JP2000144474A - Method for electrolytic refining gallium and device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently recover refined gallium from a raw gallium material contg. impurities by electrolysis. SOLUTION: A liq. raw gallium material 3 is used as an anode, and refined gallium is deposited on a cathode in an electrolytic solution 1 to electrolytically refine gallium. In this case, the scum formed on the anode surface is discharged outside an electrolytic cell 2, the liq. raw gallium material as the anode is replenished until the electrolysis is finished, and further the gallium concn. in the electrolytic solution is kept in a specified range during the electrolysis.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method and an apparatus for electrolytic purification of gallium.

[0002]

2. Description of the Related Art Recently, demand for gallium metal as a raw material for compound semiconductor devices such as GaAs and GaP and light emitting devices has been increasing. Gallium is mainly produced as a by-product of the alumina manufacturing process and zinc smelting, but scrap of semiconductor materials is also a gallium raw material.

As such a method for purifying gallium from a gallium raw material, a crystal refining method, a single crystal pulling method, and an electrolytic refining method have been well known.

The crystal refining method is a method in which seed crystals are grown on the cooling medium side of molten gallium metal, the seed crystals are grown by the cooling effect of the cooling medium, and purified solid gallium is obtained on the grown crystal side. . For example, JP-A-2-5
No. 0926 discloses a crystal purification method in which such crystal growth is performed in multiple stages.

[0005] The single crystal pulling method is a purification method in which the tip of a seed crystal is brought into contact with molten gallium metal, and a single crystal grown from the seed crystal and excluding impurities is slowly pulled. For example, JP-A-2-243727 discloses that
In this method, it is taught that forming an acidic solution layer on the surface of molten gallium improves purification efficiency.

[0006] The electrolytic refining method utilizes the property that when gallium raw material is used as an anode and energized, gallium and a metal that is electrochemically less than gallium are eluted into the electrolytic solution, and gallium and a metal nobler than gallium are electrodeposited at the cathode. Then, purified gallium metal is obtained on the cathode. For example, in JP-A-6-192877, when a gallium raw material liquid is put into the bottom of an electrolytic cell and electrolysis is performed between the raw material liquid and a rod-shaped cathode, the gallium metal deposited on the surface of the cathode becomes granular. It teaches that impurities such as indium, copper, and lead in the gallium raw material are left on the anode side while being dropped and collected in a receiver below.

[0007]

In the crystal refining method, the gallium purity cannot be increased unless the operation is repeated, and the process is complicated and the productivity is not good. Therefore, the raw material to be treated is more than 5N (99.999). % Or more of gallium metal and apply it to 6N or 7N or more (99.99999).
% Or 99.9999999% or more), and is often limited to applications in a high-purity region, and raw materials having a purity of about 2N and 3N have poor yields and are not suitable. Also,
Similarly, the single crystal pulling method is limited to application in a high-purity region, and has a problem that the equipment is expensive.

On the other hand, the electrolytic refining method is simpler in process than the former two methods, requires almost no manual operation, and is inexpensive, so that it can be used as a bridge to high-purity purification.
There is an advantage that it can be applied as a low-purity purification method. However, in the conventional electrolytic refining method, indium, copper, lead and the like are concentrated and left in the anode, and when a predetermined amount or more of impurities are concentrated in the anode, the impurities enter the electrolyte and precipitate on the cathode. This results in reduced gallium purity. Therefore, when the purity of purified gallium is regulated, the electrolytic life is naturally determined. In addition, there is a problem that "gold" mixed in a semiconductor scrap or the like cannot be removed by the conventional electrolytic refining method.

[0009]

Accordingly, the present invention provides
Inexpensive and simple process, which can remove impurities such as gold that could not be removed by the conventional method and increase the concentration of impurities in the anode in the electrolytic refining method of gallium that requires almost no manual operation. Another object of the present invention is to develop a method for electrolytically refining gallium that can extend the life of electrolysis and to purify gallium with high yield.

[0010]

According to the present invention, in a gallium electrolytic refining method in which purified gallium is deposited in an electrolytic solution on a cathode using a gallium raw material liquid as an anode, scum generated on the surface of the anode is converted into an electrolytic cell. It is characterized by performing an operation of discharging to the outside, an operation of replenishing the gallium raw material liquid of the anode until the end of electrolysis, and an operation of maintaining the gallium concentration in the electrolyte within a predetermined range during electrolysis. Provided is a method for electrorefining gallium.

