JP6489372B2 - Method for recovering copper from resin-coated copper wire - Google Patents

Description

  The present invention relates to a method for efficiently recovering copper from a resin-coated copper wire used in automobiles, home appliances, industrial electrical equipment, and the like.

  Copper wires coated with resin (referred to as resin-coated copper wires) are often used in automobiles, home appliances, industrial electrical equipment, and the like. In general, the copper material used for the resin-coated copper wire is copper having a purity of 99.9% or higher, but at present, the purity of the copper material recovered from the resin-coated copper wire is handled as about 98%. This is because the recovered copper material contains a resin of the coating material, a filler material in the resin, an insulator, elements, solder, and the like as impurities. Conventionally, when heat treatment is performed to recover the copper wire from the resin-coated copper wire, oily smoke is generated by the resin thermal decomposition, which impairs the recycling environment.

  If the resin coating and impurities are sufficiently removed and the copper wire close to the material can be recovered, the copper wire recovered from the coated copper wire can be reused as high-grade copper, for example, a copper-stretched product raw material, or Since it can be reused as another copper product raw material, it is preferable in terms of procurement of high-grade copper raw material and energy saving.

Conventionally, the following processing methods are known as methods for recovering a copper wire by removing the resin coating from the resin-coated copper wire.
(Ii) Put a waste copper wire with resin coating in a heating furnace, dry-treat in a non-oxidizing atmosphere at a temperature of 300 to 450 ° C, discharge exhaust gas containing hydrogen chloride gas, and deposit carbon residue The obtained copper wire is recovered in an unmelted state, the residue attached to the copper wire is removed through each step of vibration, sieving, and crushing, and the copper wire from which the resin coating has been removed is recovered (Patent Document 1).
(B) The resin-coated copper wire is pyrolyzed in an oxygen-free or low-oxygen atmosphere by an electric heater, microwave irradiation, and heating means using superheated steam, and this pyrolysis is performed in one or more stages of pyrolysis chambers. The resin coating is decomposed by this thermal decomposition to separate the residue and the copper wire, and the separated copper wire is recovered by washing with acid (Patent Document 2).
(C) Resin-coated copper wire is heat treated to carbonize the resin coating, the carbide and the copper wire are separated, the separated copper wire is acid washed and the copper is recovered. Then, it is heated to 500 to 800 ° C. by electromagnetic induction heating or superheated steam, and the carbonized resin and copper are separated by vibration, mechanical external force or washing (Patent Document 3).

Japanese Patent Laid-Open No. 11-188335 JP 2014-029817 A JP 2014-069137 A

  The above method (b) has a problem that oil residue is not sufficiently peeled off because the amount of carbon contained in the residue adhering to the copper wire is large, and oil smoke is generated when it is used as a raw material for copper products. . In the method (b), a copper wire having a metallic luster on the surface can be obtained.However, the heating method is complicated, and the method (c) increases the heating cost because the heating temperature is high. Both the methods (b) and (c) have a problem that the cost of waste water treatment is increased because the acid cleaning is performed.

  The present invention solves the above-mentioned problems in the conventional method of recovering copper wire from resin-coated copper wire, and does not require acid cleaning. Provided is a method capable of recovering a small amount of copper at a low cost.

The present invention relates to the following copper recovery method that has solved the above problems.
[1] At a temperature at which a resin-coated copper wire is oxidized and decomposed without being carbonized in an air atmosphere, and a copper oxide film is mechanically peeled from the surface of the copper wire to a thickness of 5 to 10 μm. A method for recovering copper, comprising firing, and after the firing, the copper oxide film is mechanically peeled together with the attached firing residue to recover the copper wire.
[2] The copper recovery method according to the above [1], wherein a copper wire having a polyester resin coating or a copper wire having a polyurethane resin coating is fired at 420 ° C. to 470 ° C. in an air atmosphere.
[3] The copper recovery method according to the above [1] or [2], wherein the fired resin-coated copper wire is subjected to ultrasonic cleaning in water, and the copper oxide film is peeled off together with the adhered firing residue.
[4] The copper oxide film is peeled off from the fired resin-coated copper wire together with the attached fired residue using a peeling machine having a peeling blade on the rotating shaft or an air table. The method for recovering copper described in 2].
[5] Crush a member having a resin-coated copper wire, magnetically sort the crushed pieces, separate the iron material, put the separated crushed pieces into a firing furnace, and oxidize and decompose the resin coating and oxidize the copper wire surface The above-mentioned [1] to [[] above, which are fired at a temperature at which the copper film is formed, put the fired crushed pieces into a mechanical peeling means, peel off the copper oxide film together with the attached baking residue, and collect the copper wire [4] The method for recovering copper according to any one of [ 4].

