A method for preparing copper powder for conductive paste by using copper smelting fume back-extraction solution

Abstract

This invention discloses a method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid, belonging to the field of powder metallurgy technology. The back-extraction liquid is purified to remove impurities, and the copper concentration is adjusted to 50-100 g / L, and the pH value is adjusted to 2-12. One or more of a complexing agent, buffer, and nucleation regulator are added at 0.1-2.0 times the molar amount of copper ions, along with a dispersant and morphology regulator, each added at 0.1-5.0% of the copper mass. A reducing agent is added to the reduction precursor solution at 1.0-2.5 times the theoretical molar amount required to completely reduce copper ions to metallic copper, and the reaction is carried out at 30-90℃ for 0.5-4 h, resulting in wet copper powder. After washing the wet copper powder, an antioxidant is added at 0.1-0.5% of the copper powder mass, and the mixture is treated at 20-70℃ for 10-50 min. The copper powder is then dried under conditions of oxygen concentration <5%, and after classification, the target copper powder is obtained. With a copper content of ≥99.5%, a particle size D50 of 0.5~5μm, spherical or near-spherical particles, no hard agglomerates, and low content of impurities such as arsenic, cadmium, and lead, it can be used in electronic conductive pastes or photovoltaic conductive pastes.

Description

Technical Field

[0001] This invention belongs to the field of powder metallurgy technology, specifically relating to a method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid. Background Technology

[0002] Copper smelting dust is an important secondary resource generated during copper smelting. This dust typically contains high-grade copper, along with various valuable elements and impurities such as zinc, germanium, arsenic, cadmium, lead, and iron. Currently, the industrial process for comprehensive copper recovery from copper smelting dust generally employs an "acid leaching-extraction-back-extraction" route. Copper is transferred to a solution through acid leaching, followed by selective extraction and back-extraction to obtain a copper-rich back-extraction solution with copper sulfate as the main component. Traditional treatment methods often use this copper-rich back-extraction solution to prepare copper sulfate crystals, obtain sponge copper through displacement, produce electrowinning copper using electrowinning, or directly return it to the main copper smelting process as a feedstock. While these methods achieve copper recovery, the added value of the resulting products is generally low, failing to fully realize the high-value potential of copper resources in copper smelting dust.

[0003] With the rapid development of industries such as electronics, new energy, and photovoltaic power generation, copper powder for conductive pastes has gradually become an important functional powder material. Compared with silver powder, copper powder has advantages such as low cost, good conductivity, and wide availability of resources, showing broad application prospects in electronic conductive pastes, silver-coated copper pastes, photovoltaic low-silver pastes, and some electrode materials. However, copper powder for conductive pastes has high requirements for purity, particle size, morphology, dispersibility, oxygen content, and oxidation resistance, and ordinary industrial copper powder cannot directly meet these requirements.

[0004] Currently, copper powder preparation technologies mainly include electrolysis, atomization, mechanical pulverization, and chemical reduction. Among these, the chemical liquid-phase reduction method has attracted widespread attention due to its relatively mild reaction conditions, strong controllability of product particle size and morphology, and suitability for preparing micron- and submicron-sized spherical or near-spherical copper powders. However, copper powders used in conductive pastes currently mostly use high-purity copper sulfate, copper chloride, or electrolytic copper solution as raw materials, resulting in high raw material purity and relatively low impurity interference. However, the complex system of copper smelting flue gas back-extraction liquid may contain residual metal ions such as arsenic, cadmium, lead, zinc, and iron, as well as chloride ions, organic phase entrainments, and other impurities. If directly used for copper powder preparation, the resulting copper powder is prone to problems such as insufficient purity, severe particle agglomeration, irregular morphology, and high oxygen content, making it difficult to meet the requirements for conductive pastes.

[0005] Therefore, it is necessary to develop a method for preparing copper powder for conductive slurry that is suitable for the characteristics of copper smelting flue dust back-extraction liquid. Through deep purification of the back-extraction liquid, copper concentration regulation, dispersion reduction, particle size and morphology control, and surface anti-oxidation treatment, the copper resources in copper smelting flue dust can be transformed from low-value-added recovery to the preparation of high-value-added functional powder materials. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid.

