Manufacturing method for aluminum alloys

Abstract

To efficiently produce large quantities of aluminum alloy with low iron content from aluminum-containing scrap. [Solution] The method of the present invention involves adding Mn and Cr to a molten aluminum alloy containing Si and Fe, and adjusting the concentration so that the mass ratio of Fe / Mn is 0.2 to 1.0 and the mass ratio of Cr / Mn is 0.1 to 0.5 (hereinafter referred to as "first step"). The process involves cooling the prepared molten aluminum alloy to a temperature 5 to 40°C higher than the temperature at which solid-phase aluminum crystallization begins (hereinafter referred to as the "second step"), and The process includes a step (hereinafter referred to as the "third step") of recovering the supernatant of the molten aluminum alloy and separating the molten aluminum alloy containing the solid produced in the second step from the molten aluminum alloy with a lower solid content.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing an aluminum alloy.

Background Art

[0002] As a countermeasure against environmental problems, in the automotive industry, in order to improve fuel efficiency, research has been actively conducted to convert the iron-based materials that have been mainly used conventionally into lightweight materials such as aluminum, magnesium, or carbon materials. Generally, these lightweight materials require a large amount of energy during production, and the large amount of carbon dioxide emissions, which is a greenhouse gas, has become a major problem.

[0003] Among the above-mentioned lightweight materials, aluminum is the second most produced after iron. Due to the large production volume, a large amount of scrap such as aluminum cans and aluminum building materials is generated. Therefore, for aluminum, a recycling system for collecting scrap and recycling it into aluminum ingots has been established. According to Non-Patent Document 1, the amount of carbon dioxide gas emitted when recycling aluminum is about 3% of the aluminum ingots (new ingots) produced by electrolytic smelting of bauxite. That is, by expanding the use of recycled aluminum ingots, it greatly contributes not only to improving fuel efficiency by reducing the weight of vehicles but also to suppressing the amount of carbon dioxide gas emitted when manufacturing aluminum.

[0004] Incidentally, recycled aluminum ingots, which are primarily made from scrap, contain impurities derived from the scrap. Among these impurities, iron (Fe) is added as an active ingredient to aluminum die-cast products and electrical wires. Furthermore, aluminum window frames have assembly screws and other components attached. Therefore, Fe is inevitably included in the molten aluminum alloy obtained by melting these scraps. However, Fe in aluminum alloys forms Al-Fe or Al-Fe-Si compounds, which reduce ductility and toughness. Consequently, aluminum scrap containing Fe as described above is mostly recycled into alloy ingots with loose iron content regulations, such as AD12.1, a die-cast alloy ingot conforming to the JIS H 2118 standard, which is a major obstacle to expanding the use of recycled ingots.

[0005] In light of the above situation, various methods for reducing the amount of Fe in recycled aluminum alloys are being investigated. For example, Patent Document 1 discloses an aluminum purification method in which the outer circumference near the top of a container holding molten aluminum is cooled to cause primary aluminum crystals to crystallize on the inner circumference of the container, which are then peeled off from the inner circumference of the container and deposited at the bottom of the container, compacted uniformly, and the molten metal is discharged to obtain primary aluminum crystals. Patent Document 1 states that high-purity aluminum in which Fe, Si, etc. are suppressed to less than a few mass ppm can be obtained by the above method.

[0006] Furthermore, Patent Document 2 discloses a method for regenerating an Al alloy, comprising the steps of: preparing a first molten metal by melting an Fe·Mn-containing material containing Fe and Mn with an Al alloy raw material; holding the first molten metal at a separation temperature at which Fe compounds crystallize; and extracting a second molten metal from which at least a portion of the Fe compounds crystallized is removed. Patent Document 2 states that by this method, a regenerated Al alloy (molten metal) with a sufficiently reduced Fe concentration can be obtained in a short time from Al alloy raw materials such as scrap. [Prior art documents] [Non-patent literature]

[0007] [Non-Patent Document 1] Shoji Aoki, Light Metals, 2013, Vol. 63, pp. 260-270. [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2002-155322 [Patent Document 2] Japanese Patent Publication No. 2020-111808 [Overview of the project] [Problems that the invention aims to solve]

