Purifying device and method for purifying high-purity aluminum by using same

Abstract

The invention relates to a purification device and a high-purity aluminum purification method using the purification device. The purification device comprises a smelting chamber shell, a smelting chamber inner cavity, a smelting container arranged at the bottom of the smelting chamber inner cavity, a magnetic field module and a directional solidification module, wherein the magnetic field module and the directional solidification module are arranged in the gap position between the smelting chamber shell and the smelting chamber inner cavity. The magnetic field module comprises a first magnetic field and a second magnetic field; the first magnetic field comprises a centrifugal magnetic field area arranged on the periphery of the side wall of an inner cavity of the smelting chamber. The second magnetic field comprises axial magnetic field areas symmetrically arranged between the top of the inner cavity of the smelting chamber and the bottom of the inner cavity of the smelting chamber; the directional solidification module comprises a cooling part arranged at the bottom of the smelting container and a heating part arranged along the peripheral side of the top of the smelting chamber shell; according to the purification device and the purification method using the purification device, the removal rate of heavy impurities is preferably as high as 85% or above, the removal rate of light impurities is preferably as high as 75% or above, and continuous production of 6N high-purity aluminum is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of high-purity metal preparation equipment and process technology, and in particular to a purification device and a high-purity aluminum purification method using the same. Background Art

[0002] High-purity aluminum has many excellent physical and chemical properties, such as low density, high thermal and electrical conductivity, and extremely strong corrosion resistance. It also has better conductivity, ductility, and light reflectivity than original aluminum. It is irreplaceable by metallic aluminum and other metals. Therefore, it is widely used in high-tech fields such as electronic information, aerospace, and precision instruments. High-purity aluminum has become a key material in integrated circuits, discrete devices, liquid crystal displays, cathode sputtering aluminum targets, and aluminum thin film materials.

[0003] Currently, aluminum purification technologies include chemical and physical methods. Chemical purification methods include three-layer electrolysis and organic solution electrolysis, while physical purification methods include condensation, fractional crystallization, directional solidification, zone melting, and electromagnetic stirring. Chemical methods generally only purify aluminum to 4N-5N and are subject to high production costs and energy consumption. Furthermore, the production process produces hazardous substances such as hydrogen fluoride and waste electrolyte. The condensation method is not very effective in purifying aluminum. The fractional crystallization method is complex and requires expensive equipment. The directional solidification method requires complex temperature control and low purification efficiency. Zone melting is also subject to complex equipment, high energy consumption, and low efficiency. Electromagnetic stirring technology has been used in the processing of low-purity aluminum, but it cannot be directly applied to the purification of high-purity aluminum of 6N and above due to the difficulty in avoiding the introduction of Fe impurities and its inefficiency in migrating light elements and ultra-low ppb-level impurities.

[0004] For example, CN117660776A discloses a method for preparing high-purity aluminum and an induction vacuum zone melting device. The preparation method uses an induction vacuum zone melting device to perform an induction zone melting process on 5N high-purity aluminum ingots. Although the processed product meets the 6N aluminum standard, the process flow of the preparation method is relatively cumbersome and the preparation device is relatively complex, which increases the purification cost and is not easy to mass-produce 6N aluminum.

[0005] For example, CN118976421A discloses a magnetic stirring system for high-performance aluminum alloy production. The device includes a melt sensing module, a magnetic field control module, a current regulation module, and a flow rate regulation module. It only uses a single electromagnetic field to stir the aluminum liquid, which does not solve the problems of light impurity separation and pollution control. Moreover, the parameter control of the device is cumbersome and not easy to operate.

[0006] In view of this, how to provide a new purification device and a purification method for high-purity aluminum to achieve high-efficiency and low-cost preparation of high-purity aluminum of 6N and above is a difficult problem that needs to be solved urgently in this field. Summary of the Invention

[0007] In order to solve the above technical problems, the present invention provides a purification device and a method for purifying high-purity aluminum using the same, which solves the problems that the existing 6N grade aluminum purification relies on electrolytic refining or regional smelting, has high energy consumption, low efficiency and complex equipment, and the single electromagnetic stirring technology is difficult to avoid the introduction of Fe impurities due to the iron core magnetic field and the migration efficiency of light elements and super-concentration impurities is insufficient, thereby realizing the efficient and low-cost purification of high-purity aluminum of 6N and above.

[0008] To achieve this object, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a purification device, comprising a smelting chamber shell, a smelting chamber inner cavity, a smelting container disposed at the bottom of the smelting chamber inner cavity, and a magnetic field module and a directional solidification module disposed in a gap between the smelting chamber shell and the smelting chamber inner cavity;

[0010] The magnetic field module includes a first magnetic field and a second magnetic field; the first magnetic field includes a centrifugal magnetic field region arranged on the outer periphery of the side wall of the inner cavity of the smelting chamber; the second magnetic field includes an axial magnetic field region symmetrically arranged between the top of the inner cavity of the smelting chamber and the bottom of the inner cavity of the smelting chamber;

[0011] The directional solidification module includes a cooling component arranged at the bottom of the smelting container and a heating component arranged along the circumference of the top of the smelting chamber shell.

[0012] The purification device described in the present invention is designed such that the magnetic field module includes both a centrifugal magnetic field region and an axial magnetic field region. The two-level magnetic fields work together to achieve full impurity spectrum control, wherein the centrifugal magnetic field region drives high-density impurity elements to migrate outward, and the axial magnetic field region suppresses melt turbulence and reduces the dispersion of light impurity elements. Combined with the directional solidification module, impurities are enriched in the top unsolidified area, thereby achieving efficient and low-cost purification of high-purity metals of 6N and above, and enabling continuous production of high-purity metal products.

[0013] Preferably, the smelting container comprises a high-purity alumina crucible.

[0014] The high purity in the high purity alumina crucible means that the purity of the alumina is as high as 99.95% or more.

[0015] Preferably, the inner cavity of the smelting chamber is made of a stainless steel lining and contains a ceramic coating.

