Method for recovering copper from enameled wire

Abstract

To provide a method for recovering copper from an enamel wire, the method being capable of reducing an environmental load and recovering high-purity copper at low processing cost.SOLUTION: A method for recovering copper from an enamel wire removes an insulator 22 from an enamel wire 2 having the insulator 22 around a conductor 21 made of copper or copper alloy to recover the copper or the copper alloy constituting the conductor 21, and includes a stripping step of compressing or rolling the enamel wire 2 to strip the insulator 22 from the conductor 21, and a removal step of peeling and removing the insulator 22 that has been stripped from the conductor 21.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for recovering copper from enameled wire.

Background Art

[0002] An enameled wire is known in which an enamel paint is applied and dried around a conductor to form an insulator. In enameled wire, since the adhesion between the conductor and the insulator is high, it is known that when the enameled wire is discarded, it is difficult to remove the insulator from the conductor and recover copper.

[0003] In Patent Document 1, a method of removing the insulator by heating and carbonizing the insulator of the enameled wire and then applying a mechanical external force is disclosed. Further, in Patent Document 2, a method of removing the insulator by immersing the enameled wire in an alkaline solution and hydrolyzing the insulator is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the method described in Patent Document 1, it is necessary to heat to a high temperature of 500°C or higher in order to carbonize the insulator, and since a huge amount of thermal energy is required, there is a problem that the processing cost becomes high. Further, there is a risk that the conductor is oxidized during heating or the carbide and the conductor are integrated, resulting in a decrease in the purity of the recoverable copper.

[0006] The method described in Patent Document 2 requires a high-concentration alkaline solution, which results in high chemical costs and wastewater treatment, leading to a significant environmental burden and high processing costs. Furthermore, heating is required to hydrolyze the insulator, further increasing processing costs.

[0007] Therefore, the present invention aims to provide a method for recovering copper from enameled wire that can reduce environmental impact and recover high-purity copper at low processing costs. [Means for solving the problem]

[0008] The present invention aims to solve the above problems and provides a method for recovering copper or copper alloy constituting a conductor by removing an insulator from an enameled wire having an insulator surrounding a conductor made of copper or a copper alloy, comprising a peeling step of applying compression or rolling to the enameled wire to peel off the insulator from the conductor, and a removal step of peeling off and removing the insulator peeled off from the conductor. [Effects of the Invention]

[0009] According to the present invention, a method for recovering copper from enameled wire can be provided that reduces environmental impact and allows for the recovery of high-purity copper at a low processing cost. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram of a copper recovery apparatus for enameled wire used in a copper recovery method for enameled wire according to one embodiment of the present invention. [Figure 2] (a) and (b) are diagrams illustrating the compression process. [Figure 3] These are photographs showing examples of enameled wire after compression processing: (a) after one press, (b) after two presses, and (c) after cuts have been made in (b) with a blade. [Figure 4] (a) is a photograph showing the cross-section of the enameled wire before compression, and (b) is a photograph showing the cross-section of the enameled wire after compression. [Figure 5] This is a diagram illustrating the rolling process. [Figure 6] This is a perspective view showing an example of a removal device. [Figure 7] This figure shows the results of the investigation into processing conditions for compression (press working). [Figure 8] This is a flowchart of a method for recovering copper from enameled wire according to one embodiment of the present invention. [Modes for carrying out the invention]

[0011] [Embodiment] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0012] Figure 1 is a schematic diagram of the copper recovery device 1 for enameled wire (hereinafter simply referred to as copper recovery device 1) used in the copper recovery method for enameled wire according to this embodiment. As shown in Figure 1, the copper recovery device 1 is a device that removes the insulator 22 from the conductor 21 of the enameled wire 2 and recovers the copper or copper alloy that constitutes the conductor 21, and comprises a stripping device 3 and a removal device 4.

[0013] The enameled wire 2 is an electric wire used, for example, in motors, transformers, and induction heating coils for vehicles. The enameled wire 2 may be a round wire with a circular cross-section or a rectangular wire with a rectangular cross-section. Furthermore, the enameled wire 2 is not limited to round or rectangular wires; for example, its cross-sectional shape may be elliptical or triangular, and its cross-sectional shape is not particularly limited. The enameled wire 2 has a conductor 21 made of copper or a copper alloy and an insulator 22 formed by applying and baking enamel paint around the conductor 21. The insulator 22 may be made of, for example, polyimide, polyamideimide, polyester, polyurethane, polyesterimide, etc.

