In order to eliminate the pitting and improve the surface morphology of cathode nickel,the influence of additives of boric acid and dodecyl sodium sulfate(SDS)on the process of nickel electrowinning from sulfate syste...In order to eliminate the pitting and improve the surface morphology of cathode nickel,the influence of additives of boric acid and dodecyl sodium sulfate(SDS)on the process of nickel electrowinning from sulfate system was studied by cathode polarization tests and nickel electrodeposition experiments.The experimental results show that the addition of boric acid can increase the cathode polarization while SDS can decrease the cathode polarization.Both boric acid and SDS are useful to eliminate the pitting on nickel deposits and improve the morphology of surface.Good deposit morphology with rare pitting and high current efficiency is favored by adding 10 g/L boric acid and 40 mg/L SDS in the electrolyte under the condition of nickel ion concentration of 80 g/L, sodium ion concentration of 10 g/L,pH of 3,current density of 220 A/m 2 and temperature of 70℃.展开更多
The microstructure evolution and electrolysis behavior of(Cu_(52)Ni_(30)Fe_(18))–x Ni Fe_2O_4(x=40wt%,50wt%,60wt%,and 70wt%)composite inert anodes for aluminum electrowinning were studied.Ni Fe_2O_4 was synthesized b...The microstructure evolution and electrolysis behavior of(Cu_(52)Ni_(30)Fe_(18))–x Ni Fe_2O_4(x=40wt%,50wt%,60wt%,and 70wt%)composite inert anodes for aluminum electrowinning were studied.Ni Fe_2O_4 was synthesized by solid-state reaction at 950°C.The dense anode blocks were prepared by ball-milling followed by sintering under a N_2 atmosphere.The phase evolution of the anodes after sintering was determined by scanning electron microscopy and energy-dispersive X-ray spectroscopy.The results indicate that a substitution reaction between Fe in the alloy phase and Ni in the oxide phase occurs during the sintering process.The samples were also examined as inert anodes for aluminum electrowinning in the low-temperature KF–NaF–AlF_3 molten electrolyte for 24 h.The cell voltage during electrolysis and the corrosion scale on the anodes were analyzed.The results confirm that the scale has a self-repairing function because of the synergistic reaction between the alloy phase with Fe added and the oxide phase.The estimated wear rate of the(Cu_(52)Ni_(30)Fe_(18))–50Ni Fe_2O_4 composite anode is 2.02 cm·a^(-1).展开更多
Effect of added Co2 +(aq)on copper electrowinning was studied using doped polyaniline(Pani)and Pb-Ag(1%)anodes and a stainless steel cathode.The presence of added Co2+ (aq)in the electrolyte solution was found to decr...Effect of added Co2 +(aq)on copper electrowinning was studied using doped polyaniline(Pani)and Pb-Ag(1%)anodes and a stainless steel cathode.The presence of added Co2+ (aq)in the electrolyte solution was found to decrease the anode potentials.The optimum level of Co2 +(aq)concentration in the electrolyte,with respect to the maximum saving of power consumption was established.Linear sweep voltammetry(LSV)was used to study the influence of added Co2 +(aq)on the anodic processes in a copper sulfate-sulfuric acid electrolyte.The oxygen-evolution potential for Pani anode is depolarised at lower current densities(≤0.01 A/cm2)and attains saturation atρ(Co 2+ )o≈0.789 g/L;whilst the oxygen-evolution potential for Pb-Ag(1%)anode is depolarised at higher current densities(≤0.02 A/cm2)and attains saturation atρ(Co 2+ )o≈1.315 g/L.The preferred orientations of the copper deposits change from(220)to(111)with the addition of 0.394?0.789 g/L Co 2+ but higher concentrations favor(220)orientation again.展开更多
