JPH07207374A - Method for melting scrap of product made of al alloy - Google Patents

Abstract

PURPOSE:To realize the recycling of scrap of a product as the recycled Al alloy without defective impurities by efficiently removing Pb and Fe which are the main impurities contained therein in the molten condition with the scrap of coated products made of Al alloy for automobile as the raw material to be recycled. CONSTITUTION:Scrap of coated products made of Al alloy is used as at least a part of the raw materials, and after the scrap is melted, at least one kind to be selected from the group consisting of the compound oxide containing Si, SiO2, Ca, Ba, the compound containing Ca and the compound containing Ba is added into the molten metal to remove Pb in the molten metal as the compound containing Pb. At least one kind to be selected from the group consisting of Ta, Ta compound, Ti, Ca, Ba, Cl, Ti oxide, Ca oxide, Ba oxide, and the compound containing Cl is added into the molten metal to remove Fe in the molten metal as the compound containing Fe. These processes are executed in an arbitrary order to remove Pb and Fe.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for melting Al alloy product scraps, and in particular, it efficiently removes Pb and Fe which are main impurities contained in coated Al alloy product scraps for automobiles.
The present invention relates to a melting method devised so that it can be recycled as an alloy raw material and effectively used.

[0002]

2. Description of the Related Art Since aluminum is lightweight, has good workability, has good corrosion resistance, and has an excellent aesthetic appearance, its use amount has rapidly increased as a material for automobile parts. Of these, castings such as engines and wheels and die cast products are generally made of Al-
Si-based alloys are mainly used, and from the viewpoint of resource saving and energy saving, a route for recycling these scraps as original product raw materials is being established.

On the other hand, recently, mainly for the purpose of reducing the weight of a vehicle body, demand for Al alloy extruded materials and plate materials for component materials such as bonnets, trunk lids, doors, and frames has been rapidly increasing. It is desirable to collect and recycle. However, in most of these applications, the surface is coated, and when recycling the coated aluminum alloy product scraps, recycled Al derived from PbO during coating is recycled.
Pb mixed into the alloy scrap melt has a serious adverse effect on the quality of the recycled product.

That is, Pb mixed from PbO contained in the coating has a low solubility in an Al alloy and is present as a simple substance of Pb in the melt and in the ingot, and is crystallized in the grains and grain boundaries of the ingot structure. Or it remains. Therefore, if this ingot is heated to a temperature higher than the melting point of Pb during processing, Pb will melt and cause work cracking.

It is known that Fe is mixed in a considerable amount as iron and iron alloy parts such as bolts, nuts and washers used for fixing Al alloy products, and this Fe dissolves in the molten metal. Al-Fe system, Al-Fe in the ingot
It becomes a eutectic compound such as -Mn-based or Al-Fe-Si-based and causes cracks in the processing step and color unevenness in the surface treatment. Therefore, in recycling the scrap of Al alloy products for automobiles, these impure elements must be removed as much as possible.

Regarding Pb among these impurities, JP-A-5-17856 proposes a method in which a pure Al plate material is heated and held at a predetermined temperature to diffuse and move Pb to the plate surface to remove the surface portion. However, it cannot be said to be a fundamental measure for removing impurities, and Pb can be removed by the segregation method in the molten metal, but it is inefficient and not industrial.

Although the following removal method for Fe has been proposed and put into practical use, it still has the following problems. Molten metal treatment: 1) Segregation method: This is a method for separating Fe impurities by utilizing the principle that high-purity Al solidifies first when the molten metal is cooled (for example, Japanese Patent Laid-Open No. 61-166929), but the productivity is very high. Very low. 2) Electrolysis method: A method in which impurities are left in the anode by electrolysis and high-purity Al is collected in the cathode (for example, Japanese Patent Publication No. 62-10315), but the cost is too high. 3) Compound method: a method of adding an element capable of forming a compound with Fe impurities to a molten metal and removing it as an Fe intermetallic compound (for example, Japanese Patent Publication No. 57-2134), but the molten metal is contaminated by the added element. I will end up.

As described above, each of the conventional methods for removing Pb and Fe has problems, and there is still no method capable of efficiently and inexpensively removing Ti and Fe in a molten metal containing Al alloy product scrap as a raw material. The current situation is that it has not been established.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its purpose is coating for automobiles in which a considerable amount of Pb and Fe are mixed as impure elements. It is an object of the present invention to provide a melting treatment method in which Al alloy product scraps are used as a melting raw material and these impure elements are efficiently removed so as to be regenerated as an Al alloy.

