A composite treatment method for reducing Fe / Si impurities in high-purity aluminum using rare earth alloying and segregation.

Abstract

This invention belongs to the field of aluminum refining technology and discloses a composite treatment method for reducing Fe / Si impurities in high-purity aluminum using rare earth alloying and segregation. The composite treatment method includes: 1) preparing a rare earth-pure aluminum mixed melt from pure aluminum raw material and an Al-RE rare earth master alloy; 2) subjecting the mixed melt to gradient cooling and heat preservation treatment; 3) performing segregation treatment on the mixed melt; wherein RE in the Al-RE rare earth master alloy is Y and / or Yb. This invention effectively removes Fe and Si from high-purity aluminum raw material using rare earth elements Y and Yb, while also promoting precipitate sedimentation by effectively reducing melt viscosity; Y and Yb elements are more easily removed from aluminum melt using segregation. The method of this invention can purify 2N8 industrial pure aluminum to 3N5 level and 4N6 high-purity aluminum to 5N level. This invention is simple, easy to implement, and has low production costs.

Description

Technical Field

[0001] This invention relates to the field of aluminum purification technology, specifically to a composite treatment method that utilizes rare earth alloying and segregation to reduce Fe / Si impurities in high-purity aluminum. Background Technology

[0002] High-purity aluminum (generally with a purity greater than 99.8%) has wide applications in industries such as semiconductors, electrical and electronic engineering, and transportation due to its excellent electrical and thermal conductivity, processability, and relatively weak magnetic permeability. Over 75% of high-purity aluminum with a purity of 3N8-4N8 (99.98%-99.998%) is used in the production of electrolytic aluminum foil, such as the cathode foil of electrolytic capacitors which uses 99.998% pure aluminum, and the anode foil which uses 99.95% pure aluminum. Aluminum with a purity of 5N+ (greater than 99.999%) is mainly used in the semiconductor industry, such as in semiconductor sputtering targets. The price of aluminum varies significantly depending on its purity, and there is currently a broad market demand for high-purity aluminum, especially high-purity aluminum with a purity of 5N and above. Developing technologies for the efficient production of 5N high-purity aluminum has significant economic benefits and can address the urgent market demand for high-purity aluminum.

[0003] Currently, the main methods for producing high-purity aluminum include the three-layer electrolysis process and the segregation process based on solute redistribution during solidification. The three-layer electrolysis refining method is highly efficient and suitable for mass production, but it consumes a lot of energy and poses serious environmental problems due to the use of fluoride electrolytes; the highest purity currently achievable is 4N. The segregation method utilizes the difference in solubility of impurities in the molten aluminum to remove impurities with an equilibrium distribution coefficient k < 1. The smaller the k value, the easier it is to remove impurities, but it cannot remove impurities with k > 1. The segregation method is further divided into stepwise crystallization, directional solidification, and zone melting.

[0004] Stepwise crystallization is currently the main production technology for high-purity aluminum, and it has achieved mass production with advantages such as low energy consumption and environmental friendliness. However, the production process is long and inefficient. Chinese patent application CN118256736A discloses a purification device and a process for preparing 5N high-purity aluminum based on stepwise crystallization. The basic implementation path of the disclosed device is that the aluminum liquid is cooled and crystallized in a purification container with longitudinal movement at the bottom, and the solid aluminum is scraped off by a scraper to achieve purification. However, this patent only discloses a device based on the stepwise crystallization method and does not involve specific purification effects. The principle of directional solidification is to control the heat flow to form a temperature gradient, so that the aluminum crystals grow and are purified in a directional manner. Chinese patent CN102277505A discloses a method for purifying high-purity aluminum by directional solidification and its smelting furnace. The purification process includes four steps: material selection, smelting, solidification purification, and finished product acquisition. The rate control of the directional solidification process is strict, and after each crystallization, it is necessary to cool and sample, and then reheat for further purification, which is not conducive to mass production and poses a challenge for large-scale production. The aforementioned patents mainly disclose purification devices, but do not cover how to efficiently reduce the content of key impurities Fe and Si in pure aluminum based on melt processing.

[0005] The principle of zone melting is that aluminum rods are locally melted, and the melting zones are moved sequentially. The solute is redistributed during solidification, removing it into the melt and thus achieving purification. Chinese patent application CN110819823A discloses a method for preparing high-purity aluminum by directional zone melting. This patent application optimizes impurity removal efficiency by controlling the moving speed of the quartz tube, etc. Zone melting can obtain high-purity samples, but the purification process requires repeated melting, resulting in low purification yield per furnace and high energy consumption. To ensure solidification is completed under equilibrium conditions, the cooling rate must be controlled at a very low level. Therefore, this method has low production efficiency and is not suitable for mass production.

[0006] In the refining and production of aluminum alloys, the removal of Fe / Si impurities is crucial. When preparing high-purity aluminum using the segregation method, segregation alone is insufficient to efficiently remove Fe and Si impurities from the molten aluminum, resulting in products with impurity content failing to meet specifications. To address this issue, this invention involves rare-earth alloying treatment of the pure aluminum melt, followed by further segregation to reduce the Fe and Si impurity content, thereby achieving further purification. Summary of the Invention

[0007] To overcome the shortcomings and deficiencies of existing technologies, the present invention aims to provide a composite treatment method for reducing Fe / Si impurities in high-purity aluminum using rare earth alloying and segregation. This invention utilizes rare earth alloying and segregation to efficiently remove impurities such as Fe and Si from high-purity aluminum, further improving the purity of the aluminum.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] A composite treatment method for reducing Fe / Si impurities in high-purity aluminum using rare earth alloying and segregation includes the following steps:

[0010] 1) Prepare a rare earth-pure aluminum mixed melt by combining pure aluminum raw material and Al-RE rare earth master alloy;

[0011] 2) The mixed melt is subjected to gradient cooling and heat preservation treatment;

[0012] 3) Segregation treatment of the mixed melt.

[0013] The pure aluminum raw material has an Al content of ≥99.8%, specifically 2N8 industrial pure aluminum or 4N6 high-purity aluminum;

[0014] In the Al-RE rare earth master alloy, RE is Y and / or Yb;

[0015] The Al-RE rare earth master alloy is an Al-Y rare earth master alloy and / or an Al-Yb rare earth master alloy.

[0016] Al-Y rare earth master alloy is Al-10wt%Y, and Al-Yb rare earth master alloy is Al-10wt%Yb.

