Method for preparing high purity copper

Abstract

A high-purity copper preparation method comprises the following steps: first, using 4N cathode copper as an anode plate, using a titanium plate as a cathode plate, and using sulfuric acid as an electrolyte to perform periodic reversal direct current electrolysis to obtain 6N cathode copper; and then using the obtained 6N cathode copper as an anode plate, using a titanium plate as a cathode plate, and using nitric acid as an electrolyte to perform periodic reversal direct current electrolysis, thereby obtaining the high-purity copper. The Ag impurity content in the obtained copper plate is reduced through the sulfuric acid electrolysis system, and then the S impurity in the copper plate is reduced through the nitric acid system, so that high-purity copper can be obtained through two-step electrolysis. The high-purity copper has low impurity content, and the S content is lower than 0.005 ppm, and the Ag content is as low as 0.04 ppm.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cathode copper production, and particularly relates to a high-purity copper preparation method. BACKGROUND

[0002] The electrolytic refining method is the most basic and most commonly used method for preparing high-purity copper, and high-purity copper is usually prepared by suspending anode copper plates in an electrolyte and then electrolyzing.

[0003] The cathode copper produced by the existing electrolytic method is mostly prepared by using a sulfuric acid electrolytic system, and the prepared high-purity copper still contains a high content of S impurities, so that the cathode copper product is difficult to meet the demand of the electronic, communication, superconducting, aerospace and other high-tech fields for the purity of high-purity copper. SUMMARY

[0004] The application aims to provide a high-purity copper preparation method to solve the problem of high impurity content of cathode copper produced by the existing electrolytic method.

[0005] The application adopts the technical scheme of:

[0006] The application adopts the technical scheme of:

[0007] S1, using 4N cathode copper as an anode plate, using a titanium plate as a cathode plate, and using sulfuric acid as an electrolyte, periodic reverse direct current electrolysis is carried out to prepare 6N cathode copper;

[0008] S2, using the 6N cathode copper obtained in S1 as an anode plate, using a titanium plate as a cathode plate, and using nitric acid as an electrolyte, periodic reverse direct current electrolysis is carried out to obtain the high-purity copper.

[0009] Further, in S1, the concentration of sulfuric acid is 30g / L-50g / L, and the concentration of copper sulfate is 40-70g / L.

[0010] Further, in S2, the concentration of nitric acid is 30g / L-50g / L, and the concentration of copper nitrate is 60-80g / L.

[0011] Further, the current density of electrolysis in S1 and S2 is 100-200A / m 2

[0012] Further, the process of periodic reverse direct current electrolysis is as follows: 4-6 days of forward current, 40-50s of no current time, and 6-10s of reverse current.

[0013] Further, the titanium plate is composed of a plurality of sub-plates arranged at intervals and having side edges on a line, and the sub-plates at both sides and the sub-plates in the middle are regularly exchanged in position during the electrolysis process.

[0014] Further, the interval between the sub-plates is 100-200 mm.

[0015] Further, in S2, after electrolysis is completed, the copper plate is stripped from the cathode plate, and the high-purity copper is obtained after acid washing, water washing, and air drying.

[0016] Further, in S2, the acid washing uses 30-50 g / L nitric acid.

[0017] Further, in S2, the water washing process is: first washing with deionized water, and then washing with hot water above 60°C.

[0018] Advantages of the present application:

[0019] 1. The preparation method of the present application uses 4N copper as the anode, and 6N copper is obtained by electrolysis in a sulfuric acid electrolyte. Then, 6N copper is used as the anode, and the cathode copper product is obtained by electrolysis in a nitric acid electrolyte. The Ag impurity content in the obtained copper plate is reduced by the sulfuric acid electrolysis system, and then the S and other impurities in the copper plate are reduced by the nitric acid system, and the residual Ag in the copper plate is removed again. The obtained high-purity copper has low impurity content, with S content lower than 0.005 ppm and Ag content as low as 0.04 ppm.

[0020] 2. In the preparation method of the present application, during electrolysis, forward and reverse currents are used for periodic commutation electrolysis. When traditional electrolysis is carried out using the same direction current, S, Ag, and other impurities will preferentially deposit on the cathode copper plate, forming a spur-like structure. During electrolysis, copper will deposit on the spur-like structure, causing some impurities to remain in the copper product. By using reverse current to dissolve the impurities deposited on the cathode copper, the impurity residue in the cathode copper is reduced, effectively improving the quality of the prepared high-purity copper.

