Lead extraction from spent lead–acid battery paste in a molten Na2CO3 salt containing Zn O as a sulfur-fixing agent was studied. Some influencing factors, including smelting temperature, reaction time, Zn O and salt ...Lead extraction from spent lead–acid battery paste in a molten Na2CO3 salt containing Zn O as a sulfur-fixing agent was studied. Some influencing factors, including smelting temperature, reaction time, Zn O and salt dosages, were investigated in detail using single-factor experiments. The optimum conditions were determined as follows: T = 880°C; t = 60 min; Na2CO3/paste mass ratio = 2.8:1; and the Zn O dosage is equal to the stoichiometric requirement. Under the optimum conditions, the direct recovery rate of lead reached 98.14%. The results suggested that increases in temperature and salt dosage improved the direct recovery rate of lead. XRD results and thermodynamic calculations indicated that the reaction approaches of lead and sulfur were Pb SO4→Pb and Pb SO4→Zn S, respectively. Sulfur was fixed in the form of Zn S, whereas the molten salt did not react with other components, serving only as a reaction medium.展开更多
The solution behavior, including solubility, reactivity and sedimentation, of ZnO and ZnS in a Na<sub>2</sub>CO<sub>3</sub>−NaCl molten salt used for Sb smelting was investigated in the tempera...The solution behavior, including solubility, reactivity and sedimentation, of ZnO and ZnS in a Na<sub>2</sub>CO<sub>3</sub>−NaCl molten salt used for Sb smelting was investigated in the temperature range of 700-1000 ºC. The saturated amount of dissolved ZnO in the molten salt remained constant at 0.02% and was unaffected by temperature; additionally, ZnO did not react with the molten salt. In contrast, the saturated amount of dissolved ZnS in the eutectic molten salt increased with increasing temperature, and the content of ZnS was 0.53% at 1000 ºC. In addition, ZnS reacted with Na<sub>2</sub>CO<sub>3</sub> above 900 ºC to give ZnO. The sedimentation rates of these three species in the molten salt followed the order of Sb>ZnS>ZnO. It was thus concluded that ZnO is an appropriate sulfur-fixing agent for low-temperature Sb smelting in a Na<sub>2</sub>CO<sub>3</sub>−NaCl molten medium, and that the optimal smelting temperature is below 900 ºC.展开更多
Cerium oxide film formed on the nickel electrode at 453 K in LiNO3-KNO3 molten salts. The molten salt background and the cathode process of Leeds on the nickel electrode were studied by using cyclic voltammetry. The c...Cerium oxide film formed on the nickel electrode at 453 K in LiNO3-KNO3 molten salts. The molten salt background and the cathode process of Leeds on the nickel electrode were studied by using cyclic voltammetry. The cathodic reaction mechanism of the molten salt background was: O-2(-)+e <----> O-2(-2); O-2+2NO(3)(-) --> 2NO(2)(-)+2O(2). According to the results of SEM and XPS, cerium oxide film, which is composed of CeO2, can form on the nickel electrode at - 1.850 V vs. Ag/AgNO3 (0.1 mol/L) reference electrode.展开更多
In this study,the mechanism of the reduction-diffusion reaction in a Sm-Fe binary system at low temperature was studied to investigate the possibility of synthesis of a Fe-rich TbCu_(7)-type SmFe_(x)(x>9)by the low...In this study,the mechanism of the reduction-diffusion reaction in a Sm-Fe binary system at low temperature was studied to investigate the possibility of synthesis of a Fe-rich TbCu_(7)-type SmFe_(x)(x>9)by the low-temperature diffusion-reduction(LTRD)process using LiCl-KCl eutectic molten salts.Firstly,the Sm-Fe phase transformation depending on the Sm-Fe composition,the LTRD temperature,and time was investigated,and it is found that the obtained metastable phase is only TbCu_(7)-type SmFe_(~8.5),which is not a Fe-rich phase.This Fe content does not change even after an expended LTRD process,and the metastable TbCu_(7)-type SmFe_(~8.5)tends to transform to the stable Sm_(2)Fe_(17)phase.In addition,it is found that the Sm-Fe phase starts to synthesize from the Sm-rich phase in the order of SmFe_(2),SmFe_(3),and SmFe_(8.5)as the LTRD temperature increases(when the time was 10 h)or the LTRD time increases(when the temperature was 550℃).Core-shell-like particles are observed in the case of a short LTRD time,and the core and the shell are Fe and the Sm-rich Sm-Fe phase,respectively,indicating that the Sm-rich phase begins to produce on the surface of the Fe particles.It is difficult to synthesize a Fe-rich TbCu_(7)-type SmFe_(x)(x>9)phase with the Sm-Fe binary system,suggesting that a different approach,such as addition of other elements,will be necessary.展开更多
