Vacuum distillation furnace and preparation method of high-purity copper particles

Abstract

This invention provides a vacuum distillation furnace and a method for preparing high-purity copper particles, relating to the field of high-purity metal preparation technology. Addressing the problem that traditional methods for producing high-purity copper particles in industrial production often fail to achieve ideal purity, resulting in high impurity content and complex composition, this invention utilizes vacuum distillation. During the vacuum distillation process, most of the valuable metals in the copper matrix volatilize into the gas phase and separate from the copper matrix, achieving a copper purity of 99.9991%, thus purifying the copper. The copper powder particles volatilized onto the condenser have a smooth surface and a purity of 5N or higher, suitable for applications such as catalyst doping, medical and chemical processing. This invention employs vacuum distillation to obtain high-purity copper condensate of 5N or higher, while simultaneously enriching and collecting copper powder particles. This method shortens the process flow, eliminates the need for waste liquid treatment, and is characterized by low cost and no pollution.

Description

Technical Field

[0001] This invention relates to the field of high-purity metal preparation technology, and in particular to a vacuum distillation furnace and a method for preparing high-purity copper particles. Background Technology

[0002] In existing industrial production, metallic copper maintains strong competitiveness in the metal materials market due to its excellent ductility, thermal conductivity, and electrical conductivity. High-purity copper refers to metallic copper with a purity of 99.999% (5N) or higher. Classified by purity, products mainly include grades such as 99.999% (5N), 99.9999% (6N), and 99.99999% (7N). Copper powder is typically fine copper particle powder with a particle size of less than 1μm. Its applications are very wide, commonly used in powder metallurgy, diamond tools, sealing materials, electrical copper powder thermal conductive materials, conductive materials, welding materials, superhard materials, friction materials, and pharmaceutical and chemical industries. With the rapid development of high-precision technology and other fields in recent years, the consumption of high-purity copper of different particle sizes is also increasing.

[0003] Currently, the main characteristics of various production methods for preparing high-purity copper powder are as follows:

[0004] (1) Electrolysis process: The process is simple and low-cost, but the requirements for the purification of the electrolyte produced after electrolysis are high, and a large amount of waste acid will be generated. Moreover, the traditional electrolysis process is difficult to achieve the purity required for metallic copper as a catalyst material. When processing copper raw materials containing multiple impurities, it is difficult to efficiently separate impurity elements, and the purity of the product is difficult to guarantee. For example, patent CN101011747A discloses a method for producing copper powder suitable for conductive paste by using electrolytic cuprous oxide as a starting material to manufacture copper powder with an average particle size of less than 1 micrometer, preferably less than 0.5 micrometers, and with uniform particle size at low cost. The method involves mixing cuprous oxide with a reducing agent in the presence of a protective colloid and in water with added water-soluble copper salt, or reducing water-soluble copper salt to form a slurry in water with a protective colloid, and then reducing cuprous oxide in the presence of the slurry. This patent successfully prepared copper powder with an average particle size of 0.3 micrometers, but the method requires a large amount of solution during operation.

[0005] (2) Atomization method: Generally, high-pressure gas, high-pressure liquid, or high-speed rotating blades are used to break down molten metal or alloys under high temperature and pressure into fine droplets, which are then condensed in a collector to obtain ultrafine metal powder. This process does not involve chemical changes and is commonly used in the production of metal powders such as Fe, Sn, Zn, Pb, and Cu. Atomized powder has advantages such as high sphericity, controllable powder particle size, low oxygen content, low production cost, and adaptability to the production of various metal powders. It has become the main development direction of high-performance and special alloy powder preparation technology. However, the atomization method has disadvantages such as low production efficiency, low yield of ultrafine powder, and relatively high energy consumption. For example, patent CN1286604C discloses a method for producing copper powder using water atomization. This method employs an annular nozzle for atomization, with a nozzle orifice diameter of 1.6–1.8 mm, a spray apex angle of 35–45 degrees, an atomizing water pressure of 12–19 MPa, a molten metal temperature of 1160–1200 °C, and a DPS ratio of 2.5–2.9 g / cm³. 3 The wet powder is dehydrated, reduced sintered, crushed, and sieved. This method can directly obtain copper powder with a low bulk ratio without drying and oxidation processes. However, there are certain operational risks in the process of preparing copper powder under high temperature and high pressure conditions, and the copper powder obtained still needs to undergo a sintering process, which can easily cause oxidation of the copper powder and reduce its purity.

