JP5700352B2 - Method of charging metal piece into shaft furnace, metal piece charging device, and method of recycling copper scrap - Google Patents

Description

  The present invention relates to a method of throwing a metal piece into a shaft furnace, a metal piece throwing apparatus suitable for this method, and a reuse of copper scrap when melting and reusing the metal used for a conductor of an electric wire, etc. It is about the method.

  Conventionally, metals such as copper (typically wires) that have been used for conductors of electric wires have been reused. Patent Document 1 discloses a technique for producing a copper alloy roughing wire by melting copper scrap obtained by pulverizing a copper wire, which has been used for the conductor, and the like, and electrolytic copper in a batch furnace. Since the batch furnace performs melting for each predetermined amount of raw material, the raw material can be easily charged into the furnace regardless of the shape of the raw material. However, since a batch furnace has a limited amount of melting once, a shaft furnace is used for continuous melting.

  For example, in the case where electric copper and copper scrap are melted to produce a pure copper melt in a shaft furnace, an electric copper plate is continuously charged in the shaft furnace, and a briquette body in which the copper scrap is gathered is introduced. The briquette body is obtained by placing a plurality of briquettes (for example, a diameter of about 10 cm × a height of about 15 cm) obtained by pressurizing and compacting a plurality of crushed pieces into a copper container and sealing them with a copper lid. This briquette body is conveyed above the shaft furnace by a lifter and is introduced into the furnace as needed.

JP 2008-202104 A

  However, the use of briquettes has the following problems.

(1) Manufacture takes time and workability is inferior.
As described above, the briquette body requires production of a briquette, production of a container, production of a lid, and sealing. Moreover, depending on the size of the small piece of copper scrap, it is difficult to produce briquettes, which leads to a decrease in workability. The size of the small piece of copper scrap depends on the size of the conductor of the wire before pulverization, and the diameter of the wire constituting this conductor varies widely from about 0.2 mm to 3 mm. A small piece having a diameter of about 1 mm or more is easy to break even when pressed, and it is difficult to produce a briquette.

(2) The resulting molten metal may have component spots.
The briquette body is heavy (about 1 to 2 tons) and the height to the upper part of the shaft furnace is as high as about 10m. Tends to be relatively long. Therefore, the obtained molten metal may have a portion where the briquette body is mixed and a portion where the briquette body is mixed. From the viewpoint of quality assurance, a molten metal having such a variation in components is not desirable.

(3) There is a risk that the tap on the bottom side of the shaft furnace may be blocked.
When the briquette body is initially introduced, the lid is closed, so that the briquette inside the container is heated by the atmosphere in the shaft furnace. Therefore, when a container, a lid, etc. melt and a briquette comes out of a container, each briquette goes to the furnace bottom side in the state heated to some extent. In the briquette body, since a plurality of briquettes are collected, the briquettes may fall to the furnace bottom side without being heated sufficiently. When a briquette with insufficient heating comes into contact with the molten metal on the bottom side of the furnace, the molten metal solidifies again, and in the worst case, the molten metal may block the outlet.

  The present invention has been made in view of the above circumstances, and one of the purposes thereof is a metal piece that can be easily put into a shaft furnace regardless of the size of the metal piece. The purpose is to provide a method of injection.

  Another object of the present invention is to provide a metal piece charging apparatus suitable for a method of loading the metal piece into a shaft furnace. Furthermore, another object of the present invention is to provide a method for reusing copper scrap.

  The present invention proposes to use a pressurized gas when a briquette or briquette body is not produced and a small piece of metal that has been crushed or cut is put into a shaft furnace. The method of throwing the metal piece into the shaft furnace according to the present invention relates to a method of throwing the metal piece into the shaft furnace from above the shaft furnace, and the metal piece is pumped above the shaft furnace with a pressurized gas. And a charging step of discharging downward in the shaft furnace.

  According to the above configuration, it is not necessary to prepare a briquette or a briquette body, and a metal piece that has been crushed or cut can be input as it is, so that the preparatory step before the input can be reduced and the workability is excellent. In particular, according to the said structure, a metal piece can be easily thrown in in a shaft furnace irrespective of the magnitude | size of a metal piece. That is, even a relatively large metal piece, which is difficult to produce briquettes, can be thrown in, and according to the above configuration, metal pieces of various sizes can be utilized without waste.

