Method for recycling anode powder of waste nickel-cadmium battery

Abstract

The invention relates to the technical field of waste cadmium-nickel battery recovery, in particular to a waste cadmium-nickel battery anode powder recovery method which comprises the following steps: S1, nickel anode powder is subjected to activation pretreatment to obtain anode slurry; s2, the anode slurry and a leaching agent are mixed for second-stage leaching treatment, and after the leaching reaction is finished, leaching anode liquid is obtained through solid-liquid separation; s3, the leached anolyte and a purifying agent are mixed for secondary purification treatment, and after the purification reaction is finished, solid-liquid separation is conducted to obtain purified anolyte; s4, the purified anolyte is subjected to extraction and reverse extraction treatment, and a nickel-containing pregnant solution is obtained; and S5, adding a precipitator into the nickel-containing pregnant solution to obtain nickel carbonate. According to the waste cadmium-nickel battery anode powder recovery method, efficient recovery of nickel is achieved, the total extraction rate of nickel can effectively exceed 98.5%, and the purity of generated nickel carbonate is higher than 99.6%.

Description

Technical Field

[0001] The present invention relates to the technical field of waste nickel-cadmium battery recycling, and particularly to a method for recycling anode powder of waste nickel-cadmium batteries. Background Art

[0002] A nickel-cadmium battery is an alkaline storage battery that uses metallic cadmium as the negative active material and nickel hydroxide as the positive active material. Compared with other secondary batteries, nickel-cadmium batteries have good low-temperature cycle performance, stable high-current discharge characteristics, high reliability, long service life, low self-discharge rate, resistance to overcharging and over-discharging, and stable discharge voltage, and are widely used in many fields such as aircraft, ships, transportation, military, and energy storage power grids.

[0003] With the increasing use of nickel-cadmium batteries, the efficient recycling of waste nickel-cadmium batteries is an indispensable link to achieve resource recycling and avoid environmental pollution. Currently, there are problems in the recycling of nickel-cadmium batteries such as long wet treatment processes and high temperatures and large energy consumption in pyrometallurgical treatment. Therefore, the development of new efficient recycling technologies is of great significance for the expansion of the battery application field, resource recycling, and environmental protection. The existing patent CN201711436821.X discloses a method for recycling cadmium and nickel in waste nickel-cadmium batteries, including: immersing waste nickel-cadmium battery materials in an HCl solution, adjusting the pH value of the obtained metal ion mixed solution to 4-7, filtering to obtain a pretreatment solution; mixing the pretreatment solution and citric acid, reacting to obtain a reaction solution, adjusting the pH value to 8-11, filtering to obtain cadmium hydroxide and a filtrate; mixing the filtrate and calcium nitrate, adjusting the pH value to 9-12, reacting to obtain a precipitate; reacting the precipitate with an HCl solution, filtering, and adjusting the pH value of the obtained filtrate to 7-12 to obtain nickel hydroxide. However, in the above technical solution, the purity of the recycled nickel is only 95.71-98.26%, and the recovery rate is only between 89.14-92.44%. Such a recovery effect may not meet the requirements for high-value-added nickel products (such as high-purity nickel materials or nickel carbonate) in actual industrial applications. Summary of the Invention

[0004] In view of this, the present invention proposes a method for recycling anode powder of waste nickel-cadmium batteries to solve the problems of large nickel loss rate and low purity of the recycled nickel anode powder in the existing nickel-cadmium battery recycling methods.

[0005] The technical solution of the present invention is realized as follows: The present invention provides a method for recycling anode powder of waste nickel-cadmium batteries, including the following steps:

[0006] S1. Activate and pretreat the nickel anode powder to obtain anode slurry;

[0007] S2. Mix the anode sludge with the leaching agent for secondary leaching treatment. After the leaching reaction ends, perform solid-liquid separation to obtain the leached anode solution;

[0008] S3. Mix the leached anode solution with the purification agent for secondary purification treatment. After the purification reaction ends, perform solid-liquid separation to obtain the purified anode solution;

[0009] S4. Perform extraction and back-extraction on the purified anode solution to obtain a nickel-rich solution;

[0010] S5. Add a precipitating agent to the nickel-rich solution to obtain nickel carbonate.

