JPH0881720A - Method for cleaning al or al alloy - Google Patents

Abstract

PURPOSE: To efficiently remove away V from an Al material and produce an Al material high in cleanliness by adding Si or an Si-contg. compound to the molten metal of the Al material contg. V as impurities to form a V-Si compound and separating away V. CONSTITUTION: S or an Si-contg. compound (such as SiO2 and Si3 N4 ) is added to the molten metal of Al or an Al alloy contg. V as impurities, which is brought into reaction with V as impurities to form a V-Si compound, and this is separated away. At that time, the amt. of the S or Si-contg. compound to be added is regulated to 1.5 to 2.5 times the ratio in stoichiometry in which the V-Si compound is formed to V contained in the molten metal, and an inert gas is blown into the molten metal to promote the floating separation of the V-Si compound in the molten metal, which is removed away by a fire resistant filter. Thus, V as impurities is inexpensively and efficiently removed away, by which the Al or Al alloy having excellent performance as an electrically conductive material can be obtd.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for cleaning Al or an Al alloy, and more particularly to a method for efficiently removing V, which is an impurity, from a molten Al or Al alloy and cleaning it.

[0002]

2. Description of the Related Art Al or Al alloy is widely used as a casing material, an outer plate material, etc. because of its characteristics such as light weight, workability and surface beauty, and it is cheaper than copper or the like. It has been put to practical use as a conductive material for transmission line materials. However, when an impurity element such as V is mixed in Al or an Al alloy, a coarse eutectic compound is generated,
There arises a problem that strength, toughness, workability, surface treatability, etc. are significantly impaired. Therefore, it is necessary to reduce the impurity element as much as possible. Above all, when V is mixed as an impurity, a big problem occurs that conductivity is lowered when it is used as an inexpensive transmission line material replacing copper recently. .

Under such circumstances, for example, Japanese Patent Laid-Open No. 4-56
Japanese Patent No. 744 proposes a method of adding B to an Al or Al alloy molten metal and removing V and Ti contained as impurities as borides, but this method has low reaction efficiency and is as expected. V removal efficiency is not obtained, and a part of the added B remains as impurities in the molten Al or Al alloy, which causes impurities to be damaged.

[0004]

The present invention has been made in view of the problems of the prior art as described above, and its purpose is to contain V because it is contained as an impurity in Al or Al alloy molten metal. It is intended to provide a method capable of efficiently removing Al or an Al alloy having high cleanliness.

[0005]

The structure of the cleaning method according to the present invention, which has been able to solve the above problems, is to add Si or a Si-containing compound to an Al or Al alloy molten metal containing V as an impurity. The main point is that a V-Si compound is formed by reacting with the impurity V and is separated. The amount of Si or Si-containing compound used when carrying out this method is 1.5 to 2. 1 which is a stoichiometric ratio for forming a V-Si compound with respect to V contained in the molten Al or Al alloy. A range of 5 times is preferable. In addition, an inert gas is blown into the molten Al or Al alloy in which the V-Si compound is formed, so that V- in the molten metal
V can be removed more efficiently by adopting a method of promoting the floating separation of the Si compound or removing the V-Si compound in the molten Al or Al alloy with a refractory filter.

[0006]

The function of Al or Al alloy is extremely easy to oxidize, and its oxidation tendency is larger than V. Therefore, Al or Al
It is known that it is impossible to remove V as an oxide from a molten alloy. Therefore, as a result of intensive studies made by the present inventors in view of developing an efficient method for removing V, V
Was found to easily form a compound with Si to form a crystallized product or a semi-molten product in an Al or Al alloy melt, which can be easily and efficiently separated and removed by flotation, sedimentation or filtration. The present invention has been reached.

