Method for removing magnesium from molten aluminum and aluminum raw material

Abstract

In a method for removing magnesium from molten aluminum according to the present invention, molten aluminum containing magnesium is produced from an aluminum raw material, and at least a portion of the magnesium in the molten aluminum is removed from the molten aluminum by using a flux. The flux is composed of fluoride salts. The melting point of the flux is 550°C or higher and below the liquidus temperature of the aluminum raw material. The flux may be a mixture of two or more types of fluoride salts.

Description

Method for removing magnesium from molten aluminum and aluminum raw material

[0001] The present invention relates to a method for removing magnesium from molten aluminum and an aluminum raw material.

[0002] Aluminum has the property that recycled aluminum can be produced by melting used aluminum products with less energy than the energy required to produce new aluminum from bauxite. Therefore, from the perspective of reducing the environmental impact of manufacturing aluminum products, it is strongly desired to increase the proportion of recycled aluminum used in the production of aluminum products. However, since the amount of alloying elements other than aluminum contained in recycled aluminum tends to be higher than that of new aluminum, it can be difficult to adjust the chemical composition within the desired range when manufacturing aluminum products using recycled aluminum.

[0003] To address this problem, various techniques have been proposed for reducing the content of alloy elements in recycled ingots. For example, Patent Document 1 describes a method for refining molten aluminum and aluminum alloys, which is characterized by adding one type of sulfate compound or a mixture of two or more different sulfate compounds as a refining agent to molten aluminum and aluminum alloys.

[0004] Japanese Patent Application Laid-Open No. 2003-253353

[0005] However, the refining agent used in Patent Document 1 has a relatively high decomposition temperature, which poses a problem that the temperature of the molten aluminum needs to be increased in order to remove the magnesium, and the energy required to remove the magnesium tends to be large.

[0006] The present invention has been made in view of the above background, and aims to provide a method for removing magnesium from molten aluminum that can easily reduce the energy required for removing magnesium.

[0007] As a result of extensive research, the present inventors have unexpectedly discovered that fluoride-based fluxes, which have conventionally been used for purposes other than the removal of magnesium, also have the effect of removing magnesium, leading to the completion of the present invention.

[0008] That is, one aspect of the present invention is a method for removing magnesium from molten aluminum, which includes preparing molten aluminum containing magnesium from an aluminum raw material and removing at least a portion of the magnesium in the molten aluminum from the molten aluminum using a flux, wherein the flux is made of a fluoride salt, and the melting point of the flux is 550°C or higher and lower than the liquidus temperature of the aluminum raw material.

[0009] In the removal method, a flux composed of a fluoride salt and having a melting point of 550°C or higher but lower than the liquidus temperature of the aluminum raw material is used. Because the melting point of the flux is lower than the liquidus temperature of the aluminum raw material, when the flux is added to the aluminum raw material, for example, the flux melts and activates before the aluminum raw material melts. Furthermore, because the molten aluminum has a temperature equal to or higher than the melting point of the flux, when the flux is added to the molten aluminum, for example, the flux added to the molten aluminum quickly melts and activates. Therefore, by using a flux having a melting point within the specified range, heating solely for the purpose of flux activation can be avoided, and the energy required for magnesium removal can be easily reduced.

[0010] As described above, by using the flux, at least a portion of the magnesium in the molten aluminum can be removed from the molten aluminum.

[0011] Therefore, according to the above-described embodiment, it is possible to provide a method for removing magnesium from molten aluminum that can easily reduce the energy required for removing magnesium.

[0012] In the removal method, aluminum raw materials that can be used include aluminum bullion, intermediate alloys, and aluminum scrap containing aluminum as a main component. In this specification, "aluminum scrap" includes, for example, in-house scrap from casting (pre-rolled aluminum scrap) generated in a company's own factory, as well as pre-consumer recycled materials and post-consumer materials defined in UL 2809. Pre-consumer recycled materials include scrap removed as waste during the manufacturing and distribution processes of aluminum products before they reach end users. More specifically, pre-consumer materials include in-house scrap from casting (pre-rolled aluminum scrap) generated in a company's own factory and scrap generated during the manufacturing process of aluminum products. Note that pre-consumer recycled materials do not include pre-consumer recycled materials.

[0013] Post-consumer materials also include aluminum products that can no longer be used for their intended purpose after being delivered to an end user, such as aluminum products that have been discarded after use by the end user.

