JP5415066B2 - Metal purification method and apparatus, refined metal, casting, metal product and electrolytic capacitor - Google Patents

Description

  The present invention relates to a metal purification method and apparatus, and more specifically, the content of eutectic impurities from metals such as aluminum, silicon, magnesium, lead, and zinc containing eutectic impurities using the principle of segregation solidification. The present invention relates to a method and an apparatus for producing a high-purity metal with a smaller amount than the original metal, and further relates to a metal purified by the above-described method, a cast product using the metal, a metal product, and an electrolytic capacitor.

  As a method for purifying this kind of metal, a rotating cooling body is immersed in a molten metal containing eutectic impurities placed in a refined molten metal holding furnace, and the cooling body is rotated while supplying a cooling fluid to the rotating cooling body. A method of crystallizing a purified metal having a high purity on the peripheral surface is known (for example, see Patent Document 1).

  In this method, it has been found that the slower the solidification rate on the peripheral surface of the cooling body, the higher the purity of the crystallized metal. By the way, when the cooling body is immersed in the molten metal to be purified while the temperature of the peripheral surface of the cooling body is low, the solidification rate on the peripheral surface is increased. Such a metal crystallized at a high solidification rate has poor adhesion to the cooling body, and is very easily peeled off by the centrifugal force caused by the rotation of the cooling body in the initial stage of purification. Moreover, there is a problem that the weight of the refined metal is reduced when there is a lot of peeling.

As a method for coping with such peeling, it has been proposed to provide a groove for preventing peeling on the circumferential surface of the rotating cooling body (see Patent Document 2).
Shoko Sho 61-3385 JP 62-280334 A

  However, the method of providing the groove for preventing peeling on the peripheral surface of the rotating cooling body is not sufficient, and peeling cannot be prevented, and thus the problem that the weight of the refined metal is still not solved. .

  The present invention has been made in view of such circumstances, and prevents the metal crystallized at a high solidification rate from peeling from the cooling body at the early stage of purification, thereby reducing the weight of the purified metal. It is an object of the present invention to provide a metal refining method and apparatus capable of increasing the size, and further to provide a metal refined by the above method, a cast product using the metal, a metal product, and an electrolytic capacitor.

The above problem is solved by the following means.
(1) In a metal purification method in which a cooling body is immersed in a molten metal to be purified and a high purity metal is crystallized on the surface of the cooling body while rotating the cooling body, the average peripheral speed of the cooling body at the initial stage of purification is A metal refining method characterized in that the refining is carried out by setting smaller than the average peripheral speed thereafter and setting the maximum peripheral speed of the cooling body at the initial stage of purification so as not to exceed the average peripheral speed thereafter.
(2) The metal purification method according to item 1, wherein the initial stage of purification is from the start of purification to the total purification time × 0.1.
(3) The relationship between the average peripheral speed V1 of the cooling body from the start of purification to the total purification time × 0.05 and the average peripheral speed V3 thereafter is set to V1 ≦ V3 × 0.9. The metal purification method as described.
(4) The relationship between the average peripheral speed V1 of the cooling body from the start of purification to the total purification time × 0.1 and the average peripheral speed V3 thereafter is set to V1 ≦ V3 × 0.9. The metal purification method as described.
(5) The metal purification method according to any one of items 1 to 4, wherein the metal to be purified is aluminum.
(6) A furnace body containing a molten metal to be refined, a cooling body immersed in the molten metal contained in the furnace body, a rotary drive device for rotating the cooling body, and a cooling body at the initial stage of purification The rotational speed of the cooling body by the rotary drive device so that the average peripheral speed is smaller than the average peripheral speed thereafter and the maximum peripheral speed of the cooling body at the initial stage of purification does not exceed the average peripheral speed thereafter. And a control means for controlling the metal refining apparatus.
(7) The metal purification apparatus as described in (6) above, wherein the initial purification period is from the start of purification to the total purification time × 0.1.
(8) The control means is such that the relationship between the average peripheral speed V1 of the cooling body from the start of purification to the total purification time × 0.05 and the average peripheral speed V3 thereafter is V1 ≦ V3 × 0.9. 8. The metal refining device according to 6 or 7 above, wherein the rotational speed of the cooling body is controlled by the rotation drive device.
(9) The control means is such that the relationship between the average peripheral speed V1 of the cooling body from the start of purification to the total purification time × 0.1 and the average peripheral speed V3 thereafter is V1 ≦ V3 × 0.9. 8. The metal refining device according to 6 or 7 above, wherein the rotational speed of the cooling body is controlled by the rotation drive device.
(10) A purified metal purified by the method according to any one of (1) to (4) above.
(11) A casting manufactured from the refined metal according to item 10 above.
(12) A metal product obtained by rolling the casting according to item 11 above.
(13) An electrolytic capacitor in which the metal product according to item 12 is used as an electrode material.

