JPS5912731B2 - Method for refining aluminum or aluminum alloy - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for refining aluminum or aluminum alloys (hereinafter they may be collectively referred to as A7), and in particular, mainly iron, chromium, molybdenum, lead, etc. contained in A7. The present invention relates to a method of purifying Al by efficiently removing metal impurities such as arsenic.

In recent years, the aluminum industry has been considering the effective use of Al scrap for resource conservation and stabilization of metal prices.

However, A7 scrap contains many metal impurities, including iron, and the refining technology has not been established, so it is only used as a raw material for some foundry alloys, and its composition is relatively regulated. It is hardly used as a raw material for alloys for wrought materials, which are difficult to manufacture.

Based on these studies, various studies have been carried out on refining methods for A7, including (1) a three-layer electrolytic refining method in which metal impurities in A7 are separated by electrolysis, and (2) a metal impurity method in which iron is separated as an intermetallic compound of A7-silicon-iron. A method has been proposed: (1) adding a high-melting-point Al-manganese alloy to molten Al, adsorbing iron to the solid phase alloy using an impurity method, and removing it as an intermetallic compound with the A7-manganese alloy. ing.

However, although method Q above yields AA of extremely high purity, the purification work is complicated and the purification cost is extremely high.
This method is not suitable for refining scrap.

In addition, in method (2), a large amount of silicon is mixed into A7 during the refining process, so its use is limited to extremely special A7-silicon alloys.

Compared to these methods, method (①) requires simpler refining work and can considerably reduce iron content, and also contains a small amount of manga/magnetic metal in Al.
This method can be said to be the most preferable from an industrial point of view, since even if impurities are mixed in, the effect of the impurities is hardly noticeable.

However, since this method attempts to adsorb and remove iron through a solid-liquid reaction, the frequency of contact between iron and the A7-manganese alloy is low and the reaction rate is extremely slow.

Therefore, the iron removal rate is considerably lower than other methods, and it has little utility as a refining method for obtaining Al, which has strict component regulations.

Under the above-mentioned circumstances, the present inventors paid particular attention to the method (2) above, and found that if the A7-manganese alloy is brought into contact with Ag in a molten state, the frequency of contact with metal impurities and the reaction rate will be increased. We thought that it would be possible to improve impurity removal efficiency, and began research to realize this idea.

As a result, the removal efficiency can be considerably improved compared to the solid-liquid contact reaction in method (1), but it is still not satisfactory.

However, as a result of further research, the Al
If an appropriate amount of magnesium is added together with manganese and the resulting molten mixture is cooled to a temperature slightly higher than its eutectic temperature, most of the metal impurities will be removed as intermetallic compounds with A[-manganese metals. I learned that it is separated by crystallization.

Moreover, in this process, not only iron but also chromium, molybdenum,
I learned that impurities such as lead and arsenic can be removed efficiently,
The present invention has finally been completed.

That is, the purification method according to the present invention refers to A containing metal impurities.
7 or AA alloy molten metal, metal manganese and/or Al-manganese alloy containing manganese in an amount equivalent to 0.5 to 6 times the amount of metal impurities contained in the molten metal, and 0.00% of the molten metal.
Magnesium metal and/or A11-Mg alloy containing 2 to 0.1 times the amount of magnesium are added and melted and mixed, and the mixed molten metal is heated to the eutectic point or 50°C below it.
Cool and hold to a high temperature range to remove metal impurities from A7
- The gist is that it is separated by crystallization as an intermetallic compound with manganese metals.

The configuration and effects of the present invention will be explained below in detail with reference to the drawings, but the following are only representative examples, and it is possible to implement the invention with appropriate changes in accordance with the spirit of the preceding and following. It is included in the scope of the technology of the present invention.

Figure 1 shows A I-manganese (Mn)-iron (Fe) system 3.
This is the original phase diagram, and in the ABCD region, (F
An intermetallic compound of eMn)A16 is produced.

Here, for the molten mixture having the composition indicated by point X, Y
After adding the A7-Mn alloy and completely melting it, cooling and holding it to a certain temperature below the liquidus temperature of this alloy and above the eutectic temperature results in the composition shown by the dots.
eMn)A, g6 intermetallic compound crystallizes, and the melt is 2
The composition changes as shown by the dots.

Therefore, by separating this crystallized product, a molten A1 alloy with a low Fe concentration can be obtained.

However, with this method, the removal of Fe is still insufficient and the amount of Mn dissolved in the A7 alloy is also quite large.

However, at the same time as adding AA-Mn alloy or
In the process of cooling the molten metal after the Mn alloy is completely melted, Al
- When Mg alloy is added, the ternary phase diagram changes to, for example, the state shown by the chain line in Figure 1, and the crystallization region of (Fe, Mn)A16 becomes A B'C'D' and moves to the lower temperature side. spread.