[0014] In the above-described manufacturing method, examples of aluminum scrap that can be used include pre-consumer recycled materials derived from aluminum can presses (so-called UBCs) and window sashes, post-consumer materials derived from window sashes, pre-consumer recycled materials derived from computer casings, post-consumer materials derived from computer casings, pre-consumer recycled materials derived from railroad vehicle components, post-consumer materials derived from railroad vehicle components, pre-consumer recycled materials derived from automobile components, and post-consumer materials derived from automobile components. Furthermore, post-consumer materials known as "zorba" can also be used as aluminum scrap. Zorba is specifically a mixture primarily composed of aluminum recovered from scrap obtained by shredding scrapped automobiles and home appliances.

[0015] Among these aluminum scraps, aluminum scrap derived from aluminum products manufactured by brazing, such as aluminum heat exchangers for automobiles, often has a large amount of flux attached thereto for the brazing process, and therefore aluminum scrap derived from aluminum products manufactured by brazing is suitable as an aluminum raw material.

[0016] The aluminum raw material preferably contains aluminum scrap. Aluminum scrap contains aluminum materials (including aluminum and aluminum alloys; the same applies hereinafter) having chemical compositions that correspond to the intended use of the original aluminum product, and may contain aluminum materials with high magnesium concentrations depending on the intended use of the original aluminum product. Therefore, in the past, when attempting to produce molten aluminum with a low magnesium concentration using aluminum scrap, it was necessary to add virgin aluminum or recycled aluminum with a relatively low magnesium concentration to the aluminum raw material together with the aluminum scrap to dilute the magnesium in the aluminum scrap.

[0017] In contrast, according to the removal method, since at least a portion of the magnesium in the molten aluminum can be removed using a flux, aluminum scrap containing a high concentration of magnesium can be effectively reused as an aluminum raw material, and it is expected that the environmental load will be reduced. From the viewpoint of further enhancing the effect of reducing the environmental load, the ratio of aluminum scrap to the aluminum raw material is preferably 50 mass % or more, more preferably 60 mass % or more, and even more preferably 70 mass % or more.

[0018] The form of the aluminum raw material is not particularly limited and may take various forms. For example, the aluminum raw material may be a wrought material such as a rolled plate, an extruded shape, or an extruded pipe. The aluminum raw material may also have the shape of the recovered aluminum product itself. Furthermore, the aluminum raw material may have the shape of fragments obtained by crushing a wrought material or an aluminum product.

[0019] The aluminum raw material preferably includes wrought material and / or aluminum scrap containing wrought material. Wrought material has a relatively large surface area relative to its volume, which is expected to further enhance the effect of magnesium removal by the flux. Therefore, by using wrought material and / or aluminum scrap containing wrought material as the aluminum raw material, it is expected that magnesium in the molten aluminum can be more easily removed from the molten aluminum.

[0020] The average chemical composition of the aluminum raw material, i.e., the chemical composition of the molten aluminum when the aluminum raw material is melted without adding a flux, may contain at least magnesium. The total amount of alloying elements other than magnesium contained in the aluminum raw material may be appropriately set depending on the chemical composition of the desired molten aluminum. For example, the aluminum raw material may have an average chemical composition that contains 0.005% by mass or more and 5.0% by mass or less of Mg (magnesium), with the balance being Al (aluminum) and unavoidable impurities. The aluminum raw material may contain 0.005% by mass or more and 5.0% by mass or less of Mg (magnesium), and may further contain, as optional components, one or more elements selected from the group consisting of 13.0% by mass or less of Si (silicon), 1.3% by mass or less of Fe (iron), 3.5% by mass or less of Cu (copper), 2.0% by mass or less of Mn (manganese), 0.1% by mass or less of Cr (chromium), 6.0% by mass or less of Zn (zinc), and 0.2% by mass or less of Ti (titanium), with the remainder being aluminum (aluminum) and unavoidable impurities. The average chemical composition of the aluminum raw material can be calculated, for example, by performing a calculation using the chemical components and masses of the individual aluminum raw materials.

[0021] The chemical components of the aluminum materials contained in each aluminum raw material are not particularly limited. Furthermore, the aluminum raw material may be composed of one type of aluminum material, or may be composed of two or more types of aluminum materials having different chemical components. The aluminum material contained in the aluminum raw material may be, for example, 1000 series aluminum, or an aluminum alloy such as a 2000 series alloy, a 3000 series alloy, a 4000 series alloy, a 5000 series alloy, a 6000 series alloy, a 7000 series alloy, or an 8000 series alloy.

