Pb-Sn-Sb三元合金气液相平衡研究

It is very important to recycle the Pb-Sn-Sb alloys produced from the smelting process of Pb, Sn and Sb and their consumption process. Vacuum distillation has many advantages such as short flow sheet, high metal recovery and no pollution in disposing of the Pb-Sn-Sb alloys. The existing vacuum distillation theory, however, still stays in the binary alloy systems, which cannot support the research of ternary and multi-component alloy systems. Firstly, the model prediction and experimental determination of activities of components in Pb-Sn-Sb alloy will be carried out. The influencing rule of activities to the distribution characteristics of components of Pb-Sn-Sb alloy in liquid and vapor phase will be established. The model of vapor-liquid phase equilibrium will be built up, and experiments will be carried out in this project. Secondly, the activities of components of Pb-Sn-Sb alloy will be obtained, the model that was used to predict activities of components of Pb-Sn-Sb alloy will be revised and improved; the vapor-liquid phase equilibrium of Pb-Sn-Sb ternary alloy system will be established, the prediction model that was used to predict the vapor-liquid phase equilibrium of components of ternary alloy systems in vacuum distillation will be built up in this project by solving the following key scientific problems: the model that was used to predict activities of components of Pb-Sn-Sb alloy will be selected, the prediction model of vapor-liquid phase equilibrium of components in Pb-Sn-Sb alloy in vacuum distillation will be built up. This project can provide the reliable theoretical foundation for recycling of Pb-Sn-Sb alloys efficiently and cleanly, and can enrich and perfect the vacuum distillation theory of multi-component alloys.

回收利用铅、锡及锑冶炼和消费过程中产生的Pb-Sn-Sb合金意义重大。真空蒸馏处理Pb-Sn-Sb合金具有流程短、无污染、金属回收率高等优点。但现有的真空蒸馏理论尚停留在二元合金体系，难以支持三元和多元合金体系的研究，本课题以Pb-Sn-Sb三元合金为对象，开展组元活度的预测和实验测定研究、组元活度对元素分布行为特性影响规律研究、元素气液相平衡建模和实验研究。通过对Pb-Sn-Sb合金组元活度预测模型的选取和元素气液相平衡预测模型的建立等关键科学问题的研究，获得Pb-Sn-Sb合金组元的活度数据，修正、完善预测Pb-Sn-Sb合金组元活度的热力学模型；建立Pb-Sn-Sb三元合金体系的气液相平衡关系，构建三元合金气液相平衡的预测模型。研究结果将为Pb-Sn-Sb合金高效、清洁回收利用提供可靠的理论依据，丰富和完善多元合金真空蒸馏理论。

项目组以Pb-Sn-Sb合金体系为对象，围绕活度预测模型的筛选、气液相平衡预测模型的建立等关键问题，进行了以下研究：(1）采用Wilson方程、Miedema模型及分子相互作用体积模型（MIVM）计算了Pb-Sn、Pb-Sb、Sn-Sb二元合金组元的活度值，比较了预测值与文献值的偏差；采用MIVM、Wilson方程、Toop模型，Kohler模型及新一代周国治几何模型（Chou’s model）计算了1073K-1573K温度范围内Pb-Sn-Sb三元合金各组元的活度。（2）研究了液态电解质纯净度、电极副反应、固体电解质电学性能等因素对电动势测定的影响，根据合金真空蒸馏实际温度区间，设计了不同的活度测定方案，准确地获得了不同温度下Pb-Sn-Sb合金体系组元的活度值等热力学数据。（3）通过对关键参数合理取值，对MIVM进行了简化；以活度测定值为标准，对简化的MIVM、Wilson方程等模型进行了预测精度筛选，确定了简化的MIVM在Pb-Sn-Sb合金体系组元活度预测最可靠。（4）以活度为基础，计算得到了二元合金真空蒸馏分离系数，绘制了Pb-Sn-Sb三元合金体系的气液相平衡成分图，提出了Pb-Sn-Sb合金体系气液相平衡关系科学表达式，绘制了气液相平衡相图（T-x(y)和p-x(y)相图），建立了Pb-Sn-Sb合金体系气液相平衡成分预测模型，揭示了合金真空蒸馏分离的可能性及合金组元在气、液相中的分布规律。（5）系统地开展了Pb-Sn-Sb合金体系的真空蒸馏实验研究，将实验值与气液平衡相图进行对比，验证了气液相平衡关系科学表达式及气液平衡相图的科学可靠性；结合化工理论，设计了新的气液平衡测定方案，获得了与气液平衡相图吻合的实验数据。项目研究结果丰富了多元合金的热力学数据，查明了热力学模型的适用条件，拓宽了气液相平衡理论在高温熔体理论研究中的应用范围，完善了真空蒸馏基础理论，为有色金属合金真空分离实践提供了可靠的理论依据和指导。