[0017] The addition amount of rare earth element (RE) meets the following conditions: the addition amount of Y is 1.5 to 50 times the Fe or Si content in the pure aluminum raw material; when the Fe content in the pure aluminum raw material is ≥ the Si content, the addition amount of Y is 1.5 to 50 times the Fe content in the pure aluminum raw material; when the Fe content in the pure aluminum raw material is < the Si content, the addition amount of Y is 1.5 to 50 times the Si content in the pure aluminum raw material.

[0018] The amount of Yb added is 1.5 to 50 times the Fe or Si content in the pure aluminum raw material; when the Fe content in the pure aluminum raw material is ≥ the Si content, the amount of Yb added is 1.5 to 50 times the Fe content in the pure aluminum raw material; when the Fe content in the pure aluminum raw material is < the Si content, the amount of Yb added is 1.5 to 50 times the Si content in the pure aluminum raw material.

[0019] When the Al content in the pure aluminum raw material is ≥99.8%, the Fe or Si content is ≥100ppm and Fe<0.2%, Si<0.1%, and the total impurities are <0.2%, the amount of rare earth RE added is 1.5 to 8 times the Fe or Si content in the pure aluminum raw material; when the Fe or Si content is <100ppm, the amount of rare earth RE added is 8 to 50 times the Fe or Si content in the pure aluminum raw material.

[0020] Specifically, when the pure aluminum raw material is 2N8 industrial pure aluminum, the amount of rare earth RE added is 1.5 to 8 times the Fe or Si content in the pure aluminum raw material, preferably 1.5 to 5 times;

[0021] When the pure aluminum raw material is 4N6 high-purity aluminum, the amount of rare earth RE added is 8 to 50 times the Fe or Si content in the pure aluminum raw material, preferably 8 to 40 times.

[0022] Step 1) involves melting pure aluminum raw material and Al-RE rare earth master alloy, mixing them thoroughly, and holding the mixture at a constant temperature to obtain a rare earth-pure aluminum mixed melt. The melting temperature is 750–800℃. The mixing process involves melting high-purity aluminum and then stirring it thoroughly; the stirring time is 5–10 minutes; and the mixture is held at a constant temperature for 3–60 minutes.

[0023] Before adding Al-RE rare earth master alloy, a B-containing master alloy, such as Al-B master alloy, can be added to the molten pure aluminum raw material.

[0024] The gradient cooling and holding process described in step 2) involves first lowering the melt temperature to 710-730℃ at a rate of 1-2.5℃ / min and holding it for 60-120min, then lowering the melt temperature to 675-685℃ at a rate of 1-2.5℃ / min and holding it for 60-120min, and finally maintaining the melt temperature at 675-685℃.

[0025] The segregation treatment mentioned in step 3) refers to cooling the melt on one side or above after heating is stopped, causing the melt to crystallize and form segregation.

[0026] The segregation treatment described in step 3) specifically refers to turning off the heating device of the segregation apparatus, placing a cover above the melt inside the cavity of the segregation apparatus, and placing a cooling device above the cover. After being cooled by the cooling device, the melt in contact with the cover begins to crystallize from top to bottom, forming segregation. The segregation time is 5 to 15 minutes.

[0027] After the segregation process is completed, the aluminum ingot is cooled, removed, and the composition of different parts of the ingot is tested. The parts with more impurities are removed to obtain the desired pure aluminum.

[0028] The 2N8 industrial pure aluminum contains the following components by mass:

[0029] Fe < 0.2%

[0030] Si < 0.1%

[0031] Al>99.8%

[0032] The balance is for other impurities, and the total amount of impurities is <0.2%.

[0033] The 4N6 high-purity aluminum contains the following components by mass:

[0034] Fe < 5ppm

[0035] Si < 8ppm

[0036] Al>99.996%

[0037] The balance is other impurities, and the total amount of impurities is <40ppm.

[0038] The 5N high-purity aluminum of this invention contains the following components by mass:

[0039] Fe < 2.5 ppm

[0040] Si < 2.5 ppm

[0041] Al>99.999%

[0042] The balance is other impurities, and the total amount of impurities is <10ppm.

[0043] The principle of this invention:

[0044] Precipitation reaction principle: Y and Yb have strong chemical reactivity and a strong affinity for Fe and Si. In Al melt, they readily react with Fe and Si impurities to form the stable compound AlFeSiRE phase. Within a certain range, the more rare earth elements added, the more AlFeSiRE phase is formed. Excess Y and Yb elements can react fully with Fe and Si impurities in the Al melt. The density of the AlFeSiRE phase is higher than that of the Al melt, thus causing precipitation that deposits at the bottom of the melt.

[0045] The principle behind the reduction in melt viscosity promoting precipitation is as follows: When Y and Yb enter the aluminum melt, they alter the atomic structure, making the atomic packing more loose. This reduces the interatomic forces, leading to lower internal friction during melt flow, which macroscopically manifests as a decrease in melt viscosity. Furthermore, rare earth elements can form new chemical bonds with aluminum atoms. These new bonds differ from aluminum-aluminum bonds, thus altering the energy distribution within the melt. These rare earth-aluminum bonds result in relatively weaker atomic bonds, allowing for easier relative atomic displacement and further reducing melt viscosity. Additionally, Y and Yb may adsorb at grain boundaries and other interfaces in the aluminum melt. This adsorption reduces interfacial energy, making the melt's microstructure more stable and improving its fluidity, ultimately resulting in a decrease in melt viscosity.

[0046] According to Stokes's Law:

[0047]

[0048] Where ν is the settling velocity of the particles, r is the particle radius, ρ is the particle density, ρ0 is the fluid density, g is the gravitational acceleration, and η is the fluid viscosity. With other conditions such as particle size, melt density, and gravitational acceleration remaining essentially constant, lower viscosity results in higher settling velocities, making it easier for the precipitate to settle to the bottom of the melt. Low-viscosity melts allow precipitates to pass through the melt more easily, making them less susceptible to viscous forces and facilitating the separation of precipitates from the melt using simple physical methods (such as static settling). Furthermore, low-viscosity melts make it easier for precipitate particles to collide and aggregate; once these aggregates form larger clusters, their settling velocity further increases.

[0049] Segregation Principle: Segregation, also known as solidification purification, purifies aluminum based on the difference in solubility of impurity elements in the liquid and solid phases. Segregation effectively removes impurity elements with an equilibrium partition coefficient less than 1 in aluminum, and the smaller the partition coefficient, the easier the impurity element is to remove. The equilibrium partition coefficients of rare earth elements Y and Yb in Al are both less than 0.003, while those of Fe and Si are 0.023 and 0.1, respectively. The partition coefficients of Y and Yb in Al are approximately one-tenth that of Fe and Si; therefore, segregation can efficiently remove excess rare earth elements (Y and Yb).