  Moreover, according to the said structure, unlike the case where a metal piece is conveyed using a lifter by using pressurized gas, for example, the said metal piece can be conveyed little by little, and also the said briquette body Compared with the case of using, the charging interval can be shortened. Therefore, according to the above-described configuration, it is easy to throw the metal pieces in small amounts, a plurality of times at short intervals, and by performing such feeding, the resulting molten metal is less likely to be spotted and uniform. A molten metal with a typical component can be obtained. Therefore, according to the said structure, it is anticipated that a high quality molten metal can be provided. Further, it is expected that a cast material such as a high-quality roughing wire can be obtained by using this molten metal.

  Furthermore, according to the said structure, a pressurized gas can be interposed between metal pieces, and a metal piece can be thrown in in a separated state, and it is hard to be thrown into a shaft furnace in the collective state. Therefore, even if the metal piece is not sufficiently heated and comes into contact with the molten metal on the furnace bottom side, it is difficult for the molten metal to solidify, and the possibility that the outlet is blocked by the solidified material can be reduced.

  In addition, according to the above configuration, the metal piece is charged into the shaft furnace while being accelerated toward the lower side in the shaft furnace by the pressurized gas, so that it falls toward the molten metal on the furnace bottom side. It is difficult for metal pieces to rise in the furnace. Here, for example, when a metal piece is thrown by free fall from the horizontal direction, the metal piece is lighter than a briquette or briquette body, so it rises due to furnace pressure (pressure in the shaft furnace generated by the heated atmosphere) Conceivable. There is a risk that the soared metal piece may adhere to and clog the upper part in the shaft furnace, particularly the inlet of the metal piece and the vicinity thereof. On the other hand, when metal pieces are thrown into the shaft furnace by free fall from the vertical direction, the metal pieces are likely to fall together and cause the above-described component spots. On the other hand, in the present invention, as mentioned above, it is difficult to soar, and the metal pieces are difficult to fall together due to the presence of the pressurized gas between the metal pieces, so that the introduction port is blocked and the components are spotted. The possibility can be reduced. Furthermore, according to the said structure, since the metal piece is the state disaggregated by the pressurized gas, it can fall to the furnace bottom side in the state fully heated by the atmosphere in a shaft furnace.

  The metal piece used in the present invention is a small piece of metal. Typically, the metal is made fine by grinding or cutting. For example, a crushed copper wire, particularly copper scrap of copper wire can be used. As described above, copper scraps of various sizes exist depending on the diameter of the copper wire. In the present invention, a copper wire piece having a relatively large diameter can be used as described above.However, as a result of investigation by the present inventors, when the amount (volume) to be conveyed at a time is constant, it is specified. It was found that when the size of the copper wire piece is small, the pressure during transport and the transport time can be reduced. Specifically, a copper wire piece having a diameter of 2.0 mm or less and a length of 5.0 mm or less is preferable. If the diameter is more than 2.0 mm or the length is more than 5.0 mm, the pressure during the conveyance and the conveyance time will increase. The smaller the diameter, the greater the effect of reducing the pressure during conveyance and the effect of reducing the conveyance time, and the diameter is more preferably 0.85 mm or less and the length is 5.0 mm or less. Further, when the diameter is 0.35 mm or more and the length is 2.0 mm or more, it is expected that it is difficult to move up and easy to carry. A copper wire may be selected, crushed or cut so as to have the above diameter and length. It is expected that the present invention can be applied to scraps of copper alloy wires in addition to the copper wires.

  As one form of this invention, it is preferable to discharge | emit the said metal piece by making a depression angle into 30 degrees or more and 60 degrees or less.

  According to the said structure, a metal piece can be thrown in more reliably toward the downward side in a shaft furnace, and scattering of the metal piece in the shaft furnace mentioned above etc. can be prevented. A more preferable depression angle is 45 °.

  As one aspect of the present invention, the method includes a transfer step of transferring a predetermined amount of a metal piece from a storage part for storing the metal piece to a pressurizing chamber, and the charging step includes the step of transferring the metal piece transferred to the pressurization chamber An example is a form in which the pressurized gas is pumped upward of the shaft furnace and discharged downward in the shaft furnace.

