JPS63162823A - Purifying method for metal - Google Patents

Abstract

PURPOSE:To prevent the furious rippling on a liquid surface and to reduce the amount of the sludge generated, by lowering the temp. of a crystallizing part progressively as the position goes down when a revolving cooling body is submerged and revolved in a molten metal in a crucible to crystallize the purified metal. CONSTITUTION:A specified amount of molten Al 4 containing eutectic impurities melted in a molting furnace is sent into a crucible 1, and the revolving cooling body 10 is submerged in the molten Al and the upper opening of the crucible 1 is hermetically covered with a cover. Then, the revolving body 10 is revolved while a cooling liquid is supplied to the inner part of the revolving body 10, and the initial crystals Al are crystallized on a high purity Al crystallizing part 11. At this time, the atmosphere above the molten metal surface in the crucible 1 is heated by a burner, etc., so that the temp. of the outer peripheral part of the crystallizing part 11 is higher at the upper end and is progressively lower toward the lower part. As a result, an Al nodule I is formed in a tapered shape expanding downward so that it generates the downward stream in the direction B. By this method, the furious rippling on the molten metal surface is prevented, and the sludge consisting of Al2O3 produced by the reaction between Al and O2 in the air is reduced.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention is used in an apparatus for producing metals of higher purity by refining various metals containing eutectic impurities such as aluminum, silicon, magnesium, lead, and zinc. The present invention relates to a rotary cooling body.

Prior Art and its Problems For example, a method is known in which aluminum to be purified containing impurities that form a eutectic with aluminum is purified to a higher purity by utilizing the principle of end-fold solidification. and,
As shown in FIG. 6, the apparatus used to carry out such a method includes a crucible (1) for holding molten aluminum (4), and a crucible (1) for holding molten aluminum (4). ), which is rotatably immersed in a rotary cooling body (20), and the rotary cooling body (20) has a tapered shape that gradually tapers downward from the upper end. After melting the aluminum, the molten aluminum (4) is placed in the crucible (1) and kept heated to a temperature that exceeds its solidification temperature, and then cooled into the heated molten aluminum (4). By immersing the body (20), maintaining the surface temperature of this cooling body (20) below the solidification temperature, and rotating this cooling body (20) to disperse and mix the impurities discharged near the solidification interface. , the thickness of the impurity-concentrated layer near the solidification interface in the liquid phase is reduced, and as a result, while increasing the temperature gradient in the liquid phase at the impurity-concentrated layer, purity is increased by the circumferential surface of the cooling body (20). Aluminum is refined by crystallizing aluminum with high aluminum content.

In the above, in order to reduce the thickness of the impurity-concentrated layer near the solidification interface in the liquid phase and thereby increase the temperature gradient to improve purification efficiency, it is necessary to use a cooling body 20) and molten aluminum (4). ) is one of the conditions.

However, as the cooling body (20) rotates, the molten aluminum (4) also flows in the same direction as the rotational direction of the cooling body, creating a vortex, so there is a limit to the increase in the relative speed, and the improvement in refining efficiency is limited. There are also limits. Moreover, the cooling body (20
), the centrifugal force increases and the cooling body (2
There is a problem in that the crystallized high-purity aluminum becomes difficult to adhere to the peripheral surface of 0), resulting in a decrease in productivity.

Therefore, in order to solve this problem, a device was devised in which a plurality of baffles (3) for reducing the flow rate of molten aluminum are provided on the inner peripheral surface of the crucible (1) at predetermined intervals in the circumferential direction. (Refer to Utility Model Publication No. 61-38912). Although this apparatus can further improve purification efficiency, the following problems arise. That is, when the baffle plate (3) is present, the flow velocity is partially different, and as a result, the flow rate of the molten aluminum (4) along the circumferential surface of the cooling body (20) as shown by the arrow (C) in FIG. An upward flow is generated, the liquid surface is violently rippled, air is drawn into the molten aluminum (4), and this air and aluminum react to generate a large amount of slag made of A/203. Therefore, sludge removal work is required, and the sludge scatters and adheres to the inner surface of the crucible (1), causing trouble in the work. Furthermore, a large amount of slag is generated, which may reduce purification efficiency.