[0050] Process Characteristics: This invention removes difficult-to-remove Fe and Si impurities by adding rare earth elements (Y and Yb) during the segregation process for preparing high-purity aluminum. This ensures effective removal of Fe and Si impurities without introducing other impurities. Excess Y and Yb can fully contact and react with Fe and Si elements in the aluminum melt, forming a stable AlFeSiRE phase that precipitates at the bottom of the melt. Impurities are removed by cutting off the bottom of the sample after solidification. The intermediate heat treatment processes, such as holding and cooling, allow sufficient time for Y and Yb to react with Fe and Si impurities in the melt, and for the generated AlFeSiRE phase precipitate to settle to the bottom, thereby improving the removal efficiency of Fe and Si impurities. The addition of rare earth elements also effectively reduces the viscosity of the melt, further promoting the sedimentation of the precipitate phase.

[0051] Furthermore, excess Y and Yb have a small equilibrium distribution coefficient in the aluminum melt, and can be effectively removed in subsequent processes using segregation. Upon cooling, primary crystals begin to crystallize at the low-temperature contact points with the melt. As time increases, the small primary crystals at the contact points gradually aggregate to form larger crystals. The crystals grow gradually from top to bottom along the direction of temperature transfer. Simultaneously, the impurity-containing liquid between the crystal lattices is squeezed into the mother liquor below, thus separating the high-purity solid layer from the impurity-containing liquid layer. This method for removing Fe and Si impurities is suitable for aluminum purification via segregation. Compared to the traditional single segregation process, adding rare earth elements can more effectively remove Fe and Si impurities, requires less amount of rare earth elements, has lower costs, and the addition process is simple and does not introduce other impurities.

[0052] Compared with existing separate segregation processes, the present invention has the following outstanding advantages and beneficial effects:

[0053] (1) This invention proposes a method for preparing high-purity aluminum that can remove key impurity elements (Fe and Si) and reduce melt viscosity, and can also effectively remove added elements through segregation.

[0054] (2) The present invention micro-alloys rare earth (Y / Yb) and then performs segregation solidification, which can efficiently remove Fe / Si impurities in pure aluminum melt and ensure that the content of other impurity elements meets the requirements. It can purify 2N8 industrial pure aluminum to 3N5 level and 4N6 high-purity aluminum to 5N level.

[0055] (3) This invention effectively removes impurity elements with a balance distribution coefficient of less than 1 from high-purity aluminum raw materials through segregation method, effectively removes key impurities Fe and Si through the addition of rare earth aluminum alloy, and achieves efficient removal of impurity elements from raw materials through gradient heat preservation treatment so that rare earth intermediate alloy reacts fully with Fe and Si and settles.

[0056] (4) The present invention has a relatively simple preparation process, does not require the application of other coarse purification materials, does not require the use of complex equipment, has low cost and energy consumption, and can be used for large-scale mass production of 5N ultra-high purity aluminum for the semiconductor industry. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the main cross-sectional structure of the segregation furnace used in this invention; 1-inlet, 2-outlet, 3-cooling copper tube, 4-graphite cover, 5-graphite crucible, 6-heating coil, 7-316 stainless steel sleeve, 8-insulating asbestos, 9-support frame, 10-quartz tube, 11-lifting platform, 12-aluminum melt.

[0058] Figure 2This is a schematic diagram of sample cutting; 10 represents height 1, 30 represents height 3, 50 represents height 5, and 90 represents height 9.

[0059] Figure 3 The removal rates of Fe impurities at different heights were measured for samples from Comparative Examples 2-3 and Examples 1-2.

[0060] Figure 4 The removal rates of Si impurities at different heights are shown for Comparative Examples 2-3 and Examples 1-2.

[0061] Figure 5 The removal rates of Fe impurities at different heights were measured for samples from Comparative Examples 5-7 and Examples 3-6.

[0062] Figure 6 The removal rates of Si impurities at different heights are shown for Comparative Examples 5-7 and Examples 3-6. Detailed Implementation

[0063] The present invention will be described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto. Taking 2N8 industrial pure aluminum and 4N6 high-purity aluminum raw materials as examples, the process flow and implementation effects are explained based on comparative examples and embodiments.

[0064] A schematic diagram of the segregation apparatus (segregation furnace) used in this embodiment of the invention is shown below. Figure 1 As shown, the furnace includes a cavity furnace body 5 (e.g., a graphite crucible), a lid 4 positioned above the furnace body opening, and a cooling pipe 3 (cooling copper pipe) positioned above the lid. The furnace body 5 is housed within a stainless steel sleeve 7, with heat-insulating asbestos 8 between the stainless steel sleeve 7 and the furnace body 5. The stainless steel sleeve 7, furnace body 5, and lid 4 are housed within a quartz tube 10, with a heating coil 6 positioned on the outside of the quartz tube 10. The stainless steel sleeve 7 and furnace body 5 are mounted on a lifting platform 11 via a support frame 9. Molten aluminum 12 is contained within the cavity of the furnace body.

[0065] The cooling pipe 3 includes an inlet 1 and an outlet 2. The cooling pipe 3 is in close contact with the cover 4.

[0066] Sample preparation and component detection: First, use wire cutting to cut the sample surface (the contact point between the graphite cap and the sample) at distances of 1cm, 3cm, and 5cm. Then, use a lathe to flatten the sample surface from top to bottom (recorded as height 0.1), the components at distances of 1cm from the surface (recorded as height 1), 3cm from the surface (recorded as height 3), 5cm from the surface (recorded as height 5), and the bottom of the sample at distances of 9cm from the surface (recorded as height 9). Use a direct-reading spectrometer to detect the components at different heights of the sample.

[0067] Figure 2 This is a schematic diagram of sample cutting; 10 represents height 1, 30 represents height 3, 50 represents height 5, and 90 represents height 9.

[0068] Comparative Example 1: 2N8 Industrial Pure Aluminum

[0069] This comparative example uses 2N8 industrial pure aluminum (mass content: Fe 1000ppm, Si 400ppm, Al 99.8%, balance being other impurity elements, the same throughout the text) as raw material. Specific steps and process parameters are as follows:

[0070] (1) Preparation of pure aluminum: Weigh out one portion of the required weight of 2N8 industrial pure aluminum.