In the following, JIS containing V as an impurity element
The cleaning method of the present invention will be specifically described by taking the case of removing V from 1100 series Al alloy scrap as an example. The present inventors have found that Fe: 0.8 wt% and V: 0.5 w
Al alloy scrap containing t% is selected as the object to be treated, and after melting this at 730 ° C., various kinds of insoluble compounds can be formed with the impurity element V in the melt. An attempt was made to add an element and separate and remove V from the molten metal as an insoluble compound. As a result, when Si is added in an appropriate amount among various elements, V contained as an impurity
It has been found that can react with Si to form an insoluble V-Si compound in the molten Al alloy and can be easily separated and removed from the molten metal. The effect of removing V by adding Si is S
Of course, when i is added as a pure product, SiO ₂ ,
It was confirmed that the same result was obtained when added as a Si-containing compound such as SiO, Si ₃ N ₄ , SiC, or SiCl ₄ .

The amount of Si or Si compound added is
It should be controlled appropriately according to the amount of V contained in the molten Al or Al alloy, and the lower limit of the added amount is V
It is a stoichiometric equivalent capable of forming a -Si compound. This is because if the amount is less than the equivalent amount, all the impurities V cannot be removed as a V-Si compound. That is, since a V-Si compound is usually produced as VSi which is a compound of one atom, the theoretical equivalent of Si to V is 1: 1 and therefore the atomic weight ratio equal to V contained in the Al or Al alloy molten metal. Si becomes the lower limit of the added amount. However, with the lower limit of Si, the reaction with V uniformly dispersed in the molten metal is difficult to proceed sufficiently in a short time, and the effect of removing V may be insufficient. It is desirable to increase the removal efficiency of V by adding an excessive amount, preferably about 1.5 to 2.5 times the theoretical equivalent amount of Si.

Incidentally, FIG. 1 is a graph showing the results of examining the relationship between the equivalent ratio of added Si to V contained in the molten Al alloy and the amount of V-Si compound produced, which is also apparent from this graph. In addition, the amount of V-Si compound produced is V
On the other hand, when Si is added in an amount of about 1.5 times the theoretical equivalent, the saturation occurs, and even if the Si addition amount is increased more than that, the production amount of the V-Si compound hardly increases. And excess Si
Is to be incorporated as an impurity in the molten Al alloy, so the addition amount of Si is 1.5 to 5. It is desirable to keep the amount below about double.

It is known that Si is mixed into Al ingot in a considerable amount as an impurity element derived from a gangue component, and Si has a less harmful effect as a disordered element as compared with V. Since the conductivity is not so adversely affected, the incorporation of a small amount of Si does not practically hinder the achievement of the object of the present invention. The specific amount of Si added is S by weight ratio to V: 1 in the molten metal.
i becomes 0.83 to 1.38.

In carrying out the present invention, Al or an Al alloy is preferably heated and melted at about 700 to 1300 ° C., and an appropriate amount of Si or a Si compound is added to and mixed with V to be contained as an impurity. It reacts with Si to form a V-Si compound. The melting temperature at this time is 13
When the temperature is higher than 00 ° C., the molten metal oxidation becomes severe and the loss of Al or Al alloy increases.

Thus, the Al formed by the V-Si compound
Alternatively, the impurities V can be removed by separating and removing the V-Si compound from the molten Al alloy, and Al or Al alloy having high cleanliness can be obtained. V-
The method for removing the Si-based compound is not particularly limited, but since this compound generally has a higher specific gravity than Al or Al alloy,
A common method is to allow the molten metal to stand and calm down, and to remove the V-Si compound by allowing it to settle at the bottom of the molten metal. Further, since a part of the compound may be suspended in the molten metal, a method of filtering the molten metal with a refractory porous filter is preferably recommended as a preferable method. At this time, an inert gas such as nitrogen, argon, He, or neon is blown into the molten metal in the form of fine bubbles, and the bubbles float and float V
A separation method such as floating the Si-based compound and removing it can also be preferably used. In this case, dehydrogenation can also be achieved at the same time. After removing the impurities in this way, if necessary, refining is performed by a known method to obtain high-purity A.
1 or Al alloys can be obtained.

