JPH0885832A - Method for melting aluminum or aluminum alloy - Google Patents

Abstract

PURPOSE: To efficiently remove Fe, contained as impurity in Al or Al alloy and particularly in their reclaimed scrap, at a low cost and to reclaim as high cleanliness Al or Al alloy. CONSTITUTION: B and/or B-containing compound, B and/or B-containing compound and Ti and/or Ti-containing compound, or Ti-B multiple compound is added to Molten Al or Al alloy containing Fe as impurity, by which an Fe-B compound or Fe-B-Ti compound is formed together with Fe and separated and removed from the molten Al or Al alloy.

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 or Al alloy, and more particularly to a method for efficiently removing Fe contained as an impurity in Al or Al alloy.

[0002]

2. Description of the Related Art Al or Al alloys are used for various purposes because they have characteristics such as lightness, workability, and surface beauty. From the viewpoint of resource saving, scraps (scraps) are collected and reused. The method to do is also being actively promoted. However, there is a problem that a coarse eutectic compound is generated due to the mixing of the impurity element, and the strength, toughness, surface treatability, etc. are significantly deteriorated, and the impurity element must be reduced as much as possible in recovery and reuse. Focusing on Fe among the impurity elements, the following removal methods are known, but each has problems in terms of removal efficiency, processing efficiency, processing cost, and the like.

Raw material pretreatment method: recovered Al or A
This is a method of magnetically separating and removing steel parts such as nails and bolts that are mixed into the alloy scrap as a joining member. In this method, the steel parts are made of Al or Al.
It cannot be separated if it is combined with scrap alloy parts.

Segregation method: For example, Japanese Examined Patent Publication No. 61-16692
As described in Japanese Patent Publication No. 9, when the molten Al or Al alloy is solidified, the principle of solidifying from a high-purity portion is utilized, and impurity Fe is added to the portion remaining in the unsolidified state at the final stage of solidification. Although it is a method of concentrating and removing, this method has low processing efficiency and is not suitable for large-scale processing.

Electrolysis method: Japanese Patent Publication No. 62-103
As described in Japanese Patent Publication No. 15, a method of separating and removing the impurity Fe from the molten Al or Al alloy by electrolysis, but this method has a high processing cost and is not suitable for large-scale processing. Lacks practicality.

Compound method: As disclosed in Japanese Patent Publication No. 57-2134, Al in molten Al or Al alloy melt
-Mn intermetallic compound is present in a solid state, and Fe is captured by the intermetallic compound to remove it as an Al-Mn-Fe intermetallic compound, but this method has low reaction efficiency and requires a long time for treatment. In addition, since a large amount of Al-Mn intermetallic compound is required, it is not economical.

[0007]

The present invention has been made in view of the above-mentioned problems of the prior art, and the purpose thereof is Fe contained in Al or Al alloy as an impurity.
The present invention intends to provide a method capable of efficiently removing and cleaning the above with low cost.

[0008]

The melting method of Al or Al alloy according to the present invention is to add B and / or B-containing compound to an Al or Al alloy molten metal containing Fe as an impurity, To form an Fe-B-based compound, or by adding a B and / or B-containing compound and Ti and / or a Ti-containing compound,
Fe-B-Ti-based compound is formed with or, a Ti-B-based composite compound is added, and Fe- with Fe-
The gist is to form a B-Ti compound and separate and remove the produced Fe-B compound or Fe-B-Ti compound from the molten Al or Al alloy melt.

At this time, Fe-B type compound or Fe-
If an inert gas is blown into the molten Al or Al alloy in which the B-Ti compound is formed, the Fe-B in the molten metal
The floating separation of the Fe-based compound or the Fe-B-Ti-based compound is promoted, and the removal efficiency can be improved. Further, Fe-B-based compound or Fe-B in Al or molten Al alloy
Another preferable method of separating and removing the —Ti compound is a method of removing the Ti-based compound with a refractory filter.

