead-zinc ores.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52074356)Open Foundation of State Key Laboratory of Mineral Processing(No.BGRIMM-KJSKL-2023-06)+5 种基金the National Key R&D Program of China(No.2022YFC2904500)the Science and Technology Innovation Program of Hunan Province,China(No.2022RC1183)Changsha Science and Technology Project,China(Outstanding Innovative Youth Training Program)Innovation driven program of Central South University(No.2023CXQD002)National 111 Project(No.B14034)the Fundamental Research Funds for the Central Universities of Central South University Project(No.50621747)。
文摘The depression mechanism of sulfite ions on sphalerite and Pb^(2+)activated sphalerite in the flotation separation of galena from sphalerite still lacked in-depth insight.Therefore,the depression mechanism of sulfite ions on sphalerite and Pb^(2+)activated sphalerite in the flotation separation of galena from sphalerite was further systematically investigated with experiments and density functional theory(DFT)calculations.The X-ray photoelectric spectroscopy(XPS)results,DFT calculation results,and frontier molecular orbital analysis indicated that sulfite ions were difficult to be adsorbed on sphalerite surface,suggesting that sulfite ions achieved depression effects on sphalerite through other non-adsorption mechanisms.First,the oxygen content in the surface of sphalerite treated with sulfite ions in creased,which enhanced the hydrophilicity of the sphalerite and further increased the difference in hydrophilicity between sphalerite and galena.Then,sulfite ions were chelated with lead ions to form PbSO_(3)in solution.The hydrophilic PbSO_(3)was more easily adsorbed on sphalerite than galena.The interaction between sulfite ions and lead ions could effectively inhibit the activation of sphalerite.In addition the UV spectrum showed that after adding sulfite ions,the peak of perxanthate in the sphalerite treated xanthate solution was significantly stronger than that in the galena with xanthate solution,indicating that xanthate interacted more readily with sulfite ions and oxygen mo lecules within the sphalerite system,leading to the formation of perxanthate.However,sulfite ions hardly depressed the flotation of ga lena and could promote the flotation of galena to some extent.This study deepened the understanding of the depression mechanism o sulfite ions on sphalerite and Pb^(2+)activated sphalerite.
基金supports from the National Natural Science Foundation of China(No.52174272)the Fundamental Research Funds for the Central Universities of Central South University,China(No.2021zzts0306)the Hunan Provincial Natural Science Foundation of China(No.2020JJ5736).
文摘Tetrasodium iminodisuccinate(IDS)was used as an inhibitor in the separation of sphalerite and pyrite in the EX−Cu(II)(ethyl xanthate and Cu2+)system.The flotation test results demonstrated that IDS can effectively separate sphalerite and pyrite under low alkaline conditions.Furthermore,high-quality zinc concentrates with a Zn grade of 58.48%and a recovery of 91.24%through mixed mineral flotation were obtained.The fundamental mechanisms were investigated through surface wettability tests,adsorption capacity tests,LEIS,FTIR,and XPS.The results confirmed that IDS prevents the adsorption of EX on the surface of pyrite,thereby reducing the response and reactivity of pyrite.The introduction of IDS causes the detachment of Cu2+from the Cu-activated pyrite surface.This process allowed IDS to chelate with the Fe sites on the surface of pyrite through the-COO-and N-centered active groups.By contrast,IDS exhibits weaker adhesion on the surface of Cu-activated sphalerite,making it easily displaced by EX through competitive adsorption.