That is, by further coexisting an Al-Mg alloy in the molten mixture, the eutectic temperature is lowered, and (Fe, Mn
)kl! 6 can be crystallized, so 2 points can be converted into 2
It becomes possible to move up to 7 points, and by similarly separating and removing this crystallized product, the removal rate of Fe and Mn in A7 can be greatly increased.

FIG. 2 is another example showing the effect of Mg addition, and is a graph showing the negative percentages of Fe and Mn in the A7 alloy before and after the separation and removal of crystallized substances.

As is clear from this result, without the addition of Mg, the limit is to reduce the content of Fe and Mn to an amount equivalent to the H line (corresponding to the B-C line in Figure 1), but with the addition of 3% Mg. Then, if Mg is added by 6%, it will reach J kneading equivalent, if Mg is added by 10%, it will reach kneading equivalent, and if Mg is added by 10%, it will reach kneading equivalent.
% addition, the content of Fe and Mn can be reduced to the amount equivalent to the L line.

In this way, in the present invention, by adding VCMg together with Mn to the A7 molten metal containing iron as an impurity,
By increasing the amount of additive U in g, the contents of Fe and Mn can be significantly reduced.

Further, as will be clarified in the examples below, according to the present invention, Fe
It was also found that metal impurities such as chromium, molybdenum, lead, and arsenic could be significantly reduced.

Furthermore, Figure 3 shows the results of measuring the relationship between the addition rate of Mg and the eutectic temperature (melting point) for 96% Al-2% Mn-2% Fe, and Mg lowers the melting point of the Al material to be treated. It is also highly effective in

Mn used in the present invention may be used in the form of either metal Mn or A7-Mn alloy, but in order to melt it quickly when added to Al, it is necessary to add about 5 to 30% Mn. A QA l-Mn alloy containing QA l-Mn is most desirable.

Moreover, the temperature of the Al molten metal when adding Mn is most preferably 720 to 850°C, taking into account the melting rate.

The amount of Mn added at this time should be selected from a range of 0.5 to 6.0 times the amount of pure Mn relative to the amount of Fe contained in the molten Al to be treated.

However, if the amount of Mn is less than the above range, the amount of intermetallic compounds is insufficient and it is not possible to remove Fe and other metal impurities sufficiently.On the other hand, if the amount exceeds the above range, as is clear from FIG. The rate is hardly improved, and crystallization occurs (Fe.

As a result of the increase in the amount of Mn)A16, the amount of Al purified product decreases and the yield decreases, so it is not practical.

Mg may also be used in the form of metallic Mg or Al-Mg alloy, and its addition temperature is slightly lower than the temperature when adding Al-Mn alloy (AI-Mg alloy has a higher
7) The optimum temperature range is 700 to 800°C (temperature at which it easily melts in the molten metal).

Here, the amount of Mg added must be selected from a range of 0.002 to 0.1 times the total amount of molten aluminum to be treated.

However, below the above range, the effect of lowering the eutectic temperature hardly appears, making it impossible to sufficiently reduce the content of metal impurities such as Fe and Mn; on the other hand, below the above range, as shown in FIG. This is because, as is clear from the above, the removal rate of metal impurities including Fe and Mn becomes less remarkable, making it impossible to achieve the object of the present invention.

In this way, A [appropriate amount of Mn (or Al-Mn in the molten metal)]
(Fe, Mn alloy) and Mg (or Al-Mg alloy) are melted and mixed, and this is gradually cooled.
AA6 is crystallized, but if the temperature of the molten metal is above the liquidus temperature, (F e M n )A16 will not crystallize, and if it is below the eutectic temperature, Al together with (FeMn)A16 will crystallize.
Since the pure product also crystallizes, it is impossible to separate only (FeMn)A16.

Therefore, the crystallization temperature should naturally be in the range above the eutectic temperature and below the liquidus temperature. After examining various temperatures, we found that the optimum temperature range is above the eutectic temperature or 50°C higher than it, and by keeping it within this temperature range, the crystallization of (Fe, Mn) A16 can be made most efficient. It was confirmed that it can be done.

The means for separating the crystallized intermetallic compound from molten Al is not particularly limited, and any known method or any solid/liquid separation method that will be developed in the future can be applied. Typical examples include a sedimentation separation method that utilizes the fact that the specific gravity of an intermetallic compound is greater than that of molten Al, a filtration separation method using a porous material, a centrifugation method, and the like.

The present invention is roughly configured and carried out as described above, but the key point is that an appropriate amount of Mn is added to the molten Al containing metal impurities.
By adding AA-Mn and Mg and/or Al-Mg and crystallizing intermetallic compounds at a predetermined temperature, chromium, molybdenum, lead, including Fe in the molten Al can be removed. Arsenic etc. are removed extremely efficiently and high purity AA or A1 alloy is recovered and barreled, and various impure Al alloys such as A7 scrap are recovered.
It has great practical value as a refining method for A1 alloy.

