A method for recycling am series magnesium alloy scrap

Abstract

This invention belongs to the field of metal resource recycling technology, specifically relating to a method for recycling AM series magnesium alloy waste. The method for recycling AM series magnesium alloy waste provided by this invention includes the following steps: vacuum pressure distillation of the AM series magnesium alloy waste to obtain metal vapor and Al-Mn alloy melt; sequentially subjecting the metal vapor to vacuum isothermal condensation and vacuum quenching condensation to obtain metallic magnesium. This invention uses vacuum pressure distillation of the AM series magnesium alloy waste to separate magnesium from non-volatile metallic impurities and non-metallic impurities (mainly oxides, such as MgO) such as aluminum, manganese, copper, iron, and nickel during the volatilization process; the metallic magnesium is condensed in the isothermal condensation section, while the volatile metallic impurities doped in the metal vapor are condensed in the quenching section. This invention removes volatile metallic impurities during the directional condensation process, further improving the purity of the metallic magnesium and obtaining high-value-added 4N high-purity magnesium and Al-Mn master alloys.

Description

Technical Field

[0001] This invention belongs to the field of metal resource recycling technology, specifically relating to a method for recycling AM series magnesium alloy waste. Background Technology

[0002] With the rapid development of the automotive industry, magnesium alloys are widely used as lightweight materials due to their ability to significantly reduce vehicle weight. AM (Mg-Al-Mn) series magnesium alloys are among the earliest developed and maturely applied ternary magnesium alloys. AM50 and AM60, as typical representatives of the AM series, possess high strength and excellent casting performance, as well as outstanding ductility and energy absorption characteristics. Their high strength and excellent casting performance make them widely used in automotive seat frames, instrument panels, brackets, steering wheels, etc. As typical die-cast magnesium alloys, the AM series generates approximately 50-70% of the feed material during the die-casting process, resulting in various forms of scrap. Even qualified castings require machining to the required dimensions, producing heavily oxidized cutting chips, which also form scrap. This scrap has a large specific surface area, contains a large number of non-metallic inclusions, and is highly flammable, posing significant safety hazards and requiring strict centralized management. Traditional refining methods are difficult to recover this type of scrap. Vacuum methods can effectively recover this scrap and obtain metallic magnesium, making it a better process for recycling this type of magnesium alloy scrap. For example, the invention patent with publication number CN 103509950A discloses a recycling equipment and process for waste magnesium alloys, which degreases AM series magnesium alloy waste at 500-600℃ for 1-1.5h and then vacuum recovers it at 600-900℃ for 7-9h to obtain recycled magnesium with a purity greater than 99.8%.

[0003] The existing vacuum method for recovering magnesium from AM series magnesium alloy scrap has low purity and poor economic efficiency. Summary of the Invention

[0004] In view of this, the present invention provides a method for recycling AM series magnesium alloy waste. The recycling method provided by the present invention can be used to recycle AM ​​series magnesium alloy waste, and the obtained metallic magnesium has a high purity of up to 4N, thereby improving the economic efficiency of recycling metallic magnesium.

[0005] To address the aforementioned technical problems, this invention provides a method for recycling AM series magnesium alloy waste, comprising the following steps:

[0006] AM series magnesium alloy waste was subjected to vacuum pressure distillation to obtain metal vapor and Al-Mn alloy melt, respectively.

[0007] The metal vapor was subjected to vacuum isothermal condensation and vacuum quenching condensation in sequence to obtain metallic magnesium.

[0008] Preferably, the temperature of the vacuum pressure distillation is 650–850°C, the vacuum degree of the vacuum pressure distillation is 300–1000 Pa, and the time of the vacuum pressure distillation is 30–60 min.

[0009] Preferably, the temperature of the vacuum isothermal condensation is less than 650°C and greater than or equal to 500°C, and the vacuum degree of the vacuum isothermal condensation is 300 to 1000 Pa.

[0010] Preferably, the vacuum degree of the vacuum quenching condensation is 300-1000 Pa.

[0011] Preferably, the condensation temperature gradient of the vacuum quenching condensation is 13–28 °C / cm.

