Regeneration method and regeneration device for aluminum scrap

Abstract

Provided is a method for regenerating an aluminum scrap using a molten salt having a larger specific gravity than the liquid phase of aluminum, in which phase separation is performed between a melt containing an aluminum-containing component contained in the aluminum scrap and the molten salt containing impurities contained in the aluminum scrap.

Description

Technical Field

[0001] The invention relates to a method and a device for regenerating aluminum waste. Background Art

[0002] In recent years, efforts to significantly reduce waste generation by preventing and reducing waste generation and by recycling and reusing it have been actively promoted. To achieve this, research and development of recycling methods for aluminum scrap is being carried out.

[0003] In Patent Document 1, a regeneration method of an Al alloy is described, comprising: a preparation step of dissolving an Fe / Mn-containing material containing Fe and Mn and an Al alloy raw material to prepare a first molten metal; a crystallization step of crystallizing an Fe compound from the first molten metal; and an extraction step of extracting a second molten metal after removing at least a portion of the Fe compound crystallized from the first molten metal.

[0004] [Prior Technical Literature]

[0005] (Patent Document)

[0006] Patent Document 1: Japanese Patent Application Publication No. 2020-111808 Summary of the invention

[0007] [Problems to be solved by the invention]

[0008] However, in the Al alloy regeneration method described in Patent Document 1, since the second molten metal is extracted in a state of being in contact with the crystallized Fe compound, the Fe compound cannot be sufficiently removed and the concentration of the Fe compound in the regenerated Al alloy cannot be sufficiently reduced.

[0009] The object of the present invention is to provide a method and device for regenerating aluminum waste, which can fully reduce the concentration of impurities.

[0010] [Technical means to solve the problem]

[0011] (1) A method for regenerating aluminum scrap, comprising: regenerating aluminum scrap using a molten salt having a specific gravity greater than that of a liquid phase of aluminum, wherein a melt containing components of aluminum contained in the aluminum scrap and the molten salt containing impurities contained in the aluminum scrap are phase-separated.

[0012] (2) The method for recycling aluminum scrap according to (1), comprising the steps of: introducing the molten aluminum scrap into a funnel-shaped container whose tubular portion is disposed in the molten salt; and cooling the molten aluminum scrap introduced into the funnel-shaped container to crystallize the impurities, and then allowing the crystallized impurities to fall into the molten salt.

[0013] (3) The method for recycling aluminum scrap according to (1), comprising the steps of: cooling the molten aluminum scrap to crystallize the impurities and then solidifying the impurities to obtain a solidified product; adding the solidified product to the molten salt; and heating the solidified product added to the molten salt to melt the components including the aluminum and float the components on the molten salt.

[0014] (4) The method for recycling aluminum scrap according to (1), comprising the steps of: placing molten aluminum on the molten salt; adding the aluminum scrap to the molten aluminum; and heating the aluminum scrap added to the molten aluminum to melt the components including the aluminum and allow the impurities to fall into the molten salt.

[0015] (5) The method for recycling aluminum scrap according to any one of (1) to (4), wherein the specific gravity of the molten salt is 2.50 or more and 3.60 or less.

[0016] (6) The method for recycling aluminum scrap according to any one of (1) to (5), wherein the molten salt contains one or more elements selected from the group consisting of Cs, Ba, Rb, Sr and Ag.

[0017] (7) A recycling device for aluminum scrap, comprising: a smelting furnace containing a molten salt having a specific gravity greater than that of a liquid phase of aluminum; a funnel-shaped container, a tubular portion of which is arranged in the molten salt; an input portion for inputting the molten aluminum scrap into the funnel-shaped container; and a cooling portion for cooling the molten aluminum scrap input into the funnel-shaped container so that impurities contained in the aluminum scrap are crystallized and the crystallized impurities fall into the molten salt.

[0018] (8) A recycling device for aluminum scrap, comprising: a cooling unit for cooling a molten aluminum scrap so that impurities contained in the aluminum scrap are crystallized and then solidified to obtain a solidified product; a melting furnace for accommodating a molten salt having a specific gravity greater than that of a liquid phase of aluminum; and an input unit for inputting the solidified product into the molten salt; and the melting furnace heats the solidified product input into the molten salt so that components containing aluminum contained in the aluminum scrap are melted and float on the molten salt.

