KR20130130014A - Method for purifying high-purity aluminium by directional solidification and smelting furnace therefor - Google Patents

Abstract

Providing 4N to 5N aluminum as the raw material, heating the aluminum raw material to a temperature of 670 ° C to 730 ° C, holding for 7 to 80 minutes, during the crystallization process of the finished product of the crystalline ingot Cooling the bottom of the chamber 3 to allow crystallization of the aluminum liquid in the direction from the bottom of the chamber 3 to the top for 1 to 8 hours to obtain a crystalline ingot, stirring the aluminum liquid and Heating, maintaining a specific temperature gradient of the aluminum liquid, and removing a portion of the crystalline ingot from one end of the ingot, wherein the remaining portion is high purity aluminum of high purity aluminum by directional solidification. Manufacturing methods are provided. Also provided is a melting furnace comprising a shell 1, a heating device 2, a chamber 3, a temperature measuring device, a stirring device and a cooling device 6.

Description

Method for producing high-purity aluminum by directional solidification and melting furnace therefor {Method for purifying high-purity aluminum by directional solidification and smelting furnace therefor}

The present invention belongs to the technical field of melting purification of high-purity aluminum. The present invention relates to a process for producing high-purity aluminum by directional solidification and to a melting furnace therefor, in particular to a process for producing high-purity aluminum (ie 5N to 6N aluminum) by directional solidification and to a melting furnace for the same.

The 5N to 6N aluminum is useful and needed in the electronic industry, in particular in the field of high technology, such as optical storage media, semiconductor devices, superconducting cables, and the like. The purity of the so-called high-purity aluminum can be defined in two ways. Purity is defined directly by industry standard grade or aluminum content, such as 99.95%, 99.99%, AL 99.993A%; Or "digital + N" or "digital + N + digital". For example, 4N represents 99.99% purity and 4N6 represents 99.996% purity. Unless otherwise stated, the aluminum purity described later in the description of the invention is generally detailed in the Chinese Non-ferrous Metals Industry Standard "Micro Aluminum Ingots for Remelting YS / T665-2009". It is usually measured and described accordingly.

Currently, general purification methods are as follows: three-layer liquid electrolysis refining method, organic solution electrolysis method and segregation method. These methods are used in most countries of the world to produce high-purity aluminum in various purity. The purity of the aluminum extracted by the three-layer liquid electrolytic purification method is generally 4N-4N8, but the power consumption is generally above 13000 kwh / t, which is about 4-5 times the segregation method. On the one hand, it is very difficult to reduce costs, and on the other hand, the environment is severely polluted by hazardous gases such as hydrogen fluoride, carbon monoxide, sulfur dioxide, and the like and waste electrolytes generated during the electrolytic process. Therefore, it is not feasible to promote the application of the three-layer liquid electrolytic purification method. Because of the higher energy consumption, lower production and complexity of the process, the organic solution electrolysis method is generally used for the production of small quantities of ultra-high purity aluminum of 7N or more, and therefore not suitable for industrial production.

The segregation method, which is a kind of physical purification method, is increasingly used because it requires a small amount of work and there is no chemical reaction contamination. The segregation method can be carried out by various processes including fractional crystallization process, zone melting process, and directional solidification process. Fractional crystallization processes have been widely applied in the industry of aluminum refining. The purification effect of the process depends on the purity of the primary aluminum (starting material) used in the process, and the aluminum raw material having a purity of 99.5% to 99.95% is commonly used and the process for producing 3N5 to 4N5 aluminum Is purified on. However, the production efficiency is low, and residual aluminum liquid affects the contamination of the final high purity aluminum. Moreover, the process and equipment are complex and the purity grade of the high purity aluminum obtained is limited. The zone melting process can produce 5N5-6N aluminum and is mainly used for further purification of high-purity aluminum produced by the three-layer liquid electrolytic purification method or segregation method. However, the equipment for performing the zone melting process is too complicated, the production efficiency is low, and the energy consumption is relatively high. Thus, it is not appropriate for industrial applications.

Directional solidification methods can be further classified into pipe-cooling solidification methods, floor-cooling methods, side-wall cooling methods, vertical gradient-cooling methods, side-cooling methods, and the like. However, these conventional existing directional solidification methods have the following drawbacks: high energy consumption and cost of the method, low yield of the method, low purity and small, making the manufactured product difficult for industrial mass production. Has a size.

