Method for removing low-melting-point eutectic impurities in high-conductivity pure aluminum material
By using a semi-solid-supergravity method to process pure aluminum materials, the problems of high energy consumption and impurity separation have been solved, achieving efficient and low-cost pure aluminum purification and improving conductivity and quality stability.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- UNIV OF SCI & TECH BEIJING
- Filing Date
- 2026-02-13
- Publication Date
- 2026-06-05
AI Technical Summary
Existing pure aluminum purification technologies suffer from high energy consumption, unstable quality, severe pollution, and difficulty in effectively separating low-melting-point eutectic impurities. Furthermore, the addition of refining agents is difficult to control, and the deep removal efficiency is low.
The semi-solid-hypergravity method is adopted. Pure aluminum material is heated to a semi-solid state, causing eutectic impurity elements in the solid phase to migrate to the liquid phase. The hypergravity field is used for separation and purification. Combined with predetermined temperature and time control, solid-liquid separation is achieved.
It efficiently removes low-melting-point eutectic impurities from pure aluminum, increases the conductivity of aluminum materials to 66.5% IACS, reduces aluminum loss rate to less than 10%, simplifies operation, reduces energy consumption and costs, and is suitable for industrial production.
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Figure CN122147091A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the technical field of deep impurity removal from pure aluminum materials, and in particular to a method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials. Specifically, it is a novel method for deep removal of low-melting-point eutectic impurities from highly conductive pure aluminum materials using a semi-solid-gravity method. Background Technology
[0002] With the advancement of my country's industrialization, annual power generation has steadily increased, posing significant challenges to power transmission. Using highly conductive materials can reduce the operating temperature of transmission lines and related equipment, thereby improving the safety and stability of the power grid, reducing transmission line losses, and effectively saving energy. Pure copper, with its excellent conductivity, is the primary material chosen by the electrical industry, but its high price limits its application in power transmission. Aluminum, with conductivity second only to copper, has been used in recent years for overhead transmission and distribution lines due to its light weight and low cost. However, the purity of aluminum is closely related to its conductivity; even high-purity aluminum contains trace amounts of inclusions that significantly affect its conductivity. Therefore, improving and optimizing the purification process of molten aluminum to produce higher-purity aluminum remains a pressing problem that needs to be solved.
[0003] Currently, the three-layer electrolyte refining method and segregation methods (including zone melting, stepwise crystallization, and directional solidification) are the main purification methods for pure aluminum materials in industry. Electrolysis is currently the most mature and widely used aluminum refining technology, but its complex production process presents challenges such as high energy consumption, unstable quality, and severe pollution. Segregation utilizes the differences in solubility of impurity elements in aluminum, controlling parameters such as temperature and pressure to migrate impurity elements to the solid or liquid phase, thereby improving the purity of aluminum. This method is more environmentally friendly, but it suffers from low production efficiency and poor purification effect. Furthermore, this method requires extremely high temperature control; higher temperatures cause trace amounts of iron impurities to dissolve in the matrix, while lower purification temperatures theoretically allow for solid-liquid separation of inclusions. However, due to the increased aluminum phase fraction in the pure aluminum matrix, a large amount of low-melting-point eutectic impurities exist in the voids between the solid aluminum matrix particles. Affected by capillary action, conventional methods are insufficient to effectively separate them.
[0004] Chinese patent CN115573004A discloses a method for removing impurity elements from molten aluminum in an aluminum electrolysis cell. It requires adding anhydrous borax to the molten aluminum to remove impurities. However, the hygroscopic and high-temperature decomposition characteristics of anhydrous borax can damage the stability of the electrolyte and may cause local overheating and corrosion problems. In addition, the introduction of boron can interfere with the reduction kinetics of aluminum and the purity of the product.
[0005] Chinese patent CN111321304A discloses a reagent for removing trace impurities from primary aluminum and its method of use. Obviously, it removes the total impurities in the molten aluminum by adding a refining agent. However, this method not only requires special preparation of the refining agent's composition and content, but also requires control of the particle size of the prepared reagent. Although the amount of reagent added is less than 10,000 parts, the process of adding the refining agent and controlling the refining agent to fully and evenly contact the molten aluminum is difficult, and it cannot remove impurities in the molten aluminum evenly and deeply.
[0006] The method for purifying aluminum and aluminum alloy melt disclosed in Chinese patent CN101871052A requires the addition and smelting of two refining media, which has technical defects such as difficulty in controlling the addition of refining agents, complexity in the process of removing impurities, and difficulty in operation.
[0007] The high-purity aluminum purification method in Chinese patent CN107354321A clearly utilizes the segregation method. Its purification process not only requires spiral rotation to stir the aluminum liquid, but also requires continuous cooling water to be introduced into the crystallizer. Obviously, it is difficult to operate, consumes a lot of water resources, has high preparation costs, low efficiency, low impurity removal efficiency, and poor effect.