基金supported by the Postdoctoral Fellowship Program(Grade A)of China Postdoctoral Science Foundation(No.BX20240429)the National Science and Technology Major Project of the Ministry of Science and Technology of China(No.2024ZD1004007)+3 种基金the National Key R&D Program of China(Nos.2022YFC2904502 and 2022YFC2904501)the National Natural Science Foundation of China(No.52204298)the Major Science and Technology Projects in Yunnan Province(No.202202AB080012)the High Performance Computing Center of Central South University。
文摘Herein,a first-principles investigation was innovatively conducted to research the surface oxidation of ZnS-like sphalerite in the absence and presence of H_(2)O .The findings showed that single O_(2) was preferred to be dissociated adsorption on sphalerite surface by generating SAO and Zn AO bonds,and the S atom on the surface was the most energy-supported site for O_(2) adsorption,on which a≡Zn-O-S-O-Zn≡structure will be formed.However,dissociated adsorption of single H_(2)O will not happen.It was preferred to be adsorbed on the top Zn atom on sphalerite surface in molecular form through Zn-O bond.Besides,sphalerite oxidation can occur as if O_(2) was present regardless of the presence of H_(2)O ,and when H_(2)O and O_(2) coexisted,the formation of sulfur oxide(SO_(2) )needed a lower energy barrier and it was easier to form on sphalerite surface than that only O_(2) existed.In the absence of H_(2)O ,when SO_(2) was generated,further oxidation of which would form neutral zinc sulfate.In the presence of H_(2)O ,the formation of SO_(2) on sphalerite surface was easier and the rate of further oxidation to form sulfate was also greater.Consequently,the occurrence of sphalerite oxidation was accelerated.
基金funded by National Key Research and Development Program(2024YFC2910400)the Second Tibetan Plateau Scientific Expedition and Research(2021QZKK0302)+1 种基金National Natural Science Foundation of China(42472115)the Chinese Geological Survey(DD20230008 and DD20230230)。
文摘Four Pb-Zn deposits,namely Bangpu(BP),Digei(DG),Nabuding(NB)and Cuoga(CG),are located within a 20 km distance of each other in the Gangdese porphyry copper belt(GPCB).The age and nature of the Pb-Zn mineralization,especially its relationship to magmatism,remain uncertain.In order to address this issue,mica from the four deposits was selected for in situ Rb-Sr dating,with sphalerite additionally being selected for in situ trace element analysis.Detailed geological research has revealed that the BP and NB deposits are primarily skarn-type Pb-Zn mineralization,while DG and CG are associated with magmatic hydrothermal breccia and are characterized by banded-type mineralization.The Rb-Sr isochron ages of syn-mineralization muscovite at the BP and CG deposits are 11±6 Ma and 19.7±0.7 Ma respectively.Fe,Cd,In,Mn and Sn occur as lattice substitutions in sphalerite from the four deposits.Cu exists as microinclusions in BP,but occurs isomorphically in the DG,NB and CG deposits.The formation temperatures of the four deposits,as calculated from sphalerite geothermometry,range from approximately 200℃to 300℃,indicating that they belong to medium temperature deposits.BP and NB are classified as skarn Pb-Zn deposits,while DG and CG are categorized as hydrothermal filled Pb-Zn deposits.These results suggest that,in addition to porphyry Cu mineralization,the GPCB also contains significant Miocene Pb-Zn mineralization.
基金Project(52204363)supported by the National Natural Science Foundation of ChinaProject(2024JJ8042)supported by the Hunan Natural Science Foundation,ChinaProject(22C0220)supported by the Education Department of Hunan Province,China。
文摘The lime-Cu^(2+)-xanthate process is commonly used for the flotation separation of sphalerite from pyrite.In this process,lime is added to the pulp to inhibit the floatability of pyrite.However,the excessive use of lime can result in pipeline blockage and inadequate recovery of associated precious metals.Therefore,it is necessary to develop new flotation process that minimizes or eliminates the use of lime.In this paper,a novel Fe^(3+)-Cu^(2+)-butyl xanthate process was developed as an alternative to lime for separating of sphalerite from pyrite.The flotation results indicated that with the artificially-mixed minerals,the flotation recovery of pyrite was lower than 16%and that of sphalerite was higher than 47%at pH 5.0−10.0.The zeta potential measurements revealed that ferric ion preferred to adsorb on pyrite,and copper ion displaced with zinc ion from the lattice at the interface of sphalerite.The wettability analyses indicated that the hydrophobicity of sphalerite surface increased apparently after being treated with Fe^(3+)-Cu^(2+)-BX,while the hydrophobicity of pyrite surface remained nearly unchanged.With XPS analysis,Cu-S bond and hydrophilic ferric hydroxide were detected separately on the surface of sphalerite and pyrite after conditioning with Fe^(3+)-Cu^(2+)-BX,which facilitated the flotation separation of sphalerite from pyrite with butyl xanthate collector.
