Method for manufacturing aluminum alloys and method for manufacturing aluminum alloy materials

Abstract

To provide a method for removing impurities, capable of efficiently removing the impurities mixed in aluminum or an aluminum alloy while reducing an environmental load.SOLUTION: A method for removing impurities according to an embodiment of the present invention comprises: a mixing step of mixing Mg or a Mg alloy into a molten metal including aluminum or an aluminum alloy and impurities, so that a content of Mg in the molten metal is 5 mass% or more and 18 mass% or less; a holding step of holding the molten metal after the mixing step in the range of 530°C or more and 700°C or less; and a separation step of separating intermetallic compounds generated in the holding step from the molten metal or in the molten metal.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an impurity removal method, a method for producing an aluminum-based alloy, and a method for producing an aluminum-based alloy material.

Background Art

[0002] Aluminum has excellent recyclability, and many aluminum products made of aluminum rolled materials such as aluminum cans and die-cast products are remelted after being discarded and recycled into new products. Although a large amount of carbon dioxide (CO2) is generated during the production of aluminum ingots, the use of aluminum ingots can be reduced by recycling aluminum products, thereby promoting the reduction of carbon dioxide.

[0003] Impurities adhere to aluminum products after being discarded, and the concentration of impurity elements gradually increases as recycling is repeated. Therefore, aluminum products are generally cascade recycled into products with looser component specifications.

[0004] On the other hand, for aluminum products after being discarded, it may be desirable to perform horizontal recycling after removing impurities, or to remove some elements and recycle them into products with different compositions.

[0005] Many techniques for removing impurities from molten aluminum or an aluminum alloy have been reported. For example, as a technique for removing Fe, a technique has been proposed in which a predetermined amount of Mg, Zn, and Mn is contained in a molten metal containing Fe as an impurity, and then an Fe compound is crystallized from this molten metal (see Patent Document 1).

[0006] In addition, as a technique for reducing the impurity concentration in molten aluminum or an aluminum alloy, techniques using a three-layer electrolytic refining method or a segregation method in the process of producing aluminum ingots have been disclosed (see Non-Patent Document 1).

Prior Art Documents

Patent Documents

[0007] [Patent Document 1] Japanese Patent Publication No. 2019-77895 [Non-patent literature]

[0008] [Non-Patent Document 1] Kondo et al., Materia, 1994, Vol.33, No.1, 62-68 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] However, the technology described in Patent Document 1 requires the addition of a relatively large amount of Mg to the molten metal, which increases the effort required to dilute the molten metal after impurity removal. Furthermore, if Mg is added and Mg metal is produced, a large amount of carbon dioxide gas will be released during the production of this metal. Moreover, in the technology described in Patent Document 1, the added Mn is included in the molten metal as an impurity, so it cannot be said that the impurities can be effectively removed.

[0010] Furthermore, while it is theoretically possible to remove impurities according to the technology described in Non-Patent Document 1, the yield may be low when used to refine scrap containing a large amount of impurity elements. In addition, the three-stage electrolytic refining method is not cost-effective in areas with high electricity costs, and the segregation method may see a decrease in yield as the impurity concentration of the raw material increases.

[0011] Thus, the above-mentioned conventional technology is insufficient as a method for recycling aluminum scrap containing many impurities collected from the market.

[0012] This invention has been made in view of these circumstances, and aims to provide an impurity removal method that can efficiently remove impurities mixed in aluminum or aluminum alloys while reducing the environmental burden. [Means for solving the problem]

[0013] A method for removing impurities according to one aspect of the present invention comprises a mixing step of mixing Mg or an Mg alloy into a molten metal containing aluminum or an aluminum alloy and impurities such that the Mg content in the molten metal is 5% by mass or more and 18% by mass or less; a holding step of holding the molten metal after the mixing step at a temperature of 530°C or more and 700°C or less; and a separation step of separating the intermetallic compounds generated in the holding step from or within the molten metal. [Effects of the Invention]

