CA2097869A1 - Process for electrolytically detoxifying or regenerating an aqueous solution containing cyanide and an apparatus for carrying out the process - Google Patents
Process for electrolytically detoxifying or regenerating an aqueous solution containing cyanide and an apparatus for carrying out the processInfo
- Publication number
- CA2097869A1 CA2097869A1 CA 2097869 CA2097869A CA2097869A1 CA 2097869 A1 CA2097869 A1 CA 2097869A1 CA 2097869 CA2097869 CA 2097869 CA 2097869 A CA2097869 A CA 2097869A CA 2097869 A1 CA2097869 A1 CA 2097869A1
- Authority
- CA
- Canada
- Prior art keywords
- cyanide
- metal
- solution
- copper
- cathode
- 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.)
- Abandoned
Links
Classifications
-
- 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
- C25D21/16—Regeneration of process solutions
- C25D21/20—Regeneration of process solutions of rinse-solutions
Landscapes
- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
- Electrodes For Compound Or Non-Metal Manufacture (AREA)
- Electrolytic Production Of Metals (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
In order to electrolytically detoxify or regenerate an aqueous solution containing cyanide, the cyanide is converted by means of anodic oxidation into carbon dioxide and/or nitrogen and/or ammonia, and at the same time the metallic portion of the cyanide compound is cathodically deposited; to improve the efficiency of the cyanide oxidation process, a metal and/or metal ions having cathodic potential are introduced into the solution. A dimensionally stable titanium-based electrode is used as the anode and it is electrocatalytically coated with oxides of platinum group metals and/or titanium, as well as with platinum metals; the cathode used is an expanded metal electrode made of copper-plated or silver-plated titanium.
In order to electrolytically detoxify or regenerate an aqueous solution containing cyanide, the cyanide is converted by means of anodic oxidation into carbon dioxide and/or nitrogen and/or ammonia, and at the same time the metallic portion of the cyanide compound is cathodically deposited; to improve the efficiency of the cyanide oxidation process, a metal and/or metal ions having cathodic potential are introduced into the solution. A dimensionally stable titanium-based electrode is used as the anode and it is electrocatalytically coated with oxides of platinum group metals and/or titanium, as well as with platinum metals; the cathode used is an expanded metal electrode made of copper-plated or silver-plated titanium.
Description
9 ~
A Process for Electrolytically Detoxifying or - Regenerating an Aqueous Solution Containing Cyanide and an Apparatus for Carrying out the Process The invention relates to a process for electrolytically detoxifying or regenerating 5 an aqueous solution containing cyanide, wherein cyanide is converted by means of anodic oxidation into carbon dioxide and/or nitrogen and/or ammonia, also an apparatus for carrying out the process.
German Patent Application DE-OS 26 00 084 describes the electrochemical treatment of dilute metal cyanide solutions such as occur, for example, in the 10 forrn of washing solutions in electroplating installations; in the described process, cyanide is anodically oxidized while rnetal is simultaneously cathodically deposited. The anode and cathoda are designed as reticulate structures or wire-mesh baskets, and both electrodss may be made from platinum-coated titanium; however, it is also possible to uss a copper cathode.
15 In accordance with one embodiment of the invention, the solution to be treated contains, in addition to copper cyanide, also sodium cyanide and sodium carbonate as well as Rochelle salt.
When carrying out electrohJtic oxidation in low concentration ranges, the unsatisfactory current efficiency proves to be a problem so that, in view of the20 customarily strictwaste discharge conditions (environmental restrictions~
imposed by the authorities, it is essential to use an additional process for detoxifying low cyanide concentrations. Furthermore, high rates of srosion (=
short seMce iives) occur at the platinum coated titanium electrodes, so that in practice the process for the electrochemical oxidation of cyanide is not very 25 economical because of the high resulting costs (anode costs~.
Furthermore, German Patent DE PS 28 36 720 describes a procsss for the continuous electrolytic regeneration of a washing solution containing silver cyanide, such as occurs during electroplating processes, wherein the , , .; .: - . ~
'~ `
`' ~ `' ` ' ;
- r~ 2 ~ 9 f~, !
concentration of cyanide is greatly reduced by anodic oxidation to ammonia, and at the same time the silver is deposited in spongy form on the cathode, from which it is periodically stripped and collected in a funnel arranged in thebottom of the regeneration cell and then filtered off. In accordance with one 5 embodiment of the invention, the anode possesses a coating of titanium and platlnum while the cathode is plated with purs silver, so that here again the problem of high erosion rates of platinum-coated titanium electrodes is encountsr~d, thereby resulting in high attendant costs in practice.
