JP5615580B2 - Cathode plate, method for producing cathode plate, and metal electrolytic refining method - Google Patents

Description

  The present invention relates to a cathode plate used for refining by electrolysis of metal, a method for producing the cathode plate, and a metal electrolytic refining method using the cathode plate.

Conventionally, as a method of refining metal by electrolysis, an aluminum plate (alloy) is used as a cathode that is a cathode, and a lead plate or a lead-silver alloy plate that is insoluble in sulfuric acid is used as an anode that is an anode. A method is known in which zinc is deposited from a liquid on a cathode and refined.
In the refining method, the exposed non-immersed portion above the cathode surface of the cathode negative electrode is corroded or thinned by the mist of the strong acid electrolyte or the like. (See FIG. 3). In this way, when corrosion or thinning occurs, the strength of the cathode plate decreases, so it falls into an electrolytic cell during use, or the cathode plate is destroyed when refining the electrodeposited metal. There are problems such as. In particular, in the region immediately above the liquid surface of the non-immersed part, the thinning and corrosion are severe, and this problem is remarkable.

As a method of reusing the thinned and corroded cathode plate, a method of compensating for the thickness of the thinned and corroded portion can be considered, but it is not concrete.
However, in metal electrolytic refining, a plurality of electrodes are usually used, and repairing the thickness of each electrode is less efficient and it is more costly to use scrap as a recycled material. However, it is considered to be preferable, and in some cases, it is not assumed that the plate thickness is 1 mm or less, and further, the thickness of the corroded portion is not assumed to be thinned or cracked. Currently.
Furthermore, since the degree of thinning and corrosion varies depending on the position where each cathode plate is used in the electrolytic cell, it is unclear how much thickness of the cathode plate should be compensated.

  Therefore, the thinned and corroded cathode plate cannot be reused as a cathode plate, and is no longer used for electrolysis and is currently used as a recycled material for aluminum. If the metal is thinned or corroded, it must be replaced with a new plate, resulting in a huge cost.

Therefore, as an electrode plate that can be used for a long period of time and can suppress the metal production cost, a corrosion-resistant portion comprising an anodized film layer having micropores in a non-immersed portion and a fluororesin layer impregnated in the micropores There has been proposed an electrode plate formed with (for example, see Patent Document 1). In this proposal, thinning of the cathode plate can be suppressed by applying alumite treatment to lay the fluororesin layer on the non-immersed part of the cathode and laying the fluororesin layer. It is said that it can prolong the life, suppress the purchase of new cathodes, and reduce the manufacturing cost.
However, the alumite treatment and the fluororesin layer have a problem of high cost. In addition, when a part of the corrosion-resistant part is damaged and peeled during use, it is difficult to repair only the part, and when performing the repair, it is more expensive than newly laying. There's a problem. In addition, non-immersed parts that have been thinned and corroded by use may be further thinned by anodizing to reduce the strength and damage of the cathode plate. Therefore, there is a problem that this proposal cannot be used.

  Therefore, a cathode plate that can be manufactured at a low cost, can be used for a long period of time, can be easily repaired, and a cathode plate that is thinned and corroded by use can also be used. It is not yet provided, and there is a strong demand for prompt provision.

JP 2009-280891 A

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention can be manufactured at a low cost, can be used for a long period of time, can be easily repaired, and can use a cathode plate that has been thinned and corroded by use. It is an object of the present invention to provide a cathode plate, a method for producing the cathode plate, and a metal electrolytic refining method using the cathode plate.

  The present inventors have found that the above problem can be solved by roughening the surface desired to protect the cathode plate and forming a plurality of resin layers thereon.