In order to solve the problems and overcome the shortcomings, such as low productivity, high energy consumption and high cost of traditional directional solidification tablets of high-purity aluminum, the present invention is directed to directional solidification at high efficiency and productivity, low energy consumption and low cost. Provided are methods for producing high-purity aluminum. High purity aluminum products can be produced by the process of the invention.

The technical solution applied to solve the technical problem faced by the present invention is a method of producing high-purity aluminum by directional solidification comprising the following steps:

A first step (material selection step) of providing 4N to 5N aluminum as a raw material and cleaning the surface of the aluminum raw material;

Feeding the aluminum raw material from the first step into the chamber of the furnace, wherein the aluminum raw material is heated to a temperature of 670 ° C. to 730 ° C., whereby the aluminum raw material is completely melted to form an aluminum liquid, Second step (melting step);

A third step (temperature holding step) of holding the aluminum liquid from the second step at a temperature of 670 ° C. to 730 ° C. for 7 minutes to 80 minutes;

Cooling the bottom of the chamber to allow crystallization of the aluminum liquid in the direction from the bottom of the chamber to the top for 1 to 8 hours to obtain a crystalline ingot, from which the crystalline ingot product is finished. Finally made by removal of the ingot portion from the finished ingot end, wherein during the crystallization process to form the ingot portion corresponding at least to the finished crystalline ingot product (hereinafter referred to as "final product"), Mechanical stirring and / or electromagnetic stirring are applied to the aluminum liquid when the aluminum liquid is heated, and the temperature of the crystal plane of the aluminum liquid at 655 ° C. to 665 ° C. and the temperature of the liquid surface of the aluminum liquid at 695 ° C. to 705 ° C. Maintaining the temperature of the aluminum liquid from the crystal plane Which gradually increased as the body surface, the fourth step;

Removing a portion of the crystalline ingot from the end of the ingot where the crystallization is finally completed, wherein the portion of the ingot to be removed is from 15% of the desired purity of the crystalline ingot product to be obtained and the thickness of the total crystalline ingot to A fifth step, wherein the remaining portion of the crystalline ingot is the finished crystalline ingot product, ie a high purity aluminum product having a desired purity.

The term “ingot portion corresponding to the final product” refers to a crystalline ingot formed into the remainder after removal of the final high-purity aluminum product, ie, the portion constituting 15% to 70% of the complete crystalline ingot in the fifth step. It is about. In other words, the remaining portion is a crystalline ingot formed by crystallization of aluminum liquid from 30% to 85% from the beginning of the finished crystal. During the crystallization process of this part of the crystalline ingot, stirring and heating are required for the aluminum liquid, and the temperature gradient of the aluminum liquid is maintained. During the subsequent crystallization process, stirring and heating are unnecessary, but may be acceptable (since this portion of the crystal ingot will be removed later and thus may not be part of the final high-purity aluminum product).

In the method for producing high-purity aluminum by directional solidification of the present invention, the crystallization process is stable and controllable, energy consumption and cost are reduced, productivity and efficiency are appropriate crystallization temperature gradient, crystallization rate and other parameters. By selecting it is improved. Moreover, the aluminum liquid is stirred during the crystallization process to reduce the thickness of the impurity-rich layer at the interface of crystallization. Stirring that creates impurities at the crystallization interface separates from the crystalline interface and diffuses upwards on top of the aluminum liquid. This measure of the present invention ensures that the final product of the crystalline ingot has high purity and that the proportion of the ingot portion corresponding to the final product associated with the complete crystalline ingot is large. Therefore, an aluminum end product having a large size and high purity can be obtained. Thus, the purity of the manufactured product may be 5N to 6N.

Preferably, in the first step, the surface of the aluminum raw material described above is cleaned by a physical cleaning process, followed by a chemical cleaning process for removing an oxide film on the surface of the aluminum raw material.

Preferably, in the fourth step, the aluminum liquid is mechanically stirred by a dried and preheated stirring blade, and the distance between the stirring blade and the crystal plane is 10 mm to 50 mm; And / or electromagnetic stirring is applied to the aluminum liquid, wherein the distance between the layer and the crystal plane stirred by electromagnetic stirring is 10 mm to 50 mm.