[0012] Preferably, the vacuum pressure distillation, vacuum constant temperature condensation, and vacuum quench condensation are performed in a vacuum recovery device, which includes a cavity; the cavity includes a heating section 1, a constant temperature condensation section 2, and a quench condensation section 3 arranged sequentially; the outer surfaces of the heating section 1 and the constant temperature condensation section 2 are provided with heating elements 9, and the surface of the heating elements 9 is provided with a heat insulation layer 4; a filter screen 5 is provided between the heating section 1 and the constant temperature condensation section 2.

[0013] The vacuum recovery equipment also includes a vacuum control system and a temperature control system 6. The vacuum control system includes an inert gas container 7 and a vacuum pump 8.

[0014] Preferably, the filter screen 5 has a pore size of 30 to 100 mesh.

[0015] Preferably, the AM series magnesium alloys include one or more of AM50, AM60, AM20, and AM100.

[0016] Preferably, the AM series magnesium alloy scrap includes scraps generated during the die casting and processing of AM series magnesium alloys, and the shape of the scraps includes blocks, flakes, strips or granules.

[0017] This invention provides a method for recycling AM series magnesium alloy waste, comprising the following steps: vacuum pressure distillation of the AM series magnesium alloy waste to obtain metal vapor and Al-Mn alloy melt; sequentially subjecting the metal vapor to vacuum isothermal condensation and vacuum quenching condensation to obtain metallic magnesium. This invention uses vacuum pressure distillation of the AM series magnesium alloy waste to separate magnesium from non-volatile metal impurities such as aluminum, manganese, copper, iron, and nickel during the volatilization process; metallic magnesium is condensed in the isothermal condensation section, while volatile metal impurities (zinc, lead, potassium, sodium) mixed in the metal vapor are condensed in the quenching condensation section. This invention employs isothermal condensation and quenching condensation to achieve directional condensation of metallic magnesium and volatile metal impurities, further improving the purity of metallic magnesium and obtaining high-value-added 4N high-purity magnesium and Al-Mn master alloy. The recycling method provided by this invention has the advantages of a short process flow, no chemical reagent consumption, no wastewater or waste gas generation, green and efficient operation, and the ability to obtain 4N high-purity magnesium and Al-Mn master alloy in one step, realizing the recycling of valuable metals in magnesium alloy waste. Attached Figure Description

[0018] Figure 1 The diagram shows the structure of the equipment used to process AM series magnesium alloy waste in this embodiment. In the diagram, 1 is the heating section, 2 is the constant temperature condensation section, 3 is the rapid cooling condensation section, 4 is the insulation layer, 5 is the filter screen, 6 is the temperature control system, 7 is the inert gas container, 8 is the vacuum pump, and 9 is the heating element. Detailed Implementation

[0019] This invention provides a method for recycling AM series magnesium alloy scrap, comprising the following steps:

[0020] AM series magnesium alloy waste was subjected to vacuum pressure distillation to obtain metal vapor and Al-Mn alloy melt, respectively.

[0021] The metal vapor was subjected to vacuum isothermal condensation and vacuum quenching condensation in sequence to obtain metallic magnesium.

[0022] AM series magnesium alloy scrap is subjected to vacuum pressure distillation to obtain metal vapor and Al-Mn alloy melt, respectively. In this invention, the AM series magnesium alloy preferably includes one or more of AM50, AM60, AM20, and AM100. In this invention, the AM series magnesium alloy scrap preferably includes scrap generated during die casting and processing of AM series magnesium alloys, and the shape of the scrap preferably includes blocks, flakes, strips, or granules.

[0023] In this invention, the temperature of the vacuum pressure distillation is preferably 650-850°C, more preferably 700-800°C; the vacuum degree of the vacuum pressure distillation is preferably 300-1000 Pa, more preferably 400-900 Pa; and the time of the vacuum pressure distillation is preferably 30-60 min, more preferably 40-55 min.

[0024] This invention preferably involves placing AM series magnesium alloys in a crucible for vacuum pressure distillation. Preferably, a filter screen is positioned at a distance of 1 / 5 to 1 / 2 from the bottom of the crucible, and the AM series magnesium alloy waste is placed on the surface of this filter screen for vacuum pressure distillation. In this invention, the pore size of the filter screen is preferably 30-100 mesh, more preferably 40-90 mesh. Placing the AM series magnesium alloy waste on the filter screen surface allows for the removal of non-metallic inclusions (mainly oxides, such as MgO) while obtaining the Al-Mn alloy melt, thus improving the purity of the Al-Mn alloy melt. During vacuum pressure distillation, residues (aluminum, manganese, and non-volatile metallic impurities) melt, are filtered through the filter screen, and collect at the bottom of the crucible. After cooling, they form an Al-Mn master alloy. In this invention, the non-volatile impurities preferably include one or more of copper, iron, and nickel. In this invention, the Al-Mn master alloy can be used for the production of 3XXX series aluminum alloys.