[0071] (2) Sample melting: The weighed 2N8 industrial pure aluminum is placed in a graphite crucible in a melting furnace for melting at a melting temperature of 800℃. After melting for 90 minutes, it is stirred for 5 minutes to make the composition uniform, and then kept at a constant temperature for 5 minutes.

[0072] (3) Gradient cooling and heat preservation treatment: The change of melt temperature is monitored by computer-aided cooling solidification heat analysis (CA-CCTA). The melt in step (2) is cooled at a rate of 2℃ / min, and then kept at 720℃ for 60-120min and 680℃ for 60-120min. When the melt temperature drops to 400-500℃, the graphite crucible and graphite lid are removed and placed at room temperature.

[0073] (4) Sample preparation: Separate the graphite crucible and graphite lid and take out the sample. The shape of the sample is consistent with the shape of the inside of the graphite crucible. Next, the sample surface, that is, the part of the sample that is close to the graphite lid, is recorded as height 0.1 (the height will be about 0.1 cm after machining off). The part 1 cm away from the sample surface is recorded as height 1, the part 3 cm away from the sample surface is recorded as height 3, the part 5 cm away from the sample surface is recorded as height 5, and the part 9 cm away from the sample surface, that is, the bottom of the sample that is close to the bottom of the graphite crucible, is recorded as height 9.

[0074] (5) Component detection: Four samples were obtained by wire cutting at heights 1, 3, and 5. The samples were then machined flat on the surfaces at heights 0.1, 1, 3, 5, and 9. The components at these five locations were then detected. Figure 2 This is a schematic diagram of the cutting of the sample in Comparative Example 1 (the same applies to all comparative examples and embodiments).

[0075] Composition analysis showed that the contents of Fe and Si impurity elements in the 2N8 sample of Comparative Example 1 were basically consistent at different heights. Therefore, it can be concluded that without the addition of rare earth elements and segregation treatment, it is impossible to effectively change the distribution of Fe and Si impurity elements at different heights in the sample of Comparative Example 1.

[0076] Comparative Example 2: 2N8 industrial pure aluminum + Y (mass content 2000ppm)

[0077] This comparative example uses 2N8 industrial pure aluminum and rare earth master alloy (Al-10Y) as raw materials. The final mass contents of Y, Fe, and Si elements in the high-purity aluminum (a mixture of 2N8 industrial pure aluminum and rare earth master alloy) are calculated and controlled to be 2000 ppm, 1000 ppm, and 400 ppm, respectively. The specific steps and process parameters are as follows:

[0078] (1) Preparation of pure aluminum: Based on the mass contents of Y, Fe and Si elements in pure aluminum being 2000ppm, 1000ppm and 400ppm respectively, calculate and weigh the required amount of 2N8 industrial pure aluminum and Al-10Y rare earth intermediate alloy, and prepare samples according to requirements.

[0079] (2) Sample melting: The weighed 2N8 industrial pure aluminum and rare earth intermediate alloy were placed in a graphite crucible in the melting furnace for melting at a melting temperature of 800℃. After melting, the mixture was stirred for 5 minutes to make the composition uniform, and then kept at a constant temperature for 5 minutes.

[0080] The subsequent steps are exactly the same as those in Comparative Example 1.

[0081] Composition analysis revealed that the Fe and Si impurity content in Comparative Example 2 sample gradually increased from top to bottom. Compared to the composition of 2N8 industrial pure aluminum raw material, the Fe impurity content decreased by 32.5%, 30.0%, 27.7%, and 21.0% at heights of 0.1, 1, 3, and 5, respectively, while increasing by 30.4% at height 9. Similarly, the Si impurity content decreased by 30.3%, 29.5%, 28.0%, and 20.3% at heights of 0.1, 1, 3, and 5, respectively, while increasing by 34.8% at height 9. Based on the comprehensive data analysis, the addition of excess Y element in Comparative Example 2, compared to Comparative Example 1, was beneficial for removing Fe and Si impurities.

[0082] Comparative Example 3: 2N8 industrial pure aluminum + Yb (mass content 2000ppm)

[0083] This comparative example uses 2N8 industrial pure aluminum and a rare earth master alloy (Al-10Yb) as raw materials. The final mass contents of Yb, Fe, and Si in the high-purity aluminum are controlled by calculation to be 2000ppm, 1000ppm, and 400ppm, respectively. Except for the added master alloy, the specific steps and process parameters are the same as those in Comparative Example 2.

[0084] Composition analysis showed that the Fe and Si impurity content in Comparative Example 3 gradually increased from top to bottom. Compared to the composition of 2N8 industrial pure aluminum raw material, the mass content of Fe impurities decreased by 38.5%, 33.2%, 28.4%, and 23.5% at heights of 0.1, 1, 3, and 5, respectively, while increasing by 46.0% at height 9. Similarly, the mass content of Si impurities decreased by 36.3%, 31.0%, 30.0%, and 21.3% at heights of 0.1, 1, 3, and 5, respectively, while increasing by 43.8% at height 9. Based on the comprehensive data analysis, compared to Comparative Example 1, the addition of excess Yb in Comparative Example 3 was beneficial for removing Fe and Si impurities, and the effect of Comparative Example 3 was superior to that of Comparative Example 2.

[0085] Comparative Example 4: 4N6 High-Purity Aluminum

[0086] This comparative example uses 4N6 high-purity aluminum (mass content: Fe 3.6 ppm, Si 3.4 ppm, Al 99.996%, balance being other impurity elements, as described throughout) as the raw material. Specific steps and process parameters are as follows:

[0087] (1) Preparation of high-purity aluminum: Weigh two portions of the required weight of 4N6 high-purity aluminum raw material, one portion for melt viscosity testing and the other portion for subsequent experiments.

[0088] (2) Melt viscosity test: 4N6 high-purity aluminum for melt viscosity test is placed in the graphite crucible inside the ultra-high temperature rheometer. The temperature is set above the melting point of Al melt (800℃) and heated for one hour. Argon protective gas is introduced at a rate of 300-400mL / min. Then the melt viscosity at 680℃ and 670℃ is measured.

[0089] (3) High-purity aluminum smelting: The weighed raw materials are melted in a graphite crucible in a smelting furnace at a melting temperature of 800℃. After all the raw materials are melted, they are stirred for 5 minutes to make the composition uniform, and then kept at a constant temperature for 5 minutes.

[0090] (4) Gradient cooling and heat preservation treatment: The specific steps are the same as those in Comparative Example 1.

