JPH0593229A - Method for purifying metal - Google Patents

Abstract

PURPOSE:To efficiently purify metal. CONSTITUTION:A nucleus forming chamber 2 and a nucleus melting chamber 3 are connected through a passage 4 furnished at the lower part of a unit furnace 1. A molten metal 7 is held in the furnace, the high-purity solid grain 9 formed in the chamber 2 is passed through the passage 4 and continuously transferred into the chamber 3 to purify the molten metal. In this case, the molten metal close to the outlet of the passage 4 in the chamber 3 is kept below the melting temp. of the solid grain 9, and the molten metal above the passage 4 is kept above the melting temp. of the solid grain 9. Since the molten metal close to the passage 4 in the chamber 3 is kept at a temp. where the solid grain 9 is not melted, the heat flow in the chamber 3 does not affect the molten metal 7 in the chamber 2 and passage 4, the solid grain 9 is transferred into the chamber 3 in good yield, and the purification efficiency is improved.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for purifying a metal by a segregation method.

[0002]

2. Description of the Related Art In recent years, with the miniaturization and refinement of electronic equipment, the metal materials used for this have been found to be conductive, flexible,
Further improvement in surface properties is required, and in response to this, the development of metal materials based on high-purity metals has been actively conducted year by year. The metal purification methods for obtaining high-purity metals are roughly classified into an electrolysis method and a segregation method, but the segregation method is superior in removing trace impurities. The segregation method is a purification method that applies a solute distribution law when a molten metal is solidified, and a zone melting method and a solidification method are known. Here, the distribution law will be described with reference to a state diagram. FIG. 3 is a phase diagram of a metal containing a solute having a partition coefficient K [K = (solute concentration of crystallized solid phase) / (initial solute concentration when the liquidus temperature is reached)] less than 1, which is an impurity element. The majority of K <1. Now, when the melt having the solute concentration C ₀ in this state diagram is cooled and the temperature reaches the liquidus temperature T ₁ , nuclei (solid phase particles) having a high concentration C ₁ are crystallized.

By the way, the above-mentioned purification method by the solidification method has been conventionally performed in a batch method and is inferior in productivity, and in order to improve this, the present inventors have succeeded in continuously producing high-purity metal. We have developed a metal purifier that can be manufactured (Japanese Patent Application No. 61-241037). This purifying device has a structure as shown in FIG. 2, and the method for purifying a solute having a distribution coefficient K of less than 1, that is, a metal melt containing impurities using this device is as follows. That is, the metal purifying device has a nucleation chamber 2 in which a nucleation device 5 for generating the solid phase particles 9 is arranged and a nucleation dissolution chamber 3 for melting the solid phase particles 9 in a lower passage. The required number of unit furnaces 1 provided with 4 and connected to each other are gutters 10 arranged above the above-mentioned nucleation chamber 3 and the next nucleation chamber 2 and connected. And the nuclei melting chamber 3 are filled with the metal melt 7 to be purified, and the solid phase particles 9 having high purity generated in the nucleation chamber 2 are gravity-transferred into the nucleation chamber 3 through the lower passage 4 and transferred. The solid phase particles 9 thus prepared are melted in the nuclear melting chamber 3 to separate the molten metal 17 in the nuclear melting chamber 3 from the molten metal 7 in the nucleation chamber 2 for purification.

[0004]

However, such a purification method has a problem that the purification efficiency of each unit furnace is low, and therefore it is necessary to install a large number of unit furnaces, and the equipment cost increases.

