CA1129376A - Electrodes for electrolytic recovery of metals - Google Patents
Electrodes for electrolytic recovery of metalsInfo
- Publication number
- CA1129376A CA1129376A CA346,929A CA346929A CA1129376A CA 1129376 A CA1129376 A CA 1129376A CA 346929 A CA346929 A CA 346929A CA 1129376 A CA1129376 A CA 1129376A
- Authority
- CA
- Canada
- Prior art keywords
- electrode
- electrodes
- substrate
- solution
- 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.)
- Expired
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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
- C25C7/00—Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
- C25C7/02—Electrodes; Connections thereof
-
- 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
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- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Electrolytic Production Of Metals (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
The specification describes an electrode assembly for use in the recovery of silver from a solution. The as-sembly comprises a first electrode having an electrically conductive substrate which passivates only where contacted by the solution and having a carbon graphite coating formed on the substrate, and a second electrode formed from a material which is non-sacrificing in the solution. The assembly also includes means for supporting the first and second electrodes in an opposing and spaced relation to permit the flow of the solution between the opposing surfaces thereof, and means for coupling a source of potential between the electrodes so that the first electrode is at a greater potential than the second.
The specification describes an electrode assembly for use in the recovery of silver from a solution. The as-sembly comprises a first electrode having an electrically conductive substrate which passivates only where contacted by the solution and having a carbon graphite coating formed on the substrate, and a second electrode formed from a material which is non-sacrificing in the solution. The assembly also includes means for supporting the first and second electrodes in an opposing and spaced relation to permit the flow of the solution between the opposing surfaces thereof, and means for coupling a source of potential between the electrodes so that the first electrode is at a greater potential than the second.
Description
-BACKGROIJND OF TllE INVENTION
I FIEID OF THE INVENTION
This invention relates generally to electrolytic recovery of ~letals and, more particularly, to the electrodes utilized to recover metal from a solution containing ions of the metal.
While attention will hereinafter be focused on silver recovery in a photographic film development process, it should be understood that electrodes constructed in accordance with the invention may be advantageously employed in the recovery of other metals within other processes.
I FIEID OF THE INVENTION
This invention relates generally to electrolytic recovery of ~letals and, more particularly, to the electrodes utilized to recover metal from a solution containing ions of the metal.
While attention will hereinafter be focused on silver recovery in a photographic film development process, it should be understood that electrodes constructed in accordance with the invention may be advantageously employed in the recovery of other metals within other processes.
2. DESCRIPTION OF THE PRIOR ART
The electrolytic recovery of metals is well known in the art.
Such recovery involves immersing a pair of electrodes in metal-bearing electrolytic solution and impressing a voltage across the electrodes which is of sufficient magnitude to effect migration of the metal ions to the cathode so that a deposition of the metal on the cathode surface, in the form of a coherent plating which is sub-sequently removed, results.
Electrolytic cells capable of accomplishing the desired recovery of metal have been developed in diverse forms embodying a variety of principles of operation and corresponding structural variations.
It is generally desirable to maximize the size of the electrodes to maximize the rate at which metal ions are plated onto the cathode.
The electrode size, however, is generally limited by the resistivity of the electrode material and available power. An additional size limitation, in the case of photographic silver recovery and other processes, has been the expense or the frangibility of the most commonly used electrode materials, carbon graphite, stainless steel, ; and platinized titanium, which have been preferable from an electro-chemical view owing to their non-sacrificing quality within the solution.
.~
U.S. Patent 3,458,425, for example, discloses an electrolytic apparatus whicl- uses a pair of carbon graphite rod anodes. Although possessing the relatively high resistivity of 1375 microhm-cm. graphite does not passivate in electrolytic solutions such as the developer solutions in automatic film processing.
U.S. Patent 3,551,317 discloses a thin flexible sheet cathode formed from stainless steel or brass, and a cylindrical anode formed from stainless steel or graphite. It will be appreciated that stain-less steel, like gxaphite, is non-passivating in the electrolytic solution.
U.S. Patent 3,560,366 discloses a tubular cathode formed from stainless steel and a plurality of anodes disposed about the outer ~ periphery of the cathode.
.:
` U.S. Patent 3,702,814 discloses a generally cylindrical stain-~ess steel cathode and a carbon rod anode.