Next, examples of the present invention will be shown.

Comparative example: 1.0 to 6 of Fe was added to molten Al containing Fe as an impurity.
．． 850 Al-Mn alloy containing Mn equivalent to 0 times the amount
The mixture was added and melted at 665° C., cooled and held at 665° C. for 30 minutes, and then the crystallized intermetallic compound was separated by filtration.

F in molten A7 before crystallization and after crystallization separation →
The umbrella prevalence of Mn and Mn was measured, and the results shown in Table 1 were obtained in winter.

Note that this end corresponds to ○→・ in Figure 2.

:As is clear from this result, although the Fe content can be reduced considerably, the effect is unsatisfactory, and moreover, a considerable amount of Mn is mixed.

Example 1 Melt A7 containing Fe as an impurity contains 1.35 to 1.35% of Fe.
Al-10%Mn alloy containing 5.0 times the amount of Mn is added and melted at 850°C, and the temperature is further lowered to 750°C, so that the Mg concentration becomes 3%, 6%, 10%, and 20%. Like A
1-30% Mg and total Mg were added and heated to 645°C or 63°C, respectively.
After holding at 0°C, 590'C, and 520°C for 30 minutes, the crystallized intermetallic compounds were separated by filtration.

Here, F' in molten AA before crystallization and after crystallization separation
The contents of e, Mn and Mg were measured, and the results shown in Table 2 were obtained.

This result corresponds to △→mu, ◇→◆, ☆→★ and ◎ in Figure 2.
→ Corresponds to ■.

As is clear from this result, by adding Mg, compared to the case without Mg addition (comparative example), Fe and Mn
It can be confirmed that the content of

Example 2 Molten A containing Fe and Cr as impurities [Al-1 corresponding to 1.15 to 1.22 times the amount of these impurities]
0% Mn was added at 850°C and melted, and after the temperature was further lowered to 750°C, metallic Mg was added and melted so that the Mg concentration was 6 coefficients, and held at 630°C for 30 minutes.1, then crystallized. The resulting intermetallic compounds were filtered and separated, and the content of each metal impurity in the molten Al before and after the crystallization separation was compared.

The results are shown in Table 3.

Example 3 Molten A containing Fe and Mo as impurities [A#-1 corresponding to 1.03.1.12 times the amount of these impurities]
0% Mn was added and melted at 850°C, and further heated to 750°C.
After the temperature was lowered to , metal Mg was added and melted so that the Mg concentration was 6%, and the crystallized intermetallic compound was then over-separated in the same manner as in Example 2.
The content of metal impurities was compared.

The results are shown in Table 4. Example 4 For molten Al containing Fe and PB as impurities, AlAl equivalent to 1.12 and 1.34 times the amount of these impurities
-1O1 was added at 850°C, and as in Example 3, 6% of metallic Mg was added and melted to crystallize. Al
The content of metal impurities was compared.

The results are shown in Table 5. Example 5 AA-10% Mn corresponding to 1.01 times the amount of these impurities was added to molten Al containing Fe and As as impurities at 850°C, and 6% Mn was added as in Example 3. An intermetallic compound crystallized by adding and melting a corresponding amount of metallic Mg was filtered and separated, and the content of metal impurities in molten Al before and after crystallization separation was compared.

The results are shown in Table 6. As is clear from the results in Tables 3 to 6, the present invention can be applied not only to Fe but also to Cr, Mo, Pb, As.
It is understood that it also exhibits a considerable removal effect for impurities such as.

[Brief explanation of drawings]

Figure 1 is a ternary phase diagram of the A7-Mn-Fe system and when Mg is present in it, Figure 2 is a graph illustrating the effect of Mg addition, and Figure 3 is a graph in which Mg is Al-Mn-Fe system. A graph showing the influence on the eutectic temperature (melting point) of M n
/Fe Graph showing the relationship between e removal rates, Figure 5 is Mg
2 is a graph showing the relationship between the addition rate and the Fe removal rate.

Claims (1)

[Claims] 1 In aluminum or aluminum alloy molten metal containing metal impurities, 0.5 of the metal impurities contained in the molten metal
Metal manganese and/or containing manganese equivalent to ~6 times the amount
or aluminum-manganese alloy and 0.00 of the molten metal
Metal magnesium and/or aluminum-magnesium alloy containing 2 to 0.1 times the amount of magnesium are added and melted and mixed, and the mixed molten metal is cooled to a range of 50°C higher than the eutectic temperature. and hold
A method for refining aluminum or an aluminum alloy, characterized by crystallizing and separating metal impurities as intermetallic compounds.