The effect of lead anode, rotating cylinder electrode (RCE), amount of 1,2-dihydroxypropane (12-DHP), temperature and rotation on the electrowinning of copper from low concentration acidified copper sulphate solution ...The effect of lead anode, rotating cylinder electrode (RCE), amount of 1,2-dihydroxypropane (12-DHP), temperature and rotation on the electrowinning of copper from low concentration acidified copper sulphate solution has been investigated. Copper powder was electrodeposited onto RCE that made of pure copper. From cyclic voltammetry experiments, an empirical parameter called the departure percent, S, was obtained which may represent the stability of the organic additive in the given medium and under the experimental conditions. The inhibition percentage, P, was 0.00 - 89.91% depending on the experimental variables. P was affected by temperature and mole fraction of 12-DHP, while rotation did not show any influence on it. Values of activation energy of electrodeposition process, Ea, were found to be less than 28 kJ mol-1 indicating diffusion controlled process. The overall mass transfer correlations under the present conditions have been computed using the dimensional analysis method. The data were valid for 90 < Sh < 1098, 737 < Sc < 59284 and 271 < Re < 7046 and the results agreed with the previous studies of mass transfer to rotating cylinders in turbulent flow regimes. The effect of time, content of 12-DHP, temperature and the speed of rotation on the morphological changes of the electrodeposited copper powder as well as deposits composition and crystallite size have been studied. Various crystallite sizes ranged 7.1 nm - 250.6 nm were obtained and characterized by EDS and XRD. Different topographs proved that the rate of copper electrodeposition increased by increasing deposition time, temperature and the speed of rotation. Also, they proved that the deposition rate decreased by adding 12-DHP to the solution. Therefore, the results obtained by SEM supported those achieved by measuring the limiting current density and follow the normal manner when organic solvents were added to the electrodeposition bath.展开更多
The separating efficiency of Sb from As and Sn in jamesonite concentrate could be improvedby changing the composition of leaching solution and other conditions.The related kineticparameters of electrode reaction were ...The separating efficiency of Sb from As and Sn in jamesonite concentrate could be improvedby changing the composition of leaching solution and other conditions.The related kineticparameters of electrode reaction were evaluated under discussion on the form of complex ionAsS<sub>3</sub><sup>3-</sup>in extract and the reduction at amalgam electrode.It was also discussed about the ef-fect of eoncentration of Na<sub>2</sub>S and SbS<sub>3</sub><sup>3-</sup>in solution on the current efficiency of SnS<sub>4</sub><sup>4-</sup> reduction.展开更多
The effects of arsenic on the cathode polarization process in zinc electrowinning,its kinetics equation,parameters and polarization mechanism were studied by multiple electrochemistry approaches.The experimental resul...The effects of arsenic on the cathode polarization process in zinc electrowinning,its kinetics equation,parameters and polarization mechanism were studied by multiple electrochemistry approaches.The experimental results show that,if[As 3+]≥3 mg/L,electrowinning first enters into stationary passivation range,and then enters into precipitation range,which indicates that the depolarization function of impurity arsenic is zinc electrowinning.展开更多
Polyaniline(Pani)anode is tested to highlight the feasibility of reduction of both energy consumption and capital costs in zinc electrowinning from sulfate solution without any modification to the existing plant.Curre...Polyaniline(Pani)anode is tested to highlight the feasibility of reduction of both energy consumption and capital costs in zinc electrowinning from sulfate solution without any modification to the existing plant.Current density,electrolyte temperature, added gelatin,added Mn 2+ ,oxygen-evolution potential,cell potential and long duration tests were investigated.The zinc deposits were also studied by means of scanning electron microscope(SEM)and X-ray diffraction(XRD).The results show that current density and added gelatin change the preferred crystal orientations of the zinc deposits.Compared with Pb-Ag(1%)anode used in industry,the cell voltage decreases by 0.15-0.30 V,energy consumption of Zn is 2.46-2.70 kW·h/kg which results in 20%energy savings.Long duration tests show that Pani anode can represent a good alterative ability for zinc electrowinning.Zinc deposits obtained have no Pb pollution.The additions of Mn2 +ions and gelatin also change the surface morphology and deposit quality of the electrodeposited zinc,affecting the crystal orientation.These researches demonstrate that Pani anode has distinct advantages over acidic electrowinning process.展开更多