[0016] Preferably, an observation port is provided on the top wall of the smelting chamber shell.

[0017] Preferably, the centrifugal magnetic field region includes an annular superconducting coil arranged around the outer wall of the inner cavity of the smelting chamber.

[0018] Preferably, the axial magnetic field region comprises a first coil symmetrically arranged at the top of the inner cavity of the smelting chamber and a second coil symmetrically arranged at the bottom of the inner cavity of the smelting chamber.

[0019] Preferably, the first coil and the second coil include ceramic encapsulated coils.

[0020] The present invention further selects a toroidal superconducting coil or a ceramic packaged coil, that is, an iron coreless electromagnetic coil, to avoid the introduction of impurities Fe.

[0021] Preferably, the cooling component comprises a water cooling component.

[0022] Preferably, the water-cooling component comprises a crucible with a water-cooling tube provided at the bottom.

[0023] Optionally, the water-cooling component includes a copper crucible with a water-cooling tube at the bottom.

[0024] Preferably, the heating component is arranged obliquely around the top of the smelting chamber shell, and the oblique direction is the heating direction toward the inner cavity of the smelting chamber.

[0025] Preferably, the inclination angle of the heating component is 30° to 60°, for example, it can be 30°, 35°, 40°, 45°, 50°, 55° or 60°.

[0026] The inclination angle refers to the angle between a line on one side of the heating element close to the smelting chamber shell and the horizontal direction.

[0027] Preferably, the heating component comprises an infrared heating element.

[0028] Preferably, the purification device further comprises a gas circulation module.

[0029] Preferably, the gas circulation module comprises a gas supply component and a vacuum pumping component which are arranged outside the outer shell of the smelting chamber.

[0030] The gas supply component of the present invention is used to provide protective gas to the inner cavity of the smelting chamber, so that subsequent smelting is carried out in a protective gas atmosphere, avoiding the introduction of impurities such as O2 and H2O in the air, which may lead to poor purification effect.

[0031] Preferably, the vacuuming component comprises a vacuum pump.

[0032] Preferably, the side wall of the smelting chamber shell is provided with a first air inlet and an air outlet.

[0033] Preferably, a second air inlet is provided on the side wall of the inner cavity of the smelting chamber.

[0034] Preferably, the air supply component is connected to the first air inlet through a pipeline.

[0035] Preferably, the vacuum pumping component is connected to the air outlet through a pipeline.

[0036] Preferably, the first air inlet and the second air inlet are connected through a pipeline.

[0037] Preferably, a gas purification component is provided on the pipeline between the first air inlet and the second air inlet.

[0038] Preferably, the purification device is further provided with a monitoring module.

[0039] The monitoring module of the present invention is used for online real-time monitoring of the melt and performing elemental analysis on it.

[0040] Preferably, the monitoring module comprises a detection component and a control component that are electrically connected.

[0041] Preferably, the detection component is arranged inside the smelting chamber shell.

[0042] Preferably, the detection component includes a LIBS probe.

[0043] Preferably, the control component is arranged outside the smelting chamber shell.

[0044] Taking the purification of high-purity aluminum as an example, the specific method of using the purification device of the present invention is as follows:

[0045] First, the aluminum raw material is placed in the smelting container, and the vacuum pumping component is used to evacuate the inner cavity of the smelting chamber to a vacuum state. Then, the gas supply component is used to fill the inner cavity of the smelting chamber with a protective gas. Subsequently, the aluminum raw material is vacuum-smelted at a high temperature. Then, the magnetic field module is turned on to electromagnetically stir the aluminum melt. Then, the directional solidification module is turned on to directionally solidify the aluminum melt to obtain an aluminum ingot. The aluminum ingot is taken out and a portion of the top of the aluminum ingot is cut off to obtain high-purity aluminum.

[0046] In a second aspect, the present invention provides a method for purifying high-purity aluminum, which is carried out using the purification device described in the first aspect.

[0047] The present invention adopts the purification device of the first aspect to purify high-purity aluminum. The purification device avoids the Fe impurities introduced from the magnetic field of the iron core during the purification process, while improving the migration efficiency of heavy-density impurity elements (such as Fe, Cu and Mn, etc.) and light elements (such as Si) and ultra-low concentration impurities (ppb level), reducing energy consumption, and realizing efficient and low-cost purification of high-purity aluminum of 6N and above. The purification device has a simple structure and is easy to operate.

[0048] Preferably, the purification method comprises the following steps:

[0049] The aluminum raw material is vacuum-melted to obtain aluminum melt, which is then subjected to electromagnetic stirring and directional solidification to obtain aluminum ingots, which are then cut to obtain high-purity aluminum.

[0050] The electromagnetic stirring includes a first electromagnetic stirring and a second electromagnetic stirring performed simultaneously;

[0051] The directional solidification includes solidifying the aluminum melt along a direction from the bottom of the inner cavity of the smelting chamber to the top of the inner cavity of the smelting chamber.

[0052] The purification method described in the present invention adopts the purification device of the first aspect, and sequentially performs vacuum melting, electromagnetic stirring and directional solidification on the aluminum raw material to obtain an aluminum ingot, and selects to perform the first electromagnetic stirring and the second electromagnetic stirring at the same time, and then cuts the aluminum ingot. The various processes work synergistically to avoid the introduction of external impurities, and at the same time, the volatile impurities (such as Zn and Mg), heavy density impurity elements (such as Fe, Cu and Mn, etc.) and light elements (such as Si) and ultra-low concentration impurities (ppb level) in the aluminum raw material are efficiently removed, thereby realizing the purification and continuous production of high-purity aluminum of 6N and above. Moreover, compared with traditional purification methods such as zone melting, the purification method described in the present invention reduces energy consumption by about 40% and shortens the purification time by 50%.

[0053] Preferably, the purity of the aluminum raw material is 4N8 to ≤5N5, for example, it can be 4N8, 4N9, 5N, 5N2 or 5N5.