[0008] In the high-purity aluminum purification method of Chinese patent CN114875248A, not only are two heat treatments required to obtain crude aluminum, but also evaporation purification treatment is required to obtain aluminum vapor. Since the evaporation process requires continuous heating, energy consumption is high. At the same time, the high boiling point of aluminum makes the distillation time long and the production efficiency low. Impurities in aluminum (such as silicon, iron, etc.) may form low-boiling-point azeotropes or volatile compounds with aluminum, which condense along with aluminum vapor during distillation and contaminate the product.
[0009] Therefore, how to deeply remove low-melting-point eutectic impurities from a pure aluminum matrix at a relatively low temperature is one of the difficulties in preparing high-purity aluminum materials.
[0010] Hypergravity technology, as a technique to enhance separation, can effectively overcome the effects of capillary action and strengthen solid-liquid separation. Based on this, this invention provides a novel method for the deep removal of low-melting-point eutectic impurities from highly conductive pure aluminum materials using a semi-solid-hypergravity approach. Summary of the Invention
[0011] The main objective of this invention is to address the technical problems inherent in existing aluminum refining technologies, including high energy consumption, unstable quality, and severe pollution from complex production processes; the difficulty in effectively separating large quantities of low-melting-point eutectic impurities from the liquid phase due to capillary action; uneven impurity removal, potential side reactions, difficulty in control, and challenges in deep removal caused by the selection and addition of refining agents; and the high consumption of water and other resources, as well as high energy consumption. Therefore, this invention proposes a method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials, capable of solving the aforementioned problems.
[0012] The technical solution is as follows:
[0013] A method for removing low-melting-point eutectic impurities from highly conductive pure aluminum material, comprising the following steps:
[0014] S1. Heating to a predetermined temperature: In a centrifuge heating furnace, the raw pure aluminum material is heated to a predetermined temperature to ensure that the pure aluminum material is in a semi-solid state, thereby obtaining semi-solid pure aluminum material;
[0015] S2, Preparation of low-melting-point impurity liquid phase: The semi-solid pure aluminum material of S1 is kept at a predetermined temperature to allow eutectic impurity elements in the solid phase to migrate into the liquid phase, thereby obtaining a semi-solid pure aluminum material containing a low-melting-point impurity liquid phase.
[0016] S3, Hypergravity Separation and Purification: The semi-solid pure aluminum material containing a low-melting-point impurity liquid phase in S2 is subjected to hypergravity separation and purification treatment. Under the action of the hypergravity field, the low-melting-point impurity liquid phase undergoes directional migration and separates from the solid phase, resulting in a high-conductivity high-purity aluminum solid phase material and an aluminum material containing low-melting-point impurities.
[0017] Optionally, the raw material S1 contains more than 99.0% aluminum, and its impurity elements include Fe and Si.
[0018] Optionally, the predetermined temperature T in S1 is determined based on the liquidus temperature T0 of the raw material pure aluminum and the initial precipitation temperature T1 of the eutectic phase of the impurity element, with the following relationship: T=(T0+T1) / 2±T3, where T3≤ 3℃.
[0019] Optionally, the semi-solid state of the semi-solid pure aluminum material in S1 is a state in which solid and liquid phases coexist; the solid-liquid ratio is related to the impurity content in the raw material, and the more impurities there are, the greater the proportion of liquid phase.
[0020] Optionally, the heating rate of the centrifuge heating furnace in S1 is 7℃ / min, and the heating method is direct one-step heating to the predetermined temperature.
[0021] Optionally, the semi-solid pure aluminum material in S2 is held at the predetermined temperature for 20-60 minutes.
[0022] Optionally, the process parameters for the ultragravity separation and purification process in S3 include: a gravity coefficient of 100-600 and an ultragravity separation time of 1-5 min.
[0023] Optionally, the removal rate of eutectic impurity elements in the raw material pure aluminum in S3 is higher than 80%, the aluminum loss rate is lower than 10%, and the conductivity of the prepared high-conductivity high-purity aluminum material is increased to a maximum of 66.5% IACS and a minimum of 63.8% IACS.
[0024] Optionally, the method for removing low-melting-point eutectic impurities from the highly conductive pure aluminum material can purify 10 kg of raw pure aluminum material in a single process; however, if repeated multiple times, the removal rate of eutectic impurity elements in the raw pure aluminum material decreases with each subsequent purification. Experimental testing has shown that after three purification processes, this method is no longer suitable for further removal of eutectic impurity elements from the raw pure aluminum material.
