JP5074762B2 - Metal purification method and apparatus, refined metal, casting, metal product and electrolytic capacitor - Google Patents

Description

  The present invention relates to a metal refining method and apparatus, and more specifically, by using the principle of segregation solidification method, the content of eutectic impurities is determined from metals such as aluminum, silicon, magnesium, lead, and zinc containing eutectic impurities. The present invention relates to a method and an apparatus for producing a high-purity metal that is smaller 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.

  Conventionally, as a purification method for high-purity metals, a cooling body is immersed in a molten metal containing eutectic impurities placed in a refined molten metal holding container, and the cooling body is rotated while supplying a cooling fluid to the cooling body. A method of crystallizing a purified metal having a purity higher than that of a molten metal around the periphery is known (for example, Patent Document 1).

  In the method described in Patent Document 1, after the metal to be purified is dissolved into a molten metal, the molten metal is always heated and maintained at a temperature exceeding its solidification temperature. The cooling body is immersed, and at that time, the surface temperature of the cooling body is maintained to be equal to or lower than the solidification temperature of the molten metal, and the relative speed between the outer circumferential surface of the cooling body and the molten metal is increased to increase the molten metal on the outer circumferential surface of the cooling body. This means that a higher-purity metal lump is crystallized and adhered.

  This method uses the principle of segregation in which, when the molten metal is held at a temperature in the region between the liquidus and solidus, it is separated into a higher purity solid phase and a liquid phase with more impurities. .

  First, a solid phase with few impurities is generated on the surface of the cooling body, and a liquid phase with many impurities is discharged to a solidification interface between the solid phase and the molten metal to form a so-called impurity concentrated layer. The metal lump that adheres and grows on the outer peripheral surface of the cooling body diffuses impurities outward by making the progress speed of the solidification interface slower than the diffusion speed to the outside of the impurity concentrated layer, and / or the impurity concentration. By forming the layer into a thin layer by dispersing the formation layer according to the flow rate of the liquid phase, the layer is obtained with less impurities.

  In recent years, higher purity metals are required for some applications.

  For example, in the case of aluminum, the raw material aluminum used for the electrode foil of the electrolytic aluminum capacitor is required to have a high purity of 99.9%. Further, in recent years, the demand for high-voltage electrolytic aluminum capacitors has increased, and as the aluminum foil necessary for such high-capacity aluminum capacitors, a higher purity of 99.99% is required.

  In order to obtain a higher-purity metal mass by a conventional purification method, the purification may be performed a plurality of times. Specifically, once purified products are collected and re-dissolved, the re-dissolved molten metal is purified, and if this is repeated, a high-purity metal lump can be obtained by the number of repetitions. However, this method has a great number of steps, and there is a high possibility that impurities are mixed from the production line during that time. In addition, by re-dissolving many times, the necessary cost and necessary energy increase, and the production efficiency is lowered.

  Therefore, it is desirable to further improve the purification efficiency in the purification process itself, rather than increasing the number of purifications.

  In the conventional method, when the cooling body is immersed and rotating in the molten metal, the surrounding molten metal is not stopped, and is rotating in the same direction as the direction of rotation of the cooling body. Although it is rotating at a peripheral speed that is slower than the rotational speed of the cooling body, the fact that the molten metal is rotating in the same direction as the cooling body means that the difference in speed between the molten metal and the cooling body is small, so the relative speed is rather It's getting late.

  In order to improve the purification efficiency, it is important how to increase the relative speed which is not actually increased.

As a means for further increasing the relative speed between the cooling body and the molten metal, the following method may be mentioned.
(A) The relative speed with the molten metal is increased by increasing the peripheral speed of the cooling body.
(B) In order to slow down the flow rate of the molten metal, a baffle plate is installed on the inner peripheral surface of the crucible as described in Patent Document 2 and Patent Document 3.
Japanese Patent Publication No.61-3385 Japanese Patent Laid-Open No. 61-170527 JP-A-63-89633

  However, in the method of increasing the relative speed with the molten metal by increasing the peripheral speed of the cooling body in (A) above, the point that the molten metal is rotated by the cooling body in the same direction is not solved, There is a problem that it is difficult to increase the relative speed. Also in terms of equipment, the device for rotating the cooling body is larger than the conventional device because the rotation speed has to be further increased, which is not practical. In addition, when the peripheral speed of the cooling body increases, the peripheral speed of the molten metal also increases, thereby increasing the level difference of the liquid level and increasing the fluctuation of the liquid level. There's a problem. Furthermore, since the centrifugal force generated on the outer peripheral surface of the cooling body increases and the metal lump attached to the outer peripheral surface of the cooling body is easily detached, the resulting metal lump is reduced, which is not preferable in terms of production efficiency.