[0005]

In the present invention, as a result of intensive studies in view of such a situation, the reason why the purification efficiency of the unit furnace is low is that the melt temperature of the nuclear melting chamber for melting the solid phase particles is
The temperature is set higher than the temperature of the melt in the nucleation chamber that produces solid particles, and as a result, the high-temperature melt convects from the nucleation chamber toward the nucleation chamber, and this high-temperature melt flow nucleates. The solid phase particles moving from the chamber are pushed back into the nucleation chamber, and further the solid phase particles are dissolved in the nucleation chamber or the lower passage,
It was clarified that the yield of transfer of solid phase particles to the nuclear melting chamber was lowered, and further research was conducted to complete the present invention. That is, the present invention holds a molten metal in a unit furnace in which a nucleation chamber and a nucleation melting chamber are connected to each other with a passage provided in the lower portion, and high-purity solid-phase particles generated in the nucleation chamber are nucleated through a lower passage. In the metal purification method of continuously transferring to the melting chamber and melting the transferred solid phase particles in the nuclear melting chamber, the temperature of the molten metal near the outlet of the lower passage of the nuclear melting chamber is less than the melting temperature of the solid particles. The temperature is controlled, and the temperature of the molten metal above the vicinity of the outlet of the lower passage is controlled to a temperature equal to or higher than the melting temperature of the solid phase particles.

According to the method of the present invention, the temperature of the molten metal in the vicinity of the outlet of the lower passage in the nuclear melting chamber is suppressed to a low temperature below the melting temperature of the solid phase particles, and the transferred solid phase particles are dissolved above the vicinity of the outlet of the lower passage. As a result, the high-temperature molten metal in the nucleation chamber rises in the nucleation chamber or the molten metal in the lower passage to push back the solid-phase particles or melt the solid-phase particles in the nucleation chamber or the lower passage. It is designed so as to prevent it. The present invention will be specifically described below with reference to the drawings. FIG. 1 is a principal part explanatory view showing an example of a mode of a unit furnace used in the present invention. The unit furnace 1 is composed of a nucleation chamber 2 and a nucleation chamber 3, and the nucleation chamber 2 and the nucleation chamber 3 pass from the nucleation chamber 2 toward the nucleation chamber 3 via a lower passage 4 having a downward slope. It is connected. A nucleation device 5 is arranged above the nucleation chamber 2. Heating elements 6 are embedded at equal intervals in the wall portion of the nucleation chamber 2 and the wall portion above the vicinity of the outlet of the lower passage of the nucleus melting chamber 3. However, the heating element is not embedded in the wall portion near the outlet of the lower passage of the nuclear melting chamber 3. This is the molten metal near the outlet
This is to prevent the temperature of 17 from rising to an unnecessarily high temperature and the influence of the heat flow on the molten metal 7 in the nucleation chamber 2 and the lower passage 4. The heating element 16 embedded in the wall below the nuclear melting chamber 3 has a separate wiring so that a large current can be passed to rapidly dissolve the solid phase particles 9. The area where the heating element 16 is embedded is
It was called the molten metal ignition zone 8. Thus, the molten metal in the nuclear melting chamber 3
17 indicates the direction of the heat flow, as indicated by the arrow
Flows only in the upper part of the above, and does not affect the molten metal 7 in the nucleation chamber 2 or the lower passage 4.

Next, a method for purifying an Al melt containing a solute having a distribution coefficient K of less than 1 as an impurity using this apparatus will be specifically described with reference to FIG. The nucleation chamber 2 and the nucleation melting chamber 3 of the unit furnace 1 are filled with the molten metal 7 to be purified, and then the nucleation apparatus 5 of the nucleation chamber 2 is operated to bring the molten metal temperature to the liquidus temperature. Lower and hold at that temperature. High-purity solid phase particles 9 are generated on the surface of the nucleation apparatus 5 in contact with the molten metal 7 according to the above-mentioned distribution law, and the solid phase particles 9 descend in the nucleation chamber 2 and pass through the lower passage 4 to generate nuclei. Move to melting chamber 3. The solid phase particles 9 that have moved to the nuclear melting chamber 3 are deposited below the nuclear melting chamber 3. When the deposition amount increases, the solid phase particles 9 float above and reach the molten metal ignition region 8 and melt. Thus, high-purity solid-phase particles 9
Is transferred to the nuclear melting chamber 3 with a good yield without being affected by the heat flow, and is further melted after being transferred to the nuclear melting chamber, so that the purification efficiency is improved. A raw material Al melt 7 is supplied to the nucleation chamber 2 of the unit furnace 1 according to the generation rate of the solid phase particles 9. A highly purified molten metal 17 overflows from the nuclear melting chamber 3 and is produced. By using multiple unit furnaces and connecting the upper part of the nuclear melting chamber of the previous unit furnace and the nucleation chamber of the next unit furnace with a gutter, etc., and using it as a purifier, a molten metal of higher purity can be continuously produced. Produced. In the method of the present invention, it is preferable that the molten metal temperature of the molten metal ignition zone 8 in the nuclear melting chamber 3 is kept sufficiently higher than the melting temperature of the solid phase particles 9 because the purification rate is improved.

