Energy-saving method for manufacturing superfine and ultralight electrolytic copper powder

Abstract

The invention discloses an energy-saving method for manufacturing superfine and ultralight electrolytic copper powder, which comprises the following steps: S1, mixing choline chloride and ethylene glycol according to a certain molar ratio at 25-45 DEG C for more than 12 hours to obtain colorless, transparent and uniform organic liquid as an additive; s2, stirring and adding an additive into the binary electrolyte of copper sulfate and sulfuric acid at 25-45 DEG C to completely dissolve the additive to obtain an electrolyte; s3, electrolyzing the electrolyte by adopting a constant current, wherein the electrolysis time is 5-30 minutes; and S4, separating and extracting the copper powder from the polar plate in a vacuum or inert gas environment, cleaning the copper powder for 2-3 times by using deoxidized deionized water at 50-60 DEG C, carrying out antioxidant treatment, cleaning the copper powder for 2-3 times by using deoxidized deionized water, and finally carrying out vacuum drying to obtain the superfine dendritic copper powder. The method has the effects that the current efficiency can be improved by 15-20%, the energy consumption is reduced by 400-700 kilowatt-hour / ton, the purity of the copper powder exceeds 99.9%, and very low apparent density, narrow particle size distribution and developed dendritic crystal with a dendritic structure are shown.

Description

Technical Field

[0001] The present invention relates to the technology for preparing electrolytic copper powder, and particularly to a method for energy-saving manufacturing of ultrafine and ultra-light electrolytic copper powder. Background Art

[0002] With the development of miniaturized and lightweight electronic devices and high-performance friction materials, the demand for ultrafine and ultra-light dendritic copper powder (particle size less than 10 microns, apparent density less than 1.0 g / cm³) has been continuously increasing. Such copper powder plays an irreplaceable and important role in self-lubricating bearings, electro-carbon products, and copper-based composites, and its particle size, morphology, and density directly affect the mechanical strength, thermal conductivity, and formability of the end products. Currently, industrial copper powder is mainly prepared by three methods: electrolysis, atomization, and chemical reduction. The copper powder obtained by the atomization method is mostly spherical or teardrop-shaped, with a high apparent density (>2.5 g / cm³), small sintering contact area, poor compressibility, high equipment investment, and difficult gas treatment; the chemical reduction method is suitable for the preparation of some ultrafine powders, but there are problems of insufficient powder purity and batch stability; the electrolysis method has become the only effective process for industrially preparing low-density dendritic copper powder at present because the copper powder produced by it has a dendritic morphology, low apparent density, high purity, and good compressibility. However, for the traditional electrolytic copper powder process to obtain an apparent density of <1.0 g / cm³, extreme parameter conditions of high current density (>1500 A / m²) and low copper ion concentration (<5 g / L) must be used. Although this process can form a well-developed dendritic structure, it brings three problems. One is high energy consumption, with the power consumption per ton of copper powder as high as over 2000 kWh / ton, and more than 30% of the energy is consumed in the hydrogen evolution side reaction; the second is severe concentration polarization, with the copper ion concentration difference Δ[Cu²⁺] between the anode and the cathode exceeding 8 g / L, resulting in coarsening of crystal grains (>20 microns) and a decrease in the structural uniformity of the copper powder; the third is prominent hydrogen embrittlement, with the hydrogen evolution reaction causing an increase in the residual hydrogen content in the copper powder (>200 ppm), which affects the mechanical properties. The improvement attempts in the industry include:

[0003] (1) Low current density process (<800 A / m²): The energy consumption can be reduced to 1500 - 1700 kWh / ton, but it causes insufficient dendritic growth, coarsening of crystal grains (>30 microns), and an increase in apparent density to >1.5 g / cm³;

[0004] (2) Organic additive method: Additives such as polyvinylpyrrolidone can refine crystal grains, but it is difficult to obtain dendritic copper powder with an apparent density less than 1.0 g / cm³, and it will also cause a decrease in the purity of the copper powder (<99.5%);

[0005] (3) Methods such as pulse electrolysis and rotating electrodes: There are problems such as complex equipment, high energy consumption, high cost, and unstable process, which limit large-scale industrial applications.