Further, according to the present invention, there is provided an anode chamber for accommodating a gallium raw material liquid as an anode, and a cathode chamber for collecting purified gallium deposited on the cathode, and a space between the anode chamber and the cathode chamber. In a gallium electrolyzer in which an electrolyte is supplied so as to flow, the anode chamber is formed in a cylindrical container, a magnet rotator is installed below the outside of the cylindrical container, and a central portion in the cylindrical container is provided. A suction pipe is arranged, and an auxiliary electrolytic cell having an insoluble anode and a cathode is provided outside the electrolytic device and a circuit for circulating the electrolytic solution between the electrolytic device and the auxiliary electrolytic cell is provided. Further, there is provided a gallium electrolytic refining apparatus characterized in that an intermediate tank is installed, the suction pipe is connected to the intermediate tank, and a filter is interposed in a pipe leading from the intermediate tank to the electrolytic apparatus.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION The inventors of the present invention have conducted intensive tests and researches to solve the above-mentioned problems. In the electrolytic refining method for depositing gallium metal, if scum generated on the anode surface is discharged out of the electrolytic cell together with part of the electrolyte, electrolysis can be continued even if the impurity concentration in the anode remains high. Have been found to be able to significantly improve the electrolytic life. It was also found that by performing the operation of discharging the scum, the gold accompanying the gallium raw material can be removed. Since the electrolysis can be continued even when the impurity concentration in the anode is high, the electrolysis can be performed while replenishing the gallium raw material liquid for the anode, and purified gallium can be obtained with a high yield. At that time, if the operation of keeping the gallium concentration in the electrolytic solution constant is performed, the electrolytic life can be further extended.

When the gallium raw material liquid in the electrolytic solution is rotated (turned), a substance exhibiting black color gathers on the liquid surface at the center of rotation. Since this substance has a black color, it can be regarded as containing gallium oxide. If scum is collected at the center of rotation of the anode using centrifugation and this scum is sucked out with a suction pipe, the oxide film generated at the interface between the gallium raw material liquid and the electrolyte can be easily removed, and gold can also be removed. It has a special effect where it can. This is because the formation of the oxide film extremely deteriorates the electrolysis efficiency, and gold cannot be separated by the usual gallium electrorefining method.

The present inventors have performed an operation of sucking out scum collected on the surface of the gallium raw material liquid at the center of rotation using a suction pipe, and surprisingly found that gold is sucked out together with the scum. . Although the reason is not always clear, gallium oxide is mainly formed on the surface of the raw material liquid as the electrolysis proceeds, and this oxide has a property that gold is more easily taken up than the liquid phase of the raw material gallium. It is thought that there is.

The gold accompanying the gallium raw material liquid does not remain in the anode residue (anode slime) in ordinary electrolysis, as shown in a comparative example described later. From the standard electrode potential, gold falls into the most noble category, and should not electrochemically dissolve (ionize) from the anode at the electrolytic potential of gallium. Nevertheless, since it does not remain in the anode residue, it is considered that it may be dispersed in the electrolytic solution in a colloidal state for some reason. Then, it is considered that the fine gold particles floating in the electrolyte in the colloidal state are involved when the gallium ions are electrodeposited at the cathode, and are entrained in the purified gallium.

As described above, the gold accompanying the gallium raw material is difficult to remove by the electrolytic refining. However, according to the present invention, the gold can be extracted together with the scum through the suction pipe, and the gold can be removed. It became very easy. Other impurities, such as In, Cu, and Pb, behave differently from gold and are concentrated as anode residues.

Also, by removing scum from the anode surface, electrolysis can be continued even if impurities in the gallium raw material are concentrated to a high concentration in the anode residue, and gallium can be newly added during the electrolysis. Even if you replenish the raw material liquid,
Electrolysis can be continued without hindrance. At this time, if the concentration of gallium in the electrolyte becomes too high, impurities in the anode also begin to dissolve in the electrolyte, so that the gallium concentration in the electrolyte is 150 g / g.
L, preferably 100 g / L or less, more preferably 60 g / L or less. For this reason, the electrolyte is circulated through an electrolytic collection tank installed outside the electrolytic cell, and gallium in the electrolytic solution is deposited on the cathode of the electrolytic collection tank, thereby removing excess gallium dissolved in the electrolytic solution. It is desirable to collect.

