CA2738135A1 - Cathode for the electrolytic deposition of zinc or the like from an electrolyte bath - Google Patents

Cathode for the electrolytic deposition of zinc or the like from an electrolyte bath Download PDF

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Publication number
CA2738135A1
CA2738135A1 CA2738135A CA2738135A CA2738135A1 CA 2738135 A1 CA2738135 A1 CA 2738135A1 CA 2738135 A CA2738135 A CA 2738135A CA 2738135 A CA2738135 A CA 2738135A CA 2738135 A1 CA2738135 A1 CA 2738135A1
Authority
CA
Canada
Prior art keywords
cathode
cathode sheet
edge strips
sheet
electrolyte
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
Application number
CA2738135A
Other languages
French (fr)
Inventor
Wolfgang Reiser
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.)
EMS ELEKTRO METALL SCHWANENMUEHLE GmbH
Original Assignee
EMS ELEKTRO METALL SCHWANENMUEHLE GmbH
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
Application filed by EMS ELEKTRO METALL SCHWANENMUEHLE GmbH filed Critical EMS ELEKTRO METALL SCHWANENMUEHLE GmbH
Publication of CA2738135A1 publication Critical patent/CA2738135A1/en
Abandoned legal-status Critical Current

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Classifications

    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25CPROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/02Electrodes; Connections thereof
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25CPROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C1/00Electrolytic production, recovery or refining of metals by electrolysis of solutions
    • C25C1/16Electrolytic production, recovery or refining of metals by electrolysis of solutions of zinc, cadmium or mercury
    • CCHEMISTRY; METALLURGY
    • C25ELECTROLYTIC OR ELECTROPHORETIC PROCESSES; APPARATUS THEREFOR
    • C25CPROCESSES FOR THE ELECTROLYTIC PRODUCTION, RECOVERY OR REFINING OF METALS; APPARATUS THEREFOR
    • C25C7/00Constructional parts, or assemblies thereof, of cells; Servicing or operating of cells
    • C25C7/06Operating or servicing
    • C25C7/08Separating of deposited metals from the cathode

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Electrochemistry (AREA)
  • Materials Engineering (AREA)
  • Metallurgy (AREA)
  • Organic Chemistry (AREA)
  • Electrolytic Production Of Metals (AREA)

Abstract

The invention relates to a cathode for the electrolytic deposition of zinc or the like, which comprises an electrolyte bath, which has a cathode sheet, a supporting and contact bar, which is attached to the upper edge of the plate--like cathode sheet and has a higher stability than the cathode sheet and has edge strips mounted at the lateral edges and possibly at the bottom edge of the cathode sheet. The edge strips are composed of an electrolyte-resistant metal, the electrical conductivity of which is lower than that of cathode sheet.

Description

EMS Elektro Metall Schwanenmuhle GmbH, D-66851 Schwanenmuhle Cathode for the electrolytic deposition of zinc or the like from an electrolyte bath The invention relates to a cathode for the electrolytic deposition of zinc or the like from an electrolyte bath, comprising a cathode sheet, a support and contact rail which is attached to the upper edge of the plate-shaped cathode sheet and has a higher stability than the cathode sheet, and edge strips attached to the lateral edges and, optionally, the lower edge of the cathode sheet.

The known electrolytic deposition of metal ions on a cathode is suitable for obtaining largely pure zinc. In the process, metal ions are electrolytically dissolved in an acid bath of recycled material, such as ore, and deposited on a cathode. The transport of the metal ions through the acid electrolyte is caused by direct current flowing between the cathode and the anode.
For this purpose, suitable cathodes can generally be divided into two main components, namely the cathode plate or cathode sheet on which the metal to be obtained is deposited, and the part referred to as contact, support or also head rail, which serves for introducing the electrical current into the plate-shaped cathode sheet and for mechanically stabilizing and moving the cathode sheet.

The electrolytic deposition on the surfaces of cathodes of the zinc to be obtained follows the current density distribution between the anode and the cathode and, at the same time, protects the cathode sheet against corrosion in the acid bath.

In order to obtain a uniform deposition or a metal build-up that is as uniform as possible on the cathode, the goal is as constant a current density distribution over the cathode surface as possible. Normally, no metal deposition occurs at the upper liquid level of the acid bath, the so-called liquid zone, so that consequently, no protection of the cathode sheet against the acid electrolyte is created here by the deposited zinc.
Depending on the material used, the cathode sheet can therefore corrode in the liquid zone and wear down prematurely.