[0006] Therefore, the current process falls into a technical paradox: to obtain ultrafine and ultra-light copper powder, a high energy consumption cost must be paid; if energy conservation and consumption reduction are pursued, an ideal fractal structure and grain size cannot be obtained.

[0007] The present invention provides an energy-saving preparation method based on an electrolysis system assisted by a choline chloride-ethylene glycol eutectic solvent additive. By regulating the electrochemical deposition microenvironment, grain refinement of copper powder, significant reduction of the loose bulk density, and control of side reactions are achieved under medium and low current densities (700 - 1100 A / m²), and the energy efficiency ratio is greatly improved. Summary of the Invention

[0008] Aiming at the problems of high energy consumption, high loose bulk density, and difficulty in meeting the application requirements of high-end materials in the preparation of copper powder by the electrolysis method in the prior art, the present invention provides a method for energy-saving manufacturing of ultrafine and ultra-light electrolytic copper powder. By reasonably designing the electrolyte composition and electrolysis process, the energy consumption of copper powder can be significantly reduced, and ultrafine copper powder with small particle size, low loose bulk density, and uniform morphology can be prepared, meeting the strict requirements of high-end materials for the performance of copper powder.

[0009] To solve the above technical problems, the technical solution provided by the present invention is as follows:

[0010] A method for energy-saving manufacturing of ultrafine and ultra-light electrolytic copper powder, comprising the following steps:

[0011] S1: Mix choline chloride and ethylene glycol at a certain molar ratio at 25°C - 45°C for more than 12 hours to obtain a colorless, transparent, and homogeneous organic liquid as an additive;

[0012] S2: Stir and add the additive obtained in step S1 to a binary electrolyte of copper sulfate and sulfuric acid at 25°C - 45°C until it is completely dissolved to obtain an electrolyte;

[0013] S3: Electrolyze the electrolyte obtained in step S2 by constant current, and the electrolysis time is 5 - 30 minutes;

[0014] S4: Separate and extract the copper powder from the electrode plate in a vacuum or inert gas environment, wash it 2 - 3 times with deoxygenated deionized water at 90°C - 100°C, then perform an antioxidant treatment, and then wash it 2 - 3 times with deoxygenated deionized water at 90°C - 100°C again, and finally dry it in vacuum to obtain ultrafine dendritic copper powder.

[0015] Optionally, the molar ratio of choline chloride to ethylene glycol in step S1 is 1:2.

[0016] Optionally, the concentration of the additive in the electrolyte obtained in step S2 is 0.5 to 2.0 g / L. When the additive concentration in the electrolyte is lower than 0.5 g / L, the electrolytic copper powder does not have very obvious dendritic dendrites and is cauliflower-shaped, resulting in an increase in the loose bulk density of the copper powder, uneven particle size distribution, a decrease in current efficiency, and an increase in energy consumption. When the additive concentration in the electrolyte is higher than 2 g / L, the morphology of the electrolytic copper powder is fine and irregular crystals. Therefore, an appropriate additive concentration is more beneficial for the electrolytic copper powder to have an extremely obvious and developed dendritic dendrite structure.

[0017] Optionally, the mass ratio of copper sulfate pentahydrate, sulfuric acid, and the additive in the electrolyte obtained in step S2 is (16 - 24):(120 - 160):(0.5 - 2).

[0018] Optionally, during electrolysis in step S3, pure copper plates are used as the anode and cathode, the electrode distance is 2 - 5 cm, the electrolyte temperature is 320 - 340 K, and the current density is 700 - 1100 A / m².

[0019] Optionally, in step S4, washing with absolute ethanol 2 - 3 times is used as the antioxidant treatment.

[0020] Optionally, in step S4, antioxidant treatment is carried out by placing it in a benzotriazole solution.

