Chemistry: electrical and wave energy – Apparatus – Electrolytic
Patent
1991-11-12
1993-04-20
Valentine, Donald R.
Chemistry: electrical and wave energy
Apparatus
Electrolytic
204275, 204290R, 204294, 204297R, 204278, C25C 700, C25C 120, C25C 702, C25D 1700
Patent
active
052039790
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a device for the electrolytic recovery of silver from a photographic processing liquid, said device comprising a cylindrical electrolysis tank having at its bottom a liquid inlet and a liquid outlet as well as a hollow-cylindrical anode, which is arranged concentrically within said cylindrical tank, and an expendable cathode, which is formed into a hollow cylinder, rests against the inner surface of the tank wall and consists of a sheet carrier which is provided with an electrically conductive layer on the surface facing the anode, and also having electrical contacts for the cathode and the anode.
U.S. Pat. No. 4,028,212 discloses a silver recovery device which in one of its embodiments comprises a hollow cylindrical plastic electrolysis tank whose top is provided with an air vent. The cathode which is made of a strip of stainless steel is formed into a hollow cylinder. It is outwardly spring urged in the tank so as to rest against the inner surface of the tank wall. At the upper rim of the cathode, an angular portion is arranged which is electrically connected with the power supply via a screw screwed through the top. A hollow cylinder provided with a cover extends across a liquid inlet opening disposed in the center of the tank bottom. It serves as a carrier for a carbon anode which surrounds the hollow cylinder. In its wall, a number of jet tubes are uniformly distributed across the circumference of the wall surface and passed through the peripheral wall of the carbon anode. During electrolytic silver deposition the photographic processing liquid enters the hollow cylinder through the inlet opening and flows through the jet tubes into the space between the anode and the cathode which rests against the inner surface of the tank wall, before it flows out again through a discharge opening disposed in the tank bottom between anode and cathode.
Since the hollow cylinder, which is provided with jets and associated with the liquid inlet opening, also serves as a carrier for the anode, the complete assembly group including the anode has to be removed when a jet is clogged, for example. During such an operation the anode may be damaged. All jets have to be removed for cleaning. If an electrolytic silver deposition has been completed in this known silver recovery device the hollow-cylindrically shaped cathode can be removed from the open tank, bent open, scraped and used again. This operation is complicated, time-consuming and difficult because the bent-off contact tongue of the angular portion as well as the end of the screw which is connected with the electrical lead and contacts the contact tongue must be carefully cleaned. Moreover, much skill is required for seizing the cathode and removing it from the tank.
According to another embodiment of this known silver recovery device an expendable cathode is also provided which consists of a plastic strip in the form of a hollow cylinder which has an electrically conductive coating.
In order that this expandable plastic cathode can spring outwardly and fit as snugly into the inner surface of the tank wall as a hollow-cylindrical cathode consisting of a thin-walled resilient steel sheet it must be produced from a thicker, highly resilient and thus expensive plastic material. Since a fresh expendable plastic cathode must be used for each electrolytic silver deposition the use of such expendable cathodes is very expensive. Moreover it is difficult and complicated to seize the silvercoated expendable cathode and remove it from the tank.
If a thin plastic sheet carrying the electrically conductive layer were used instead of such an expendable cathode it would be no problem to mold such sheet into a hollow cylinder. However, the spring force by which it would be urged against the inner surface of the tank wall would be too low. During electrolytic silver deposition the sheet cathode resting against the inner surface of the tank wall might become indented and and be displaced so that perfect silver recovery would no longer be ensured. It might even
REFERENCES:
patent: 3959110 (1976-05-01), Burgess
patent: 3985634 (1976-10-01), Larson et al.
patent: 4028212 (1977-06-01), Bowen et al.
patent: 4069127 (1978-01-01), Salemi et al.
patent: 4149954 (1979-04-01), Ransbottom
patent: 4175026 (1979-11-01), Houseman
patent: 4269690 (1981-05-01), Graham, III
patent: 4440616 (1984-04-01), Houseman
Huttemeister Franz-Joseph
Uffinger Gerhard
Eastman Kodak Company
Legg L. George
Valentine Donald R.
LandOfFree
Silver recovery device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Silver recovery device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Silver recovery device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1523940