The electrochemical separation of Mn(Ⅱ)impurity from molten NaCl-KCl-MgCl_(2)was systematically investigated to facilitate the electrolytic production of high-purity magnesium.The reduction of Mn(Ⅱ)to Mn metal on tu...The electrochemical separation of Mn(Ⅱ)impurity from molten NaCl-KCl-MgCl_(2)was systematically investigated to facilitate the electrolytic production of high-purity magnesium.The reduction of Mn(Ⅱ)to Mn metal on tungsten electrode was a quasi-reversible process controlled by diffusion.The apparent standard potential and exchange current density of Mn(Ⅱ)/Mn(0)electrode reaction were determined at temperatures ranging from 973 to 1048 K.Solid Mn metal generated during electrolysis aggregated into irregular clumps and adsorbed some needle-like MgO,imposing a detrimental effect on both the aggregation and the purity of magnesium metal.After electrolysis at-1.5 V in molten NaCl-KCl-MgCl_(2)-0.62wt.%MnCl_(2)for 8 h,the concentration of MnCl_(2)impurity decreased to 0.037 wt.%,achieving a removal efficiency of 94.14%.When direct electrolysis was performed in molten NaCl-KCl-MgCl_(2)-0.62wt.%MnCl_(2),the obtained magnesium metal was small blocks with a caviar-like appearance,and the purity was just 98.59%.In contrast,a large globule of magnesium metal was obtained when electrolysis was performed in the purified electrolyte,and its purity was improved to 99.94%.The controlled-potential electrolysis proposed in this work has been verified to be a green and practically effective method to separate the metal ion impurities from molten electrolyte for high purity magnesium extraction.展开更多
Sodium(Na)and magnesium(Mg)are becoming important for making energy-storage batteries and structural materials.Herein,we develop a liquid-metal-electrode-assisted electrolysis route to producing Na and Mg with low-car...Sodium(Na)and magnesium(Mg)are becoming important for making energy-storage batteries and structural materials.Herein,we develop a liquid-metal-electrode-assisted electrolysis route to producing Na and Mg with low-carbon emissions and no chlorine gas evolution.The clean production stems from the choice of a molten NaCl-Na_(2)CO_(3) electrolyte to prevent chlorine gas evolution,an inert nickel-based anode to produce oxygen,and a liquid metal cathode to make the cathodic product sit at the bottom of the electrolytic cell.We achieve a current efficiency of>90%for the electrolytic production of liquid Na-Sn alloy.Later,Mg-Sn alloy is prepared using the obtained Na-Sn alloy to displace Mg from molten NaCl-MgCl_(2) with a displacement efficiency of>96%.Further,Na and Mg are separated from the electrolytic Na-Sn and displaced Mg-Sn alloys by vacuum distillation with a recovery rate of>92%and Sn can be reused.Using this electrolysisdisplacement-distillation(EDD)approach,we prepare Mg from seawater.The CO_(2)emission of the EDD approach is~20.6 kg CO_(2)per kg Mg,which is less than that of the Australian Magnesium(AM)electrolysis process(~25.0 kg CO_(2)per kg Mg)and less than half that of the Pidgeon process(~45.2 kg CO_(2)per kg Mg).展开更多
Compared with Pidgeon process,the relative vacuum continuous magnesium smelting process reduces the ratio of material to magnesium by changing raw materials and the direct reduction after calcination of prefabricated ...Compared with Pidgeon process,the relative vacuum continuous magnesium smelting process reduces the ratio of material to magnesium by changing raw materials and the direct reduction after calcination of prefabricated pellets,so that the energy consumption per ton of magnesium produced is reduced by 30∼40%,and the carbon emission is reduced by 43∼52%,breaking through the vacuum conditions to achieve continuous production.However,in the process of industrialization,it was found that the magnesium yield in the condenser was low.Therefore,this paper constructs a condenser model of relative vacuum continuous magnesium refining process,and comprehensively analyzes the condensation mechanism of magnesium vapor through simulation and experiment.It is found that the dynamic characteristics of magnesium vapor condensation is an important index to measure its continuity.Under the condition offlowing argon as the protective gas,when the condensation plate spacing is 10 cm,the surface roughness amplitude variance is 2,and the carrier gasflow rate is 20×10^(-3) m/s,the magnesium vapor has a better condensation effect,and the condensation efficiency formula is derived.展开更多
Magnesium(Mg),as one of the most abundant elements in earth's crust,is the lightest structural metal with extensive applications across various industries.However,the performance of Mg-based products is highly dep...Magnesium(Mg),as one of the most abundant elements in earth's crust,is the lightest structural metal with extensive applications across various industries.However,the performance of Mg-based products is highly dependent on their impurity levels,and the lack of high-purity Mg,along with efficient purification method,has posed significant challenge to its widespread industrial adoption.This study investigates the impurity behavior in Mg ingots during the vacuum gasification purification process.Through the analysis of binary phase diagrams,iron(Fe)-based foam material was selected for the filtration and purification of Mg vapor in a vacuum tube furnace.A novel approach combining vacuum gasification,vapor purification,and directional condensation is proposed.The effect of filter pore sizes and filtration temperatures on the efficacy of impurity removal was evaluated.Experimental results demonstrate that Fe-based foam with a pore size of 60 ppi,at a filtration temperature of 773 K,effectively removes impurities such as calcium(Ca),potassium(K),sodium(Na),manganese(Mn),silicon(Si),aluminum(Al),and various oxides,sulfides,and chlorides from the vapor phase.Consequently,high-purity Mg with a purity level exceeding 5N3 was obtained in the condensation zone.展开更多