[0021] In addition, the present invention also provides a kind of copper powder, which is prepared by the method for energy-saving manufacturing of ultrafine and ultra-light electrolytic copper powder described above. The loose bulk density of the copper powder is 0.30 - 0.40 g / cm³, the particle size is 6 - 9 μm, the current efficiency during the preparation process is 65 - 91%, and the energy consumption is 800 - 1000 kWh / ton.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. Energy-saving and highly efficient: By adding an additive formed by mixing choline chloride and ethylene glycol in the electrolyte, the formation of dendritic dendrites is effectively promoted, enabling the electrolysis process to be carried out at a lower current density, thereby significantly reducing energy consumption while ensuring the dendritic morphology of the copper powder.

[0024] 2. Superior performance: The copper powder prepared by the present invention has a very obvious and developed dendritic dendrite structure, with clear crystal arms and edges of the branches and leaves, and uniform particle size distribution. Its average particle size D50 is 8.5 μm, and the loose bulk density is as low as 0.30 - 0.40 g / cm³, meeting the requirements for high-end materials.

[0025] 3. Simple process and easy for industrial application: The preparation method of the present invention is easy to operate, and the additive used is an organic substance that is green, environmentally friendly, safe, and low-cost, suitable for large-scale industrial production.

[0026] 4. Excellent morphology and performance: Compared with the copper powder prepared by the traditional electrolysis method, using the additives and electrolysis process of the present invention, the obtained copper powder has a smaller particle size, a lower apparent density, and a more developed dendritic morphology. The branches are well-developed, with a uniform size distribution. The crystal arms and edges of the primary dendrites (trunks) and secondary dendrites (branches and leaves) are well-developed, significantly improving the application performance of the copper powder.

[0027] Through the above technical solutions, the present invention provides an innovative method to effectively solve the problems of energy consumption and apparent density of copper powder, which can meet the strict requirements of high-end materials for the performance of copper powder and provide a feasible technical path for the industrial production of high-performance copper powder. Description of the Drawings

[0028] Figure 1 It is a morphology diagram of the copper powder prepared in Example 1 of the present invention.

[0029] Figure 2 It is a morphology diagram of the copper powder prepared in Example 2 of the present invention.

[0030] Figure 3 It is a morphology diagram of the copper powder prepared in Example 3 of the present invention.

[0031] Figure 4 It is a morphology diagram of the copper powder prepared in Comparative Example 1.

[0032] Figure 5 It is a morphology diagram of the copper powder prepared in Comparative Example 2.

[0033] Figure 6 It is a morphology diagram of the copper powder prepared in Comparative Example 3.

[0034] Figure 7 It is a morphology diagram of the copper powder prepared in Comparative Example 4. Detailed Embodiments

[0035] The embodiments of the present invention provide a method for energy-saving manufacturing of ultrafine and ultra-light electrolytic copper powder, including the following steps:

[0036] Example 1

[0037] S1: Mix choline chloride and ethylene glycol at a molar ratio of 1:2 at 25°C to 45°C for more than 12 hours to obtain a colorless, transparent, and homogeneous organic liquid, denoted as additive X;

[0038] S2: Dissolve additive X, CuSO4·5H2O, and H2SO4 in deionized water to obtain an electrolyte solution containing 0.5 g / L of the additive, and the mass ratio of copper sulfate pentahydrate, sulfuric acid, and additive X in the electrolyte solution is 24:130:0.5;

[0039] S3: Place the electrolyte in an electrolytic cell for electrolysis. Use pure copper plates as the anode and cathode, control the anode-cathode distance at 3 cm, the electrolysis time at 10 minutes, the electrolyte temperature at 323 K, and the current density at 1100 A / m².

[0040] S4: After the electrolysis is completed, collect the copper powder deposited on the cathode, wash it 3 times with hot deionized water, then perform antioxidant coating in a benzotriazole solution, wash it 2 more times with deionized water, then take it out after natural filtration and dehydration, and vacuum dry it at 45 °C for 12 hours to obtain electrolytic copper powder.

