Leaching method and recycling method of metal in nickel cobalt lithium manganate positive plate

Abstract

The invention provides a leaching method and a recycling method of metal in a nickel cobalt lithium manganate positive plate. The leaching method comprises the following steps: pre-treating a nickel cobalt lithium manganate positive plate disassembled from a waste battery to obtain positive powder; preparing a gluconic acid leaching agent containing gluconobacter oxydans, and electrolyzing the positive electrode powder at the voltage of 2.0-2.5 V by adopting a double-chamber electrochemical electrolytic tank to obtain a leaching solution containing Li < + >, Ni < 2 + >, Co < 2 + > and Mn < 2 + >. Positive electrode powder, a gluconic acid leaching agent and a ferrous sulfate aqueous solution are put into a cathode chamber of a double-chamber electrochemical electrolytic tank, and an inorganic alkali aqueous solution is contained in an anode chamber of the double-chamber electrochemical electrolytic tank; the leaching efficiency can be improved and the leaching rate is high through the effects of dissolution of gluconic acid, electrolysis for hydrogen release and auxiliary reduction of Fe < 2 + >.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling and utilization of lithium ion batteries, in particular to the recycling of positive electrode materials, and more particularly to a method for leaching and recycling metals in nickel-cobalt-manganese-lithium positive electrode sheets. Background Art

[0002] With the rapid industrialization of new energy vehicles, their sales will soar, and the number of lithium-ion power batteries will also increase exponentially. At the same time, the environmental pollution problem and the reasonable resource recycling of waste lithium-ion power batteries have become a common concern in the industry and a problem that needs to be solved urgently. Solving this problem is not only conducive to environmental protection, but also conducive to the recycling of resources, and has great practical significance.

[0003] At present, the main materials recycled from waste lithium-ion batteries are negative electrode current collectors (commonly copper foil), positive electrode current collectors (commonly aluminum foil), positive electrode active materials and negative electrode active materials. Among them, the recycling of positive electrode active materials mainly includes two processes: wet process and pyrometallurgical process. The wet process has become the mainstream recycling solution due to its mild conditions and low energy consumption. It mainly includes pretreatment, leaching, recycling and other links.

[0004] Pretreatment is mainly to selectively separate higher-value cathode materials, remove lower-value components or organic solvents, and reduce the adverse effects of subsequent leaching processes. The main methods include discharge, crushing, dissolution, pyrolysis, etc. Leaching is mainly the process of selectively extracting and recovering various metals from the cathode materials obtained by pretreatment. The main methods include wet leaching, microbial leaching, water leaching, etc. Recovery is the process of recovering various metal ions from the leachate using extraction, precipitation, electrochemical and other methods. Among them, the leaching process is the key step in the recovery of cathode materials, and its leaching rate directly affects the subsequent recovery rate. Although the current leaching process is very mature, there are still many problems.

[0005] The wet leaching of waste lithium-ion battery positive electrode materials is mainly acid leaching, using inorganic acid (sulfuric acid, hydrochloric acid or nitric acid) + hydrogen peroxide as the most common leaching system. The combination of inorganic acid + hydrogen peroxide can leach positive electrode materials well, but inorganic acid is highly corrosive, has high requirements for equipment, and is prone to produce harmful gases.

[0006] Microbial leaching utilizes the complexation, reduction, oxidation, and leaching of certain specific microorganisms and metabolites to achieve the purpose of recovering and dissolving valuable metals. Although microbial leaching has advantages such as environmental friendliness, low cost, and low acid consumption, it also has shortcomings such as long cycle, difficulty in strain cultivation, and low efficiency. Microbial leaching has a long cycle.

[0007] Water leaching is to convert the cathode material obtained by pretreatment into lithium carbonate components by reduction roasting, and then recover lithium by water leaching / carbonation water leaching. Water leaching of lithium elements in waste materials has the characteristics of high efficiency and easy product processing, but most of them need roasting treatment, which still has the disadvantages of slightly high energy consumption and easy pollution. Summary of the invention

[0008] Based on the above problems, the purpose of the present invention is to provide a leaching method and a recovery method for metals in nickel-cobalt-manganese-lithium positive electrode sheets. This leaching method not only has high leaching efficiency and short leaching time, but also has low energy consumption, does not require the use of strong acid, and has low acid requirements.