It is an object of the invention to propose a means by which the large volumes 10 of cyanidic waste water accumulating, in particular, in electroplating operations may be elactrochemically treated in a cost-effective manner, with high current efficiencies beirlg achieved even at low concentrations, thus rendering further detoxification processs superfluous; furthermore, the purpose is also to ~.
propose an apparatus for the electrolytic detoxification or regeneration of an 15 aqueous solution containing cyanide; and an additional goal is to increase the Iifetime of the anodes.
In general terms, ths invention provides a process for electrolytically detoxifying or regenerating an aqueous solution containing cyanide, wherein cyanide is converted by means of anodic oxidation into carbon dioxide and/or nitrogen 20 and/or ammonia, characterized in that in order to improve the efficiency of the cyanid~ conversion process a metal and/or metal ions having cathodic potential are introduced into the solution, and further characterized in that the oxidation takes place at a dimensionally stable anode.
An important advantage of the process is that, due to the high degree of 25 efficiency, a rapid reaction sequence is achieved, and thereby not only the powe~ consumption costs but also the electrode costs (coating costs) may be held relatively low.
A further advantage is obtained by recycling tne cathodically deposited metallic`
component of the cyanide compound.
,:
, ~ . .
~7~6~
, ,,, According to another general aspect of the present invention, apparatus is provided for electrolytically detoxifying or regenerating an aqueous solution containing cyanide by means of anodic oxidation, wherein at least two eiectrodes are immersed in the solution, and at least one of these electrodes 5 consists substantially of valve metal, and the surface of the anode contains at least a noble metal and/or noble metal oxide, and at least the surface of the cathode contains silver or copper, characterized in that the anode is a dimensionally stable electrode having an electrocatalytic coating consisting of oxides of the platinum group oF metals and/or of valve metal, and consisting 10 also of platinum metals, and the spacing between the anode and the cathode is in the range of 5 - 50 mm.
The term "expanded metal grid" used in the present disclosure and claims also relat~s to an expanded metal foil.
One important advantage of th0 equipment is that the anode has a long service 15 life because of its dimensionally stable structure and the high degree of resistance of its coating. Furthermore, because of the high degree of efficiency, the size and thus also the costs of the equipment may be kept :
relatively low.
In the following, the subject of the invention is explained on the basis of various 20 embodiments.
~L~.
An electrochemical cell having a solution container with a superjacent cell housing containing a paGkage of elongated, plate-shaped electrodes arranged parallel to and at a distance from each other, with the anodes being arranged 25 in the centre of the housing and the cathodes at the ends of the housing, is used to electrochemically detoxiFy a pure cyanidic solution containing 5 - 100 g/L cyanide. The cathode used consists of an expanded metal grid of copper-plated titanium (copper surface), while the anode takes the form of a ` ' ! ' ', ~` ' , ~' ', ~ , . ,.
A Process for Electrolytically Detoxifying or - Regenerating an Aqueous Solution Containing Cyanide and an Apparatus for Carrying out the Process The invention relates to a process for electrolytically detoxifying or regenerating 5 an aqueous solution containing cyanide, wherein cyanide is converted by means of anodic oxidation into carbon dioxide and/or nitrogen and/or ammonia, also an apparatus for carrying out the process.
German Patent Application DE-OS 26 00 084 describes the electrochemical treatment of dilute metal cyanide solutions such as occur, for example, in the 10 forrn of washing solutions in electroplating installations; in the described process, cyanide is anodically oxidized while rnetal is simultaneously cathodically deposited. The anode and cathoda are designed as reticulate structures or wire-mesh baskets, and both electrodss may be made from platinum-coated titanium; however, it is also possible to uss a copper cathode.
15 In accordance with one embodiment of the invention, the solution to be treated contains, in addition to copper cyanide, also sodium cyanide and sodium carbonate as well as Rochelle salt.
