JP6540466B2 - Method of regenerating an electrowinning base plate - Google Patents

Description

  The present invention relates to a method of regenerating an electrowinning base plate. More particularly, the present invention relates to a method of regenerating an insulator-masked mother plate, and repainting the insulator to regenerate the mother plate.

  In electrowinning of a metal such as nickel, a base plate of a material different from the metal to be electrolysed and usable repeatedly is used as a cathode, and after electrolysis for a predetermined time, the electrodeposited material is pulled from the base plate The method of peeling and recovering is generally performed. At this time, by masking the base plate with an insulator, it is possible to obtain an electrodeposit having an arbitrary special shape.

  For example, in view of the filling property to the anode box of the plating apparatus, the handling property, etc., the electric nickel used as an anode for plating is preferably in the form of a small lump having no corners and having a rounded shape. In order to produce such small-scale electrodeposited nickel by electrowinning, electrolysis is carried out using a base plate masked with an insulator so as to have a large number of circular electrodeposited surfaces (portions where nickel is electrodeposited) on the surface. Is performed (e.g., Patent Document 1).

  After electrowinning using the insulator masked mother plate, vibration is applied to the mother plate to peel off the electrodeposit. Repeated electrowinning and stripping operations cause the insulator to deteriorate and gradually peel off part of the insulator together with the electrodeposited material. When the insulator peels off and the shape of the electrodeposition surface changes, an electrodeposit having a desired shape can not be obtained. Therefore, before the shape abnormality of the electrodeposition surface occurs due to the peeling of the insulator, it is necessary to repaint the insulator to regenerate the mother board.

Japanese Patent Laid-Open No. 2002-302787

  An object of the present invention is to provide an efficient method of regenerating an electrowinning base plate in view of the above-mentioned circumstances.

The method for regenerating an electrowinning base plate according to the first aspect of the present invention is a method for regenerating a base plate masked by applying an epoxy resin as an insulator, wherein the blast treatment removes the insulator from the base plate by blasting. And providing a process.
The method of regenerating an electrowinning base plate according to a second aspect of the present invention is characterized in that, in the first aspect, the abrasive used for the blast treatment is a ferronickel slag.
The method for regenerating an electrowinning base plate of the third invention is characterized in that, in the second invention, the grain size of the abrasive is 0.3 to 1.7 mm.

According to the first aspect of the present invention, the insulator can be efficiently removed by removing the insulator from the base plate by blasting.
According to the second aspect of the invention, since the abrasive is ferro-nickel slag, the free silica content of dust generated by blasting can be reduced, and the working environment can be improved.
According to the third invention, since the particle size of the abrasive is 0.3 to 1.7 mm, the life of the base plate after regeneration can be extended.

(A) A figure is a front view of a mother board before masking by an insulator, (B) A figure is a front view of a mother board after masking.

Next, an embodiment of the present invention will be described based on the drawings.
The method for regenerating an electrowinning base plate according to the present embodiment is a step of using a base plate masked with an insulator to obtain an electrodeposition of a special shape among the base plates used as a cathode in electrowinning of a metal such as nickel. It is a reproduction method. Hereinafter, a base plate used to obtain special shape of electric nickel will be described as an example.

(Mother board 1)
First, the mother board 1 will be described.
As shown in FIG. 1A, the base plate 1 is composed of a rectangular plate portion 11, a beam 12, and a ribbon 13 connecting the plate portion 11 and the beam 12. The ribbon 13 and the plate portion 11 and the beam 12 are fixed by welding. The beam 12 is an electrical contact for electrowinning and is also a support member for suspending the base plate 1 in the electrolytic cell. In the base plate 1 used for electrowinning nickel, the plate portion 11 and the ribbon 13 are made of stainless steel or titanium, and the beam 12 is made of copper.

  As shown in FIG. 1B, by applying the insulator 14 to the base plate 1, the plate portion 11 is masked in a pattern having a large number of circular electrodeposition surfaces 15. As the insulator 14, an insulating resin such as an epoxy resin is used.

  When electrowinning is performed using the mother plate 1 masked by the insulator 14 as a cathode and a nickel chloride solution as an electrolytic solution, nickel is electrodeposited only on the circular electrodeposition surface 15. After electrowinning, the base plate 1 is vibrated to peel off the electrodeposit (small lump of electric nickel). The mother plate 1 from which the electrodeposited material has been peeled off is again subjected to electrowinning. As described above, the electrowinning and stripping work are repeatedly performed using the base plate 1.