[0021] 3. In the preparation method of the present application, the cathode plate is modularly arranged, and the appropriate interval between the sub-plates is controlled. By adjusting the positions of the intermediate and edge anode plates, the surface flatness of the copper plate during electrolytic preparation of the cathode copper is further improved, thereby reducing the deposition of impurities in the copper plate. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The micro-surface schematic diagram of the high-purity copper prepared in Example 1;

[0023] Figure 2 The micro-surface schematic diagram of the high-purity copper prepared in Comparative Example 2 under the same magnification. Figure 1 DETAILED DESCRIPTION

[0024] ​In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0025] The present application provides a high-purity copper preparation method, comprising the following steps:

[0026] S1, using 4N cathode copper as anode plate, titanium plate as cathode plate, sulfuric acid as electrolyte, and performing periodic reversing direct current electrolysis under a current density of 100-200 A / m 2 to obtain 6N cathode copper;

[0027] S2, using the 6N cathode copper obtained in S1 as anode plate, titanium plate as cathode plate, nitric acid as electrolyte, and performing periodic reversing direct current electrolysis under a current density of 100-200 A / m 2 to obtain the high-purity copper.

[0028] In S1, the concentration of sulfuric acid is 30-50 g / L, and the concentration of copper sulfate is 40-70 g / L.

[0029] In S2, the concentration of nitric acid is 30-50 g / L, and the concentration of copper nitrate is 60-80 g / L.

[0030] The process of periodic reversing direct current electrolysis is as follows: 4-6 days of forward current, 40-50 seconds of no current, and 6-10 seconds of reverse current.

[0031] The titanium plate is composed of multiple sub-plates arranged in a line and spaced apart, and during the electrolysis process, the sub-plates on both sides are periodically exchanged with the sub-plates in the middle.

[0032] The spacing between the sub-plates is 100-200 mm.

[0033] In S2, after the electrolysis is completed, the copper plate is peeled off from the cathode plate, and the high-purity copper is obtained after acid pickling, water washing, and air drying.

[0034] In S2, the acid pickling uses 30-50 g / L nitric acid.

[0035] In S2, the water washing process is as follows: first, rinsing with deionized water, and then hot water washing at a temperature above 60°C.

[0036] Example 1:

[0037] The first step is sulfuric acid solution production. 4N cathode copper is used as an anode plate. The 4N electrolytic copper plate is processed into 450 mm x 360 mm by using hydraulic shearing method. Then, two holes with a diameter of φ10 are drilled on the width by using a bench drill. The copper plate is removed from the surface impurities, immersed in 3% to 5% sulfuric acid solution for pickling in a running tank, and then washed with water. After that, the copper plate is hung on the copper hook in the electrolytic tank. The titanium plate is used as the cathode plate, which can be selected from TA1 or TA2. The titanium plate is processed into 420 x 2 mm and hung on the titanium hook in the electrolytic tank. The electrolyte is 40 g / L sulfuric acid and 55 g / L copper sulfate. The periodic reverse direct current electrolysis is carried out at a current density of 150 A / m 2 The periodic reverse electrolysis process is as follows: 5 days of forward current, 45 s of no current, and 8 s of reverse current. To maintain the same liquid level, water is added once every half day to supplement the evaporated water. The supplement position is the marked position of the tank body. The drop-in method is used for water supplement, and the drop-in speed is about 100 drops per minute. To reduce the unevenness of the cathode copper during electrolysis, the titanium plate can be composed of multiple sub-plates with their side edges on a line and arranged at intervals. For example, the 420 mm x 2 mm titanium plate can be arranged as three 140 mm x 2 mm sub-plates. During electrolysis, the sub-plates on both sides are exchanged with the sub-plate in the middle every 12 h of reaction. That is, the positions of the three sub-plates are not fixed. After electrolysis, 6N ultra-pure copper is prepared. The copper plate hung in the tank after deposition is washed with flowing tap water three times for standby use.

[0038] The second step is nitric acid solution production. The 6N cathode copper prepared in the first step is used as the anode plate, and the titanium plate is used as the cathode plate. The titanium plate can be manufactured according to the manufacturing method in the first step. The electrolyte is 40 g / L nitric acid and 70 g / L copper nitrate. The periodic reverse direct current electrolysis is carried out at a current density of 150 A / m 2 After electrolysis, 7N ultra-pure copper is prepared. After electrolysis, the copper plate is peeled off from the cathode plate, and then sequentially pickled, washed with water, and dried to obtain the high-purity copper. The pickling is carried out using 30 to 50 grams per liter of nitric acid. The water washing process is first rinsed with deionized water and then scalded with hot water above 60°C to reduce oxidation during water washing.