[0008]

In the method of the present invention, the temperature of the molten metal in the vicinity of the outlet of the lower passage in the nuclear melting chamber is suppressed to a temperature lower than the melting temperature of the solid phase particles, and the solid phase particles transferred from the nucleation chamber are dissolved in the vicinity of the outlet of the lower passage. Since it is performed above, the high-temperature molten metal in the nucleation chamber rises in the nucleation chamber or the molten metal in the lower passage to push back the solid-phase particles, or to move the solid-phase particles to the nucleation chamber or the lower part. Purification efficiency is improved without melting in the passage. Further, since the solid phase particles transferred to the nuclear melting chamber are melted above the nuclear melting chamber, the temperature of the molten metal in the molten metal ignition zone can be set high and the melting rate of the solid phase particles can be increased.

[0009]

EXAMPLES The present invention will be described in detail below with reference to examples. Example 1 Five unit furnaces shown in FIG. 1 were used, and the upper parts of the nuclear melting chamber of the previous unit furnace and the nucleation chamber of the next unit furnace were connected by a gutter to form a purifying device. A refining experiment of the molten Al was performed. The nucleation chamber of the unit furnace has a depth to the entrance of the lower passage of 400 mm and a cross-sectional inner diameter of 200 x 110 m.
m, depth of the nuclear melting chamber is 500 mm, inner diameter of cross section is 60 × 1
10 mm, the lower passage has a length of 200 mm, and the inner diameter of the cross section is 2
A graphite rectangular cylinder of 5 × 110 mm was used. A heating element made of silicon knit was embedded in the walls of the nucleation chamber and the nucleation chamber. Al molten metal has a distribution coefficient of less than 1 C
A 99.7% pure impurity element containing 1500, 300, 300, 200, 400, 200 and 500 ppm of impurity elements such as u, Fe, Mg, Ni, Si, Mn and Zn was used. The melt temperature T ₁ of the 663 ° C. nucleation chamber below the first unit furnace, molten metal temperature of Matakaku lysis chamber is in the vicinity of the lower passage outlet the melt temperature T ₂ 670
° C., the addition of the molten metal temperature T ₃ of the molten metal Ignition zone to 685 ° C., above the melt temperature T ₄ from the melt Ignition region also was controlled to 690 ° C.. The molten metal ignition zone is 1 from the bottom of the nuclear melting chamber.
The range was 50 to 250 mm. T ₁ , T ₂ , T ₃ , T
The temperature measurement positions of ₄ are indicated by the symbols ,,, in the figure. An internal water-cooled AC oscillation type was used as the nucleation device immersed in the upper part of the molten metal in the nucleation chamber. As the surface material of the molten metal immersion portion of this nucleation apparatus, graphite and alumina having different wettability with Al molten metal were mixed and sintered, and fine solid phase particles were generated. The frequency of the nucleation device is 50 Hz, the amount of cooling water is 30 ml / min, and 4 / min.
0 g of solid phase particles were produced. Therefore, 40 g of the raw material molten metal was supplied to the nucleation chamber of the first unit furnace per minute. Second
The molten metal temperature after the unit furnace is as much as the purity increases,
The temperature was set slightly higher than the molten metal temperature of the unit furnace. The molten metal temperature distribution in the nuclear melting chamber was controlled so as to be similar to that of the first unit furnace.