[0009] To achieve the above-mentioned object, the first aspect of the present invention provides a method for leaching metal from a nickel-cobalt-manganese-lithium positive electrode sheet, comprising: (1) Preparation of materials The nickel-cobalt-manganese-oxide lithium positive electrode sheets disassembled from waste batteries are pre-treated to obtain positive electrode powder; (2) Bioelectrolysis leaching Prepare a gluconic acid leaching agent containing Gluconobacter oxidans, use a double-chamber electrochemical electrolytic cell and electrolyze the positive electrode powder at a voltage of 2.0-2.5V to obtain a Li-containing + 、Ni 2+ 、Co 2+ and Mn 2+ The positive electrode powder, the gluconic acid leaching agent and the ferrous sulfate aqueous solution are placed in the cathode chamber of the double-chamber electrochemical electrolytic cell, and the anode chamber of the double-chamber electrochemical electrolytic cell contains an inorganic alkali aqueous solution.

[0010] The leaching method adopted by the present invention is essentially an electrolysis-assisted biological leaching technology. Gluconobacter oxidans is added to the electrolyte. This bacterium can produce gluconic acid, which is used to convert the insoluble metals in the positive electrode sheet of the nickel-cobalt-manganese-based lithium system into soluble metals during electrolysis, thereby completing the leaching process. Compared with the traditional pure biological leaching process, it has the advantages of high metal leaching efficiency and short leaching time. Specifically, the positive electrode powder is put into the gluconic acid leaching agent, and Li is dissociated under the dissolution of gluconic acid. + 、Ni 3+ 、Co 3+ and Mn 4+ After the electrolysis is powered on, the anode end of the double-chamber electrochemical cell undergoes water decomposition and oxygen evolution reaction, and the generated H + Passing through the membrane in the dual-chamber electrochemical cell into the cathode chamber, further promoting the dissociation of the positive electrode powder. At the same time, in the cathode chamber, Fe 2+ The assisted reduction of Ni 3+ 、Co 3+ and Mn 4+ Reduced to Ni2+ 、 Co 2+ and Mn 2+ during the process, while Fe 2+ itself is oxidized to Fe 3+ . When the concentration of Fe 3+ in the electrolyte continuously increases, due to the reduction of the cathode electrode itself, Fe 3+ will be reduced to Fe 2+ , promoting the regeneration of Fe 2+ , thus realizing the closed-loop of Fe 2+ accelerating the metal leaching reaction. During this process, the assisted reduction of Fe 2+ can accelerate the dissociation of the positive electrode powder. Therefore, through the dissolution of gluconic acid, electrolytic hydrogen evolution, and the assisted reduction of Fe 2+ , the leaching efficiency can be improved and the leaching rate is high.

[0011] In addition, a positive electrode powder, a gluconic acid leaching agent, and an aqueous solution of ferrous sulfate are provided in the cathode chamber of the two-chamber electrochemical electrolytic cell, and an aqueous solution of inorganic base is contained in the anode chamber. According to the characteristic that H + produced by the electrolysis of water in the two-chamber electrochemical electrolytic cell can pass through the membrane in the two-chamber electrochemical electrolytic cell, the acidity and alkalinity of the cathode (acidic) and anode (alkaline) can be maintained, and at the same time, material crossover can be prevented during the leaching process. The characteristic of maintaining the acidity and alkalinity of the cathode and anode systems through the electrolysis of water ensures the efficient progress of the bioelectrolytic leaching reaction. Compared with the traditional acid leaching method, continuously supplying H + to the cathode electrolyte (through the ionization of water) enables the leaching process to be carried out at a lower acid concentration (such as 75 - 300 mM gluconic acid), thus avoiding the disadvantages of using strong acids and also avoiding high-energy-consuming methods such as roasting.