[0014] An impurity removal method according to one aspect of the present invention can efficiently remove impurities mixed in aluminum or aluminum alloys while reducing the environmental burden. [Brief explanation of the drawing]

[0015] [Figure 1] Figure 1 is a flowchart showing an impurity removal method according to one embodiment of the present invention. [Figure 2] Figure 2 is a flowchart showing a method for manufacturing an aluminum-based alloy according to one embodiment of the present invention. [Figure 3] Figure 3 is a flowchart showing a method for manufacturing an aluminum alloy that differs from the method for manufacturing an aluminum alloy shown in Figure 2. [Figure 4] Figure 4 is a flow chart showing a method for manufacturing an aluminum alloy material according to one embodiment of the present invention. [Modes for carrying out the invention]

[0016] [Description of Embodiments of the Invention] First, embodiments of the present invention will be listed and described.

[0017] The impurity removal method according to one aspect of the present invention includes a mixing step of mixing Mg or an Mg alloy into a molten metal containing aluminum or an aluminum alloy and an impurity so that the content of Mg in the molten metal is 5% by mass or more and 18% by mass or less, a holding step of holding the molten metal after the mixing step within a range of 530°C or higher and 700°C or lower, and a separation step of separating an intermetallic compound generated in the holding step from or within the molten metal.

[0018] In the impurity removal method, since the liquidus temperature of the molten metal can be appropriately lowered by controlling the content of Mg in the molten metal within the above range in the mixing step, by holding the molten metal at a temperature within the above range in the holding step, an intermetallic compound containing the impurity can be generated in a molten metal containing aluminum and Mg (Al-Mg based molten metal). In addition to being able to reduce the production amount of aluminum ingots by aiming for the recycling of aluminum, the impurity removal method can reduce the production amount of Mg ingots by suppressing the content of Mg in the molten metal within the above range, so that the amount of carbon dioxide gas generated due to the production of these ingots can be reduced. As a result, the impurity removal method can reduce the environmental load.

[0019] The holding time of the molten metal in the holding step is preferably 3 minutes or more. Thus, by setting the holding time of the molten metal in the holding step to be not less than the above lower limit, the impurities can be easily and surely removed.

[0020] The impurity is preferably at least one selected from the group consisting of Cr, Ti, V, and Zr. Thus, by having the impurity be at least one selected from the group consisting of Cr, Ti, V, and Zr, the impurity can be easily removed from the molten metal while suppressing the addition amount of Mg in the mixing step.

[0021] The method for producing an aluminum-based alloy according to another aspect of the present invention includes a casting step of casting the molten metal after the intermetallic compound is separated by the separation step, using the impurity removal method.

[0022] Since the manufacturing method for this aluminum alloy utilizes the impurity removal method, it is possible to recycle aluminum.

[0023] The method for manufacturing the aluminum alloy may include a component adjustment step before the casting step in which the components of the molten metal are adjusted after the intermetallic compounds have been separated by the separation step. By including a component adjustment step before the casting step in which the components of the molten metal are adjusted after the intermetallic compounds have been separated by the separation step, the recycling of aluminum can be made easier.

[0024] A method for manufacturing an aluminum alloy material according to yet another aspect of the present invention comprises a plastic deformation step of plastically working the aluminum alloy obtained through the above casting step using the method for manufacturing the aluminum alloy.

[0025] Since the manufacturing method for the aluminum alloy material uses the impurity removal method, it is possible to recycle aluminum.

[0026] The manufacturing method for the aluminum alloy material may include a component adjustment step for adjusting the composition of the molten metal after the intermetallic compounds have been separated by the separation step. By including a component adjustment step for adjusting the composition of the molten metal after the intermetallic compounds have been separated by the separation step, the recycling of aluminum can be made easier.

[0027] The embodiments of the present invention will be described in detail below with reference to the drawings. It should be noted that, regarding the numerical values ​​described herein, only one of the upper or lower limits may be adopted, or the upper and lower limits may be combined in any way.