[0054] Preferably, the impurities of the aluminum raw material include Zn, Mg, Fe, Cu, Mn, Si and B.

[0055] Preferably, the vacuum melting comprises first evacuating the inner cavity of the melting chamber to a vacuum and then introducing a protective gas.

[0056] Preferably, the vacuum degree of the vacuum melting is ≤10 -3 Pa, for example, can be 10 -3 Pa, 10 -4 Pa or 10 -5 Pa et al.

[0057] Preferably, the flow rate of the protective gas is 5 to 30 L / min, for example, 5 L / min, 8 L / min, 10 L / min, 15 L / min, 20 L / min, 25 L / min or 30 L / min.

[0058] Preferably, the protective gas comprises argon and / or nitrogen.

[0059] The argon and / or nitrogen described in the present invention are high-purity argon and / or high-purity nitrogen, which refer to argon and / or nitrogen with O2≤0.1ppm and H2O≤0.5ppm.

[0060] Preferably, the vacuum melting temperature is 720-760°C, for example, 720°C, 730°C, 740°C, 750°C or 760°C.

[0061] Preferably, the vacuum melting time is 3 to 5 hours, for example, 3 hours, 3.5 hours, 4 hours, 4.5 hours or 5 hours.

[0062] Preferably, the magnetic field strength of the first electromagnetic stirring is 0.1-0.5 T, for example, 0.1 T, 0.15 T, 0.2 T, 0.25 T, 0.3 T, 0.35 T, 0.4 T, 0.45 T or 0.5 T.

[0063] Preferably, the frequency of the first electromagnetic stirring is 1 to 5 Hz, for example, 1 Hz, 1.5 Hz, 2 Hz, 2.5 Hz, 3 Hz, 3.5 Hz, 4 Hz, 4.5 Hz or 5 Hz.

[0064] The present invention further prefers that the magnetic field strength of the first electromagnetic stirring is 0.1~0.5T, and the frequency of the first electromagnetic stirring is 1~5Hz. The combination of the two makes the electromagnetic force sufficient but does not generate turbulence, thereby efficiently driving the heavy-density impurities (such as Fe, Cu and Mn, etc.) in the aluminum melt to migrate outward. If the magnetic field strength or frequency of the first electromagnetic stirring is too low, the electromagnetic force is insufficient to effectively drive the heavy-density impurities to migrate outward, resulting in poor purification effect; if the magnetic field strength or frequency of the first electromagnetic stirring is too high, it will cause violent turbulence or secondary disturbance inside the melt, causing the migrated impurities to be drawn into the melt again, resulting in a poor purification effect and increased energy consumption.

[0065] Preferably, the magnetic field intensity of the second electromagnetic stirring is 0.01-0.1 T, for example, it can be 0.01 T, 0.02 T, 0.03 T, 0.04 T, 0.05 T, 0.06 T, 0.07 T, 0.08 T, 0.09 T or 0.1 T.

[0066] Preferably, the frequency of the second electromagnetic stirring is 6-8 Hz, for example, 6 Hz, 6.2 Hz, 6.5 Hz, 6.8 Hz, 7 Hz, 7.2 Hz, 7.5 Hz, 7.8 Hz, or 8 Hz.

[0067] The present invention further prefers that the magnetic field strength of the second electromagnetic stirring is 0.01~0.1T, and the frequency of the second electromagnetic stirring is 6~8Hz. The combination of the two allows the light impurities inside the melt and the heavy impurities migrating outward to migrate upward and be enriched to the top of the melt, and high-purity aluminum is obtained in combination with subsequent cutting treatment; if the magnetic field strength or frequency of the second electromagnetic stirring is low, the efficiency of the upward migration of impurity elements is reduced, and at the same cutting height, the purity of the product is lower. At the same product purity, the cutting height is higher, that is, the loss is greater; if the magnetic field strength or frequency of the second electromagnetic stirring is high, turbulence will be generated inside the melt, thereby causing heavy and dense impurities to be drawn into the interior and mixed with light elements, and the efficiency of upward dispersion is reduced, resulting in a worse purification effect.

[0068] Preferably, the electromagnetic stirring time is 20 to 60 min, for example, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min.

[0069] Preferably, the solidification rate of the directional solidification is 0.5 to 2 mm / min, for example, 0.5 mm / min, 0.8 mm / min, 1 mm / min, 1.2 mm / min, 1.5 mm / min, 1.8 mm / min or 2 mm / min.

[0070] The present invention further prefers that the solidification rate of the directional solidification is 0.5 to 2 mm / min to ensure that the impurities are fully migrated and enriched before solidification, thereby improving the purification effect; if the solidification rate is too fast, the impurities will solidify before they are fully migrated, resulting in the impurities being unable to be fully enriched at the top of the melt and being trapped in the product; if the solidification rate is too slow, the purification efficiency will be reduced and the energy consumption will increase.

[0071] Preferably, the vertical temperature gradient of the directional solidification is 10 to 50°C / cm, for example, it can be 10°C / cm, 15°C / cm, 20°C / cm, 25°C / cm, 30°C / cm, 35°C / cm, 40°C / cm, 45°C / cm or 50°C / cm.

[0072] It is worth noting that the directional solidification described in the present invention is carried out from the bottom of the melt to the top of the melt, and the vertical temperature gradient refers to the difference between the temperature at the top of the melt and the temperature at the bottom of the melt.

[0073] Preferably, the cutting process includes cutting off the top of the aluminum ingot, and the height of the aluminum ingot removed by cutting accounts for 10-15% of the total height of the aluminum ingot, for example, it can be 10%, 11%, 12%, 13%, 14% or 15%.

[0074] In the purification method of the present invention, impurities are concentrated to 10-15% of the top of the aluminum ingot, thereby reducing cutting losses.