When carrying out electrohJtic oxidation in low concentration ranges, the unsatisfactory current efficiency proves to be a problem so that, in view of the20 customarily strictwaste discharge conditions (environmental restrictions~
imposed by the authorities, it is essential to use an additional process for detoxifying low cyanide concentrations. Furthermore, high rates of srosion (=
short seMce iives) occur at the platinum coated titanium electrodes, so that in practice the process for the electrochemical oxidation of cyanide is not very 25 economical because of the high resulting costs (anode costs~.
Furthermore, German Patent DE PS 28 36 720 describes a procsss for the continuous electrolytic regeneration of a washing solution containing silver cyanide, such as occurs during electroplating processes, wherein the , , .; .: - . ~
'~ `
`' ~ `' ` ' ;
- r~ 2 ~ 9 f~, !
concentration of cyanide is greatly reduced by anodic oxidation to ammonia, and at the same time the silver is deposited in spongy form on the cathode, from which it is periodically stripped and collected in a funnel arranged in thebottom of the regeneration cell and then filtered off. In accordance with one 5 embodiment of the invention, the anode possesses a coating of titanium and platlnum while the cathode is plated with purs silver, so that here again the problem of high erosion rates of platinum-coated titanium electrodes is encountsr~d, thereby resulting in high attendant costs in practice.
It is an object of the invention to propose a means by which the large volumes 10 of cyanidic waste water accumulating, in particular, in electroplating operations may be elactrochemically treated in a cost-effective manner, with high current efficiencies beirlg achieved even at low concentrations, thus rendering further detoxification processs superfluous; furthermore, the purpose is also to ~.
propose an apparatus for the electrolytic detoxification or regeneration of an 15 aqueous solution containing cyanide; and an additional goal is to increase the Iifetime of the anodes.
In general terms, ths invention provides a process for electrolytically detoxifying or regenerating an aqueous solution containing cyanide, wherein cyanide is converted by means of anodic oxidation into carbon dioxide and/or nitrogen 20 and/or ammonia, characterized in that in order to improve the efficiency of the cyanid~ conversion process a metal and/or metal ions having cathodic potential are introduced into the solution, and further characterized in that the oxidation takes place at a dimensionally stable anode.
An important advantage of the process is that, due to the high degree of 25 efficiency, a rapid reaction sequence is achieved, and thereby not only the powe~ consumption costs but also the electrode costs (coating costs) may be held relatively low.
A further advantage is obtained by recycling tne cathodically deposited metallic`
component of the cyanide compound.
,:
, ~ . .
~7~6~
, ,,, According to another general aspect of the present invention, apparatus is provided for electrolytically detoxifying or regenerating an aqueous solution containing cyanide by means of anodic oxidation, wherein at least two eiectrodes are immersed in the solution, and at least one of these electrodes 5 consists substantially of valve metal, and the surface of the anode contains at least a noble metal and/or noble metal oxide, and at least the surface of the cathode contains silver or copper, characterized in that the anode is a dimensionally stable electrode having an electrocatalytic coating consisting of oxides of the platinum group oF metals and/or of valve metal, and consisting 10 also of platinum metals, and the spacing between the anode and the cathode is in the range of 5 - 50 mm.
The term "expanded metal grid" used in the present disclosure and claims also relat~s to an expanded metal foil.
One important advantage of th0 equipment is that the anode has a long service 15 life because of its dimensionally stable structure and the high degree of resistance of its coating. Furthermore, because of the high degree of efficiency, the size and thus also the costs of the equipment may be kept :
relatively low.
In the following, the subject of the invention is explained on the basis of various 20 embodiments.
~L~.
An electrochemical cell having a solution container with a superjacent cell housing containing a paGkage of elongated, plate-shaped electrodes arranged parallel to and at a distance from each other, with the anodes being arranged 25 in the centre of the housing and the cathodes at the ends of the housing, is used to electrochemically detoxiFy a pure cyanidic solution containing 5 - 100 g/L cyanide. The cathode used consists of an expanded metal grid of copper-plated titanium (copper surface), while the anode takes the form of a ` ' ! ' ', ~` ' , ~' ', ~ , . ,.
2~7~J ,---dimensionally stable titanium-based anode having an electrocatalytic coating consisting oF oxides of the platinum group of metals and/or of titanium, and also corisisting of metals from the platinum group. The fundamental structure of such anodes is known, for example, from German Patent DE-PS 20 41 250.