[0010]

[Means for Solving the Problems] The composition of the melting method according to the present invention, which has achieved the above-mentioned problems, uses coated aluminum alloy product scraps for automobiles as at least a part of raw materials, and after melting the scraps, (1) ) A compound oxide containing Si in the molten metal, SiO ₂ , C
adding at least one selected from the group consisting of a, Ba, Ca-containing compounds and Ba-containing compounds, and removing Pb in the melt as Pb-containing compounds (2) Ta, Ta compounds in the melt, Ti, Ca, Ba,
A step of adding at least one selected from the group consisting of Cl, Ti oxides, Ca oxides, Ba oxides, and chlorine-containing compounds and removing Fe in the melt as Fe-containing compounds, in any order. The main point is to reduce the Pb concentration in the molten metal to 80 ppm or less and the Fe concentration to 0.5% by weight or less by carrying out or simultaneously.

[0011]

First, the method of removing Pb will be described in detail. To remove the Pb component, the complex oxide containing Si as described above, SiO
₂ , a method of using at least one selected from the group consisting of Ca, Ba, a Ca-containing compound and a Ba-containing compound is adopted, and a method of using a complex oxide containing Si and / or SiO ₂ , and Ca , Ba, a Ca-containing compound, and a method using at least one of Ba-containing compounds will be described separately.

Al alloys are extremely susceptible to oxidation, and their oxidation tendency is higher than that of Pb oxides. Therefore, it is considered impossible to remove Pb as an oxide from the molten Al alloy. However, as a result of diligent study by the present inventors,
It has been found that the complex oxide of Si and Pb can be crystallized in the molten Al alloy and separated and removed without causing metal loss. This is because the Si-Pb-O-based composite oxide is Al
It is considered that this is because the free energy of formation is lower than that of Al ₂ O ₃ which is the oxide of Al. Therefore, in the present invention, Si and an oxygen source are present in a molten metal formed by melting Al alloy product scraps, The complex oxide with Pb is crystallized and removed.

In the present invention, SiO ₂ and / or Si-based complex oxide is added to the molten Al alloy to remove Pb. Si-based complex oxides that can be used include MgSiO ₃ , CaSiO ₃ , FeSiO ₃ , Mn
Examples thereof include SiO ₃ and ZnSiO ₃ . The added amount of SiO ₂ and / or Si-based composite oxide needs to be increased or decreased according to the amount of impurities Pb mixed in the molten metal.
The lower limit of the total amount of these elements is the stoichiometric equivalent amount capable of forming a Si-Pb-O-based composite oxide. This is because if the amount is less than the equivalent amount, all of the impurities Pb cannot be removed as a complex oxide. For example, by adding only SiO ₂ ,
When forming (PbO) (SiO ₂ ) ₃ , Pb: 1
Si is required to be 3 mol (stoichiometric equivalent) with respect to mol, and the weight ratio is 84.3 (SiO ₂ is 18).
0.3): 207. Therefore, it is sufficient to add 0.41% by weight or more of SiO ₂ to the molten metal containing 1% by weight of Pb. However, considering that there are few reaction fields for forming the complex oxide, it is preferable to allow 1.5 times or more the equivalent amount of the element to be present.

On the other hand, if Si is present in an excessively large amount relative to the amount of Pb in the molten metal, it will rather cause contamination of the molten metal, which may lead to deterioration of the performance of the regenerated Al alloy. Therefore, S
The upper limit of i is preferably about 3 times the stoichiometric equivalent capable of forming a composite oxide. More preferably, it is not more than twice the equivalent amount.

Thus, the impurities Pb can be removed by separating these complex oxides from the molten Al alloy in which the complex oxides of Pb and Si are crystallized. The method for removing the composite oxide is not particularly limited, but it is considered that this composite oxide is heavier than the Al alloy. Therefore, after allowing the molten metal to stand and calming it, the composite oxide is allowed to settle, and then the refractory porous filter is used. It is preferable to remove it by a method such as filtration of the molten metal. In addition, since many complex oxides are suspended in the molten metal, inert gas such as nitrogen, argon, He, and neon is blown into the molten metal in the form of fine bubbles, and the complex oxides are floated as the bubbles float. A separation method such as removing the slag by removing it can also be preferably used. In this case, dehydrogenation can be achieved at the same time.