Means for solving the problems are as follows. That is,
<1> A cathode plate used for metal electrolytic refining,
At least a part of the surface of the non-immersed part that is not immersed in the electrolyte solution of the cathode plate is roughened,
A cathode plate comprising a plurality of resin layers on the roughened surface.
<2> The plurality of resin layers are composed of a primer resin layer, a silicon fiber-containing resin layer, and a protective layer,
The cathode plate according to <1>, wherein a primer resin layer, a silicon fiber-containing resin layer, and a protective layer are provided in this order on the roughened surface.
<3> The cathode plate according to any one of <1> to <2>, wherein the entire surface of the non-immersed portion is roughened.
<4> The cathode plate according to any one of <1> to <3>, wherein the thickness of at least a part of the non-immersed part is thinner than that of the immersed part immersed in the electrolytic solution.
<5> The cathode plate according to <4>, wherein at least one end in the lateral direction of the non-immersed portion is repaired with a material of the cathode plate.
<6> The cathode plate according to any one of <4> to <5>, wherein both lateral ends of the non-immersed part are repaired with a material of the cathode plate.
<7> The method for producing a cathode plate according to any one of <1> to <6>,
A roughening step of roughening at least part of the surface of the non-immersed portion of the cathode plate;
A primer resin layer forming step of forming a primer resin layer on the roughened surface;
A silicon fiber-containing resin layer forming step of forming a resin layer containing silicon fibers on the surface of the primer resin layer;
A protective layer forming step of forming a protective layer on the surface of the silicon fiber-containing resin layer;
A method for producing a cathode plate, comprising:
<8> Further, a removal step of removing at least a part of the non-immersed portion of the cathode plate;
A filling step of filling the removed part with the material of the cathode plate;
It is a manufacturing method of the cathode plate as described in said <7> containing.
<9> The method for producing a cathode plate according to any one of <7> to <8>, wherein the roughening step is performed by sandblasting.
<10> A metal electrolytic refining method, wherein at least one cathode plate according to any one of <1> to <6> is used as a cathode electrode.

  According to the present invention, conventional problems can be solved, it can be manufactured at a low cost, it can be used for a long period of time, and it can be easily repaired. It is possible to provide a cathode plate capable of using the cathode plate, a method for producing the cathode plate, and a metal electrolytic refining method using the cathode plate.

FIG. 1 is a schematic front view of a cathode plate manufactured in Example 1. FIG. FIG. 2 is a schematic side view of the cathode plate manufactured in Example 1. FIG. FIG. 3 is a schematic view of the front surface of the cathode plate which has been corroded and thinned by use. FIG. 4 is a schematic front view of the cathode plate after being used for metal electrolytic refining. FIG. 5 is a schematic front view of the cathode plate after the filling process.

(Cathode plate and cathode plate manufacturing method)
The cathode plate of the present invention is a cathode plate used for metal electrolytic refining, wherein at least a part of the surface of the non-immersed portion that is not immersed in the electrolyte solution of the cathode plate is roughened, and the roughened surface. A plurality of resin layers are provided on the surface.
The plurality of resin layers particularly need chemical resistance to strong acids and the like, and heat resistance of about 100 ° C., but can be appropriately selected according to the intended function. The primer resin layer and the silicon fiber-containing resin layer And a protective layer, and it is preferable to have a primer resin layer, a silicon fiber-containing resin layer, and a protective layer in this order on the roughened surface.

  In the cathode plate, at least a part of the non-immersed portion is roughened, and a plurality of resin layers are provided on the roughened surface, so that the insulating layer is formed in a range where the plurality of resin layers are formed. Can be given. The cathode plate can be subjected to metal electrolytic refining in the same manner as in the prior art. Further, the range provided with the insulating properties is a strong acid electrolyte, electrolysis heat, protector (resin formed on the side edge). ) And the like, and with excellent strength, it is resistant to some impact and rubbing.

The cathode plate can be preferably manufactured by the method for manufacturing a cathode plate of the present invention.
Hereinafter, the cathode plate will be described together with the description of the cathode plate manufacturing method of the present invention.

<Method of manufacturing cathode plate>
The method for producing a cathode plate of the present invention includes at least a roughening step and a resin layer forming step for forming a plurality of resin layers, and further includes other steps as necessary.
There is no restriction | limiting in particular as said resin layer formation process, Although it can select suitably according to the objective, It includes a primer resin layer formation process, a silicon fiber containing resin layer formation process, and a protective layer formation process. preferable.

The range of the cathode plate in which the roughening step and the resin layer forming step are performed is not particularly limited as long as it is at least part of the non-immersed portion, and can be appropriately selected according to the purpose. The entire non-immersed part is preferred.
Here, the said non-immersion part means the range of the upper part of the liquid level of the said electrolyte solution of the said cathode plate.
The total thickness of the plurality of resin layers is not particularly limited and may be appropriately selected depending on the intended purpose, but is preferably about 0.1 mm to 0.5 mm.