  When the electrowinning and stripping operations are repeated, the insulator 14 is deteriorated, and part of the insulator 14 is gradually removed along with the electrodeposited material. It is determined that such a mother board 1 has reached the end of its life, and is returned to the regeneration processing. The regenerated mother plate 1 is used again for electrowinning.

  Here, whether or not the life of the mother board 1 has expired is determined, for example, by the following method. The deteriorated insulator 14 adheres to the electric nickel and is peeled off from the base plate 1 together with the electric nickel. Then, the generation rate of the electric nickel which the insulator 14 adhered is confirmed for every production lot of electric nickel. Then, when the generation rate of the electric nickel to which the insulator 14 is attached exceeds 1%, it is determined that the life of the base plate 1 has expired.

  In the present specification, the lifetime of the mother plate 1 means the number of repetitions of the electrolytic extraction and stripping operation which is performed until the mother plate 1 after the regeneration treatment needs to be regenerated again.

(How to play)
Below, the reproduction | regeneration method of the mother board 1 is demonstrated.
The base plate 1 is regenerated by repainting the insulator 14 by performing (1) a blasting process, (2) a cleaning process, and (3) a masking process in this order.

(1) Blasting Step First, the insulator 14 is removed from the base plate 1 by blasting. Here, all the insulators 14 applied to the base plate 1 are removed. The method of blasting is not particularly limited. For example, the base plate 1 may be erected, and the discharge nozzle of the blasting device may be directed to the base plate 1 to discharge the abrasive. Moreover, the conditions of the blasting treatment are not particularly limited either, but for example, it is performed under the following conditions. The discharge pressure of the abrasive is 0.55 MPa. The distance between the discharge port of the abrasive and the base plate 1 is about 0.3 m, and the discharge direction of the abrasive is obliquely downward, and the approach angle to the base plate 1 is in the range of 20 to 30 °. The moving speed of the collision position of the abrasive is 1.0 m / min.

  As an abrasive used for blasting, ferro-nickel slag, silica sand, etc. can be used. Among these, it is preferable to use ferro-nickel slag. The reason for this will be described later. Here, the ferronickel slag is a grit abrasive material for blasting treatment in which the slag in the case of smelting nickel of boronickel, which is a silica-magnesia-iron oxide system, is pulverized in water or pulverized in air.

  Thus, the insulator 14 can be removed more efficiently than the other methods by removing the insulator 14 from the base plate 1 by blasting.

(2) Cleaning Step Next, the base plate 1 is washed with a shower or the like to remove dust attached to the base plate 1 by blasting. Then, the mother board 1 (see FIG. 1A) which is not masked by the insulator 14 is obtained.

(3) Masking process Finally, the insulator 14 is applied to the base plate 1 and masking is performed. Then, the mother board 1 (see FIG. 1B) masked with the insulator 14 is obtained.

(Abrasive)
By the way, when blasting is performed, the abrasive is crushed to generate dust, which is scattered to the work place. If blasting is performed in a closed space, scattering of dust to the work place can be suppressed. Even in this case, however, dust may leak as the base plate 1 is taken out, or dust may leak from the connection of the exhaust duct. Therefore, management of work environment is required.

The Occupational Safety and Health Act defines management categories based on work environment measurement as follows.
First control classification: It is estimated that the average concentration of harmful substances in air does not exceed the control concentration at most (95% or more) of the unit work area, and it is judged that the work environment management is appropriate .
Second control classification: It is estimated that the average concentration of harmful substances in air at the unit work place does not exceed the control concentration, but it is judged that there is room for improvement in work environment management compared to the first management classification. It is.
Third control classification: It is estimated that the average concentration of harmful substances in air at the unit work place exceeds the control concentration, and it is judged that work environment management is not appropriate.

In the case of dust of rock, rock, mineral, metal or carbon in the above definition, “control concentration” is defined by the following formula (1). Here, E is a control concentration [mg / m ³ ], and S is a free silica content of dust [%].
E = 3.0 / (1.19 × S + 1) (1)

  From equation (1), it can be seen that the lower the free silica content S of dust, the higher the control concentration E. As the control concentration E becomes higher, the work area control classification can be improved. For example, the work place of the third management division can be made the first management division.