An object of the present invention is to provide a metal refining method that solves the above problems.

Means for Solving the Problems The metal refining method according to the present invention involves placing molten metal in a crucible, immersing a rotary cooling body in the molten metal, and rotating the rotary cooling body to improve the purity of the surrounding surface. In crystallizing refined metal, a rotary cooling body is used in which the part below the molten metal surface is a purified metal crystallization part, and at least the upper outer periphery of the high purity metal crystallization part is used. By setting the temperature of the surface to be highest at the upper end and lower toward the bottom, the rate of crystallization of refined metal toward at least the upper portion of the refined metal crystallization section is slowest at the upper end and faster toward the bottom. The method is characterized in that the shape of the upper part of the metal lump that crystallizes is in the shape of a lower floor.

In the above, a method for making the temperature of at least the upper outer circumferential surface of the refined metal crystallization part of the rotary cooling body highest at the upper end and decreasing downwards is to open and close the upper end opening of the crucible with a lid that can be opened and closed. A method of heating the atmosphere above the liquid level of molten metal in a crucible, a method of heating a portion of a rotating cooling body above the liquid level of molten metal, a method of heating the part of the crucible that is above the liquid level of molten metal, and a method of heating the atmosphere above the liquid level of molten metal in a rotating cooling body. There are methods such as decreasing the amount of fluid at the top and increasing it toward the bottom, and methods that combine these methods.

Example Examples of the present invention will be described below.

The following example applies the method of this invention to the production of high-purity aluminum. Note that the same parts and parts are denoted by the same reference numerals throughout the drawings.

FIG. 1 shows a first specific example of the apparatus used to carry out the invention.

In Fig. 1, the high-purity aluminum production equipment consists of a graphite melt holding crucible (1), a rotary cooling body (2) that can move up and down, and an inner wall of the crucible (1) spaced at a predetermined interval in the circumferential direction. It consists of a plurality of baffle plates (3) for reducing the flow rate of molten aluminum detachably fixed to the circumferential surface. The upper end opening of the crucible (1) is closed with a lid (path shown) that can be opened and closed. Further, the amount of molten aluminum (4) put into the crucible (1) is set to be approximately constant.

The rotary cooling body (2) is a hollow body made of graphite, ceramics, etc., and gradually becomes thicker from the upper end toward the bottom and gradually becomes thinner from the middle part of its length toward the lower end. .

The rotary cooling body (2) is attached to the lower end of the hollow rotating shaft (5), into which cooling fluid is supplied from the cooling fluid supply pipe (path shown) arranged in the hollow rotating shaft (5). It is now being supplied.

In addition, the rotary cooling body (2) cools the liquid surface of the molten aluminum (4) in a predetermined amount of molten aluminum (4) placed in the crucible (2) during the production of high-purity aluminum. The body (2) is immersed so that it is between the upper end and the maximum diameter part (2a) at the middle part of the height, and the part below the liquid level is a high-purity aluminum crystallized part (6) (refined metal crystallization part).