[0012] As a technical solution of the present invention, the lithium nickel cobalt manganese oxide-based positive electrode sheet includes a positive electrode active material, a binder, and a conductive agent. The chemical formula of the positive electrode active material is LiNi x Co y Mn z M (1-x-y-z) O 2 , where M is at least one of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, and Ti, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z ≤ 1. The binder includes PVDF, and the conductive agent includes at least one of conductive carbon black, conductive graphite, carbon fiber, carbon nanotube, and graphene.

[0013] As a technical solution of the present invention, the pretreatment includes crushing the nickel cobalt manganese oxide lithium positive electrode sheet disassembled from the waste battery to obtain a powder with a particle size of 70-90 μm, and then using a 100-300 mesh sieve coupled with a vibrating agitator to screen to obtain the positive electrode powder.

[0014] As a technical solution of the present invention, the preparation method of the gluconic acid extractant comprises culturing Gluconobacter oxydans in a glucose modified culture medium at 20-40°C and 100-200 rpm on a shaker for 30-60 hours, filtering the filtrate to obtain the filtrate and then diluting the filtrate.

[0015] As a technical solution of the present invention, the concentration of gluconic acid in the gluconic acid leaching agent is 75-300 mmol / L.

[0016] As a technical solution of the present invention, the cathode chamber and anode chamber of the dual-chamber electrochemical electrolytic cell are separated by a proton exchange membrane or an ion exchange membrane, an iridium oxide coated titanium mesh is inserted into the cathode chamber as a cathode, and stainless steel is inserted into the anode chamber as an anode.

[0017] As a technical solution of the present invention, the concentration of the ferrous sulfate aqueous solution is 0.5-0.8 mol / L, and the molar ratio of iron in the ferrous sulfate aqueous solution to cobalt in the positive electrode powder in the cathode chamber is 1:6-8.

[0018] As a technical solution of the present invention, the inorganic alkali aqueous solution is a 0.8-1.2 mol / L potassium hydroxide aqueous solution.

[0019] As a technical solution of the present invention, an immersion stirrer is provided in the cathode chamber, and the stirring speed is 500-700 r / min.

[0020] The second aspect of the present invention provides a method for recovering metals in a nickel-cobalt-manganese-lithium positive electrode sheet, comprising: (I) Obtaining a Li-containing cathode according to the aforementioned method for leaching metal from a lithium nickel-cobalt-manganese oxide cathode sheet + 、Ni 2+ 、Co 2+ and Mn 2 + of the leachate; (II) Post-treatment of the leachate to recover Li + 、Ni 2+ 、Co 2+ and Mn 2+ , the post-treatment includes at least one operation of precipitation, adsorption and extraction.

[0021] The leaching method of the present invention can recover a high proportion of Li + 、Ni2+ , Co 2+ and Mn 2+ . Detailed implementation mode

[0022] The present invention provides a method for leaching and recycling metals in a lithium nickel cobalt manganese oxide-based positive electrode sheet, which can achieve high-proportion leaching and recycling of Li, Ni, Co and Mn.

[0023] The lithium nickel cobalt manganese oxide-based positive electrode sheet of the present invention refers to a positive electrode sheet containing a lithium nickel cobalt manganese oxide-based positive electrode active material. The lithium nickel cobalt manganese oxide-based positive electrode sheet includes a positive electrode active material, a binder and a conductive agent. The positive electrode active material includes a lithium nickel cobalt manganese oxide-based positive electrode active material, and its chemical formula is LiNi x Co y Mn z M (1-x-y-z) O 2 , where M is at least one of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V and Ti, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z ≤ 1. The binder includes PVDF. The conductive agent includes at least one of conductive carbon black, conductive graphite, carbon fiber, carbon nanotube and graphene. The mass ratio of the positive electrode active material, the binder and the conductive agent can be but is not limited to 85-98:0.5-3.0:0.5-3.0. The positive electrode sheet can be prepared by making a slurry of the positive electrode active material, the binder and the conductive agent with a solvent and coating it on a positive electrode current collector and drying, rolling, etc.