  Further, in the method of installing the baffle plate on the inner peripheral surface of the crucible (B), although the baffle plate has an effect of suppressing the flow rate of the entire molten metal or causing turbulence, the range of the effect is within the crucible It will be restricted to the outer peripheral part of the inner side range by the length of a baffle plate from a surrounding surface. In order to exert the effect to the vicinity of the outer peripheral surface of the cooling body, it is necessary to extend the baffle plate to the vicinity of the outer peripheral surface of the cooling body, but in this state, the metal block adhered and grown on the outer peripheral surface of the cooling body is in contact with the baffle plate. In addition, there is a risk that the baffle will be damaged. In addition, in order to obtain a crucible having a baffle plate on the inner peripheral surface of the crucible, there is a method of adhering the baffle plate as a separate part to the inner peripheral surface of the crucible, or a method of manufacturing a crucible having a baffle plate from the beginning. However, it takes time and effort for both production and maintenance.

  The present invention has been made in view of such circumstances, and it is possible to safely and efficiently use high-purity metal without increasing the peripheral speed of the cooling body or providing a baffle plate on the inner peripheral surface of the crucible. It is an object of the present invention to provide a metal purification method and apparatus, a refined metal, a cast product, a metal product, and an electrolytic capacitor that can be refined well.

The above problem is solved by the following means.
(1) In a metal refining method in which a cooling body is immersed in a molten metal to be purified contained in a crucible and high purity metal is crystallized on the surface of the cooling body while rotating the cooling body, presence of molten metal in the crucible The metal is characterized in that the refining is performed by setting the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body to a half or less of the longest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body. Purification method.
(2) The metal refining method according to item 1, wherein the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body is 10 mm or more.
(3) The ratio d / D of the outer dimension d of the cooling body in the horizontal plane including the D to the maximum inner dimension D of the opening of the crucible is 0.2 or more in the portion where the molten metal exists in the crucible. 3. The metal refining method according to 1 or 2 above.
(4) The metal refining method according to any one of the preceding items 1 to 3, wherein the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body is changed with the formation of the refined lump attached to the cooling body.
(5) The metal refining method according to any one of items 1 to 4, wherein the molten metal is aluminum.
(6) A crucible containing the molten metal to be purified, and a rotatable cooling body immersed in the molten metal accommodated in the crucible, wherein the inside of the crucible A metal refining device, wherein the shortest distance between the peripheral surface and the outer peripheral surface of the cooling body is set to be less than or equal to one half of the longest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body.
(7) The metal refining device according to item 6 above, wherein the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body is set to 10 mm or more.
(8) The ratio d / D of the outer dimension d of the cooling body in the horizontal plane including the D to the maximum inner dimension D of the opening of the crucible is 0.2 or more in the molten metal existing portion in the crucible. 8. The metal refining device according to 6 or 7 above.
(9) The metal refining according to any one of the preceding items 6 to 8, wherein the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body is changed with the formation of the refining lump attached to the cooling body. apparatus.
(10) A purified metal purified by the method according to any one of 1 to 5 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 (1) above, the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body in the portion where the molten metal exists in the crucible is the longest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body. Therefore, when the molten metal flows from a location where the distance between the inner peripheral surface of the cooling body and the crucible is narrow to a wide location, the width increases, In addition to the circumferential direction, the degree of freedom in the radial direction increases. When the centrifugal force by the cooling body extends in the radial direction, the direction of the molten metal flow changes, and even when the flow size is the same, the radial component of the molten metal flow velocity is generated. The direction component becomes smaller. As a result, the relative speed of the outer peripheral surface of the cooling body with respect to the molten metal can be increased, and the purification efficiency can be improved. In addition, since the molten metal flow is also generated in the radial direction component, the diffusion to the outside of the impurity concentrated layer formed at the solidification interface of the metal lump that adheres to and grows on the surface of the cooling body is promoted, and the higher purity is achieved. The effect that a metal lump is obtained also occurs.