U.S. Patent 3,751,351 discloses a single cathode in the form of a flat metal plate and two metal anodes in the form of flat metal ; plates which are parallel to and spaced from the cathode. All elec-trodes are formed of stainless steel, carbon or platinized titanium.
SUMMMY OE T~E INVENTION
An electrode construction is provided herein, wherein the electrode is adapted, but not limited, for use an an anode in electrolytic recovery of metal. Basically, the electrode comprises an electrically conductive substrate which surficially passivates in response to contact with the metal-bearing solution, means for coupling a power ; source to the substrate and a non-sacrificing carbon graphite coating formed on the substrate. The substrate acts as the primary current path permitting a relatively uniform current density throughout the ; electrode structure. Because the current need flow only through a , a coating of carbon graphite, the current path through the relatively _2-higller resistivity associated with the graphite is limited to the thi(kness of the coating.
Additionally, the surficial passivation of the substrate upon contact with the metal-bearing solution provides a "bandage" chara-cteristic to the electrode.
As used throughout this disclosure, the term "surficially passivating" shall be used to denote the passivation of the substrate material at the solution-contacting surface. The surficial passivation prevents the substrate from being sacrificed.
Further details concerning the present invention will be apparent from the following detailed description of the preferred embodiment, of which the following figures form a part.
BRIEF DESCRIPTION OF THE DRAWING
Figure 1 is a perspective view of an electrode pair constructed in accordance with the present invention.
Figure 2 is a schematic representation of a power supply for the electrodes and constructed in accordance with the present invention.
Figure 3 is a cross_section view of a second electrode pair constructed in accordance with the present invention.
, -3-112~376 DETAIIED ~ESCRIPTION OF THE PREFERRED EMBODIMENT
Initial reference is made to Figure 1 w}-~ich shows a perspective view of an elec~rode pair constructed in accordance with the present invelltion and intended for use in the fixer solution bath of an automatic photoyraphic film processing system. Silver from the processed film enters into solution and, unless recovered, repre-sents an economic loss and degrades the performance of the fixer.
In silver recovery, the anode size has heretofore been constrained owing to the fragility of carbon and the cost of the two preferable anode materials, carbon and platinum. Carbon and platinum have been used because they do not passivate in the fixer solution. It should be mentioned that stainless steel, another commonly used anode materiaL, completely passivates during the electrolytic process and is, therefore, not as desirable.
As shown in Figure 1, the electrode pair includes an anode 10 which is formed from a titanium substrate; titanium provides a low resistance electrical path, being characterized by a resistivity of 42 microhm-cm. At least one surface lOa of the substrate is coated with a conductive graphite coating approximately 200 micxons (8 mils~
thick. The preferred coating is manufactured by Acheson Colloids, Ine., Port Huron, Michigan. While the formula of the coa~ing is deemcd proprietary by that company, it is available as Electrodag 158. An electrical lead 14 is welded to the substrate and provides connection to a power source.
The cathode l6 is preferably formed from a sheet of stainless steel, but may also be silver or other suitable material. The cathode 16 is held in a spaced relation from the anode 10 by means of a plur-ality of spacers 18. The spacers 18 are preferably snap-in polypro-pylene members, but may also be formed from any electrically non-conductive material compatible with the electrolytic solution.
It will be appreciated that the use of a highly conductive substrate and non-sacrificing overcoating results in lower power llZ9376 requirements for an electrode than that required by an electrode formed only from the non-sacrificing, but less conductive, material.
Acc:ordingly, larger anode structures of uniform utilization are possible for use with commonly available power sources.
~ l inherent feature of the anode 10 relates to a "self-healing"
property resulting from the passivation of titanium when it is contacted by the fixer solution of a photographic film process. Specifically, an oxide of the titanium is formed by such contact, and the oxide is dialectric; for that reason, the exposed area does not conduct electrons into the solution from portions of substrate which are adjacent to the exposed region. Consequently, the unintentional removal of a portion of the non-sacrificing graphite coating 12 will result in the formation of a surficial layer of titanium oxide which prevents further passi-vation of the substrate interior or of adjacent portions of the sub-strate underlying the coating 12. This feature is particularly important owing to the presence of "pinhole" gaps in the carbon coating which are found from time to time. The presence of these "pinholes" is not understood, but they are commonly found. The use of a passivating substrate prevents a noticable degradation in the anode 10 performance.