[0022] The total amount of magnesium in the aluminum raw material is preferably 0.05 mass% or more. Such aluminum raw materials usually contain aluminum materials with relatively high magnesium concentrations, such as 3000 series alloys, 5000 series alloys, and 6000 series alloys. When these aluminum materials are used as aluminum raw materials, it can be difficult to adjust the chemical composition of the molten aluminum to a desired range. Therefore, aluminum materials with relatively high magnesium concentrations have traditionally been limited in their use as aluminum raw materials.

[0023] In contrast, according to the removal method, at least a portion of the magnesium in the molten aluminum can be removed by the flux, which further expands the range of use of aluminum materials with a relatively high magnesium concentration as aluminum raw materials, and enables the aluminum materials with a relatively high magnesium concentration to be effectively utilized as resources.

[0024] Furthermore, from the viewpoint of more reliably obtaining the effect of removing magnesium from the molten aluminum, the total amount of magnesium in the aluminum raw material is preferably 0.05 mass % or more and 5.0 mass % or less.

[0025] The flux used in the removal method is composed of a fluoride salt and has a melting point of 550°C or higher, lower than the liquidus temperature of the aluminum raw material. By using a flux having a melting point within the specified range, the removal method can easily reduce the energy required for the magnesium removal process.

[0026] If the melting point of the flux is lower than 550°C, the timing of flux activation may be too early, which may reduce the effectiveness of magnesium removal. On the other hand, if the melting point of the flux is equal to or higher than the liquidus temperature of the aluminum raw material, it may be necessary to increase the temperature of the molten aluminum to activate the flux, which may result in an increase in the energy required to remove magnesium.

[0027] The flux may be composed of one type of fluoride salt, but is preferably a mixture of two or more types of fluoride salts. By mixing two or more types of fluoride salts, the melting point of the mixture can be lowered below the melting points of the individual fluoride salts. As a result, the melting point of the flux can be more easily adjusted within the specified range.

[0028] Examples of fluoride salts that constitute the flux include metal fluorides such as NaF, KF, CaF, and AlF; fluorosilicates such as NaSiF and KSiF; NaAlF, KAlF, KAlF, and KAlF. 6、 Fluoroaluminates such as CsAlF4 and their hydrates can be used. From the viewpoint of more easily reducing the magnesium content in the molten aluminum, the flux should preferably be KAlF4, K2AlF5, K3AlF 6、 A mixture of two or more fluoride salts selected from the group consisting of CsAlF4 and hydrates thereof is preferred. As such a mixture of fluoride salts, for example, commercially available products such as NOCOLOK (registered trademark) flux and NOCOLOK (registered trademark) Cs flux can be used.

[0029] The amount of flux used is preferably 0.1 mass % or more and 10 mass % or less, more preferably 0.3 mass % or more and 10 mass % or less, and even more preferably 1.0 mass % or more and 10 mass % or less, relative to the mass of the aluminum raw material. By setting the amount of flux used within the above-mentioned specific range, the effect of removing magnesium from the molten aluminum can be further enhanced.

[0030] In the removal method, the operation of removing magnesium using a flux may be carried out after preparing molten aluminum from the aluminum raw material, or may be carried out in parallel with the operation of preparing molten aluminum from the aluminum raw material.

[0031] More specifically, in a first aspect of the removal method, an aluminum raw material having flux attached thereto is melted to produce molten aluminum, thereby making it possible to remove at least a portion of the magnesium contained in the molten aluminum from the molten aluminum.

[0032] In this embodiment, for example, a flux may be added to an aluminum raw material to prepare an aluminum raw material to which flux is attached, and then the aluminum raw material may be used to prepare molten aluminum.

[0033] The method for applying the flux to the aluminum raw material is not particularly limited, and various methods can be used. For example, the flux may be applied to the aluminum raw material by suspending the flux in a solvent such as water or an acrylic resin aqueous solution and then spraying the flux suspension onto the aluminum raw material. The flux can also be applied to the aluminum raw material by immersing the aluminum raw material in the flux suspension or by mixing the aluminum raw material with powdered flux or a flux suspension.

