Mg Removing Agent and Method for Producing Aluminum Alloy

Abstract

To provide a Mg removal agent to be used for removing Mg from molten aluminum alloy.SOLUTION: A Mg removal agent of the invention is made of a chloride and copper oxide. The chloride contains at least one or more basic metal element selected from K, Na, and Ca, and Mg. The chloride contains, for example, MgCl2 of 0.2-60 mass% and KCl of 40-99.8 mass% relative to the whole amount thereof. The blending mass ratio of the chloride to the copper oxide is, for example, 0.15 or more. The chloride may be a molten salt or a mixed salt. At least a part of the chloride may be a mineral containing the basic metal element and Mg or derived from the mineral. A good example of the Mg removal agent is granular flux to be introduced into molten aluminum alloy.SELECTED DRAWING: Figure 3B

Description

Technical Field

[0001] The present invention relates to a flux for removing Mg from molten aluminum alloy.

Background Art

[0002] With the increasing awareness of environmental protection and the like, lightweight aluminum-based members are being used in various fields. Recycling scrap instead of using newly refined aluminum can promote the use of aluminum-based members while achieving energy savings, reducing environmental impact, and decarbonization.

[0003] When using scrap, various elements other than Al may be mixed in the molten metal. Unwanted or excessive elements need to be removed from the raw material molten metal (also referred to as "Al alloy molten metal") obtained by melting the scrap. As an example, descriptions related to the removal of Mg are found in the following documents.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Patent Document 4

Patent Document 5

Patent Document 6

Non-Patent Documents

[0005]

Non-Patent Document 1

Non-Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0006] Patent Document 1 describes a method (a kind of metal oxide treatment method) of reacting an Al alloy melt containing Mg with silica (SiO2) (2Mg + SiO2 → 2MgO + Si) to remove Mg as MgO.

[0007] Patent Document 2 proposes a method of adding pellets containing aluminum borate (9Al2O3·2B2O3) to an Al alloy melt containing Mg, attaching Mg onto the pellets, and removing it as a reaction product (MgAl2O4).

[0008] Patent Documents 3 and 4 propose a method of adding powdery battery slag obtained by roasting used dry batteries to an Al alloy melt containing Mg to remove Mg. The main components of the battery slag are ZnO and MnO2, and Mg is removed as a reaction product with these oxides (MgO, MgMn2O4 or MgMnO3). Chlorides contained in the battery slag enhance the wettability with the Al alloy melt and these oxides, and promote the formation of reaction products. In the case of an alkaline dry battery where the amount of chloride in the battery slag is less than that of a manganese dry battery, chlorides (a mixed salt of KCl and NaCl) are supplemented.

[0009] Patent Document 5 uses a mixed salt of magnesium chloride and zinc chloride as a refining flux for an Al alloy melt. Although expensive copper chloride is also exemplified as a salt that can be used as a flux, its specific examples are not described in Patent Document 5.

[0010] Patent Document 6 proposes purifying an Al alloy melt by further adding copper oxide powder to a flux (a mixed salt of only NaCl and KCl) dissolved on an Al alloy melt containing Mg. Specifically, 3 to 5 g of copper oxide is added to 100 g or 150 g of the mixed salt (mass ratio of copper oxide to the mixed salt: 20 to 50). It is considered that copper oxide is difficult to decompose in the mixed salt of NaCl and KCl, and only a small amount of copper oxide can be added to the mixed salt.

[0011] Non-Patent Documents 1 and 2 describe a chlorine gas treatment method and a flux treatment method. In the chlorine gas treatment method, Mg that has reacted with gases such as chlorine, hexachloroethane, and carbon tetrachloride blown into the Al alloy melt is removed as MgCl2 (Mg + Cl2 → MgCl2). In the flux treatment method, Mg that has reacted with fluorides (such as AlF3, NaAlF4, K3AlF6, etc.) added to the Al alloy melt is removed as MgF2 (for example, 3Mg + 2AlF3 → 3MgF2 + 2Al). Such treatment methods increase the amount of Al trapped in dross and lost, and also cause deterioration of the working environment and generation of harmful waste.