[0025] Technical principle of the invention:
[0026] This invention first clarifies the existence form of inclusion elements in the non-equilibrium phase solidification process of industrial pure aluminum, and proposes a new method for purifying pure aluminum materials by combining semi-solid and hypergravity, the working principle of which is shown in Figure 4(a). As shown in Figure 4(a), when the pure aluminum sample is held in a semi-solid state, the solubility of the iron-rich phase in the solid phase is much lower than that in the liquid phase. Iron-rich inclusions in the aluminum matrix continuously migrate towards the liquid phase at the grain boundaries. Based on this, a hypergravity field is introduced to increase convection in the melt, promoting the discharge and transport of solute, squeezing the liquid phase at the grain boundaries out of the aluminum matrix, reducing the iron-rich phase in the liquid phase, and ensuring a large concentration difference of the iron-rich phase between the solid and liquid phases. This further promotes the migration of the iron-rich phase from the solid to the liquid phase at the grain boundaries, reducing the content of solute (iron-rich phase) in the solid phase. Ultimately, the purpose of purifying the pure aluminum material is achieved, as shown in Figure 4(b).
[0027] The above technical solution has at least the following advantages compared with the existing technology:
[0028] The above-mentioned solution proposes a method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials. This method can solve the technical problems of high energy consumption, unstable quality, and serious pollution in existing aluminum refining technologies, as well as the technical problem that a large number of low-melting-point eutectic impurities are difficult to effectively separate in the liquid phase due to capillary action. It can also solve the technical problems of uneven impurity removal, potential side reactions, difficulty in control, and difficulty in deep removal caused by the selection and addition of refining agents, and the technical problems of high water and other resource consumption and high energy consumption.
[0029] The method of the present invention can make pure aluminum material in a semi-solid state by heating it to a predetermined temperature. This state is conducive to the continuous migration of iron-rich inclusions in the solid phase to the liquid phase at the grain boundaries.
[0030] The method of this invention prepares a low-melting-point liquid phase containing impurities, which enables eutectic impurity elements in the solid phase to migrate into the liquid phase. The migration rate of these eutectic impurity elements is affected by the holding temperature and time. Therefore, the preset temperature T is determined based on the liquidus temperature T0 of the raw material pure aluminum and the initial precipitation temperature T1 of the eutectic phase of the impurity elements. The relationship is: T=(T0+T1) / 2±T3, where T3≤ 3℃; the holding time is selected as 20-60min.
[0031] The method of this invention uses high gravity separation and purification to promote the migration of the iron-rich phase in the solid to the liquid phase at the grain boundaries, and to squeeze the liquid phase impurities at the grain boundaries out of the aluminum matrix, thereby achieving the effect of extreme impurity removal.
[0032] The eutectic impurity element removal rate of the raw material pure aluminum of the present invention is higher than 80%, the aluminum loss rate is lower than 10%, and the conductivity of the prepared high-conductivity high-purity aluminum material is increased to a maximum of 66.5% IACS and a minimum of 63.8% IACS.
[0033] In summary, compared with traditional methods, the method of the present invention purifies the raw material pure aluminum material at low temperature, low cost, and high efficiency by heating the raw material pure aluminum material to a predetermined temperature to make it semi-solid, preparing it into a low-melting-point liquid phase containing impurities, and separating and purifying it by gravity. This method can effectively overcome the influence of capillary action, enhance solid-liquid separation, is simple and easy to operate, has low cost, low energy consumption, and high efficiency, and is conducive to large-scale industrial production and promotion. Attached Figure Description
[0034] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.
[0035] Figure 1 This is a process flow diagram of a method for removing low-melting-point eutectic impurities in a highly conductive pure aluminum material according to the present invention.
[0036] Figure 2 This is a SEM image of a high-conductivity, high-purity aluminum solid material prepared by a method for removing low-melting-point eutectic impurities in a high-conductivity pure aluminum material according to Embodiment 1 of the present invention.
[0037] Figure 3This is an SEM image of an aluminum material containing low-melting-point impurities prepared by a method for removing low-melting-point eutectic impurities from a highly conductive pure aluminum material according to Embodiment 1 of the present invention.
[0038] Figure 4(a) is a sample melting process diagram of a method for removing low-melting-point eutectic impurities in a highly conductive pure aluminum material according to the present invention.
[0039] Figure 4(b) is a diagram of the gravity separation process of a method for removing low-melting-point eutectic impurities in a highly conductive pure aluminum material according to the present invention. Detailed Implementation
[0040] The technical solution of the present invention will now be described with reference to the accompanying drawings.
[0041] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.
[0042] In the embodiments of the present invention, the terms "image" and "picture" may sometimes be used interchangeably. It should be noted that when the distinction is not emphasized, their intended meanings are consistent.
[0043] In this embodiment of the invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.
[0044] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.
[0045] A method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials, wherein the method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials is combined with... Figure 1 Includes the following steps:
[0046] S1. Heating to a predetermined temperature: In a centrifuge heating furnace, the raw pure aluminum material is heated to a predetermined temperature to ensure that the pure aluminum material is in a semi-solid state, thereby obtaining semi-solid pure aluminum material;
[0047] S2, Preparation of low-melting-point impurity liquid phase: The semi-solid pure aluminum material of S1 is kept at a predetermined temperature to allow eutectic impurity elements in the solid phase to migrate into the liquid phase, thereby obtaining a semi-solid pure aluminum material containing a low-melting-point impurity liquid phase.
