Study On Gas-liquid Equilibrium Of Zinc-based Binary Alloy System

Vacuum distillation is widely used in the separation and purification of non-ferrous alloys because of its advantages of short process,no pollution,simple equipment and high metal recovery.The separation coefficient can only roughly judge the separation degree of alloy,and it is difficult to provide more accurate experimental condition information(such as temperature,pressure,etc.)for the separation of alloy.Therefore,it is necessary to carry out vapor liquid equilibrium research In order to provide theoretical guidance for the efficient separation of alloys by vacuum distillation,VLE(equilibrium)was used to predict the distribution of alloy components in the gas and liquid phases at a certain temperature and pressure.In this paper,the activities of Zn-X(X= Ni,Ag,Al,Sn,Bi)Zn-based binary alloys were calculated by Wilson equation,MIVM,SRSM and RSM,respectively,and the prediction bias was calculated.The results show that the average standard deviation and average relative deviation of Wilson equation are the smallest,which are ± 0.012% and 3.460%,respectively.Then,the vapor-liquid equilibrium data of Zn-X(X= Ni,Ag,Al,Sn,Bi)Zn-based binary alloys system under vacuum distillation were calculated by Wilson Equation,and the gas-liquid equilibrium phase diagram(T-x-y diagram)was drawn.Under the guidance of VLE and vacuum distillation theory,vacuum distillation experiments of Zn-Ni and Zn-Ag binary alloys were carried out.The results show that for Zn-Ni alloy,the purity of residual Ni is above99.5% when the temperature reaches 1573K;for Zn-Ag alloy,the purity of Ag reaches more than 99.99% when the temperature reaches 1373 K.The distribution of the alloy components in the gas and liquid phases under the condition of 5?10Pa was obtained by analyzing the content of the residue and volatile.Herington test and Van Ness test were used to check the thermodynamic consistency of VLE calculated value and experimental value.The results show that the experimental value and calculated value are consistent with the thermodynamic consistency.The comparison between the experimental data and the theoretical calculation results shows that the experimental values and the calculated values are basically consistent.Compared with the T-x-y phase diagrams calculated by Wilsonequation and VLE data obtained by experiment,the change trend of experimental points is basically consistent with the theoretical value,which shows that VLE data and phase diagram calculated by Wilson equation can guide the vacuum distillation separation of alloy.This study not only enriched the thermodynamic data of Zn-based binary alloys system,improved the basic theory of vacuum distillation,but also provided theoretical support for the efficient separation of Zn-based alloys.