[0041] The morphology of the obtained copper powder is as Figure 1 shown. The average particle size D50 of this copper powder is 8.23 μm. The purity of the copper powder detected by ICP (the same below) is 99.9%, the apparent density is 0.39 g / cm³, the current efficiency is 80%, and the energy consumption is 956 kWh / ton.

[0042] Example 2

[0043] S1: Mix choline chloride and ethylene glycol at a molar ratio of 1:2 at 25 °C to 45 °C for more than 12 hours, denoted as additive X.

[0044] S2: Dissolve additive X, CuSO4·5H2O, and H2SO4 in deionized water to obtain an electrolyte containing 1.0 g / L of the additive, and make the mass ratio of copper sulfate pentahydrate, sulfuric acid, and the additive in the electrolyte 20:150:1.

[0045] S3: Place the electrolyte in an electrolytic cell for electrolysis. Use pure copper plates as the anode and cathode, control the anode-cathode distance at 3 cm, the electrolysis time at 10 minutes, the electrolyte temperature at 323 K, and the current density at 1000 A / m².

[0046] S4: After the electrolysis is completed, collect the copper powder deposited on the cathode, wash it 3 times with hot deionized water, then perform antioxidant coating in a benzotriazole solution, wash it 2 more times with deionized water, then take it out after natural filtration and dehydration, and vacuum dry it at 45 °C for 12 hours to obtain electrolytic copper powder.

[0047] The morphology of the obtained copper powder is as Figure 2 shown. The average particle size D50 of this copper powder is 7.75 μm. The purity of the copper powder detected by ICP is 99.9%, the apparent density is 0.36 g / cm³, the current efficiency is 83%, and the energy consumption is 851 kWh / ton.

[0048] Example 3

[0049] S1: Mix choline chloride and ethylene glycol at a molar ratio of 1:2, denoted as additive X.

[0050] S2: Dissolve additive X, CuSO4·5H2O, and H2SO4 in deionized water to obtain an electrolyte solution containing 2.0 g / L of the additive. The mass ratio of copper sulfate pentahydrate, sulfuric acid, and the additive in the electrolyte solution is 20:150:2.

[0051] S3: Place the electrolyte solution in an electrolytic cell for electrolysis. Use pure copper plates as the anode and cathode, control the distance between the anode and cathode at 3 cm, the electrolysis time at 10 minutes, the electrolyte temperature at 323 K, and the current density at 1000 A / m².

[0052] S4: After the electrolysis is completed, collect the copper powder deposited on the cathode, wash it 3 times with hot deionized water, then perform antioxidant coating in a benzotriazole solution, wash it 2 more times with deionized water, naturally filter and dehydrate it, take it out, and vacuum dry it at 45°C for 12 hours to obtain electrolytic copper powder.

[0053] The morphology of the obtained copper powder is as Figure 3 shown. The average particle size D50 of this copper powder is 7.24 μm, the purity of the copper powder detected by ICP is 99.9%, the loose bulk density is 0.38 g / cm³, the current efficiency is 85%, and the energy consumption is 900 kWh / ton.

[0054] Comparative Example 1

[0055] S1: Mix choline chloride and ethylene glycol in a molar ratio of 1:2 and label it as additive X.

[0056] S2: Dissolve additive X, CuSO4·5H2O, and H2SO4 in deionized water to obtain an electrolyte solution containing 4.0 g / L of the additive. The mass ratio of copper sulfate pentahydrate, sulfuric acid, and the additive in the electrolyte solution is 20:150:4.

[0057] S3: Place the electrolyte solution in an electrolytic cell for electrolysis. Use pure copper plates as the anode and cathode, control the distance between the anode and cathode at 3 cm, the electrolysis time at 10 minutes, the electrolyte temperature at 323 K, and the current density at 1000 A / m².

[0058] S4: After the electrolysis is completed, collect the copper powder deposited on the cathode, wash it 3 times with hot deionized water, then perform antioxidant coating in a benzotriazole solution, wash it 2 more times with deionized water, naturally filter and dehydrate it, take it out, and vacuum dry it at 45°C for 12 hours to obtain electrolytic copper powder.

