JPS5959846A - Method for removing and recovering magnesium from scrap - Google Patents

Abstract

PURPOSE:To remove and recover Mg from scraps by reacting the scraps with zinc chloride in a salt bath contg. NaCl and KCl as principal components to form an NaCl-KCl-MgCl2 bath. CONSTITUTION:Scraps contg. Mg such as Al scraps contg. Mg are reacted with ZnCl2 in a salt bath contg. NaCl and KCl as principal components to form an Al-Zn alloy and an NaCl-KCl-MgCl2 bath. High purity Mg can be separated and recovered from the NaCl-KCl-MgCl2 bath by electrolysis in the molten state. The manufacture of pure Al and the refining of Zn can be carried out at the same time by separating high purity Zn from the Al-Zn alloy by a vacuum distillation method.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for recovering and removing magnesium in scrap, particularly magnesium in aluminum scrap.

Rational removal of magnesium contained in scrap,
It has traditionally been considered difficult to recover. For example, aluminum scrap often contains -7gnesium,
When producing recycled secondary 1-luminium metal, it must be removed, and it can be removed by blowing chlorine gas into the melt.
It was difficult to put it into practical use due to environmental pollution problems.

On the other hand, when zinc chloride is applied to aluminum scrap containing magnesium, the result is Δ(!
M g + Z n Cj22→8A Z n +M
It is known that a substitution reaction can proceed quantitatively on C12-(1) to remove and separate magnesium. However, in this case, zinc chloride itself has strong deliquescent properties and is more expensive than chlorine, and the addition of zinc chloride increases the zinc content in aluminum (for example, 2 kg of zinc chloride per 1 scrap). When added, the zinc content increases by 0.05%, the zinc content is 0°19 (cannot be used in corrosion-resistant alloys of the following specifications), and zinc chloride is 11).
reacts quantitatively with magnesium as described above, but in reality, most of the scrap is octaβ, so the following (
2) and (3), 8e (-3/2 Z
n Ce 2→Δ7ICI13 +3/2Zn-(21
Δ1− M g + 2 / 38j! CI! 3→
MgCff2+x8N-(31 First, 86(M3 is generated, which replaces Mg and becomes M
gCj! The reaction proceeds in two steps, resulting in Δ1ce3 produced at this time and Z ri Cj! that is initially added.
The vapor pressure of No. 2 was high, and it was difficult to prevent and remove its dasu l- and fume, so it could not be put into practice.

The inventors of the present invention have conducted extensive research in view of the above problems, and have found that by reacting aluminum scrap with zinc chloride in a salt bath containing NaC(!KCl as a main component), the AlCl2 produced is Absorbed in the bath A I
Cjl! 3 N a CIl-K Cl! Tonattehi 11& Without doing anything, it reacts with M g in the scrap and M g Cj! It was discovered that Mg in scrap can be efficiently removed and recovered by producing Mg2.
This led to this invention.

Accordingly, the present invention provides scrap with a magnesium content j of Na CII -1 < 11 whose main component is CIt.
The Δβ-Zn alloy produced by reacting with zinc chloride in a bath and NaCl! K Cj! M g CIt
It is characterized by separating the two baths.

According to the present invention, the obtained Aβ-Zn alloy is separated by vacuum distillation and extracted as high-purity Zn, thereby making it possible to simultaneously produce pure aluminum and smelt zinc. On the other hand, NaC6-K CII M g C1
22 High purity Mg can be separated and recovered by molten salt electrolysis.

Next, the present invention will be explained with reference to the drawings.

Figure 1 shows the Aj2-Mg alloy (Mg9.83%, m, p6
FIG. 2 is a D′rA diagram showing the reaction situation caused by heating an excessive amount of Z n C7!2 powder at 17° C. (chip). According to equation (1), a large exothermic peak is seen around 370°C,
An endotherm is observed at 419°C due to the subsequent melting of Zn. However, ZnCe. is more than the equivalent amount in the alloy, the alloy is completely chlorinated and Zn and Zn
C(! 2 M g Ce 2-8llC7!3 forms a melt.

Therefore, ZnC62, which corresponds to 1 Mg content in the alloy,
Based on the expectation that Mg removal would occur preferentially by adding
The alloy was heated in a sealed tube at 400° C. for 100 minutes with an excess of alloy. As a result, the shape of the alloy chip after heating remained the same, but as shown in the following table a>+m, it was found that Mg in the alloy was replaced with Zn. However, the reaction occurs between the alloy chip surface and the Z n CIl 2 melt, and is not necessarily selective.

a) 400°C 100 m I n , , no
N a C4-l (C7!b) 650℃100ntIn
,, 15gNaC1-1<C12 (1: it Figure 2 is a graph showing the effect of the amount of ZnC7!2 added, which is less than Mg removal in the Aj!-Mg and ZnC7!2 (7J substitution reaction). When a salt bath is not used, the MMg ratio is only about 70% when the amount of Zn, CIl 2 added is 1 equivalent, and as the amount added increases, the Mg removal ratio also increases. 10 loss rate also increases.