  According to the invention described in the preceding item (1), the average peripheral speed of the cooling body at the initial stage of purification is set smaller than the average peripheral speed after that, and the maximum peripheral speed of the cooling body at the initial stage of purification is set to the average peripheral speed thereafter. Since the refining is performed so as not to exceed the speed, the centrifugal force of the rotating cooling body acting on the crystallized metal having a high solidification rate at the initial stage of purification when the cooling body is immersed in the molten metal to be purified. Therefore, it is possible to prevent the crystallized metal from being separated from the rotating cooling body. Thus, the purification is performed while preventing the crystallization metal having poor adhesion to the cooling body from being peeled off, and then the peripheral speed of the cooling body is increased to crystallize the metal having a high purification efficiency. Thus, the weight of the purified metal obtained can be increased by preventing the crystallization metal from peeling off at the initial stage of purification.

  According to the invention described in the preceding item (2), separation of the crystallized metal at the initial stage of purification can be stably prevented.

  According to the invention described in the preceding item (3), the relationship between the average peripheral speed V1 of the cooling body from the start of purification to the total purification time × 0.05 and the average peripheral speed V3 thereafter is V1 ≦ V3 × 0.9. Since it is set, the effect of preventing the initial separation of the crystallized metal having a high solidification rate and poor adhesion to the cooling body can be exhibited effectively.

  According to the invention described in the preceding item (4), the relationship between the average peripheral speed V1 of the cooling body from the start of purification to the total purification time × 0.1 and the average peripheral speed V3 thereafter is V1 ≦ V3 × 0.9. Since it is set, the effect of preventing the initial separation of the crystallized metal having a high solidification rate and poor adhesion to the cooling body can be exhibited more effectively.

  According to the invention described in the above item (5), it is possible to prevent separation of crystallized aluminum having a high solidification rate and poor adhesion to a cooling body at the initial stage of purification, thereby increasing the purified weight of the aluminum lump.

  According to the invention described in the preceding item (6), there is provided a refining device capable of preventing the separation of the crystallized metal having a high solidification rate and poor adhesion to the cooling body at an early stage of purification and increasing the weight of the obtained refined metal. sell.

  According to the invention described in the preceding item (7), a purification apparatus capable of stably preventing the separation of the crystallized metal at the initial stage of purification can be obtained.

  According to the invention described in the preceding item (8), a purification apparatus capable of effectively exhibiting the initial peeling prevention effect of a crystallized metal having a high solidification rate and poor adhesion to a cooling body can be obtained.

  According to the invention described in the preceding item (9), it can be a purification apparatus capable of further effectively exhibiting the effect of preventing the initial separation of a crystallized metal having a high solidification rate and poor adhesion to a cooling body.

  According to the invention described in item (10) above, it can be a refined metal having a large weight.

  According to the invention described in the preceding item (11), it can be a casting manufactured from a refined metal having a large weight.

  According to the invention described in the preceding item (13), a rolled metal product manufactured from a refined metal having a large weight can be obtained.

  According to the invention described in item (14) above, an electrolytic capacitor using an electrode material manufactured from a refined metal having a large weight can be obtained.

  An embodiment of the present invention will be described below.

  FIG. 1 is a diagram for explaining a schematic configuration of a metal refining apparatus according to an embodiment of the present invention and a metal refining method using the same.

  In FIG. 1, reference numeral 1 denotes a molten metal holding furnace, and a molten metal 2 is accommodated and held in the molten metal holding furnace 1. A rotating cooling body 3 is disposed above the holding furnace 1 so as to be movable up and down, left and right. At the time of metal refining, the cooling body 3 moves downward and is immersed in the molten metal 2 in the molten metal holding furnace 1. Has been made. Moreover, although illustration was abbreviate | omitted, the refined metal scraping apparatus is installed by the arrangement | positioning parallel to the molten metal holding furnace 1, and the metal crystallized in the cooling body 3 can be scraped off and collect | recovered. Furthermore, the molten metal 2 in the molten metal holding furnace 1 is arranged in the heating furnace so as to have a constant temperature, and is heated from the outside of the holding furnace 1.

