Classifications

• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
  • C25D17/10—Electrodes, e.g. composition, counter electrode
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D17/00—Constructional parts, or assemblies thereof, of cells for electrolytic coating
  • C25D17/10—Electrodes, e.g. composition, counter electrode
  • C25D17/12—Shape or form
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
  • C25B11/02—Electrodes; Manufacture thereof not otherwise provided for characterised by shape or form
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25B—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES FOR THE PRODUCTION OF COMPOUNDS OR NON-METALS; APPARATUS THEREFOR
  • C25B11/00—Electrodes; Manufacture thereof not otherwise provided for
  • C25B11/04—Electrodes; Manufacture thereof not otherwise provided for characterised by the material
  • C25B11/051—Electrodes formed of electrocatalysts on a substrate or carrier
  • C25B11/073—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material
  • C25B11/091—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds
  • C25B11/093—Electrodes formed of electrocatalysts on a substrate or carrier characterised by the electrocatalyst material consisting of at least one catalytic element and at least one catalytic compound; consisting of two or more catalytic elements or catalytic compounds at least one noble metal or noble metal oxide and at least one non-noble metal oxide
• • 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
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D7/00—Electroplating characterised by the article coated
  • C25D7/06—Wires; Strips; Foils
  • C25D7/0607—Wires
• • C—CHEMISTRY; METALLURGY
  • C25—ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
  • C25D—PROCESSES FOR THE ELECTROLYTIC OR ELECTROPHORETIC PRODUCTION OF COATINGS; ELECTROFORMING; APPARATUS THEREFOR
  • C25D7/00—Electroplating characterised by the article coated
  • C25D7/06—Wires; Strips; Foils
  • C25D7/0614—Strips or foils
  • C25D7/0642—Anodes

