Method for preparing high-purity cobalt through deep purification and cyclic electrodeposition

Abstract

The invention provides a method for preparing high-purity cobalt through deep purification and circulating electrodeposition, which comprises the following steps: carrying out deep purification on a cobalt stock solution through macroporous styrene-divinylbenzene chelate resin and at least one styrene anion exchange resin in sequence to remove main control impurity elements Fe, Cu and Ni, and then carrying out circulating dynamic electrodeposition refining at the flow rate of 10-50L / h to obtain high-purity cobalt. And a cobalt layer is deposited on the titanium plate cathode, and a high-purity cobalt plate product with the purity being 99.999% or above is obtained after the deposited cobalt layer is stripped and cleaned with pure water. Through the synergistic effect of multiple resin deep impurity removal and dynamic circulation electrodeposition, the content of impurities Fe and Cu is as low as 0.00001 g / L, the content of impurity Ni is as low as 0.00005 g / L, the content difference of the impurities on the upper portion and the lower portion of the prepared high-purity cobalt plate is smaller than or equal to 100 ppb, the problem of uneven distribution of static electrodeposition is solved, the method has the advantages of being short in technological process, easy and convenient to operate and excellent in product uniformity, and the requirement for cobalt materials for integrated circuits is met.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of hydrometallurgical preparation of cobalt, and particularly relates to a method for preparing high-purity cobalt through deep purification and cyclic electrodeposition. BACKGROUND

[0002] High-purity cobalt has excellent electromigration resistance, magnetic properties and electrical conductivity, and is an important material for preparing magnetic recording materials, superalloys and integrated circuit components. Cobalt with a purity of 99.9%-99.99% is widely used in the manufacture of magnetic materials and superalloys, while cobalt with a purity of 99.999% or even higher is mainly used as a sputtering target for the integrated circuit industry to react with a silicon substrate to form cobalt silicide, which is used in the manufacture of integrated circuit contact layer materials.

[0003] The preparation process of high-purity cobalt mainly includes two steps of deep purification of cobalt solution and electrodeposition refining. Deep purification of cobalt solution is to remove Ni, Fe, Cu and other main impurity elements that are difficult to separate during electrodeposition refining of cobalt solution. The existing deep purification methods of cobalt solution mainly include extraction, membrane separation and ion exchange. The extraction method has good effects on most metal ions, but the separation effect on trace Ni and Cu metal ions is poor. The membrane separation method has the disadvantages of poor stability and high cost. The ion exchange method has good separation effect on elements with similar properties. Electrodeposition refining is to deposit cobalt from the purified cobalt-containing solution to obtain high-purity cobalt plate. Currently, Fe, Ni, Cu and other impurity elements have similar deposition potentials with cobalt at very low concentrations. In this case, it is difficult to prepare high-purity cobalt plate from the cobalt electrodeposition solution. Currently, static electrodeposition is generally used for electrodeposition refining of cobalt solution, but it causes concentration difference between the upper and lower parts of the cobalt electrodeposition solution, resulting in different polarization degrees of the upper and lower parts of the high-purity cobalt plate during growth, and uneven distribution of impurity content in the high-purity cobalt plate. SUMMARY

[0004] The purpose of the present application is to overcome the problems in the prior art and provide a high-purity cobalt preparation method. The method uses at least one chelating resin and at least one ion exchange resin to deeply remove impurities from cobalt stock solution, and uses a cyclic dynamic electrodeposition method to prepare high-purity cobalt plate with uniform quality, so that the high-purity cobalt plate meets the purity requirements of integrated circuits.

[0005] In order to achieve the above purpose, the present application provides the following technical solutions.

[0006] A method for preparing high-purity cobalt through deep purification and cyclic electrodeposition, comprising the following steps:

[0007] (a) deep purification: the cobalt stock solution is sequentially flowed through a chelating resin column and at least one anion exchange resin column arranged in series at a flow rate of 1-3 BV / h, wherein: the chelating resin is a macroporous styrene-divinylbenzene (DVB) chelating resin, and the anion exchange resin is a macroporous styrene anion exchange resin, and the Fe, Cu and Ni main control impurities are removed by multiple adsorption to make the concentrations of Fe, Cu and Ni in the purified cobalt solution each ≤0.0001 g / L;

[0008] (b) cyclic electrodeposition: the purified cobalt solution is injected into an electrodeposition tank, and a peristaltic pump is started to make the purified cobalt solution flow at a flow rate of 10-50 L / h in a closed loop system composed of the electrodeposition tank and a circulating tank, the current density is controlled to be 50-100 A / m2, and a cobalt layer is deposited on a titanium plate cathode;

[0009] (c) cathode treatment: after the electrodeposition is completed, the cathode plate with the deposited cobalt layer is removed, and the cobalt plate on the cathode plate is peeled off;

[0010] (d) pure water cleaning: the peeled-off cobalt plate is rinsed with pure water, and a high-purity cobalt plate is finally obtained, wherein the difference in the content of each of the main control impurity elements Fe, Cu and Ni between the upper and lower parts of the obtained high-purity cobalt plate is ≤100 ppb.