The metal deposited and built-up on the cathode during the electrolytic deposition is peeled off both sides of the cathode outside the acid bath (stripping). In this context, it is an impediment if the material to be obtained grows over the edges of the cathode sheet during deposition in the acid bath or the electrolyte, thus connecting the two sides of the cathode sheet mechanically. There is, therefore, a requirement to keep the cathode edges free from the zinc to be obtained during the electrolytic deposition. For this purpose, it is known to attach to or on the cathode sheet so-called edge strips, which up till now consist of an electrically insulating material. The edge strips enclose the areas of the edges or rims of the cathode, so that the direct current flowing through the cathode is not introduced into the electrolyte bath at the edges, so that no metal ions are deposited and accumulated in those areas.

The edge strips enclose either only the two vertically extending edges of the cathode sheet, or also the lower, horizontally extending edge. A
variety of solutions are known with regard to the manner of attachment of the edge strips to the plate-shaped cathode sheet. However, what all of these solutions have in common is the use of an electrically insulating material such as plastic, rubber or wax for the edge strips.

These known cathodes with edge strips have some drawbacks which in practice lead to additional operating costs.

The known edge strips are unable to cope with large mechanical stresses and can be damaged when the cathode is processed outside the electrolyte bath. This can lead to impedimental metal depositions being produced in the area of the zone of the edge if the cathode is used again. Moreover, damages to the cathode sheet itself may also result.
The known edge strips are not connected sufficiently securely to the cathode sheet. Thus, infiltration by the electrolyte occurs. This leads to metal build-up in the area of the edge zones of the cathode sheet underneath the edge strips, or even to the dissolution of the cathode material in the electrolyte. In both cases, the area of the edge zones of the cathode sheet underneath the edge strips is destroyed. The period of use of the cathode sheet is thus reduced. The edge strips may possibly also lose their purchase on the cathode sheet and remain in the electrolyte bath. This can cause considerable disturbances in operation.
Due to being used in the acid electrolyte, the edge strips change their chemical and physical properties. As a consequence, the electrolyte is contaminated with foreign chemicals or other foreign substances. There is also the danger of the edge strips wearing down prematurely.

The invention is based on the object of avoiding the drawbacks described above in the electrolytic deposition of metals from an electrolyte bath, and accordingly, of providing a cathode for the deposition of zinc and similar metals that can be used longer than known cathodes and thus has a longer life span.

According to the invention, this object is achieved with a cathode comprising the features of claim 1. Advantageous embodiments and developments of the invention are the subject matter of the sub-claims dependent on claim 1.

In contrast to the prior art described above, the edge strips, according to the present invention, do not consist of an electrically insulating material, but from a metal which is resistant against the electrolyte, but which has a significantly and substantially lower electrical conductivity than the cathode sheet. The deposition of the metal ions on the metallic edge strips of the cathode is reduced in accordance with the ratio of the conductance values of the metal used for the edge strips to the metal of the cathode sheet. The thickness of the metal layer thus formed in the edge strips is so small that the subsequent peeling process of the obtained zinc or similar metal is not affected by the surfaces of the cathode sheet.

According to the invention, the edge strips consist, for example, of stainless steel or titanium, whereas the cathode sheet can be an aluminum sheet.

These metallic edge strips can be securely and permanently attached to the cathode sheet in a suitable manner, for example by means of rivets, bolts, clamps or welding, so that the above-mentioned drawbacks of the known non-metallic edge strips are avoided.

Due to the substantially higher mechanical stability of the edge strips to be provided according to the invention, the danger of damage and loss is significantly reduced.
The metallic edge strips provided according to the invention can be connected to the cathode sheet with a much stronger support.

The metallic edge strips have an inert behavior with regard to the electrolyte. There is no change of the chemical or physical structure of the edge strips if the metallic material is suitably selected.

In order to protect the area of the cathode sheet located at the surface or the level of the electrolyte bath, a plastic coating process, for example, is carried out. The plastic is applied to the cathode sheet in a suitable manner and prevents corrosion so long as the plastic coating rests against the cathode sheet firmly and without a parting line. If this is not the case, an infiltration behind the plastic may occur and the corrosion will progress correspondingly fast.