[Specific description]
The present invention is a temperature at which a resin-coated copper wire is formed in a film thickness of 5 to 10 μm so that the resin coating is oxidized and decomposed without being carbonized in an air atmosphere, and the copper oxide film is mechanically peeled on the surface of the copper wire. The copper recovery method is characterized in that after the baking, the copper oxide film is mechanically peeled off together with the attached baking residue to recover the copper wire.

  The resin-coated copper wire to be treated in the present invention is a copper wire coated with a resin, and is a copper wire coated with an insulating resin such as a polyurethane resin, a polyester resin, a polyesterimide resin, a polyamideimide resin, or a polyimide resin. Resin-coated copper wire is commonly used as a magnet wire because it is often used in motors, generators, and transformers, and is also known as enameled wire. The method of the present invention can be widely applied to these resin-coated copper wires. Moreover, the collection | recovery method of this invention can process not only the single-piece | unit of a resin coating copper wire but the crushing piece of the state in which the resin coating copper wire was wound around the coil.

  In the recovery method of the present invention, the resin-coated copper wire is baked in an air atmosphere at a temperature at which the resin coating is oxidatively decomposed and the copper oxide film is mechanically peeled from the copper wire surface. Specifically, for example, baking is performed so that the temperature of the resin coating is higher than the temperature at which the resin coating is oxidatively decomposed and the thickness of the copper oxide film on the surface of the copper wire is 5 to 10 μm.

  The firing step of the recovery method of the present invention is a step in which the resin-coated copper wire is heated in an air atmosphere to oxidatively decompose (combust) the resin coating, and is different from the treatment method in which the resin coating is carbonized. What is necessary is just to set a calcination temperature according to the kind of resin. Various resin coatings can be oxidatively decomposed (burned) by heating to approximately 400 ° C to 500 ° C. For example, a copper wire having a polyester resin coating or a copper wire having a polyurethane resin coating can be oxidatively decomposed by heat treatment at 420 ° C. to 470 ° C. in an air atmosphere. By this baking step, the organic component of the resin coating is decomposed to generate carbon dioxide gas and the like, and is removed from the system. The firing residue remaining on the surface is removed together with the copper oxide film.

In the firing step of the recovery method of the present invention, the resin coating is oxidized and decomposed, and the copper wire surface is oxidized to form a copper oxide coating (Cu ₂ O coating) with a mechanically peeled thickness. Specifically, for example, the copper oxide film formed on the surface of the copper wire is fired so that the film thickness becomes 5 to 10 μm. Accordingly, the firing temperature is preferably a temperature at which the resin coating is oxidatively decomposed and the copper oxide film thickness is 5 to 10 μm.

  Since the copper oxide film on the surface of the copper wire is peeled off in the next step, if the thickness of the copper oxide film is thicker than 10 μm, the loss of recovered copper increases. By forming the copper oxide film to 10 μm or less, copper loss can be suppressed. On the other hand, when the thickness of the copper oxide film is less than 5 μm, mechanical peeling is difficult.