[0007] The objective of this invention is achieved as follows: the method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid includes the following steps: Purification and impurity removal of back-extraction solution: The back-extraction solution is clarified, filtered, and de-oiled to remove suspended solids, entrained organic phases, and impurities. Then, it is purified to remove impurity elements other than copper, resulting in purified back-extraction solution. Control of the reduction precursor solution system: Adjust the copper concentration of the purified back-extraction solution to 50~100g / L and the pH value to 2~12; add one or more of the complexing agent, buffer, and crystal nucleation regulator at 0.1~2.0 times the molar amount of copper ions to control the copper ion reduction rate and the copper crystal nucleus formation process; then add dispersant and morphology regulator to control the growth direction and particle morphology of copper crystal nuclei. The amount of dispersant and morphology regulator added is 0.1~5.0% of the copper mass to obtain the reduction precursor solution after system control. Liquid-phase dispersion reduction: Under stirring conditions, a reducing agent is added to the pre-reduction solution after system conditioning, according to 1.0 to 2.5 times the theoretical molar amount required to completely reduce copper ions to metallic copper. The reaction is carried out at 30 to 90°C for 0.5 to 4 hours to reduce copper ions to generate metallic copper powder. Solid-liquid separation is performed to obtain wet copper powder and reduced solution. Surface anti-oxidation treatment: Wash the wet copper powder to remove residual impurities, add an anti-oxidation treatment reagent at 0.1 ~ 0.5% of the copper powder mass, and perform surface anti-oxidation treatment on the washed wet copper powder at 20 ~ 70℃ for 10 ~ 50 min to form a thin protective layer on the surface of the copper powder. Then dry the copper powder under conditions of oxygen concentration < 5%. Copper powder post-processing: The dried copper powder is classified to obtain the target copper powder.

[0008] Compared with the prior art, the technical solution described in this invention has the following advantages: 1. This technical solution addresses the complex characteristics of copper smelting flue dust back-extraction liquid, which is characterized by high acidity, numerous impurities, and organic matter. It proposes a combined and synergistic impurity removal process involving neutralization and hydrolysis, iron powder replacement, oxidation precipitation, and activated carbon adsorption. This process achieves efficient separation of impurity removal and copper retention, ensuring not only the purity of copper powder (≥99.5%) but also eliminating the impact of impurities such as As, Cd, and Pb on the subsequent reduction powdering process and the quality of copper powder products, thereby improving the stability of the preparation process.

[0009] 2. This technical solution uses a complexing agent to control the nucleation rate. The complexing agent can react with Cu2+ Formation of complexes reduces free Cu 2+ Concentration increases the nucleation energy barrier, thus inducing homogeneous nucleation rather than explosive nucleation. Specific functional groups of morphology modifiers are selectively adsorbed onto different crystal faces of copper crystals, ultimately inducing the formation of specific morphologies. The selected dispersant prevents the aggregation of already formed copper particles through steric hindrance and electrostatic repulsion, resulting in a narrower particle size distribution. A synergistic regulatory strategy for controlling nucleation rate, preventing aggregation, and inducing crystal facet growth was successfully constructed.

[0010] 3. This technical solution optimizes the method of adding the reducing agent. By slowly adding the reducing agent dropwise, the reaction system is kept in a low supersaturation region, which is more conducive to homogeneous nucleation. When Cu in the reaction system... 2+ As the concentration decreases due to consumption, and the supersaturation falls below the critical value, nucleation terminates and the process shifts to growth only, which is more conducive to the formation of monodisperse particles. By matching parameters such as the type of reducing agent, reaction temperature, and stirring intensity, controllable preparation of copper powder particle size and morphology can be achieved. In addition, the liquid-phase dispersion reduction method for preparing copper powder has relatively mild process conditions and lower equipment requirements, making it suitable for integration with wet treatment processes for copper smelting dust.

[0011] 4. The antioxidants selected in this technical solution, such as benzotriazoles, fatty acids, and ascorbic acids, provide excellent protection for copper powder based on coordination film formation, hydrophobic coating, and reduction protection mechanisms, respectively. Under low-oxygen conditions, a continuous oxide film will not form on the surface of the copper powder. Through the dual protection mechanism of chemical coating and low-oxygen drying, the oxidation stability problem of copper powder during storage and application is solved, enabling the product to meet the long-term stability requirements of conductive pastes.

