JPH05171307A - Method for purifying metal - Google Patents

Abstract

PURPOSE:To provide a purifying method of metal, by which high purity molten metal can efficiently be produced. CONSTITUTION:In the purifying method of the metal, the prescribed number of unit furnaces 1 connecting a nucleus generating chamber 2 and a nucleus melting chamber 5 through a lower passage 5 are arranged and the nucleus melting chamber 3 in the previous unit furnace 1 and the nucleus generating chamber in the following unit furnace are connected by arranging a trough 11 at the upper part to form the purifying apparatus. Then, in this purifying apparatus, the molten metal 9 is held and in each nucleus generating chamber 2, the high purity solid phase particles 10 are generated and shifted to the nucleus melting chamber 3 through the lower passage 5 and melted in the nucleus melting chamber 3 and shifted to the nucleus generating chamber 2 in the following unit furnace 1. In the lower passage 5, one pair of hollow porous compressive rolls 6 are arranged and rotated and the solid phase particles 10 in the nucleus generating chamber 2 are compressed between the compressive rolls 6 and shifted into the nucleus melting chamber 3. Further, low purity molten metal around the solid phase particles 10 is extracted into the hollow parts of the hollow porous compressive rolls 6 and removed to prevent the invasion of the low purity molten metal into the nucleus melting chamber 3, and by this method, the purifying 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 metal purification method for producing a high-purity metal used as a material for electronic devices such as bonding wires and memory disks.

[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 characteristics is required, and in response to this, the development of metallic materials based on high-purity metals is becoming active 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 for removing a trace amount of 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.

The above-mentioned distribution law will now be described with reference to the state diagram. FIG. 3 shows partition coefficient K [K = (solute concentration of crystallized solid phase) / (initial solute concentration) when the liquidus temperature is reached]
Is a phase diagram of a metal containing a solute having a value of less than 1, and most of the impurity elements have K <1. Now, when the melt having the solute concentration C ₀ in this state diagram is being cooled and the temperature reaches the liquidus temperature T ₁ , nuclei (solid phase particles) having the C ₁ concentration crystallize first.

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). As shown in FIG. 4, this metal purification device is a unit furnace composed of a nucleation chamber 2 in which a nucleation device 4 for solid phase particle generation is arranged and a nucleation melting chamber 3 for melting the solid phase particles 10. A plurality of the reactors 1 are connected to the nucleation chamber 3 of the previous unit furnace 1 and the nucleation chamber of the next unit furnace (not shown) 11
And the nucleation chamber 2 and the nucleation chamber 3 of each unit furnace 1 are partitioned by an underflow type partition wall 12, and the underflow portion between the nucleation chamber 2 and the nucleation chamber 3 is separated. A structure in which a downward slope is provided from the nucleation chamber 2 to the nuclear melting chamber 3 on the floor surface, and the temperature of the molten metal can be controlled for each chamber 2 and 3 by the heating element 13 embedded in the furnace wall Is. Thus, according to the purification method by this apparatus, the solid-phase particles 10 generated by the nucleation device 4 in the nucleation chamber 2 of the first unit furnace 1 are transferred from the nucleation chamber 2 to the nucleation dissolution chamber 3 underflow part The solid phase particles 10 flowing in the nuclear melting chamber 3 are re-melted in the nuclear melting chamber 3 kept at high temperature to increase the purity of the molten metal 9 in the nuclear melting chamber 3 Then, this molten metal 9 is transferred through a gutter 11 to a nucleation chamber of a second unit furnace (not shown), and here again the first unit furnace 1
The same operation as that carried out in step 1 is carried out with the set temperature of the molten metal raised to some extent, and the same operation is repeated until the final unit furnace, whereby the purity of the molten metal 9 is gradually increased.

[0005]

However, in the metal purification method using this apparatus, the movement of the solid phase particles in the nucleation chamber to the nucleation dissolution chamber depends on the gravity, and the low temperature around the solid phase particles is reduced. Because of the fact that the pure molten metal enters the nuclear melting chamber together with the solid phase particles, and the high temperature molten metal in the nuclear melting chamber causes an upward flow in the nucleation chamber to prevent the solid phase particles from settling,
There was a problem that sufficient purification efficiency could not be obtained.