[0011] In the present invention, in step S1, the activation pretreatment promotes the formation of a uniform anode sludge from nickel anode powder; in step S2, the secondary leaching treatment promotes the dissolution of nickel in the acidic leaching solution and removes impurities; in step S3, the secondary purification treatment is performed on the leaching solution to promote the oxidation precipitation of macromolecules and insoluble impurities; in step S4, nickel is further selectively extracted by extraction and back-extraction to obtain a nickel-rich solution with high concentration and high purity; in step S5, nickel carbonate precipitate is formed through a precipitation reaction. The technical solution provided by the present invention realizes the effective recovery of nickel from the solution, and the purity of the obtained nickel carbonate product can reach more than 99.6%; compared with the prior art, the effect is very remarkable, the process flow is easy to be applied on a large scale, and it can be widely used in industrial production.

[0012] On the basis of the above technical solution, preferably, in step S1, the activation pretreatment includes: performing ball milling treatment on the nickel anode powder in the activation solution, and the liquid-solid ratio of the nickel anode powder to the activation solution is 1-3:1; the activation solution is a mixed solution of water and alcohol.

[0013] On the basis of the above technical solution, preferably, the volume ratio of water to alcohol in the activation solution is 100:2-10; the alcohol includes one or more of methanol, ethanol, ethylene glycol, and isopropyl alcohol.

[0014] By using ball milling technology for activation pretreatment, physical refinement of the powder, exposure of reaction sites, and improvement of chemical properties are realized. When the anode sludge after ball milling treatment is subjected to subsequent leaching treatment, the acidic leaching agent can more fully contact the nickel in the powder, effectively improving the dissolution rate of nickel.

[0015] On the basis of the above technical solution, preferably, step S2 specifically includes:

[0016] S21. Mix the anode sludge with the first leaching agent for the first-stage leaching treatment. After the leaching reaction ends, perform solid-liquid separation to obtain the first-stage slag phase and the first-stage leaching solution;

[0017] S22. Mix the first-stage slag phase with the second leaching agent in a closed environment for the second-stage leaching treatment. After the leaching reaction ends, perform solid-liquid separation to obtain the second-stage slag phase and the second-stage leaching solution.

[0018] S23. Mix the first-stage leaching solution and the second-stage leaching solution evenly to obtain the leached anolyte.

[0019] On the basis of the above technical solutions, preferably, in step S21, the solid-liquid ratio of the anode mud to the leaching agent is 1:8 - 10, the temperature of the first-stage leaching treatment is 70 - 80 °C, and the time is 2 - 4 h; in step S22, the solid-liquid ratio of the first-stage slag phase to the leaching agent is 1:3 - 5, the temperature of the second-stage leaching treatment is 90 - 120 °C, and the time is 4 - 8 h.

[0020] On the basis of the above technical solutions, preferably, the first leaching agent includes one or more of sulfuric acid, nitric acid, hydrochloric acid, acetic acid, and oxalic acid; the second leaching agent is a mixed solution of sulfuric acid and ammonium chloride.

[0021] More preferably, the concentration of the first leaching agent is 2 - 10 M, the concentration of sulfuric acid in the second leaching agent is 2 - 10 M, the concentration of ammonium chloride is 0.2 - 0.5 M, and the volume ratio of sulfuric acid to ammonium chloride in the second leaching agent is 8 - 10:1.

[0022] In the present invention, after the waste cadmium-nickel battery anode powder undergoes activation pretreatment, the dissolution of nickel in the prepared anode mud has a gradient distribution. The first-stage leaching mainly dissolves the easily soluble part, enabling most nickel ions to enter the solution; while the nickel remaining in the first-stage leaching residue is more slowly or difficult to dissolve due to the influence of crystal structure, particle wrapping, or other physical shielding effects. Therefore, the second-stage leaching is adopted. The second stage uses a higher temperature and longer reaction time in a closed environment to achieve sufficient leaching of the insoluble part. By performing the leaching in stages, the reaction process is optimized, and the excessive energy consumption and side reaction risks caused by single high-temperature and long-time leaching can be avoided.