However, when the concentration of gallium in the electrolytic solution is too low, the current efficiency (the amount of electrodeposited metal / theoretical electrodeposited metal) decreases, so that the concentration of gallium in the electrolytic solution is 30 g / L or more, preferably 50 g / L. It is desirable to maintain above. When the concentration is less than 30 g / L, the current efficiency falls below 80%. Therefore, the concentration of gallium in the electrolyte is 30 to 150 g / L, preferably 30 to 100 g / L,
More preferably, it is good to maintain 50-60 g / L.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a schematic sectional view showing an example of an apparatus for carrying out the method of the present invention, and FIG. 2 is a schematic plan view of an electrolytic cell of the apparatus.

In this apparatus, the inside of an electrolytic cell 2 containing an electrolytic solution 1 is divided into an anode chamber 4 containing a gallium raw material liquid 3 as an anode and a cathode chamber 5 for collecting purified gallium deposited on a cathode. The anode chamber 4 is formed by a cylindrical container 6, a magnet rotator 7 is provided below the outside of the cylindrical container 6, and a suction pipe 8 is arranged in the center of the cylindrical container 6. It is ideal that the inner wall of the cylindrical container 6 is a perfect circle. However, in some cases, the inner wall may be a polygon having a partly angled corner. Is also good. Reference numeral 9 denotes a conductive rod coated with insulation. Metal terminal 10 attached to the tip of this conductive rod 9
Is immersed in the gallium raw material liquid 3, and a positive voltage is applied to the conductive rod 9, whereby the gallium raw material liquid 3 becomes an anode. On the other hand, the electrolyte in the cathode chamber 5 contains the cathode plate 11.
Is immersed, and a negative voltage is applied to this.

The anode chamber 4 and the cathode chamber 5 are configured so that the electrolyte 1 communicates with each other. In the illustrated apparatus, the height of the cylindrical container 6 forming the anode chamber 4 is adjusted to the height of the electrolyte 1. By installing it on one side in the electrolytic cell 2 so that it is lower than the surface,
The electrolyte is communicated with both chambers 4 and 5. Reference numeral 12 denotes a partition plate disposed between the two chambers 4 and 5. The height of the partition plate 12 is set lower than the level of the electrolytic solution in substantially the same manner as the cylindrical container 6. The partition plate 12 and the cylindrical container 6
A lid 13 is provided in a space formed between the cover 13 and the space 13, and a space below the cover 13 is hollow. The configuration in which the electrolytic solution 1 communicates between the anode chamber 4 and the cathode chamber 5 is not limited to this example. For example, an independent cathode chamber is formed adjacent to a cylindrical container forming the anode chamber, A configuration in which a communication path is provided on a wall that separates both chambers may be used.

A magnet rotator 7 installed outside and below the cylindrical container 6 is mounted so as to rotate around the central axis of the container 6, and the rotation is given by a motor 14.
A permanent magnet is used for the rotor 7, which rotates on a horizontal plane below the container 6 about the container axis, so that the gallium raw material liquid 3 in the container 6 is given a rotational force in the same direction by the magnetic force. Therefore, a swirling flow is generated around the container axis, and centrifugal force is given by this rotation.

The suction pipe 8 installed at the center of the cylindrical vessel 6 is positioned above the electrolytic cell 2 so that the suction hole at the tip thereof is located at the central surface of the swirling gallium raw material liquid 3. From above to be inserted into the electrolyte so as to be vertically movable. Accordingly, when a negative pressure is generated in the suction pipe 8 and the suction is performed, the material on the central surface of the raw material liquid 2 is sucked. At that time, the position of the suction hole at the tip is adjusted so that the material at the extreme surface of the raw material liquid 2 can be sucked.

At the center surface of the swirling gallium raw material liquid 3, a substance 15 (scum) having a lower specific gravity than the raw material liquid is collected by centrifugal force.
The scum 15 can be sucked out of the device. At that time, even if the electrolyte 1 is entrained, a small amount of the raw material liquid 3
There is no particular problem if the amount is accompanied by an amount that does not interfere with electrolysis.

On the other hand, in the cathode chamber 5, gallium metal precipitates on the surface of the cathode plate 11, but when the temperature of the electrolytic solution is maintained at a temperature equal to or higher than the melting point of gallium, the deposited gallium metal becomes liquid, and And is collected as refined gallium from the outlet 17.

In such an apparatus configuration, in the illustrated apparatus, an auxiliary electrolytic cell 20 having an insoluble anode 18 and a cathode 19 is provided outside the electrolytic cell 2, and the electrolytic cell 2 and the auxiliary electrolytic cell 2 are provided.
A circuit 21 (a, b, c, d) in which the electrolyte 1 circulates between 0 is provided.

