The effects of pre-compression and pre-aging on the age-hardening response and microstructure of Mg-9.8Sn3.0 Zn(wt.%)alloy have been investigated via hardness test and advanced electron microscopy.The alloy subjected ...The effects of pre-compression and pre-aging on the age-hardening response and microstructure of Mg-9.8Sn3.0 Zn(wt.%)alloy have been investigated via hardness test and advanced electron microscopy.The alloy subjected to both pre-compression and pre-aging exhibits the most refined and densest distribution of precipitates upon aging at 200℃,leading to the superior age-hardening performance observed in the alloy.Comparatively,the alloy that underwent only pre-aging displayed a greater number density of precipitates than its counterpart that was neither pre-compressed nor pre-aged when both were aged to their peak conditions at 200℃,indicating an enhanced age-hardening response in the pre-aged alloy.The precipitates in these three peak-aged alloys consist of Mg_(2)Sn and MgZn_(2)phases.The reason why the pre-aged alloy has a higher number density of precipitates than the directly aged alloy is that MgZn_(2)phase formed during pre-aging can serve as heterogeneous nucleation site for the formation of Mg_(2)Sn.The reason why the pre compression and pre-aged alloy has the highest number density of precipitates is that Mg_(3)Sn and MgZn_(2)phases formed during pre-aging,alongside lattice defects introduced during pre-compression,collectively act as effective heterogeneous nucleation sites for the formation of Mg_(2)Sn during the subsequent aging at 200℃.展开更多
Graphitic carbon nitride(g-C_(3)N_(4))exhibits great mechanical as well as thermal characteristics,making it a valuable ma-terial for use in photoelectric conversion devices,an accelerator for synthesis of organic com...Graphitic carbon nitride(g-C_(3)N_(4))exhibits great mechanical as well as thermal characteristics,making it a valuable ma-terial for use in photoelectric conversion devices,an accelerator for synthesis of organic compounds,an electrolyte for fuel cell applications or power sources,and a hydrogen storage substance and a fluorescence detector.It is fabricated using dif-ferent methods,and there is a variety of morphologies and nanostructures such as zero to three dimensions that have been designed for different purposes.Ther e are many reports about g-C_(3)N_(4) in recent years,but a comprehensive review which covers nanostructure dimensions and their properties are missing.This review paper aims to give basic and comprehensive understanding of the photocatalytic and electrocatalytic usages of g-C_(3)N_(4).It highlights the recent progress of g-C_(3)N_(4) nano-structure designing by covering synthesis methods,dimensions,morphologies,applications and properties.Along with the summary,we will also discuss the challenges and prospects.Scientists,investigators,and engineers looking at g-C_(3)N_(4) nanostructures for a variety of applications might find our review paper to be a useful resource.展开更多
The enhancement of chalcopyrite bioleaching with an enriched microbial community by acidified seawater was studied,and the enhancing mechanism was analyzed.The microbial community was enriched at the Dabaoshan mine si...The enhancement of chalcopyrite bioleaching with an enriched microbial community by acidified seawater was studied,and the enhancing mechanism was analyzed.The microbial community was enriched at the Dabaoshan mine site,and the treated ore sample had high concentrations of chalcopyrite and galena.The experimental results show that copper extraction from chalcopyrite with an enriched microbial community in seawater was promoted from 13.1%to 62.1%by acidification in comparison with that without acidification.Further analyses of the solutions,solid residues and microbial compositions by scanning electron microscopy,X-ray diffraction,Raman spectroscopy,Fourier transform infrared spectroscopy and 16 S rDNA sequencing revealed the promoting effects of acidified seawater.This acidification can increase the biodissolution of chalcopyrite to increase the concentration of iron ions and maintain the redox potential in the range of 360−410 mV.The latter produces an optimal redox environment conducive to chalcopyrite dissolution via Cu_(2)S.The adaptability of the microbial community to a high-salt environment is improved.Chloride ions at 580 mmol/L improve the leaching kinetics of chalcopyrite by increasing the porosity and noncrystallinity of the intermediate elemental sulfur.This study provides a promising way to bioleaching copper minerals using seawater for areas with freshwater shortages.展开更多
The hydrazine oxidation reaction(HzOR)has garnered significant attention as a feasible approach to replace sluggish anodic reactions to save energy.Nevertheless,there are still difficulties in developing highly effici...The hydrazine oxidation reaction(HzOR)has garnered significant attention as a feasible approach to replace sluggish anodic reactions to save energy.Nevertheless,there are still difficulties in developing highly efficient catalysts for the HzOR.Herein,we report amorphous ruthenium nanosheets(a-Ru NSs)with a thickness of approximately 9.6 nm.As a superior bifunctional electrocatalyst,a-Ru NSs exhibited enhanced electrocatalytic performance toward both the HzOR and hydrogen evolution reaction(HER),outperforming benchmark Pt/C catalysts,where the a-Ru NSs achieved a work-ing potential of merely-76 mV and a low overpotential of only 17 mV to attain a current density of 10 mA·cm^(-2) for the HzOR and HER,respectively.Furthermore,a-Ru NSs displayed a low cell voltage of 28 mV at 10 mA·cm^(-2) for overall hy-drazine splitting in a two-electrode electrolyzer.In situ Raman spectra revealed that the a-Ru NSs can efficiently promote N‒N bond cleavage,thereby producing more*NH_(2)and accelerating the progress of the reaction.展开更多