In such a configuration, molten aluminum (4) to be purified containing eutectic impurities such as Fe5Si%Cu and Mg melted in a melting furnace (path shown) is fed into the crucible (1). At this time, the rotary cooling body (2) is in the raised position and outside the crucible (1). After putting a predetermined amount of molten aluminum (4) into the crucible (1), the rotary cooling body (2) is
The crucible (1) is immersed in molten aluminum (4) so that the liquid level is between its upper end and the largest diameter portion (2a), and the upper opening of the crucible (1) is closed with a lid. When the rotary cooling body (2) is rotated while supplying cooling fluid into the interior of the rotary cooling body (2), a smooth layer is first formed on the high purity aluminum crystallized portion (8) of the rotary cooling body (2). High purity primary aluminum with solidified surfaces crystallizes out. The eutectic impurities are discharged into the liquid phase, forming an impurity-concentrated layer of eutectic impurities in the liquid phase near the solidification interface. Due to the rotation of the rotary cooling body (2), the molten aluminum (4) also flows in the same direction as the rotating direction of the rotary cooling body (2), but the baffle plate (3) prevents the molten aluminum (4) from flowing.
) is reduced, so that the relative velocity between the rotary cooling body (2) and the liquid phase, ie the difference between the circumferential speed of the rotary cooling body (2) and the flow velocity of the molten aluminum (4), becomes considerably large. Therefore, the impurity concentration layer formed near the interface is effectively stirred and mixed with most of the other liquid phase, and the impurities in the impurity concentration layer are dispersed throughout the liquid phase, resulting in impurity concentration. The thickness of the layer becomes thinner and the temperature gradient in this region also becomes larger. Moreover, the molten aluminum (
The turbulent flow described in 4) also occurs, and the impurity concentrated layer is thinned by this as well. If solidification is allowed to proceed in this state, the cooling body (2
), an aluminum lump (1) of much higher purity than the original aluminum is obtained.

At this time, the atmosphere above the liquid level in the crucible (1) is heated with a burner, etc., and the temperature of the outer peripheral surface of the high-purity aluminum crystallization part (6) of the rotary cooling body (2) is adjusted so that the upper end is the highest. Make it high and get lower towards the bottom. Then, the amount of crystallization in the high-purity aluminum crystallization part (6) is small at the upper end, increases downward to the maximum diameter part (2a), and becomes equal below the maximum diameter part (2a), and the amount of crystallization in the high-purity aluminum crystallization part ( 6
) The shape of the high-purity aluminum lump (I) crystallized on the outer peripheral surface of the aluminum ingot (I) is thinnest at the upper end, gradually widens downward, becomes thickest at the maximum diameter part (2a), and becomes thinner downward. It becomes something. Therefore, in the vicinity of the cooling body (2), a downward flow as shown by the arrow (A) in FIG. 1 is generated along the upper part of the high-purity aluminum lump (1). As a result, violent ripples on the liquid surface are prevented, and the A
/20. The amount of slag will be reduced.

Next, more specific examples will be described.

Six baffle plates (3) were provided on the inner peripheral surface of the crucible (1). Further, the outer diameter of the maximum diameter portion (2a) of the cooling body (2) was set to 1501 mm. Then, in the crucible (1), Fed, 07wt%, SiO.

Molten aluminum (4) containing 0.04vt% was added and kept heated at 670°C. Further, the atmosphere on the −F side of the molten aluminum (4) was heated and maintained at 700°C. Next, the rotary cooling body (2) was immersed in the molten aluminum (4), and was rotated at a rotational speed of 40 Orpm while supplying a cooling fluid to the inside thereof. After performing this operation for 30 minutes, the rotation of the cooling body (2) is stopped,
The cooling body (2) was raised. 1 on the circumferential surface of the cooling body (2)
A 3 kg aluminum lump was crystallized. Thereafter, the aluminum lump (1) crystallized on the circumferential surface of the cooling body (2) was removed, and the average impurity concentration of Fe and Si in the aluminum lump (+) was measured. As a result, Fed, 005
0wt%, Sin, 0070wt%, and the effective distribution coefficient obtained by dividing this value by the original impurity concentration is K (Fe) = 0
．． 07, K(St)-0.17. Further, during the operation, the liquid level of the molten aluminum (4) was quiet and no slag was observed.

For comparison, a comparative example using a conventional device will be described. The outer diameter of the portion of the rotary cooling body (20) in contact with the liquid surface of the molten aluminum (4) was fixed at 1501. Then, in the crucible (1), FeO, 07w
Molten aluminum (4) containing t%, SLo, and 04vt% was added and kept heated at 670°C. Next, the rotary cooling body (20) is immersed in the molten aluminum (4), and the rotational speed is increased to 400 while supplying cooling fluid to the inside of the rotary cooling body (20).
Rotated at rpm. After performing this operation for 30 minutes, the rotation of the cooling body (20) was stopped and the cooling body (20) was raised. A 10 kg aluminum lump was crystallized on the circumferential surface of the cooling body (20). Thereafter, the aluminum lump crystallized on the circumferential surface of the cooling body (20) was removed, and the average impurity concentration of Fe and Si in the aluminum lump was measured.

