JP6760191B2 - Manufacturing method of specially shaped electrodeposition - Google Patents

Description

The present invention relates to a method for producing a specially shaped electrodeposited object. More specifically, the present invention relates to a method for producing a specially shaped electrodeposition by electrolytic refining using a mother plate whose surface is masked with an insulating material as a cathode, and a method for reducing connection defects in which adjacent electrodepositions are connected.

In electrowinning of nickel and the like, a base plate of a metal different from the target metal and a material that can be used repeatedly is used as a cathode, and after electrolysis for a predetermined time, the electrodeposit is peeled off from the base plate and recovered. The method is commonly practiced. At this time, by masking the mother plate with an insulating material, an electrodeposited material having an arbitrary special shape can be obtained.

For example, nickel electroplating used as an anode for plating is preferably in the shape of a small lump with no corners and rounded from the viewpoint of filling property and handleability in the anode box of the plating apparatus. In order to produce such small lumps of electrolytic nickel by electrowinning, it is possible to electrolyze using a master plate that masks the insulator, leaving a large number of circular electrodeposited parts (portions where nickel is electrodeposited). (For example, Patent Document 1).

JP-A-2002-302787

In the production of the specially shaped electrodeposite as described above, a shape defect may occur in which the shape of the manufactured electrodeposit is not the desired shape. Electrodepositions with poor shape do not meet quality standards and cannot be manufactured. Therefore, there is a problem that the yield is lowered when the shape defect occurs.

Therefore, it is possible to reduce shape defects by managing the number of years of use of the mother plate, which is conventionally used as a cathode, and replacing the one that has passed the predetermined number of years of use (usually 3 to 4 years) with a new one. Was there. However, in recent years, there has been a demand for further reduction of shape defects.

In view of the above circumstances, an object of the present invention is to provide a method for manufacturing a specially shaped electrodeposited object, which can reduce the poorly connected electrodeposited objects which are adjacent to each other.

The method for producing a specially shaped electrodeposited object of the first invention uses a masking step of masking the surface of a master plate constituting a cathode with an insulator leaving a plurality of electrodeposited portions having a predetermined shape, and the masked cathode. An electrolytic smelting step of performing electrolytic smelting to obtain an electrodeposition, an insulator removing step of removing the insulating material from the master plate of the cathode after being used in the electrolytic smelting step, and the insulating material removing. After the step, the step includes a measuring step of measuring the thickness difference of the base plate, and a replacement step of replacing the cathode with a new one and supplying it to the masking step when the thickness difference exceeds the threshold value. It is characterized by that.
In the method for producing a specially shaped electrodeposited object of the second invention, in the first invention, the thickness of a plurality of points of the base plate is measured in the measuring step, and the difference between the maximum value and the minimum value of the measured values is the thickness. It is characterized by making a difference.
The method for producing a specially shaped electrodeposited object of the third invention is characterized in that, in the first invention, the thickness difference is measured by using an apparatus capable of measuring the total thickness of the base plate in the measuring step.
In the method for manufacturing a specially shaped electrodeposited object of the fourth invention, in the first invention, the threshold value is set as a thickness difference which is a target connection failure rate by obtaining a relationship between the thickness difference and the connection failure rate in advance. It is characterized by.
In the method for producing a specially shaped electrodeposited object of the fifth invention, in the first invention, the set value of the shortest distance between adjacent electrodeposited objects after the completion of electrolytic refining is 2 mm or more and 4 mm or less, and the threshold value is 0. It is characterized in that it is 5.5 mm or more and 1 mm or less.

According to the present invention, the base plate, which is prone to poor connection, can be replaced with a new one by determining the cathode replacement time using the difference in thickness of the base plate as an index. As a result, poor connection can be reduced.

It is a manufacturing flow chart of the manufacturing method of the special shape electrodeposite which concerns on one Embodiment of this invention. It is a front view of a cathode. It is an enlarged view of the part A in FIG. It is a graph which shows the relationship between the thickness difference of a base plate and the connection failure rate. It is explanatory drawing of the distance between a cathode and an anode.

Next, an embodiment of the present invention will be described with reference to the drawings.
A method for manufacturing a specially shaped electrodeposited object according to an embodiment of the present invention will be described based on the manufacturing flow shown in FIG. The production method of the present embodiment is a method of obtaining a small lump-shaped electrodeposition of nickel. The manufacturing method of the present embodiment includes a masking step, an electrolytic refining step, a stripping step, an insulator removing step, a measuring step, and a replacement step. Hereinafter, they will be described in order.