In this study,a synergistic sulfidation-acid leaching process was proposed to recover valuable metals from gypsum residue and zinc-containing fume.The equilibrium phase composition of the sulfidation reaction and calc...In this study,a synergistic sulfidation-acid leaching process was proposed to recover valuable metals from gypsum residue and zinc-containing fume.The equilibrium phase composition of the sulfidation reaction and calculations of the thermodynamic stability region show that 89.36%Zn,>99%Pb and>99%Cu of gypsum residue and zinc-containing fume can be sulfured to ZnS,PbS and Cu 2 S,under sufficient sulfur partial pressure,low oxygen partial pressure and 400-1000℃.Sulfidation roasting experiments show that the sulfidation rate of Cu,Pb and Zn reach 81.43%,88.25% and 92.31%,respectively,under the roasting conditions of material mass ratio of 30 g:10 g,carbon dosage of 3.75 g,roasting temperature of 800℃ for 3 h.E−pH plots show that ZnS,PbS and Cu_(2)S can be enriched in the leaching residue,under leaching conditions at 25℃,pH<4 and-0.4 V<φ(E)<0.04 V.The leaching experiments showed that the sulfide is retained in the leaching residue,while the leaching rates of Cu,Pb and Zn are 1.94%,2.05% and 1.51%,respectively,under the conditions of 25℃,C_(HCl) of 0.5 mol/L,L/S of 5 mL/g,stirring rate of 300 r/min,and stirring time of 30 min.This study provides a new approach for the synergistic disposal of gypsum residue and zinc containing fume.展开更多
Microstructure and mechanical properties of aged Mg-10Gd-2Y-0.4Zr-0.4Ag alloy sheets prepared by different rolling routes were investigated.The results showed that the cross rolling aged(CRA)sheet possesses larger gra...Microstructure and mechanical properties of aged Mg-10Gd-2Y-0.4Zr-0.4Ag alloy sheets prepared by different rolling routes were investigated.The results showed that the cross rolling aged(CRA)sheet possesses larger grain size than unidirectional rolling aged(URA)sheet due to the occurrence of dynamic recovery during rolling which reduces the dislocation density and delays dynamic recrystallization(DRX).The URA sheet has basal texture and RD favored texture while CRA sheet has multiple-peak texture.Both sheets precipitate β'phase and CRA sheet exhibits a stronger aging response.The CRA sheet has higher yield strength and tensile strength than URA sheet,with reduced yield strength anisotropy but increased tensile strength anisotropy.Taking into account different strengthening mechanisms,although the finer grain size of URA sheet enhances grain boundary strengthening,CRA sheet is more responsive to aging,leading to superior aging-precipitated phase strengthening and consequently higher yield strength.展开更多
The addition of NaCl in the ammonium persulfate-APS(as an oxidant)leaching was investigated.APS has some advantages compared with conventional oxidants and its standard redox potential(E°)is2.0V.Effect of six par...The addition of NaCl in the ammonium persulfate-APS(as an oxidant)leaching was investigated.APS has some advantages compared with conventional oxidants and its standard redox potential(E°)is2.0V.Effect of six parameters such as NaCl concentration,APS concentration,temperature,time,liquid–solid ration(L/S),and stirring speed on the leaching behavior was studied.Results showed that metals extraction increased with increasing of NaCl concentration,APS concentration,leaching temperature(up to333K),and L/S ratio.During oxidative leaching of sulfide minerals,the occurrence of elemental sulfur layer on particle surface is known as primary problem that causes low metal extraction.According to the results,the passivation effect of sulfur layer and low dissolution problems can be eliminated in the presence of chloride ions.Copper and iron extraction yields were obtained as75%and80%,respectively under leaching conditions as follows:APS concentration250g/L;NaCl concentration150g/L;time180min;temperature333K;stirring speed400r/min;and L/S250mL/g.展开更多
In the travel process of urban residents,travelers will take a series of activities such as imitation and exclusion by observing other people’s travel modes,which affects their following trips.This process can be see...In the travel process of urban residents,travelers will take a series of activities such as imitation and exclusion by observing other people’s travel modes,which affects their following trips.This process can be seen as a repeated game between members of the travelers.Based on the analysis of this game and its evolution trend,a multi-dimensional game model of low-carbon travel for residents is established.The two dimensional game strategies include whether to accept the low-carbon concept and whether to choose low-carbon travel.Combined with evolutionary game theory,the low-carbon travel choices of residents in different cities are simulated,and the evolutionary stability strategies are obtained.Finally,the influences of the main parameters of the model on the evolution process and stability strategies are discussed.The results show that travelers would develop towards two trends.Cities with more developed public traffic system have a higher proportion of receiving low-carbon concept and choosing low-carbon travel.Cities with underdeveloped public transport system could increase this proportion by some measures such as encouraging residents to choose slow transport and increasing the propaganda of low-carbon travel,but the positive effects of the measures like propaganda have a limited impact on the proportion.展开更多
A large amount of coal gangue from coal mining and processing is regarded as waste and usually stockpiled directly. In order to recycle the valuable elements from the coal gangue, an integrated process is proposed. Th...A large amount of coal gangue from coal mining and processing is regarded as waste and usually stockpiled directly. In order to recycle the valuable elements from the coal gangue, an integrated process is proposed. The process consists of three steps: 1concentrating alumina from the coal gangue via activation roasting followed by alkali leaching of Si O2 which produces alumina concentrate for alumina extraction by the Bayer process; 2) synthesizing tobermorite whiskers from the filtrated alkali liquo containing silicate via a hydrothermal method and reusing excess caustic liquor; and 3) enriching titanium component from the Baye process residue by sulfuric acid leaching. Alumina concentrate with 69.5% Al_2O_3 and mass ratio of alumina to silica(A/S) of 5.9pure 1.1 nm tobermorite whisker and TiO_2-rich material containing 33% TiO_2 are produced, respectively, with the optimal parameters Besides, the actual alumina digestion ratio of alumina concentrate reaches 80.4% at 270 oC for 40 min in the Bayer process.展开更多