  According to the above configuration, for example, the amount of metal pieces to be charged at a time can be made constant, and variations in the components of the molten metal hardly occur. Moreover, a molten metal can be manufactured continuously over a long period of time by repeating the said transfer process and the said injection | throwing-in process continuously.

  The above-described method of charging the metal piece of the present invention into the shaft furnace can be carried out, for example, by using the metal piece charging apparatus of the present invention. The metal piece charging device of the present invention is a device for charging a metal piece into the shaft furnace from above the shaft furnace. The apparatus includes a storage section for storing a metal piece, a pressurizing chamber for holding a predetermined amount of the metal piece transferred from the storage section, and introducing the metal piece from the pressurizing chamber to an upper portion of the shaft furnace. A transport pipe, a pressurized gas supply section that generates a pressurized gas for spraying the metal pieces in the pressurizing chamber to the shaft furnace through the transport pipe, and the pressurization And an introduction portion arranged so that the metal piece that has been pumped by gas and passed through the transfer pipe is discharged downward in the shaft furnace.

  The method of putting the metal piece of the present invention into the shaft furnace can be suitably used when copper scrap is reused. The copper scrap recycling method of the present invention relates to a method of casting and recycling copper scrap, and the metal charged into the shaft furnace by the method of charging the metal piece of the present invention into the shaft furnace. A step of producing a cast material by melting a metal raw material including a piece; In particular, the metal piece is copper scrap. Such a reusing method of the present invention can be suitably used, for example, when a cast material is produced by separately adding copper to copper scrap.

  According to the method of feeding the metal piece of the present invention into the shaft furnace and the metal piece feeding device of the present invention, the metal piece can be easily put into the shaft furnace. According to the method for reusing copper scrap of the present invention, copper scrap can be reused efficiently, which can contribute to effective use of limited resources.

FIG. 1 is a schematic diagram of a metal piece charging device according to an embodiment. FIG. 2 is a schematic diagram of a metal piece holding unit included in the metal piece feeding device according to the embodiment.

  Hereinafter, an embodiment will be described with reference to FIGS. In the drawings, the same reference numerals indicate the same items.

  A metal piece charging device 1 shown in FIG. 1 is an apparatus that is provided in the shaft furnace 100 and for charging a metal piece that melts in the shaft furnace. The charging device 1 includes a metal piece holding unit 10 that stores metal pieces, and a pressurized gas supply unit that generates pressurized gas that serves as power for transporting the metal pieces to the shaft furnace 100 and applies the metal pieces to the metal pieces. 20 and a transport pipe 30 for introducing a power-supplied metal piece from the metal piece holder 10 to above the shaft furnace 100. Hereinafter, each configuration will be described in more detail.

[Shaft furnace 100]
The shaft furnace 100 has the same basic structure as a general shaft furnace, and is provided with a cylindrical main body 101, a raw material supply port 102 provided above the main body 101, and a lower side of the main body 101. A truncated cone part 103 tapered toward the bottom, a plurality of burners 104 provided around the truncated cone part 103, and a hot water outlet 105 provided in the furnace bottom are provided. The shaft furnace 100 heats and melts the metal introduced into the main body 101 from the raw material supply port 102 by the burner 104 to produce the molten metal 200, and discharges the molten metal 200 from the hot water outlet 105.

  Heated gas heated by the burner 104 or the molten metal 200 is accumulated above the shaft furnace 100. The metal introduced into the main body 101 from above in the shaft furnace 100 is gradually heated by the heat of the heated gas (while remaining heated), and moves downward in the shaft furnace 100 due to gravity, and is finally melted. To 200 molten metal. Here, a metal piece (here, copper scraps obtained by pulverizing or cutting copper wires used for electric wire conductors) is fed from the raw material supply port 102, and a copper plate made of electrolytic copper from another raw material supply port (not shown) 110 is charged to make a pure copper melt.

[Metal piece holder 10]
The metal piece holding unit 10 will be described with reference to FIG. The metal piece holding unit 10 includes a storage unit 11 that stores metal pieces, and a pressurizing chamber 12 that is disposed below the storage unit 11 and holds a predetermined amount of metal pieces transferred from the storage unit 11.

  The storage unit 11 is a funnel-shaped container capable of storing a predetermined amount (2.5 tons in this case) of metal pieces. With this shape, the storage unit 11 can easily discharge the metal piece from the lower discharge port 11o to the pressurizing chamber 12 by its own weight. An appropriate valve is provided between the discharge port 11o and the pressurizing chamber 12, and only a predetermined amount of metal pieces is transferred to the pressurizing chamber 12. In addition, when the metal piece of the storage part 11 decreases, it supplies suitably.