基金supported by the National Key R&D Program of China(2018YFA0702701)the Fundamental Research Funds for the Central Universities(WK3410000015).
文摘Infrared microthermometry allows direct measurement of fluid inclusions hosted in opaque ore minerals and can provide direct constraints on the evolution of ore-forming fluids.This study presents infrared microthermometry of spherite-hosted fluid inclusions from the Xinqiao deposit in the Middle-Lower Yangtze Metallogenic Belt and sheds new light on the ore genesis of the deposit.Considering that infrared light may lead to non-negligible temperature deviations during microthermometry,some tests were first conducted to ensure the accuracy of the microthermometric measurements.The measurement results indicated that using the lowest light intensity of the microscope and inserting an optical filter were effective in minimizing the possible temperature deviations of infrared microthermometry.All sphalerite-hosted fluid inclusions from the Xinqiao deposit were aqueous.They show homogenization temperature ranging from~200 to 350℃,but have two separate salinity groups(1.0 wt%-10 wt%and 15.1 wt%-19.2 wt%NaCl equivalent).The low-salinity group represents sedimentary exhalative(SEDEX)-associated fluids,whereas the high-salinity group results from modification by later magmatic hydrothermal fluids.Combined with published fluid inclusion data,the four-stage fluid evolution of the Xinqiao deposit was depicted.Furthermore,our data suggest that the Xinqiao deposit was formed by twostage metallogenic events including SEDEX and magmatic-hydrothermal mineralization.
基金Project(51274255)supported by the National Natural Science Foundation of ChinaProject(502042012)supported by the Postdoctoral Research Station of Central South University,ChinaProject supported by Co-Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources,China
文摘Interaction mechanism of the collector,2-mercaptobenzothiazole（MBT）,with chalcopyrite and sphalerite surfaces were investigated by Fourier transform infrared（FTIR） and density functional theory,Results of FTIR showed that some characteristic peaks of MBT were observed on the chalcopyrite surface,including C=N,C=N-S and C-S stretching vibration peaks,and the adsorption product was CuMBT.But there were no characteristic peaks of MBT on the sphalerite surface.The thione molecular form of MBT was the most efficient and stable,N and exocyclic S were the more favourable reactive sites for nucleophilic attacked by metal atoms.Compared with ZnS（110）,MBT is more readily adsorbed on CuFeS2（112）.Attachment of MBT occurs due to strong bonding through exocyclic S p and s orbits with Cu d orbit on CuFeS2（112） and electron transfer from Cu atom to S atom.Under the vacuum condition,MBT in the form of thione molecular cannot be adsorbed on ZnS（110） spontaneously.
基金This work was supported by the National Natural Science Foundation of People’s Republic of China(No.NSFC52174246)the Interdisciplinary Scientific Research Foundation of Guangxi University(No.2022JCC016).