[0028] [Impurity removal method] This impurity removal method removes impurities that are difficult to remove when mixed into aluminum or aluminum alloys from Al-Mg molten metal. This method involves incorporating Mg, an essential element of the JIS-A5000 system, into the molten metal, maintaining the molten metal in a temperature range of 530°C to 700°C to promote the eutectic formation of impurities, and separating the resulting intermetallic compounds from the molten metal to remove the impurities. This impurity removal method does not require the deliberate mixing of unnecessary impurities to generate the intermetallic compounds, and can improve yield. By using this impurity removal method, the concentration of Mg in the molten metal can be suppressed while reducing the impurity concentration to, for example, below the permissible limit of the JIS-A5000 system.

[0029] To achieve horizontal recycling of aluminum from wrought aluminum to wrought aluminum, it is necessary to reduce impurities to below the permissible concentration for the wrought aluminum. From this perspective, the impurity removal method can reduce the concentration of impurities that are mixed into aluminum or aluminum alloys and are difficult to remove to, for example, 0.2% by mass or less.

[0030] As shown in Figure 1, the impurity removal method comprises a mixing step S1 in which Mg or an Mg alloy is mixed into a molten metal containing aluminum or an aluminum alloy and impurities such that the Mg content in the molten metal is 5% by mass or more and 18% by mass or less; a holding step S2 in which the molten metal after the mixing step S1 is held in a range of 530°C to 700°C; and a separation step S3 in which the intermetallic compounds generated in the holding step S2 are separated from or within the molten metal. In this impurity removal method, the molten metal may be held under an inert atmosphere from the viewpoint of preventing oxidation of Mg, etc. Furthermore, from the viewpoint of preventing oxidation of Mg, etc., a small amount (for example, about 30 ppm by mass) of Be (beryllium) may be added to the molten metal, or a flux may be sprayed.

[0031] 〔impurities〕 The impurities removed by this impurity removal method are not particularly limited, but examples include transition metal elements. Aluminum products can have transition metal elements attached as impurities, and the concentration of these impurities tends to increase with repeated recycling. Furthermore, as the applications of aluminum products expand, it is conceivable that transition metal elements may be added to impart strength, rigidity, heat resistance, etc. On the other hand, transition metal elements are generally difficult to remove through refining.

[0032] The inventors primarily investigated methods for removing such transition metal elements and searched for elements that could be efficiently removed from the molten metal while suppressing the Mg content in the molten metal. As a result, the inventors found that among the above transition metal elements, at least one selected from the group consisting of Cr (chromium), Ti (titanium), V (vanadium), and Zr (zirconium) is preferred as the impurity.

[0033] Cr, Ti, V, and Zr are readily incorporated as additives in aluminum alloys, grain refiners, and ingots. These elements are easily removed from the liquid phase because the crystallization temperature of the stable compounds formed by their bonding with aluminum is higher than the liquidus temperature of aluminum. Furthermore, the mixing of Mg into the molten metal increases their activity, enabling compound formation at higher temperatures. Specifically, compared to Fe and Mn, Cr, Ti, V, and Zr have higher compound formation temperatures. Additionally, while mixing Mg into the molten metal lowers the liquidus temperature of aluminum, it raises the compound formation temperature of Cr, Ti, V, and Zr. Therefore, this impurity removal method allows for easy removal of the impurities from the molten metal by suppressing the amount of Mg added in the mixing step S1 while easily forming intermetallic compounds in the holding step S2, provided that the impurities are at least one selected from the group consisting of Cr, Ti, V, and Zr.

[0034] (Mixing process) In mixing step S1, for example, Mg or an Mg alloy is mixed into the molten metal obtained by dissolving aluminum scrap containing the above-mentioned impurities.