As known in the art, it is desirable to provide a coulombic output from the cathode in accordance with the amount of silver in solution.
If the coulombic output is too high, constituents of the fixer solution are converted to sulfides degrading both the fixer and the electrode performance. Naturally, too small of a coulombic output will result in an insufficient rate of recovery of silver. As shown in Figure 1, the present invention includes a coulombic adjustment device which couples the power leads 14 from the electrode to line voltage. The adjustment device 20 is seen, in Figure 1, to comprise a module con-. .
taining a pair of prongs 22 compatible with wall-mounted power outlets and a numerical scale from 1 to 10 circumferentially disposed about a rotatable knob 24.
.~ _5-1~29376 The module serves as a housing for circuitry illustrated in Figure ' as comprising a step-down txansformer 30, and AC-DC converter 32 coupled a(ross the secondary of the transformer 30, and a variable resistor 34 couplecl across the output of the rectifier 32. As may be appreciated, tlle wiper member 36 of the variable resistor 34 is coupled to the lead l4 for connection to the cathode 16. It will also be appreciated that the rotation of the knob 24 (Figure 1) results in the movement of the wiper member 36 to vary the voltage applied to the cathode 16.
The proper setting for the knob 24, with respect to the circum-ferential scale, has been empirically determined in accordance with the approximate quantity of silver known to enter the fixer solution for each square inch of processed film- Accordingly, a table has t~een empirically derived which relates the proper scale setting with two parameters which are easily determined by the user of the silver-recovery system: film size and film quantity. This table is reproduced as TABL~ I below.
.~
' ;' ' .
~'~
':
.
~129376 TABLE I
~ILM SIZE
Y. PER WEEK lOx12 8xlO 6x12 5x12 DENTAL
O O O O O O
2 .28 .19 .17 .14 .01 4 .56 .37 .33 .28 .02 6 .83 .56 .50 .42 .03 8 1.11 .74 .67 .56 .04 1.39 .93 .83 .69 .05 12 1.67 1.11 1.00 .83 .06 1~ 1.94 1.30 1.17 .97 .07 16 2.22 1.48 1.33 1.11 .08 18 2.50 1.67 1.50 1.25 .09 2.78 1.85 1.67 1.39 .10 ; 22 3.06 2.04 1.83 1.53 .11 i 24 3.33 2.22 2.00 1.67 .13 ~I
26 3.61 2.41 2.17 1.81 .14 28 3.89 2.59 2.33 1.94 .15 4.17 2.78 2.50 2.08 .16 4.86 3.24 2.92 2.43 .18 ' 40 5.56 3.70 3.33 2.78 .21 `; 45 6.25 4.17 3.75 3.12 .23 ' 50 6.95 4.63 4.17 3.47 .26 I 75 -- 6.94 6.25 5.21 .39 `, 100 -- 9.26 8.33 6.94 .52 200 - - - - - - - - 1.04 - - - - 1.56 400 __ __ __ __ 2.08 , ', ,. ~
llZ9376 An inherent advantage to the embodiment described in ~igure 1 is that the electrode pair may be placed within the fixer tank of an automatic film processor, thereby eliminating the need for "add-on"
units known in the art.
Figure 3 is a cross-sectional view of a second electrode pair constructed in accordance with the present invention. A first generally tubular member 110 is provided having an inner surface 112 formed from a cathode material such as stainless steel. While the member 110 could, itself, be a stainless steel member, an alternative provides a cylinder of easily formed material, such as PVC, which is inert in the electro-lyte solution and a thin, flexible sheet of the cathode material which may be wound into a cylinder of slightly smaller diameter than the PVC for insertion therein and subsequently permitted to expand, whereby the PVC cylinder would function as a mandril.
A second tubular member 114 is sized to fit in a generally coaxial manner within the first tubular member 110. The second tubular member 114 is formed from an electrically conductive substrate which passivates in response to contact with the electrolytic solution and which is coated about its outer surface 116 with a carbon graphite composition in accor-dance with the foregoing description. A motor 118 may conveniently be mounted within the tubular member 114 and serves to operate a pump whereby the electrolytic fluid flows between the outer surface of the inner tubular member 114 and inner surface of the outer tubular member 110.