[0011] Preferably, the chelating resin and the anion exchange resin in step (a) are arranged in series in the order of the chelating resin column first and then the anion exchange resin column, the anion exchange resin has two types, which are a styrene anion exchange resin containing a quaternary amine group functional group and a styrene anion exchange resin containing a tertiary quaternary amine group functional group, and when the flow rate is 1 BV / h, the concentrations of Fe and Cu in the purified cobalt solution are ≤0.00001 g / L, and the concentration of Ni is ≤0.00005 g / L.

[0012] Preferably, the macroporous chelating resin in step (a) has a pore size ≥50 nm, and the macroporous anion exchange resin has a pore size ≥30 nm, and the cobalt stock solution has a cobalt content of 110-130 g / L.

[0013] Preferably, in step (b), the dynamic circulation flow rate is 30 L / h, the current density is 70-90 A / m2, the electrodeposition temperature is 40-50℃, the electrodeposition solution pH value is 1-3, the electrode spacing is 10-15 cm, the anode uses a titanium coated ruthenium mesh, and the cathode uses a titanium plate. 2

[0014] Preferably, the electrodeposited cobalt plate in step (b) has a growth period of 15 days.

[0015] Preferably, the pure water used in step (d) has a resistivity ≥18 MΩ·cm, the cleaning method is ultrasonic cleaning, and the purity of the finally obtained high-purity cobalt plate is ≥99.999%.

[0016] ​The beneficial effects of the present application are that: the purification method of high-purity cobalt with cobalt stock solution adopts a chelating resin and at least one ion exchange resin to deeply remove impurities from the cobalt stock solution, and the Fe and Cu contents in the prepared cobalt electrodeposition solution can be controlled to a level of 0.00001 g / L at the lowest, and the Ni content can be controlled to a level of 0.00005 g / L at the lowest; the high-purity cobalt prepared by the dynamic circulation electrodeposition method solves the problem of uneven distribution of impurity contents in the upper and lower parts of the plate in the high-purity cobalt prepared by static electrodeposition, so that the impurity content difference between the upper and lower parts is within 100 ppb; the process flow of the present application is short, the operation is simple, and the internal quality uniformity of the obtained high-purity cobalt is good. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 Process flow chart for preparing high-purity cobalt by deep purification and circulation electrodeposition of the present application DETAILED DESCRIPTION

[0018] Example 1

[0019] Macroporous styrene DVB chelating resin A (pore size 50 nm) and quaternary ammonium styrene anion exchange resin B (pore size 30 nm) were respectively packed into columns, and three parts of cobalt stock solution containing 100 g / L of cobalt were taken, which were respectively flowed through the chelating resin column and the anion exchange resin column in series at a flow rate of 1 BV / h, 2 BV / h and 3 BV / h in turn to obtain purified cobalt solution, and the ICP-MS detection results are shown in Table 1. At a flow rate of 1 BV / h, the purification effect of Fe, Cu and Ni impurity elements in the purified cobalt solution is better.

[0020] Table 1 Detection results of cobalt electrodeposition solution after purification of chelating resin A and ion exchange resin B

[0021]

[0022]

[0023] The three parts of the above purified cobalt solution were respectively injected into three different electrodeposition tanks, and the peristaltic pump was started to perform dynamic electrodeposition at a circulation flow rate of 10 L / h, 30 L / h and 50 L / h respectively, so that the purified cobalt solution was dynamically circulated in the closed loop system composed of the electrodeposition tank and the circulation tank, and the titanium coated ruthenium mesh anode and the titanium plate cathode were used, the distance between the anode and the cathode was 10 cm, the current density was controlled to be 80 A / m 2 , the temperature was 45±2℃, the PH value was 1-3, and after electrodeposition for 15 days, the cathode deposited a cobalt layer with a thickness of 2-3 mm.