[0034] In this embodiment, the molten aluminum can also be prepared using an aluminum raw material to which a flux has been applied in advance. For example, in the manufacturing process of an aluminum product produced by brazing, a flux made of a fluoride salt and having a melting point within the above-mentioned specific range may be applied to the aluminum product or its component parts. Therefore, if the aluminum product or the like to which the flux has been applied is to be discarded for some reason, the aluminum product or the like can be used as an aluminum raw material to which a flux has been applied.

[0035] Furthermore, in the manufacturing process of aluminum products produced by brazing, the brazing heat is performed after the application of flux. After the brazing heat, flux that melted during the brazing heat and then solidified may adhere to the surface of the aluminum product. Furthermore, the flux that melted and then solidified has the effect of removing magnesium from the molten aluminum, just like unmelted flux. Therefore, if aluminum products, etc., are to be discarded for some reason after brazing is complete, these aluminum products, etc. can be used as aluminum raw materials with flux attached.

[0036] Although the mechanism by which magnesium is removed by the flux in this embodiment is not entirely clear, it is believed that magnesium is removed, for example, by the following mechanism. As described above, the flux attached to the aluminum raw material has a melting point within the specific range. Therefore, when the aluminum raw material is heated, the flux melts and is activated before the aluminum raw material starts to melt.

[0037] When the flux is activated, the oxide film present on the surface of the aluminum raw material is first destroyed by the flux, exposing the base material of the aluminum raw material to the surface. Meanwhile, since the magnesium contained in the aluminum raw material has a relatively low vapor pressure, it is thought that when the aluminum raw material is heated in a state in which the oxide film on the surface of the aluminum raw material has been destroyed, the magnesium in the aluminum raw material easily evaporates and is released to the outside of the aluminum raw material.

[0038] Furthermore, flux adhering to the aluminum raw material that is not consumed in the reaction with the oxide film dissolves in the molten aluminum and destroys the oxide film formed on the surface of the molten aluminum. As a result, it is believed that the magnesium in the molten aluminum evaporates and is dispersed outside the molten aluminum. Furthermore, some of the flux in the molten aluminum reacts with magnesium to form dross containing magnesium fluoride. It is believed that removing this dross from the molten aluminum can further reduce the total amount of magnesium dissolved in the molten aluminum.

[0039] As described above, in this embodiment, it is believed that the flux reacts with the oxide film present on the surface of the aluminum raw material or the molten aluminum, thereby accelerating the evaporation of magnesium in the aluminum raw material or the molten aluminum. Furthermore, it is believed that the reaction between the flux and magnesium in the molten aluminum can capture the magnesium in the molten aluminum as dross. As a result, it is believed that the total amount of magnesium in the molten aluminum can be easily reduced.

[0040] In a second embodiment of the removal method, after an aluminum raw material is melted to prepare molten aluminum, the flux is added to the molten aluminum. In this case, the flux added to the molten aluminum is activated in the molten aluminum and destroys the oxide film formed on the surface of the molten aluminum. As a result, the magnesium in the molten aluminum evaporates and is dispersed outside the molten aluminum. Furthermore, as described above, a portion of the flux in the molten aluminum reacts with magnesium to form dross containing magnesium fluoride.

[0041] Therefore, in this embodiment, it is believed that the total amount of magnesium in the molten aluminum can be easily reduced by promoting the evaporation of magnesium in the molten aluminum and forming dross containing magnesium fluoride.

[0042] From the viewpoint of avoiding unnecessary heating of the aluminum raw material and more easily reducing the energy required for removing magnesium, it is preferable to prepare molten aluminum by melting the aluminum raw material to which the flux has adhered.

[0043] Example 1 An example of the method for removing magnesium from molten aluminum is described below. The aluminum raw material used in this removal method is aluminum scrap derived from various wrought aluminum alloys, such as rolled plates and extruded pipes. The total amount of magnesium contained in the aluminum raw material is 0.53 mass% relative to the mass of the aluminum raw material. The flux used in this removal method is a mixture containing KAlF4 and K2AlF5.5H2O in a mass ratio of KAlF4:K2AlF5.5H2O = 78:22.

[0044] In this example, first, 0.3 mass % of flux is applied to the aluminum raw material. The aluminum raw material is then charged into a melting furnace and heated in the furnace to melt the aluminum raw material and produce molten aluminum. Ten minutes after the aluminum raw material is completely melted, the magnesium concentration in the molten aluminum is 0.18 mass %.

