EP0035008A2 - Verfahren und Apparat zur Aufbereitung photographischer Lösungen - Google Patents

Verfahren und Apparat zur Aufbereitung photographischer Lösungen Download PDF

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Publication number
EP0035008A2
EP0035008A2 EP81870013A EP81870013A EP0035008A2 EP 0035008 A2 EP0035008 A2 EP 0035008A2 EP 81870013 A EP81870013 A EP 81870013A EP 81870013 A EP81870013 A EP 81870013A EP 0035008 A2 EP0035008 A2 EP 0035008A2
Authority
EP
European Patent Office
Prior art keywords
control electrode
cathode
potential
electrolysis
silver
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
EP81870013A
Other languages
English (en)
French (fr)
Other versions
EP0035008A3 (en
EP0035008B1 (de
Inventor
Pierre F. Vandenput
Philippe A. De Meester
Jean-Pierre J. Heraly
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Esterol AG
Original Assignee
Esterol AG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Family has litigation
First worldwide family litigation filed litigation Critical https://patents.darts-ip.com/?family=19729355&utm_source=google_patent&utm_medium=platform_link&utm_campaign=public_patent_search&patent=EP0035008(A2) "Global patent litigation dataset” by Darts-ip is licensed under a Creative Commons Attribution 4.0 International License.
Application filed by Esterol AG filed Critical Esterol AG
Priority to AT81870013T priority Critical patent/ATE11602T1/de
Publication of EP0035008A2 publication Critical patent/EP0035008A2/de
Publication of EP0035008A3 publication Critical patent/EP0035008A3/fr
Application granted granted Critical
Publication of EP0035008B1 publication Critical patent/EP0035008B1/de
Expired legal-status Critical Current

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C1/00—Electrolytic production, recovery or refining of metals by electrolysis of solutions
    • C25C1/20—Electrolytic production, recovery or refining of metals by electrolysis of solutions of noble metals
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25C—PROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/06—Operating or servicing
    • C—CHEMISTRY; METALLURGY
    • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
    • C25D21/00—Processes for servicing or operating cells for electrolytic coating
    • C25D21/12—Process control or regulation
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03C—PHOTOSENSITIVE MATERIALS FOR PHOTOGRAPHIC PURPOSES; PHOTOGRAPHIC PROCESSES, e.g. CINE, X-RAY, COLOUR, STEREO-PHOTOGRAPHIC PROCESSES; AUXILIARY PROCESSES IN PHOTOGRAPHY
    • G03C5/00—Photographic processes or agents therefor; Regeneration of such processing agents
    • G03C5/26—Processes using silver-salt-containing photosensitive materials or agents therefor
    • G03C5/395—Regeneration of photographic processing agents other than developers; Replenishers therefor
    • G03C5/3954—Electrical methods, e.g. electroytic silver recovery, electrodialysis
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03D—APPARATUS FOR PROCESSING EXPOSED PHOTOGRAPHIC MATERIALS; ACCESSORIES THEREFOR
    • G03D3/00—Liquid processing apparatus involving immersion; Washing apparatus involving immersion
    • G03D3/02—Details of liquid circulation
    • G03D3/06—Liquid supply; Liquid circulation outside tanks
    • G03D3/065—Liquid supply; Liquid circulation outside tanks replenishment or recovery apparatus