[0024] The cathode plate was removed and mechanically stripped of the cobalt plate. After ultrasonic cleaning (40 kHz, 30 min) in 18.2 MΩ·cm pure water and nitrogen drying, high-purity cobalt was prepared. GDMS detection showed that the purity of the cobalt plate was 99.9995%, and the content difference of Fe, Cu and Ni impurity elements between the upper and lower parts of the high-purity cobalt plate was shown in Table 2. Among them, when the cobalt electrodeposition liquid circulation flow rate was close to static electrodeposition at 10 L / h, the content difference of impurity elements was larger; when the cobalt electrodeposition liquid circulation flow rate was 30 L / h, the content difference of impurities between the upper and lower parts of the cobalt plate was smaller; when the cobalt electrodeposition liquid circulation flow rate was 50 L / h, the flow rate was fast, the distribution of impurity elements in the electrodeposition liquid was disturbed, and the content difference of impurities between the upper and lower parts of the process cobalt plate was larger, verifying the elimination effect of suitable dynamic circulation flow rate on the impurity concentration gradient.

[0025] Table 2 Detection results of high-purity cobalt plate prepared by dynamic circulation electrodeposition after purification by chelating resin A and ion exchange resin B

[0026]

[0027] Example 2

[0028] The macroporous styrene DVB chelating resin A (pore size 50 nm) and the tertiary amine group styrene anion exchange resin C (pore size 40 nm) were respectively packed into columns, and three parts of cobalt solution containing 110 g / L of cobalt were taken and flowed through the chelating resin column and the anion exchange resin column in series at flow rates of 1 BV / h, 2 BV / h and 3 BV / h respectively to obtain purified cobalt liquid. The ICP-MS detection results are shown in Table 3. At a flow rate of 1 BV / h, the purification effect of Fe, Cu and Ni impurity elements in the purified cobalt liquid is better.

[0029] Table 3 Detection results of cobalt electrodeposition liquid after purification by chelating resin A and ion exchange resin C

[0030]

[0031] The three parts of the aforementioned purified cobalt liquid were respectively injected into three different electrodeposition tanks, and dynamic electrodeposition was carried out at circulation flow rates of 10 L / h, 30 L / h and 50 L / h respectively by opening the peristaltic pump to make the purified cobalt liquid dynamically circulate in the closed loop system composed of the electrodeposition tank and the circulation tank. A titanium-coated ruthenium mesh anode and a titanium plate cathode were used, the distance between the anode and the cathode was 13 cm, the current density was controlled at 80 A / m 2 , the temperature was 40±2℃, the pH value was 1-3, and after 15 days of electrodeposition, a 2-3 mm thick cobalt layer was deposited on the cathode.

[0032] The cathode plate was removed and mechanically stripped of the cobalt plate. After ultrasonic cleaning (40 kHz, 30 min) in 18 MΩ·cm pure water and nitrogen drying, high-purity cobalt was obtained. GDMS detection showed that the purity of the cobalt plate was 99.9992%, and the content difference of Fe, Cu and Ni impurity elements between the upper and lower parts of the high-purity cobalt plate was as shown in Table 4. Among them, when the cobalt electrodeposition liquid circulation flow rate was close to static electrodeposition at 10 L / h, the content difference of impurity elements was larger; when the cobalt electrodeposition liquid circulation flow rate was 30 L / h, the content difference of impurity elements between the upper and lower parts of the cobalt plate was smaller; when the cobalt electrodeposition liquid circulation flow rate was 50 L / h, the flow rate was fast, the distribution of impurity elements in the electrodeposition liquid was disturbed, and the content difference of impurity elements between the upper and lower parts of the process cobalt plate was larger, verifying the elimination effect of suitable dynamic circulation flow rate on the impurity concentration gradient.

[0033] Table 4 Detection results of high-purity cobalt plate prepared by dynamic circulation electrodeposition after purification by chelating resin A and ion exchange resin C

[0034]

[0035] Example 3

[0036] The macroporous styrene DVB chelating resin A (pore size 50 nm), quaternary ammonium styrene anion exchange resin B (pore size 30 nm) and tertiary amine styrene anion exchange resin C (pore size 40 nm) were respectively packed into columns, and three portions of cobalt solution containing 120 g / L of cobalt were taken and sequentially flowed through the chelating resin column and the anion exchange resin column in series at flow rates of 1 BV / h, 2 BV / h and 3 BV / h, respectively, to obtain purified cobalt liquid. The ICP-MS detection results are shown in Table 5. At a flow rate of 1 BV / h, the purification effect of Fe, Cu and Ni impurity elements in the purified cobalt liquid was better.

[0037] Table 5 Detection results of cobalt electrodeposition liquid after purification by chelating resin A and ion exchange resins B and C

[0038]

[0039] The three portions of the aforementioned purified cobalt liquid were respectively injected into three different electrodeposition tanks, and dynamic electrodeposition was carried out at circulation flow rates of 10 L / h, 30 L / h and 50 L / h by opening the peristaltic pump, so that the purified cobalt liquid was dynamically circulated in the closed loop system composed of the electrodeposition tank and the circulation tank. A titanium-coated ruthenium mesh anode and a titanium plate cathode were used, the distance between the anode and the cathode was 10 cm, the current density was controlled at 80 A / m 2 , the temperature was 50±2℃, the pH value was 1-3, and after electrodeposition for 15 days, a cobalt layer with a thickness of 2-3 mm was deposited on the cathode.