[0045] Example 2 The aluminum raw material used in the removal method of this example is aluminum scrap derived from various aluminum alloy wrought materials such as rolled plates and extruded pipes. The total amount of magnesium contained in the aluminum raw material is 0.53 mass% relative to the mass of the aluminum raw material. The flux used in the removal method of this example is the same as the flux used in Example 1.

[0046] In this example, an aluminum raw material is first charged into a melting furnace and heated to melt the aluminum raw material and produce molten aluminum. Then, 0.3 mass % of flux relative to the mass of the molten aluminum is added to the molten aluminum, and the molten aluminum is stirred. Ten minutes after the flux is added and dissolved in the molten aluminum, the magnesium concentration in the molten aluminum is 0.45 mass %.

[0047] Example 3 The aluminum raw material used in the removal method of this example is an aluminum alloy raw material. The total amount of magnesium contained in the aluminum raw material is 0.52 mass% relative to the mass of the aluminum raw material. The flux used in the removal method of this example is the same as the flux used in Example 1.

[0048] In this example, an aluminum raw material is first charged into a melting furnace and heated to melt the aluminum raw material and produce molten aluminum. Then, 0.3 mass % of flux relative to the mass of the molten aluminum is added to the molten aluminum, and the molten aluminum is stirred. Ten minutes after the flux is added and dissolved in the molten aluminum, the magnesium concentration in the molten aluminum is 0.42 mass %.

[0049] Example 4 The aluminum raw material used in the removal method of this example is an aluminum alloy bullion. The total amount of magnesium contained in the aluminum raw material is 0.53 mass% relative to the mass of the aluminum raw material. The flux used in the removal method of this example is the same as the flux used in Example 1.

[0050] In this example, an aluminum raw material is first charged into a melting furnace and heated to melt the aluminum raw material and produce molten aluminum. Then, a flux is added to the molten aluminum in an amount of 1.0 mass % relative to the mass of the molten aluminum, and the molten aluminum is stirred. Ten minutes after the flux is added and dissolved in the molten aluminum, the magnesium concentration in the molten aluminum is 0.34 mass %.

[0051] Example 5 The aluminum raw material used in the removal method of this example is an aluminum alloy raw material. The total amount of magnesium contained in the aluminum raw material is 0.53 mass% relative to the mass of the aluminum raw material. The flux used in the removal method of this example is the same as the flux used in Example 1.

[0052] In this example, an aluminum raw material is first charged into a melting furnace and heated to melt the aluminum raw material and produce molten aluminum. Subsequently, a flux is added to the molten aluminum in an amount of 3.0 mass% relative to the mass of the molten aluminum, and the molten aluminum is stirred. Ten minutes after the flux is added and dissolved in the molten aluminum, the magnesium concentration in the molten aluminum is 0.19 mass%.

[0053] Comparative Example 1 The aluminum raw material used in the removal method of this example is aluminum scrap derived from various aluminum products. The total amount of magnesium contained in the aluminum raw material is 0.53 mass% relative to the mass of the aluminum raw material. In this example, the aluminum raw material is charged into a melting furnace without adding flux to either the aluminum raw material or the molten aluminum, and the aluminum raw material is melted by heating in the melting furnace to produce molten aluminum. The magnesium concentration in the molten aluminum obtained in this manner is 0.53 mass%.

[0054]

[0055] As shown in Table 1, in all of Examples 1 to 5, the magnesium concentration in the molten aluminum after magnesium removal was lower than the total amount of magnesium contained in the aluminum raw materials. In contrast, in Comparative Example 1, the magnesium concentration in the molten aluminum after magnesium removal was approximately the same as the total amount of magnesium contained in the aluminum raw materials. Therefore, from a comparison between Examples 1 to 5 and Comparative Example 1, it can be seen that by using a flux made of a fluoride salt and having a melting point within the above-mentioned specific range, it is possible to remove at least a portion of the magnesium in the molten aluminum.

[0056] Furthermore, a comparison between Example 1 and Example 2 reveals that the magnesium concentration in the molten aluminum can be further reduced by producing molten aluminum by melting an aluminum raw material having flux attached thereto. Furthermore, a comparison between Example 1 and Examples 3 to 5 reveals that when molten aluminum is produced by melting an aluminum raw material having flux attached thereto, the magnesium concentration in the molten aluminum can be more efficiently reduced with a smaller amount of flux than when flux is added to the molten aluminum.