  The pressurizing chamber 12 is a container that temporarily holds the metal piece until a predetermined amount of the metal piece transferred from the storage unit 11 is conveyed to the shaft furnace 100. The pressurizing chamber 12 also has a funnel shape that tapers downward. Therefore, the metal piece in the pressurizing chamber 12 can be easily discharged from the discharge port 12o provided on the lower side to the transfer tube 30 connected to the discharge port 12o. The pressurizing chamber 12 has an air supply port 12g into which a pressurized gas from a pressurized gas supply unit 20 (FIG. 1) described later is introduced, and a metal piece and the pressurized gas are mixed. It is also a container. When the pressurized gas from the air supply port 12g is blown, the metal piece in the pressurizing chamber 12 can move in the transport pipe 30 and travels through the transport pipe 30 toward the shaft furnace 100.

  Further, the metal piece holding unit 10 includes a case 13 for storing the storage unit 11 and the pressurizing chamber 12, and the metal pieces are scattered outside or impurities from the external environment are mixed into the metal pieces. To prevent that.

[Pressurized gas supply unit 20]
Here, compressed air is used as power for conveying the metal piece from the pressurizing chamber 12 to the shaft furnace 100. Therefore, the pressurized gas supply unit 20 includes a compressor 21 that compresses air and a cylinder unit 22 that stores the air compressed by the compressor 21. The pressure of the compressed air is adjusted by a control unit (not shown) of the compressor 21. In addition to air, a gas that does not easily affect the molten metal, for example, an inert gas such as Ar or N ₂ may be used.

  A pipe 23 (FIG. 2) is arranged between the air inlet 12g (FIG. 2) of the pressurizing chamber 12 and the cylinder part 22, and the compressed air is supplied to the pressurizing chamber 12 through the pipe 23. Is introduced.

[Transport pipe 30]
The transfer pipe 30 is a transfer path for introducing a metal piece in the pressurizing chamber 12 from the pressurizing chamber 12 to the shaft furnace 100, and one end is connected to the discharge port 12o of the pressurizing chamber 12 described above, and the other end This inlet 30i is disposed in the raw material supply port 102 of the shaft furnace 100. An air supply port 30g (FIG. 2) into which the pressurized gas from the cylinder part 22 is introduced is provided in the transport pipe 30 near the discharge port 12o. A pipe 24 (FIG. 2) is also arranged between the air supply port 30g and the cylinder part 22, and a pressurization necessary for conveying a predetermined amount of metal pieces in the pressurization chamber 12 to the shaft furnace 100. A gas is introduced into the transfer pipe 30 through the pipe 24.

  As described above, the transfer pipe 30 is arranged at one end side connected to the discharge port 12o of the pressurizing chamber 12 on the lower side of the shaft furnace 100 as shown in FIG. And extends upward from the raw material supply port 102 of the shaft furnace 100. Then, a portion (introduction portion) in the vicinity of the connection portion with the shaft furnace 100 in the transport pipe 30 is such that the introduction port 30i faces downward toward the raw material supply port 102 located below the portion extending upward. Are inclined. Here, the transport pipe 30 is arranged so that the depression angle θ of the introduction part including the introduction port 30i is about 45 °. By disposing the introduction portion so as to be inclined downward in this manner, the metal piece that has passed through the transfer pipe 30 is discharged from the introduction port 30i (raw material supply port 102) downward to the shaft furnace 100.

[how to use]
For example, when recycling copper scrap of a copper wire used for a conductor of an electric wire by the metal piece charging device 1 having the above configuration, the copper scrap (metal piece) is charged into the shaft furnace 100. Is transferred from the metal piece stored in the storage unit 11 to the pressurizing chamber 12 by a predetermined amount (here, 50 kg). At this time, a predetermined amount of the metal piece moves to the pressurizing chamber 12 by its own weight. Further, the compressor 21 produces compressed air having a predetermined pressure (here, 0.6 MPa) and stores it in the cylinder part 22.

