Co / CoOx / Co3O4 anode for cobalt electrodeposition and preparation method of Co / CoOx / Co3O4 anode

Abstract

The invention relates to the field of material preparation, and particularly discloses a Co / CoOx / Co3O4 anode for cobalt electrodeposition and a preparation method of the Co / CoOx / Co3O4 anode. The anode is prepared by carrying out constant-current anodic polarization on a Co plate in a solution, and the main component of the anode is Co / CoOx / Co3O4. The preparation method of the anode comprises the following steps: 1, cleaning a cobalt plate obtained by electrodeposition of a sulfuric acid system by using hot water, and naturally drying; secondly, shot blasting treatment is conducted on the cobalt plate, and the surface roughness of the cobalt plate is improved; and 3, in a cobalt-containing solution, carrying out constant-current anodic polarization, and depositing a CoOx / Co3O4 gradient film layer on the surface of the cobalt plate to obtain a Co / CoOx / Co3O4 anode. Compared with a lead alloy anode or a Ti / PbO2 anode for cobalt electrodeposition, the anode has the advantages of high catalytic activity, no Pb < 2 + > dissolution risk and good application prospect.

Description

Technical Field

[0001] The present invention relates to the field of material preparation, and specifically discloses a Co / CoO x / Co3O4 anode for cobalt electrowinning and a preparation method thereof. Background Art

[0002] Electrowinning in sulfuric acid system is an important method for extracting and preparing metallic cobalt. At present, Pb alloy anodes (Pb-Sb, Pb-Ca-Sn, Pb-Ag) or Ti / PbO2 anodes are mainly used for cobalt electrowinning in sulfuric acid system. During electrowinning, Pb in the substrate or coating will be oxidized and dissolved into the electrolyte, posing a risk of contaminating the cathode product, and Pb needs to be removed from the electrolyte regularly. 2+ . Summary of the Invention

[0003] Aiming at the disadvantage that Pb is easily dissolved in the traditional Pb alloy anode and Ti-based PbO2 anode for cobalt electrowinning, the present invention proposes an anode for cobalt electrowinning and a preparation method thereof. 2+

[0004] The anode for cobalt electrowinning proposed by the present invention is prepared by anodic polarization of a Co plate at a constant current in a solution, and its main components are Co / CoO x / Co3O4.

[0005] The preparation method of the anode for cobalt electrowinning proposed by the present invention includes the following steps:

[0006] First step, cleaning the cobalt plate obtained by electrowinning in sulfuric acid system with hot water and drying it naturally;

[0007] Second step, performing shot peening on the cobalt plate to improve the surface roughness of the cobalt plate;

[0008] Third step, in a cobalt-containing solution, anodic polarization at a constant current is carried out to deposit a CoO x / Co3O4 gradient film layer on the surface of Co to obtain a Co / CoO x / Co3O4 anode.

[0009] Preferably, the shot peening can be SiO2 or ZrO2, and the particle size is 50-1000 μm.

[0010] Preferably, during the anodic polarization at a constant current, the solution is prepared from CoSO4, (NH4)2SO4 and water, the pH is controlled at 3-6, and the Co 2+ concentration is controlled at 5-40 g / L.

[0011] Preferably, during the anodic polarization at a constant current, the current density is 5-20 mA cm -2 , and the constant current polarization time is 24-72 h.

[0012] The inventive concept and technical principle of the present invention are as follows:

[0013] (1) Completely abandon lead-containing anodes: Whether it is a Pb alloy anode or a Ti / PbO2 anode, during service, Pb in the substrate or coating will oxidize and dissolve into the solution, which may cause the lead content in the cathode product to exceed the standard. Therefore, the present invention proposes to directly use the electrodeposited Co plate as the anode substrate.

[0014] (2) Pre-prepare an oxide layer on the surface of the Co plate: Directly using a cobalt plate as the anode may lead to continuous dissolution of cobalt, similar to cobalt electrolytic refining, and thus Co in the solution cannot be 2+ deposited and precipitated. Therefore, we pre-prepare an electrochemically stable oxide layer on the surface of the Co plate, so that the anode mainly undergoes an oxygen evolution reaction during service, rather than the dissolution of Co.

[0015] (3) Design principle of the CoO x / Co3O4 deposition layer: For Pb alloy anodes and Ti / PbO2 anodes, during electrowinning, Co in the electrolyte 2+ will undergo oxidative deposition. This disordered deposition of cobalt oxides (hydroxides) has low oxygen evolution activity and poor structural stability. Therefore, we pre-prepare a CoO x / Co3O4 deposition layer on the surface of the Co plate. The Co3O4 on the surface layer has two advantages. First, Co3O4 has good oxygen evolution catalytic activity, which is beneficial to reducing the anode overpotential; second, Co3O4 can regulate the oxidative deposition behavior of Co in the solution during electrowinning, inhibit the disordered oxidative deposition of Co 2+ , and improve the stability of the oxide film layer. 2+ Specific implementation mode

[0016] The content of the present invention will be described in detail in conjunction with the following embodiments.

