Process for the preparation of crude cadmium from cadmium-containing soot

Abstract

This invention belongs to the field of metallurgical technology and relates to a method for preparing crude cadmium from cadmium-containing flue dust, comprising the following steps: S1, neutral leaching of cadmium-containing flue dust with deionized water to obtain filter residue and filtrate 1; then acid leaching of the filter residue with sulfuric acid to obtain lead slag and filtrate 2; S2, mixing filtrate 1 and filtrate 2, adding an oxidant and iron salt for primary purification to obtain arsenic-antimony slag and filtrate 3; adding zinc powder twice to filtrate 3 for secondary purification to obtain copper-nickel slag and filtrate 4; S3, concentrating filtrate 4 to obtain cadmium-rich solution, then aging at 70-85℃; subsequently cooling to 50-65℃, adding polyethylene glycol, and adding aluminum-magnesium alloy powder under high-speed stirring for a displacement reaction; after the reaction, obtaining filtrate and crude cadmium. This invention deeply removes impurities such as arsenic, antimony, and lead from cadmium-containing flue dust and obtains high-purity, dense crude cadmium particles with the aid of morphology modifiers, high-speed stirring, and aluminum-magnesium alloy powder.

Description

Technical Field

[0001] This invention belongs to the field of metallurgical technology, specifically relating to a method for preparing crude cadmium from cadmium-containing flue dust. Background Technology

[0002] The smog collected by electrostatic precipitators in lead smelting workshops is a source of cadmium-containing soot, whose chemical composition is highly complex, mainly containing various valuable elements such as Cd, Pb, As, Zn, S, Cu, Sb, and Ag. Cadmium is a highly toxic and carcinogenic element, causing irreversible damage to the environment and human health; at the same time, cadmium is an important raw material for colored pigments and nickel-cadmium batteries. Given the hazards of cadmium and its uses, the resource utilization and harmless treatment of cadmium soot has significant economic and environmental value.

[0003] The traditional wet process for recovering cadmium from cadmium soot is “sulfuric acid leaching - solution purification - zinc powder or aluminum powder replacement (to obtain sponge cadmium) - sponge cadmium briquettes (to obtain crude cadmium)”. This process has the following inherent defects: (1) long process and high energy consumption: the briquettes of sponge cadmium are an essential additional step, resulting in a long process and high energy consumption; (2) low metal recovery rate: during the washing and briquettes of sponge cadmium, the physical and chemical losses of cadmium are serious, and the total recovery rate is usually less than 95%; (3) high safety and environmental risks: sponge cadmium has a large specific surface area and is extremely easy to oxidize and spontaneously combust in the air, making its handling and storage very dangerous.

[0004] To effectively address the aforementioned technical challenges, the industry has undertaken a series of research and explorations. For example, some studies have attempted to directly prepare cadmium plates using electrowinning, aiming to simplify the process and improve production efficiency. However, practical applications have shown that electrowinning itself has many limitations, such as low current efficiency, oxygen evolution and acid mist pollution during the anodic reaction, and the increasingly prominent issues of complex equipment structure and high operation and maintenance costs, which limit the large-scale industrial promotion of this technology. Therefore, developing a new process that can eliminate dependence on electrowinning and efficiently and stably obtain dense crude cadmium products directly from solution through chemical displacement reactions would not only significantly shorten the process flow and reduce energy and material consumption, but also have significant technological breakthrough value and considerable economic application value. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides a method for preparing crude cadmium from cadmium-containing flue ash.

[0006] The specific technical solution is as follows:

[0007] A method for preparing crude cadmium from cadmium-containing fly ash includes the following steps:

[0008] S1 Cadmium-containing soot is neutrally leached with deionized water to obtain filter residue and filtrate 1. Then, the filter residue is acidically leached with sulfuric acid to obtain lead slag and filtrate 2.

[0009] S2 After mixing filtrate 1 and filtrate 2, add oxidant and iron salt for primary purification to obtain arsenic antimony slag and filtrate 3; add zinc powder to filtrate 3 twice for secondary purification to obtain copper nickel slag and filtrate 4.

[0010] S3 concentrates filtrate 4 to obtain cadmium-rich solution, and ages it at 70~85℃; then cools it to 50~65℃, adds polyethylene glycol, and adds aluminum-magnesium alloy powder under stirring to carry out a displacement reaction. After the reaction is completed, filtrate and crude cadmium are obtained.