Another effective method for removing Pb from the molten Al alloy is to add Ca, B into the molten alloy.
The method of adding and processing a, Ca compound, or Ba compound is mentioned. However, the inventors of the present invention have further studied and found that Pb easily forms an intermetallic compound with Ca and Ba, and can be separated and removed without crystal loss in the molten Al by crystallization. . Therefore, in the present invention, P
b and / or Ba as another method for removing b
It is also possible to employ a method in which is added to the molten metal.

Ca or Ba can be added as a simple metal or in the form of a compound such as silica, carbide, fluoride, boride, chloride or sulfide. The amount of addition needs to be increased or decreased depending on the amount of Pb contained in the molten Al or Al alloy, and it has been confirmed by experiments that the amount of Ca is the weight relative to Pb1 in the molten metal. The ratio is preferably 0.5 to 2, and the Ba amount is preferably 1.7 to 6.9. C
When the amount of a or Ba is insufficient, the effect of removing Pb is insufficient, and when it is too large, Ca and Ba remain as impurities in the treated molten metal and the molten metal is contaminated.

The theoretical lower limit is a stoichiometric equivalent amount capable of forming an intermetallic compound. For example, when Ca is added, two kinds of intermetallic compounds of CaPb or Ca ₂ Pb are added between Pb and CaPb. Therefore, it is difficult to determine the stoichiometric equivalent. The free energy of formation of CaPb is about −90 kJ / molPb at 660 ° C., and the free energy of formation of Ca ₂ Pb is about −170 kJ / molPb at 660 ° C. Therefore, considering that Ca ₂ Pb is more easily produced than CaPb, Ca: Pb = 2: 1 is a stoichiometric equivalent, and it is preferable that Ca is present in an amount of 2 mol or more per mol of Pb in the molten metal. Become. The weight ratio is C
a: Pb = 80: 207, which is roughly in agreement with the experimental value.

In carrying out this Pb removal method,
One or more of Ca, Ba, a Ca compound and a Ba compound can be added directly to the melting furnace, or can be added by a method of blowing together with an inert gas into a molten metal from a nozzle. If an inert gas such as nitrogen, argon, He, or neon is blown into the molten metal in the form of fine bubbles, the intermetallic compounds floating in the molten metal will float up along with the bubbles, making it easier to remove them. It also has an effect. Also, dehydrogenation can be achieved at the same time.

By separating and removing the intermetallic compound thus produced from the molten Al alloy, it is possible to obtain a regenerated Al alloy having a small content of impurities Pb. The method for removing the intermetallic compound is not particularly limited, but since the intermetallic compound is considered to be heavier than the Al alloy, after allowing the molten metal to stand still and calming in the same manner as in the above method, the intermetallic compound is allowed to settle,
A method of filtering the molten metal with a refractory porous filter may be adopted.

Next, the removal of Fe from the molten metal will be described. In the present invention, Ta is used as a means for removing Fe,
Ta compound, Ti, Ca, Ba, Cl, Ti oxide, C
A method of using at least one selected from the group consisting of a oxides, Ba oxides, and chlorine-containing compounds is adopted, but in the following description, a method using Ta or a Ta compound and Ca, Ba, Cl, The method using one or more of Ca oxide, Ba oxide and chlorine-containing compound will be described separately.

First, the method of using Ta or a Ta compound will be explained. As mentioned above, Al is extremely easy to oxidize and its oxidation tendency is larger than that of Fe oxide. Therefore, Fe may be removed as an oxide from the molten Al alloy. It is considered difficult. However, as a result of intensive studies by the present inventors, the intermetallic compound of Ta and Fe exists in the crystallization or semi-molten state in the molten Al or Al alloy without causing metal loss, and is separated and removed by filtration. Found to get. It is considered that this is because the intermetallic compound of Ta and Fe is thermodynamically stable.