[0006] (3) Vacuum distillation refining method: Vacuum distillation is carried out under reduced pressure and is generally used to separate substances that are easily decomposed when heated to the boiling point under normal pressure. Vacuum distillation is also used for the deep purification of certain special gases and is another common method for purifying high-purity metals. However, if you want to purify copper at the same time and prepare copper powder with the correct particle size, traditional equipment can only achieve the purpose of purification and cannot achieve granulation. Patent CN113897501A discloses a method for purifying metallic manganese by vacuum distillation. The method involves heating the raw manganese under vacuum conditions, collecting the distilled manganese vapor through a condenser, and then condensing it to obtain metallic manganese. This method can purify commercially available raw manganese to a purity of 4N~5N, with a total impurity content of <50ppm and a total gaseous element impurity content of <100ppm. It also reduces the number of non-metallic insoluble inclusions with a particle size >1.3μm per gram of metallic manganese to <5000, meeting the requirements for semiconductor target materials. Furthermore, it has advantages such as simple process, low energy consumption, and minimal environmental pollution. However, this method, while purifying metals through vacuum distillation, only achieves purification and cannot yield usable metal particles. Summary of the Invention

[0007] The purpose of this invention is to provide a vacuum distillation furnace and a method for preparing high-purity copper particles. This invention can directly obtain high-purity copper particles with a particle size of 1~100μm or higher (5N grade or above). Furthermore, this invention shortens the process flow, eliminates the need for waste liquid treatment, and features low cost and no pollution.

[0008] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0009] The present invention provides a vacuum distillation furnace, wherein a evaporation perforation plate is provided between the condensation plate and the evaporation chamber; the pore diameter of the evaporation perforation plate is 1~10mm.

[0010] Preferably, the porosity of the volatile plate is 0.138% to 13.80%.

[0011] Preferably, the evaporation plate is in the shape of a conical disk.

[0012] Preferably, the evaporation plate is a chromium plate.

[0013] This invention provides a method for preparing high-purity copper particles, comprising the following steps: placing metallic copper raw material in the evaporation chamber of the vacuum distillation furnace described above, performing vacuum distillation, and obtaining high-purity copper particles in the condenser; the vacuum degree of the vacuum distillation is 0.1~100 Pa, the temperature of the vacuum distillation is 1100~1800℃, and the particle size of the high-purity copper particles is 1~100 μm.

[0014] Preferably, the vacuum distillation time is 0.5 to 3 hours.

[0015] Preferably, the rate of heating to the temperature of the vacuum distillation is 5~20℃ / min.

[0016] Preferably, the copper raw material includes electrolytic cathode copper.

[0017] The present invention provides a vacuum distillation furnace, wherein a evaporation perforation plate is provided between the condensation plate and the evaporation chamber; the pore diameter of the evaporation perforation plate is 1~10mm.

[0018] According to the principle of gas atomization, the higher the compressed gas pressure and the greater the flow rate, the greater the amount of mist released per unit time, and thus the smaller the particles. With the addition of an orifice plate, compared to a system without an orifice plate, the gas flow rate is greater at high temperatures as the gas passage narrows, resulting in smaller particles and a higher powder yield. This invention utilizes the aforementioned vacuum distillation furnace, which simultaneously purifies copper and achieves granulation, obtaining copper powder particles of the desired size.

[0019] This invention addresses the problem that traditional methods used in the industrial production of high-purity copper particles often fail to achieve the desired purity, resulting in high impurity content and complex composition. By utilizing vacuum distillation, most of the valuable metals in the copper matrix volatilize into the gas phase and separate from the copper matrix during the vacuum distillation process, achieving a copper purity of 99.9991%. This purification of copper is achieved, and the copper powder particles volatilized onto the condenser have a smooth surface and a purity of over 5N, making them suitable for applications such as catalyst doping, medical and chemical industries.

[0020] This invention uses vacuum distillation to obtain high-purity copper condensate of grade 5N or higher, while simultaneously enriching and collecting copper powder particles. This method shortens the process flow, eliminates the need for waste liquid treatment, and features low cost and no pollution. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the structure of the vacuum distillation furnace of the present invention, wherein: 1-sealing ring; 2-handle; 3-sealing screw; 4-furnace cover; 5-furnace shell; 6-evacuation port; 7-crucible; 8-heating element; 9-thermocouple; 10-insulating cotton; 11-electrode; 12-graphite felt; 13-water inlet and cooling water; 14-protective shell; 15-evaporation plate; 16-condensation plate; 17-gas cylinder;

[0022] Figure 2 This is a flowchart illustrating the preparation process of the high-purity copper particles of this invention.

[0023] Figure 3 This is a top view of the vacuum distillation high-purity copper condensate product from Example 1;

[0024] Figure 4 This is a top view of the volatiles from the vacuum distillation of high-purity copper particles in Example 1;

[0025] Figure 5 This is a top view of the vacuum distillation high-purity copper condensate product from Example 2;

[0026] Figure 6 This is a top view of the volatiles from the vacuum distillation of high-purity copper particles in Example 2;

[0027] Figure 7 This is a top view of the vacuum distillation high-purity copper condensate product from Example 3;

[0028] Figure 8 This is a top view of the volatiles from the vacuum distillation of high-purity copper particles in Example 3;

[0029] Figure 9 This is the test report for the vacuum distillation high-purity copper condensate product from Example 3;

[0030] Figure 10 This is the test report for volatiles from vacuum distilled high-purity copper particles in Example 3;

[0031] Figure 11 This is a scanning electron microscope image of high-purity spherical copper particles obtained by vacuum distillation in Example 1;

[0032] Figure 12 This is a scanning electron microscope image of high-purity spherical copper particles obtained by vacuum distillation in Example 3. Detailed Implementation

[0033] The present invention provides a vacuum distillation furnace, wherein a evaporation perforation plate is provided between the condensation plate and the evaporation chamber; the pore diameter of the evaporation perforation plate is 1~10mm.

[0034] In this invention, the aperture of the evaporation plate is preferably 2-9 mm, more preferably 3-8 mm, and even more preferably 4-6 mm. By controlling the aperture of the evaporation plate within the above range, this invention can prevent impurities from clogging the plate due to excessively small apertures, while ensuring a high gas flow rate, thereby ensuring the amount of powder produced and obtaining copper particles.

[0035] In this invention, the porosity of the volatile plate is preferably 0.138% to 13.80%, more preferably 1% to 10%, and even more preferably 2% to 8%. In the embodiments of this invention, it is specifically 2.2%.

[0036] In this invention, the evaporation holes in the evaporation plate are preferably spaced 1 km from the center to the edge of the plate. 2 2 2 3 2 4 2 5 2 ...n 2 The number of holes is distributed sequentially from the inside to the outside.

[0037] In this invention, the evaporation orifice plate is preferably conical in shape, and the vertical distance between the lowest and highest points of the evaporation orifice plate (i.e., the height of the evaporation orifice plate) is preferably 5-10 cm. This invention does not have special requirements for the diameter of the evaporation orifice plate, as long as it can cover the evaporation chamber.