5 The volume o~ the solution container is in the range of 50 - 1000 L; the anodic current density is in the range of 10û - 2500 A/m2. The distance between the electrodes is in the range of 0.5 - 5 cm. The reac~ion takes place at a temperature in the range of 20 - 50C. The electrolytic detoxification is carried out until a final cyanide concentration of 0.2 mg/L and a final copper 10 concentration of 0.1 mg/L is achieved.
When treating a solution of the kind mentioned in Example 1 with the addition of copper in the range of 10 - 500 mg/L copper ions, it is also possible to carry out the first phase of the treatment (first run-through) using a cathode made of15 expanded titanium metal without any copper-plated surface or copper coating.
The copper is added either in the form of copper sulphate (solid or dissolved) or in the form of a waste water solution containing copper ions. The remaining process parameters mentioned in Example 1, as well as the structure of the dimensionally stable anode and the electrode spacing mentioned in that 20 example, are retained.
A Gyanidic silver solution containing 13.5 g/~ silver ions and 1.8 g/L free cyanide ions is demetallized using an electrochemical apparatus having a dimensionally stable anods in accordance with Examples 1 and 2 and squipped 25 with a cathode made of expanded copper metal foil. The electrochemical treatment is carried out until a silver ion concentration of less than 0.1 mg/L is obtained; the residual cyanide concentration following demetallizing is 8.~ g/L
free cyanide ions. The remaining process parameters, such as the anodic and cathodic current density, the electrode spacing and the temperature 30 correspond to those quoted in Example 1.
"
2~7~J9 , However, it is also possible, instead of an expanded copper metal foil, to use an expanded silver metal foil.
-The demetallized solution obtained in this manner may be detoxified accordingto the process described in Example 1 or according to the process described 5 in the following Example 4.
A silver cyanide solution from which the silver has been removed (silver ion concentration less than 0.1 mg/L) and containing 8.6 g/L free cyanide is supplied to a suitably constructed electrochemical cell whose cathode consists 10 of copper-plated expanded titaniurn metal. The current density and electrode spacing, as well as the operating temperature, are maintained at the sama values as those quoted in the preceding examples. The electrolytic detoxification (anodic oxidation) i5 carried out until a cyanide content of 0.1 mg/L is measured.
15 In an apparatus for carrying out the processs of Examples 1 to 4, solution issupplied by means of a recirculating device to ~he bottom area of the cell housing1 and once it has passed through the package of electrodes it flows via an overflow over the side walis of the cell housing into a discharge container, arran3ed in cascade fashion with its own overflow, for the purpose of 20 degassing the solution; once the solution has passed a second overFlow stage it has become substantiaily degassed and it is returned to the solution container and recirculated, and it continues to undergo electrochemical treatment until the desired or legally prescribed residual concentration is attained.
... . -~:, ~ ., :. .
5 The volume o~ the solution container is in the range of 50 - 1000 L; the anodic current density is in the range of 10û - 2500 A/m2. The distance between the electrodes is in the range of 0.5 - 5 cm. The reac~ion takes place at a temperature in the range of 20 - 50C. The electrolytic detoxification is carried out until a final cyanide concentration of 0.2 mg/L and a final copper 10 concentration of 0.1 mg/L is achieved.
When treating a solution of the kind mentioned in Example 1 with the addition of copper in the range of 10 - 500 mg/L copper ions, it is also possible to carry out the first phase of the treatment (first run-through) using a cathode made of15 expanded titanium metal without any copper-plated surface or copper coating.
The copper is added either in the form of copper sulphate (solid or dissolved) or in the form of a waste water solution containing copper ions. The remaining process parameters mentioned in Example 1, as well as the structure of the dimensionally stable anode and the electrode spacing mentioned in that 20 example, are retained.
A Gyanidic silver solution containing 13.5 g/~ silver ions and 1.8 g/L free cyanide ions is demetallized using an electrochemical apparatus having a dimensionally stable anods in accordance with Examples 1 and 2 and squipped 25 with a cathode made of expanded copper metal foil. The electrochemical treatment is carried out until a silver ion concentration of less than 0.1 mg/L is obtained; the residual cyanide concentration following demetallizing is 8.~ g/L
free cyanide ions. The remaining process parameters, such as the anodic and cathodic current density, the electrode spacing and the temperature 30 correspond to those quoted in Example 1.
"
2~7~J9 , However, it is also possible, instead of an expanded copper metal foil, to use an expanded silver metal foil.
-The demetallized solution obtained in this manner may be detoxified accordingto the process described in Example 1 or according to the process described 5 in the following Example 4.
