Method for directly casting aluminum alloy through cooperation of secondary aluminum and electrolytic aluminum liquid

Abstract

The invention relates to the field of non-ferrous metallurgy and resource recycling, in particular to a method for directly casting aluminum alloy through cooperation of secondary aluminum and electrolytic aluminum liquid, and the method comprises the steps that S1, secondary aluminum raw materials are crushed, and iron and non-iron impurities are removed; s2, smelting the pretreated secondary aluminum raw material, sampling, and rapidly determining the chemical components of the secondary aluminum raw material; s3, the proportion of the secondary aluminum melt, the electrolytic aluminum liquid and the necessary alloy additives is calculated; s4, the secondary aluminum melt and the high-temperature electrolytic aluminum liquid are mixed, an alloy additive is added according to the proportion in the step S3, and aluminum alloy melt obtained after collaborative smelting is obtained through uniform stirring; s5, the aluminum alloy melt obtained after collaborative smelting is subjected to refining and online treatment; and S6, the aluminum alloy melt treated in the step S5 is cast into an aluminum alloy product in a specified shape. The method has the effect of solving the problems of high energy consumption, large burning loss, difficulty in component control, long flow, low added value of products and the like in secondary aluminum utilization.

Description

Technical Field

[0001] This application relates to the field of non-ferrous metal metallurgy and resource recycling, and in particular to a method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid. Background Technology

[0002] Aluminum alloys are widely used in various fields such as automobiles, aerospace, rail transportation, and food packaging due to their excellent properties, such as lightweight, high strength, good corrosion resistance, and machinability. Currently, aluminum alloy production mainly relies on adding alloying components or microalloying elements to primary aluminum (electrolytic aluminum liquid) or pure aluminum ingots. However, the production process of primary aluminum or pure aluminum ingots is complex, requiring the extraction of alumina from bauxite followed by molten electrolysis. This not only results in a long and costly process but also involves significant resource consumption and puts considerable pressure on the environment.

[0003] Meanwhile, recycled aluminum, as an important aluminum resource, derives its raw materials from scrap aluminum and aluminum alloys or aluminum-containing waste, which are widely distributed in industries such as vehicles, power, construction, electronics, and food packaging. Although recycled aluminum resources are abundant, their complex composition, diverse specifications, and significant differences in shape and specific gravity make sorting, alloy composition proportioning, and smelting and refining during the recycling process extremely difficult. These problems not only affect the crystallization quality of aluminum alloy products but also reduce their mechanical properties. With the increase in vehicle scrapping, the surge in food packaging, and the approaching end of the service life of many aluminum products, the amount of recycled aluminum resources both domestically and internationally is growing rapidly.

[0004] In existing technologies, there are several patents related to recycled aluminum production processes. For example, by using recycled aluminum production equipment to perform multiple cleaning processes of varying degrees on the molten recycled aluminum, impurities in the recycled aluminum are effectively reduced, ensuring the quality of the recycled aluminum. Alternatively, an automated aluminum-iron separation process for recycled aluminum melting is used to effectively separate metallic iron and metallic aluminum during the recycled aluminum smelting process, improving the quality of aluminum alloys and the metal recovery rate. This process is highly automated, energy-saving, and environmentally friendly. However, although existing technologies have achieved efficient separation of metallic aluminum and iron from recycled aluminum and employ crucible furnace-type or reverberatory furnace-type smelting furnaces for the smelting and refining of recycled aluminum to produce aluminum alloy ingots, the entire process still suffers from problems such as high energy consumption, high metal loss, and low product added value. Summary of the Invention

[0005] To address the problems of high energy consumption, large burn-off, difficulty in composition control, long process, and low product added value in the utilization of recycled aluminum, this application provides a method for directly casting aluminum alloys using recycled aluminum in conjunction with electrolytic aluminum liquid.

[0006] This application provides a method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid, employing the following technical solution: A method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid includes the following steps: S1. Raw material sorting and pretreatment: The recycled aluminum raw materials are classified into cast aluminum alloys and wrought aluminum alloys, and crushed according to their physical property differences. Then, they are sorted to remove ferrous and non-ferrous impurities. S2. Pre-melting and composition analysis of recycled aluminum: The pretreated recycled aluminum raw material is smelted under a protective atmosphere to obtain recycled aluminum melt. Then, the recycled aluminum melt is sampled and its chemical composition is rapidly determined. S3. Batching Calculation: Based on the composition standard of the target aluminum alloy grade and the composition of the recycled aluminum melt measured in step S2, calculate the ratio of recycled aluminum melt, electrolytic aluminum liquid and necessary alloying additives. S4. Co-melting: The recycled aluminum melt obtained in step S2 is mixed with the high-temperature electrolytic aluminum liquid from the electrolytic aluminum plant, and alloy additives are added according to the proportion in step S3. After stirring evenly, the aluminum alloy melt after co-melting is obtained. S5. Melt treatment: Refining and online treatment of the aluminum alloy melt after co-melting, wherein the online treatment includes at least degassing, slag removal and grain refinement; S6. Casting: The aluminum alloy melt processed in step S5 is cast into an aluminum alloy product of a specified shape.

[0007] By adopting the above technical solution, recycled aluminum is first classified into cast and wrought aluminum alloys and crushed differently, combined with magnetic separation and color sorting for deep impurity removal. Secondly, the recycled aluminum is pre-melted under a protective atmosphere and subjected to rapid compositional analysis, pre-locking the composition of the recycled aluminum to avoid repeated adjustments and resource waste caused by fluctuations in the composition of recycled aluminum in traditional processes. Based on the target grade requirements, the precise ratio of recycled aluminum melt, electrolytic aluminum liquid, and alloy additives is calculated, allowing the high purity of the electrolytic aluminum liquid to complement the alloying element advantages of the recycled aluminum, reducing energy consumption and burn-off in the electrolytic aluminum remelting process. Simultaneously, the resource value of recycled aluminum is fully utilized through co-melting. Subsequently, the melt undergoes refining, vacuum degassing, filtration to remove slag, and ultrasonic refining treatment to further purify the melt and improve the uniformity of the microstructure, effectively enhancing the mechanical properties and yield of the aluminum alloy. Finally, the cast products, due to their precise composition and controllable impurities, can be directly used in high-value-added applications.

[0008] Preferably, in step S1, the crushing process based on differences in physical properties specifically involves: For brittle cast aluminum alloys, mechanical crushing is used to break them into block-shaped materials. For wrought aluminum alloys with good toughness, a high-shear-force mechanical shredding method is used to shear them to obtain sheet or strip materials.

[0009] By adopting the above technical solutions, cast aluminum alloys, due to their high brittleness, can be quickly separated into blocky materials by mechanical crushing, avoiding excessive entanglement or fine powder generation when shredding tough materials, thus improving crushing efficiency and reducing material loss. Wrought aluminum alloys, due to their good toughness, can be precisely sheared into sheet or strip materials by high-shear mechanical shredding. The regular shape design ensures more thorough separation of impurities from the aluminum matrix during subsequent magnetic separation for iron removal and color sorting for non-ferrous impurities. Simultaneously, the heating and flow of the melt are more uniform during pre-melting, reducing smelting energy consumption and avoiding over- or under-processing of the two types of recycled aluminum by uniform crushing. If wrought aluminum alloys are crushed, their toughness leads to long crushing times, high energy consumption, and the generation of fine particles that are difficult to separate. If cast aluminum alloys are shredded, their brittleness leads to excessive material crushing, increasing the difficulty of subsequent impurity removal and the risk of burn-off.

[0010] Preferably, the sorting includes at least: Iron impurities are removed by magnetic separation; Non-ferrous impurities in plastics are removed by color sorting or air sorting.

[0011] By adopting the above technical solutions, magnetic separation utilizes the difference in ferromagnetism to accurately capture iron impurities in recycled aluminum, controlling the iron content to an extremely low level. This avoids problems such as aluminum alloy embrittlement and reduced corrosion resistance caused by excessive iron residue during subsequent smelting. Color separation quickly separates light-colored or dark-colored plastic fragments based on the color difference of the material, while air separation separates lighter plastics with lower density through airflow. The synergistic effect of the two can efficiently remove non-ferrous plastic impurities mixed in recycled aluminum, improve impurity removal efficiency, and avoid the hidden dangers of melt contamination and porosity defects caused by carbides, hydrogen, etc. generated by high-temperature decomposition of plastics during smelting.

[0012] Preferably, in step S2, the smelting is carried out in a rotary kiln, and the smelting specifically involves: promoting the homogenization of the melt composition and accelerating the smelting process through the rolling motion of the rotary kiln; the protective atmosphere specifically involves: introducing an inert gas into the furnace to form a protective atmosphere.

[0013] By adopting the above technical solutions, the rotary kiln's rolling motion continuously tumbles the material, avoiding the localized temperature differences and compositional segregation problems associated with static melting. This ensures that the recycled aluminum raw material fully contacts the thermal field during melting, shortening the melting time and promoting uniform diffusion of components in different regions of the melt. This guarantees the accuracy of subsequent sampling and testing, and the analysis results of the melt with uniform composition more accurately reflect the overall composition, avoiding errors in batching calculations caused by localized component deviations. Simultaneously, the protective atmosphere created by introducing inert gas into the furnace isolates oxygen and moisture from the air, inhibiting the oxidation reaction of active elements in the recycled aluminum and the dissolution of hydrogen generated from moisture decomposition into the melt. This reduces the aluminum oxidation loss rate, decreases aluminum slag production, improves resource utilization, and reduces the load on subsequent slag removal processes. Furthermore, the inert gas atmosphere also avoids metallurgical defects caused by gas absorption in the melt, laying the foundation for pure mixing with the electrolytic aluminum liquid during subsequent co-melting and for the final aluminum alloy product.

[0014] Preferably, the melting temperature is controlled within the range of 700℃-730℃, and the melting time is controlled within the range of 20min-30min.

[0015] By adopting the above technical solution, the melting point of aluminum, the main component of recycled aluminum, is about 660℃. The temperature of 700℃-730℃ can ensure that the recycled aluminum raw materials containing alloying elements such as magnesium and silicon are completely melted, while not exceeding the temperature of severe oxidation or volatilization of most active elements. Combined with inert gas protection, the oxidation and gas absorption of aluminum are further suppressed. The 20min-30min melting time and the rolling motion of the rotary kiln work together to ensure that the material is heated evenly in the hot zone. This avoids the problem of local over-melting or under-melting caused by uneven heating in traditional furnaces, and does not require extending the melting time to increase energy consumption. At the same time, it ensures the uniformity of the melt composition.

[0016] Preferably, in step S3, the ingredient calculation follows the following principles: When the target grade is cast aluminum alloy, cast recycled aluminum melt should be given priority as the main raw material. When the target grade is wrought aluminum alloy, wrought recycled aluminum melt should be given priority as the main raw material.

[0017] By adopting the above technical solutions, cast aluminum alloys typically have specific requirements for the content of elements such as silicon and copper. Cast recycled aluminum, due to its inherently high silicon content and composition closer to the target range for cast aluminum alloys, is preferentially selected as the main raw material. This reduces the mixing ratio with electrolytic aluminum liquid, preserving the beneficial alloying elements already present in the recycled aluminum while avoiding the waste of adding high-cost intermediate alloys after dilution of the electrolytic aluminum liquid. Similarly, wrought aluminum alloys have stricter control over elements such as magnesium and manganese. Wrought recycled aluminum, because its original composition has magnesium and manganese content more suitable for the requirements of wrought aluminum alloys, is preferentially selected as the main raw material. This reduces the amount of alloy additives needed and minimizes compositional fluctuations caused by mixing recycled aluminum from different sources. This not only maximizes the preservation of the advantageous components of recycled aluminum and reduces the remelting energy consumption of the electrolytic aluminum liquid, but also reduces stirring time and temperature fluctuations during subsequent co-melting by precisely controlling the initial composition of the melt.

[0018] Preferably, in step S4, the recycled aluminum melt is transported to the alloy production workshop through an aluminum ladle or insulated pipeline and mixed with the high-temperature electrolytic aluminum liquid; The stirring device is activated during the mixing process with the high-temperature electrolytic aluminum liquid from the electrolytic aluminum plant to ensure uniform melt composition.

[0019] By adopting the above technical solution, the pre-melted recycled aluminum melt is transported through an aluminum ladle or insulated pipe, suppressing heat loss during the transfer process and maintaining the recycled aluminum melt at a suitable temperature close to the pre-melting endpoint. This avoids the formation of cold clumps due to cooling, which would hinder the diffusion and fusion with the high-temperature electrolytic aluminum liquid. During the mixing process, the stirring device is turned on, and mechanical force is used to promote the flow and contact of the two melts, allowing the alloying elements pre-retained in the recycled aluminum to diffuse rapidly and evenly with the pure aluminum matrix of the electrolytic aluminum liquid, eliminating the problem of uneven composition that is easily left behind by static mixing.

[0020] Preferably, in step S5, the refining temperature is 730-750℃, high-purity argon and refining agent are introduced during the refining process, and the refining time is 15-20 minutes. After refining, the material needs to be kept at 760-780℃ for 30-40 minutes.

[0021] By adopting the above technical solution, the refining stage temperature is limited to 730-750℃, which avoids insufficient reaction of the refining agent at low temperatures and prevents the high temperature from aggravating the oxidation and burn-off of aluminum. High-purity argon gas and refining agent are introduced simultaneously. When the argon gas bubbles rise in the melt, they adsorb hydrogen and inclusions and carry them to the surface. The refining agent reduces the surface tension of the melt through chemical reaction, promotes the decomposition of oxides and combines with hydrogen to form bubbles that are discharged. The refining time of 15-20 minutes is precisely matched with the kinetic process of gas escape and inclusion aggregation, which ensures thorough degassing and slag removal and avoids the drop in melt temperature and increase in energy consumption caused by over-refining. The subsequent holding at 760-780℃ for 30-40 minutes uses a thermal field slightly higher than the refining temperature to promote the continued rise of residual small bubbles and further aggregation and sedimentation of tiny inclusions. At the same time, it allows the components of the recycled aluminum and electrolytic aluminum liquid to be fully diffused and uniformly mixed.

[0022] Preferably, in step S5, the degassing is performed using a vacuum degassing method, the slag removal is performed using a filtration method, and the grain refinement is performed using an ultrasonic treatment method.

[0023] By adopting the above technical solutions, the vacuum degassing method reduces the pressure of the melt environment and forces dissolved hydrogen to escape by utilizing the physical principle of hydrogen partial pressure difference, thus eliminating porosity defects inside the aluminum alloy after casting; the filtration method uses multi-stage ceramic filter plates to intercept residual oxides, nitrides and other tiny inclusions in the melt. Compared with natural sedimentation or argon flotation slag removal, it can capture finer impurity particles, reduce the total amount of inclusions in the melt, and improve the density and fatigue strength of the aluminum alloy; the ultrasonic grain refinement method uses high-frequency vibration of 20-40kHz to stimulate the cavitation effect of the melt, breaking the original coarse dendritic structure and promoting uniform nucleation.

[0024] Preferably, in step S1, the recycled aluminum raw material for casting aluminum alloy includes waste materials from engine blocks, gearbox housings, and wheel hubs of automobiles and motorcycles. The recycled aluminum raw materials for deformed aluminum alloys include waste materials from beverage cans, compacted white materials, car door panels, engine hoods, aluminum profiles, wires, and pipes.

[0025] By adopting the above technical solutions, the raw materials for cast aluminum alloys are selected from waste materials such as engine blocks, gearbox housings, and wheel hubs from automobiles and motorcycles. Their original purpose is to make castings, and they are characterized by high silicon content and high brittleness, which naturally matches the high silicon requirements of cast aluminum alloys. When using mechanical crushing, brittle materials can be quickly separated into regular blocks of 50-150mm, reducing the generation of fine powder. Combined with magnetic separation and color sorting, impurities can be efficiently removed and excessive crushing of materials can be avoided, resulting in pre-treated recycled aluminum with uniform composition and low impurity content. The raw materials for wrought aluminum alloys come from waste materials such as aluminum cans and automobile door panels. The content of elements such as magnesium and manganese in the original composition is suitable for the mechanical performance requirements of wrought aluminum alloys. Using high-shear shredding, they can be cut into sheets of less than 100mm, which are easier to separate from lightweight impurities such as plastics, reducing the subsequent impurity removal load.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. First, recycled aluminum is classified into cast and wrought aluminum alloys and crushed differently, combined with magnetic separation and color sorting for deep impurity removal. Second, recycled aluminum is pre-melted under a protective atmosphere and subjected to rapid composition analysis to pre-lock the composition of recycled aluminum, avoiding repeated adjustments and resource waste caused by fluctuations in the composition of recycled aluminum in traditional processes. Based on the target grade requirements, the precise ratio of recycled aluminum melt, electrolytic aluminum liquid, and alloy additives is calculated, so that the high purity of electrolytic aluminum liquid and the alloy element advantages of recycled aluminum complement each other, reducing energy consumption and burn-off in the electrolytic aluminum remelting process. At the same time, the resource value of recycled aluminum is fully utilized through co-melting. Subsequently, the melt undergoes refining, vacuum degassing, filtration to remove slag, and ultrasonic refining to further purify the melt and improve the uniformity of the structure, effectively improving the mechanical properties and yield of the aluminum alloy. Finally, the cast product, due to its precise composition and controllable impurities, can be directly used in high-value-added applications, significantly shortening the long process of electrolysis-ingot casting-remelting-casting, and comprehensively reducing production costs and carbon emissions.

[0027] 2. The main component of recycled aluminum, aluminum, has a melting point of approximately 660℃. A temperature of 700℃-730℃ ensures that the recycled aluminum raw material containing alloying elements such as magnesium and silicon is completely melted without exceeding the temperature at which most active elements undergo severe oxidation or volatilization. Combined with inert gas protection, this further inhibits the oxidation and gas absorption of aluminum. The 20-30 minute melting time, combined with the rolling motion of the rotary kiln, ensures that the material is heated evenly in the thermal field. This avoids the problem of local over-melting or under-melting caused by uneven heating in traditional furnaces, and eliminates the need to extend the melting time to increase energy consumption. At the same time, it ensures the uniformity of the melt composition. Attached Figure Description

[0028] Figure 1 This is a schematic flowchart of the method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid in the embodiments of this application. Detailed Implementation

[0029] The following is in conjunction with the appendix Figure 1 This application will be described in further detail.

[0030] This application discloses a method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid. (Refer to...) Figure 1 The method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid includes the following steps: S1. Raw material sorting and pretreatment: The recycled aluminum raw materials are classified into cast aluminum alloys and wrought aluminum alloys, and crushed according to their differences in physical properties. Then, they are sorted to remove ferrous and non-ferrous impurities.

[0031] Specifically, the crushing process based on differences in physical properties is as follows: For cast aluminum alloys with high brittleness, mechanical crushing is used to break them into block-shaped materials; for wrought aluminum alloys with good toughness, mechanical tearing with high shear force is used to shear them into sheet-shaped or strip-shaped materials.

[0032] Due to their high brittleness, cast aluminum alloys can be quickly separated into lumps using mechanical crushing, avoiding excessive entanglement or fine powder generation when shredding tough materials. This improves crushing efficiency and reduces material loss. Wrought aluminum alloys, on the other hand, have good toughness. High-shear mechanical shredding can precisely cut them into sheets or strips. The regular shape design ensures more thorough separation of impurities from the aluminum matrix during subsequent magnetic separation and color sorting of non-ferrous impurities. At the same time, the heating and flow of the melt are more uniform during pre-melting, reducing smelting energy consumption. This avoids over- or under-processing of the two types of recycled aluminum by uniform crushing. If wrought aluminum alloys are crushed, their toughness leads to long crushing time, high energy consumption, and the generation of fine particles that are difficult to separate. If cast aluminum alloys are shredded, their brittleness leads to excessive material crushing, increasing the difficulty of subsequent impurity removal and the risk of burn-off.

[0033] In an optional embodiment, the sorting process includes at least: removing ferrous impurities by magnetic separation; and removing non-ferrous plastic impurities by color separation or air separation. Magnetic separation utilizes the difference in ferromagnetism to precisely capture ferrous impurities in recycled aluminum, controlling the iron content to an extremely low level to avoid problems such as aluminum alloy embrittlement and reduced corrosion resistance caused by excessive iron residue during subsequent smelting. Color separation quickly separates light-colored or dark-colored plastic fragments based on material color differences, while air separation separates lighter plastics with lower density through airflow. The combined effect of these two methods can efficiently remove non-ferrous plastic impurities mixed in recycled aluminum, improving impurity removal efficiency and avoiding the potential hazards of melt contamination and porosity defects caused by carbides, hydrogen, etc., generated by the high-temperature decomposition of plastics during smelting. Among these, ferrous impurities in recycled aluminum include metallic foreign objects such as bolts and nails, while color separation is based on material color differences such as the color difference between plastic and the aluminum matrix, and lighter plastics such as polyethylene and polypropylene.

[0034] In one optional embodiment, the recycled aluminum raw materials for cast aluminum alloys include waste materials from engine blocks, gearbox housings, and wheel hubs of automobiles and motorcycles; the recycled aluminum raw materials for wrought aluminum alloys include waste materials from beverage cans, compacted white materials, automobile door panels, engine hoods, aluminum profiles, wires, and pipes. Cast aluminum alloy raw materials are selected from waste materials such as engine blocks, gearbox housings, and wheel hubs from automobiles and motorcycles. Their original purpose is to make castings. They are characterized by high silicon content and high brittleness, which naturally matches the high silicon requirements of cast aluminum alloys. When mechanically crushed, brittle materials can be quickly separated into regular blocks of 50-150mm, reducing the generation of fine powder. Combined with magnetic separation and color sorting, impurities can be efficiently removed and excessive crushing of materials can be avoided, resulting in pre-treated recycled aluminum with uniform composition and low impurity content. On the other hand, wrought aluminum alloy raw materials come from waste materials such as aluminum cans and automobile door panels. The content of elements such as magnesium and manganese in the original composition is suitable for the mechanical performance requirements of wrought aluminum alloys. High-shear shredding can cut them into sheets of less than 100mm, which is easier to separate from lightweight impurities such as plastics, reducing the subsequent impurity removal load.

[0035] S2. Pre-melting and composition analysis of recycled aluminum: The pretreated recycled aluminum raw material is smelted under a protective atmosphere to obtain recycled aluminum melt. Then, the recycled aluminum melt is sampled and its chemical composition is rapidly determined.

[0036] The smelting process takes place in a rotary kiln, specifically by using the rolling motion of the rotary kiln to promote the homogenization of the melt composition and accelerate the smelting process; the protective atmosphere is specifically formed by introducing inert gas into the furnace. The rotary kiln's rolling motion continuously tumbles the material, avoiding the localized temperature differences and compositional segregation issues associated with static melting. This ensures that the recycled aluminum raw material fully contacts the thermal field during melting, shortening melting time and promoting uniform diffusion of components across different regions of the melt. This guarantees the accuracy of subsequent sampling and testing, as the analysis results from a uniformly composed melt more accurately reflect the overall composition, avoiding errors in batching calculations caused by localized component deviations. Simultaneously, the protective atmosphere created by introducing inert gas into the furnace isolates oxygen and moisture from the air, inhibiting the oxidation reaction of active elements in the recycled aluminum and the dissolution of hydrogen produced by moisture decomposition into the melt. This reduces the aluminum oxidation loss rate, decreases aluminum slag production, improves resource utilization, and lowers the load on subsequent slag removal processes. Furthermore, the inert gas atmosphere prevents metallurgical defects caused by the melt absorbing gases (such as hydrogen and oxygen), laying the foundation for pure mixing with molten aluminum during subsequent co-melting and for the final aluminum alloy product.

[0037] In an optional embodiment, the melting temperature is controlled within the range of 700℃-730℃, and the melting time is controlled within the range of 20min-30min. The melting point of aluminum, the main component of recycled aluminum, is approximately 660℃. A temperature of 700℃-730℃ ensures that the recycled aluminum raw material containing alloying elements such as magnesium and silicon is completely melted, avoiding subsequent compositional deviations caused by unmelted particles. Simultaneously, the recycled aluminum does not exceed the severe oxidation or volatilization temperature of most active elements. Combined with inert gas protection, this further inhibits aluminum oxidation and gas absorption. The 20min-30min melting time, in conjunction with the rotary kiln's rolling motion, ensures that the material is heated uniformly in the thermal field. This avoids the localized overmelting or undermelting problems caused by uneven heating in traditional furnaces, without requiring extended melting time and increasing energy consumption, while also ensuring the uniformity of the melt composition.

[0038] S3. Batching Calculation: Based on the composition standard of the target aluminum alloy grade and the composition of the recycled aluminum melt measured in step S2, calculate the ratio of recycled aluminum melt, electrolytic aluminum liquid and necessary alloying additives.

[0039] The ingredient calculation follows these principles: When the target grade is cast aluminum alloy, cast recycled aluminum melt should be given priority as the main raw material; when the target grade is wrought aluminum alloy, wrought recycled aluminum melt should be given priority as the main raw material.

[0040] Cast aluminum alloys typically have specific requirements for the content of elements such as silicon and copper. Cast recycled aluminum, due to its inherently higher silicon content and composition closer to the target range for cast aluminum alloys, is preferentially selected as the main raw material. This reduces the mixing ratio with electrolytic aluminum liquid, preserving the beneficial alloying elements already present in the recycled aluminum while avoiding the waste of adding expensive intermediate alloys after dilution of the electrolytic aluminum liquid. Similarly, wrought aluminum alloys have even stricter controls on elements such as magnesium and manganese. Wrought recycled aluminum, because its original composition has magnesium and manganese content more suitable for the requirements of wrought aluminum alloys, is preferentially used as the main raw material. This reduces the amount of alloy additives needed and minimizes compositional fluctuations caused by mixing recycled aluminum from different sources. This not only maximizes the preservation of the advantageous components of recycled aluminum and reduces the remelting energy consumption of the electrolytic aluminum liquid, but also reduces stirring time and temperature fluctuations during subsequent co-melting by precisely controlling the initial composition of the melt.

