A leaching method of waste lithium ion battery powder

Abstract

The application discloses a kind of waste lithium ion battery powder leaching methods, it is related to battery recycling technical field.Adopting ferrous sulfate as leaching agent can leach the main metal and impurity except copper in battery powder under mild conditions;Utilize nickel-cobalt slag to reduce ferric iron, while improving the main metal concentration in feed liquid without introducing new impurities;Aluminum is removed by bicarbonate to obtain aluminum slag, there is still a small amount of ferric ion in the process of removing aluminum, under the synergistic effect of a small amount of ferric ion, the aluminum slag obtained in the aluminum removal process is regular round, the aluminum content in the slag is high, the slag amount is small, the solid-liquid separation speed is fast, and the metal loss rate is low;After positive electrode powder is oxidized by ferrous ion, iron is removed to obtain purified liquid.The process of the application is simple, low in cost and highly practical, and can efficiently leach valuable metals under mild leaching conditions, and the leaching agent can be recycled.

Description

Technical Field

[0001] This invention relates to the field of battery recycling technology, and more specifically, to a leaching method for waste lithium-ion battery powder. Background Technology

[0002] In recent years, with the rapid development of my country's new energy vehicle industry, the demand for power batteries has surged, and at the same time, the volume of retired power batteries has also increased rapidly. Retired power batteries contain recyclable valuable metal resources such as nickel, cobalt, manganese, and lithium, as well as toxic and hazardous substances such as lithium hexafluorophosphate and dimethoxyethane, posing potential threats to the environment and human health, and thus requiring effective recycling and disposal. Driven by factors such as mineral resource shortages, rising upstream raw material prices, and a surge in retired power batteries, the recycling and reuse of power batteries has become a focus of research and development.

[0003] The general process of lithium-ion battery recycling consists of four steps: discharge, dismantling, active material separation, and valuable metal recovery and separation. The first three steps constitute the pretreatment stage, while the fourth step is the core processing stage. Currently, industrially, the H2SO4-H2O2 system is mainly used for low-acid and high-acid leaching to leach metals such as nickel, cobalt, and manganese from the raw materials. Chemical impurity removal is then performed, using iron powder to remove copper and chemical precipitation to remove iron and aluminum simultaneously. Current recycling processes mainly suffer from the following problems:

[0004] (1) High acid leaching is highly corrosive to equipment;

[0005] (2) Removing iron and aluminum together results in a large amount of slag, poor solid-liquid separation, and a high metal loss rate. The resulting slag needs to be acid-washed to reduce the metal loss rate.

[0006] In view of this, the present invention is proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a leaching method for waste lithium-ion battery powder, which aims to leach valuable metals under mild conditions while reducing the metal loss rate of aluminum slag.

[0008] This invention is implemented as follows:

[0009] This invention provides a leaching method for waste lithium-ion battery powder, comprising:

[0010] Mild leaching: Ferrous sulfate is used as a leaching agent to leach waste lithium-ion battery powder to obtain leachate and leaching residue;

[0011] Reduced ferric iron: The leaching solution is mixed with nickel-cobalt slag and reacted to obtain a reduced solution. The amount of nickel-cobalt slag is controlled to be 0.9 to 0.98 times the theoretical amount.

[0012] Aluminum removal: The reduced solution is mixed with bicarbonate and reacted to obtain a solution after aluminum removal and aluminum slag;

[0013] Ferrous oxide ions: The solution after aluminum removal is mixed with the positive electrode powder and reacted to obtain ferrous oxide solution and oxide residue;

[0014] Iron removal: The ferrous oxide solution is mixed with nickel cobalt manganese carbonate to react and obtain a purified solution and iron slag.

[0015] In an optional implementation, the mild leaching process controls the reaction pH to be 0.5-1.5, the reaction time to be 0.5h-2h, and the amount of waste lithium-ion battery powder used to be 0.8-1.0 times the theoretical amount.

[0016] Preferably, the mild leaching process includes: heating the leaching agent base solution with a ferrous ion concentration of 20 g / L-120 g / L to 20°C-80°C, adjusting the pH value to 0.5-1.5 with sulfuric acid, and then mixing and reacting the leaching agent base solution with waste lithium-ion battery powder.

[0017] In an optional embodiment, the waste lithium-ion battery powder is first pretreated and then gently leached. The pretreatment involves mixing the waste lithium-ion battery powder with kerosene for 1-5 hours and then performing solid-liquid separation to obtain the pretreated battery powder.

[0018] Preferably, the amount of kerosene used is controlled so that the liquid-to-solid ratio is 1:3-5.

[0019] In an optional embodiment, the process of reducing ferric iron includes: reacting nickel-cobalt slag with leaching solution at 40℃-85℃ for 1-2 hours, controlling the pH value of the system to be 0.5-1.5 during the reaction, and separating the solid and liquid after the reaction to obtain the reduced solution.

[0020] In an optional embodiment, during the aluminum removal process, the reaction temperature is controlled at 60℃-90℃, the system pH value is 3.8-4.1, and the reaction time is 30min-120min;

[0021] Preferably, the aluminum removal process includes: heating the reduced liquid to the reaction temperature, mixing it with a 10%-20% (by mass) bicarbonate solution, and then separating the solid and liquid after the reaction to obtain the aluminum-removed liquid and aluminum slag.

[0022] More preferably, the aluminum slag is washed with water and then discharged.

[0023] In an optional embodiment, during the oxidation of ferrous ions, the amount of positive electrode powder is controlled to be 1.1 to 1.5 times the theoretical molar amount of ferrous ions, the reaction temperature is 40°C to 80°C, the reaction time is 1 to 2 hours, and the reaction pH is 0.5 to 1.5. After the reaction is completed, solid and liquid separation is performed to obtain ferrous oxide residue and oxide slag, and the oxide slag is returned to the mild leaching process.

[0024] In an optional embodiment, during the iron removal process, the reaction temperature is controlled at 80℃-90℃, the system pH value is 5.4-6.3, and the reaction time is 30min-120min;

[0025] Preferably, after heating the ferrous oxide solution to the reaction temperature, it is mixed with nickel cobalt manganese carbonate and alkali, and the pH value is adjusted to 5.4-6.3. After the reaction is completed, solid-liquid separation is performed to obtain purified liquid and iron slag.