By means of an electrochemical study,the influence of arsenic,antimony and cobalt on cathodic polarization in the zinc electrowinning process,the associated kinetic equations and parameters,and the polarization mechan...By means of an electrochemical study,the influence of arsenic,antimony and cobalt on cathodic polarization in the zinc electrowinning process,the associated kinetic equations and parameters,and the polarization mechanism have been studied.The results show that the experimental values of the kinetic parameters are in accord with the theoretical values in the ZnSO4/H2SO4 solution with a single impurity is added.In contrast,the charge transfer coefficient α is smaller than the theoretical value in the ZnSO4/H2SO4 solution when the three impurities are added together.展开更多
Huge quantities of zinc leaching residues(ZLRs) generated from zinc production are dumped continuously around the world and pose a potential environmental threat because of their considerable amounts of entrained heav...Huge quantities of zinc leaching residues(ZLRs) generated from zinc production are dumped continuously around the world and pose a potential environmental threat because of their considerable amounts of entrained heavy metals(mainly lead). Most ZLRs have not been properly treated and the valuable metals in them have not yet been effectively recovered. Herein, the deep cleaning of a ZLR and recovery of valuable metals via a hydrometallurgical route were investigated. The cleaning process consists of two essential stages: acid leaching followed by calcium chloride leaching. The optimum conditions for extracting zinc, copper, and indium by acid leaching were a sulfuric acid concentration of 200 g·L^(-1), a liquid/solid ratio of 4:1(m L/g), a leaching time of 2 h, and a temperature of 90°C. For lead and silver extractions, the optimum conditions were a calcium chloride concentration of 400 g·L^(-1), a pH value of 1.0, a leaching time of 1 h, and a temperature of 30°C. After calcium chloride leaching, silver and lead were extracted out and the lead was finally recovered as electrolytic lead by electrowinning. The anglesite phase, which poses the greatest potential environmental hazard, was removed from the ZLR after deep cleaning, thus reducing the cost of environmental management of ZLRs. The treatment of chlorine and spent electrolyte generated in the process was discussed.展开更多
The low cell voltage during electrolytic Mn from the MnCl_(2) system can effectively reduce the power consumption.In this work,the Ti/Sn−Ru−Co−Zr modified anodes were obtained by using thermal decomposition oxidation....The low cell voltage during electrolytic Mn from the MnCl_(2) system can effectively reduce the power consumption.In this work,the Ti/Sn−Ru−Co−Zr modified anodes were obtained by using thermal decomposition oxidation.The physical parameters of coatings were observed by SEM(scanning electron microscope).Based on the electrochemical performance and SEM/XRD(X-ray diffraction)of the coatings,the influence of Zr on electrode performance was studied and analyzed.When the mole ratio of Sn−Ru−Co−Zr is 6:1:0.8:0.3,the cracks on the surface of coatings were the smallest,and the compactness was the best due to the excellent filling effect of ZrO_(2)nanoparticles.Moreover,the electrode prepared under this condition had the lowest mass transfer resistance and high chloride evolution activity in the 1mol%NH_(4)Cl and 1.5mol%HCl system.The service life of 3102 h was achieved according to the empirical formula of accelerated-life-test of the new type anode.展开更多