As a result, FeO, 0070vt%, Si 0.00
88 wt%, and its effective partition coefficient is K (Fe)-
It was 0,1, K (S 1) - 0,21. Furthermore, during the operation of the shuttle, violent splashing of molten metal occurred on the surface of the molten aluminum (4), and a large amount of slag was generated.

This slag adhered to the inner peripheral surface of the crucible (1) above the liquid level and became an obstacle to the continuation of the refining operation.

FIG. 2 shows a second specific example of the apparatus used to practice the invention.

In FIG. 2, the rotary cooling body (10) has a hollow cylindrical shape with the same diameter over its entire length, and the portion below the liquid level of the molten aluminum (4) is a high-purity aluminum crystallization area (10).
1).

In such a configuration, the production of high purity aluminum is carried out in the same way as in the apparatus shown in FIG. The crystallized high-purity aluminum lump (I) has a tapered shape that spreads downward from the upper end, and a downward flow as shown by the arrow (B) in Figure 2 flows along the top of this high-purity aluminum lump (I). As a result, severe ripples on the liquid surface are prevented, and the amount of slag made of A/203 produced as a result of the reaction between oxygen in the air and aluminum is reduced.

FIG. 3 shows a third specific example of the apparatus used to carry out the invention.

In FIG. 3, the rotary cooling body (20) has the same configuration as that used in the conventional method, and has a Taber cylindrical shape that gradually becomes thinner from the upper end downward. ) is a high-purity aluminum crystallization part (16) below the liquid level. In such a configuration, the production of high purity aluminum is carried out in the same way as in the apparatus shown in FIG. The crystallized high-purity aluminum lump (1) has a tapered shape that spreads downward from the upper end, and descends as shown by the arrow (D) in Figure 3 along the upper part of this high-purity aluminum lump (1). A flow occurs. As a result, violent ripples on the liquid surface are prevented, and the A
The amount of slag consisting of /203 is reduced.

FIG. 4 shows a fourth specific example of the apparatus used to carry out the invention.

In FIG. 4, the high-purity aluminum manufacturing apparatus includes a melting furnace (12) for melting aluminum to be purified, followed by four crucibles (IA) to (LD), and four crucibles (1A) to (LD). A baffle plate (3) is provided inside the crucible (ID) in the same way as in the apparatus of the above embodiment.Also, a high-purity aluminum crystal that can be moved up and down corresponds to each crucible (IA) to (ID). A rotary cooling body (2) is provided for discharging the crucibles (LA) to (10). Adjacent crucibles (LA) to (10) are connected to each other through a connecting gutter (13) at the upper end, and the leftmost crucible (LA) ) in the melting furnace (12
) A gutter (14) is attached to the receiver to receive the molten aluminum supplied from the crucible (ID) on the right end.
A molten metal discharge gutter (15) is attached to the upper end.

In the high-purity aluminum manufacturing apparatus having such a configuration, the aluminum to be purified is melted in the melting furnace (12) and sent to each of the crucibles (IA) to (ID). When the amount of molten metal in each crucible (LA) to (ID) reaches a predetermined amount, the cooling body (2) is lowered and immersed in the molten metal, and the upper end openings of the crucibles (LA) to (ID) are closed. . Then, the atmosphere above the liquid level of the molten aluminum (4) is heated and maintained at a temperature higher than its liquidus temperature.