<< Roughening process >>
The roughening step is a step of roughening at least a part of the surface of the non-immersed portion of the cathode plate.

-Cathode plate-
There is no restriction | limiting in particular as a shape, a structure, a magnitude | size, and a material of the said cathode plate, According to the objective, it can select suitably.
Examples of the shape of the cathode plate include a shape in which the length in the vertical direction when immersed in the electrolytic solution is longer than the length in the lateral direction orthogonal to the vertical direction. For example, the length is 1,000 mm or more, and the lateral length is 500 mm or more. Examples of the length of the non-immersed part in the vertical direction include 0 mm to 100 mm. The present invention is not affected by these dimensional lengths.
Examples of the thickness of the cathode plate include 6 mm.

The cathode plate has side edges that are attached to an edge insulating member at both ends in the lateral direction. The side edge portion may be subjected to the roughening step and the resin layer forming step. By performing the roughening step or the like on the side edge, it is possible to prevent metal from being deposited on the side edge even if the electrolyte enters the gap with the edge insulating member. By using the edge insulating member, the metal electrodeposited on the cathode plate can be prevented from being integrated so as to surround the edge of the cathode plate, and the electrodeposited metal can be easily peeled off.
There is no restriction | limiting in particular as a shape of the said side edge part, According to the objective, it can select suitably, For example, the shape whose shape of the liquid surface part vicinity of the said electrolyte solution is R shape is mentioned.
Examples of the range of the side edge include a length of 1,100 mm in the vertical direction and a length of 15 mm in the lateral direction.

  As a material of the cathode plate, a material generally used for electrolysis can be appropriately selected, and examples thereof include aluminum and an aluminum alloy. Among these, an aluminum alloy is preferable, and a 1000 series alloy is more preferable because it can be welded.

The cathode plate may be used for metal electrolytic refining or may be unused.
The cathode plate used for the metal electrolytic refining may be such that the thickness of at least a part of the non-immersed part is thinner than that of the immersed part immersed in the electrolytic solution.
When using the cathode plate used for the metal electrolytic refining, it is preferable that at least one end in the lateral direction of the non-immersed part is repaired with the material of the cathode plate, and both ends in the lateral direction of the non-immersed part are the cathode plate. More preferably, the material is repaired.
The repair means replacing the thickness of the thinned cathode plate with a material of the cathode plate that is thicker than at least the thickness after being thinned.

-Roughening-
The surface roughening method is not particularly limited and may be appropriately selected depending on the intended purpose. However, blasting is preferred because it does not affect electrodeposition and does not require a mask process.

In the blasting, hard particles are made to collide with the cathode plate with compressed air, roughen from the surface of the original cathode plate, and dirt and a deteriorated layer are removed. The blasting consists of sandblasting technology.
There is no restriction | limiting in particular as a medium used for the said blast, According to the objective, it can select suitably, For example, sand, an alumina powder (aluminum oxide powder), a metal particle, etc. are mentioned. The sand, alumina powder (aluminum oxide powder), and metal particles are preferable because they are suitable for the treatment of the cathode plate in terms of particle diameter and shape. Among these, alumina powder and sand which are inexpensive and can be processed with a relatively uniform surface are more preferable, and alumina powder is particularly preferable in that the surface of the cathode plate can be roughened and the medium is less consumed and easy to handle.
There is no restriction | limiting in particular as said sand, According to the objective, it can select suitably, For example, No. 4 silica sand, No. 5 silica sand (particle size: 300 micrometers-600 micrometers) etc. are mentioned.
There is no restriction | limiting in particular as said alumina powder, Although it can select suitably according to the objective, # 24 (particle size: 600 micrometers-710 micrometers) and # 100 (particle diameter: 106 micrometers-125 micrometers) are preferable.
There is no restriction | limiting in particular as surface roughness after the said roughening, Although it can select suitably according to the objective, Arithmetic mean roughness Ra has desirable 3-30 micrometers.