[0009] However, while the method described in Patent Document 1 yields solid-phase aluminum with very low Fe content, it requires meticulous temperature control and the solidification process is energy-intensive, posing environmental problems. Furthermore, the method described in Patent Document 2 has limitations in the amount of Fe reduction, resulting in recycled aluminum that only meets the standards of JIS-AD12.1, which has a relatively high Fe content. Therefore, a technology that can solve the above problems was desired. [Means for solving the problem]

[0010] As a result of diligent research by the inventors, we discovered that the above problems can be solved by a specific method, leading to the present invention. In other words, the present invention is [1] A step of adding Mn and Cr to molten aluminum alloy containing Si and Fe to adjust the concentration so that the mass ratio of Fe / Mn is 0.2 to 1.0 and the mass ratio of Cr / Mn is 0.1 to 0.5 (hereinafter referred to as "the first step"), The process involves cooling the prepared molten aluminum alloy to a temperature 5 to 40°C higher than the temperature at which solid-phase aluminum crystallization begins (hereinafter referred to as the "second step"), and A step of collecting the supernatant of the molten aluminum alloy and separating the molten aluminum alloy containing the solid produced in the second step from the molten aluminum alloy with a lower solid content (hereinafter referred to as the "third step"), A method for producing a refined aluminum alloy containing, [2] The manufacturing method according to [1], wherein in the first step, Si is further added to the molten aluminum alloy to adjust the Si concentration in the molten aluminum alloy to 4 to 14% by mass, and [3] The manufacturing method according to [1], further comprising the step of heating the molten aluminum alloy containing the solid produced in the second step to a temperature at which the solid melts, and recovering the molten metal obtained by the heating, after the third step, Regarding. [Effects of the Invention]

[0011] The method of the present invention makes it possible to mass-produce aluminum alloys with a low Fe content from aluminum alloys that inevitably contain Fe, such as scrap-derived aluminum alloys, in an efficient manner. [Modes for carrying out the invention]

[0012] As described above, the present invention involves a step of adding Mn and Cr to a molten aluminum alloy containing Si and Fe, and adjusting the concentration so that the mass ratio of Fe / Mn is 0.2 to 1.0 and the mass ratio of Cr / Mn is 0.1 to 0.5 (hereinafter referred to as the "first step"). The process involves cooling the prepared molten aluminum alloy to a temperature 5 to 40°C higher than the temperature at which solid-phase aluminum crystallization begins (hereinafter referred to as the "second step"), and The process includes a step (hereinafter referred to as the "third step") in which the supernatant of the molten aluminum alloy is collected and separated into the molten aluminum alloy containing the solid produced in the second step and the molten aluminum alloy with a lower solid content. Each of the above steps will be described in detail below.

[0013] 1.First step The first step involves adding Mn and Cr to molten aluminum alloy containing Si and Fe, and adjusting the concentration so that the mass ratio of Fe / Mn is 0.2 to 1.0 and the mass ratio of Cr / Mn is 0.1 to 0.5. The molten aluminum alloy containing Si and Fe can be any molten metal containing Si and Fe that is used in the method of the present invention. Specific examples of such molten metals include, for example, aluminum scrap containing Fe and Si, such as aluminum die-cast products, electrical wires, and aluminum sashes with assembly screws attached. When producing molten aluminum alloy from these scraps, it is preferable to place the scrap in a heating furnace and heat it to a normal temperature for melting the scrap, for example, 680-800°C. These scrap-derived molten metals generally contain Fe and Si as unavoidable impurities. There are no particular restrictions on the Si content; it is sufficient that the amount of Si necessary for removing the Fe contained in the molten metal is present.

[0014] Furthermore, it is preferable to adjust the amount of Si contained in the molten metal to preferably 4 to 14% by mass, more preferably 6 to 13% by mass, and even more preferably 10 to 13% by mass. By setting the amount of Si in the molten metal within the above numerical range, it is possible to further improve the efficiency of removing Fe contained in the molten metal while minimizing the amount of Si used, and by lowering the crystallization start temperature of solid-phase aluminum, the crystallization of solid-phase aluminum is further suppressed in the cooling process in the second step described later, making the separation of the solid and the molten aluminum alloy described later easier. The amount of Si in the molten metal can be adjusted, for example, by using metallic silicon.