The auxiliary electrolytic cell 20 prevents gallium concentration in the electrolytic solution 1 from becoming too high by precipitating gallium dissolved in the electrolytic solution 1 at the cathode 19. Perform gallium electrowinning. The gallium metal deposited on the cathode 19 of the auxiliary electrolytic cell 20 is dropped from the cathode 19 to the bottom of the cell and is collected as purified gallium from the outlet 22 because the electrolytic solution is maintained at a temperature higher than the melting point of gallium.

In the illustrated apparatus, an intermediate tank 24 is further provided outside the electrolytic tank 2. This intermediate tank 2
4, the electrolytic solution passed through the auxiliary electrolytic cell 20 is supplied to a conduit 21b.
The intermediate tank 24 and the suction pipe 8 are connected by a pipe 25, and the fluid sucked by the suction pipe 8 is supplied to the intermediate tank 24. And, in the pipe 21c leading from the intermediate tank 24 to the electrolytic tank 2,
A filter 26 and a pump 27 are interposed. That is,
The overflow electrolytic solution in the electrolytic cell 2 is configured to return to the electrolytic cell 2 via the pipe 21a → the auxiliary electrolytic tank 20 → the pipe 21b → the intermediate tank 24 → the pipe 21c → the filter 26 → the pipe 21d.

A pump 28 is interposed in a pipeline 25 extending from the suction pipe 8 to the intermediate tank 24. By driving the pump 28, a negative pressure is generated in the suction pipe 8 and the suction pipe 8 is sucked into the suction pipe 8. The fluid (scum 15 + electrolyte 1 + raw material liquid 3) is supplied to the intermediate tank 24. At that time, by controlling the rotation speed and starting / stopping the pump 28,
The amount of suction can be adjusted, and the flow rate can be adjusted by providing a flow control valve (not shown) in the conduit 25. However, a head may be provided between the intermediate tank 24 and the suction pipe 8, and the fluid may flow naturally into the intermediate tank 24 by the head without using the pump 28. In this case, a flow rate adjusting valve is provided in the pipeline 25 to adjust the flow rate.

In the intermediate tank 24, the scum from the suction pipe 8 and the electrolytic solution and the electrolytic solution from the auxiliary electrolytic tank 20 are combined, while the fluid stays in the intermediate tank 24.
Adjust the temperature of the electrolyte in the entire system. For this purpose, the intermediate tank 24 is provided with a heater 30 and a stirrer 31. The heater 30 employs a throw-in heater in the illustrated example, and heats the fluid in the tank to a predetermined temperature by adjusting the amount of electricity of the heater 32 immersed in the liquid. Stirrer 31
The agitating blade 33 is rotated by a motor to impart agitation to the fluid in the tank.

The fluid in the tank whose temperature has been adjusted is returned to the electrolytic cell 2 by the pump 27. In this process, the suspension (scum) in the fluid is filtered off by passing through the filter 26. Activated carbon is used as a filter material for the filter 21 in the illustrated apparatus, but a resin filter made of polypropylene, Teflon, or the like can be used, and other materials that are resistant to alkali at 50 ° C. are not particularly limited.

The filtrate of the filter 21 is returned to the electrolytic cell 2 via a pipe 21d. By disposing the discharge end 35 of the pipe 21d on the side of the anode chamber 4 (cylindrical vessel 6), this fluid is used as a raw material. It is poured into the upper part of the liquid 3. Due to this reflux, the liquid level of the electrolytic solution 1 in the electrolytic cell 2 is kept at a certain level during the electrolysis (the overflow port 3).
6) and the temperature of the electrolyte is also maintained at a predetermined temperature.

The electrolytic cell 2 is provided with a raw material supply tube 37 for supplying the gallium raw material liquid to the cylindrical container 6 of the anode chamber 4 during electrolysis. This tube 37 is detachably installed, but when replenishing the raw material, the injection end 3 is closed.
8 is immersed in the gallium raw material liquid 3 and the liquid gallium raw material is injected.

In FIG. 2, the left half with the electrode plate 11 as the central axis is symmetrically arranged on the right side, and the anode chamber 4 having the cylindrical container 6 is provided on both sides of the cathode chamber 5 with the cathode chamber 5 interposed therebetween. If the electrolytic cell is configured in such a manner, the processing amount can be doubled.

Next, a description will be given of an operation mode when the method of the present invention is carried out using the illustrated apparatus.