[0035] In mixing step S1, Mg, an essential element in JIS-A5000 series aluminum alloys, is added to the molten metal containing aluminum or an aluminum alloy and the aforementioned impurities. The inclusion of Mg in the molten metal promotes the formation of intermetallic compounds containing the aforementioned impurities in the Al-Mg molten metal. This impurity removal method does not require the deliberate dissolution of excessive amounts of unnecessary impurities into the molten metal in order to form the aforementioned intermetallic compounds. Furthermore, since Mg is not an impurity, this impurity removal method does not require a separate step for removing Mg. Therefore, in this impurity removal method, for example, the molten metal after the above impurities have been removed can be diluted as needed and used for aluminum recycling. The procedure for diluting the molten metal after the above impurities have been removed (dilution step) will be described later. Examples of Mg alloys to be mixed in mixing step S1 include JIS-MC5 and JIS-MDC2A.

[0036] The effects of mixing Mg or an Mg alloy in the mixing step S1 include, for example, the following (a) and (b). (a) The liquidus temperature is lowered, which allows the molten metal to be kept at a low temperature and promotes the formation of the intermetallic compound. (b) Mg increases the activity of impurity elements, thereby promoting the formation of the above intermetallic compounds.

[0037] The impurity removal method can convert the impurities into intermetallic compounds in the molten metal through the effects of one or both of (a) and (b) above.

[0038] As described above, in mixing step S1, Mg or Mg alloy is mixed so that the Mg content in the molten metal is 5% by mass or more and 18% by mass or less. The lower limit of the Mg content in the molten metal after mixing step S1 is preferably 7.5% by mass. On the other hand, the upper limit of the content is preferably 15% by mass, and more preferably 12% by mass. Furthermore, the upper limit of the content is even more preferably less than 11% by mass. If the content is less than the lower limit, it may not be possible to sufficiently lower the liquidus temperature of the molten metal. Conversely, if the content exceeds the upper limit, the Mg concentration in the molten metal after the impurities are removed in separation step S3 will be high, which may increase the cost required for diluting Mg and increase the environmental burden.

[0039] (holding process) In the holding step S2, the intermetallic compound is generated in the molten metal that has been cooled after the mixing step S1.

[0040] As mentioned above, the lower limit of the holding temperature of the molten metal in holding step S2 is 530°C, preferably 550°C, and more preferably 575°C. On the other hand, as mentioned above, the upper limit of the holding temperature is 700°C, preferably 650°C, more preferably 640°C, and even more preferably 625°C. In order to efficiently generate the intermetallic compound from the molten metal, it is desirable to hold the molten metal in a low-temperature liquid phase in holding step S2. If the holding temperature exceeds the upper limit, the efficiency of the generation of the intermetallic compound may be insufficient. Conversely, if the holding temperature is below the lower limit, the aluminum in the molten metal may solidify, or the generation rate of the intermetallic compound may be slowed down.

[0041] The lower limit of the holding time for the molten metal in the holding step S2 is preferably 3 minutes, more preferably 5 minutes, and even more preferably 10 minutes. If the holding time is less than the lower limit, it may be difficult to sufficiently generate the intermetallic compounds. On the other hand, the upper limit of the holding time is preferably 180 minutes, more preferably 120 minutes, and even more preferably 60 minutes. By setting the holding time below the upper limit, this impurity removal method can suppress excessive fuel costs required for temperature control of the molten metal. Furthermore, even if the holding time is below the upper limit, this impurity removal method can sufficiently generate the intermetallic compounds. Therefore, by using the molten metal after the intermetallic compounds have been separated in the separation step S3 described later for aluminum recycling, carbon dioxide emissions can be reduced.

[0042] (separation process) In separation step S3, for example, the intermetallic compound generated in holding step S2 is separated from the molten metal. In separation step S3, the impurities are removed from the molten metal by separating the intermetallic compound from the molten metal after holding step S2. The separation procedure for the intermetallic compound in separation step S3 can be selected depending on the form in which the intermetallic compound exists. For example, if the intermetallic compound is in the form of fine particles of several tens of micrometers, methods such as adhering it to flux, filtering it with a refractory filter, or precipitating it in the molten metal and recovering only the supernatant can be used.

