A method for producing electrolytic cobalt using multi-stage electrolysis

Abstract

The present application relates to a kind of preparation electrolytic cobalt with multistage electrolysis method, belong to hydrometallurgy technical field.The present application is first broken and is handled solid raw material containing cobalt, and powder is prepared by being ground sufficiently, this step increases the contact area of raw material and inorganic acid solution, and improves the dissolution efficiency;Cobalt-containing solid powder is dissolved in inorganic acid solution, and electrolyte containing cobalt ion is formed;Through the treatment such as the filtration of modified nanofiltration membrane, the addition of hydrogen peroxide and polyacrylamide, impurity ions in mixed solution are effectively removed, and the purity of cobalt ion is improved;First electrolysis step uses insoluble anode to electrolyze, can deposit rough electrolytic cobalt on cathode, realizes the preliminary purification of cobalt;Second electrolysis uses sulfuric acid-hydrochloric acid mixed acid solution as electrolyte, further removes the impurities in rough electrolytic cobalt, and high-purity electrolytic cobalt is obtained.

Description

Technical Field

[0001] This invention belongs to the field of hydrometallurgical technology and relates to a method for preparing electrolytic cobalt using multi-stage electrolysis. Background Technology

[0002] Electrolytic cobalt is a high-purity, high-quality cobalt material widely used in precision instruments, cemented carbide, welding industry, lithium batteries, thermocouples, high-strength steel alloys, powder metallurgy, and many other fields. Particularly in the automotive, aerospace, medical, chemical, and energy industries, electrolytic cobalt, due to its excellent corrosion resistance and stability under high temperature and pressure conditions, has become a crucial material for manufacturing key components.

[0003] Multi-stage electrolytic cobalt preparation is a technology that improves cobalt purity through multiple electrolytic refining processes. In the preparation process, the cobalt-containing raw material is first converted into a cobalt salt solution through crushing and dissolving steps, and then subjected to multi-stage electrolysis in a series of electrolytic cells. Each stage of electrolysis aims to remove impurity ions from the solution, increasing the purity of cobalt ions, and ultimately depositing high-purity electrolytic cobalt on the cathode. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing electrolytic cobalt using multi-stage electrolysis, which has the characteristic of high purity.

[0005] The objective of this invention can be achieved through the following technical solutions:

[0006] A method for preparing electrolytic cobalt using multi-stage electrolysis, the specific process of which is as follows:

[0007] S1: The cobalt-containing solid raw material is crushed and ground in a ball mill at a speed of 500-600 r / min for 4-5 hours to obtain powder A;

[0008] S2: Dissolve powder A in a 10% inorganic acid solution, wherein the solid-liquid mass ratio of powder A to inorganic acid solution is 1:(5~10), to obtain mixed solution B;

[0009] S3: Pass the mixed solution B through a modified nanofiltration membrane, collect the concentrate, add 1-2 wt% hydrogen peroxide to the concentrate, stir for 1-2 h, add 1 wt% polyacrylamide after stirring, continue stirring for 0.5 h, filter to obtain mixed solution C;

[0010] S4: Inject the mixed solution C into the electrolytic cell and perform the first electrolysis using an insoluble anode to obtain crude electrolytic cobalt;

[0011] S5: The crude electrolytic cobalt obtained from the first electrolysis is washed with deionized water and then dried at 80°C for 8 hours to remove impurities and moisture adhering to the surface.

[0012] S6: The crude electrolytic cobalt is subjected to secondary electrolysis. The electrolytic solution is a 10% sulfuric acid-hydrochloric acid mixed acid solution. Metallic cobalt is used as the cathode and crude electrolytic cobalt is used as the anode to further remove impurities and obtain high-purity electrolytic cobalt.

[0013] S7: The obtained electrolytic cobalt is purged with nitrogen for 12 hours. After purging, it is crushed and ground to obtain the electrolytic cobalt.

[0014] Furthermore, the inorganic acid solution in S2 is one of nitric acid, sulfuric acid, or hydrochloric acid.