[0019] (9) A recycling device for aluminum scrap, comprising: a melting furnace containing, from the bottom, a molten salt having a specific gravity greater than that of a liquid phase of aluminum and molten aluminum; and an input portion for inputting aluminum scrap into the molten aluminum; and the melting furnace heats the aluminum scrap input into the molten aluminum so that components containing aluminum contained in the aluminum scrap are melted and impurities contained in the aluminum scrap fall into the molten salt.

[0020] (Effects of the Invention)

[0021] According to the present invention, a method for regenerating aluminum scrap and an apparatus for regenerating aluminum scrap capable of sufficiently reducing the concentration of impurities can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram showing an example of an aluminum scrap recycling device according to the present embodiment.

[0023] Figure 2 It means borrowing Figure 1 A schematic diagram of a method for regenerating aluminum waste performed by an aluminum waste regeneration device.

[0024] Figure 3 This is a graph showing an example of the relationship between the specific gravity of the liquid phase and solid phase of aluminum and the solid phase of impurities and the temperature.

[0025] Figure 4 It is a schematic diagram showing another example of the recycling device for aluminum scrap according to the present embodiment.

[0026] Figure 5 It means borrowing Figure 4 A schematic diagram of a method for regenerating aluminum waste performed by an aluminum waste regeneration device.

[0027] Figure 6 It is a schematic diagram showing another example of the recycling device for aluminum scrap according to the present embodiment.

[0028] Figure 7 It means borrowing Figure 6 A schematic diagram of a method for regenerating aluminum waste performed by an aluminum waste regeneration device.

[0029] Figure 8 It is shown Figure 6 Schematic diagram of a variation of an apparatus for recycling aluminum scrap. DETAILED DESCRIPTION

[0030] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0031] The method for regenerating aluminum scrap in the present embodiment uses a molten salt having a specific gravity greater than that of the liquid phase of aluminum to regenerate the aluminum scrap, and phase-separates the molten material containing the aluminum component contained in the aluminum scrap and the molten salt containing the impurities contained in the aluminum scrap. Thus, since the impurities are suppressed from dissolving and mixing into the components containing aluminum, the concentration of impurities in the regenerated aluminum is sufficiently reduced. Therefore, the regenerated aluminum can be applied to, for example, forging materials and casting materials. In addition, impurities can be separated even without using a filter.

[0032] Figure 1 An example of the aluminum scrap recycling device according to the present embodiment is shown in FIG.

[0033] The recycling device 10 for aluminum scraps includes: a melting furnace 11 containing a molten salt S having a specific gravity greater than that of a liquid phase of aluminum; a funnel-shaped container 12, a tubular portion 12a of which is arranged in the molten salt S; and a molten material input portion for inputting the molten aluminum scrap M into the funnel-shaped container 12. In addition, the recycling device 10 for aluminum scraps includes a cooling portion for cooling the molten aluminum scrap M input into the funnel-shaped container 12, so that impurities contained in the molten aluminum scrap M are crystallized and the crystallized impurities fall into the molten salt S. Among them, the melting furnace 11 is heated to melt the molten salt S. In addition, the molten aluminum scrap M is input into the funnel-shaped container 12 so that the self-weight and the buoyancy received from the molten salt S are balanced.

[0034] The melt input part is not particularly limited as long as the melt M of aluminum scrap can be input into the funnel-shaped container 12 , and examples thereof include a well-known automatic pouring device.

[0035] The cooling unit is not particularly limited as long as it can cool the molten material M of the aluminum scrap put into the funnel-shaped container 12, and an example thereof may be a well-known air cooling device.

[0036] In this specification and claims, cooling includes natural cooling.

[0037] Next, a method for regenerating aluminum scrap using the aluminum scrap regeneration apparatus 10 will be described.

