Browse Prior Art Database

Rapid Silver Recovery

IP.com Disclosure Number: IPCOM000049104D
Original Publication Date: 1982-May-01
Included in the Prior Art Database: 2005-Feb-09
Document File: 2 page(s) / 55K

Publishing Venue

IBM

Related People

Ellis, RE: AUTHOR

Abstract

Metallic silver is recovered from waste material by forming a saturated AgNO(3) solution which is then dripped onto a zinc, brass or copper plate. Silver-bearing waste may be any of the following: (a) Ag(2)S, Ag(2)O as from photo fixer sludge; (b) silver/base metal alloys including silver plate; and (c) silver-bearing ashes as from burned photographs. Exceptions: Waste known to contain ABC1 must first be treated to form Ag(2)O/Ag(2) S.

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Rapid Silver Recovery

Metallic silver is recovered from waste material by forming a saturated AgNO(3) solution which is then dripped onto a zinc, brass or copper plate. Silver-bearing waste may be any of the following: (a) Ag(2)S, Ag(2)O as from photo fixer sludge; (b) silver/base metal alloys including silver plate; and (c) silver-bearing ashes as from burned photographs. Exceptions: Waste known to contain ABC1 must first be treated to form Ag(2)O/Ag(2) S.

Silver-bearing waste 10 is contained in funnel 11 and paper filter 12. An AgNO(3) solution, initially diluted, is recirculated through waste 10 by means of flow path 13, until a silver-saturated solution is formed in container 14. Thereafter, the saturated solution is allowed to drip onto brass plate 15, from a height of about 25 millimeters.

Soft crystalline silver 16 deposits out of this solution onto the plate. The solution thereafter collects on the bottom of container 17. This solution has regained a portion of its acid (HNO(3)) properties. It is useful to pump this liquid back into the funnel 11 to create more AgNO(3).

As an aid to obtaining higher process efficiency, a semiconductor heat transfer device 18 and a fan 19 first cool the solution at the bottom of container 17, and then heat the solution prior to reintroduction of the solution to funnel 11 by way of conduit 20. Cooling in the area of silver formation reduces the redissolving of newly formed silver. Subsequent heating increases the dissolving...