  According to the invention described in (2) above, since the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body is 10 mm or more, the distance between the outer peripheral surface of the cooling body and the inner peripheral surface of the crucible is reduced. It is possible to avoid the risk that the metal lump contacts the inner peripheral surface of the crucible.

  According to the invention described in item (3) above, the ratio d of the outer dimension d of the cooling body in the horizontal plane including D to the maximum inner dimension D of the opening of the crucible in the molten metal existing portion in the crucible. Since / D is 0.2 or more, the effect of the invention of the preceding item (1) due to the difference in the flow velocity between the place where the distance between the outer peripheral surface of the cooling body and the inner peripheral surface of the crucible is narrow and wide is effectively exhibited. Can be made.

  According to the invention described in the preceding item (4), the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body is changed with the formation of the purified lump attached to the cooling body. The shortest distance from the inner peripheral surface of the crucible is narrowed by the metal lump that grows by adhering to the outer peripheral surface of the cooling body, and the concern that it finally comes into contact with the inner peripheral surface of the crucible can be solved.

  According to the invention described in item (5) above, high-purity aluminum can be purified.

  According to the invention described in the preceding item (6), the relative speed of the outer peripheral surface of the cooling body with respect to the molten metal can be increased, and a production apparatus capable of improving the purification efficiency can be obtained.

  According to the invention described in item (7) above, it is possible to avoid the risk that the distance between the outer peripheral surface of the cooling body and the inner peripheral surface of the crucible becomes too small and the metal lump comes into contact with the inner peripheral surface of the crucible.

  According to the invention described in the preceding item (8), the effect of the invention of the preceding item (6) due to a difference in flow velocity between a narrow place and a wide place between the outer peripheral surface of the cooling body and the inner peripheral surface of the crucible is effectively exhibited. Purification equipment.

  According to the invention described in the preceding item (9), the shortest distance between the outer peripheral surface of the cooling body and the inner peripheral surface of the crucible is narrowed by the metal lump that grows attached to the outer peripheral surface of the cooling body, and finally Can eliminate the concern of contact with the inner surface of the crucible.

  According to the invention described in the above item (10), it can be a purified metal with high purity.

  According to the invention described in item (11) above, a cast product with high purity can be obtained.

  According to the invention described in item (12), a rolled metal product with high purity can be obtained.

  According to the invention described in the preceding item (13), an electrolytic capacitor using an electrode material made of high-purity rolled metal 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 low and low cylindrical crucible, and a molten metal (also referred to as molten metal) 10 is accommodated and held inside the crucible 1. The crucible 1 is composed of a heating furnace and is heated so that the molten metal 10 has a constant temperature.

  The shape of the crucible 1 is not limited to a cylinder, but it is desirable that the inner peripheral surface be configured with a curve as much as possible. Moreover, the heating method of the furnace which comprises the crucible 1 may be an electric heating or a gas burner.

  The temperature of the molten metal 10 only needs to exceed the solidification temperature, but is preferably lower than the temperature at which no solid phase exists in the molten metal while the cooling body 2 is immersed in the molten metal 10.

  The cooling body 2 is formed in a truncated cone shape having a large diameter at the upper end side, and is installed at the lower end of the rotary shaft 3 that can move up and down. The shape of the cooling body 2 is not limited and may be a columnar shape or other shapes. The rotating shaft 3 has a tubular shape, and a space is also formed inside the cooling body 2. A refrigerant supply pipe 4 and a refrigerant discharge pipe 5 are inserted into the rotary shaft 3 so that the refrigerant is supplied from the refrigerant supply pipe 4. The supplied refrigerant is jetted into the internal space of the cooling body 2 through the refrigerant supply pipe 4, and then discharged through the refrigerant discharge pipe 5 inside the rotary shaft 3. Can be cooled from the inside. As the refrigerant, gas or liquid is used. The surface of the cooling body 2 is preferably made of a material having high thermal conductivity such as metal or graphite.