[0038] In this invention, the evaporation plate is preferably a chromium plate. The chromium evaporation plate is chosen because, firstly, metallic chromium has a melting point of 1907℃ and is resistant to high temperatures; more importantly, during the volatilization of impurity elements, chromium can effectively react chemically with impurity elements such as Fe, Si, Mn, Al, and Cl at high temperatures and adsorb onto the lower surface of the evaporation plate. (Due to the relationship of saturated vapor pressure, most of the above impurity elements are still in a gaseous state within a given temperature range, with relatively high activation energy, and will undergo chemical reactions at high temperatures. Within the given temperature range, a small portion of copper will also condense. Considering the difference in the molecular free path between impurity elements and copper, more impurity elements condense to the lower surface, while copper vapor will pass through the orifice plate into the upper condensation zone and condense into copper particles.) This achieves the separation of impurity elements from copper. Since the condensation plate is in direct contact with the cooling water system, copper vapor will rapidly condense into copper powder particles when it collides with the condensation plate, and be collected above the evaporation plate and on the condensation plate.

[0039] In this invention, the evaporation orifice plate is located in the region below the copper condensation temperature. In an embodiment of this invention, specifically, the highest point of the evaporation orifice plate is located at 1 / 2 of the distance between the evaporation chamber and the condensation plate.

[0040] In this invention, the other structures of the vacuum distillation furnace are all well-known in the art, and this invention does not impose any special limitations. For example... Figure 1 As shown, the vacuum distillation furnace provided by the present invention includes: 1-sealing ring; 2-handle; 3-sealing screw; 4-furnace cover; 5-furnace shell; 6-evacuation port; 7-crucible; 8-heating element; 9-thermocouple; 10-insulating cotton; 11-electrode; 12-graphite felt; 13-water inlet and cooling water; 14-protective shell; 15-evaporation plate; 16-condensation plate; 17-gas cylinder, wherein the crucible is located in the evaporation chamber.

[0041] The vacuum distillation furnace provided by this invention does not produce waste liquid or waste gas, and has the characteristics of low cost and no pollution.

[0042] This invention provides a method for preparing high-purity copper particles, comprising the following steps: placing metallic copper raw material in the evaporation chamber of the vacuum distillation furnace described above, performing vacuum distillation, and obtaining high-purity copper particles in the condenser; the vacuum degree of the vacuum distillation is 0.1~100 Pa, the temperature of the vacuum distillation is 1100~1800℃, and the particle size of the high-purity copper particles is 1~100 μm.

[0043] The present invention does not have special requirements on the source and purity of the copper raw material. In the embodiments of the present invention, the copper raw material preferably includes electrolytic cathode copper with a purity of 3N grade.

[0044] Before vacuum distillation, the present invention preferably cleans the surface oil of the copper raw material; the present invention does not have special requirements for the method of cleaning the surface oil, and any cleaning method well known in the art can be used. In an embodiment of the present invention, the copper raw material is specifically cleaned in anhydrous ethanol and then air-dried in a cleanroom.

[0045] In this invention, the vacuum degree of the vacuum distillation is preferably 1~95 Pa, more preferably 5~90 ​​Pa, and even more preferably 10~80 Pa; the temperature of the vacuum distillation is preferably 1200~1700℃, more preferably 1300~1600℃, and even more preferably 1400~1500℃; the time of the vacuum distillation is preferably 0.5~3h, more preferably 1~2.5h, and even more preferably 1.5~2h.

[0046] In this invention, the rate of heating to the temperature of the vacuum distillation is preferably 5~20℃ / min, more preferably 10~15℃ / min.

[0047] After completing the vacuum distillation, the present invention preferably allows the material to cool naturally to room temperature under vacuum conditions, and high-purity copper particles are collected on a condenser plate.

[0048] In this invention, the particle size of the high-purity copper particles is 1~100μm, preferably 10~90μm, and more preferably 20~80μm. The purity of the high-purity copper particles is preferably 5N or higher.

[0049] Figure 2 This is a flowchart illustrating the preparation process of the high-purity copper particles of this invention. Figure 2 As shown, this invention first cleans the surface oil of the copper raw material, then places the cleaned copper raw material in the evaporation chamber of a vacuum distillation furnace for vacuum distillation, and obtains high-purity copper particles in the condenser. According to practical applications, this invention can sieve the high-purity copper particles to obtain high-purity copper powder (which can be used for catalyst doping) and high-purity spherical copper (which can be used for coatings).

[0050] This invention addresses the problem that traditional methods used in the industrial production of high-purity copper particles often fail to achieve the desired purity, resulting in high impurity content and complex composition. By utilizing vacuum distillation, most of the valuable metals in the copper matrix volatilize into the gas phase and separate from the copper matrix during the vacuum distillation process, achieving a copper purity of 99.9991%. This purification of copper is achieved, and the copper powder particles volatilized onto the condenser have a smooth surface and a purity of over 5N, making them suitable for applications such as catalyst doping, medical and chemical industries.

[0051] This invention uses vacuum distillation to obtain high-purity copper condensate of grade 5N or higher, while simultaneously enriching and collecting copper powder particles. This method shortens the process flow, eliminates the need for waste liquid treatment, and features low cost and no pollution.

[0052] The following detailed description of the vacuum distillation furnace and the method for preparing high-purity copper particles provided by the present invention, with reference to the embodiments, should not be construed as limiting the scope of protection of the present invention.

[0053] The vacuum distillation furnace used in the following examples is as follows: Figure 1 As shown, the highest point of the evaporation plate is located at 1 / 2 of the distance between the condenser plate and the evaporation chamber. The evaporation plate is made of chromium and is a conical disc. The vertical distance between the lowest and highest points is 10 cm. The porosity of the evaporation plate is 2.2%, the pore diameter is 4 mm, and the pores extend from the center outwards at a rate of 1... 2 2 2 3 2 4 2 5 2 There are 55 holes arranged sequentially from the inside out.

[0054] Example 1

[0055] (1) 10.56g of 3N grade electrolytic cathode copper was cleaned in anhydrous ethanol, air-dried in a clean room, and then placed in a vacuum distillation furnace. The furnace pressure was maintained at 10Pa and the temperature was raised to the distillation temperature of 1400℃ at a constant temperature of 10℃ / min. The impurities were removed by vacuum distillation for 120min, so that the volatile impurity elements Al, Cd, Bi, Ga, K, Mg, Zn, Pb, Ga, Fe, Ni, Si, Au and other elements were vaporized and volatilized to the lower surface of the volatilization orifice plate. The furnace was cooled to room temperature under vacuum conditions, and high-purity distilled copper was obtained in the crucible. High-purity copper particles were collected on the condenser plate.

[0056] A top view of vacuum distilled high-purity copper products is shown below. Figure 3 .

[0057] The test results showed that the mass of the high-purity copper powder condensate obtained by distillation was 7.428g, the recovery rate was 70.34%, and the purity of the distilled high-purity copper powder was 99.9991%.

[0058] A top view of vacuum distilled high-purity copper volatiles, i.e., high-purity copper particles, is shown below. Figure 4 Scanning electron microscope image (see) Figure 11 .Depend on Figure 11 It can be seen that the high-purity copper particles obtained by this invention have a smooth surface and a regular shape.

[0059] Testing revealed that the obtained high-purity copper particles weighed 3.132 g, with a yield of 29.66%; the particle size ranged from 1 to 10 μm, and the purity was 99.9991%.

[0060] Example 2

[0061] (1) 10.24g of 3N grade electrolytic cathode copper was cleaned in anhydrous ethanol, air-dried in a clean room, and then placed in a vacuum distillation furnace. The furnace pressure was maintained at 10Pa and the temperature was raised to the distillation temperature of 1450℃ at a constant temperature of 10℃ / min. The impurities were removed by vacuum distillation for 100min, so that the volatile impurity elements Al, Cd, Bi, Ga, K, Mg, Zn, Pb, Ga, Fe, Ni, Si, Au and other elements were vaporized and volatilized to the lower surface of the volatilization orifice plate. The furnace was cooled to room temperature under vacuum conditions, and high-purity distilled copper was obtained in the crucible. High-purity copper particles were collected on the condenser plate.