[0057] Although embodiments of the method for removing magnesium from molten aluminum have been described above based on the examples, the specific embodiments of the method for removing magnesium from molten aluminum according to the present invention are not limited to those in the examples, and the configuration can be changed as appropriate within the scope of the present invention.

[0058] For example, in Examples 1 to 5, the flux is added to either the aluminum raw material or the molten aluminum, but the flux may be added to both the aluminum raw material and the molten aluminum.

[0059] Furthermore, the method for removing magnesium from molten aluminum according to the present invention can take the following aspects [1] to [8], for example.

[0060] [1] A method for removing magnesium from molten aluminum, which involves preparing molten aluminum containing magnesium from an aluminum raw material and removing at least a portion of the magnesium in the molten aluminum from the molten aluminum using a flux, wherein the flux is composed of a fluoride salt, and the melting point of the flux is 550°C or higher and lower than the liquidus temperature of the aluminum raw material.

[0061] [2] The method for removing magnesium from molten aluminum according to [1], wherein the flux is a mixture of two or more types of fluoride salts. [3] The method for removing magnesium from molten aluminum according to [2], wherein the flux is a mixture of two or more types of fluoride salts selected from the group consisting of KAlF4, K2AlF5, K3AlF6, CsAlF4, and hydrates thereof.

[0062] [4] The method for removing magnesium from molten aluminum according to any one of [1] to [3], wherein the amount of the flux used is 0.1 mass% or more and 10 mass% or less relative to the mass of the aluminum raw material. [5] The method for removing magnesium from molten aluminum according to any one of [1] to [4], wherein the aluminum raw material includes a wrought material and / or aluminum scrap comprising a wrought material. [6] The method for removing magnesium from molten aluminum according to any one of [1] to [5], wherein the total amount of magnesium in the aluminum raw material is 0.05 mass% or more.

[0063] [7] The method for removing magnesium from molten aluminum according to any one of [1] to [6], wherein the molten aluminum is prepared by melting an aluminum raw material having the flux attached thereto. [8] The method for removing magnesium from molten aluminum according to any one of [1] to [6], wherein the molten aluminum is prepared by melting the aluminum raw material and then adding the flux to the molten aluminum.

[0064] Furthermore, the aluminum raw material according to the present invention can take the following embodiment [9], for example: [9] An aluminum raw material used for producing molten aluminum, comprising: a base material made of aluminum or an aluminum alloy; and a flux adhered to a surface of the base material, wherein the flux is made of a fluoride salt and has a melting point of 550°C or higher and lower than the liquidus temperature of the base material.

Claims

1. A method for removing magnesium from molten aluminum, which involves preparing molten aluminum containing magnesium from an aluminum raw material and removing at least a portion of the magnesium in the molten aluminum from the molten aluminum using a flux, wherein the flux is composed of a fluoride salt, and the melting point of the flux is 550°C or higher and lower than the liquidus temperature of the aluminum raw material.

2. The method for removing magnesium from molten aluminum according to claim 1, wherein the flux is a mixture of two or more types of fluoride salts.

3. The method for removing magnesium from molten aluminum according to claim 2, wherein the flux is a mixture of two or more fluoride salts selected from the group consisting of KAlF4, K2AlF5, K3AlF6, CsAlF4, and hydrates thereof.

4. A method for removing magnesium from molten aluminum according to claim 1, wherein the amount of the flux used is 0.1 mass % or more and 10 mass % or less relative to the mass of the aluminum raw material.

5. The method for removing magnesium from molten aluminum according to claim 1, wherein the aluminum raw material includes wrought material and / or aluminum scrap containing wrought material.

6. A method for removing magnesium from molten aluminum according to claim 1, wherein the total amount of magnesium in the aluminum raw material is 0.05 mass% or more.

7. A method for removing magnesium from molten aluminum according to any one of claims 1 to 6, wherein the molten aluminum is produced by melting the aluminum raw material to which the flux is attached.

8. The method for removing magnesium from molten aluminum according to any one of claims 1 to 6, wherein the flux is added to the molten aluminum after the aluminum raw material is melted to prepare the molten aluminum.

9. An aluminum raw material used to prepare molten aluminum, comprising: a substrate made of aluminum or an aluminum alloy; and a flux adhered to the surface of the substrate, wherein the flux is composed of a fluoride salt and has a melting point of 550°C or higher and lower than the liquidus temperature of the substrate.

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