A silver cyanide solution from which the silver has been removed (silver ion concentration less than 0.1 mg/L) and containing 8.6 g/L free cyanide is supplied to a suitably constructed electrochemical cell whose cathode consists 10 of copper-plated expanded titaniurn metal. The current density and electrode spacing, as well as the operating temperature, are maintained at the sama values as those quoted in the preceding examples. The electrolytic detoxification (anodic oxidation) i5 carried out until a cyanide content of 0.1 mg/L is measured.
15 In an apparatus for carrying out the processs of Examples 1 to 4, solution issupplied by means of a recirculating device to ~he bottom area of the cell housing1 and once it has passed through the package of electrodes it flows via an overflow over the side walis of the cell housing into a discharge container, arran3ed in cascade fashion with its own overflow, for the purpose of 20 degassing the solution; once the solution has passed a second overFlow stage it has become substantiaily degassed and it is returned to the solution container and recirculated, and it continues to undergo electrochemical treatment until the desired or legally prescribed residual concentration is attained.
... . -~:, ~ ., :. .
Claims (15)
1. A process for electrolytically detoxifying or regenerating an aqueous solution containing cyanide, wherein cyanide is converted by means of anodic oxidation into carbon dioxide and/or nitrogen and/or ammonia, characterized in that in order to improve the efficiency of the cyanide conversion process a metal and/or metal ions having cathodic potential are introduced into the solution, and further characterized in that the oxidation takes place at a dimensionally stable anode.
2. A process according to Claim 1, characterized in that the cyanide conversion is carried out at an anodic current density in the range of 100 -2500 A/m2 and at a cathodic current density in the range of 50 - 1500 A/m2.
3. A process according to Claim 1, characterized in that a metal whose surface consists at least of copper is introduced into the solution.
4. A process according to one of Claims 1 to 3, characterized in that copper ions are added to the solution.
5. A process according to Claim 1 or 2, characterized in that a metal whose surface consists at least of silver is introduced into the solution.
6. A process according to one of Claims 1 or 2, characterized in that silver ions are added to the solution.
7. A process according to one of the Claims 1 to 3, characterized in that the conversion of the cyanide is carried out until a final concentration of 0.2 mg/L cyanide is reached in the solution.
8. An apparatus for electrolytically detoxifying or regenerating an aqueous solution containing cyanide by means of anodic oxidation, wherein at least two electrodes are immersed in the solution, and at least one of these electrodes consists substantially of valve metal, and the surface of the anode contains at least a noble metal and/or noble metal oxide, and at least the surface of the cathode contains silver or copper, characterized in that the anode is a dimensionally stable electrode having an electrocatalytic coating consisting of oxides of the platinum group of metals and/or of valve metal, and consisting also of platinum metals, and the spacing between the anode and the cathode is in the range of 5 - 50 mm.
9. An apparatus according to Claim 8, characterized in that the valve metal is titanium.
10. An apparatus according to Claim 8, characterized in that the cathode consists of an expanded metal grid.
11. An apparatus according to Claim 8, characterized in that the cathode consists of metal sheet having a thickness in the range of 0.5 - 2.5 mm.
12. An apparatus according to one of Claims 8 to 11, characterized in that the cathode consists of copper-plated titanium.
13. An apparatus according to one of Claims 8 to 11. characterized in that the cathode consists substantially of copper.
14. An apparatus according to one of Claims 8 to 11, characterized in that the cathode consists of silver-plated titanium.