The oxidation of oxygen ions and the generation of an anode effect at a low oxygen content of 150 mg/kg were discussed in this paper.Cyclic voltammetry and square-wave voltammetry tests were conducted to explore the a...The oxidation of oxygen ions and the generation of an anode effect at a low oxygen content of 150 mg/kg were discussed in this paper.Cyclic voltammetry and square-wave voltammetry tests were conducted to explore the anodic processes of LiF-NdF_(3)melt after a lengthy period of pre-electrolysis purification at 1000℃(during which the oxygen content reduced from 413 to 150 mg/kg).The oxidation process of oxygen ions was found to have two stages:oxidation product adsorption and CO/CO_(2)gas evolution.The adsorption stage was controlled by diffusion,whereas the gas evolution was controlled by the electrochemical reaction.In comparison with oxygen content of 413 mg/kg,the decrease in the amplitude of the current at low oxygen content of 150 mg/kg was much gentler during the forward scanning process when the anode effect occurred.Fluorine-ion oxidation peaks that occurred at about 4.2 V vs.Li/Li+could be clearly observed in the reverse scanning processes,in which fluorine ions were oxidized and perfluorocarbons were produced,which resulted in an anode effect.展开更多
In this paper, the sintered Ti anodes （STA） with Ti suboxide intermediate layers and β-MnO<sub>2</sub> activelayers were investigated in detail. At usual industrial current densities, the oxygen evoluti...In this paper, the sintered Ti anodes （STA） with Ti suboxide intermediate layers and β-MnO<sub>2</sub> activelayers were investigated in detail. At usual industrial current densities, the oxygen evolutionoverpotential on STA is reduced by 350 mV compared with lead anodes. According to the equationobtained experimentally, the service life of STA may be expected to be more than 3 years. After los-ing activity, STA may be recoated with β-MnO<sub>2</sub> active layers and used again. The electrocatalyticactivity and the service life of the reused anodes remained almost unchanged. The possible reasonsfor losing activity of STA during the anodic evolution of oxygen were investigated by means of elec-tron probe microanalysis, electron scanning microscope and X-ray diffraction.展开更多
In order to economically recover the copper from the low grade copper ores, a bioleaching solvent extraction electrowinning plant with a design capacity of 2 000 t cathode copper per year in Dexing Copper Mine was ope...In order to economically recover the copper from the low grade copper ores, a bioleaching solvent extraction electrowinning plant with a design capacity of 2 000 t cathode copper per year in Dexing Copper Mine was operated in September, 1997. The results during the 10 month period of the industrial copper dump leaching have been obtained and the approaches have been carried out to enhance the copper dissolution from the waste rocks. The overall operation flowsheet is depicted. The problems confronted in the process and possible way for improving are discussed.展开更多
A hydrometallurgical process has been developed for cobalt recovery from a waste catalyst (petroleum refining industry). This waste catalyst containing about 2.18 weight % of Co, is highly contaminated by Mg, Al, Si, ...A hydrometallurgical process has been developed for cobalt recovery from a waste catalyst (petroleum refining industry). This waste catalyst containing about 2.18 weight % of Co, is highly contaminated by Mg, Al, Si, Ca, Fe, Ni, Cu, Zn, Mo. The major steps are: (I) The spent catalyst is roasted with flux material in an electrical furnace at very high temperature (700?C) for a specific duration. (II) The roasted sample is leached with sulphuric acid to bring the metal contents into solution form. (III) For separating cobalt values from the leach solution, the solution pH is raised by NaOH addition, where all cobalt content is precipitated at a pH of about 12. (IV) This cobalt hydroxide precipitate is filtered and dissolved in minimum amount of sulphuric acid to get cobalt sulphate solution which is used as the electrolyte for the electrolytic recovery of cobalt. For optimizing various parameters like (1) H2SO4 concentration;(2) Duration;(3) Cobalt concentration;(4) Current density;(5) Temperature;(6) Stirring etc., The particle surface morphology and deposited layers have been characterized by scanning electron microscopy (SEM). A compact metallic deposit containing 70% cobalt was obtained.展开更多