[0026] In an optional implementation, it further includes:

[0027] Acid-dissolving iron slag: Iron slag is dissolved using sulfuric acid to obtain ferric sulfate solution;

[0028] Mild copper leaching: Ferric sulfate solution is mixed with the leaching residue obtained in the mild leaching stage to produce graphite and copper-leached solution;

[0029] Copper removal by displacement: The nickel-cobalt slag is mixed with the copper leaching solution and reacted to obtain a copper and ferrous sulfate solution;

[0030] Preferably, the nickel-cobalt slag is added according to the theoretical molar amount of copper ions, the reaction temperature is controlled at 40℃-60℃, the reaction time is 1h-2h, and after the reaction is completed, solid-liquid separation is performed to obtain sponge copper and ferrous sulfate solution. The ferrous sulfate solution is used to prepare the leaching agent base solution for the mild leaching stage.

[0031] In an optional embodiment, the process of acid dissolving iron slag includes: mixing the obtained iron slag with water to make a slurry, controlling the liquid-solid ratio to 1:1-3, heating to 40℃-85℃, and then mixing with sulfuric acid to a pH value of 0.5-1.5.

[0032] In an optional embodiment, during the mild copper immersion process, sulfuric acid is added to control the pH value to 1.0-2.0, the reaction temperature is controlled at 40℃-85℃, and the reaction time is 1h-2h. After the reaction is completed, solid-liquid separation is performed to obtain graphite and copper immersion liquid.

[0033] This invention offers the following advantages: using ferrous sulfate as a leaching agent allows for the leaching of main metals (excluding copper) and impurities from battery powder under mild conditions; the reduction of ferric iron using nickel-cobalt slag (residue from the hydrogen reduction of cathode powder for lithium extraction) increases the concentration of main metals in the leaching solution without introducing new impurities; aluminum slag is obtained by removing aluminum with bicarbonate, and a small amount of ferric ions remains during the aluminum removal process. With the synergistic effect of this small amount of ferric ions, the aluminum slag obtained from the aluminum removal process is in the form of regular discs, with a high aluminum content, small slag volume, fast solid-liquid separation, and low metal loss rate; the cathode powder is then oxidized to remove ferrous ions, resulting in a purified solution. The process of this invention is simple, low-cost, and highly practical, efficiently leaching valuable metals under mild leaching conditions, and the leaching agent can be recycled. Attached Figure Description

[0034] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0035] Figure 1 For process flow diagram;

[0036] Figure 2 Here is a SEM image of the aluminum dross obtained in Example 1;

[0037] Figure 3 The image shows the XRD pattern of the aluminum dross obtained in Example 1.

[0038] Figure 4 The XRD pattern of the aluminum dross obtained in Comparative Example 1 is shown.

[0039] Figure 5 SEM image of the aluminum dross obtained in Comparative Example 1;

[0040] Figure 6 The image shows the SEM image of the aluminum slag obtained in Comparative Example 2. Detailed Implementation

[0041] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0042] This invention provides a leaching method for waste lithium-ion battery powder. Please refer to [link / reference]. Figure 1 ,include:

[0043] S1, Preprocessing

[0044] Waste lithium-ion battery powder undergoes pretreatment followed by gentle leaching. Pretreatment involves mixing the waste lithium-ion battery powder with kerosene for 1-5 hours, followed by solid-liquid separation to obtain pretreated battery powder. This pretreated powder is then used in the subsequent gentle leaching process. By using inexpensive kerosene to pretreat the waste lithium-ion battery powder, the graphite in the powder is coated. The two-step gentle leaching process then removes all the main metals and impurities, resulting in graphite that has not been damaged by acid leaching.

[0045] Specifically, waste lithium-ion battery powder includes both positive and negative electrode materials, and is the battery powder before leaching. Waste lithium-ion battery powder and kerosene can be mixed at room temperature for 1 hour, 3 hours, 5 hours, etc.

[0046] In some embodiments, the amount of kerosene used is controlled by a liquid-to-solid ratio of 1:3-5, where the liquid-to-solid ratio is a mass ratio, such as 1:3, 1:4, 1:5, etc.

[0047] In actual operation, waste lithium-ion battery powder and kerosene are mixed and stirred at room temperature for 1-3 hours to allow the kerosene to be adsorbed onto the graphite surface. After filtration, pretreated battery powder is obtained.

[0048] S2, gentle leaching

[0049] Ferrous sulfate was used as a leaching agent to leach waste lithium-ion battery powder to obtain leachate and leaching residue. The leaching was carried out with ferrous sulfate, and the ferrous ions were leached to generate trivalent iron ions, which efficiently and gently leach out the main metals and impurities in the battery powder except copper.

[0050] In some embodiments, the mild leaching process controls the reaction pH to be 0.5-1.5, the reaction time to be 0.5-2 hours, and the amount of waste lithium-ion battery powder used to be 0.8-1.0 times the theoretical amount. By controlling the reaction conditions, the valuable metals in the waste lithium-ion battery powder are leached more fully, thereby increasing the leaching rate. Specifically, the reaction pH can be 0.5, 0.8, 1.0, 1.2, 1.5, etc., the reaction time can be 0.5 hours, 0.8 hours, 1.0 hours, 1.2 hours, 1.5 hours, 1.7 hours, 2.0 hours, etc., and the amount of waste lithium-ion battery powder used is controlled to be 0.8 times, 0.9 times, or 1.0 times the theoretical amount, respectively.

[0051] In actual operation, the mild leaching process includes: heating the leaching agent base solution with a ferrous ion concentration of 20g / L-120g / L to 20℃-80℃, adjusting the pH value to 0.5-1.5 with sulfuric acid, slowly adding the pretreated battery powder, and simultaneously adding sulfuric acid to control the pH value within the range of 0.5-1.5. The pH value must be maintained within the range of 0.5-1.5 throughout the entire leaching process. After the battery powder is added and the reaction is completed, continue stirring for 0.5h-2h, and then filter to obtain the leachate and leach residue.

