A method for preparing recycled aluminum alloy from waste aluminum alloy

Abstract

This invention discloses a method for preparing recycled aluminum alloys from waste aluminum alloys, relating to the field of recycled aluminum alloy technology. The invention includes: classifying, cleaning, magnetically separating, and removing non-waste aluminum alloy impurities from the recycled waste aluminum alloy; melting the waste aluminum alloy into molten aluminum in a coreless medium-frequency induction furnace, followed by argon gas degassing; adding refining and refining agents to the molten aluminum, stirring under a magnetic field and maintaining the temperature for a period of time, then skimming slag from the surface of the molten aluminum and filtering; adding an intermediate alloy to the purified molten aluminum to adjust its composition, blowing in argon gas, and stirring under a magnetic field to ensure uniform alloy composition; and after stirring under a magnetic field for a period of time, obtaining the recycled aluminum alloy through semi-solid metal flow forming. The recycled aluminum alloy prepared by this invention has a low hydrogen content, a more complete primary phase α-Al morphology, a significantly reduced size, and significantly improved mechanical properties, strength, and plasticity. Simultaneously, the reuse of waste aluminum alloys helps reduce production costs, saves resources, and is suitable for widespread application.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of recycled aluminum alloy, and particularly relates to a method for preparing recycled aluminum alloy from waste aluminum alloy. BACKGROUND

[0002] With the acceleration of global industrialization and urbanization, aluminum alloy, as a lightweight and high-strength material, has been widely used in aerospace, automobile manufacturing, construction and other fields. However, with the mass production and use of aluminum alloy products, the amount of waste aluminum alloy is also increasing. The random disposal of waste aluminum alloy not only wastes valuable resources, but also causes serious environmental pollution. Therefore, the recycling of waste aluminum alloy is of great significance for resource conservation and environmental pollution reduction.

[0003] The recycling of aluminum alloy mainly involves recycling waste aluminum alloy, and then preparing new aluminum alloy materials through a series of processing technologies. This method not only effectively reduces the production of new aluminum, reduces energy consumption and environmental pollution, but also provides recycled aluminum alloy materials with comparable or better performance than primary aluminum. In the recycling process of waste aluminum alloy, the key processing steps include collection, classification, crushing, cleaning, melting and refining of waste aluminum alloy. Among them, the melting and refining process is the key to preparing high-quality recycled aluminum alloy. However, the existing recycling method of waste aluminum alloy has some challenges, such as high impurity content, uneven alloy composition, and difficulty in removing gas and inclusions, which will affect the performance and stability of recycled aluminum alloy.

[0004] Therefore, developing a new method that can effectively remove impurities from waste aluminum alloy, optimize alloy composition, and improve the performance of recycled aluminum alloy is of great significance for promoting the recycling of waste aluminum alloy. This method should be able to achieve efficient recycling and reuse of waste aluminum alloy, and prepare recycled aluminum alloy materials with high purity and high performance to meet the demand of different industries for aluminum alloy materials. SUMMARY

[0005] The purpose of the present application is to provide a method for preparing recycled aluminum alloy from waste aluminum alloy, which solves the problem of low performance and stability of existing recycled aluminum alloy by using a process route of screening, melting, melt purification, composition adjustment, pouring and semi-solid rheological forming to prepare recycled aluminum alloy with excellent comprehensive performance.