[0038] First, aluminum scrap is heated to a temperature of 700°C or higher (e.g., 750°C) and melted to obtain a molten aluminum scrap M. Next, the molten aluminum scrap M is poured into the funnel-shaped container 12 whose tubular portion 12a is disposed in the molten salt S, and then the molten aluminum scrap M poured into the funnel-shaped container 12 is cooled at a cooling rate of, for example, 0.7°C / min. As a result, when the temperature reaches 700°C or lower, the impurities I crystallize and agglomerate in the tubular portion 12a (see Figure 2 (a)). At this time, since the specific gravity of the impurity I is greater than that of the molten salt S, the molten salt S enters between the tubular portion 12a and the impurity I. Further, when the crystallized impurity I increases, the self-weight of the impurity aggregate A becomes greater than the surface tension, and the impurity aggregate A falls from the tubular portion 12a into the molten salt S (refer to Figure 2 (b)). Then, when the temperature reaches 560°C or less, the recycled aluminum R, which is a component containing aluminum, solidifies. Finally, the funnel-shaped container 12 containing the solidified recycled aluminum R is taken out of the melting furnace 11. In addition, the impurity aggregates A that have fallen into the molten salt S are removed using, for example, a metal mesh.

[0039] Examples of the aluminum scrap include scraps of aluminum parts to which bolts are fastened or pressed. The impurities I include, for example, one or more elements selected from the group consisting of Si, Mn, Fe, and Cu.

[0040] In addition, when the impurity I is difficult to crystallize, one or more elements selected from the group consisting of Fe, Mn, Cr, V and Si may be added to the aluminum scrap melt M to adjust the composition of the aluminum scrap melt M. In this case, the sludge factor may also be considered. For example, if the composition of the aluminum scrap melt M is adjusted to include Fe (1.0 mass%), Mn (1.6 mass%), Cr (0.25 mass%), V (0.60 mass%) and Si (7.0 mass%) as impurities, the impurity I crystallizes at a temperature of 700° C. or less.

[0041] Figure 3 An example of the relationship between the specific gravity of the liquid phase and solid phase of aluminum and the solid phase of impurities and temperature is shown in FIG. Among them, the impurities are composed of Al, Fe, Mn, Cr, V and Si. It is estimated that Mn4Al 16 Si3 type crystal structure.

[0042] The specific gravity of the molten salt S is preferably 2.50 or more and 3.60 or less, and more preferably 2.70 or more and 3.10 or less. If the specific gravity of the molten salt S is 2.50 or more, the molten salt S is difficult to move into the melt M of the aluminum scrap, and if it is 3.60 or less, the agglomerates A of the impurities easily fall into the molten salt S. The specific gravity of the liquid phase of aluminum is 2.45.

[0043] The melting point of the molten salt S is preferably 750°C or lower, more preferably 550°C or lower. When the melting point of the molten salt S is 750°C or lower, the impurity aggregates A easily fall into the molten salt S. The melting point of the molten salt S is, for example, 530°C or higher.

[0044] The molten salt includes, for example, one or more elements selected from the group consisting of Cs, Ba, Rb, Sr, and Ag. Specific examples of the molten salt S include, for example, a mixture of BaCl2, CaCl2, and LiCl.

[0045] Table 1 shows the relationship between the formulation of the mixture of BaCl2, CaCl2 and LiCl and the specific gravity at 570°C.

[0046] [Table 1]

[0047]

[0048] Figure 4 Another example of the aluminum scrap recycling device according to the present embodiment is shown in FIG.

[0049] The aluminum scrap recycling device 20 includes: a melt input part for inputting the aluminum scrap melt into the cylindrical metal mold 21; and a cooling part for cooling the aluminum scrap melt input into the cylindrical metal mold 21 so that the impurities I contained in the aluminum scrap melt are crystallized and then solidified to obtain a solidified material C. In addition, the aluminum scrap recycling device 20 includes: a melting furnace 22 for accommodating a molten salt S having a specific gravity greater than that of a liquid phase of aluminum; and a solidified material input part for inputting the solidified material C into the molten salt S. The melting furnace 22 is heated to melt the molten salt S, and then the solidified material C input into the molten salt S is heated so that the components containing aluminum contained in the solidified material C are melted and float on the molten salt S.

[0050] The melt input part is not particularly limited as long as it can input the melt M of aluminum scrap into the cylindrical metal mold 21 , and an example thereof may be a well-known automatic pouring device.

[0051] The cooling unit is not particularly limited as long as it can cool the melt of the aluminum scrap accommodated in the cylindrical metal mold 21, and an example thereof may be a well-known air cooling device.