[0011] The main components of cadmium-containing fly ash are: Cd ≥ 15 wt%, Pb ≤ 15 wt%, Zn ≤ 5.0 wt%, Cu ≤ 1.0 wt%, As ≤ 1.0 wt%, Sb ≤ 1.0 wt%, and Ni ≤ 1.0 wt%.

[0012] The principle of this invention is as follows:

[0013] This invention involves neutral-acid leaching of cadmium-containing soot to separate cadmium from lead, gold, and silver. Subsequently, a primary purification process (iron salt-oxidation method) and a secondary purification process are performed to separate cadmium from impurities such as arsenic, antimony, copper, and nickel. Finally, crude cadmium with a cadmium content >99.0 wt% is obtained through aging and displacement.

[0014] In step S1, the cadmium-containing soot is subjected to two countercurrent leaching processes to obtain a cadmium-rich leachate.

[0015] Furthermore, in the neutral leaching process, the liquid-to-solid mass ratio is (2~4):1, the temperature is 40~85℃, and the time is 1~2h; in the acidic leaching process, the sulfuric acid concentration is 5~15g / L, the liquid-to-solid mass ratio is (3~5):1, the temperature is 70~85℃, and the time is 2~4h.

[0016] Preferably, the lead slag obtained in step S1 is returned to the lead smelting system to recover lead, gold, and silver.

[0017] In step S2, the iron salt-oxidation method is used. An oxidant and ferric salt are added to the mixture of filtrate 1 and filtrate 2. After the reaction, arsenic and antimony are precipitated in a stable form of iron salt co-precipitate, providing a high-purity solution for subsequent replacement and avoiding impurities from interfering with the crystallization process of cadmium. At the same time, zinc powder is added in two batches to deeply remove copper and nickel from the solution, resulting in pure filtrate 4, i.e., cadmium sulfate solution.

[0018] Furthermore, the purification temperature is 80~95℃, the time is 1~2h, and the pH is 3~4; the molar ratio of the total amount of arsenic and antimony in the mixed solution of oxidant and filtrate 1 and filtrate 2 is (2~5):1; the molar ratio of the total amount of arsenic and antimony in the mixed solution of iron salt and filtrate 1 and filtrate 2 is (5~10):1.

[0019] The preferred iron salt is ferric sulfate or ferric chloride, and the preferred oxidant is hydrogen peroxide.

[0020] Furthermore, in the secondary purification process, the molar ratio of the total amount of zinc powder added to the total amount of copper in the solution in the first step is (1~1.3):1, the reaction temperature is 40~80℃, and the reaction time is 1~2h. The molar ratio of the total amount of zinc powder added to the total amount of nickel in the solution in the second step is (1~1.3):1, the reaction temperature is 40~80℃, and the reaction time is 1~2h.

[0021] Preferably, the arsenic-antimony slag and copper-nickel slag obtained in step S2 are returned to the copper pyrometallurgical system to recover copper, arsenic, nickel, etc.

[0022] In step S3, the cadmium-rich solution is aged at high temperature to induce a slightly saturated state of cadmium ions in the solution, creating thermodynamic conditions for subsequent uniform and dense precipitation. Simultaneously, polyethylene glycol, as a crystal morphology control agent, selectively adsorbs onto specific crystal faces of cadmium nuclei, inhibiting dendritic growth. High-speed stirring provides strong fluid shear force, promptly breaking up newly formed micro-dendritic crystals and preventing them from interconnecting into a sponge-like network, promoting the formation of regular, dense cadmium particles. Furthermore, compared to pure magnesium powder, the electrocoupler effect between magnesium and aluminum is regulated by the relatively low activity of aluminum, resulting in a more moderate overall reaction rate and easier process control. The deposited metal tends to nucleate and grow more uniformly, forming a denser powder product, which is beneficial for a more thorough reaction. Compared to pure aluminum powder, its surface oxide film is more easily destroyed, leading to a more complete reaction. Additionally, the remaining aluminum-magnesium alloy powder after the displacement reaction can continue to react with acid in a slightly acidic solution (pH=4~5), preventing the aluminum-magnesium alloy powder from mixing with crude cadmium as an impurity, resulting in high purity crude cadmium.