[0006] To solve the above technical problems, the present application is realized by the following technical scheme:

[0007] The present application is a method for preparing recycled aluminum alloy from waste aluminum alloy, which comprises:

[0008] (1) Screening: The recycled waste aluminum alloy is used as raw material, and its chemical composition is detected, and classified, cleaned, magnetically selected and non-waste aluminum alloy impurities are removed; before adding into the furnace, the surface of the recycled waste aluminum is first pickled to remove the surface oxide layer, and is broken into debris;

[0009] (2) Melting: The waste aluminum alloy treated in step (1) is placed in a coreless medium frequency induction furnace to melt into aluminum liquid, magnetically stirred and kept for a period of time, and then argon is introduced for degassing;

[0010] (3) Melt purification: After the aluminum liquid treated in step (2), first add a refining agent to it, and then add a refiner, the whole melt purification process is introduced into nitrogen, magnetically stirred and kept for a period of time, then the surface of the aluminum liquid is scraped, and filtered;

[0011] (4) Component adjustment: After the aluminum liquid treated in step (3), the composition of the aluminum liquid is detected by using a photoelectric direct-reading spectrometer, then an appropriate amount of intermediate alloy is added for composition adjustment, argon is blown in, and the alloy composition is uniformly stirred by magnetic field, and then the composition of the aluminum liquid is detected by using a photoelectric direct-reading spectrometer, and intermediate alloy is added in real time until the mass percentage of each element of the aluminum liquid reaches the target aluminum alloy composition;

[0012] (5) Pouring and semi-solid rheological forming: The aluminum liquid treated in step (4) is magnetically stirred for a period of time, and is poured into a preheated mold, and the recycled aluminum alloy is obtained by semi-solid metal rheological forming.

[0013] As a preferred technical solution, the raw material of step (1) is waste photovoltaic aluminum frame, waste door and window aluminum alloy and waste mobile phone aluminum alloy shell.

[0014] As a preferred technical solution, the pickling of step (1) uses a mixed solution of 43% phosphoric acid (5 mol / L), 2% nitric acid (8 mol / L) and 55% acetic acid (10 mol / L) to remove the oxide layer.

[0015] As a preferred technical solution, the melting temperature of step (2) is 730-780℃.

[0016] As a preferred technical solution, the refiner of step (3) is Al-Ti-C intermediate alloy, and the holding time is 15-30 min.

[0017] As a preferred technical solution, the intermediate alloys in step (4) are Al-10Si, Al-30Mg, Al-20Mn, Al-5Fe, and Al-40Cu, respectively. The mass percentages of each element in the target aluminum alloy are as follows: Si: 8.0%~12%, Mg: 0.1%~0.5%, Mn: 0.1%~0.5%, Fe: 0.5%~0.8%, Cu: 0.1%~0.5%, other individual items 0.1%~1.5%, and the balance is Al.

[0018] As a preferred technical solution, the semi-solid metal rheoforming in step (5) has a magnetic stirring rate of 500r / min to 1000r / min and a mold preheating temperature of 180℃ to 240℃.

[0019] As a preferred technical solution, the recycled aluminum alloy has a tensile strength ≥300MPa, a hydrogen content ≤0.1mL / 100gAl, and an elongation at break ≥18%.

[0020] The present invention has the following beneficial effects:

[0021] a. This invention achieves effective utilization of resources by recycling waste aluminum alloy materials such as waste photovoltaic aluminum frames, waste aluminum alloy doors and windows, and waste aluminum alloy mobile phone casings, thereby reducing the demand for primary aluminum production and thus reducing energy consumption and environmental pollution.

[0022] b. Adding a magnetic field during the smelting process helps accelerate the diffusion and homogenization of alloying elements, reduces segregation, and improves the microstructure uniformity and performance stability of recycled aluminum alloys. Introducing argon gas for degassing effectively removes dissolved gases from the molten aluminum, reducing porosity and inclusions in the recycled aluminum alloy, thus improving its purity and mechanical properties.

[0023] c. In the melt purification step, by adding refining agents and finesing agents, and combining nitrogen purification and magnetic field stirring technology, impurities and gases in the aluminum melt are effectively removed, the grain structure is refined, and the purity and uniformity of the recycled aluminum alloy are significantly improved, thereby enhancing its mechanical properties and corrosion resistance. At the same time, environmental pollution is reduced, and green and efficient aluminum alloy recycling and reuse is achieved.

