Circular vibrating sieve and powder sieving method

Abstract

To provide a circular vibration sieve machine capable of suppressing discharging of particles smaller than sieve openings of a sieve mesh as coarse powders, and a powder sieving method.SOLUTION: This powder sieving method comprises a step of sieving powder by using a circular vibration sieve machine. The circular vibration sieve machine includes a circular sieve mesh 40, a powder supply port for supplying powder to an upper surface of the sieve mesh 40, a discharge guide 41 provided in the upper surface of the sieve mesh, a sieve frame 30 that surrounds an outer periphery of the sieve mesh 40, a coarse power discharge port 53 formed in an upper part of the sieve frame 30, and a vibrator that vibrates the sieve mesh 40. The powder supply port is configured such that the most frequent position of a powder falling point is within a range of 0.4 r-0.6 r from a center O of the sieve mesh 40 to an outside, and an angle θ is within a range of 0-45°. The discharge guide 41 is a rod member having a length of 0.17 r-0.38 r and a base end provided at an edge of the coarse powder discharge port 53, and is tilted by 20-50° as a whole.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a circular vibrating sieve and a method for sieving powder, and more particularly to a circular vibrating sieve and a method for sieving powder using the circular vibrating sieve. [Background technology]

[0002] In the electrowinning of nickel and other metals, a metal plate made of a reusable material and different from the target metal is used as a cathode, and after electrolysis for a predetermined time, the electrodeposit is peeled off from the metal plate and recovered. In this case, by masking the surface of the metal plate with insulating resin except for the electrodeposit, electrodeposits of any special shape can be obtained.

[0003] A cathode (mother plate) made of a metal plate masked with insulating resin is repeatedly used for electrowinning. Repeated use of the mother plate gradually peels off the insulating layer formed by the insulating resin, resulting in an increased defect rate for the electrodeposit. When the defect rate exceeds a standard value, it is determined that the insulating layer has reached the end of its life, and the mother plate is reconditioned. The mother plate is reconditioned by removing all of the insulating layer on the surface of the mother plate by blasting, and then masking it with new insulating resin (Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2018-178212 Summary of the Invention [Problem to be solved by the invention]

[0005] After being used in the blasting process, the abrasive is collected and foreign matter is removed using a separator. The abrasive from which foreign matter has been removed is sent to a sieve and separated into fine powder and coarse powder. The fine powder is discarded, while the coarse powder is used again in the blasting process. This allows the abrasive to be reused, reducing the cost of new abrasive.

[0006] Blasting can be used to adjust the surface roughness of a metal plate to a predetermined level, thereby preventing the insulating layer from peeling off. The surface roughness of the metal plate can be adjusted by the particle size of the abrasive used in the blasting. Therefore, the mesh size of the sieve mesh installed in the sieve is set so that an abrasive with an appropriate particle size can be obtained.

[0007] However, particles smaller than the mesh size may remain on the sieve, resulting in the average particle size of the abrasive recovered as coarse powder being smaller than the target value, making it impossible to adjust the surface of the metal plate to the target roughness.

[0008] In view of the above circumstances, an object of the present invention is to provide a circular vibrating sieve that can prevent particles smaller than the mesh openings of the sieve screen from being discharged as coarse powder, and a method for sieving powder. [Means for solving the problem]

