The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 15, 2001
Filed:
Feb. 24, 1999
Dowa Mining Co., Ltd., Tokyo, JP;
Abstract
A process for producing a high-purity silver material comprising placing a silver feed in a crucible disposed in a furnace comprising an inner cylinder which encloses the crucible and an outer cylinder which encloses the inner cylinder; heating the silver feed at a temperature not lower than 1065° C. and at a pressure not higher than 0.1 Pa such that the silver evaporates and condenses on the ceiling of the inner cylinder to yield silver particles; and collecting silver particles in a recovery mold disposed beneath the crucible and within the inner cylinder, 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within the crucible, whereas sulfur, sodium and the other impurities having a higher vapor pressure than silver are withdrawn by a vacuum pump and are then introduced into a cooling trap disposed beneath the recovery mold, such that the higher vapor pressure impurities are solidified in the cooling trap.