[0024] d. During the composition adjustment stage, the mass percentage of elements in the molten aluminum reached the predetermined optimization range, significantly improving the comprehensive performance of the recycled aluminum alloy, such as strength and corrosion resistance, and providing a reliable raw material basis for manufacturing high-performance aluminum alloy products.

[0025] e. Semi-solid rheoforming technology significantly improves the mechanical properties and forming quality of recycled aluminum alloys by optimizing the solid-liquid two-phase structure of the alloy, while reducing defects and energy consumption, thus broadening its application prospects. Magnetic stirring effectively improves the uniformity of alloy composition, while appropriate preheating temperature ensures smooth contact between the mold and the molten aluminum and the forming quality.

[0026] Of course, any product implementing this invention does not necessarily need to achieve all of the advantages described above at the same time. Attached Figure Description

[0027] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the 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.

[0028] Figure 1 This is a flowchart of a method for preparing recycled aluminum alloy from waste aluminum alloy according to the present invention. Detailed Implementation

[0029] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] To make the purpose, technical solution, and advantages of this application clearer, the following description is provided in conjunction with the appendix. Figure 1 The present application will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the application.

[0032] Example 1

[0033] A method for preparing recycled aluminum alloy from waste aluminum alloy includes the following steps:

[0034] (1) Screening: The recycled waste photovoltaic aluminum frames, waste door and window aluminum alloys and waste mobile phone aluminum alloy shells are used as raw materials. Their chemical composition is tested, and they are classified, cleaned, magnetically separated and non-waste aluminum alloy impurities are removed. Before being added to the furnace, the surface oxide layer of the recycled waste aluminum is removed by a mixed solution of 43% phosphoric acid (5mol / L), 2% nitric acid (8mol / L) and 55% acetic acid (10mol / L). The pickling time is 5-10 minutes, and the aluminum is crushed into fragments.

[0035] (2) Melting: The waste aluminum alloy processed in step (1) is placed in a coreless medium frequency induction furnace to melt into aluminum liquid. The melting temperature is 730℃~780℃, the magnetic field strength is 12T, the holding time is 30min, and then argon gas is introduced for degassing.

[0036] (3) Melt purification: The aluminum liquid treated in step (2) is first added with a refining agent, which is hydrogen gas, at a rate of 2 ml / min. Then a refining agent is added, which is an Al-Ti-C master alloy. It is rolled and deformed with a deformation amount of 30% and the grain size reaches the submicron level. Nitrogen gas is introduced throughout the entire melt purification process. The magnetic field strength of the stirring is 12T. The temperature is held for 15 min. The slag on the surface of the aluminum liquid is removed and filtered.

[0037] (4) Composition adjustment: The aluminum liquid treated in step (3) is tested for composition using a photoelectric direct-reading spectrometer. Then, appropriate amounts of intermediate alloys Al-10Si, Al-30Mg, Al-20Mn, Al-5Fe, and Al-40Cu are added for composition adjustment. Argon gas is blown in and the mixture is stirred in a magnetic field to make the alloy composition uniform. After standing for a period of time, the aluminum liquid composition is tested again using a photoelectric direct-reading spectrometer. Intermediate alloys are added in real time until the mass percentage of each element in the aluminum liquid reaches the target aluminum alloy composition: Si: 8.0%~12%, Mg: 0.1%~0.5%, Mn: 0.1%~0.5%, Fe: 0.5%~0.8%, Cu: 0.1%~0.5%, other single items 0.1%~1.5%, and the balance is Al.

[0038] (5) Casting and semi-solid rheoforming: The aluminum liquid treated in step (4) is magnetically stirred and kept at a temperature for a period of time. The magnetic stirring rate is 800 r / min. It is then poured into a preheated mold at a preheating temperature of 180℃~240℃. Recycled aluminum alloy is obtained through semi-solid metal rheoforming.

[0039] The recycled aluminum alloy prepared in this embodiment has fine grains and a uniform structure, a hydrogen content of 0.09 mL / 100 g Al, a tensile strength of 320 MPa, and an elongation at break of 22%.

[0040] Example 2

[0041] A method for preparing recycled aluminum alloy from waste aluminum alloy includes the following steps:

[0042] (1) Screening: The recycled waste photovoltaic aluminum frames, waste door and window aluminum alloys and waste mobile phone aluminum alloy shells are used as raw materials. Their chemical composition is tested, and they are classified, cleaned, magnetically separated and non-waste aluminum alloy impurities are removed. Before being added to the furnace, the surface oxide layer of the recycled waste aluminum is removed by a mixed solution of 43% phosphoric acid (5mol / L), 2% nitric acid (8mol / L) and 55% acetic acid (10mol / L). The pickling time is 5-10 minutes, and the aluminum is crushed into fragments.

[0043] (2) Melting: The waste aluminum alloy processed in step (1) is placed in a coreless medium frequency induction furnace to melt into aluminum liquid. The melting temperature is 730℃~780℃, the magnetic field strength is 12T, the holding time is 30min, and then argon gas is introduced for degassing.

[0044] (3) Melt purification: The aluminum liquid treated in step (2) is first added with a refining agent, which is hydrogen gas, at a rate of 4 ml / min. Then a refining agent is added, which is an Al-Ti-C master alloy. It is rolled and deformed with a deformation amount of 50%, and the grain size reaches the submicron or even nanoscale. Nitrogen gas is introduced throughout the entire melt purification process. The magnetic field strength of the stirring is 12T. The temperature is held for 15 min. The slag on the surface of the aluminum liquid is removed and filtered.

[0045] (4) Composition adjustment: The aluminum liquid treated in step (3) is tested for composition using a photoelectric direct-reading spectrometer. Then, appropriate amounts of intermediate alloys Al-10Si, Al-30Mg, Al-20Mn, Al-5Fe, and Al-40Cu are added for composition adjustment. Argon gas is blown in and the mixture is stirred in a magnetic field to make the alloy composition uniform. After standing for a period of time, the aluminum liquid composition is tested again using a photoelectric direct-reading spectrometer. Intermediate alloys are added in real time until the mass percentage of each element in the aluminum liquid reaches the target aluminum alloy composition: Si: 8.0%~12%, Mg: 0.1%~0.5%, Mn: 0.1%~0.5%, Fe: 0.5%~0.8%, Cu: 0.1%~0.5%, other single items 0.1%~1.5%, and the balance is Al.

[0046] (5) Casting and semi-solid rheoforming: The aluminum liquid treated in step (4) is magnetically stirred and kept at a temperature for a period of time. The magnetic stirring rate is 800 r / min. It is then poured into a preheated mold at a preheating temperature of 180℃~240℃. Recycled aluminum alloy is obtained through semi-solid metal rheoforming.

[0047] The recycled aluminum alloy prepared in this embodiment has fine grains and a uniform structure, a hydrogen content of 0.075 mL / 100 g Al, a tensile strength of 350 MPa, and an elongation at break of 25%.

[0048] Example 3

[0049] A method for preparing recycled aluminum alloy from waste aluminum alloy includes the following steps:

[0050] (1) Screening: The recycled waste photovoltaic aluminum frames, waste door and window aluminum alloys and waste mobile phone aluminum alloy shells are used as raw materials. Their chemical composition is tested, and they are classified, cleaned, magnetically separated and non-waste aluminum alloy impurities are removed. Before being added to the furnace, the surface oxide layer of the recycled waste aluminum is removed by a mixed solution of 43% phosphoric acid (5mol / L), 2% nitric acid (8mol / L) and 55% acetic acid (10mol / L). The pickling time is 5-10 minutes, and the aluminum is crushed into fragments.

[0051] (2) Melting: The waste aluminum alloy processed in step (1) is placed in a coreless medium frequency induction furnace to melt into aluminum liquid. The melting temperature is 730℃~780℃, the magnetic field strength is 12T, the holding time is 30min, and then argon gas is introduced for degassing.

[0052] (3) Melt purification: The aluminum liquid treated in step (2) is first added with a refining agent, which is hydrogen gas, at a rate of 6 ml / min. Then a refining agent is added, which is an Al-Ti-C master alloy. It is rolled and deformed with a deformation amount of 70% and the grain size reaches the nanoscale. Nitrogen gas is introduced throughout the entire melt purification process. The magnetic field strength of the stirring is 12T. The temperature is held for 15 min. The slag on the surface of the aluminum liquid is removed and filtered.

[0053] (4) Composition adjustment: The aluminum liquid treated in step (3) is tested for composition using a photoelectric direct-reading spectrometer. Then, appropriate amounts of intermediate alloys Al-10Si, Al-30Mg, Al-20Mn, Al-5Fe, and Al-40Cu are added for composition adjustment. Argon gas is blown in and the mixture is stirred in a magnetic field to make the alloy composition uniform. After standing for a period of time, the aluminum liquid composition is tested again using a photoelectric direct-reading spectrometer. Intermediate alloys are added in real time until the mass percentage of each element in the aluminum liquid reaches the target aluminum alloy composition: Si: 8.0%~12%, Mg: 0.1%~0.5%, Mn: 0.1%~0.5%, Fe: 0.5%~0.8%, Cu: 0.1%~0.5%, other single items 0.1%~1.5%, and the balance is Al.

[0054] (5) Casting and semi-solid rheoforming: The aluminum liquid treated in step (4) is magnetically stirred and kept at a temperature for a period of time. The magnetic stirring rate is 800 r / min. It is then poured into a preheated mold at a preheating temperature of 180℃~240℃. Recycled aluminum alloy is obtained through semi-solid metal rheoforming.

[0055] The recycled aluminum alloy prepared in this embodiment has fine grains and a uniform microstructure, a hydrogen content of 0.085 mL / 100 g Al, a tensile strength of 320 MPa, and an elongation at break of 21%.

[0056] Example 4

[0057] A method for preparing recycled aluminum alloy from waste aluminum alloy includes the following steps:

[0058] (1) Screening: Same as in Example 2;

[0059] (2) Smelting: Same as in Example 2;

[0060] (3) Melt purification: Same as in Example 2;

[0061] (4) Ingredient adjustment: Same as in Example 2;

[0062] (5) Casting and semi-solid rheoforming: The aluminum liquid treated in step (4) is magnetically stirred and kept at a temperature for a period of time. The magnetic stirring rate is 500 r / min. It is then poured into a preheated mold at a preheating temperature of 180℃~240℃. Recycled aluminum alloy is obtained through semi-solid metal rheoforming.

[0063] The recycled aluminum alloy prepared in this embodiment has fine grains and a uniform structure, a hydrogen content of 0.1 mL / 100 g Al, a tensile strength of 310 MPa, and an elongation at break of 23%.

[0064] Example 5

[0065] A method for preparing recycled aluminum alloy from waste aluminum alloy includes the following steps:

[0066] (1) Screening: Same as in Example 2;

[0067] (2) Smelting: Same as in Example 2;

[0068] (3) Melt purification: Same as in Example 2;

[0069] (4) Ingredient adjustment: Same as in Example 2;

[0070] (5) Casting and semi-solid rheoforming: The aluminum liquid treated in step (4) is magnetically stirred and kept at a temperature for a period of time. The magnetic stirring rate is 1000 r / min. It is then poured into a preheated mold at a preheating temperature of 180℃~240℃. Recycled aluminum alloy is obtained through semi-solid metal rheoforming.

[0071] The recycled aluminum alloy prepared in this embodiment has fine grains and a uniform structure, a hydrogen content of 0.08 mL / 100 g Al, a tensile strength of 330 MPa, and an elongation at break of 23%.

[0072] Comparative Example 1

[0073] (1) Screening: The recycled waste photovoltaic aluminum frames, waste door and window aluminum alloys and waste mobile phone aluminum alloy shells are used as raw materials. Their chemical composition is tested, and they are classified, cleaned, magnetically separated and non-waste aluminum alloy impurities are removed. Before being added to the furnace, the surface oxide layer of the recycled waste aluminum is removed by a mixed solution of 43% phosphoric acid (5mol / L), 2% nitric acid (8mol / L) and 55% acetic acid (10mol / L). The pickling time is 5-10 minutes, and the aluminum is crushed into fragments.

[0074] (2) Melting: The waste aluminum alloy processed in step (1) is placed in a coreless medium frequency induction furnace to melt into aluminum liquid. The melting temperature is 730℃~780℃, the magnetic field strength is 10T, the holding time is 30min, and then argon gas is introduced for degassing.

[0075] (3) Melt purification: Add a refining agent to the aluminum liquid after the treatment in step (2). The refining agent is hydrogen gas, the rate is 4 ml / min, the magnetic field strength of the stirring is 12T, the temperature is held for 15 min, the slag on the surface of the aluminum liquid is removed, and the liquid is filtered.

[0076] (4) Composition adjustment: The aluminum liquid treated in step (3) is tested for composition using a photoelectric direct-reading spectrometer. Then, appropriate amounts of intermediate alloys Al-10Si, Al-30Mg, Al-20Mn, Al-5Fe, and Al-40Cu are added for composition adjustment. Argon gas is blown in and the mixture is stirred in a magnetic field to make the alloy composition uniform. After standing for a period of time, the aluminum liquid composition is tested again using a photoelectric direct-reading spectrometer. Intermediate alloys are added in real time until the mass percentage of each element in the aluminum liquid reaches the target aluminum alloy composition: Si: 8.0%~12%, Mg: 0.1%~0.5%, Mn: 0.1%~0.5%, Fe: 0.5%~0.8%, Cu: 0.1%~0.5%, other single items 0.1%~1.5%, and the balance is Al.

[0077] (5) Casting and semi-solid rheoforming: The aluminum liquid treated in step (4) is magnetically stirred and kept at a temperature for a period of time. The magnetic stirring rate is 500 r / min. It is then poured into a preheated mold at a preheating temperature of 180℃~240℃. Recycled aluminum alloy is obtained through semi-solid metal rheoforming.

[0078] The recycled aluminum alloy prepared in this embodiment has fine grains and a uniform structure, a hydrogen content of 1.3 mL / 100 g Al, a tensile strength of 290 MPa, and an elongation at break of 24%.

[0079] Comparative Example 2

[0080] (1) Screening: The recycled waste photovoltaic aluminum frames, waste door and window aluminum alloys and waste mobile phone aluminum alloy shells are used as raw materials. Their chemical composition is tested, and they are classified, cleaned, magnetically separated and non-waste aluminum alloy impurities are removed. Before being added to the furnace, the surface oxide layer of the recycled waste aluminum is removed by a mixed solution of 43% phosphoric acid (5mol / L), 2% nitric acid (8mol / L) and 55% acetic acid (10mol / L). The pickling time is 5-10 minutes, and the aluminum is crushed into fragments.

[0081] (2) Melting: The waste aluminum alloy processed in step (1) is placed in a coreless medium frequency induction furnace to melt into aluminum liquid. The melting temperature is 730℃~780℃, the magnetic field strength is 10T, the holding time is 30min, and then argon gas is introduced for degassing.

[0082] (3) Melt purification: After the aluminum liquid is treated in step (2), a refining agent is first added to it. The refining agent is hydrogen gas at a rate of 4 ml / min. Then a refining agent is added. The refining agent is Al-Ti-C master alloy, which is rolled and deformed with a deformation amount of 50%. The grain size reaches the submicron or even nanoscale. Nitrogen gas is introduced throughout the entire melt purification process. The magnetic field strength of the stirring is 12T. The temperature is held for 15 min. The slag on the surface of the aluminum liquid is removed and filtered.