[0023] On the basis of the above technical solutions, preferably, step S3 specifically includes:

[0024] S31. Mix the leached anolyte with the first purifying agent for the first-stage purification treatment. After the purification reaction ends, perform solid-liquid separation to obtain the first anolyte.

[0025] S32. Mix the first anolyte with the second purifying agent for the second-stage purification treatment. After the purification reaction ends, perform solid-liquid separation to obtain the purified anolyte.

[0026] Based on the above technical solutions, preferably, in step S31, the mass ratio of the leached anode solution to the first purifying agent is 80-100:1, the temperature of the first-stage purification treatment is 50-80 °C, and the time is 2-4 h; in step S32, the mass ratio of the first anode solution to the second purifying agent is 80-100:1, the temperature of the second-stage purification treatment is 80-90 °C, and the time is 4-6 h.

[0027] Based on the above technical solutions, preferably, the first purifying agent includes one or more of hydrogen peroxide, ammonium persulfate, peracetic acid, and sodium chlorite; the second purifying agent includes potassium hydroxide and / or sodium hydroxide.

[0028] More preferably, the concentration of the first purifying agent is 0.2-2 M; the concentration of the second purifying agent is 0.2-2 M.

[0029] In the present invention, the two-stage purification treatment first uses an oxidant for mild pretreatment to remove most of the easily oxidizable organic substances and impurities, and then uses high-temperature and strong-alkali conditions to promote the complete precipitation of the impurities that still remain and are difficult to remove after the first-stage purification treatment. This two-pronged approach improves the impurity removal efficiency. The segmented treatment method ensures the stability and selectivity of the reaction during the entire purification process and ensures that the finally obtained purified anode solution has a sufficiently high purity, which is beneficial to the efficient recovery of nickel during the subsequent extraction and stripping processes, and improves the resource utilization rate and product quality of the entire process.

[0030] Based on the above technical solutions, preferably, in step S4, the purified anode solution is extracted with an extractant, and after the extraction is completed, a nickel-containing organic solution is obtained, and then a sulfuric acid solution is added thereto for stripping to obtain a nickel-rich solution.

[0031] Based on the above technical solutions, preferably, the extractant includes one of C272, P204, and P507; the precipitant includes potassium carbonate, and the addition amount of the precipitant is a mass ratio of 4-6:1.

[0032] The reaction between the purified anode solution and the extractant promotes the separation of nickel ions from the impurities in the aqueous phase, and most of the nickel is enriched in the organic phase, realizing the selective extraction of nickel; in the stripping stage, under the action of sulfuric acid, nickel ions are transferred and reduced from the organic phase to nickel salts in the aqueous phase, forming an aqueous solution rich in nickel, that is, a nickel-rich solution. Through the extraction and stripping processes, not only the extraction and separation process of nickel ions is optimized, but also the quality and purity of the subsequent products are significantly improved, providing strong technical support for the efficient resource recovery of the anode powder of waste cadmium-nickel batteries.

[0033] The method for recycling the anode powder of waste cadmium-nickel batteries of the present invention has the following beneficial effects compared with the prior art:

[0034] (1) The method for recovering anode powder of waste cadmium-nickel batteries of the present invention realizes efficient recovery of nickel by organically integrating activation pretreatment, two-stage leaching, two-stage purification, extraction stripping and precipitation. The scheme can effectively make the total nickel extraction rate exceed 98.5%, and the purity of the generated nickel carbonate is higher than 99.6%. The process flow structure is clear, the connection between the processes is reasonable, and it has good continuity and stability. At the same time, it has the advantages of low energy consumption and environmental protection, and is suitable for large-scale industrial application;