Ta is a single metal or TaB,
It can be added as a Ta compound such as TaCl ₃ , TaN, Ta ₂ Si. The amount of Ta needs to be increased or decreased according to the amount of Fe contained in the molten Al alloy. The lower limit of the total addition amount of Ta and the elemental metal Ta in the Ta compound is a stoichiometric equivalent amount capable of forming an intermetallic compound. This is because if the amount is less than the equivalent, all of the impurity Fe cannot be removed as an intermetallic compound. Since the intermetallic compound of Ta and Fe is Fe-Ta, both must be equimolar, and the weight ratio is 180.9: 55.8. However, considering that there are few reaction fields for forming the intermetallic compound, it is preferable to allow 1.5 times or more of the equivalent amount of Ta to be present.

On the other hand, if Ta is present in an excessively larger amount than the amount of Fe in the molten metal, it may rather cause contamination of the molten metal, leading to deterioration in the performance of the obtained Al alloy. Therefore, T
The upper limit of the total amount of a added is preferably about 3 times the stoichiometric equivalent capable of forming an intermetallic compound. More preferably, it is not more than twice the equivalent amount. When adding as a Ta compound, the addition amount may be determined in terms of Ta element.

When Ta and / or Ta compound is added to Al or Al melt, the temperature of the melt is 1000 to 13
The temperature is preferably 00 ° C. If the temperature is lower than 1000 ° C., Ta is not melted so that an intermetallic compound with Fe is less likely to be formed, and if the temperature exceeds 1300 ° C., the molten metal oxidation becomes severe and the metal loss increases. For the same reason, Ta
After the addition, the melting temperature of a normal Al alloy is 700 to 900 ° C.
It is better to lower the temperature.

Next, one of Ti, Ca, Ba, Cl, Ti oxide, Ca oxide, Ba oxide and chlorine-containing compound is used.
Explaining the Fe removal method using seeds or more, Ca,
It was confirmed that the complex oxide of Ba, Ti or Cl and Fe was also present in the molten Al alloy in a crystallized or semi-molten state without causing metal loss, and could be easily separated and removed by filtration. That is, it is considered that the complex oxide of these elements and Fe also has lower free energy of formation than Al ₂ O ₃ which is an oxide of Al.

By the way, FeO, Fe ₃ O ₄ , Fe ₂ O
_The free energy of formation of Fe compounds such as ₃ is higher than that of Al ₂ O ₃ , while Ca ₂ Fe ₂ O
Fe composite oxides such as ₅ , FeTiO ₃ and FeCl ₂ O ₄ are lower than the free formation energy of Al ₂ O ₃ , and therefore, Ca, Ba, Ti and Cl are added to the molten Al alloy to form a mixture with Fe. By forming a complex oxide,
Fe can be removed.

In this case as well, two methods can be adopted in the same manner as the above method of forming a composite oxide with Ta to remove Fe. First, the first method is a method of adding an oxide of Ca, Ba or Ti to the molten metal. In this method, since the additive is an oxide, it is not necessary to blow air to oxidize it. Also, instead of these oxides, Ca, B
It is also possible to employ a method in which at least one of a, Ti, or Cl, or a compound other than an oxide containing at least one of these elements is added to provide an oxygen source for forming a composite oxide by blowing air. It is also possible to use both methods together. Ca, Ba and Ti are added as elemental metals, or Ca compounds such as CaSi, CaC and CaF and B
Ba compounds such as aSi, BaC, and BaF, TiCl ₄ ,
It can also be added as a Ti compound such as TiS ₂ or TiF ₃ . Cl is blown with air as Cl ₂ gas or as chlorides such as KCl, NaCl, NH ₄ Cl, T
iCl ₄ or the like may be added. It should be noted that the effects were all effective although there were some differences.

Ca, Ba, T added to the molten Al alloy
The amount of each of i and Cl elements is the impurity F mixed in the molten metal.
The total amount of abundance should be increased or decreased according to the amount of e, but the lower limit value of the total amount of these elements is preferably a stoichiometric equivalent capable of forming a complex oxide. However, if the amount is less than the equivalent amount, all of the impurity Fe cannot be removed as a complex oxide. For example, when only Ca is added to form Ca ₂ Fe ₂ O ₅ , Ca and Fe need to be equimolar, and the weight ratio is 40: 55.8. Has 0.716 Ca
It suffices to add it in an amount of not less than wt%. However, considering that there are few reaction fields for forming a complex oxide,
It is preferable to allow 1.5 times or more of the equivalent amount of the element to be present.