The heights of the cylindrical container 6 and the partition plate 12 are not particularly limited.
It is preferable that the electrolytic solution 1 freely flows between the anode chamber 4 and the cathode chamber 5. An aqueous solution of NaOH is used for the electrolytic solution 1. The NaOH concentration is 100 to 200 g / L, more preferably about 150 g / L. When the NaOH concentration is lower than 100 g / L, the voltage between the electrodes increases, and the purity of purified gallium decreases. On the other hand, if it exceeds 200 g / L, the concentration of impurities dissolved in the liquid increases, and the purity of purified gallium also decreases. The temperature of the electrolyte is 35 to 70
C is preferable, and more preferably 50 to 65C.
If the temperature is lower than 35 ° C., the voltage between the electrodes increases, and if the temperature exceeds 70 ° C., the electrolytic efficiency does not particularly increase, and the material of the electrolytic cell may be affected. The temperature of the electrolytic solution is adjusted by the heater 30 of the intermediate tank 24 in the illustrated apparatus. In addition,
Since the melting point of metallic gallium is 29.9 ° C., the temperature in the bath must be maintained higher than this.

Under the conditions of the electrolytic solution, an appropriate amount of the gallium raw material liquid 3 is put into the cylindrical container 6 of the anode chamber 4, and the centrifugal force is applied to the raw material liquid 3 by rotating the magnet rotor 7. An electric current is started between the raw material liquid 3 and the cathode plate 11 using the raw material liquid 3 as an anode, so that the current density becomes 0.02 to 0.2 A / cm ² , preferably 0.05 to 0.1 A / cm ^2. Turn on electricity. When the current density is lower than 0.02 A / cm ² , the electrolysis does not proceed, and when the current density exceeds 0.2 A / cm ² , the purity of the purified gallium decreases.

During the electrolysis, when the raw material liquid 3 is rotated around the central axis by the magnet rotor 7 and the centrifugal force is continuously applied, a substance (scum 15) having a lower specific gravity than the gallium metal becomes a central part of the surface of the raw material liquid 3. Come together. The number of rotations of the magnet rotor 7 is controlled so that the gathering state of the scum 15 becomes the best, and the rotation state of the raw material liquid 3 is adjusted. Scum 15
Is blacker than the raw material liquid.
You can know the state of gathering on the central surface.

As described above, the scum 15 gathered at the center may contain a small amount of oxides of impurities in the raw material liquid 3 including gallium oxide. However,
Since gold is hardly oxidized, it should not be possible for gold oxide to be present.
Then, when this scum 15 is sucked up, gold is also accompanied.

When the scum 15 gathered at the center is sucked up by the suction pipe 8, the suction hole at the tip of the suction pipe 8 is positioned slightly above the scum 15 so that the raw material liquid 3 is not sucked up as much as possible. Therefore, it is preferable to suck up the scum 15 together with the electrolytic solution 1. As a result, most of the generated scum 15 can be sucked up together with the electrolytic solution, and it can be sucked up with gold, assuming that the raw material liquid is unavoidably accompanied by the raw material liquid.

In the illustrated apparatus, the gold-entrained scum 15 sucked up together with the electrolyte enters the intermediate tank 24, is stirred from the auxiliary electrolytic tank 20 with the electrolyte entering the intermediate tank 24, and is heated by the heater 30. . As a result, a fluid at a predetermined temperature in which scum, gold, and a small amount of a gallium raw material liquid are turbid in the electrolytic solution can be obtained. This fluid is the filter 2
After the suspension is filtered off in step 6, it is returned to the electrolytic cell 2,
The temperature and the flow rate of the reflux liquid are adjusted by the operation of the heater 30 and the rotation speed of the pump 27 so as to correspond to the temperature and the amount of the electrolyte required in the electrolytic cell 2. This operation can be performed by automatic control.

In the course of the reflux, the suspended matter in the liquid is filtered off in the filter 26, and gold is entrained with the filtered substance. The gold recovered here occupies most of the gold mixed in the gallium raw material liquid. Therefore, the concentration of gold in the remaining anode is extremely low, and the concentration of gold in purified gallium deposited at the cathode is also extremely low. The lower gold concentration in the purified gallium can significantly reduce the load of the next step for obtaining high-purity gallium. The removal of gold by the method of the present invention is very advantageous in producing high purity gallium of 6N or 7N.