[0052] The solidified product feeding part is not particularly limited as long as it can feed the solidified product C into the molten salt S, and examples thereof include a well-known automatic feeding device.

[0053] Next, a method for regenerating aluminum scrap using the aluminum scrap regeneration device 20 will be described.

[0054] First, aluminum scrap is heated to a temperature of 700°C or higher to melt it, and a molten aluminum scrap is obtained. Next, the molten aluminum scrap is put into the cylindrical metal mold 21, and then the molten aluminum scrap put into the cylindrical metal mold 21 is cooled at a cooling rate of, for example, 0.5°C / min. As a result, when the temperature reaches 600°C or lower, the impurity I crystallizes and agglomerates at the bottom of the cylindrical metal mold 21. Next, when the temperature reaches 560°C or lower, the molten aluminum scrap solidifies to obtain a solidified material C. Next, the solidified material C is put into the molten salt S, and the solidified material C put into the molten salt S is heated. As a result, when the temperature reaches 560°C or higher, the recycled aluminum R, which is a component containing aluminum, melts and floats on the molten salt S (refer to Figure 5 ). At this time, since the impurity aggregate A is not melted, it remains at the bottom of the melting furnace 22. Finally, the molten recycled aluminum R is discharged from the upper part of the melting furnace 22. In addition, the impurity aggregate A remaining at the bottom of the melting furnace 22 is heated to a temperature of 700°C or more and melted, and then discharged from the lower part of the melting furnace 22.

[0055] Figure 6Another example of the aluminum scrap recycling device according to the present embodiment is shown in FIG.

[0056] The aluminum scrap recycling device 30 includes: a melting furnace 31, which contains molten salt S and molten aluminum R1 having a specific gravity greater than that of the liquid phase of aluminum in order from the bottom; and a scrap input part, which inputs aluminum scrap B into the molten aluminum R1. The melting furnace 31 heats the molten salt S and the molten aluminum R1 to melt, and then heats the aluminum scrap B input into the molten aluminum R1, so that the aluminum-containing components contained in the aluminum scrap B are melted, and impurities contained in the aluminum scrap B fall into the molten salt S.

[0057] The scrap feeding part is not particularly limited as long as it can feed the aluminum scrap B into the molten aluminum R1, and examples thereof include a well-known automatic feeding device.

[0058] Next, a method for regenerating aluminum scrap using the aluminum scrap regeneration device 30 will be described.

[0059] First, after the aluminum scrap B is put into the molten aluminum R1, the aluminum scrap B put into the molten aluminum R1 is heated. As a result, when the temperature reaches 560°C or higher, the components containing aluminum in the molten aluminum R1 melt to form the recycled aluminum R. In addition, the aluminum scrap B containing the components melted, that is, the impurities I, has a greater specific gravity than the recycled aluminum R, and therefore falls into the molten salt S (see Figure 7 ). Finally, the regenerated aluminum R is discharged from the upper part of the melting furnace 31. In addition, impurities I dropped into the molten salt S are removed using, for example, a metal mesh.

[0060] Figure 8 A variation of the recycling device 30 for aluminum scrap is shown in FIG.

[0061] The aluminum scrap regeneration device 40 is the same as the aluminum scrap regeneration device 30 except that a melting furnace 41 is used instead of the melting furnace 31. The area A1 of the melting furnace 41 containing the molten aluminum R1 is larger than the area A2 of the area containing the molten salt S, and an inlet 41a and a take-out port 41b are provided. Among them, the inlet 41a is a region for putting in aluminum scrap B, and the take-out port 41b is a region for taking out impurities I. In addition, the aluminum scrap regeneration device 40 is provided with partitions 42 and 43 for dividing the inlet 41a and the take-out port 41b, respectively. Furthermore, a container 44 (for example, a metal mesh container) having a through hole is movably arranged at the bottom of the melting furnace 41. Therefore, by moving the container 44 containing the impurities I falling into the molten salt S at the bottom in the horizontal direction and then moving it in the plumb direction, the impurities I can be taken out.

[0062] As mentioned above, although embodiment of this invention was described, this invention is not limited to the said embodiment, Within the range of the summary of this invention, the said embodiment can also be changed suitably.