Table 1 shows the chemical compositions of ferronickel slag and silica sand. From Table 1, it can be seen that the ratio of SiO ₂ is lower in ferronickel slag than in silica sand. Therefore, it can be inferred that the use of ferronickel slag as the grinding material can reduce the free silicic acid content of the dust as compared to the case of using silica sand.

  In fact, when the free silica content of dust generated by blasting was measured, the free silica content was 13% when ferronickel slag was used as an abrasive, and free when silica sand was used as an abrasive. The silica content was found to be 50 to 60%. That is, if ferro-nickel slag is used as a grinding material, the free silicic acid content of dust can be reduced compared with the case where siliceous sand is used. As a result, the control concentration can be increased and the control division of the work place can be improved.

  For the above reasons, the abrasive used for blasting is preferably ferronickel slag. If the abrasive is ferro-nickel slag, the free silica content of dust generated by blasting can be reduced, and the working environment can be improved.

Below, an Example is described.
(Common condition)
The regeneration process was performed on the mother board 1. The plate portion 11 of the base plate 1 is a stainless steel plate having a length of 1.1 m, a width of 0.8 m, and a thickness of 10 mm. Both surfaces of the plate portion 11 are masked by epoxy resin. The thickness of the resin is 1 mm. The electrodeposition surface 15 formed by masking is a circle with a diameter of 15 mm. The total number of electrodeposition surfaces 15 is 2021 in total on both sides of the plate portion 11. The base plate 1 is not a new product, and has been repeatedly subjected to an electrolytic extraction and stripping operation, and it is determined that the life has expired.

The conditions for blasting in the blasting process are as follows.
Blasting device: manufactured by NITCHU, part number DMH-100
Discharge pressure: 0.55MPa
Distance between discharge port and base plate: about 0.3 m
Ejection angle: 20 to 30 ° diagonally downward with respect to the upright base plate

Example 1
In the blasting step, ferronickel slag (particle size: 0.1 to 0.4 mm) was used as an abrasive. In addition, the moving speed of the collision position of the abrasive was 1.0 m / min. When 24 base plates were processed, 0 out of 24 base plates was able to remove the resin by the first blasting treatment. The resin of 16 mother boards in 24 sheets was able to be removed by the second blasting process. The remaining eight mother boards were able to remove the resin in the third blasting treatment.
The management category based on work environment measurement was the first management category.

  After the cleaning step and the masking step were performed to regenerate the mother plate, the mother plate was used for electrolytic collection. The life of the mother plate after the regeneration treatment was three times. That is, when electrolytic extraction and stripping work were repeated three times using the base plate after the regeneration treatment, the resin began to peel off.

  In Example 1, since ferro-nickel slag of fine particle size (0.1-0.4 mm) is used as a grinding material, in order to remove resin of all the mother boards, blast processing needed to be performed 3 times. Thus, it was found that the grinding force was weak in the ferronickel slag having a particle size of 0.1 to 0.4 mm.

(Example 2)
In the blasting step, ferro-nickel slag (particle size: 0.3 to 0.8 mm) was used as an abrasive. The remaining conditions are the same as in Example 1. When 52 base plates were processed, 35 out of 52 base plates were able to remove the resin by the first blasting treatment. The remaining 17 mother boards were able to remove the resin by blasting for the second time.
The management category based on work environment measurement was the first management category.

  After the cleaning step and the masking step were performed to regenerate the mother plate, the mother plate was used for electrolytic collection. The life of the mother plate after the regeneration treatment was three times.

  In Example 2, a ferronickel slag having a coarser particle size (0.3 to 0.8 mm) than that of Example 1 was used. As a result, it was possible to remove the resin of all the mother plates by double blasting. Thus, it has been found that the use of ferronickel slag having a particle size of 0.3 to 0.8 mm provides sufficient grinding power. However, in Examples 1 and 2, the lifetime of the mother plate after the regeneration treatment is three times, and there is a problem that the lifetime is short.

(Example 3)
In the blasting step, ferronickel slag (particle size: 0.3 to 1.7 mm) was used as an abrasive. The remaining conditions are the same as in Example 1. When 52 base plates were processed, 45 out of 52 base plates were able to remove the resin by the first blasting treatment. The remaining seven mother boards were able to remove the resin by blasting for the second time.
The management category based on work environment measurement was the first management category.

  After the cleaning step and the masking step were performed to regenerate the mother plate, the mother plate was used for electrolytic collection. The life of the mother board after the regeneration treatment was five times.