[0010]

Function: Melted Al or Al alloy (hereinafter simply referred to as A
For Fe contained as an impurity in (1), the removal methods as described above have been proposed, but all have problems in terms of Fe removal efficiency and treatment cost, and therefore, in industrial scale. Lack of practicality. Then Fe in the molten Al alloy
Is generally stable and does not easily form a compound with other elements.

However, the inventors of the present invention investigated the reactivity of many elements and compounds with Fe in the molten Al alloy, and as a result, as described above, B and / or B-containing compounds were
Fe contained in molten Al alloy efficiently reacts with Fe
-When a solid or semi-molten composite compound composed of a B-based compound is produced, and when B and / or B-containing compound and Ti and / or Ti-containing compound are added to the molten Al alloy melt, Fe When a solid or semi-molten composite compound composed of a Fe-B-Ti-based compound is generated by efficiently reacting with each other, and when the Ti-B-based composite compound is added to the molten Al alloy, it also becomes Fe. Efficiently react with each other to form a solid or semi-molten composite compound composed of a Fe-B-Ti-based compound, and these composite compounds are separated by levitation or sedimentation due to the difference in specific gravity from the molten Al alloy. It was also found that it can be easily separated and removed from the molten Al alloy by filtration treatment or the like.

That is, according to the present invention, Fe in the molten Al alloy reacts with B or a B-containing compound to form a Fe-B type compound, and when Ti or a Ti-containing compound coexists with the B or B-containing compound. Fe reacts with these to produce Fe-
When a B-Ti-based compound is produced, and when a Ti-B-based composite compound is added, Fe reacts with these and Fe-B
-Ti-based compounds are produced, and all of these products are present as insoluble solids or semi-molten products in the molten Al alloy and can be easily removed from the molten alloy. Is.

In this case, Fe contained in the molten Al alloy
In order to efficiently remove the Fe and B, the amount of B or T in excess of the stoichiometric equivalent that can form a complex compound with Fe depending on the content of Fe.
It is necessary to add i, etc., but if they are added in too large a quantity, they will remain in the molten Al alloy and cause defect defects due to impurities, so addition of an excessive amount should be avoided.

For example, when B ₂ is added to produce Fe ₂ B, the lower limit of the amount of B added is 0.5 mol per 1 mol of Fe in the molten Al alloy, and the weight ratio is Fe: B.
= 55.85: 5.41. Therefore, 1% by weight of F
It is sufficient to add 0.1% by weight or more of B to the molten Al alloy containing e. When FeB _{2 is} to be generated and removed, the lower limit of the amount of added B is 2 mol with respect to 1 mol of Fe contained as an impurity, and the weight ratio is Fe: B = 55.85: 21.6. And therefore 1
For an Al alloy melt containing Fe by weight, B is 0.
4 wt% or more may be added.

In addition, Fe in the molten Al alloy (Fe, T
i) In the case of removing B _{2 and} B ₂ , the addition amounts of B and Ti are the lower limit values of an equimolar amount of Ti and a double molar amount of B with respect to Fe which is also contained as an impurity.

That is, B or B and Ti easily react with Fe contained in the molten Al alloy in an approximately stoichiometric equivalence ratio, but Fe is uniformly dispersed in the molten Al alloy. Therefore, in order to efficiently remove Fe by efficiently reacting it with B or Ti, the Fe content should be slightly higher than the stoichiometric equivalent,
For example, it is preferable to add about 1.2 times or more B or Ti. However, if these additive elements are added excessively with respect to the impurity Fe in the molten metal, they remain unreacted and cause contamination of the molten metal.
It may lead to deterioration of alloy performance. Therefore, it is desirable that the upper limit of the added amount is suppressed to about 3 times or less, and more preferably 2 times or less of the stoichiometric equivalent for forming the Fe-B-based or Fe-B-Ti-based compound.