[0024] The method for leaching metals in the lithium nickel cobalt manganese oxide-based positive electrode sheet of the present invention includes the following steps.

[0025] (1) Preparation of materials The lithium nickel cobalt manganese oxide-based positive electrode sheet disassembled from a waste battery is pretreated to obtain positive electrode powder; (2) Bioelectrolytic leaching Prepare a gluconic acid leaching agent containing Gluconobacter oxydans, and use a two-chamber electrochemical electrolytic cell to electrolyze the positive electrode powder at a voltage of 2.0-2.5V to obtain a leaching solution containing Li + , Ni 2+ , Co 2+ and Mn 2+ .

[0026] Among them, the pretreatment includes crushing the lithium nickel cobalt manganese oxide-based positive electrode sheet disassembled from the waste battery to obtain a powder with a particle size of 70-90 μm, and then screening it with a 100-300 mesh sieve coupled with a vibrating stirrer to obtain positive electrode powder.

[0027] The preparation method of the gluconic acid extractant comprises culturing Gluconobacter oxidans in a glucose modified medium at 20-40°C and 100-200rpm for 30-60h, filtering to obtain the filtrate and then diluting. Gluconobacter oxidans (B58 strain) can use commercial strains, such as those from KBR-BN0312 of Keborui, Zhongke Ruipu, etc. The glucose modified medium may include 2.7g of peptone, 5.0g of sodium chloride, 0.3g of dipotassium hydrogen phosphate, 0.1g of glucose, 3.0ml of 1% bromothymol blue aqueous solution, 5.0g of agar, and 1000ml of distilled water. The temperature of the shaking culture may be, but is not limited to, 20°C, 22°C, 24°C, 26°C, 28°C, 30°C, 32°C, 34°C, 36°C, 38°C, and 40°C. The frequency of the shaking table oscillation can be, but is not limited to, 100rpm, 110rpm, 120rpm, 130rpm, 140rpm, 150rpm, 160rpm, 170rpm, 180rpm, 190rpm, 200rpm. The time of shaking table oscillation can be, but is not limited to, 30h, 35h, 40h, 45h, 50h, 55h, 60h. The filtrate can be obtained by filtering through a mesh of 0.20-0.25μm, and the pH value of the filtrate is 2.0-2.5. The filtrate is diluted to a concentration of 75-300mmol / L of gluconic acid to obtain a gluconic acid leaching agent, and the concentration of gluconic acid can be, but is not limited to, 75mmol / L, 100mmol / L, 125mmol / L, 150mmol / L, 175mmol / L, 200mmol / L, 225mmol / L, 250mmol / L, 275mmol / L, 300mmol / L.

[0028] The cathode chamber and anode chamber of the double-chamber electrochemical cell are separated by a proton exchange membrane or an ion exchange membrane. An iridium oxide-coated titanium mesh is inserted into the cathode chamber as a cathode, and stainless steel is inserted into the anode chamber as an anode. The electrolysis voltage is 2.0~2.5V. The positive electrode powder, gluconic acid leaching agent and ferrous sulfate aqueous solution are placed in the cathode chamber of the double-chamber electrochemical cell, and the anode chamber of the double-chamber electrochemical cell contains an inorganic alkali aqueous solution. The proton exchange membrane or ion exchange membrane allows small molecules of H + Shuttle, and hinder Li + 、Ni 2+ 、Co 2+ and Mn 2+Shuttle between the anode chamber and the cathode chamber. The concentration of the ferrous sulfate aqueous solution is 0.5~0.8mol / L. As an example, it can be but not limited to 0.5mol / L, 0.6mol / L, 0.7mol / L, and 0.8mol / L. Specifically, the concentration of the ferrous sulfate aqueous solution can be adjusted according to the metal ion content of the positive electrode powder. The molar ratio of iron in the ferrous sulfate aqueous solution and cobalt in the positive electrode powder in the cathode chamber is 1:6~8. As an example, the molar ratio of the two can be but not limited to 1:6, 1:7, and 1:8. The inorganic alkali aqueous solution is a 0.8~1.2mol / L potassium hydroxide aqueous solution. As an example, the concentration of the potassium hydroxide aqueous solution can be but not limited to 0.8mol / L, 0.9mol / L, 1.0mol / L, 1.1mol / L, and 1.2mol / L. The inorganic alkali aqueous solution mainly provides ionized water, so its concentration can also be adjusted according to actual conditions.