On the other hand, if these elements are present in an excessively larger amount than the amount of Fe in the molten metal, they will rather cause contamination of the molten metal and may lead to deterioration of the performance of the regenerated Al alloy obtained. Therefore, the upper limit of the total amount of these elements is preferably about 3 times the stoichiometric equivalent capable of forming a composite oxide. More preferably, it is not more than twice the equivalent amount.

Even when these elements are added as oxides or other compounds, it is Ca, Ba, Ti, and Cl that form the composite oxide with Fe. Should be decided. However, when only oxides are added and air is not blown, it is considered that oxygen is deprived from the atmosphere or Al ₂ O ₃ already formed in the molten metal. Since it is considered that the oxygen source is insufficient from the value, it is preferable to add the oxide in an amount of 1.5 times or more the equivalent of the metal element.
Further, the amount of air blown at the time of forming the composite oxide by blowing air is 1 to 3 times the stoichiometric equivalent in order to prevent Al ₂ O _{3 from} being formed by excess oxygen as much as possible,
It is preferably 1.5 to 2 times.

The specific addition amount of the element is a weight ratio with respect to Fe: 1, and Ca = 0.
72-2.1, Ba = 2.5-7.2, Ti = 0.86
.About.2.6 and Cl = 1.3 to 3.8.

In the case of the combined use system, an element having a low free energy for forming an oxide tends to form a complex oxide first, and a complex oxide with other elements tends not to be formed until all the elements are consumed. Therefore, in the case of the combined system, it is necessary to determine the total addition amount in consideration of this.

The composite oxide of Fe thus produced is converted into Al.
By separating from the molten alloy, the removal of the impurity Fe can be achieved. Since these complex oxides are considered to be heavier than the molten Al alloy, the complex oxides are allowed to settle by allowing the molten metal to stand still, and then removed by filtering the molten metal with a refractory porous filter. Good. Also in this case, since many of the complex oxides are suspended in the molten metal, inert gas such as nitrogen, argon, He, or neon is blown into the molten metal in the form of fine bubbles, and the complex oxide is mixed with the bubbles rising. A separation method such as floating the oxide to remove it can also be preferably adopted. In this case, dehydrogenation can be achieved at the same time.

Thus, the coated Al alloy product scraps for automobiles are melted together with other Al alloy product scraps and Al ingots as the case may be, and the molten metal is refined by a conventional method, and then the above Pb removal and Fe removal are carried out. Are sequentially carried out in an arbitrary order, or simultaneously, or by carrying out refining after the above Pb and Fe removal treatments, Pb content and F
It is possible to obtain a recycled Al alloy having a very low e content. At this time, in order to eliminate the obstacles of these impurities as a recycled Al alloy product, the Pb content in the final molten metal should be 80 pp.
m or less, preferably 50 ppm or less, more preferably 1
0 ppm or less, Fe content is 0.5 wt% or less,
Preferably 0.3% by weight or less, more preferably 0.20
It should be less than or equal to weight%. Incidentally, the dissolution treatment in carrying out the present invention may be carried out within a usual temperature range of 700 to 900 ° C.

[0036]

EXAMPLES Next, examples of the present invention will be shown, but the present invention is not limited by the following examples, and may be carried out with appropriate modifications within a range compatible with the gist of the preceding and following description. Of course, it is possible, and all of them are included in the technical scope of the present invention.

Example 1 (Removal of Pb from molten metal) Raw material: Aluminum alloy plate scraps for automobiles, mainly bonnet material, raw material pretreatment: No melting: 30 t LNG-fired reverberatory furnace, air melting, 750 ° C. Refining: KCl flux Blowing N ₂ gas (0.1% by weight of the amount of molten metal) Pb removal treatment: 1.7 times the amount of S with respect to the amount of Pb in the molten metal
Blowing iO ₂ with a lance using N ₂ gas as a carrier gas (gas flow rate: 20 Nl / min) Slag: Discharging slag to the outside of the melting furnace Degassing treatment: Union Carbide Sniff used Deinclusion treatment: Using tubular filter (18 pieces) made by Mitsui Metal Co., Ltd. Casting: Semi-continuous casting of 400 mm ^t x 1500 mm ^w slab Processing: Hot and cold rolling to 0.3 mm ^t Al alloy plate Inspection: Hot working crack The occurrence rate, cold rolled sheet strength test, and surface treatment (alumite) property results of the cold rolled sheet are shown in Table 1 together with a comparative example in which only the Pb removal treatment is omitted.
Shown in.