[0052] Specifically, based on the ferrous ion concentration, the concentration of the leaching agent base solution can be 20 g / L, 50 g / L, 80 g / L, 100 g / L, 120 g / L, etc., and the reaction temperature can be 20℃, 40℃, 60℃, 80℃, etc.

[0053] S3, Reduced ferric iron

[0054] The leaching solution is mixed with nickel-cobalt slag to obtain a reduced solution. The amount of nickel-cobalt slag is controlled to be 0.9 to 0.98 times the theoretical amount. The nickel-cobalt slag (residue from the hydrogen reduction of cathode powder for lithium extraction) is used to reduce ferric iron without introducing new impurities, while simultaneously increasing the concentration of the main metal in the solution. The amount of nickel-cobalt slag used is slightly less than the theoretical amount, reserving a small amount of ferric iron. This is because, with the synergistic effect of a small amount of ferric iron, the aluminum slag obtained in the subsequent aluminum removal process forms better, resulting in higher liquid-solid separation efficiency and lower metal loss rate.

[0055] In an optional embodiment, the process of reducing ferric iron includes: reacting nickel-cobalt slag with leaching solution at 40℃-85℃ for 1-2 hours, controlling the pH value of the system to be 0.5-1.5 during the reaction, and separating the solid and liquid after the reaction to obtain the reduced solution.

[0056] Specifically, the reaction temperature between nickel-cobalt slag and leaching solution can be 40℃, 50℃, 60℃, 70℃, 80℃, 85℃, etc.; the reaction time can be 1h, 1.5h, 2.0h, etc.; and the pH value of the reaction process control system can be 0.5, 0.8, 1.0, 1.2, 1.5, etc.

[0057] S4, aluminum removal

[0058] The reduced solution is mixed with bicarbonate to produce a dealuminized solution and aluminum slag. Aluminum slag is obtained by using bicarbonate for dealuminization. By controlling the process conditions, the resulting aluminum slag is in the form of regular discs, with a small volume, fast solid-liquid separation, and low metal loss. The obtained aluminum slag has a high aluminum content and a low metal content, which can be achieved by washing with water.

[0059] In some embodiments, during the aluminum removal process, the reaction temperature is controlled at 60℃-90℃, the system pH value is 3.8-4.1, and the reaction time is 30min-120min. By optimizing the aluminum removal process parameters, aluminum is fully removed, and the resulting filter residue is washed with water and discharged as slag.

[0060] Specifically, the reaction temperature can be 60℃, 70℃, 80℃, 90℃, etc., the pH value of the system can be 3.8, 3.9, 4.0, 4.1, etc., and the reaction time can be 30min, 50min, 70min, 100min, 120min, etc.

[0061] In practice, the aluminum removal process includes: heating the reduced liquid to the reaction temperature, mixing it with a 10%-20% (w / w) bicarbonate solution, and then separating the solid and liquid phases after the reaction to obtain the aluminum-removed liquid and aluminum slag. Using a 10%-20% (w / w) bicarbonate solution for the reaction helps to obtain a more uniform aluminum slag. Specifically, the mass fraction of the bicarbonate solution can be 10%, 15%, 20%, etc. The bicarbonate solution is added slowly, and after the addition is complete, the reaction is continued with stirring for 30-120 minutes.

[0062] S5, ferrous oxide ions

[0063] The aluminum-removed liquid is mixed with the cathode powder and reacted to obtain ferrous oxide liquid and oxide slag. The main component of the cathode powder is nickel-cobalt-manganese oxide. The nickel-cobalt-manganese oxide reacts with the ferrous oxide to oxidize the ferrous ions into ferric ions, which facilitates subsequent iron removal.

[0064] In some embodiments, during the oxidation of ferrous ions, the amount of positive electrode powder is controlled to be 1.1 to 1.5 times the theoretical molar amount of ferrous ions, the reaction temperature is 40°C to 80°C, and the reaction time is 1 to 2 hours. Sulfuric acid is added throughout the oxidation process to control the pH value to 0.5 to 1.5. After the reaction is complete, solid-liquid separation yields ferrous oxide residue and oxidation slag. The oxidation slag is returned to the mild leaching process. By controlling the reaction conditions, ferrous ions are fully reacted to generate ferric ions, thus ensuring the iron removal effect.

[0065] Specifically, the amount of positive electrode powder used is 1.1 times, 1.2 times, 1.3 times, 1.4 times, 1.5 times, etc. of the theoretical molar amount of divalent iron ions; the reaction temperature can be 40℃, 50℃, 60℃, 70℃, 80℃, etc.; the reaction time can be 1h, 1.5h, 2.0h, etc.; and the pH value controlled throughout the reaction process can be 0.5, 0.8, 1.0, 1.2, 1.5, etc.

[0066] S6, Iron removal

[0067] The ferrous oxide solution was mixed with nickel, cobalt and manganese carbonate to produce a purified solution and iron slag. The purified solution contained impurities and its main components were valuable metals such as nickel, cobalt, manganese and lithium.

[0068] In some embodiments, during the iron removal process, the reaction temperature is controlled at 80℃-90℃, the system pH value is 5.4-6.3, and the reaction time is 30min-120min. By controlling the iron removal process under relatively high temperature and weak acid conditions, ferric ions are fully removed.

[0069] Specifically, the reaction temperature can be 80℃, 85℃, 90℃, etc., the pH value of the system can be 5.4, 5.5, 5.6, 5.7, 5.8, 5.9, 6.0, 6.1, 6.2, 6.3, etc., and the reaction time can be 30min, 50min, 70min, 100min, 120min, etc.

[0070] In actual operation, the ferrous oxide solution is heated to the reaction temperature, then mixed with nickel cobalt manganese carbonate and alkali. The pH is adjusted to 5.4-6.3. After the additives are added, stirring continues for 30-120 minutes. After the reaction is complete, solid-liquid separation is performed to obtain purified liquid and iron slag. The alkali can be ordinary soda ash or liquid alkali, such as sodium hydroxide solution, etc., and its dosage is controlled to keep the pH within the above range. The solid-liquid separation method can be, but is not limited to, filtration.