[0015] Mn and Cr are added to the molten metal to adjust the concentration. In the concentration adjustment, the mass ratio of Fe / Mn is preferably adjusted to 0.2 to 1.0, more preferably 0.3 to 0.8. By setting the mass ratio of Fe / Mn within the above numerical range, while suppressing the amount of Mn used as much as possible, the removal efficiency of Fe contained in the molten metal can be further increased, and the amount of Mn contained in the finally obtained aluminum alloy can be further suppressed. In addition, in the concentration adjustment, the mass ratio of Cr / Mn is preferably adjusted to 0.1 to 0.5, more preferably 0.15 to 0.4. By setting the mass ratio of Cr / Mn within the above numerical range, while suppressing the amount of Cr used as much as possible, the removal efficiency of Fe contained in the molten metal can be further increased, and the amount of Cr contained in the finally obtained aluminum alloy can be further suppressed. When adjusting the concentration of Mn, for example, tablets made of metallic manganese, an alloy of manganese and other metals, such as an alloy of aluminum and metallic manganese, can be used. When adjusting the concentration of Cr, for example, tablets made of metallic chromium, an alloy of chromium and other metals, such as an alloy of aluminum and metallic chromium, can be used.

[0016] In addition, the measurement of the component amounts of Fe, Si, Mn, Cr, etc. in the molten metal can be performed, for example, by using a solid emission spectroscopic analyzer (model number ARL 3460) manufactured by Thermo Electron Corporation to measure a test piece obtained by solidifying the molten metal.

[0017] 2. Second step The second step is a step of cooling the aluminum alloy molten metal prepared in the first step to a temperature 5 to 40 °C higher than the solid-phase aluminum crystallization start temperature. By setting the cooling temperature to a temperature 5 to 40 °C higher than the solid-phase aluminum crystallization start temperature, while further suppressing the crystallization of solid-phase aluminum, an alloy containing Al, Fe, Si, Mn, and Cr (for example, specifically, Al 15The precipitation of Si2(Fe,Mn,Cr)3 can be further promoted, enabling more efficient removal of Fe from the molten aluminum alloy. In the present invention, the "solid-phase aluminum precipitation start temperature" specifically refers to the temperature at which the precipitation of aluminum contained in the molten aluminum alloy obtained in the first step starts. Since the temperature at which the precipitation of aluminum starts varies depending on the amounts of other components contained in aluminum, when performing the second step, it is preferable to measure in advance the amounts of components other than aluminum contained in the molten aluminum alloy before cooling. Here, the "components other than aluminum" specifically refers to the components defined in JISH2211:2010 Aluminum Alloy Ingot for Castings (see Tables 3 and 4) or H2118:2006 Aluminum Alloy Ingot for Die Castings (see the table), and more specifically, the metal elements of Cu, Si, Mg, Zn, Fe, Mn, Cr, Ni, Sn, Pb, and Ti. The amounts of the above components may be measured, for example, in the same manner as in the first step, using a solid-state emission spectroscopic analyzer (model number ARL 3460) manufactured by Thermo Electron Corporation on a test piece obtained by solidifying the molten aluminum alloy. By using known thermodynamic simulation software such as Thermo-Calc of Itochu Techno-Solutions Corporation, for example, the solid-phase aluminum precipitation start temperature of the molten aluminum alloy obtained in the first step can be calculated.

[0018] The method of cooling the molten aluminum alloy can generally use any cooling means used when handling molten metals. As such cooling means, interruption of heating of the molten metal, air cooling or water cooling of the container containing the molten aluminum alloy, etc. can be used without particular limitation. As described above, in the second step, Fe contained in the molten aluminum alloy forms compounds with other metal elements. Since the precipitation start temperature of the above compounds is higher than the precipitation start temperature of solid-phase aluminum, it precipitates as a solid in the liquid-phase molten aluminum alloy by the cooling performed in the second step. After performing the cooling step, the molten aluminum alloy may be allowed to stand at the cooled temperature in order to settle the precipitated solid.

[0019] 3.Third step The third step is to collect the supernatant of the molten aluminum alloy cooled in the second step and separate the molten aluminum alloy containing the solid generated in the second step from the molten aluminum alloy with a lower solid content. Here, "supernatant" refers to, for example, the upper 70-80% volume of the molten aluminum alloy contained in the heating furnace when a heating furnace is used to manufacture the molten aluminum alloy. By setting the amount of supernatant within the above numerical range, it is possible to obtain a higher purity molten aluminum alloy while further suppressing the content of the Fe-containing solid generated in the second step. Any means used to recover molten metal can be used to recover the supernatant. Examples of such recovery methods include tilt tapping and pumping using a pump. By recovering the supernatant as described above, the molten aluminum alloy containing the solid generated in the second step is separated from the molten aluminum alloy with a lower solid content. The supernatant recovered as described above contains a lower solid content from the solid generated in the second step, and preferably contains no solid at all. Therefore, the supernatant obtained has a low content of Fe as an impurity, as well as Mn and Cr added in the first step. By cooling the obtained supernatant, a high-purity metallic aluminum alloy that can be used for aluminum casting alloy ingots or new ingot alloy ingots can be obtained.