[0012] The present invention has been made in view of such circumstances, and an object thereof is to provide a new Mg remover and the like that can efficiently remove Mg from an Al alloy melt.

Means for Solving the Problem

[0013] As a result of intensive research to solve this problem, the present inventor has newly found that by using a flux having copper oxide and a chloride containing Mg to be removed, the concentration of Mg contained in the Al alloy melt can be efficiently reduced. By developing this result, the present invention described below has been completed.

[0014] 《Metal Remover》 The present invention is an Mg remover that contains a chloride and copper oxide, the chloride has at least one base metal element selected from K, Na, and Ca and Mg, and is used to remove Mg from an aluminum alloy melt.

[0015] According to the Mg remover of the present invention (also simply referred to as "remover"), Mg can be removed from an aluminum alloy melt (appropriately referred to as "Al alloy melt" or simply "melt") with high efficiency or low cost while avoiding the generation of harmful waste and deterioration of the working environment.

[0016] 《Method for Producing Aluminum Alloy, etc.》 The present invention is also understood as a manufacturing method (such as a purification method of an aluminum alloy or a Mg removal method) for obtaining an aluminum alloy with a reduced Mg concentration by bringing the above-described Mg removing agent into contact with a molten aluminum alloy containing Mg. The method of bringing the removing agent into contact with the molten metal is, for example, addition of the removing agent to the surface of the molten metal, forced introduction of the removing agent into the molten metal (pressure feeding by a feeder or the like), or the like.

[0017] When the molten metal before Mg removal (appropriately also referred to as "raw material molten metal") is prepared using aluminum-based scrap, the present invention may also be understood as a manufacturing method of a recycled aluminum alloy (such as a recycling method of an aluminum alloy). Note that the Al alloy after Mg removal may be used as a solidified product (ingot or the like) or may be used as it is in the form of a molten metal (including a semi-molten state).

[0018] 《Others》 (1) Unless otherwise specified, the concentrations and compositions referred to in this specification are indicated as mass ratios (mass%) with respect to the whole of the object (molten metal, composition, etc.). Appropriately, mass% is simply indicated as "%".

[0019] (2) The molten metal before Mg removal contains Mg, and as long as Al is the main component (more than 50 atomic%, 70 atomic% or more, and further 85 atomic% or more with respect to the whole molten metal), the specific composition is not limited. The Mg concentration with respect to the whole molten metal before Mg removal is not limited, but for example, it may be 3 mass% or less, and further 1 mass% or less. The molten metal or alloy after Mg removal may be used for casting or for rolled products.

[0020] (3) Unless otherwise specified, "x to y" referred to in this specification includes the lower limit value x and the upper limit value y. An arbitrary numerical value included in various numerical values or numerical ranges described in this specification can be used as a new lower limit value or upper limit value to newly establish a range such as "a to b".

Brief Description of the Drawings

[0021]

Figure 1

Figure 2

Figure 3A

Figure 3B

Figure 3C

Figure 4

Figure 5

Figure 6A

Figure 6B

Figure 7A

Figure 7B

Mode for Carrying Out the Invention

[0022] One or two or more components arbitrarily selected from this specification can be added to the components of the present invention described above. The content described in this specification can be either a method component or a component related to an object (for example, a remover or an Al alloy (molten metal)).

[0023] 《Mg Removal Principle》 The principle by which Mg is removed from the Al alloy molten metal by the removal method of the present invention is considered as follows.

[0024] (1) Redox reaction (electrochemical reaction) Mg contained in the molten Al alloy can be oxidized as follows. Anode reaction: Mg → Mg 2+ + 2e - (10a)

[0025] On the other hand, Cu contained in the remover 2+ can be reduced and precipitated as follows. Cathode reaction: Cu 2+ + 2e - → Cu (10b)

[0026] (2) Copper oxide Cu 2+ When the source is CuO, the above-mentioned redox reaction is shown as follows. CuO + Mg → Cu + MgO (1)

[0027] Based on the standard Gibbs free energy of the chlorides and oxides of the metal elements shown in Fig. 1 (also simply referred to as "Gibbs free energy"), the reaction formula (1) will proceed in a stable direction where the Gibbs free energy change ΔG is negative (ΔG < 0), that is, from the left side to the right side.