[0035] (2) A combination of the first and second leaching stages is adopted, where the readily soluble nickel is fully dissolved by a reaction at a high solid-liquid ratio at 70 to 80°C for 2 to 4 hours; then the second leaching is carried out in a closed environment at 90 to 120°C for 4 to 8 hours, which not only supplements the residual insoluble nickel but also activates the nickel ions to form a complex using a mixture of sulfuric acid and ammonium chloride, thereby improving the dissolution efficiency. This staged operation realizes the comprehensive recovery of the two parts of nickel resources, ensures the improvement of the overall dissolution rate, and takes into account both energy consumption control and safe and stable operation;

[0036] (3) Through a two-stage purification process: In the first stage, a mild oxidizing purifier is used to preliminarily oxidize and precipitate organic matter and other easily oxidizable impurities in the leachate; then, in the second stage, a strong base is used to further remove the remaining interfering ions by adjusting the pH and precipitation reaction. This two-stage purification method is progressive, ensuring that the purified anolyte has extremely high purity, providing ideal raw material conditions for the subsequent extraction step;

[0037] (4) The purified anolyte is fully mixed with a suitable extractant, and the complexing ability of the extractant is used to transfer nickel ions to the organic phase with high selectivity, thereby achieving effective enrichment of nickel; then, a sulfuric acid solution is added to the nickel-containing organic liquid for stripping to break the nickel-organic complex, and the nickel ions are efficiently transferred back to the aqueous phase to form a nickel-rich liquid. This operation not only improves the separation purity of nickel, but also realizes the recycling of chemical agents, providing a guarantee for the subsequent precipitation to generate high-purity nickel carbonate. DETAILED DESCRIPTION

[0038] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0039] It should be noted that waste cadmium-nickel batteries come from scrapped energy batteries such as ships and base stations.

[0040] Example 1

[0041] This embodiment provides a method for recovering anode powder from waste cadmium-nickel batteries, which specifically includes the following steps:

[0042] S1. Take 10 g of nickel anode powder and 20 g of activation liquid, mix them, and place them in a ball mill for ball milling activation treatment to obtain anode slurry. The activation liquid is a mixed liquid of water and ethanol with a volume ratio of 100:6.

[0043] S2. Place the anode slurry in a 6 M hydrochloric acid solution. The solid-liquid ratio of the anode slurry to the hydrochloric acid solution is 1:9. Leach at 75 °C for 9 h, then perform solid-liquid separation to separately collect the first-stage residue phase and the first-stage leaching solution. Place the first-stage residue phase in a mixed solution of sulfuric acid and ammonium chloride. The solid-liquid ratio of the first-stage residue phase to the mixed solution is 1:4. The concentration of sulfuric acid in the mixed solution is 6 M, the concentration of ammonium chloride is 0.3 M, and the volume ratio of sulfuric acid to ammonium chloride is 9:1. Leach in a closed environment at 105 °C for 6 h. After the second-stage leaching is completed, obtain the second-stage leaching solution. Combine the first-stage leaching solution and the second-stage leaching solution to obtain the leached anode solution for the next step of treatment.

[0044] S3. In the leached anode solution, first add 1 M hydrogen peroxide. The mass ratio of the leached anode solution to hydrogen peroxide is 90:1. React at 65 °C for 3 h. After the purification reaction is completed, perform solid-liquid separation to obtain the first anode solution. Add 1 M potassium hydroxide to the first anode solution. The mass ratio of the first anode solution to potassium hydroxide is 90:1. React at 85 °C for 5 h, then perform solid-liquid separation to obtain the purified anode solution.

[0045] S4. Add the extractant C272 to the purified anode solution for extraction. After the extraction is completed, obtain the nickel-containing organic liquid, and then add sulfuric acid solution to it for back-extraction to obtain the nickel-rich liquid.

[0046] S5. Add potassium carbonate to the nickel-rich liquid. The mass ratio of potassium carbonate to the nickel-rich liquid is 1:5 to obtain the product nickel carbonate.

[0047] Example 2

[0048] S1. Take 10 g of nickel anode powder and 10 g of activation liquid, mix them, and place them in a ball mill for ball milling activation treatment to obtain anode slurry. The activation liquid is a mixed liquid of water and methanol with a volume ratio of 100:2.

[0049] S2. Place the anode mud in a mixed solution of 5M hydrochloric acid solution and sulfuric acid solution. The volume ratio of the hydrochloric acid solution to the sulfuric acid solution is 1:1, and the solid-liquid ratio of the anode mud to the mixed solution is 1:8. Leach at 70 °C for 4 h, then perform solid-liquid separation, and collect the first-stage slag phase and the first-stage leachate respectively; Place the first-stage slag phase in a mixed solution of sulfuric acid and ammonium chloride. The solid-liquid ratio of the first-stage slag phase to the mixed solution is 1:3. The concentration of sulfuric acid in the mixed solution is 2M, the concentration of ammonium chloride is 0.2M, and the volume ratio of sulfuric acid to ammonium chloride is 8:1. Leach in a closed environment at 90 °C for 8 h. After the second-stage leaching is completed, obtain the second-stage leachate. Combine the first-stage leachate and the second-stage leachate to obtain the leached anode solution for the next treatment.

[0050] S3. In the leached anode solution, first add 0.2M ammonium persulfate. The mass ratio of the leached anode solution to ammonium persulfate is 80:1. React at 50 °C for 4 h. After the purification reaction is completed, perform solid-liquid separation to obtain the first anode solution; Add 0.2M sodium hydroxide to the first anode solution. The mass ratio of the first anode solution to sodium hydroxide is 80:1. React at 80 °C for 6 h, then perform solid-liquid separation to obtain the purified anode solution.

[0051] S4. Add the extractant P204 to the purified anode solution for extraction. After the extraction is completed, obtain the nickel-containing organic solution, and then add sulfuric acid solution to it for back-extraction to obtain the nickel-rich solution.

[0052] S5. Add potassium carbonate to the nickel-rich solution. The mass ratio of potassium carbonate to the nickel-rich solution is 1:4 to obtain the product nickel carbonate.

[0053] Example 3

[0054] S1. Take 10 g of nickel anode powder and 30 g of activation solution and mix them, then place them in a ball mill for ball milling activation treatment to obtain the anode mud. The activation solution is a mixed solution of water and ethylene glycol with a volume ratio of 100:10.

[0055] S2. Place the anode mud in 5M acetic acid solution. The solid-liquid ratio of the anode mud to the acetic acid solution is 1:10. Leach at 80 °C for 2 h, then perform solid-liquid separation, and collect the first-stage slag phase and the first-stage leachate respectively; Place the first-stage slag phase in a mixed solution of sulfuric acid and ammonium chloride. The solid-liquid ratio of the first-stage slag phase to the mixed solution is 1:5. The concentration of sulfuric acid in the mixed solution is 10M, the concentration of ammonium chloride is 0.5M, and the volume ratio of sulfuric acid to ammonium chloride is 10:1. Leach in a closed environment at 120 °C for 4 h. After the second-stage leaching is completed, obtain the second-stage leachate. Combine the first-stage leachate and the second-stage leachate to obtain the leached anode solution for the next treatment.

[0056] S3. In the leached anolyte, first add 2 M peracetic acid. The mass ratio of the leached anolyte to peracetic acid is 100:1. React at 80 °C for 2 h. After the purification reaction ends, perform solid-liquid separation to obtain the first anolyte. Add 2 M potassium hydroxide to the first anolyte. The mass ratio of the first anolyte to potassium hydroxide is 100:1. React at 90 °C for 4 h and then perform solid-liquid separation to obtain the purified anolyte.

[0057] S4. Add the purified anolyte to the extractant P507 for extraction. After the extraction is completed, obtain the nickel-containing organic solution, and then add sulfuric acid solution to it for back-extraction to obtain the nickel-rich solution.

[0058] S5. Add potassium carbonate to the nickel-rich solution. The mass ratio of potassium carbonate to the nickel-rich solution is 1:6 to obtain the product nickel carbonate.

[0059] Comparative Example 1

[0060] This comparative example provides a method for recovering the anode powder of waste cadmium-nickel batteries. The difference from Example 1 is that the two-stage leaching treatment is not carried out, and the specific steps are as follows:

[0061] S1. Take 10 g of nickel anode powder and 20 g of activation solution and mix them, place them in a ball mill for ball milling activation treatment to obtain anode slurry. The activation solution is a mixed solution of water and ethanol with a volume ratio of 100:6.

[0062] S2. Place the anode slurry in 6 M hydrochloric acid solution. The solid-liquid ratio of the anode slurry to the hydrochloric acid solution is 1:9. Leach at 75 °C for 9 h, perform solid-liquid separation to obtain the leached anolyte, and carry out the next treatment.

[0063] Steps S3 - S5 are the same as those in Example 1.

[0064] Comparative Example 2

[0065] This comparative example provides a method for recovering the anode powder of waste cadmium-nickel batteries. The difference from Example 1 is that the secondary purification treatment is not carried out, and the specific steps are as follows:

[0066] S1 - S2 are the same as those in Example 1.

[0067] S3. In the leached anolyte, first add 1 M hydrogen peroxide. The mass ratio of the leached anolyte to hydrogen peroxide is 90:1. React at 65 °C for 8 h. After the purification reaction ends, perform solid-liquid separation to obtain the purified anolyte.

[0068] S4. Add the purified anolyte to the extractant C272 for extraction. After the extraction is completed, obtain the nickel-containing organic solution, and then add sulfuric acid solution to it for back-extraction to obtain the nickel-rich solution.

[0069] S5. Potassium carbonate is added to the nickel-rich solution, and the mass ratio of potassium carbonate to the nickel-rich solution is 1:5 to obtain nickel carbonate as the product.

[0070] Comparative Example 3

[0071] This comparative example provides a method for recycling the anode powder of waste cadmium-nickel batteries. The difference from Example 1 is that the extraction-stripping treatment is not carried out, and the specific steps are as follows:

[0072] S1 - S3 are the same as in Example 1.

[0073] S4. Potassium carbonate is added to the purified anode solution prepared in step S3, and the mass ratio of potassium carbonate to the nickel-rich solution is 1:5 to obtain nickel carbonate as the product.

[0074] Comparative Example 4

[0075] This comparative example provides a method for recycling the anode powder of waste cadmium-nickel batteries. The difference from Example 1 is that the purification treatment is carried out first and then the leaching treatment. The specific steps are as follows:

[0076] S1. Take 10 g of nickel anode powder and mix it with 20 g of activation solution, and place it in a ball mill for ball milling activation treatment to obtain anode slurry, where the activation solution is a mixed solution of water and ethanol with a volume ratio of 100:6.

[0077] S2. In the anode slurry, first add 1 M hydrogen peroxide, and the mass ratio of the leaching anode solution to hydrogen peroxide is 90:1. React at 65 °C for 3 h. After the purification reaction ends, solid-liquid separation is carried out to obtain the first anode solution; add 1 M potassium hydroxide to the first anode solution, and the mass ratio of the first anode solution to potassium hydroxide is 90:1. React at 85 °C for 5 h, and then carry out solid-liquid separation to obtain the purified anode solution.

[0078] S3. Place the purified anode solution in a 6 M hydrochloric acid solution, and the solid-liquid ratio of the purified anode solution to the hydrochloric acid solution is 1:9. Leach at 75 °C for 9 h, and carry out solid-liquid separation to collect the first-stage slag phase and the first-stage leaching solution respectively; place the first-stage slag phase in a mixed solution of sulfuric acid and ammonium chloride, and the solid-liquid ratio of the first-stage slag phase to the mixed solution is 1:4. The concentration of sulfuric acid in the mixed solution is 6 M, and the concentration of ammonium chloride is 0.3 M. Leach in a closed environment at 105 °C for 6 h. After the second-stage leaching ends, obtain the second-stage leaching solution. Combine the first-stage leaching solution and the second-stage leaching solution to obtain the leaching anode solution for the next step of treatment.