[0017] Example 1

[0018] The cobalt plate obtained by electrowinning in a sulfuric acid system (thickness ~5 mm, working size 1200 mm×1000 mm) was cleaned with hot water and dried naturally. Shot peening treatment was carried out on the cobalt plate to improve the surface roughness of the cobalt plate. The shot peening was SiO2 with a diameter of 500 μm; in a cobalt-containing solution (Co 2+ concentration was 10 g / L, and the addition amount of ammonium sulfate was controlled to make the pH controlled at 4), constant current anodic polarization (10 mAcm -2 ) was carried out for 48 h to deposit a CoO x / Co3O4 gradient film layer on the surface of Co, and a Co / CoO x / Co3O4 anode was obtained.

[0019] During the 72-hour cobalt electrowinning process (20 mA cm -2 , 60 °C), compared with the Pb-Sb anode, the potential of the Co / CoO x / Co3O4 anode is 80 mV lower, the anode weight loss is reduced by 82%, and there is no Pb in the electrolyte 2+ .

[0020] Example 2

[0021] The cobalt plate obtained by electrowinning in the sulfuric acid system was washed with hot water (thickness ~5 mm, working size 1200 mm × 1000 mm) and dried naturally. Shot peening was carried out on the cobalt plate to increase the surface roughness of the cobalt plate. The shot peening was ZrO2 with a diameter of 800 μm; in a cobalt-containing solution (Co 2+ concentration was 5 g / L, and the addition amount of ammonium sulfate was controlled so that the pH was controlled at 5) constant current anodic polarization (5 mA cm -2 ) for 72 h, and a CoO x / Co3O4 gradient film layer was deposited on the surface of Co to obtain a Co / CoO x / Co3O4 anode.

[0022] During the 72-hour cobalt electrowinning process (20 mA cm -2 , 60 °C), compared with the Ti / PbO2 anode, the potential of the Co / CoO x / Co3O4 anode is 50 mV lower, the anode weight loss is reduced by 62%, and there is no Pb in the electrolyte 2+ .

[0023] Example 3

[0024] The cobalt plate obtained by electrowinning in the sulfuric acid system was washed with hot water (thickness ~5 mm, working size 1200 mm × 1000 mm) and dried naturally. Shot peening was carried out on the cobalt plate to increase the surface roughness of the cobalt plate. The shot peening was ZrO2 with a diameter of 70 μm; in a cobalt-containing solution (Co 2+ concentration was 25 g / L, and the addition amount of ammonium sulfate was controlled so that the pH was controlled at 5) constant current anodic polarization (5 mA cm -2 ) for 24 h, and a CoO x / Co3O4 gradient film layer was deposited on the surface of Co to obtain a Co / CoO x / Co3O4 anode.

[0025] During the 72-hour cobalt electrowinning process (20 mA cm -2 , 60 °C), compared with the Ti / PbO2 anode, the potential of the Co / CoO x / Co3O4 anode is 60 mV lower, the anode weight loss is reduced by 81%, and there is no Pb in the electrolyte 2+ .

Claims

1. A Co / CoO for Cobalt Electrodeposition x / The method for preparing Co3O4 anode is characterized in that, The following steps are involved: The cobalt plate obtained by electrowinning in the sulfuric acid system is cleaned with hot water and dried naturally; Shot peening is performed on the cobalt plate to improve the surface roughness of the cobalt plate; In a cobalt-containing solution, constant current anodic polarization is performed to deposit CoO on the surface of the cobalt plate. x / Co3O4 gradient film layer, obtain Co / CoO x / Co3O4 anode.

2. The preparation method according to claim 1, characterized in that The shot peening material is SiO2 or ZrO2, and the particle size is 50 to 1000 μm.

3. The preparation method according to claim 1, characterized in that: During the constant current anodic polarization process, the solution was prepared by CoSO4, (NH4)2SO4 and water, and the pH was controlled at 3-6. 2+ The concentration is controlled at 5-40g / L.

4. The preparation method according to claim 1, characterized in that: During the constant current anodic polarization process, the current density is 5-20 mA cm -2 , constant current polarization time is 24 to 72 hours.

5. A Co / CoO for cobalt electrowinning prepared by the method of any one of claims 1 to 4 x / Co3O4 anode.