WO2023175677A1

WO2023175677A1 - Metal regeneration method and metal-powder-containing resin molded body manufacturing method

Info

Publication number: WO2023175677A1
Application number: PCT/JP2022/011349
Authority: WO
Inventors: 大輔亀井
Original assignee: 三菱電機株式会社
Priority date: 2022-03-14
Filing date: 2022-03-14
Publication date: 2023-09-21
Also published as: JPWO2023175677A1

Abstract

Provided is a metal regeneration method including a step (S10) for preparing a metal mixture in which multiple types of non-magnetic metal bodies having different shapes from each other are mixed and a step (S20) for pulverizing the metal mixture into metal powder. In the step (S20) for pulverizing, the particle diameters of the entire metal powder are reduced so as to be equal to or less than a first value; first metal powder having the particle diameters that are equal to or less than a second value is removed from the entire metal powder, the second value being less than the first value; and second metal powder having particle diameters that are greater than the second value and equal to or less than the first value is recovered. The above metal regeneration method additionally includes a step (S30) for removing, from the second metal powder, third metal powder having particle diameters that are equal to or greater than a third value and recovering fourth metal powder having particle diameters that are greater than the second value and less than the third value. The third value is greater than the second value and less than the first value.

Description

Method for recycling metal and method for manufacturing resin molded body containing metal powder

The present disclosure relates to a method for recycling metal and a method for manufacturing a metal powder-containing resin molded body.

In recent years, electrical appliances such as air conditioners, televisions, refrigerators, and washing machines that are used in ordinary households in Japan have been changed due to legal regulations related to global environmental protection such as the Home Appliance Recycling Law, or from the viewpoint of effective use of materials. Promoting the recycling of component parts has become an important issue.

The following methods are known as methods for recovering valuables such as plastics and metals from recovered electrical appliances.

First, the components of the collected electrical appliances are classified according to their size and material, and then each is coarsely ground into pieces ranging from several centimeters to several tens of centimeters square using a crusher.

Second, magnetic metals such as iron are recovered from the coarse crushed pieces using a magnetic separator.
Third, metals (eg, non-magnetic metals) such as aluminum (Al), copper (Cu), and stainless steel (SUS) are recovered from the remaining coarse crushed pieces using an eddy current separator.

Fourth, from the remaining coarse crushed pieces, foams such as urethane with low specific gravity and metal pieces and metal wire with high specific gravity are recovered by air sorting.

The final residue after the above sorting is recovered as recovered plastic. Several tenths of recovered plastics are recovered as industrial waste or thermal recycling.

Incidentally, as a method for recovering metals as valuable materials, a sorting method using a color sorter and a specific gravity sorter is known. In addition, Japanese Patent Application Laid-open No. 7-178385 (Patent Document 1) describes a method for recovering valuables from printed circuit boards, focusing on the properties of the material. A method of sorting glass fibers and resins, which are easily brittle substances, by crushing and classifying them is shown.

Japanese Unexamined Patent Publication No. 7-178385

Even after metals are recovered using the above-mentioned magnetic separator, eddy current separator, etc., the recovered plastic still contains a maximum of about 5% by weight of multiple types of metal bodies that are valuable materials.

Furthermore, in the sorting method using color or specific gravity, it is difficult to separate and sort multiple types of metals that have small differences in color or specific gravity. For example, there is a small difference between the specific gravity of copper wire, which is a valuable resource, and the specific gravity of enamelled wire, which has a thin polymer film formed around the copper wire. Therefore, it is difficult to separate and recover copper wire and enameled wire from recovered plastic using the specific gravity sorting method.

In this way, methods for separating and recycling valuable metals from electrical appliances are required to further improve the recycling rate.

Note that Patent Document 1 is a method for separating metals from glass fibers and resins, and does not describe how to select and recover specific metals from a mixture of metals.

One objective of the present disclosure is to provide a metal regeneration method that can regenerate a specific type of metal with higher efficiency from a mixture containing multiple types of metal bodies.

Furthermore, as described above, metals recycled by conventional recycling methods include multiple types of metals. Therefore, in order to manufacture a metal powder-containing resin molded body containing a specific type of metal powder with high purity, a process of refining the metal recycled by a conventional recycling method is required.

Another object of the present disclosure is to provide a method for producing a metal powder-containing resin molded body that can produce a metal powder-containing resin molded body that contains a specific type of metal powder in high purity without refining the metal. It is in.

A method for recycling metal according to an embodiment of the present disclosure includes a step of preparing a metal mixture in which multiple types of metal bodies having different shapes are mixed, and a step of pulverizing the metal mixture into metal powder. In the pulverizing step, the particle size of all the metal powders is set to be equal to or less than a first value, and the first metal powder whose particle size is equal to or less than a second value smaller than the first value is extracted from all the metal powders. The second metal powder is removed and the second metal powder has a particle size larger than the second value and less than or equal to the first value. The metal regeneration method described above includes removing a third metal powder whose particle size is larger than the third value from the second metal powder, and removing a fourth metal powder whose particle size is larger than the second value and smaller than the third value. The method further includes a step of collecting the powder. The third value is greater than the second value and less than the first value.

According to the present disclosure, it is possible to provide a metal regeneration method that can regenerate a specific type of metal with higher efficiency from a mixture containing multiple types of metal bodies.