  In the recovery method of the present invention, after firing the resin-coated copper wire, the copper oxide film is mechanically peeled off together with the adhered firing residue to recover the copper wire. Because the copper oxide film formed on the surface of the copper wire by firing the resin-coated copper wire and the metal copper (copper wire) have different crystal structures, this interface part is brittle, vibration, mechanical external force, ultrasonic vibration in water Etc., the copper oxide film easily peels off. Although the baking residue of the resin coating adheres to the copper oxide film, the adhesion residue is peeled off together with the copper oxide film. Impurity metals (lead, iron, etc.) adhering to the copper wire are removed together with the copper oxide film.

  For example, a peeling machine having a peeling blade on the rotating shaft may be used as the peeling means. An example of a peeling machine is shown in FIG. In FIG. 1, the peeling machine 10 includes a vertical storage tank 11, a dust collector 12 is connected to the side wall of the storage tank 11, and an outlet 13 is provided at the tank bottom. Further, a rotating shaft 14 is provided upright inside the storage tank 11, and a plurality of separation blades 15 are attached to the rotating shaft 14. The peeling blade 15 is preferably made of soft plastic or cowhide.

  The crushed pieces obtained by crushing the resin-coated copper wire are fired, and the resin coating is oxidized (burned) and decomposed. The fired crushed pieces 20 are charged into the storage tank 11 of the peeling machine 10, and the peeling blades 15 are rotated by the rotating shaft 14 to stir the crushed pieces 20. By this stirring, the copper oxide film of the crushed pieces 20 is easily peeled off, and the copper oxide film powder, impurity metal powder, and the like are removed from the system by the dust collector 12. The copper wire exposed by removing the copper oxide film is collected from the outlet 13.

  An air table or an ultrasonic vibrator may be used as the peeling means. The fired resin-coated copper wire is placed in an air table, and the copper oxide film can be peeled off by applying air pressure. Moreover, the fired resin-coated copper wire is put into water and subjected to ultrasonic waves, and the copper oxide film can be peeled off by this ultrasonic vibration.

An example of processing steps based on the recovery method of the present invention is shown in FIG.
A resin-coated copper wire is wound around the stator of the motor. A member having a resin-coated copper wire, such as a stator, collected from an automobile, a household appliance, an industrial electric device, or the like is put into the crusher 30 to be crushed pieces. The crushed pieces are put into the magnetic separator 31 to separate the iron material. The crushed pieces from which the iron material has been separated are put into the firing furnace 33. Alternatively, the crushed pieces from which the iron material is separated are put into the wind power sorter 32 and light crushed pieces such as resin pieces are removed, and then put into the firing furnace 33.

  Since the resin-coated copper wire is wound on the crushed pieces, the crushed pieces are baked in the firing furnace 33 under the temperature conditions in which the resin coating of the crushed pieces is oxidatively decomposed and a copper oxide film is formed on the surface of the copper wires. Preferably, baking is performed so that the film thickness of the copper oxide film is 5 to 10 μm. By this baking treatment, the organic component of the resin coating is decomposed into carbon dioxide and the like and removed outside the furnace.

  The fired crushed pieces are put into a mechanical peeling means 34, for example, a peeling machine 10, an air table, an ultrasonic vibrator, etc., and the copper oxide film is peeled off from the copper wire together with the adhered residue, and the copper oxide film is removed. Collect the stripped copper wire pieces. On the other hand, the peeled copper oxide coating powder, iron powder, lead powder and other impurity metal powders are collected through the dust collector 35.

  The copper wire recovered by the method of the present invention has sufficiently removed the resin component and the impurity metal. Specifically, in the drawn copper wire, the amount of carbon after firing is around 10 ppm, the amount of hydrogen is around 2 ppm, It is copper with a quality close to the copper quality (99.9%) of the copper wire. In addition, the coil crushed material is processed, the amount of carbon and the amount of hydrogen after firing are about the same as the drawn copper wire, and the amount of residual iron and residual lead are also slight (Fe: 420 ppm, Pb: about 10 ppm) It is possible to recover copper having a quality close to the copper quality (99.9%) of the copper wire.