[0013]

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 As a raw material, JIS-11 containing V: 0.5 wt%
00 pure Al-based scrap was used and melted in the atmosphere using a 10-ton reflective melting furnace (fuel oil burning). After melting, the amount of Si or Si compound shown in Table 1 was added, and then 0.1 wt% of KCl-based flux with respect to the amount of molten metal was blown in using nitrogen gas, and then passed through a fireproof filter having a mesh size of 5 μm. After removing the insoluble matter, a billet having a diameter of 300 mm was manufactured by the semi-continuous casting method (4 pieces were taken).
At this time, the melt after passing through the filter is sampled and I
Elemental analysis was performed by the CP method to quantify the concentration of residual V. If the residual V concentration was 200 ppm or less, it passed (○), 200
Those with ˜500 ppm were regarded as semi-acceptable (Δ), and those exceeding 500 ppm were disqualified (×).

The results are shown in Table 1, and V in the molten metal is shown.
V in Al or Al alloy by adding 1.5 times the theoretical equivalent of Si or Si compound to the amount
It can be seen that can be efficiently removed and cleaned. If the amount of Si added exceeds 2.5 times the theoretical equivalent, an excessive amount of Si will be taken into the molten metal and the Si concentration will increase, so any further addition will not serve the purpose of cleaning the molten metal.

[0016]

[Table 1]

Example 2 JIS-60 containing V: 0.2 wt% as a raw material
Al alloy scrap No. 00 was used and melted in the atmosphere using a 12 ton reflective melting furnace (fuel oil burning). After melting, the amount of Si or Si compound shown in Table 2 was added, and then 0.1 wt% of KCl-based flux with respect to the amount of molten metal was blown in using nitrogen gas, and then passed through a fireproof filter with a mesh of 10 μm. After removing the insoluble matter, a billet having a diameter of 300 mm was manufactured by the semi-continuous casting method (4 pieces were taken). At this time, the molten metal after passing through the filter was sampled and the elemental analysis by the ICP method was carried out to quantify the concentration of residual V. Those with a residual V concentration of 200 ppm or less were passed (○), those with 200 to 500 ppm were semi-passed (△). ),
Those exceeding 500 ppm were regarded as rejects (x).

The results are shown in Table 2. As in the case of Example 1, by adding 1.5 times the theoretical equivalent of Si or Si compound to the amount of V in the molten metal, Al was added. It can be seen that V in the alloy can be efficiently removed and cleaned. When the amount of Si added exceeds 2.5 times the theoretical equivalent, an excessive amount of Si is still incorporated in the molten metal and
Since the concentration increases, addition beyond that will not serve the purpose of cleaning the melt.

[0019]

[Table 2]

[0020]

The present invention is constituted as described above, and A
l or Al alloy which is mixed as an impurity in Al alloy and adversely affects conductivity etc. can be removed inexpensively and efficiently, and highly pure Al or Al alloy having excellent performance as a conductive material is manufactured. I got it.

[Brief description of drawings]

FIG. 1 Addition Si to V contained in molten Al alloy
3 is a graph showing the relationship between the stoichiometric equivalence ratio and the amount of V-Si compound produced.

Front page continued (72) Inventor Ryuhei Masuda 1-5-5 Takatsukadai, Nishi-ku, Kobe-shi, Hyogo Inside Kobe Steel Institute of Kobe Steel, Ltd. (72) Kiyomasa Oga 1-chome, Takatsuka-dai, Nishi-ku, Kobe-shi, Hyogo No. 5-5 Kobe Steel Co., Ltd., Kobe Research Institute (72) Inventor Motohiro Arai 1-5-5 Takatsukadai, Nishi-ku, Kobe City, Hyogo Prefecture Kobe Steel Co., Ltd., Kobe Research Institute

Claims (4)

[Claims] 1. A step of adding Si or a Si-containing compound into an Al or Al alloy melt containing V as an impurity and reacting with the impurity V to form a V-Si compound and separating the compound. Al characterized by
Alternatively, a method for cleaning an Al alloy. 2. V contained in molten Al or Al alloy
To a stoichiometric ratio of 1.5 to form a V-Si compound.
2. Addition of ˜2.5 times Si or Si compound.
The cleaning method described in. 3. An inert gas is blown into an Al or Al alloy molten metal in which a V-Si compound is formed to produce VS in the molten metal.
The cleaning method according to claim 1 or 2, which promotes floating separation of the i compound. 4. The refractory filter removes the V-Si compound in the Al or molten Al alloy.
The cleaning method according to any one of 3 above.