  The cooling body 2 is configured such that the rotating shaft 3 moves downward to be immersed and rotated in the molten metal. At this time, the shortest distance between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 in the portion where the molten metal 10 exists is L1, and the longest distance between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 is L2. Then, the positional relationship when the crucible 1 and the cooling body 2 are immersed is determined in advance so that L1 is less than or equal to half of L2.

  The reason for this positional relationship is as follows. That is, when the molten metal 10 flows from a location where the distance between the inner peripheral surface of the cooling body 2 and the crucible 1 is narrow to a wide location, the width increases, so that in addition to the circumferential direction of the cooling body 2, in the radial direction. The degree of freedom increases. When the centrifugal force by the cooling body 2 extends in the radial direction, the direction of the molten metal flow is changed, and even when the flow size is the same, the radial component of the molten metal flow velocity is generated. The circumferential component is reduced. As a result, the relative speed of the outer peripheral surface of the cooling body with respect to the molten metal can be increased.

  In addition, since the molten metal flow is also generated in the radial direction component, the diffusion to the outside of the impurity concentrated layer formed at the solidification interface of the metal lump that adheres and grows on the surface of the cooling body 2 is promoted, and the purity is increased. The effect that the metal lump of this is obtained also occurs.

  In the shortest distance L1 and the longest distance L2 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2, when L1 exceeds half of L2, the radial component of the melt flow velocity is small, and the outer periphery of the cooling body with respect to the melt The relative speed of the surface cannot be increased, and the effect of promoting diffusion outside the impurity concentrated layer is not sufficient. Desirably, LI / L2 ≦ 0.4 is set.

  Further, in the portion where the molten metal 10 is present, the ratio d / D of the outer diameter d of the cooling body 2 in the horizontal plane including the D to the maximum inner diameter D of the opening of the crucible 1 is 0.2 or more. desirable. If d / D is less than 0.2, the flow rate of the molten metal 10 for achieving the above-described effect of setting LI / L2 ≦ 1/2 may not increase, and the outer peripheral surface of the cooling body 2 and the crucible 1 There is a possibility that an effect due to a difference in flow velocity between a place where the distance to the inner peripheral surface is narrow and a place where the distance is wide cannot be expected. Particularly preferably, d / D ≧ 0.3 is set. However, if d / D is too large, the change in the flow velocity between the place where the distance between the outer peripheral surface of the cooling body 2 and the inner peripheral surface of the crucible 1 is short and the place where it is long becomes slow, and the flow velocity of the radial component is large. Therefore, it is preferable to set d / D ≦ 0.7 because there is a possibility that the diffusion effect to the outside of the impurity concentrated layer cannot be sufficiently exhibited. In addition, when the internal space of the crucible 1 is not circular in cross section, or when the cooling body 2 is not circular in cross section, the maximum internal dimension D of the opening of the crucible 1 and the above D in the portion where the molten metal 10 in the crucible 1 exists The ratio d / D of the outer dimension d of the cooling body 2 in the horizontal plane to be included may be set to 0.2 or more.

  Moreover, when a metal lump adheres to the outer peripheral surface of the cooling body 2 and grows, the distance between the outer peripheral surface of the cooling body 2 and the inner peripheral surface of the crucible 1 becomes too small, and the metal lump becomes an inner peripheral surface of the crucible. Therefore, it is desirable to secure a minimum distance L1 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 of 10 mm or more.

  Further, the rotation shaft 3 itself has a mechanism that can move in parallel in the horizontal plane, and the distances L1 and L2 between the outer peripheral surface of the cooling body 2 and the inner peripheral surface of the crucible 1 while the cooling body 2 is immersed. By making the operation to change the temperature little by little, the shortest distance L1 between the outer peripheral surface of the cooling body 2 and the inner peripheral surface of the crucible 1 is caused by the metal lump growing on the outer peripheral surface of the cooling body 2 It is possible to eliminate the concern that it will narrow and eventually come into contact with the inner peripheral surface of the crucible 1. The distances L1 and L2 between the outer peripheral surface of the cooling body 2 and the inner peripheral surface of the crucible 1 may be changed little by little by translating the crucible 1 instead of translating the rotating shaft 3 itself. .