[0012] 5. This technical solution uses copper back-extraction solution obtained from copper smelting dust leaching-extraction-back-extraction as raw material to prepare copper powder for conductive paste. Unlike traditional methods that use commercial copper sulfate or electrolytic copper solutions as raw materials, this solution achieves a direct conversion from solution to powder, undergoing only one solid-phase precipitation step, shortening the process flow and reducing energy consumption. It transforms copper resources from conventional recycled products into functional powders for conductive paste, expanding the resource utilization pathway for copper smelting dust and increasing product added value and market application potential. Attached Figure Description

[0013] Figure 1 The results are the particle size test results of the copper powder prepared in Example 1; Figure 2 Here is an SEM image of the copper powder prepared in Example 1; Figure 3 These are the particle size test results of the copper powder prepared in Example 2; Figure 4 Here is an SEM image of the copper powder prepared in Example 2; Figure 5 The results are the particle size test results of the copper powder prepared in Example 3; Figure 6 This is an SEM image of the copper powder prepared in Example 3. Detailed Implementation

[0014] The present invention will be further described below, but this is not intended to limit the invention in any way. Any modifications or substitutions made based on the teachings of the present invention shall fall within the scope of protection of the present invention.

[0015] The method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid according to the present invention includes the following steps: Purification and impurity removal of back-extraction solution: The back-extraction solution is clarified, filtered, and de-oiled to remove suspended solids, entrained organic phases, and impurities. Then, it is purified to remove impurity elements other than copper, resulting in a purified back-extraction solution.

[0016] Control of the reduction precursor solution system: Adjust the copper concentration of the purified back-extraction solution to 50~100g / L and the pH value to 2~12; add one or more of the complexing agent, buffer, and crystal nucleation regulator at 0.1~2.0 times the molar amount of copper ions to control the copper ion reduction rate and copper crystal nucleation process, avoiding instantaneous reduction that leads to coarse particles or agglomeration. Then add dispersant and morphology regulator to reduce the agglomeration between copper powder particles, improve the dispersibility of copper powder, and control the growth direction and particle morphology of copper crystal nuclei. The amount of dispersant and morphology regulator added is 0.1~5.0% of the copper mass to obtain the reduction precursor solution after system control.

[0017] Liquid-phase dispersion reduction: Under stirring conditions, a reducing agent is added to the pre-reduction solution after system conditioning, according to 1.0 to 2.5 times the theoretical molar amount required to completely reduce copper ions to metallic copper. The reaction is carried out at 30 to 90°C for 0.5 to 4 hours to gradually reduce copper ions to generate metallic copper powder. Solid-liquid separation is performed to obtain wet copper powder and reduced solution.

[0018] This process controls the method and speed of adding the reducing agent, the reaction temperature, the stirring intensity, the amount of dispersant, and the reaction time to obtain copper powder with narrow particle size distribution, regular morphology, and good dispersibility.

[0019] Surface anti-oxidation treatment: Wash the wet copper powder sequentially with deionized water, ethanol or other suitable washing media to remove residual soluble salts, reducing agent decomposition products, dispersants and organic impurities. During the washing process, the copper powder should be kept away from the air for a long time to reduce the risk of oxidation. Add an anti-oxidation treatment reagent at 0.1 to 0.5% of the copper powder mass and perform surface anti-oxidation treatment on the washed wet copper powder at 20 to 70°C for 10 to 50 minutes to form a thin protective layer on the surface of the copper powder. Then dry the copper powder under conditions of oxygen concentration <5%.

[0020] Copper powder post-processing: The dried copper powder is broken up, sieved, and classified to remove agglomerated particles and obtain the target copper powder.

[0021] The purification and impurity removal process employs one or a combination of several of the following: pH adjustment precipitation, sulfide precipitation, oxidation precipitation, displacement impurity removal, adsorption impurity removal, and complexation impurity removal.

[0022] The copper concentration adjustment of the back-extraction solution is achieved by one or a combination of concentration, dilution, and addition of copper salt solution.

[0023] The pH value is adjusted to a range suitable for the selected reducing agent: if the reducing agent is ascorbic acid, the pH is 3-8; if it is hypophosphite, the pH is 2-5; if it is glucose, the pH is 10-12.

[0024] The dispersant is selected from one or a combination of several of the following: polyvinylpyrrolidone, polyethylene glycol, gelatin, gum arabic, polyacrylate, dodecylbenzene sulfonate, and citrate.