[0006]

The present invention has been made as a result of intensive studies in view of such a situation, and an object thereof is to provide a metal purification method capable of efficiently producing a high-purity metal. To provide. That is, the present invention provides a required number of unit furnaces in which a nucleation chamber and a nucleation chamber are connected to each other with a passage provided in the lower part, and the nucleation chamber of the previous unit furnace and the nucleation chamber of the next unit furnace are located in the upper part A passage is provided and connected to form a purifier, which holds the molten metal and continuously supplies high-purity solid phase particles generated in the nucleation chamber of each unit furnace to the nucleation chamber through the lower passage. In the nucleation chamber of the next unit furnace by melting the transferred solid phase particles in the nucleation chamber, and in the metal purification method of the next unit furnace, a hollow porous pressing roll forming a pair in the lower passage is used. Arranged and rotating the pressing roll to transfer the solid phase particles from the nucleation chamber to the nuclear melting chamber, and extracting and removing the high-concentration molten metal around the solid phase particles into the hollow portion of the hollow porous pressing roll. It is characterized by.

In the method of the present invention, the solid phase particles generated in the nucleation chamber are rotated between a pair of hollow porous pressing rolls, compressed between the rolls and transferred to the nucleation dissolution chamber, and the solid phase particles are surrounded by the solid phase particles. The low-purity molten metal is extracted into the hollow portion of the hollow porous compression roll to remove it to prevent the low-purity molten metal from entering the nucleus melting chamber, and the lower passage is blocked by the hollow porous compression roll to form the core. By suppressing the upward flow of the molten metal from the melting chamber to the nucleation chamber, the sedimentation rate of solid phase particles in the nucleation chamber is increased. The method of the present invention will be specifically described below with reference to the drawings. FIG. 1 is a side view showing an example of an embodiment of a unit furnace used in the method of the present invention, and FIG. 2 is a side view showing a hollow porous press roll. The unit furnace 1 comprises a nucleation chamber 2 and a nucleation chamber 3, and the nucleation chamber 2 includes a nucleation device 4
Are arranged, and the nucleation chamber 2 and the nuclear melting chamber 3 are connected by a lower passage 5. A pair of hollow porous pressing rolls 6 are arranged in the lower passage 5 with their axes oriented at right angles to the passage direction. The hollow porous pressing roll 6 is connected to a drive motor 8 via a V-belt 7 and rotates so that the facing surface of the pressing roll 6 moves to the nuclear melting chamber 3. The boundary portion between the hollow porous press roll 6 and the lower passage wall portion is sufficiently sealed so that no molten metal leaks.

Next, using the unit furnace, the distribution coefficient K
A method for purifying a molten metal containing a solute having a value of less than 1 as an impurity will be specifically described with reference to FIGS. 1 and 2. First, a predetermined amount of molten metal 9 to be purified is injected into the nucleation chamber 2 and the nucleation melting chamber 3 of the first unit furnace 1, and then the nucleation apparatus 4 of the nucleation chamber 2 is operated and the molten metal temperature is increased. Is lowered to the liquidus temperature and kept at that temperature. Molten metal 9
Solid phase particles 10 having a higher purity than the molten metal 9 are generated according to the distribution law described above, and the generated solid phase particles 10 settle in the molten metal 9 of the nucleation chamber 2 to reach the lower passage 5 and rotate. It is drawn into the hollow porous pressing roll 6 and compressed, and only the solid phase particles 10 are fed into the nuclear melting chamber 3. Solid phase particles 10
The surrounding low-purity molten metal penetrates the wall of the hollow porous pressing roll 6 and is extracted and removed in the hollow portion of the pressing roll 6. The melt temperature in the nuclear melting chamber 3 is maintained at a temperature at which the solid phase particles 10 are melted, the solid phase particles 10 are redissolved to improve the purity of the molten metal 9 in the nuclear melting chamber 3, and the molten metal 9 is guttered 11 Through the nucleation chamber of the second unit furnace (not shown). The raw material melt 9 is replenished in the nucleation chamber 2 of the first unit furnace 1. During this time, since the lower passage 5 is blocked by the hollow porous pressing roll 6, the upward flow of the molten metal 9 from the nucleus melting chamber 3 toward the nucleation chamber 2 is blocked. In the method of the present invention, the solid phase particles 10 generated in the nucleation chamber 2 are rapidly fed into the nucleation dissolution chamber 3 using the hollow porous pressing roll 6,
The nucleation device 4 has a high nucleation speed, for example, Japanese Patent Application No. 1-27.
No. 2228 and Japanese Patent Application No. 1-290720, which have a high performance of an internal water-cooled rotary type, in which the part to be immersed in the molten metal 9 is composed of a mixture of graphite and ceramics materials having different wettability with the molten metal 9, It is preferable to use the nucleation device 4.