[0075] As a further preferred technical solution of the present invention, the purification method comprises the following steps:

[0076] First, the inner cavity of the smelting chamber is evacuated to a vacuum degree of ≤10 -3 Pa, and then a protective gas is introduced at a flow rate of 5 to 30 L / min, after which the aluminum raw material with a purity of 4N8 to 5N5 is vacuum melted at 720 to 760°C for 3 to 5 hours to obtain an aluminum melt, and then the aluminum melt is simultaneously subjected to a first electromagnetic stirring and a second electromagnetic stirring for 20 to 60 minutes, the magnetic field strength of the first electromagnetic stirring being 0.1 to 0.5 T and the frequency being 1 to 5 Hz, the magnetic field strength of the second electromagnetic stirring being 0.01 to 0.1 T and the frequency being 6 to 8 Hz, and then directionally solidified at a solidification rate of 0.5 to 2 mm / min along the direction from the bottom of the inner cavity of the melting chamber to the top of the inner cavity of the melting chamber to obtain an aluminum ingot, the vertical temperature gradient of the directional solidification being 10 to 50°C / cm, and finally the top of the aluminum ingot, which accounts for 10 to 15% of the total height of the aluminum ingot, is cut and removed to obtain high-purity aluminum.

[0077] Compared with the prior art, the present invention has at least the following beneficial effects:

[0078] (1) The purification device provided by the present invention is designed to have a magnetic field module that includes a centrifugal magnetic field region and an axial magnetic field region. The two-level magnetic fields work together to achieve full impurity spectrum control, wherein the centrifugal magnetic field region drives high-density impurity elements to migrate outward, and the axial magnetic field region suppresses melt turbulence and reduces the dispersion of light impurity elements. In combination with a directional solidification module, impurities are enriched in the top unsolidified area, thereby achieving efficient and low-cost purification of high-purity metals of 6N and above, and capable of continuous production of high-purity metal products. The device has a simple structure, is easy to operate, and has low energy consumption.

[0079] (2) The method for purifying high-purity aluminum provided by the present invention adopts the purification device of the first aspect, and sequentially performs vacuum melting on the aluminum raw material, simultaneously performs first electromagnetic stirring and second electromagnetic stirring, and directional solidification to obtain an aluminum ingot, and combines with the subsequent cutting treatment of the top of the aluminum ingot. The various steps work synergistically to avoid the introduction of external impurities, and at the same time, the volatile impurities (such as Zn and Mg), heavy impurity elements (such as Fe, Cu and Mn, etc.) and light elements (such as Si) and ultra-low concentration impurities (ppb level) in the aluminum raw material are efficiently removed, wherein the removal rate of heavy impurity elements is preferably as high as 85% or more, and the removal rate of light impurity elements is preferably as high as 75% or more, thereby realizing the efficient purification and continuous production of 6N and above high-purity aluminum, which is suitable for fields such as semiconductor targets or superconducting devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] Figure 1 1 is a schematic front view of the structure of the purification device provided in Example 1 of the present invention;

[0081] Figure 2 : is a schematic diagram of the magnetic field direction of the magnetic field module in the purification device provided in Example 1 of the present invention, wherein A and B are schematic diagrams of the magnetic field distribution of the centrifugal magnetic field region, and C is a schematic diagram of the magnetic field distribution of the axial magnetic field region;

[0082] Figure 3 This is a distribution diagram of Fe impurity elements in high-purity aluminum obtained in Example 1 of the present invention;

[0083] Figure 4 This is a distribution diagram of Cu impurity elements in high-purity aluminum obtained in Example 1 of the present invention;

[0084] Figure 5 This is a distribution diagram of Si impurity elements in the high-purity aluminum obtained in Example 1 of the present invention;

[0085] In the figure: 1. Melting chamber shell; 2. Melting chamber inner cavity; 3. Alumina crucible; 4. Observation port; 5. Toroidal superconducting coil; 6. First coil; 7. Second coil; 8. Water cooling component; 9. Infrared heating element; 10. Gas supply component; 11. Vacuum pump; 12. First air inlet; 13. Air outlet; 14. Second air inlet; 15. Gas purification component; 16. LIBS probe; 17. Control component. DETAILED DESCRIPTION

[0086] The technical solution of the present invention will be further described below with reference to the accompanying drawings and through specific embodiments. However, the following examples are merely simplified examples of the present invention and do not represent or limit the scope of protection of the present invention. The scope of protection of the present invention shall be subject to the claims.

[0087] 1. Implementation

[0088] Example 1

[0089] This embodiment provides a purification device, such as Figure 1 As shown, the purification device includes a smelting chamber shell 1, a smelting chamber inner cavity 2, an alumina crucible 3 (purity of 99.95%) arranged at the bottom of the smelting chamber inner cavity 2, and a magnetic field module, a directional solidification module, a gas circulation module and a monitoring module arranged in the gap between the smelting chamber shell 1 and the smelting chamber inner cavity 2; an observation port 4 is provided on the top wall of the smelting chamber shell 1;

[0090] The magnetic field module includes a first magnetic field and a second magnetic field; the first magnetic field includes a centrifugal magnetic field region arranged on the outer periphery of the side wall of the inner cavity 2 of the smelting chamber; the centrifugal magnetic field region includes a ring-shaped superconducting coil 5 arranged around the outer periphery of the inner cavity 2 of the smelting chamber; the second magnetic field includes an axial magnetic field region symmetrically arranged between the top of the inner cavity 2 of the smelting chamber and the bottom of the inner cavity 2 of the smelting chamber; the second magnetic field includes a first coil 6 symmetrically arranged on the top of the inner cavity 2 of the smelting chamber and a second coil 7 symmetrically arranged on the bottom of the inner cavity 2 of the smelting chamber;

[0091] The directional solidification module includes a cooling component provided at the bottom of the alumina crucible 3 and a heating component provided along the top circumference of the smelting chamber shell 1; the cooling component includes a water-cooling component 8; the water-cooling component 8 is a copper crucible with a water-cooling tube provided at the bottom; the heating component is provided obliquely around the top of the smelting chamber shell 1, and the oblique direction is the heating direction toward the inner cavity 2 of the smelting chamber, and the inclination angle is 45°; the heating component is an infrared heating element 9;