[0039] Example 2:

[0040] The first step is sulfuric acid solution production. 4N cathode copper is used as an anode plate. The 4N electrolytic copper plate is processed into 450 mm x 360 mm by using hydraulic shearing method. Then, two holes with a diameter of φ10 are drilled on the width by using a drill. The copper plate is cleaned by removing surface impurities and is immersed in 3% to 5% sulfuric acid solution in a running tank. After water washing, the copper plate is hung on a copper hook in an electrolytic tank. A titanium plate is used as a cathode plate, which can be selected from TA1 or TA2. The titanium plate is processed into 420 x 2 mm and is hung on a titanium hook in the electrolytic tank. 30 g / L sulfuric acid and 40 g / L copper sulfate are used as electrolyte. Periodic reversal direct current electrolysis is carried out at a current density of 100 A / m 2 The periodic reversal electrolysis process is as follows: 4 days of forward current, 40 s of no current, and 6 s of reverse current. Water is added once every half day to supplement the evaporated water, and the supplement position is the marked position of the tank body. The water is added by dripping at a speed of about 100 drops per minute. In order to reduce the unevenness of the cathode copper during electrolysis, the titanium plate can be composed of multiple sub-plates arranged in a line and spaced apart. For example, the 420 mm x 2 mm titanium plate can be arranged as three 140 mm x 2 mm sub-plates. During electrolysis, the sub-plates on both sides are exchanged with the sub-plate in the middle every 12 h of reaction, i.e., the positions of the three sub-plates are not fixed. After electrolysis is completed, 6N ultra-pure copper is prepared. The copper plate hung in the tank after deposition is washed with flowing tap water three times for standby use.

[0041] The second step is nitric acid solution production. The 6N cathode copper prepared in the first step is used as an anode plate, and a titanium plate is used as a cathode plate. The titanium plate can be manufactured according to the manufacturing method in the first step. 30 g / L nitric acid and 60 g / L copper nitrate are used as electrolyte. Periodic reversal direct current electrolysis is carried out at a current density of 100 A / m 2 The electrolysis cycle is as follows: 4 days of forward current, 40 s of no current, and 6 s of reverse current. After electrolysis is completed, 7N ultra-pure copper is prepared. The copper plate is peeled off from the cathode plate after electrolysis is completed. After acid washing, water washing, and air drying, the high-purity copper is obtained. The acid washing is carried out by using 30 to 50 grams per liter of nitric acid. The water washing process is first rinsed with deionized water and then scalded with hot water above 60°C to reduce oxidation during water washing.

[0042] Example 3:

[0043] The first step is sulfuric acid solution production. 4N cathode copper is used as an anode plate. The 4N electrolytic copper plate is processed into 450 mm x 360 mm by using hydraulic shearing method. Then, two holes with a diameter of φ10 are drilled on the width by using a drill. The copper plate is cleaned by removing surface impurities and is immersed in 3% to 5% sulfuric acid solution in a running tank. After water washing, the copper plate is hung on a copper hook in an electrolytic tank. A titanium plate is used as a cathode plate, which can be selected from TA1 or TA2. The titanium plate is processed into 420 x 2 mm and is hung on a titanium hook in the electrolytic tank. Sulfuric acid with a concentration of 50 g / L and copper sulfate with a concentration of 70 g / L are used as electrolyte. Periodic reversal direct current electrolysis is carried out at a current density of 200 A / m 2 The periodic reversal electrolysis process is as follows: 6 days of forward current, 50 s of no current, and 10 s of reverse current. In order to keep the liquid level consistent, water is added once every half day to supplement the evaporated water. The water is added at a mark position of the tank body by using a dripping method at a speed of about 100 drops per minute. In order to reduce the unevenness of the cathode copper during electrolysis, the titanium plate can be composed of multiple sub-plates arranged in a line and spaced apart. For example, the titanium plate with a size of 420 mm x 2 mm can be arranged as three sub-plates with a size of 140 mm x 2 mm. During electrolysis, the sub-plates on both sides are exchanged with the sub-plate in the middle every 12 h of reaction. That is, the positions of the three sub-plates are not fixed. After electrolysis, 6N ultra-pure copper is prepared. The copper plate deposited in the tank is washed with deionized water and then with flowing tap water for three times for standby use.

[0044] The second step is nitric acid solution production. The 6N cathode copper prepared in the first step is used as an anode plate, and a titanium plate is used as a cathode plate. The titanium plate can be processed according to the method in the first step. Sulfuric acid with a concentration of 50 g / L and copper sulfate with a concentration of 80 g / L are used as electrolyte. Periodic reversal direct current electrolysis is carried out at a current density of 200 A / m 2 The electrolysis cycle is as follows: 6 days of forward current, 50 s of no current, and 10 s of reverse current. After electrolysis, 7N ultra-pure copper is prepared. The copper plate is peeled off from the cathode plate after electrolysis. The copper plate is sequentially subjected to acid washing, water washing, and air drying to obtain the high-purity copper. The acid washing is carried out by using nitric acid with a concentration of 30 to 50 g / L. The water washing process includes rinsing with deionized water and then hot water washing at a temperature of 60°C or higher to reduce oxidation during water washing.