[0038]

[Table 1]

Example 2 (Removal of Fe from Molten Metal) Raw material: Aluminum alloy plate scraps for automobiles, bonnet material, paint removal with iron bolts for fixing Material melting: 30 t LNG-fired reverberatory furnace, air melting, 750 ° C. Refining: Cl ₂ gas, 100 Nl x 15 minutes blow-in Fe removal treatment: (1) After raising the temperature of the molten metal to 900 to 1200 ° C, Ta is added in a stoichiometric ratio of 1.5 to 2 times the amount of Fe in the molten metal. Then, keep at 75 ° C. (2) Add Ca or Ba in stoichiometric ratio to the amount of Fe in the molten metal by 1.5 to 3 times, then oxidize and
Alternatively, a complex oxide of Ba and Fe is produced. Slag-inspection: The same results as in Example 1 are shown in Table 2 together with Comparative Examples in which only Fe treatment is omitted.

[0040]

[Table 2]

Example 3 (simultaneous removal of Pb and Fe) Raw materials: Aluminum alloy plate scraps for automobiles, bonnets, trunk lids, roofs, and iron bolts for fixing doors mixed. Melting: heavy oil burning, 30 t reverberatory furnace, atmospheric melting, 750 ° C. Refining: Cl ₂ gas, blowing 100 Nl × 15 minutes Impurity element removal treatment: A: (1) Pb removal: Pb removal as in Example 1 (2 ) Fe removal: After Pb removal, (2) of Example 2 or
Fe removal in the same manner as (2) B: (1) Fe removal: Fe removal in the same manner as (1) or (2) of Example 2 (2) Pb removal: After Fe removal, same as in Example 1 Then F
e Removal C: (Fe + Pb) simultaneous removal: of Example 1 and Example 2
(1), or simultaneous execution of combination of Example 1 and (2) of Example 2 Slag-inspection: carried out in the same manner as in Example 1 The results are as shown in Table 3, and Pb and Fe in the molten metal scrap It can be seen that any of the above can be significantly reduced, and a quality that does not interfere with the recycled Al alloy can be secured.

[0042]

[Table 3]

[0043]

EFFECTS OF THE INVENTION The present invention is configured as described above, and uses the coated Al alloy product scraps for automobiles as a regenerating raw material to efficiently remove Pb and Fe, which are the main impurities contained therein, in a dissolved state. As a result, the Al alloy scrap can be regenerated as an Al alloy having high cleanliness.

 ─────────────────────────────────────────────────── ─── Continued front page (72) Inventor Kiyomasa Oga 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture Kobe Steel Research Institute, Kobe Steel Co., Ltd. (72) Inventor Motohiro Arai Takatsuka, Nishi-ku, Kobe-shi, Hyogo Prefecture No. 1-5-5 Kobe Steel Works, Ltd., Kobe Research Institute (72) Inventor Minji Masuda 14-1, Chofu Minatomachi, Shimonoseki City, Yamaguchi Prefecture Kobe Steel Co., Ltd., Chofu Factory (72) Inventor Takayuki Kitano Yamaguchi 14-1 Chofu Minatomachi, Shimonoseki City, Shizuoka Prefecture Kobe Steel Co., Ltd. Chofu Works

Claims (1)

[Claims] 1. A coated Al alloy product scrap for automobiles is used as at least a part of a raw material, and after melting this, (1) a compound oxide containing Si in the melt, SiO ₂ , C
adding at least one selected from the group consisting of a, Ba, Ca-containing compounds and Ba-containing compounds, and removing Pb in the melt as Pb-containing compounds (2) Ta, Ta compounds in the melt, Ti, Ca, Ba,
A step of adding at least one selected from the group consisting of Cl, Ti oxides, Ca oxides, Ba oxides, and chlorine-containing compounds and removing Fe in the melt as Fe-containing compounds in any order. A melting method of Al alloy product scraps, which is carried out or carried out simultaneously to reduce the Pb concentration in the molten metal to 80 ppm or less and the Fe concentration to 0.5 wt% or less.