[0009] A circular vibrating sieve machine according to a first aspect of the present invention comprises a circular sieve screen, a powder supply port for supplying powder to an upper surface of the sieve screen, a discharge guide provided on the upper surface of the sieve screen, a sieve frame surrounding the outer periphery of the sieve screen, a coarse powder discharge port formed in the sieve frame above the sieve screen, a fine powder discharge port formed in the sieve frame below the sieve screen, and a vibrator for vibrating the sieve screen, wherein the radius of the sieve screen is defined as r, and the distance from the center of the sieve screen to the edge of the coarse powder discharge port on the first direction side is defined as r. When the angle toward the center of the sieve screen is 0° and the angle θ is 0°, the powder supply port is configured so that the most frequent position of the powder falling point is within a range of 0.4r to 0.6r outward from the center of the sieve screen, and θ is within a range of 0 to 45°, and the discharge guide is a rod with a length of 0.17r to 0.38r, whose base end is provided on the edge of the coarse powder discharge port on the first direction side, and whose entirety is inclined at an angle of 20 to 50° in a second direction opposite to the first direction with respect to the radial direction of the sieve screen. A powder sieving method according to a second aspect of the present invention includes a step of sieving the powder using the circular vibrating sieve of the first aspect of the present invention, and the amount of the powder supplied to the circular vibrating sieve in the step is 1,000 to 5,000 kg / h m per unit area of ​​the sieve screen. 2 It is characterized in that: A third invention provides a powder sieving method according to the second invention, characterized in that the powder contains 10 to 80% by weight of particles having a particle size smaller than the mesh size of the sieve screen. A fourth aspect of the present invention is a powder sieving method according to the third aspect of the present invention, characterized in that the powder is an abrasive material used in blasting. A fifth aspect of the present invention is a powder sieving method according to the second aspect of the present invention, characterized in that the powder is ferronickel slag. A sixth aspect of the present invention is a powder sieving method according to the fifth aspect of the present invention, characterized in that the ferronickel slag is an abrasive used in a blasting process for removing an insulating layer masked on a mother board. The powder sieving method of the seventh invention is characterized in that, in any of the second to sixth inventions, the vibrator has an upper weight and a lower weight, and the phase angle between the upper weight and the lower weight is 0 to 30°. [Effects of the Invention]

[0010] According to the present invention, the powder is supplied to an eccentric position on the sieve screen that is separated from the coarse powder outlet by the discharge guide, which prevents the powder from being discharged from the coarse powder outlet immediately after being supplied to the sieve screen. Furthermore, the powder travels at least one revolution on the sieve screen before being guided to the coarse powder outlet, ensuring sufficient time for processing on the sieve screen. This prevents particles smaller than the mesh size of the sieve screen from being discharged as coarse powder. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 2 is a vertical cross-sectional view of a circular vibrating sieve according to one embodiment. [Figure 2] FIG. 2 is a plan view of the sieve mesh of the circular vibrating sieve machine. [Figure 3] Figure (A) shows the positional relationship between the upper and lower weights and the movement of powder on the sieve when the phase angle is 60°. Figure (B) shows the positional relationship between the upper and lower weights and the movement of powder on the sieve when the phase angle is 0°. [Figure 4] FIG. [Figure 5] 1 is a graph showing particle size ratios of coarse powders obtained in Example 1 and Comparative Example 1. [Figure 6] 1 is a graph showing the distribution of surface roughness Ra of metal plates obtained in Example 1 and Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0012] Next, an embodiment of the present invention will be described with reference to the drawings. (Circular vibrating sieve) As shown in FIG. 1, a circular vibrating sieve 1 according to one embodiment of the present invention has a cylindrical base 10 with a bottom. A base 21 is supported on the upper part of the base 10 via a plurality of frame support springs 11. A housing 22 is fixed to the underside of the center of the base 21. A rotating shaft 23 is rotatably supported by the housing 22. An upper weight 24 is attached to the upper end of the rotating shaft 23 that protrudes above the housing 22. A lower weight 25 is attached to the lower end of the rotating shaft 23 that protrudes below the housing 22. The upper weight 24 and the lower weight 25 rotate together with the rotating shaft 23.

[0013] A first pulley 13 is attached to the lower end of the rotary shaft 23 via a drive spring 12. The first pulley 13 is rotatably supported on the bottom surface of the base 10. A motor 14 is provided inside the base 10. A second pulley 15 is attached to the rotary shaft of the motor 14. An endless belt 16 is stretched between the first pulley 13 and the second pulley 15. When the motor 14 is driven, the rotary shaft 23 rotates.

[0014] The vibrating body 20 is made up of the base 21, the housing 22, the rotary shaft 23, the upper weight 24, and the lower weight 25. When the motor 14 is driven, the vibrating body 20 vibrates.

