Ultra-high purity copper and its preparation method and application

Abstract

The present invention provides an ultra-high purity copper and a preparation method and application thereof, the method comprising the following steps: (1) mixing crude copper and acid solution to obtain a copper salt solution; (2) subjecting the copper salt solution obtained in step (1) to multi-stage leaching to obtain copper salt crystals; (3) in the process of copper electrolysis, adding the copper salt crystals obtained in step (2) to the electrolyte to adjust the copper ion concentration to obtain ultra-high purity copper; wherein the purity of the crude copper is ≤4N, and the purity of the ultra-high purity copper is ≥6N. The preparation method provided by the present invention combines the multi-stage leaching and copper electrolysis process, uses high-purity copper salt crystals as a copper ion maintainer in the electrolyte, ensures the smooth progress of the copper electrolysis process, and finally obtains ultra-high purity copper, realizes the stable production of ultra-high purity copper, and improves the economic benefits and product competitiveness of ultra-high purity copper industrialization.

Description

Technical Field

[0001] The invention belongs to the technical field of metal purification and relates to ultra-high purity copper, and in particular to ultra-high purity copper and a preparation method and application thereof. Background Art

[0002] At present, electrolytic copper mainly uses high-purity (4N) metal copper plates as raw materials, which are used as electrolytic anodes in electrolytic cells and continuously release copper ions under the action of current to ensure the copper ion concentration in the electrolyte. However, due to the presence of more impurities in 4N copper: silver, sulfur, silicon and other elements, and because the reduction potential of copper is close to that of silver, silver will inevitably be deposited on the cathode titanium plate together with copper during the electrolytic copper process, which ultimately makes it difficult to stably maintain the purity of ultra-high purity copper above 6N. This is also the main reason for the large fluctuations in the purity of ultra-high purity electrolytic copper products at this stage, the poor stability of product purity, the rising rate of unqualified products and the low economic benefits of industrialization. In order to improve the purity of electrolytic copper products, technicians usually use electrolytic additives, membrane separation and extraction methods to reduce the impurity content in the electrolyte and achieve stable preparation of ultra-high purity metallic copper.

[0003] When preparing ultra-high purity metals by electrolytic copper, technicians generally choose to add specific additives during the electrolysis process to achieve selective deposition of cathode reaction kinetics, thereby reducing the deposition of impurity metals on the cathode surface. However, most of the additives used in industry are concentrated on forming complexes, and are even used for the flattening of the cathode surface. Secondly, due to the similar complexing ability of silver ions and copper ions, most additives usually complex with copper ions first, and only a small amount complexes with impurity silver ions. This has also become the main reason why it is difficult to achieve stable preparation of ultra-high purity metals with additives at this stage.

[0004] The membrane separation method mainly adds specific anion and cation exchange membranes or resins to anions and cations during the electrolysis process, and uses its screening effect on anions and cations and ions of different valence states to achieve the screening of monovalent and divalent impurity cations and impurity ions. This method can achieve ultra-high purity copper products with only low silver ions (0.3-0.05ppm). In actual industrial production, the cost of proton exchange membranes and resins is usually maintained at 3,000 yuan / m 2 , and due to the requirements of the industrial production process of electrolytic copper, the use time in a strong acidic environment is generally 15 days, which also leads to problems such as increased use frequency of proton exchange membranes (0.5-1 year / time) and reduced selectivity. The above problems in actual production lead to a significant increase in preparation costs and are accompanied by the risk of reduced product purity.

[0005] In addition, for the pretreatment methods before electrolysis, technicians usually choose specific metal extractants to extract, enrich and purify copper ions. However, the conventional use of metal extractants to enrich copper ions is generally carried out in a sulfuric acid system, which undoubtedly increases the risk of excessive sulfur content in ultra-high purity copper products. At present, in order to obtain ultra-high purity 6N copper and reduce the sulfur content therein, technicians usually carry out the electrolysis process in a nitric acid system, but because nitrate ions have a strong oxidizing effect on ketone oxime and ether oxime extractants, ketone oxime and ether oxime are degraded and converted into corresponding aldehydes and ethers, which in turn causes the extractant to fail.

