A method of recovering cobalt starting sheets

Abstract

This invention belongs to the field of cobalt electrowinning technology, specifically relating to a method for recovering cobalt starter sheets, comprising: S1, obtaining the cobalt starter sheet to be recovered and the electrowinning anolyte, and performing pretreatment, wherein the electrowinning anolyte includes Co 2+ and H + S2. Add the cobalt starting electrode to the electrowinning anolyte to form the first system; S3. Obtain the redox potential of the first system. When the redox potential of the first system is >550mV, add FeSO4 to the first system and control the Fe content in the first system. 2+ The concentration of Fe was 50-200 ppm. When the redox potential of the first system was <350 mV, hydrogen peroxide was added to the first system until the pH of the first system was 1.5-2. Then, the pH of the first system was adjusted to 3.5-4.0, and the reaction was carried out for 1-1.5 hours. The mixture was then filtered to obtain a residue and a filtrate. The filtrate can be used for the preparation of electrolytic cobalt. The Fe concentration in the system was controlled by detecting the redox potential. 2+ The concentration and redox potential of the system, as well as the timing of hydrogen peroxide addition, affect the reduction of Co in the cobalt-based electrode. 3+ At the same time, it reduces the consumption of hydrogen peroxide during cobalt leaching.

Description

Technical Field

[0001] This invention belongs to the field of cobalt electrowinning technology, specifically a method for recycling cobalt starting sheets. Background Technology

[0002] Cobalt waste cathode sheets mainly originate from defective products in the cobalt electrowinning process (such as cathode sheets that have detached from titanium seed plates), scraps, or used cathode sheets (such as cathode sheets that have been burned during electrowinning, turned black, or have broken tabs, making them unsuitable for further electrowinning). Their cobalt content is typically as high as 99.9%, but they may still contain small amounts of impurities (such as Fe and Cu). Due to the high value of cobalt, efficient cobalt recycling and reduced processing costs are crucial.

[0003] Currently, the industrial treatment of cobalt waste anode sheets mainly employs hydrometallurgical processes. These include sulfuric acid and hydrogen peroxide leaching, which consumes large amounts of both; anolyte leaching, which has low dissolution efficiency and cannot dissolve high-valence cobalt; HCl / HNO3 leaching, which is highly corrosive and causes heavy pollution; reduction roasting-acid leaching, which is energy-intensive and involves cobalt volatilization; and bioleaching, which has a long leaching cycle and low tolerance to high cobalt concentrations. Existing technologies still suffer from low recovery rates, high energy consumption, significant pollution, and complex processes. Summary of the Invention

[0004] To address the above problems, the present invention provides a method for recycling cobalt starting sheets, comprising the following steps:

[0005] S1. Obtain the cobalt starter sheet and electrodeposition anolyte to be recycled, and perform pretreatment. The electrodeposition anolyte includes Co. 2+ and H + ;

[0006] S2. The cobalt starting electrode is added to the electrowinning anolyte to form a first system;

[0007] S3. Obtain the redox potential of the first system. When the redox potential of the first system is >550mV, add FeSO4 to the first system and control the Fe content in the first system. 2+ The concentration of hydrogen peroxide is 50-200 ppm. When the redox potential of the first system is <350 mV, hydrogen peroxide is added to the first system until the pH of the first system is 1.5-2.

[0008] S4. Adjust the pH of the first system to 3.5-4.0, react for 1-1.5 hours, and then filter to obtain filter residue and filtrate. The filtrate can be used for the preparation of electrolytic cobalt.

[0009] In a preferred embodiment of the method for recycling cobalt starting sheets according to the present invention, in step S1, the Co... 2+The concentration of H is 50-60 g / L. + The concentration of the anolyte is 1.4-2 mol / L, and the temperature of the anolyte is 45-55℃.

[0010] Furthermore, the Co 2+ The concentration is any one of 50 g / L, 52 g / L, 54 g / L, 56 g / L, 58 g / L, 60 g / L, or any two of them.