[0020] As described above, the method of the present invention is carried out in a simple operation of heating the scrap at the normal temperature for melting it, adding an additional metal, and then performing a cooling process. Therefore, according to the method of the present invention, it is possible to produce a larger amount of aluminum alloy from a larger amount of scrap. Furthermore, since the amount of energy required in the method of the present invention is lower than the amount of energy required to produce new aluminum ingots, CO2 emissions can be further suppressed and the burden on the environment can be minimized.

[0021] Furthermore, after the third step, the molten aluminum alloy containing the solid produced in the second step may be further heated to the temperature at which the solid melts, and the molten metal obtained by the heating may be recovered. As described above, when producing molten aluminum alloy from scrap, the scrap is heated in a heating furnace. Also, as a result of recovering the supernatant of the molten aluminum alloy in the third step, the molten aluminum alloy containing the solid remains in the heating furnace. By heating the molten aluminum alloy containing the solid to the temperature at which the solid melts, specifically, for example, a temperature of 860°C or higher, the solid melts, and the molten aluminum alloy remaining in the heating furnace becomes molten metal consisting only of the liquid phase. When the molten metal is reheated, in addition to the molten metal, slag consisting mainly of oxides may be generated. When such slag is generated, care should be taken not to mix the generated slag with the molten aluminum alloy with high concentrations of Fe, Mn, and Cr, and the molten metal should be recovered. When recovering the molten metal, any means used when recovering molten metal can be used. Examples of such recovery methods include pumping out the water using tilting taps and pumping pumps.

[0022] Finally, if any residue has been generated, it is collected from the heating furnace. There are no particular restrictions on the collection method; it may be scraped out using a metal claw-shaped jig. In this way, virtually no residue remains in the furnace, making it possible to perform this method continuously.

[0023] The molten aluminum alloy and residue with high concentrations of Fe, Mn, and Cr recovered as described above can be used as a deoxidizing agent for steel materials, etc.

[0024] The present invention will be described in more detail below with reference to examples. It goes without saying that the examples do not affect the scope of the present invention. [Examples]

[0025] 1. Small-lot testing (1) Raw materials used JIS H2102-2011 Aluminum Ingot P0610A JIS G2312-1986 Metallic Silicon No. 1 • Al-10%Fe matrix alloy manufactured by Tomatsu Metallurgy Co., Ltd. • Al-10%Mn matrix alloy manufactured by Tomatsu Metallurgy Co., Ltd. • Al-10%Cr matrix alloy manufactured by Tomatsu Metallurgy Co., Ltd.

[0026] (2) Test method In a Tokyo Molex Crucible A8 graphite crucible, 2.7 kg of industrial aluminum raw material (99.7% purity), metallic silicon, Al-10%Fe master alloy, Al-10%Mn master alloy, and Al-10%Cr master alloy were placed according to the metal composition ratios shown in Table 1 below. This mixture was then heated to 800°C in an electric furnace (model MM-111P) manufactured by Masuda Rika Kogyo Co., Ltd. to obtain molten aluminum alloy (first step). 80 g of the obtained molten aluminum alloy was recovered to prepare a test specimen, and the amounts of Cu, Si, Mg, Zn, Fe, Mn, Cr, Ni, Sn, Pb, and Ti were measured using a Thermo Electron solid emission spectrometer (model ARL 3460). Based on the measured results, the solid-phase aluminum crystallization start temperature calculated using Thermo-Calc by Itochu Techno-Solutions Corporation is shown in Table 1.