[0015] Furthermore, the method for preparing the modified nanofiltration membrane in S3 is as follows:

[0016] S3.1: Dissolve graphene oxide in deionized water to prepare a 20% graphene oxide solution D;

[0017] S3.2: Mix graphene oxide solution D and 50% carboxybetaine solution at a volume ratio of 1:1 to obtain mixed solution E;

[0018] S3.3: Immerse the polyamide membrane in mixed solution E for 12 hours at a temperature of 40°C, and dry it at room temperature after immersion to obtain the modified nanofiltration membrane.

[0019] Furthermore, the permeation pressure of the modified nanofiltration membrane in S3 is 0.25–1 MPa.

[0020] Furthermore, the insoluble anode material in S4 is one of carbon, lead, graphite, and stainless steel.

[0021] Furthermore, the parameters for the first electrolysis in S4 are an electrolysis temperature of 55–65°C and a current density of 300–400 A / m. 2 The electrolysis voltage is 1.6–2.2V, and the electrolysis time is 3–4 hours.

[0022] Furthermore, in the sulfuric acid-hydrochloric acid mixed acid solution in S6, the volume ratio of sulfuric acid to hydrochloric acid is 1:1.

[0023] Furthermore, the parameters for the second electrolysis in S6 are an electrolysis temperature of 50–65°C and a current density of 400–500 A / m. 2 The electrolysis voltage is 1.8–2.0V, and the electrolysis time is 4–6h.

[0024] Furthermore, the nitrogen purging flow rate in S7 is 10 m / s.

[0025] This invention employs multi-stage electrolytic purification to effectively remove impurities from cobalt-containing solid raw materials, resulting in high-purity electrolytic cobalt. The electrolytic cobalt prepared by this method has a uniform deposition layer, a smooth surface, and is free of cracks and pores, exhibiting excellent physical properties.

[0026] This invention first crushes cobalt-containing solid raw materials, commonly copper-cobalt ore and nickel-cobalt ore, and grinds them into powder. This step increases the contact area between the raw material and the inorganic acid solution, improving the dissolution efficiency. The cobalt-containing solid powder is then dissolved in the inorganic acid solution to form a mixed solution containing cobalt ions, providing the necessary electrolyte for the subsequent electrolysis process. This invention effectively removes impurity ions from the mixed solution and improves the purity of cobalt ions through modified nanofiltration membrane filtration and the addition of hydrogen peroxide and polyacrylamide. The first electrolysis step uses an insoluble anode, which deposits crude electrolytic cobalt on the cathode, achieving preliminary purification of cobalt. The second electrolysis uses a sulfuric acid-hydrochloric acid mixed acid solution as the electrolyte to further remove impurities from the crude electrolytic cobalt, yielding high-purity electrolytic cobalt. Finally, nitrogen purging removes residual gases and impurities from the surface of the electrolytic cobalt, and crushing and grinding bring the electrolytic cobalt to the required particle size, improving product quality and application value.

[0027] Modified nanofiltration membranes possess finer pore sizes and superior separation performance, effectively intercepting tiny particles and impurity ions in solutions, thereby improving filtration efficiency. This invention improves the surface properties of the nanofiltration membrane through modification treatment, reducing the adsorption and deposition of contaminants on the membrane surface, thus enhancing the membrane's fouling resistance. The modified nanofiltration membrane exhibits better selective permeability to cobalt ions and other impurity ions, more effectively retaining cobalt ions while removing impurities during the filtration process.

[0028] Graphene oxide possesses abundant oxygen-containing functional groups, such as hydroxyl and carboxyl groups, which can interact with the nanofiltration membrane surface, improving the membrane's hydrophilicity and separation performance. Carboxybetaine, an amphoteric compound, exhibits excellent antifouling properties. Mixing it with graphene oxide further improves the surface properties of the nanofiltration membrane, reducing pollutant adsorption on the membrane surface. The mixed solution of graphene oxide and carboxybetaine can be uniformly coated onto the nanofiltration membrane surface, bonding with it through physical adsorption and chemical bonding to form a modified layer. This modified layer not only improves the filtration accuracy and separation performance of the nanofiltration membrane but also enhances its antifouling resistance and selective permeability.