In this manner, the gold mixed in the gallium raw material liquid 3 is removed by the filter 26, and impurities such as In, Cu, Pb and the like mixed in the gallium raw material liquid 3 are concentrated in the anode residue. As a result, the purified gallium collected in the reservoir 16 of the cathode chamber 5 contains Au, In, C
U, Pb, etc. hardly coexist, resulting in high-purity metallic gallium.

On the other hand, since oxide scum generated on the surface of the gallium raw material liquid 3 is removed, troubles such as breakout (electrolysis stop) due to generation of these oxide films occur (the oxide film becomes an insulating layer). If the interelectrode voltage is sharply increased, and if the electrolysis is forcibly continued, low purity gallium is electrodeposited on the cathode, etc.) can be prevented beforehand. Therefore, even if the gallium raw material is supplied from the raw material supply tube 37 and the electrolysis is continued, the electrolysis can proceed without any trouble. If the electrolysis is advanced while replenishing the raw materials, the impurity concentration in the anode residue will increase. However, according to the method of the present invention, the electrolysis can be continued unless the impurity concentration becomes very high as a result of removing the scum on the surface. it can.

During the continuation of the electrolysis, the concentration of the electrolytic solution is controlled in the auxiliary electrolytic cell 20. This is because the concentration of gallium in the electrolyte gradually increases during electrolysis. In terms of electricity, the anode
The amount of gallium dissolved in the electrolyte should be the same as that of the cathode and the amount of electrodeposition at the same load, but the gallium concentration in the electrolyte should be kept constant. The gallium concentration in the electrolyte gradually increases due to the elution of an equivalent or more of the purified gallium which has been electrodeposited once again at the cathode. As described above, when the concentration of gallium in the electrolytic solution increases, elution of impurities into the electrolytic solution may also start. Therefore, by precipitating gallium in the electrolytic solution on the cathode 19 in the auxiliary electrolytic tank 20, excessive dissolution is caused. Gallium is collected as purified gallium. In the auxiliary electrolytic cell 20, the gallium concentration in the electrolytic solution exiting the electrolytic cell 20 is within a predetermined range, for example, 30 to 15
0 g / L, preferably 30 to 100 g / L, and more preferably 50 to 60 g / L.
What is necessary is just to control the amount of electricity to be applied between the anode and the cathode 19 and the duration of the electricity. This control can be automated.

As described above, according to the present invention, even if the gallium raw material is supplied to the anode during electrolysis and electrolysis is continued for a long time, the cathode 11 of the electrolyzer 2 and the cathode 19 of the auxiliary electrolyzer 20 are used. Impurities can be prevented from being mixed into the purified gallium precipitated and recovered, and the anode residue can have a high impurity concentration of In, Cu, Pb, etc., and the gold can be filtered.
Therefore, purified gallium can be produced with high productivity under a high purification rate.

[0047]

EXAMPLE 1 In the apparatus shown in FIGS. 1 and 2, 35 L of an electrolytic solution in which 50 g / L of Ga and 150 g / L of NaOH were dissolved was placed in the electrolytic cell 2.
The pump 27 was driven in the order of → the auxiliary electrolytic cell 20 → the intermediate cell 24 → the electrolytic cell 2 to circulate at a flow rate of 300 mL / min. Then, in the intermediate tank 24, the heater 30 and the stirrer 31 are turned on, and the temperature of the electrolytic solution in the electrolytic tank 2 becomes 5 °.
The amount of heat input by the heater 27 was adjusted by a controller attached to the heater so that the temperature became 0 ° C.

Next, 10 kg of the gallium raw material liquid 3 previously melted is charged into the cylindrical container 6 of the anode chamber 4, the motor 14 is driven to rotate the magnet rotor 7, and the gallium raw material liquid 3 is rotated. 3 was caused to generate a swirling flow to apply a centrifugal force. In this state, the suction hole at the tip of the suction pipe 8 is adjusted to a position approximately 5 mm higher than the surface of the center of the raw material liquid 3, and the pump 28 is driven to 150 mL.
/ Min. The metal terminal 10 at the tip of the conductive rod 9 was set so as to be constantly immersed in the gallium raw material liquid 3. In this state, current supply was started at a current density of 0.10 A / cm ² with the cathode plate 11 made of a stainless steel plate, and electrolysis was continuously performed for 879 hours. in the meantime,
The molten gallium raw material liquid was supplied from the raw material supply tube 37 in a total of 43.7 kg in 24 divided portions. In addition, in the auxiliary electrolytic cell 20, the gallium concentration in the electrolytic solution is 50 to 60 g / min by starting and stopping the energization under a current of 6 A.
Gallium was electrowinned so as to fall within the range of L.