[0023] Furthermore, the concentration of cadmium sulfate in the cadmium-rich solution is >40g / L.

[0024] Furthermore, the aging time is 2-4 hours; the volume of polyethylene glycol added is 0.05%-0.1% of the solution volume, the stirring rate is 300-500 r / min, the displacement reaction time is 1-2 hours, and the pH is controlled at 4-5 during the displacement reaction.

[0025] Furthermore, in the aluminum-magnesium alloy powder, the magnesium content is 20wt%~40wt% and the aluminum content is 60wt%~80wt%; the molar ratio of the total amount of magnesium and aluminum in the magnesium-aluminum alloy powder to the total amount of cadmium in the solution is (1~1.1):1.

[0026] Preferably, the degree of polymerization of the polyethylene glycol is 1200-1600; and the particle size of the aluminum-magnesium alloy powder is 100-200 mesh.

[0027] Preferably, in step S3, during the displacement reaction, sulfuric acid or sodium hydroxide is added to adjust the pH to 4-5.

[0028] The crude cadmium obtained in step S3 is in the form of dense granules with a density > 6.5 g / cm3 and a composition of Cd > 99.0 wt%, Zn < 0.5 wt%, and Pb < 0.05 wt%.

[0029] Preferably, the filtrate obtained in step S3 is returned to the wastewater treatment system.

[0030] The beneficial effects of this invention are as follows:

[0031] This invention enhances the removal of arsenic and antimony from cadmium-containing fly ash by employing an iron salt-oxidation method to convert them into stable precipitates. Simultaneously, zinc powder is added to further remove copper and nickel from the solution. High-temperature aging induces a slightly saturated state of cadmium ions in the solution, creating thermodynamic conditions for the subsequent uniform and dense precipitation of crude cadmium. Polyethylene glycol, as a crystal morphology control agent, selectively adsorbs onto specific crystal faces of cadmium nuclei, inhibiting their dendritic growth. High-speed stirring provides strong fluid shear force, promptly breaking up newly formed micro-dendritic crystals and preventing them from interconnecting into a sponge-like network, promoting the formation of regular, dense cadmium particles. Furthermore, the reaction process of aluminum-magnesium alloy powder is easier to control, and the deposited metal tends to nucleate and grow more uniformly, forming a denser powder product. Attached Figure Description

[0032] Figure 1 This is a process flow diagram for preparing crude cadmium from cadmium-containing flue dust in a specific implementation method. Detailed Implementation

[0033] The embodiments of the present invention will be described in further detail below with reference to the accompanying drawings and examples. The following examples are for illustrative purposes only and should not be construed as limiting the scope of the invention. Unless otherwise specified, the experimental methods used in the following examples are conventional methods. Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0034] Example 1

[0035] Methods for preparing crude cadmium from cadmium-containing fly ash.

[0036] The main components of the cadmium-containing fly ash are: Cd 15.24wt%, Pb 14.14wt%, Zn 4.57wt%, Cu 0.83wt%, As 0.74wt%, Sb 0.95wt%, and Ni 0.92wt%.

[0037] Includes the following steps:

[0038] S1. Cadmium-containing soot is neutrally leached at 85°C for 1 hour using deionized water at a liquid-to-solid mass ratio of 2:1. After solid-liquid separation, filtrate 1 and filter residue are obtained. Subsequently, the filter residue is acidically leached at 85°C for 2 hours using a 5 g / L sulfuric acid solution at a liquid-to-solid mass ratio of 3:1. After solid-liquid separation, filtrate 2 and lead slag are obtained. The obtained lead slag is returned to the lead smelting system to recover lead, gold, and silver.