[0029] Hydrogen peroxide, as a strong oxidant, can effectively oxidize some impurity ions in the solution. Therefore, through the oxidation of hydrogen peroxide, it reacts with impurity ions in a redox reaction, converting them into a more easily removed form or causing them to precipitate directly, thereby purifying the solution. This can further purify the cobalt salt solution and improve the purity of cobalt ions, creating more favorable conditions for the subsequent electrolysis process. Polyacrylamide, a high-molecular-weight flocculant, can aggregate tiny particles and impurity ions in the solution into larger flocs through adsorption and bridging, facilitating subsequent filtration operations and further purifying the cobalt salt solution, thus improving the purity of cobalt ions.

[0030] The first electrolysis reduces cobalt ions in the purified cobalt salt solution to metallic cobalt at the cathode, yielding crude electrolytic cobalt. Through electrolysis, cobalt ions in the solution are effectively converted into metallic cobalt, achieving preliminary purification of cobalt. Simultaneously, electrolysis removes some impurities, improving the purity of cobalt. During electrolysis, a reduction reaction occurs at the cathode, where cobalt ions accept electrons and are reduced to metallic cobalt. Due to the selectivity of electrolysis, most impurity ions are not reduced at the cathode, thus achieving separation of cobalt from impurities.

[0031] The second electrolysis further removes impurities from the crude electrolytic cobalt, yielding electrolytic cobalt of higher purity. Through this secondary electrolysis, the crude electrolytic cobalt can be further purified, removing trace impurities and achieving even higher purity. This helps improve the quality and application value of electrolytic cobalt. In the secondary electrolysis process, a sulfuric acid-hydrochloric acid mixed solution is used as the electrolyte. This electrolyte has a certain dissolving ability for impurities. Simultaneously, due to the selectivity of electrolysis, impurity ions may undergo oxidation at the anode and be removed, while cobalt ions are reduced to metallic cobalt at the cathode. Through the further purification effect of the secondary electrolysis, even higher purity electrolytic cobalt can be obtained.

[0032] The beneficial effects of this invention are:

[0033] (1) The modified nanofiltration membrane used in the preparation process of this invention has a finer filtration pore size and better separation performance, which can effectively intercept tiny particles and impurity ions in the solution, thereby improving filtration efficiency. Through modification treatment, the surface properties of the nanofiltration membrane are improved, reducing the adsorption and deposition of pollutants on the membrane surface, thereby enhancing the membrane's resistance to fouling. The modified nanofiltration membrane has better selective permeability to cobalt ions and other impurity ions, and can more effectively retain cobalt ions while removing impurities during the filtration process.

[0034] (2) The present invention has undergone multi-stage electrolytic purification treatment, which effectively removes impurities from cobalt-containing solid raw materials and obtains electrolytic cobalt with higher purity. Detailed Implementation

[0035] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features, and effects of the present invention, in conjunction with embodiments, is provided below.

[0036] Example 1

[0037] S1: The copper-cobalt ore is crushed and ground in a ball mill at a speed of 550 r / min for 5 hours to obtain powder A;

[0038] S2: Dissolve powder A in a 10% nitric acid solution, wherein the solid-liquid mass ratio of powder A to inorganic acid solution is 1:8, to obtain mixed solution B;

[0039] S3: Pass the mixed solution B through a modified nanofiltration membrane with a permeation pressure of 0.5 MPa, collect the concentrate, add 1 wt% hydrogen peroxide to the concentrate, stir for 1 h, add 1 wt% polyacrylamide after stirring, continue stirring for 0.5 h, filter to obtain mixed solution C;

[0040] The modified nanofiltration membrane is prepared as follows:

[0041] S3.1: Dissolve graphene oxide in deionized water to prepare a 20% graphene oxide solution D;

[0042] S3.2: Mix graphene oxide solution D and 50% carboxybetaine solution at a volume ratio of 1:1 to obtain mixed solution E;

[0043] S3.3: Immerse the polyamide membrane in mixed solution E for 12 hours at a temperature of 40°C, and dry it at room temperature after immersion to obtain the modified nanofiltration membrane.

[0044] S4: Inject the mixed solution C into the electrolytic cell and perform the first electrolysis using insoluble graphite anode. The parameters for the first electrolysis are: electrolysis temperature 60℃, current density 350A / m³. 2 The electrolysis voltage was 2V and the electrolysis time was 3h to obtain crude electrolytic cobalt;

[0045] S5: The crude electrolytic cobalt obtained from the first electrolysis is washed with deionized water and then dried at 80°C for 8 hours to remove impurities and moisture adhering to the surface.

[0046] S6: The crude electrolytic cobalt undergoes a second electrolysis. The parameters for the second electrolysis are: electrolysis temperature 65℃, current density 450A / m³. 2The electrolysis voltage is 1.8V, the electrolysis time is 4h, and the electrolysis solution is a 10% sulfuric acid-hydrochloric acid mixed acid solution with a volume ratio of sulfuric acid to hydrochloric acid of 1:1. Metallic cobalt is used as the cathode and crude electrolytic cobalt is used as the anode to further remove impurities and obtain high-purity electrolytic cobalt.

[0047] S7: The obtained electrolytic cobalt is purged with nitrogen gas at a flow rate of 10 m / s for 12 h. After purging, the cobalt is crushed and ground to obtain the electrolytic cobalt.

[0048] Example 2

[0049] S1: The nickel-cobalt ore is crushed and ground in a ball mill at a speed of 500 r / min for 4 hours to obtain powder A;

[0050] S2: Dissolve powder A in a 10% sulfuric acid solution, wherein the solid-liquid mass ratio of powder A to inorganic acid solution is 1:10, to obtain mixed solution B;

[0051] S3: Pass the mixed solution B through a modified nanofiltration membrane with a permeation pressure of 1 MPa, collect the concentrate, add 2 wt% hydrogen peroxide to the concentrate, stir for 2 h, add 1 wt% polyacrylamide after stirring, continue stirring for 0.5 h, filter to obtain mixed solution C;

[0052] The modified nanofiltration membrane is prepared as follows:

[0053] S3.1: Dissolve graphene oxide in deionized water to prepare a 20% graphene oxide solution D;

[0054] S3.2: Mix graphene oxide solution D and 50% carboxybetaine solution at a volume ratio of 1:1 to obtain mixed solution E;

[0055] S3.3: Immerse the polyamide membrane in mixed solution E for 12 hours at a temperature of 40°C, and dry it at room temperature after immersion to obtain the modified nanofiltration membrane.

[0056] S4: Inject the mixed solution C into the electrolytic cell and perform the first electrolysis using insoluble stainless steel anode. The parameters for the first electrolysis are: electrolysis temperature 55℃, current density 300A / m³. 2 The electrolysis voltage was 1.6V and the electrolysis time was 4h to obtain crude electrolytic cobalt;

[0057] S5: The crude electrolytic cobalt obtained from the first electrolysis is washed with deionized water and then dried at 80°C for 8 hours to remove impurities and moisture adhering to the surface.

[0058] S6: The crude electrolytic cobalt undergoes a second electrolysis. The parameters for the second electrolysis are: electrolysis temperature 50℃, current density 400A / m³. 2 The electrolysis voltage is 1.8V, the electrolysis time is 6h, and the electrolysis solution is a 10% sulfuric acid-hydrochloric acid mixed acid solution with a volume ratio of sulfuric acid to hydrochloric acid of 1:1. Metallic cobalt is used as the cathode and crude electrolytic cobalt is used as the anode to further remove impurities and obtain high-purity electrolytic cobalt.