Definitions

  • the present invention relates to a method and an apparatus for the treatment of a photographic fixative bath, with a view to extracting the silver in the form of metallic silver by electrolysis in a bath comprising electrodes, it is ie at least one cathode and anodes.
  • a method and an apparatus are known in which a fixer bath is subjected to electrolysis in order to recover the silver in metallic form on at least one cathode.
  • the electric electrolysis current must have a sufficiently low intensity so that the sulfurization of the silver is avoided. Due to the fact that the electrolysis current must be low, the recovery of the silver is far from complete and it sometimes happens that more than 2 grams / liter of silver is lost in the fixing baths sent to the after their electrolysis. This obviously results in a significant loss of money economically.
  • the photographic fixer bath containing an excess of antioxidant agent is subjected to an electrolysis so as to ensure the deposition metallic silver on at least one cathode placed between two anodes in the electrolytic bath, subjected to turbulence, the pH being maintained at approximately 3.5 to 4.5 and the electrolysis current being subjected in this bath to regulation depending on its silver content, the intensity of the current being brought to decrease as the silver content of the bath decreases.
  • the electrolysed bath can be used again as a photographic fixative bath.
  • the potential difference to be applied to the electrodes during electrolysis must include at least the potential difference to overcome the ohmic resistance of the electrolysis cell, the concentration polarization due to the concentration gradients in the electrolyte and the overvoltage. inherent in the rate of reactions occurring at the electrodes.
  • the electrolysis rate is related to the electrolysis current and therefore to the potential difference applied to the electrodes. To perform electrolysis fairly quickly, while avoiding side reactions in the photographic fixative bath at low concentrations of silver, the electrolysis current is modified during the operation.
  • Apparatuses for treating baths of photographic fixatives are known in which the electric electrolysis current is adjusted during electrolysis, either as a function of the silver concentration of the bath of photographic fixer, or as a function of the resistivity of the cell. electrolysis, or again depending on the overvoltage at the cathode.
  • Known devices based on the measurement of the overvoltage at the cathode use a reference electrode connected by a bridge of silver nitrate placed in the vicinity of the cathode and make it possible to control the electrolysis up to very low silver concentrations.
  • This system implies the obligation to use a set of liquid junctions of different electrolytes, such as nitrate silver and, for example, mercury chloride, when using a calomel reference electrode.
  • the migration of different ions causes, during electrolysis, irreversible phenomena which modify the value of the overvoltage at the junctions of electrolytes.
  • the present invention aims to remedy the drawbacks described above by a method according to which the intensity of the electrolysis current is adjusted by measuring both the resistivity of the electrolysis cell and the overvoltage at the electrodes by the potential difference. between a control electrode immersed in the electrolytic bath and a cathode serving as a working electrode.
  • the electrolysis current is advantageously adjusted as a function of the potential difference between a control electrode, composed of pure carbon and immersed in the electrolytic bath, and a cathode serving as a working electrode, the voltage of the control electrode being maintained at a constant reference value.
  • the apparatus for treating a photographic fixer bath according to the invention which comprises, in order to extract the silver in metallic form, as electrodes, at least one cathode and anodes, as well as an electrode control, is essentially characterized in that the control electrode is composed of pure carbon and is immersed in the stirred electrolytic bath near said or of a cathode serving as working electrode, and in that it comprises a regulating device connected to the control electrode and said cathode and arranged for adjusting the electrolysis current as a function of the potential difference between said control electrode and said cathode.
  • the device for regulating the electrolysis current comprises a connected adder assembly. tee for adding the potential of the control electrode and a predetermined reference potential; a comparator / integrator assembly having an input connected to the output of the adder assembly and a second input connected to receive the potential of said cathode, said assembly being arranged to integrate the potential difference between said control electrode and the reference potential and for comparing the integrated value to the potential of the cathode so as to produce a control signal, and a current generator connected to supply the electrolysis current in response to said control signal from the comparator / integrator assembly.
  • the method and the apparatus according to the invention aim to extract the silver contained in a photographic fixer bath as the silver bath becomes saturated, with a view to prolonging the duration of use of this bath.
