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采用纯物质饱和蒸气压、分离系数和Pb-i系气-液相平衡成分图从热力学上分析粗铅真空蒸馏精炼脱除杂质的可行性。探讨粗铅中常见的杂质铜、锡、银、锌、砷、锑、铋在真空蒸馏精炼过程中的行为规律。结果表明:粗铅低温(923~1023 K)真空蒸馏时,锌和砷挥发进入气相而被除去,大部分锑挥发进入气相而实现与铅的分离,而铋则随铅残留于液相中无法除去。粗铅高温(1323~1423 K)真空蒸馏时,铅挥发进入气相冷凝,铜、锡、银不挥发而富集于残留物中被除去,铅挥发的同时铋也随着铅一起挥发进入气相无法除去。此理论为真空蒸馏脱除粗铅中的杂质提供新的思路,并能有效富集贵金属银等,对粗铅采用真空蒸馏精炼除杂具有一定的指导意义和实用价值。
The feasibility of impurity removal by crude lead vacuum distillation was analyzed thermodynamically using saturated vapor pressure of pure substance, separation coefficient and Pb-i system gas-liquid equilibrium composition diagram. To investigate the behavior of copper, tin, silver, zinc, arsenic, antimony and bismuth in common crude lead during vacuum distillation and refining. The results show that zinc and arsenic are volatilized into the gas phase when crude lead is distilled at low temperature (923 ~ 1023 K), and most of the antimony is volatilized into the gas phase to separate from lead. However, bismuth remains in the liquid phase with lead Remove. When the crude lead is distilled under vacuum at high temperature (1323-1423 K), the lead is volatilized into the vapor phase to condense. The copper, tin and silver are not concentrated in the residue and are enriched in the residue. The lead volatilizes while the lead volatilizes and enters the gas phase Remove. This theory provides a new idea for the vacuum distillation to remove impurities in crude lead, and can effectively enrich precious silver. It is of guiding significance and practical value for vacuum distillation and impurity removal of crude lead.