Whi]e the foregoing description has been of a preferred embodi-ment of the present invention, it will be recognized that many vari-ations and modifications are apparent to those skilled in the art.
It is accordingly intended that the invention be defined only by the appended claims which are to be interpreted as broadly as permissible in light of the prior art.
I CLAIM:
The electrolytic recovery of metals is well known in the art.
Such recovery involves immersing a pair of electrodes in metal-bearing electrolytic solution and impressing a voltage across the electrodes which is of sufficient magnitude to effect migration of the metal ions to the cathode so that a deposition of the metal on the cathode surface, in the form of a coherent plating which is sub-sequently removed, results.
Electrolytic cells capable of accomplishing the desired recovery of metal have been developed in diverse forms embodying a variety of principles of operation and corresponding structural variations.
It is generally desirable to maximize the size of the electrodes to maximize the rate at which metal ions are plated onto the cathode.
The electrode size, however, is generally limited by the resistivity of the electrode material and available power. An additional size limitation, in the case of photographic silver recovery and other processes, has been the expense or the frangibility of the most commonly used electrode materials, carbon graphite, stainless steel, ; and platinized titanium, which have been preferable from an electro-chemical view owing to their non-sacrificing quality within the solution.
.~
U.S. Patent 3,458,425, for example, discloses an electrolytic apparatus whicl- uses a pair of carbon graphite rod anodes. Although possessing the relatively high resistivity of 1375 microhm-cm. graphite does not passivate in electrolytic solutions such as the developer solutions in automatic film processing.
U.S. Patent 3,551,317 discloses a thin flexible sheet cathode formed from stainless steel or brass, and a cylindrical anode formed from stainless steel or graphite. It will be appreciated that stain-less steel, like gxaphite, is non-passivating in the electrolytic solution.
U.S. Patent 3,560,366 discloses a tubular cathode formed from stainless steel and a plurality of anodes disposed about the outer ~ periphery of the cathode.
.:
` U.S. Patent 3,702,814 discloses a generally cylindrical stain-~ess steel cathode and a carbon rod anode.
U.S. Patent 3,751,351 discloses a single cathode in the form of a flat metal plate and two metal anodes in the form of flat metal ; plates which are parallel to and spaced from the cathode. All elec-trodes are formed of stainless steel, carbon or platinized titanium.
SUMMMY OE T~E INVENTION
An electrode construction is provided herein, wherein the electrode is adapted, but not limited, for use an an anode in electrolytic recovery of metal. Basically, the electrode comprises an electrically conductive substrate which surficially passivates in response to contact with the metal-bearing solution, means for coupling a power ; source to the substrate and a non-sacrificing carbon graphite coating formed on the substrate. The substrate acts as the primary current path permitting a relatively uniform current density throughout the ; electrode structure. Because the current need flow only through a , a coating of carbon graphite, the current path through the relatively _2-higller resistivity associated with the graphite is limited to the thi(kness of the coating.
Additionally, the surficial passivation of the substrate upon contact with the metal-bearing solution provides a "bandage" chara-cteristic to the electrode.
As used throughout this disclosure, the term "surficially passivating" shall be used to denote the passivation of the substrate material at the solution-contacting surface. The surficial passivation prevents the substrate from being sacrificed.
Further details concerning the present invention will be apparent from the following detailed description of the preferred embodiment, of which the following figures form a part.
BRIEF DESCRIPTION OF THE DRAWING
Figure 1 is a perspective view of an electrode pair constructed in accordance with the present invention.
Figure 2 is a schematic representation of a power supply for the electrodes and constructed in accordance with the present invention.
Figure 3 is a cross_section view of a second electrode pair constructed in accordance with the present invention.
, -3-112~376 DETAIIED ~ESCRIPTION OF THE PREFERRED EMBODIMENT
Initial reference is made to Figure 1 w}-~ich shows a perspective view of an elec~rode pair constructed in accordance with the present invelltion and intended for use in the fixer solution bath of an automatic photoyraphic film processing system. Silver from the processed film enters into solution and, unless recovered, repre-sents an economic loss and degrades the performance of the fixer.