  In the recovery method of the present invention, the resin coating is oxidatively decomposed by baking at a temperature of about 400 ° C. to 500 ° C. in an air atmosphere, and a minimum amount of copper is oxidized to remove impurities adhering to the surface. Can do. Further, since the recovery method of the present invention is fired in an air atmosphere, there is no need to use a special atmosphere (an oxygen-free state, such as a nitrogen atmosphere or a vacuum atmosphere), and the running cost and equipment cost can be kept low. . Furthermore, since heat is generated when the resin coating is oxidatively decomposed (burned) in an air atmosphere, the energy cost for processing the coated copper wire can be reduced. The copper oxide film produced in the firing step is easily peeled off, and the processing cost can be reduced because the recovered copper wire does not require acid cleaning.

  If the stator of the motor is crushed with the resin-coated copper wire being wound, the iron fragments of the stator will be stuck into the resin coating or copper wire, and even the magnetic separator will not remove the iron fragments etc. Some of them are attached to the copper wire later, but metals other than copper (iron, lead, etc.) attached to the copper wire are removed together with the copper oxide film, so these impurity metals are easily removed. be able to.

The schematic sectional drawing of a peeling machine. The process flowchart based on the collection | recovery method of this invention. EPMA analysis photograph of the cross section of the fired copper wire.

Examples of the present invention are shown below together with comparative examples.
The carbon remaining in the copper wire was quantified by a combustion-infrared absorption method using a simultaneous carbon / sulfur analyzer (CSLS-600 manufactured by LECO). Hydrogen was quantified by an inert gas melting-thermal conductivity method using a hydrogen analyzer (RHEN-602 manufactured by LECO). Oxygen was quantified by an inert gas melting-infrared absorption method using a nitrogen / oxygen simultaneous analyzer (TCEN-600 manufactured by LECO). The purity of copper was quantified by electrogravimetry. Impurities remaining in copper were quantified with an inductively coupled plasma emission spectrometer (iCAP-6500 Duo manufactured by Thermo Fisher Scientific) after dissolving the sample in acid. The cross-section of the copper wire was subjected to surface analysis using an energy dispersive X-ray spectrometer (HITACHI SU8230 + Bruker QUANTAX).
The resin-coated copper wire A used in the examples and comparative examples is for televisions and is not a drawn copper wire, so iron and lead are not included in the coating. The resin-coated copper wire B is a copper wire drawn from the coil, and the iron powder and lead powder of the coil adhere to the coating during the drawing process. The coating resin for the copper wire A is a polyurethane resin, and the coating resin for the copper wire B is a polyester resin. The coating resin for the copper wire C is a formal resin, and the coating resin for the copper wire D is a polyesterimide resin.

[Example 1]
250 g of resin-coated copper wire A (components are shown in Table 1) was put in an electric furnace and baked for 1 hour under conditions of a temperature of 450 ° C. and an air flow rate of 1 L / min. The inside of the furnace was cooled to room temperature, and the fired copper wire was taken out. This baked copper wire was immersed in water, and ultrasonic waves were washed in water for 20 minutes to remove the oxide film. The results are shown in Table 2. In addition, a part of the copper wire after firing (before ultrasonic treatment) was collected, and the cross section of the copper wire was observed by EPMA analysis. This cross-sectional photograph is shown in FIG.
As shown in FIG. 3, an oxide film having a thickness of 5 to 10 μm is formed on the surface of the copper wire. This oxide film was confirmed to be copper oxide (Cu ₂ O) from the element ratio. Cracks are generated at the interface between the pure copper and the copper oxide film. As shown in Table 2, the amount of carbon after firing was 10 ppm, the amount of hydrogen was 2 ppm, and the resin coating was almost removed. The weight was reduced by 2.5% due to surface oxidation and the copper recovery yield was 97.5%. Moreover, the purity of the recovered copper was 99.9%, which was high-purity copper.