[0025] After obtaining the metal vapor, the present invention sequentially performs vacuum isothermal condensation and vacuum quenching condensation on the metal vapor to obtain metallic magnesium. In the present invention, the temperature of the vacuum isothermal condensation is preferably less than 650°C and greater than or equal to 500°C, more preferably 530-600°C; the vacuum degree of the vacuum isothermal condensation is preferably 300-1000 Pa, more preferably 400-900 Pa.

[0026] In this invention, the vacuum degree of the vacuum quenching condensation is preferably 300–1000 Pa, more preferably 400–900 Pa. In this invention, the condensation temperature gradient of the vacuum quenching condensation is preferably 13–28 °C / cm, more preferably 15–25 °C / cm. In this invention, the vacuum quenching condensation method is preferably air cooling or water cooling.

[0027] In this invention, the vacuum pressure distillation, vacuum isothermal condensation, and vacuum quench condensation are preferably performed in a vacuum recovery device, which preferably includes a cavity; the cavity preferably includes a heating section 1, an isothermal condensation section 2, and a quench condensation section 3 arranged sequentially; a heating element 9 is provided on the outer surface of the heating section 1 and the isothermal condensation section 2, and a heat insulation layer 4 is provided on the surface of the heating element 9; a filter screen 5 is provided between the heating section 1 and the isothermal condensation section 2. This invention preferably utilizes the heating element 9 to provide a heat source.

[0028] In this invention, the pore size of the filter screen 5 is preferably 30-100 mesh, more preferably 40-90 mesh. By placing a filter screen between the heating section 1 and the constant-temperature condensation section 2, this invention can intercept oxide particles entrained in metal vapor, thereby improving the purity of metallic magnesium.

[0029] In this invention, the outer surface of the reaction chamber of the quenching and condensation section 3 is preferably provided with a condenser sleeve. In this invention, the cooling medium of the quenching and condensation section 3 is preferably air or water, more preferably water.

[0030] In this invention, the rapid cooling condensation section 3 can form a large degree of subcooling, which promotes the condensation of other volatile impurities (zinc (Zn), lead (Pb), potassium (K), sodium (Na)) in the metal vapor, thereby improving the purity of the magnesium metal.

[0031] In this invention, the vacuum recovery equipment preferably further includes a vacuum control system and a temperature control system 6. In this invention, the vacuum control system includes an inert gas container 7 and a vacuum pump 8. Preferably, the vacuum pump 8 is used to pump the pressure inside the cavity to 0.1–1 Pa, and then inert gas is introduced into the cavity through the inert gas container 7 to achieve the required vacuum level. In this invention, the inert gas is preferably argon, helium, neon, krypton, or xenon, more preferably argon.

[0032] Figure 1 The diagram shows the structure of the equipment used to process AM series magnesium alloy waste in the embodiment. In the diagram, 1 is the heating section, 2 is the constant temperature condensation section, 3 is the rapid cooling condensation section, 4 is the insulation layer, 5 is the filter screen, 6 is the temperature control system, 7 is the inert gas container, 8 is the vacuum pump, and 9 is the heating element.

[0033] This invention controls the pressure within the cavity through a vacuum control system, thereby regulating the vacuum level required for vacuum pressure-controlled distillation, vacuum isothermal condensation, and vacuum quenching condensation. This invention also regulates the temperatures required for vacuum pressure-controlled distillation, vacuum isothermal condensation, and vacuum quenching condensation through a temperature control system.

[0034] This invention utilizes a vacuum control system to adjust the system vacuum level, which can appropriately reduce the evaporation rate of metals. By taking advantage of the differences in the velocity, energy, and condensation temperature characteristics of different metal vapors, and by controlling the temperature and temperature gradient of the condensation zone, magnesium vapor is directionally condensed in a specific area. Other impurity metals are driven by the large temperature gradient to condense in a lower temperature area, thereby further purifying the magnesium metal during the directional condensation process.