[0027] [Table 1]

[0028] Next, the obtained molten aluminum alloy was cooled to a temperature of +23°C above the crystallization start temperature of each solid phase aluminum (second step). Then, the supernatant, equivalent to 70% of the upper part of the molten metal, was collected by hand (third step). Test specimens were prepared using 80g of the molten metal collected by hand, and measured using a Thermo Electron solid-state emission spectrometer (model ARL 3460). The measurement results are shown in Table 2 below. Note that in Table 2, the Fe removal rate is where Fe is the Fe concentration after cooling is complete, and where Fe is the Fe concentration before cooling began. 0 (1-Fe / Fe 0 This value was derived using the formula ) × 100.

[0029] [Table 2]

[0030] As shown in Table 2, the Fe removal rate in the examples was high, exceeding 60%. In contrast, the Fe removal rates of Comparative Examples 1-6 were lower than those of Examples 1-4. Furthermore, the Fe concentration in Examples 1-4 was in the range of 0.25-0.34 mass%, which is low enough to be used as an alloy ingot for casting. In addition, Examples 1-4 had a Mn content of 0.35-0.82 mass% and a Cr content of 0.03-0.10 mass%, both of which were sufficient to be used as an alloy ingot for casting.

[0031] 2. Large-scale lot testing (1) Raw materials used • Base metal used as a raw material for aluminum secondary alloys • Beverage cans and spray can scraps (hereinafter referred to as "can scraps") JIS G2312-1986 Metallic Silicon No. 1 • Metallic manganese • Al-75%Cr Tablets

[0032] (2) Test method Large-scale testing was conducted using a heating furnace with a nominal capacity of 3 tons. A burner-heated rotary furnace was used as the heating furnace. Approximately 3 to 5 tons of base metal (Examples 5 and 6) or scrap metal (Examples 7 to 9) were loaded into the rotary furnace and heated to 800°C to obtain molten aluminum alloy. While maintaining the heating temperature of 800°C, a portion of the obtained molten aluminum alloy was collected to prepare test specimens, which were measured using a Thermo Electron solid-state emission spectrometer (model ARL 3460). Metallic silicon, metallic manganese, and Al-75%Cr tablets were added to the obtained molten metal, and samples were collected and measured in the same manner as above, adjusting the raw material ratio to the ratio shown in Table 3 below (first step). Furthermore, 80 g of the molten aluminum alloy obtained above was recovered to prepare test specimens, and the amounts of Cu, Si, Mg, Zn, Fe, Mn, Cr, Ni, Sn, Pb, and Ti were measured using a Thermo Electron solid-state emission spectrometer (model ARL 3460). Based on the measured results, the solid-phase aluminum crystallization start temperature calculated using Thermo-Calc from ITOCHU Techno-Solutions Corporation is shown in Table 3.

[0033] [Table 3]

[0034] Next, the obtained molten aluminum alloy was cooled to a temperature of solid-phase aluminum crystallization initiation temperature + 23°C for Examples 5-8, and to a temperature of solid-phase aluminum crystallization initiation temperature + 20°C for Example 9 (second step). Then, the molten metal was tilted and the supernatant corresponding to the upper 70% of the molten metal was collected (third step). Test specimens were prepared using 80g of the collected molten metal and measured using a Thermo Electron solid-state emission spectrometer (model ARL 3460). The measurement results are shown in Table 4 below. Note that in Table 4, the Fe removal rate is calculated as the Fe concentration after cooling is complete (Fe) and the Fe concentration before cooling is started (Fe). 0 (1-Fe / Fe 0 This value was derived using the formula ) × 100.

[0035] [Table 4]

[0036] As shown in Table 4, all examples showed a high Fe removal rate of 70% or more, confirming that the method of the present invention makes it possible to produce large quantities of aluminum alloy with low Fe content. The Fe concentrations in Examples 5 and 6 were 0.25% by mass to 0.33% by mass, which are levels that can be used as alloy ingots for casting. Furthermore, the Fe concentrations in Examples 7 and 8 were 0.12% by mass and 0.16% by mass, respectively, which are levels that can be used as high-ductility alloy ingots using new aluminum ingots.

[0037] After tilting the furnace to pour the supernatant molten aluminum alloy, the furnace contained both the unrecovered molten aluminum alloy and a solid (Al-Si-Fe compound) that had settled at the bottom. The furnace was heated to approximately 900°C to melt the solid, then the heating was stopped, and the molten aluminum alloy, which had melted the solid, was poured into an iron container using the tilting method until it flowed completely. A sample of the molten aluminum alloy from the iron container was taken to prepare a test piece for component analysis, and it was measured using a Thermo Electron solid emission spectrometer (model ARL 3460). The measurement results are shown in Table 5.