[0006] It can be seen that how to provide a method for preparing ultra-high purity copper, avoid the introduction of impurities, achieve stable production of ultra-high purity copper, and improve the economic benefits and product competitiveness of ultra-high purity copper industrialization has become an urgent problem that technical personnel in this field need to solve. Summary of the invention

[0007] In view of the deficiencies in the prior art, the purpose of the present invention is to provide an ultra-high purity copper and a preparation method and application thereof. The preparation method combines multi-stage leaching and copper electrolysis processes, uses high-purity copper salt crystals as copper ion maintainers in the electrolyte, ensures the smooth progress of the copper electrolysis process, and finally obtains ultra-high purity copper, thereby achieving stable production of ultra-high purity copper and improving the economic benefits and product competitiveness of ultra-high purity copper industrialization.

[0008] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0009] In a first aspect, the present invention provides a method for preparing ultra-high purity copper, the preparation method comprising the following steps:

[0010] (1) mixing crude copper and acid solution to obtain a copper salt solution;

[0011] (2) subjecting the copper-containing solution obtained in step (1) to multi-stage leaching to obtain copper salt crystals;

[0012] (3) During the copper electrolysis process, the copper salt crystals obtained in step (2) are added to the electrolyte to adjust the copper ion concentration to obtain ultra-high purity copper.

[0013] Among them, the purity of the crude copper is ≤4N, for example, it can be 1N, 1N5, 2N, 2N5, 3N, 3N5 or 4N, and the purity of the ultra-high purity copper is ≥6N, for example, it can be 6N, 6N5, 7N, 7N5 or 8N, but it is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0014] In the present invention, 4N and 6N are both common terms for indicating purity, where "N" stands for "Nines", i.e., purity is expressed in multiples of 9. For example, 4N indicates a purity of 99.99%, 4N5 indicates a purity of 99.995%, and so on, so they are not described in detail.

[0015] The preparation method provided by the present invention synergistically combines multi-stage leaching and copper electrolysis processes, firstly utilizes multi-stage leaching to obtain high-purity copper salt crystals, and then uses the high-purity copper salt crystals as copper ion maintainers in the electrolyte, thereby ensuring the smooth progress of the copper electrolysis process and avoiding the introduction of impurities, and finally obtaining ultra-high purity copper, realizing the stable production of ultra-high purity copper, and improving the economic benefits and product competitiveness of ultra-high purity copper industrialization.

[0016] Preferably, the acid solution in step (1) comprises nitric acid solution and / or sulfuric acid solution.

[0017] Preferably, the concentration of the copper salt solution in step (1) is 60-200 g / L, for example, 60 g / L, 80 g / L, 100 g / L, 120 g / L, 140 g / L, 160 g / L, 180 g / L or 200 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0018] Preferably, the multi-stage leaching in step (2) includes three-stage leaching, and each stage of leaching includes high-temperature concentration, crystal redissolution and cooling crystallization performed in sequence.

[0019] In the present invention, the three-stage leaching utilizes the difference in solubility of copper salt at different temperatures and the difference in distribution coefficient of impurities in the solid and liquid phases to crystallize and purify copper salt from a low-concentration solution to obtain high-purity copper salt crystals, which are subsequently used as a copper ion maintainer in the electrolyte.

[0020] Preferably, the temperature of the high temperature concentration is 35-65°C, for example, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C or 65°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0021] The present invention limits the temperature of high-temperature concentration to within the range of 35-65°C, thereby achieving rapid removal of water in the solution and avoiding the generation of more acidic harmful gases, such as nitrogen oxides, acid mist, etc., caused by excessively high temperature in nitric acid / sulfuric acid in the solution, thereby meeting environmental protection requirements.

[0022] Preferably, the temperature for re-dissolving the crystals is 20-40°C, for example, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C or 40°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0023] The present invention limits the temperature of crystal redissolution to within the range of 20-40° C., accelerates the appearance of copper ion crystals in the high-temperature zone of the electrolyte due to the reduction of the solution volume, and reduces the volatilization volume of the electrolyte in this area.

[0024] Preferably, the cooling crystallization temperature is 10-30°C, for example, it can be 10°C, 12°C, 14°C, 16°C, 18°C, 20°C, 22°C, 24°C, 26°C, 28°C or 30°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0025] The present invention limits the temperature of cooling crystallization to within the range of 10-30°C, fully utilizes the high and low temperature solubility difference of copper salt, and realizes the rapid crystallization of metal copper salt.

[0026] Preferably, the anode used in the copper electrolysis process in step (3) comprises a 4N copper plate, and the cathode comprises a titanium plate.

[0027] In the present invention, the 4N copper plate means that the purity of the metal copper in the copper plate is 4N, that is, 99.99%.