Many silver(Ag)containing consumer-products(e.g.textiles)release Ag into the environment,posing ecotoxicological risks.Ag recovery mitigates environmental hazards,recycles Ag,and leads to sustainability.In the present...Many silver(Ag)containing consumer-products(e.g.textiles)release Ag into the environment,posing ecotoxicological risks.Ag recovery mitigates environmental hazards,recycles Ag,and leads to sustainability.In the present work,Ag has been recovered as Ag^0nanoparticles from the spent solution(thiourea(TU)～0.5 mol/L pH～1.1–1.2,and Ag～550 mg/L)obtained from the regeneration of an Ag-loaded resin using a simple undivided electrolytic cell.The reclaimed regenerant solution has been recycled and reused in a closed-loop scheme over multiple cycles.The process parameters,i.e.,current(0.05 A)and stirring speed(600 r/min),have been optimized for Ag recovery of～94%and TU loss of～2%.The reclaimed regenerant solution has been shown to regenerate Ag-loaded resin samples with>90%regeneration efficiency over 4 cycles of consecutive extraction and regeneration.The recovered Ag^0nanoparticles are monodisperse,consistently spherical in shape,and have a mean diameter of～6 nm with standard deviation of the Gaussian fit as～2.66 nm.展开更多
文摘In order to eliminate the pitting and improve the surface morphology of cathode nickel,the influence of additives of boric acid and dodecyl sodium sulfate(SDS)on the process of nickel electrowinning from sulfate system was studied by cathode polarization tests and nickel electrodeposition experiments.The experimental results show that the addition of boric acid can increase the cathode polarization while SDS can decrease the cathode polarization.Both boric acid and SDS are useful to eliminate the pitting on nickel deposits and improve the morphology of surface.Good deposit morphology with rare pitting and high current efficiency is favored by adding 10 g/L boric acid and 40 mg/L SDS in the electrolyte under the condition of nickel ion concentration of 80 g/L, sodium ion concentration of 10 g/L,pH of 3,current density of 220 A/m 2 and temperature of 70℃.
基金financially supported by the Major Science and Technology Programs of CHALCO(ZB2013CBBCe1)the Zhengzhou Non-ferrous Metals Research Institute Co.Ltd.of CHALCO for supporting this work
文摘The microstructure evolution and electrolysis behavior of(Cu_(52)Ni_(30)Fe_(18))–x Ni Fe_2O_4(x=40wt%,50wt%,60wt%,and 70wt%)composite inert anodes for aluminum electrowinning were studied.Ni Fe_2O_4 was synthesized by solid-state reaction at 950°C.The dense anode blocks were prepared by ball-milling followed by sintering under a N_2 atmosphere.The phase evolution of the anodes after sintering was determined by scanning electron microscopy and energy-dispersive X-ray spectroscopy.The results indicate that a substitution reaction between Fe in the alloy phase and Ni in the oxide phase occurs during the sintering process.The samples were also examined as inert anodes for aluminum electrowinning in the low-temperature KF–NaF–AlF_3 molten electrolyte for 24 h.The cell voltage during electrolysis and the corrosion scale on the anodes were analyzed.The results confirm that the scale has a self-repairing function because of the synergistic reaction between the alloy phase with Fe added and the oxide phase.The estimated wear rate of the(Cu_(52)Ni_(30)Fe_(18))–50Ni Fe_2O_4 composite anode is 2.02 cm·a^(-1).
基金Project(50974065)supported by the National Natural Science Foundation of ChinaProject(2009009)supported by the Analysis and Testing Foundation of Kunming University of Science and Technology,China
文摘Effect of added Co2 +(aq)on copper electrowinning was studied using doped polyaniline(Pani)and Pb-Ag(1%)anodes and a stainless steel cathode.The presence of added Co2+ (aq)in the electrolyte solution was found to decrease the anode potentials.The optimum level of Co2 +(aq)concentration in the electrolyte,with respect to the maximum saving of power consumption was established.Linear sweep voltammetry(LSV)was used to study the influence of added Co2 +(aq)on the anodic processes in a copper sulfate-sulfuric acid electrolyte.The oxygen-evolution potential for Pani anode is depolarised at lower current densities(≤0.01 A/cm2)and attains saturation atρ(Co 2+ )o≈0.789 g/L;whilst the oxygen-evolution potential for Pb-Ag(1%)anode is depolarised at higher current densities(≤0.02 A/cm2)and attains saturation atρ(Co 2+ )o≈1.315 g/L.The preferred orientations of the copper deposits change from(220)to(111)with the addition of 0.394?0.789 g/L Co 2+ but higher concentrations favor(220)orientation again.