  After starting the refining of the metal mass as described above, the metal mass adhering to the outer peripheral surface of the cooling body 2 is also pulled up at the same time by pulling up the cooling body 2 after a certain period of time has passed. The adhered metal mass is removed and recovered by applying mechanical force or reheating. Examples of the refined metal include metals such as aluminum, silicon, magnesium, lead, and zinc containing eutectic impurities.

  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 foil as an electrode material of an aluminum electrolytic capacitor, for example.

Example 1
First, the used refiner will be described.

  The crucible 1 is formed in a low-cylindrical shape with an inner diameter D of 400 mm. On the other hand, the cooling body 2 is made of cylindrical graphite having an outer diameter d of 150 mm, and is installed at the lower end of the rotating shaft 3 capable of moving up and down. The rotating shaft 3 is tubular, and the cooling body 2 also has a hollow portion inside. Air was used as the refrigerant. The structure is such that air is ejected through the refrigerant supply pipe 4 inserted into the rotary shaft 3 into the hollow interior of the cooling body 2 and then discharged through the refrigerant discharge pipe 5 of the rotary shaft 3. It has become.

  The cooling body 2 is configured such that the rotating shaft 3 moves downward and can be immersed and rotated in the molten aluminum 10, and the cooling body 2 is immersed for a certain period of time while being cooled by flowing air inside. An aluminum lump adheres to the outer peripheral surface of the film and grows. Then, the rotating shaft 3 is raised, the cooling body 2 with the aluminum lump attached is pulled up from the molten metal, and moved together with the rotating shaft 3 to a place where a device for scraping the aluminum lump is removed. Scrap and collect.

  Using such a purification apparatus, the aluminum metal to be purified was put in the crucible 1 and melted by electric heating to obtain a molten aluminum 10, which was kept at 665 ° C. The molten aluminum 10 at that time contained mainly 510 ppm of Fe and 180 ppm of Si as impurities.

  The cooling body 2 was heated and held in advance so that the surface temperature was 550 ° C., and then the cooling body 3 was immersed in the molten aluminum 10 in the crucible 1. At that time, the shortest distance L1 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 55 mm, and the longest distance L2 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 195 mm.

  After the cooling body 2 is immersed in the molten metal 10, the cooling body 2 is rotated at a peripheral speed = 4.7 m / sec while flowing cooling air inside the cooling body 2 at a flow rate of 2000 liters / minute. For 5 minutes. As a result, an aluminum block adhered and grown on the outer peripheral surface of the cooling body 2 was obtained. The weight of the obtained aluminum lump was 6.1 kg and contained 48 ppm Fe and 34 ppm Si as impurities. The purification efficiency is calculated by the ratio of the impurity concentration contained in the aluminum lump attached to the cooling body 2 to the impurity concentration contained in the original molten aluminum. When converted to the purification efficiency, the purification efficiency of Fe is 0.10, The purification efficiency of Si was 0.21.

(Example 2)
The aluminum metal to be purified was put in the crucible 1 and melted by electric heating to obtain a molten aluminum 10 and kept at 665 ° C. The molten aluminum 10 at that time contained mainly 500 ppm of Fe and 250 ppm of Si as impurities.

  The same apparatus as Example 1 was used for the purification apparatus. The cooling body 2 was heated and held in advance so that the surface temperature was 550 ° C., and then the cooling body 2 was immersed in the molten aluminum 10 in the crucible 1. At that time, the shortest distance L1 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 12 mm, and the longest distance L2 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 238 mm.

  After the cooling body was immersed in the molten metal, the compressed air for cooling was allowed to flow inside the cooling body at a flow rate of 2000 liters / minute and held at a peripheral speed of 4.7 m / second for 1 minute. As a result, an aluminum block adhered and grown on the outer peripheral surface of the cooling body was obtained. The weight of the obtained aluminum lump was 1.1 kg and contained 40 ppm Fe and 45 ppm Si as impurities. In terms of purification efficiency, the purification efficiency of Fe was 0.08, and the purification efficiency of Si was 0.18.

