JP5128167B2 - Metal refining method, metal refining device, refined metal, casting, metal product and electrolytic capacitor - Google Patents

Description

  The present invention utilizes the principle of the segregation solidification method to reduce the content of eutectic impurities from metals such as aluminum, silicon, magnesium, lead, zinc and the like containing eutectic impurities, compared to the original metal, and high purity. The present invention relates to a metal refining method and a metal refining apparatus for producing the metal, and further relates to a refined metal, a cast product, a metal product and an electrolytic capacitor purified by the metal refining method.

As a metal purification method, there are roughly classified an electrolytic method and a segregation solidification method. Although the electrolytic method can be highly refined, there is a disadvantage that a large amount of electric power is required and the cost is increased. On the other hand, the segregation solidification method is a purification method that applies the solute distribution law when the molten metal solidifies, and is an excellent production method in terms of cost because it can be purified with a simple apparatus.
As one of the segregation and solidification methods, a rotating cooling body is immersed in a molten metal containing eutectic impurities placed in a refining molten metal holding furnace, and the cooling body is rotated while supplying a coolant to the rotating cooling body. A method of crystallizing a purified metal with high purity on the peripheral surface is known (for example, see Patent Documents 1 and 2).
Japanese Patent Publication No.61-3385 Japanese Examined Patent Publication No. 3-65415

  By the way, in this refining method, since the rotary cooling body is immersed and rotated in the molten metal, the molten metal may be scattered from the inside of the refining molten metal holding crucible to the outside. Molten metal is generally very hot. Such scattering of high-temperature objects to the outside of the crucible causes a problem that safety is lowered. In addition, the molten metal is scattered outside the holding crucible, resulting in a problem that the yield is reduced.

As a technique for preventing molten metal scattering outside the crucible, a technique for preventing molten metal scattering and heat radiation prevention is installed above the molten liquid surface in the crucible (see, for example, Patent Document 3) or from the molten liquid surface during refining. There exists a technique of installing a molten metal scattering prevention tool on the upper part (see, for example, Patent Document 4).
JP-A-9-188512 Japanese Patent Laid-Open No. 5-26584

However, when the techniques disclosed in Patent Documents 3 and 4 are applied, the scattering of molten metal to the outside is reduced, and although the effect of improving safety and the effect of suppressing the decrease in yield are obtained, the effect is not sufficient. Absent. In addition, these techniques are techniques for preventing molten metal scattering by installing additional parts, and there is a problem that the equipment cost increases due to an increase in the number of parts.
The present invention has been made in view of the above circumstances, and realizes improvement of safety and prevention of yield reduction by suppressing the scattering of molten metal to the outside of the crucible without increasing the number of parts. An object of the present invention is to provide a metal refining method, a metal refining apparatus, a refining metal, a cast product, a metal product, and an electrolytic capacitor.

In order to achieve the above object, the present invention provides the following means.
(1) A molten aluminum holding crucible, a heating means for heating the molten aluminum in the molten aluminum holding crucible, and an aluminum refining apparatus equipped with a rotatable inverted frustoconical rotary cooling body are accommodated in the holding crucible. After immersing the rotating cooling body in the molten aluminum and rotating the rotating cooling body, crystallizing high purity aluminum on the rotating cooling body, and then purifying the purified aluminum crystallized on the rotating cooling body with a molten aluminum holding crucible a recovery to that of aluminum purification methods taken from the depth of the holding crucible: H, the height of the molten aluminum from the crucible bottom: h, the crucible opening inner diameter: when the d, H, h, the relationship d aluminum purification process but which is characterized in that satisfies the condition 0.55 ≦ (H-h) / d ≦ 1.4.
(2) A molten aluminum holding crucible, a heating means for heating the molten aluminum in the molten aluminum holding crucible, and a rotating cooling body having a rotatable inverted frustoconical shape, and contained in the molten aluminum accommodated in the holding crucible While purifying the rotating cooling body and rotating the rotating cooling body, high purity aluminum is crystallized on the rotating cooling body, and then the purified aluminum crystallized on the rotating cooling body is taken out from the molten aluminum holding crucible and recovered. When the depth of the holding crucible is H, the height of molten aluminum from the bottom of the crucible is h, and the inner diameter of the crucible opening is d, the relationship between H, h, and d is 0.55 ≦ (H -H) An aluminum purifier characterized by satisfying the condition of d / 1.4.
(3) Purified aluminum purified by the method described in item 1 above.
(4) A casting manufactured from the refined aluminum described in item 3 above.
(5) An aluminum product comprising a plate or foil obtained by rolling the cast product according to item 4 above.
(6) An electrolytic capacitor in which the aluminum product according to item 5 is used as an electrode material.