[0009]

In the method of the present invention, the solid phase particles generated in the nucleation chamber of the unit furnace are transferred by compressing them by rotating the pair of hollow porous pressing rolls, so that the solid phase particles are promptly sent to the nucleation chamber. Be done. Further, since the low-purity molten metal around the solid phase particles is discharged into the hollow portion of the hollow porous pressing roll, the molten metal in the nuclear melting chamber is kept in high purity. Further, since the lower passage connecting the nucleation chamber and the nucleation chamber is blocked by the hollow porous pressing roll, the rising flow of the molten metal from the nucleation chamber to the nucleation chamber is eliminated, and the solid phase particles in the nucleation chamber are quickly Settles.
Therefore, the high-purity molten metal is efficiently produced.

[0010]

EXAMPLES The present invention will be described in detail below with reference to examples. Example 1 An Al molten metal purification experiment was conducted using a purification apparatus in which five unit furnaces shown in FIG. 1 were connected in series with a gutter. The internal shape and dimensions of each unit furnace are 400 mm deep in the nucleation chamber.
Then, from the upper opening to a depth of 200 mm,
60x60mm, 20mm above the floor from a depth of 200mm
The inner surfaces of the left and right walls were linearly narrowed up to a height of about 3 degrees with a gradient of about 3 degrees, and then the floor surface had a semicircular cross section with a diameter of 40 mm. The depth of the nuclear melting chamber was 400 mm, and the length and width of the inner plane were 60 × 60 mm. The lower passage between the nucleation chamber and the nucleation chamber had a circular cross section with an inner diameter of 40 mmφ with a downward slope of 30 degrees toward the nucleation chamber. At the center of the lower passage of each unit furnace, a pair of hollow porous squeezing rolls having a structure as shown in FIG. 2 were arranged so that the shaft thereof was oriented at right angles to the passage direction. As the roll, a cylindrical alumina roll having an outer diameter of 25 mmφ and an inner diameter of 15 mmφ was used. Porous alumina having a pore size of 50 to 100 μm and a porosity of 20% was used, and the roll interval was set to 0.3 mm. A SiC heating element was embedded in the furnace wall. Further, a SiC heating element formed in a U-shaped cross section was used for the gutter after being electrically heated.

As the nucleation device, an internal water-cooled AC electric nucleation device made of a sintered body of graphite mixed with 5% alumina was used. Attach this nucleation device to the top of the melt in the nucleation chamber.
It was immersed for 30 mm, and water at 15 ° C. was flown inside the nucleation apparatus, and an alternating current of 50 Hz was applied to this to give vibration. The production rate of the solid phase particles produced by the nucleation device was variously changed depending on the amount of water flowing in the nucleation device, and the rotation speed of the hollow porous pressing roll was set to an optimum value accordingly. As the raw material molten metal, an Al molten metal having a purity of 99.7% was used. Elements of Cu, Fe, Mg, Mn, Ni, Si, and Zn are contained as impurities in this molten Al, and all of these elements have a distribution coefficient K.
Is less than 1. The raw material melt is filled in the purifying device, and the temperature of the melt in the nucleation chamber of the first unit furnace is adjusted.
Set the melt temperature in the nucleation chamber to 665 ° C and 675 ° C, respectively, to generate solid-phase particles from the nucleation device, and transfer these to the nucleation chamber through the hollow porous press roll placed in the lower passage. The purification experiment was started. The molten metal produced from the nuclear melting chamber of the first unit furnace was continuously transferred to the nucleation chamber of the second unit furnace through the gutter, and the same operation was repeated in the second unit furnace. The molten metal temperature after the second unit furnace is
It was set higher in sequence according to the purity of the molten metal. The nucleation chamber of the first unit furnace was continuously replenished with the total amount of the solid phase particles and the molten metal discharged from the hollow porous press roll. The amount of solid phase particles produced was variously changed.