[0028] Incidentally, each Gibbs free energy shown in Fig. 1 is based on Knacke O., Kubaschwski O., Hesselmann K., "Thermochemical Properties of Inorganic Substances" (1991), SPRlNGER - VERLAG. Fig. 1 shows each Gibbs free energy at 660 °C. The tendency (magnitude relationship) of each Gibbs free energy at least in the range of 660 - 800 °C is the same as that of each Gibbs free energy shown in Fig. 1.

[0029] According to the experiments of the present inventors, since CuO is difficult to wet the molten Al alloy, even if CuO is directly added to the molten Al alloy, the reaction formula (1) did not proceed easily. Also, even when CuO was added to the molten Al alloy together with a mixed salt of only NaCl and KCl, the progress of the reaction formula (1) was still slow.

[0030] However, Cu 2+When copper chloride (CuCl₂) was used as the source, the redox reaction shown below proceeded easily. However, since CuCl₂ itself is expensive, it is not preferable as a raw material for a remover (such as a flux) used in the industrial purification of Al alloys. CuCl₂ + Mg → Cu + MgCl₂ (2b)

[0031] (3) Magnesium chloride (MgCl₂) When the present inventors further studied, it was found that when a remover containing a chloride containing Mg (for example, MgCl₂) to be removed from the Al alloy melt and CuO was used, the reaction shown below proceeded easily. CuO + MgCl₂ → CuCl₂ + MgO (2a)

[0032] The CuCl₂ obtained in reaction formula (2a) contributes to the Mg trap from the Al alloy melt by the above-described reaction formula (2b). The fact that both reaction formula (2a) and reaction formula (2b) proceed from the left side to the right side also agrees with the fact that each free energy change ΔG shown in FIG. 1 is negative (ΔG <0), which is a stable direction.

[0033] Mg trapped from the Al alloy melt into the remover changes from MgCl₂ to MgO and does not return from MgO to MgCl₂. As shown in the enlarged part of FIG. 1, this can also be understood from the fact that the free energy of magnesium oxide (MgO) is smaller than that of magnesium chloride (MgCl₂). Thus, Mg in the Al alloy melt is taken into the remover as MgO and reduced.

[0034] (4) Small brackets When reaction formula (2a) and reaction formula (2b) are combined, reaction formula (1) is obtained. Conversely, reaction formula (1) can be divided into reaction formula (2a) and reaction formula (2b) (see FIG. 1). In this case, MgCl₂ appearing in reaction formulas (2a) and (2b) is considered to act catalytically to cause reaction formula (1) to proceed from the left side to the right side.

[0035] Thus, when a remover composed of a chloride containing Mg and copper oxide is brought into contact with an Al alloy melt, the reaction formula (1) proceeds, and Mg in the Al alloy melt is removed as MgO. Note that CuO in the remover can be precipitated as reduced Cu. Such reactions are schematically shown in Fig. 2.

[0036] Incidentally, although the reason is not clear, most of the precipitated Cu is taken into the remover (molten chloride) and basically does not mix into the Al alloy melt. Also, CuO is relatively inexpensive and is suitable as a raw material for a remover (flux, etc.) used in the industrial purification of Al alloys.

[0037] 《Chloride》 The chloride preferably contains at least a base metal element and Mg. The chloride may be a metal chloride composed only of a metal element and Cl, but may also contain other non-metal elements (including halogen elements). The chloride may also contain a metal element other than Mg and a specific base metal element (for example, an alkali metal other than K, Na, Ca (such as Li, etc.) or an alkaline earth metal (such as Ba, etc.)).

[0038] The base metal element consists of one or more selected from K, Na, and Ca. The chloride of the base metal element (simply referred to as "base salt") is stable (see Fig. 1) and is not directly involved in the above-described redox reaction, etc. The base salt contributes to ensuring wettability with the Al alloy melt, collectability of Mg from the Al alloy melt, retention of products (for example, MgO and precipitated Cu), etc.