The mechanism of oxygen pressure acid leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation was investigated in this study.Artificial sphalerite was fabricated with varying amounts of iron content via the ...The mechanism of oxygen pressure acid leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation was investigated in this study.Artificial sphalerite was fabricated with varying amounts of iron content via the sintering of ZnS and FeS and used for the pressure acid leaching experiment.The variations in the potential of the pressure leaching system were investigated by using a self-designed potential autoclave.The results showed that compared to the non-iron sphalerite,there was a violent redox reaction between the 25.70%Fe-artificial sphalerite and dissolved oxygen during the process of pressure leaching;and the catalytic mechanism was attributed to the redox couple Fe^3+/Fe^2+,where Fe3+oxidizes the H2S gas film and the reduced Fe2+state is subsequently oxidized by the dissolved oxygen.Furthermore,the effect of temperature,H2SO4 concentration,and oxygen partial pressure on the artificial sphalerite with different iron contents was studied.The sphalerite samples with iron content were observed to dissolve more easily in sulfuric acid compared to the non-iron samples.Moreover,the activation energy of artificial sphalerite was observed to be lower in the sample with 25.70%iron content(22.26 kJ/mol)compared to that with no iron(32.31 kJ/mol);and the apparent reaction orders were obtained with respect to H2SO4 concentration(1.10 and 1.36)and oxygen partial pressure(1.29 and 1.41),respectively.A comprehensive kinetic model was developed on the basis of the experimental data and the fitted leaching ratio plot;and the kinetic equations for the leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation were determined.展开更多
D2EHPA(P204),tri-butyl-phosphate(TBP)and sodium chloride(NaCl)were attractive for selective extraction of scandium from acid leaching solution of red mud.The extraction parameters of P204 concentration(X_(P204)),NaCl ...D2EHPA(P204),tri-butyl-phosphate(TBP)and sodium chloride(NaCl)were attractive for selective extraction of scandium from acid leaching solution of red mud.The extraction parameters of P204 concentration(X_(P204)),NaCl concentration(C_(NaCl)),pH value,reaction time,stirring speed and O/A were investigated to extract scandium and separate iron from the acid leaching solution.The extraction mechanism was analyzed by Fourier transform infrared spectroscopy(FT-IR)and thermodynamic theory.The single-stage extraction efficiency of scandium,iron andβ(Sc/Fe)were 99.1%,9.4%and 1061.2,respectively,with C_(NaCl) of 75 g/L and XP204 of 0.75 at solution pH value of 1.2 and stirring speed of 200 r/min for 6 min,in which a good separation effect of scandium and iron was obtained.The vibration absorption peak Sc─O was contributed to the extraction of scandium with P204.The complex[FeCln]^(3−n) existed in the solution with adding NaCl into the acid leaching solution.The value of n was higher and the valence state of the complex[FeCln]^(3−n) was lower with an increase of chloride concentration,which restricts the extraction efficiency of iron with P204.The extraction of three stages in the counter-current simulation experiments was carried out according to the McCabe-Thiele diagram.Gibbs free energy change(ΔG)of−5.93 kJ/mol,enthalpy change(ΔH)of 23.45 kJ/mol and entropy change(ΔH)of 98.54 J/(mol·K)were obtained in the solvent extraction proces,which indicate that the extraction reaction is easily spontaneous and endothermic and a proper increase of temperature is conducive to the extraction of scandium.展开更多
Alkali-leaching and acid-leaching were proposed for the dephosphorization of Changde iron ore, which contains an average of 1.12% for phosphorus content. Sodium hydroxide, sulfuriced, hydrochloric and nitric acids wer...Alkali-leaching and acid-leaching were proposed for the dephosphorization of Changde iron ore, which contains an average of 1.12% for phosphorus content. Sodium hydroxide, sulfuriced, hydrochloric and nitric acids were used for the preparation of leach solutions. The results show that phosphorus occurring as apatite phase could be removed by alkali-leaching, but those occurring in the iron phase could not. Sulfuric acid is the most effective among the three kinds of acid. 91.61% phosphorus removal was attained with 1% sulfuric acid after leaching for 20 rain at room temperature. Iron loss during acid-leaching can be negligible, which was less than 0.25%.The pH value of solution after leaching with1% sulfuric acid was about 0.86, which means acid would not be exhausted during the process and it could be recycled, and the recycle of sulfuric acid solution would make the dephosphorization process more economical.展开更多
The precipitation performance and kinetics of gibbsite from sodium aluminate solution with different sodium oxalate concentrations as well as the corresponding influence mechanism of oxalate during the seed precipitat...The precipitation performance and kinetics of gibbsite from sodium aluminate solution with different sodium oxalate concentrations as well as the corresponding influence mechanism of oxalate during the seed precipitation process were systematically investigated by physicochemical properties test,using SEM and Raman spectra.As the concentration of sodium oxalate increases,both the precipitation rate and particle size of gibbsite decrease.The presence of sodium oxalate not only increases the viscosity of sodium aluminate solution,but also promotes the transformation of Al(OH)4^? to Al2O(OH)6^2?.The overall reaction rate constant decreases and the apparent activation energy of gibbsite increases with the increasing sodium oxalate concentration,the rate controlling step of which is chemical reaction.The needle-like sodium oxalate precipitates on the gibbsite crystals and covers the active Al(OH)3 seed sites,which leads to the lower precipitation rate and the finer particle size of gibbsite during the seed precipitation process.展开更多