文摘The effect of lead anode, rotating cylinder electrode (RCE), amount of 1,2-dihydroxypropane (12-DHP), temperature and rotation on the electrowinning of copper from low concentration acidified copper sulphate solution has been investigated. Copper powder was electrodeposited onto RCE that made of pure copper. From cyclic voltammetry experiments, an empirical parameter called the departure percent, S, was obtained which may represent the stability of the organic additive in the given medium and under the experimental conditions. The inhibition percentage, P, was 0.00 - 89.91% depending on the experimental variables. P was affected by temperature and mole fraction of 12-DHP, while rotation did not show any influence on it. Values of activation energy of electrodeposition process, Ea, were found to be less than 28 kJ mol-1 indicating diffusion controlled process. The overall mass transfer correlations under the present conditions have been computed using the dimensional analysis method. The data were valid for 90 < Sh < 1098, 737 < Sc < 59284 and 271 < Re < 7046 and the results agreed with the previous studies of mass transfer to rotating cylinders in turbulent flow regimes. The effect of time, content of 12-DHP, temperature and the speed of rotation on the morphological changes of the electrodeposited copper powder as well as deposits composition and crystallite size have been studied. Various crystallite sizes ranged 7.1 nm - 250.6 nm were obtained and characterized by EDS and XRD. Different topographs proved that the rate of copper electrodeposition increased by increasing deposition time, temperature and the speed of rotation. Also, they proved that the deposition rate decreased by adding 12-DHP to the solution. Therefore, the results obtained by SEM supported those achieved by measuring the limiting current density and follow the normal manner when organic solvents were added to the electrodeposition bath.
文摘The separating efficiency of Sb from As and Sn in jamesonite concentrate could be improvedby changing the composition of leaching solution and other conditions.The related kineticparameters of electrode reaction were evaluated under discussion on the form of complex ionAsS<sub>3</sub><sup>3-</sup>in extract and the reduction at amalgam electrode.It was also discussed about the ef-fect of eoncentration of Na<sub>2</sub>S and SbS<sub>3</sub><sup>3-</sup>in solution on the current efficiency of SnS<sub>4</sub><sup>4-</sup> reduction.
基金Project(2008049)supported by Personal Training of Kunming University of Science and TechnologyProject(2008ZC013M)supported bythe Basic Research Program of Scientific and Technological Department Yunnan Province
文摘The effects of arsenic on the cathode polarization process in zinc electrowinning,its kinetics equation,parameters and polarization mechanism were studied by multiple electrochemistry approaches.The experimental results show that,if[As 3+]≥3 mg/L,electrowinning first enters into stationary passivation range,and then enters into precipitation range,which indicates that the depolarization function of impurity arsenic is zinc electrowinning.
基金Project(50974065)supported by the National Natural Science Foundation of ChinaProject(2009009)supported by the Analysis and Testing Foundation of Kunming University of Science and Technology,China
文摘Polyaniline(Pani)anode is tested to highlight the feasibility of reduction of both energy consumption and capital costs in zinc electrowinning from sulfate solution without any modification to the existing plant.Current density,electrolyte temperature, added gelatin,added Mn 2+ ,oxygen-evolution potential,cell potential and long duration tests were investigated.The zinc deposits were also studied by means of scanning electron microscope(SEM)and X-ray diffraction(XRD).The results show that current density and added gelatin change the preferred crystal orientations of the zinc deposits.Compared with Pb-Ag(1%)anode used in industry,the cell voltage decreases by 0.15-0.30 V,energy consumption of Zn is 2.46-2.70 kW·h/kg which results in 20%energy savings.Long duration tests show that Pani anode can represent a good alterative ability for zinc electrowinning.Zinc deposits obtained have no Pb pollution.The additions of Mn2 +ions and gelatin also change the surface morphology and deposit quality of the electrodeposited zinc,affecting the crystal orientation.These researches demonstrate that Pani anode has distinct advantages over acidic electrowinning process.