[0039] The base salt may be a simple salt or a double salt of KCl, NaCl, or CaCl2. When using a double salt, it is possible to adjust properties such as melting point, vapor pressure, density, wettability, or hygroscopicity, and reduce costs. The double salt preferably contains stable KCl with a relatively low melting point (see Fig. 1). For example, KCl may be contained in an amount of 40 to 99.8% by mass, 50 to 80% by mass, or even 55 to 60% by mass based on the total chloride. Note that NaCl may be contained in an amount of, for example, 25 to 65% by mass, 30 to 50% by mass, or even 35 to 45% by mass based on the total chloride.

[0040] The chloride (all or part) containing the base metal element and Mg may be a mixture of multiple raw material salts (mixed salt), a fused salt obtained by melting the whole raw material salt and then solidifying it, or a mineral-derived chloride such as a mineral or a chloride obtained from a mineral. As a mineral containing the base metal element and Mg, there is, for example, carnallite. As a mineral-derived chloride, there is, for example, the anhydride of that carnallite (e.g., KMgCl3).

[0041] Mg (and further MgCl2) contained in the chloride acts catalytically in the Mg removal treatment from the Al alloy melt (especially in its initial stage) as described above. Therefore, Mg in the chloride only needs to be sufficient to allow the reaction formula (2a) to proceed to the right side. Thus, the remover preferably contains MgCl2 in an amount of, for example, 0.2 to 60% by mass, 0.3 to 55% by mass, 0.4 to 40% by mass, 0.5 to 30% by mass, 2 to 20% by mass, and further 7 to 15% by mass based on the whole chloride. When there is too much MgCl2, evaporation of MgCl2 and generation of chlorine gas (Cl2) are likely to occur during the Mg removal treatment.

[0042] During the Mg removal treatment, as shown in the reaction formula (2a), MgCl2 becomes MgO and is consumed. On the other hand, as shown in the reaction formula (2b), Mg taken in from the Al alloy melt becomes MgCl2. While repeating such consumption and replenishment of MgCl2, Mg in the Al alloy melt is removed as MgO according to the amount of CuO contained in the remover.

[0043] 《Copper Oxide》 Copper oxide is mainly CuO, but may contain Cu2O. Also, at least a part of CuO may change to Cu2O during the Mg removal treatment.

[0044] 《Mixing Ratio》 In order to efficiently remove Mg from the Al alloy melt, both the chloride and copper oxide are required. The mixing ratio (chloride / copper oxide), which is the mass ratio of the chloride to the copper oxide, is preferably, for example, 0.15 or more. Further, the mixing ratio may be, for example, 0.2 to 9, 0.25 to 7, 0.5 to 5, and further 0.7 to 2.5.

[0045] Mg Removing Agent The removing agent may be a mixture of chloride and copper oxide or a melt. The removing agent can take various forms, such as lumps, granules (crushed powder, granular, powdery, etc.). When the removing agent is granular, its particle size (also referred to as "grain size") is, for example, about 0.1 - 8 mm, 0.5 - 5 mm, and even more preferably 1 - 3 mm in maximum length (diameter). The particle size and particle size distribution of the removing agent are adjusted in consideration of its dispersibility and solubility in the Al alloy melt.

[0046] The Mg removing agent is, for example, granular flux introduced into the Al alloy melt or its raw material lump (solid). In addition, the Mg removing agent may be used to form a molten salt layer with a predetermined thickness on the surface of the Al alloy melt.

Examples

[0047] Various fluxes were introduced into the Al alloy melt containing Mg, and the amount of Mg removed by each flux (the degree of reduction in Mg concentration) was evaluated. The present invention will be described in more detail based on such specific examples.

[0048] 《Outline of Mg Removal Treatment》 (1) Al Alloy Melt As the Al alloy melt containing Mg to be removed (also referred to as "Al - Mg melt" / raw material melt), any one of melts 1 - 4 shown in Table 1 was used. Each melt was prepared by dissolving alloy raw materials weighed according to the desired composition in a graphite crucible. Unless otherwise specified, all the melts used in the experiment were at 710 °C (±20 °C) and 1000 g.