[0025] The morphology modifier is selected from one or a combination of several of citrate, tartrate, ethylenediaminetetraacetic acid, and aminocarboxylate, or other additives that can regulate the complexation state of copper ions and crystal growth behavior.

[0026] The stirring speed is 200–1000 r / min.

[0027] The reducing agent is selected from any one or a combination of several of ascorbic acid, glucose, hypophosphite, and formaldehyde-based reducing agents, or other reducing agents suitable for the liquid-phase reduction of copper ions. Preferably, it is selected from any one of ascorbic acid, glucose, or hypophosphite.

[0028] The reducing agent is added in one go, in batches, or by dropping, with batch or dropping being preferred. The addition method should ensure that the temperature fluctuation of the reaction system is ≤±5℃ in order to control the reduction reaction rate and promote the uniform generation of copper crystal nuclei and uniform growth of particles.

[0029] The solid-liquid separation is performed using any one of centrifugal separation, pressure filtration, or vacuum filtration.

[0030] The antioxidant treatment is one or a combination of several of the following: organic protective agent coating, weak reducing atmosphere protection, antioxidant impregnation, surface complexation protection, or inert atmosphere treatment.

[0031] The reagents used in the antioxidant treatment are selected from one or more of benzotriazoles, fatty acids, organic amines, ascorbic acid, or other protective agents that can inhibit the oxidation of copper powder surface.

[0032] The drying is carried out under vacuum, inert atmosphere, or low oxygen conditions, wherein the low oxygen conditions refer to an oxygen concentration ≤2%.

[0033] The drying temperature is 40–100°C.

[0034] The target copper powder has a copper content of ≥99.5%, a particle size D50 of 0.5-5μm, spherical or near-spherical particles, no hard agglomerates, and low content of impurities such as arsenic, cadmium, and lead, and is qualified for further evaluation as an electronic conductive paste or photovoltaic conductive paste.

[0035] Example 1

[0036] Purification and impurity removal of the back-extraction solution: The back-extraction solution is clarified, filtered, and deoiled to remove suspended solids, entrained organic phases, and impurities. At 30℃, the pH of the back-extraction solution system is adjusted to 3.5-4.0 with ammonia water, stirred for 1.0 h, and aged for 0.5 h to allow Fe... 3+ Al 3 + Sb 3+ After impurities have hydrolyzed and precipitated, filter. Add iron powder at 2.5 times the total molar amount of impurity elements As, Sb, and Bi, stir and react at 55℃ for 1.5 h, then filter. Add ferrous sulfate to bring the Fe / As molar ratio of the back-extraction solution to 2.0:1, and add theoretically oxidized As. 3+ Add 1.5 times the required amount of hydrogen peroxide and adjust the pH of the back-extraction solution system to 3.5-4.0 with ammonia. Stir and react at 65℃ for 2.0 h, then filter. Add 2% activated carbon powder according to the mass of the back-extraction solution system, stir and adsorb at 25℃ for 1.0 h, then filter. Remove impurities other than copper to obtain purified back-extraction solution.

[0037] Control of the reduction precursor solution system: The copper concentration of the purified back-extraction solution was adjusted to 75 g / L, and the pH value was adjusted to 5-6 with ammonia. EDTA was added at 0.5 times the molar amount of copper ions, and the pH value of the system was maintained at 5-6 with ammonia. Then, the dispersant polyvinylpyrrolidone and the morphology control agent sodium citrate were added. The amount of dispersant added was 1.5% of the copper mass, and the amount of morphology control agent added was 2.0% of the copper mass, to obtain the reduced precursor solution after system control.

[0038] Liquid-phase dispersion reduction: Ascorbic acid (15% by mass) was added dropwise to the pre-reduction solution after system conditioning, according to 1.5 times the theoretical molar amount required to completely reduce copper ions to metallic copper. The stirring speed was set to 550 r / min, and the reaction was carried out at 70℃ for 1.5 h. After centrifugation, wet copper powder and reduced solution were obtained.

[0039] Surface anti-oxidation treatment: The wet copper powder was washed sequentially with deionized water and ethanol to remove residual soluble salts, reducing agent decomposition products, dispersants and organic impurities. Benzotriazole, an anti-oxidation reagent, was added at 0.3% of the copper powder mass. The wet copper powder was subjected to surface anti-oxidation treatment at 60°C. Specifically, benzotriazole was dissolved in anhydrous ethanol to prepare a solution, which was then mixed with the wet copper powder and impregnated for 20 minutes to form a thin protective layer on the surface of the copper powder. The copper powder was then dried under vacuum at 55°C.