[0041] S4. Co-melting: The recycled aluminum melt obtained in step S2 is mixed with the high-temperature electrolytic aluminum liquid from the electrolytic aluminum plant, and alloy additives are added according to the proportion in step S3. After stirring evenly, the aluminum alloy melt after co-melting is obtained.

[0042] In this process, molten recycled aluminum is transported to the alloy production workshop via molten aluminum ladles or insulated pipes, where it is mixed with high-temperature electrolytic aluminum liquid. During the mixing process, a stirring device is activated to ensure uniform melt composition. Transporting the pre-melted recycled aluminum melt via molten aluminum ladles or insulated pipes suppresses heat loss during the transfer process, maintaining the recycled aluminum melt at a suitable temperature close to the pre-melting endpoint. This prevents the formation of cold clumps due to cooling, which would hinder diffusion and fusion with the high-temperature electrolytic aluminum liquid. The stirring device, activated during mixing, uses mechanical force to drive the flow and contact of the two melts, allowing the pre-retained alloying elements in the recycled aluminum to diffuse rapidly and uniformly with the pure aluminum matrix of the electrolytic aluminum liquid, eliminating the compositional inconsistencies that can easily result from static mixing.

[0043] S5. Melt treatment: Refining and online treatment of the aluminum alloy melt after co-melting. Online treatment includes at least degassing, slag removal and grain refinement.

[0044] The refining temperature is 730-750℃, and high-purity argon and refining agent are introduced during the refining process. The refining time is 15-20 minutes. After refining, the mixture needs to be kept at 760-780℃ for 30-40 minutes. During the refining stage, the temperature is limited to 730-750℃ to avoid insufficient reaction of the refining agent at low temperatures and to prevent the high temperatures from aggravating the oxidation and burn-off of aluminum. High-purity argon gas and the refining agent are introduced simultaneously. When the argon gas bubbles rise in the melt, they adsorb hydrogen and inclusions and carry them to the surface. The refining agent reduces the surface tension of the melt through chemical reaction, promotes the decomposition of oxides and combines with hydrogen to form bubbles that are discharged. The refining time of 15-20 minutes is precisely matched with the kinetic process of gas escape and inclusion aggregation, which ensures thorough degassing and slag removal, while avoiding the drop in melt temperature and increase in energy consumption caused by over-refining. The subsequent holding at 760-780℃ for 30-40 minutes uses a thermal field slightly higher than the refining temperature to promote the continued rise of residual small bubbles and further aggregation and sedimentation of tiny inclusions. At the same time, it allows the components of the recycled aluminum and electrolytic aluminum liquid to be fully diffused and uniformly mixed.

[0045] In an optional embodiment, degassing is performed using vacuum degassing, slag removal using filtration, and grain refinement using ultrasonic treatment. Vacuum degassing reduces the pressure of the melt environment and forces dissolved hydrogen to escape using the physical principle of hydrogen partial pressure difference, thus eliminating porosity defects inside the aluminum alloy after casting. Filtration uses multi-stage ceramic filter plates to intercept residual oxides, nitrides, and other minute inclusions in the melt. Compared to natural sedimentation or argon flotation slag removal, it can capture finer impurity particles, reduce the total amount of inclusions in the melt, and improve the density and fatigue strength of the aluminum alloy. Ultrasonic grain refinement uses high-frequency vibration of 20-40kHz to stimulate the cavitation effect of the melt, breaking down the original coarse dendritic structure and promoting uniform nucleation.

[0046] S6. Casting: The aluminum alloy melt processed in step S5 is cast into an aluminum alloy product of a specified shape.

[0047] The implementation principle of this application embodiment is as follows: First, recycled aluminum is classified into cast and wrought aluminum alloys and crushed differently (cast aluminum is crushed to adapt to its brittleness, and wrought aluminum is torn to adapt to its toughness), combined with magnetic separation and color sorting for deep impurity removal; second, recycled aluminum is pre-melted under a protective atmosphere and its composition is rapidly analyzed to pre-lock the composition of recycled aluminum, avoiding repeated adjustments and resource waste caused by fluctuations in the composition of recycled aluminum in traditional processes; based on the target grade requirements, the precise ratio of recycled aluminum melt, electrolytic aluminum liquid and alloy additives is calculated, so that the high purity of electrolytic aluminum liquid and the alloy element advantages of recycled aluminum complement each other, reducing energy consumption and burn-off in the electrolytic aluminum remelting process, while making full use of the resource value of recycled aluminum through synergistic melting; subsequently, the melt is refined, vacuum degassing, filtration slag removal and ultrasonic refining treatment to further purify the melt and improve the uniformity of the structure, effectively improving the mechanical properties and yield of aluminum alloys; finally, the cast product, due to its precise composition and controllable impurities, can be directly used in high value-added scenarios, greatly shortening the long process of electrolysis-ingot casting-remelting-casting, and comprehensively reducing production costs and carbon emissions.