In the above description, the case where B or Ti is added as a simple substance has been described, but the present invention is not limited to this, and it is possible to add it as a B-containing compound or a Ti-containing compound, and considering economical efficiency. Rather, the latter is often more advantageous. The most common are as such compounds, is a Al-B and Al-Ti alloy containing master alloy and Al, B ₂ O ₃ as another B-containing compound, B ₄ C,
BF ₃ , KBF ₄ , NaBF _4, etc., and TiO, TiO ₂ , TiCl ₄ , TiN, TiC as Ti-containing compounds
It is also possible to use etc.
It is also possible to use more than one species together. In addition, as a means for simultaneously adding B and Ti, addition of an Al-B-Ti alloy or a Ti-B-based composite compound such as TiB ₂ is also recommended as a preferable embodiment.

As described above, Fe-B system or Fe-
After the B-Ti-based composite compound is produced, by separating these composite compounds from the molten Al alloy,
Removal of the impurity Fe can be achieved. The method for removing the complex compound is not particularly limited, but as a general method, a method is used in which the complex compound is floated or settled by allowing the molten metal to stand and calm down, or a refractory porous body. Examples of the method include filtering the molten metal with a filter. Since many of the composite compounds are suspended in the molten metal, an inert gas such as nitrogen, argon, He, or neon is blown into the molten metal in the form of fine bubbles, and the composite compounds are floated as the bubbles float. A method for promoting separation such as removing the slag is also preferable, and in this case, a secondary effect that dehydrogenation also proceeds simultaneously can be obtained.

Thus, Al or Al whose Fe has been removed
The molten alloy can be regenerated as Al or Al alloy having high cleanliness by refining to remove other impurities as necessary.

[0020]

The present invention will be described in more detail with reference to the following examples, but the following examples do not limit the present invention.
All modifications and implementations that do not depart from the spirit of the description below are included in the technical scope of the present invention.

Example 1 JIS-110 containing 1.0% by weight of Fe as a raw material
0 Al alloy scrap was used. As the melting furnace, a reflection type melting furnace (heavy oil-fired) of 10 tons was used, which was melted in the air at 720 ° C., and the amount of B shown in Table 1 (where B is Al-
(Added as B alloy) or B compound and stirred,
Then, nitrogen gas was blown in at a flow rate of 0.6 m ³ / h for 30 minutes to float and remove the produced composite compound. This molten metal is sampled and a ceramic filter (mesh size about 2
50 μm) to remove the remaining Fe—B-based compound, and then elemental analysis was performed to determine the residual concentrations of Fe and B, and the results shown in Table 1 were obtained. The term "equivalent ratio" in the table indicates the ratio of the stoichiometric equivalent to the Fe content in the molten Al alloy. Further, (○) in the inspection items means that the Fe residual concentration is 0.05% by weight or less and the B residual concentration is 0.01% by weight or less, and (X) indicates the above. It means that the residual concentration is exceeded.

[0022]

[Table 1]

Example 2 JIS-500 containing Fe: 2.5 wt% as a raw material
Same as Example 1 except that 0 alloy scrap was used and argon gas was blown at a flow rate of 0.6 m ³ / h for 30 minutes after addition of B or B compound to promote floating separation of the produced composite compound. Fe removal treatment was performed to obtain the results shown in Table 2.

[0024]

[Table 2]

Example 3 As a raw material, AC4C-based alloy scrap containing 0.8% by weight of Fe was used, and after adding B or B compound, nitrogen gas was blown thereinto at a flow rate of 0.6 m ³ / h for 30 minutes. Fe removal treatment was performed in the same manner as in Example 1 except that the floating separation of the composite compound was accelerated.
The results shown in are obtained.

[0026]

[Table 3]

Example 4 JIS-300 containing 1.5% by weight of Fe as a raw material
Same as Example 1 except that 4 series alloy scrap was used and nitrogen gas was blown at a flow rate of 0.6 m ³ / h for 20 minutes after adding B or B compound to promote floating separation of the produced composite compound. Then, Fe removal treatment was performed and the results shown in Table 4 were obtained.