[0063] [Example]

[0064] Hereinafter, examples of the present invention will be described, but the present invention is not limited to the examples.

[0065] (Example 1)

[0066] Aluminum scrap recycling device 30 (refer to Figure 6 ) to regenerate the aluminum scrap B. Specifically, after the aluminum scrap B is added to the molten aluminum R1, the aluminum scrap B added to the molten aluminum R1 is heated for 1 hour. At this time, as the aluminum scrap B, 6 kg of an aluminum frame with screws containing Fe as an impurity is used. In addition, as the molten salt S and the molten aluminum R1, 1.8 kg of a molten salt composed of BaCl2 (38 mol%), CaCl2 (44 mol%) and LiCl (18 mol%) melted at 750°C and having a specific gravity of 2.6 at 750°C and 2.5 kg of pure aluminum are used respectively. Finally, the regenerated aluminum R is taken out of the upper part of the smelting furnace 31. Among them, the specific gravity of the molten salt is an actual measurement value obtained by the maximum foam pressure method.

[0067] (Comparative Example 1)

[0068] The aluminum scrap B was regenerated in the same manner as in Example 1 except that the molten salt S was not used.

[0069] [Concentration of impurities]

[0070] The concentration of Fe in the recycled aluminum was analyzed using ICP emission spectroscopy.

[0071] Table 2 shows the analysis results of the Fe concentration in the recycled aluminum.

[0072] [Table 2]

[0073] Fe concentration in recycled aluminum [mass %] Example 1 0.30 Comparative Example 1 0.35

[0074] As can be seen from Table 2, the Fe concentration in the recycled aluminum is lower in Example 1 than in Comparative Example 1 in which no molten salt is used.

[0075] [Production of melt from aluminum scrap]

[0076] After heating an aluminum alloy (A356.2) as aluminum scrap to 750°C to melt it, a master alloy containing Fe, Mn, Cr, V and Si was added to adjust the composition of the aluminum scrap melt M. The composition of the aluminum scrap melt M was analyzed by ICP emission spectrometry, and the result was Si (6.3 mass%), Fe (0.84 mass%), Mn (1.6 mass%), Cr (0.22 mass%), V (0.36 mass%) and Al (the remainder).

[0077] (Example 2)

[0078] A recycling device 10 (using aluminum scrap Figure 1 Reference), the aluminum scrap is regenerated. Specifically, the molten aluminum scrap M is put into the funnel-shaped container 12 in which the tubular portion 12a is arranged in the molten salt S, and after the self-weight and the buoyancy received from the molten salt S are balanced, the molten aluminum scrap M put into the funnel-shaped container 12 is cooled to 560°C at a cooling rate of 0.7°C / min. At this time, as the molten salt S, 3.5 kg of BaCl2 (38 mol%), CaCl2 (44 mol%) and LiCl (18 mol%) melted at 750°C and having a specific gravity of 2.6 at 750°C is used. As a result, the regenerated aluminum R solidifies, and the funnel-shaped container 12 containing the solidified regenerated aluminum R is taken out from the smelting furnace 11. At this time, the agglomerate A of the impurities falls into the molten salt S. The concentration of Fe in the regenerated aluminum was analyzed, and the result was 0.34% by mass. It can be seen from this that the concentration of Fe in the regenerated aluminum is sufficiently reduced.

[0079] (Example 3)

[0080] A recycling device 20 using aluminum scrap (refer to Figure 4) to regenerate the aluminum scrap. Specifically, after 4.2 kg of the molten aluminum scrap was put into the cylindrical metal mold 21, the molten aluminum scrap put into the cylindrical metal mold 21 was cooled to 560°C at a cooling rate of 0.5°C / min. As a result, the impurity I crystallized and agglomerated at the bottom of the cylindrical metal mold 21. In addition, the molten aluminum scrap solidified to obtain a solidified material C. Next, after the solidified material C was put into the molten salt S, the solidified material C put into the molten salt S was heated. At this time, as the molten salt S, 6.0 kg of a molten salt composed of BaCl2 (38 mol%), CaCl2 (44 mol%) and LiCl (18 mol%) which had been melted at 650°C and had a specific gravity of 2.7 at 650°C was used. As a result, the regenerated aluminum R melted and floated on the molten salt S. At this time, the agglomerate A of the impurity did not melt, so it remained at the bottom of the smelting furnace 22. Finally, the molten regenerated aluminum R was tapped from the upper portion of the melting furnace 22. The Fe concentration in the regenerated aluminum was analyzed and found to be 0.24% by mass. This indicates that the Fe concentration in the regenerated aluminum was sufficiently reduced.

[0081] Reference numerals

[0082] 10, 20, 30, 40 aluminum waste recycling device

[0083] 11, 22, 31, 41 melting furnaces

[0084] 12 Funnel-shaped container

[0085] 12a Tubular portion

[0086] 21. Cylindrical metal mold

[0087] 41a Input port

[0088] 41b Take exit

[0089] 42, 43 partition

[0090] 44 Container

[0091] A impurity aggregate

[0092] B Aluminum Scrap

[0093] C Concrete

[0094] I Impurities

[0095] M Melt of aluminium scrap

[0096] R Recycled Aluminum

[0097] R1 Molten Aluminum

[0098] S Molten Salt

Claims

1. A method for regenerating aluminum waste, using a molten salt having a specific gravity greater than that of the liquid phase of aluminum to regenerate the aluminum waste, wherein: The melt containing the component of aluminum contained in the aluminum scrap and the molten salt containing the impurities contained in the aluminum scrap are phase-separated.

2. The method for recycling aluminum waste according to claim 1, wherein: The process includes the following steps: Putting the melt of the aluminum scrap into a funnel-shaped container whose tubular portion is disposed in the molten salt; and The molten aluminum scrap introduced into the funnel-shaped container is cooled to crystallize the impurities, and then the crystallized impurities are dropped into the molten salt.

3. The method for recycling aluminum waste according to claim 1, wherein: The process includes the following steps: Cooling the molten aluminum scrap to crystallize the impurities and then solidifying the molten aluminum scrap to obtain a solidified product; adding the solidified product into the molten salt; and The solidified product introduced into the molten salt is heated to melt the component including the aluminum and float on the molten salt.

4. The method for recycling aluminum waste according to claim 1, wherein: The process includes the following steps: placing molten aluminum on the molten salt; Adding the aforementioned aluminum scrap into the aforementioned molten aluminum; and, The aluminum scrap introduced into the molten aluminum is heated to melt the components including the aluminum and to cause the impurities to fall into the molten salt.

5. The method for recycling aluminum waste according to claim 1 or 2, wherein: The specific gravity of the molten salt is 2.50 or more and 3.60 or less.

6. The method for recycling aluminum waste according to claim 1 or 2, wherein: The molten salt contains one or more elements selected from the group consisting of Cs, Ba, Rb, Sr, and Ag.

7. A recycling device for aluminum waste, comprising: a smelting furnace containing a molten salt having a specific gravity greater than that of the liquid phase of aluminum; A funnel-shaped container, the tubular portion of which is disposed in the molten salt; A feeding part is used to feed the molten aluminum scrap into the funnel-shaped container; and The cooling part cools the melt of the aluminum scrap put into the funnel-shaped container so that impurities contained in the aluminum scrap are crystallized and then the crystallized impurities fall into the molten salt.

8. A recycling device for aluminum waste, comprising: A cooling section cools the molten aluminum scrap so that impurities contained in the aluminum scrap are crystallized and then solidified to obtain a solidified product; a smelting furnace containing a molten salt having a specific gravity greater than that of a liquid phase of aluminum; and A feeding part is used to feed the solidified product into the molten salt; and The smelting furnace heats the solidified product introduced into the molten salt so that components including aluminum contained in the aluminum scrap are melted and floated on the molten salt.

9. A recycling device for aluminum waste, comprising: A smelting furnace containing, from the bottom, a molten salt having a specific gravity greater than that of a liquid phase of aluminum and molten aluminum; and, The input part inputs aluminum scrap into the molten aluminum. The smelting furnace heats the aluminum scrap introduced into the molten aluminum so that components including aluminum contained in the aluminum scrap are melted and impurities contained in the aluminum scrap fall into the molten salt.

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