  Compressed air is introduced into the pressurizing chamber 12 and the transfer pipe 30 from the cylinder portion 22. By blowing the compressed air, the metal piece in the pressurizing chamber 12 is completely transferred from the discharge port 12o to the transfer tube 30. Further, the metal pieces transferred to the transfer pipe 30 are sequentially pumped through the transfer pipe 30 toward the shaft furnace 100 by the introduced compressed air.

  Then, the metal piece that has been pumped to the raw material supply port 102 of the shaft furnace 100 through the transport pipe 30 falls down evenly downward in the shaft furnace 100 and is melted.

  Here, the introduction of the pressurized gas is performed at a predetermined interval for a predetermined time (about 1 minute), and the metal piece is put into the shaft furnace 100. By sufficiently securing the introduction time of the pressurized gas, a predetermined amount (50 kg in this case) of the metal piece can be reliably introduced into the shaft furnace 100. In addition, if cleaning is performed by providing a time for introducing only the pressurized gas among the time for introducing the pressurized gas, the entire amount of the predetermined amount of metal pieces can be more reliably conveyed to the shaft furnace. Then, once the predetermined introduction time has elapsed, the introduction of the pressurized gas is temporarily stopped, a predetermined amount of the metal piece is transferred from the storage unit 11 to the pressure chamber 12, and the pressurized gas is again introduced for the predetermined time. Then, the metal piece is charged. By continuously repeating the transfer of the metal piece and the injection with the pressurized gas, the molten metal can be produced continuously over a long period of time. Further, by making the amount of the metal piece transferred to the pressurizing chamber 12 constant, it is possible to produce a molten metal having a uniform quality.

  For example, a cast material such as a copper roughing wire is produced by the molten metal 200 formed by melting. By doing so, the copper scrap can be reused.

[effect]
By using the metal piece charging device 1 having the above configuration, it is not necessary to prepare briquettes or briquette bodies, and the metal pieces are put into the shaft furnace as they are, so there are few preparation steps before charging and workability is improved. Excellent. In particular, by using the charging device 1, it is possible to charge the shaft furnace regardless of the size of the metal piece.

  In addition, by using the charging device 1, it is possible to feed a small amount of powdered metal pieces, not briquettes, with a short feeding interval. Therefore, the obtained molten metal does not vary in components, and it is expected that the charging device 1 can provide a molten metal having a homogeneous component.

  Furthermore, since the charging device 1 is configured to drop the metal piece, there is almost no possibility that the molten metal on the furnace bottom side is solidified by the metal piece, and the outlet is not substantially blocked by the solidified product. In addition, in the charging device 1, when the metal piece is introduced into the shaft furnace, it is accelerated downward by the pressurized gas, so that it is easier to fall than the case of its own weight alone. It ’s hard to soar. Therefore, it is possible to prevent the raw material supply port from being blocked due to the metal piece rising. Further, since the metal pieces are easily fallen apart by being pumped downward by the pressurized gas, the molten metal components are less likely to vary as compared with the case where the metal pieces are solidified and dropped.

(Test example)
Metal pieces having different sizes were prepared, and when transported to the shaft furnace 100 using the metal piece charging device 1, the pressure and transport time during transport were examined.

The following two types of metal pieces were prepared.
Metal piece (I) Diameter: 0.35 mm x length: 2.0 mm to diameter: 0.85 mm x length: 5.0 mm. Each metal piece satisfies a diameter: 0.35-0.85 mm and a length: 2.0-5.0 mm.
Metal piece (II) Diameter: 2.0mm x Length: 2.0-5.0mm

  The amount (volume) transported at one time was fixed, and the maximum pressure required for one transport and the time (transport time) required to transport to the shaft furnace when transported at this maximum pressure were measured. Table 1 shows the results when the metal piece (I) was used for four times of pressure feeding. When the metal piece (II) was used for four times of pumping, the maximum pressure was 0.55 to 0.60 MPa, and the transport time was an average of four times of 58 seconds.