Regarding the problems of low efficiency, high energy consumption, and high cost of the method of producing high-purity aluminum by the conventional directional solidification method, the present invention also provides high-purity at high productivity, low energy consumption, and low cost through directional solidification. Provide a melting furnace for producing aluminum.

The technical solution for solving the above problems is a melting furnace comprising a shell, a heating device, a chamber, a temperature measuring device, a stirring device and a cooling device. The furnace is useful for practicing the process of the invention for producing high-purity aluminum by directional solidification. In the melting furnace:

The chamber is installed in the shell;

A heating device is mounted between the shell and the chamber, if one heating device is present, and arranged at the top of the chamber, if one or more heating devices are present, which are in the direction from top to bottom of the chamber. Are spaced apart;

A cooling device is arranged below the chamber at the bottom of the furnace.

The stirring device comprises a mechanical stirring device and / or an electromagnetic stirring device;

The temperature measuring device includes a roadside temperature sensing device and a chamber temperature sensor device, wherein the roadside temperature sensing device is arranged between the cooling device and the shell, and the chamber temperature sensor device is located at another position along the height direction of the chamber. It is used to measure the chamber temperature.

The furnace of the present invention has a compact arrangement and a rational structure. It is useful to implement the method of producing high-purity aluminum by the directional solidification described above, and is simple to use. The furnace can be used to produce high-purity aluminum by coordinative combination of heating device, cooling device, temperature measuring device and stirring device. Thus, power consumption and cost are low, while production yield and purity are high.

Preferably, the stirring device comprises a mechanical stirring device; The blades of the mechanical stirring device here are arranged in the lower part of the mechanical stirring device, and can be raised or lowered along the height direction of the stirring device.

Preferably, the stirring device comprises an electromagnetic stirring device, which is arranged between the shell and the heating device and arranged in a displacement manner with the heating device in the height direction of the melting furnace.

Preferably, a thermal insulation layer is arranged inside the shell and outside the heater.

More preferably, the stirring device comprises an electromagnetic stirring device, which is arranged between the thermal insulation layer and the heating device, arranged in a displacement manner with the heating device along the height direction of the furnace.

Preferably, the chamber temperature sensor device includes several temperature sensors distributed outside the chamber along the height direction of the chamber.

Preferably, the heating device is an electric heating device. The present invention is particularly suitable for large-scale production of high-purity aluminum having a purity of 5N to 6N.

The present invention is particularly suitable for large-scale production of high-purity aluminum having a purity of 5N to 6N.

1 is a schematic diagram of a structure of a melting furnace used in a method for producing high-purity aluminum by directional solidification according to an embodiment of the present invention.
For convenience of description, the positional relationship, such as the top, bottom, tower, bottom, interior, exterior of the components of the furnace, is described with reference to the arrangement of the components shown in the accompanying drawings.

BRIEF DESCRIPTION OF DRAWINGS To enable those skilled in the art to have a better understanding of the technical solutions of the present invention, the present invention is described in more detail below with reference to the accompanying drawings and embodiments.

Example 1:

This example provides a method for producing high-purity aluminum by directional solidification comprising the following steps:

First step (step of material selection): providing 4N to 5N aluminum as raw material, and cleaning the surface of aluminum raw material. On the surface of the aluminum raw material, dust, impurities, oxide films and the like are removed through dusting, cleaning, chemical etching, etc. to improve the purity of the raw material and reduce the amount of impurities to be introduced into the dissolution process, Therefore, the purity of the product is improved as much as possible.

Preferably, the aforementioned cleaning step of the surface of the aluminum raw material is: the surface of the aluminum raw material is cleaned by a physical cleaning process (eg, dusting, cleaning, and other non-chemical means), The following chemical cleaning processes (eg, chemical etching, etc.) include those applied to remove the oxide film from the surface of the aluminum raw material.

Second step (melting step): feeding the aluminum raw material from the first step into the chamber of the melting furnace, wherein the aluminum raw material is heated at a temperature of 670 ° C. to 730 ° C., so that the aluminum raw material Melt completely to form. In other words, the aluminum raw material is melted in a chamber for purification to form aluminum in a molten state.

Third step (maintaining temperature): holding the aluminum liquid from the second step for 7 to 80 minutes at a temperature of 670 ° C to 730 ° C. In other words, the molten aluminum raw material is thermally insulated for a period of time so that the melting can be completed, and the temperature and composition of the aluminum liquid can be more uniform and stable.