[0014] In enameled wire 2, it is known that the adhesion between the insulator 22 and the conductor 21 is high. Therefore, when disposing of the enameled wire 2, it is not easy to remove the insulator 22 from the conductor 21 and recover the conductor 21 (that is, recover the copper or copper alloy constituting the conductor 21). In the copper recovery device 1 according to the present embodiment, even in the enameled wire 2 where the adhesion between the conductor 21 and the insulator 22 is high, the insulator 22 can be easily removed, enabling easy recovery of the copper or copper alloy constituting the conductor 21. This will be described in detail below.

[0015] (Peeling device 3) The peeling device 3 is a device that performs a peeling process of applying compression processing (pressing) or rolling processing to the enameled wire 2 to peel the insulator 22 from the conductor 21.

[0016] Figs. 2(a) and (b) are diagrams for explaining compression processing (pressing). When performing compression processing with the peeling device 3, a press 31 for performing compression processing is used as the peeling device 3. In compression processing, the enameled wire 2 is crushed in a direction perpendicular to the longitudinal direction. In particular, it is preferable to move the enameled wire 2 along the longitudinal direction and continuously perform compression processing along the longitudinal direction of the enameled wire 2. In the present embodiment, a rectangular wire is used as the enameled wire 2, and in the peeling process, compression processing is performed by pressing in the minor axis direction of the enameled wire 2. At this time, by arranging a gauge block 311 between the presses 31, the enameled wire 2 is formed to have the same thickness as the gauge block 311.

[0017] By performing compression processing, as shown in Fig. 2(b), the enameled wire 2 is deformed so as to be expanded in the direction perpendicular to the press direction, and a compressive stress acts in the press direction (the minor axis direction of the enameled wire 2), while a tensile stress acts in the direction perpendicular to the press direction (the major axis direction of the enameled wire 2). Then, in the major axis direction of the enameled wire 2, the enameled wire 2 is stretched, and due to the difference in the ease of elongation between the conductor 21 and the insulator 22, a shear stress is generated at the interface between the conductor 21 and the insulator 22, resulting in partial peeling between the conductor 21 and the insulator 22. By making a cut 22a in this peeled portion (compression surface) with the blade 41 of the removing device 4 described later, the insulator 22 can be removed from the conductor 21.

[0018] In compression processing, multiple presses may be performed at any location in the longitudinal direction of the enameled wire 2. By performing multiple presses, partial peeling between the conductor 21 and the insulator 22 is more likely to occur. Also, in compression processing, it is advisable to repeatedly perform the operation of running the enameled wire 2 after pressing and then pressing again, sequentially applying presses to the entire longitudinal direction of the enameled wire 2.

[0019] Fig. 3 is a photograph showing an example of the enameled wire 2 after compression processing. Fig. 3(a) is a photograph after one press, (b) is a photograph after two presses, and (c) is a photograph when a cut is made with a blade after two presses. Also, Fig. 4(a) is a photograph showing the cross-section of the enameled wire 2 before compression processing, and Fig. 4(b) is a photograph showing the cross-section of the enameled wire 2 after compression processing. Note that Fig. 4(b) shows the state where a cut 22a has been made in the insulator 22 with a blade. As shown in Figs. 3 and 4, it was confirmed that the insulator 22 can be peeled from the conductor 21 by performing compression processing. The suitable processing conditions during compression processing will be described later.

[0020] Figure 5 is a diagram illustrating the rolling process. When rolling is performed in the peeling process, a rolling mill 32 is used as the peeling device 3. In the rolling mill 32, the enameled wire 2 is passed between a pair of rollers 321, compressing and stretching the enameled wire 2. In the rolling mill 321, the rollers 321 are rotated so that the outer surface of the rollers 331 moves in the same direction as the direction in which the enameled wire 2 travels at the position where they contact the enameled wire 2. In the rolling process, similar to the compression process described above, the enameled wire 2 is stretched in a direction perpendicular to the compression direction (the opposing direction of the rollers 321), and due to the difference in the ease of stretching between the conductor 21 and the insulator 22, shear stress is generated at the interface between the conductor 21 and the insulator 22, resulting in a partial peeling area between the conductor 21 and the insulator 22.

[0021] (Removal device 4) The removal device 4 is a device that performs a removal process in which the insulator 22 that has been peeled off from the conductor 21 by the peeling device 3 is peeled off and removed. Figure 6 is a diagram showing an example of the removal device 4. As shown in Figure 6, the removal device 4 makes continuous cuts 22a along the longitudinal direction of the insulator 22 after the peeling process with a blade 41, and removes the insulator 22 from the conductor 21 by continuously peeling off the insulator 22 that has been divided by the cuts 22a.