[0048] S3, Hypergravity Separation and Purification: The semi-solid pure aluminum material containing a low-melting-point impurity liquid phase in S2 is subjected to hypergravity separation and purification treatment. Under the action of the hypergravity field, the low-melting-point impurity liquid phase undergoes directional migration and separates from the solid phase, resulting in a high-conductivity high-purity aluminum solid phase material and an aluminum material containing low-melting-point impurities.
[0049] Specifically, the raw material S1 contains more than 99.0% aluminum, and its impurity elements include Fe and Si.
[0050] Specifically, the predetermined temperature T in S1 is determined based on the liquidus temperature T0 of the raw material pure aluminum and the initial precipitation temperature T1 of the eutectic phase of the impurity element, and the relationship is: T=(T0+T1) / 2±T3, where T3≤ 3℃.
[0051] Specifically, the semi-solid state of the semi-solid pure aluminum material in S1 is a state in which solid and liquid phases coexist; the solid-liquid ratio is related to the impurity content in the raw material, and the more impurities there are, the greater the proportion of liquid phase.
[0052] Specifically, the heating rate of the centrifuge heating furnace in S1 is 7℃ / min, and the heating method is direct one-step heating to the predetermined temperature.
[0053] Specifically, the semi-solid pure aluminum material in S2 is held at the predetermined temperature for 20-60 minutes.
[0054] Specifically, the process parameters for the ultragravity separation and purification process in S3 include: a gravity coefficient of 100-600 and an ultragravity separation time of 1-5 min.
[0055] In particular, the removal rate of eutectic impurity elements in the raw material pure aluminum in S3 is higher than 80%, the aluminum loss rate is less than 10%, and the conductivity of the prepared high-conductivity high-purity aluminum material is increased to a maximum of 66.5% IACS and a minimum of 63.8% IACS.
[0056] Specifically, the method for removing low-melting-point eutectic impurities from the highly conductive pure aluminum material can purify 10 kg of raw pure aluminum material in a single operation. If the process is repeated multiple times, the removal rate of eutectic impurity elements in the raw pure aluminum material decreases with the increase of the number of operations. According to experimental testing, after purifying the raw pure aluminum material a maximum of 3 times, it is not suitable for removing eutectic impurity elements from the raw pure aluminum material.
[0057] Example 1
[0058] This embodiment describes a method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials. The experimental material is 1060 pure aluminum with an aluminum content higher than 99.6%, and the main impurity elements are Fe and Si. Its liquidus temperature is 658℃, and the precipitation temperature of the eutectic phase of the impurity elements is 648℃. The predetermined temperature T is determined based on the liquidus temperature T0 of the raw pure aluminum material and the precipitation temperature T1 of the eutectic phase of the impurity elements, with the relationship being: T=(T0+T1) / 2±T3, where T3≤ 3℃. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials includes the following steps:
[0059] S1. Heating to the predetermined temperature: In the centrifuge heating furnace, the raw material 1060 pure aluminum material is heated to 653℃ to ensure that the pure aluminum material is in a semi-solid state. The heating method is to heat to the predetermined temperature in one step, and the heating rate is 7℃ / min. The semi-solid state of the semi-solid pure aluminum material is a state in which solid and liquid phases coexist, and thus semi-solid pure aluminum material is obtained.
[0060] S2. Preparation of low-melting-point impurity liquid phase: The semi-solid pure aluminum material in S1 is kept at a predetermined temperature for 20 minutes to allow eutectic impurity elements in the solid phase to migrate into the liquid phase, thereby obtaining a semi-solid pure aluminum material containing a low-melting-point impurity liquid phase.
[0061] S3, Hypergravity Separation and Purification: The semi-solid pure aluminum material containing a low-melting-point impurity liquid phase in S2 is subjected to hypergravity separation and purification treatment. The gravity coefficient is 200 and the hypergravity separation time is 2 minutes. Under the action of the hypergravity field, the low-melting-point impurity liquid phase undergoes directional migration and separates from the solid phase, resulting in a high-conductivity high-purity aluminum solid phase material and an aluminum material containing low-melting-point impurities.
[0062] The microstructure of highly conductive, high-purity aluminum solid materials and aluminum materials containing low-melting-point impurities separated by gravity was observed using SEM, such as... Figure 2 and Figure 3 As shown, it can be clearly observed that the aluminum matrix of the high-conductivity, high-purity aluminum solid material consists of spherical aluminum crystal particles, with the black areas representing voids. In contrast, the aluminum material containing low-melting-point impurities exhibits a large number of bright white precipitates. This suggests that under the influence of hypergravity, the low-melting-point eutectic phase in the pure aluminum material enters the lower part of the crucible.
[0063] In this embodiment, ICP analysis was used to separate the high-conductivity, high-purity aluminum solid material and the aluminum material containing low-melting-point impurities by gravity. The removal rates of impurity elements Fe and Si were calculated to be 82.84% and 80.16%, respectively, with an aluminum loss rate of 7.24%. The conductivity of the prepared high-conductivity, high-purity aluminum material was improved to 64.5% IACS.
[0064] The method for removing low-melting-point eutectic impurities in highly conductive pure aluminum material in this embodiment can purify 10 kg of raw pure aluminum material in a single operation. If the process is repeated multiple times, the removal rate of eutectic impurity elements in the raw pure aluminum material decreases with the increase of the number of operations. According to experimental testing, after purifying the raw pure aluminum material for a maximum of 2 operations, it is not suitable for removing eutectic impurity elements from the raw pure aluminum material.
[0065] Example 2
[0066] This embodiment describes a method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials. The experimental material is 1050 pure aluminum with an aluminum content higher than 99.5%, and the main impurity elements are Fe and Si. Its liquidus temperature is 658℃, and the precipitation temperature of the eutectic phase of the impurity elements is 650℃. The predetermined temperature T is determined based on the liquidus temperature T0 of the raw pure aluminum material and the precipitation temperature T1 of the eutectic phase of the impurity elements, with the relationship being: T=(T0+T1) / 2±T3, where T3≤ 3℃. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials includes the following steps:
[0067] S1. Heating to the predetermined temperature: In the centrifuge heating furnace, the raw material 1050 pure aluminum material is heated to 653℃ to ensure that the pure aluminum material is in a semi-solid state. The heating method is to heat to the predetermined temperature in one step, and the heating rate is 7℃ / min. The semi-solid state of the semi-solid pure aluminum material is a state in which solid and liquid phases coexist, and semi-solid pure aluminum material is obtained.
[0068] S2. Preparation of low-melting-point impurity liquid phase: The semi-solid pure aluminum material in S1 is kept at a predetermined temperature for 40 min, so that the eutectic impurity elements in the solid phase migrate into the liquid phase, and a semi-solid pure aluminum material containing a low-melting-point impurity liquid phase is obtained.
[0069] S3. Hypergravity separation and purification: The semi-solid pure aluminum material containing a low-melting-point impurity liquid phase in S2 is subjected to hypergravity separation and purification treatment. The gravity coefficient is 400 and the hypergravity separation time is 3 minutes. Under the action of the hypergravity field, the low-melting-point impurity liquid phase undergoes directional migration and separates from the solid phase, resulting in a high-conductivity high-purity aluminum solid phase material and an aluminum material containing low-melting-point impurities.
[0070] In this embodiment, ICP analysis was used to separate the high-conductivity, high-purity aluminum solid material and the aluminum material containing low-melting-point impurities by gravity. The removal rates of impurity elements Fe and Si were calculated to be 81.54% and 85.47%, respectively, with an aluminum loss rate of 7.56%. The conductivity of the prepared high-conductivity, high-purity aluminum material was improved to 64.4% IACS.
[0071] The method for removing low-melting-point eutectic impurities in highly conductive pure aluminum material in this embodiment can purify 10 kg of raw pure aluminum material in a single process. If the process is repeated multiple times, the removal rate of eutectic impurity elements in the raw pure aluminum material decreases with the increase of the number of times. According to experimental tests, after purifying the raw pure aluminum material a maximum of 3 times, it is not suitable for removing eutectic impurity elements from the raw pure aluminum material.
[0072] Example 3
[0073] This embodiment describes a method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials. The experimental material is 1100 pure aluminum with an aluminum content higher than 99.0%, and the main impurity elements are Fe and Si. Its liquidus temperature is 656℃, and the precipitation temperature of the eutectic phase of the impurity elements is 646℃. The predetermined temperature T is determined based on the liquidus temperature T0 of the raw pure aluminum material and the precipitation temperature T1 of the eutectic phase of the impurity elements, with the relationship being: T=(T0+T1) / 2±T3, where T3≤ 3℃. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials includes the following steps:
[0074] S1. Heating to the predetermined temperature: In the centrifuge heating furnace, the raw material 1100 pure aluminum material is heated to 648℃ to ensure that the pure aluminum material is in a semi-solid state. The heating method is to heat to the predetermined temperature in one step, and the heating rate is 7℃ / min. The semi-solid state of the semi-solid pure aluminum material is a state in which solid and liquid phases coexist, and thus semi-solid pure aluminum material is obtained.
[0075] S2. Preparation of low-melting-point impurity liquid phase: The semi-solid pure aluminum material in S1 is kept at a predetermined temperature for 60 min, so that the eutectic impurity elements in the solid phase migrate into the liquid phase, and a semi-solid pure aluminum material containing a low-melting-point impurity liquid phase is obtained.
[0076] S3. Hypergravity separation and purification: The semi-solid pure aluminum material containing a low-melting-point impurity liquid phase in S2 is subjected to hypergravity separation and purification treatment. The gravity coefficient is 600 and the hypergravity separation time is 5 minutes. Under the action of the hypergravity field, the low-melting-point impurity liquid phase undergoes directional migration and separates from the solid phase, resulting in a high-conductivity high-purity aluminum solid phase material and an aluminum material containing low-melting-point impurities.
[0077] In this embodiment, ICP analysis was used to separate the high-conductivity, high-purity aluminum solid material and the aluminum material containing low-melting-point impurities by gravity. The removal rates of impurity elements Fe and Si were calculated to be 92.86% and 89.59%, respectively, with an aluminum loss rate of 9.18%. The conductivity of the prepared high-conductivity, high-purity aluminum material was improved to 63.8% IACS.
[0078] The method for removing low-melting-point eutectic impurities in highly conductive pure aluminum material in this embodiment can purify 10 kg of raw pure aluminum material in a single process. If the process is repeated multiple times, the removal rate of eutectic impurity elements in the raw pure aluminum material decreases with the increase of the number of times. According to experimental tests, after purifying the raw pure aluminum material a maximum of 3 times, it is not suitable for removing eutectic impurity elements from the raw pure aluminum material.
[0079] Example 4
[0080] This embodiment describes a method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials. The experimental material is 1070 pure aluminum with an aluminum content higher than 99.7%, and the main impurity elements are Fe and Si. Its liquidus temperature is 659℃, and the precipitation temperature of the eutectic phase of the impurity elements is 650℃. The predetermined temperature T is determined based on the liquidus temperature T0 of the raw pure aluminum material and the precipitation temperature T1 of the eutectic phase of the impurity elements, with the relationship being: T=(T0+T1) / 2±T3, where T3≤ 3℃. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials includes the following steps:
[0081] S1. Heating to the predetermined temperature: In the centrifuge heating furnace, the raw material 1070 pure aluminum material is heated to 655℃ to ensure that the pure aluminum material is in a semi-solid state. The heating method is to heat to the predetermined temperature in one step, and the heating rate is 7℃ / min. The semi-solid state of the semi-solid pure aluminum material is a state in which solid and liquid phases coexist, and thus semi-solid pure aluminum material is obtained.
[0082] S2. Preparation of low-melting-point impurity liquid phase: The semi-solid pure aluminum material in S1 is kept at a predetermined temperature for 30 minutes to allow eutectic impurity elements in the solid phase to migrate into the liquid phase, thereby obtaining a semi-solid pure aluminum material containing a low-melting-point impurity liquid phase.
[0083] S3, Hypergravity Separation and Purification: The semi-solid pure aluminum material containing a low-melting-point impurity liquid phase in S2 is subjected to hypergravity separation and purification treatment. The gravity coefficient is 600 and the hypergravity separation time is 1 min. Under the action of the hypergravity field, the low-melting-point impurity liquid phase undergoes directional migration and separates from the solid phase, resulting in a high-conductivity high-purity aluminum solid phase material and an aluminum material containing low-melting-point impurities.
[0084] In this embodiment, ICP analysis was used to separate the high-conductivity, high-purity aluminum solid material and the aluminum material containing low-melting-point impurities by gravity. The removal rates of impurity elements Fe and Si were calculated to be 88.57% and 85.61%, respectively, with an aluminum loss rate of 7.58%. The conductivity of the prepared high-conductivity, high-purity aluminum material was improved to 65.58% IACS.
[0085] The method for removing low-melting-point eutectic impurities in highly conductive pure aluminum material in this embodiment can purify 10 kg of raw pure aluminum material in a single operation. If the process is repeated multiple times, the removal rate of eutectic impurity elements in the raw pure aluminum material decreases with the increase of the number of operations. According to experimental testing, after purifying the raw pure aluminum material for a maximum of 2 operations, it is not suitable for removing eutectic impurity elements from the raw pure aluminum material.
[0086] Example 5
[0087] This embodiment describes a method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials. The experimental material is 1080 pure aluminum with an aluminum content higher than 99.80%, and the main impurity elements are Fe and Si. Its liquidus temperature is 659.5℃, and the precipitation temperature of the eutectic phase of the impurity elements is 646.5℃. The predetermined temperature T is determined based on the liquidus temperature T0 of the raw pure aluminum material and the precipitation temperature T1 of the eutectic phase of the impurity elements, with the relationship being: T=(T0+T1) / 2±T3, where T3≤ 3℃. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials includes the following steps:
[0088] S1. Heating to the predetermined temperature: In the centrifuge heating furnace, the raw material 1080 pure aluminum material is heated to 657℃ to ensure that the pure aluminum material is in a semi-solid state. The heating method is to heat to the predetermined temperature in one step, and the heating rate is 7℃ / min. The semi-solid state of the semi-solid pure aluminum material is a state in which solid and liquid phases coexist, thus obtaining semi-solid pure aluminum material.
[0089] S2, Preparation of low-melting-point impurity liquid phase: The semi-solid pure aluminum material of S1 is kept at a predetermined temperature for 35 min, so that the eutectic impurity elements in the solid phase migrate into the liquid phase, and a semi-solid pure aluminum material containing a low-melting-point impurity liquid phase is obtained.
[0090] S3. Hypergravity separation and purification: The semi-solid pure aluminum material containing a low-melting-point impurity liquid phase in S2 is subjected to hypergravity separation and purification treatment. The gravity coefficient is 600 and the hypergravity separation time is 3 minutes. Under the action of the hypergravity field, the low-melting-point impurity liquid phase undergoes directional migration and separates from the solid phase, resulting in a high-conductivity high-purity aluminum solid phase material and an aluminum material containing low-melting-point impurities.
[0091] In this embodiment, ICP analysis was used to separate the high-conductivity, high-purity aluminum solid material and the aluminum material containing low-melting-point impurities by gravity. The removal rates of impurity elements Fe and Si were calculated to be 89.27% and 90.72%, respectively, with an aluminum loss rate of 8.37%. The conductivity of the prepared high-conductivity, high-purity aluminum material was improved to 65.91% IACS.
[0092] The method for removing low-melting-point eutectic impurities in highly conductive pure aluminum material in this embodiment can purify 10 kg of raw pure aluminum material in a single operation. If the process is repeated multiple times, the removal rate of eutectic impurity elements in the raw pure aluminum material decreases with the increase of the number of operations. According to experimental testing, after purifying the raw pure aluminum material for a maximum of 2 operations, it is not suitable for removing eutectic impurity elements from the raw pure aluminum material.
[0093] Example 6
[0094] This embodiment describes a method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials. The experimental material is 1085 pure aluminum with an aluminum content higher than 99.85%, and the main impurity elements are Fe and Si. Its liquidus temperature is 660℃, and the precipitation temperature of the eutectic phase of the impurity elements is 650℃. The predetermined temperature T is determined based on the liquidus temperature T0 of the raw pure aluminum material and the precipitation temperature T1 of the eutectic phase of the impurity elements, with the relationship being: T=(T0+T1) / 2±T3, where T3≤ 3℃. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials includes the following steps:
[0095] S1. Heating to the predetermined temperature: In the centrifuge heating furnace, the raw material 1085 pure aluminum material is heated to 658℃ to ensure that the pure aluminum material is in a semi-solid state. The heating method is to heat to the predetermined temperature in one step, and the heating rate is 7℃ / min. The semi-solid state of the semi-solid pure aluminum material is a state in which solid and liquid phases coexist, thus obtaining semi-solid pure aluminum material.
[0096] S2. Preparation of low-melting-point impurity liquid phase: The semi-solid pure aluminum material in S1 is kept at a predetermined temperature for 45 min, so that the eutectic impurity elements in the solid phase migrate into the liquid phase, and a semi-solid pure aluminum material containing a low-melting-point impurity liquid phase is obtained.
[0097] S3. Hypergravity separation and purification: The semi-solid pure aluminum material containing a low-melting-point impurity liquid phase in S2 is subjected to hypergravity separation and purification treatment. The gravity coefficient is 600 and the hypergravity separation time is 5 minutes. Under the action of the hypergravity field, the low-melting-point impurity liquid phase undergoes directional migration and separates from the solid phase, resulting in a high-conductivity high-purity aluminum solid phase material and an aluminum material containing low-melting-point impurities.
[0098] In this embodiment, ICP analysis was used to separate the high-conductivity, high-purity aluminum solid material and the aluminum material containing low-melting-point impurities by gravity. The removal rates of impurity elements Fe and Si were calculated to be 91.27% and 92.52%, respectively, with an aluminum loss rate of 9.58%. The conductivity of the prepared high-conductivity, high-purity aluminum material was improved to 66.5% IACS.
[0099] The method for removing low-melting-point eutectic impurities in highly conductive pure aluminum material in this embodiment can purify 10 kg of raw pure aluminum material in a single operation. If the process is repeated multiple times, the removal rate of eutectic impurity elements in the raw pure aluminum material decreases with the increase of the number of operations. According to experimental testing, after purifying the raw pure aluminum material for a maximum of 2 operations, it is not suitable for removing eutectic impurity elements from the raw pure aluminum material.
[0100] The above-mentioned solution proposes a method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials. This method can solve the technical problems of high energy consumption, unstable quality, and serious pollution in existing aluminum refining technologies, as well as the technical problem that a large number of low-melting-point eutectic impurities are difficult to effectively separate in the liquid phase due to capillary action. It can also solve the technical problems of uneven impurity removal, potential side reactions, difficulty in control, and difficulty in deep removal caused by the selection and addition of refining agents, and the technical problems of high water and other resource consumption and high energy consumption.
[0101] The method of the present invention can make pure aluminum material in a semi-solid state by heating it to a predetermined temperature. This state is conducive to the continuous migration of iron-rich inclusions in the solid phase to the liquid phase at the grain boundaries.
