| The yield of antimony ranks our country the first in the world. But the production of antimony is only a few except antimony ingot. Many foreign countries gain huge profit through importing Chinese crude antimony and selling to China again by further processing. So further processing crude antimony and developing new kinds of antimony are very necessary to Chinese economic development.With the development of high technology, the use of high purity metals are more and more wide, such as 4N, 5N, 6N antimony, which have high economic values. However, on account of the technological restriction of high purity antimony, the increase of high purity antimony yield is difficult. There are strictly technological requirements to domination process in the procedure. So a new method of preparing 4N antimony by vacuum distillation is brought forward in the dissertation. The theoretic analysis is done, and new technology of preparing 4N antimony is obtained through experiment study.According to the standard of high purity antimony, the content of fourteen impurities in the raw material is analysed. Firstly, the thermodynamics analysis is carried through. According to different boiling point, we can predict that the antimony can be separated from the impurities. Then the vapour pressures of pure substance of antimony and impurities are compared under different temperature. The impurities in the raw material are classified through vapour pressures of pure substance. One kind is more volatilizable than antimony, the other is much more difficult to evaporate than antimony. According to different vapour pressures of pure substance the antimony can be separated from the impurities. At the same time another criterion which can judge the feasibility to separate the antimony from the impurities, is separation coefficient . The antimony is looked as chief body, separation coefficient, phase diagram, and gas-liquid equilibrium composition diagram of antimony-based binary alloy are analysed. The results show that antimony can be separated from the impurities under vacuum condition, too. Secondly, the kinetics study is carried through. There are four restriction processes which influencethe impurities' evaporation from the antimony. The first process is the impuritiesdiffusion from the inside of the liquid antimony to the surface. The second is the impurities' evaporation on the liquid antimony surface. The third is the diffusion of impurities gas in the residual gas of vacuum furnace. The last is the condensation of impurities gas. According to the experiment condition, the impurities diffusion from the inside of liquid antimony to the surface is a main process, which greatly influences the separation between antimony and impurities. Then the zone refine is also discussed, and shows that zone refine can produce higher purity antimony on the basis of vacuum distillation.According to the thermodynamics and kinetics analysis of vacuum distillation, the experiment research is carried through. The first is separation of antimony and arsenic by inner-heating vacuum furnace. Three kinds of experiment show that the antimony can be separated from the arsenic under definite temperature and pressure. Then the kilogram level experiments are gone along by outer-heating vacuum furnace. Three methods are adopted. The first method is that it makes the arsenic and low boiling-point impurities evaporate from the liquid antimony, and make the antimony and high boiling-point impurities remain. The second method is that the gas is inflooded the liquid antimony in order to stir the liquid. It can accelerate the diffusion of arsenic and low boiling-point impurities in the liquid and increase the evaporation quantity, but the antimony and high boiling-point impurities would be remained. The third method makes the antimony, arsenic and low boiling-point impurities evaporate simultaneously by lowering the pressure in the vacuum furnace. The arsenic and low boiling-point impurities can be separated from the antimony by different condensat... |
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