[0071] S7, acid-soluble iron slag

[0072] Iron slag is dissolved in sulfuric acid to obtain ferric sulfate solution, which is then used in the subsequent gentle copper leaching process.

[0073] In some embodiments, the acid dissolution process of iron slag includes: mixing the obtained iron slag with water to form a slurry, controlling the liquid-to-solid ratio at 1:1-3, heating to 40℃-85℃, and then mixing with sulfuric acid until the pH value is 0.5-1.5, so that the iron slag is completely dissolved. Specifically, the amount of water used is controlled to have a liquid-to-solid ratio of 1:1, 1:2, 1:3, etc., the acid dissolution temperature can be 40℃, 50℃, 60℃, 70℃, 80℃, 85℃, etc., the pH value can be controlled to be 0.5, 0.8, 1.0, 1.2, 1.5, etc., and the reaction time is controlled to ensure that the iron slag is completely dissolved.

[0074] S8, Mild copper immersion

[0075] Ferric sulfate solution is mixed with the leaching residue obtained from the mild leaching stage to produce graphite and a copper-leached solution. The leaching residue contains graphite and copper. The copper can be leached using ferric sulfate solution. Through two steps of mild leaching, all the main metals and impurities are leached out, resulting in graphite that has not been damaged by acid leaching. Using an acid-dissolving iron slag solution to leach copper effectively avoids the strong corrosiveness of strong acids on the leaching equipment, saves on auxiliary material costs, and reduces production costs. Under the two-step mild leaching conditions, the recovery rates of nickel, cobalt, manganese, and lithium are all greater than 98%.

[0076] In some embodiments, during the mild copper immersion process, sulfuric acid is added to control the pH value to 1.0-2.0, the reaction temperature is controlled at 40℃-85℃, and the reaction time is 1h-2h. After the reaction is completed, solid-liquid separation is performed to obtain graphite and copper-immersed liquid. The solid-liquid separation method can be, but is not limited to, filtration.

[0077] Specifically, the pH value can be controlled at 1.0, 1.5, 2.0, etc., the reaction temperature can be 40℃, 50℃, 60℃, 70℃, 80℃, 85℃, etc., and the reaction time can be 1h, 1.5h, 2.0h, etc.

[0078] S9, Copper Removal by Replacement

[0079] The nickel-cobalt slag is mixed with the copper leaching solution to obtain a copper and ferrous sulfate solution. The copper is removed by replacing it with the nickel-cobalt slag. Without introducing new impurities, the concentration of the main metal in the solution is greatly increased, the amount of wastewater is reduced, and the production capacity is increased.

[0080] In some embodiments, nickel-cobalt slag is added according to the theoretical molar amount of copper ions, the reaction temperature is controlled at 40℃-60℃, the reaction time is 1h-2h, and after the reaction is completed, solid-liquid separation is performed to obtain sponge copper and ferrous sulfate solution. The ferrous sulfate solution is used to prepare the leaching agent base solution in the mild leaching stage, so that the raw materials can be recycled.

[0081] Specifically, the reaction temperature can be 40℃, 50℃, 60℃, etc., and the reaction time can be 1h, 1.5h, 2.0h, etc.

[0082] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0083] It should be noted that the composition of the waste lithium cobalt oxide battery powder processed in the following embodiments is shown in Table 1, the composition of the waste ternary battery powder processed is shown in Table 2, the composition of the nickel-cobalt slag used in the process is shown in Table 3, and the composition of the cathode powder is shown in Table 4.

[0084] Table 1. Composition of waste lithium cobalt oxide battery powder

[0085] composition Co Ni Mn Cu Fe Al Li content 21.04％ 5.94％ 3.35％ 8.51％ 0.64％ 12.14％ 3.16％

[0086] Table 2 Composition of waste ternary lithium battery powder

[0087] composition Co Ni Mn Cu Fe Al Li content 3.66％ 24.66％ 5.92％ 1.6％ 0.19％ 1.48％ 3.90％

[0088] Table 3 Composition of nickel-cobalt slag

[0089] composition Co Ni Mn Cu Fe Al Li content 8.95％ 34.52％ 12.92％ 0.01％ 0.02％ 0.04％ 0.43％

[0090] Table 4. Composition of the positive electrode powder

[0091]

[0092]

[0093] Example 1

[0094] This embodiment provides a leaching method for waste lithium-ion battery powder, including the following steps:

[0095] (1) Pretreatment: Waste lithium cobalt oxide battery powder is mixed with kerosene, the liquid-solid ratio is controlled at 1:3, and stirred at room temperature for 3 hours to allow the kerosene to be adsorbed on the graphite surface. The pretreated battery powder is obtained by filtration.

[0096] (2) Mild leaching: Prepare 80g / L (Fe 2+ The leaching agent base solution (concentration) was prepared at a controlled temperature of 60℃. First, the pH of the leaching agent solution was adjusted to 1.0 with sulfuric acid. Then, 0.8 times the theoretical amount of pretreated lithium cobalt oxide battery powder was slowly added. Simultaneously, sulfuric acid was added to maintain the pH between 0.5 and 1.0. Throughout the leaching reaction, the pH must be maintained between 0.5 and 1.0. After the battery powder was added, the reaction was continued with stirring for 1 hour. The solution was then filtered to obtain the leaching liquid and leaching residue.

[0097] (3) Reduction of ferric iron: Add nickel-cobalt slag with a theoretical molar amount of ferric ions of 0.98 times to the leaching solution and stir at 40°C for 2 hours. During the entire reduction process, sulfuric acid needs to be added to ensure that the solution pH is 0.5-1.0 to obtain the reduced ferric iron solution.

[0098] (4) Aluminum removal: After reducing ferric iron, heat the liquid to 60°C, add 10% sodium bicarbonate solution, control the addition rate, stir the reaction and adjust the pH of the solution to 3.8. After the auxiliary materials are added, continue stirring the reaction for 120 minutes, filter to obtain aluminum removal liquid and aluminum slag, and wash and dry the aluminum slag.