[0049] (2) Chloride Unless otherwise specified, any one of chlorides 1 - 5 shown in Table 2 was used as the chloride constituting the flux. As their base salts, a composite salt of NaCl and KCl was used. Unless otherwise specified, the chlorides were mixed salts or molten salts.

[0050] The mixed salt was prepared by directly mixing the powdered raw salts (NaCl, KCl, MgCl₂) weighed to the desired composition. Commercial reagents were used as the raw salts. This also applies to the copper oxide described later.

[0051] The molten salt was prepared as follows. First, the raw salts serving as the base salts (NaCl and KCl) were placed in an alumina crucible and heated to 730 °C (±20 °C) to be melted. MgCl₂ was added to the molten base salt, and the molten salt in which the whole had dissolved was poured into a mold (φ40×20) and solidified. The obtained solid salt was pulverized in an alumina mortar to obtain a granular form with a particle size (maximum length) of 5 mm or less. All treatments were carried out in an air atmosphere.

[0052] (3) Flux Each chloride and powdered copper oxide (CuO) were weighed to prepare a flux having the blending ratio shown in Table 3. The blending ratio is the mass ratio of the chloride to the copper oxide. Table 3 also shows the mass ratio of the chloride to the whole flux (chloride + copper oxide). Unless otherwise specified, the blending ratio of the flux was any one of those shown in Table 3.

[0053] (4) Mg removal treatment The granular (including powdered) flux (chloride and copper oxide) was wrapped in commercially available aluminum foil (thickness: 11 μm) and introduced into the molten Al alloy in a crucible. The molten metal into which the flux was introduced was stirred for 1 minute with an alumina protection tube and then held (left standing) for 10 minutes or 30 minutes. The molten metal during the treatment was held at a constant temperature by an electric furnace.

[0054] (5) Analysis The molten Al alloy collected from near the approximate center of the crucible after a predetermined holding time was poured into a mold (stainless steel analysis type) and naturally solidified in the air to obtain an analysis sample (Al alloy).

[0055] The chemical components (Mg concentration, Cu concentration) of the Al alloy were analyzed with a fluorescence X-ray analyzer (XRF: ZSX Primus II manufactured by Rigaku Corporation). Each component composition (concentration) shown in this example is the mass ratio with respect to the whole Al alloy.

[0056] Example 1 The influence of the mixing ratio of the flux on the Mg concentration in the Al alloy melt was evaluated by the following experiment.

[0057] (1) Treatment Each flux with a different mixing ratio (Table 3) was added to the Al alloy melt (melt 1 in Table 1), and Mg removal treatment was carried out according to the procedure shown in Fig. 3A. The mixing of the flux was carried out by adjusting the mass of the melted chloride 4 (Table 2) with respect to CuO: 5 g (constant). For example, for the flux with a mixing ratio of 1, 5 g of chloride 4 (KCl - 41.8% NaCl - 5% MgCl2) was mixed with respect to 5 g of CuO.

[0058] (2) Evaluation The relationship between the mixing ratio of the flux and the Mg concentration in the Al alloy after treatment is summarized in Fig. 3B.

[0059] As is clear from Fig. 3B, it was found that by the coexistence of copper oxide and the chloride containing Mg, Mg can be efficiently reduced from the Al alloy melt even when the holding time is about 10 minutes. In particular, when the mixing ratio thereof becomes 0.15 or more, it was found that the Mg concentration is rapidly reduced. Also, when the mixing ratio becomes 0.5 or more, further 1 or more, the Mg concentration becomes substantially the minimum value, and it was also found that even if the mixing ratio increases more than that, that state is maintained (that is, it becomes a saturated state).

[0060] In addition, when the mixing ratio of the above-mentioned flux was 9, the chloride formed a molten salt layer on the surface of the melt (molten metal surface). Considering the Mg removal processability (workability) by the flux, it is preferable to set the mixing ratio to 9 or less, further 8 or less.