Comparative Example 1 In Example 1, a refining experiment of molten Al was carried out by the same method as in Example 1 except that the hollow porous pressing roll was not arranged in the lower passage. In this way, when the high-purification experiment was continuously performed for 10 hours, the molten metal produced from the nuclear melting chambers of the fourth and fifth unit furnaces was sampled and the quantitative analysis of impurities was performed. The results are shown in Table 1 together with the amount of solid phase particles produced, the number of revolutions of the hollow porous press roll, and the amount of molten metal discharged from the hollow porous press roll.

[0013]

[Table 1]

As is clear from Table 1, all the melts produced by the method products of the present invention (Nos. 1 to 6) have a high purity, and the purity is maintained at a high level even if the production rate of solid phase particles increases. Was done. The reason why the high-purity molten metal was efficiently produced in this way is that the solid-phase particles reaching the lower passage are forcibly sent to the nuclear melting chamber by the hollow porous pressing roll, and the low-purity molten metal near the solid-phase particles is Is discharged to the outside through the hollow porous press roll, and the hollow porous press roll blocks the upward flow of the molten metal from the nucleation chamber to the nucleation chamber. On the other hand, in each of the comparative example products, the purity of the molten metal produced is low, and the purity sharply decreases as the production rate of solid phase particles increases. This is because the moving speed of the solid phase particles in the lower passage was slow, that the low-purity molten metal around the solid phase particles moved to the nuclear melting chamber together with the solid phase particles, and from the nuclear melting chamber to the nucleation chamber. The cause is that there was an upward flow of molten metal. Further, since the purified state of the product of the present invention is already higher than that of the fifth unit furnace of the comparative product at the outlet of the fourth unit, according to the method of the present invention, the unit furnace is It was proved that one can be reduced. So far, the purification experiment of a melt containing a solute with a distribution coefficient K of less than 1 as an impurity has been described. However, a melt containing a solute with a distribution coefficient K of more than 1 as an impurity can also be hollow in the apparatus proposed in Japanese Patent Application No. Purification efficiency can be improved by arranging a porous pressing roll. Needless to say, the same effect can be obtained even if the raw material melt used is not limited to the Al melt, but is applied to other metal melts such as copper. A plurality of pairs of hollow porous press rolls may be used, and the material and shape of the hollow porous press rolls can be arbitrarily designed according to the structure of the unit furnace and the type of molten metal.

[0015]

[Effect] As described above, according to the method of the present invention, the molten metal can be efficiently purified, and a remarkable effect is industrially achieved.

[Brief description of drawings]

FIG. 1 is an explanatory side view showing an example of a metal purification method of the present invention.

FIG. 2 is a side view showing an embodiment of a hollow porous pressing roll used in the metal purification method of the present invention.

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

FIG. 4 is a side view for explaining a conventional metal purification method.

[Explanation of symbols]

 1 unit furnace 2 nucleation chamber 3 nucleation chamber 4 nucleation device 5 lower passage 6 hollow porous pressing roll 7 V-belt 8 drive motor 9 melt 10 solid phase particles 11 gutter 12 partition wall 13 heating element

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

Claims (1)

[Claims] 1. A required number of unit furnaces in which a nucleation chamber and a nucleation chamber are connected to each other with a passage provided in the lower part, and a nucleation chamber of the preceding unit furnace and a nucleation chamber of the next unit furnace are connected to the upper passage. Is connected to form a purifier, which holds the molten metal in the purifier and continuously supplies high-purity solid phase particles generated in the nucleation chamber of each unit furnace to the nucleation chamber through the lower passage. In the metal purification method of transferring, melting the transferred solid-phase particles in the nucleation chamber and transferring to the nucleation chamber of the next unit furnace, a pair of hollow porous pressing rolls is arranged in the lower passage. Then, by rotating the pressing roll to transfer the solid phase particles from the nucleation chamber to the nuclear melting chamber, the low-purity molten metal around the solid phase particles is extracted and removed in the hollow portion of the hollow porous pressing roll. Characteristic metal purification method.