(Masking process)
In the masking step, the surface of the base plate is masked with an insulator against the cathode used for electrolytic refining. As shown in FIG. 2, the cathode 1 is composed of a square master plate 11 made of stainless steel or titanium, a beam 12 made of copper, and a ribbon 13 connecting the master plate 11 and the beam 12. The ribbon 13, the mother plate 11, and the beam 12 are fixed by welding.

An insulating material (insulating resin) 14 is applied to both the front and back surfaces of the main plate 11 by using a masking device that performs screen printing. At this time, a plurality of electrodeposited portions 15 having a predetermined shape are left on the surface of the mother plate 11. In electrolytic refining, nickel is electrodeposited only on the electrodeposited portion 15, so that small-lumped electrolytic nickel can be obtained.

In the example shown in FIG. 2, the mother plate 11 is masked by a pattern in which a large number of circular electrodeposition portions 15 are arranged in a staggered pattern. As shown in FIG. 3, for example, the diameter φ ₁ of the electrodeposited portion 15 is 12 to 15 mm. The shortest distance (distance between the 14 portions of the insulator) D ₁ of the adjacent electrodeposited portions 15 is 5 to 6 mm. The thickness of the insulator 14 is about 0.5 mm.

The shape of the electrodeposited portion 15 is not limited to a circle, and may be another shape such as an ellipse or a rectangle. As the shape of the electrodeposited portion 15, various shapes are adopted according to the shape of the target electrodeposited object.

(Electrorefining process)
In the electrolytic refining step, electrolytic refining is performed using the cathode 1 masked in the masking step to obtain an electrodeposited product. Specifically, a plurality of cathodes 1 and a plurality of anodes 2 are alternately inserted into an electrolytic cell 3 filled with an electrolytic solution, and electrolysis is performed by energizing. For example, in the case of nickel electrowinning, an insoluble electrode provided with an anode box is used as the anode 2. An aqueous nickel chloride solution is used as the electrolytic solution, and this is continuously supplied to the electrolytic cell 3. By energizing for a predetermined time (for example, 2 weeks), small lumps of electrolytic nickel are electrodeposited on the electrodeposited portion 15 of the cathode 1.

The electrodeposited material electrodeposited on the electrodeposited portion 15 grows to the thickness of the insulating material 14, and then grows in both directions perpendicular to the base plate 11 and parallel to the base plate 11. That is, the electrodeposited material grows beyond the range of the electrodeposited portion 15 to the region where the insulating material 14 is applied. When the shape of the electrodeposited portion 15 is circular, the electrodeposited object grows into a button shape in which the central portion is flat and the peripheral portion is raised.

Electrorefining is operated under the condition that the electrodeposited material grows to the target size. Specifically, operating conditions such as the composition of the electrolytic solution, the current value between the anode and the cathode, and the energization time are set so that the electrodeposited object grows to the target size. As shown in FIG. 3, for example, electrodeposit 16 after the electrolytic refining is completed, the diameter φ ₂ 16~19mm, a button type having a thickness of about 5 mm.

The target dimensions of the electrodeposits 16 are set so that adjacent electrodepositions 16 do not come into contact with each other. For example, the shortest distance D ₂ between adjacent electrodepositions 16 after the completion of electrolytic refining is set to ₂ to 4 mm. In other words, the operating conditions are set so that the shortest distance D ₂ between adjacent electrodeposition objects 16 becomes the above set value.

The electrodeposition is not limited to nickel, and electrodepositions of other metals such as cobalt may be obtained. Further, the present invention is not limited to electrowinning, and may be electrorefining.

(Peeling process)
After energizing for a predetermined time, the cathode 1 is removed from the electrolytic cell 3. In the stripping step, the cathode 1 is vibrated by a method such as hammering to strip the electrodeposited material electrodeposited on the cathode 1. The electrodeposited material stripped from the cathode 1 is polished, washed, and dried to become a product.

The cathode 1 from which the electrodeposition has been stripped is reinserted into the electrolytic cell 3 and subjected to electrolytic refining. That is, the cathode 1 is repeatedly used in the electrolytic refining step and the stripping step. When the cathode 1 is used repeatedly, the insulator 14 coated on the cathode 1 deteriorates and peels off. Therefore, in order to reapply the insulating material 14, the cathode 1 in which the insulating material 14 has deteriorated is sent to the insulating material removing step.

