Patent ID: 6231637
Filing Date: 2001-05-15
Classification: B22F,C22B,Y02P

Abstract:
A process for producing a high-purity silver material which comprises:(a) placing a silver feed in a crucible disposed in a furnace, said furnace comprising an inner cylinder which encloses said crucible and an outer cylinder which encloses the inner cylinder, said inner cylinder having a ceiling;(b) heating the silver feed within the crucible to a temperature of 1200 to 1350.degree. C. and at a pressure of 0.02 Pa or less such that the silver evaporates and condenses on the ceiling of the inner cylinder to yield silver particles; and(c) recovering the silver particles in a recovery mold disposed beneath the crucible and within the inner cylinder for purifying the silver, such that gold, copper and other impurities having a lower vapor pressure than silver remain within the crucible, whereas sulfur, sodium and the other impurities having a higher vapor pressure than silver are withdrawn by a vacuum pump and are introduced into a cooling tray disposed beneath the recovery mold, said impurities having a higher vapor pressure than silver being solidified in said cooling trap.