3 is a flowchart showing a metal regeneration method according to the present embodiment. FIG. 2 is a diagram for explaining a crusher used in the metal regeneration method according to the present embodiment. It is a graph showing the wire diameter distribution of copper wire contained in the metal mixture introduced into the pulverizing step in the example. It is a graph showing the wire diameter distribution of enamelled wire contained in the metal mixture introduced into the pulverizing step in the example. 2 is a graph showing the wire diameter distribution of stainless steel wires included in the metal mixture input to the pulverizing process in Examples. It is a graph showing the maximum length distribution of aluminum plates contained in the metal mixture introduced into the pulverizing process in Examples. 1 is a flowchart showing a method for manufacturing a metal powder-containing resin molded body according to the present embodiment.

Embodiments of the present disclosure will be described below with reference to the drawings.
<Metal recycling method>
The metal regeneration method according to the present embodiment is a method of regenerating a predetermined nonmagnetic metal as metal powder from a metal mixture in which a plurality of types of nonmagnetic metal bodies having different shapes are mixed. In other words, the metal regeneration method according to the present embodiment is a method of manufacturing a predetermined nonmagnetic metal as metal powder using a metal mixture in which multiple types of nonmagnetic metal bodies having different shapes are mixed as a starting material. It is.

In this specification, non-magnetic metal means a metal that does not have ferromagnetism, and is a concept that includes weakly magnetic metals. The nonmagnetic metal body means a structure made of nonmagnetic metal, and includes a nonmagnetic metal wire and a nonmagnetic metal plate. A non-magnetic metal wire is a wire whose main constituent material is a non-magnetic metal and does not have a plastic film. A non-magnetic metal plate is a plate material whose main constituent material is a non-magnetic metal and does not have a plastic film. Examples of non-magnetic metal wires are copper (Cu) wire, stainless steel (SUS) wire, and enameled wire. An example of a non-magnetic metal plate is an aluminum (Al) plate. Copper wire means a wire made only of copper or copper alloy. Enameled wire refers to a wire made of copper wire and an enamel film covering the surface of the copper wire. The enamel film is formed by baking an enamel paint applied to the surface of the core wire.

The metal powder produced by the metal regeneration method according to the present embodiment is copper powder.
As shown in FIG. 1, in the metal regeneration method according to the present embodiment, first, a metal mixture in which a plurality of types of non-magnetic metal bodies having different wire diameter distributions are mixed is prepared (step (S10). )). The metal mixture can be prepared by any method, but for example is produced from recycled plastic by the following method.

First, various parts obtained by dismantling electrical appliances such as refrigerators, washing machines, and air conditioners are roughly crushed into pieces ranging from several centimeters to several tens of centimeters square by a crushing device. Here, various parts include large metal parts such as compressors, heat exchangers, and motors, large plastic molded parts such as refrigerator cases, washing machine water tanks, control boards, cords, and other parts. included.

Next, ferromagnetic metals such as iron are removed from the roughly crushed pieces using a magnetic separator, weakly magnetic metals such as aluminum, copper, and stainless steel are removed using an eddy current separator, and the specific gravity is Small foams such as urethane and heavy metals are removed. The final residue left after these sorting processes is recovered as recycled plastic. The recovered plastic includes multiple types of nonmagnetic metal bodies, at least one type of coated metal wire, and multiple types of plastic pieces.

The coated metal wire means a wire having a core wire made of a non-magnetic metal and a plastic film covering the surface of the core wire. An example of a coated metal wire is a coated copper wire that is composed of a copper wire and a plastic film that covers the surface of the copper wire. The material constituting the plastic film is, for example, polyvinyl chloride (PVC).

Note that the plurality of types of nonmagnetic metal bodies contained in the recovered plastic are, for example, three types of nonmagnetic metal wires: copper wire, enameled wire, and stainless steel, and an aluminum plate. The at least one coated metal wire is, for example, a coated copper wire. Copper wire, enamelled wire, and coated copper wire have been used for wiring in electrical appliances, for example. Stainless steel wire includes those that have been incorporated into plastics as piano wire (spring steel) in electrical appliances. Aluminum plates include those used for capacitor electrodes in electrical appliances.

The wire diameter distributions of each of the plurality of copper wires, the plurality of enamelled wires, and the plurality of stainless steel wires contained in the recovered plastic are different from each other. The average value of the wire diameters of the plurality of copper wires is larger than the average value of the respective wire diameters of the plurality of enamelled wires and the average value of the respective wire diameters of the plurality of stainless steel wires. The average maximum length of the plurality of aluminum plates contained in the recovered plastic is longer than the average value of the wire diameters of each of the copper wire, enamelled wire, and stainless steel wire. Note that the maximum length of the aluminum plate means the maximum value among the external dimensions of the aluminum plate.

Next, a first mixture, which is a mixture containing a plurality of types of non-magnetic metal wires and plastic pieces whose dimensions are within a predetermined range, is sorted and recovered from the recovered plastic using a sieve (step (S11)). . Preferably, the copper wire, enamelled wire, stainless steel wire, aluminum plate, coated copper wire, and plastic pieces to be sorted and collected as the first mixture are separated by a sieve with an opening of 3.5 mm or more and less than 15.0 mm. It is something. The opening is in accordance with the JIS standard (JIS Z 8801-1). If the recovered plastic contains a large amount of non-magnetic metal wire separated by a sieve with a mesh opening larger than the upper limit of the above range, the recovered plastic is sent to a crusher as a pre-process to this step (S11). The coarsely crushed recovered plastic is then input into this step (S11), or the non-magnetic metal wire selected in this step (S11) as having a maximum length larger than the upper limit of the above range is crushed. It is preferable that the first mixture is coarsely pulverized in an apparatus, and the coarsely pulverized nonmagnetic metal wire is sieved again to selectively recover the first mixture. The sieve used in this step is, for example, an ultrasonic vibrating sieve.

