Study On The Volatilization Law Of Silver In Vacuum Distillation Copper-silver Alloy

Due to the complex electronic structure,with excellent electrical,optical and magnetic properties,copper and silver are used in many fields widely containing anode sludge and deserted solder,so that it will be of great importance to recycle silver from a variety of secondary resource.However,the sparation procedure of Ag-Cu alloy were brought high cost and long period that fall short of the subject of energy-saving and emission-reduction at present.Vacuum distillation has many advantages such as short flow sheet,pollution-free and high metal recoveries and so on,which makes it widely applied in the area of secondary material recovery.This study is investigated in the possibility of the sparation of Ag-Cu alloy by vacuum distillation,including the separation effect and mechamism which were researched in detail and scientificity.Silver can be obtained by treating the Ag-Cu-Sb alloy with the method of vacuum distillation,however,the mechanism concerning how the alloy of Ag-Cu and Ag-Cu-Sb changes during the distillation process is yet to be thoroughly investigated.And a role like Sb is played by the AIMD of Ag-Cu-Sb alloy are yet to be explained.Consequently,it will be of great scientific values for the vacuum distillation of Ag-Cu-Sb alloy by conducting researches investigating the structure and properties of it and the electronic properties of it.In this thesis,with the help of computer simulation,the structure and property of Ag-Cu,Ag-Cu-Sb liquid state alloy was investigated by adopting ab initio molecular dynamic,furthermore,comparison and verification of the results was performed by the Ag-Cu-Sb alloy vacuum distillation experiments.Activity for Ag-Cu under 1423K was predicted by different thermodynamic calculation model,compared to experimental values,and MIVM is the most feasible thermodynamic calculation model correctly.Ag-Cu activity coefficients were used to calculate separation coefficient and vapor-liquid phase equilibrium composition under different temperature(1473K,1573K,1673K,1773K and 1873K),which decide whether Ag-Cu could be separated by vacuum distillation in thermodynamics perspective.When the pressure was maintained at IOPa and the temperature was set during 1473K-1873K,the evaporation rate of Ag-Cu alloy was calculated,and the gas composition under the same conditions was that the mass fraction content of silver is above 85%accordingly;Ag3Sb and Cu2Sb are respectively chosen as the typification of Silver-Antimonide and Copper-Antimonide to calculate the initial decomposition temperature by Gibbs free energy at 10Pa and 105pa.The result of Gibbs free energy shows the possibility of Ag3Sb is easier than Cu2Sb's in thermal-decomposition reaction so that Sb would accelerate the volatilization behavior of Ag.Furthermore,dynamic simulation concerning the liquid state structure,surface structure of Ag-Cu binary alloy as well as the liquid structure of Ag-Cu-Sb ternary alloy was conducted by employing the ab initio molecular dynamic.And structure optimization of Ag-Cu binary alloy gas state cluster was performed.What's more,dynamic simulation of the stable cluster obtained was also conducted.The result indicates that when the pressure was maintained at 30Pa,the temperature was kept at 673K,873K,1053K,1273K and 1473K,the structural properties and movement orderliness of Ag and Cu were analyzed in Ag-30wt.%Cu binary alloy.The stable structure of Ag-30wt.%Cu alloy melt changes according to the change of temperaure,and it is difficult to separate the Ag-30wt.%Cu alloy by vacuum distillation when these stable structure exist under these conditions because the similar movement orderliness and structural property between Ag and Cu.From the results of clusters among AgnCun,AgnSbn,and CunSbn at normal temperature condition,the binding energy and HOMO-LUMO gap are revealed the interaction situation,electronic and orbital property including the bonding rule.The maximum binding energy is Cu-Sb bond and the minimum binding energy is Ag-Sb bond so that the results show that the diffusion of alloy atoms was accelerated,and the interaction between Ag-Cu atoms was reduced by Sb.Considering about the atomic radius,the mechamism is Sb atoms cover Cu atoms so that the Ag-Cu atoms interaction would be broke,due to the Ag-Sb binding energy is weaker than Cu-Sb binding energy,which caused the diffusion of Ag atoms was accelerated.Finally,to examine the accuracy of the abovementioned results theoretically,the vacuum distillation researches on Ag-Cu and Ag-Cu-Sb alloy was carried out.The experimental factor containing the raw material composition,the vapour temperature,volatilization space and constant temperature time were investigated in the method of single factor for the separation coefficient and vapor-liquid phase equilibrium composition.Expand the scale of experiments later,the raw materials mainly including Ag-Cu-Sb alloy were investigated for the evaporation rule of silver,which reveal Sb would accelerate the volatilization behavior of Ag,and Cu would obstruct the volatilization behavior of Ag.The experimental results were compared to theoretically calculation results,which is obtained that theoretically calculation results is feasible rules of the volatilization behavior of Ag.