Study On The Volatilization And Condensation Law Of Each Component Of Noble Lead Alloy In The Process Of Vacuum Separation

With the increasing demand for rare and precious metal resources in today's society and the increasingly severe environmental protection requirements,it is particularly important to extract rare and precious metals efficiently and cleanly from anode slime and noble lead produced in lead and copper smelting process.In recent years,vacuum distillation technology has been successfully applied to the treatment of this material,realizing the green and efficient smelting of gold and silver in anode slime,forming the most characteristic precious metal smelting process.However,the unclear rules of volatilization and condensation of components in noble lead restrict the development of vacuum distillation equipment to large-scale and high-efficiency direction.Therefore,through theoretical analysis,simulation calculation and experimental research,this paper carries out basic research on the volatilization and condensation law of each component,enriches the basic data of non-ferrous metallurgy,and lays a foundation for the further development of precious metal smelting process.Firstly,the thermodynamic and dynamic analysis of the separation of noble lead was carried out.The temperature and pressure range of separation of noble lead are obtained by the relation between saturated vapor pressure and temperature of pure metal.The vapor-liquid equilibrium diagram and binary phase diagram of Pb-Me and Sb-Me alloys are analyzed in depth,and the existing state and phase of each component after vacuum distillation and separation are explained.The distribution of each component in vacuum atmosphere is obtained by the molecular mean free path theory,and the influence of pressure and temperature on the dominant condensation region is revealed.Secondly,the volatilization and condensation of lead,antimony and silver in precious lead were systematically studied.The temperature gradient distribution between the evaporation surface and the condensation surface is revealed by COMSOL MULTIPHYSICS simulation;The effects of distillation temperature,constant temperature time and material quality on volatilization and condensation of volatile elements were studied;In addition,the theory is modified and the dominant condensation regions of Pb and Sb are 24?44 mm and 44?59 mm,respectively.Finally,the experimental results show that the selective condensation of lead and antimony in different regions is realized after the condensation height is adjusted;At950 ? and 1250 ?,the dominant condensation region of lead was in accordance with the normal distribution of "L=44" and "L=74" respectively;The dominant condensation region of antimony also conforms to the normal distribution of "L=44" at950 ?,and nearly linearly increases at 1250 ?.The optimum conditions were 1250 ?,10 Pa and 3 h.At this time,the direct yield of lead,bismuth and silver reached 91%,95% and 94%,respectively.