文摘Iron is an impurity widely occurred in sphalerite,and its effect on sphalerite flotation is complex.In this work,the effects of iron content and spin state on electronic properties and floatability of iron-bearing sphalerite are comprehensively studied using density functional theory Hubbard U(DFT+U)calculations combined with coordination chemistry flotation.The band gap of ideal sphalerite is 3.723 eV,and thus electron transition is difficult to occur,resulting in poor floatability.The results suggest the band gap of sphalerite decreases with increasing iron content.For low iron content,the decreased band gap facilitates electron transition;at this case,Fe^(2+)in a high-spin state possesses oneπelectron pair,which can form a weakπ-backbonding with xanthate,causing increasing floatability.However,for medium and high iron-bearing sphalerite,with the further decrease of band gap,Fe^(2+)is oxidized to Fe^(3+)due to electrochemical interaction,and henceπ-backbonding is eliminated,leading to lower floatability of iron-bearing sphalerite,which is consistent with the flotation experimental results.This work could give a deeper understanding of how sphalerite flotation behaviors are affected by iron content.
基金supported by the 12th Five-Year Plan Projects of State Key Laboratory of Ore Deposit Geochemistry, Chinese Academy of Sciences (Nos. SKLODG-ZY125-09, SKLODG-ZY125-02)the National Natural Science Foundation of China (Nos. 41373064, 41102053 and 41163001)the Science and Technology Plan Project of Yunnan Province (No. 2009CD029)
文摘Dating of lead-zinc deposits is of critical importance for better understanding of ore genesis, but has long been a big challenge due to the lack of suitable minerals that can be unequivocally linked to the ore genesis and that can be used for tradition radiometric methods. This kind of deposits have simple mineralogy dominated by galena and sphalerite commonly associated with calcite and other gangue minerals. Both galena and sphalerite have low and high variable Re concentrations and thus Re-Os dating of these minerals have been less promising. In addition, the recovery of Re is extremely low for galena when conventional method was applied, lending additional difficulty in precisely dating galena. In this study, we investigate the recovery of Re using different media for anion exchange separation and reporte a revised preparation method for Re-Os dating of galena and sphalerite. By using the new protocol, two reliable Re-Os isochron ages of galena and sphalerite from the Fule（20.4±3.2 Ma） and Laochang（308±25 Ma） Pb-Zn deposits in Yunnan Province, SW China, are achieved.
基金the National Natural Science Foundation of China （Grant No. 40572022）.
文摘The photocatalytic reductive capability of a natural semiconducting mineral, sphalerite has been studied for the first time. The sphalerite from the Huangshaping deposit of Hunan Province performed great photoreductive capability that 91.95% of the Cr^6＋ was reduced under 9 h visible light irradiation, higher than the 70.58% under 9.5 h UV light irradiation. The highly reductive ability results from its super negative potential of electrons in the conduction band. Furthermore, Fe substitution for Zn introduces donor states, and the oxidation process of Fe^2＋ to Fe^3＋ makes it an effective hole-scavenger. Cd and Cu substitute for Zn also reduce the bandgap and help broaden the absorbing edge towards the visible light. These substituting metal ions in natural sphalerite make it a hyper-active photocatalyst and very attractive for solar energy utilization.
基金Project(50864001) supported by the National Natural Science Foundation of China
文摘The electronic properties of sphalerite(110)surface bearing Fe,Mn and Cd impurities were calculated using density-functional theory,and the effects of impurities on the copper activation of sphalerite were investigated.Calculated results indicate that both Fe and Mn impurities narrow the band gap of sphalerite surface and lead to the Fermi level shifting to conduction band.Impurity levels composed of Fe 3d and Mn 3d orbital appearing in band gap are beneficial to electrons transfer from the valence band to the conduction band and promote the surface conductivity and the electrochemical activity.The results show that Fe and Mn impurities cannot be replaced by Cu atom,which reduces the exchange sites(Zn)for Cu atom,hence Fe-and Mn-bearing sphalerites are hard to be activated by copper.Cd impurity has little effect on electronic structure of sphalerite surface;however,Cd atom is easily replaced by Cu atom,and this is the reason why the Cd-bearing sphalerite can be easily floated.