A hydrometallurgical process for indium extraction and ferric oxide powder preparation for soft magnetic ferrite material was developed. Using reduction lixivium from high-acid reductive leaching of zinc oxide calcine...A hydrometallurgical process for indium extraction and ferric oxide powder preparation for soft magnetic ferrite material was developed. Using reduction lixivium from high-acid reductive leaching of zinc oxide calcine as raw solution, copper and indium were firstly recovered by iron powder cementation and neutralization. The recovery ratios of Cu and In are 99% and 95%, respectively. Some harmful impurities that have negative influences on magnetic properties of soft magnetic ferrite material are deeply removed with sulfidization purification and neutral flocculation method. Under the optimum conditions, the content of impurities like Cu, Pb, As, Al in pure Zn-Fe sulfate solution are less than 0.004 g/L, but those of Cd, Si, Ca and Mg are relatively high. Finally, thermal precipitation of iron is carried out at 210 ℃ for 1.5 h. The precipitation ratio of Fe is 93.33%. Compared with the quality standard of ferric oxide for soft magnetic ferrite materials, the contents of Al and Mg in obtained ferric oxide powder meet the requirement of YHT1 level of ferric oxide, and those of Si, Ca meet the requirement of YHT3 level of ferric oxide. XRD and SEM characterizations confirm that the obtained sample is well-dispersed spindle spherule with regular a-Fe2O3 crystal structure. The length-to-diameter ratio ofa-Fe2O3 powder is （3-4）：1 with an average particle size of 0.5 μm.展开更多
Many researchers found that the Fe2+together with less amount of Cu2+can accelerate the leaching of chalcopyrite.In this work,the leaching of chalcopyrite with Cu2+was investigated.The leaching residuals were examined...Many researchers found that the Fe2+together with less amount of Cu2+can accelerate the leaching of chalcopyrite.In this work,the leaching of chalcopyrite with Cu2+was investigated.The leaching residuals were examined by Raman spectroscopy.Based on the leaching experiments,the chemical equilibrium in solution was calculated using Visual MINTEQ.The results showed that the Fe in chalcopyrite lattice was replaced by Cu2+;therefore,the chalcopyrite transformed into covellite.Furthermore,the formation of chalcocite occurred when Fe2+and Fe3+were added to the solution containing Cu2+.The copper extraction increased with a decrease of the initial redox potential(or the ratio of Fe3+/Fe2+).展开更多
A dual cell system was used to study the influence of chloride ions on the electrogenerative leaching of sulfide minerals. The results show that the influences of chloride ions on a series of electrogenerative leachin...A dual cell system was used to study the influence of chloride ions on the electrogenerative leaching of sulfide minerals. The results show that the influences of chloride ions on a series of electrogenerative leaching system are similar, and chlorine ion is involved in the electrogenerative leaching process of sulfide minerals directly. The output power increases with the increase of Cl^- concentration. The influence on the electrogenerative leaching rate decreases when the Cl^- concentration reaches a certain value. The mechanisms of anodic reaction are deduced based on the reasonable hypothesis, and kinetic equations with respect to chlorine ions for each sulfide mineral are obtained. The kinetic equations show that when concentration of Cl^- is relatively low, the electrogenerative leaching rates are predicted to have 2/5,3/7,1/3 and 1/3 order dependence on Cl^- concentration for chalcopyrite concentrate,nickel concentrate, sphalerite and galena. As concentration of Cl^- increases, the correlative dependence of electrogenerative leaching rate on concentration of Cl^- becomes weak.展开更多
基金Project(52101167)supported by the National Natural Science Foundation of ChinaProject(2022JJ40604)supported by the Natural Science Foundation of Hunan Province,ChinaProject(2022ZZTS0538)supported by the Postgraduate Research Innovation Project of Central South University,China。
文摘The effects of pre-compression and pre-aging on the age-hardening response and microstructure of Mg-9.8Sn3.0 Zn(wt.%)alloy have been investigated via hardness test and advanced electron microscopy.The alloy subjected to both pre-compression and pre-aging exhibits the most refined and densest distribution of precipitates upon aging at 200℃,leading to the superior age-hardening performance observed in the alloy.Comparatively,the alloy that underwent only pre-aging displayed a greater number density of precipitates than its counterpart that was neither pre-compressed nor pre-aged when both were aged to their peak conditions at 200℃,indicating an enhanced age-hardening response in the pre-aged alloy.The precipitates in these three peak-aged alloys consist of Mg_(2)Sn and MgZn_(2)phases.The reason why the pre-aged alloy has a higher number density of precipitates than the directly aged alloy is that MgZn_(2)phase formed during pre-aging can serve as heterogeneous nucleation site for the formation of Mg_(2)Sn.The reason why the pre compression and pre-aged alloy has the highest number density of precipitates is that Mg_(3)Sn and MgZn_(2)phases formed during pre-aging,alongside lattice defects introduced during pre-compression,collectively act as effective heterogeneous nucleation sites for the formation of Mg_(2)Sn during the subsequent aging at 200℃.