Next, a second mixture containing a plurality of types of non-magnetic metal bodies and coated metal wires is sorted and recovered from the first mixture by centrifugation (step (S12)). Centrifugation is performed, for example, by applying centrifugal force to the first mixture using a water stream and utilizing the difference in specific gravity in the water stream. As a result, plastic pieces with relatively low specific gravity are removed from the first mixture, and copper wire, enameled wire, stainless steel wire, aluminum plate, coated copper wire, and plastic pieces with relatively high specific gravity are removed from the second mixture. They will be sorted and collected as such.

For example, the sum of the weight ratios of the copper wire, enameled wire, stainless steel wire, and aluminum plate contained in the second mixture is about 5% by weight. The weight ratio of the coated copper wire contained in the second mixture is about 35% by weight. The weight ratio of the plastic pieces contained in the second mixture is about 60% by weight. Plastic pieces are mainly made of polypropylene (PP), polystyrene (PS), acrylonitrile butadiene styrene (ABS) copolymer, polyoxymethylene (Pol), etc. yoxymethhylene: POM), polybutyl ethylene terephthalate It is a plastic flake made of polybutyleneterephthalate (PBT), polycarbonate (PC), PC/ABS mixed alloy, or PVC.

Next, the metal mixture, which is a mixture of a plurality of types of non-magnetic metal wires and non-magnetic metal plates, is sorted and recovered from the second mixture (step (S13)). In this step (S13), for example, wet specific gravity sorting is first performed, and then color sorting is performed. Wet gravity sorting uses a solvent that has a higher specific gravity than the plastic pieces. As a result, plastic pieces contained in the second mixture are removed, and copper wire, enameled wire, stainless steel wire, aluminum plate, and coated copper wire are sorted and recovered as a third mixture. The specific gravity of the solvent used in wet specific gravity screening is greater than each of PP, PS, ABS, POM, PBT, PC, PC/ABS, and PVC, and smaller than each of multiple types of nonmagnetic metals. Although any value may be used, it is, for example, about 1.5.

In color sorting, coated copper wire is removed from the third mixture based on the color observed when visible light is irradiated to the third mixture sorted and collected by wet specific gravity sorting, and copper wire, enamelled wire, and stainless steel are separated. A metal mixture of wires and aluminum plates is sorted and collected. The color of the plastic film of the coated metal wire is different from the color of the core wire (metal color). Therefore, the coated copper wire can be distinguished from the non-magnetic metal wire based on the color observed when a mixture containing the non-magnetic metal wire and the coated copper wire is irradiated with visible light.

The metal mixture includes a metal mass in which copper wire, enameled wire, stainless steel wire, and aluminum plate are entangled with each other. It is thought that this metal lump is formed when centrifugation by water flow is performed in the previous step (S12).

In the above steps (S11) to (S13), the wire diameter of each of the plurality of types of non-magnetic metal wires does not increase or decrease. Therefore, through the above steps (S11) to (S13), a metal mixture is prepared in which a plurality of types of nonmagnetic metal wires having different wire diameter distributions are mixed. The above steps (S11) and (S12) are effective from the viewpoint of increasing the recovery efficiency of the metal mixture in the step (S13). The step (S13) is effective from the viewpoint of increasing work efficiency in the subsequent step (S20) of pulverizing the metal mixture into metal powder. If the coated copper wire is crushed in the post-process (S20), the plastic film may generate heat, making it impossible to continue crushing. A method of pulverizing while cooling with liquid nitrogen or the like to suppress heat generation is also considered, but if the above step (S13) is not performed, the weight ratio of the coated copper wire in the third mixture is high and the heat value is high. The cooling effect is small because the amount of water increases. Furthermore, if the above step (S13) is not performed, the weight ratio of the coated copper wire in the third mixture becomes high, so there is a possibility that the regeneration efficiency of the copper powder decreases. Additionally, instead of the above step (S13), a method of carbonizing the plastic film by heating the third mixture in a heating furnace at 700°C or higher may be considered, but harmful gases may be generated when the plastic burns. There is sex. Therefore, the above step (S13) is advantageous compared to other methods even in consideration of the environment.

In the metal regeneration method according to the present embodiment, secondly, the metal mixture prepared in the previous step (S10) is pulverized into metal powder (step (S20)). In this step (S20), the metal mixture is pulverized into metal powder by a pulverizer that applies impact force and shear force to the metal mixture. In other words, the pulverization in this step shortens the wire diameter and wire length of the non-magnetic metal wire so that the particle size of the metal powder obtained by pulverizing the non-magnetic metal wire is smaller than the wire diameter of the non-magnetic metal wire. It is also done so that it becomes smaller. FIG. 2 shows an example of a crusher.

The crusher 10 shown in FIG. 2 includes a supply section 11, a crushing section 12, and a classifying section 13. The supply section 11 is a section to which the metal mixture is supplied from the outside. The supply unit 11 is provided to apply vibration to the metal mixture to loosen metal lumps contained in the metal mixture. The crushing section 12 is provided to apply impact force and shear force to the metal mixture. The crushing section 12 is, for example, a hammer mill, a cutter mill, or a screen mill having a screen on the outlet side (classifying section 13) relative to the rotating hammer or cutter blade in the hammer mill or cutter mill. The material constituting the hammer or cutter blade of the crushing section 12 is harder than the non-magnetic metal to be crushed. The material constituting the hammer or cutter blade of the crushing section 12 is, for example, cemented carbide. The Vickers hardness of copper is 60 to 120 HV, the Vickers hardness of stainless steel is 200 to 500 HV, and the Vickers hardness of aluminum is 20 to 40 HV. In contrast, the Vickers hardness of cemented carbide is 1700 to 2100 HV. Therefore, the particle size of the metal powder of the non-magnetic metal wire after pulverization is not affected by the hardness of each metal to be pulverized, but depends on the wire diameter of each metal. The pulverized metal powder has a fractured surface or a sheared surface.