基金financial supports from the National Natural Science Foundation of China(Nos.51974364,51904339)Hunan Province for Clean and Efficient Utilization of Strategic Calcium-containing Mineral,China(No.2018TP1002)。
文摘Environmentally friendly flotation reagent,polyaspartic acid(PAPA),was tested as a potential selective depressant in the flotation separation of chalcopyrite and Cu-activated sphalerite.The depression mechanism of PAPA was revealed by contact angle measurements,Zeta potential measurements,Fourier transform infrared spectroscopy(FT-IR)analysis and inductively coupled plasma(ICP)measurement.The micro-flotation tests with single minerals showed that PAPA selectively depressed Cu-activated sphalerite,while chalcopyrite remained floatable.Moreover,a concentrate containing 31.40%Cu with a recovery of 92.43%was obtained in flotation tests of artificially mixed minerals.Results of contact angle measurements,Zeta potential measurements and FT-IR spectrum revealed that PAPA exerted a much stronger adsorption on Cu-activated sphalerite surface than on chalcopyrite surface,preventing the further adsorption of sodium diethyl dithiocarbamate(DDTC)on its surface.ICP measurements indicated that PAPA had an excellent complexing ability with Cu^(2+)in flotation pulp,weakening the activation of Cu species on sphalerite surface and producing selective depression.
基金Projects(51974364,51904339)supported by the National Natural Science Foundation of ChinaProject(2018TP1002)supported by the Hunan Province for Clean and Efficiency Utilization of Strategic Calcium-containing Mineral,China。
文摘The depression mechanism of zinc sulfate(ZnSO4)and sodium dimethyl dithiocarbamate(DMDC)as the combined depressant on sphalerite was investigated by micro-flotation experiments,ion complexing tests,contact angle tests and X-ray photoelectron spectroscopy(XPS)analysis.The micro-flotation tests revealed that ZnSO4+DMDC had a better selective depression effect on sphalerite than using single ZnSO4 or DMDC.Ion complexing tests confirmed that DMDC had a strong complexing capacity with lead ions or hydroxy complexes.Contact angle tests illustrated that ZnSO4+DMDC makes the sphalerite surface more hydrophilic than ZnSO4 or DMDC.XPS analysis indicated that the combined depressant could prevent collector adsorbing on the Pb-activated sphalerite surface by a competitive adsorption method,while the combined depressant and collector were co-adsorbed on galena surface.
基金Project(50864001) supported by the National Natural Science Foundation of China
文摘The electronic properties of sphalerite(110) surface with Zn-vacancy and S-vacancy were calculated by using density-functional theory,and the effects of vacancy defect on the copper activation of sphalerite were investigated.The calculated results indicate that surface state occurs in the band gap of Zn-vacancy sphalerite,which is from the contribution of S 3p orbital at the first layer of the surface.The presence of S-vacancy results in surface state appearing near the Fermi level and the bottom of conductor band,which are composed of S 3p and Zn 4s orbital,respectively.The surface structure of Zn-vacancy sphalerite is more stable than S-vacancy surface due to the occupation of Zn-vacancy by Cu atoms;hence,the substitution reaction of Cu for Zn vacancy is easier than the substitution of Cu for Zn atoms with S-vacancy surface.
基金We would like to acknowledge the financial support of the Ministry of Science and Technology of China(Grant No.2021YFC2900300)the National Natural Science Foundation of China(Grant Nos.41772074 and 42172103).