In this study,the temperature of the low-temperature reduction-diffusion(LTRD)process was successfully decreased to below 600℃by introducing LiClKCl eutectic molten salt with a low eutectic point(352℃)as a solvent f...In this study,the temperature of the low-temperature reduction-diffusion(LTRD)process was successfully decreased to below 600℃by introducing LiClKCl eutectic molten salt with a low eutectic point(352℃)as a solvent for Ca reductant.Therefore,the Sm-Fe binary compounds,which were synthesizable at previously-unexplored low temperatures by the LTRD process using LiCl-KCl eutectic molten salt,were investigated,including whether a new metastable or ThMn_(12)-type Sm-Fe binary phase was formed.The Sm-Fe phase transitions of the SmFe binary compounds at a low temperature were identified,and it was found that MgCu_(2)-type Sm-Fe,PuNi_(3)-type SmFe and TbCu_(7)-type Sm-Fe phases were synthesized and stable at 400,500 and 550℃respectively.Although no new metastable Sm-Fe and ThMn_(12)-type Sm-Fe compounds were discovered in this study,this work can demonstrate that it is possible to synthesize the Sm-Fe phase at very low temperatures by the LTRD process for the first time.展开更多
对NaCl-KCl、NaCl-CaCl_(2)、NaCl-Na_(2)CO_(3)、NaCl-KCl-CaCl_(2)和NaCl-KCl-Na_(2)CO_(3)熔盐体系开展比较分析,研究不同熔盐体系的相图、热稳定性和硫化锑的溶解度。根据锑元素分布特征、电流效率、能耗及熔渣成分表征结果,优选出...对NaCl-KCl、NaCl-CaCl_(2)、NaCl-Na_(2)CO_(3)、NaCl-KCl-CaCl_(2)和NaCl-KCl-Na_(2)CO_(3)熔盐体系开展比较分析,研究不同熔盐体系的相图、热稳定性和硫化锑的溶解度。根据锑元素分布特征、电流效率、能耗及熔渣成分表征结果,优选出适合Sb_(2)S_(3)电解还原的熔盐体系。结果表明,所有熔盐体系均具有良好热稳定性,且可实现Sb_(2)S_(3)的电解还原。添加CaCl_(2)的体系不利于Sb_(2)S_(3)溶解,而添加Na_(2)CO_(3)的体系会与Sb_(2)S_(3)发生反应。此外,NaCl-KCl体系的电流效率最高(75.68%),且能耗最低(2.18 k W·h/kg)。展开更多
基金financially supported by the National Nature Science Foundation of China (Nos. 51234009 and 51104182)the Natural Science Foundation of Hunan Province, China (No. 13JJ5035)the Scientific Research Fund of Hunan Provincial Education Department, China (No. 14C0349)
文摘Lead extraction from spent lead–acid battery paste in a molten Na2CO3 salt containing Zn O as a sulfur-fixing agent was studied. Some influencing factors, including smelting temperature, reaction time, Zn O and salt dosages, were investigated in detail using single-factor experiments. The optimum conditions were determined as follows: T = 880°C; t = 60 min; Na2CO3/paste mass ratio = 2.8:1; and the Zn O dosage is equal to the stoichiometric requirement. Under the optimum conditions, the direct recovery rate of lead reached 98.14%. The results suggested that increases in temperature and salt dosage improved the direct recovery rate of lead. XRD results and thermodynamic calculations indicated that the reaction approaches of lead and sulfur were Pb SO4→Pb and Pb SO4→Zn S, respectively. Sulfur was fixed in the form of Zn S, whereas the molten salt did not react with other components, serving only as a reaction medium.
基金Projects(51104128,51234009)supported by the National Natural Science Foundation of China
文摘The solution behavior, including solubility, reactivity and sedimentation, of ZnO and ZnS in a Na<sub>2</sub>CO<sub>3</sub>−NaCl molten salt used for Sb smelting was investigated in the temperature range of 700-1000 ºC. The saturated amount of dissolved ZnO in the molten salt remained constant at 0.02% and was unaffected by temperature; additionally, ZnO did not react with the molten salt. In contrast, the saturated amount of dissolved ZnS in the eutectic molten salt increased with increasing temperature, and the content of ZnS was 0.53% at 1000 ºC. In addition, ZnS reacted with Na<sub>2</sub>CO<sub>3</sub> above 900 ºC to give ZnO. The sedimentation rates of these three species in the molten salt followed the order of Sb>ZnS>ZnO. It was thus concluded that ZnO is an appropriate sulfur-fixing agent for low-temperature Sb smelting in a Na<sub>2</sub>CO<sub>3</sub>−NaCl molten medium, and that the optimal smelting temperature is below 900 ºC.