[0102] The method of this invention prepares a low-melting-point liquid phase containing impurities, which enables eutectic impurity elements in the solid phase to migrate into the liquid phase. The migration rate of these eutectic impurity elements is affected by the holding temperature and time. Therefore, the preset temperature T is determined based on the liquidus temperature T0 of the raw material pure aluminum and the initial precipitation temperature T1 of the eutectic phase of the impurity elements. The relationship is: T=(T0+T1) / 2±T3, where T3≤ 3℃; the holding time is selected as 20-60min.
[0103] The method of this invention uses high gravity separation and purification to promote the migration of the iron-rich phase in the solid to the liquid phase at the grain boundaries, and to squeeze the liquid phase impurities at the grain boundaries out of the aluminum matrix, thereby achieving the effect of extreme impurity removal.
[0104] The eutectic impurity element removal rate of the raw material pure aluminum of the present invention is higher than 80%, the aluminum loss rate is lower than 10%, and the conductivity of the prepared high-conductivity high-purity aluminum material is increased to a maximum of 66.5% IACS and a minimum of 63.8% IACS.
[0105] In summary, compared with traditional methods, the method of the present invention purifies the raw material pure aluminum material at low temperature, low cost, and high efficiency by heating the raw material pure aluminum material to a predetermined temperature to make it semi-solid, preparing it into a low-melting-point liquid phase containing impurities, and separating and purifying it by gravity. This method can effectively overcome the influence of capillary action, enhance solid-liquid separation, is simple and easy to operate, has low cost, low energy consumption, and high efficiency, and is conducive to large-scale industrial production and promotion.
[0106] It should be understood that the term "and / or" in this article is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. Additionally, the character " / " in this article generally indicates an "or" relationship between the preceding and following related objects, but it can also represent an "and / or" relationship. Please refer to the context for a more accurate understanding.
[0107] In this invention, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of a single item or a plurality of items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, and c can be a single item or multiple items.
[0108] It should be understood that, in various embodiments of the present invention, the order of the above-mentioned process numbers does not imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present invention.
[0109] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials, characterized in that, The method for removing low-melting-point eutectic impurities from the highly conductive pure aluminum material includes the following steps: S1. Heating to a predetermined temperature: In a centrifuge heating furnace, the raw pure aluminum material is heated to a predetermined temperature to ensure that the pure aluminum material is in a semi-solid state, thereby obtaining semi-solid pure aluminum material; S2. Preparation of low-melting-point impurity liquid phase: The semi-solid pure aluminum material in S1 is kept at a predetermined temperature to allow eutectic impurity elements in the solid phase to migrate into the liquid phase, thereby obtaining a semi-solid pure aluminum material containing a low-melting-point impurity liquid phase. S3, Hypergravity Separation and Purification: The semi-solid pure aluminum material containing a low-melting-point impurity liquid phase in S2 is subjected to hypergravity separation and purification treatment. Under the action of the hypergravity field, the low-melting-point impurity liquid phase undergoes directional migration and separates from the solid phase, resulting in a high-conductivity high-purity aluminum solid phase material and an aluminum material containing low-melting-point impurities.
2. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials according to claim 1, characterized in that, The raw material S1 contains more than 99.0% aluminum, and its impurity elements include Fe and Si.
3. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials according to claim 1, characterized in that, The predetermined temperature T in S1 is determined based on the liquidus temperature T0 of the raw material pure aluminum and the initial precipitation temperature T1 of the eutectic phase of the impurity element. The relationship is: T=(T0+T1) / 2±T3, where T3≤ 3℃.
4. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials according to claim 1, characterized in that, The semi-solid state of the semi-solid pure aluminum material in S1 is a state in which solid and liquid phases coexist; the solid-liquid ratio is related to the impurity content in the raw material, the more impurities there are, the greater the proportion of liquid phase.
5. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials according to claim 1, characterized in that, The heating rate of the centrifuge heating furnace in S1 is 7℃ / min, and the heating method is direct one-step heating to the predetermined temperature.
6. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials according to claim 1, characterized in that, The semi-solid pure aluminum material in S2 is held at the predetermined temperature for 20-60 minutes.
7. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials according to claim 1, characterized in that, The process parameters for the ultragravity separation and purification process in S3 include: a gravity coefficient of 100-600 and an ultragravity separation time of 1-5 min.
8. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials according to claim 1, characterized in that, The removal rate of eutectic impurity elements in the raw material pure aluminum in S3 is higher than 80%, and the aluminum loss rate is less than 10%. The conductivity of the prepared high-conductivity high-purity aluminum material is increased to a maximum of 66.5% IACS and a minimum of 63.8% IACS.
9. The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum materials according to claim 1, characterized in that, The method for removing low-melting-point eutectic impurities from highly conductive pure aluminum material described in S3 can purify 10 kg of raw pure aluminum material in a single process. However, if the process is repeated multiple times, the removal rate of eutectic impurity elements decreases with each subsequent purification attempt. Experimental testing showed that after three purification attempts, this method is no longer suitable for further removal of eutectic impurity elements from the raw pure aluminum material.