[0028]

[Table 4]

Example 5 JIS-600 containing 1.2% by weight of Fe as a raw material
Same as Example 1 except that 0-based alloy scrap was used and nitrogen gas was blown at a flow rate of 0.6 m ³ / h for 30 minutes after adding B or B compound to promote floating separation of the produced composite compound. Then, Fe removal treatment was performed and the results shown in Table 5 were obtained.

[0030]

[Table 5]

Example 6 JIS-110 containing 1.0% by weight of Fe as a raw material
0 Al alloy scrap was used. As the melting furnace, a reflection type melting furnace (heavy oil-fired) of 10 tons was used, which was melted in the air at 720 ° C., and the amount of B or B compound and Ti or Ti compound or Ti-B system shown in Table 6 was added to this molten metal. Compound added (however, B is Al-B alloy, Ti is Al-
It was added as a Ti alloy: the same below) and stirred, and then nitrogen gas was blown for 30 minutes at a flow rate of 0.6 m ³ / h to float and remove the composite compound produced. This molten metal is sampled and a ceramic filter (mesh size about 200μ
The remaining Fe-B-Ti-based compound was removed by passing through m), and then elemental analysis was performed to determine the residual concentrations of Fe, B and Ti, and the results shown in Table 6 were obtained. In addition,
In the table, "equivalent ratio" indicates the ratio to the stoichiometric equivalent to the Fe content in the molten Al alloy.
In addition, the inspection item passed is that the residual Fe concentration is 0.
The content of B is 0.05% by weight or less and the B residual concentration is 0.01% by weight or less, and "fail" means that the residual concentration exceeds the above-mentioned residual concentration.

[0032]

[Table 6]

Example 7 JIS-500 containing 2.5% by weight of Fe as a raw material
By using 0 alloy scrap and adding B or B compound and Ti or Ti compound, or Ti-B compound, and blowing argon gas for 30 minutes at a flow rate of 0.6 m ³ / h, the composite compound produced is floated and separated. Fe removal treatment was performed in the same manner as in Example 6 except that the above was promoted, and the results shown in Table 7 were obtained.

[0034]

[Table 7]

Example 8 As a raw material, AC4C alloy scrap containing 0.8% by weight of Fe was used, and B or B compound and Ti or T were used.
After adding the i compound or the Ti-B compound, blowing nitrogen gas at a flow rate of 0.6 m ³ / h for 30 minutes to promote floating separation of the produced composite compound, and in the same manner as in Example 6 above. Fe removal treatment was performed, and Table 8
The results shown in are obtained.

[0036]

[Table 8]

Example 9 JIS-300 containing 1.5% by weight of Fe as a raw material
Using 4 series alloy scrap, B or B compound and Ti
Alternatively, in the same manner as in Example 6 except that the Ti compound or the Ti—B-based compound was added and then nitrogen gas was blown therein at a flow rate of 0.6 m ³ / h for 20 minutes to promote the floating separation of the produced composite compound. Fe removal treatment,
The results shown in Table 9 were obtained.

[0038]

[Table 9]

Example 10 JIS-600 containing 1.2% by weight of Fe as a raw material
Using 0 series alloy scrap, B or B compound and Ti
Alternatively, in the same manner as in Example 6 except that the Ti compound or the Ti-B-based compound was added and nitrogen gas was blown therein at a flow rate of 0.6 m ³ / h for 30 minutes to promote the floating separation of the produced composite compound. Fe removal treatment,
The results shown in Table 10 were obtained.

[0040]

[Table 10]

As is clear from the above Examples 1 to 10, according to the present invention, Al containing Fe as an impurity is used.
Or B or B compound, B or B in molten Al alloy
It can be seen that by adding an appropriate amount of the compound and Ti or a Ti compound, or a Ti-B-based compound, Fe can be efficiently removed by a simple treatment without substantially increasing the mixing amount of B and Ti in the molten metal. .