During the electrolysis, the pumping amounts of the pumps 27 and 28 are kept substantially at the above-mentioned amounts, and the vertical position is adjusted so that the suction pipe 8 is maintained at a position about 5 mm higher than the scum 15 gathered at the center. did. Activated carbon was used as the filter medium of the filter 26.

Table 1 shows the operation results of this example.

[0051]

[Table 1]

As can be seen from the results in Table 1, the amount of purified gallium thus obtained, together with the electrolytic cell 2 and the auxiliary electrolytic cell 20, could be recovered to nearly 90% of the raw material gallium, but the electrolytic gallium was still electrolyzed. Was possible. In addition, impurities of the obtained purified gallium can be reduced to 7 ppm for indium, 0.1 ppm or less for gold, and 0.5 ppm or less for copper and lead, and a gallium grade of 4 to 5N (99.9) can be obtained.
99%) class.

Example 2 Processing was performed in the same manner as in Example 1 except that a gallium raw material having a large amount of impurities was used. However,
The electrolysis time was up to 395 hours. During that time, the molten gallium raw material liquid was supplied in a total of 12.2 kg in 10 divided portions. Table 2 shows the operation results.

[0054]

[Table 2]

Table 2 shows the results of electrolysis in which the concentration of In was concentrated to the limit in the gallium raw material liquid of the anode using a gallium raw material having a particularly high In concentration. This indicates that the concentration could be increased to nearly 88%. Near the end of the electrolysis, the anode showed a gray solid state except for the vicinity of the conductive rod 9. In in purified gallium
The concentration was around 800 ppm, but the values for copper and lead were below the detection values. From these results, it is understood that the method of the present invention is effective for purification from a gallium raw material having a very high In concentration.

Example 3 The purified gallium obtained in Example 2 was used as a raw material and treated in the same manner as in Example 1. The electrolysis time was continuous for 360 hours, during which time, a total of 11.8 kg of the raw material was replenished in a liquid state in ten batches. Table 3 shows the operation results.

[0057]

[Table 3]

As can be seen from the results in Table 3, the impurities of the obtained purified gallium can be reduced to 2 ppm or less for indium and 0.5 ppm or less for copper and lead, and the gallium quality can be reduced to 5N (99.999%). ) Class. The amount of purified gallium is determined by the electrolytic cell 2 and the auxiliary electrolytic cell 20.
In total, it was possible to recover up to nearly 90%.

On the other hand, since a high In residue was obtained as an anode residue in Example 2, when Examples 2 and 3 were combined, In was efficiently separated from a gallium raw material containing In at a high concentration to achieve high quality. Gallium can be obtained.

As can be seen from the above embodiments, in actual operation, by combining these embodiments, a line with extremely high production efficiency can be completed. For example, a gallium raw material 10 containing 2,000 ppm of indium as an impurity
When producing 5N class gallium from 0 kg, first, 90 kg of purified gallium is obtained from Example 1. As in Example 2, 9.7 kg of 3N-class gallium was obtained from 10 kg of anode residual gallium in which indium was concentrated to 20,000 ppm. About 0.3 kg of the impurities concentrated to 80% is bleed off, and gallium is recovered by another method. 9.7kg of 3N class gallium
Is returned to the first process, and 8.8 g of 5N class gallium
kg can be obtained. In other words, 98.
An 8% 5N class recovery is expected.

[Comparative Example] Electrolysis in the auxiliary electrolytic cell 20 was not performed, the magnet rotor 7 was not rotated (the motor 14 was not driven), and liquid was not absorbed from the suction pipe 8 (the pump 28 was stopped). Electrolysis was carried out under the same conditions as in Example 1 except that no centrifugal force was applied to the raw material liquid and no scum was discharged (the filter 26 was not used). The current efficiency with respect to the change and the In concentration in the electrolytic solution were measured. Table 4 shows the results.

[0062]

[Table 4]

As can be seen from the results in Table 4, if the gallium concentration in the electrolyte is not maintained in an appropriate range, the electrolysis efficiency is lowered and In is eluted into the electrolyte.

[0064]

As described above, according to the present invention, impurities such as gold, which cannot be removed by the conventional electrolytic refining method for gallium, can be removed, and raw materials can be supplied to the anode. In addition, the concentration of impurities in the anode residue can be increased, and the electrolysis life can be extended. As a result, the yield of purified gallium can be improved, and the purification efficiency can be improved. Therefore, it can greatly contribute to the purification of gallium from gallium raw materials produced from the zinc smelting process, crude gallium recovered from compound semiconductor scrap, and gallium raw materials having a high impurity content generated from the high-purity gallium purification process. .

