Process and apparatus for increased purification of pure metals such as indium by means of vacuum distillation

摘要

A 99.99% pure indium feed is charged into crucible 8 and heated to 1250 C. by upper heater 6 in a vacuum atmosphere at 110⁴ Torr, whereupon indium evaporates, condenses on the inner surfaces of inner tube 3 and drips to be recovered into liquid reservoir 9 in the lower part of tubular member 11 whereas impurity elements having lower vapor pressure than indium stay within crucible 8. The recovered indium mass in liquid reservoir 9 is heated to 1100 C. by lower heater 7 and the resulting vapors of impurity elements having higher vapor pressure than indium pass through diffuser plates 12 in the upper part of tubular member 11 to be discharged from the system whereas the indium vapor recondenses upon contact with diffuser plates 12 and returns to liquid reservoir 9, yielding 99.9999% pure indium while preventing the loss of indium.