  A rotation driving device 4 such as a motor is connected to the cooling body via a rotating shaft 31 so that a rotational force can be applied to the cooling body 3. The rotational speed of the rotation drive device 4, in other words, the rotational speed of the cooling body 3 can be variably controlled by the control unit 5, thereby refining the average peripheral speed of the cooling body 3 at the initial stage of purification as will be described later. The average peripheral speed is set to be smaller than the average peripheral speed, and the maximum peripheral speed of the cooling body in the initial purification stage can be set not to exceed the average peripheral speed thereafter.

  As shown in FIG. 1 (a), the rotary cooling body 3 is immersed in the molten metal 2 in the molten metal holding furnace 1 and rotated while supplying a cooling fluid therein, and the purified metal 6 is disposed on the peripheral surface of the cooling body 1. Crystallize slowly. This order is not particularly limited, and there is no problem even if the rotating cooling body 3 is immersed in the molten metal 2 while rotating. The eutectic impurities are discharged into the liquid phase to form a common impurity impurity concentration layer in the liquid phase near the solidification interface. The impurities in the impurity concentration layer are formed by the relative speed between the rotating cooling body 3 and the molten metal 2. Is dispersed throughout the liquid phase. When solidification proceeds in this state, a metal lump 6 having a purity much higher than that of the original molten metal 2 is obtained on the peripheral surface of the cooling body 3 as shown in FIG.

  The high-purity metal lump 6 on the peripheral surface of the rotary cooling body 3 is pulled up together with the cooling body 3 from the molten metal 2 after a certain period of time, and is scraped off and recovered from the cooling body 3. After that, the cooling body 3 is again crushed in the molten metal 2 in the molten metal holding furnace 1 and used for metal refining. This process is repeated and metal purification is continuously performed.

  In this step, the cooling body after scraping off the purified metal has a temperature clearly lower than the temperature of the molten metal. Therefore, the molten metal 2 that is in contact with the same surface of the cooling body 3 when dipped in the molten metal 2 abruptly solidifies due to thermal diffusion to the cooling body 3. At this time, the solidified metal is rapidly cooled, so the adhesion to the cooling body 3 is poor, and therefore, the refined metal lump 6 often peels off during the purification, and in this case, it is obtained after a certain period of purification. The refined lump weight is reduced. In this way, the purification process becomes very unstable, resulting in poor production efficiency.

  Therefore, in the present invention, in order to prevent the metal refined lump 6 having poor adhesion with the cooling body 3 crystallized immediately after the cooling body 3 from being immersed from the cooling body 3, The centrifugal force acting on the metal refined lump 6 is reduced by intentionally reducing the peripheral speed. In other words, the average peripheral speed of the cooling body at the initial stage of purification is set to be smaller than the average peripheral speed thereafter, and the maximum peripheral speed of the cooling body at the initial stage of purification is set not to exceed the average peripheral speed thereafter. Is to do.

  According to this method, the purified metal crystallized immediately after the immersion of the cooling body 3 is prevented from peeling because the average peripheral speed of the rotating cooling body 3 is low and the maximum peripheral speed is small, and thereafter the peripheral speed is reduced. As shown in FIG. 1 (c), the crystallized metal refined mass 6 grows without peeling and can be stably refined, and the finally obtained refined metal weight increases.

  Here, the initial stage of purification refers to, for example, the time from the start of purification to the total purification time × 0.1. Even if the average peripheral speed is reduced to a time exceeding the total purification time x 0.1, not only does the effect of preventing the peeling of the purified metal saturate, but also the productivity of the purified metal that is finally obtained is increased and the weight of the purified metal is increased. There is a fear that you can not.

  Specifically, the average peripheral speed V1 of the cooling body 3 from the start of purification to the total purification time × 0.05 is set to V1 ≦ V3 × 0.9 with respect to the average peripheral speed V3 thereafter, and purification is performed. In order to obtain a more reliable effect, purification is performed at the average peripheral speed V1 of the cooling body 3 from the start of purification until the total purification time × 0.1, and thereafter the average peripheral speed V3 (however, V1 ≦ V3 × 0.9).