Next, it is rotated while supplying cooling fluid from the hollow rotating shaft (5) into its interior. Then, due to the principle of segregation solidification, high-purity aluminum is crystallized only on the peripheral surface of the lower portion of the maximum diameter portion (2a) of the rotary cooling body (2). The eutectic impurities are expelled into the liquid phase and are moved away from the cooling body (2) by the centrifugal force generated by the rotation of the cooling body (2). In this way, aluminum of higher purity and desired purity than the original aluminum supplied from the melting furnace (12) is obtained. The principle of obtaining high purity aluminum on the circumferential surface of the rotary cooling body (2) in each of the crucibles (IA) to (ID) is the same as in the case of the apparatus of Example 1 above.

In this equipment, if the aluminum to be purified contains impurities that will form peritectics with aluminum, a boron addition system equipped with a stirrer between the melting furnace (12) and the leftmost crucible (IA) is used. It is a good idea to have a crucible ready for use. Then, the molten metal is first fed into this crucible from the melting furnace (12), boron is added to the molten metal in this crucible, and the mixture is stirred by the above-mentioned stirrer. Then, boron reacts with peritectic impurities such as Ti and VSZr contained in the molten metal.
Insoluble borides such as B2, V B2 and Z r B2 are produced. Excess boron is removed as a eutectic impurity. The borides are moved away from the cooling body (2) by the centrifugal force generated by the rotation of the cooling body (2) in the crucibles (IA) to (ID), and are deposited on the aluminum crystallized on the circumferential surface of the cooling body (2). It will no longer be included.

FIG. 5 shows a fifth specific example of the apparatus used to carry out the invention.

The difference in FIG. 5 from the apparatus shown in FIG. 1 is that a baffle plate (3) is not provided on the inner circumferential surface of the crucible (1), and the other configurations are the same.

Also, in the devices shown in FIGS. 2 to 4, the baffle plate (3) may not be provided.