[0040] The cathode plate was removed and mechanically stripped of the cobalt plate. The cobalt plate was cleaned ultrasonically (40 kHz, 30 min) in 18 MΩ·cm pure water and dried with nitrogen to obtain high-purity cobalt. GDMS detection showed that the purity of the cobalt plate was 99.9999%. The difference in the content of Fe, Cu and Ni impurity elements between the upper and lower parts of the high-purity cobalt plate is shown in Table 6. When the circulating flow rate of the cobalt electrodeposition solution was 10 L / h, the impurity element content difference was large because the cobalt electrodeposition was close to static electrodeposition. When the circulating flow rate of the cobalt electrodeposition solution was 30 L / h, the impurity element content difference between the upper and lower parts of the cobalt plate was small. When the circulating flow rate of the cobalt electrodeposition solution was 50 L / h, the flow rate was fast, the distribution of the impurity elements in the electrodeposition solution was disturbed, and the impurity element content difference between the upper and lower parts of the process cobalt plate was large, verifying the effect of the appropriate dynamic circulating flow rate on the elimination of the impurity concentration gradient.

[0041] Table 6 Test results of high-purity cobalt plates prepared by dynamic circulation electrodeposition after purification by chelating resin A and ion exchange resin B

[0042]

[0043] The above description is merely preferred embodiments of the present application, and any simple modification, equivalent change and modification made according to the technical essence of the present application to the above embodiments all fall within the protection scope of the present application.

Claims

1. A method for preparing high-purity cobalt by deep purification cyclic electrowinning, characterized in that: The following steps are involved: (a) deep purification: the cobalt stock solution is passed through a chelate resin column and at least one anion exchange resin column arranged in series at a flow rate of 1-3 BV / h, wherein the chelate resin is a macroporous styrene-divinylbenzene (DVB) chelate resin and the anion exchange resin is a macroporous styrene anion exchange resin, and the main controlling impurities of Fe, Cu, and Ni are removed by multiple adsorption to make the concentrations of Fe, Cu, and Ni in the purified cobalt solution ≤0.0001 g / L; (b) Circulating electrolysis: The purified cobalt solution is injected into the electrolysis tank, and the peristaltic pump is turned on to circulate the purified cobalt solution dynamically in the closed loop system composed of the electrolysis tank and the circulation storage tank at a flow rate of 10–50 L / h. The current density is controlled at 50–100 A / m 2 , depositing a cobalt layer on a titanium plate cathode; (c) Cathode treatment: After the electrodeposition is completed, the cathode plate with the deposited cobalt layer is removed and the cobalt plate on the cathode plate is peeled off; (d) Pure water cleaning: The stripped cobalt plate is rinsed with pure water to obtain a high-purity cobalt plate, wherein the difference in the content of each of the main controlling impurity elements, Fe, Cu, and Ni, between the upper and lower parts of the cobalt plate is ≤100 ppb.

2. The method according to claim 1, wherein: In the step (a), the chelating resin and the anion exchange resin are connected in series in the order of first connecting the chelating resin column and then the anion exchange resin column. There are two types of anion exchange resins, namely, a styrene anion exchange resin containing a quaternary amino functional group and a styrene anion exchange resin containing a tertiary quaternary amino functional group. When the flow rate is 1 BV / h, the Fe and Cu concentrations in the cobalt electrolyte after purification are ≤0.00001 g / L, and the Ni concentration is ≤0.00005 g / L.

3. The method according to claim 2, wherein: In the step (a), the pore size of the macroporous chelating resin is ≥50 nm, the pore size of the macroporous anion exchange resin is ≥30 nm, and the cobalt stock solution contains 100-120 g / L of cobalt.

4. The method according to claim 1, wherein: In the step (b), the dynamic circulation flow rate is 30 L / h, the current density is 70-90 A / m2, the electrolysis temperature is 40-50°C, the pH value of the electrolysis solution is 1-3, the electrode spacing is 10-15 cm, the anode is a titanium-coated ruthenium mesh, and the cathode is a titanium plate.

5. The method according to claim 4, wherein: The growth period of the electrolytic cobalt plate in step (b) is 15 days.

6. The method according to claim 1, wherein: The resistivity of the pure water used in step (d) is ≥18 MΩ·cm, and the cleaning method is ultrasonic cleaning. The purity of the high-purity cobalt plate finally obtained is ≥99.999%.

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