According to the invention described in the preceding item (1), it is possible to suppress the scattering of molten aluminum to the outside of the crucible caused by the rotation of the rotary cooling body, and it is possible to improve safety. Moreover, since scattering of molten aluminum to the outside of the crucible is suppressed, loss due to the outflow of molten aluminum is suppressed, and the yield is improved.

In addition, it is possible to prevent the crucible from being damaged due to low-temperature oxidation due to the increased weight of the crucible.

According to the invention described in the preceding item ( 2 ), it is possible to provide an aluminum refining device that can suppress the scattering of molten aluminum to the outside of the crucible caused by the rotation of the rotating cooling body and suppress the loss due to the outflow of molten aluminum .

According to the invention as described in the preceding paragraph (3) was purified while suppressing loss due to outflow of scattering and molten aluminum into the crucible out of the molten aluminum, can no high purity purification aluminum.

According to the invention as described in the preceding paragraph (4), purified while suppressing loss due to outflow of scattering and molten aluminum into the crucible out of the molten aluminum, can no high purity casting.

According to the invention as described in the preceding paragraph (5), which is purified while suppressing loss due to outflow of scattering and molten aluminum into the crucible out of the molten aluminum, can no high purity rolled aluminum products.

According to the invention as described in the preceding paragraph (6) was purified while suppressing loss due to outflow of scattering and molten aluminum into the crucible out of the molten aluminum, the electrode material made of high purity rolled aluminum was used electrolytic It can be a capacitor.

  An embodiment of the present invention will be described below.

  A metal refining apparatus according to an embodiment of the present invention is shown in FIG.

  This metal refining apparatus is provided with a melting furnace 1 having an open top, and a low and low cylindrical holding crucible 2 for holding molten metal is disposed in the melting furnace. A rotary cooling device 3 is provided above the opening of the molten metal holding crucible 2. The rotary cooling device 3 includes a rotatable vertical rotary shaft 31 and an inverted frustoconical rotary cooling body 32 fixed to the lower end of the rotary shaft 31.

  The rotating shaft 31 is made of a heat resistant material, and a flange 31 a is integrally formed at the lower end of the rotating shaft 31. The rotating cooling body 32 has an upper end detachably attached to the flange 31 a at the lower end of the rotating shaft 31, and a portion other than the upper end portion of the rotating cooling body 32 is in the molten metal 4 held by the crucible 2. The immersed portion becomes the purified metal crystallization portion of the rotary cooling body 32. The rotary cooling device 3 is driven up and down by appropriate driving means (not shown) and is driven to rotate.

  A hollow space 32 a is formed inside the rotary cooling body 32, and this space 32 a communicates with a refrigerant supply pipe 33 and a refrigerant discharge pipe 34 that penetrate the rotary shaft 31 in the vertical direction. The refrigerant supplied by the refrigerant supply device 35 is supplied to the internal space 32a of the rotary cooling body 32 through the refrigerant supply pipe 33, and then discharged through the refrigerant discharge pipe 34. It can be cooled while rotating.

  The melting furnace 1 is formed of a refractory, and a heater 5 as a heating means is attached to the inner peripheral surface of the melting furnace 1.

The molten metal holding crucible 2 is formed of a material such as graphite that hardly reacts with the metal and does not contaminate the molten metal, and is made of a refractory placed on the bottom wall of the melting furnace 1. 6 and placed in the melting furnace 1.
As shown in FIG. 2, the holding crucible 2 has a crucible depth of H, a height of the molten metal 4 from the bottom of the crucible: h, and an inner diameter of the crucible opening: d. The shape satisfies the condition of 55 ≦ (H−h) / d.

  Here, the reasons for limiting the shape are as follows.

  First, when the crucible depth of the holding crucible 2 is H, the height of the molten metal 4 from the bottom of the crucible is h, and the inner diameter of the crucible opening is d is 0.55> (Hh) / d, the crucible 2 goes outside. It is difficult to sufficiently suppress the molten metal scattering, and it is difficult to obtain desired effects such as improvement in safety and improvement in yield. For this reason, it is necessary to satisfy the condition of 0.55 ≦ (H−h) / d. In particular, 0.6 ≦ (H−h) / d is preferable.