FIG. 3 and Table bN shown above each show one embodiment of the present invention. That is, A1-Mg alloy and Z n C12-N a
Cj! The results are shown in which the reaction with -K C1 was performed by varying the amount of ZnC7!2 added and heating in a quartz sealed tube at 650°C for 100 minutes. As is clear from the figure, Mg in the alloy
When an equivalent amount of ZnC #2 is added, almost 100% of Mg is extracted into the salt bath to obtain an A/-Zn alloy, and the Mg content in the resulting alloy is about 0.01 wt%.
It can be seen that there are fewer 10 losses on 6s.

Mg due to Z n C (1,!) shown in this formula (1)
The substitution reaction is a type of thermite reaction, which is completed in a short time without exothermic heat. As an example, A6-Mg alloy (
Mg10%) 5 g) fi: Z n c 7!23
g (for this ritMg) and NaC1! -KC
7! (Molar ratio 1X1') Add to 15g mixture, 6
When the reaction tube is maintained at 50°C, as shown in Fig.
The Mg removal rate reaches 100% in minutes.

FIG. 5 is a graph showing the relationship between treatment temperature and Mg removal rate. The salt bath melts from 400℃, and ZnCβ2-K C
The 1-N a C (l melt and the Aff-Mg alloy start to react, and the reaction rate reaches 100% at 600°C.

At this temperature, the Al-Mg alloy and the Al-Zr+gold alloy become liquids, and the reaction proceeds quickly because it occurs between liquid and liquid.

There are almost no impurities in the Δp scrap extracted by the above de-Mg reaction, and J a C (1-K Ce -M
Since M g CA' 2 in the g G 7!2 melt is of high purity, the operation of -Jl molten salt electrolysis (20% Na
Cd, 2096KCI! , 5 Q%M g C12 bath)
As in the case of 1, high purity Mg (99.9%) can be filled.

First, the Δ12-Zn alloy is separated into Zn and 8C by vacuum distillation, but Zn can be made as pure as distilled zinc by the ISP method. In addition, 8β is Fe other than Mg and Zn contained in aluminum scrap,
Although the purity (99.8%) obtained by the Whole Yale method cannot be reached due to residues such as Si, it is sufficient to increase the purity by further electrochemical purification.
(,1-MgCl12 can be used.

As described above, the present invention, in which scrap containing magnesium is reacted with zinc chloride in a salt bath, has the following effects.

■ Conventional use of zinc chloride alone has had a problem with its hygroscopicity, but by mixing and melting zinc chloride with other salts, for example, Zn Cj! 2 Na CIt -K Cj!
By creating a salt bath and reacting it with aluminum scrap in the salt bath, hygroscopicity can be suppressed and handling becomes easier.

■ By using a salt bath, aluminum chloride, which is a reaction product, is collected in the salt bath, and aluminum chloride, which has traditionally been treated as dust or fume and caused operational troubles, is reacted with magnesium in the scrap and desorbed. This can be done with magnesium (see formulas (2) and (3)).

■ By using a salt bath, unlike when zinc chloride is applied directly to aluminum scrap (see Figure 14), there is no localized violent reaction on the scrap surface.
The reaction should be carried out slowly. Since it is a liquid-liquid reaction and sufficient contact takes place, the reaction rate is high and it completes in a short time (see Figure 4).

■ After the reaction, the salt bath is used as it is for M g Ce 2-
NaCl-KCj! With a salt bath, magnesium electrolysis can be carried out.

(2) Using the zinc chloride used in the present invention, it becomes possible to simultaneously produce aluminum by demagnesizing and manufacture zinc needles.

Currently, zinc is smelted using either the dry method or wet electrolysis method using ZnS concentrate, but as shown in No. 61 Ice 1, ZnS concentrate is directly chlorinated with oxygen and chlorine. Zn
CJz is manufactured and this 7. After implementing rtCI12 in the present invention, N a CIt −K CIM g CIt
Chlorine gas obtained by two-bath electrolysis is used as Zn5IN#Jλ
This can be achieved by using circulating stools to reduce chloride.

[Brief explanation of drawings]

Figure 1 is for explaining the present invention.〇-Mg alloy and ZnC
DT Yashi 1 showing the reaction situation with n2, Figure 2 is also A
l-Mg and 7. n Cri 2 position 1 negative reversal), 6G Koo L
7. Effect on Jurujuku magnesium. n Ce 2 attachment J
Graphs showing the effects of X1 electricity, Figures 3 to 5
Figure 1 is a graph showing an example of the present invention, and Figure 6 is a flow sheet of a zinc smelting method showing an example of application of the present invention.
Rikenni L-gyo Co., Ltd. Transfer 1 Last Iσ...Nailing glare Mg+-, you °'-4Z n
CE 2 'AiJ calltn 妓釆(650°C, lO
o#-) now +z n'f) a ZnCQ2'Jit-
Red Fig. 4 Reaction time (intermediate) Solution M9, 7 place JJL dark ~ 311 raw 650 ° C, A (2-Mg meeting i: l g, No
(J!-KCQ', 3gZnCQz: Ig J'JQMg, 1) 代し逼υ1の出i2'/ifmi and, τ2jノ1生ZnCQ2: 3g, Village: 5g
, No (4-K (4: 15g, 1004 confections (l)
(To) ZnS confirmed payment

Claims (1)

[Claims] Scrap containing magnesium is converted into NaCβ-K C
6 was reacted with zinc chloride in a salt bath mainly composed of 1, e-Zn alloy and NaC(!-1(CIM g
A method for removing and recovering magnesium in scrap, which is characterized by separating magnesium from C(12 bath).