In the classification section 13, the metal powder crushed in the crushing section 12 is classified according to its particle size. The classification section 13 includes, for example, an ultrasonic vibrating sieve.

In the classification section 13, the metal powder is classified into metal powder whose particle size is less than or equal to the first value A, and metal powder whose particle size is larger than the first value A. The metal powder whose particle size is larger than the first value A is supplied to the supply section 11 again, is crushed again in the crushing section 12 under the same conditions as when it was first crushed, and is classified in the classification section 13. be done. This process is repeated until the particle sizes of all metal powders become equal to or less than the first value A. As a result, in this step (S20), the particle diameters of all metal powders are set to be equal to or less than the first value A.

In this step (S20), first metal powder whose particle size is less than or equal to a second value B, which is smaller than the first value A, is removed from all the metal powder whose particle size is less than or equal to the first value A. , a second metal powder whose particle size is greater than the second value B and less than or equal to the first value A is recovered.

In this step (S20), the particle size distribution of the metal powder after pulverization differs depending on the wire diameter distribution of the non-magnetic metal wire and the maximum length distribution of the non-magnetic metal plate in the metal mixture before pulverization. As mentioned above, the wire diameter distribution of the non-magnetic metal wire and the maximum length distribution of the non-magnetic metal plate in the metal mixture before pulverization differ depending on the type of non-magnetic metal, so the metal powder after pulverization differs depending on the type of non-magnetic metal. The particle size distribution also differs depending on the type of nonmagnetic metal.

Non-magnetic metal wires tend to be cut in the wire length direction after the unpulverized lump breaks up, so by being crushed repeatedly, the wire length gradually becomes shorter and becomes powder-like. It was confirmed that when a non-magnetic metal plate is repeatedly crushed, it gradually becomes finely rectangular and linear, and when it is crushed repeatedly, the line length gradually becomes shorter and becomes powder-like. Therefore, regarding the particle size of metal powder after pulverization, the particle size of metal powder derived from a non-magnetic metal wire is the wire diameter before pulverization, and the particle size of metal powder derived from a non-magnetic metal plate is the maximum length before pulverization. It is thought that it depends.

The first metal powder is a powder mixture obtained by pulverizing non-magnetic metal wires having a relatively small wire diameter among the plurality of types of non-magnetic metal wires contained in the metal mixture. The first metal powder is a mixture of a powder obtained by grinding an enameled wire and a powder obtained by grinding a stainless steel wire. The second metal powder is a powder obtained by pulverizing a non-magnetic metal wire having a relatively large wire diameter among multiple types of non-magnetic metal wires contained in the metal mixture, and a non-magnetic metal plate having a relatively long maximum length. is a mixture of ground powders. The second metal powder is a mixture of a powder obtained by pulverizing a copper wire (copper powder) and a powder obtained by pulverizing an aluminum plate (aluminum powder).

In the metal regeneration method according to the present embodiment, thirdly, from the second metal powder formed in the previous step (S20), a third metal whose particle size is equal to or larger than the third value C is passed through a sieve. The powder is removed and fourth metal powder whose particle size is larger than the second value B and smaller than the third value C is recovered (step (S30)). The third value C is larger than the second value B and smaller than the first value A. The sieve used in this step (S30) is, for example, an ultrasonic vibrating sieve.

The third metal powder, which has a relatively large particle size among the second metal powders, is a non-magnetic metal powder whose maximum length is longer than the wire diameter of other non-magnetic metal wires among the multiple types of non-magnetic metal bodies contained in the metal mixture. It is a powder obtained by crushing a metal plate. The third metal powder is aluminum powder. The fourth metal powder, which has a relatively small particle size among the second metal powders, is a powder obtained by pulverizing a non-magnetic metal wire having a relatively large wire diameter among the multiple types of non-magnetic metal wires contained in the metal mixture. It is a mixture of The fourth metal powder is copper powder.

Each value of the first value A and the second value B used in the above step (S20) and the third value C used in the above step (S30) is determined based on the plurality of types contained in the recovered plastic. It is set according to the wire diameter distribution of the non-magnetic metal wire and the maximum length distribution of the non-magnetic metal plate in order to increase the recovery rate of metal powder made of a specific type of non-magnetic metal body from the non-magnetic metal body. .

When the non-magnetic metal bodies contained in the recovered plastic are copper wire, enameled wire, stainless steel wire, and aluminum plate, the first value A is preferably set to 1 mm or less. When the first value A is larger than 1 mm, metal lumps that are not broken down in the supply section 11 are not broken down by the crushing section 12 and are discharged to the classification section 13 more frequently. Preferably, the first value A is 500 μm or more. When the first value A is smaller than 500 μm, all the metal powder becomes too fine and classification in the classification section 13 becomes difficult.