[0028] Preferably, the electrolyte in step (3) comprises copper nitrate solution and / or copper sulfate solution.

[0029] Preferably, the electrolyte in step (3) also includes hydrogen peroxide.

[0030] Preferably, the hydrogen peroxide is added to the electrolyte before the start of copper electrolysis and left to stand for 1-5 hours, for example, 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, 3.5 hours, 4 hours, 4.5 hours or 5 hours, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0031] The present invention adds hydrogen peroxide to the electrolyte and utilizes the strong oxidizing property of hydrogen peroxide to fully oxidize certain reducing impurities in the electrolyte, such as metal ions or organic substances, thereby reducing the interference of these impurities on the electrolysis process and improving the stability of the electrolysis process. The decomposition products are water and oxygen, which meets the green and environmentally friendly production requirements.

[0032] In the present invention, the concentration of the hydrogen peroxide can be 10-20wt%, and the mixing volume ratio of the hydrogen peroxide to the electrolyte can be (0.1-2)mL:1L, for example, it can be 0.1mL:1L, 0.5mL:1L, 1mL:1L, 1.5mL:1L or 2mL:1L, but it is not limited to the listed values, and other values ​​not listed within the numerical range are also applicable.

[0033] Preferably, the copper ion concentration in step (3) is 50-200 g / L, for example, 50 g / L, 60 g / L, 70 g / L, 80 g / L, 90 g / L, 100 g / L, 110 g / L, 120 g / L, 130 g / L, 140 g / L, 150 g / L, 160 g / L, 170 g / L, 180 g / L, 190 g / L or 200 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are equally applicable.

[0034] The present invention adds copper salt crystals to the electrolyte to adjust the copper ion concentration to 50-200 g / L. This copper source selection method improves the purity of the electrolyte, reduces the total impurity content in the electrolysis process, is beneficial to improving product purity, and improves production continuity and efficiency. By controlling the copper ion concentration in the electrolyte, the deposition rate of copper on the cathode can be adjusted, thereby affecting the crystal structure and physical properties of the deposited copper, and ultimately obtaining higher quality electrolytic copper.

[0035] Preferably, the hydrogen ion concentration in the electrolyte in step (3) is 0.01-0.4 g / L, for example, it can be 0.01 g / L, 0.02 g / L, 0.03 g / L, 0.04 g / L, 0.05 g / L, 0.1 g / L, 0.2 g / L, 0.3 g / L or 0.4 g / L, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0036] Preferably, during the copper electrolysis process in step (3), the current density is 50-200 mA / cm 2 , for example, it can be 50mA / cm 2 、60mA / cm 2 , 70mA / cm 2 、80mA / cm 2 , 90mA / cm 2 , 100mA / cm 2 , 110mA / cm 2 , 120mA / cm 2 , 130mA / cm 2 , 140mA / cm 2 , 150mA / cm 2 , 160mA / cm2 , 170mA / cm 2 , 180mA / cm 2 、190mA / cm 2 or 200mA / cm 2 The electrolysis temperature is 10-45°C, for example, it can be 10°C, 12°C, 14°C, 16°C, 18°C, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C, 40°C, 42°C, 44°C or 45°C, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0037] As a preferred technical solution of the first aspect of the present invention, the method comprises the following steps:

[0038] (1) mixing crude copper and acid solution to prepare a copper salt solution with a concentration of 60-200 g / L; the acid solution comprises nitric acid solution and / or sulfuric acid solution;

[0039] (2) subjecting the copper-containing solution obtained in step (1) to three-stage leaching, wherein each stage of leaching comprises high-temperature concentration, crystal redissolution and cooling crystallization performed in sequence, and the temperature of high-temperature concentration is controlled to be 35-65° C., the temperature of crystal redissolution is controlled to be 20-40° C., and the temperature of cooling crystallization is controlled to be 10-30° C., to obtain copper salt crystals;

[0040] (3) Using a 4N copper plate as the anode, a titanium plate as the cathode, and a copper nitrate solution and / or a copper sulfate solution as the electrolyte, hydrogen peroxide is added to the electrolyte before the start of copper electrolysis, and the copper electrolysis process is started after standing for 1-5 hours, and the current density is controlled to be 50-200 mA / cm 2 , the electrolysis temperature is 10-45° C., the copper salt crystals obtained in step (2) are added to the electrolyte to adjust the copper ion concentration to 50-200 g / L and the hydrogen ion concentration to 0.01-0.4 g / L, and ultra-high purity copper is obtained.