[0029] The positive electrode powder is solid. In order to facilitate the reaction in the electrolyte of a heterogeneous mixture, an immersion stirrer is provided in the cathode chamber, and the stirring speed is 500~700r / min. As an example, the stirring speed can be but is not limited to 500r / min, 520r / min, 540r / min, 560r / min, 580r / min, 600r / min, 620r / min, 640r / min, 660r / min, 680r / min, and 700r / min.

[0030] The Li-containing + 、Ni 2+ 、Co 2+ and Mn 2+ The leaching solution can be further treated to recover Li + 、Ni 2+ 、Co 2+ and Mn 2+ The post-treatment includes at least one of precipitation, adsorption and extraction. The precipitation can be carried out by using an alkali solution (such as sodium hydroxide, potassium hydroxide or ammonia) to precipitate Ni 2+ 、Co 2+ and Mn 2+ , using lithium precipitants (such as sodium carbonate, potassium carbonate, sodium phosphate or potassium phosphate) to precipitate Li +. Adsorption is the use of different adsorption resins (such as chelating resins containing phosphate groups, phosphite groups, sulfonic acid groups, hypophosphite groups or amino groups; using peanut shells, reed straw, bamboo shells, buckwheat shells, rice straw or grapefruit peels after pyrolysis of biochar) to treat different metal ions by chelation or adsorption. Extraction is the use of different extractants (such as Mextral 54-100 1-phenyl-1,3-decanedione, P507 2-ethylhexyl phosphate-2-ethylhexyl ester and C272 bis (2,4,4-trimethylpentyl) phosphonic acid) to extract different metal ions. Post-treatment can be carried out by one of precipitation, adsorption and extraction operations, or by a combination of multiple operations. It mainly depends on the recovery of Ni 2+ 、Co 2+ and Mn 2+ , or multiple metal ions are recovered together.

[0031] In order to better illustrate the purpose, technical scheme and beneficial effects of the present invention, the present invention will be further described below in conjunction with specific embodiments. It should be noted that the following implementation method is a further explanation of the present invention and should not be used as a limitation of the present invention.

[0032] Example 1 This embodiment is a method for leaching metals from a nickel-cobalt-manganese-lithium oxide positive electrode sheet, and the steps are as follows.

[0033] (1) Preparation of materials The nickel-cobalt-manganese-based positive electrode sheets (positive electrode active material: NCM523, binder: PVDF, conductive agent: SP, mass ratio of the three: 97:1.5:1.5) removed from the waste ternary lithium-ion batteries were crushed to obtain a powder with a particle size of 70-90μm. Subsequently, the obtained powder was screened using a #200 mesh screen coupled with a vibrating agitator to obtain positive electrode powder.

[0034] (2) Bioelectrolysis leaching Gluconobacter oxydans (strain B58, KBR-BN0312) was cultured in a glucose-modified medium at 30°C with a shaking table at 150 rpm for 42 h, and then the filtrate (pH 2.2) was obtained by filtration (0.22 μm), and diluted with pure water to obtain a solution with a gluconic acid concentration of 150 mmol / L as a gluconic acid extractant. The glucose-modified medium includes 2.7 g of peptone, 5.0 g of sodium chloride, 0.3 g of dipotassium hydrogen phosphate, 0.1 g of glucose, 3.0 ml of 1% bromothymol blue aqueous solution, 5.0 g of agar, and 1000 ml of distilled water.