Effects of the Invention According to the metal refining method of the present invention, a rotary cooling body is used in which the portion below the molten metal surface is a refined metal crystallization region with higher purity, and By setting the temperature of the outer circumferential surface of at least the upper part to be highest at the upper end and decreasing toward the bottom, the crystallization rate of refined metal toward at least the upper part of the refined metal crystallization section is the slowest at the upper end and decreases toward the bottom. This method is characterized by the shape of the upper part of the crystallizing metal lump expanding downward, so that after crystallization of the metal lump, the metal lump near the liquid surface near the rotary cooling body. Then, a downward flow is generated along the upper part of the metal lump. Therefore, the occurrence of ripples on the liquid surface, scattering of molten metal, etc. is prevented, and as a result, the amount of slag consisting of Al2O3 produced as a result of the reaction between oxygen in the air and aluminum is reduced, which occurs as a result of generation of a large amount of slag. Problems are prevented before they occur.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view showing a first specific example of the device used to carry out the present invention, FIG. 2 is a vertical cross-sectional view showing a second specific example of the device used to carry out the present invention, and FIG. Figure 1 is a vertical sectional view showing a third specific example of the device used to carry out the present invention, Figure 4 is a vertical sectional view showing a fourth specific example of the device used to carry out the present invention, and Figure 5 is a vertical sectional view showing a fourth specific example of the device used to carry out the present invention. 6 is a vertical cross-sectional view showing a fifth specific example of the apparatus used in carrying out the present invention, and FIG. 6 is a vertical cross-sectional view showing the apparatus used in carrying out the conventional method. (1) (LA) ~ (ID)... Crucible, (2) (1
0)... Rotary cooling body, (4)... Molten aluminum, (8) (11) (16)... High purity aluminum crystallization part (refined metal crystallization part), (I)... High purity aluminum ingot. Patent applicant Showa Aluminum Co., Ltd. Agent
Einosuke Kishimoto (4 others) Figure 1 Figure 2 Figure 5 Figure 6 March 25, 1988 1. Display of the case 1985 Patent Application No. 313248 2, Name of the invention MU method for metals 3, Person making the amendment Relationship to the case Patent applicant 4 Agent Address 6 Inaba Building, 57-57 Ugidani Nishinocho, Minami-ku, Osaka 6th floor Telephone 06-252-2436 Name (608
7) Patent Attorney Einosuke Kishimoto No. 6, Number of inventions increased by amendment 7, Contents of amendment subject to amendment (1) Amend the statement in the scope of claims column of the specification as shown in the attached sheet do. (2) From page 2, line 5 to page 4, line 19 of the same book, “For example...
There is... ” should be corrected as follows. "For example, there is a known method of refining aluminum that contains impurities that form eutectic with aluminum to a higher purity by utilizing the principle of segregation solidification. The method according to the patent application is that after the aluminum to be purified is melted, this molten aluminum is placed in a crucible and is always heated and maintained at a temperature exceeding its solidification temperature. A hollow rotary cooling body with a tapered cylindrical shape tapered downward is immersed in the cooling body, and cooling fluid is fed into this cooling body to maintain its surface temperature below the above-mentioned solidification temperature while rotating this cooling body. By dispersing and mixing the impurities discharged near the solidification interface during crystallization on the outer circumferential surface of the cooling body into the entire liquid phase, the thickness of the impurity concentrated layer near the solidification interface in the liquid phase can be reduced. As a result, there is a method of refining aluminum by crystallizing highly pure aluminum from the circumferential surface of a cooling body while increasing the temperature gradient in the liquid phase in the impurity-concentrated layer (Japanese Patent Publication No. 3385/1985). reference)
. In the above method, in order to reduce the thickness of the impurity-concentrated layer near the solidification interface in the liquid phase and thereby increase the temperature gradient and improve purification efficiency, it is necessary to connect the cooling body and molten aluminum. Condition 1 is to increase the relative speed
It is one. However, as the cooling body rotates, the molten aluminum also flows in the same direction as the rotational direction of the cooling body, creating a vortex, so there is a limit to the increase in the relative speed, and there is also a limit to the improvement in refining efficiency. Moreover, if the number of revolutions of the cooling body is increased, centrifugal force increases, making it difficult for crystallized high-purity aluminum to adhere to the circumferential surface of the cooling body, resulting in a decrease in productivity. In addition, when the rotation speed of the cooling body is increased, the area around the cooling body tries to involve the molten aluminum, and air is drawn into the molten aluminum.
This air and aluminum react to generate a large amount of slag consisting of A12o3. Moreover, since the cooling body used in the above-mentioned conventional method has a tapered cylindrical shape that tapers downward from the upper end, when it is rotated, the circumferential speeds of the upper and lower parts will be different. The circumferential speed at the top becomes larger than the circumferential speed at the bottom, creating a flow with an upward velocity component in the molten aluminum.As a result, the surface of the molten aluminum ripples and air is drawn into the molten aluminum. This air reacts with aluminum to generate a large amount of slag consisting of A12o3. therefore,