[0091] (5) Sample preparation: The specific steps are the same as those in Comparative Example 1.

[0092] (6) Detection of components: The specific steps are the same as those in Comparative Example 1.

[0093] Viscosity testing showed that the melt viscosity of 4N6 high-purity aluminum in Comparative Example 4 increased as the temperature decreased. Composition analysis revealed that, without any treatment, the Fe and Si impurity element content of the 4N6 sample in Comparative Example 4 remained essentially consistent at different heights. Therefore, it can be concluded that without the addition of rare earth elements and segregation treatment, the distribution of Fe and Si impurity elements at different heights in the sample of Comparative Example 4 cannot be effectively altered.

[0094] Comparative Example 5: 4N6 high-purity aluminum + Y (mass content 40 ppm)

[0095] This comparative example uses 4N6 high-purity aluminum and rare earth master alloy (Al-10Y) as raw materials, and the final mass contents of Y, Fe, and Si in high-purity aluminum are controlled by calculation to be 40 ppm, 3.6 ppm, and 3.4 ppm, respectively. The specific steps and process parameters are as follows:

[0096] (1) Preparation of high-purity aluminum: Based on the mass contents of Y, Fe and Si elements in high-purity aluminum being 40ppm, 3.6ppm and 3.4ppm respectively, calculate and weigh the required amount of 4N6 high-purity aluminum and Al-10Y rare earth intermediate alloy, and prepare two samples according to the requirements. One sample is used for melt viscosity detection and the other is used for subsequent experiments.

[0097] (2) Same as Comparative Example 4.

[0098] (3) High-purity aluminum smelting: The weighed raw materials 4N6 high-purity aluminum and Al-10Y rare earth intermediate alloy are melted in a graphite crucible in a smelting furnace at a melting temperature of 800℃. After melting for 90 minutes, the mixture is stirred for 5 minutes to make the composition uniform, and then kept at a constant temperature for 5 minutes.

[0099] The subsequent steps are exactly the same as those in Comparative Example 4.

[0100] Compared to the melt viscosity of 4N6 high-purity aluminum in Comparative Example 4, the addition of 40 ppm Y element in Comparative Example 5 reduced the melt viscosity. Composition analysis showed that the Fe and Si impurity content in Comparative Example 5 gradually increased from top to bottom. Compared to the composition of the 4N6 high-purity aluminum raw material, the mass content of Fe impurities decreased by 25.0%, 25.0%, 19.4%, and 19.4% at heights of 0.1, 1, 3, and 5, respectively, while increasing by 44.4% at height 9. Similarly, the mass content of Si impurities decreased by 26.5%, 23.5%, 20.6%, and 17.6% at heights of 0.1, 1, 3, and 5, respectively, while increasing by 47.1% at height 9. Overall data analysis indicates that, compared to Comparative Example 4, the addition of excessive Y element in Comparative Example 5 reduced the melt viscosity, making the precipitated phase easier to settle and facilitating the removal of Fe and Si impurities.

[0101] Comparative Example 6: 4N6 high-purity aluminum + Yb (mass content 40 ppm)

[0102] This comparative example uses 4N6 high-purity aluminum and a rare earth master alloy (Al-10Yb) as raw materials. The final mass contents of Yb, Fe, and Si in the high-purity aluminum are controlled by calculation to be 40 ppm, 3.6 ppm, and 3.4 ppm, respectively. Except for the added master alloy, the specific steps and process parameters are the same as those in Comparative Example 5.

[0103] Compared to the melt viscosity of 4N6 high-purity aluminum in Comparative Example 4, the addition of 40 ppm Yb in Comparative Example 6 reduced the melt viscosity. Composition analysis showed that the Fe and Si impurity content in Comparative Example 6 gradually increased from top to bottom. Compared to the composition of the 4N6 high-purity aluminum raw material, the mass content of Fe impurities decreased by 27.8%, 25.0%, 22.2%, and 19.4% at heights of 0.1, 1, 3, and 5, respectively, while increasing by 44.4% at height 9. Similarly, the mass content of Si impurities decreased by 26.5%, 26.5%, 23.5%, and 20.6% at heights of 0.1, 1, 3, and 5, respectively, while increasing by 50.0% at height 9. Overall, the data analysis indicates that the addition of excessive Yb in Comparative Example 6 reduced the melt viscosity compared to Comparative Example 4, making the precipitate phase easier to settle and facilitating the removal of Fe and Si impurities.

[0104] Comparative Example 7: 4N6 high-purity aluminum + segregation treatment

[0105] This comparative example uses 4N6 high-purity aluminum as raw material. The specific steps and process parameters are as follows:

[0106] (1) Preparation of high-purity aluminum: Weigh the required weight of 4N6 high-purity aluminum raw material as the target sample, and use one portion for the next step of segregation and purification experiment.

[0107] (2) Melt viscosity test: The melt viscosity is consistent with that of the 4N6 high-purity aluminum melt in Comparative Example 4.

[0108] (3) High-purity aluminum smelting: The weighed raw materials for the segregation purification experiment are placed in a segregation furnace (see...). Figure 1 The graphite crucible is placed inside a protective sleeve containing heat-insulating asbestos on its side walls and bottom to ensure that heat is transferred only through the top of the graphite crucible. Next, high-purity aluminum is melted at 800℃ for 90 minutes. After complete melting, the mixture is stirred for 5 minutes to ensure homogeneity, and then allowed to stand at that temperature for 5 minutes.

[0109] (4) Gradient cooling and heat preservation treatment: Computer-aided cooling solidification heat analysis (CA-CCTA) is used to monitor the change of melt temperature. The melt in step (3) is cooled at a rate of 2℃ / min and kept at 720℃ and 680℃ for 60-120min respectively. Finally, the melt temperature in the crucible is maintained at 680℃.

[0110] (5) Segregation: Next, turn off the furnace heating coils and use computer-aided cooling solidification heat analysis (CA-CCTA) to monitor the change in melt temperature. Then, place a copper pipe with circulating cooling water on top of the graphite lid, making sure it is tightly fitted. This allows the heat in the graphite crucible and the graphite crucible lid to be transferred from bottom to top through the copper pipe. Because the copper pipe is in close contact with the graphite crucible lid, the temperature at the lid is lower. This ensures that the melt inside the graphite crucible begins to crystallize from top to bottom, forming a segregation process (generally segregation for 5-10 minutes).

[0111] (6) Sample preparation: The sample preparation steps are the same as those in Comparative Example 4.

[0112] (7) Detection of components: The steps for detecting components are the same as those for comparative example 4.