[0092] The gas circulation module includes a gas supply component 10 and a vacuum pump 11 disposed outside the smelting chamber shell 1; a first gas inlet 12 and a gas outlet 13 are disposed on the side wall of the smelting chamber shell 1; a second gas inlet 14 is disposed on the side wall of the smelting chamber inner cavity 2; the gas supply component 10 is connected to the first gas inlet 12 via a pipeline; the vacuum pump 11 is connected to the gas outlet 13 via a pipeline; the first gas inlet 12 and the second gas inlet 14 are connected via a pipeline; a gas purification component 15 is disposed on the pipeline between the first gas inlet 12 and the second gas inlet 14;

[0093] The monitoring module includes a detection component and a control component 17 that are electrically connected; the detection component is a LIBS probe 16 and is disposed inside the smelting chamber shell 1 ; the control component 17 is disposed outside the smelting chamber shell 1 .

[0094] This embodiment also provides a method for purifying high-purity aluminum, which is performed using the above-mentioned purification device and includes the following steps:

[0095] First, the inner cavity of the smelting chamber is evacuated to a vacuum degree of 10 -3Pa, and then argon (0.08ppm O2, 0.4ppm H2O) is introduced at a flow rate of 20L / min, and then the aluminum raw material with a purity of 5N is vacuum melted at 740°C for 4h to obtain aluminum melt, and then the aluminum melt is simultaneously subjected to the first electromagnetic stirring and the second electromagnetic stirring for 40min, the magnetic field strength of the first electromagnetic stirring is 0.3T and the frequency is 3Hz, and the magnetic field strength of the second electromagnetic stirring is 0.06T and the frequency is 7Hz, and then directionally solidified along the direction from the bottom of the inner cavity 2 of the melting chamber to the top of the inner cavity 2 of the melting chamber at a solidification rate of 1mm / min to obtain an aluminum ingot, the vertical temperature gradient of the directional solidification is 40°C / cm, and finally the top of the aluminum ingot, which accounts for 12% of the total height of the aluminum ingot, is cut and removed to obtain 6N grade high-purity aluminum.

[0096] The impurities and their contents in the aluminum raw material and high-purity aluminum in this embodiment are shown in Table 1;

[0097] Table 1

[0098]

[0099] like Figure 2 As shown in the figure, A and B are schematic diagrams of the magnetic field distribution in the centrifugal magnetic field area, and C is a schematic diagram of the magnetic field distribution in the axial magnetic field area; the direction of the arrow indicates the direction of movement of the melt, i.e., the molten aluminum, under the Lorentz force, i.e., the outer layer spirals and flows stably in the axial direction.

[0100] like Figure 3 As shown in FIG. 1 , it can be seen that in this embodiment, Fe increases sharply in the top 20% region (peak value 50 ppm), and the concentration in the middle region is lower than 0.1 ppm; Figure 4 As shown in FIG. 1 , it can be seen that in this embodiment, Cu suddenly rises in the top 10% region, but the peak value is only 1 ppm, and the concentration in the middle region is also lower than 0.1 ppm; Figure 5 As shown, the Si concentration increases gently (the peak is only 1 ppm).

[0101] Compared with traditional processes, the method described in this example enriches impurities in the top area and combines it with subsequent cutting steps to achieve the preparation of high-purity aluminum, and the cutting loss is greatly reduced.

[0102] Example 2

[0103] This embodiment provides a purification device, comprising a smelting chamber shell, a smelting chamber inner cavity, an alumina crucible (with a purity of 99.98%) disposed at the bottom of the smelting chamber inner cavity, and a magnetic field module, a directional solidification module, a gas circulation module, and a monitoring module disposed in a gap between the smelting chamber shell and the smelting chamber inner cavity.

[0104] The magnetic field module includes a first magnetic field and a second magnetic field; the first magnetic field includes a centrifugal magnetic field region arranged on the outer periphery of the inner wall of the smelting chamber; the centrifugal magnetic field region includes a ring-shaped superconducting coil arranged around the outer periphery of the inner wall of the smelting chamber; the second magnetic field includes an axial magnetic field region symmetrically arranged between the top and bottom of the inner cavity of the smelting chamber; a first coil symmetrically arranged on the top and a second coil symmetrically arranged on the bottom of the inner cavity of the smelting chamber;

[0105] The directional solidification module includes a cooling component provided at the bottom of the alumina crucible and a heating component provided along the circumference of the top of the smelting chamber shell; the cooling component includes a water-cooling component; the water-cooling component is a copper crucible with a water-cooling tube provided at the bottom; the heating component is provided obliquely around the top of the smelting chamber shell, with the heating direction being toward the inner cavity of the smelting chamber, and the inclination angle is 30°; the heating component is an infrared heating element;

[0106] The gas circulation module includes a gas supply component and a vacuum pump disposed outside the smelting chamber shell; a first gas inlet and a gas outlet are disposed on a side wall of the smelting chamber shell; a second gas inlet is disposed on a side wall of the smelting chamber inner cavity; the gas supply component is connected to the first gas inlet via a pipeline; the vacuum pump is connected to the gas outlet via a pipeline; the first gas inlet and the second gas inlet are connected via a pipeline; a gas purification component is disposed on the pipeline between the first gas inlet and the second gas inlet;

[0107] The monitoring module includes a detection component and a control component that are electrically connected; the detection component is a LIBS probe and is arranged inside the smelting chamber shell; the control component is arranged outside the smelting chamber shell.