[0022] In this embodiment, a pair of blades 41 are positioned opposite each other, one above the center of the enameled wire 2. Each blade 41 forms a cut 22a along the longitudinal direction of the enameled wire 2, thereby continuously dividing the insulator 22 into two halves, left and right. The divided insulator 22 is then opened to the left and right, and each insulator 22 is guided to the winding roller 43 via the guide roller 42. As the enameled wire 2 is run, the insulator 22 is wound up by the winding roller 43, causing the insulator 22 to be pulled to the left and right, and continuously stripped from the conductor 21. Note that the up and down and left and right directions here are relative and are not limited to the vertical and horizontal directions.

[0023] The winding tension of the insulator 22 by the winding roller 43 should be between 5% and 90% of the breaking strength of the insulator 22. The breaking strength of the insulator 22 is the value measured by performing a tensile test using an autograph after cutting the insulator 22 from the enameled wire 2 into strips with a width of 1 mm, at a gauge length of 30 mm and a tensile speed of 10 mm / min. This allows the insulator 22 to be peeled off stably without causing deflection or breakage of the insulator 22. Furthermore, the angle θ between the direction in which the insulator 22 is pulled when peeling it from the conductor 21 and the direction in which the enameled wire 2 runs should be between 30 degrees and 160 degrees, preferably between 90 degrees and 160 degrees. This makes it easier to peel the insulator 22 from the conductor 21 and also suppresses breakage of the insulator 22 during winding. Note that the removal device 4 shown in Figure 6 is merely an example, and the specific structure of the removal device 4 can be modified as appropriate.

[0024] (Regarding suitable processing conditions for the peeling process) Compression processing (press processing) was performed while changing the processing conditions, and it was confirmed whether the insulator 22 could be easily stripped off the processed enameled wire 2. The results are shown in Figure 7. In Figure 7, the areas from which the insulator 22 could be easily stripped off are indicated by hatching. In addition, a flat rectangular wire was used as the enameled wire 2, and the press was applied in the direction of its short axis.

[0025] As shown in Figure 7, when performing compression processing, it is desirable to perform the processing so that the rate of change in thickness is 54.5% or more. The rate of change in thickness can be obtained by the following formula, where A is the thickness of the enameled wire 2 before processing (for example, the thickness in the short axis direction of a rectangular wire) and B is the thickness of the enameled wire 2 after processing. Percentage change in thickness (%) = {(AB) / A} × 100

[0026] Furthermore, as shown in Figure 7, when performing compression processing, it is desirable to perform the processing so that the rate of change in Vickers hardness is 105.5% or more. The rate of change in Vickers hardness can be obtained by the following formula, where C is the Vickers hardness before processing and D is the Vickers hardness after processing. The Vickers hardness was measured using the method described in JIS Z2244 (2009). The measurement conditions were a load of 200g and a holding time of 15 seconds. The cross-section of the sample was mirror-polished, and the average value of the values ​​measured at two locations near the center of the conductor 21 was used. Change in Vickers hardness (%) = {(DC) / C} × 100

[0027] Figure 7 shows an example of compression processing, but it is desirable to apply similar conditions to rolling processing as well. That is, when rolling processing is performed in the peeling process, it is desirable to process the material so that the rate of change in thickness is 54.5% or more and the rate of change in Vickers hardness is 105.5% or more, just as in the case of compression processing.

[0028] (Method for recovering copper from enameled wire) Figure 8 is a flowchart of the copper recovery method for enameled wire according to this embodiment. As shown in Figure 8, in the copper recovery method for enameled wire according to this embodiment, the peeling step S1 and the removal step S2 are repeated in succession to recover the copper or copper alloy constituting the conductor 21 of the enameled wire 2.

[0029] In the stripping process of step S1, the stripping device 3 is used to compress or roll the enameled wire 2 to strip the insulator 22 from the conductor 21. At this time, it is preferable to perform the processing so that the rate of change in thickness is 54.5% or more and the rate of change in Vickers hardness is 105.5% or more. Note that in the stripping process, it is not necessary for the entire insulator 22 to be stripped from the conductor 21; it is sufficient for stripping to occur in a part of the insulator 22 to serve as a starting point for peeling.