[0059] S7: The obtained electrolytic cobalt is purged with nitrogen gas at a flow rate of 10 m / s for 12 h. After purging, the cobalt is crushed and ground to obtain the electrolytic cobalt.

[0060] Example 3

[0061] S1: The copper-cobalt ore is crushed and ground in a ball mill at a speed of 600 r / min for 4 hours to obtain powder A;

[0062] S2: Dissolve powder A in a 10% hydrochloric acid solution, wherein the solid-liquid mass ratio of powder A to inorganic acid solution is 1:5, to obtain mixed solution B;

[0063] S3: Pass the mixed solution B through a modified nanofiltration membrane with a permeation pressure of 0.25 Pa, collect the concentrate, add 1 wt% hydrogen peroxide to the concentrate, stir for 1 h, add 1 wt% polyacrylamide after stirring, continue stirring for 0.5 h, filter to obtain mixed solution C;

[0064] The modified nanofiltration membrane is prepared as follows:

[0065] S3.1: Dissolve graphene oxide in deionized water to prepare a 20% graphene oxide solution D;

[0066] S3.2: Mix graphene oxide solution D and 50% carboxybetaine solution at a volume ratio of 1:1 to obtain mixed solution E;

[0067] S3.3: Immerse the polyamide membrane in mixed solution E for 12 hours at a temperature of 40°C, and dry it at room temperature after immersion to obtain the modified nanofiltration membrane.

[0068] S4: Inject the mixed solution C into the electrolytic cell and perform the first electrolysis using insoluble graphite anode. The parameters for the first electrolysis are: electrolysis temperature 65℃, current density 400A / m³. 2 The electrolysis voltage was 2.2V, and the electrolysis time was 3h to obtain crude electrolytic cobalt;

[0069] S5: The crude electrolytic cobalt obtained from the first electrolysis is washed with deionized water and then dried at 80°C for 8 hours to remove impurities and moisture adhering to the surface.

[0070] S6: The crude electrolytic cobalt undergoes a second electrolysis. The parameters for the second electrolysis are: electrolysis temperature 65℃, current density 500A / m³. 2 The electrolysis voltage is 2.0V, the electrolysis time is 4h, and the electrolysis solution is a 10% sulfuric acid-hydrochloric acid mixed acid solution with a volume ratio of sulfuric acid to hydrochloric acid of 1:1. Metallic cobalt is used as the cathode and crude electrolytic cobalt is used as the anode to further remove impurities and obtain high-purity electrolytic cobalt.

[0071] S7: The obtained electrolytic cobalt is purged with nitrogen gas at a flow rate of 10 m / s for 12 h. After purging, the cobalt is crushed and ground to obtain the electrolytic cobalt.

[0072] Comparative Example 1

[0073] This comparative example does not use a modified nanofiltration membrane; the remaining steps are the same as in Example 1.

[0074] Comparative Example 2

[0075] In this comparative example, no graphene oxide solution was added during the preparation of the modified nanofiltration membrane; the remaining steps were the same as in Example 1.

[0076] Comparative Example 3

[0077] In this comparative example, no carboxybetaine solution was added during the preparation of the modified nanofiltration membrane; the remaining steps were the same as in Example 1.

[0078] Comparative Example 4

[0079] In this comparative example, no hydrogen peroxide was added during the preparation process, and the remaining steps were the same as in Example 1.

[0080] Comparative Example 5

[0081] In this comparative example, no polyacrylamide was added during the preparation process, and the remaining steps were the same as in Example 1.

[0082] Comparative Example 6

[0083] In this comparative example, no secondary electrolysis was performed during the preparation process; the remaining steps were the same as in Example 1.

[0084] The purity of the electrolytic cobalt prepared in the examples and comparative examples was tested, and the experimental results are summarized in the table below.