[0108] This embodiment also provides a method for purifying high-purity aluminum, which is performed using the above-mentioned purification device and includes the following steps:

[0109] First, the inner cavity of the smelting chamber is evacuated to a vacuum degree of 10 -4Pa, and then argon (0.06ppm O2, 0.5ppm H2O) is introduced at a flow rate of 10L / min, and then the aluminum raw material with a purity of 4N8 is vacuum melted at 720°C for 5h to obtain aluminum melt, and then the aluminum melt is simultaneously subjected to the first electromagnetic stirring and the second electromagnetic stirring for 20min, the magnetic field strength of the first electromagnetic stirring is 0.5T and the frequency is 5Hz, and the magnetic field strength of the second electromagnetic stirring is 0.1T and the frequency is 8Hz, and then directionally solidified in the direction from the bottom of the inner cavity of the melting chamber to the top of the melting cavity at a solidification rate of 2mm / min to obtain an aluminum ingot, the vertical temperature gradient of the directional solidification is 50°C / cm, and finally the top of the aluminum ingot, which accounts for 10% of the total height of the aluminum ingot, is cut and removed to obtain 6N grade high-purity aluminum.

[0110] The impurities and their contents in the aluminum raw material and high-purity aluminum in this embodiment are shown in Table 2;

[0111] Table 2

[0112]

[0113] Example 3

[0114] This embodiment provides a purification device, comprising a smelting chamber shell, a smelting chamber inner cavity, an alumina crucible (with a purity of 99.96%) disposed at the bottom of the smelting chamber inner cavity, and a magnetic field module, a directional solidification module, a gas circulation module, and a monitoring module disposed in a gap between the smelting chamber shell and the smelting chamber inner cavity; an observation port is disposed on the top wall of the smelting chamber shell;

[0115] The magnetic field module includes a first magnetic field and a second magnetic field; the first magnetic field includes a centrifugal magnetic field region arranged on the outer periphery of the inner wall of the smelting chamber; the centrifugal magnetic field region includes a ring-shaped superconducting coil arranged around the outer periphery of the inner wall of the smelting chamber; the second magnetic field includes an axial magnetic field region symmetrically arranged between the top and bottom of the inner cavity of the smelting chamber; a first coil symmetrically arranged on the top and a second coil symmetrically arranged on the bottom of the inner cavity of the smelting chamber;

[0116] The directional solidification module includes a cooling component provided at the bottom of the alumina crucible and a heating component provided along the circumference of the top of the smelting chamber shell; the cooling component includes a water-cooling component; the water-cooling component is a copper crucible with a water-cooling tube provided at the bottom; the heating component is provided obliquely around the top of the smelting chamber shell, with the heating direction being toward the inner cavity of the smelting chamber, and the inclination angle is 50°; the heating component is an infrared heating element;

[0117] The gas circulation module includes a gas supply component and a vacuum pump disposed outside the smelting chamber shell; a first gas inlet and a gas outlet are disposed on a side wall of the smelting chamber shell; a second gas inlet is disposed on a side wall of the smelting chamber inner cavity; the gas supply component is connected to the first gas inlet via a pipeline; the vacuum pump is connected to the gas outlet via a pipeline; the first gas inlet and the second gas inlet are connected via a pipeline; a gas purification component is disposed on the pipeline between the first gas inlet and the second gas inlet;

[0118] The monitoring module includes a detection component and a control component that are electrically connected; the detection component is a LIBS probe and is arranged inside the smelting chamber shell; the control component is arranged outside the smelting chamber shell.

[0119] This embodiment also provides a method for purifying high-purity aluminum, which is performed using the above-mentioned purification device and includes the following steps:

[0120] First, the inner cavity of the smelting chamber is evacuated to a vacuum degree of 10 -3 Pa, and then nitrogen (0.05ppm O2, 0.3ppm H2O) is introduced at a flow rate of 30L / min, and then the aluminum raw material with a purity of 5N5 is vacuum melted at 760°C for 3h to obtain aluminum melt, and then the aluminum melt is simultaneously subjected to the first electromagnetic stirring and the second electromagnetic stirring for 60min, the magnetic field strength of the first electromagnetic stirring is 0.1T and the frequency is 1Hz, the magnetic field strength of the second electromagnetic stirring is 0.01T and the frequency is 6Hz, and then directionally solidified in the direction from the bottom of the inner cavity of the melting chamber to the top of the melting cavity at a solidification rate of 0.5mm / min to obtain an aluminum ingot, the vertical temperature gradient of the directional solidification is 10°C / cm, and finally the top of the aluminum ingot, which accounts for 15% of the total height of the aluminum ingot, is cut and removed to obtain 6N grade high-purity aluminum.

[0121] The impurities and their contents in the aluminum raw material and high-purity aluminum in this embodiment are shown in Table 3;

[0122] Table 3

[0123]

[0124] Example 4

[0125] This embodiment provides a purification device, which is consistent with the embodiment 1 except that the gas supply component is not provided.

[0126] This embodiment also provides a method for purifying high-purity aluminum. Except for using the purification device provided in this embodiment, the rest of the purification method is the same as that of Example 1.

[0127] In this embodiment, since the purification device is not provided with a gas supply component, argon gas cannot be introduced to provide an argon atmosphere, resulting in the possibility of introducing a small amount of O2 and / or H2O in the air during the smelting process, resulting in poor purification effect.

[0128] Example 5

[0129] This embodiment provides a method for purifying high-purity aluminum. The purification method is the same as that of Example 1, except that the magnetic field intensity of the first electromagnetic stirring is 0.6 T.

[0130] Example 6

[0131] This embodiment provides a method for purifying high-purity aluminum. The purification method is the same as that of Example 1, except that the magnetic field intensity of the first electromagnetic stirring is 0.08 T.

[0132] Example 7

[0133] This embodiment provides a method for purifying high-purity aluminum. The purification method is the same as that of Example 1, except that the magnetic field intensity of the second electromagnetic stirring is 0.12 T.

[0134] Example 8

[0135] This embodiment provides a method for purifying high-purity aluminum. The purification method is the same as that of Example 1, except that the magnetic field intensity of the second electromagnetic stirring is 0.008 T.

[0136] Example 9

[0137] This embodiment provides a method for purifying high-purity aluminum. The purification method is the same as that of Example 1 except that the solidification rate is 2.2 mm / min.