[0059] The morphology of the obtained copper powder is as Figure 4 shown. The average particle size D50 of this copper powder is 6.85 μm, the purity of the copper powder detected by ICP is 99.9%, the loose bulk density is 0.52 g / cm³, the current efficiency is 80%, and the energy consumption is 1050 kWh / ton.

[0060] Comparative Example 2

[0061] Dissolve CuSO4·5H2O and H2SO4 in deionized water to obtain an electrolyte without additives. Place the electrolyte in an electrolytic cell for electrolysis. Use pure copper plates as the anode and cathode, control the anode-cathode distance at 3 cm, the electrolysis time at 10 minutes, the electrolyte temperature at 323 K, and the current density at 1200 A / m². After electrolysis, collect the copper powder deposited on the cathode, wash it 3 times with hot deionized water, then conduct antioxidant coating in a benzotriazole solution, wash it 2 more times with deionized water, take it out after natural filtration and dehydration, and vacuum dry it at 45 °C for 12 hours to obtain electrolytic copper powder.

[0062] The morphology of the obtained copper powder is as Figure 5 shown. The average particle size D50 of this copper powder is 27.4 μm, the purity of the copper powder detected by ICP is 99.9%, the apparent density is 0.53 g / cm³. The current efficiency is 64%, and the energy consumption is 1557 kWh / t.

[0063] Comparative Example 3

[0064] Dissolve choline chloride, CuSO4·5H2O, and H2SO4 in deionized water to obtain an electrolyte containing 1.0 g / L of choline chloride, and the mass ratio of copper sulfate pentahydrate, sulfuric acid, and choline chloride in the electrolyte is 20:150:1.

[0065] Place the electrolyte in an electrolytic cell for electrolysis. Use pure copper plates as the anode and cathode, control the anode-cathode distance at 3 cm, the electrolysis time at 10 minutes, the electrolyte temperature at 323 K, and the current density at 1000 A / m². After electrolysis, collect the copper powder deposited on the cathode, wash it 3 times with hot deionized water, then conduct antioxidant coating in a benzotriazole solution, wash it 2 more times with deionized water, take it out after natural filtration and dehydration, and vacuum dry it at 45 °C for 12 hours to obtain electrolytic copper powder.

[0066] The morphology of the obtained copper powder is as Figure 6 shown. The average particle size D50 of this copper powder is 7.25 μm, the purity of the copper powder detected by ICP is 99.9%, the apparent density is 0.46 g / cm³, the current efficiency is 77%, and the energy consumption is 1370 kWh / t.

[0067] Comparative Example 4

[0068] Dissolve ethylene glycol, CuSO4·5H2O, and H2SO4 in deionized water to obtain an electrolyte containing 1.0 g / L of ethylene glycol, and the mass ratio of copper sulfate pentahydrate, sulfuric acid, and ethylene glycol in the electrolyte is 20:150:1.

[0069] The electrolyte is placed in an electrolytic cell for electrolysis. Using pure copper plates as the anode and cathode, controlling the anode-cathode distance at 3 cm, the electrolysis time at 10 minutes, the electrolyte temperature at 323 K, and the current density at 800 A / m². After electrolysis, the copper powder deposited on the cathode is collected, washed 3 times with hot deionized water, then subjected to antioxidant coating in a benzotriazole solution, washed 2 more times with deionized water, and then taken out after natural filtration and dehydration, and vacuum dried at 45 °C for 12 hours to obtain electrolytic copper powder.

[0070] The morphology of the obtained copper powder is as Figure 7 shown. The average particle size D50 of this copper powder is 8.74 μm, the purity of the copper powder detected by ICP is 99.9%, the apparent density is 0.42 g / cm³, the current efficiency is 78%, and the energy consumption is 1456 kWh / t.