[0011] In a preferred embodiment of the method for recovering cobalt starting sheets according to the present invention, in step S2, the cobalt element in the cobalt starting sheet reacts with H in the electrowinning anolyte. + The concentration-to-moment ratio is (0.9-1):1.

[0012] As a preferred embodiment of the method for recycling cobalt starter sheets according to the present invention, step S2 further includes: during the process of adding the cobalt starter sheet to the electrowinning anolyte to form the first system, controlling the feeding rate of the starter sheet so that the temperature of the first system is between 50-65°C.

[0013] As a preferred embodiment of the method for recycling cobalt starting sheets according to the present invention, step S3 further includes: treating the first system with ultrasound, wherein the frequency of the ultrasound is 30-50kHz.

[0014] Furthermore, the frequency of the ultrasound is any one of 30kHz, 35kHz, 40kHz, 45kHz, and 50kHz, or a range between any two of them.

[0015] In a preferred embodiment of the method for recycling cobalt starting sheets according to the present invention, in step S3, the molar ratio of hydrogen peroxide added to the first system to the amount of cobalt in the cobalt starting sheet is (0.8-0.9):1.

[0016] In a preferred embodiment of the method for recovering cobalt starting sheets according to the present invention, in step S4, the pH is adjusted using NaOH or Na2CO3, and the temperature of the first system is 60-70℃.

[0017] In a preferred embodiment of the method for recovering cobalt starting sheets according to the present invention, in step S4, the filter residue includes Fe(OH)3, and the filter residue is recovered.

[0018] In a preferred embodiment of the method for recycling cobalt starting sheets according to the present invention, in step S1, the cobalt content in the cobalt starting sheet is ≥90%, and the cobalt starting sheet includes Co. 3+ .

[0019] In a preferred embodiment of the method for recovering cobalt starter sheets according to the present invention, in step S4, the filtrate used in the process of preparing cobalt by electrowinning can be used as the electrowinning anolyte in step S1.

[0020] This invention controls the Fe in the system by detecting the redox potential. 2+ The concentration and redox potential of the system, as well as the timing of hydrogen peroxide addition, affect the reduction of Co in the cobalt-based electrode. 3+ At the same time, it reduces the consumption of hydrogen peroxide during cobalt leaching, and uses electrowinning anolyte to leach cobalt ions, allowing the leachate to be directly applied to the preparation of electrowinning cobalt. Detailed Implementation

[0021] The technical solutions described below in conjunction with the embodiments will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] This invention provides a method for recycling cobalt starting sheets, the specific steps of which are as follows:

[0023] S1. Obtain the cobalt starter sheet and electrodeposition anolyte to be recycled, and perform pretreatment. The electrodeposition anolyte includes Co. 2+ and H + ;

[0024] The cobalt-containing starter sheet has a cobalt content ≥99%. The starter sheet undergoes pretreatment by shearing and crushing it to ensure the size of the crushed sheet is <5 mm, thereby increasing the leaching surface area. The Co content in the electrowinning anolyte is... 2+ The concentration is 50-60 g / L, H + The concentration is 1.4-2 mol / L, and the temperature of the electrodeposited anolyte is 45-55℃.

[0025] S2. The cobalt starting electrode is added to the electrowinning anolyte to form a first system;

[0026] Cobalt in the cobalt starter reacts with H in the electrowinning anolyte + The concentration-to-molar ratio of the two substances is (0.9-1):1. During the process of adding the cobalt starter sheet to the electrowinning anolyte to form the first system, the feeding rate of the starter sheet is controlled so that the temperature of the first system is 50-65℃. The first system is treated with ultrasound at a frequency of 30-50kHz.

[0027] S3. Obtain the redox potential of the first system. When the redox potential of the first system is >550mV, add FeSO4 to the first system and control the Fe content in the first system. 2+ The concentration of hydrogen peroxide is 50-200 ppm. When the redox potential of the first system is <350 mV, hydrogen peroxide is added to the first system until the pH of the first system is 1.5-2.