基金supported by the National Natural Science Foundation of China (Grant No 50574045)PhD Program Foundation of the Ministry of Education of China (Grant No 20050674003)+1 种基金Personnel Training Program of Kunming University of Science and Technology (Grant No 2008049)the Basic Research Program in Science and Technology of Yunnan Province (Grant No 2008ZC013M)
文摘By means of an electrochemical study,the influence of arsenic,antimony and cobalt on cathodic polarization in the zinc electrowinning process,the associated kinetic equations and parameters,and the polarization mechanism have been studied.The results show that the experimental values of the kinetic parameters are in accord with the theoretical values in the ZnSO4/H2SO4 solution with a single impurity is added.In contrast,the charge transfer coefficient α is smaller than the theoretical value in the ZnSO4/H2SO4 solution when the three impurities are added together.
基金financially supported by the National Natural Science Foundation of China (Nos. U1302274 and 51674026)the Fundamental Research Funds for the Central Universities (No. 230201606500078)the Yunnan Technical Innovation and Personnel Training Program
文摘Huge quantities of zinc leaching residues(ZLRs) generated from zinc production are dumped continuously around the world and pose a potential environmental threat because of their considerable amounts of entrained heavy metals(mainly lead). Most ZLRs have not been properly treated and the valuable metals in them have not yet been effectively recovered. Herein, the deep cleaning of a ZLR and recovery of valuable metals via a hydrometallurgical route were investigated. The cleaning process consists of two essential stages: acid leaching followed by calcium chloride leaching. The optimum conditions for extracting zinc, copper, and indium by acid leaching were a sulfuric acid concentration of 200 g·L^(-1), a liquid/solid ratio of 4:1(m L/g), a leaching time of 2 h, and a temperature of 90°C. For lead and silver extractions, the optimum conditions were a calcium chloride concentration of 400 g·L^(-1), a pH value of 1.0, a leaching time of 1 h, and a temperature of 30°C. After calcium chloride leaching, silver and lead were extracted out and the lead was finally recovered as electrolytic lead by electrowinning. The anglesite phase, which poses the greatest potential environmental hazard, was removed from the ZLR after deep cleaning, thus reducing the cost of environmental management of ZLRs. The treatment of chlorine and spent electrolyte generated in the process was discussed.
基金financially supported by the National Natural Science Foundation of China (Nos. 51564029, 51504111, 52064028, and 22002054)the China Postdoctoral Science Foundation (No. 2018M633418)+1 种基金the Technology Innovation Talents Project of Yunnan Province (No. 2019HB111)Analysis and Testing Foundation of Kunming University of Science and Technology (Nos. 2019 M20182202013, 2020M20192202035, and 2020M2019 2202099)
文摘The low cell voltage during electrolytic Mn from the MnCl_(2) system can effectively reduce the power consumption.In this work,the Ti/Sn−Ru−Co−Zr modified anodes were obtained by using thermal decomposition oxidation.The physical parameters of coatings were observed by SEM(scanning electron microscope).Based on the electrochemical performance and SEM/XRD(X-ray diffraction)of the coatings,the influence of Zr on electrode performance was studied and analyzed.When the mole ratio of Sn−Ru−Co−Zr is 6:1:0.8:0.3,the cracks on the surface of coatings were the smallest,and the compactness was the best due to the excellent filling effect of ZrO_(2)nanoparticles.Moreover,the electrode prepared under this condition had the lowest mass transfer resistance and high chloride evolution activity in the 1mol%NH_(4)Cl and 1.5mol%HCl system.The service life of 3102 h was achieved according to the empirical formula of accelerated-life-test of the new type anode.
基金the National Natural Science Foundation of China(No.51774145).The“Minjiang Scholar”Program of Department of Education,Fujian Province,China was also acknowledged.