[0138] Example 10

[0139] This embodiment provides a method for purifying high-purity aluminum. The purification method is the same as that of Example 1 except that the solidification rate is 0.3 mm / min.

[0140] 2. Comparative Example

[0141] Comparative Example 1

[0142] This comparative example provides a purification device and a purification method. The purification device is the same as Example 1 except that only the first magnetic field is set without the second magnetic field, and the purification method is correspondingly adjusted to only perform the first electromagnetic stirring without the second electromagnetic stirring.

[0143] Comparative Example 2

[0144] This comparative example provides a purification device and a purification method. The purification device is the same as Example 1 except that only the second magnetic field is set without the first magnetic field, and the purification method is correspondingly adjusted to only perform the second electromagnetic stirring without the first electromagnetic stirring.

[0145] Comparative Example 3

[0146] This comparative example provides a method for purifying high-purity aluminum. The purification method is the same as Example 1, except that the first electromagnetic stirring and the second electromagnetic stirring are not performed simultaneously, but the first electromagnetic stirring is performed for 20 minutes before the second electromagnetic stirring is performed for 20 minutes.

[0147] Comparative Example 4

[0148] This comparative example provides a method for purifying high-purity aluminum. The purification method is the same as Example 1, except that the first electromagnetic stirring and the second electromagnetic stirring are not performed simultaneously, but the second electromagnetic stirring is performed for 20 minutes before the first electromagnetic stirring is performed for 20 minutes.

[0149] 3. Test and its results

[0150] The high-purity aluminum obtained in the above examples and comparative examples was analyzed for impurity elements using a laser-induced breakdown spectrometer (Applied Spectra, J200 LIBS, USA). The removal rates of Fe, Cu, Mn, and Si impurity elements were calculated according to the following formulas. The results are shown in Table 4.

[0151]

[0152] Table 4

[0153] project Fe removal rate Cu removal rate Mn removal rate Si removal rate Example 1 99％ 99％ 90％ 80％ Example 2 95％ 95％ 85％ 75％ Example 3 95％ 95％ 85％ 75％ Example 4 90％ 90％ 70％ 70％ Example 5 90％ 90％ 65％ 70％ Example 6 88％ 85％ 65％ 65％ Example 7 88％ 75％ 60％ 65％ Example 8 85％ 60％ 50％ 60％ Example 9 85％ 50％ 40％ 60％ Example 10 70％ 40％ 30％ 55％ Comparative Example 1 50％ 20％ 20％ 40％ Comparative Example 2 45％ 25％ 25％ 45％ Comparative Example 3 55％ 45％ 45％ 50％ Comparative Example 4 48％ 23％ 30％ 55％

[0154] From the data in Table 4 we can see that:

[0155] (1) It can be seen from Examples 1 to 3 that the purification device provided by the present invention and the method for purifying high-purity aluminum using the same achieve efficient removal of heavy impurity elements and light impurity elements, wherein the removal rate of heavy impurity elements (Fe, Cu and Mn) is as high as over 85%, and the removal rate of light impurity elements (Si) is as high as over 75%, thereby producing 6N grade high-purity aluminum.

[0156] (2) From Example 1 and Example 4, it can be seen that the purification device described in Example 4 is not provided with a gas supply component, resulting in the smelting and purification process not being carried out in an argon protective atmosphere, resulting in a decrease in the removal rate of heavy impurity elements and light impurity elements. This shows that the present invention further preferably provides a gas supply component to further improve the purification effect.

[0157] (3) Combining Example 1 with Examples 5 to 8, it can be seen that the magnetic field strength of the first electromagnetic stirring in Example 5 or Example 6 is too large or too small, resulting in a decrease in the removal rate of the corresponding impurity elements; the magnetic field strength of the second electromagnetic stirring in Example 7 or Example 8 is too large or too small, also resulting in a decrease in the removal rate of the corresponding impurity elements. This shows that the present invention further prefers that the magnetic field strength of the first electromagnetic stirring is 0.1 to 0.5 T, and further prefers that the magnetic field strength of the second electromagnetic stirring is 0.01 to 0.1 T. The combination of the two further improves the purification effect of high-purity aluminum.

[0158] (4) Combining Example 1 with Example 9 and Example 10, it can be seen that the solidification rate of the directional solidification described in Example 9 or Example 10 is too fast or too slow, which leads to a decrease in the removal rate of the corresponding impurity elements. This shows that the present invention further prefers that the solidification rate of the directional solidification is 0.5 to 2 mm / min, which further ensures the enrichment of the impurity elements at the top of the aluminum ingot, thereby improving the purity of the final product high-purity aluminum.

[0159] (5) From Example 1 and Comparative Examples 1 to 4, it can be seen that since only the first magnetic field is set in Comparative Example 1 and only the second magnetic field is set in Comparative Example 2, it is impossible to control the entire impurity spectrum, and the removal rates of heavy-density impurity elements and light impurity elements are both reduced; since the first electromagnetic stirring and the second electromagnetic stirring in Comparative Examples 3 and 4 are not carried out simultaneously, but are carried out independently in a sequence, the removal rates of heavy-density impurity elements and light impurity elements are both reduced; this shows that the present invention selects the magnetic field module in the purification device to include the first magnetic field and the second magnetic field, and in the subsequent purification method, the first electromagnetic stirring and the second electromagnetic stirring are selected to be carried out simultaneously, and the two work together to achieve control of the entire impurity spectrum and improve the purification effect.

[0160] In summary, the purification device of the present invention and the method for purifying high-purity aluminum using the same are designed to include a centrifugal magnetic field region and an axial magnetic field region at the same time by designing the magnetic field module, and performing the first electromagnetic stirring and the second electromagnetic stirring at the same time. The two-stage magnetic field works synergistically to achieve full impurity spectrum control, and combines directional solidification to enrich the impurity elements to the top of the aluminum ingot, and subsequently cuts and removes the impurity-enriched part on the top of the aluminum ingot, thereby achieving low-cost purification of high-purity aluminum of 6N and above.