[0061] (3) Observation The surface of the molten metal after treatment and the slag-removed ash were observed. Observation examples (holding time: 30 minutes) when the mixing ratio of the flux was 0 or 1 are also shown in Fig. 3C. When the mixing ratio was 0, unreacted CuO was seen on the surface of the molten metal and in the ash. On the other hand, when the mixing ratio was 1, such CuO was not seen on the surface of the molten metal or in the ash. It is considered that the wettability of copper oxide with respect to the Al alloy molten metal was improved by the melted chloride (especially the base salt), and Mg was efficiently removed from the Al alloy molten metal.

[0062] Also, as can be seen from Fig. 3C, when the mixing ratio was 0, trapped metallic Al was observed on the surface of the molten metal and in the slag-removed ash. On the other hand, when the mixing ratio was 1, the surface of the molten metal and the slag-removed ash did not contain such metallic Al and were in a dry state.

[0063] 《Example 2》 The influence of the MgCl2 concentration in the flux (chloride) on the Mg concentration of the Al alloy molten metal was evaluated by the following experiment.

[0064] (1) Treatment Fluxes composed of chlorides 1 to 5 (Table 2) with different MgCl2 concentrations and copper oxide were added to molten metal 1 (Table 1), and Mg removal treatment was carried out in the same manner as in Example 1 according to the procedure shown in Fig. 3A. In this example, the mixing ratio was 1 (CuO: 5 g, each chloride: 5 g) in all cases.

[0065] (2) Evaluation The relationship between the MgCl2 concentration in the chloride and the Mg concentration in the Al alloy after treatment is summarized in Fig. 4.

[0066] As is clear from Fig. 4, it was found that by including Mg (Mg 2+ ) in the chloride, Mg can be efficiently removed from the Al alloy molten metal even when the holding time is about 10 minutes. In particular, it became clear that even when the MgCl2 concentration in the chloride is slightly more than 0.3 mass% (for example, 0.5 to 7 mass%, further 1 to 6 mass%), the Mg concentration is rapidly reduced. This is considered to be because the above-mentioned reaction formula (1) proceeded via reaction formulas (2a) and (2b).

[0067] Example 3 The influence of the holding time after the introduction of the flux on the Mg concentration of the Al alloy melt was evaluated by the following experiment.

[0068] (1) Treatment A flux consisting of 10 g of chloride 4 (Table 2) and 10 g of copper oxide (mixing ratio: 1) was added to 1800 g of melt 2 (Table 1), and the Mg removal treatment was carried out in the same manner as in Example 1 according to the procedure shown in Fig. 3A. However, in this example, the holding time after stirring the flux introduced into the Al alloy melt was set to 10 minutes, 20 minutes, 30 minutes, or 60 minutes.

[0069] (2) Evaluation The relationship between the holding time and the Mg concentration in the Al alloy after the treatment is summarized in Fig. 5. As is clear from Fig. 5, the Mg concentration in the Al alloy melt decreased with the holding time, but it was also found that the Mg concentration in the Al alloy melt was sufficiently reduced at a holding time of about 20 minutes.

[0070] Example 4 The influence of a flux using a chloride with a changed preparation method and MgCl2 concentration on the reduction of the Mg concentration in the Al alloy melt was evaluated by the following experiment.

[0071] (1) Flux As the chloride, a mixed salt (KCl - 10% NaCl - 50% MgCl2) was prepared by only mixing the powdery raw salts (1 g of KCl, 0.5 g of NaCl, 1.5 g of MgCl2) without melting. 6 g of copper oxide (mixing ratio: 0.5) was added to 3 g of this mixed salt to obtain a powdery flux.

[0072] (2) Treatment According to the procedure shown in Fig. 6A, the flux was added to the Al alloy melt (1000 g of melt 3 in Table 1) for the Mg removal treatment. The melt temperature was 750 °C, and the holding time after stirring was 30 minutes.

[0073] (3) Evaluation The Mg concentration and Cu concentration in the Al alloy before and after the Mg removal treatment were compared and shown in Fig. 6B. As is clear from Fig. 6B, it was found that even with a flux using a mixed salt with a high MgCl2 concentration, the Mg concentration in the Al alloy melt could be sufficiently reduced.