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of an apparatus for performing the method of the present invention.

FIG. 2 is a schematic plan view of an electrolytic cell part of the apparatus of FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Electrolyte solution 2 Electrolyzer 3 Gallium liquid raw material 4 Anode chamber 5 Cathode chamber 6 Cylindrical container 7 Magnet rotor 8 Suction pipe 9 Conductive rod 10 Metal terminal 11 Cathode plate 12 Partition plate 15 Gallium liquid material gathered at the surface center. Scum 17 Purified gallium discharge port 20 Auxiliary electrolytic tank 21 Circulation circuit 24 Intermediate tank 25 Pipeline connecting suction pipe and intermediate tank 26 Filter 30 Heater 37 Material supply tube

 ────────────────────────────────────────────────── ─── Continuing on the front page (72) Inventor Kishio Tayama 1-8-2 Marunouchi, Chiyoda-ku, Tokyo F-term in Dowa Mining Co., Ltd. (reference) 4K058 AA12 BA07 BB03 CA07 CA25 DD18 EB02 FC13 FC27

Claims (7)

[Claims] 1. A method for electrolytically refining gallium in which purified gallium is deposited in an electrolyte using a gallium raw material liquid as an anode and discharging the scum formed on the surface of the anode out of the electrolytic cell, and until the electrolysis is completed. A process for replenishing the gallium raw material liquid for the anode during the process. 2. A method for electrolytically refining gallium in which purified gallium is deposited in an electrolytic solution on a cathode using a gallium raw material liquid as an anode, wherein scum generated on the surface of the anode is discharged out of the electrolytic cell, and until the electrolysis is completed. A process for replenishing the gallium raw material liquid for the anode and an operation for maintaining the gallium concentration in the electrolyte within a predetermined range during electrolysis. 3. The operation of discharging scum generated on the surface of the anode to the outside of the electrolytic cell is performed by applying a centrifugal force to the gallium raw material liquid of the anode by a magnetic field, and the scum collected on the surface of the central portion is removed together with a part of the electrolyte. 3. The method for refining gallium according to claim 1 or 2, wherein the gallium is sucked out of the electrolytic cell. 4. The method according to claim 3, wherein the scum and the electrolytic solution sucked out of the electrolytic cell are returned to the electrolytic cell after the scum is separated by a filter. 5. An operation for maintaining the gallium concentration in the electrolytic solution within a predetermined range during the electrolysis, wherein the electrolytic solution is circulated through an electrolytic collecting tank provided outside the electrolytic tank, and the electrolytic solution is supplied to the cathode of the electrolytic collecting tank. 5. The method for electrolytically refining gallium according to claim 2, which is an operation for precipitating gallium therein. 6. An anode chamber for accommodating a gallium raw material liquid as an anode, and a cathode chamber for collecting purified gallium deposited on the cathode, wherein a flow is made between the anode chamber and the cathode chamber. In a gallium electrolyzer containing an electrolyte solution, the anode chamber is formed in a cylindrical vessel, a magnet rotor is installed below the outside of the cylindrical vessel, and a suction pipe is arranged in the center of the cylindrical vessel. And an auxiliary electrolytic cell having an insoluble anode and a cathode provided outside the cell of the electrolytic device, and a circuit for circulating the electrolytic solution between the electrolytic device and the auxiliary electrolytic cell is provided. apparatus. 7. An anode chamber for accommodating a gallium raw material liquid as an anode, and a cathode chamber for collecting purified gallium deposited on the cathode, and an electrolytic chamber for flowing between the anode chamber and the cathode chamber. In the gallium electrolyzer containing the liquid, the anode chamber is constituted by a cylindrical container, a magnet rotor is installed below the outside of the cylindrical container, and a suction pipe is arranged at a central portion in the cylindrical container. An auxiliary electrolytic cell having an insoluble anode and a cathode is provided outside the electrolytic apparatus, and a circuit for circulating the electrolytic solution between the electrolytic apparatus and the auxiliary electrolytic cell is provided. An intermediate cell is further provided in the circulation circuit. A gallium electrolytic refining apparatus, characterized in that the suction pipe is connected to the intermediate tank, and a filter is interposed in a pipe leading from the intermediate tank to the electrolytic apparatus.