Patent ID: 6932852
Filing Date: 2005-08-23
Classification: C22B,Y10S

Abstract:
1. A method of enhanced purification of a high-purity metal by purifying a metal feed by distillation in a vacuum atmosphere to yield a desired metal with high purity, said method comprising carrying out a first thermal purification step in which said metal feed in a feed crucible positioned in an upper interior of an inner tube maintaining said vacuum atmosphere is heated and the generated vapor of said desired metal is brought into contact with an inner surface of said inner tube so that the vapor of said desired metal is condensed and recovered in a separate form from impurity elements that have a lower vapor pressure than said desired metal and which are allowed to stay within said feed crucible, and carrying out a second thermal purification step in which said desired metal as recovered is admitted into and heated in a liquid reservoir in a lower part of a tubular member positioned in a lower interior of said inner tube and the generated vapor is passed through a diffuser positioned in an upper part of said tubular member and guided by suction so that the vapor of impurity elements having a higher vapor pressure than said desired metal are solidified in a separate form in a cooling trap positioned below said tubular member and the vapor of said desired metal is brought into contact with said diffuser so that the vapor of said desired metal is condensed and returned to said liquid reservoir, said method being carried out in a purifying apparatus comprising a rigid shell outer tube that accommodates said inner tube, said outer tube having an inner wall which is entirely covered with a carbonaceous heat-insulating material and having an upper heater and a lower heater, each of said upper heater and said lower heater being made of a carbonaceous material, said inner tube, said crucible, said diffuser and any other members placed in said inner tube are made of a carbonaceous material.