文摘The oxidation of oxygen ions and the generation of an anode effect at a low oxygen content of 150 mg/kg were discussed in this paper.Cyclic voltammetry and square-wave voltammetry tests were conducted to explore the anodic processes of LiF-NdF_(3)melt after a lengthy period of pre-electrolysis purification at 1000℃(during which the oxygen content reduced from 413 to 150 mg/kg).The oxidation process of oxygen ions was found to have two stages:oxidation product adsorption and CO/CO_(2)gas evolution.The adsorption stage was controlled by diffusion,whereas the gas evolution was controlled by the electrochemical reaction.In comparison with oxygen content of 413 mg/kg,the decrease in the amplitude of the current at low oxygen content of 150 mg/kg was much gentler during the forward scanning process when the anode effect occurred.Fluorine-ion oxidation peaks that occurred at about 4.2 V vs.Li/Li+could be clearly observed in the reverse scanning processes,in which fluorine ions were oxidized and perfluorocarbons were produced,which resulted in an anode effect.
文摘In this paper, the sintered Ti anodes （STA） with Ti suboxide intermediate layers and β-MnO<sub>2</sub> activelayers were investigated in detail. At usual industrial current densities, the oxygen evolutionoverpotential on STA is reduced by 350 mV compared with lead anodes. According to the equationobtained experimentally, the service life of STA may be expected to be more than 3 years. After los-ing activity, STA may be recoated with β-MnO<sub>2</sub> active layers and used again. The electrocatalyticactivity and the service life of the reused anodes remained almost unchanged. The possible reasonsfor losing activity of STA during the anodic evolution of oxygen were investigated by means of elec-tron probe microanalysis, electron scanning microscope and X-ray diffraction.
文摘In order to economically recover the copper from the low grade copper ores, a bioleaching solvent extraction electrowinning plant with a design capacity of 2 000 t cathode copper per year in Dexing Copper Mine was operated in September, 1997. The results during the 10 month period of the industrial copper dump leaching have been obtained and the approaches have been carried out to enhance the copper dissolution from the waste rocks. The overall operation flowsheet is depicted. The problems confronted in the process and possible way for improving are discussed.
文摘A hydrometallurgical process has been developed for cobalt recovery from a waste catalyst (petroleum refining industry). This waste catalyst containing about 2.18 weight % of Co, is highly contaminated by Mg, Al, Si, Ca, Fe, Ni, Cu, Zn, Mo. The major steps are: (I) The spent catalyst is roasted with flux material in an electrical furnace at very high temperature (700?C) for a specific duration. (II) The roasted sample is leached with sulphuric acid to bring the metal contents into solution form. (III) For separating cobalt values from the leach solution, the solution pH is raised by NaOH addition, where all cobalt content is precipitated at a pH of about 12. (IV) This cobalt hydroxide precipitate is filtered and dissolved in minimum amount of sulphuric acid to get cobalt sulphate solution which is used as the electrolyte for the electrolytic recovery of cobalt. For optimizing various parameters like (1) H2SO4 concentration;(2) Duration;(3) Cobalt concentration;(4) Current density;(5) Temperature;(6) Stirring etc., The particle surface morphology and deposited layers have been characterized by scanning electron microscopy (SEM). A compact metallic deposit containing 70% cobalt was obtained.
文摘Many silver(Ag)containing consumer-products(e.g.textiles)release Ag into the environment,posing ecotoxicological risks.Ag recovery mitigates environmental hazards,recycles Ag,and leads to sustainability.In the present work,Ag has been recovered as Ag^0nanoparticles from the spent solution(thiourea(TU)～0.5 mol/L pH～1.1–1.2,and Ag～550 mg/L)obtained from the regeneration of an Ag-loaded resin using a simple undivided electrolytic cell.The reclaimed regenerant solution has been recycled and reused in a closed-loop scheme over multiple cycles.The process parameters,i.e.,current(0.05 A)and stirring speed(600 r/min),have been optimized for Ag recovery of～94%and TU loss of～2%.The reclaimed regenerant solution has been shown to regenerate Ag-loaded resin samples with>90%regeneration efficiency over 4 cycles of consecutive extraction and regeneration.The recovered Ag^0nanoparticles are monodisperse,consistently spherical in shape,and have a mean diameter of～6 nm with standard deviation of the Gaussian fit as～2.66 nm.