基金M Tahir is funded by EU H2020 Marie Skłodows-ka-Curie Fellowship(1439425).
文摘Graphitic carbon nitride(g-C_(3)N_(4))exhibits great mechanical as well as thermal characteristics,making it a valuable ma-terial for use in photoelectric conversion devices,an accelerator for synthesis of organic compounds,an electrolyte for fuel cell applications or power sources,and a hydrogen storage substance and a fluorescence detector.It is fabricated using dif-ferent methods,and there is a variety of morphologies and nanostructures such as zero to three dimensions that have been designed for different purposes.Ther e are many reports about g-C_(3)N_(4) in recent years,but a comprehensive review which covers nanostructure dimensions and their properties are missing.This review paper aims to give basic and comprehensive understanding of the photocatalytic and electrocatalytic usages of g-C_(3)N_(4).It highlights the recent progress of g-C_(3)N_(4) nano-structure designing by covering synthesis methods,dimensions,morphologies,applications and properties.Along with the summary,we will also discuss the challenges and prospects.Scientists,investigators,and engineers looking at g-C_(3)N_(4) nanostructures for a variety of applications might find our review paper to be a useful resource.
基金Project(2022YFC2105300)supported by the National Key Research and Development Program of ChinaProjects(41802038,51774342)supported by the National Natural Science Foundation of China。
文摘The enhancement of chalcopyrite bioleaching with an enriched microbial community by acidified seawater was studied,and the enhancing mechanism was analyzed.The microbial community was enriched at the Dabaoshan mine site,and the treated ore sample had high concentrations of chalcopyrite and galena.The experimental results show that copper extraction from chalcopyrite with an enriched microbial community in seawater was promoted from 13.1%to 62.1%by acidification in comparison with that without acidification.Further analyses of the solutions,solid residues and microbial compositions by scanning electron microscopy,X-ray diffraction,Raman spectroscopy,Fourier transform infrared spectroscopy and 16 S rDNA sequencing revealed the promoting effects of acidified seawater.This acidification can increase the biodissolution of chalcopyrite to increase the concentration of iron ions and maintain the redox potential in the range of 360−410 mV.The latter produces an optimal redox environment conducive to chalcopyrite dissolution via Cu_(2)S.The adaptability of the microbial community to a high-salt environment is improved.Chloride ions at 580 mmol/L improve the leaching kinetics of chalcopyrite by increasing the porosity and noncrystallinity of the intermediate elemental sulfur.This study provides a promising way to bioleaching copper minerals using seawater for areas with freshwater shortages.
基金supported by the National Key R&D Program of China(2018YFA0702001)National Natural Science Foundation of China(22371268,22301287)+3 种基金Fundamental Research Funds for the Central Universities(WK2060000016)Anhui Provincial Natural Science Foundation(2208085J09,2208085QB33)Collaborative Innovation Program of Hefei Science Center,CAS(2022HSC-CIP020)Youth Innovation Promotion Association of the Chinese Academy of Science(2018494)and USTC Tang Scholar.
文摘The hydrazine oxidation reaction(HzOR)has garnered significant attention as a feasible approach to replace sluggish anodic reactions to save energy.Nevertheless,there are still difficulties in developing highly efficient catalysts for the HzOR.Herein,we report amorphous ruthenium nanosheets(a-Ru NSs)with a thickness of approximately 9.6 nm.As a superior bifunctional electrocatalyst,a-Ru NSs exhibited enhanced electrocatalytic performance toward both the HzOR and hydrogen evolution reaction(HER),outperforming benchmark Pt/C catalysts,where the a-Ru NSs achieved a work-ing potential of merely-76 mV and a low overpotential of only 17 mV to attain a current density of 10 mA·cm^(-2) for the HzOR and HER,respectively.Furthermore,a-Ru NSs displayed a low cell voltage of 28 mV at 10 mA·cm^(-2) for overall hy-drazine splitting in a two-electrode electrolyzer.In situ Raman spectra revealed that the a-Ru NSs can efficiently promote N‒N bond cleavage,thereby producing more*NH_(2)and accelerating the progress of the reaction.