[0099] The metal ion content in the aluminum slag was tested and found to be as follows: Ni: 0.52%, Co: 0.14%, Mn: 0.05%, Al: 26.56%, Fe: 0.9%, Na: 0.19%, S: 6.91%.

[0100] (5) Ferrous oxide: Add 1.1 times the theoretical molar amount of ferrous ions of the positive electrode powder to the aluminum removal solution, stir and react at 40°C for 1 hour. During the entire oxidation process, sulfuric acid needs to be added to control the pH within the range of 1.0-1.5. After filtration, ferrous oxide solution and oxide residue are obtained. Oxidation residue is then returned to the leaching process.

[0101] (6) Iron removal: Heat the ferrous oxide solution to 80°C, add 15% soda ash solution to adjust the pH to 5.4, and after the auxiliary materials are added, continue stirring for 30 minutes. Filter to obtain iron slag and purified liquid.

[0102] The test results showed that the purified solution contained Al: 0.6 mg / L, Fe: 1.9 mg / L, and Cu: 0.9 mg / L.

[0103] (7) Acid dissolution of iron slag: Pulp the iron slag at a liquid-to-solid ratio of 1:3 and stir, control the temperature at 40℃, add sulfuric acid to adjust the pH to 0.5, so that the iron slag is completely dissolved.

[0104] (8) Mild copper leaching: Add the leaching residue obtained in step (2) to the ferric sulfate solution obtained in step (7), add sulfuric acid to control the pH to 1.0-2.0, stir and react at 40℃ for 2 hours, and filter to obtain graphite and copper leaching solution.

[0105] The total recovery rates of the main metals were tested to be 99.05% for Ni, 98.37% for Co, 98.21% for Mn, and 99.62% for Li.

[0106] (9) Displacement to remove copper: Add the theoretical molar amount of nickel-cobalt slag with copper ions to the copper leaching solution, stir and react at 60°C for 1 hour, filter to obtain sponge copper and ferrous sulfate solution, and reuse the ferrous sulfate solution as the leaching agent base solution in the mild leaching process.

[0107] Example 2

[0108] This embodiment provides a leaching method for waste lithium-ion battery powder, including the following steps:

[0109] (1) Pretreatment: Waste ternary battery powder is mixed with kerosene, the liquid-solid ratio is controlled at 1:4, and stirred at room temperature for 3 hours to allow the kerosene to be adsorbed on the graphite surface. The pretreated ternary battery powder is obtained by filtration.

[0110] (2) Mild leaching: Prepare 20g / L (Fe 2+ The leaching agent base solution (concentration) is prepared at a controlled temperature of 80℃. First, the pH of the leaching agent solution is adjusted to 1.5 with sulfuric acid. Then, 1.0 times the theoretical amount of ternary lithium battery powder is slowly added, with sulfuric acid added simultaneously to maintain the pH between 1.0 and 1.5. Throughout the leaching reaction, the pH must be maintained between 0.5 and 1.5. After the battery powder is added, the reaction is continued with stirring for 1.5 hours. The solution is then filtered to obtain the leachate and leaching residue.

[0111] (3) Reduction of ferric iron: Add nickel-cobalt slag with a theoretical molar amount of ferric ions of 0.95 times to the leaching solution and stir at 60°C for 1 hour. During the entire reduction process, sulfuric acid needs to be added to ensure that the solution pH is ≤1.5 to obtain the reduced ferric iron solution.

[0112] (4) Aluminum removal: After reducing ferric iron, heat the liquid to 80°C, add 15% sodium bicarbonate solution, control the addition rate, stir the reaction and adjust the pH of the solution to 4.1. After the auxiliary materials are added, continue stirring the reaction for 60 minutes, filter to obtain aluminum removal liquid and aluminum slag, wash the aluminum slag with water and dry it.

[0113] The metal ion content in the aluminum slag was tested and found to be as follows: Ni: 0.57%, Co: 0.15%, Mn: 0.08%, Al: 27.12%, Fe: 0.7%, Na: 0.17%, S: 6.47%.

[0114] (5) Ferrous oxide: Add 1.3 times the theoretical molar amount of ferrous ions of the positive electrode powder to the aluminum removal liquid, stir and react at 60°C for 1 hour. During the entire oxidation process, sulfuric acid needs to be added to control the pH in the range of 1.0-1.5. After filtration, ferrous oxide liquid and oxide residue are obtained. The oxide residue is then returned to the leaching process.

[0115] (6) Iron removal: Heat the ferrous oxide solution to 80°C, add sodium hydroxide solution to adjust the pH to 5.8, and after the auxiliary materials are added, continue stirring for 60 minutes. Filter to obtain iron slag and purified liquid.

[0116] The test results showed that the purified solution contained Al: 0.5 mg / L, Fe: 1.3 mg / L, and Cu: 1.0 mg / L.

[0117] (7) Acid dissolution of iron slag: Pulp the iron slag at a liquid-solid ratio of 1:1 and stir, control the temperature at 60℃, add sulfuric acid to adjust the pH to 1.5, so that the iron slag is completely dissolved.

[0118] (8) Mild copper leaching: Add the leaching residue obtained in step (2) to the ferric sulfate solution obtained in step (7), add sulfuric acid to control the pH to 1.0-2.0, stir and react at 60℃ for 1 hour, and filter to obtain graphite and copper leaching solution.

[0119] The total recovery rates of the main metals were tested to be 99.19% for Ni, 98.16% for Co, 98.31% for Mn, and 99.59% for Li.

[0120] (9) Displacement to remove copper: Add the theoretical molar amount of nickel-cobalt slag with copper ions to the copper leaching solution, stir and react at 60°C for 1 hour, filter to obtain sponge copper and ferrous sulfate solution, and reuse the ferrous sulfate solution as the leaching agent base solution in the mild leaching process.

[0121] Example 3

[0122] This embodiment provides a leaching method for waste lithium-ion battery powder, including the following steps:

[0123] (1) Pretreatment: Waste lithium cobalt oxide battery powder is mixed with kerosene, the liquid-solid ratio is controlled at 1:5, and stirred at room temperature for 1 hour to allow the kerosene to be adsorbed on the graphite surface. The pretreated ternary battery powder is obtained by filtration.