[0030] In the removal process of step S2, the insulator 22 that has been peeled off from the conductor 21 is removed using the removal device 4. Here, as shown in Figure 6, cuts 22a are made continuously along the longitudinal direction of the insulator 22 after the peeling process using the blade 41, and the insulator 22 is removed from the conductor 21 by continuously peeling off the insulator 22 that has been divided by the cuts 22a. It is preferable that the part in which the cuts 22a are made is a compressed surface that has undergone compression or rolling. However, it is not limited to this, and any method that can peel off and remove the insulator 22 may be used to remove the insulator 22. The conductor 21 from which the insulator 22 has been removed is recovered by being wound up on a winding drum, for example.

[0031] (Operation and Effects of the Embodiment) As described above, the copper recovery method for enameled wire according to this embodiment includes a peeling step of applying compression or rolling to the enameled wire 2 to peel off the insulator 22 from the conductor 21, and a removal step of peeling off and removing the insulator 22 that has been peeled off from the conductor 21.

[0032] By performing compression or rolling processes, the difference in the elasticity of the conductor 21 and the insulator 22 can be utilized to separate the insulator 22 from the conductor 21, making it possible to easily peel and remove the insulator 22 from the conductor 21. This embodiment has a low environmental impact because it does not use chemicals that require wastewater treatment, and because it does not require heat treatment, the conductor 21 does not oxidize, and the carbonized insulator 22 does not integrate with the conductor 21, allowing for the recovery of high-purity copper. Furthermore, this embodiment does not require treatment using chemicals that have high processing costs, and general compression or rolling equipment can be used, resulting in very low equipment and processing costs, and enabling the recovery of copper or copper alloys at a low cost.

[0033] (modified version) In the above embodiment, a case was described in which the peeling process and the removal process are performed on a single manufacturing line. However, the manufacturing line may be divided into separate processes, such as winding the enameled wire 2 once after the peeling process and then performing the removal process on the wound enameled wire 2. In addition, both compression and rolling processes may be performed in the peeling process to make the insulator 22 easier to peel off.

[0034] (Summary of the embodiments) Next, the technical concept understood from the embodiments described above will be described using the reference numerals and other symbols from the embodiments. However, the reference numerals and other symbols in the following description are not limited to the components in the claims that are specifically shown in the embodiments.

[0035] [1] A method for recovering copper from an enameled wire (2) having an insulator (22) surrounding a conductor (21) made of copper or a copper alloy, comprising: a peeling step of applying compression or rolling to the enameled wire (2) to peel off the insulator (22) from the conductor (21); and a removal step of peeling off and removing the insulator (22) that has been peeled off from the conductor (21).

[0036] [2] The method for recovering copper from an enameled wire according to [1], wherein the enameled wire (2) is a flat rectangular wire, and in the stripping step, the compression process is performed so as to press the enameled wire (2) in the direction of the short axis, and in the compression process, the thickness change rate in the direction of the short axis is 54.5% or more.

[0037] [3] The method for recovering copper from enameled wire according to [1], wherein the stripping step is performed such that the rate of change in Vickers hardness is 105.5% or more.

[0038] [4] The method for recovering copper from an enameled wire according to [1], wherein in the removal step, cuts (22a) are made in the insulator (22) after the peeling step with a blade (41) in a continuous manner along the longitudinal direction, and the insulator (22) is removed by continuously peeling off the insulator (22) that has been divided by the cuts (22a).

[0039] (Note) Although embodiments of the present invention have been described above, the embodiments described above do not limit the invention as defined in the claims. Furthermore, it should be noted that not all combinations of features described in the embodiments are necessarily essential for solving the problem of the invention. Moreover, the present invention can be implemented with appropriate modifications without departing from its spirit. [Explanation of Symbols]

[0040] 1... Copper recovery device for enameled wire 2... Enamel wire 21... Conductor 22...Insulator 3... Peeling device 31... Swaging machine 32…Die drawing machine 33…mouth machine 4...Removal device 41...Blade

Claims

1. A method for recovering the copper or copper alloy constituting the conductor by removing the insulator from an enameled wire having an insulator around a conductor made of copper or a copper alloy, A stripping step in which the enameled wire is subjected to compression or rolling to remove the insulator from the conductor, The process includes a removal step of peeling off and removing the insulator that has been removed from the conductor, The aforementioned enameled wire is a flat rectangular wire, In the peeling step, the compression process is performed by pressing the enamel wire in the direction of its short axis, and in the compression process, the rate of change in thickness in the direction of the short axis is 54.5% or more, and the rate of change in Vickers hardness is 105.5% or more. Methods for recovering copper from enameled wire.

2. In the removal step, the insulator after the peeling step is continuously cut along its longitudinal direction with a blade, and the insulator is removed by continuously peeling off the insulator that has been divided by the cuts. A method for recovering copper from enameled wire according to claim 1.

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