基金Projects(52174269,52374293)supported by the National Natural Science Foundation of ChinaProject(2022RC1123)supported by the Science and Technology Innovation Program of Hunan Province,China。
文摘In this study,a synergistic sulfidation-acid leaching process was proposed to recover valuable metals from gypsum residue and zinc-containing fume.The equilibrium phase composition of the sulfidation reaction and calculations of the thermodynamic stability region show that 89.36%Zn,>99%Pb and>99%Cu of gypsum residue and zinc-containing fume can be sulfured to ZnS,PbS and Cu 2 S,under sufficient sulfur partial pressure,low oxygen partial pressure and 400-1000℃.Sulfidation roasting experiments show that the sulfidation rate of Cu,Pb and Zn reach 81.43%,88.25% and 92.31%,respectively,under the roasting conditions of material mass ratio of 30 g:10 g,carbon dosage of 3.75 g,roasting temperature of 800℃ for 3 h.E−pH plots show that ZnS,PbS and Cu_(2)S can be enriched in the leaching residue,under leaching conditions at 25℃,pH<4 and-0.4 V<φ(E)<0.04 V.The leaching experiments showed that the sulfide is retained in the leaching residue,while the leaching rates of Cu,Pb and Zn are 1.94%,2.05% and 1.51%,respectively,under the conditions of 25℃,C_(HCl) of 0.5 mol/L,L/S of 5 mL/g,stirring rate of 300 r/min,and stirring time of 30 min.This study provides a new approach for the synergistic disposal of gypsum residue and zinc containing fume.
基金Project(2023GK2020)supported by the Key Research and Development Program of Hunan Province,China。
文摘Microstructure and mechanical properties of aged Mg-10Gd-2Y-0.4Zr-0.4Ag alloy sheets prepared by different rolling routes were investigated.The results showed that the cross rolling aged(CRA)sheet possesses larger grain size than unidirectional rolling aged(URA)sheet due to the occurrence of dynamic recovery during rolling which reduces the dislocation density and delays dynamic recrystallization(DRX).The URA sheet has basal texture and RD favored texture while CRA sheet has multiple-peak texture.Both sheets precipitate β'phase and CRA sheet exhibits a stronger aging response.The CRA sheet has higher yield strength and tensile strength than URA sheet,with reduced yield strength anisotropy but increased tensile strength anisotropy.Taking into account different strengthening mechanisms,although the finer grain size of URA sheet enhances grain boundary strengthening,CRA sheet is more responsive to aging,leading to superior aging-precipitated phase strengthening and consequently higher yield strength.
基金supported by the FUBAP(Firat University scientific research projects)under the project No:MF.12.32
文摘The addition of NaCl in the ammonium persulfate-APS(as an oxidant)leaching was investigated.APS has some advantages compared with conventional oxidants and its standard redox potential(E°)is2.0V.Effect of six parameters such as NaCl concentration,APS concentration,temperature,time,liquid–solid ration(L/S),and stirring speed on the leaching behavior was studied.Results showed that metals extraction increased with increasing of NaCl concentration,APS concentration,leaching temperature(up to333K),and L/S ratio.During oxidative leaching of sulfide minerals,the occurrence of elemental sulfur layer on particle surface is known as primary problem that causes low metal extraction.According to the results,the passivation effect of sulfur layer and low dissolution problems can be eliminated in the presence of chloride ions.Copper and iron extraction yields were obtained as75%and80%,respectively under leaching conditions as follows:APS concentration250g/L;NaCl concentration150g/L;time180min;temperature333K;stirring speed400r/min;and L/S250mL/g.
基金Project(BK20160512)supported by the Natural Science Foundation of Jiangsu Province,ChinaProject(16YJCZH027)supported by the Humanity and Social Science Youth Foundation of Ministry of Education of ChinaProject(15GLC004)supported by the Social Science Foundation of Jiangsu Province,China
文摘In the travel process of urban residents,travelers will take a series of activities such as imitation and exclusion by observing other people’s travel modes,which affects their following trips.This process can be seen as a repeated game between members of the travelers.Based on the analysis of this game and its evolution trend,a multi-dimensional game model of low-carbon travel for residents is established.The two dimensional game strategies include whether to accept the low-carbon concept and whether to choose low-carbon travel.Combined with evolutionary game theory,the low-carbon travel choices of residents in different cities are simulated,and the evolutionary stability strategies are obtained.Finally,the influences of the main parameters of the model on the evolution process and stability strategies are discussed.The results show that travelers would develop towards two trends.Cities with more developed public traffic system have a higher proportion of receiving low-carbon concept and choosing low-carbon travel.Cities with underdeveloped public transport system could increase this proportion by some measures such as encouraging residents to choose slow transport and increasing the propaganda of low-carbon travel,but the positive effects of the measures like propaganda have a limited impact on the proportion.
