JPS5931581B2 - Demagnesium treatment method for aluminum alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a secondary aluminum alloy ingot containing magnesium;
The present invention relates to a method for removing magnesium from recycled aluminum alloy materials such as scrap.

In recent years, aluminum has come to be used for buildings, various structures such as vehicles, and other industrial components, but most of it is used in the form of alloys containing magnesium in various ranges, so aluminum can be recycled from scrap. In order to obtain the next recycled ingot, it is often necessary to remove the magnesium contained therein to reduce the amount of magnesium to a level suitable for use as a general aluminum ingot.

The materials for the above-mentioned secondary recycled ingots are those with a large surface area relative to their weight, such as extruded molds, can stock, and plate materials, and those with a small surface area relative to their weight, such as ingots and engine parts. However, it is difficult to sort these materials by composition, and even if recycled ingots are sorted and melted, the composition of the materials varies, making it impossible to reliably produce recycled ingots. For this reason, after all the materials are collected in each group and the alloying elements are averaged, magnesium contained in the molten metal is removed to produce recycled aluminum alloy ingots with a small amount of magnesium.

The melting of the above-mentioned materials and the removal of magnesium are normally carried out as follows.

In other words, when melting the above-mentioned materials in a melting furnace, the material with a small surface area relative to its weight is first melted to form a seed liquid, and then the material with a large surface area relative to its weight is melted into the seed liquid. Hey,
Materials that are easily consumed by oxidation are charged and melted in a forced manner to prevent oxidation loss that often occurs when producing recycled aluminum alloy ingots.

After all of these materials are dissolved, a demagnesium aid such as sodium aluminum fluoride is pushed into the aluminum bath using a jig such as a phosphorizer to cause a demagnesium reaction and remove magnesium from the molten metal. However, the amount of magnesium is kept below the level suitable for use as a general aluminum ingot.

This conventional method of melting and demagnesizing work is not only high-temperature work but also dangerous, and because the materials and auxiliaries must be pushed into the molten metal, it is impossible to leave the furnace for long periods of time. Moreover, this demagnesium reaction took a long time and was unstable.

For example, in order to obtain a molten aluminum with a magnesium content of 0.3% or less from a molten aluminum containing about 1% magnesium using potassium aluminum fluoride as a demagnesium removal aid, a processing time of 2 to 5 hours is required. Therefore, it was not efficient.

For this reason, there are only a limited number of auxiliaries for demagnesium that can be used industrially, and these auxiliaries are expensive, which is a factor that increases the cost of secondary recycled ingots.

The present invention has been made in view of the above-mentioned unfavorable circumstances, and aims to be efficient and labor-saving, expand the range of industrially usable aids for demagnesium, and reduce oxidation loss during fermentation of materials. The present invention proposes a demagnesium treatment method that can reduce the amount of demagnesium used when melting recycled aluminum alloy materials containing magnesium. The present invention provides a novel method for demagnesizing an aluminum alloy, which is characterized by coating almost the entire surface of the material with an auxiliary agent and then melting the material.

The present invention will be explained in detail below.

Regarding the removal of magnesium contained in recycled aluminum alloy materials, the inventors aimed to learn the influence of silicon, which is a common alloying element in aluminum alloys and is used in large quantities, and which has such a strong affinity that it forms intermetallic compounds with magnesium. (This melts 7 into aluminum-silicon alloy 5 containing 1% magnesium and keeps it at 800℃, and then adds 300g of potassium aluminum fluoride and stirs to obtain 0.3% magnesium content ζ I asked for the time it would take for this to happen.

The results are shown in FIG.

In Figure 1, the vertical axis indicates the magnesium content of 1% and 0.
Time to reach 3% magnesium content, horizontal axis is 1%
Shows the silicon content of aluminum alloys containing magnesium and silicon.

According to this, for example, in the case of 1% magnesium or aluminum alloy bath water that does not contain silicon, it takes 15 minutes to reach 0.3% magnesium content, and 1% magnesium containing silicon
% magnesium, 0.3 for aluminum alloy molten metal
It took 55 minutes to reach % magnesium content, and then 1
In the case of molten magnesium and aluminum alloys containing 0% silicon, 80
It took minutes.

From these results, the inventors found that silicon in the molten aluminum alloy affects the demagnesium reaction rate, and as the silicon content increases, the demagnesium reaction rate slows down.

Therefore, the inventors used fluorides and chlorides of alkali and alkaline earth metals as auxiliaries for demagnesium, and conducted research to eliminate the influence of silicon on the demagnesium reaction described above, which the inventors discovered. I found out about the result method.

For example, 3004, which is often used in can stock,
Material (American Aluminum Association Standard) (Si<0.30
%, Fe(0,7%, Cu(0,25%9M
n1.0~Mg0.8~1.3%, Zn (0.25%)
When a material containing a large amount of magnesium and a small amount of silicon is coated with the above-mentioned demagnesium auxiliary agent and then dissolved, the phase that first elutes from this material is a phase with a high concentration of magnesium, and Since the influence of silicon was small, this phase and the auxiliary agent covering the material reacted effectively and quickly, and the magnesium in the material could be removed in a short time.