  In Example 3, a ferronickel slag having a grain size (0.3 to 1.7 mm) that is even coarser than that in Example 2 was used. Then, the life of the mother plate after the regeneration treatment was five times, and the life could be extended.

  From Examples 1 to 3, it was confirmed that the grain size of the abrasive is preferably 0.3 to 1.7 mm when using ferro-nickel slag as the abrasive. If it is a ferro-nickel slag of this particle size, the frequency | count of blasting can be reduced and not only operation efficiency is good, but the lifetime of the base plate after reproduction | regeneration can be extended.

  The reason why the life of the base plate after regeneration changes depending on the particle size of the ferronickel slag is considered to be as follows. When ferronickel slag is used as the abrasive, it is considered that dust of ferronickel slag remains on the surface of the base plate even after the cleaning step. If masking is performed in this state, the insulator is easily peeled off. If a coarse grain size (0.3 to 1.7 mm) ferronickel slag is used as the abrasive, the surface roughness of the base plate is increased, and the biting of the insulator onto the base plate is improved. As a result, it is considered that the life of the mother plate is extended.

(Example 4)
In the blasting step, silica sand (particle size: 0.07 to 0.6 mm) was used as an abrasive. The remaining conditions are the same as in Example 1.
The management classification based on work environment measurement was the third management classification.

  After the cleaning step and the masking step were performed to regenerate the mother plate, the mother plate was used for electrolytic collection. The life of the mother board after the regeneration treatment was five times.

  In Example 4, since silica sand was used as the abrasive, the management division became the third management division. In Examples 1 to 3 in which ferro-nickel slag is used as the abrasive, the management classification is the first management classification. From this, it was confirmed that the working environment can be improved if the abrasive is ferro-nickel slag.

(Example 5)
In the blasting step, the moving speed of the collision position of the abrasive was 1.5 m / min. The other conditions are the same as in Example 2. When 24 base plates were processed, 0 out of 24 base plates was able to remove the resin by the first blasting treatment. The resin of 17 mother boards in 24 sheets was able to be removed by the second blasting treatment. The remaining seven mother plates were able to remove the resin in the third blasting treatment.
The management category based on work environment measurement was the first management category.

  After the cleaning step and the masking step were performed to regenerate the mother plate, the mother plate was used for electrolytic collection. The life of the mother plate after the regeneration treatment was three times.

  In the fifth embodiment, the moving speed of the collision position of the abrasive is faster than that of the second embodiment. As a result, it was found that the number of blasting operations increased from 2 to 3 and the working efficiency was reduced.

(Example 6)
In the blasting step, the moving speed of the collision position of the abrasive was 0.6 m / min. The other conditions are the same as in Example 2. When 17 base plates were processed, 5 out of 17 base plates were able to remove the resin by the first blasting treatment. The remaining 12 mother boards were able to remove the resin by blasting for the second time.
The management category based on work environment measurement was the first management category.

  After the cleaning step and the masking step were performed to regenerate the mother plate, the mother plate was used for electrolytic collection. The life of the mother plate after the regeneration treatment was three times.

  In the sixth embodiment, the moving speed of the collision position of the abrasive is slower than that of the second embodiment. However, the number of times of blasting was two, and there was no change between Example 2 and Example 6. It was found that the working time is longer and the working efficiency is reduced because the moving speed of the collision position of the abrasive is reduced. From Examples 2, 5 and 6, it was confirmed that the moving speed of the impact position of the abrasive is 1.0 m / min.

Table 2 shows the conditions and results of Examples 1 to 6.
A: Ferro nickel slag (particle size: 0.1 to 0.4 mm)
B: Ferro nickel slag (particle size: 0.3 to 0.8 mm)
C: Ferro nickel slag (particle size: 0.3 to 1.7 mm)
D: Silica sand (particle size: 0.07 to 0.6 mm)

1 base plate 11 plate portion 12 beam 13 ribbon 14 insulator 15 electrodeposited surface

Claims (3)

A method of regenerating a mother board masked by applying an epoxy resin as an insulator,
A method for regenerating an electrowinning base plate, comprising a blasting step of removing an insulator from the base plate by blasting. The method for regenerating an electrowinning base plate according to claim 1, wherein the abrasive used for the blasting treatment is a ferronickel slag. The method for regenerating a base plate for electrolytic collection according to claim 2, wherein the particle size of the abrasive is 0.3 to 1.7 mm.