Fourth step (purification step by solidification): cooling the bottom of the chamber to allow crystallization of the aluminum liquid in the direction from the bottom of the chamber to the top for 1 to 8 hours to obtain a crystalline ingot, thereby From the final product is prepared by removal of a portion of the ingot from the ingot end where the crystallization is finally completed, wherein at least during the crystallization process to form the ingot portion corresponding to the final product, mechanical stirring and / or electromagnetic Agitation is applied to the aluminum liquid, and at the same time the aluminum liquid is heated, and the aluminum liquid is heated to 655 ° C. (because the high purity metal liquid has a greater degree of subcooling and the liquid temperature can be below freezing point) to 665 ° C. Crystal plane, ie the temperature of the lower surface of the aluminum liquid and 695 To be heated while maintaining the temperature of the liquid surface of the liquid aluminum at 705 ℃, thereby increasing the temperature of the liquid aluminum in the liquid surface gradually from the crystal plane. Cooling the bottom of the chamber causes crystallization of aluminum liquid at the bottom of the chamber, and the crystal plane is gradually moved upwards. As a result, crystalline ingots are formed. Preferably during the crystallization process (ie the crystalline ingot portion obtained by crystallization from 30% to 85% from the start of the complete crystallization) to form the ingot portion corresponding to the final product, the aluminum liquid While the aluminum liquid is stirred to reduce the thickness of the impurity-rich layer at the interface, the aluminum liquid is heated to maintain an appropriate temperature gradient of the aluminum liquid. For example, the temperature of the lowest layer of aluminum liquid is maintained at 655 ° C. to 665 ° C. (ie, the temperature close to the melting point of aluminum), and the top layer of the aluminum liquid is maintained at 695 ° C. to 705 ° C., This ensures that the crystallization process proceeds stably. The temperature gradient can be maintained by adjusting the degree of cooling and heating. Since the accuracy of temperature control is limited, the temperature of the lowest and highest layers of the aluminum liquid can vary within a certain range. If the temperature is precisely controlled, it is feasible to maintain the temperature at the correct point. In the process of crystallization, the thickness of the aluminum liquid layer is reduced. The temperature of the top layer of the aluminum liquid can be gradually reduced to close to the temperature of the crystallization surface. The temperature of the crystallization surface cannot escape the unacceptable freezing point. Due to the attenuation of the thickness of the aluminum liquid layer, it is very difficult to maintain a large temperature gradient. Thus, the temperature of the top layer of the aluminum liquid can be lowered. After the crystallization process for forming the ingot portion corresponding to the final product is completed (ie, when the crystallization has started to form an ingot portion which can be removed after the fifth step), the stirring of the aluminum liquid stops. And maintenance of the temperature gradient is no longer necessary. In fact, when the crystallization has proceeded to the final stage, the aluminum liquid is so thin that it is difficult to continue stirring and maintain a temperature gradient.

Preferably, the aluminum liquid is stirred by a stirring blade dried and preheated during the mechanical stirring, and the distance between the stirring blade and the crystal plane is adjusted to 10 mm to 50 mm, if the aluminum liquid is for electromagnetic stirring If agitated, the distance between the layer to which the electromagnetic agitation is applied and the crystal plane is adjusted to 10 mm to 50 mm. In other words, the mechanical agitation is performed by a stirring blade, which is also dried and preheated to avoid adverse effects on the crystallization process (the preheated temperature may be at or about the temperature of the aluminum liquid). When mechanical stirring and / or electromagnetic stirring is carried out, the distance between the stirring layer and the crystal plane can be kept between 10 mm and 50 mm in order to achieve the optimum effect of stirring. Since the crystal plane proceeds progressively upwards, the aforementioned distance can be adjusted by raising or lowering by selectively operating the electromagnetic stirring coil (raising or lowering the electromagnetic stirring coil) at the stirring blades and / or other positions.