[0079] S4. Add the extraction agent C272 to the leaching anode solution for extraction. After the extraction is completed, obtain the nickel-containing organic solution, and then add sulfuric acid solution for stripping to obtain the nickel-rich solution.

[0080] S5. Potassium carbonate is added to the nickel-rich solution, and the mass ratio of potassium carbonate to the nickel-rich solution is 1:5 to obtain nickel carbonate as the product.

[0081] Comparative Example 5

[0082] This comparative example provides a method for recycling the anode powder of waste cadmium-nickel batteries. The difference from Example 1 is the different two-stage leaching treatment, which specifically includes the following steps:

[0083] S1. 10 g of nickel anode powder and 20 g of activation solution are mixed and placed in a ball mill for ball milling activation treatment to obtain anode slurry. The activation solution is a mixed solution of water and ethanol with a volume ratio of 100:6.

[0084] S2. The anode slurry is placed in a 6 M hydrochloric acid solution. The solid-liquid ratio of the anode slurry to the hydrochloric acid solution is 1:9, and leaching is carried out at 75 °C for 9 h. Solid-liquid separation is performed, and the first-stage slag phase and the first-stage leaching solution are collected separately. The first-stage slag phase is placed in a sulfuric acid solution. The solid-liquid ratio of the first-stage slag phase to the sulfuric acid solution is 1:4, the concentration of the sulfuric acid solution is 6 M, and leaching is carried out at 105 °C for 6 h. After the two-stage leaching is completed, the second-stage leaching solution is obtained. The first-stage leaching solution and the second-stage leaching solution are combined to obtain the leached anode solution for the next treatment.

[0085] S3 - S5 are the same as those in Example 1.

[0086] Performance Detection

[0087] The purity and recovery rate of the recycled nickel in the examples and comparative examples are detected. For purity detection: The nickel content in the nickel carbonate samples prepared in the examples and comparative examples is detected by mass spectrometry (ICP-MS). Purity = mass of nickel in the sample / total mass of the sample × 100%. Recovery rate: Before the recycling treatment, the nickel content in the anode powder of waste cadmium-nickel batteries is detected by mass spectrometry (ICP-MS). Nickel recovery rate = mass of the actually recycled nickel in the product / mass of nickel in the anode powder of waste cadmium-nickel batteries × 100%. The results are shown in Table 1.

[0088] Table 1 Recovery rate and recovery purity of nickel

[0089] Recovery rate (%) Purity (%) Example 1 99.3 99.6 Example 2 98.9 99.6 Example 3 99.7 99.8 Comparative Example 1 92.0 93.5 Comparative Example 2 93.8 92.0 Comparative Example 3 90.5 92.3 Comparative Example 4 91.5 93.2 Comparative Example 5 95.4 97.5

[0090] As can be seen from Table 1, the technical solution of the embodiment of the present invention can achieve efficient recovery of nickel; compared with Example 1, the nickel recovery rate and purity in Comparative Example 1 are both reduced, probably because some refractory nickel elements may not be fully replenished, resulting in a slight decrease in the recovery efficiency and product purity; compared with Example 1, the nickel recovery rate and purity in Comparative Example 2 are both reduced, probably because although the single-stage purification treatment can remove some impurities, the lack of subsequent high-temperature alkaline precipitation to further remove the remaining interfering ions will inevitably lead to a relatively high impurity content in the product; compared with Example 1, the nickel recovery rate and purity in Comparative Example 3 are both reduced, probably because the lack of a step for highly selective enrichment and separation of nickel ions results in the co-precipitation of the intervening impurities and nickel; compared with Example 1, the nickel recovery rate and purity in Comparative Example 4 are both reduced, indicating that leaching first and then purification treatment can improve the nickel recovery efficiency; compared with Example 1, the nickel recovery rate and purity in Comparative Example 5 are both reduced, and the solubilizing effect of ammonium chloride is beneficial to improving the replenishment effect of nickel.