[0071] As can be seen from Examples 1 to 3, when the method provided by the present invention is adopted and the addition amount of additive X is controlled at 0.5 - 2 g / L, the prepared copper powder has an extremely obvious and developed dendritic structure, with well-developed branches and uniform size distribution. The crystal arms and edges of the primary dendrites (trunks) and secondary dendrites (branches) are well-developed. The average particle size D50 of this copper powder is less than 8.5 μm, its apparent density is less than 0.4 g / cm³, the current efficiency is controlled at 80 - 85%, and the energy consumption is less than 1000 kWh / t. In Comparative Example 1, the additive exceeds 2 g / L, so the prepared copper powder is in a fine and fragmented state and shows agglomeration. The average particle size D50 of this copper powder is 6.85 μm, and the apparent density is 0.52 g / cm³. In Comparative Example 2, there is no additive in the electrolyte. The average particle size D50 of the copper powder is 27.4 μm, the apparent density is 0.53 g / cm³, which is significantly larger than that in the examples, and the current efficiency decreases while the energy consumption increases. In Comparative Examples 3 - 4, only a single additive, choline chloride or ethylene glycol, is added, and the copper powder shows an indistinct and underdeveloped dendritic structure.

[0072] It can be seen that the copper powder prepared by the preparation method provided by the present invention has an extremely obvious and developed dendritic structure, with well-developed branches and uniform size distribution. The crystal arms and edges of the primary dendrites (trunks) and secondary dendrites (branches) are well-developed. The average particle size D50 of this copper powder is less than 8.5 μm, the apparent density is less than 0.4 g / cm³, the current efficiency exceeds 80%, and the energy consumption is less than 1000 kWh / t, which is significantly different from the cauliflower-like copper powder without additives.

[0073] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalent technologies, the present invention also intends to include these changes and modifications.

Claims

1. A method for energy-saving manufacturing of ultrafine and ultra-light electrolytic copper powder, characterized in that, It includes the following steps: S1: Mix choline chloride and ethylene glycol at a certain molar ratio at 25°C to 45°C for more than 12 hours to obtain a colorless, transparent and homogeneous organic liquid as additive X; S2: Stir and add additive X to the binary electrolyte of copper sulfate and sulfuric acid at 25°C to 45°C until it is completely dissolved to obtain an electrolyte added with additive X; S3: Electrolyze the electrolyte obtained in step S2 by constant current, and the electrolysis time is 5 to 30 minutes; S4: Separate and extract the copper powder from the electrode plate in a vacuum or inert gas environment, wash it 2 to 3 times with deoxygenated deionized water at 90°C to 100°C, then perform an antioxidant treatment, and then wash it 2 to 3 times with deoxygenated deionized water at 90°C to 100°C, and finally dry it in vacuum to obtain ultrafine dendritic copper powder.

2. The method for energy-saving production of superfine and ultra-light electrolytic copper powder according to claim 1, characterized in that In step S1, the molar ratio of choline chloride to ethylene glycol is 1:

2.

3. The method for energy-saving manufacturing of ultrafine and ultra-light electrolytic copper powder according to claim 1, characterized in that The concentration of the additive in the electrolyte obtained in step S2 is 0.5 to 2.0 g / L.

4. The method for energy-saving manufacturing of ultrafine and ultra-light electrolytic copper powder according to claim 1 or 2 or 3, characterized in that, The mass ratio of copper sulfate pentahydrate, sulfuric acid to the additive in the electrolyte obtained in step S2 is (16 to 24):(120 to 160):(0.5 to 2).

5. The method for energy-saving manufacturing of ultrafine and ultra-light electrolytic copper powder according to claim 4, characterized in that, During electrolysis in step S3, the current density is 700 to 1100 A / m², the pure copper plate is used as the anode and cathode, the electrode distance is 2 to 5 cm, and the electrolyte temperature is 320 to 340 K.

6. The method for energy-saving manufacturing of ultra-fine and ultra-light electrolytic copper powder according to claim 5, characterized in that: The apparent density of the copper powder is 0.30 to 0.40 g / cm³, the particle size is 6 to 9 μm, the current efficiency during the preparation process is 65 to 91%, and the energy consumption is 800 to 1000 kWh / t.

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