[0039] S2: After mixing filtrate 1 and filtrate 2, ferric sulfate and hydrogen peroxide are added, and the mixture is heated to 80℃ at pH 3 for a first purification reaction for 2 hours. After solid-liquid separation, arsenic-antimony slag and filtrate 3 are obtained. Then, a second purification is performed. Zinc powder is added to filtrate 3 and reacted at 40℃ for 2 hours. After the reaction, zinc powder is added to the solution again and reacted at 80℃ for 1 hour. After the reaction, copper-nickel slag and filtrate 4 are obtained after solid-liquid separation. The arsenic-antimony slag and copper-nickel slag are returned to the copper pyrometallurgical system to recover copper, arsenic, nickel, etc. The molar ratio of H2O2 in hydrogen peroxide to the total amount of arsenic and antimony in the mixed solution of filtrate 1 and filtrate 2 is 3:1, and the molar ratio of ferric sulfate to the total amount of arsenic and antimony in the mixed solution of filtrate 1 and filtrate 2 is 7:1. The molar ratio of the total amount of zinc powder added in the first addition to the total amount of copper in the solution is 1:1, and the molar ratio of the total amount of zinc powder added in the second addition to the total amount of nickel in the solution is 1.3:1.

[0040] S3. Filtrate 4 was concentrated to a cadmium sulfate concentration of 40.25 g / L to obtain a cadmium-rich solution, which was then aged at 70°C for 3 h. Subsequently, the temperature was lowered to 50°C, and polyethylene glycol (degree of polymerization 1200) was added as a morphology control agent. Then, aluminum-magnesium alloy powder was slowly and continuously added under high-speed stirring at 400 r / min to carry out a displacement reaction for 1 h, and the pH of the solution was controlled at 4. After the reaction was completed, filtrate and crude cadmium were obtained. The filtrate was returned to the wastewater treatment system. The volume of polyethylene glycol added was 0.1% of the solution volume. The aluminum-magnesium alloy powder had a particle size of 100 mesh, a magnesium content of 20 wt%, and an aluminum content of 80 wt%. The molar ratio of the total magnesium and aluminum in the aluminum-magnesium alloy powder to the total cadmium in the solution was 1:1.

[0041] Example 2

[0042] Methods for preparing crude cadmium from cadmium-containing fly ash.

[0043] The main components of the cadmium-containing fly ash are: Cd 19.55wt%, Pb 10.24wt%, Zn 3.25wt%, Cu 0.57wt%, As 0.94wt%, Sb 0.86wt%, and Ni 0.37wt%.

[0044] Includes the following steps:

[0045] S1. Cadmium-containing soot is neutrally leached for 2 hours at 40°C using deionized water at a liquid-to-solid mass ratio of 3:1. After solid-liquid separation, filtrate 1 and filter residue are obtained. Subsequently, the filter residue is acidically leached for 3 hours at 75°C using a 12 g / L sulfuric acid solution at a liquid-to-solid mass ratio of 4:1. After solid-liquid separation, filtrate 2 and lead slag are obtained. The obtained lead slag is returned to the lead smelting system to recover lead, gold, and silver.

[0046] S2: After mixing filtrate 1 and filtrate 2, ferric sulfate and hydrogen peroxide are added, and the mixture is heated to 85℃ at pH 3.5 for a first purification reaction of 1.5h. After solid-liquid separation, arsenic-antimony slag and filtrate 3 are obtained. Then, a second purification is performed. Zinc powder is added to filtrate 3 and reacted at 80℃ for 1h. After the reaction, zinc powder is added again to the solution and reacted at 40℃ for 2h. After the reaction, copper-nickel slag and filtrate 4 are obtained after solid-liquid separation. The arsenic-antimony slag and copper-nickel slag are returned to the copper pyrometallurgical system to recover copper, arsenic, nickel, etc. The molar ratio of H2O2 in hydrogen peroxide to the total amount of arsenic and antimony in the mixed solution of filtrate 1 and filtrate 2 is 2:1, and the molar ratio of ferric sulfate to the total amount of arsenic and antimony in the mixed solution of filtrate 1 and filtrate 2 is 5:1. The molar ratio of the total amount of zinc powder added in the first addition to the total amount of copper in the solution is 1.3:1, and the molar ratio of the total amount of zinc powder added in the second addition to the total amount of nickel in the solution is 1:1.