[0015] A sieve frame 30 is fixed to the top of the base 21. The sieve frame 30 is composed of a lower cylindrical frame 31, a middle cylindrical frame 32, and an upper cylindrical frame 33 stacked one on top of the other. The top of the upper cylindrical frame 33 is closed by a tapered lid 34. A powder inlet 35 is provided in the center of the lid 34.

[0016] A sieve mesh 40 is stretched inside the sieve frame 30. The sieve mesh 40 is a mesh-like member formed by weaving together a large number of wires. The sieve mesh 40 may also be a plate material with a large number of holes. The sieve mesh 40 is circular, and its peripheral edge is sandwiched and fixed between the middle cylindrical frame 32 and the upper cylindrical frame 33. The sieve frame 30 applies an appropriate amount of tension to the sieve mesh 40. The sieve frame 30 also surrounds the outer periphery of the circular sieve mesh 40. The sieve mesh 40 divides the internal space of the sieve frame 30 into upper and lower sections.

[0017] A crank-shaped powder supply pipe 51 is provided inside the lid 34. One end of the powder supply pipe 51 is connected to the inlet 35. The other end (powder supply port 52) ​​of the powder supply pipe 51 opens toward the upper surface of the sieve screen 40. The powder introduced into the inlet 35 falls from the powder supply port 52 and is supplied to the upper surface of the sieve screen 40. Here, the powder is supplied to a position offset from the center of the sieve screen 40.

[0018] The structure of the powder supply pipe 51 is not particularly limited as long as it can supply the powder to a position offset from the center of the sieve screen 40. For example, the powder supply pipe 51 may be a straight, bottomed cylindrical pipe instead of a crank-shaped pipe. By providing an opening (powder supply port 52) ​​in a portion of the side of the bottomed cylindrical pipe near the bottom, the powder can be supplied to a position offset from the center of the sieve screen 40. Furthermore, the powder may be configured to fall straight down vertically from the powder supply port 52, or may fall in a parabolic curve. Therefore, in a plan view, the position of the powder supply port 52 and the point where the powder falls on the sieve screen 40 do not need to coincide.

[0019] The vibration of the vibrating body 20 causes the sieve screen 40 to vibrate, thereby sieving the powder. Powder larger than the mesh size of the sieve screen 40 remains on the upper surface of the sieve screen 40. A coarse powder discharge outlet 53 is formed above the sieve screen 40 of the sieve frame 30, i.e., in the upper cylindrical frame 33. A coarse powder discharge path 54 is connected to the coarse powder discharge outlet 53. The coarse powder remaining on the upper surface of the sieve screen 40 is discharged to the outside of the circular vibrating sieve machine 1 via the coarse powder discharge outlet 53 and the coarse powder discharge path 54.

[0020] Powder particles smaller than the mesh size of the sieve screen 40 pass through the sieve screen 40 and fall downward. A fine powder discharge outlet 55 is formed below the sieve screen 40 in the sieve frame 30, specifically in the lower cylindrical frame 31. A fine powder discharge path 56 is connected to the fine powder discharge outlet 55. A conical receiving portion 57 is also provided inside the lower cylindrical frame 31. The fine powder that has fallen through the sieve screen 40 is discharged to the outside of the circular vibrating sieve machine 1 via the fine powder discharge outlet 55 and the fine powder discharge path 56.

[0021] As shown in FIG. 2, the center of the circular sieve screen 40 is O, the radius is r, and the angle around the center O is θ. The angle θ is positive in the first direction D1. The angle θ from the center O toward the edge of the coarse powder discharge port 53 on the first direction D1 side is set to 0°. In the example shown in FIG. 2, the first direction D1 is clockwise, but the first direction D1 may also be counterclockwise. The direction opposite to the first direction D1 is set to second direction D2.

[0022] As described above, the powder supply port 52 is configured so that the powder falls at a position offset from the center O of the sieve screen 40. Preferably, the powder supply port 52 is configured so that the most frequent position of the powder fall point is within a range of 0.4r to 0.6r outward from the center O of the sieve screen 40, and θ is within a range of 0 to 45°. Hereinafter, this range will be referred to as A. The powder fall point refers to the point on the sieve screen 40 where the powder falls. Since the powder falls with a certain degree of spread, the fall points spread according to a certain distribution. The most frequent position of the fall points refers to the point with the highest frequency in the distribution of fall points.