[0045] Comparative Example 1

[0046] With 4N cathode copper as anode plate, 4N electrolytic copper plate is processed into 450mmx360mm by hydraulic shearing method, then two holes with diameter of φ10 are drilled on the width by a drill, the copper plate is removed from surface impurities, immersed into 3% to 5% sulfuric acid solution for pickling in a running tank, then washed with water, and hung on copper hooks in an electrolytic tank, with titanium plate as cathode plate, the titanium plate can be the one in embodiment 1, and can be selected from TA1 or TA2 brand, hung on titanium plate hooks in the electrolytic tank, with 40g / L sulfuric acid, 55g / L copper sulfate, 40g / L nitric acid and 70g / L copper nitrate as electrolyte, and subjected to periodic reverse direct current electrolysis at a current density of 150A / m 2 The periodic reverse electrolysis process is as follows: 5 days of forward current, 45s of no current, 8s of reverse current, water is added once every half day to supplement the volatilized water to keep the liquid level consistent, the water is added by dripping at a speed of about 100 drops per minute, in order to reduce the unevenness of the cathode copper during electrolysis, the titanium plate can be composed of multiple sub-plates with their side edges arranged in a line and spaced apart, for example, a 420mmx2mm titanium plate can be arranged into three 140mmx2mm sub-plates, during electrolysis, the sub-plates on both sides are exchanged with the sub-plate in the middle every 12h of reaction, that is, the positions of the three sub-plates are not fixed, after electrolysis, ultra-pure copper is prepared.

[0047] Comparative Example 2

[0048] The difference from embodiment 1 is that, during electrolysis, periodic reverse direct current electrolysis is not used, and electrolysis is carried out at a current density of 150A / m 2 with a single current direction.

[0049] The cathode copper products obtained in embodiment 1 and comparative example 2 are observed microscopically, as shown in Figure 1 and Figure 2 , the surface of the cathode copper obtained in embodiment 1 is obviously smoother than that of the cathode copper product obtained in comparative example 2, the impurity content of the cathode copper products obtained in embodiments 1-3, 6N cathode copper obtained in embodiment 1 and the cathode copper products obtained in comparative examples 1-2 is analyzed and detected, and the detection results are shown in table 1.

[0050] Table 1: Impurity content detection results of cathode copper products obtained in embodiments 1-3 and comparative examples 1-3

[0051]

[0052] It should be noted that the above embodiments are only used to illustrate the present application, but the present application is not limited to the above embodiments, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application all fall within the protection scope of the present application.

Claims

1. A method for preparing high-purity copper, characterized in that, Includes the following steps: S1. Using 4N copper cathode as the anode and a titanium plate as the cathode, and sulfuric acid and copper sulfate as the electrolyte, 6N copper cathode was prepared by periodic reversing direct current electrolysis; the concentration of sulfuric acid was 30 g / L to 50 g / L, and the concentration of copper sulfate was 40 to 70 g / L; the electrolysis current density was 100 to 200 A / m. 2 The process of cyclic reversing DC electrolysis is as follows: 4-6 days of forward current, 40-50 seconds of no current time, and 6-10 seconds of reverse current. S2. Using the 6N cathode copper obtained in S1 as the anode plate and a titanium plate as the cathode plate, and nitric acid and copper nitrate as the electrolyte, periodic reversed direct current electrolysis is performed to obtain the high-purity copper; the concentration of nitric acid is 30 g / L to 50 g / L, and the concentration of copper nitrate is 60 to 80 g / L; the current density of electrolysis is 100 to 200 A / m. 2 The process of cyclic reversing DC electrolysis is as follows: 4-6 days of forward current, 40-50 seconds of no current time, and 6-10 seconds of reverse current. The titanium plate is composed of multiple sub-plates with their side edges aligned on a line and spaced apart. During the electrolysis process, the sub-plates on both sides are periodically swapped with the sub-plate in the middle, with a spacing of 100-200 mm between the sub-plates.

2. The method for preparing high-purity copper as described in claim 1, characterized in that, In S2, after electrolysis is completed, a copper plate is obtained by peeling off the cathode plate, and then subjected to acid washing, water washing and air drying to obtain the high-purity copper.

3. The method for preparing high-purity copper as described in claim 2, characterized in that, In S2, the pickling process uses 30-50 g / L of nitric acid.

4. The method for preparing high-purity copper as described in claim 2, characterized in that, In S2, the water washing process is as follows: first rinse with deionized water, then scald with hot water above 60°C.

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