  Further, if the maximum peripheral speed V2 of the cooling body 3 in the initial stage of purification is equal to or higher than the average peripheral speed thereafter, the average peripheral speed V1 of the cooling body 3 in the initial stage of purification is set smaller than the average peripheral speed V3 thereafter. However, since the refined metal may be peeled off due to the centrifugal force generated by the maximum peripheral speed, it is necessary to set the maximum peripheral speed V2 of the cooling body at the initial stage of purification not to exceed the average peripheral speed V3 thereafter. is there. Preferably, it is desirable to set the maximum peripheral speed V2 of the cooling body 3 at the initial stage of purification to 0.95 times or less of the average peripheral speed V3 thereafter.

  In this metal refining apparatus, the molten metal holding furnace 1 may be a single one, or a plurality of holding furnaces may be connected to each other by a connecting rod. In the case of a single substance, when the purification is repeated, the impurity concentration of the molten metal increases, so that the purity of the purified metal is deteriorated. Therefore, it is better to replace the molten metal regularly. When they are connected to each other by a connecting rod, if a new molten metal is poured from one end, the molten metal 2 flows out to the adjacent molten metal holding furnace 1 and the high concentration molten metal stays in the molten metal holding furnace 1 as it is. Therefore, it is not necessary to replace the molten metal. Further, the molten metal that has flowed out of the most downstream molten metal holding furnace 1 is discharged because it has a concentration that is not suitable for purification.

  The rotary cooling body 3 is preferably made of graphite or ceramics, but is not limited thereto. Since the rotary cooling body 3 also becomes high temperature due to contact with the high-temperature molten metal, it may be any metal as long as it does not melt at this high temperature and does not cause an extreme decrease in strength.

  The refrigerant for cooling the rotary cooling body 3 is not particularly limited, and nitriding gas, carbon dioxide gas, argon gas, compressed air, and the like can be used, but compressed air is recommended in terms of cost.

  The refined metal may include metals such as aluminum, silicon, magnesium, lead, and zinc containing eutectic impurities. In particular, when aluminum is purified, if impurities that generate peritectic crystals with aluminum are contained, boron addition and stirring are preferably performed. By adding boron and stirring, boron reacts with peritectic impurities such as Ti, V, and Zr contained in the molten metal, and insoluble borides such as TiB2, VB2, and ZrB2 are generated. Excess boron is removed as eutectic impurities. The boride is separated from the cooling body 3 by the centrifugal force generated by the rotation of the cooling body 3 in the molten metal holding furnace 1 and is not contained in the aluminum crystallized on the peripheral surface of the cooling body 3. In addition, when the molten metal holding furnaces 1 are connected to each other by connecting rods, it is preferable to arrange a boron addition crucible in the uppermost stream. Boron is generally supplied into the molten metal as a master alloy rod added to aluminum.

  The metal refine | purified by the above can exhibit the outstanding characteristic and function by using for various processes and uses. For example, a refined metal may be used for casting to produce a cast product, or the cast product may be rolled and used as various metal plates or metal foils. Moreover, you may use this metal foil as an electrode material of an aluminum electrolytic capacitor, for example.

[Example]
A molten aluminum containing mainly Fe: 500 ppm and Si: 400 ppm as impurities is placed in a refining holding furnace, and the power of the refining furnace heater is adjusted and maintained at a temperature of 665 ° C. Then, a tapered rotating cooling body with an outer diameter of 150 mm at the upper end adjusted for temperature is immersed in the molten metal, and purified aluminum is crystallized on the peripheral surface of the rotating cooling body for 7 minutes while rotating at the speed shown below. I let you. The rotating cooling body was cooled by directly applying compressed air.
(1) The number of rotations of the cooling body is from the start of purification to the total purification time × 0.05, average peripheral speed V1: 2.7 m / sec, maximum peripheral speed V2: 2.9 m / sec, and thereafter peripheral speed 3.1 m / Sec (therefore, the average peripheral speed V3 was also set to 3.1 m / sec). As a result of performing the purification experiment five times, the weight of the purified lump was 6.1 kg on average. Further, the number of peelings that occurred during the purification was investigated with the passage of time after the start of purification, as shown in Table 1, and the rate of peeling occurred within the total purification time × 0.05 from the start of purification.

