To provide an accurate prediction of the product component dependence of temperature and pressure in vacuum distillation and give convenient and efficient guidance for the designing of the process parameters of indust...To provide an accurate prediction of the product component dependence of temperature and pressure in vacuum distillation and give convenient and efficient guidance for the designing of the process parameters of industrial production, according to the molecular interaction volume model(MIVM), the separation coefficient(β) and vapor-liquid equilibrium composition of Au-Ag alloy at different temperatures are calculated. Combined with the vapor-liquid equilibrium(VLE) theory, the VLE phase diagrams, including the temperature-composition(T-x) and pressure-composition(p-x) diagrams of Au-Ag alloy in vacuum distillation are plotted. The triple points and condensation temperatures of gold and silver vapors are calculated as well. The results show that the β decreases and the contents of gold in vapor phase increase with the distillation temperature increasing. Low pressures have positive effect on the separation of Ag and Au. The difference between the condensation temperatures of gold and silver is about 450 K in the pressure range of 1-10 Pa.展开更多
Magnesium alloys,regarded as the most promising structural materials for lightweight applications,have gained enhanced strength and heat resistance through the addition of rare earth elements,leading to their widespre...Magnesium alloys,regarded as the most promising structural materials for lightweight applications,have gained enhanced strength and heat resistance through the addition of rare earth elements,leading to their widespread use in aerospace and defense industries.However,with the growing volume of end-of-life components and inherently low production yields,the efficient recycling of rare earth-containing magnesium alloys has become increasingly critical.This study explores the separation and enrichment behavior of magnesium and neodymium during the vacuum recycling of rare earth magnesium alloys,utilizing gas-liquid phase theory and phase diagram computational methods.Both theoretical analyses and experimental results indicate that the separation process in the Mg-Nd system—whether by vacuum distillation or gasification—follows a consistent phase transformation sequence:Mg_(41)Nd_(5)→Mg_(3)Nd→MgNd→Nd.Two distinct neodymium-rich morphologies were observed:a loose porous structure and a dense,compact form.Notably,vacuum gasification of ZM6 rare earth magnesium alloy resulted in a neodymium concentration of 82.91 wt.%in the solid residue.The process demonstrated high direct recovery efficiency,rapid separation kinetics,and zero secondary waste generation—establishing it as a green and highly efficient recycling approach for magnesium alloy scrap.These findings provide fundamental theoretical and practical support for the recycling of Nd-containing magnesium alloys and contribute to the sustainable utilization of secondary rare earth resources.展开更多
Nickel-based superalloy was treated with molten zinc for the selective extraction of nickel.The effects of heating temperature,heating time,and the mass ratio of zinc to superalloy on the extraction of metals in the s...Nickel-based superalloy was treated with molten zinc for the selective extraction of nickel.The effects of heating temperature,heating time,and the mass ratio of zinc to superalloy on the extraction of metals in the superalloy were investigated.An extraction rate of 95.2%for nickel,55.4%for iron and 30.4%for chromium,but low extraction rates of the refractory metals(titanium(Ti),molybdenum(Mo),and niobium(Nb))were obtained under the optimal conditions of the heating temperature of 850℃,the heating time of 4 h,and the zinc/superalloy mass ratio of 10:1.In the subsequent vacuum distillation process,the obtained nickel alloy contained nickel with a purity of 73.5 wt.%after zinc removal.Moreover,the recovered zinc after the distillation process had a purity of 99.9 wt.%.The results of the investigated process indicated the possibility of extracting nickel directly from nickel-based superalloy scraps.展开更多
基金supported by the National Natural Science Foundation of China (No.52064029)Yunling Scholarship of Yunnan Province Ten-Thousand Plan,China (No.KKRC201952012)Yunnan Province Ten Thousand Talents Program-Youth Top Talent Project,China (No.2018-73)。
文摘To provide an accurate prediction of the product component dependence of temperature and pressure in vacuum distillation and give convenient and efficient guidance for the designing of the process parameters of industrial production, according to the molecular interaction volume model(MIVM), the separation coefficient(β) and vapor-liquid equilibrium composition of Au-Ag alloy at different temperatures are calculated. Combined with the vapor-liquid equilibrium(VLE) theory, the VLE phase diagrams, including the temperature-composition(T-x) and pressure-composition(p-x) diagrams of Au-Ag alloy in vacuum distillation are plotted. The triple points and condensation temperatures of gold and silver vapors are calculated as well. The results show that the β decreases and the contents of gold in vapor phase increase with the distillation temperature increasing. Low pressures have positive effect on the separation of Ag and Au. The difference between the condensation temperatures of gold and silver is about 450 K in the pressure range of 1-10 Pa.
基金supported by the National Natural Science Foundation of China(No.92475108)Yunnan Province Nonferrous Metal Vacuum Metallurgy Top Team(No.202305AS350012).
文摘Magnesium alloys,regarded as the most promising structural materials for lightweight applications,have gained enhanced strength and heat resistance through the addition of rare earth elements,leading to their widespread use in aerospace and defense industries.However,with the growing volume of end-of-life components and inherently low production yields,the efficient recycling of rare earth-containing magnesium alloys has become increasingly critical.This study explores the separation and enrichment behavior of magnesium and neodymium during the vacuum recycling of rare earth magnesium alloys,utilizing gas-liquid phase theory and phase diagram computational methods.Both theoretical analyses and experimental results indicate that the separation process in the Mg-Nd system—whether by vacuum distillation or gasification—follows a consistent phase transformation sequence:Mg_(41)Nd_(5)→Mg_(3)Nd→MgNd→Nd.Two distinct neodymium-rich morphologies were observed:a loose porous structure and a dense,compact form.Notably,vacuum gasification of ZM6 rare earth magnesium alloy resulted in a neodymium concentration of 82.91 wt.%in the solid residue.The process demonstrated high direct recovery efficiency,rapid separation kinetics,and zero secondary waste generation—establishing it as a green and highly efficient recycling approach for magnesium alloy scrap.These findings provide fundamental theoretical and practical support for the recycling of Nd-containing magnesium alloys and contribute to the sustainable utilization of secondary rare earth resources.
基金financial supports from the National Natural Science Foundation of China(Nos.51922108,51874371,51904350)the Hunan Natural Science Foundation,China(No.2019JJ20031)the Hunan Key Research and Development Program,China(No.2019SK2061)。
文摘Nickel-based superalloy was treated with molten zinc for the selective extraction of nickel.The effects of heating temperature,heating time,and the mass ratio of zinc to superalloy on the extraction of metals in the superalloy were investigated.An extraction rate of 95.2%for nickel,55.4%for iron and 30.4%for chromium,but low extraction rates of the refractory metals(titanium(Ti),molybdenum(Mo),and niobium(Nb))were obtained under the optimal conditions of the heating temperature of 850℃,the heating time of 4 h,and the zinc/superalloy mass ratio of 10:1.In the subsequent vacuum distillation process,the obtained nickel alloy contained nickel with a purity of 73.5 wt.%after zinc removal.Moreover,the recovered zinc after the distillation process had a purity of 99.9 wt.%.The results of the investigated process indicated the possibility of extracting nickel directly from nickel-based superalloy scraps.