[0041] Wherein, the purity of the crude copper is ≤4N, and the purity of the ultra-high purity copper is ≥6N.

[0042] In a second aspect, the present invention provides an ultra-high purity copper prepared by the preparation method described in the first aspect, wherein the purity of the ultra-high purity copper is ≥6N, for example, it can be 6N, 6N5, 7N, 7N5 or 8N, but is not limited to the listed values, and other unlisted values ​​within the numerical range are also applicable.

[0043] In a third aspect, the present invention provides an application of the ultra-high purity copper as described in the second aspect, wherein the ultra-high purity copper is used to manufacture a pure copper target or an alloy target.

[0044] The numerical range described in the present invention not only includes the point values ​​listed above, but also includes any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] The preparation method provided by the present invention synergistically combines multi-stage leaching and copper electrolysis processes, firstly utilizes multi-stage leaching to obtain high-purity copper salt crystals, and then uses the high-purity copper salt crystals as copper ion maintainers in the electrolyte, thereby ensuring the smooth progress of the copper electrolysis process and avoiding the introduction of impurities, and finally obtaining ultra-high purity copper, realizing the stable production of ultra-high purity copper, and improving the economic benefits and product competitiveness of ultra-high purity copper industrialization. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a three-stage leaching device adopted by the method for preparing ultra-high purity copper provided by the present invention.

[0048] Among them: 1-copper salt solution storage tank; 2-screw feeder; 3-heating plate; 4-cooling water inlet; 5-cooling water outlet; 6-copper salt crystal storage tank; 10-primary extraction unit; 11-high temperature concentration area; 12-crystal re-dissolution area; 13-cooling crystallization area; 20-secondary extraction unit; 30-tertiary extraction unit. DETAILED DESCRIPTION

[0049] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0050] The present invention provides a three-stage extraction device, such as Figure 1 As shown, the three-stage leaching device includes a primary leaching unit 10, a secondary leaching unit 20 and a tertiary leaching unit 30 connected in sequence. Each leaching unit includes a high-temperature concentration zone 11, a crystal redissolution zone 12 and a cooling crystallization zone 13 connected in sequence.

[0051] Specifically, the high-temperature concentration zone 11 is provided with a copper salt solution storage tank 1, and the copper salt solution flows from the copper salt solution storage tank 1 through a screw feeder 2 in sequence through the high-temperature concentration zone 11, the crystal re-dissolution zone 12 and the cooling crystallization zone 13, and the high-temperature concentration zone 11 and the crystal re-dissolution zone 12 are both provided with a heating plate 3, and the crystal re-dissolution zone 12 and the cooling crystallization zone 13 are both provided with a cooling water inlet 4 and a cooling water outlet 5, and the obtained copper salt crystals are finally transmitted to the copper salt crystal storage tank 6 for the next stage of leaching.

[0052] Example 1

[0053] This embodiment provides a method for preparing ultra-high purity copper, which specifically includes the following steps:

[0054] (1) mixing crude copper with a purity of 4N and a nitric acid solution to prepare a copper nitrate solution with a concentration of 200 g / L;

[0055] (2) Using Figure 1 The three-stage leaching device shown performs three-stage leaching on the copper nitrate solution obtained in step (1), and each stage of leaching includes high-temperature concentration, crystal redissolution and cooling crystallization in sequence, and the temperature of high-temperature concentration is controlled to be 35° C., the temperature of crystal redissolution is 30° C., and the temperature of cooling crystallization is 20° C., to obtain copper nitrate crystals;

[0056] (3) A 4N copper plate was used as the anode, a titanium plate was used as the cathode, and a copper nitrate solution was used as the electrolyte. Hydrogen peroxide was added to the electrolyte before the copper electrolysis began. After standing for 3 hours, the copper electrolysis process began. The current density was controlled to be 120 mA / cm 2 , the electrolysis temperature is 10° C., and the copper nitrate crystals obtained in step (2) are added to the electrolyte to adjust the copper ion concentration to 100 g / L and the hydrogen ion concentration to 0.1 g / L to obtain ultra-high purity copper.