5th step (obtaining the final product): removing the part of the crystalline ingot from the end of the ingot where the crystallization is finally completed, wherein the part of the ingot removed is dependent on the desired purity of the obtained crystalline ingot, Range from 15% to 70% of the thickness of the complete crystalline ingot. The remainder of the crystalline ingot is the final product crystalline ingot product, ie a high-purity aluminum product with the desired purity (5N to 6N). According to the principle of directional solidification, in the crystal ingot derived from the present method, the portion formed in the initial stage of the crystallization process has a higher purity, and the portion formed in the late stage of the crystallization process is lower in purity because it is rich in impurities. It is known to have. Thus, in this step, to meet the purity requirements, the ingot portion formed at the end of the crystallization process is cut off from the crystal ingot (this portion can be used in other fields). The remaining part (ie the final product of the crystalline ingot) is the desired final product of high-purity aluminum. Of course, the purity of the final product can also be determined, so that if the purity does not meet the requirements, the crystalline ingot can be further cut off or refined for the method of purifying directional solidification of the present invention, Can be recycled back to the raw material.

Naturally, the process for producing high-purity aluminum by directional solidification of this embodiment can be performed under vacuum or protective atmosphere, in order to reduce oxidation of the aluminum liquid.

In the method for producing high-purity aluminum by directional solidification of the present embodiment, the crystallization process is stable and controllable, energy consumption and cost are reduced, and the productivity and efficiency are appropriate crystallization temperature gradient, crystallization rate and other Improved by the selection of parameters. Moreover, the aluminum liquid is stirred during the crystallization process to reduce the thickness of the impurity-rich layer at the crystallization interface. Stirring that creates impurities at the crystallization interface separates from the crystalline interface and diffuses upwards on top of the aluminum liquid. This measure of the present invention ensures that the final product of the crystalline ingot is of high purity and that the proportion of the ingot portion corresponding to the final product associated with the complete crystalline ingot is large. Thus, a final product of aluminum with large size and high purity can be obtained. Thus, the purity of the manufactured product may be from 5N to 6N.

Example 2:

This example provides a method for producing high-purity aluminum by directional solidification comprising the following steps:

Providing 4N aluminum as a raw material, and physically cleaning the surface of the aluminum raw material;

Feeding the aluminum raw material into a chamber of a furnace, wherein the aluminum raw material is heated to a temperature of 670 ° C. to melt completely to form an aluminum liquid;

Maintaining the aluminum liquid at a temperature of 670 ° C. for 80 minutes;

Cooling the bottom of the chamber to allow crystallization of the aluminum liquid in the direction from the bottom of the chamber to the top for 1 hour to obtain a crystalline ingot; During the crystallization process to form an ingot portion corresponding to the final product, mechanical agitation and electromagnetic agitation are applied to the aluminum liquid, while at the same time the aluminum liquid induces the crystal plane of the aluminum liquid to a temperature of 655 ° C. to 660 ° C., Maintaining the liquid surface of the aluminum liquid at a temperature of 700 ° C. to 705 ° C., and heating, the temperature of the aluminum liquid gradually increases from the crystal plane to the liquid surface, wherein the mechanical agitation causes the dried and preheated stirring blade to And the distance between the stirring blade and the crystal plane is adjusted to 10 mm, while the distance between the stirred layer and the crystal plane is adjusted to 10 mm to 20 mm (the stirred layer by electromagnetic stirring). Adjustment is mainly achieved by operating another electromagnetic stirring coil, The array density of the half coil are limited and, maintaining the correct distance between the agitating layer and the crystal plane is difficult, and in the place of, the distance typically a specific range), a fourth step;

Removing 15% of the thickness of the complete crystalline ingot from the ingot end where the crystallization was finally completed; And the remainder of the crystalline ingot is a final product of the crystalline ingot, ie a high-purity final product of 5N aluminum.

Example 3:

This example provides a method for producing high-purity aluminum by directional solidification, which differs from Example 2 in the following respects:

In the first step, 5N aluminum is provided as raw material, and after physical cleaning of the surface of the aluminum raw material, chemical cleaning is performed sequentially to remove the oxide film from the surface of the aluminum raw material.

In a second step, the aluminum raw material is heated to a temperature of 730 ° C.

In a third step, the aluminum liquid is maintained at 730 ° C. for 7 minutes.

In a fourth step, a crystalline ingot is obtained after 8 hours of cooling step; During the crystallization process to form the ingot portion corresponding to the final product, only mechanical stirring is applied to the aluminum liquid, and the distance between the stirring blade and the crystal plane is 50 mm. The temperature of the crystal plane of the aluminum liquid is maintained at 660 ° C., and the temperature of the liquid surface of the aluminum liquid is maintained at 695 ° C. to 700 ° C.