[0043] Furthermore, in separation step S3, the intermetallic compound generated in holding step S2 may be separated in the molten metal. One procedure for separating the intermetallic compound in the molten metal is to precipitate the intermetallic compound in the molten metal and then solidify the molten metal. After the molten metal has solidified, the impurities can be removed by cutting off the parts where the intermetallic compound has aggregated.

[0044] (Dilution process) The molten metal (Al-Mg alloy molten metal) remaining after the intermetallic compounds have been removed by the above separation process can be used as an Al-Mg intermediate alloy for aluminum molten metal with a low impurity concentration.

[0045] Furthermore, in the dilution process described above, it is also possible to evaporate the Mg, which has a high vapor pressure, by holding the molten metal under vacuum, thereby lowering the Mg concentration in the molten metal. In addition, by using a flux for Mg removal, it is possible to obtain an Al-Mg molten metal with a low Mg concentration.

[0046] Furthermore, an aluminum recycling method that adds the above-mentioned dilution step to the above-mentioned mixing step S1, holding step S2, and separation step S3 is one embodiment of the present invention.

[0047] <Advantages> This impurity removal method allows for the appropriate reduction of the liquidus temperature of the molten metal by controlling the Mg content in the molten metal within the specified range during the mixing step S1. By maintaining the molten metal within this range during the holding step S2, intermetallic compounds containing the impurities can be generated in the molten metal containing aluminum and Mg (Al-Mg molten metal). This impurity removal method reduces the amount of aluminum ingots produced by promoting aluminum recycling, and also reduces the amount of Mg ingots produced by keeping the Mg content in the molten metal within the specified range. As a result, the amount of carbon dioxide generated due to the production of these ingots can be reduced. Consequently, this impurity removal method can reduce the environmental impact.

[0048] This impurity removal method involves adding Mg, an essential element in aluminum alloys such as JIS-A5000 series, to the molten metal to promote the compounding of impurity elements, and then separating the resulting intermetallic compounds from the molten metal to remove the impurity elements. This impurity removal method efficiently removes impurity elements that were previously difficult to remove by coexisting them with Mg, thereby reducing the concentration of these impurity elements to a level suitable for incorporation into aluminum sheets. In this process, by keeping the Mg content in the molten metal low, the amount of ingot used in the manufacture of aluminum sheets can be reduced. Therefore, this impurity removal method allows for the use of difficult-to-recycle scrap as a substitute for aluminum ingots and reduces carbon dioxide emissions.

[0049] [Manufacturing method for aluminum alloys] Next, a method for manufacturing an aluminum alloy using the impurity removal method will be described with reference to Figures 2 and 3. This method for manufacturing an aluminum alloy is used, for example, to produce an Al-Mg alloy. The method includes a casting step in which the molten metal is cast after the intermetallic compounds have been separated in the separation step S3. Furthermore, the method for manufacturing an aluminum alloy includes a component adjustment step prior to the casting step, in which the components of the molten metal after the intermetallic compounds have been separated in the separation step are adjusted.

[0050] The manufacturing method for the aluminum alloy may involve performing the casting process only once or multiple times after the separation process S3. Furthermore, if the casting process is performed multiple times, the component adjustment process may be performed before any of the casting processes. Additionally, the component adjustment process can be performed multiple times. For example, in Figure 2, the component adjustment process S4 and the casting process S5 are performed once each in that order after the separation process S3. In Figure 3, the casting process (first casting process S6), the component adjustment process S7, and the casting process (second casting process S8) are performed in that order after the separation process S3. However, the number and order of the casting process and the component adjustment process are not limited to the configurations shown in Figures 2 and 3. The component adjustment process and the casting process will be described in detail below.