(Example 3)
The aluminum metal to be purified was placed in the crucible 1 and melted by electric heating to maintain a molten aluminum 10 at 665 ° C. The molten aluminum 10 at that time contained mainly 500 ppm of Fe and 250 ppm of Si as impurities.

  The same apparatus as Example 1 was used for the purification apparatus. The cooling body 2 was heated and held in advance so that the surface temperature was 550 ° C., and then the cooling body 2 was immersed in the molten aluminum 10 in the crucible 1. At that time, the shortest distance L1 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 33 mm, and the longest distance L2 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 217 mm.

  After the cooling body 2 is immersed in the molten metal 10, the compressed air for cooling is flowed into the cooling body 2 at a flow rate of 2000 liters / minute, and is held for 3 minutes while rotating at a peripheral speed = 4.7 m / second. did. As a result, an aluminum block adhered and grown on the outer peripheral surface of the cooling body 2 was obtained. The weight of the resulting aluminum lump was 3.4 kg and contained 47 ppm Fe and 49 ppm Si as impurities. In terms of purification efficiency, the purification efficiency of Fe was 0.09, and the purification efficiency of Si was 0.20.

Example 4
The aluminum metal to be purified was placed in the crucible 1 and melted by electric heating to maintain a molten aluminum 10 at 665 ° C. The molten aluminum 10 at that time contained mainly 500 ppm of Fe and 250 ppm of Si as impurities.

  The same apparatus as Example 1 was used for the purification apparatus. The cooling body 2 was heated and held in advance so that the surface temperature was 550 ° C., and then the cooling body 2 was immersed in the molten aluminum 10 in the crucible 1. At that time, the shortest distance L1 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 55 mm, and the longest distance L2 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 195 mm.

  After the cooling body 2 is immersed in the molten metal 10, the compressed air for cooling flows through the inside of the cooling body 2 at a flow rate of 2000 liters / minute and is held for 5 minutes while rotating at a peripheral speed of 2.7 m / second. did. As a result, an aluminum block adhered and grown on the outer peripheral surface of the cooling body 2 was obtained. The weight of the obtained aluminum lump was 6.2 kg and contained 80 ppm Fe and 60 ppm Si as impurities. In terms of purification efficiency, the purification efficiency of Fe was 0.16, and the purification efficiency of Si was 0.24.

(Example 5)
The aluminum metal to be purified was placed in the crucible 1 and melted by electric heating to maintain a molten aluminum 10 at 665 ° C. The molten aluminum 10 at that time contained mainly 500 ppm of Fe and 250 ppm of Si as impurities.

  The refining apparatus is almost the same as in Example 1, but the shortest distance between the inner week surface of the crucible 1 and the outer peripheral surface of the cooling body 2 while the cooling body 2 is immersed in the interior for a certain period of time while cooling. In order to variably control the distance L1, an apparatus to which a mechanism for moving the rotary shaft 3 in a horizontal plane was added was used. The cooling body 2 was heated and held in advance so that the surface temperature was 550 ° C., and then the cooling body 2 was immersed in the molten aluminum 10 in the crucible 1. At that time, the shortest distance L1 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 is 12 mm, the longest distance L2 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 is 238 mm, and the rotating shaft 3 And the shortest distance L1 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 is 55 mm after 5 minutes, the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 The longest distance L2 was set to be 195 mm.

  After the cooling body 2 is immersed in the molten metal 10, the compressed air for cooling flows through the inside of the cooling body 2 at a flow rate of 2000 liters / minute and is held for 5 minutes while rotating at a peripheral speed = 4.7 m / second. did. As a result, an aluminum block adhered and grown on the outer peripheral surface of the cooling body 2 was obtained. The weight of the obtained aluminum lump was 6.0 kg and contained 40 ppm Fe and 44 ppm Si as impurities. In terms of purification efficiency, the purification efficiency of Fe was 0.08, and the purification efficiency of Si was 0.18.

(Example 6)
The aluminum metal to be purified was placed in the crucible 1 and melted by electric heating to maintain a molten aluminum 10 at 665 ° C. The molten aluminum 10 at that time contained mainly 500 ppm of Fe and 250 ppm of Si as impurities.

