真空蒸馏脱粗铋中银的新工艺

NEW TECHNIQUE OF DESILVERIZATION FROM CRUDE BISMUTH BY VACUUM DISTILLATION

为克服粗铋精炼中，传统的加锌除银工艺存在的效率低、污染环境等问题，提出了用真空蒸馏，将铋蒸馏、冷凝，银残留在蒸馏渣中的脱银工艺。实验研究表明，粗铋的真空蒸馏脱银在温度约１０５０℃和约３０Ｐａ真空条件下，经过两次一级蒸馏或一次两级蒸馏，使铋中含银量达到低于５×１０－４％的要求。据实验结论设计的内加热闭式多级连续粗铋真空蒸馏炉，具有进出料方便、炉况稳定、热效率高、自动控制和对环境无污染等优点。

In order to improve the traditional Parkes method of desilverization (zinc desilverization) for fining crude bismuth, the new technique of desilverization by vacuum distillation, in which bismuth is distilled and then condensed but silver remains in residue, has been investigated. The experimental results showed that under the following conditions, e.g. distillation temperature about 1 050 ℃, vacuum pressure about 30 Pa and either twice one grade distillation or once two grade distillation, the silver content in crude bismuth could be reduced to below 5×10 -4 %. A multistage inter heating closed vacuum furnace was roughly designed based on the experimental results. The designed furnace can be used for continuous production, and also has the advantages of the convenience for feeding and outlet of material, high heat efficiency and no pollution.