[0035] The present invention sets a large temperature difference between the heating section 1 and the constant temperature condensation section 2, which is conducive to driving the volatile impurity metal in the metal vapor to migrate to the rapid cooling condensation section 3. Otherwise, the impurity vapor metal will first condense in the constant temperature condensation section. Even if the temperature of the constant temperature condensation section reaches the set temperature and some impurities volatilize again, it will still contaminate the magnesium metal in the constant temperature condensation section (reducing the purity).

[0036] This invention utilizes the saturated vapor pressure and condensation characteristics of magnesium and impurity metals, and coordinates the system vacuum degree and condensation temperature to directly recover 4N high-purity magnesium and Al-Mn master alloys that can be used for aluminum alloy production from AM series waste in one step.

[0037] This invention utilizes the aforementioned vacuum equipment to directly recover AM series magnesium alloy waste in one step, simultaneously obtaining 4N high-purity magnesium and an Al-Mn master alloy for aluminum alloy preparation. The entire process is carried out in a sealed vacuum furnace, resulting in a short process flow, no chemical reagent consumption, and no wastewater or waste gas generation, making it green and efficient. It solves the problems of low purity of recycled magnesium obtained by vacuum methods, repeated distillation, and the inability to reuse residues, greatly improving the economics of vacuum-based recovery of AM series magnesium alloy waste and achieving efficient recycling of metal resources.

[0038] To further illustrate the present invention, the technical solutions provided by the present invention will be described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0039] Example 1

[0040] use Figure 1 The device shown processes magnesium alloy waste. A 50-mesh filter screen is installed at 1 / 2 of the distance from the bottom of the crucible. After placing the AM50A block magnesium alloy waste on the surface of the filter screen in the crucible, it is placed in the heating section 1 of the reaction chamber. A 50-mesh filter screen is placed between the heating section and the constant temperature condensation section 2, and the chamber is vacuum sealed.

[0041] Turn on vacuum pump 8 to evacuate the reaction chamber to 1 Pa, then fill with argon gas to adjust the vacuum level in the chamber to 300 Pa. Simultaneously heat heating section 1 and isothermal condensation section 2 at a heating rate of 10 °C / min. Air is introduced into the condenser sleeve of quench condensation section 3 to condense the gases at a condensation temperature gradient of 13.75 °C / cm. Set the temperature of heating section 1 to 800 °C and the temperature of isothermal condensation section 2 to 550 °C. After the temperature reaches the set temperature, maintain the temperature for 50 min (perform vacuum pressure distillation for 50 min).

[0042] After the heat preservation is completed, heating is stopped, and the system vacuum is maintained at 300 Pa until the temperature inside the reaction chamber drops to room temperature. The vacuum pump is then turned off, and the argon gas filling is stopped. In the isothermal condensation section 2, 4N high-purity magnesium (Al 0.0015%, Zn 0.0018%, Fe < 0.0001%, Cu < 0.0001%, Ni < 0.0001%, Mn < 0.0001%, Si 0.0053%) with a purity > 99.991% is obtained. In the crucible, Al-Mn master alloy (Al 91.84%, Mn 6.51%, Cu 0.028%, Fe 0.023%, Ni 0.0082%, Zn 0.0004%, Si 0.28%) is obtained, wherein the contents of impurities Cu, Fe, Ni, Si, and Zn meet the composition requirements for 3XXX aluminum alloys in GB / T3190-2020 Chemical Composition of Wrought Aluminum and Aluminum Alloys. The metal recovery rate of the entire recycling process reached 99.52%.

[0043] Example 2

[0044] use Figure 1 The device shown processes magnesium alloy waste. A 50-mesh filter screen is installed at 1 / 2 of the distance from the bottom of the crucible. After placing the AM60A block magnesium alloy waste on the surface of the filter screen in the crucible, it is placed in the heating section 1 of the reaction chamber. A 50-mesh filter screen is placed between the heating section and the constant temperature condensation section 2, and the chamber is vacuum sealed.

[0045] Turn on vacuum pump 8 to evacuate the reaction chamber to 1 Pa, then fill it with argon gas to adjust the vacuum level to 1000 Pa. Simultaneously heat heating section 1 and isothermal condensation section 2 at a heating rate of 10 °C / min. Cooling water is circulated through the condenser sleeve of quench condensation section 3 to condense the material at a condensation temperature gradient of 27.5 °C / cm. Set the temperature of heating section 1 to 750 °C and the temperature of isothermal condensation section 2 to 630 °C. After the temperature reaches the set temperature, maintain the temperature for 60 min (perform vacuum pressure distillation for 60 min).