  The method for controlling the degree of roughening is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include a method, a method for adjusting a medium discharge area, and a method for adjusting a medium discharge time. These methods may be used alone or in combination of two or more.

  The range of roughening of the cathode plate may be only the non-immersed part or may include an immersed part.

Since the media such as sand may adhere to the cathode plate after the blasting treatment, it is preferable to perform a cleaning process.
There is no restriction | limiting in particular as said washing | cleaning method, According to the objective, it can select suitably, For example, the washing | cleaning by air, the washing | cleaning by water, the washing | cleaning by a dilute acid etc. are mentioned.

<< Resin layer forming process >>
The resin layer forming step is a step of forming the plurality of resin layers in a laminate on the roughened surface. The resin layer is a multiple layer composed of two or more layers.
The material of the resin layer may be a resin of the same material, or may be a material in which additive components are changed in each layer. By forming and laminating layers according to the respective desired characteristics such as adhesion, heat conduction, wear resistance and the like for each layer, a highly functional layer can be integrally formed.
As the resin, a resin whose function can be adjusted by an additive or the like as described above may be used, and it is desirable that the resin is the same resin in each layer. This is because the physical properties and the like should be the same when laminated.

-Primer resin layer formation process-
The primer resin layer forming step is a step of forming a primer resin layer on the roughened surface.
The primer resin layer serves as a base layer and can improve the adhesion of a silicon fiber-containing resin, which will be described later, to the cathode plate.

-Primer resin layer-
The primer resin layer contains at least a resin and further contains other components as necessary.

---- Resin ---
There is no restriction | limiting in particular as said resin, Although it can select suitably according to the objective, Vinyl ester-type resin is preferable. These may be used individually by 1 type and may use 2 or more types together.

--- Other ingredients ---
There is no restriction | limiting in particular as said other component, unless the effect of this invention is impaired, It can select suitably according to the objective, For example, an inorganic powder, a hardening | curing agent, an accelerator, etc. are mentioned.

--Formation method--
There is no restriction | limiting in particular as a formation method of the said primer resin layer, According to the objective, it can select suitably, For example, the method of apply | coating with a spray, the method of applying with a brush etc. are mentioned. Among these, the method of applying with a brush is preferable because it is thick and can be applied uniformly.

There is no restriction | limiting in particular as an application quantity of the coating liquid of the said primer resin layer, According to the objective, it can select suitably, For example, 0.2 kg / m < ² > etc. are mentioned.

  There is no restriction | limiting in particular as thickness of the said primer resin layer, According to the objective, it can select suitably.

  The range for forming the primer resin layer may be the entire roughened surface, or only the non-immersed portion on the roughened surface.

-Silicon fiber-containing resin layer forming step-
The silicon fiber-containing resin layer forming step is a step of forming a resin layer containing silicon fibers on the surface of the primer resin layer.
Since the silicon fiber-containing resin layer contains silicon fiber, the silicon fiber-containing resin layer can be prevented from peeling off from the cathode plate due to a difference in thermal expansion at the temperature of the electrolytic solution in metal electrolytic refining described later.

--Silicon fiber-containing resin layer--
The silicon fiber-containing resin layer contains at least silicon fiber and a resin, and further contains other components as necessary.

--- Silicon fiber ---
There is no restriction | limiting in particular as said silicon fiber, According to the objective, it can select suitably, For example, glass flakes etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.

---- Resin ---
There is no restriction | limiting in particular as said resin, Although it can select suitably according to the objective, Vinyl ester-type resin is preferable. These may be used individually by 1 type and may use 2 or more types together.

--- Other ingredients ---
There is no restriction | limiting in particular as said other component, unless the effect of this invention is impaired, It can select suitably according to the objective, For example, a hardening | curing agent etc. are mentioned.

--Formation method--
There is no restriction | limiting in particular as a formation method of the said silicon fiber containing resin layer, According to the objective, it can select suitably, For example, the method of applying with a spray, the method of applying with a brush, etc. are mentioned. Among these, the method of applying with a brush is preferable because it is thick and can be applied uniformly.

The coating amount of the coating liquid of the silicon fiber-containing resin layer is not particularly limited and may be appropriately selected depending on the intended ^purpose. Examples thereof include 1.6kg / ^{m 2} ~1.8kg / m 2 .