[0023] A discharge guide 41 is provided on the upper surface of the sieve screen 40. The discharge guide 41 is a rod having a length of 0.17r to 0.38r. The base end of the discharge guide 41 is provided on the edge of the coarse powder discharge port 53 on the first direction D1 side. The entire discharge guide 41 is inclined in the second direction D2 with respect to the radial direction of the sieve screen 40. The angle formed between the radial direction of the sieve screen 40 and the discharge guide 41 is defined as α. It is preferable that α is 20 to 50°.

[0024] As described above, the powder is supplied to an eccentric position of the sieve screen 40. In addition, the point where the powder falls is separated from the coarse powder discharge port 53 by the discharge guide 41. Therefore, it is possible to prevent the powder from being discharged from the coarse powder discharge port 53 immediately after being supplied to the sieve screen 40.

[0025] The vibration of the sieve screen 40 is generated by the rotation of the upper weight 24 and the lower weight 25 attached above and below. In principle, the rotation of the upper weight 24 generates horizontal vibrations in the sieve screen 40, causing the powder on the sieve screen 40 to move in the circumferential direction. The rotation of the lower weight 25 generates vertical vibrations, causing the powder on the sieve screen 40 to move in the radial direction. The vibration mode created by these combined vibrations changes depending on the angle between the upper weight 24 and the lower weight 25 (hereinafter referred to as the "phase angle").

[0026] 3(A), when the lower weight 25 is positioned at an angle of approximately 60° to the second direction D2 side of the upper weight 24, the powder on the sieve screen 40 moves in a spiral manner in the first direction D1 toward the center. As the phase angle becomes smaller, the tendency of the powder on the sieve screen 40 to move toward the center weakens, and instead, it tends to move toward the periphery.

[0027] As shown in Figure 3(B), when the positions of the lower weight 25 and the upper weight 24 are aligned (phase angle is 0°), the powder on the sieve mesh 40 moves in a spiral manner in the first direction D1 from the center toward the outer periphery.

[0028] The phase angle between the upper weight 24 and the lower weight 25 is preferably 0 to 30°. In this way, the powder on the sieve screen 40 spreads from the center toward the periphery, allowing efficient sieving using the entire sieve screen 40. In addition, the powder on the sieve screen 40 moves in the first direction D1. Therefore, the powder supplied to the region A travels around the sieve screen 40 at least once before being guided to the coarse powder discharge port 53. This ensures sufficient time for the powder to be processed on the sieve screen 40, and prevents particles smaller than the mesh size of the sieve screen 40 from being discharged as coarse powder.

[0029] (Method of sieving powder) A powder sieving method according to one embodiment of the present invention includes a step of sieving powder using the circular vibrating sieve 1 having the above-described configuration. In this step, powder is supplied to the circular vibrating sieve 1, and sieved coarse powder and fine powder are obtained.

[0030] In order to obtain the effect of suppressing particles smaller than the mesh size of the sieve screen 40 from being discharged as coarse powder in the circular vibrating sieve 1, the amount of powder supplied to the circular vibrating sieve 1 is set to 1,000 to 5,000 kg / h m per unit area of ​​the sieve screen 40. 2 It is preferable that:

[0031] Furthermore, the powder before sieving preferably contains 10 to 80% by weight of particles having a particle size smaller than the mesh size of the sieve screen 40. For example, the mesh size of the sieve screen 40 is set to 300 μm. In this case, the powder before sieving preferably contains 10 to 80% by weight of particles having a particle size smaller than 300 μm.

[0032] The powder may be an abrasive used in blasting, or may be ferronickel slag, which is used as an abrasive in blasting to remove an insulating layer masked on a base plate.

[0033] Meanwhile, hemispherical or disc-shaped nickel electrodeposits (generally called "electronic nickel button") are produced by the following procedure.

[0034] First, a mother plate 2 is manufactured. As shown in Fig. 4, the surface of a stainless steel or titanium metal plate 61 is covered with an insulating layer 63, leaving a plurality of electrodeposited portions 62. A beam 65 made of copper or nickel-copper clad material is attached to the upper edge of the metal plate 61 via a hanger 64.