Example 2 In Example 1, the molten metal temperature T ₁ was 663 ° C., T ₂ was 670 ° C., T ₃ was 680 ° C. without the molten metal ignition zone.
A purification experiment was conducted by the same method as in Example 1 except that T ₄ was set at 690 ° C. Comparative Example 1 Using the conventional unit furnace shown in FIG. 2, the molten metal temperature T ₁ was 663 ° C., T ₂ was 675 ° C., T ₃ was 680 ° C., and T
_A purification experiment was performed by the same method as in Example 1 except that ₄ was set to 690 ° C. In this way, one purification experiment
At 0 hours, the melt overflowing from each nuclear melting chamber was sampled and the impurities were quantitatively analyzed.
The results are shown in Table 1.

[0011]

[Table 1]

As is clear from Table 1, the invention examples (No.
In Nos. 1 and 2, the amount of impurities was smaller than that in Comparative Example (No. 3). Among them, the No. 1 which has a molten metal ignition zone. 1 is
The purification efficiency was particularly excellent, and the purity of the fourth unit furnace outlet was higher than that of the fifth unit furnace outlet of the comparative example (No. 3). From this, it was demonstrated that the number of unit furnaces can be reduced by the method of the present invention. The reason why the purification efficiency of the comparative example (No. 3) is low is that the temperature of the molten metal near the outlet of the lower passage of the nuclear melting chamber exceeds the melting temperature of the solid phase particles, and the molten metal temperature T ₁ below the nucleation chamber and the nuclear melting chamber Temperature T near the outlet of the lower passage of
_Since the difference between the temperature and the value of ₂ was as large as 12 ° C, the high temperature molten metal in this part rose in the nucleation chamber and the lower passage to push back the solid phase particles that were descending, and also to transfer the solid particles to the nucleation chamber and the lower passage. It is due to the fact that it melted inside. In Examples ₁ and ₂ , the difference between the melt temperature T ₁ below the nucleation chamber and the melt temperature T ₂ near the outlet of the lower passage of the nucleation chamber was 7 ° C. The upward flow of the molten metal from the nucleation chamber to the nucleation chamber is negligible, and it is considered that solid-phase particles are not pushed back. Although the case of purifying an Al molten metal has been described above, the method of the present invention can be applied to the case of purifying another molten metal such as copper, and the same effect can be obtained. Further, the method of the present invention can enhance the purification efficiency even when applied to the method for purifying a metal containing an impurity having a distribution coefficient K of more than 1 which was previously proposed by the present inventors in Japanese Patent Application No. 61-241036. It is possible.

[0013]

As described above, according to the method of the present invention, the metal purification efficiency can be increased by a simple operation of controlling the temperature of the molten metal in the nuclear melting chamber of the unit furnace to a predetermined temperature distribution. Has a remarkable effect.

[Brief description of drawings]

FIG. 1 is an explanatory view of essential parts showing an example of a mode of a unit furnace used in a method of the present invention.

FIG. 2 is an explanatory view of a main part of a metal unit furnace used in a conventional method.

FIG. 3 is a metal state diagram for explaining a distribution law of solute elements.

[Explanation of symbols]

 1 unit furnace 2 nucleation chamber 3 nucleation chamber 4 lower passage 5 nucleation device 6,16 heating element 7,17 molten metal 8 molten metal ignition zone 9 solid phase particles 10 gutter

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Akira Yamazaki 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd. (72) Yoshihiro Yama Yamada 2-6-1, Marunouchi, Chiyoda-ku, Tokyo Furukawa Electric Co., Ltd.

Claims (1)

[Claims] 1. A molten metal is held in a unit furnace in which a nucleation chamber and a nucleation melting chamber are connected to each other with a passage provided in the lower portion, and high-purity solid-phase particles generated in the nucleation chamber are nucleated through the lower passage. In the metal purification method in which the solid phase particles are continuously transferred to the chamber, and the transferred solid phase particles are melted in the nuclear melting chamber, the temperature of the molten metal near the outlet of the lower passage of the nuclear melting chamber is lower than the melting temperature of the solid phase particles. And the temperature of the molten metal above the vicinity of the outlet of the lower passage to a temperature above the melting temperature of the solid phase particles.