  It can be seen that by using a small metal piece as described above, the pressure at the time of transportation can be reduced and the transportation time can be shortened. In particular, when using a small metal piece satisfying the size of 2.0 mm or less in diameter and 5.0 mm or less in length, when conveying with a constant amount (volume) of metal piece to be conveyed at a time, the diameter is 0.85. When using a smaller metal piece (I) that satisfies the size of mm or less and a length of 5.0 mm or less, the pressure during conveyance is further reduced compared to the case of using the metal piece (II), and the conveyance time It can be seen that can be further reduced. The reason for this is that even if the volume to be conveyed at one time is the same, the smaller the size of the metal piece, the higher the filling rate of the metal piece in the conveyance tube and the larger the input weight at one time. it is conceivable that. By using a metal piece that satisfies a specific size in this way, it is expected that the conveyance capacity can be improved and the energy related to the reuse of copper scrap can be reduced, and the energy efficiency is good.

  The above-described embodiment can be appropriately changed without departing from the gist of the present invention, and is not limited to the above-described configuration. For example, the transfer amount of the metal piece to the pressurizing chamber, the pressurizing pressure of the pressurized gas, the size of the metal piece, and the like can be appropriately changed.

  The method of charging the metal piece of the present invention into the shaft furnace and the metal piece charging apparatus of the present invention can be suitably used when metal pieces such as copper scrap are charged into the shaft furnace. The method for reusing copper scrap of the present invention can be suitably used when a new product is produced from copper scrap.

1 Metal piece charging device
10 Metal piece holder 11 Reservoir 11o, 12o Discharge port 12 Pressurization chamber
12g Air supply port 13 Case
20 Pressurized gas supply part 21 Compressor 22 Cylinder part 23, 24 Piping
30 Transport pipe 30i Inlet 30g Air inlet
100 Shaft furnace 101 Main body 102 Raw material supply port 103 Frustum
104 Burner 105 Outlet 110 Copper plate 200 Molten metal

Claims (8)

A main body that discharges the molten metal obtained by melting the supplied metal, and a burner that is provided on the lower side of the main body and that heats and melts the metal charged into the main body is used as a casting material. When supplying the metal to a shaft furnace that continuously produces the molten metal,
A metal piece is pumped above the shaft furnace by a pressurized gas,
Downward of the shaft furnace from the inlet portion being disposed inclined downward from the top of the shaft furnace, immediately poured step of discharging the metal pieces in a state of being accelerated by the pressurized gas A method of throwing a metal piece into a shaft furnace.   2. The method of putting the metal piece into the shaft furnace according to claim 1, wherein the metal piece is discharged at a depression angle of 30 ° to 60 °. A transfer step of transferring a predetermined amount of the metal piece from the storage part for storing the metal piece to the pressurizing chamber;
In the charging step, the metal piece transferred to the pressurizing chamber is pumped upward of the shaft furnace with the pressurized gas, and discharged downward in the shaft furnace,
3. The method for charging the metal piece according to claim 1 or 2, wherein the transfer step and the charging step are continuously repeated.   4. The method of putting the metal piece into the shaft furnace according to claim 1, wherein the metal piece is obtained by pulverizing a copper wire.   5. The method of putting the metal piece into the shaft furnace according to claim 4, wherein the metal piece has a diameter of 2.0 mm or less and a length of 5.0 mm or less.   6. The method according to claim 4, wherein the metal piece has a diameter of 0.85 mm or less and a length of 5.0 mm or less. A main body that discharges the molten metal obtained by melting the supplied metal, and a burner that is provided on the lower side of the main body and that heats and melts the metal charged into the main body is used as a casting material. It is attached to a shaft furnace that continuously produces the molten metal,
A reservoir for storing metal pieces;
A pressurizing chamber for holding a predetermined amount of the metal piece transferred from the reservoir;
One end is connected to the pressurizing chamber, the other end is connected to a raw material supply port provided above the side surface of the shaft furnace, and the metal piece is introduced from the pressurizing chamber to the upper portion of the shaft furnace. Tube,
A pressurized gas supply unit that generates a pressurized gas for spraying the metal piece in the pressurized chamber and pumping the metal piece to the shaft furnace through the transport pipe;
It is a part including the connection part with the said raw material supply port in the said conveyance pipe | tube, Comprising: It arrange | positions incline toward the said raw material supply port below from the said raw material supply port , The said metal piece is said shaft furnace An introduction device for a metal piece, comprising an introduction portion for discharging downward in the inside. A method for reusing copper scrap by casting and recycling copper scrap,
Comprising a step of producing a cast material by melting a metal raw material containing the metal piece charged into the shaft furnace by the method according to any one of claims 1 to 6,
The method for reusing copper scrap, wherein the metal piece is copper scrap.

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