[0124] (2) Mild leaching: Prepare 100g / L (Fe) 2+The leaching agent base solution (concentration) is prepared at a controlled temperature of 40℃. First, the pH of the leaching agent solution is adjusted to 0.5 with sulfuric acid. Then, 0.9 times the theoretical amount of pretreated lithium cobalt oxide battery powder is slowly added, while simultaneously adding sulfuric acid to maintain the pH between 0.5 and 1.0. Throughout the leaching reaction, the pH must be maintained between 0.5 and 1.0. After the battery powder is added, the reaction is continued with stirring for 1.5 hours. The solution is then filtered to obtain the leaching liquid and leaching residue.

[0125] (3) Reduction of ferric iron: Add nickel-cobalt slag with a theoretical molar amount of ferric ions of 0.98 times to the leaching solution and stir at 40°C for 2 hours. The solution pH must be ≤1.0 throughout the reduction process to obtain the reduced ferric iron solution.

[0126] (4) Aluminum removal: After reducing ferric iron, heat the liquid to 90°C, add 10% sodium bicarbonate solution, control the addition rate, stir the reaction and adjust the pH of the solution to 3.8. After the auxiliary materials are added, continue stirring the reaction for 90 minutes, filter to obtain aluminum removal liquid and aluminum slag, wash the aluminum slag with water and dry it.

[0127] The metal ion content in the aluminum slag was tested and found to be as follows: Ni: 0.53%, Co: 0.24%, Mn: 0.08%, Al: 26.37%, Fe: 1.09%, Na: 0.17%, S: 6.79%.

[0128] (5) Ferrous oxide: Add 1.5 times the theoretical molar amount of ferrous ions of the positive electrode powder to the aluminum removal liquid, stir and react at 40℃ for 2 hours. During the entire oxidation process, sulfuric acid needs to be added to control the pH in the range of 0.5-1.0. After filtration, ferrous oxide liquid and oxide residue are obtained. Oxidation residue is then returned to the leaching process.

[0129] (6) Iron removal: Heat the ferrous oxide solution to 80°C, add 15% soda ash solution to adjust the pH to 6.3, after the auxiliary materials are added, continue stirring for 30 minutes, and filter to obtain iron slag and purified liquid.

[0130] The test results showed that the purified solution contained Al: 0.6 mg / L, Fe: 1.9 mg / L, and Cu: 0.5 mg / L.

[0131] (7) Acid dissolution of iron slag: Pulp the iron slag at a liquid-to-solid ratio of 1:2 and stir, control the temperature at 80℃, add sulfuric acid to adjust the pH to 1.0, so that the iron slag is completely dissolved.

[0132] (8) Mild copper leaching: Add the leaching residue obtained in step (2) to the ferric sulfate solution obtained in step (7), add sulfuric acid to control the pH to 1.0-2.0, stir and react at 85℃ for 1 hour, and filter to obtain graphite and copper leaching solution.

[0133] The total recovery rates of the main metals were as follows: Ni: 99.37%, Co: 98.69%, Mn: 98.81%, and Li: 99.71%.

[0134] (9) Displacement to remove copper: Add the theoretical molar amount of nickel-cobalt slag with copper ions to the copper leaching solution, stir and react at 50°C for 1 hour, filter to obtain sponge copper and ferrous sulfate solution, and reuse the ferrous sulfate solution as the leaching agent base solution in the mild leaching process.

[0135] Comparative Example 1

[0136] This comparative example provides a leaching method for waste lithium-ion battery powder, including the following steps:

[0137] (1) Low acid leaching: Weigh 600 kg of waste ternary lithium-ion battery powder, mix it in a 2:1 ratio, set the water bath temperature to 90℃, start stirring, slowly add concentrated sulfuric acid to adjust the pH to 0.5, continue stirring for 30 min, then slowly add hydrogen peroxide to adjust the pH to 2.0, continue stirring for 1 h, and then filter to obtain low acid leaching residue and low acid leaching solution.

[0138] (2) High-acid leaching: The low-acid leaching residue obtained in step (1) was mixed with water at a ratio of 3:1 to form a slurry. The water bath temperature was set to 90℃, and stirring was started. Approximately 300 g / L of concentrated sulfuric acid was slowly added. After stirring for 1 hour, 100 g / L of sodium thiosulfate was added. The high-acid leaching solution and high-acid residue were obtained by filtration. The total leaching rates of the main metals were Ni: 99.74%, Co: 97.89%, Mn: 98.91%, and Li: 99.32%.

[0139] (3) First copper removal: The low acid leaching solution obtained in step (1) is heated to 50°C, the theoretical amount of iron powder is added, and after stirring for 60 minutes, it is filtered to obtain the first copper removal solution and sponge copper.

[0140] (4) Aluminum removal: Prepare a 15% sodium carbonate solution, adjust the pH of the copper-removed solution to 3.8-4.1 at 90℃, continue stirring for 1 hour, and filter to obtain the aluminum-removed solution and aluminum slag. The aluminum slag is washed with water and dried.

[0141] The metal ion content in the aluminum slag was tested and found to be as follows: Ni: 2.66%, Co: 0.52%, Mn: 0.17%, Al: 17.53%, Fe: 1.07%, Na: 4.06%, S: 10.14%.

[0142] (5) Iron removal: Divalent iron is oxidized to trivalent iron using hydrogen peroxide or manganese dioxide, and iron is removed by goethite method. After the iron slag is washed and dried, the following components are detected in the slag: Ni: 2.71%, Co: 0.49%, Mn: 0.11%, Fe: 35.97%.

[0143] (6) Deep copper and aluminum removal: The iron-removed liquid is heated to 80°C, and the pH is adjusted to 5.1-5.4 with soda ash to remove aluminum to below 1 mg / L. Then, sodium sulfide with a copper ion concentration of 10 times is added for deep copper removal. The reaction is carried out for 60 min, and the purified liquid is obtained by filtration. The filter residue is reused in the leaching process.

[0144] Comparative Example 2

[0145] This comparative example provides a leaching method for waste lithium-ion battery powder, including the following steps:

[0146] (1) Pretreatment: Waste lithium cobalt oxide battery powder is mixed with kerosene, the liquid-solid ratio is controlled at 1:3, and stirred at room temperature for 3 hours to allow the kerosene to be adsorbed on the graphite surface. The pretreated battery powder is obtained by filtration.

[0147] (2) Mild leaching: Prepare 80g / L (Fe 2+ The leaching agent base solution (concentration) was prepared at a controlled temperature of 60℃. First, the pH of the leaching agent solution was adjusted to 1.0 with sulfuric acid. Then, 0.8 times the theoretical amount of pretreated lithium cobalt oxide battery powder was slowly added. Simultaneously, sulfuric acid was added to maintain the pH between 0.5 and 1.0. Throughout the leaching reaction, the pH must be maintained between 0.5 and 1.0. After the battery powder was added, the reaction was continued with stirring for 1 hour. The solution was then filtered to obtain the leaching liquid and leaching residue.

[0148] (3) Reduction of ferric iron: Add the theoretical molar amount of nickel-cobalt slag with ferric ions to the leaching solution and stir the reaction at 40°C for 2 hours. During the entire reduction process, sulfuric acid needs to be added to ensure that the solution pH ≤ 1.0, and the ferric iron reduced solution is obtained.

[0149] (4) Aluminum removal: After reducing ferric iron, heat the liquid to 60°C, add 10% sodium bicarbonate solution, control the addition rate, stir the reaction and adjust the pH of the solution to 3.8. After the auxiliary materials are added, continue stirring the reaction for 120 minutes, filter to obtain aluminum removal liquid and aluminum slag, and wash and dry the aluminum slag.

[0150] The metal ion content in the aluminum slag was tested and found to be as follows: Ni: 1.63%, Co: 0.56%, Mn: 0.08%, Al: 26.54%, Fe: 0.08%, Na: 0.15%, S: 6.37%.

[0151] (5) Ferrous oxide: Add 1.1 times the theoretical molar amount of ferrous ions of the positive electrode powder to the aluminum removal solution, stir and react at 40°C for 1 hour. During the entire oxidation process, sulfuric acid needs to be added to control the pH within the range of 1.0-1.5. After filtration, ferrous oxide solution and oxide residue are obtained. Oxidation residue is then returned to the leaching process.

[0152] (6) Iron removal: Heat the ferrous oxide solution to 80°C, add 15% soda ash solution to adjust the pH to 5.4, and after the auxiliary materials are added, continue stirring for 30 minutes. Filter to obtain iron slag and purified liquid.

[0153] The test results showed that the purified solution contained Al: 0.5 mg / L, Fe: 1.7 mg / L, and Cu: 0.9 mg / L.

[0154] (7) Acid dissolution of iron slag: Pulp the iron slag at a liquid-to-solid ratio of 1:3 and stir, control the temperature at 40℃, add sulfuric acid to adjust the pH to 0.5, so that the iron slag is completely dissolved.

[0155] (8) Mild copper leaching: Add the leaching residue obtained in step (2) to the ferric sulfate solution obtained in step (7), add sulfuric acid to control the pH to 1.0-2.0, stir and react at 40℃ for 2 hours, and filter to obtain graphite and copper leaching solution.

[0156] The total recovery rates of the main metals were tested to be 99.19% for Ni, 98.34% for Co, 98.17% for Mn, and 99.64% for Li.

[0157] (9) Displacement to remove copper: Add the theoretical molar amount of nickel-cobalt slag with copper ions to the copper leaching solution, stir and react at 60°C for 1 hour, filter to obtain sponge copper and ferrous sulfate solution, and reuse the ferrous sulfate solution as the leaching agent base solution in the mild leaching process.

[0158] Note: The only difference between Comparative Example 2 and Example 1 is that in step (3), nickel-cobalt slag with a theoretical molar amount of ferric ions is added to the leaching solution.

[0159] Experimental Example 1

[0160] The dry basis elemental composition of aluminum slag in Examples 1-3 and the comparative example was analyzed, and the results are shown in Table 5:

[0161] Table 5. Dry-basis elemental composition of aluminum slag

[0162] element Ni Co Mn Al Fe Na S Example 1 0.52％ 0.14％ 0.05％ 26.56％ 0.91％ 0.19％ 6.91％ Example 2 0.57％ 0.15％ 0.08％ 27.12％ 0.74％ 0.17％ 6.47％ Example 3 0.53％ 0.24％ 0.08％ 26.37％ 1.09％ 0.17％ 6.79％ Comparative Example 1 2.66％ 0.52％ 0.17％ 17.53％ 1.07％ 4.06％ 10.14％ Comparative Example 2 1.63％ 0.56％ 0.08％ 26.54％ 0.08％ 0.15％ 6.37％

[0163] As shown in Table 5, the aluminum slag obtained using soda ash in Comparative Example 1 has higher contents of nickel, cobalt, manganese, sodium, and sulfur than the aluminum slag obtained using sodium bicarbonate, while the aluminum content is lower. This indicates that the aluminum slag obtained by using bicarbonate alone for aluminum removal has a smaller slag volume and a lower metal loss rate. Table 5 also shows that in Comparative Example 2, without the presence of ferric iron, the metal loss rate of the aluminum slag obtained during aluminum removal is higher than that of Examples 1-3, indicating that the aluminum slag obtained without ferric iron has poorer formation and higher metal entrainment.

[0164] Experimental Example 2

[0165] The XRD and SEM results of aluminum slag in Example 1 are as follows: Figure 2 , Figure 3 As shown; the XRD and SEM results of the aluminum slag in Comparative Example 1 are as follows. Figure 4 , Figure 5 As shown; the SEM detection results of aluminum slag in Comparative Example 2 are as follows. Figure 6 As shown.

[0166] Figure 2 This indicates that the aluminum slag obtained in the example is in the form of regular circular flakes.

[0167] Figure 3 This indicates that the obtained aluminum slag has good crystallinity and large grains.

[0168] Figure 4 This indicates that the aluminum slag obtained in Comparative Example 1 is sodium vanadium sulfite, hence the large amount of slag.