Definitions

• the invention relates to an electrode structure for oxygen evolution suitable for plants of galvanic electrodeposition of metals equipped with horizontal cells.
• non consumable anodes in processes of galvanic electrodeposition of metals in horizontal cells as a replacement of heavier and less performant lead anodes is a well-known practice in the art.
• Insoluble anodes allow in fact a higher flexibility in plant design and consequent operation mode.
• Non consumable anodes also allow operating at higher current density than lead anodes with consequent advantages on productivity.
• oxygen is produced as the result of the anodic reaction. Operating at higher current density making use of non- consumable anodes brings about however an increased oxygen production on the anode surface.
• electrodeposition plants are equipped with horizontal cells; in such case, a metal ribbon or wire used as cathode is transported across an electrolytic bath between rows of anodes arranged parallel to each other.
• an increased oxygen production generally implies problems associated with gas stagnation with consequent increase of local current density which negatively affects homogeneity of deposition. It would therefore be desirable to provide an electrode with enhanced mechanical
• the invention relates to an electrode for oxygen evolution in electroplating plants equipped with horizontal cells, comprising a valve metal substrate and an outer catalytic layer, said substrate consisting of a metal sheet provided with slits of area ranging from 2 to 8 cm 2 , said slits being spaced apart by a distance of 5 to 25 cm.
• the slits are arranged in an evently spaced apart configuration.
• the electrode has a rectangular shape and said slits have an elongated shape, optionally with the major side arranged parallel to the short side of the electrode.
• the electrode for oxygen evolution in electroplating plants equipped with horizontal cells is provided with slits regularly spaced apart and having an area of 3 to 5 cm 2 .
• slits regularly spaced apart and having an area of 3 to 5 cm 2 .
• the production of metal does not show any advantage with slits having a lower size than the one specified and spaced apart by a larger distance. This could happen because too small and spaced apart slits do not allow a sufficient gas release and recirculation.
• too large and tightly spaced slits entail a loss of active area negatively affecting the homogeneity of deposition.
• valve metal of the oxygen-evolving electrode in electroplating plants equipped with horizontal cells is titanium and the catalytic layer comprises oxides of iridium, tantalum and titanium.
• the present invention relates to a horizontal electrochemical cell for electroplating processes comprising at least one electrode as hereinbefore described. So long as the anodic section is structured in two parallel rows of anodes with the metal ribbon of wire acting as cathode being transported therebetween, slits may be present on one row of anodes only, preferably the upper one.
• the invention relates to a cell comprising an upper row of anodes and a lower row of anodes, arranged one above the other, and a cathode consisting of a continuous metal ribbon or wire subject to an advancing motion between the upper row of anodes and the lower row of anodes, said direction of advancement being parallel to said parallel rows of anodes and said at least one electrode being an anode of said upper row of anodes.
• a cell having slits arranged with the major side perpendicular to the direction of advancement of the metal ribbon or wire used as the cathode.
• the present invention relates to an electroplating plant equipped with at least one horizontal electrochemical cell for electroplating processes comprising at least one electrode as hereinbefore described.
• Figure 1 shows a top view of a possible embodiment of an anode according to the invention provided with twelve slits.
• Figure 2 shows a side view of a possible embodiment of a horizontal cell according to the invention.
• FIG. 1 shows a top view of a possible embodiment of an anode A having twelve slits B mutually spaced apart by distance C and at distance D from the periphery.
• Figure 2 shows a side view of a possible embodiment of a horizontal cell having eight anodes L with twelve slits each, arranged in two parallel rows through which a metal ribbon I acting as the cathode is transported. There are also indicated electrolyte bath inlet E, depleted electrolyte bath outlet F, discharge of oxygen produced at the anodes G and level of electrolyte bath H.
• anodes of 1380 mm x 200 mm x 6 mm size consisting of a titanium substrate provided with a catalytic coating consisting of two distinct layers, namely a first (internal) layer based on oxides of tantalum and iridium in a 65:35 weight ratio (corresponding to a molar ratio of about 63.6:36.4), at an overall iridium loading of 10 g/m 2 , and a second (external) layer based on oxides of iridium, tantalum and titanium in a 78:20:2 weight ratio (corresponding to a molar ratio of about 72.6:19.9:7.5), at an overall iridium loading of 35 g/m 2 , were subdivided into two groups of eight anodes each and arranged parallel in two corresponding rows on either side of a sheet to be zinc-plated.
• Each anode was provided with 12 elongated slits of 400 mm 2 area, arranged with the short side oriented parallel to the length of the sheet, mutually spaced apart by 198 mm and at a distance of 25 mm from the periphery of the sheet.
• Anodes were tested in a zinc-plating plant with horizontal cells at a current density of 13 kA/m 2 with an electrolytic bath containing 100 g/l of zinc, at a temperature of 50°C and pH 2. Anode deactivation occurred after depositing 210 tons of zinc.
• an anode is considered to be deactivated when the slope of the ohmic drop in the electrolyte bath increases in time by 20% with respect to the initial value.
• current distribution becomes uneven with current concentrating in correspondence of the most active zones of the anodes: the concentration of current determines an increase of ohmic drop in the electrolyte bath which hence becomes a representative parameter of the state of conservation of anodes.
• anodes of 1380 mm x 200 mm x 6 mm size consisting of a titanium substrate provided with a catalytic coating consisting of two distinct layers, namely a first (internal) layer based on oxides of tantalum and iridium in a 65:35 weight ratio (corresponding to a molar ratio of about 63.6:36.4), at an overall iridium loading of 10 g/m 2 , and a second (external) layer based on oxides of iridium, tantalum and titanium in a 78:20:2 weight ratio (corresponding to a molar ratio of about 72.6:19.9:7.5), at an overall iridium loading of 35 g/m 2 , were subdivided into two groups of eight anodes each and arranged parallel in two corresponding rows on either side of a sheet to be zinc-plated.
• anodes of 1380 mm x 200 mm x 6 mm size consisting of a titanium substrate provided with a catalytic coating consisting of two distinct layers, namely a first (internal) layer based on oxides of tantalum and iridium in a 65:35 weight ratio (corresponding to a molar ratio of about 63.6:36.4), at an overall iridium loading of 10 g/m 2 , and a second (external) layer based on oxides of iridium, tantalum and titanium in a 78:20:2 weight ratio (corresponding to a molar ratio of about 72.6:19.9:7.5), at an overall iridium loading of 35 g/m 2 , were subdivided into two groups of eight anodes each and arranged parallel in two corresponding rows on either side of a sheet to be zinc-plated.
• Each anode was provided with 12 elongated slits of 400 mm 2 area, arranged with the short side oriented parallel to the length of the sheet, mutually spaced apart by 198 mm and at a distance of 25 mm from the periphery of the sheet.
• Anodes were tested in a zinc-plating plant with horizontal cells at a current density of 10 kA/m 2 with an electrolytic bath containing 100 g/l of zinc, at a temperature of 50°C and pH 2. Anode deactivation occurred after depositing 180 tons of zinc.
• COUNTEREXAMPLE 2 Sixteen anodes of 1380 mm x 200 mm x 6 mm size consisting of a titanium substrate provided with a catalytic coating consisting of two distinct layers, namely a first (internal) layer based on oxides of tantalum and iridium in a 65:35 weight ratio (corresponding to a molar ratio of about 63.6:36.4), at an overall iridium loading of 10 g/m 2 , and a second (external) layer based on oxides of iridium, tantalum and titanium in a 78:20:2 weight ratio (corresponding to a molar ratio of about 72.6:19.9:7.5), at an overall iridium loading of 35 g/m 2 , were subdivided into two groups of eight anodes each and arranged parallel in two corresponding rows on either side of a sheet to be zinc-plated.
• Anodes were tested in a zinc-plating plant with horizontal cells at a current density of 10 kA/m 2 with an electrolytic bath containing 100 g/l of zinc, at a temperature of 50°C and pH 2. Anode deactivation occurred after depositing 140 tons of zinc.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Electrochemistry (AREA)
• Materials Engineering (AREA)
• Metallurgy (AREA)
• Engineering & Computer Science (AREA)
• Electrodes For Compound Or Non-Metal Manufacture (AREA)
• Electroplating Methods And Accessories (AREA)
• Optical Measuring Cells (AREA)
• Breeding Of Plants And Reproduction By Means Of Culturing (AREA)
• Micro-Organisms Or Cultivation Processes Thereof (AREA)
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• 2011
  • 2011-11-24 IT IT002136A patent/ITMI20112136A1/it unknown
• 2012
  • 2012-11-23 WO PCT/EP2012/073527 patent/WO2013076277A2/en not_active Ceased
  • 2012-11-23 US US14/351,657 patent/US20140231267A1/en not_active Abandoned
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  • 2012-11-23 CN CN201280056364.0A patent/CN103946428A/zh active Pending
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  • 2012-11-23 BR BR112014011550A patent/BR112014011550A2/pt not_active Application Discontinuation
  • 2012-11-23 EP EP12799524.9A patent/EP2783027A2/en not_active Withdrawn
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• 2014
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