When the non-magnetic metal bodies contained in the recovered plastic are copper wire, enameled wire, stainless steel wire, and aluminum plate, and the first value A is 1 mm, the second value B is set to 45 μm or more. is preferable. When the second value B is smaller than 45 μm, the fourth metal powder having a particle size larger than the second value B contains Cu powder formed by grinding the enameled wire and Fe powder formed by grinding the stainless steel wire. A large amount of Cu powder is contained, and as a result, the weight ratio of the Cu powder, which is obtained by pulverizing the copper wire in the fourth metal powder, decreases. Preferably, the second value B is 200 μm or less. When the second value B is larger than 200 μm, the weight ratio of the Cu powder obtained by pulverizing the copper wire in the fourth metal powder increases, but the yield thereof decreases.

When the non-magnetic metal bodies contained in the recovered plastic are copper wire, enameled wire, stainless steel wire, and aluminum plate, and the first value A is 1 mm, the third value C is 500 μm or less. preferable. If the third value C is larger than 500 μm, the fourth metal powder whose particle size is less than the third value C will contain a large amount of Al powder obtained by crushing an aluminum plate, and as a result, The weight ratio of the Cu powder formed by pulverizing the copper wire in the four metal powders decreases. Preferably, the third value C is 350 μm or more. When the third value C is smaller than 350 μm, the weight ratio of the Cu powder obtained by pulverizing the copper wire in the fourth metal powder increases, but the yield thereof decreases.

Note that the above-mentioned trends regarding the first value A, the second value B, and the third value C are derived from the results of an evaluation test of the copper powder regeneration method described below.

As described above, according to the metal regeneration method according to the present embodiment, a specific type of non-magnetic metal body is recycled as metal powder from a metal mixture in which multiple types of non-magnetic metal bodies are mixed. As an example, in the metal recycling method according to the present embodiment, copper powder can be recycled from a metal mixture containing a copper wire, an enameled wire, a stainless steel wire, and an aluminum plate.

The present inventor focused on the fact that the shape distributions (wire diameter distribution and maximum length distribution) of multiple types of non-magnetic metal wires and non-magnetic metal plates contained in recovered plastic were different from each other, and pulverized a mixture of these. We discovered that the particle size distribution of each non-magnetic metal powder obtained by pulverization differs from each other due to the difference in shape distribution before crushing, and that as a result, metal powder made of a specific type of non-magnetic metal can be selectively recovered. Ta.

The present inventor has determined that the first value A, the second value B, and the third value are determined according to the wire diameter distribution of multiple types of nonmagnetic metal wires and the maximum length distribution of the nonmagnetic metal plate contained in the recovered plastic. It has been confirmed that by appropriately setting each value C, the recovery rate of metal powder made of a specific type of non-magnetic metal can be increased. Details will be described later.

<Evaluation test of copper powder regeneration method>
In this evaluation test, the effectiveness of an example of each combination of the first value A, the second value B, and the third value C in the metal regeneration method according to the present embodiment was evaluated. In this evaluation test, the first value A was 1 mm, the second value B was 45 μm, and the third value C was 500 μm.

First, a metal mixture containing only a copper wire, an enameled wire, a stainless steel wire, and an aluminum plate was prepared through the above steps (S11) to (S13). The metal mixture used was separated using a sieve with openings of 3.5 mm or more and 15.0 mm or less. The opening is in accordance with the JIS standard (JIS Z 8801-1).

The weight ratio of each of the copper wire, enameled wire, and stainless steel wire contained in the metal mixture was measured using a digital balance after confirming the composition using a fluorescent X-ray analyzer. As shown in Table 1, in the metal mixture, the copper wire was 80% by weight, the enameled wire was 3% by weight, the stainless steel wire was 6% by weight, and the aluminum plate was 11% by weight.

The wire diameter distribution of each of the copper wire, enameled wire, and stainless steel wire contained in the metal mixture, and the maximum length distribution of the aluminum plate contained in the metal mixture were measured using a digital micrometer and calipers. 3 to 6 show the results of each measurement. The horizontal axis in each of Figures 3 to 5 indicates the wire diameter (unit: μm) of the copper wire, enameled wire, and stainless steel wire, and the vertical axis in each of Figures 3 to 5 indicates the abundance ratio of each wire diameter. (frequency). The horizontal axis in FIG. 6 indicates the maximum length (unit: μm) of the aluminum plate, and the vertical axis in FIG. 6 indicates the abundance ratio (frequency) of each maximum length. The wire diameter of the copper wire contained in the metal mixture is 70 μm or more and 800 μm or less, the wire diameter of the enamelled wire is 80 μm or more and 800 μm or less, the wire diameter of the stainless steel wire is 150 μm or more and 900 μm or less, and the wire diameter of the aluminum plate is The length was 10,000 μm or more and 25,000 μm or less.

As shown in FIG. 3, the copper wires contained in the metal mixture included one group with a wire diameter of less than 450 μm and one group with a wire diameter of more than 650 μm. Moreover, among the copper wires of one group having wire diameters of less than 450 μm, the wire diameters were relatively uniformly distributed among each class. The average value of the wire diameter of the copper wire was about 320 μm.

On the other hand, from the wire diameter distribution of the enameled wires shown in FIG. 4, it was confirmed that the wire diameters of each enameled wire were distributed unevenly within a relatively narrow range of 250 μm or less. The average wire diameter of the enameled wire was about 230 μm. From the wire diameter distribution of the stainless steel wires shown in FIG. 5, it was confirmed that the wire diameters of each stainless steel wire were unevenly distributed within a relatively narrow range of 200 μm or less. The average wire diameter of the stainless steel wire was about 240 μm.