Not only does slag removal work become necessary, but the sludge scatters and adheres to the inner surface of the crucible, impeding the work. Furthermore, a large amount of slag is generated, which may reduce purification efficiency. The above-mentioned ripples become more likely to occur after aluminum lumps begin to crystallize on the circumferential surface of the rotary cooling body. The applicant also proposed that a plurality of baffles for reducing the flow rate of molten aluminum be provided at predetermined intervals in the circumferential direction on the inner peripheral surface of the crucible in order to reduce the flow rate of the vortex flow of the molten aluminum. (Refer to Utility Model Publication No. 61-38912). In this case, the relative speed between the cooling body and molten aluminum can be increased without increasing the rotational speed of the cooling body so much, and the refining efficiency can be further improved. However, the presence of the baffle causes the flow velocity of the molten aluminum to differ locally, with the result that the molten aluminum has an upward velocity component near the top of the section of the cooling body that is below the liquid surface. More flow will occur. Therefore, the surface of the molten aluminum ripples more violently, and the adverse effects of the ripples become more severe. (3) In the same book, page 5, line 6, ``purity'' is changed to ``purity in the refined metal crystallization area below the molten metal surface.''
I am corrected. In lines 7 to 9 of the same page, "High purity metal crystallization section as a rotary cooling body" is corrected to "refined metal crystallization section." (4) On page 6, line 6 of the same book, between ``method'' and ``and,'' it says, ``The inner circumferential surface of the refined metal crystallization area is covered with a heat insulating material, and the thickness of the heat insulating material is adjusted from the thinnest at the top to the bottom. ``How to gradually thicken it towards the top.'' (5) "Katte" and "cooling body" in the same book, page 10, line 6
``After the aluminum lump (1) crystallizes, the circumferential speed in the upper part of the aluminum lump (1) becomes smaller than the circumferential speed in the lower part in the part above the maximum diameter part (2a).'' do. Add the following sentence between lines 11 and 12 on the same page. In the above, even at the initial stage of the operation, that is, before the high-purity aluminum ingot (1) begins to crystallize into the shape described above, the under-floor part above the maximum diameter part (2a) , a flow of molten aluminum (4) with a downward velocity component is generated in the vicinity, which prevents violent ripples from occurring on the liquid surface.
8) "Conventional example" on page 11, line 16 of the same book is corrected to "shown in Figure 6." On line 17 of the same page, between “state” and “rotating cooling body”, “
In the device shown in Fig. 6, a rotary cooling body (20) immersed in molten aluminum (4) in a crucible (1) has a tapered shape that gradually becomes thinner from the upper end downward. . Add this. (7) In the same book, p. 13, line 8, ``It is carried out.'' The atmosphere above the molten aluminum (4) surface is heated with a burner, etc.
1) The temperature of the outer circumferential surface is the highest at the upper end and decreases downward. ” he corrected. In line 10 of the same page, ``in the same manner as in Example 1'' is added between ``Nari,'' and ``Kono''. In lines 18 and 19 of the same page, "used in the conventional method" is corrected to "shown in FIG. 6." (8) In the same book, page 14, line 5, ``It is carried out.
1) The temperature of the outer circumferential surface is the highest at the upper end and decreases downward. ” he corrected. In line 7 of the same page, ``in the same manner as in Example 1'' is added between ``Nari,'' and ``Kono''. On line 12 of the same page, next to "It will decrease.""In this device, ripples will occur on the liquid surface during the initial stage of operation, that is, until the high-purity aluminum lump (1) begins to crystallize in the above shape." .” is added. (9) On page 18, line 7 of the same book, between the words ``produces'' and ``therefore,'' it says ``In other words, after the metal lump crystallizes, if the rotary cooling body is rotated, the upper and lower parts of the metal lump As a result, the circumferential velocity of the upper part of the metal lump becomes smaller than that of the lower part, and a flow with a downward velocity component is generated in the molten metal near the rotary cooling body. join. (10) “Implementation of conventional methods” on page 19, line 2 of the same book was changed to “Implementation of conventional methods”
Implementation of a comparative example with respect to the example carried out using the apparatus shown in the figure.'' In the above claims, placing molten metal in a crucible, immersing a rotary cooling body in the molten metal, and rotating the rotary cooling body to bring it out.
By setting the temperature of the outer circumferential surface of at least the upper part of the refined metal crystallization section so that the temperature is highest at the upper end and decreases toward the bottom, the rate of crystallization of refined metal toward at least the upper part of the refined metal crystallization section is increased. 1. A method for refining a metal, characterized in that the crystallizing metal mass is slowest and becomes faster toward the bottom, and the shape of the upper part of the metal mass to be crystallized is made to widen downward.

Claims (1)

[Claims] Molten metal is placed in a crucible, a rotary cooling body is immersed in the molten metal, and as the rotary cooling body is rotated, purified metal with high purity is crystallized from its circumferential surface. The lower part of the refined metal crystallization part is made of a purified metal crystallization part with higher purity, and the temperature of at least the upper outer peripheral surface of the refined metal crystallization part is set so that the temperature is highest at the upper end and becomes lower toward the bottom. By doing so, the rate of refined metal crystallization to at least the upper part of the refined metal crystallization part is slowest at the upper end and becomes faster toward the bottom, and the shape of the upper part of the metal lump to be crystallized is changed to a shape that spreads downward. A metal refining method characterized by: