JPH08295959A - Method for refining aluminum or aluminum alloy - Google Patents

Abstract

PURPOSE: To efficiently remove Ba contained as impurities in Al or an Al alloy by simple treatment. CONSTITUTION: The molten metal of Al or an Al alloy contg. at least Ba as impurities is treated in an oxidizing atmosphere, and the same is separated away as oxides or multiple oxides contg. Ba. Or, the molten metal of Al or an Al alloy contg. Ba as impurities is added with at least one kind selected from the group of Mo, Si, Ti and Zr as a simple substance or as an alloy or a compound with Al, and treatment is executed in an oxidizing atmosphere, by which Ba is removed away as multiple oxides.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying Al or an Al alloy, and more particularly to a method for efficiently removing Ba contained as an impurity from an Al or Al alloy molten metal.

[0002]

2. Description of the Related Art Al or Al alloys (hereinafter represented by Al alloys) are used for various purposes because they have characteristics such as light weight, workability and surface beauty. But,
The inclusion of the impurity element causes problems such as coarsening of the eutectic compound, resulting in a problem that strength, toughness, surface treatability, etc. are significantly deteriorated. Therefore, various methods have been proposed and implemented for the purpose of reducing impurity elements as much as possible. However, focusing on Ba among the impurity elements, an effective removal method has not been developed so far.

[0003]

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and its purpose is to
It is intended to provide a method capable of efficiently removing Ba contained as an impurity from a molten alloy by a simple treatment.

[0004]

Means for Solving the Problems The method of the present invention that has been able to achieve the above-mentioned object is that an Al or Al alloy molten metal containing at least Ba as an impurity is treated under an oxidizing atmosphere to perform oxidation containing Ba. Of removing as a substance or a complex oxide, or Al containing Ba as an impurity
Alternatively, at least one selected from the group consisting of Mo, Si, Ti, and Zr is added to the molten Al alloy as a simple substance, an alloy with Al, or a compound, and the mixture is treated in an oxidizing atmosphere to perform complex oxidation of Ba. The gist is that it includes the step of removing the product.

As a method for obtaining an oxidizing atmosphere in the above method, a method of melting in an air atmosphere or a method of blowing an oxygen-containing gas into the molten metal is adopted. In addition, the Ba-containing oxide or composite oxide produced by the above method can be efficiently removed by levitation separation by sedation of the molten metal, floatation separation by blowing an inert gas, or filtration alone or in combination.

[0006]

The impurities contained in the molten metal of Al or Al alloy (hereinafter represented by Al alloy again) generally form an intermetallic compound with Al.
It is considered to be difficult to separate and remove it from the molten alloy, and the same is expected for Ba. However, as a result of diligent study by the present inventors focusing on Ba contained as an impurity in the molten Al alloy,
When the molten alloy is treated in an oxidizing atmosphere, the selective oxidation of Ba occurs so that it can be separated / removed as Ba oxide. In particular, Mo, Si, Ti,
When one or more kinds of Zr are added and treated in an oxidizing atmosphere,
Since these elements form a complex oxide with Ba, and this complex oxide is produced in the molten Al alloy in a solid or semi-molten state, Ba is easily removed from the molten metal by separating and removing them. I knew what I could do.

That is, when an Al alloy melt containing Ba as an impurity is treated in an oxidizing atmosphere, insoluble Ba oxide is generated in the Al alloy melt, and Mo, Si, Ti, Zr is contained in the Al alloy melt. If one or more of the above are added and treated in an oxidizing atmosphere, BaMoO ₄ , Ba ₂ SiO
₄ , to form complex oxides such as Ba ₂ TiO ₃ and BaZrO ₃ , and since these complex oxides have lower free energy of formation than Al oxides in the melting temperature range of Al alloys, they can be easily formed from the molten metal. It was confirmed that they could be separated and removed.

Therefore, the present invention is characterized by a method of separating and removing Ba as an impurity as much as possible on the premise that the Al alloy contains Ba as an impurity. As a specific method thereof, Ba is contained. A state in which Ba oxide is generated by treating the molten Al alloy in an oxidizing atmosphere, or at least one element selected from the group consisting of Mo, Si, Ti, and Zr coexists in the molten Al alloy. By supplying oxygen to the molten metal, a complex oxide containing Ba is generated. The Al alloy is Ti or S
When it contains an element such as i, the Ti or Si can be utilized as it is, and Ba can be removed as a complex oxide with the elements containing it by simply supplying oxygen to the molten metal.

The means for supplying oxygen to the molten Al alloy is not particularly limited, and the method is such that the molten metal is vigorously agitated in the atmosphere and the air on the surface of the molten metal is engulfed inside to supply oxygen, Can be adopted, such as a method of blowing into the molten metal by mixing an appropriate amount of oxygen with an inert gas such as argon or nitrogen, but the most preferable among them is an inert gas such as argon. This is a method of mixing an appropriate amount of oxygen into the molten metal and blowing oxygen into the molten metal without excess or deficiency.
This method is preferable because Ba can be efficiently removed as a composite oxide while suppressing the oxidation loss of Al as much as possible.

The above-mentioned elements forming a complex oxide together with Ba can be added as a simple substance of each element or as an alloy with Al which is a mother alloy, and can also be added as a chloride or an oxide. . Further, when the molten Al alloy to be treated originally contains these elements, it is possible to effectively utilize the contained elements as complex oxide-forming elements. In that case, those elements are positively used. In some cases, it may not be necessary to add.

The abundances of the above elements in the molten Al alloy are such that they are together with Ba as described above, BaMoO ₄ and Ba ₂ Si.
As for forming a complex oxide such as O ₄ , Ba ₂ TiO ₃ , and BaZrO ₃ , it is at least the theoretical equivalent amount capable of forming them according to Ba contained in the Al alloy, and the Ba content is set to 1. The theoretical equivalent weight of each is Mo:
0.69, Si: 0.2, Ti: 0.17, Zr: 0.
However, these are the lower limits of the theoretical amount, and considering reaction efficiency, yield, etc., it is desirable to make them exist in a slightly excess amount than the theoretical amount, and usually with respect to the B content in the Al alloy. It is recommended to use at least 1.5 times the theoretical equivalent amount, more preferably at least twice the equivalent amount. However, if the added amount of these elements is excessively large, the added elements may rather cause impurities in the molten metal to be contaminated. Therefore, the amount should be 3 times or less, more preferably 2.5 times or less. Is desired.

These elements or their compounds may be mixed into the molten metal in any state such as powder or lump, but among them, powder is preferably used together with the oxygen-containing gas in the blowing flow. It is preferable to employ the method of loading and blowing into the molten metal because the elements can be uniformly dispersed in the molten metal in a shorter time and the reaction of forming a complex oxide with Ba can proceed in a shorter time.

Since the formation reaction of the above complex oxide proceeds without any problem under the temperature condition of 700 to 900 ° C. which is a very general melting temperature of Al alloy, the processing temperature is the same as the usual melting temperature condition. However, it is also effective to adjust the molten metal temperature after the complex oxide formation reaction so as to give a temperature condition such that the complex oxide can be separated more efficiently depending on the type of complex oxide to be formed. .

In the present invention, the impurity Ba can be removed by separating the composite oxide produced in the solid or semi-molten state as described above from the molten Al alloy. The method for removing the complex oxide is not particularly limited, but as a general method, a method of calming the molten metal to float the complex oxide, or blowing fine bubbles of an inert gas into the molten metal,
A method of adhering the composite oxide floating in the molten metal to the fine bubbles to promote floating separation, a method of filtering with a refractory filter, or the like may be performed alone or in combination as necessary. In addition, if necessary, by performing a combination of usual refining treatment after the above treatment,
It is also effective to further improve the cleanliness.

[0015]

EXAMPLES Hereinafter, the structure and operation and effect of the present invention will be described more specifically with reference to examples. However, the present invention is not limited by the following examples and does not depart from the spirit of the preceding and following examples. All modifications within the scope are included in the technical scope of the present invention.

Example 1 As a raw material, JIS containing Ba: 1.0 mass%
5052 series aluminum alloy scrap 100kg
And using a reflective melting furnace (heavy oil cooking) at 720 ° C
Dissolved in the atmosphere. The mixed gas having the composition shown in Table 1 below was blown into the molten metal at 30 liters / minute for 30 minutes to calm the molten metal to remove the floating complex oxides from the molten metal surface, and then collect the molten metal to obtain the elements. An analysis was performed to determine the residual Ba content. This molten metal was further refined by further blowing KCl-based flux together with nitrogen gas, and then a casting test was conducted to examine the presence or absence of impurity defects.

The results are shown in Table 1 together. When an oxygen-containing gas was blown into the molten Al alloy melt containing Ba,
It can be seen that Ba contained as an impurity is efficiently removed as an oxide and can be regenerated into an Al alloy having high cleanliness.

[0018]

[Table 1]

Example 2 As a raw material, JIS containing Ba: 1.0 mass%
5052 series aluminum alloy scrap 100kg
And using a reflective melting furnace (heavy oil cooking) at 720 ° C
Dissolved in the atmosphere. At this time, the elements shown in Table 2 are used alone, A
A predetermined amount was added as an alloy or compound with 1. After continuing stirring for 15 minutes in the air at the same temperature and proceeding with oxidation, the molten metal was calmed down, the complex oxide floating on the surface was removed from the molten metal surface, and then the elemental analysis of the molten metal was performed to obtain the residual Ba amount. It was This molten metal was further refined by further blowing KCl-based flux together with nitrogen gas, and then a casting test was conducted to examine the presence or absence of impurity defects.

The results are also shown in Table 2. When the molten Al alloy containing Si, Ti, Zr or Mo together with Ba is oxidized in the atmosphere, Ba contained as an impurity is efficiently removed, and Al having a high cleanliness is obtained. It turns out that the alloy can be regenerated.

[0021]

[Table 2]

[0022]

The present invention is constituted as described above, and A
It was possible to easily and efficiently remove Ba contained as an impurity in 1 or Al alloy in a molten state, and regenerate it into Al or Al alloy having high cleanliness.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Kenji Osumi 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Prefecture Kobe Steel Research Institute, Kobe Steel Co., Ltd.

Claims (3)

[Claims] 1. Al containing at least Ba as an impurity
Alternatively, a method for refining Al or Al alloy is characterized by including a step of treating the molten Al alloy in an oxidizing atmosphere and removing it as an oxide or composite oxide containing Ba. 2. Al or Al containing Ba as an impurity
At least one selected from the group consisting of Mo, Si, Ti, and Zr is added to the molten alloy as a simple substance, an alloy with Al, or a compound, and treated in an oxidizing atmosphere to form Ba as a complex oxide. A method for purifying Al or an Al alloy, which comprises a step of removing. 3. The refining method according to claim 1 or 2, wherein an oxygen-containing gas is blown into the molten metal.