Further, as shown in FIG. 6, the maximum length of the aluminum plate was widely distributed from less than 12,000 μm to 24,000 μm or less, but the average value of the maximum length of the aluminum plate was about 16,000 μm.

Next, in accordance with the above step (S20), the metal mixture is vibrated using the hopper HLF-30 as a supply section to break up the metal lumps, and then the metal mixture is was crushed. The rotating blade was a blunt blade made of cemented carbide. The rotation speed of the rotary blade was 1000 rpm. The clearance between the rotary blade and the inner wall of the crushing section was 0.5 mm. The opening shape of each hole in the screen was round, and the hole diameter (opening) of the screen was 1 mm.

While pulverization was performed under the above conditions, the metal powder that passed through the screen was classified using an ultrasonic vibrating sieve machine CB50UR-1S as a classification section. Here, the second value B was 45 μm. Specifically, the first metal powder having a particle size of 45 μm or less was removed from the metal powder that passed through the screen. Furthermore, metal powder with a particle size larger than 1 mm that did not pass through the screen was returned to the supply section and subjected to the above-mentioned vibration, crushing, and classification in this order. This series of steps was repeated until all the metal powder passed through the screen.

Next, according to the above step (S30), among the second metal powders with a particle size larger than 45 μm classified as above using an ultrasonic vibrating sieve machine CB50UR-1S, those with a particle size of 500 μm or more are classified. A certain third metal powder was removed, and fourth metal powder having a particle size of less than 500 μm was sorted and collected.

Next, for each of the first metal powder, third metal powder, and fourth metal powder obtained as described above, the purity of Cu, Al, and iron (Fe) was determined using a fluorescent X-ray analyzer. It was measured using Specifically, 0.5 g was extracted from each of the first metal powder, third metal powder, and fourth metal powder, and the weight ratio of Cu, Al, and Fe in each extracted metal powder was analyzed by fluorescent X-ray analysis. Measured using a device. In addition to Cu, Al, and Fe, each metal powder contains, for example, manganese (Mn), nickel (Ni), cobalt (Co), zinc (Zn), barium (Ba), tin (Sn), and chromium (Cr). , titanium (Ti), calcium (Ca), and vanadium (V) are each contained less than 0.1% by weight, but these are ignored and the sum of the weights of Cu, Al, and Fe is taken as 100%.Cu, Each weight ratio of Al and Fe was calculated.

Furthermore, using the measurement results of the particle size distribution of metal powder obtained when copper wire and enameled wire are individually pulverized, the weight ratio of Cu powder due to copper wire and the calculated weight ratio of Cu are determined. The weight ratio of Cu powder due to the enameled wire was estimated. The particle size of the metal powder obtained by pulverizing the copper wire alone was overall larger than the particle size of the metal powder obtained by pulverizing the enameled wire alone. This is considered to be due to the fact that the average wire diameter of the copper wire before pulverization is larger than the average wire diameter of the enamelled wire before pulverization, as described above.

In addition, the calculated weight ratio of Al was taken as the weight ratio of Al powder due to the aluminum plate, and the calculated weight ratio of Fe was taken as the weight ratio of Fe powder due to the stainless steel wire.

The calculation results are shown in Table 2.

As shown in Table 2, the weight ratio of the Cu powder that is estimated to be attributable to the copper wire in the fourth metal powder is 92%, and the weight ratio of the copper wire in the metal mixture before pulverization and the This was about 10% higher than the weight ratio of Cu powder, which is estimated to be caused by the copper wire in the first metal powder and the third metal powder. In addition, Cu powder, which is estimated to be caused by the enamelled wire, was measured only in the first metal powder, but not in the third metal powder and fourth metal powder (i.e., the second metal powder). .

Furthermore, as shown in Table 2, Fe powder was measured only in the first metal powder and the third metal powder, but not in the fourth metal powder. Al powder was measured from each of the first metal powder, third metal powder, and fourth metal powder, but the weight ratio of Al powder in the fourth metal powder was different from that in the first metal powder and third metal powder. The weight ratio of Al powder was lower than that of Al powder.

From the results shown in FIGS. 3 to 6 and Tables 1 and 2, it can be seen that the first value A is 1 mm, the second value B is 45 μm, and the third value C is 500 μm, and the metal is recycled according to this embodiment. When the method is carried out, the fourth metal powder contains Cu powder, which is estimated to be caused by the enamelled wire, Fe powder, which is caused by the stainless steel wire, and aluminum, compared to the first metal powder and the third metal powder. It was confirmed that the weight ratio of Al powder, which is attributed to the plate, is the lowest, and the weight ratio of Cu powder, which is estimated to be attributed to the copper wire, is the highest.

The reason why the above test results were obtained is considered as follows.
First, in the above step (S20), each non-magnetic metal wire in the metal mixture is pulverized under the same conditions, so that the particle size distribution of the metal powder obtained by pulverizing the non-magnetic metal wire is the same as that before pulverization. This is approximately the same as the wire diameter distribution of each non-magnetic metal wire. Therefore, based on the wire diameter distribution of each non-magnetic metal wire shown in Figs. The particle size distribution of the Fe powder obtained by pulverizing the copper wire is different from the particle size distribution of the Cu powder obtained by pulverizing the copper wire, and is biased in a relatively narrow range. In particular, under the pulverization conditions where the first value A is 1 mm, the particle size distribution of the Cu powder obtained by pulverizing the enameled wire and the Fe powder obtained by pulverizing the stainless steel wire is biased to a narrow range of 45 μm or less. As a result, under the pulverization conditions where the first value A is 1 mm, and the second value B is 45 μm, the second metal powder recovered as having a particle size larger than the second value B (the third metal powder The weight ratio of the Cu powder obtained by pulverizing the enameled wire and the Fe powder obtained by pulverizing the stainless steel wire in the metal powder and the fourth metal powder can be made sufficiently low.