15. An apparatus according to one of Claims 8 to 11, characterized in that the cathode consists substantially of silver.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DEP4218916.0 | 1992-06-10 | ||
| DE19924218916 DE4218916C2 (en) | 1992-06-10 | 1992-06-10 | Use of a grid anode for electrolytic detoxification or regeneration of an aqueous solution containing cyanide |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2097869A1 true CA2097869A1 (en) | 1993-12-11 |
Family
ID=6460670
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2097869 Abandoned CA2097869A1 (en) | 1992-06-10 | 1993-06-07 | Process for electrolytically detoxifying or regenerating an aqueous solution containing cyanide and an apparatus for carrying out the process |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0573743A3 (en) |
| JP (1) | JPH06101081A (en) |
| CA (1) | CA2097869A1 (en) |
| DE (1) | DE4218916C2 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102004023161A1 (en) * | 2004-05-07 | 2005-11-24 | Eilenburger Elektrolyse- Und Umwelttechnik Gmbh | Electrolysis cell with multilayer expanded metal cathodes |
| CN116212941B (en) * | 2022-12-08 | 2024-07-23 | 湖南大学 | Preparation method and application of catalyst |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| BE758770A (en) * | 1969-11-28 | 1971-04-16 | Loftfield Richard E | Dimensionally stable anode |
| DE2251442C3 (en) * | 1972-10-20 | 1980-01-10 | Gewerkschaft Keramchemie, 5433 Siershahn | Process for the electrolytic detoxification of cyanide |
| GB1483126A (en) * | 1975-01-03 | 1977-08-17 | Electricity Council | Electrolytic treatment of dilute cyanide solution and cell therefor |
| JPS53140235A (en) * | 1977-03-02 | 1978-12-07 | Okubo Katsuhiro | Continuous circulation system electrolytic treatment method of silver plating wash water and its device |
| DE2836720C2 (en) * | 1978-08-22 | 1986-06-26 | Okubo, Katsuhiro, Tokio/Tokyo | Process for the continuous electrolytic regeneration of a washing solution containing silver cyanide which occurs during electroplating processes and a device for carrying out the process |
-
1992
- 1992-06-10 DE DE19924218916 patent/DE4218916C2/en not_active Expired - Fee Related
-
1993
- 1993-03-16 EP EP93104209A patent/EP0573743A3/en not_active Withdrawn
- 1993-06-07 CA CA 2097869 patent/CA2097869A1/en not_active Abandoned
- 1993-06-10 JP JP5138711A patent/JPH06101081A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| JPH06101081A (en) | 1994-04-12 |
| DE4218916C2 (en) | 1996-03-21 |
| DE4218916A1 (en) | 1993-12-16 |
| EP0573743A3 (en) | 1995-05-17 |
| EP0573743A2 (en) | 1993-12-15 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| EP0071443B1 (en) | Device for waste water treatment | |
| EP0074167A1 (en) | Metal contaminant removal | |
| US5599437A (en) | Electrolysis of electroactive species using pulsed current | |
| CA2449512A1 (en) | Electrolysis cell for restoring the concentration of metal ions in electroplating processes | |
| Lanza et al. | Removal of Zn (II) from chloride medium using a porous electrode: current penetration within the cathode | |
| US7056424B2 (en) | Cathode for electrochemical regeneration of permanganate etching solutions | |
| RU2181150C2 (en) | Method of pickling steel | |
| CA2391038A1 (en) | Method and device for regulating the metal ion concentration in an electrolyte fluid as well as application of said method and use of said device | |
| US4859300A (en) | Process for treating plastics with alkaline permanganate solutions | |
| CA2439061A1 (en) | Method and device for recovering metals with pulsating cathode currents also combined with anode coupling processes | |
| US4064022A (en) | Method of recovering metals from sludges | |
| US4069116A (en) | Electrochemical process for producing manganese dioxide | |
| US4564432A (en) | Apparatus for recovering metals dissolved in a solution | |
| CN1802456A (en) | Method for regenerating etching solutions containing iron for the use in etching or pickling copper or copper alloys and an apparatus for carrying out said method | |
| CA2097869A1 (en) | Process for electrolytically detoxifying or regenerating an aqueous solution containing cyanide and an apparatus for carrying out the process | |
| EP0226291B1 (en) | Method for extending service life of a hydrogen-evolution electrode | |
| Kim et al. | Performance assessment of electrolysis using copper and catalyzed electrodes for enhanced nutrient removal from wastewater | |
| JP2640933B2 (en) | Electrolytic treatment method for chemical plating waste liquid | |
| EP0602141B1 (en) | Electrolytic device and method having a porous stirring electrode | |
| EP0435835A2 (en) | Process for electroplating zinc alloy and apparatus employed therefor | |
| CA2517379C (en) | Method for copper electrowinning in hydrochloric solution | |
| Socha et al. | Simultaneous Electrooxidation of Cyanides and Recovery of Copper on Carbon Fibre | |
| EP4007824A1 (en) | Metal recovery from lead containing electrolytes | |
| JPH06336700A (en) | Treatment of waste water and water washings from noble metal plating using cyanide bath | |
| JPH06142654A (en) | Water modifying electrode |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Dead |