[0062] A top view of vacuum distilled high-purity copper is shown below. Figure 5 .

[0063] The mass of the high-purity copper powder condensate obtained by distillation was 8.046 g, the recovery rate was 78.57%, and the purity of the distilled high-purity copper powder was 99.9992%.

[0064] A top view of the volatiles from vacuum distillation of high-purity copper particles is shown below. Figure 6 .

[0065] Testing revealed that the obtained high-purity copper product weighed 2.194g, with a yield of 21.43%. The high-purity copper particles had a particle size of 1~10μm and a purity of 99.9987%.

[0066] Example 3

[0067] (1) 10.54g of 3N grade electrolytic cathode copper was cleaned in anhydrous ethanol, air-dried in a clean room, and then placed in a vacuum distillation furnace. The furnace pressure was maintained at 5Pa by evacuation. The temperature was raised to the distillation temperature of 1500℃ at a constant temperature of 10℃ / min. The impurities were removed by vacuum distillation for 90min, so that the volatile impurity elements Al, Cd, Bi, Ga, K, Mg, Zn, Pb, Ga, Fe, Ni, Si, Au and other elements were vaporized and volatilized to the lower surface of the volatilization plate. The furnace was cooled to room temperature under vacuum conditions, and high-purity distilled copper was obtained in the crucible. High-purity copper particles were collected on the condenser plate.

[0068] A top view of vacuum distilled high-purity copper is shown below. Figure 7 .

[0069] The mass of the high-purity copper powder condensate obtained by distillation was 7.783 g, the recovery rate was 73.84%, and the purity of the distilled high-purity copper powder was 99.9987%.

[0070] A top view of vacuum distilled high-purity copper volatiles, i.e., high-purity copper particles, is shown below. Figure 8 Scanning electron microscope image (see) Figure 12 .Depend on Figure 12It can be seen that the copper powder particles are of uneven size, with some non-spherical small particles interspersed in the middle, combined with the characterization results of Example 1 ( Figure 11 It can be seen that the heat preservation time has a significant impact on the spheroidization rate of copper powder. Moreover, within a certain heat preservation time, the longer the heat preservation time, the higher the spheroidization rate and the more uniform the particle size of the copper powder.

[0071] The high-purity copper particles obtained were measured to be 2.757 g, with a yield of 26.16%. The particle size ranged from 1 to 10 μm, and the purity was 99.99902%.

[0072] The results of high-purity copper detection by vacuum distillation are shown below. Figure 9 See the volatile matter test report. Figure 10 .

[0073] Examples 4-11

[0074] The only difference from Example 1 is the vacuum distillation conditions. The specific vacuum distillation conditions and the purity of the high-purity copper particles are shown in Table 1.

[0075] Table 1. Vacuum distillation conditions and purity of high-purity copper particles in Examples 4-11

[0076]

[0077] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing high-purity copper particles, characterized in that, The process includes the following steps: placing metallic copper raw material in the evaporation chamber of a vacuum distillation furnace for vacuum distillation, and obtaining high-purity copper particles in a condenser; the vacuum degree of the vacuum distillation is 0.1~100 Pa, and the temperature of the vacuum distillation is 1100~1800℃; the particle size of the high-purity copper particles is 1~100 μm. A evaporation perforation plate is provided between the condenser plate and the evaporation chamber of the vacuum distillation furnace; the pore diameter of the evaporation perforation plate is 1~8mm; The evaporation plate is in the shape of a conical disk; The evaporation plate is a chromium plate.

2. The preparation method according to claim 1, characterized in that, The vacuum distillation time is 0.5 to 3 hours.

3. The preparation method according to claim 1 or 2, characterized in that, The rate of heating to the vacuum distillation temperature is 5~20℃ / min.

4. The preparation method according to claim 1, characterized in that, The copper raw material includes electrolytic cathode copper.

5. The preparation method according to claim 1, characterized in that, The porosity of the volatile plate is 0.138%~13.80%.

Images