Furthermore, when a mixture of materials having various alloy compositions is coated with the above-mentioned demagnesium auxiliary agent and then melted, the conventional method is to melt the entire amount of the materials and then demagnesize them. Unlike in the case of the method, in the process of dissolving each material, the Iwata phase reacts with the auxiliary agent covering the material, so even if a material with a high silicon content is mixed in, The silicon in this material did not affect the demagnesium reaction of other magnesium-containing materials, and the demagnesium reaction was able to proceed effectively in each magnesium-containing material.

This also reduces the loss of aluminum due to oxidation, since the auxiliary agent prevents contact between the material and the atmosphere, especially when the auxiliary agent is melted at the melting temperature of the material. Since contact with the aluminum is effectively prevented, the loss of aluminum due to oxidation can be reduced even better than in the case described above.

The present invention has been made in view of the above-mentioned findings, namely, almost the entire surface of recycled aluminum alloy material is treated with fluorides and chlorides of alkali and alkaline earth metals.
An auxiliary agent for demagnesizing consisting of one or more types, which is applied using a jig such as a shovel, or by immersing the material in a fluidized bed in which the above auxiliary agent is fluidized, or by melting the above auxiliary agent. This is a demagnesium treatment method for an aluminum alloy, in which magnesium is removed by coating the material by immersion or other means, and then melting the material in a melting furnace or over a seed bath in the melting furnace.

According to the method of the present invention, the removal efficiency of magnesium is poor due to the influence of silicon in the molten metal, and it takes a long time to remove magnesium. Therefore, it is now possible to effectively use a substance that could not be used industrially as an auxiliary agent for demagnesium. The auxiliary agent on the surface prevents contact between air and the material, so there is less oxidation loss of aluminum.
Recycled aluminum alloy can be obtained with good yield.

In addition, since the method of the present invention only requires covering the material with an auxiliary agent and then melting it, many workers are not required to spend long hours in front of the furnace for melting and demagnesium treatment, unlike in the conventional method. This is an extremely labor-saving method.

Next, specific examples will be described.

Table 1: JIS for secondary recycled ingot materials used in Koko Examples
Indicates standard composition.

Example 1 Engine parts 10.51 and low quality ingots 10.51 were melted in a melting furnace to obtain a seed molten metal, and this seed molten metal was maintained at 800°C and analyzed for its composition. ,
29%, Cu2.86FeO, 78%.

Next, use a shovel to uniformly apply 7 to 90% sodium aluminum fluoride to a mixed material of 4.3 tons of building material scraps and 4.51 tons of can scraps, and then pour this material onto the molten metal in three portions using a forklift. It took 100 minutes to melt the building material scraps and can stock scraps.

After the melting was completed, floating slag on the surface was removed, the composition of the bath water was immediately analyzed, and then casting was performed.

Demagnesium rate Cox - (amount of magnesium in molten metal after demagnesium treatment ÷ amount of magnesium in molten material)
) X1001 was 311% 30 minutes after treatment, and aluminum oxidation loss C (1-(total amount of product + amount of remaining metal) ÷ total amount of dissolved material) X100I was 5.1%.

These values are shown in Table 2 (Invention Example 1). On the other hand, for comparison, demagnesium treatment was performed using a conventional method.

That is, a low-grade lump (lit) of the engine member 105 is melted in a melting furnace to make a seed hot water, and then 4 tons of can stock scraps are added to the seed hot water.
Building material layer 4.51 was melted by pushing it in using a jig.

It took 105 minutes to dissolve the can stock scraps and building material scraps.

After completion of fermentation, it was kept at 800°C and its composition was analyzed, and it was found to be Si 5.22%, Mg 0.45%, Cu2.
18%, Fe 2 O, 75%.

Next, 90% sodium aluminum fluoride and 7 were added twice each from three locations using a phosphorizer to perform a demagnesium treatment.

This work took 20 minutes.

Subsequently, the floating slag on the surface of the bath was removed and the composition was analyzed, and the composition was analyzed again 30 minutes and 1 hour later, and then casting was performed.

The demagnesium rate was 13.3% at 1 hour after treatment, and the oxidation loss of aluminum was 7.1%.

These values are shown in Table 2 (Comparative Example 1). This results in
When sodium aluminum fluoride is used as an auxiliary agent for demagnesium in the method of the present invention, the demagnesium rate is 20% higher 30 minutes after treatment than when the same auxiliary agent is used in the conventional method. Retention also improved by 2%.

It was confirmed that sodium aluminum fluoride can be sufficiently used as an auxiliary agent for demagnesizing by employing the method of the present invention.

Example 2 A low-grade ingot 10.51 and an engine member 1181 were melted in a melting furnace and held at 800°C, and the composition was analyzed. Si 5.40%, Mg 0.29%, Cu 2.7
%, Fe 0.75%.