[0113] Composition analysis revealed that the Fe and Si impurity content in Comparative Example 7 gradually increased from top to bottom. Compared to the composition of 4N6 high-purity aluminum raw material, the Fe impurity content decreased by 22.2%, 19.4%, 13.9%, and 13.9% at heights of 0.1, 1, 3, and 5, respectively, while increasing by 38.9% at height 9. Similarly, the Si impurity content decreased by 23.5%, 20.6%, 20.6%, and 11.8% at heights of 0.1, 1, 3, and 5, respectively, while increasing by 44.1% at height 9. Based on the comprehensive data analysis, the segregation method used in Comparative Example 7 was more effective in removing Fe and Si impurities compared to Comparative Example 4.

[0114] To further illustrate the effects of the present invention, the present invention will be described below in conjunction with embodiments.

[0115] Example 1: 2N8 industrial pure aluminum + Y (2000ppm) + segregation treatment

[0116] This embodiment uses 2N8 industrial pure aluminum and rare earth master alloy (Al-10Y) as raw materials for batching, and calculates and controls the final mass content of Y, Fe, and Si elements in high-purity aluminum to be 2000ppm, 1000ppm, and 400ppm, respectively. The specific steps and process parameters are as follows:

[0117] (1) Preparation of pure aluminum: Based on the mass contents of Y, Fe and Si elements in high-purity aluminum being 2000ppm, 1000ppm and 400ppm respectively, weigh out the required 2N8 industrial pure aluminum and Al-10Y rare earth intermediate alloy and prepare samples according to requirements.

[0118] (2) Pure aluminum smelting: The weighed raw materials are placed in a segregation furnace (such as...) Figure 1 The graphite crucible is placed in a protective sleeve containing heat-insulating asbestos on its side walls and bottom to ensure that heat is transferred only through the top of the graphite crucible. The melting temperature is 800℃. After melting for 90 minutes, the crucible is stirred for 5 minutes to ensure uniform composition and then kept at a constant temperature for 5 minutes.

[0119] (3) Gradient cooling and heat preservation treatment: Computer-aided cooling solidification heat analysis (CA-CCTA) is used to monitor the change of melt temperature. The melt in step (2) is cooled at a rate of 2℃ / min and kept at 720℃ and 680℃ for 60-120min respectively. Finally, the melt temperature in the crucible is maintained at 680℃.

[0120] (4) Segregation: Next, the furnace heating coils are turned off, and computer-aided cooling solidification heat analysis (CA-CCTA) is used to monitor the change in melt temperature. Then, a copper pipe with circulating cooling water is placed above the graphite lid, tightly fitted, so that the heat in the graphite crucible and graphite crucible lid is transferred from bottom to top through the copper pipe. Because the copper pipe is in close contact with the graphite crucible lid, the temperature at the lid is lower. This ensures that the melt inside the graphite crucible begins to crystallize from top to bottom, forming a segregation process.

[0121] (5) Sample preparation: The specific steps are the same as those in Comparative Example 1.

[0122] (6) Detection of components: The specific steps are the same as those in Comparative Example 1.

[0123] Composition analysis showed that the Fe and Si impurity content in the sample of Example 1 gradually increased from top to bottom. Compared with the composition of 2N8 industrial pure aluminum raw material, the mass content of Fe impurity decreased by 81.5%, 81.0%, 80.8%, and 80.0% at heights of 0.1, 1, 3, and 5, respectively, and increased by 88.2% at height 9. Similarly, the mass content of Si impurity decreased by 78.3%, 77.5%, 77.3%, and 75.5% at heights of 0.1, 1, 3, and 5, respectively, and increased by 85.8% at height 9. The element content in the sample of Example 1 at heights of 0.1–5 met the industry standard for 3N5 high-purity aluminum, and 3N5 high-purity aluminum was successfully prepared. Comprehensive data analysis indicated that adding excess Y element before segregation treatment in Example 1 was more effective in removing Fe and Si impurities than in comparative examples 1–3.

[0124] Example 2: 2N8 industrial pure aluminum + Yb (2000ppm) + segregation treatment

[0125] This embodiment uses 2N8 industrial pure aluminum and rare earth master alloy (Al-10Yb) as raw materials for batching, and calculates and controls the final mass content of Yb, Fe, and Si elements in high-purity aluminum to be 2000ppm, 1000ppm, and 400ppm, respectively. Except for the added master alloy, the other specific steps and process parameters are the same as in Example 1.

[0126] Composition analysis showed that the Fe and Si impurity content in the sample of Example 2 gradually increased from top to bottom. Compared with the composition of 2N8 industrial pure aluminum raw material, the mass content of Fe impurity decreased by 82.0%, 81.5%, 81.2%, and 80.5% at heights of 0.1, 1, 3, and 5, respectively, and increased by 90.1% at height 9. Similarly, the mass content of Si impurity decreased by 80.0%, 78.5%, 78.3%, and 76.5% at heights of 0.1, 1, 3, and 5, respectively, and increased by 90.3% at height 9. The element content in the sample of Example 2 at heights of 0.1–5 met the industry standard for 3N5 high-purity aluminum, and 3N5 high-purity aluminum was successfully prepared. Comprehensive data analysis indicated that adding excess Yb before segregation treatment in Example 2 was more effective in removing Fe and Si impurities than Comparative Examples 1–3 and Example 1.

[0127] Example 3: 4N6 high-purity aluminum + Y (mass content 40ppm) + segregation treatment

[0128] This embodiment uses 4N6 high-purity aluminum and rare earth master alloy (Al-10Y) as raw materials for batching, and calculates and controls the final mass content of rare earth elements Y, Fe, and Si in high-purity aluminum to be 40 ppm, 3.6 ppm, and 3.4 ppm, respectively. Except for the difference in the content of high-purity aluminum and added master alloy compared with Example 1, the other specific steps and process parameters are the same as in Example 1.

[0129] Composition analysis showed that the Fe and Si impurity content in the sample of Example 3 gradually increased from top to bottom. Compared with the composition of 4N6 high-purity aluminum raw material, the mass content of Fe impurity decreased by 44.4%, 44.4%, 38.9%, and 38.9% at heights of 0.1, 1, 3, and 5, respectively, and increased by 88.9% at height 9. The mass content of Si impurity decreased by 47.1%, 44.1%, 41.2%, and 38.2% at heights of 0.1, 1, 3, and 5, respectively, and increased by 76.5% at height 9. The average Y content at heights of 0.1, 1, 3, and 5 was 0.4 ppm, with a removal rate of 99.0%. The element content of the sample in Example 3 at heights of 0.1 to 5 met the industry standard for 5N high-purity aluminum, and 5N high-purity aluminum was successfully prepared. Based on comprehensive data analysis, adding an excessive amount of Y element before segregation treatment in Example 3 is beneficial for removing Fe and Si impurities without introducing additional impurities, and the effect is better than that of Comparative Examples 4 to 7.