[0051] (Component adjustment process) In the above component adjustment step, the components of the molten metal, from which the impurities have been removed via the separation step S3, are adjusted. In the above component adjustment step, aluminum ingots, alloying elements, etc., are added to the molten metal. By adding aluminum ingots and alloying elements in the above component adjustment step, it becomes easier to manufacture JIS-A5000 series aluminum alloy materials by the aluminum alloy material manufacturing method described later. In addition, in the above component adjustment step, it is also possible to adjust the components of the molten metal by diluting it. Furthermore, if the above component adjustment step is performed multiple times, it is possible to change the components added each time.

[0052] (Casting process) In the above casting process, the molten metal from which the impurities have been removed via the separation process S3 is cast. In this method of manufacturing aluminum alloys, the molten metal after the separation process S3 contains Mg, and impurities have been removed from this molten metal. Therefore, the above casting process is suitable for casting Al-Mg alloys.

[0053] <Advantages> Since the method for manufacturing the aluminum alloy uses the impurity removal method, it is possible to recycle aluminum. Furthermore, since the method for manufacturing the aluminum alloy includes the above-mentioned component adjustment step, it is possible to recycle aluminum more easily.

[0054] [Manufacturing method for aluminum alloy materials] The manufacturing method for the aluminum alloy material is carried out using the manufacturing method for aluminum alloys described above. As shown in Figure 4, the manufacturing method for the aluminum alloy material includes a plastic deformation step S9 for plastically deformation of the aluminum alloy obtained through the casting step S5. In Figure 4, an example of a manufacturing method for aluminum alloy material is shown using the manufacturing method for aluminum alloys shown in Figure 2. However, the manufacturing method for the aluminum alloy material may also be carried out using the manufacturing method for aluminum alloys shown in Figure 3, or using a manufacturing method for aluminum alloys that does not include the above-mentioned component adjustment step.

[0055] The method for manufacturing the aluminum alloy material may include a component adjustment step for adjusting the composition of the molten metal after the intermetallic compounds have been separated by the separation step S3. If the method for manufacturing the aluminum alloy material includes the component adjustment step, the method may further perform a casting step after this component adjustment step, and then perform the plastic deformation step on the aluminum alloy obtained in this casting step. This component adjustment step can be carried out in the same procedure as the component adjustment step in the aluminum alloy material manufacturing method described above. By including the component adjustment step in the method for manufacturing the aluminum alloy material, the composition of the resulting aluminum alloy material can be easily controlled. As a result, aluminum recycling can be made easier.

[0056] (Plastic working process) In the above plastic deformation process, an aluminum alloy is subjected to plastic deformation to produce an aluminum alloy material. Examples of plastic deformation include hot working and cold working. Specific processing methods include rolling, extrusion, and forging. In the above plastic deformation process, the aluminum alloy may be subjected to heat treatment as needed. Examples of heat treatment include homogenization heat treatment, solution heat treatment, and aging treatment.

[0057] In the above plastic deformation process, for example, an Al-Mg alloy material is produced. In particular, it is preferable to produce an aluminum alloy material of the JIS-A5000 series in the above plastic deformation process. In other words, the method for producing this aluminum alloy material is suitably used as a method for producing an aluminum alloy material of the JIS-A5000 series. In this method for producing an aluminum alloy material, the molten metal after the separation process S3 contains Mg, an essential element of the JIS-A5000 series, and impurities are removed from this molten metal. Therefore, this method for producing an aluminum alloy material is easy to use as a method for producing an aluminum alloy material of the JIS-A5000 series.

[0058] <Advantages> Since the manufacturing method for the aluminum alloy material uses the impurity removal method, it is possible to recycle aluminum.

[0059] [Other embodiments] The above embodiments do not limit the configuration of the present invention. Accordingly, the above embodiments allow for the omission, substitution, or addition of components of each part of the above embodiments based on the description herein and common technical knowledge, and all such omissions should be interpreted as falling within the scope of the present invention.