[0048] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid, characterized in that, Including the following steps: S1. Raw material sorting and pretreatment: The recycled aluminum raw materials are classified into cast aluminum alloys and wrought aluminum alloys, and crushed according to their physical property differences. Then, they are sorted to remove ferrous and non-ferrous impurities. S2. Pre-melting and composition analysis of recycled aluminum: The pretreated recycled aluminum raw material is smelted under a protective atmosphere to obtain recycled aluminum melt. Then, the recycled aluminum melt is sampled and its chemical composition is rapidly determined. S3. Batching Calculation: Based on the composition standard of the target aluminum alloy grade and the composition of the recycled aluminum melt measured in step S2, calculate the ratio of recycled aluminum melt, electrolytic aluminum liquid and necessary alloying additives. S4. Co-melting: The recycled aluminum melt obtained in step S2 is mixed with the high-temperature electrolytic aluminum liquid from the electrolytic aluminum plant, and alloy additives are added according to the proportion in step S3. After stirring evenly, the aluminum alloy melt after co-melting is obtained. S5. Melt treatment: Refining and online treatment of the aluminum alloy melt after co-melting, wherein the online treatment includes at least degassing, slag removal and grain refinement; S6. Casting: The aluminum alloy melt processed in step S5 is cast into an aluminum alloy product of a specified shape.

2. The method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid according to claim 1, characterized in that, In step S1, the specific steps of crushing the objects based on their physical properties are as follows: For brittle cast aluminum alloys, mechanical crushing is used to break them into block-shaped materials. For wrought aluminum alloys with good toughness, a high-shear-force mechanical shredding method is used to shear them to obtain sheet or strip materials.

3. The method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid according to claim 2, characterized in that, The sorting includes at least: Iron impurities are removed by magnetic separation; Non-ferrous impurities in plastics are removed by color sorting or air sorting.

4. The method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid according to claim 1, characterized in that, In step S2, the smelting is carried out in a rotary kiln. Specifically, the smelting is achieved by using the rolling motion of the rotary kiln to promote the homogenization of the melt composition and accelerate the smelting process. Specifically, the protective atmosphere is achieved by introducing an inert gas into the furnace to form a protective atmosphere.

5. The method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid according to claim 4, characterized in that, The temperature range for melting is 700℃-730℃, and the time range for melting is 20min-30min.

6. The method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid according to claim 1, characterized in that, In step S3, the ingredient calculation follows the following principles: When the target grade is cast aluminum alloy, cast recycled aluminum melt should be given priority as the main raw material. When the target grade is wrought aluminum alloy, wrought recycled aluminum melt should be given priority as the main raw material.

7. The method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid according to claim 1, characterized in that, In step S4, the recycled aluminum melt is transported to the alloy production workshop through an aluminum ladle or insulated pipe and mixed with the high-temperature electrolytic aluminum liquid. The stirring device is activated during the mixing process with the high-temperature electrolytic aluminum liquid from the electrolytic aluminum plant to ensure uniform melt composition.

8. The method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid according to claim 1, characterized in that, In step S5, the refining temperature is 730-750℃, high-purity argon and refining agent are introduced during the refining process, and the refining time is 15-20 minutes. After refining, the material needs to be kept at 760-780℃ for 30-40 minutes.

9. The method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid according to claim 8, characterized in that, In step S5, the degassing is performed using a vacuum degassing method, the slag removal is performed using a filtration method, and the grain refinement is performed using an ultrasonic treatment method.

10. The method for directly casting aluminum alloys using recycled aluminum and electrolytic aluminum liquid according to claim 1, characterized in that, In step S1, the recycled aluminum raw material for casting aluminum alloy includes waste materials from engine blocks, gearbox housings, and wheel hubs of automobiles and motorcycles. The recycled aluminum raw materials for deformed aluminum alloys include waste materials from beverage cans, compacted white materials, car door panels, engine hoods, aluminum profiles, wires, and pipes.

Images