[0074] Note that the Cu concentration in the Al alloy melt hardly changed before and after the Mg removal treatment. From this, it was also found that the Cu precipitated by the Mg removal treatment hardly mixed into the Al alloy melt and was taken into the flux residue (the removed ash).

[0075] 《Example 5》 The influence of a flux using a chloride derived from a mineral on the reduction of the Mg concentration in the Al alloy melt was evaluated by the following experiment.

[0076] (1) Flux For the preparation of the chloride, the molten dehydrated product of carnallite (Promag F manufactured by Pyrotech Japan Co., Ltd.) was used. Its composition (mass ratio) was KCl - 45.5% MgCl2. The composition analysis was performed by atomic absorption spectrometry for K, ICP emission spectrometry for Mg, and ion chromatography for Cl.

[0077] A flux obtained by adding 5 g of copper oxide (mixing ratio: 1) to 5 g of the molten dehydrated product of carnallite (simply referred to as "carnallite" as appropriate) and a flux obtained by adding 5 g of copper oxide (mixing ratio: 1) to a mixed salt (total 5 g) consisting of 0.5 g of carnallite and 4.5 g of KCl were prepared. The carnallite and the mixed salt were used in granular form without melting.

[0078] (2) Treatment According to the procedure shown in Fig. 7A, each flux (10 g) was added to the Al alloy melt (4 / 1000 g of the melt in Table 1) for Mg removal treatment. The melt temperature was 710 °C, and the holding time after stirring was 30 minutes.

[0079] (3) Evaluation The Mg concentration and Cu concentration in the Al alloy before and after the Mg removal treatment were compared and shown in Fig. 7B. As is clear from Fig. 7B, it was found that the Mg concentration in the Al alloy melt could be similarly reduced even with the flux prepared using mineral-derived chlorides.

[0080] Also, when formulating the flux, using a mixed salt of KCl and carnallite rather than using only carnallite resulted in a greater reduction in the Mg concentration. It is considered that this is because when using carnallite containing a large amount of MgCl2, evaporation of MgCl2 and generation of Cl2 occurred during the Mg removal treatment, resulting in a decrease in the chloride itself.

[0081] In any case, by using minerals in chlorides containing Mg, it is possible to achieve cost reduction of the flux by omitting the melting of the chloride, improvement of the working environment by suppressing chlorine gas generated during the Mg removal treatment, and the like.

[0082] From the above, it was confirmed that by using the Mg remover of the present invention, Mg can be efficiently removed from the Al alloy melt.

[0083]

Table 1

[0084]

Table 2

[0085]

Table 3

Claims

1. comprising a chloride and copper oxide, the chloride having at least one base metal element selected from K, Na, and Ca and Mg, and containing 0.2 to 60% by mass of MgCl₂ with respect to the whole, the mixing ratio, which is the mass ratio of the chloride to the copper oxide, being 0.15 to 9, a Mg remover used for removing Mg from a molten aluminum alloy.

2. The chloride contains 0.5 to 30% by mass of MgCl ２ with respect to the whole, and is the Mg remover according to claim 1.

3. The Mg remover according to Claim 1 or 2, wherein the chloride contains 40 to 99.8% by mass of KCl with respect to the whole.

4. The Mg remover according to any one of Claims 1 to 3, wherein the mixing ratio is 0.5 to 8.

5. The Mg remover according to any one of Claims 1 to 4, wherein the chloride is a melting salt or a mixed salt.

6. The Mg remover according to any one of Claims 1 to 5, wherein at least a part of the chloride is a mineral containing the base metal element and Mg or a chloride derived from the mineral obtained from the mineral.

7. The Mg remover according to any one of Claims 1 to 6, which is a granular flux introduced into the molten aluminum alloy.

8. A manufacturing method for obtaining an aluminum alloy with a reduced Mg concentration by bringing the Mg remover according to any one of Claims 1 to 7 into contact with a molten aluminum alloy containing Mg.

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