In silver recovery, the anode size has heretofore been constrained owing to the fragility of carbon and the cost of the two preferable anode materials, carbon and platinum. Carbon and platinum have been used because they do not passivate in the fixer solution. It should be mentioned that stainless steel, another commonly used anode materiaL, completely passivates during the electrolytic process and is, therefore, not as desirable.
As shown in Figure 1, the electrode pair includes an anode 10 which is formed from a titanium substrate; titanium provides a low resistance electrical path, being characterized by a resistivity of 42 microhm-cm. At least one surface lOa of the substrate is coated with a conductive graphite coating approximately 200 micxons (8 mils~
thick. The preferred coating is manufactured by Acheson Colloids, Ine., Port Huron, Michigan. While the formula of the coa~ing is deemcd proprietary by that company, it is available as Electrodag 158. An electrical lead 14 is welded to the substrate and provides connection to a power source.
The cathode l6 is preferably formed from a sheet of stainless steel, but may also be silver or other suitable material. The cathode 16 is held in a spaced relation from the anode 10 by means of a plur-ality of spacers 18. The spacers 18 are preferably snap-in polypro-pylene members, but may also be formed from any electrically non-conductive material compatible with the electrolytic solution.
It will be appreciated that the use of a highly conductive substrate and non-sacrificing overcoating results in lower power llZ9376 requirements for an electrode than that required by an electrode formed only from the non-sacrificing, but less conductive, material.
Acc:ordingly, larger anode structures of uniform utilization are possible for use with commonly available power sources.
~ l inherent feature of the anode 10 relates to a "self-healing"
property resulting from the passivation of titanium when it is contacted by the fixer solution of a photographic film process. Specifically, an oxide of the titanium is formed by such contact, and the oxide is dialectric; for that reason, the exposed area does not conduct electrons into the solution from portions of substrate which are adjacent to the exposed region. Consequently, the unintentional removal of a portion of the non-sacrificing graphite coating 12 will result in the formation of a surficial layer of titanium oxide which prevents further passi-vation of the substrate interior or of adjacent portions of the sub-strate underlying the coating 12. This feature is particularly important owing to the presence of "pinhole" gaps in the carbon coating which are found from time to time. The presence of these "pinholes" is not understood, but they are commonly found. The use of a passivating substrate prevents a noticable degradation in the anode 10 performance.
As known in the art, it is desirable to provide a coulombic output from the cathode in accordance with the amount of silver in solution.
If the coulombic output is too high, constituents of the fixer solution are converted to sulfides degrading both the fixer and the electrode performance. Naturally, too small of a coulombic output will result in an insufficient rate of recovery of silver. As shown in Figure 1, the present invention includes a coulombic adjustment device which couples the power leads 14 from the electrode to line voltage. The adjustment device 20 is seen, in Figure 1, to comprise a module con-. .
taining a pair of prongs 22 compatible with wall-mounted power outlets and a numerical scale from 1 to 10 circumferentially disposed about a rotatable knob 24.
.~ _5-1~29376 The module serves as a housing for circuitry illustrated in Figure ' as comprising a step-down txansformer 30, and AC-DC converter 32 coupled a(ross the secondary of the transformer 30, and a variable resistor 34 couplecl across the output of the rectifier 32. As may be appreciated, tlle wiper member 36 of the variable resistor 34 is coupled to the lead l4 for connection to the cathode 16. It will also be appreciated that the rotation of the knob 24 (Figure 1) results in the movement of the wiper member 36 to vary the voltage applied to the cathode 16.
The proper setting for the knob 24, with respect to the circum-ferential scale, has been empirically determined in accordance with the approximate quantity of silver known to enter the fixer solution for each square inch of processed film- Accordingly, a table has t~een empirically derived which relates the proper scale setting with two parameters which are easily determined by the user of the silver-recovery system: film size and film quantity. This table is reproduced as TABL~ I below.
.~
' ;' ' .
~'~
':
.