文摘Due to the combined influences such as ore-forming temperature,fluid and metal sources,sphalerite tends to incorporate diverse contents of trace elements during the formation of different types of Lead-zinc(Pb-Zn)deposits.Therefore,trace elements in sphalerite have long been utilized to distinguish Pb-Zn deposit types.However,previous discriminant diagrams usually contain two or three dimensions,which are limited to revealing the complicated interrelations between trace elements of sphalerite and the types of Pb-Zn deposits.In this study,we aim to prove that the sphalerite trace elements can be used to classify the Pb-Zn deposit types and extract key factors from sphalerite trace elements that can dis-criminate Pb-Zn deposit types using machine learning algorithms.A dataset of nearly 3600 sphalerite spot analyses from 95 Pb-Zn deposits worldwide determined by LA-ICP-MS was compiled from peer-reviewed publications,containing 12 elements(Mn,Fe,Co,Cu,Ga,Ge,Ag,Cd,In,Sn,Sb,and Pb)from 5 types,including Sedimentary Exhalative(SEDEX),Mississippi Valley Type(MVT),Volcanic Massive Sulfide(VMS),skarn,and epithermal deposits.Random Forests(RF)is applied to the data processing and the results show that trace elements of sphalerite can successfully discriminate different types of Pb-Zn deposits except for VMS deposits,most of which are falsely distinguished as skarn and epithermal types.To further discriminate VMS deposits,future studies could focus on enlarging the capacity of VMS deposits in datasets and applying other geological factors along with sphalerite trace elements when con-structing the classification model.RF’s feature importance and permutation feature importance were adopted to evaluate the element significance for classification.Besides,a visualized tool,t-distributed stochastic neighbor embedding(t-SNE),was used to verify the results of both classification and evalua-tion.The results presented here show that Mn,Co,and Ge display significant impacts on classification of Pb-Zn deposits and In,Ga,Sn,Cd,and Fe also have relatively important effects compared to the rest ele-ments,confirming that Pb-Zn deposits discrimination is mainly controlled by multi-elements in spha-lerite.Our study hence shows that machine learning algorithm can provide new insights into conventional geochemical analyses,inspiring future research on constructing classification models of mineral deposits using mineral geochemistry data.
基金Projects(51764022,51404119)supported by the National Natural Science Foundation of ChinaProject(161046)supported by Fok Ying Tong Education Foundation,ChinaProject(2018M632810)supported by China Postdoctoral Science Foundation。
文摘The contents of Fe and Zn in natural sphalerite samples were determined by chemical titration and spectroscopic techniques(portable X-ray fluorescence(P-XRF) spectrometry, electron probe microanalysis with energy dispersive spectroscopy(EPMA-EDS), electron probe microanalysis with wavelength dispersive spectroscopy(EPMA-WDS), and time-of-flight secondary ion mass spectrometry(To F-SIMS)). Besides, the distribution of Fe and Zn in sphalerite samples was analyzed by imaging EPMA-WDS and imaging To F-SIMS. The results show that Fe and Zn contents determined by each spectroscopic technique have good linearity with those determined by chemical titration(R^2>0.77), and the R^2 values of Fe are generally greater than those of Zn. The imaging analysis results revealed that Fe and Zn are not uniformly distributed in the sphalerite.
基金supported by the National Key Basic Research Program of China (973 Program,No.410020010).
文摘Different natural sphalerites have a range of photocatalytic properties that can potentially be exploited for environmental remediation purposes.To develop value in the exploitation of sphalerite,samples were collected from 19 ore deposits in China and characterized for their mineralogical and photocatalytic properties.X-ray diffraction(XRD) and electron probe micro analysis(EPMA) measurements indicated that all the natural sphalerites from various localities crystallized in cubic phases with various chemical compositions.The substitution of Fe for Zn ranged from 0.235% to 14.826% by weight,Mn from 0.004% to4.868%,Cu from 0.009% to 5.529% and Cd from 0.133% to 1.576%.As Fe became more abundant,the color of natural sphalerite darkened,becoming almost black;and higher Fe content was associated with stronger visible light absorption.Photoluminescence spectra showed emission mainly related to S-vacancies and progressively decreasing fluorescence intensity with increasing Fe content.Tests of the photocatalytic degradation of methyl orange indicated that the sample with the highest Cd content but moderate Fe content had the highest photocatalytic activity.Specifically,the degradation of Methyl Orange(30 mg/L)attained 82.11% efficiency under visible light irradiation for 4 hr of natural sphalerite with4.262% Fe and 1.576% Cd.Overall,the Fe content in sphalerite was found to contribute to the visible light absorption ability and the recombination rate of photo-generated electrons and holes,while substitution by Cd was observed to have a greater effect on the photocatalytic properties.These findings provide a scientific basis for the profitable utilization of base metal resources like sphalerite.