[0161] The applicant declares that the above is only a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention fall within the scope of protection and disclosure of the present invention.

Claims

1. A purification device, characterized in that: The purification device includes a smelting chamber shell, a smelting chamber inner cavity, a smelting container arranged at the bottom of the smelting chamber inner cavity, and a magnetic field module and a directional solidification module arranged in the gap between the smelting chamber shell and the smelting chamber inner cavity; The magnetic field module includes a first magnetic field and a second magnetic field; the first magnetic field includes a centrifugal magnetic field region arranged on the outer periphery of the side wall of the inner cavity of the smelting chamber; the second magnetic field includes an axial magnetic field region symmetrically arranged between the top of the inner cavity of the smelting chamber and the bottom of the inner cavity of the smelting chamber; The directional solidification module includes a cooling component arranged at the bottom of the smelting container and a heating component arranged along the circumference of the top of the smelting chamber shell.

2. The purification device according to claim 1, characterized in that The centrifugal magnetic field region includes an annular superconducting coil arranged around the outer wall of the inner cavity of the smelting chamber; Preferably, the axial magnetic field region comprises a first coil symmetrically arranged at the top of the inner cavity of the smelting chamber and a second coil at the bottom of the inner cavity of the smelting chamber; Preferably, the cooling component comprises a water cooling component; Preferably, the heating component is arranged obliquely around the top of the smelting chamber shell, and the oblique direction is the heating direction toward the inner cavity of the smelting chamber.

3. The purification device according to claim 1 or 2, characterized in that The purification device also includes a gas circulation module; Preferably, the gas circulation module comprises a gas supply component and a vacuum pumping component arranged outside the smelting chamber shell; Preferably, the side wall of the smelting chamber shell is provided with a first air inlet and an air outlet; Preferably, a second air inlet is provided on the side wall of the inner cavity of the smelting chamber; Preferably, the air supply component is connected to the first air inlet through a pipeline; Preferably, the vacuum pumping component is connected to the air outlet through a pipeline; Preferably, the first air inlet and the second air inlet are connected via a pipeline; Preferably, a gas purification component is provided on the pipeline between the first air inlet and the second air inlet.

4. The purification device according to any one of claims 1 to 3, characterized in that: The purification device is also provided with a monitoring module; Preferably, the monitoring module comprises a detection component and a control component that are electrically connected; Preferably, the detection component is arranged inside the smelting chamber shell; Preferably, the control component is arranged outside the smelting chamber shell.

5. A method for purifying high-purity aluminum, characterized in that: The purification method is carried out using the purification device according to any one of claims 1 to 4.

6. The purification method according to claim 5, characterized in that The purification method comprises the following steps: The aluminum raw material is vacuum-melted to obtain aluminum melt, which is then subjected to electromagnetic stirring and directional solidification to obtain aluminum ingots, which are then cut to obtain high-purity aluminum. The electromagnetic stirring includes a first electromagnetic stirring and a second electromagnetic stirring performed simultaneously; The directional solidification includes solidifying the aluminum melt along a direction from the bottom of the inner cavity of the smelting chamber to the top of the inner cavity of the smelting chamber.

7. The purification method according to claim 5 or 6, characterized in that The purity of the aluminum raw material is 4N8 to 5N5; Preferably, the impurities of the aluminum raw material include Zn, Mg, Fe, Cu, Mn, Si and B; Preferably, the vacuum melting comprises first evacuating the inner cavity of the melting chamber to a vacuum and then introducing a protective gas; Preferably, the vacuum degree of the vacuum melting is ≤10 -3 Pa; Preferably, the flow rate of the protective gas is 5 to 30 L / min; Preferably, the protective gas comprises argon and / or nitrogen; Preferably, the vacuum melting temperature is 720-760°C; Preferably, the vacuum melting time is 3 to 5 hours.

8. The purification method according to claims 5 to 7, characterized in that: The magnetic field strength of the first electromagnetic stirring is 0.1 to 0.5 T; Preferably, the frequency of the first electromagnetic stirring is 1 to 5 Hz; Preferably, the magnetic field intensity of the second electromagnetic stirring is 0.01 to 0.1 T; Preferably, the frequency of the second electromagnetic stirring is 6 to 8 Hz; Preferably, the electromagnetic stirring time is 20 to 60 minutes.

9. The purification method according to any one of claims 5 to 8, characterized in that: The solidification rate of the directional solidification is 0.5 to 2 mm / min; Preferably, the vertical temperature gradient of the directional solidification is 10 to 50°C / cm; Preferably, the cutting process includes cutting and removing the top of the aluminum ingot, and the height of the aluminum ingot removed by cutting accounts for 10-15% of the total height of the aluminum ingot.

10. The purification method according to any one of claims 6 to 9, characterized in that: The purification method comprises the following steps: First, evacuate the inner chamber of the smelting chamber to a vacuum degree of ≤10 -3 Pa, and then a protective gas is introduced at a flow rate of 5 to 30 L / min, after which the aluminum raw material with a purity of 4N8 to 5N5 is vacuum melted at 720 to 760°C for 3 to 5 hours to obtain an aluminum melt, and then the aluminum melt is simultaneously subjected to a first electromagnetic stirring and a second electromagnetic stirring for 20 to 60 minutes, the magnetic field strength of the first electromagnetic stirring being 0.1 to 0.5 T and the frequency being 1 to 5 Hz, the magnetic field strength of the second electromagnetic stirring being 0.01 to 0.1 T and the frequency being 6 to 8 Hz, and then directionally solidified at a solidification rate of 0.5 to 2 mm / min along the direction from the bottom of the inner cavity of the melting chamber to the top of the inner cavity of the melting chamber to obtain an aluminum ingot, the vertical temperature gradient of the directional solidification being 10 to 50°C / cm, and finally the top of the aluminum ingot, which accounts for 10 to 15% of the total height of the aluminum ingot, is cut and removed to obtain high-purity aluminum.

Images