~129376 TABLE I
~ILM SIZE
Y. PER WEEK lOx12 8xlO 6x12 5x12 DENTAL
O O O O O O
2 .28 .19 .17 .14 .01 4 .56 .37 .33 .28 .02 6 .83 .56 .50 .42 .03 8 1.11 .74 .67 .56 .04 1.39 .93 .83 .69 .05 12 1.67 1.11 1.00 .83 .06 1~ 1.94 1.30 1.17 .97 .07 16 2.22 1.48 1.33 1.11 .08 18 2.50 1.67 1.50 1.25 .09 2.78 1.85 1.67 1.39 .10 ; 22 3.06 2.04 1.83 1.53 .11 i 24 3.33 2.22 2.00 1.67 .13 ~I
26 3.61 2.41 2.17 1.81 .14 28 3.89 2.59 2.33 1.94 .15 4.17 2.78 2.50 2.08 .16 4.86 3.24 2.92 2.43 .18 ' 40 5.56 3.70 3.33 2.78 .21 `; 45 6.25 4.17 3.75 3.12 .23 ' 50 6.95 4.63 4.17 3.47 .26 I 75 -- 6.94 6.25 5.21 .39 `, 100 -- 9.26 8.33 6.94 .52 200 - - - - - - - - 1.04 - - - - 1.56 400 __ __ __ __ 2.08 , ', ,. ~
llZ9376 An inherent advantage to the embodiment described in ~igure 1 is that the electrode pair may be placed within the fixer tank of an automatic film processor, thereby eliminating the need for "add-on"
units known in the art.
Figure 3 is a cross-sectional view of a second electrode pair constructed in accordance with the present invention. A first generally tubular member 110 is provided having an inner surface 112 formed from a cathode material such as stainless steel. While the member 110 could, itself, be a stainless steel member, an alternative provides a cylinder of easily formed material, such as PVC, which is inert in the electro-lyte solution and a thin, flexible sheet of the cathode material which may be wound into a cylinder of slightly smaller diameter than the PVC for insertion therein and subsequently permitted to expand, whereby the PVC cylinder would function as a mandril.
A second tubular member 114 is sized to fit in a generally coaxial manner within the first tubular member 110. The second tubular member 114 is formed from an electrically conductive substrate which passivates in response to contact with the electrolytic solution and which is coated about its outer surface 116 with a carbon graphite composition in accor-dance with the foregoing description. A motor 118 may conveniently be mounted within the tubular member 114 and serves to operate a pump whereby the electrolytic fluid flows between the outer surface of the inner tubular member 114 and inner surface of the outer tubular member 110.
Whi]e the foregoing description has been of a preferred embodi-ment of the present invention, it will be recognized that many vari-ations and modifications are apparent to those skilled in the art.
It is accordingly intended that the invention be defined only by the appended claims which are to be interpreted as broadly as permissible in light of the prior art.
I CLAIM:
Claims (15)
1. In a silver recovery system, an electrode comprising:
an electrically conductive substrate which passivates where in contact with the silver-bearing solution;
means for coupling a power source to the substrate; and a carbon graphite coating formed on the substrate.
an electrically conductive substrate which passivates where in contact with the silver-bearing solution;
means for coupling a power source to the substrate; and a carbon graphite coating formed on the substrate.
2. The electrode of Claim 1 wherein the substrate is formed from titanium.
3. The electrode of Claim 2 wherein the coating is approximately 200 microns thick.
4. An electrode assembly for use in the recovery of silver from a solution and comprising:
a first electrode having an electrically conductive sub-strate which passivates only where contacted by the solution and having a carbon graphite coating formed on the substrate;
a second electrode formed from a material which is non-sacrificing in the solution;
means for supporting the first and second electrodes in an opposing and spaced relation to permit the flow of the solution between the opposing surfaces thereof; and means for coupling a source of potential voltage between the electrodes so that the first electrode is at a greater potential than the second.
a first electrode having an electrically conductive sub-strate which passivates only where contacted by the solution and having a carbon graphite coating formed on the substrate;
a second electrode formed from a material which is non-sacrificing in the solution;
means for supporting the first and second electrodes in an opposing and spaced relation to permit the flow of the solution between the opposing surfaces thereof; and means for coupling a source of potential voltage between the electrodes so that the first electrode is at a greater potential than the second.