[0083] (4) Composition adjustment: The aluminum liquid treated in step (3) is tested for composition using a photoelectric direct-reading spectrometer. Then, appropriate amounts of intermediate alloys Al-10Si, Al-30Mg, Al-20Mn, Al-5Fe, and Al-40Cu are added for composition adjustment. Argon gas is blown in and the mixture is stirred in a magnetic field to make the alloy composition uniform. After standing for a period of time, the aluminum liquid composition is tested again using a photoelectric direct-reading spectrometer. Intermediate alloys are added in real time until the mass percentage of each element in the aluminum liquid reaches the target aluminum alloy composition: Si: 8.0%~12%, Mg: 0.1%~0.5%, Mn: 0.1%~0.5%, Fe: 0.5%~0.8%, Cu: 0.1%~0.5%, other single items 0.1%~1.5%, and the balance is Al.

[0084] (5) Casting: The aluminum liquid treated in step (4) is cast into a preheated mold to obtain recycled aluminum alloy. The preheating temperature is 180℃~240℃.

[0085] The recycled aluminum alloy prepared in this embodiment has fine grains and a uniform microstructure, a hydrogen content of 1.1 mL / 100 g Al, a tensile strength of 305 MPa, and an elongation at break of 21%.

[0086] Comparative Example 3

[0087] (1) Screening: The recycled waste photovoltaic aluminum frames, waste door and window aluminum alloys and waste mobile phone aluminum alloy shells are used as raw materials. Their chemical composition is tested, and they are classified, cleaned, magnetically separated and non-waste aluminum alloy impurities are removed. Before being added to the furnace, the surface oxide layer of the recycled waste aluminum is removed by a mixed solution of 43% phosphoric acid (5mol / L), 2% nitric acid (8mol / L) and 55% acetic acid (10mol / L). The pickling time is 5-10 minutes, and the aluminum is crushed into fragments.

[0088] (2) Melting: The waste aluminum alloy processed in step (1) is placed in a coreless medium frequency induction furnace to melt into aluminum liquid. The melting temperature is 730℃~780℃ and the holding time is 30min. Then argon gas is introduced for degassing.

[0089] (3) Melt purification: After the aluminum liquid is treated in step (2), a refining agent is first added to it. The refining agent is hydrogen gas at a rate of 4 ml / min. Then a refining agent is added. The refining agent is an Al-Ti-C master alloy. It is rolled and deformed with a deformation amount of 50%. The grain size reaches the submicron or even nanoscale. Nitrogen gas is introduced throughout the entire melt purification process. The temperature is maintained for 15 min. The slag on the surface of the aluminum liquid is removed and filtered.

[0090] (4) Composition adjustment: The aluminum liquid treated in step (3) is tested for composition using a photoelectric direct-reading spectrometer. Then, appropriate amounts of intermediate alloys Al-10Si, Al-30Mg, Al-20Mn, Al-5Fe, and Al-40Cu are added for composition adjustment. Argon gas is blown in and the mixture is stirred to make the alloy composition uniform. After standing for a period of time, the aluminum liquid composition is tested again using a photoelectric direct-reading spectrometer. Intermediate alloys are added in real time until the mass percentage of each element in the aluminum liquid reaches the target aluminum alloy composition: Si: 8.0%~12%, Mg: 0.1%~0.5%, Mn: 0.1%~0.5%, Fe: 0.5%~0.8%, Cu: 0.1%~0.5%, other single items 0.1%~1.5%, and the balance is Al.

[0091] (5) Casting and semi-solid rheoforming: The aluminum liquid treated in step (4) is stirred and kept at a temperature for a period of time. The stirring rate is 500 r / min, and it is poured into a preheated mold. The preheating temperature is 180℃~240℃. Recycled aluminum alloy is obtained through semi-solid metal rheoforming.

