JP2636162B2 - Iron removal method of aluminum alloy material - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION This invention, by reducing the iron content of the reproduction aluminum alloy ingots, aims to expand applications of the reproduction alloy ingots, aluminum order to further facilitate the recycling of aluminum alloy scrap material Alloy material
On the iron removal method .

[0002]

2. Description of the Related Art In the recycling of aluminum, in the case of obtaining recycled aluminum alloy ingots from raw aluminum cans, aluminum sashes, and other scraps, iron, magnesium, zinc are used unless perfect separation of dissimilar metals in the raw material scraps is performed. Is inevitable. In the case of producing a recycled aluminum alloy ingot, the iron content can be as high as 2-3% or more depending on the type of scrap. According to the conventional technology, when the content of impurities is high, a method of adding and diluting pure aluminum of new ingot or a higher purity alloy ingot, a method commonly called a blending technique has been adopted. There is no technology for removing impurities such as iron. With respect to magnesium, which is the only metal more active than aluminum, a method of removing magnesium by reacting with chlorine gas to produce magnesium chloride has been industrialized. In the laboratory, there is a method in which manganese is added to a molten aluminum-silicon-iron alloy to crystallize a compound and cause segregation by gravity, but it is not industrial because it requires a long time.

[0003]

When the content of iron in an aluminum alloy is increased, the intermetallic compound containing iron develops in a metal structure in the form of needles, so that mechanical properties such as elongation and impact value are increased. Significantly reduces toughness. Also,
It also has a bad effect on corrosion resistance. For this reason, for example, the casting alloy material of JIS standard, which is often used for castings of automobile parts and the like, is in the range of 0.2% to 1% depending on the type of the alloy. Since it is well known that the shrinkage of castings is large, ingots of 0.5% or less are usually used. Also, in the alloy material for die casting, the target product thickness is thin and quenched, so that the adverse effect is small. Rather, it is considered to be an effective element in improving the seizure resistance, and the standard is 1.3% or less. ing.

On the other hand, in the case of wrought materials, the allowable amount varies greatly depending on the material, and is 0.12% to 0.7%. For this reason, die-casting alloy materials having a large iron allowance have been manufactured from scrap so far, and about 92% of the used amount is currently covered by recycled materials. However, it is less than about 65% for alloys for die and sand casting, and only less than 6% for wrought materials. The reason why the application range is smaller than that of the alloy material for die casting is that there is no technology for industrially removing iron impurities.

[0005] In the conventional dilution method, the amount of new metal used as the diluent is large. Especially in Japan, new bullion is mostly dependent on imports due to the energy situation. Furthermore, compared to the energy required to obtain a primary aluminum alloy ingot from bauxite which is a natural resource, the energy required to obtain a recycled aluminum alloy ingot by recycling scrap is about 3% of that. It is possible. That is, enormous energy can be saved together with valuable resources by recycling. Therefore, from the viewpoint of more resource saving and energy saving, impurities must be actively removed to effectively use scrap. Therefore, the development of an industrially useful impurity removal technology is an urgent and important task.

[0006]

When iron is contained in a primary crystal, for example, in an Al-Si-Fe-based alloy, iron is reduced to about 1.5%.
%, K ₅ (Al ₁₅ Fe ₆ Si ₅ ) as a primary crystal,
Crystallize K ₆ (AL ₄ FeSi) and the like. These generally crystallize in the form of needles, and it is known that the addition of manganese to these crystals results in a massive shape. The primary crystal can be more easily segregated by the shape change of the primary crystal due to the addition of manganese.

When a centrifugal force is applied to this alloy during solidification from the molten state, primary crystals having a large specific gravity segregate to the outer peripheral side due to the action of the centrifugal force and solidify. At this time, the inner peripheral portion where the iron content becomes relatively low except for the centrifugal force is unsolidified and has fluidity because the melting point is lower than the primary crystallization temperature. This is pumped out by an electromagnetic pump or the like, or discharged from a discharge port provided in advance. In this way, the iron content is reduced by separating the high iron content portion from the low iron content portion.

[0008]

EXAMPLE Casting alloy containing 1.5% iron AC3A alloy with 1.1% manganese added was poured into a mold attached to a vertical centrifuge at a temperature of 1023K. 5
A rotation of 00 rpm was provided. The rotation was stopped before the whole of the poured molten metal was solidified, and the unsolidified molten metal on the inner peripheral side was discharged. An analysis of the segregated and solidified portion on the outer peripheral side and the inner peripheral side that was not solidified revealed that the former had an iron concentration of about 5%.
And about 0.5% in the latter case.

That is, since primary crystals containing iron and manganese have a large specific gravity and a high melting point, they are collected on the outer peripheral side by the action of centrifugal force, and iron and manganese are relatively concentrated, segregated and solidified. On the other hand, the iron and manganese contents are relatively low in the inner peripheral portion, and the primary crystal is in a molten state even after solidification, and can be discharged to the outside. At this time, it can be said that the iron removal rate is about 67%.

[0010]

As will be understood from the above detailed description.
According to the iron removal method of the present invention, the iron content is about 1.5% or less.
The iron concentration of the upper aluminum alloy material is 0.5% or less
With the same centrifugal force as the centrifugal casting method, which is a generally used industrial casting method for cylindrical castings, and in a short time , and the relative iron content collected on the inner peripheral side of
The unsolidified part with a low solidification temperature has fluidity
Very easy and easy to discharge
Alloy material in a field where aluminum can be purified by means and recycling from scrap was not applicable
Available, this by recycling is expected to be further promoted.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view schematically showing an apparatus for applying a centrifugal force to solidification. FIG. 1 (a) shows a time when molten metal is poured into a mold of a stationary apparatus , and FIG. This shows the time when the centrifugal force is applied by rotating the mold. In (c), when the rotation is stopped when the primary crystal solidifies, the unsolidified portion has fluidity on the inner peripheral side where the iron content is relatively low and the melting point is low. At the time when the is discharged.

[Explanation of symbols]

 1 Pouring port for pouring molten metal into mold 2 Mold lid 3 Mold 4 Pouring molten metal 5 Mold base 6 Discharge port 7 Rotating shaft

Claims (1)

(57) [Claims] An aluminum alloy having an iron content of about 1.5% or more.
Method to reduce the iron content of
The above aluminum alloy material is replaced with a metal having a large specific gravity including iron.
Between compound and composition which crystallized as the primary crystal, the relative aluminum alloy material, by the action of centrifugal force during the solidification from a molten state, it is segregated coagulate large primary crystals of specific gravity on the outer peripheral side, centrifuged at this point With the exception of power,
Solidification temperature with relatively low iron content collected on the inner circumference
Unsolidified part with low fluidity is discharged outside with fluidity
And extracting and extracting a portion having a low iron content .