In a fifth step, 70% of the thickness of the complete crystalline ingot is removed from the ingot end where the crystallization is finally completed. Thus a high-purity end product, 6N aluminum, is obtained.

Example 4:

This example provides a method for producing high-purity aluminum by directional solidification, which differs from Example 2 in the following respects:

In a first step, 4N5 aluminum is provided as raw material.

In a second step, the aluminum raw material is heated to a temperature of 700 ° C.

In a third step, the aluminum liquid is maintained at a temperature of 710 ° C. for 40 minutes.

In the fourth step, the crystalline ingot is obtained after 4 hours of the cooling step; During the crystallization process to form the ingot portion corresponding to the final product, only electromagnetic stirring is applied to the aluminum liquid, and the distance between the stirred layer and the crystal plane by electromagnetic stirring is 30 mm (electromagnetic which can rise or fall) Stirring coils may be used). The temperature of the crystal plane of the aluminum liquid is maintained at 660 ° C to 665 ° C, and the temperature of the liquid surface of the aluminum liquid is maintained at 698 ° C to 702 ° C.

In a fifth step, 40% of the thickness of the complete crystalline ingot is removed from the ingot where the crystallization is finally completed. Thus a high-purity end product, 5N4 aluminum, is obtained.

Example 5:

This example provides a method for producing high-purity aluminum by directional solidification, which differs from Example 2 in the following respects:

In a first step, 4N8 aluminum is provided as raw material.

In a second step, the aluminum raw material is heated to a temperature of 705 ° C.

In a third step, the aluminum liquid is maintained at a temperature of 705 ° C. for 60 minutes.

In the fourth step, the crystalline ingot is obtained after 6 hours of the cooling step; During the crystallization process to form the ingot portion corresponding to the final product, the distance between the stirring blade and the crystal plane is 30 mm, and the distance between the layer and the crystal plane stirred by electromagnetic stirring is 40 mm to 50 mm. The temperature of the crystal plane of the aluminum liquid is maintained at 658 ° C to 662 ° C, and the temperature of the liquid surface of the aluminum liquid is maintained at 700 ° C.

In a fifth step, 50% of the thickness of the complete crystalline ingot is removed from the crystallized ingot end. Thus a high-purity end product, 5N6 aluminum, is obtained.

Example 6:

As shown in FIG. 1, the present embodiment provides a melting furnace used in the above-described method for producing high-purity aluminum by directional solidification, and includes a shell (1), a heater (2), a chamber (3), A temperature measuring device (not shown in the figure), a stirring device 5, and a cooling device 6.

In the melting furnace, the chamber (3) is equipped with the shell (1); The aluminum liquid is crystallized in the chamber.

At least one heating device 2 is arranged in a melting furnace arranged between the shell 1 and the chamber 3. If one heating device 2 is present, it is arranged at the position of the upper part of the chamber 3, and if there are several heating devices 2, it is spaced in the direction from the top to the bottom of the chamber 3 Arranged to have. In other words, in order to maintain the above-described temperature gradient in the crystallization process, if there is only one heating device 2, it is arranged on top of the chamber 3, and if there are multiple heating devices 2, It is arranged to be spaced in the direction from the top to the bottom of the chamber 3 (ie preferably arranged at the top of the chamber 3), and there may be a space between adjacent heating devices 2. During the crystallization process, by adjusting the temperature of the cooling device 6 and the heating device 2, the above-described temperature gradient can be maintained.

Preferably, the heating device 2 is an electronic heating device 2.

The cooling device 6 is arranged below the chamber 3, which is the bottom of the furnace, for cooling the bottom of the chamber 3 so that the aluminum melt can crystallize along the direction from the bottom to the top of the chamber.

Preferably, the insulating layer 4 is arranged inside the shell 1 and outside the heating device 2 for the purpose of improving the thermal insulation effect of the chamber 3, reducing the power consumption, and maintaining the temperature accurately. .

The stirring device comprises a mechanical stirring device 5 and / or an electromagnetic stirring device 8; These are used to stir the aluminum melt.