基金[The project was financially supported by the National Science Foundation of China.]
文摘Cerium oxide film formed on the nickel electrode at 453 K in LiNO3-KNO3 molten salts. The molten salt background and the cathode process of Leeds on the nickel electrode were studied by using cyclic voltammetry. The cathodic reaction mechanism of the molten salt background was: O-2(-)+e <----> O-2(-2); O-2+2NO(3)(-) --> 2NO(2)(-)+2O(2). According to the results of SEM and XPS, cerium oxide film, which is composed of CeO2, can form on the nickel electrode at - 1.850 V vs. Ag/AgNO3 (0.1 mol/L) reference electrode.
文摘In this study,the mechanism of the reduction-diffusion reaction in a Sm-Fe binary system at low temperature was studied to investigate the possibility of synthesis of a Fe-rich TbCu_(7)-type SmFe_(x)(x>9)by the low-temperature diffusion-reduction(LTRD)process using LiCl-KCl eutectic molten salts.Firstly,the Sm-Fe phase transformation depending on the Sm-Fe composition,the LTRD temperature,and time was investigated,and it is found that the obtained metastable phase is only TbCu_(7)-type SmFe_(~8.5),which is not a Fe-rich phase.This Fe content does not change even after an expended LTRD process,and the metastable TbCu_(7)-type SmFe_(~8.5)tends to transform to the stable Sm_(2)Fe_(17)phase.In addition,it is found that the Sm-Fe phase starts to synthesize from the Sm-rich phase in the order of SmFe_(2),SmFe_(3),and SmFe_(8.5)as the LTRD temperature increases(when the time was 10 h)or the LTRD time increases(when the temperature was 550℃).Core-shell-like particles are observed in the case of a short LTRD time,and the core and the shell are Fe and the Sm-rich Sm-Fe phase,respectively,indicating that the Sm-rich phase begins to produce on the surface of the Fe particles.It is difficult to synthesize a Fe-rich TbCu_(7)-type SmFe_(x)(x>9)phase with the Sm-Fe binary system,suggesting that a different approach,such as addition of other elements,will be necessary.
基金financially supported by"Adaptable and Seamless Technology Transfer Program through Target-Driven R&D(A-STEP),(No.JPMJTM20EB)commissioned by the Japan Science and Technology Agency(JST)。
文摘In this study,the temperature of the low-temperature reduction-diffusion(LTRD)process was successfully decreased to below 600℃by introducing LiClKCl eutectic molten salt with a low eutectic point(352℃)as a solvent for Ca reductant.Therefore,the Sm-Fe binary compounds,which were synthesizable at previously-unexplored low temperatures by the LTRD process using LiCl-KCl eutectic molten salt,were investigated,including whether a new metastable or ThMn_(12)-type Sm-Fe binary phase was formed.The Sm-Fe phase transitions of the SmFe binary compounds at a low temperature were identified,and it was found that MgCu_(2)-type Sm-Fe,PuNi_(3)-type SmFe and TbCu_(7)-type Sm-Fe phases were synthesized and stable at 400,500 and 550℃respectively.Although no new metastable Sm-Fe and ThMn_(12)-type Sm-Fe compounds were discovered in this study,this work can demonstrate that it is possible to synthesize the Sm-Fe phase at very low temperatures by the LTRD process for the first time.
基金the financial supports from the National Natural Science Foundation of China(No.52074362)。
文摘对NaCl-KCl、NaCl-CaCl_(2)、NaCl-Na_(2)CO_(3)、NaCl-KCl-CaCl_(2)和NaCl-KCl-Na_(2)CO_(3)熔盐体系开展比较分析,研究不同熔盐体系的相图、热稳定性和硫化锑的溶解度。根据锑元素分布特征、电流效率、能耗及熔渣成分表征结果,优选出适合Sb_(2)S_(3)电解还原的熔盐体系。结果表明,所有熔盐体系均具有良好热稳定性,且可实现Sb_(2)S_(3)的电解还原。添加CaCl_(2)的体系不利于Sb_(2)S_(3)溶解,而添加Na_(2)CO_(3)的体系会与Sb_(2)S_(3)发生反应。此外,NaCl-KCl体系的电流效率最高(75.68%),且能耗最低(2.18 k W·h/kg)。