[0040] Copper powder post-processing: The dried copper powder is broken up, sieved, and classified to remove agglomerated particles and obtain the target copper powder.

[0041] The obtained copper powder was tested for copper content, particle size distribution, specific surface area, tap density, morphology, sphericity, dispersibility, and electrical conductivity. The test results for the copper powder indicators are shown in Table 1, and the particle size test results are shown in... Figure 1 As shown in the figure, the SEM observation results of copper powder are as follows: Figure 2 As shown.

[0042] Table 1 Test Results of Copper Powder Properties

[0043] Example 2

[0044] Purification and removal of back-extraction solution: The back-extraction solution is purified and removed using the same process as in Example 1 to remove suspended solids, entrained organic phases and impurities, and remove impurity elements other than copper to obtain purified back-extraction solution.

[0045] Control of the reduction precursor solution system: The copper concentration of the purified back-extraction solution was adjusted to 80 g / L, and the pH value was adjusted to 11-11.5 with sodium hydroxide. Ethylenediamine was added at 1.5 times the molar amount of copper ions, and the pH value was adjusted and maintained constant with ammonia. Then, polyethylene glycol (PEG) and disodium ethylenediaminetetraacetate (EDTA) were added as dispersant (0.5% of the copper mass) and morphology modifier (1.0% of the copper mass) to obtain the controlled reduction precursor solution.

[0046] Liquid-phase dispersion reduction: According to 2.0 times the theoretical molar amount required to completely reduce copper ions to metallic copper, glucose (mass concentration 25%) was added dropwise to the pre-reduction solution after system conditioning. The stirring speed was set to 700 r / min, and the reaction was carried out at 80℃ for 2.0 h. After vacuum filtration, wet copper powder and reduced solution were obtained.

[0047] Surface anti-oxidation treatment: The wet copper powder was washed sequentially with deionized water and ethanol to remove residual soluble salts, reducing agent decomposition products, dispersants and organic impurities. Oleic acid, an anti-oxidation reagent, was added at 0.2% of the copper powder mass. The wet copper powder was subjected to surface anti-oxidation treatment at 55℃. Specifically, oleic acid and wet copper powder were mixed in ethanol and ultrasonically dispersed for 15 minutes to form a thin protective layer on the surface of the copper powder. The copper powder was then dried at 50℃ under an inert atmosphere.

[0048] Copper powder post-treatment: Same as in Example 1.

[0049] The obtained copper powder was tested, and the indicators were the same as in Example 1. The test results of the copper powder indicators are shown in Table 2, and the test results of the copper powder particle size are shown in Table 2. Figure 3 As shown in the figure, the SEM observation results of copper powder are as follows: Figure 4 As shown.

[0050] Table 2 Test Results of Copper Powder Properties

[0051] Example 3

[0052] Purification and removal of back-extraction solution: The back-extraction solution is purified and removed using the same process as in Example 1 to remove suspended solids, entrained organic phases and impurities, and remove impurity elements other than copper to obtain purified back-extraction solution.

[0053] Control of the reduction precursor solution system: Adjust the copper concentration of the purified back-extraction solution to 70 g / L and the pH value to 3-4; add sodium citrate at 1.0 times the molar amount of copper ions, then add dispersant gelatin and morphology modifier potassium sodium tartrate. The amount of dispersant added is 1.0% of the copper mass, and the amount of morphology modifier added is 1.5% of the copper mass, to obtain the reduced precursor solution after system control.

[0054] Liquid-phase dispersion reduction: According to 1.8 times the theoretical molar amount required to completely reduce copper ions to metallic copper, hypophosphite was added dropwise to the pre-reduction solution after system conditioning. The stirring speed was set to 550 r / min, and the reaction was carried out at 65℃ for 2.0 h. After pressure filtration, wet copper powder and reduced solution were obtained.

[0055] Surface anti-oxidation treatment: The wet copper powder is washed sequentially with deionized water and ethanol to remove residual soluble salts, reducing agent decomposition products, dispersants and organic impurities. Ascorbic acid, an antioxidant, is added at 0.3% of the copper powder mass. The wet copper powder is then subjected to surface anti-oxidation treatment at 30°C. Specifically, ascorbic acid is dissolved in deionized water, added to the wet copper powder and stirred for 25 minutes to form a thin protective layer on the surface of the copper powder. The copper powder is then dried under vacuum at 55°C.