Next, 90 kg of an auxiliary agent made of potassium aluminum fluoride mixed with 20% aluminum fluoride was uniformly applied to the mixed material of 4.1 tons of building material layer and 3.45 tons of can scrap, and then this material was mixed with the above-mentioned method. It was poured into the bath water in three parts using a forklift.

It took 95 minutes to dissolve the building material waste and can material waste.

After the melting was completed, floating slag on the surface was removed, the composition of Mitoyu was analyzed, and then casting was performed.

The demagnesium rate was 60.4% 30 minutes after treatment, and the oxidation loss of aluminum was 25%.

These values are shown in Table 2 (Invention Example 2).

On the other hand, demagnesium treatment was carried out using a conventional method for comparison.

That is, engine parts 1O1O1 low-grade lumps 11. Ot
was melted in a melting furnace, and then 3.7 tons of building material layer and 4.2 tons of can material scrap were melted.
t was dissolved by pushing it into bath water using a jig.

It took 95 minutes to dissolve the building material scraps and can stock scraps.

After the melting was completed, the surface was held at 800°C and the composition of the molten metal was analyzed. Si 5.24%, MgO, 44%
%, Cu 2.31%, and Fe 0.78%.

Next, add 20% aluminum fluoride to potassium aluminum fluoride.
Demagnesium treatment was carried out by adding 9 to the auxiliary agent 90, which was a mixture of 90% and 90%, twice each from 3 locations using a phosphorizer.

This work (this took 20 minutes).

Next, the composition was analyzed after removing floating slag on the surface of the hot water, and again after 30 minutes and 1 hour.
It was then cast.

The demagnesium rate was 36.4% one hour after treatment, and the oxidation loss of aluminum was 5.0%.

These values are shown in Table 2 (Comparative Example 2).

As a result, when a mixture of aluminum potassium fluoride and 20% aluminum fluoride is used as a demagnesium auxiliary agent in the method of the present invention, the demagnesium removal rate is lower than when the same auxiliary agent is used in the conventional method. After 30 minutes, it improved by 28.6% and the aluminum yield was also 2.5.
%Got well.

It was confirmed that the above-mentioned auxiliary agent can be used as an even better demagnesium auxiliary agent according to the present invention.

Example 3 Engine component 10.51 and low-grade ingot LIT were melted in a melting furnace and held at 800°C, and the composition was analyzed. Si 6.28%, Mg 0.28%, Cu
It was 2.76% F e O, 87%.

Next, 90 kg of an auxiliary agent consisting of 50% sodium chloride and 50% potassium chloride was evenly applied with a shovel to the mixed material of 3.5 tons of building material layer and 4.1 tons of can scrap, and then this material was The mixture was poured into the above-mentioned hot water in three batches using a forklift.

It took 95 minutes to dissolve the building material waste and can material waste.

After the melting was completed, floating slag on the surface was removed, the composition of the molten metal was analyzed, and then casting was performed.

The demagnesium removal rate was 22.2% 30 minutes after treatment, and the oxidation loss of aluminum was 3.4%.

These values are shown in Table 2 (Invention Example 3).

On the other hand, demagnesium treatment was carried out using a conventional method for comparison.

That is, engine member 11. The O1 low-grade lump iot was melted in a melting furnace, and then 4.1 tons of building material scraps and 3.9 tons of can scraps were pushed into the core bath using a jig and melted.

It took 90 minutes to dissolve the building material scraps and can stock scraps.

After the melting was completed, the molten metal was held at 800°C, and the molten metal composition was analyzed. Si 5.39%, Mg 0.41
%, Cu 2.18%, and Fe 2 O, 69%.

Next, 7 was added to auxiliary agent 90, which was a mixture of 50% sodium chloride and potassium chloride, twice from three locations using a phosphorizer to perform demagnesium treatment.

This work took 20 minutes.

Next, the floating slag on the surface of the molten metal was removed, the composition was analyzed, and the composition was analyzed again 30 minutes and 1 hour later.
It was then cast.

The demagnesium rate was 9.8% one hour after treatment, and the oxidation loss of aluminum was 4.4%.

These values are shown in Table 2 (Comparative Example 2).

As a result, when a mixture of 50 parts sodium chloride and 50 parts potassium chloride is used as a demagnesium auxiliary agent in the method of the present invention, the demagnesium removal rate is lower than when the same auxiliary agent is used in the conventional method. 14 in 30 minutes.
9 points better, and the aluminum yield also improved by 1.0 points.

It was confirmed that the above-mentioned auxiliary agent can be sufficiently used as an auxiliary agent for demagnesium according to the present invention.

The material composition of the material of the present invention example, which corresponds to the material composition of the material of the present invention before treatment in the comparative example in Table 2, cannot be measured because some of the material is dissolved during the demagnesium treatment in the example of the present invention. This is calculated from the composition of the material.

Claims (1)

[Claims] 1 After coating almost the entire surface of a recycled aluminum alloy material containing magnesium with a demagnesium aid consisting of one or more fluorides and chlorides of alkali and alkaline earth metals, the material is dissolved. A method for demagnesizing an aluminum alloy, characterized by melting in a furnace or over a seed bath in a decomposition furnace.