[Example 2 and Example 3]
The firing treatment and ultrasonic cleaning were performed in the same manner as in Example 1 except that the furnace temperature of the firing furnace was set to 470 ° C. (Example 2) and 420 ° C. (Example 3). The results are shown in Table 2. As shown in Table 2, the amount of carbon after the treatment is 12 to 13 pppm, the amount of hydrogen is 2 to 3 ppm, and the resin coating is almost removed. Since the firing temperature of Example 2 was higher than that of Example 1, the copper oxide film on the copper surface increased, and the copper recovery yield was 95.1%. Further, the purity of the recovered copper in both Example 2 and Example 3 was 99.9%.

Example 4
A baking treatment and ultrasonic cleaning were performed in the same manner as in Example 1 except that the baking time was set to 5 hours. The results are shown in Table 2. The amount of carbon after the treatment is 8 ppm, the amount of hydrogen is 2 ppm, and the resin coating is almost removed. The copper recovery yield was 97.5%, and the purity of the recovered copper was 99.9%.

[Comparative Example 1]
Baking treatment and ultrasonic cleaning were performed in the same manner as in Example 1 except that the firing atmosphere was changed to a nitrogen atmosphere (flow rate: 1 L / min). The results are shown in Table 2. Since the firing was performed under a nitrogen atmosphere, almost no copper oxide film was formed on the surface of the copper wire, and the fired residue remaining on the surface could not be peeled off even when the fired copper wire was ultrasonically cleaned. For this reason, the amount of carbon after the treatment was 5000 ppm, the amount of hydrogen was 210 ppm, and a large amount of resin coating firing residue remained.

[Comparative Example 2]
The baking treatment and ultrasonic cleaning were performed in the same manner as in Example 1 except that the furnace temperature of the baking furnace was set to 380 ° C. The results are shown in Table 2. Because the firing temperature is low to advance the oxidative decomposition of the resin coating and sufficiently form a copper oxide film on the surface of the copper wire for the type of coating resin, the surface of the copper wire that has been baked is ultrasonically cleaned. The remaining fired residue could not be peeled off, the amount of carbon after the treatment was 2300 ppm, the amount of hydrogen was 40 ppm, and a large amount of the fired residue of the resin coating remained.

[Comparative Example 3]
The baking treatment was performed in the same manner as in Example 1 except that the ultrasonic cleaning after the baking treatment was not performed. The results are shown in Table 2. Since ultrasonic cleaning is not performed, the firing residue adheres to the surface of the fired copper wire. For this reason, the amount of carbon and hydrogen in the firing residue is larger than that in Example 1.

  The firing time of Example 3 is 1 hour (baking temperature 420 ° C.), and the firing time of Example 4 is 5 hours (baking temperature 420 ° C.). It was confirmed that about 1 hour was sufficient.

  As shown in Comparative Example 1, when the resin-coated copper wire is baked in a nitrogen atmosphere and the resin is carbonized, a copper oxide film is not formed on the copper surface, so that the baking residue can be removed by peeling off the copper oxide film. It is difficult to recover high-purity copper because a large amount of baking residue remains. Moreover, as shown in Comparative Example 2, if the firing temperature is too low relative to the type of coating resin, the copper oxide film is not mechanically peeled off and a firing residue remains. As shown in Examples 1 to 4, when the copper oxide film is formed to have a mechanically peeled thickness, the baking residue can be easily removed together with the copper oxide film by ultrasonic cleaning in water.

  Specifically, when the coating resin is a polyurethane resin, the firing temperature of Comparative Example 2 is low to advance the oxidative decomposition of the resin coating to sufficiently form a copper oxide film on the surface of the copper wire, while the same kind of resin is used. At the firing temperatures of Examples 1 to 4 having a coating, the oxidative decomposition of the resin coating and the formation of the copper oxide film on the surface of the copper wire proceed sufficiently. Accordingly, for the copper wire A having a polyurethane resin coating, the firing temperature is preferably 420 ° C to 470 ° C. Thus, the firing temperature of the resin-coated copper wire is preferably a temperature at which the oxidative decomposition of the resin coating is advanced to sufficiently form a copper oxide film on the surface of the copper wire, depending on the type of the coating resin.