[0035] Next, electrowinning is performed using the mother plate 2 as a cathode. Specifically, multiple cathodes and multiple anodes are alternately inserted into an electrolytic cell filled with an electrolyte, and electrolysis is performed by passing a current through the cells. In the case of nickel electrowinning, an insoluble electrode equipped with an anode box is used as the anode. An aqueous solution of nickel chloride is used as the electrolyte, and this is continuously supplied to the electrolytic cell. After passing a current for a predetermined time (for example, 4 to 10 days), electrolytic nickel is electrodeposited on the electrodeposited portion 62 of the mother plate 2.

[0036] After a predetermined period of time has passed, the mother plate 2 is removed from the electrolytic cell. The mother plate 2 is vibrated by a method such as hammering to peel off the electrodeposit that has been electrodeposited on the mother plate 2. The electrodeposit that has been peeled off from the mother plate 2 is polished, washed, and dried to become a product.

[0037] The mother plate 2 from which the electrodeposits have been stripped is inserted into the electrolytic cell as a cathode again and subjected to electrowinning. That is, the mother plate 2 is used repeatedly for electrowinning. When the mother plate 2 is used repeatedly, the insulating layer 63 deteriorates and peels off, resulting in a high defect rate for the electrodeposits. When the defect rate exceeds a reference value, it is determined that the insulating layer 63 has reached the end of its life, and the mother plate 2 is reconditioned.

[0038] The mother plate 2 is reconditioned by first removing the insulating layer 63 from the metal plate 61. The insulating layer 63 is removed by blasting. Ferronickel slag is a suitable abrasive material for the blasting. The metal plate 61 from which the insulating layer 63 has been removed is masked again with insulating resin, and the insulating layer 63 is then formed.

[0039] After being used in the blasting process, the abrasive is collected and foreign matter is removed using a separator. The abrasive from which foreign matter has been removed is sent to a circular vibrating sieve 1, where it is separated into fine powder and coarse powder. The fine powder is discarded, while the coarse powder is used again in the blasting process. This allows the abrasive to be reused, reducing the cost of new abrasive.

[0040] By adjusting the surface of the metal plate 61 to a predetermined roughness by blasting, it is possible to prevent peeling of the insulating layer 63. The surface roughness of the metal plate 61 can be adjusted by the particle size of the abrasive used in the blasting. Therefore, the mesh size of the sieve mesh 40 is set so as to obtain an abrasive with an appropriate particle size.

[0041] The sieving method of this embodiment can prevent particles smaller than the mesh size of the sieve screen 40 from being discharged as coarse powder. This increases the average particle size of the abrasive recovered as coarse powder. This allows the surface of the metal plate 61 to be adjusted to a desired roughness. [Example]

[0042] Example 1 Ferronickel slag used as an abrasive in the blasting of base plates was collected, foreign matter was removed using a separator, and then the slag was sieved using a circular vibrating sieve. The phase angle between the lower and upper weights was set to 0°. The sieve mesh installed in the circular vibrating sieve was circular with a radius of 40 cm. The mesh size of the sieve mesh was 300 μm. The most frequent position for the powder to fall was set to 20 cm (0.5r) outward from the center of the sieve mesh, with θ at 30°. The length of the discharge guide was 14 cm (0.35r), and α was 35°. The ferronickel slag supply rate was 2,600 kg / h·m per unit area of ​​the sieve mesh. 2 It was decided.

[0043] The particle size ratio of the particles recovered as coarse powder was measured by a sieving method. Furthermore, the ferronickel slag recovered as coarse powder was used as an abrasive to blast a mother plate. The surface roughness Ra (arithmetic mean roughness) of the blasted metal plate was measured using a small surface roughness measuring instrument manufactured by Mitutoyo Corporation. One out of every 40 to 50 blasted metal plates was sampled, and the surface roughness Ra of each sample was measured at nine locations on each side: (top, middle, bottom) x (left, middle, right) (a total of 18 locations on both sides). In Example 1, approximately 70 samples were used. Therefore, the number of data points for surface roughness Ra was approximately 1,300.