基金the financial supports from the National Key Research and Development Program of China(No.2021YFC2901400)he Distinguished Young Research Project of Anhui Higher Education,China(No.2023AH020017)the Xinjiang Tianchi Talent Introduction Plan,China。
文摘The electrochemical separation of Mn(Ⅱ)impurity from molten NaCl-KCl-MgCl_(2)was systematically investigated to facilitate the electrolytic production of high-purity magnesium.The reduction of Mn(Ⅱ)to Mn metal on tungsten electrode was a quasi-reversible process controlled by diffusion.The apparent standard potential and exchange current density of Mn(Ⅱ)/Mn(0)electrode reaction were determined at temperatures ranging from 973 to 1048 K.Solid Mn metal generated during electrolysis aggregated into irregular clumps and adsorbed some needle-like MgO,imposing a detrimental effect on both the aggregation and the purity of magnesium metal.After electrolysis at-1.5 V in molten NaCl-KCl-MgCl_(2)-0.62wt.%MnCl_(2)for 8 h,the concentration of MnCl_(2)impurity decreased to 0.037 wt.%,achieving a removal efficiency of 94.14%.When direct electrolysis was performed in molten NaCl-KCl-MgCl_(2)-0.62wt.%MnCl_(2),the obtained magnesium metal was small blocks with a caviar-like appearance,and the purity was just 98.59%.In contrast,a large globule of magnesium metal was obtained when electrolysis was performed in the purified electrolyte,and its purity was improved to 99.94%.The controlled-potential electrolysis proposed in this work has been verified to be a green and practically effective method to separate the metal ion impurities from molten electrolyte for high purity magnesium extraction.
基金support from the National Natural Science Foundation of China(No’s.U22B2071,51874211,52031008)the Chilwee Group(CWDY-ZH-YJY-202101-001).
文摘Sodium(Na)and magnesium(Mg)are becoming important for making energy-storage batteries and structural materials.Herein,we develop a liquid-metal-electrode-assisted electrolysis route to producing Na and Mg with low-carbon emissions and no chlorine gas evolution.The clean production stems from the choice of a molten NaCl-Na_(2)CO_(3) electrolyte to prevent chlorine gas evolution,an inert nickel-based anode to produce oxygen,and a liquid metal cathode to make the cathodic product sit at the bottom of the electrolytic cell.We achieve a current efficiency of>90%for the electrolytic production of liquid Na-Sn alloy.Later,Mg-Sn alloy is prepared using the obtained Na-Sn alloy to displace Mg from molten NaCl-MgCl_(2) with a displacement efficiency of>96%.Further,Na and Mg are separated from the electrolytic Na-Sn and displaced Mg-Sn alloys by vacuum distillation with a recovery rate of>92%and Sn can be reused.Using this electrolysisdisplacement-distillation(EDD)approach,we prepare Mg from seawater.The CO_(2)emission of the EDD approach is~20.6 kg CO_(2)per kg Mg,which is less than that of the Australian Magnesium(AM)electrolysis process(~25.0 kg CO_(2)per kg Mg)and less than half that of the Pidgeon process(~45.2 kg CO_(2)per kg Mg).
基金the National Natural Science Foundation of China(U1908225,U1702253)the Special Funds for Ba-sic Research Operations of Central Universities(N182515007,N170908001,N2025004).
文摘Compared with Pidgeon process,the relative vacuum continuous magnesium smelting process reduces the ratio of material to magnesium by changing raw materials and the direct reduction after calcination of prefabricated pellets,so that the energy consumption per ton of magnesium produced is reduced by 30∼40%,and the carbon emission is reduced by 43∼52%,breaking through the vacuum conditions to achieve continuous production.However,in the process of industrialization,it was found that the magnesium yield in the condenser was low.Therefore,this paper constructs a condenser model of relative vacuum continuous magnesium refining process,and comprehensively analyzes the condensation mechanism of magnesium vapor through simulation and experiment.It is found that the dynamic characteristics of magnesium vapor condensation is an important index to measure its continuity.Under the condition offlowing argon as the protective gas,when the condensation plate spacing is 10 cm,the surface roughness amplitude variance is 2,and the carrier gasflow rate is 20×10^(-3) m/s,the magnesium vapor has a better condensation effect,and the condensation efficiency formula is derived.
基金supported by the Yunnan Province Nonferrous Metal Vacuum Metallurgy Top Team[No.202305AS350012]。
文摘Magnesium(Mg),as one of the most abundant elements in earth's crust,is the lightest structural metal with extensive applications across various industries.However,the performance of Mg-based products is highly dependent on their impurity levels,and the lack of high-purity Mg,along with efficient purification method,has posed significant challenge to its widespread industrial adoption.This study investigates the impurity behavior in Mg ingots during the vacuum gasification purification process.Through the analysis of binary phase diagrams,iron(Fe)-based foam material was selected for the filtration and purification of Mg vapor in a vacuum tube furnace.A novel approach combining vacuum gasification,vapor purification,and directional condensation is proposed.The effect of filter pore sizes and filtration temperatures on the efficacy of impurity removal was evaluated.Experimental results demonstrate that Fe-based foam with a pore size of 60 ppi,at a filtration temperature of 773 K,effectively removes impurities such as calcium(Ca),potassium(K),sodium(Na),manganese(Mn),silicon(Si),aluminum(Al),and various oxides,sulfides,and chlorides from the vapor phase.Consequently,high-purity Mg with a purity level exceeding 5N3 was obtained in the condensation zone.