(2) The number of rotations of the cooling body was changed from the start of purification to the total purification time × 0.1, average peripheral speed V1: 2.7 m / sec, maximum peripheral speed V2: 2.9 m / sec, and thereafter peripheral speed 3.1 m. / Sec (therefore, the average peripheral speed V3 was also set to 3.1 m / sec). As a result of conducting the purification experiment five times, the weight of the purified lump was 6.14 kg on average. Further, the number of peelings occurred during the purification was investigated with the passage of time after the start of purification, as shown in Table 2, and the rate of peeling occurred within the total purification time × 0.1 from the start of purification.

[Conventional example]
A molten aluminum containing mainly Fe: 500 ppm and Si: 400 ppm as impurities is placed in a refining holding furnace, and the power of the refining furnace heater is adjusted and maintained at a temperature of 665 ° C. After that, a tapered cooling cooling body having an outer diameter of 150 mm whose temperature is adjusted at the upper end is crushed in the molten metal and rotated at a constant speed of 3.1 m / sec. Purified aluminum was crystallized. The rotating cooling body was cooled by directly applying compressed air.

  As a result of conducting the purification experiment five times, the weight of the purified lump was 6.0 kg on average. Further, the number of peelings that occurred during purification was examined with the passage of time after the start of purification, as shown in Table 3, and peeling occurred in all purifications from the start of purification to the total purification time × 0.05.

It is a figure for demonstrating the schematic structure of the metal purification apparatus which concerns on one Embodiment of this invention, and the metal purification method using the same.

Explanation of symbols

1 Molten metal holding furnace 2 Molten metal (molten metal)
3 Cooling body 4 Rotation drive device 5 Control unit 6 Refined metal block

Claims (8)

In a metal purification method in which a cooling body is immersed in a molten metal to be purified, and a high-purity metal is crystallized on the surface of the cooling body while rotating the cooling body.
When the cooling body is immersed in the molten metal, the purification starts, and when the cooling body is pulled from the molten metal to the total purification time, the total purification time from the start of purification × 0 Set the average peripheral speed of the cooling body at the initial stage of purification up to 1 smaller than the average peripheral speed after that, and set the maximum peripheral speed of the cooling body at the initial stage of purification not to exceed the average peripheral speed thereafter. A metal purification method characterized by performing purification. 2. The metal refining according to claim 1, wherein the relationship between the average peripheral speed V1 of the cooling body from the start of refining to the total refining time × 0.05 and the average peripheral speed V3 thereafter is set to V1 ≦ V3 × 0.9. Method. The relationship between the average peripheral speed V1 of the cooling body from the start of purification to the total purification time x 0.1 and the average peripheral speed V3 thereafter is set to V1 ≤ V3 x 0.9. Metal purification method. The metal purification method according to claim 1, wherein the metal to be purified is aluminum. A furnace body containing the molten metal to be refined;
A cooling body immersed in the molten metal contained in the furnace body;
A rotation drive device for rotating the cooling body;
When the cooling body is immersed in the molten metal, the purification starts, and when the cooling body is pulled from the molten metal to the total purification time, the total purification time from the start of purification × 0 .1 so that the average peripheral speed of the cooling body in the initial stage of purification becomes smaller than the average peripheral speed thereafter, and the maximum peripheral speed of the cooling body in the initial stage of purification does not exceed the average peripheral speed thereafter. Control means for controlling the rotational speed of the cooling body by the rotary drive device;
A metal refining apparatus characterized by comprising: The control means is a rotary drive device so that the relationship between the average peripheral speed V1 of the cooling body from the start of purification to the total purification time × 0.05 and the average peripheral speed V3 thereafter is V1 ≦ V3 × 0.9. The metal refining device according to claim 5, wherein the rotation speed of the cooling body is controlled. The control means is a rotary drive device so that the relationship between the average peripheral speed V1 of the cooling body from the start of purification to the total purification time × 0.1 and the average peripheral speed V3 thereafter is V1 ≦ V3 × 0.9. The metal refining device according to claim 5, wherein the rotational speed of the cooling body is controlled by the gas generator. A purified metal purified by the method according to claim 1.

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