  • the apparatus for treating a photographic fixer bath according to the invention shown in FIG. 1, comprises, in a known manner, an electrolysis cell 1 mounted downstream of an enclosure (not shown) in which s fixes a photographic film and the overflow of which is sent via a pipe 2 into the electrolysis cell 1.
  • the electrolysis cell 1 contains at least one cathode 3 in the form of a plate, for example made of stainless steel, disposed between two anodes 4 constituted, for example, by high density and high purity graphite. Cathode 3 and anodes 4 are held in place and guided in the cell electrolysis 1 by known means (not shown).
  • a device for stirring the electrolyte which may be constituted by a dip tube 5 whose upper end is bent as shown in 6.
  • This dip tube whose lower end is perforated to allow the entry of electrolyte in the tube, is connected a pipe 7 supplying this tube 5 with compressed air from a source of compressed air, not shown.
  • the compressed air supplied to the lower part of the dip tube 5 is expelled in mixture with liquid fixative through the free end 6, creating permanent agitation or turbulence in the intervals between the cathode 3 and the anodes 4, so that that the silver ions in the electrolytic bath are brought close to the cathode (s) 3 in order to be fixed there.
  • a control electrode 8 immersed in the electrolytic bath. This electrode which has a determined potential with respect to the cathode, plays a role which will be explained later.
  • the cathode 3, the two anodes 4 and the control electrode 8 are connected by electrical conductors to a control device mounted in a housing (not shown) in which is also mounted the compressed air supply device.
  • the photographic fixative bath used in the process according to the invention is advantageously an aqueous solution containing approximately 100 to 200 g / l of ammonium or sodium thiosulfate and from 0 to 50 g / l of ammonium thiocyanate, as well as '' an excess of sodium sulfite up to a concentration of 60 g / 1.
  • This bath also contains a known tanning agent, at a starting concentration which can reach 15 g / liter, this concentration usually being between approximately 5 and 15 g / liter.
  • the pH of the photographic fixing bath is maintained at a value of approximately 3.5 to 4.5 by adding thereto, if necessary, a small amount of an acid, such as acetic acid.
  • the electrolysis cell 1 could contain a greater number of cathodes and anodes, the number of anodes always being one unit greater than the number cathodes.
  • the electrolysis current in the electrolysis cell 1 is regulated according to the silver content of the electrolytic bath so that the current decreases when the silver content of the electrolytic bath becomes less than a predetermined low value, for example 0.5-2 g / 1.
  • This regulation is ensured from the potential of the control electrode 8 by means of a regulation device 10 illustrated diagrammatically in FIG. 2.
  • This device is organized to maintain the potential Uec of the control electrode 8 at a predetermined set value and to compare this potential with the potential of the cathode 3 in order to adjust the electrolysis current.
  • the potential Uec of the control electrode 8 is applied by line 103 to a terminal 101 of the regulating device 10.
  • To a second terminal 102 is applied the predetermined reference or reference potential Uref.
  • the potentials Uec and Uref are of opposite polarities and are added by a circuit of resistors 11: the sum of these potentials is applied to a first input 104 of an operational amplifier 12.
  • a second input 105 of this amplifier receives the potential Uc from the cathode 3 via the line 106 through the resistor 13.
  • An integration capacitor 14 is connected in parallel with the amplifier 12.
  • the current on line 104 is zero and the voltage across the terminals of capacitor 14 is at a constant value.
  • the voltage on the output line 107 of the amplifier 12 controls a current generator 15 to generate a current which, after amplification in the amplifier 16, supplies the anodes 4 to supply the electrolysis current.
  • the reference potential Uref is chosen to be equal to the potential that the control electrode 8 would take for a concentration of the electrolytic bath of the order of 0.5 to 2 g / l with a zero electrolysis current.
  • the reference potential Uref is for example from 300 to 600 millivolts.
  • the control electrode 8 is advantageously polarized by a low current, of 1 mA for example, to protect this electrode against damage which would be caused at the surface.
  • a low current of 1 mA for example.
  • the control electrode 8 is protected by a sheath 9, for example made of foam, to avoid turbulence of the electrolytic bath in the immediate vicinity of this electrode, such turbulence possibly having the effect of causing an undesirable variation in the potential of this electrode.
EP81870013A 1980-02-21 1981-02-16 Verfahren und Apparat zur Aufbereitung photographischer Lösungen Expired EP0035008B1 (de)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AT81870013T ATE11602T1 (de) 1980-02-21 1981-02-16 Verfahren und apparat zur aufbereitung photographischer loesungen.