  There is no restriction | limiting in particular as thickness of the said silicon fiber containing resin layer, According to the objective, it can select suitably.

-Protective layer formation process-
The protective layer forming step is a step of forming a protective layer on the surface of the silicon fiber-containing resin layer.
The protective layer is a layer that protects the silicon fiber-containing resin layer.

--Protective layer--
The protective layer contains at least silica and a resin, and further contains other components as necessary.

--- Silica ---
There is no restriction | limiting in particular as said silica, According to the objective, it can select suitably. These may be used individually by 1 type and may use 2 or more types together.

  As content of the said silica in the said protective layer, 1 mass%-3 mass% are preferable as solid content.

---- Resin ---
There is no restriction | limiting in particular as said resin, Although it can select suitably according to the objective, Vinyl ester-type resin is preferable. These may be used individually by 1 type and may use 2 or more types together.

--- Other ingredients ---
The other components are not particularly limited as long as the effects of the present invention are not impaired, and can be appropriately selected according to the purpose. Examples thereof include a curing agent and paraffin.

--Formation method--
There is no restriction | limiting in particular as a formation method of the said protective layer, According to the objective, it can select suitably, For example, the method of apply | coating with a spray, the method of applying with a brush etc. are mentioned. Among these, the method of applying with a brush is preferable because it is thick and can be applied uniformly.

The coating amount of the coating liquid of the protective layer is not particularly limited and may be appropriately selected depending on the intended ^purpose. Examples thereof include ^{1.6kg / m 2 ~1.8kg / m 2} .

  There is no restriction | limiting in particular as thickness of the said protective layer, According to the objective, it can select suitably.

-Other processes-
There is no restriction | limiting in particular as said other process, unless the effect of this invention is impaired, It can select suitably according to the objective, For example, a removal process and a welding process are mentioned.
By performing the removing step and the welding step, it is possible to repair the non-immersed portion of the cathode plate that has been thinned and corroded by use. As the cathode plate of the present invention, the repaired cathode plate can also be used.

-Removal process-
The removing step is a step of removing at least a part of the non-immersed portion of the cathode plate.
In the cathode plate, the thickness of the non-immersed part that is not immersed in the electrolytic solution is thinner than the thickness of the immersed part that is immersed in the electrolytic solution, and at least a part of the thinned part is removed in the removing step. Remove.

The range of removal of the cathode plate may be one end of the non-immersed part of the cathode plate or both ends, but both ends can be increased in that the apparent strength of the entire cathode plate can be increased. Is preferred.
The central part of the cathode plate may not be removed.
As a removal range in the lateral direction of the cathode plate, a range including all cracks (usually about 50 mm) generated by thinning of the cathode plate may be removed, or an end portion of the crack (cathode plate) You may remove the range which left the center side.
The removal range in the vertical direction of the cathode plate can be selected as appropriate according to the wear of the side edge, but is preferably above the upper end of the side edge.

There is no restriction | limiting in particular as said removal method, According to the objective, it can select suitably, For example, a normal cutting tool is mentioned.
Specific examples of the cutting tool include a commercially available metal cutter, press, and fusing machine. These may be used individually by 1 type and may use 2 or more types together.

--Replenishment process--
The filling step is a step of filling the removed part with the material of the cathode plate.
There is no restriction | limiting in particular as a method of filling a cathode plate in the said removed part, According to the objective, it can select suitably, For example, welding, adhesion | attachment, riveting, etc. are mentioned.

  The material of the cathode plate to be supplemented is not particularly limited and can be appropriately selected depending on the purpose, but it is preferable to use a homogeneous material. For example, the cathode plate that has become scrap can be used.

  There is no restriction | limiting in particular as the said welding method, A normal arc welding method can be selected suitably.

  The cathode plate of the present invention can be easily repaired even when the silicon-containing resin layer is peeled off by use. That is, the silicon-containing resin layer and the like are once peeled off by the blasting process used in the roughening step, and then the primer resin layer forming step, the silicon fiber-containing resin layer forming step, and the protective layer forming step are performed. As a result, the cathode plate can be repaired and reused.