基金Projects(51234008,51174230)supported by the National Natural Science Foundation of ChinaProject(NCET-11-0515)supported by the Program for New Century Excellent Talents in University,ChinaProject supported by Co-Innovation Center for Clean and Efficient Utilization of Strategic Metal Mineral Resources,China
文摘A large amount of coal gangue from coal mining and processing is regarded as waste and usually stockpiled directly. In order to recycle the valuable elements from the coal gangue, an integrated process is proposed. The process consists of three steps: 1concentrating alumina from the coal gangue via activation roasting followed by alkali leaching of Si O2 which produces alumina concentrate for alumina extraction by the Bayer process; 2) synthesizing tobermorite whiskers from the filtrated alkali liquo containing silicate via a hydrothermal method and reusing excess caustic liquor; and 3) enriching titanium component from the Baye process residue by sulfuric acid leaching. Alumina concentrate with 69.5% Al_2O_3 and mass ratio of alumina to silica(A/S) of 5.9pure 1.1 nm tobermorite whisker and TiO_2-rich material containing 33% TiO_2 are produced, respectively, with the optimal parameters Besides, the actual alumina digestion ratio of alumina concentrate reaches 80.4% at 270 oC for 40 min in the Bayer process.
基金Projects(51804136,51764016)supported by the National Natural Science Foundation of ChinaProject(U1402271)supported by the Joint Funds of the National Natural Science Foundation of China+2 种基金Project(20181BAB216017)supported by the Jiangxi Provincial Natural Science Foundation,ChinaProject(GK-201803)supported by the Research Fund Program of State Key Laboratory of Rare Metals Separation and Comprehensive Utilization,ChinaProjects(yy2016001,yy2016012)supported by the Research Fund Program of the State Key Laboratory of Pressure Hydrometallurgical Technology of Associated Nonferrous Metal Resources,China。
文摘The mechanism of oxygen pressure acid leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation was investigated in this study.Artificial sphalerite was fabricated with varying amounts of iron content via the sintering of ZnS and FeS and used for the pressure acid leaching experiment.The variations in the potential of the pressure leaching system were investigated by using a self-designed potential autoclave.The results showed that compared to the non-iron sphalerite,there was a violent redox reaction between the 25.70%Fe-artificial sphalerite and dissolved oxygen during the process of pressure leaching;and the catalytic mechanism was attributed to the redox couple Fe^3+/Fe^2+,where Fe3+oxidizes the H2S gas film and the reduced Fe2+state is subsequently oxidized by the dissolved oxygen.Furthermore,the effect of temperature,H2SO4 concentration,and oxygen partial pressure on the artificial sphalerite with different iron contents was studied.The sphalerite samples with iron content were observed to dissolve more easily in sulfuric acid compared to the non-iron samples.Moreover,the activation energy of artificial sphalerite was observed to be lower in the sample with 25.70%iron content(22.26 kJ/mol)compared to that with no iron(32.31 kJ/mol);and the apparent reaction orders were obtained with respect to H2SO4 concentration(1.10 and 1.36)and oxygen partial pressure(1.29 and 1.41),respectively.A comprehensive kinetic model was developed on the basis of the experimental data and the fitted leaching ratio plot;and the kinetic equations for the leaching of sphalerite catalyzed by Fe^3+/Fe^2+self-precipitation were determined.
基金Projects(51904097,51804103)supported by the National Natural Science Foundation of ChinaProject(2019GGJS056)supported by the Training Program for Young Backbone Teachers in Colleges and Universities of Henan Province,China+2 种基金Project(HB201905)supported by Open Foundation of State Environmental Protection Key Laboratory of Mineral Metallurgical Resources Utilization and Pollution Control,ChinaProject(202102310548)supported by Scientific and Technological Project of Henan Province,ChinaProject(21IRTSTHN006)supported by Program for Innovative Research Team in the University of Henan Province,China。
文摘D2EHPA(P204),tri-butyl-phosphate(TBP)and sodium chloride(NaCl)were attractive for selective extraction of scandium from acid leaching solution of red mud.The extraction parameters of P204 concentration(X_(P204)),NaCl concentration(C_(NaCl)),pH value,reaction time,stirring speed and O/A were investigated to extract scandium and separate iron from the acid leaching solution.The extraction mechanism was analyzed by Fourier transform infrared spectroscopy(FT-IR)and thermodynamic theory.The single-stage extraction efficiency of scandium,iron andβ(Sc/Fe)were 99.1%,9.4%and 1061.2,respectively,with C_(NaCl) of 75 g/L and XP204 of 0.75 at solution pH value of 1.2 and stirring speed of 200 r/min for 6 min,in which a good separation effect of scandium and iron was obtained.The vibration absorption peak Sc─O was contributed to the extraction of scandium with P204.The complex[FeCln]^(3−n) existed in the solution with adding NaCl into the acid leaching solution.The value of n was higher and the valence state of the complex[FeCln]^(3−n) was lower with an increase of chloride concentration,which restricts the extraction efficiency of iron with P204.The extraction of three stages in the counter-current simulation experiments was carried out according to the McCabe-Thiele diagram.Gibbs free energy change(ΔG)of−5.93 kJ/mol,enthalpy change(ΔH)of 23.45 kJ/mol and entropy change(ΔH)of 98.54 J/(mol·K)were obtained in the solvent extraction proces,which indicate that the extraction reaction is easily spontaneous and endothermic and a proper increase of temperature is conducive to the extraction of scandium.