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
LU82188 1980-02-21
LU82188A LU82188A1 (fr) 1980-02-21 1980-02-21 Procede et appareil de traitement de bains de fixateurs photographiques

Publications (3)

Publication Number Publication Date
EP0035008A2 true EP0035008A2 (de) 1981-09-02
EP0035008A3 EP0035008A3 (en) 1982-06-09
EP0035008B1 EP0035008B1 (de) 1985-01-30

Family

ID=19729355

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81870013A Expired EP0035008B1 (de) 1980-02-21 1981-02-16 Verfahren und Apparat zur Aufbereitung photographischer Lösungen

Country Status (6)

Country Link
US (1) US4377456A (de)
EP (1) EP0035008B1 (de)
JP (1) JPS56138737A (de)
AT (1) ATE11602T1 (de)
DE (1) DE3168559D1 (de)
LU (1) LU82188A1 (de)

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2556374A1 (fr) * 1983-12-12 1985-06-14 Joliot Robert Dispositif pour maintenir a une valeur determinee la concentration en argent des bains de fixage dans les laboratoires cinematographiques ou photographiques
EP0201837A1 (de) * 1985-05-14 1986-11-20 Kodak-Pathe Verfahren Und Vorrichtung zum Regeln des Betriebspunktes einer Elektrolysezelle
EP0598144A1 (de) * 1992-11-10 1994-05-25 Agfa-Gevaert N.V. Verwendung einer pH-empfindlichen Referenz-Elektrode für die elektrolytische Entsilberung
EP0754780A1 (de) * 1995-07-15 1997-01-22 Agfa-Gevaert N.V. Verfahren und Vorrichtung zur Entsilberung von Lösungen
US5759377A (en) * 1995-07-15 1998-06-02 Agfa-Gevaert Process for de-silvering of a silver-containing solution

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4675085A (en) * 1985-07-31 1987-06-23 Adalberto Vasquez Method and apparatus for recovery of metal from solution
GB8927964D0 (en) * 1989-12-11 1990-02-14 Kodak Ltd Method and apparatus for recovering silver from a photographic fixing solution
US5770034A (en) * 1995-07-15 1998-06-23 Agfa-Gevaert N.V. Process and apparatus for desilvering a silver-containing solution
GB9726534D0 (en) * 1997-12-17 1998-02-11 Eastman Kodak Co Determination of silver in a photographic solution

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1866701A (en) * 1929-03-13 1932-07-12 Eastman Kodak Co Method and apparatus for recovering silver from fixing solutions
DE1187806B (de) * 1962-03-21 1965-02-25 Bayer Ag Verfahren und Vorrichtung zur Silberrueckgewinnung aus Fixierbaedern
US4065374A (en) * 1976-08-10 1977-12-27 New Nippon Electric Co., Ltd. Method and apparatus for plating under constant current density

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4186067A (en) * 1974-06-26 1980-01-29 Ciba-Geigy Aktiengesellschaft Electrolytic recovery of silver from photographic bleach-fix baths
US4287044A (en) * 1980-03-31 1981-09-01 Silver Systems, Ltd. Silver recovery apparatus

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1866701A (en) * 1929-03-13 1932-07-12 Eastman Kodak Co Method and apparatus for recovering silver from fixing solutions
DE1187806B (de) * 1962-03-21 1965-02-25 Bayer Ag Verfahren und Vorrichtung zur Silberrueckgewinnung aus Fixierbaedern
US4065374A (en) * 1976-08-10 1977-12-27 New Nippon Electric Co., Ltd. Method and apparatus for plating under constant current density

Cited By (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2556374A1 (fr) * 1983-12-12 1985-06-14 Joliot Robert Dispositif pour maintenir a une valeur determinee la concentration en argent des bains de fixage dans les laboratoires cinematographiques ou photographiques
EP0201837A1 (de) * 1985-05-14 1986-11-20 Kodak-Pathe Verfahren Und Vorrichtung zum Regeln des Betriebspunktes einer Elektrolysezelle
FR2582022A1 (fr) * 1985-05-14 1986-11-21 Kodak Pathe Procede et dispositif de regulation de la position du point de fonctionnement d'une cellule d'electrolyse
EP0598144A1 (de) * 1992-11-10 1994-05-25 Agfa-Gevaert N.V. Verwendung einer pH-empfindlichen Referenz-Elektrode für die elektrolytische Entsilberung
EP0754780A1 (de) * 1995-07-15 1997-01-22 Agfa-Gevaert N.V. Verfahren und Vorrichtung zur Entsilberung von Lösungen
US5759377A (en) * 1995-07-15 1998-06-02 Agfa-Gevaert Process for de-silvering of a silver-containing solution

Also Published As

Publication number Publication date
ATE11602T1 (de) 1985-02-15
US4377456A (en) 1983-03-22
LU82188A1 (fr) 1981-09-10
EP0035008A3 (en) 1982-06-09
DE3168559D1 (en) 1985-03-14
EP0035008B1 (de) 1985-01-30
JPS56138737A (en) 1981-10-29

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