[0038] [Table 5]

[0039] In all of Examples 5-9, the Si concentration was not significantly different compared to the supernatant molten aluminum alloy, while the Fe, Mn, and Cr concentrations increased dramatically. These results confirm that by removing the solid, not only Fe but also the added Mn and Cr can be recovered.

[0040] Furthermore, after the molten aluminum alloy, which contained the melted solid, was poured out by tilting, slag generated during reheating remained in the furnace. The slag was scraped out into an iron container using an iron claw-shaped jig.

[0041] Table 6 shows the recovered amounts of the supernatant molten aluminum alloy after cooling (referred to as supernatant molten metal), the molten aluminum alloy after reheating to dissolve the Al-Si-Fe compound (referred to as high-impurity molten metal), and the scraped-off slag (referred to as residue) recovered in Examples 5 to 9, as well as their ratios to the total recovered amount of each material.

[0042] [Table 6]

[0043] In Examples 5 and 6, almost no slag was generated after melting the base metal of the aluminum raw material, so the total amount of raw material loaded and recovered were almost equal. In other words, the entire amount of molten aluminum alloy before cooling began was recovered as supernatant molten metal, high-impurity molten metal, and residue. This means that the method can be carried out continuously without performing operations such as furnace cleaning. In fact, after recovering the residue in Example 7, the aluminum raw material for Example 8 was loaded immediately and the process was carried out.

[0044] In Examples 7-9, the amount of raw material loaded and the total amount recovered do not match because slag was removed after the aluminum scrap raw material was dissolved. The amount of slag generated after dissolution varies each time depending on the presence or absence of paint, residual moisture, and the degree of dirt and foreign matter contamination in the scrap can. However, from the results of Examples 5 and 6, it is clear that the amount of molten aluminum alloy before cooling begins matches the total amount recovered. The slag removed from the furnace after dissolving the scrap can can be separated into molten aluminum alloy and ash by a known ash-pressing treatment. The molten aluminum alloy recovered by the ash-pressing treatment may be returned to the molten aluminum alloy before cooling begins, and the ash recovered by the ash-pressing treatment can be used as a deoxidizer for steel materials, etc.

[0045] The recovery rate of the supernatant molten aluminum alloy in Examples 5-9 was 70%-80%, and the recovery rate increased as the Fe concentration before cooling began to decrease. Furthermore, the recovered highly impurity molten metal and residue can be used as a deoxidizing agent for steel materials.

[0046] Based on the above results, the aluminum alloy manufacturing method of the present invention makes it possible to efficiently obtain large quantities of aluminum alloys with low Fe, Mn, and Cr concentrations that can be used for aluminum casting alloy ingots and even new ingot alloy ingots, from low-grade scrap that was previously limited to use for secondary alloy ingots. Furthermore, the resulting molten aluminum alloy and residues with high Fe, Mn, and Cr concentrations can be used as deoxidizers for steel materials, etc. [Industrial applicability]

[0047] The method of the present invention enables the efficient mass production of aluminum alloys with a low Fe content from aluminum scrap containing Fe. Therefore, the effective utilization of scrap is promoted while minimizing the burden on the environment.

Claims

1. A step of adding Mn and Cr to molten aluminum alloy containing Si and Fe to adjust the concentration so that the mass ratio of Fe / Mn is 0.2 to 1.0 and the mass ratio of Cr / Mn is 0.1 to 0.5 (hereinafter referred to as "the first step"), The process involves cooling the prepared molten aluminum alloy to a temperature 5 to 40°C higher than the solid-phase aluminum crystallization start temperature (hereinafter referred to as the "second step"), and A step of collecting the supernatant of the molten aluminum alloy and separating the molten aluminum alloy containing the solid produced in the second step from the molten aluminum alloy with a lower solid content (hereinafter referred to as the "third step"), A method for producing a refined aluminum alloy containing [a specific substance].

2. The manufacturing method according to claim 1, wherein in the first step, Si is further added to the molten aluminum alloy to adjust the Si concentration in the molten aluminum alloy to 4 to 14% by mass.

3. The manufacturing method according to claim 1, further comprising the step of heating the molten aluminum alloy containing the solid produced in the second step to a temperature at which the solid melts, after the third step, and recovering the molten metal obtained by the heating.

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