[0057] Example 2

[0058] This embodiment provides a method for preparing ultra-high purity copper, which specifically includes the following steps:

[0059] (1) mixing crude copper with a purity of 3N5 and a sulfuric acid solution to prepare a copper sulfate solution with a concentration of 60 g / L;

[0060] (2) Using Figure 1 The three-stage leaching device shown performs three-stage leaching on the copper sulfate solution obtained in step (1), and each stage of leaching includes high-temperature concentration, crystal redissolution and cooling crystallization in sequence, and the temperature of high-temperature concentration is controlled to be 60° C., the temperature of crystal redissolution is 40° C., and the temperature of cooling crystallization is 30° C., to obtain copper sulfate crystals;

[0061] (3) A 4N copper plate was used as the anode, a titanium plate was used as the cathode, and a copper sulfate solution was used as the electrolyte. Hydrogen peroxide was added to the electrolyte before the copper electrolysis began. The copper electrolysis process was started after standing for 5 hours, and the current density was controlled to be 200 mA / cm 2 , the electrolysis temperature is 45° C., and the copper sulfate crystals obtained in step (2) are added to the electrolyte to adjust the copper ion concentration to 50 g / L and the hydrogen ion concentration to 0.4 g / L to obtain ultra-high purity copper.

[0062] Example 3

[0063] This embodiment provides a method for preparing ultra-high purity copper, which specifically includes the following steps:

[0064] (1) mixing crude copper with a purity of 4N and a sulfuric acid solution to prepare a copper sulfate solution with a concentration of 100 g / L;

[0065] (2) Using Figure 1 The three-stage leaching device shown performs three-stage leaching on the copper sulfate solution obtained in step (1), and each stage of leaching includes high-temperature concentration, crystal redissolution and cooling crystallization in sequence, and the temperature of high-temperature concentration is controlled to be 65° C., the temperature of crystal redissolution is controlled to be 40° C., and the temperature of cooling crystallization is controlled to be 20° C., to obtain copper sulfate crystals;

[0066] (3) A 4N copper plate was used as the anode, a titanium plate was used as the cathode, and a copper sulfate solution was used as the electrolyte. Hydrogen peroxide was added to the electrolyte before the copper electrolysis began. After standing for 1 hour, the copper electrolysis process began. The current density was controlled to be 50 mA / cm 2 , the electrolysis temperature is 20° C., and the copper sulfate crystals obtained in step (2) are added to the electrolyte to adjust the copper ion concentration to 200 g / L and the hydrogen ion concentration to 0.2 g / L to obtain ultra-high purity copper.

[0067] Example 4

[0068] This embodiment provides a method for preparing ultra-high purity copper. Except that the temperature of the high-temperature concentration in step (2) is changed to 30° C., the remaining steps and conditions are the same as those in Example 1, and thus are not described in detail here.

[0069] Example 5

[0070] This embodiment provides a method for preparing ultra-high purity copper. Except that the temperature for redissolving the crystals in step (2) is changed to 15° C., the remaining steps and conditions are the same as those in Example 1 and are not described in detail here.

[0071] Example 6

[0072] This embodiment provides a method for preparing ultra-high purity copper. Except that the cooling crystallization temperature in step (2) is changed to 35° C., the remaining steps and conditions are the same as those in Example 1 and are not described in detail here.

[0073] Example 7

[0074] This embodiment provides a method for preparing ultra-high purity copper. Except that hydrogen peroxide is not added to the electrolyte in step (3), the remaining steps and conditions are the same as those in Example 1, and thus are not described in detail here.

[0075] Example 8

[0076] This embodiment provides a method for preparing ultra-high purity copper. Except for step (3) of adjusting the copper ion concentration to 40 g / L, the remaining steps and conditions are the same as those in Example 1, and thus are not described in detail here.

[0077] Comparative Example 1

[0078] This comparative example provides a method for preparing metallic copper. Except that the three-stage leaching in step (2) is changed to a single-stage leaching, the remaining steps and conditions are the same as those in Example 1, and thus are not described in detail here.

[0079] Comparative Example 2

[0080] This comparative example provides a method for preparing metallic copper. Except for directly cooling the copper nitrate solution in step (1) to crystallize, and adding the obtained copper nitrate crystals to the electrolyte in step (3), the remaining steps and conditions are the same as those in Example 1, and thus are not described in detail here.

[0081] After testing, the purity of the metallic copper obtained in Examples 1-8 and Comparative Examples 1-2 is shown in Table 1 below.