[0035] A double-chamber electrochemical electrolytic cell is used, with a ferrous sulfate aqueous solution with a concentration of 0.6 mol / L as the electrolyte, and a molar ratio of Fe to Co of 1:7. The cathode chamber and the anode chamber of the double-chamber electrochemical electrolytic cell are separated by a proton exchange membrane, and an iridium oxide-coated titanium mesh is inserted into the cathode chamber as the cathode, and stainless steel is inserted into the anode chamber as the anode. The cathode chamber contains a mixture of positive electrode powder, ferrous sulfate aqueous solution and gluconic acid leaching agent. The anode chamber contains a 1M potassium hydroxide aqueous solution. An immersed mechanical stirrer is set in the cathode chamber to stir the mixture, and the stirring speed is 600r / min.

[0036] The double-chamber electrochemical cell uses a voltage of 2.0~2.5V to electrolyze the positive electrode powder to obtain Li + 、Ni 2+ 、Co 2+ and Mn 2+ of the leachate.

[0037] Example 2 This embodiment is a method for leaching metals from a nickel-cobalt-manganese-lithium oxide positive electrode sheet, and the steps are as follows.

[0038] (1) Preparation of materials The nickel-cobalt-manganese-based positive electrode sheets (positive electrode active material: NCM811, binder: PVDF, conductive agent: SP, mass ratio of the three: 97:2:1) removed from the waste ternary lithium-ion batteries were crushed to obtain a powder with a particle size of 70-90μm. Subsequently, the obtained powder was screened using a #200 mesh screen coupled with a vibrating agitator to obtain positive electrode powder.

[0039] (2) Bioelectrolysis leaching Gluconobacter oxydans (strain B58, Zhongke Ruipu) was cultured in a glucose modified medium at 35°C with shaking at 200 rpm for 55 h, and then the filtrate (pH 2.1) was obtained by filtration (0.22 μm), and diluted with pure water to obtain a solution with a gluconic acid concentration of 270 mmol / L as a gluconic acid extractant. The glucose modified medium includes 2.7 g of peptone, 5.0 g of sodium chloride, 0.3 g of dipotassium hydrogen phosphate, 0.1 g of glucose, 3.0 ml of 1% bromothymol blue aqueous solution, 5.0 g of agar, and 1000 ml of distilled water.

[0040] A double-chamber electrochemical electrolytic cell is used, with an aqueous solution of ferrous sulfate at a concentration of 0.8 mol / L as the electrolyte, and a molar ratio of Fe to Co of 1:6. The cathode chamber and the anode chamber of the double-chamber electrochemical electrolytic cell are separated by a proton exchange membrane, and an iridium oxide-coated titanium mesh is inserted into the cathode chamber as the cathode, and stainless steel is inserted into the anode chamber as the anode. The cathode chamber contains a mixture of positive electrode powder, an aqueous solution of ferrous sulfate and a gluconic acid leaching agent. The anode chamber contains a 1M aqueous solution of potassium hydroxide. An immersed mechanical stirrer is provided in the cathode chamber to stir the mixture, and the stirring speed is 650r / min.

[0041] The double-chamber electrochemical cell uses a voltage of 2.0~2.5V to electrolyze the positive electrode powder to obtain Li + 、Ni 2+ 、Co 2+ and Mn 2+ of the leachate.

[0042] Comparative Example 1 This comparative example is a method for leaching metals from a nickel-cobalt-manganese-lithium oxide positive electrode sheet, and the steps are as follows.

[0043] (1) Preparation of materials The nickel-cobalt-manganese-based positive electrode sheets (positive electrode active material: NCM523, binder: PVDF, conductive agent: SP, mass ratio of the three: 97:1.5:1.5) removed from the waste ternary lithium-ion batteries were crushed to obtain a powder with a particle size of 70-90μm. Subsequently, the obtained powder was screened using a #200 mesh screen coupled with a vibrating agitator to obtain positive electrode powder.

[0044] (2) Electrolytic leaching A double-chamber electrochemical electrolytic cell is used, with a ferrous sulfate aqueous solution with a concentration of 0.6 mol / L as the electrolyte, and a molar ratio of Fe to Co of 1:7. The cathode chamber and the anode chamber of the double-chamber electrochemical electrolytic cell are separated by a proton exchange membrane, and an iridium oxide-coated titanium mesh is inserted into the cathode chamber as the cathode, and stainless steel is inserted into the anode chamber as the anode. The cathode chamber contains a mixture of positive electrode powder and ferrous sulfate aqueous solution. The anode chamber contains a 1M potassium hydroxide aqueous solution. An immersed mechanical stirrer is provided in the cathode chamber to stir the mixture, and the stirring speed is 600r / min.