Preferably, when the stirring device includes the mechanical stirring device 5, the stirring blade 7 of the mechanical stirring device 5 is arranged in the lower portion of the mechanical stirring device 5, and the height direction of the stirring device is provided. It can rise or fall along. In other words, the upper end of the stirring blade 7 can be connected to a bracket (not shown in the figure), and the bracket can be connected to a lifting device (not shown in the figure), so that the stirring blade 7 ) May be raised or lowered to maintain the aforementioned distance between the stir blade and the crystal plane. Various structures of the mechanical stirring device 5 have not been described in detail in the present invention.

Preferably, if the stirring device comprises an electromagnetic stirring device 8, the electromagnetic stirring device 8 is between the shell 1 and the heating device 2, or the heat insulating layer 4 and the heating device 2. It is arranged in between, and is set in a displacement manner having the heating device 2 in the height direction of the melting furnace. In other words, when the heat insulating layer 4 is not present, the electromagnetic stirring device 8 (mainly electromagnetic stirring coil) is arranged between the shell 1 and the heating device 2, and when the heat insulating layer 4 is present, The electromagnetic stirring device 8 is arranged between the heat insulating layer 4 and the heating device 2. The electromagnetic stirring device 8 is always set at a position different from the position of the heating device 2 along the height direction of the melting furnace. In the arrangement of this way, the electromagnetic stirring device 8 is separated and separated from the heating device 2 and is thus not affected by the heating device 2. Since the electromagnetic stirring device is arranged at a different position in height from the heating device 2, the electromagnetic fields generated by it may not pass through the heating device 2 and can be applied directly onto the aluminum liquid. have. Thus, an excellent stirring effect can be achieved. In the crystallization process, by moving to the top of the crystal plane, the other electromagnetic stirring device 8 (ie, the electromagnetic stirring coil) is operated sequentially, and the aforementioned distance between the stirring layer and the crystal plane can be maintained. . Of course, if only one electromagnetic stirring device 8 is present and can be raised and lowered like the stirring blade 7, the aforementioned distance between the stirring bed and the crystal plane can also be maintained.

The temperature measuring device includes a roadside temperature sensing device and a chamber temperature sensor device. The roadside temperature sensing device is installed between the cooling device 6 and the shell 1, and the chamber temperature sensor device is used to measure the temperature of the chamber 3 to another position in the height direction.

Preferably, the chamber temperature sensor device comprises several temperature sensors (eg, thermocouples) distributed outside of the chamber 3 along the height direction to measure the temperature of the chamber 3 at different heights. ). Of course, if there is only one chamber temperature sensor device, it is feasible as long as it can rise or fall along the height direction.

During the crystallization process, the cooling device 6 can be adjusted according to the temperature measurement result of the temperature measuring device, so as to maintain the above-mentioned temperature gradient of the aluminum liquid.

In the melting furnace of the present embodiment, the heating device 2, the heat insulating layer 4, the mechanical stirring device 5, the cooling device 6, the electromagnetic stirring device 8, and the temperature measuring device all use devices known in the art. Can be. The furnace may also include other known structures, for example devices for maintaining a vacuum or providing a protective atmosphere.

The melting furnace of the present invention has a compact arrangement and reasonable structure. The implementation of the aforementioned method for producing high-purity aluminum by directional solidification is simple to use and useful. The furnace can be used to produce high-purity aluminum using a combination of heating, cooling, temperature measuring and stirring devices. Thus, power consumption and cost are low, while production yield and purity are high.

It is to be understood that the foregoing embodiments are merely illustrated to illustrate the principles of the invention. However, the present invention is not limited thereto. Various modifications and improvements can be made to those skilled in the art without departing from the spirit and essence of the invention, and such changes and modifications are also within the scope of the invention.