(Metal electrolytic refining method)
The cathode plate of the present invention can be used as it is in a conventional metal electrolytic refining method. Since there is no need to change special conditions, it can be used while being mixed with a conventional cathode plate. In addition, it is not necessary to change the specifications and settings of the device for stripping the electrodeposited metal from the cathode and the cathode transport and storage device. For this reason, the cathode plate can be used from one sheet, and the effect can be obtained on the same day without waiting for a period of total replacement of the conventional cathode plates in large quantities.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
The cathode plate 31 shown in FIGS. 1 and 2 was produced as follows.

<Preparation of electrode plate>
An aluminum alloy was used as the electrode plate 33. The electrode plate has a vertical length of 1,500 mm or less, a horizontal length of 1,000 mm or less, and a thickness of 6 mm. The electrode plate has side edges 35 at both lateral ends.
In FIG. 1, 32 indicates a head bar, and 34 indicates a contact point with the bus bar.

<Roughening process>
A portion 37 (hereinafter sometimes referred to as a “corrosion resistant portion”) located above the side edge portion of the electrode plate 33 was subjected to sand blasting treatment to roughen the surface. In addition, the said corrosion-resistant part also has a side surface. The surface roughness after the roughening was an arithmetic average roughness Ra of 24 μm.
-Sand blasting-
Abrasive: Alumina (White Alundum) # 24 (Fuji Seisakusho)
Blast air pressure: 0.5 MPa

  A resin layer was laminated on the roughened corrosion-resistant part using a commercially available resin paint. The resin layer had a three-layer structure of a primer resin layer as a base, a silicon fiber-containing resin layer, and a protective layer.

<Primer resin layer forming step>
The following primer resin layer coating solution was applied to the roughened corrosion-resistant part by brush coating. The coating amount was 0.2 kg / m ² .
The primer resin layer coating solution uses a resin composed of bisphenol vinyl ester, styrene, and methacrylic acid as a primer resin, and is mixed with magnesium silicate powder, using a curing agent (MEKPO) and an accelerator. .
In addition, after application | coating, it was left for several tens of minutes and dried.

<Silicon fiber-containing resin layer forming step>
The following silicon fiber-containing resin layer coating solution was applied to the corrosion-resistant portion where the primer resin layer was formed by brush coating. The coating amount ^was set to ^{1.6kg / m 2 ~1.8kg / m 2} .
The silicon-containing resin layer coating solution is a resin containing a bisphenol-based vinyl ester, styrene, glass flake, or other inorganic material as a silicon-containing resin, and a curing agent (MEKPO) is used for the resin.
In addition, after application | coating, it was left for several tens of minutes and dried.

<Protective layer forming step>
The following protective layer coating solution was applied by brushing to the corrosion-resistant part where the silicon fiber-containing resin layer was formed. The coating amount ^was set to ^{1.6kg / m 2 ~1.8kg / m 2} .
As the silicon fiber-containing resin, the protective layer coating solution is made of bisphenol vinyl ester, styrene, or other inorganic material, and a curing agent (MEKPO) is used for this.
In addition, after application | coating, it was left to stand for several hours and dried.

  Corrosion-resistant portions with the thickness of the three layers being 0.3 mm are formed on the surface of the roughened electrode plate by the primer resin layer forming step, the silicon fiber-containing resin layer forming step, and the protective layer forming step, and the cathode plate 1 was produced.

The cathode plate 1 laminated with the resin can be used in an electrolytic cell in a normal zinc refining process. An electrolytic solution containing a desired metal, an anode plate, and a cathode plate are disposed in the electrolytic cell, and zinc is electrolytically deposited on the cathode plate by energizing each electrode.
The electrolyte includes an electrolyte containing sulfuric acid, zinc, manganese, etc., the anode plate is a lead-silver anode plate, and the cathode plate is the cathode plate 1 (aluminum cathode laminated with resin). Was used.
The conditions for electrolysis and the like were the same as in the past. Since there is no special condition for the cathode plate of the present invention, even if the cathode plate 1 and the conventional cathode plate are used together in the same battery case, the production conditions of the electrolysis and the metal quality are affected. There was no.
It was found that the cathode plate 1 can be stored, managed, and handled in the same way as a conventional cathode plate, and no new management change or addition of equipment is required.

(Example 2)
<Preparation of electrode plate>
The electrode plate was the same as Example 1 except that an electrode plate used for metal electrolytic refining and cracked due to corrosion and thinning was used.
FIG. 4 is a schematic view showing the cathode plate after being used for metal electrolytic refining.

<Removal process>
A portion 51 including a crack in the electrode plate 33 of the cathode plate used for the metal electrolytic refining was removed with a metal cutter. The removed range was the upper ends of the electrode plate, 50 mm from the top of the electrode plate, and 50 mm from the lateral end.

<Compensation process>
An aluminum alloy (A1000 series) made of the same material as the electrode plate was repaired by welding at the place removed in the removing step.
FIG. 5 shows a schematic front view of the cathode plate after compensation.

<Roughening process>
In order to form a corrosion-resistant portion in the same range as in Example 1 using the cathode plate after the welding process, first, sandblasting was performed to roughen the surface. The sandblast treatment was performed in the same manner as in Example 1.

<Primer resin layer forming step>
A primer resin layer was formed on the roughened corrosion-resistant portion in the same manner as in Example 1.

<Silicon fiber-containing resin layer forming step>
In the same manner as in Example 1 above, a silicon fiber-containing resin layer was formed on the corrosion-resistant portion where the primer resin layer was formed.

<Protective layer forming step>
A protective layer was formed in the same manner as in Example 1 on the corrosion-resistant part where the silicon fiber-containing resin layer was formed.

  Corrosion-resistant portions with the thickness of the three layers being 0.3 mm are formed on the surface of the roughened electrode plate by the primer resin layer forming step, the silicon fiber-containing resin layer forming step, and the protective layer forming step, and the cathode plate 2 was produced.

In the electrolytic cell of Example 1, the conventional cathode plate, the cathode plate of Example 1 and the cathode plate of Example 2 were used while mixed in the same cell. The product quality and equipment were not abnormal.
In addition, the produced zinc was 100 t or more, and there was no problem even when it was used for 3 months or more.

  From the results of Examples 1 and 2, it was found that the cathode plate of the present invention can be manufactured at low cost. Moreover, since it has a corrosion-resistant part, since it can endure the corrosion by the sulfuric acid mist contained in electrolyte solution, it turned out that it can be used for a long period of time. Furthermore, it has been found that it is possible to use a cathode plate which has been thinned and corroded by use. Further, the corrosion-resistant part can be easily repaired by blasting.

  The cathode plate of the present invention can be manufactured at a low cost, can be used for a long period of time, can be easily repaired, and a cathode plate that is thinned and corroded by use can also be used. Therefore, it is suitably used for a metal electrolytic refining method.

1 Corrosion and reduced thickness 31 Cathode plate 32 Head bar 33 Electrode plate 34 Contact with bus bar 35 Side edge 37 Corrosion resistant part 51 Removal range 101 Repaired part

Claims (6)

A cathode plate used for metal electrolytic refining,
At least a part of the surface of the non-immersed part that is not immersed in the electrolyte solution of the cathode plate is roughened,
A cathode plate comprising a plurality of resin layers comprising a primer resin layer, a silicon fiber-containing resin layer, and a protective layer on the roughened surface.   The cathode plate according to claim 1, wherein the thickness of at least a part of the non-immersed part is thinner than that of the immersed part immersed in the electrolytic solution.   The cathode plate according to claim 2, wherein at least one end in the lateral direction of the non-immersed portion is repaired with a material of the cathode plate. A method for producing a cathode plate according to any one of claims 1 to 3,
A roughening step of roughening at least part of the surface of the non-immersed portion of the cathode plate;
A primer resin layer forming step of forming a primer resin layer on the roughened surface;
A silicon fiber-containing resin layer forming step of forming a resin layer containing silicon fibers on the surface of the primer resin layer;
A protective layer forming step of forming a protective layer on the surface of the silicon fiber-containing resin layer;
A method for producing a cathode plate, comprising:   The method for manufacturing a cathode plate according to claim 4, wherein the roughening step is performed by sandblasting.   A metal electrolytic refining method comprising using at least one cathode plate according to any one of claims 1 to 3 as a cathode electrode.