[0085] Electrolytic cobalt purity (%) Example 1 99.9 Example 2 99.8 Example 3 99.8 Comparative Example 1 94.7 Comparative Example 2 95.5 Comparative Example 3 95.9 Comparative Example 4 96.4 Comparative Example 5 96.8 Comparative Example 6 92.3

[0086] Data from the examples and comparative examples show that modifying the nanofiltration membrane, adding hydrogen peroxide and polyacrylamide during the preparation process, and performing multiple electrolysis all result in higher purity of the prepared electrolytic cobalt.

[0087] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.

Claims

1. A method for preparing electrolytic cobalt using multi-stage electrolysis, characterized in that, The specific process for preparing electrolytic cobalt is as follows. S1: The cobalt-containing solid raw material is crushed and ground in a ball mill at a speed of 500~600 r / min for 4~5 hours to obtain powder A; S2: Dissolve powder A in a 10% inorganic acid solution, wherein the solid-liquid mass ratio of powder A to inorganic acid solution is 1:(5~10), to obtain mixed solution B; S3: Pass the mixed solution B through a modified nanofiltration membrane, collect the concentrate, add 1~2wt% hydrogen peroxide to the concentrate, stir for 1~2h, add 1wt% polyacrylamide after stirring, continue stirring for 0.5h, filter to obtain mixed solution C; S4: Inject the mixed solution C into the electrolytic cell and perform the first electrolysis using an insoluble anode to obtain crude electrolytic cobalt; S5: The crude electrolytic cobalt obtained from the first electrolysis is washed with deionized water and then dried at 80°C for 8 hours to remove impurities and moisture adhering to the surface. S6: The crude electrolytic cobalt is subjected to a second electrolysis. The electrolytic solution is a 10% sulfuric acid-hydrochloric acid mixed acid solution. Metallic cobalt is used as the cathode and crude electrolytic cobalt is used as the anode to further remove impurities and obtain high-purity electrolytic cobalt. S7: The electrolytic cobalt obtained from the second electrolysis is purged with nitrogen for 12 hours. After purging, it is crushed and ground to obtain the electrolytic cobalt. The modified nanofiltration membrane in S3 is prepared by the following method. S3.1: Dissolve graphene oxide in deionized water to prepare a 20% graphene oxide solution D; S3.2: Mix graphene oxide solution D and 50% carboxybetaine solution at a volume ratio of 1:1 to obtain mixed solution E; S3.3: Immerse the polyamide membrane in mixed solution E for 12 hours at a temperature of 40°C, and dry it at room temperature after immersion to obtain the modified nanofiltration membrane.

2. The method for preparing electrolytic cobalt using multi-stage electrolysis according to claim 1, characterized in that, The inorganic acid solution in S2 is one of nitric acid, sulfuric acid, or hydrochloric acid.

3. The method for preparing electrolytic cobalt using multi-stage electrolysis according to claim 1, characterized in that, The permeation pressure of the modified nanofiltration membrane in S3 is 0.25~1MPa.

4. The method for preparing electrolytic cobalt using multi-stage electrolysis according to claim 1, characterized in that, The insoluble anode material in S4 is one of lead, graphite, or stainless steel.

5. The method for preparing electrolytic cobalt using multi-stage electrolysis according to claim 1, characterized in that, The parameters for the first electrolysis in S4 are: electrolysis temperature 55~65℃, current density 300~400A / m. 2 The electrolysis voltage is 1.6~2.2V, and the electrolysis time is 3~4h.

6. The method for preparing electrolytic cobalt using multi-stage electrolysis according to claim 1, characterized in that, In the sulfuric acid-hydrochloric acid mixed acid solution S6, the volume ratio of sulfuric acid to hydrochloric acid is 1:

1.

7. The method for preparing electrolytic cobalt using multi-stage electrolysis according to claim 1, characterized in that, The parameters for the second electrolysis in S6 are: electrolysis temperature 50~65℃, current density 400~500A / m. 2 The electrolysis voltage is 1.8~2.0V, and the electrolysis time is 4~6h.

8. The method for preparing electrolytic cobalt using multi-stage electrolysis according to claim 1, characterized in that, The nitrogen purging velocity in S7 is 10 m / s.