[0028] The redox potential of the first system was detected using an oxidation-reduction potentiometer (ORP).

[0029] S4. Adjust the pH of the first system to 3.5-4.0, react for 1-1.5 hours, and then filter to obtain filter residue and filtrate. The filtrate can be used for the preparation of electrolytic cobalt.

[0030] The pH of the first system was adjusted to 3.5-4.0 using Na₂CO₃ or NaOH, and the temperature of the first system was controlled at 60-70℃, so that Fe... 3+ Impurities are allowed to precipitate, and the reaction time is 1-1.5 hours. The mixture is then filtered through a filter press to obtain filtrate and filter residue. The filter residue is recovered, and it mainly consists of Fe(OH)3. The filtrate is then used as an electrodeposition solution in the preparation of electrolytic cobalt.

[0031] Example 1

[0032] Waste cobalt starting sheets were obtained and crushed using a shearing shredder to a size of 4.6 mm, yielding 2 L of electrodeposition anolyte containing 60 g / L of Co. 2+ The leaching process involved adding 0.7 mol / L H₂SO₄ to the anolyte at a temperature of 52°C. 74.3 g of waste cobalt starting material was added to the anolyte to form a first leaching system. The ratio of the amount of cobalt starting material added to the hydrogen ion concentration in the anolyte was 0.9:1. The leaching temperature was 55-65°C, and ultrasonic waves at a frequency of 50 kHz were applied simultaneously. The redox potential of the first system was measured using an ORP meter. When the ORP in the first system exceeded 550 mV, FeSO₄ was added to the first system, and the Fe concentration was controlled within the specified range. 2+The concentration of hydrogen peroxide was 100-200 ppm. When the redox potential of the first system was <350 mV, hydrogen peroxide was added to the first system until the pH of the first system was 1.6. The amount of hydrogen peroxide added was 1 mol, and the molar ratio of the amount of hydrogen peroxide added to the amount of cobalt in the added cobalt starting sheet was 0.8:1. NaOH was added to the first system to adjust the pH to 3.5. After reacting for 1.5 h, the mixture was filtered to obtain filtrate and filter residue. The iron content in the filtrate was detected to be 0.2 ppm. The filtrate was used to prepare electrolytic cobalt, and the iron content in the obtained electrolytic cobalt was 18 ppm, which met the standards of YS / T255-2009, Co9995.

[0033] Example 2

[0034] Waste cobalt starting sheets were obtained and crushed using a shearing shredder to a size of 3.5 mm, yielding 2 L of electrowinning anolyte containing 52 g / L of Co. 2+ The leaching process involved adding 0.8 mol / L H₂SO₄ to the anolyte at a temperature of 55°C. 89.5 g of waste cobalt starting material was added to the anolyte to form a first leaching system. The ratio of the amount of cobalt starting material added to the hydrogen ion concentration in the anolyte was 0.95:1. The leaching temperature was 56-62°C, and ultrasonic waves at a frequency of 35 kHz were applied simultaneously. The redox potential of the first system was measured using an ORP meter. When the ORP in the first system exceeded 550 mV, FeSO₄ was added to the first system, and the Fe concentration in the first system was controlled. 2+ The concentration of hydrogen peroxide was 120-190 ppm. When the redox potential of the first system was <350 mV, hydrogen peroxide was added to the first system until the pH of the first system was 2. The amount of hydrogen peroxide added was 1.29 mol, and the molar ratio of the amount of hydrogen peroxide added to the amount of cobalt in the added cobalt starting sheet was 0.85:1. NaOH was added to the first system to adjust the pH to 4. After reacting for 1.3 h, the mixture was filtered to obtain filtrate and filter residue. The iron content in the filtrate was detected to be 0.1 ppm. The filtrate was used to prepare electrolytic cobalt, and the iron content in the obtained electrolytic cobalt was 11 ppm, which met the YS / T255-2009, Co9995 standard.

[0035] Example 3

[0036] Waste cobalt starting sheets were obtained and crushed using a shearing shredder to a size of 4.1 mm, yielding 2 L of electrowinning anolyte containing 50 g / L of Co. 2+The leaching process involved adding 1 mol / L H₂SO₄ to the anolyte at a temperature of 45°C. 117.8 g of waste cobalt starting material was added to the anolyte to form a first leaching system. The ratio of the amount of cobalt starting material added to the hydrogen ion concentration in the anolyte was 1:1. The leaching temperature was 50-60°C, and ultrasound at a frequency of 30 kHz was applied simultaneously. The oxidation-reduction potential (ORP) of the first system was measured using an ORP meter. When the ORP of the first system exceeded 550 mV, FeSO₄ was added to the first system, and the concentration of Fe in the first system was controlled. 2+ The concentration of hydrogen peroxide was 50-110 ppm. When the redox potential of the first system was <350 mV, hydrogen peroxide was added to the first system until the pH of the first system was 1.8. The amount of hydrogen peroxide added was 1.8 mol, and the molar ratio of the amount of hydrogen peroxide added to the amount of cobalt in the added cobalt starting sheet was 0.9:1. NaOH was added to the first system to adjust the pH to 3.7. After reacting for 1 hour, the mixture was filtered to obtain filtrate and filter residue. The iron content in the filtrate was detected to be 0.5 ppm. The filtrate was used to prepare electrolytic cobalt, and the iron content in the obtained electrolytic cobalt was 28 ppm, which met the YS / T255-2009, Co9995 standard.

[0037] Comparative Example 1

[0038] Waste cobalt starting sheets were obtained and crushed using a shearing shredder to a size of 4.6 mm, yielding 2 L of electrodeposition anolyte containing 56 g / L of Co. 2+ The leaching process involved adding 0.7 mol / L H₂SO₄ to the anolyte at a temperature of 52°C. 99.0 g of waste cobalt starting material was added to the anolyte to form a first leaching system. The ratio of the amount of cobalt starting material added to the hydrogen ion concentration in the anolyte was 1.2:1. The leaching temperature was 55-65°C, and ultrasonic waves at a frequency of 40 kHz were applied simultaneously. The redox potential of the first system was measured using an ORP meter. When the ORP in the first system exceeded 550 mV, FeSO₄ was added to the first system, and the Fe concentration was controlled within the specified range. 2+ The concentration of hydrogen peroxide was 100-200 ppm. When the redox potential of the first system was <350 mV, hydrogen peroxide was added to the first system until the pH of the first system was 1.6. The amount of hydrogen peroxide added was 1.12 mol, and the ratio of the amount of hydrogen peroxide added to the amount of cobalt in the added cobalt starting sheet was 0.8:1. NaOH was added to the first system to adjust the pH to 3.5. After reacting for 1.5 h, the mixture was filtered to obtain filtrate and filter residue. The iron content in the filtrate was 0.2 ppm. The filtrate was used to prepare electrolytic cobalt, but electrolytic cobalt that meets the standards of YS / T255-2009, Co9995 could not be obtained.

[0039] In Comparative Example 1, an excessive amount of cobalt starting sheet was added. Undissolved cobalt would deposit and be oxidized, affecting the formation of electrolytic cobalt.

[0040] Comparative Example 2

[0041] Waste cobalt starting sheets were obtained and crushed using a shearing shredder to a size of 4.6 mm, yielding 2 L of electrodeposition anolyte containing 56 g / L of Co. 2+ The leaching process involved adding 0.7 mol / L H₂SO₄ to the anolyte at a temperature of 52°C. 74.3 g of waste cobalt starting material was added to the anolyte to form a first leaching system. The ratio of the amount of cobalt starting material added to the hydrogen ion concentration in the anolyte was 0.9:1. The leaching temperature was 55-65°C, and ultrasonic waves at a frequency of 40 kHz were applied simultaneously. The redox potential of the first system was measured using an ORP meter. When the ORP in the first system exceeded 550 mV, FeSO₄ was added to the first system, and the Fe concentration was controlled within the specified range. 2+ The concentration of hydrogen peroxide was 100-200 ppm. When the redox potential of the first system was <350 mV, hydrogen peroxide was added to the first system until the pH of the first system was 1.6. The amount of hydrogen peroxide added was 1.01 mol, and the molar ratio of the amount of hydrogen peroxide added to the amount of cobalt in the added cobalt starting sheet was 0.8:1. NaOH was added to the first system to adjust the pH to 2. After reacting for 1.5 h, the mixture was filtered to obtain filtrate and filter residue. The iron content in the filtrate was detected to be 20 ppm. The filtrate was used to prepare electrolytic cobalt. The iron content in the obtained electrolytic cobalt was 320 ppm, which did not meet the standards of YS / T255-2009, Co9995.