[0092] The recycled aluminum alloy prepared in this embodiment has fine grains and a uniform microstructure, a hydrogen content of 1.2 mL / 100 g Al, a tensile strength of 315 MPa, and an elongation at break of 22%.

[0093] It is worth noting that the various units included in the above system embodiments are only divided according to functional logic, but are not limited to the above division, as long as the corresponding functions can be achieved; in addition, the specific names of each functional unit are only for easy differentiation and are not used to limit the scope of protection of the present invention.

[0094] Furthermore, those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware, and the corresponding program can be stored in a computer-readable storage medium.

[0095] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for producing a secondary aluminum alloy from scrap aluminum alloy, characterized by, It comprises the following steps: (1) screening: the recycled waste aluminum alloy is used as raw material, and its chemical composition is detected, and classified, cleaned, magnetically selected and non-waste aluminum alloy impurities are removed; before being added into the furnace, the surface of the recycled waste aluminum is pickled to remove the surface oxide layer, and is broken into debris; (2) smelting: the waste aluminum alloy treated in step (1) is placed in a coreless medium-frequency induction furnace to be melted into aluminum liquid, is magnetically stirred and is kept for a period of time, and then argon is introduced for degassing; (3) melt purification: the aluminum liquid treated in step (2) is first added with a refining agent, and then is added with a refiner, the whole melt purification process is introduced with nitrogen, is magnetically stirred and is kept for a period of time, the surface of the aluminum liquid is raked, and is filtered; (4) composition adjustment: the aluminum liquid treated in step (3) is detected for its composition by using a photoelectric direct-reading spectrometer, then appropriate intermediate alloy is added for composition adjustment, argon is blown in, and the alloy composition is uniformly stirred in a magnetic field, is kept for a period of time, the aluminum liquid composition is detected by using a photoelectric direct-reading spectrometer, intermediate alloy is added in real time until the mass percentage of each element of the aluminum liquid reaches the target aluminum alloy composition; (5) pouring and semi-solid rheological forming: the aluminum liquid treated in step (4) is magnetically stirred for a period of time, and is poured into a preheated mold, and then semi-solid metal rheological forming is carried out to obtain recycled aluminum alloy.

2. The method of claim 1, wherein the method further comprises: The raw material of step (1) is waste photovoltaic aluminum frame, waste aluminum alloy of doors and windows and waste aluminum alloy shell of mobile phone. ​ 3. The method of claim 1, wherein the method further comprises: The pickling of step (1) uses a mixed solution of 43% phosphoric acid, 2% nitric acid and 55% acetic acid to remove the oxide layer. ​ 4. The method of claim 1, wherein the method further comprises: The smelting temperature of step (2) is 730-780℃. ​ 5. The method of claim 1, wherein the method further comprises: The refiner of step (3) is Al-Ti-C intermediate alloy, and the holding time is 15-30 min. ​ 6. The method of claim 1, wherein the method further comprises the step of: The intermediate alloy of step (4) is Al-10Si, Al-30Mg, Al-20Mn, Al-5Fe and Al-40Cu, and the mass percentage of each element of the target aluminum alloy is as follows: Si: 8.0%-12%, Mg: 0.1%-0.5%, Mn: 0.1%-0.5%, Fe: 0.5%-0.8%, Cu: 0.1%-0.5%, and other single element: 0.1%-1.5%, and the balance is Al. ​ 7. The method of claim 1, wherein the method further comprises: The magnetic field stirring rate of the semi-solid metal rheological forming of step (5) is 500-1000 r / min, and the preheating temperature of the mold is 180-240℃. ​ 8. A recycled aluminium alloy produced according to the method of any one of claims 1 to 7, characterised in that, The tensile strength of the recycled aluminum alloy is ≥300 MPa, the hydrogen content is ≤0.1 mL / 100 g Al, and the elongation at break is ≥18%.

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