  In addition, when H, h, d is (H−h) / d> 1.4, the crucible 2 may be damaged due to low-temperature oxidation due to its own weight, and the molten metal 4 may be used as a holding container. It can be difficult to play a role. In addition, the amount of heat released from the crucible to the atmosphere increases by increasing the surface area of the crucible 2 that comes into contact with the outside air. In order to keep the contained metal in a molten state, it is necessary to supply a large amount of heat sufficient to compensate for heat dissipation, but such a large amount of heat must be supplied in a limited space. It can be difficult. Therefore, it is preferable to set the shape to satisfy the condition of (Hh) /d≦1.4, and it is particularly preferable to set (Hh) /d≦1.3.

  The inner bottom portion of the crucible 2 is not limited to a flat surface, and may be formed in an arc shape that bulges downward. In this case, the crucible depth H and the height of the molten metal from the crucible bottom. h refers to the distance from the deepest part.

  The metal purification method using the metal purification apparatus is performed as follows.

  A crude metal lump to be refined is stored in advance in the crucible 2 and heated by a heater 5 to form a molten metal 4, which is heated and held at a temperature exceeding the solidification temperature by the heater 5. The molten metal 4 may be accommodated in the crucible 2 after being separately melted. Next, while supplying the refrigerant to the internal space 32a of the rotary cooling body through the refrigerant supply pipe 33, the rotary cooling body 32 is rotated via the rotary shaft 31 by a driving means (not shown) as shown in FIG. Then, it is lowered and immersed in the molten metal 4. The order of supplying the coolant to the rotating cooling body 32, rotating the rotating cooling body 32, and immersing the cooling body 32 in the molten metal 4 is not limited to the above, and the rotating cooling body 32 is melted. There is no particular problem even if the rotary cooling body 32 is rotated after being immersed in the metal 4 and the refrigerant is supplied thereafter.

  From the effect of segregation solidification and the effect that the impurities in the impurity concentrated layer are dispersed throughout the liquid phase by the relative speed between the rotating cooling body 32 and the molten metal 4, as shown in FIG. In the purified metal crystallization part of the body 32, high-purity metal crystallizes, and a purified high-purity metal lump 7 is formed. As shown in FIG. 3C, the formed high-purity metal lump 7 is pulled up together with the rotary cooling body 32, scraped off by the scraping device 8, and then collected. Thereafter, as shown in FIG. 3 (d), the rotary cooling body 3 is heated by the heating device 9 so as to reach a predetermined temperature, and is then immersed again in the molten metal 4 in the holding crucible 2, and similarly. Used for metal purification. This process is repeated and metal purification is performed continuously.

  In this metal refining device, the holding crucibles 2 may be separated or 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 4 increases, so that the purity of the purified metal is deteriorated. Therefore, it is necessary to replace the molten metal 4 periodically. When they are connected to each other by a connecting rod, if a new molten metal 4 is poured from one end, the molten metal flows out to the adjacent holding crucible 2 and the molten metal 4 is not convected to the crucible 2 as it is. There is no need to replace 4. The molten metal 4 flowing out from the most downstream holding crucible 2 has a concentration that is not suitable for refining and is discharged.

  The rotary cooling body 32 is preferably made of graphite or ceramics, but is not limited thereto. Since the rotary cooling body also becomes high temperature in contact with the high-temperature molten metal 4, it may be any metal as long as it does not melt at this high temperature and does not extremely decrease in strength, and may be made of metal. Further, the temperature adjustment of the rotary cooling body 32 may be performed only at a location where it contacts the molten metal 4. A gas burner, an induction heating device, or the like can be used in place of the heater 5, but the type is not particularly limited as long as the temperature can be raised to a predetermined temperature. Although depending on the purification conditions, if the temperature of the rotary cooling body 32 is prevented from dropping until the refined metal is pulled up, scraped off, and refined, the heating process by the heating device 9 is not particularly required. The refrigerant for cooling the rotary cooling body is not particularly limited, and nitrogen gas, carbon dioxide gas, argon gas, compressed air, and the like can be used, and compressed air can be recommended from the viewpoint of cost.