  The same apparatus as Example 1 was used for the refinement | purification apparatus except the outer diameter of the cooling body 2 having been 250 mm. The cooling body 2 was heated and held in advance so that the surface temperature was 550 ° C., and then the cooling body 2 was immersed in the molten aluminum 10 in the crucible 1. At that time, the shortest distance L1 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 50 mm, and the longest distance L2 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 100 mm.

  After the cooling body 2 is immersed in the molten metal 10, the compressed air for cooling flows through the inside of the cooling body 2 at a flow rate of 2000 liters / minute and is held for 5 minutes while rotating at a peripheral speed = 4.7 m / second. did. As a result, an aluminum block adhered and grown on the outer peripheral surface of the cooling body 2 was obtained. The weight of the obtained aluminum lump was 9.8 kg and contained 52 ppm Fe and 55 ppm Si as impurities. In terms of purification efficiency, the purification efficiency of Fe was 0.10, and the purification efficiency of Si was 0.22.

(Example 7)
The aluminum metal to be purified was placed in the crucible 1 and melted by electric heating to maintain a molten aluminum 10 at 665 ° C. The molten aluminum 10 at that time contained mainly 500 ppm of Fe and 250 ppm of Si as impurities.

  The same apparatus as Example 1 was used for the refinement | purification apparatus except the outer diameter of the cooling body 2 having been 40 mm. The cooling body 2 was heated and held in advance so that the surface temperature was 550 ° C., and then the cooling body 2 was immersed in the molten aluminum 10 in the crucible 1. At that time, the shortest distance L1 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 80 mm, and the longest distance L2 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 280 mm.

  After the cooling body 2 is immersed in the molten metal 10, the peripheral speed is 2.5 m / sec while flowing compressed air for cooling through the cooling body 2 at a flow rate of 2000 liters / minute (for convenience of the device, it is obtained. Held for 5 minutes while rotating at the maximum peripheral speed). As a result, an aluminum block adhered and grown on the outer peripheral surface of the cooling body 2 was obtained. The weight of the obtained aluminum lump was 1.6 kg and contained 80 ppm Fe and 63 ppm Si as impurities. In terms of purification efficiency, the purification efficiency of Fe was 0.16, and the purification efficiency of Si was 0.25.

(Example 8)
The aluminum metal to be purified was placed in the crucible 1 and melted by electric heating to maintain a molten aluminum 10 at 665 ° C. The molten aluminum 10 at that time contained mainly 500 ppm of Fe and 250 ppm of Si as impurities.

  The same apparatus as Example 1 was used for the refinement | purification apparatus except the outer diameter of the cooling body 2 having been 300 mm. The cooling body 2 was heated and held in advance so that the surface temperature was 550 ° C., and then the cooling body 2 was immersed in the molten aluminum 10 in the crucible 1. At that time, the shortest distance L1 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 22 mm, and the longest distance L2 between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 78 mm.

  After immersing the cooling body 2 in the molten metal 10, hold the compressed air for cooling inside the cooling body 2 at a flow rate of 2000 liters / minute while rotating at a peripheral speed of 4.7 m / second for 1 minute. did. As a result, an aluminum block adhered and grown on the outer peripheral surface of the cooling body 2 was obtained. The weight of the obtained aluminum lump was 1.2 kg and contained 52 ppm Fe and 54 ppm Si as impurities. In terms of purification efficiency, the purification efficiency of Fe was 0.10, and the purification efficiency of Si was 0.22.

(Comparative Example 1)
The aluminum metal to be purified was placed in the crucible 1 and melted by electric heating to maintain a molten aluminum 10 at 665 ° C. The molten aluminum 10 at that time contained mainly 500 ppm of Fe and 250 ppm of Si as impurities.

  The same apparatus as Example 1 was used for the purification apparatus. The cooling body 2 was heated and held in advance so that the surface temperature was 550 ° C., and then the cooling body 2 was immersed in the molten aluminum 10 in the crucible 1. At that time, the center of the cooling body 2 was aligned with the center of the crucible 1 so that the distance between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 125 mm.