Furthermore, aluminum exists as a plate in the metal mixture, and its maximum length is extremely large compared to the wire diameter of the non-magnetic metal wire. Therefore, in the step (S20), the particle size of the Al powder obtained by pulverizing the aluminum plate is larger than the particle size of the metal powder obtained by pulverizing each nonmagnetic metal wire. In particular, under the pulverization conditions where the first value A is 1 mm, the particle size distribution of the Al powder is biased to a range larger than 500 μm. As a result, under the grinding conditions where the first value A is 1 mm, and the third value C is 500 μm, aluminum is contained in the fourth metal powder recovered as having a particle size smaller than the third value C. The weight ratio of Al powder obtained by pulverizing the plate can be made sufficiently low.

In the fourth metal powder regenerated from the metal mixture by the metal regeneration method according to the present embodiment, the purity (weight ratio) of the Cu powder is high. Therefore, according to the metal recycling method according to the present embodiment, a copper polishing process for increasing the purity of copper, which is generally performed in methods of recovering copper from recovered plastic, is not necessary. Since the refined copper process requires a large amount of energy, when regenerating copper powder using the metal regeneration method according to the present embodiment, energy savings can be achieved compared to the conventional recovery method in which the refined copper process is performed. can be realized.

Further, as described above, the Cu powder in the fourth metal powder regenerated from the metal mixture by the metal regeneration method according to the present embodiment has a high purity (weight ratio), and the Cu powder formed by pulverizing copper wire has a high purity (weight ratio). It consists only of powder and is separated from Cu powder, which is made of crushed enamelled wire. Therefore, the Cu powder in the fourth metal powder is suitable for antibacterial materials. In particular, when a metal powder-containing resin molded article is obtained by adding the fourth metal powder as an antibacterial material to a plastic resin, the antibacterial activity of the molded article depends on the purity and particle size of the Cu powder in the fourth metal powder. Quaternary metal powder containing high purity and fine Cu powder is suitable as an antibacterial agent.

The antibacterial activity (for example, the minimum inhibitory concentration of Salmonella typhi) of Al powder and Fe powder is about 1/100 lower than that of Cu powder made from pulverized copper wire. Furthermore, the antibacterial activity of Cu powder made from crushed enameled wire is inferior to that of Cu powder made from crushed copper wire, because its surface is covered with an enamel film. The fourth metal powder, which is substantially free of Al powder, Fe powder, and Cu powder obtained by pulverizing enameled wire, and contains highly purified Cu powder obtained by pulverizing copper wire, is suitable for antibacterial materials.

Furthermore, from the viewpoint of increasing the antibacterial activity of the Cu powder, the particle size of the Cu powder is preferably 1 mm or less. Since the particle size of the Cu powder in the fourth metal powder is 500 μm or less, the antibacterial activity of the Cu powder in the fourth metal powder is high.

<Method for producing metal powder-containing resin molded body>
The method for manufacturing a metal powder-containing resin molded body according to the present embodiment includes a step of preparing the fourth metal powder recycled and recovered in the above step (S30) of the metal recycling method according to the present embodiment, and 4. After melting and kneading the metal powder and the thermoplastic resin, the method includes a step of molding (S40).

In the molding step (S40), the weight ratio of the fourth metal powder in the kneaded product of the fourth metal powder and the thermoplastic resin may be 30% or more. In this case, the thermoplastic resin is prepared as a powder. The molding method may be any molding method, such as extrusion molding or injection molding.

In addition, in the molding step (S40), if the weight ratio of the fourth metal powder in the mixture of the fourth metal powder and the thermoplastic resin is 20% or less, the thermoplastic resin is powder, chips, Alternatively, it can be prepared in any shape such as pellets.

The metal powder-containing resin molded body is suitable for an antibacterial member that includes the fourth metal powder as an antibacterial material.
(Modified example)
In the metal regeneration method according to the present embodiment described above, the starting material is a metal mixture of copper wire, enameled wire, stainless steel wire, and aluminum plate, but the starting material is not limited to the above metal mixture. The metal mixture only needs to include at least a plurality of first metal wires and a plurality of second metal wires.

In the wire diameter distribution of the plurality of first metal wires, 50% of the plurality of first metal wires fall below the maximum wire diameter D50, and in the wire diameter distribution of the plurality of second metal wires, 75% of the plurality of second metal wires fall below. It only needs to be larger than the maximum wire diameter D75. For example, the first metal wire is a copper wire and the second metal wire is an enamelled wire or a stainless steel wire. In the distribution values in FIGS. 3 and 4, the maximum wire diameter D50 (290 μm) of the copper wire is larger than the maximum wire diameter D75 (283 μm) of the enamelled wire. Moreover, in the distribution values in FIGS. 3 and 5, the maximum wire diameter D50 of the copper wire is larger than the maximum wire diameter D75 (266 μm) of the stainless steel wire.

