Preparation of high-purity bismuth by sulphur deleadization in vacuum distillation

The feasibility of separation of impurities in refined bismuth and sulphur deleadization with vacuum distillation was studied theoretically. Experimental studies on sulphur deleadization were carried out under vacuum. The influences of amount of sulphur, distillation temperature, vacuum degree and distillation time on deleadization were investigated and an optimal technical condition was achieved. The content of lead in refined bismuth can be decreased from 30 μg/g to 0.21 μg/g, which has reached the level of “5N” high-purity bismuth. Other impurities in refined bismuth can be also removed effectively under certain conditions.

精铋的真空蒸馏硫化除铅

从理论上分析了用真空蒸馏分离精铋中各杂质和通过加硫除铅的可行性。在真空炉内进行了精铋加硫除铅的实验研究,考察了加硫量、蒸馏温度、残压和蒸馏时间以及加硫次数等因素对除铅效果的影响,得到了最佳工艺条件:每克铋加硫量控制在0.02 g左右、蒸馏温度约1073 K、残压控制在16 Pa左右,蒸馏时间不超过15 min。在此条件下可将金属铋中的杂质铅含量由30μg/g降到了0.21μg/g,达到了“5N”高纯铋的要求。良好的实验结果表明,精铋硫化除铅具有工艺流程简单、改善劳动环境及提高生产率等优点,是一种去除精铋中铅的有效方法。