基金Project (50321402) supported by the National Natural Science Foundation of China project(2004CB619204) supported by Major State Basic Research Development Program of China
文摘Alkali-leaching and acid-leaching were proposed for the dephosphorization of Changde iron ore, which contains an average of 1.12% for phosphorus content. Sodium hydroxide, sulfuriced, hydrochloric and nitric acids were used for the preparation of leach solutions. The results show that phosphorus occurring as apatite phase could be removed by alkali-leaching, but those occurring in the iron phase could not. Sulfuric acid is the most effective among the three kinds of acid. 91.61% phosphorus removal was attained with 1% sulfuric acid after leaching for 20 rain at room temperature. Iron loss during acid-leaching can be negligible, which was less than 0.25%.The pH value of solution after leaching with1% sulfuric acid was about 0.86, which means acid would not be exhausted during the process and it could be recycled, and the recycle of sulfuric acid solution would make the dephosphorization process more economical.
基金Projects(51774079,51674075)supported by the National Natural Science Foundation of ChinaProject(N182508026)supported by the Fundamental Research Funds for the Central Universities,China。
文摘The precipitation performance and kinetics of gibbsite from sodium aluminate solution with different sodium oxalate concentrations as well as the corresponding influence mechanism of oxalate during the seed precipitation process were systematically investigated by physicochemical properties test,using SEM and Raman spectra.As the concentration of sodium oxalate increases,both the precipitation rate and particle size of gibbsite decrease.The presence of sodium oxalate not only increases the viscosity of sodium aluminate solution,but also promotes the transformation of Al(OH)4^? to Al2O(OH)6^2?.The overall reaction rate constant decreases and the apparent activation energy of gibbsite increases with the increasing sodium oxalate concentration,the rate controlling step of which is chemical reaction.The needle-like sodium oxalate precipitates on the gibbsite crystals and covers the active Al(OH)3 seed sites,which leads to the lower precipitation rate and the finer particle size of gibbsite during the seed precipitation process.
基金Project(50674104) supported by the National Natural Science Foundation of ChinaProject(2006BA02B04-4-2) supported by the Planned Science and Technology of China
文摘A hydrometallurgical process for indium extraction and ferric oxide powder preparation for soft magnetic ferrite material was developed. Using reduction lixivium from high-acid reductive leaching of zinc oxide calcine as raw solution, copper and indium were firstly recovered by iron powder cementation and neutralization. The recovery ratios of Cu and In are 99% and 95%, respectively. Some harmful impurities that have negative influences on magnetic properties of soft magnetic ferrite material are deeply removed with sulfidization purification and neutral flocculation method. Under the optimum conditions, the content of impurities like Cu, Pb, As, Al in pure Zn-Fe sulfate solution are less than 0.004 g/L, but those of Cd, Si, Ca and Mg are relatively high. Finally, thermal precipitation of iron is carried out at 210 ℃ for 1.5 h. The precipitation ratio of Fe is 93.33%. Compared with the quality standard of ferric oxide for soft magnetic ferrite materials, the contents of Al and Mg in obtained ferric oxide powder meet the requirement of YHT1 level of ferric oxide, and those of Si, Ca meet the requirement of YHT3 level of ferric oxide. XRD and SEM characterizations confirm that the obtained sample is well-dispersed spindle spherule with regular a-Fe2O3 crystal structure. The length-to-diameter ratio ofa-Fe2O3 powder is （3-4）：1 with an average particle size of 0.5 μm.
基金Project(2016RS2016)supported by the Hunan Provincial Science and Technology Leader(Innovation Team of Interface Chemistry of Efficient and Clean Utilization of Complex Mineral Resources),ChinaProject supported by the Co-Innovation Centre for Clean and Efficient Utilization of Strategic Metal Mineral Resources,ChinaProject(2015CX005)supported by the Innovation Driven Plan of Central South University,China
文摘Many researchers found that the Fe2+together with less amount of Cu2+can accelerate the leaching of chalcopyrite.In this work,the leaching of chalcopyrite with Cu2+was investigated.The leaching residuals were examined by Raman spectroscopy.Based on the leaching experiments,the chemical equilibrium in solution was calculated using Visual MINTEQ.The results showed that the Fe in chalcopyrite lattice was replaced by Cu2+;therefore,the chalcopyrite transformed into covellite.Furthermore,the formation of chalcocite occurred when Fe2+and Fe3+were added to the solution containing Cu2+.The copper extraction increased with a decrease of the initial redox potential(or the ratio of Fe3+/Fe2+).
基金Project(50374077) supported by the National Natural Science Foundation of China
文摘A dual cell system was used to study the influence of chloride ions on the electrogenerative leaching of sulfide minerals. The results show that the influences of chloride ions on a series of electrogenerative leaching system are similar, and chlorine ion is involved in the electrogenerative leaching process of sulfide minerals directly. The output power increases with the increase of Cl^- concentration. The influence on the electrogenerative leaching rate decreases when the Cl^- concentration reaches a certain value. The mechanisms of anodic reaction are deduced based on the reasonable hypothesis, and kinetic equations with respect to chlorine ions for each sulfide mineral are obtained. The kinetic equations show that when concentration of Cl^- is relatively low, the electrogenerative leaching rates are predicted to have 2/5,3/7,1/3 and 1/3 order dependence on Cl^- concentration for chalcopyrite concentrate,nickel concentrate, sphalerite and galena. As concentration of Cl^- increases, the correlative dependence of electrogenerative leaching rate on concentration of Cl^- becomes weak.