FIG. 1 is a graph showing the relationship between the stoichiometric equivalent ratio of added B to Fe in the molten Al alloy and the amount of Fe-B based compound produced. From this graph, the amount of added B is shown. It can be seen that it is necessary to add about 1.2 times the stoichiometric equivalent ratio to the impurity Fe. FIG. 2 also shows the relationship between the amount of added B and the amount of B remaining in the molten metal. In order to prevent defects due to the remaining excess B (defects derived from B of the cast product), the addition B It is understood that the amount should be suppressed to about 3 times or less in stoichiometric equivalence ratio with respect to Fe.

FIG. 3 is a graph showing the relationship between the stoichiometric equivalent ratio of B and Ti to Fe in the molten Al alloy and the amount of Fe-B and Fe-B-Ti compounds produced. From this graph, it can be seen that B and Ti should be added to Fe in a stoichiometric equivalent ratio of about 1.2 times. FIG. 4 also shows the relationship between the amounts of added B and Ti and the residual amounts of B and Ti in the molten metal. Defects due to the residual excess amounts of B and Ti (defects in cast products).
It can be understood that the amount of added B and Ti can be suppressed to about 2.5 times or less in stoichiometric equivalence ratio with respect to Fe in order to prevent the above.

After the above Fe removal treatment, it is general to carry out a normal refining treatment using KCl-based flux or the like to remove other impurities, and a degassing treatment. It can be regenerated as high Al or Al alloy. Also, B or a B compound,
B or B compound and Ti or Ti compound, or T
The Fe-B-based or Fe-B-Ti-based composite compound formed by the addition of the i-B-based compound can be removed before the refining as described above, and in some cases, the refining can be performed while leaving the composite compound. Alternatively, it is also possible to perform degassing treatment and finally remove it by filtration with a filter.

[0045]

The present invention is constituted as described above, and A
1 or Al alloy, particularly Fe contained as an impurity in the recovered scrap, can be efficiently removed at low cost, and it can be regenerated as Al or Al alloy having high cleanliness.

[Brief description of drawings]

FIG. 1 shows addition B to Fe in molten Al alloy.
3 is a graph showing the relationship between the stoichiometric equivalence ratio and the amount of Fe-B-based compound produced.

FIG. 2 is a graph showing the relationship between the amount of B added to the molten Al alloy and the amount of B remaining in the Fe-removed molten metal.

FIG. 3 shows B and T for Fe in molten Al alloy.
5 is a graph showing the relationship between the stoichiometric equivalent ratio of i and the production amount of a Fe—B—Ti compound.

FIG. 4 is a graph showing the relationship between the amounts of B and Ti added to the molten Al alloy and the amounts of B and Ti remaining in the Fe-removed molten metal.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Kenji Ohsumi Kenji Osumi 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Kobe Steel Co., Ltd. Kobe Research Institute (72) Inventor Takashi Nakamura Minami-ku, Fukuoka-shi, Fukuoka 2-6-11 Oike

Claims (5)

[Claims] 1. Al or Al containing Fe as an impurity
A method for melting Al or an Al alloy, comprising the step of adding B and / or a B-containing compound to the molten alloy to form an Fe-B-based compound with Fe and separating the compound. 2. Al or Al containing Fe as an impurity
In the molten alloy, B and / or B-containing compound and Ti and / or Ti-containing compound were added, and Fe was added.
And a step of forming an Fe-B-Ti based compound between them and separating the Fe-B-Ti-based compound from each other. 3. Al or Al containing Fe as an impurity
A method for melting Al or an Al alloy, which comprises a step of adding a Ti-B-based composite compound to a molten alloy to form an Fe-B-Ti-based compound with Fe and separating the compound. . 4. An Fe-B compound or Fe-B-Ti
An inert gas is blown into the molten Al or Al alloy in which the system compound is formed to promote floating separation of the Fe-B compound or Fe-B-Ti compound in the melt.
The dissolution method according to any one of 3 to 3. 5. The melting method according to claim 1, wherein the Fe—B-based compound or the Fe—B—Ti-based compound in the molten Al or Al alloy melt is removed by a refractory filter.