Cathodes protected in the liquid zone are known. What these known cathodes have in common is the use of a chemically resistant plastic which, however, detaches relatively easily from the cathode sheet, thus 5 becoming incapable of fulfilling its function. Moreover, the area of the cathode sheet provided with a plastic coating is subjected to large mechanical stresses by the peeling process during the removal of the obtained metal, which leads to a premature wear of the plastic coating.

According to the invention, a chemically resistant metal, for example stainless steel or titanium, is used as a protection for the cathode sheet instead of plastic. Such a metal can be bonded to the cathode sheet very intimately, so that an infiltration of the electrolyte under the coating of the cathode sheet is prevented. Since metals generally have a higher mechanical strength than plastic, the wear when the obtained zinc or other metal is peeled off is reduced to a fraction as compared with plastic. The durability and the life span of the protection of the cathode are therefore significantly increased also in the area of the liquid zone.

In order to facilitate the process of peeling off the zinc deposited on the cathode by the electrolysis, the use of a so-called peeling blade is known. From above, this blade pushes between the cathode sheet and the metal layer deposited thereon. In many cases, contact disks of plastic, which are provided on one or also on both sides of the cathode sheet at the level of the liquid zone or electrolyte surface, serve as the contact for the peeling blade. The known contact disks consist of plastic, since that is not electrically conductive and therefore prevents the build-up of a metal layer in this area. However, the contact disks are subjected to strong mechanical stress due to the impact of the peeling blade during stripping. Therefore, the contact disks are often damaged or even knocked out. Then, their functional capability is not provided anymore.
According to the invention, the contact disks also consist of metals resistant to the acid bath or the electrolyte, such as, for example, stainless steel or titanium. The build-up of the metal layer produced on the cathode during the electrolytic deposition occurs in accordance with the ratio of the conductance values of the metals used for the contact disks and the cathode sheet. The thickness of the metal layer forming on the contact disk can be influenced by the electrical transition between the cathode sheet and the contact disks. A metal layer deposited appropriately thinly on the contact disks does not impede the function of the peeling blade. The impact of the peeling blade on the contact disks consisting of metal is incapable of damaging or destroying the contact disks. Therefore, the metallic contact disks have a significantly higher life span than known contact disks of plastic.

Because the contact disks are disposed on the cathode in the area of the electrolyte surface or liquid zone, they can be combined with the metallic liquid zone protection described above and connected therewith to form a unit. Liquid zone protection with an integrated contact disk also extends the life span of the cathode sheet.

For further explanation of the invention, an exemplary embodiment of the cathode according to the invention is represented schematically in an illustration in the drawing.

The cathode 1 comprises a cathode sheet 2 consisting of aluminum sheet, for example, which is attached to a support rail 3. At the position shown in the drawing, the cathode sheet 2 can be hung into an electrolyte bath whose surface is indicated by a dashed line 4.

The support rail 3 is provided with hooks 5 for handling and with contacts for introducing current 6.
To the vertical edges 7 of the cathode sheet, edge strips 8 are permanently attached which consist of metal whose electrical conductivity is significantly lower than that of the cathode sheet. In the exemplary embodiment shown, another edge strip 9 consisting of the same metal as the edge strip 8 is attached to the lower edge of the cathode sheet 2. However, this edge strip 9 may also be omitted.
Contact disks 10 of the same material as the edge strips 8 and 9, which serve for facilitating the contact of peeling blades, are attached - on one side or both sides - to the cathode sheet 2 at the level of the surface of the electrolyte bath (dashed line 4).

A protective layer 11 that can consist of the same material as the edge strips 8 and 9 and the contact disks 10 is disposed on the front and the rear of the cathode sheet 2 in the area of the liquid zone of the electrolyte bath or the surface thereof (dashed line 4).

An electrical insulation, for example, an insulating coating or an insulating intermediate layer, can be provided between the cathode sheet 2 and the edge strips 8 and 9 which are applied thereto and consist of poorly conductive metal and the also poorly conductive contact disks 10, in order to keep the deposition of zinc or other metal on these additional components as small as possible.
The ratio of the electrical conductivity between the cathode sheet 2 consisting of aluminum and the edge strips 8 and 9 consisting of stainless steel is about 50:1. If titanium is used for the edge strips and the contact pieces, this ratio is much larger since titanium is a very poor conductor.