[0045] The double-chamber electrochemical cell uses a voltage of 2.0~2.5V to electrolyze the positive electrode powder to obtain Li + 、Ni 2+ 、Co 2+ and Mn 2+ of the leachate.

[0046] Comparative Example 2 This comparative example is a method for leaching metals from a nickel-cobalt-manganese-lithium oxide positive electrode sheet, and the steps are as follows.

[0047] (1) Preparation of materials The nickel-cobalt-manganese-based positive electrode sheets (positive electrode active material: NCM811, binder: PVDF, conductive agent: SP, mass ratio of the three: 97:2:1) removed from the waste ternary lithium-ion batteries were crushed to obtain a powder with a particle size of 70-90μm. Subsequently, the obtained powder was screened using a #200 mesh screen coupled with a vibrating agitator to obtain positive electrode powder.

[0048] (2) Acid leaching The positive electrode powder was leached for 60 minutes with a mixed solution of 5.0wt.% sulfuric acid solution and 2.5wt.% hydrogen peroxide (the volume ratio of the two was 5:1), the solid-liquid ratio of the positive electrode powder to the mixed solution was 0.1g / g, and the slurry obtained after leaching was filtered to obtain the leachate.

[0049] The content of each metal ion in each leachate was obtained by ICP-OES and the leaching rate of each metal ion in the leachate of Examples 1-2 and Comparative Examples 1-2 was calculated, and the results are shown in Table 1. The leachate of Examples 1-2 and Comparative Examples 1-2 was subjected to ion recovery, and the recovery method was as follows. The recovery rates of various metal ions are shown in Table 1.

[0050] Recovery method: The leachate is added to an adsorption column filled with chelating resin HPMn-1 (provided by Jiangsu Haipu Functional Materials Co., Ltd.) for adsorption to obtain the first adsorption water, and then desorb manganese with sulfuric acid at a concentration of 5.0wt.%, and then precipitate and recover manganese with a sodium hydroxide solution at a concentration of 10.0wt.%. The first adsorption water is added to an adsorption column filled with chelating resin HP-C / N-1 for adsorption to obtain the second adsorption water, and then desorb cobalt with sulfuric acid at a concentration of 4.0wt.%, and then precipitate and recover cobalt with a sodium hydroxide solution at a concentration of 10.0wt.%. The third adsorption water is neutralized with a sodium hydroxide solution at a concentration of 10.0wt.%, nickel is recovered after precipitation, and a filtrate is obtained by filtration. At 50°C, a saturated sodium carbonate solution is added to the filtrate for reaction for 2h to crystallize lithium carbonate.

[0051] Table 1 Metal recovery rates of Examples 1-2 and Comparative Examples 1-2

[0052] From the results in Table 1, it can be seen that the leaching method of Examples 1 to 2 is through dissolution of gluconic acid, electrolysis of hydrogen, Fe 2+The three effects of auxiliary reduction can obtain a higher leaching rate, and the corresponding metal ion recovery rate is higher. Comparative Example 1 only uses electrolytic leaching, and both the leaching rate and the recovery rate are relatively high. Although Comparative Example 2 has a certain leaching rate and recovery rate, a large amount of acid is used, and the acid requirement is high.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention is described in detail with reference to the preferred embodiments, it is not limited to those listed in the embodiments. Those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A method for leaching metal from a nickel-cobalt-manganese-lithium positive electrode sheet, characterized in that: include: (1) Preparation of materials The nickel-cobalt-manganese-oxide lithium positive electrode sheets disassembled from waste batteries are pre-treated to obtain positive electrode powder; (2) Bioelectrolysis leaching Prepare a gluconic acid leaching agent containing Gluconobacter oxidans, use a double-chamber electrochemical electrolytic cell and electrolyze the positive electrode powder at a voltage of 2.0-2.5V to obtain a Li-containing + 、Ni 2+ 、Co 2+ and Mn 2+ The positive electrode powder, the gluconic acid leaching agent and the ferrous sulfate aqueous solution are placed in the cathode chamber of the double-chamber electrochemical electrolytic cell, and the anode chamber of the double-chamber electrochemical electrolytic cell contains an inorganic alkali aqueous solution.