[0046] After the heat preservation period, heating was stopped, and the system vacuum was maintained at 1000 Pa until the temperature inside the reaction chamber dropped to room temperature. The vacuum pump was then turned off, and the argon gas supply was stopped. In the isothermal condensation section 2, 4N high-purity magnesium (Al < 0.0001%, Zn 0.0014%, Fe < 0.0001%, Cu 0.0001%, Ni < 0.0001%, Mn < 0.0001%, Si 0.0061%) with a purity > 99.992% was obtained. In the crucible, an Al-Mn master alloy (Al 92.10%, Mn 6.34%, Cu 0.022%, Fe 0.019%, Ni 0.0022%, Zn 0.0006%, Si 0.25%) was obtained, with impurities of Cu, Fe, Ni, Si, and Zn lower than the standard for 3XXX aluminum alloys. The metal recovery rate of the entire recycling process reached 99.75%.

[0047] The recycling results from Examples 1 and 2 show that the method provided by this invention can be used to recycle AM ​​series magnesium alloy waste to obtain high-purity metallic magnesium and aluminum-manganese alloys.

[0048] Although the above embodiments have provided a detailed description of the present invention, they are only some embodiments of the present invention, and not all embodiments. People can obtain other embodiments based on these embodiments without creative effort, and these embodiments all fall within the protection scope of the present invention.

Claims

1. A method of recycling AM-series magnesium alloy scrap material, characterized by, Includes the following steps: AM series magnesium alloy scrap was subjected to vacuum pressure distillation to obtain metal vapor and Al-Mn alloy melt, respectively; the temperature of the vacuum pressure distillation was 750~800℃, the vacuum degree of the vacuum pressure distillation was 300~1000Pa, and the time of the vacuum pressure distillation was 50~60min. The metal vapor is subjected to vacuum isothermal condensation and vacuum quenching condensation sequentially to obtain metallic magnesium; the vacuum degree of the vacuum isothermal condensation is 300~1000Pa; the vacuum degree of the vacuum isothermal condensation is 550~630℃; the vacuum degree of the vacuum quenching condensation is 300~1000Pa; the condensation temperature gradient of the vacuum quenching condensation is 13.75~27.5℃ / cm; The vacuum pressure distillation, vacuum constant temperature condensation, and vacuum quench condensation are carried out in a vacuum recovery device, which includes a cavity; the cavity includes a heating section (1), a constant temperature condensation section (2), and a quench condensation section (3) arranged sequentially; the outer surfaces of the heating section (1) and the constant temperature condensation section (2) are provided with heating elements (9), and the surface of the heating elements (9) is provided with a heat insulation layer (4); a filter screen (5) is provided between the heating section (1) and the constant temperature condensation section (2), which can intercept oxide particles mixed in magnesium metal vapor; the quench condensation section (3) can form a large degree of supercooling, which promotes the condensation of volatile impurities in the metal vapor and improves the purity of the magnesium metal; the volatile impurities include zinc, lead, potassium, and sodium; A crucible is set in the vacuum pressure distillation section, and a filter screen is set at a position 1 / 5 to 1 / 2 of the distance from the bottom of the crucible. AM series magnesium alloy waste is placed on the surface of the filter screen and vacuum pressure distilled to obtain Al-Mn alloy melt. After the Al-Mn alloy melt passes through the filter screen to filter out oxides, it collects at the bottom of the crucible and forms an Al-Mn master alloy after cooling. The oxides include MgO.

2. The method of claim 1, wherein, The vacuum recovery equipment also includes a vacuum control system and a temperature control system (6), wherein the vacuum control system includes an inert gas container (7) and a vacuum pump (8).

3. The method of claim 2, wherein, The filter screen (5) has a pore size of 30~100 mesh.

4. The method of claim 1, wherein, The AM series magnesium alloys include one or more of AM50, AM60, AM20 and AM100.

5. The method of claim 1, wherein, The AM series magnesium alloy scrap includes scraps generated during the die casting and processing of AM series magnesium alloys, and the shape of the scraps includes blocks, flakes, strips or granules.

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