基金financially supported by the China Geological Survey (No. 12120114019701)the Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan)
文摘This study reports the sphalerite Rb-Sr age and LA-MC-ICP-MS in situ sulfur isotope analysis results of the Daliangzi Lead-Zinc Deposit in the Sichuan-Yunnan-Guizhou （SYG） triangle. Sphalerite Rb-Sr dating yields a Mississippian age of 345.2±3.6 Ma （MSWD=I.4）, which is older than the published Late Triassic mineralization ages （230-200 Ma） of some other deposits. This indicates that at least two stages of lead-zinc mineralization have occurred in the SYG lead-zinc triangle. The first stage occurred in the Mississippian under an extensional environment, while the second stage occurred in the Late Triassic under a compressional environment. In situ sulfur isotope analysis of sphalerite growth zoning presents relatively large δ^34S values of 11.3‰-15.2‰ with small variations. The large δ^34S values indicate a reduced sulfur source of thermochemical reduction of seawater sulfates. Abundant organic matter in the black fracture zone possibly supplied reductants for thermochemical sulfate reduction （TSR） at the mineralization site. The small variation of δ^34S values suggests a slow and stable TSR process that could prevent the sudden supersaturation of sphalerite in the fluid and the resulting of fast participation. This is consistent with the well-crystallized characteristic of the sphalerite of the Daliangzi Deposit.
基金Supported by the National Basic Research Program （2010CB630902, 2004CB619202） the National Natural Science Foundation of China （31070034, 30800011, 31260396）+1 种基金 the Knowledge Innovation Program of CAS （2AKSCX2-YW-JS401） the Reward Fund for Young Scientists of Shandong Province （2007BS08002） of China
文摘This work presents a study for chemical leaching of sphalerite concentrate under various constant Fe3+ concentrations and redox potential conditions. The effects of Fe3+ concentration and redox potential on chemical leaching of sphalerite were investigated. The shrinking core model was applied to analyze the experimental results. It was found that both the Fe3+ concentration and the redox potential controlled the chemical leaching rate of sphalerite. A new kinetic model was developed, in which the chemical leaching rate of sphalerite was proportional to Fe3+ concentration and Fe3+ /Fe2+ ratio. All the model parameters were evaluated from the experimental data. The model predictions fit well with the experimental observed values.
基金Project(2008BAE60B00) supported by the National Science & Technology Pillar Program during the Eleventh Five-year Plan Period,China
文摘The flotation tests and XPS analyses on galena,sphalerite and pyrite have been carried out in a collecting-depressing-reactivating system(hereafter referred as the CDR system).In this system,sulfide minerals were first collected and activated by the collector,and then depressed strongly by Ca(OH)2 in the strong alkaline solution,and finally reactivated by H2SO4.The flotation tests of pure minerals show that in this system the flotation behaviors of sphalerite and pyrite present irreversible characteristics along with the change of pulp potential.Furthermore,through the CDR system,considerable differences in the flotabilities between galena and sphalerite/pyrite are also observed.The XPS analysis results for galena,sphalerite and pyrite in a CDR system show that in the strong alkaline solution,some of the collectors,that have been already adsorbed on the mineral surface in the collecting process,are desorbed by Ca(OH)2.The XPS analysis results also show that in H2SO4 reactivating process,the surface hydroxides of galena are desorbed again by H2SO4 and replaced by diethyl dithiocarbamate,but those of sphalerite and pyrite are not desorbed.This flotation system may be applied to the bulk-differential flotation process of sulfur-bearing low-grade lead-zinc ores.
