Theoretical And Experimental Study On Vacuum Distillation Of Pb - Sb Binary Alloy

There will produce large amounts of Pb-Sb alloy during the process of lead and antimony smelting, in order to improve the space utilization of Pb-Sb alloy efficiently, the issue which is secondary recycling, green regeneration and comprehensive utilization of complex lead-antimony resources has been very crucial in metallurgical field. Vacuum metallurgy theory is a new theory in recent years, aimed at using green and clean mothods to dispose all kinds of alloys, it also has some advantages, such as short process, no pollution and high metal recovery rate, etc. The existing theory of vacuum distillation is not yet complete, however, it can only judge the possibility of separation in alloy and estimate gas liquid ingredients roughly. In this paper, adopting Pb-Sb binary alloy as the research object, the activity of Pb and Sb has been precdicted and measured by using thermodynamic model and experimental method, respectively. The theory and experiment of gas-liquid equilibrium have been researched, too. Calculating the all activities of Pb-Sb alloy in all range of ingredients by using accurate prediction model, then, combining the theory of vacuum distillation and phase equilibrium theory to construct the gas liquid equilibrium model of Pb-Sb binary alloy and draw the gas liquid equilibrium of Pb-Sb binary alloy for filling the blank of gas liquid equilibrium in metallurgical field, enriching the thermodynamic data of alloy, improving the basic theory of vacuum distillation. This theory has guiding significance on separation of alloy and providing theoretical support for non-ferrous metallurgical industry.(1) Firstly, using different models to calculate the activities of Pb-Sb binary alloy: establish MTVM, Wilson equation and Miedema model, respectively, calculate the activities of Pb-Sb binary alloy in the temperature range from 1073K to 1573K.(2) Secondary, adopting electromotive force mothod (EMF) to mensurate the activities of Pb-Sb binary alloy. ①Using CaF2 and yttria stabilized zirconia (8 YSZ) as the solid electrolyte to establish primary battery and mensurate the Pb-Sb binary alloy, show that:CaF2 and 8YSZ solid electrolyte are improper to mensurate the electromotive force of Pb-Sb binary alloy. ② Using LiCl-KCl-PbCl2 solution as liquid electrolyte to establish primary battery and mensurate the activities of Pb-Sb binary alloy (mole fraction of lead are 0.2,0.4,0.6 and 0.8, respectively.) in the temperature range from905K to 1073K (Temperature interval is 25 K),then compare the calculated value with experimental value we can see, the average relative deviation is less than 1, it illustrate that adopting LiCl-KCl-PbCl2 liquid electrolyte to mensurate the activities of Pb-Sb binary alloy is feasible.(3) Compare and select the calculated value which are predicted by MIVM, Wilson equation and Miedema model with literature value and experimental value we can know:average relative deviation of MIVM is the smallest, average relative deviation of Wilson equation is a little big, but double results are all less than 2%. However, average relative deviation of Miedema model is the biggest, approximately 17%. So, predictive effect:MIVM> Wilson equation> Miedema model, it can illustrate that it’s feasible to predict the activities of Pb-Sb binary alloy by using MIVM.(4) Combine predicted activities of Pb-Sb binary alloy by using MIVM with the theory of vacuum distillation, vacuum metallurgy and gas-liquid equilibrium, then establish gas-liquid equilibrium diagram of Pb-Sb system (T-x-y diagram and P-x-y diagram). The optimal experimental condition can be determined before experiments based on the VLE phase diagram. Above all, the distribution of components of alloy dependence of temperature and pressure can be predicted using VLE phase diagram, from which the production component can also be predicted.(5) Finally, the VLE was determined experimentally for Pb-Sb binary alloy. Compare experimental value with calculated value which precdict by gas-liquid equilibrium diagram we can see, calculated value is consistent with the experimental value, the results show that the Pb-Sb binary VLE model built up in this work was reliable.