[0047] S3. Filtrate 4 was concentrated to a cadmium sulfate concentration of 42.26 g / L to obtain a cadmium-rich solution, which was then aged at 75°C for 2 h. Subsequently, the temperature was lowered to 60°C, and polyethylene glycol (degree of polymerization 1400) was added as a morphology control agent. Then, aluminum-magnesium alloy powder was slowly and continuously added under high-speed stirring at 300 r / min to carry out a displacement reaction for 1.5 h, and the pH of the solution was controlled at 4.5. After the reaction was completed, filtrate and crude cadmium were obtained. The filtrate was returned to the wastewater treatment system. The volume of polyethylene glycol added was 0.08% of the solution volume. The aluminum-magnesium alloy powder had a particle size of 150 mesh, a magnesium content of 40 wt%, and an aluminum content of 60 wt%. The molar ratio of the total magnesium and aluminum in the aluminum-magnesium alloy powder to the total cadmium in the solution was 1.1:1.

[0048] Example 3

[0049] Methods for preparing crude cadmium from cadmium-containing fly ash.

[0050] The main components of the cadmium-containing fly ash are: Cd 20.14wt%, Pb 8.75wt%, Zn 2.41wt%, Cu 0.55wt%, As 0.67wt%, Sb 0.82wt%, and Ni 0.64wt%.

[0051] Includes the following steps:

[0052] S1. Cadmium-containing soot is neutrally leached for 1.5 hours at 75°C using deionized water at a liquid-to-solid mass ratio of 4:1. After solid-liquid separation, filtrate 1 and filter residue are obtained. Subsequently, the filter residue is acidically leached for 4 hours at 70°C using a 15 g / L sulfuric acid solution at a liquid-to-solid mass ratio of 5:1. After solid-liquid separation, filtrate 2 and lead slag are obtained. The obtained lead slag is returned to the lead smelting system to recover lead, gold, and silver.

[0053] S2: After mixing filtrate 1 and filtrate 2, ferric sulfate and hydrogen peroxide are added, and the mixture is heated to 95℃ at pH 4 for a first purification reaction of 1 hour. After solid-liquid separation, arsenic-antimony slag and filtrate 3 are obtained. A second purification is then performed: zinc powder is added to filtrate 3 and reacted at 60℃ for 1.5 hours. After the reaction, zinc powder is added again and reacted at 60℃ for 1.5 hours. After the reaction, copper-nickel slag and filtrate 4 are obtained after solid-liquid separation. The arsenic-antimony slag and copper-nickel slag are returned to the copper pyrometallurgical system for the recovery of copper, arsenic, nickel, etc. The molar ratio of H2O2 in hydrogen peroxide to the total amount of arsenic and antimony in the mixed solution of filtrate 1 and filtrate 2 is 5:1, and the molar ratio of ferric sulfate to the total amount of arsenic and antimony in the mixed solution of filtrate 1 and filtrate 2 is 10:1. The molar ratio of the total amount of zinc powder added in the first addition to the total amount of copper in the solution is 1.1:1, and the molar ratio of the total amount of zinc powder added in the second addition to the total amount of nickel in the solution is 1.2:1.

[0054] S3. Filtrate 4 was concentrated to a cadmium sulfate concentration of 43.65 g / L to obtain a cadmium-rich solution, which was then aged at 85°C for 4 h. Subsequently, the temperature was lowered to 65°C, and polyethylene glycol (degree of polymerization 1600) was added as a morphology control agent. Then, aluminum-magnesium alloy powder was slowly and continuously added under high-speed stirring at 500 r / min to carry out a displacement reaction for 2 h, and the pH of the solution was controlled at 5. After the reaction was completed, filtrate and crude cadmium were obtained. The filtrate was returned to the wastewater treatment system. The volume of polyethylene glycol added was 0.05% of the solution volume. The aluminum-magnesium alloy powder had a particle size of 200 mesh, a magnesium content of 30 wt%, and an aluminum content of 70 wt%. The molar ratio of the total magnesium and aluminum in the aluminum-magnesium alloy powder to the total cadmium in the solution was 1.05:1.

[0055] test

[0056] The contents of Cd, Zn, and Pb and their densities in the crude cadmium obtained in Examples 1-3 were detected, and the results are shown in Table 1.

[0057] Cd in crude cadmium was determined by titration in "Chemical Analysis Methods for Copper Smelting Dust Part 7: Determination of Cadmium Content by Flame Atomic Absorption Spectrometry and Titration" (YS / T 1512.7-2021); impurities Zn and Pb were determined by inductively coupled plasma atomic emission spectrometry (YS / T 1512.10-2022) in "Chemical Analysis Methods for Copper Smelting Dust Part 10: Determination of Content of Copper, Lead, Zinc, Bismuth, Arsenic, Indium, Silver, Cadmium, Antimony, Calcium, Magnesium and Iron" (YS / T 1512.10-2022); and density was determined by liquid impregnation method in "Determination of Effective Density of Metal Powders" (GB / T 5161-2014).