Reference numbers shown in the drawings are:
1: shell; 2: heater;
3: chamber; 4: heat insulation layer;
5. Mechanical stirring device; 6. cooling system;
7. stirring blade; 8. Electromagnetic stirring device

Claims (10)

Providing 4N to 5N aluminum as a raw material and cleaning the surface of the aluminum raw material;
Feeding the aluminum raw material from the first step into the chamber of the furnace, wherein the aluminum raw material is heated to a temperature of 670 ° C. to 730 ° C., whereby the aluminum raw material is completely melted to form an aluminum liquid, Second step;
A third step of maintaining the aluminum liquid from the second step at a temperature of 670 ° C. to 730 ° C. for 7 minutes to 80 minutes;
Cooling the bottom of the chamber to allow crystallization of the aluminum liquid in the direction from the bottom of the chamber to the top for 1 to 8 hours to obtain a crystalline ingot, from which the crystalline ingot product is finished. Finally produced by removal of the portion of the ingot from the finished ingot end, wherein during the crystallization process to form at least the ingot portion corresponding to the finished crystalline ingot product, mechanical agitation and / or electromagnetic agitation is Applied to an aluminum liquid, and at the same time the aluminum liquid is heated while maintaining the temperature of the crystal plane of the aluminum liquid at 655 ° C. to 665 ° C. and the temperature of the liquid surface of the aluminum liquid at 695 ° C. to 705 ° C., and the aluminum liquid The temperature of the liquid surface from the crystal plane Gradually increasing to a fourth step;
Removing a portion of the crystalline ingot from the end of the ingot where the crystallization is finally completed, wherein the portion of the ingot to be removed is from 15% of the desired purity of the crystalline ingot product to be obtained and the thickness of the total crystalline ingot to And a fifth step, wherein the remaining portion of the crystalline ingot is the finished crystalline ingot product, i.e., a high purity aluminum product having a desired purity. The method according to claim 1,
In the first step, the step of cleaning the surface of the aluminum raw material is:
Cleaning the surface of the aluminum raw material by a physical cleaning process, and
And applying a chemical cleaning process to remove the oxide film from the surface of the aluminum raw material. The method according to claim 1 or 2,
In the fourth step,
Mechanical stirring is applied to the aluminum liquid by a dried and preheated stirring blade, the distance between the stirring blade and the crystal plane being between 10 mm and 50 mm; And / or
Electromagnetic stirring is applied to the aluminum liquid, wherein the distance between the layer stirred by electromagnetic stirring and the crystal plane is from 10 mm to 50 mm. A shell, heating device, chamber, temperature measuring device, stirring device and cooling device; here,
The chamber is installed in the shell;
The heaters are arranged between the shell and the chamber and, if there is one heater, are positioned and arranged in the upper part of the chamber, and if there are a plurality of heaters, they are from the top to the lower part of the chamber. Arranged at intervals in the direction of;
The cooling device is arranged below the chamber at the bottom of the furnace;
The stirring device comprises a mechanical stirring device and / or an electromagnetic stirring device;
The temperature measuring device includes a roadside temperature sensing device and a chamber temperature sensing device, the roadside temperature sensing device is arranged between the cooling device and the shell, and the chamber temperature sensing device is located at different positions along the height direction of the chamber. Melting furnace useful for carrying out the method for producing high purity aluminum by directional solidification as claimed in any one of claims 1 to 3 used for measuring the chamber temperature. The method of claim 4,
The stirring device comprises a mechanical stirring device; here,
The stirring blade of the mechanical stirring device is arranged in the lower portion of the mechanical stirring device, and is useful for carrying out the method of producing high purity aluminum by directional solidification, which is capable of raising and lowering along the height direction of the stirring device. Melting furnace. The method according to claim 4 or 5,
The stirring device comprises an electromagnetic stirring device, which is arranged between the shell and the heating device, and arranged in a displacement manner with the heating device in accordance with the height direction of the melting furnace of high purity aluminum by directional solidification. Melting furnaces useful for carrying out manufacturing methods. The method according to claim 4 or 5,
And a heat insulating layer is arranged inside the shell and outside the heating device. A melting furnace useful for carrying out a method for producing high purity aluminum by directional solidification. The method of claim 7,
The stirring device includes an electromagnetic stirring device, wherein the electromagnetic stirring device is arranged between the heat insulation layer and the heating device, and is arranged in a dislocation manner together with the heating device according to the height direction of the melting furnace. A melting furnace useful for carrying out a method for producing high purity aluminum by directional solidification. The method according to claim 4 or 5,
The chamber temperature sensing device is useful for carrying out a method for producing high purity aluminum by directional solidification, characterized in that it comprises several temperature sensors distributed outside of the chamber along the height direction of the chamber. The method according to claim 4 or 5,
The heating device is useful for carrying out a method for producing high purity aluminum by directional solidification, characterized in that the electric heating device.

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