(Insulation removal process)
In the insulator removing step, the cathode 1 after being repeatedly used in the electrolytic refining step is subjected to a process of removing the insulator 14 from the base plate 11. The removal of the insulator 14 is performed, for example, by a blast treatment. The cathode 1 from which the insulator 14 has been removed is supplied to the masking step through a measurement step and a replacement step described later. The cathode 1 is masked again and subjected to electrolytic refining.

In the method for manufacturing a specially shaped electrodeposite as described above, a shape defect may occur in which the shape of the manufactured electrodeposit is not the desired shape. There are various defects in shape, and one of them is a poor connection. The connection failure means a failure in which adjacent electrodeposites are connected to each other on the cathode 1.

The inventor of the present application focused on the relationship between the difference in thickness of the mother plate 11 after removing the insulating material 14 and the occurrence rate of connection defects (connection failure rate), and conducted the test. The test was carried out under the following conditions in the above-mentioned manufacturing method (excluding the measurement step and the replacement step).
Material of cathode base plate: Stainless steel Main plate dimensions of electrolytic solution immersion part: 830 mm wide, 1,090 mm long
Thickness of mother plate when new: 5 mm
Insulation thickness: 0.5 mm
Shape of electrodeposited part: Circular with a diameter of 15 mm Arrangement of electrodeposited part: Approximately 2,300 pieces are arranged in a staggered pattern on one side of the main plate. Shortest distance between adjacent electrodeposited parts: 6 mm
The operating conditions of the electrolytic smelting are set so that the diameter of the electrodeposition after the completion of the electrolytic smelting is 17 to 19 mm, that is, the shortest distance between adjacent electrodepositions after the completion of the electrolytic smelting is 2 to 4 mm. Has been done.

Twenty of the cathodes 1 extracted from the electrolytic cell 3 after the electrolytic refining were selected, and the connection failure rate and the thickness difference of the mother plate 11 were measured for each of them. The number of years of use of the selected cathode 1 varies (0 to 3 years).

The connection failure rate was obtained from the electrodeposited material obtained in the stripping step based on the following mathematical formula (1).
r = w _f / w _g ... (1)
Here, r is the connection failure rate per mother plate, w _f is the weight of the poorly connected electrodeposited material generated by one mother plate, and w _g is the total weight of the electrodeposited material obtained from one mother plate. Is.

The difference in thickness of the mother plate 11 means the non-uniformity of the thickness of the mother plate 11, and is represented by the difference between the thickness of the thickest portion and the thickness of the thinnest portion of the mother plate 11. The thickness difference of the base plate 11 was measured by the following procedure. About 50 mm inward from both the left and right edges of the mother plate 11 after removing the insulator 14 in the insulator removing step, and from the upper end to the lower end of the electrolytic solution immersion portion, 7 at equal intervals. The thickness of the position was measured with a dial gauge. The difference between the maximum value and the minimum value among the measured values at 14 points in total was defined as the "thickness difference".

As a result, the graph shown in FIG. 4 was obtained. From the graph of FIG. 4, it can be seen that there is a positive correlation between the thickness difference of the base plate 11 and the connection failure rate. By fitting the obtained measurement points with a quadratic function, a relational expression between the difference in thickness of the base plate and the poor connection rate was obtained. The inventor of the present application has obtained the idea of reducing the connection failure rate to a target value by determining the replacement time of the cathode 1 using this relational expression as a management index.

(Measurement process)
Returning to FIG. 1, a method for manufacturing a specially shaped electrodeposited object will be described.
After the insulating material removing step, the cathode 1 from which the insulating material 14 has been removed is sent to the measuring step. In the measuring step, the thickness difference of the base plate 11 is measured. The method for measuring the thickness difference is not particularly limited, but as described above, the thickness of the base plate 11 at a plurality of locations may be measured, and the difference between the maximum value and the minimum value of the measured values may be defined as the thickness difference. Here, the measurement position of the thickness and the number thereof are not particularly limited. Further, the thickness difference may be obtained by using a device such as a film pressure measuring device that can measure the entire thickness of the base plate 11.

(Replacement process)
The cathode 1 having a thickness difference within the threshold value obtained in the measurement step is directly supplied to the masking step and used repeatedly. When the thickness difference obtained in the measurement step exceeds the threshold value, the cathode 1 is replaced with a new one and supplied to the masking step.

Here, the "threshold value" is set as a thickness difference that is a target connection failure rate after obtaining the relationship between the thickness difference and the connection failure rate in advance by the procedure as described above. The "connection failure rate" here means the connection failure rate of all electrodeposited materials obtained during a specific operation period, and is defined by the following mathematical formula (2).
R = W _f / W _g ... (2)
Here, R is the poor connection rate of all electrodeposited materials obtained in a specific operating period, W _f is the weight of all poorly connected electrodepositions generated in a specific operating period, and W _g is all obtained in a specific operating period. The total weight of the electrodeposited material.

The connection failure rate r per mother plate, which is the measurement point in the graph of FIG. 4, was obtained for all the mother plates used in a specific operation period, and when they were averaged, the connection failure rate of all electrodeposits was obtained. It becomes R. It is considered that the connection failure rate R of all electrodeposited materials is substantially equal to the value obtained by the relational expression obtained by fitting in the graph of FIG. That is, the connection failure rate R of all electrodeposited objects can be estimated from the relational expression obtained by fitting in the graph of FIG.

For example, in the example shown in FIG. 4, when the target value of the connection failure rate is 1.6%, the threshold value may be set to 1.0 mm. When the target value of the connection failure rate is 0.9%, the threshold value may be set to 0.8 mm. The lower the target value of the connection failure rate is set, the shorter the period of use of the cathode 1 and the higher the frequency of replacement. Therefore, it is preferable to set the target value of the connection failure rate in a balance between the cost of replacing the cathode 1 and the loss due to the connection failure.

The specific relationship between the thickness difference and the poor connection rate is considered to depend on the set value of the shortest distance D ₂ between adjacent electrodeposition objects after the completion of electrolytic refining. This is because the poor connection is caused by the electrodeposition material growing larger than usual and coming into contact with the adjacent electrodeposition material. Therefore, when the set value is 2 to 4 mm and the threshold value is 1.0 mm or less, the connection failure rate can be suppressed to 1.6% or less. Further, if the threshold value is 0.8 mm or less, the connection failure rate can be suppressed to 0.9% or less.

Even with the new cathode 1, there is a slight difference in thickness of the mother plate 11. Therefore, the threshold value is preferably at least this initial thickness difference or more, for example, 0.5 mm or more.

As described above, by determining the replacement time of the cathode 1 using the difference in thickness of the base plate 11 as an index, the base plate 11 in which poor connection is likely to occur can be replaced with a new one. As a result, poor connection can be reduced.

The reason why there is a relationship as shown in FIG. 4 between the thickness difference of the base plate 11 and the connection failure rate is not clear, but the inventor of the present application speculates as follows.
The mother plate 11 becomes thinner as the period of use elapses. It is considered that the main cause of the thinning of the base plate 11 is the blasting process in the insulating material removing step. The blasting process is performed by spraying the blasting material onto the base plate 11. When the blast material collides with the base plate 11, the base plate 11 is worn and thinned.

Normally, the size of the mother plate 11 is about 1,000 mm square. A blast material is sprayed onto the mother plate 11 with a width of 100 to 300 mm. In order to spray the blasting material on the entire surface of the base plate 11, the blasting process is performed while reciprocating the nozzle for ejecting the blasting material with respect to the base plate 11. At this time, there are areas where the blasting material is sprayed in an overlapping manner and areas where the blasting material is not sprayed, resulting in uneven wear of the mother plate 11. As a result, when the blasting process is repeated, the thickness of the mother plate 11 becomes uneven. That is, there is a difference in thickness.

As shown in FIG. 5, in electrolytic refining, the cathode 1 and the anode 2 are inserted into the electrolytic cell 3 in parallel with a predetermined gap. In the case of a novel cathode 1 (dotted chain line in FIG. 5) in which the base plate 11 is not thinned, the distance L ₀ (for example, 40 to 50 mm) between the cathode 1 and the anode 2 is almost uniform regardless of the location. The operating conditions of the electrolytic refining are set so that the shortest distance D ₂ between adjacent electrodeposition objects after the completion of the electrolytic refining is the set value in this state.

It is assumed that the surface of the cathode 1 (solid line in FIG. 5) that has been used repeatedly has irregularities. In this case, the distance L ₁ between the convex portion of the cathode 1 and the anode 2 is shorter than the distance L ₂ between the concave portion of the cathode 1 and the anode 2. Then, the electric resistance between the convex portion of the cathode 1 and the anode 2 becomes relatively low, and the current density becomes high. On the contrary, the electric resistance between the recess of the cathode 1 and the anode 2 becomes relatively high, and the current density becomes low. As a result, the growth of the electrodeposit is relatively fast at the convex portion of the cathode 1, and the growth of the electrodeposition is relatively slow at the concave portion of the cathode 1.