[0060] For example, in the impurity removal method, the molten metal may be stirred when generating the intermetallic compound in the holding step S2. However, the impurity removal method can easily generate the intermetallic compound without stirring the molten metal.

[0061] The method for manufacturing the aluminum alloy is not limited to a configuration that includes the above-described component adjustment step. For example, if the method for manufacturing the aluminum alloy does not include the above-described component adjustment step, the aluminum alloy obtained by the method can be used as an intermediate alloy, and the components of this intermediate alloy can be adjusted separately. [Examples]

[0062] The present invention will be described in detail below based on examples, but the present invention should not be interpreted as being limited based on the description of these examples.

[0063] [No.1 to No.6] Molten metal was prepared by dissolving A5052, Al-5%Cr, Al-5%Ti, Al-5%V, Al-5%Zr, pure Mg, and pure Al in a graphite crucible so that Mg and the impurity elements shown in Table 1 were present in the amounts shown in Table 1. Subsequently, this molten metal was cooled to the holding temperature shown in Table 1 and allowed to stand for the holding time shown in Table 1. After that, the furnace power was turned off and the molten metal solidified, and a portion was taken from the top of the resulting ingot and the impurity concentration was measured by ICP emission spectrometry. The measurement results are shown in Table 1. In the above ingot, it is thought that compounds containing impurity elements precipitated at the bottom, so the measurement results in Table 1 are considered to represent the impurity content in the Al-Mg alloy portion.

[0064] [No. 7 and No. 8] Molten metal was prepared by dissolving A5052 and pure Mg in a Si-C crucible so that Mg and the impurity elements shown in Table 1 were present in the amounts shown in Table 1. Subsequently, this molten metal was cooled to the holding temperature shown in Table 1 and allowed to stand for the holding time shown in Table 1. After that, the crucible was tilted to dispense only the supernatant so that the residual molten metal was between 10% and 20% by mass of the dissolved amount. After dispensing, this supernatant was solidified and the impurity concentration was measured by solid-state emission spectrometry. The measurement results are shown in Table 1.

[0065] [Table 1]

[0066] As shown in Table 1, it can be seen that impurities such as Cr, Ti, V, and Zr can be removed by setting the Mg content in the molten metal to 5% to 18% by mass and maintaining the molten metal at a temperature of 530°C to 700°C. [Industrial applicability]

[0067] As described above, the impurity removal method according to one aspect of the present invention is suitable for removing impurities mixed into aluminum or aluminum alloys.

Claims

1. A mixing step in which Mg or Mg alloy is mixed into a molten metal containing aluminum or an aluminum alloy and impurities such that the Mg content in the molten metal is 5% by mass or more and less than 11% by mass, A holding step is performed to maintain the molten metal after the mixing step in a range of 530°C to 700°C. A separation step for separating the intermetallic compounds generated in the holding step from or within the molten metal, A casting process in which the molten metal after the intermetallic compound has been separated by the above separation process is cast. Equipped with, The above impurity is at least one selected from the group consisting of Cr, Ti, V, and Zr. A method for manufacturing aluminum alloys, comprising the above casting process, to produce JIS-A5000 series aluminum alloys.

2. The method for producing an aluminum alloy according to claim 1, wherein the holding time of the molten metal in the holding step is 3 minutes or more.

3. A method for producing an aluminum alloy according to claim 1 or 2, further comprising a component adjustment step for adjusting the components of the molten metal after the intermetallic compounds have been separated by the separation step, prior to the casting step described above.

4. Using the method for manufacturing an aluminum alloy according to claim 1 or claim 2, A method for manufacturing an aluminum alloy material, comprising a plastic working step for plastically working the aluminum alloy obtained through the above casting step.

5. A method for producing an aluminum alloy material according to claim 4, further comprising a component adjustment step for adjusting the components of the molten metal after the intermetallic compound has been separated by the above separation step.

Images