[0130] Example 4: 4N6 high-purity aluminum + Y (mass content 100ppm) + segregation treatment

[0131] In this embodiment, 4N6 high-purity aluminum and rare earth master alloy (Al-10Y) are used as raw materials for batching. The final mass contents of rare earth elements Y, Fe, and Si in high-purity aluminum are controlled by calculation to be 100ppm, 3.6ppm, and 3.4ppm, respectively. The content of high-purity aluminum and added master alloy in this embodiment is different from that in Example 1, and the melt viscosity needs to be detected. The step of detecting the melt viscosity is the same as step (2) in Comparative Example 4. The other specific steps and process parameters are the same as those in Example 1.

[0132] Melt viscosity analysis revealed that the addition of 100 ppm of Y element in Example 4 reduced the melt viscosity compared to that of 4N6 high-purity aluminum in Comparative Example 4. Composition analysis showed that the Fe and Si impurity content in the Example 4 sample gradually increased from top to bottom. Compared to the composition of the 4N6 high-purity aluminum raw material, the Fe impurity content decreased by 63.9%, 61.1%, 61.1%, and 55.6% at heights of 0.1, 1, 3, and 5, respectively, but increased by 177.8% at height 9. Similarly, the Si impurity content decreased by 70.6%, 64.7%, 61.8%, and 58.8% at heights of 0.1, 1, 3, and 5, respectively, but increased by 97.1% at height 9. The average Y element content at heights of 0.1, 1, 3, and 5 was 0.5 ppm, with a removal rate of 99.5%. In Example 4, the elemental content of the sample at heights of 0.1–5 met the industry standard for 5N high-purity aluminum, and 5N high-purity aluminum was successfully prepared. Comprehensive data analysis shows that adding excess Y element before segregation treatment in Example 4 is beneficial for removing Fe and Si impurities without introducing additional impurities, and the effect is superior to Comparative Examples 4–7 and Example 3.

[0133] Example 5: 4N6 high-purity aluminum + Yb (40 ppm by mass) + segregation treatment

[0134] This embodiment uses 4N6 high-purity aluminum and rare earth master alloy (Al-10Yb) as raw materials for batching, and calculates and controls the final mass content of rare earth Yb, Fe, and Si elements in high-purity aluminum to be 40 ppm, 3.6 ppm, and 3.4 ppm, respectively. Except for the difference in the content of high-purity aluminum and added master alloy compared with Example 1, the other specific steps and process parameters are the same as in Example 1.

[0135] Composition analysis showed that the Fe and Si impurity content in the sample of Example 5 gradually increased from top to bottom. Compared with the composition of 4N6 high-purity aluminum raw material, the mass content of Fe impurity decreased by 50.0%, 47.2%, 47.2%, and 41.7% at heights of 0.1, 1, 3, and 5, respectively, and increased by 97.2% at height 9. Similarly, the mass content of Si impurity decreased by 50.0%, 50.0%, 44.1%, and 41.2% at heights of 0.1, 1, 3, and 5, respectively, and increased by 79.4% at height 9. The average Yb content at heights of 0.1, 1, 3, and 5 was 0.4 ppm, with a removal rate of 99.0%. The element content of the sample in Example 5 at heights of 0.1–5 met the industry standard for 5N high-purity aluminum, and 5N high-purity aluminum was successfully prepared. Based on comprehensive data analysis, adding an excess of Yb element before segregation treatment in Example 5 is beneficial for removing Fe and Si impurities without introducing additional impurities, and its effect is better than that of Comparative Examples 4-7 and Example 3.

[0136] Example 6: 4N6 high-purity aluminum + Yb (mass content 100ppm) + segregation treatment

[0137] In this embodiment, 4N6 high-purity aluminum and rare earth master alloy (Al-10Yb) are used as raw materials for batching. The final mass contents of rare earth elements Yb, Fe, and Si in high-purity aluminum are controlled by calculation to be 100ppm, 3.6ppm, and 3.4ppm, respectively. The content of high-purity aluminum and added master alloy in this embodiment is different from that in Example 1, and the melt viscosity needs to be detected. The step of detecting the melt viscosity is the same as step (2) in Comparative Example 1. The other specific steps and process parameters are the same as those in Example 1.

[0138] Composition analysis showed that the Fe and Si impurity content in the sample of Example 6 gradually increased from top to bottom. Compared with the composition of 4N6 high-purity aluminum raw material, the mass content of Fe impurity decreased by 66.7%, 66.7%, 63.9%, and 61.1% at heights of 0.1, 1, 3, and 5, respectively, and increased by 200.0% at height 9. The mass content of Si impurity decreased by 70.6%, 67.6%, 67.6%, and 61.8% at heights of 0.1, 1, 3, and 5, respectively, and increased by 114.7% at height 9. The average Yb content at heights of 0.1, 1, 3, and 5 was 0.5 ppm, with a removal rate of 99.5%. The element content of the sample in Example 6 at heights of 0.1 to 5 met the industry standard for 5N high-purity aluminum, and 5N high-purity aluminum was successfully prepared. Based on comprehensive data analysis, adding an excess of Yb element before segregation treatment in Example 6 is beneficial for removing Fe and Si impurities without introducing additional impurities, and the effect is the best among all comparative examples and examples.

[0139] To better compare and illustrate the differences in process and effect among the comparative examples and embodiments, the melt viscosity data are summarized in Table 1, the Fe and Si impurity element content at different heights (2N8 raw material) is summarized in Table 2, and the Fe and Si impurity element content at different heights (4N6 raw material) is summarized in Table 3. All embodiments of the present invention remove Fe and Si impurity elements from high-purity aluminum through rare earth alloying and remove excess rare earth elements and remaining Fe and Si impurity elements through segregation. This process can effectively purify high-purity aluminum without introducing additional impurity elements. Specifically, in Examples 1-2, the final high-purity aluminum samples prepared had an Al purity greater than 3N5 at heights of 0.1–5, and in Examples 4-6, the final high-purity aluminum samples prepared had an Al purity greater than 5N at heights of 0.1–5. Among the 2N8 high-purity aluminum, Example 2, based on the addition of 2000 ppm Yb and synergistic treatment with segregation, exhibits superior overall performance; among the 4N6 high-purity aluminum, Example 6, based on the addition of 100 ppm Yb and synergistic treatment with segregation, exhibits superior overall performance.