When purifying aluminum, if impurities containing aluminum and peritectic crystals are contained, boron is added and stirred. The added boron reacts with peritectic impurities such as Ti, V, and Zr contained in the molten metal to produce insoluble borides such as TiB ₂ , VB ₂ , and ZrB ₂ . Excess boron is removed as eutectic impurities. The boride is not contained in the aluminum crystallized on the peripheral surface of the cooling body by being separated from the cooling body by the centrifugal force generated by the rotation of the cooling body in the crucible. Further, when the holding crucibles 2 are connected to each other by a connecting rod, it is preferable to arrange a boron addition crucible at the most upstream part. Boron is generally supplied into the molten metal as a master alloy rod added to aluminum.

  Since the metal refine | purified by the above is high purity, the outstanding characteristic and function can be exhibited by using it 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 plate and metal foil as an electrode material of an aluminum electrolytic capacitor, for example.

Hereinafter, specific examples will be described together with comparative examples.
Examples 1-4
The holding crucible 2 depth: H, crucible opening inner diameter: d is set to various values as shown in Table 1, and molten aluminum (molten metal) is placed on the crucible bottom from the crucible bottom. S: Housed so that h is as shown in Table 1. And the rotary cooling body 32 which set the temperature the same was immersed in the molten metal, and refinement | purification was implemented by rotating the rotary cooling body 32 at the same speed with each material.

  As a result, in Examples 1 to 3 of Table 1, as indicated by ◎ in the item of “spatter of molten metal”, scattering of molten aluminum to the outside of the crucible caused by the rotation of the rotating cooling body 32 is not observed. In Example 4 of 1, as indicated by a circle in the item “spatter of molten metal”, the molten aluminum is hardly scattered outside the crucible due to the rotation of the rotating cooling body 32. It was confirmed that purification was possible with high safety and reduced yield reduction.

Comparative Examples 1-4
The same conditions as in Examples 1 to 4 except that the depth of the holding crucible 2 is H, the height of the molten metal 4 from the bottom of the crucible 4 is h, and the inside diameter of the crucible opening is d as shown in Table 1. The aluminum was purified at

  As a result, as shown by “x” in the item “spatter of molten metal” in Table 1, it was observed that the molten aluminum spattered to the outside of the crucible generated by the rotation of the rotary cooling body 32.

  From the above results, according to the method of the present invention, it can be confirmed that it is possible to improve safety and prevent yield reduction by suppressing the scattering of molten metal to the outside of the crucible without increasing the number of parts. It was.

It is a vertical sectional view of a refining device concerning one embodiment of this invention. It is explanatory drawing of the symbol which shows a crucible dimension. It is a figure for demonstrating the metal purification method using the metal purification apparatus of FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Melting furnace 2 Holding crucible 3 Rotating cooling device 31 Rotating shaft 32 Rotating cooling body 33 Refrigerant supply pipe 34 Refrigerant discharge pipe 4 Molten metal 5 Heater 6 Mounting table 7 Metal lump

Claims (6)

A molten aluminum holding crucible, a heating means for heating the molten aluminum in the molten aluminum holding crucible, an aluminum refining apparatus provided with a rotating cooling body rotatable inverted truncated cone shape with,
The rotary cooling body is immersed in the molten aluminum accommodated in the holding crucible, and while the rotary cooling body is rotated, high-purity aluminum is crystallized on the rotary cooling body, and then purification is performed on the rotary cooling body. aluminum and an aluminum refining how to recover removed from the molten aluminum holding crucible,
When the holding crucible depth is H, the molten aluminum height from the crucible bottom is h, and the crucible opening inner diameter is d, the relationship between H, h, and d is 0.55 ≦ (H−h) / d. An aluminum refining method characterized by satisfying a condition of ≦ 1.4 . A molten aluminum holding crucible, a heating means for heating the molten aluminum in the molten aluminum holding crucible, and a rotating cooling body having a rotatable inverted frustoconical shape, the rotating cooling body in the molten aluminum accommodated in the holding crucible This is an aluminum refining device that crystallizes high-purity aluminum on the rotating cooling body while rotating the rotating cooling body, and then takes out and recovers the purified aluminum crystallized on the rotating cooling body from the molten aluminum holding crucible. And
When the holding crucible depth is H, the molten aluminum height from the crucible bottom is h, and the crucible opening inner diameter is d, the relationship between H, h, and d is 0.55 ≦ (H−h) / d. An aluminum refining apparatus characterized by satisfying a condition of ≦ 1.4. The refined aluminum refine | purified by the method of Claim 1. A casting manufactured from the purified aluminum according to claim 3. An aluminum product comprising a plate or foil obtained by rolling the cast product according to claim 4. An electrolytic capacitor in which the aluminum product according to claim 5 is used as an electrode material.

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