  After the cooling body 2 is immersed in the molten metal 10, the compressed air for cooling flows through the inside of the cooling body 2 at a flow rate of 2000 liters / minute and is held for 5 minutes while rotating at a peripheral speed = 4.7 m / second. did. As a result, an aluminum block adhered and grown on the outer peripheral surface of the cooling body 2 was obtained. The weight of the obtained aluminum lump was 6.3 kg and contained 70 ppm Fe and 58 ppm Si as impurities. In terms of purification efficiency, the purification efficiency of Fe was 0.14, and the purification efficiency of Si was 0.23.

(Comparative Example 2)
The aluminum metal to be purified was placed in the crucible 1 and melted by electric heating to maintain a molten aluminum 10 at 665 ° C. The molten aluminum 10 at that time contained mainly 500 ppm of Fe and 250 ppm of Si as impurities.

  The same apparatus as Example 1 was used for the purification apparatus. The cooling body 2 was heated and held in advance so that the surface temperature was 550 ° C., and then the cooling body 2 was immersed in the molten aluminum 10 in the crucible 1. At that time, the center of the cooling body was positioned at the center of the crucible 1 so that the distance between the inner peripheral surface of the crucible 1 and the outer peripheral surface of the cooling body 2 was 125 mm.

  After the cooling body 2 is immersed in the molten metal 10, the compressed air for cooling flows through the inside of the cooling body 2 at a flow rate of 2000 liters / minute and is held for 5 minutes while rotating at a peripheral speed of 2.7 m / second. did. As a result, an aluminum block adhered and grown on the outer peripheral surface of the cooling body 2 was obtained. The weight of the obtained aluminum lump was 6.3 kg, and 90 ppm of Fe and 70 ppm of Si were contained as impurities. In terms of purification efficiency, the purification efficiency of Fe was 0.18, and the purification efficiency of Si was 0.28.

  The conditions and results of the above Examples and Comparative Examples are summarized in Table 1.

  From the results in Table 1, it was confirmed that the purification efficiency could be improved according to this embodiment.

It is a schematic block diagram of the production | generation apparatus which concerns on one Embodiment of this invention. It is the II sectional view taken on the line of FIG.

Explanation of symbols

1 crucible 2 cooling body 3 rotating shaft 10 molten metal

Claims (13)

In a metal purification method in which a cooling body is immersed in a molten metal to be purified contained in a crucible, and a high purity metal is crystallized on the surface of the cooling body while rotating the cooling body.
Refining is performed by setting the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body in the portion where the molten metal is present in the crucible to one half or less of the longest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body. A metal refining method characterized by performing.   The metal refining method according to claim 1, wherein the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body is 10 mm or more.   A ratio d / D of an outer dimension d of the cooling body in a horizontal plane including the D with respect to a maximum inner dimension D of the opening of the crucible in a portion where the molten metal exists in the crucible is 0.2 or more. The metal purification method according to 1 or 2.   The metal refining method according to any one of claims 1 to 3, wherein the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body is changed with the formation of the refined lump attached to the cooling body.   The metal refining method according to claim 1, wherein the molten metal is aluminum. A crucible containing the molten metal to be purified;
A rotatable cooling body immersed in the molten metal contained in the crucible;
With
In the part where the molten metal exists in the crucible, the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body is set to be less than or equal to one half of the longest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body. The metal refinement | purification apparatus characterized by becoming.   The metal refining device according to claim 6, wherein the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body is set to 10 mm or more.   A ratio d / D of an outer dimension d of the cooling body in a horizontal plane including the D with respect to a maximum inner dimension D of the opening of the crucible in a portion where the molten metal exists in the crucible is 0.2 or more. 6. The metal purification apparatus according to 6 or 7.   The metal refining apparatus according to any one of claims 6 to 8, wherein the shortest distance between the inner peripheral surface of the crucible and the outer peripheral surface of the cooling body is changed with the formation of the refined lump attached to the cooling body.   A purified metal purified by the method according to claim 1.   A casting manufactured from the refined metal according to claim 10.   A metal product obtained by rolling the cast product according to claim 11.   An electrolytic capacitor in which the metal product according to claim 12 is used as an electrode material.

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