In this way, the current is concentrated on the convex portion of the cathode 1, and the electrodeposited material grows large. If the electrodeposition becomes too large and comes into contact with the adjacent electrodeposition, the connection will be poor. The degree of unevenness on the surface of the base plate 11 is represented by the difference in thickness. The larger the thickness difference, the more likely the above phenomenon occurs. Therefore, a positive correlation occurs between the thickness difference of the mother plate 11 and the connection failure rate.

In the case of a new cathode 1 or a uniformly thinned cathode 1, the distance between the cathode 1 and the anode 2 is almost uniform depending on the location, so that the electrical resistance and the current density are almost uniform. is there. Therefore, the growth rate of the electrodeposited material does not vary, and poor connection is unlikely to occur.

Next, an embodiment will be described.
The common conditions in Examples 1 and 2 and Comparative Example 1 described below are as follows.
Material of cathode base plate: Stainless steel Main plate dimensions of electrolytic solution immersion part: 830 mm wide, 1,090 mm long
Thickness of mother plate when new: 5 mm
Insulation thickness: 0.5 mm
Shape of electrodeposited part: Circular with a diameter of 15 mm Arrangement of electrodeposited part: Approximately 2,300 pieces are arranged in a staggered pattern on one side of the main plate. Shortest distance between adjacent electrodeposited parts: 6 mm
The operating conditions (current value, energization time, etc.) of the electrolytic refining process are that the diameter of the electrodeposition after the completion of electrolytic refining is 17 to 19 mm, that is, the shortest distance between adjacent electrodepositions after completion of electrolytic refining is 2. It is set to be ~ 4 mm.

(Example 1)
An operation was carried out to obtain a specially shaped electric nickel by the manufacturing method shown in FIG. In the replacement step, the threshold was set to 1.0 mm.
When the connection failure rate R was calculated from all the electrodeposited materials obtained during the operation period of half a year, it was 1.6%.

(Example 2)
An operation was carried out to obtain a specially shaped electric nickel by the manufacturing method shown in FIG. In the replacement process, the threshold was set to 0.8 mm.
When the connection failure rate R was calculated from all the electrodeposited materials obtained during the operation period of half a year, it was 0.9%.

(Comparative Example 1)
An operation was carried out to obtain specially shaped nickel by the same method as the manufacturing method shown in FIG. 1, except for the measurement step and the replacement step. At this time, the cathode 1 which had been used for 3 years was replaced with a new one.
When the connection failure rate R was calculated from all the electrodeposited materials obtained during the operation period of half a year, it was 3.0%.

From the above, it was confirmed that the connection failure rate R can be reduced by determining the replacement time of the cathode 1 using the thickness difference of the mother plate 11 as an index.

1 Cathode 11 Mother plate 12 Beam 13 Ribbon 14 Insulation 15 Electroplated part 16 Electroplated object 2 Anode 3 Electrolytic cell

Claims (5)

A masking process in which the surface of the mother plate constituting the cathode is masked with an insulating material while leaving a plurality of electrodeposited portions having a predetermined shape.
The electrolytic refining process of obtaining an electrodeposite by performing electrolytic refining using the masked cathode, and
An insulator removing step of removing the insulator from the master plate of the cathode after being used in the electrolytic refining step.
After the insulation removal step, a measurement step of measuring the thickness difference of the base plate and a measurement step
A method for producing a specially shaped electrodeposited product, comprising: a replacement step of replacing the cathode with a new one and supplying the cathode to the masking step when the thickness difference exceeds a threshold value. The specially shaped electrodeposited material according to claim 1, wherein in the measuring step, the thicknesses of a plurality of locations of the base plate are measured, and the difference between the maximum value and the minimum value of the measured values is defined as the thickness difference. Production method. The method for manufacturing a specially shaped electrodeposited object according to claim 1, wherein in the measuring step, the thickness difference is measured using an apparatus capable of measuring the total thickness of the mother plate. The method for manufacturing a specially shaped electrodeposited object according to claim 1, wherein the threshold value is set as a thickness difference that is a target connection failure rate by obtaining a relationship between the thickness difference and the connection failure rate in advance. The set value of the shortest distance between the adjacent electrodeposited objects after the completion of electrolytic refining is 2 mm or more and 4 mm or less.
The method for producing a specially shaped electrodeposited object according to claim 1, wherein the threshold value is 0.5 mm or more and 1 mm or less.

Images