真空蒸馏银锌壳时铅锌的蒸发速率

The Evaporation Rates of Lead and Zinc in Vacuum Distillation Ag-Zn-Pb Crust

本文介绍银锌壳真空蒸馏时,锌、铅蒸发速率与温度、残压、熔体深度的关系实验结果,并讨论过程和动力学性质。锌、铅的蒸发速率达到有应用价值的必须温度分别为700℃和1050℃。此温度下锌、铅蒸发速率分别为2.2×10^(-3)g/cm^2·S和2.0×10^(-3)g/cm^2·S.温度是影响铅蒸发速率的最主要因素.压力的减小促使锌、铅蒸发速率增大,在1000℃时蒸馏铅所要求的残压不能大于13.3Pa.在熔体无搅拌,压力为13.3Pa时蒸馏过程相应的活化能为E_(Zn)=68.51J;E_(Pb)=142.54J. 锌在蒸馏过程中表现出两个不同级反应,蒸馏初期为零级反应,热传导支配蒸发率.蒸馏后期为一级反应,受扩散过程所控制.铅的蒸馏则受气相和熔体的扩散所限制。

The experimental results for relationship of the temperature, the residual pressure and the melt depth on evaporation rates of lead and zinc are presented in this paper and the kinetic property in process is discussed as well. 700℃ and 1050℃ are respectively the necessary temperatures under which evaporation rates of zinc and lead can reach applied-value temperatures. Under the temperatures the evaporation rates of zinc and lead are 2.2×10^(-3)g cm℃2·s and 2.0×10^(-3)g cm^(-2)·sec^(-1).Temperature is the most important factor to influence the increase of the evaporation rates of lead. At 1000℃, the residual pressure required in evaporation lead can not be more than 13.3Pa.The corresponding activation energies Ezn and Epb are 16.39 and 34.10 kcal when the pressure is 13.3Pa and the melt is not stirred. The two different orders of reactions are presented in the process of zinc evaporation. The initial evaporation peried is zero of reactian in which evaporation tate is controlled by themoconduct.The last evaporation period is first ouder of reaction in which evaporation rate is controlled by diffasion, while lead evaporation is limited by the diffusions of gasial phase and melt.