Example 5
50 g of resin-coated copper wire B (components shown in Table 1) was placed in an electric furnace and fired for 1 hour under conditions of a temperature of 450 ° C. and an air flow rate of 1 L / min. The inside of the furnace was cooled to room temperature, and the fired copper wire was taken out. This baked copper wire was immersed in water, and ultrasonic waves were washed in water for 20 minutes to remove the oxide film. The results are shown in Table 3.

[Comparative Example 4]
The resin-coated copper wire B was fired in the same manner as in Example 5 except that ultrasonic cleaning after the firing process was not performed. The results are shown in Table 3. Since ultrasonic cleaning is not performed, the firing residue is attached to the surface of the fired copper wire. For this reason, the amount of carbon and hydrogen in the firing residue is larger than that in Example 5, and the remaining amount of iron and lead There are many.

Example 6
50 g of a resin-coated copper wire C (components shown in Table 1) was placed in an electric furnace and baked for 1 hour under conditions of a temperature of 400 ° C. and an air flow rate of 1 L / min. The inside of the furnace was cooled to room temperature, and the fired copper wire was taken out. This baked copper wire was immersed in water, and ultrasonic waves were washed in water for 20 minutes to remove the oxide film. The results are shown in Table 3. The resin coating is oxidatively decomposed by the baking treatment, and the baking residue is removed by ultrasonic cleaning, so the amount of carbon and hydrogen after the treatment is small, and iron and lead attached to the surface of the copper wire together with the oxide film Since it is removed, the remaining amount of iron and lead after processing is small.

Example 7
50 g of a resin-coated copper wire D (components shown in Table 1) was placed in an electric furnace and fired for 1 hour under conditions of a temperature of 500 ° C. and an air flow rate of 1 L / min. The inside of the furnace was cooled to room temperature, and the fired copper wire was taken out. This baked copper wire was immersed in water, and ultrasonic waves were washed in water for 20 minutes to remove the oxide film. The results are shown in Table 3. The resin coating is oxidatively decomposed by the baking treatment, and the baking residue is removed by ultrasonic cleaning, so the amount of carbon and hydrogen after the treatment is small, and iron and lead attached to the surface of the copper wire together with the oxide film Since it is removed, the remaining amount of iron and lead after processing is small.

10-Peeling machine, 11-Storage tank, 12-Dust collector, 13-Takeout port, 14-Rotating shaft, 15-Peeling blade, 20-Crushing piece, 30-Crushing machine, 31-Magnetic sorter, 32-Wind sorter 33-firing furnace, 34-peeler, 35-dust collector.

Claims (5)

The resin-coated copper wire is baked at a temperature at which the resin coating is oxidized and decomposed without being carbonized in an air atmosphere, and the copper oxide film is mechanically peeled on the surface of the copper wire to a thickness of 5 to 10 μm. A copper recovery method, wherein after the baking, the copper oxide film is mechanically peeled off together with the attached baking residue to recover the copper wire. The copper recovery method according to claim 1, wherein a copper wire having a polyester resin coating or a copper wire having a polyurethane resin coating is fired at 420 ° C to 470 ° C in an air atmosphere. The method for recovering copper according to claim 1 or 2, wherein the fired resin-coated copper wire is subjected to ultrasonic cleaning in water, and the copper oxide film is peeled off together with the adhered firing residue. The copper oxide film is peeled off from the fired resin-coated copper wire together with the attached fired residue using a peeling machine having a peeling blade on the rotating shaft or using an air table. Copper recovery method. The member having the resin-coated copper wire is crushed, the crushed pieces are magnetically separated to separate the iron material, the separated crushed pieces are put in a firing furnace, the resin coating is oxidatively decomposed, and the copper oxide film is formed on the copper wire surface Any one of Claims 1-4 which baked at the temperature to form, put the baked crushing piece in a mechanical peeling means, peels a copper oxide film with the attached baking residue, and collects a copper wire . The method for recovering copper described in 1.

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