[0044] (Comparative Example 1) The ferronickel slag was sieved using the same procedure as in Example 1. However, the phase angle between the lower weight and the upper weight was set to 60°. The most frequent position of the powder falling point was set to the center of the sieve. The length of the discharge guide was set to 20 cm (0.5 r), and α was set to 35°. The other conditions were the same as in Example 1.

[0045] The particle size ratio of the particles recovered as coarse powder was measured. Furthermore, the ferronickel slag recovered as coarse powder was used as an abrasive to blast a mother plate. The surface roughness Ra of the metal plate after blasting was measured. In Comparative Example 1, the number of samples for measuring the surface roughness Ra was approximately 140. Therefore, the number of data points for surface roughness Ra was approximately 2,500.

[0046] The particle size ratios of the coarse powder obtained in Example 1 and Comparative Example 1 are shown in Figure 5. In Comparative Example 1, approximately 45% of particles with a particle size of less than 300 µm remained. In contrast, in Example 1, the particles with a particle size of less than 300 µm were reduced to approximately 20%. This confirmed that Example 1 was able to prevent particles smaller than the mesh size of the sieve from being discharged as coarse powder.

[0047] The distribution of the surface roughness Ra of the metal plate after blasting is shown in Figure 6. It can be seen that the surface roughness Ra of Example 1 is shifted in the rougher direction compared to Comparative Example 1. The target value for the surface roughness Ra of the metal plate is set to 5.9 μm or more. In Example 1, more than 80% of the plates had a surface roughness Ra of 5.9 μm or more, confirming that the target value was met. [Explanation of symbols]

[0048] 1. Circular vibrating sieve 10 Mounting stand 20 vibrating body 21 Base 22 Housing 23 Rotation axis 24 Upper weight 25 Lower Weight 30 Sieve frame 40 Sieve screen 41 Ejection Guide 52 Powder supply port 53 Coarse powder outlet 55 Fine powder outlet

Claims

1. A circular sieve mesh, a powder supply port for supplying powder to an upper surface of the sieve; a discharge guide provided on the upper surface of the sieve; a sieve frame surrounding the outer periphery of the sieve mesh; a coarse powder discharge port formed above the sieve mesh of the sieve frame; a fine powder discharge port formed below the sieve mesh of the sieve frame; and a vibrator that vibrates the sieve mesh, When the radius of the sieve screen is r, and the angle around the first direction based on the center of the sieve screen, which is an angle from the center of the sieve screen toward the edge of the coarse powder discharge port on the first direction side, is θ, The powder supply port is configured so that the most frequent position of the powder falling point is within a range of 0.4r to 0.6r outward from the center of the sieve screen, and θ is within a range of 0 to 45°, The discharge guide is a rod having a length of 0.17r to 0.38r, a base end of which is provided on the edge of the coarse powder discharge port on the first direction side, and the entire guide is inclined at an angle of 20 to 50 degrees in a second direction opposite to the first direction with respect to the radial direction of the sieve screen. A circular vibrating sieve machine characterized by the above.

2. The method comprises a step of sieving the powder using the circular vibrating sieve according to claim 1, The amount of powder supplied to the circular vibrating sieve in this step is 1,000 to 5,000 kg / h m per unit area of ​​the sieve mesh. ２ is A method for sieving powder, comprising:

3. The powder has a particle size smaller than the mesh size of the sieve of 10 to 80% by weight.

3. The method for sieving powder according to claim 2, wherein the sieving step comprises the steps of:

4. The powder is an abrasive material used in blasting.

4. The method for sieving powder according to claim 3.

5. The powder is ferronickel slag.

3. The method for sieving powder according to claim 2, wherein the sieving step comprises the steps of:

6. The ferronickel slag is an abrasive used in blasting to remove the insulating layer masked on the base plate.

6. The method for sieving powder according to claim 5, wherein the sieving step comprises the steps of:

7. The vibrating body has an upper weight and a lower weight, The phase angle between the upper weight and the lower weight is 0 to 30 degrees.

7. The method for sieving powder according to claim 2, wherein the powder is sieved in a manner similar to that described above.

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