Claims (7)

1. Cathode for the electrolytic deposition of zinc or the like from an electrolyte bath, with an electrically conductive cathode sheet to whose upper edge a supporting and contact rail having a higher stability than the cathode sheet is attached, and with edge strips attached to the other edges of the cathode sheet, characterized in that the edge strips (8; 9; 10) of the cathode sheet (2) consist of metal which is resistant to the electrolyte used and whose electrical conductivity is significantly lower than that of the cathode sheet.
2. Cathode according to claim 1, characterized in that the cathode sheet consists of aluminum.
3. Cathode according to claim 1 or 2, characterized in that the edge strips (8; 9) consist of stainless steel.
4. Cathode according to claim 1 or 2, characterized in that the edge strips (8; 9) consist of titanium.
5. Cathode according to any one of the claims 1 to 4, characterized in that the cathode sheet (2), in the region of the liquidity zone (4) of the electrolyte bath, is provided with a cover or a coating or a protection of stainless steel or titanium.
6. Cathode according to any one of the claims 1 to 5, characterized in that the cathode sheet (2) is provided with contact disks (10) for contacting a peeling blade, which consist of a metal with a significantly lower electrical conductivity than the cathode sheet.
7. Cathode according to any one of the claims 1 to 6, characterized in that an electrical insulation is provided between the cathode sheet (2) and the edge strips (8; 9) and the contact disks (10).
CA2738135A 2008-08-29 2009-08-11 Cathode for the electrolytic deposition of zinc or the like from an electrolyte bath Abandoned CA2738135A1 (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
DE102008041698.3 2008-08-29
DE200810041698 DE102008041698A1 (en) 2008-08-29 2008-08-29 Cathode for the electrolytic deposition of zinc or the like. From an electrolyte bath
PCT/EP2009/060391 WO2010023101A1 (en) 2008-08-29 2009-08-11 Cathode for the electrolytic deposition of zinc or the like from an electrolyte bath

Publications (1)

Publication Number Publication Date
CA2738135A1 true CA2738135A1 (en) 2010-03-04

Family

ID=41353907

Family Applications (1)

Application Number Title Priority Date Filing Date
CA2738135A Abandoned CA2738135A1 (en) 2008-08-29 2009-08-11 Cathode for the electrolytic deposition of zinc or the like from an electrolyte bath

Country Status (5)

Country Link
EP (1) EP2324143A1 (en)
AU (1) AU2009286832A1 (en)
CA (1) CA2738135A1 (en)
DE (1) DE102008041698A1 (en)
WO (1) WO2010023101A1 (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018119497A1 (en) * 2016-12-28 2018-07-05 Cecal Tecno Indústria E Comércio De Equipamentos Sob Encomenda Ltda. Lateral protection for a cathode of an electrolytic cell for producing zinc

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102014003424B4 (en) 2014-03-04 2017-04-13 Vdm Metals International Gmbh Cathode for the electrolytic zinc extraction
CN104762640B (en) * 2015-04-28 2017-11-21 北京矿冶研究总院 Electro-deposition metal pre-stripping device

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US1977499A (en) * 1932-12-28 1934-10-16 Tetrault Michael Electrolytic apparatus
GB2080829B (en) * 1980-07-26 1984-01-18 Berger Peter Electrode edge protector especially starting sheets in electrowinning and electrorefining
US4551219A (en) * 1984-05-21 1985-11-05 Pfizer Inc. Flush edge protected metal laminates
AT395722B (en) * 1990-04-23 1993-02-25 Austria Metall ALUMINUM CATHODE SHEETS FOR ELECTROLYTIC PRODUCTION OF ZINC
AT403808B (en) * 1994-09-29 1998-05-25 Austria Metall Cathode plate for the electrolytic recovery of metals from a liquid electrolyte

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2018119497A1 (en) * 2016-12-28 2018-07-05 Cecal Tecno Indústria E Comércio De Equipamentos Sob Encomenda Ltda. Lateral protection for a cathode of an electrolytic cell for producing zinc
ES2779774R1 (en) * 2016-12-28 2020-10-09 Cecal Tecno Ind E Comercio De Equipamentos Sob Encomenda Ltda SIDE PROTECTION FOR CATHODE OF ELECTOLYTIC TUBE FOR PRODUCTION OF METALLIC ZINC

Also Published As

Publication number Publication date
DE102008041698A1 (en) 2010-03-04
WO2010023101A1 (en) 2010-03-04
AU2009286832A1 (en) 2010-03-04
EP2324143A1 (en) 2011-05-25

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Legal Events

Date Code Title Description
FZDE Discontinued

Effective date: 20150811