[0082] Table 1

[0083]

[0084]

[0085] It can be seen that the preparation method provided by the present invention synergistically combines the multi-stage leaching and copper electrolysis processes, firstly utilizes the multi-stage leaching to obtain high-purity copper salt crystals, and then uses the high-purity copper salt crystals as the copper ion maintainer in the electrolyte, thereby ensuring the smooth progress of the copper electrolysis process and avoiding the introduction of impurities, and finally obtaining ultra-high purity copper, realizing the stable production of ultra-high purity copper, and improving the economic benefits and product competitiveness of the industrialization of ultra-high purity copper.

[0086] The applicant declares that the above is only a specific implementation mode of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily thought of by those skilled in the art within the technical scope disclosed by the present invention shall fall within the protection scope and disclosure scope of the present invention.

Claims

1. A method for preparing ultra-high purity copper, characterized in that: The preparation method comprises the following steps: (1) mixing crude copper and acid solution to obtain a copper salt solution; (2) subjecting the copper salt solution obtained in step (1) to multi-stage leaching to obtain copper salt crystals; (3) During the copper electrolysis process, the copper salt crystals obtained in step (2) are added to the electrolyte to control the copper ion concentration to obtain ultra-high purity copper; Wherein, the purity of the crude copper is ≤4N, and the purity of the ultra-high purity copper is ≥6N.

2. The preparation method according to claim 1, characterized in that: The acid solution in step (1) comprises a nitric acid solution and / or a sulfuric acid solution; Preferably, the concentration of the copper salt solution in step (1) is 60-200 g / L.

3. The preparation method according to claim 1 or 2, characterized in that: The multi-stage leaching in step (2) includes three-stage leaching, and each stage of leaching includes high-temperature concentration, crystal redissolution and cooling crystallization performed in sequence.

4. The preparation method according to claim 3, characterized in that: The temperature of the high temperature concentration is 35-65°C; Preferably, the temperature for re-dissolving the crystals is 20-40°C; Preferably, the temperature of the cooling crystallization is 10-30°C.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The anode used in the copper electrolysis process in step (3) includes a 4N copper plate, and the cathode includes a titanium plate; Preferably, the electrolyte in step (3) comprises copper nitrate solution and / or copper sulfate solution; Preferably, the electrolyte in step (3) further comprises hydrogen peroxide; Preferably, the hydrogen peroxide is added to the electrolyte before copper electrolysis begins and is left to stand for 1-5 hours.

6. The preparation method according to any one of claims 1 to 5, characterized in that: The copper ion concentration in step (3) is 50-200 g / L; Preferably, the hydrogen ion concentration in the electrolyte in step (3) is 0.01-0.4 g / L.

7. The preparation method according to any one of claims 1 to 6, characterized in that: During the copper electrolysis process in step (3), the current density is 50-200 mA / cm 2 , the electrolysis temperature is 10-45℃.

8. The preparation method according to any one of claims 1 to 7, characterized in that: The method comprises the following steps: (1) mixing crude copper and acid solution to prepare a copper salt solution with a concentration of 60-200 g / L; the acid solution comprises nitric acid solution and / or sulfuric acid solution; (2) subjecting the copper salt solution obtained in step (1) to three-stage leaching, wherein each stage of leaching comprises high-temperature concentration, crystal redissolution and cooling crystallization in sequence, and the temperature of high-temperature concentration is controlled to be 35-65° C., the temperature of crystal redissolution is controlled to be 20-40° C., and the temperature of cooling crystallization is controlled to be 10-30° C., to obtain copper salt crystals; (3) Using a 4N copper plate as the anode, a titanium plate as the cathode, and a copper nitrate solution and / or a copper sulfate solution as the electrolyte, hydrogen peroxide is added to the electrolyte before the start of copper electrolysis, and the copper electrolysis process is started after standing for 1-5 hours, and the current density is controlled to be 50-200 mA / cm 2 , the electrolysis temperature is 10-45° C., the copper salt crystals obtained in step (2) are added to the electrolyte to adjust the copper ion concentration to 50-200 g / L and the hydrogen ion concentration to 0.01-0.4 g / L, to obtain ultra-high purity copper; Wherein, the purity of the crude copper is ≤4N, and the purity of the ultra-high purity copper is ≥6N.

9. An ultra-high purity copper prepared by the preparation method according to any one of claims 1 to 8, characterized in that: The purity of the ultra-high purity copper is ≥6N.

10. An application of the ultra-high purity copper as claimed in claim 9, characterized in that: The ultra-high purity copper is used to manufacture pure copper target material or alloy target material.

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