[0042] This invention controls the Fe in the system by detecting the redox potential. 2+ The concentration of Co and the redox potential of the system, as well as the timing of hydrogen peroxide addition, are factors that influence the reduction of Co in the cobalt-based electrode. 3+ At the same time, it reduces the consumption of hydrogen peroxide during cobalt leaching, and uses electrowinning anolyte to leach cobalt ions, allowing the leachate to be directly applied to the preparation of electrowinning cobalt.

[0043] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for recycling cobalt starting sheets, characterized in that, Includes the following steps: S1. Obtain the cobalt starter sheet and electrodeposition anolyte to be recycled, and perform pretreatment. The electrodeposition anolyte includes Co. 2+ and H + ; S2. The cobalt starting electrode is added to the electrowinning anolyte to form a first system; S3. Obtain the redox potential of the first system. When the redox potential of the first system is >550mV, add FeSO4 to the first system and control the Fe content in the first system. 2+ The concentration of hydrogen peroxide is 50-200 ppm. When the redox potential of the first system is <350 mV, hydrogen peroxide is added to the first system until the pH of the first system is 1.5-2. S4. Adjust the pH of the first system to 3.5-4.0, react for 1-1.5 hours, and then filter to obtain filter residue and filtrate. The filtrate can be used for the preparation of electrolytic cobalt.

2. The method for recycling cobalt starting sheets according to claim 1, characterized in that, In step S1, the Co 2+ The concentration of H is 50-60 g / L. + The concentration of the anolyte is 1.4-2 mol / L, and the temperature of the anolyte is 45-55℃.

3. The method for recycling cobalt starting sheets according to claim 1, characterized in that, In step S2, the cobalt element in the cobalt starting sheet reacts with the H in the electrowinning anolyte. + The concentration-to-moment ratio is (0.9-1):

1.

4. The method for recycling cobalt starting sheets according to claim 3, characterized in that, Step S2 further includes: during the process of adding the cobalt starter sheet to the electrowinning anolyte to form the first system, controlling the feeding rate of the starter sheet so that the temperature of the first system is between 50-65°C.

5. The method for recycling cobalt starting sheets according to claim 1, characterized in that, Step S3 further includes: processing the first system with ultrasound, wherein the frequency of the ultrasound is 30-50kHz.

6. The method for recycling cobalt starting sheets according to claim 1, characterized in that, In step S3, the molar ratio of hydrogen peroxide added to the first system to cobalt in the cobalt starting sheet is (0.8-0.9):

1.

7. The method for recycling cobalt starting sheets according to claim 1, characterized in that, In step S4, the pH is adjusted using NaOH or Na2CO3, and the temperature of the first system is 60-70℃.

8. The method for recycling cobalt starting sheets according to claim 1, characterized in that, In step S4, the filter residue includes Fe(OH)3, and the filter residue is recovered.

9. The method for recycling cobalt starting sheets according to claim 1, characterized in that, In step S1, the cobalt content in the cobalt starting sheet is ≥90%, and the cobalt starting sheet includes Co. 3+ .

10. The method for recycling cobalt starting sheets according to claim 1, characterized in that, In step S4, the anolyte produced during the process of applying the filtrate to prepare cobalt electrowinning can be used as the electrowinning anolyte in step S1.