In the pulverizing step (S20), each of the plurality of first metal wires and the plurality of second metal wires is pulverized under the same conditions. If the hardness of the first metal constituting the plurality of first metal wires and the second metal constituting the plurality of second metal wires is softer than the hardness of the hammer or cutter blade used for crushing, the above-mentioned The particle size of the metal powder obtained by pulverizing each of the plurality of first metal wires and the plurality of second metal wires depends on the wire diameter of each metal wire before pulverization. Therefore, if the maximum wire diameter D50 of the first metal wire is larger than the maximum wire diameter D75 of the second metal wire, the first metal wire can be crushed by crushing the first metal wire and the second metal wire under the same conditions. The maximum particle size d50 of the metal powder obtained by pulverizing the second metal wire is larger than the maximum particle size d75 of the metal powder obtained by pulverizing the second metal wire.

As a result, as described above, each of the first value A, the second value B, and the third value C is determined according to the wire diameter distribution of the first metal wire and the second metal wire. By setting appropriately, the metal powder obtained by crushing the first metal wire can be efficiently recovered.

Specifically, the first value A and the third value C are set to values larger than the maximum wire diameter D50 of the first metal wire. The second value B is set to a value larger than the maximum particle size d75 of the metal powder obtained by pulverizing the second metal wire and smaller than the maximum particle size d50 of the metal powder obtained by pulverizing the first metal wire. be done. In this way, as described above, the weight ratio of the metal powder obtained by pulverizing the first metal wire using the metal mixture containing the first metal wire and the second metal wire as a starting material is 90% or more. Metal powder can be recycled.

Although the embodiments of the present disclosure have been described above, the embodiments described above can be modified in various ways. Further, the scope of the present disclosure is not limited to the above-described embodiments. The scope of the present disclosure is indicated by the claims, and is intended to include meanings equivalent to the claims and all changes within the range.

10. Pulverizer, 11. Supply section, 12. Grinding section, 13. Classification section.

Claims

a step of preparing a metal mixture in which multiple types of metal bodies having different shapes are mixed;
pulverizing the metal mixture into metal powder;
In the step of pulverizing, the particle size of all the metal powders is set to be equal to or less than a first value, and the particle size of all the metal powders is equal to or less than a second value smaller than the first value. 1 metal powder is removed, and a second metal powder whose particle size is larger than the second value and smaller than or equal to the first value is collected;
removing a third metal powder having a particle size of a third value or more from the second metal powder and recovering a fourth metal powder having a particle size of the second value or more and less than the third value; More prepared,
The method for regenerating metal, wherein the third value is greater than the second value and smaller than the first value.
The plurality of types of metal bodies include a first non-magnetic metal wire, a second non-magnetic metal wire, and a third non-magnetic metal plate,
The preparing step is a step of recovering the metal mixture by centrifugation from a mixture containing the first non-magnetic metal wire, the second non-magnetic metal wire, the third non-magnetic metal plate, and the plastic piece. including;
In the metal mixture, the first non-magnetic metal wire, the second non-magnetic metal wire, and the third non-magnetic metal plate are entangled with each other,
In the pulverizing step, the metal mixture is pulverized into the metal powder by a pulverizer that applies impact force and shear force to the metal mixture,
The Vickers hardness of each of the material constituting the first non-magnetic metal wire, the material constituting the second non-magnetic metal wire, and the material constituting the third non-magnetic metal plate constitutes the crushing part. The method for reclaiming metal according to claim 1, wherein the hardness is lower than the Vickers hardness of the material.
The mixture includes a coated metal wire having a core wire made of a non-magnetic metal and a plastic film covering the surface of the core wire,
3. The metal regeneration method according to claim 2, wherein the step of preparing further includes the step of removing the coated metal wire from the mixture based on the color observed when the mixture is irradiated with visible light.
The metal regeneration method according to claim 3, wherein the first value is 1 mm or less, and the second value is 45 μm or more.
The metal regeneration method according to claim 4, wherein the third value is 500 μm or less.
The plurality of types of metal bodies include a plurality of first metal wires and a plurality of second metal wires,
The Vickers hardness of the material constituting the plurality of first metal wires and the material constituting the plurality of second metal wires constitutes a crushing section used to crush the metal mixture in the crushing step. lower than the Vickers hardness of the material,
In the wire diameter distribution of the plurality of first metal wires, the maximum wire diameter D50 below which 50% of the plurality of first metal wires falls is the maximum wire diameter D50 of the plurality of second metal wires in the wire diameter distribution of the plurality of second metal wires. Greater than the maximum wire diameter D75, which is below 75%,
The metal regeneration method according to claim 1, wherein in the pulverizing step, each of the plurality of first metal wires and the plurality of second metal wires is pulverized.
Each of the plurality of first metal wires is a copper wire,
Each of the plurality of second metal wires is an enameled wire or a stainless steel wire,
The first metal powder is a powder obtained by pulverizing at least one of the enameled wire and the stainless steel wire,
7. The metal recycling method according to claim 6, wherein the fourth metal powder is copper powder obtained by pulverizing the copper wire.
The plurality of metal bodies include copper wire, enameled wire, stainless steel wire, and aluminum plate,
The wire diameter of the copper wire is 70 μm or more and 800 μm or less,
The wire diameter of the enameled wire is 80 μm or more and 800 μm or less,
The wire diameter of the stainless steel wire is 150 μm or more and 900 μm or less,
The maximum length of the aluminum plate is 10,000 μm or more and 25,000 μm or less,
The method for recycling metal according to any one of claims 1 to 7, wherein the fourth metal powder is copper powder obtained by pulverizing the copper wire.
a step of preparing the fourth metal powder recovered in the recovering step of the metal regeneration method according to any one of claims 1 to 8;
A method for manufacturing a metal powder-containing resin molded body, comprising a step of melting and kneading the fourth metal powder and a thermoplastic resin and then molding the fourth metal powder and a thermoplastic resin.