5. The assembly of Claim 4 wherein the substrate is titanium.
6. The assembly of Claim 5 wherein the second electrode is formed from stainless steel.
7. The assembly of Claim 4 wherein the electrodes are generally planar.
8. The assembly of Claim 7 wherein the electrodes respectively have a plurality of through-holes and further including;
a plurality of spacer members adapted to support the electrodes in a spaced relation, the spacer member being respectively coupled to the electrodes via mutually aligned through-holes.
a plurality of spacer members adapted to support the electrodes in a spaced relation, the spacer member being respectively coupled to the electrodes via mutually aligned through-holes.
9. The assembly of Claim 4 including a pair of coaxial tubular members relatively sized and positioned to define a fluid-conducting path between the outer surface of one member and the inner surface of the other member, the electrodes being respectively formed on said inner and outer surfaces.
10. A silver recovery apparatus comprising:
a first generally tubular member having as its inner surface a first electrode;
a second generally tubular member having as its outer surface a second electrode and sized to fit generally coaxially within the first member, the members being relatively sized to define a fluid conducting path between the opposing electrodes, one of the electrodes being an anode formed from an electrically conductive substrate and a coating which is non-sacrificing in a silver solution electrolyte, the other electrode being a cathode formed from an electrically conductive material, means for impressing a voltage between the two electrodic surfaces; and pump means for conducting the silver solution electrolyte through the defined path and a motor adapted for coupling to a source of power for operating the pump means, at least one of the voltage impressing means and motor being mounted within the second tubular member.
a first generally tubular member having as its inner surface a first electrode;
a second generally tubular member having as its outer surface a second electrode and sized to fit generally coaxially within the first member, the members being relatively sized to define a fluid conducting path between the opposing electrodes, one of the electrodes being an anode formed from an electrically conductive substrate and a coating which is non-sacrificing in a silver solution electrolyte, the other electrode being a cathode formed from an electrically conductive material, means for impressing a voltage between the two electrodic surfaces; and pump means for conducting the silver solution electrolyte through the defined path and a motor adapted for coupling to a source of power for operating the pump means, at least one of the voltage impressing means and motor being mounted within the second tubular member.
11. The apparatus of Claim 10 wherein the anode substrate is selected from the group consisting of stainless steel and titanium.
12. The apparatus of Claim 11 wherein the anode coating is graphite.
13. The apparatus of Claim 10 wherein the cathode is stainless steel.
14. The apparatus of Claim 10 wherein at least one of the tubular members is formed from molded plastic and includes a coating of the electrode material on its path-defining surface.
15. The apparatus of Claim 10 wherein the pump means includes a motor mounted within the second tubular member.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US1740479A | 1979-03-05 | 1979-03-05 | |
| US17,404 | 1979-03-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1129376A true CA1129376A (en) | 1982-08-10 |
Family
ID=21782401
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA346,929A Expired CA1129376A (en) | 1979-03-05 | 1980-03-04 | Electrodes for electrolytic recovery of metals |
Country Status (6)
| Country | Link |
|---|---|
| JP (1) | JPS55161087A (en) |
| CA (1) | CA1129376A (en) |
| DE (1) | DE3007775A1 (en) |
| FR (1) | FR2450881A1 (en) |
| GB (1) | GB2046306A (en) |
| NL (1) | NL8001306A (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9394584B2 (en) | 2013-12-03 | 2016-07-19 | Tetra Recycling, Inc. | Method of recovering silver and paper from silver-coated paper film |
-
1980
- 1980-02-29 DE DE19803007775 patent/DE3007775A1/en not_active Withdrawn
- 1980-03-04 CA CA346,929A patent/CA1129376A/en not_active Expired
- 1980-03-04 NL NL8001306A patent/NL8001306A/en not_active Application Discontinuation
- 1980-03-05 FR FR8004880A patent/FR2450881A1/en not_active Withdrawn
- 1980-03-05 JP JP2680980A patent/JPS55161087A/en active Pending
- 1980-03-05 GB GB8007569A patent/GB2046306A/en not_active Withdrawn
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9394584B2 (en) | 2013-12-03 | 2016-07-19 | Tetra Recycling, Inc. | Method of recovering silver and paper from silver-coated paper film |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS55161087A (en) | 1980-12-15 |
| FR2450881A1 (en) | 1980-10-03 |
| DE3007775A1 (en) | 1980-09-18 |
| GB2046306A (en) | 1980-11-12 |
| NL8001306A (en) | 1980-09-09 |
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