2. The method for leaching metal from a nickel-cobalt-manganese-lithium oxide positive electrode sheet according to claim 1, characterized in that: The lithium nickel cobalt manganese oxide-based positive electrode sheet includes a positive electrode active material, a binder, and a conductive agent. The chemical formula of the positive electrode active material is LiNi x Co y Mn z M (1-x-y-z) O2, where M is at least one of Mg, Cu, Zn, Al, Sn, B, Ga, Cr, Sr, V, and Ti, 0 < x < 1, 0 < y < 1, 0 < z < 1, and x + y + z ≤ 1. The binder includes PVDF, and the conductive agent includes at least one of conductive carbon black, conductive graphite, carbon fiber, carbon nanotube, and graphene.

3. The method for leaching metal from a nickel-cobalt-manganese-lithium oxide positive electrode sheet according to claim 1, characterized in that: The pretreatment includes crushing the nickel-cobalt-manganese-lithium oxide positive electrode sheet disassembled from the waste battery to obtain a powder with a particle size of 70-90 μm, and then screening using a 100-300 mesh sieve coupled with a vibrating agitator to obtain the positive electrode powder.

4. The method for leaching metal from a nickel-cobalt-manganese-lithium oxide positive electrode sheet according to claim 1, characterized in that: The preparation method of the gluconic acid extractant comprises the following steps: culturing Gluconobacter oxidans in a glucose modified culture medium at 20-40° C. and 100-200 rpm on a shaking table for 30-60 hours, filtering to obtain a filtrate, and then diluting the filtrate.

5. The method for leaching metal from a nickel-cobalt-manganese-lithium oxide positive electrode sheet according to claim 1, characterized in that: The concentration of gluconic acid in the gluconic acid leaching agent is 75-300 mmol / L.

6. The method for leaching metal from a nickel-cobalt-manganese-lithium oxide positive electrode sheet according to claim 1, characterized in that: The cathode chamber and the anode chamber of the double-chamber electrochemical electrolytic cell are separated by a proton exchange membrane or an ion exchange membrane, an iridium oxide coated titanium mesh is inserted into the cathode chamber as a cathode, and stainless steel is inserted into the anode chamber as an anode.

7. The method for leaching metal from a nickel-cobalt-manganese-lithium oxide positive electrode sheet according to claim 1, characterized in that: The concentration of the ferrous sulfate aqueous solution is 0.5-0.8 mol / L, and the molar ratio of iron in the ferrous sulfate aqueous solution to cobalt in the positive electrode powder in the cathode chamber is 1:6-8.

8. The method for leaching metal from a nickel-cobalt-manganese-lithium oxide positive electrode sheet according to claim 1, characterized in that: The inorganic alkali aqueous solution is a 0.8-1.2 mol / L potassium hydroxide aqueous solution.

9. The method for leaching metal from a nickel-cobalt-manganese-lithium oxide positive electrode sheet according to claim 1, characterized in that: An immersion stirrer is provided in the cathode chamber, and the stirring speed is 500-700 r / min.

10. A method for recovering metals from a nickel-cobalt-manganese-lithium oxide positive electrode sheet, characterized in that: include: (I) The method for leaching metal from a nickel-cobalt-manganese-based lithium positive electrode sheet according to any one of claims 1 to 9 to obtain a Li-containing + 、Ni 2+ 、Co 2+ and Mn 2+ of the leachate; (II) Post-treatment of the leachate to recover Li + 、Ni 2+ 、Co 2+ and Mn 2+ , the post-treatment includes at least one operation of precipitation, adsorption and extraction.

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