[0058] Table 1. Contents and densities of Cd, Zn, and Pb in crude cadmium

[0059]

[0060] As shown in Table 1, the purity of the crude cadmium in Examples 1-3 all reached over 99%, and the density was all greater than 6.5 g / cm³. 3 This indicates that the crude cadmium produced using this technology has high purity and high density.

[0061] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for the preparation of crude cadmium from cadmium-containing soot, characterized in that, The method comprises the following steps: S1: neutral leaching of cadmium-containing fly ash with deionized water to obtain a filter residue and a filtrate 1, and then acid leaching of the filter residue with sulfuric acid to obtain a lead residue and a filtrate 2; S2: mixing of the filtrate 1 and the filtrate 2, and then adding an oxidizing agent and an iron salt to perform primary purification to obtain an arsenic-antimony residue and a filtrate 3; adding zinc powder twice to the filtrate 3 to perform secondary purification to obtain a copper-nickel residue and a filtrate 4; S3: concentrating the filtrate 4 to obtain a cadmium-rich solution, and then aging at 70-85 DEG C; subsequently, cooling to 50-65 DEG C, adding polyethylene glycol, and then adding aluminum-magnesium alloy powder under stirring to perform a displacement reaction, and finally obtaining a filtrate and crude cadmium.

2. The method of claim 1, wherein the crude cadmium is prepared by the steps of: In step S1, during the neutral leaching, the liquid-solid mass ratio is (2-4):1, the temperature is 40-85 DEG C, and the time is 1-2 h; during the acid leaching, the sulfuric acid concentration is 5-15 g / L, the liquid-solid mass ratio is (3-5):1, the temperature is 70-85 DEG C, and the time is 2-4 h.

3. The method of claim 1, wherein the crude cadmium is prepared by the steps of: In step S2, the primary purification temperature is 80-95 DEG C, the time is 1-2 h, and the pH is 3-4.

4. The method of claim 1, wherein the crude cadmium is prepared by the steps of: In step S2, the molar ratio of the oxidizing agent to the total amount of arsenic and antimony in the mixed solution of the filtrate 1 and the filtrate 2 is (2-5):1; the molar ratio of the iron salt to the total amount of arsenic and antimony in the mixed solution of the filtrate 1 and the filtrate 2 is (5-10):

1.

5. The method of claim 1, wherein the crude cadmium is prepared by the steps of: In step S2, during the secondary purification, the molar ratio of the total amount of the first zinc powder to the total amount of copper in the solution is (1-1.3):1, the reaction temperature is 40-80 DEG C, and the reaction time is 1-2 h; the molar ratio of the total amount of the second zinc powder to the total amount of nickel in the solution is (1-1.3):1, the reaction temperature is 40-80 DEG C, and the reaction time is 1-2 h.

6. The method of claim 1, wherein the crude cadmium is prepared by the steps of: In step S3, the cadmium sulfate concentration in the cadmium-rich solution is >40 g / L.

7. The method of claim 1, wherein the crude cadmium is prepared by the steps of: In step S3, the aging time is 2-4 h; the volume of the polyethylene glycol added is 0.05%-0.1% of the volume of the solution.

8. The method of claim 1, wherein the crude cadmium is prepared by the steps of: In step S3, the stirring rate is 300-500 r / min; in the aluminum-magnesium alloy powder, the magnesium content is 20wt%-40wt%, and the aluminum content is 60wt%-80wt%; the molar ratio of the total amount of magnesium and aluminum in the aluminum-magnesium alloy powder to the total amount of cadmium in the solution is (1-1.1):

1.

9. The method of claim 1, wherein the crude cadmium is prepared by the steps of: In step S3, the displacement reaction time is 1-2 h, and the pH is controlled to be 4-5 during the displacement reaction.

10. The method of claim 1, wherein the crude cadmium is prepared by the steps of: In step S3, the particle size of the aluminum-magnesium alloy powder is 100-200 meshes.

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