[0091] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for recycling anode powder of waste cadmium-nickel batteries, characterized in that: It includes the following steps: S1. Activate and pretreat nickel anode powder to obtain anode slurry; S2. Mix the anode slurry with a leaching agent for two-stage leaching treatment. After the leaching reaction ends, perform solid-liquid separation to obtain leached anode liquid; S3. Mix the leached anode liquid with a purifying agent for secondary purification treatment. After the purification reaction ends, perform solid-liquid separation to obtain purified anode liquid; S4. Perform extraction and back-extraction treatment on the purified anode liquid to obtain nickel-rich liquid; S5. Add a precipitating agent to the nickel-rich liquid to obtain nickel carbonate.

2. The method for recycling anode powder of waste cadmium-nickel batteries according to claim 1, characterized in that: In step S1, the activation pretreatment includes: ball-milling the nickel anode powder in an activation liquid, and the solid-liquid ratio of the nickel anode powder to the activation liquid is 1:1 - 3; the activation liquid is a mixed solution of water and alcohol.

3. The method for recycling anode powder of waste cadmium-nickel batteries according to claim 2, wherein: The volume ratio of water to alcohol in the activation liquid is 100:2 - 10; the alcohol includes one or more of methanol, ethanol, ethylene glycol, and isopropanol.

4. The method for recycling anode powder of waste cadmium-nickel batteries according to claim 1, characterized in that: Step S2 specifically includes: S21. Mix the anode slurry with a first leaching agent for the first-stage leaching treatment. After the leaching reaction ends, perform solid-liquid separation to obtain the first-stage slag phase and the first-stage leaching liquid; S22. Mix the first-stage slag phase with a second leaching agent in a closed environment for the second-stage leaching treatment. After the leaching reaction ends, perform solid-liquid separation to obtain the second-stage slag phase and the second-stage leaching liquid; S23. Mix the first-stage leaching liquid and the second-stage leaching liquid evenly to obtain leached anode liquid.

5. The method for recycling the anode powder of waste cadmium-nickel batteries according to claim 4, characterized in that: In step S21, the solid-liquid ratio of the anode slurry to the leaching agent is 1:8 - 10, the temperature of the first-stage leaching treatment is 70 - 80°C, and the time is 2 - 4 h; in step S22, the solid-liquid ratio of the first-stage slag phase to the leaching agent is 1:3 - 5, the temperature of the second-stage leaching treatment is 90 - 120°C, and the time is 4 - 8 h.

6. The method for recycling anode powder of waste cadmium-nickel batteries according to claim 4, characterized in that: The first leaching agent includes one or more of sulfuric acid, nitric acid, hydrochloric acid, acetic acid, and oxalic acid; the second leaching agent is a mixed solution of sulfuric acid and ammonium chloride.

7. The method for recycling the anode powder of waste cadmium-nickel batteries according to claim 1, wherein: Step S3 specifically includes: S31. Mix the leached anode liquid with a first purifying agent for the first-stage purification treatment. After the purification reaction ends, perform solid-liquid separation to obtain the first anode liquid; S32. Mix the first anode liquid with a second purifying agent for the second-stage purification treatment. After the purification reaction ends, perform solid-liquid separation to obtain purified anode liquid.

8. The method for recycling the anode powder of waste cadmium-nickel batteries according to claim 7, characterized in that: In step S31, the mass ratio of the leached anode liquid to the first purifying agent is 80 - 100:1, the temperature of the first-stage purification treatment is 50 - 80°C, and the time is 2 - 4 h; in step S32, the mass ratio of the first anode liquid to the second purifying agent is 80 - 100:1, the temperature of the second-stage purification treatment is 80 - 90°C, and the time is 4 - 6 h.

9. The method for recycling anode powder of waste cadmium-nickel batteries according to claim 8, characterized in that: The first purifying agent includes one or more of hydrogen peroxide, ammonium persulfate, peracetic acid, and sodium chlorite; the second purifying agent includes potassium hydroxide and / or sodium hydroxide.

10. A method for recovering anode powder from waste cadmium-nickel batteries according to claim 1, characterized in that: The extractant includes one of C272, P204, and P507; the precipitating agent includes potassium carbonate.