[0140] Table 1. Melt viscosities of 4N6 high-purity aluminum at 680°C and 670°C in the comparative and examples.

[0141]

[0142] Table 2 shows the Fe and Si impurity element content at different heights in the comparative and examples (2N8 raw material).

[0143]

[0144] Table 3 shows the Fe and Si impurity element content at different heights of samples in the comparative and example samples (4N6 raw material).

[0145]

[0146]

[0147] Figure 3 The removal rates of Fe impurities at different heights were measured for samples from Comparative Examples 2-3 and Examples 1-2.

[0148] Figure 4 The removal rates of Si impurities at different heights are shown for Comparative Examples 2-3 and Examples 1-2.

[0149] Figure 5 The removal rates of Fe impurities at different heights were measured for samples from Comparative Examples 5-7 and Examples 3-6.

[0150] Figure 6 The removal rates of Si impurities at different heights are shown for Comparative Examples 5-7 and Examples 3-6.

[0151] The implementation of the present invention is not limited to the embodiments described above. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A composite treatment method for reducing Fe / Si impurities in high-purity aluminum using rare earth alloying and segregation, characterized in that: Includes the following steps: 1) Prepare a rare earth-pure aluminum mixed melt by combining pure aluminum raw materials and Al-RE rare earth master alloy; 2) The mixed melt is subjected to gradient cooling and heat preservation treatment; 3) Segregation treatment of the mixed melt; In the Al-RE rare earth master alloy, RE is Y and / or Yb; The Al-RE rare earth master alloy is an Al-Y rare earth master alloy and / or an Al-Yb rare earth master alloy. The addition amount of rare earth element (RE) meets the following conditions: the addition amount of Y is 1.5 to 50 times the Fe or Si content in the pure aluminum raw material; when the Fe content in the pure aluminum raw material is ≥ the Si content, the addition amount of Y is 1.5 to 50 times the Fe content in the pure aluminum raw material; when the Fe content in the pure aluminum raw material is < the Si content, the addition amount of Y is 1.5 to 50 times the Si content in the pure aluminum raw material. The amount of Yb added is 1.5 to 50 times the Fe or Si content in the pure aluminum raw material; when the Fe content in the pure aluminum raw material is ≥ the Si content, the amount of Yb added is 1.5 to 50 times the Fe content in the pure aluminum raw material; when the Fe content in the pure aluminum raw material is < the Si content, the amount of Yb added is 1.5 to 50 times the Si content in the pure aluminum raw material. The pure aluminum raw material is 2N8 industrial pure aluminum or 4N6 high-purity aluminum; When the pure aluminum raw material is 2N8 industrial pure aluminum, the amount of rare earth RE added is 1.5 to 8 times the Fe or Si content in the pure aluminum raw material; When the pure aluminum raw material is 4N6 high-purity aluminum, the amount of rare earth RE added is 8 to 50 times the Fe or Si content in the pure aluminum raw material; The gradient cooling and holding process described in step 2) involves first lowering the melt temperature to 710-730℃ at a rate of 1-2.5℃ / min and holding it for 60-120min, then lowering the melt temperature to 675-685℃ at a rate of 1-2.5℃ / min and holding it for 60-120min, and finally maintaining the melt temperature at 675-685℃. The segregation treatment mentioned in step 3) refers to cooling the melt on one side or above after heating is stopped, causing the melt to crystallize and form segregation.

2. The composite treatment method for reducing Fe / Si impurities in high-purity aluminum using rare earth alloying and segregation as described in claim 1, characterized in that: When the Al content in the pure aluminum raw material is ≥99.8%, the Fe or Si content is ≥100ppm and Fe < 0.2%, Si <0.1%, and the total impurities are < 0.2%, the amount of rare earth RE added is 1.5 to 8 times the Fe or Si content in the pure aluminum raw material; when the Fe or Si content is <100ppm, the amount of rare earth RE added is 8 to 50 times the Fe or Si content in the pure aluminum raw material.

3. The composite treatment method for reducing Fe / Si impurities in high-purity aluminum by utilizing rare earth alloying and segregation as described in claim 2, characterized in that: The pure aluminum raw material contains ≥99.8% Al; the Al-Y rare earth master alloy is Al-10wt%Y, and the Al-Yb rare earth master alloy is Al-10wt%Yb.

4. The composite treatment method for reducing Fe / Si impurities in high-purity aluminum by utilizing rare earth alloying and segregation as described in claim 1, characterized in that: When the pure aluminum raw material is 2N8 industrial pure aluminum, the amount of rare earth RE added is 1.5 to 5 times the Fe or Si content in the pure aluminum raw material; When the pure aluminum raw material is 4N6 high-purity aluminum, the amount of rare earth element RE added is 8 to 40 times the Fe or Si content in the pure aluminum raw material.

5. The composite treatment method for reducing Fe / Si impurities in high-purity aluminum by utilizing rare earth alloying and segregation according to claim 1, characterized in that: The segregation treatment described in step 3) specifically refers to turning off the heating device of the segregation device, placing a cover above the melt in the cavity of the segregation device, and placing a cooling device above the cover. After being cooled by the cooling device, the melt in contact with the cover begins to crystallize from top to bottom, forming segregation.

6. The composite treatment method for reducing Fe / Si impurities in high-purity aluminum by utilizing rare earth alloying and segregation according to claim 1, characterized in that: After the segregation process is completed, the aluminum ingot is cooled, removed, and the composition of different parts of the ingot is tested. The parts with more impurities are removed to obtain the desired pure aluminum.

7. The composite treatment method for reducing Fe / Si impurities in high-purity aluminum by utilizing rare earth alloying and segregation as described in claim 1, characterized in that: Step 1) involves melting pure aluminum raw material and Al-RE rare earth intermediate alloy, mixing them, and keeping them at a constant temperature to obtain a rare earth-pure aluminum mixed melt.

8. The composite treatment method for reducing Fe / Si impurities in high-purity aluminum by utilizing rare earth alloying and segregation according to claim 7, characterized in that: The melting temperature is 750~800℃; the mixing is carried out by stirring after melting high-purity aluminum; the stirring time is 5~10 minutes. Let it stand still and keep warm for 3-60 minutes.

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