[0056] Copper powder post-treatment: Same as in Example 1.

[0057] The obtained copper powder was tested, and the indicators were the same as in Example 1. The test results of the copper powder indicators are shown in Table 3, and the test results of the copper powder particle size are shown in Table 3. Figure 5 As shown in the figure, the SEM observation results of copper powder are as follows: Figure 6 As shown.

[0058] Table 3 Test Results of Copper Powder Properties

Claims

1. A method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid, characterized in that, The process includes the following steps: Purification and impurity removal of back-extraction solution: The back-extraction solution is clarified, filtered, and de-oiled to remove suspended solids, entrained organic phases, and impurities. Then, it is purified to remove impurity elements other than copper, resulting in purified back-extraction solution. Control of the reduction precursor solution system: Adjust the copper concentration of the purified back-extraction solution to 50~100g / L and the pH value to 2~12; add one or more of the complexing agent, buffer, and crystal nucleation regulator at 0.1~2.0 times the molar amount of copper ions to control the copper ion reduction rate and copper crystal nucleus formation process. Then add the dispersant and morphology regulator to control the growth direction and particle morphology of copper crystal nuclei. The amount of dispersant and morphology regulator added is 0.1~5.0% of the copper mass, and the amount of morphology regulator added is 0.1~5.0% of the copper mass, to obtain the reduction precursor solution after system control. Liquid-phase dispersion reduction: Under stirring conditions, a reducing agent is added to the pre-reduction solution after system conditioning, according to 1.0 to 2.5 times the theoretical molar amount required to completely reduce copper ions to metallic copper. The reaction is carried out at 30 to 90°C for 0.5 to 4 hours to reduce copper ions to generate metallic copper powder. Solid-liquid separation is performed to obtain wet copper powder and reduced solution. Surface anti-oxidation treatment: Wash the wet copper powder to remove residual impurities, add an anti-oxidation treatment reagent at 0.1 ~ 0.5% of the copper powder mass, and perform surface anti-oxidation treatment on the washed wet copper powder at 20 ~ 70℃ for 10 ~ 50 min to form a thin protective layer on the surface of the copper powder. Then dry the copper powder under conditions of oxygen concentration < 5%. Copper powder post-processing: The dried copper powder is classified to obtain the target copper powder.

2. The method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid according to claim 1, characterized in that, The purification process employs one or a combination of several of the following methods: pH adjustment precipitation, sulfide precipitation, oxidation precipitation, displacement purification, adsorption purification, and complexation purification.

3. The method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid according to claim 1, characterized in that, The pH value is adjusted to a range suitable for the selected reducing agent: if the reducing agent is ascorbic acid, the pH is 3-8; if it is hypophosphite, the pH is 2-5; if it is glucose, the pH is 10-12.

4. The method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid according to claim 1, characterized in that, The dispersant is selected from one or a combination of several of the following: polyvinylpyrrolidone, polyethylene glycol, gelatin, gum arabic, polyacrylate, dodecylbenzene sulfonate, and citrate.

5. The method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid according to claim 1, characterized in that, The morphology modifier is selected from one or a combination of several of citrate, tartrate, ethylenediaminetetraacetic acid, and aminocarboxylate.

6. The method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid according to claim 1, characterized in that, The reducing agent is selected from any one of ascorbic acid, glucose, or hypophosphite.

7. The method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid according to claim 1, characterized in that, The reducing agent is added in batches or dropwise, and the method of addition must ensure that the temperature fluctuation of the reaction system is ≤±5℃.

8. The method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid according to claim 1, characterized in that, The antioxidant treatment is one or a combination of several of the following: organic protective agent coating, weak reducing atmosphere protection, antioxidant impregnation, surface complexation protection, or inert atmosphere treatment.

9. The method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid according to claim 1 or 8, characterized in that, The reagents used in the antioxidant treatment are selected from one or a combination of several of the following: benzotriazoles, fatty acids, organic amines, and ascorbic acids.

10. The method for preparing copper powder for conductive paste using copper smelting flue dust back-extraction liquid according to claim 1, characterized in that, The drying temperature is 40–100°C.

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