[0169] Figure 5 This indicates that the sodium aluminate slag obtained in Comparative Example 1 formed irregular agglomerates.

[0170] Figure 6 This indicates that when ferric iron is not involved in aluminum removal, the resulting aluminum slag is irregularly agglomerated into spherical shapes, leading to a higher metal content in the slag.

[0171] Experimental Example 3

[0172] The leaching rates of the main metals in the test examples and comparative examples are shown in Table 6.

[0173] Test method: Using aqua regia slag, the metal content was determined using a Thermo Fisher Scientific 7200 ICP analyzer. The metal leaching rate was calculated using the following formula:

[0174]

[0175] Where m1 is the mass of the initial raw material, in grams;

[0176] w1—Mass fraction of metal in the initial raw material, %;

[0177] m2 — Mass of leaching residue, in grams;

[0178] w2—Mass fraction of metal in the leaching residue, %;

[0179] Table 6. Test results of main metal leaching rate in the examples and comparative examples.

[0180] element Ni Co Mn Li Example 1 99.05％ 98.37％ 98.21％ 99.62％ Example 2 99.19％ 98.16％ 98.31％ 99.59％ Example 3 99.37％ 98.69％ 98.81％ 99.71％ Comparative Example 1 99.74％ 97.89％ 98.91％ 99.32％ Comparative Example 2 99.19％ 98.34％ 98.17％ 99.64％

[0181] As can be seen from Table 6, the leaching rate of the main metal obtained by two mild leaching processes is comparable to that obtained by conventional processes of first low acid leaching and then high acid leaching. Mild leaching can greatly reduce the amount of acid used, and the leaching agent can be recycled. Compared with conventional leaching processes, mild leaching processes can reduce auxiliary material costs, are friendly to leaching equipment, and avoid damage to graphite by strong acids.

[0182] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method of leaching of spent lithium ion battery powder, characterized by, include: Mild leaching: Ferrous sulfate is used as a leaching agent to leach waste lithium-ion battery powder to obtain leachate and leaching residue; the mild leaching process controls the reaction pH to be 0.5-1.5, the reaction time to be 0.5h-2h, and the amount of waste lithium-ion battery powder used to be 0.8-1.0 times the theoretical amount; the mild leaching process includes: heating the leaching agent bottom solution with a ferrous ion concentration of 20g / L-120g / L to 20℃-80℃, adjusting the pH to 0.5-1.5 with sulfuric acid, and then mixing the leaching agent bottom solution with the waste lithium-ion battery powder for reaction; Reduced ferric iron: The leaching solution is mixed and reacted with nickel-cobalt slag to obtain a reduced solution, wherein the amount of nickel-cobalt slag is controlled to be 0.9 to 0.98 times the theoretical amount; Aluminum removal: The reduced solution is mixed with bicarbonate and reacted to obtain a solution after aluminum removal and aluminum slag; Ferrous oxide ions: The aluminum-removed liquid is mixed with the positive electrode powder to obtain ferrous oxide liquid and oxide residue; Iron removal: The ferrous oxide solution is mixed with nickel cobalt manganese carbonate to react and obtain a purified solution and iron slag.

2. The leaching process according to claim 1, characterized in that, The waste lithium-ion battery powder is first pretreated and then subjected to gentle leaching. The pretreatment involves mixing the waste lithium-ion battery powder with kerosene for 1-5 hours and then performing solid-liquid separation to obtain the pretreated battery powder.

3. The leaching process according to claim 2, characterized in that, The amount of kerosene used is controlled so that the liquid-to-solid ratio is 1:3-5.

4. The leaching process according to claim 1, characterized in that, The process of reducing ferric iron includes: reacting the nickel-cobalt slag with the leaching solution at 40℃-85℃ for 1-2 hours, controlling the pH value of the system to be 0.5-1.5 during the reaction, and separating the solid and liquid to obtain the reduced solution after the reaction.

5. The leaching process according to claim 1, characterized in that, During the aluminum removal process, the reaction temperature is controlled at 60℃-90℃, the pH value of the system is 3.8-4.1, and the reaction time is 30min-120min.

6. The leaching process according to claim 5, characterized in that, The aluminum removal process includes: heating the reduced liquid to the reaction temperature, mixing it with a 10%-20% (by mass) bicarbonate solution, and then separating the solid and liquid to obtain the aluminum-removed liquid and aluminum slag after the reaction is completed.

7. The leaching process according to claim 6, characterized in that, The aluminum slag is washed with water and then discharged.

8. The leaching process according to claim 1, characterized in that, During the oxidation of ferrous ions, the amount of positive electrode powder is controlled to be 1.1 to 1.5 times the theoretical molar amount of ferrous ions, the reaction temperature is 40℃ to 80℃, the reaction time is 1h to 2h, and the reaction pH value is 0.5 to 1.

5. After the reaction is completed, solid-liquid separation is performed to obtain the ferrous oxide residue and the oxide slag. The oxide slag is returned to the mild leaching process.

9. The leaching process according to claim 1, characterized in that, During the iron removal process, the reaction temperature is controlled at 80℃-90℃, the pH value of the system is 5.4-6.3, and the reaction time is 30min-120min.

10. The leaching process according to claim 9, characterized in that, After heating the ferrous oxide solution to the reaction temperature, it is mixed with nickel cobalt manganese carbonate and alkali, and the pH value is adjusted to 5.4-6.

3. After the reaction is completed, solid-liquid separation is performed to obtain the purified solution and iron slag.

11. The leaching process according to claim 1, characterized in that, Also includes: Acid-dissolving iron slag: The iron slag is dissolved using sulfuric acid to obtain a ferric sulfate solution; Mild copper leaching: The ferric sulfate solution is mixed with the leaching residue obtained in the mild leaching stage to produce graphite and copper-leached solution; Copper removal by displacement: The nickel-cobalt slag is mixed with the copper leaching solution to obtain a copper and ferrous sulfate solution.

12. The leaching process according to claim 11, characterized in that, The nickel-cobalt slag is added according to the theoretical molar amount of copper ions, the reaction temperature is controlled at 40℃-60℃, the reaction time is 1h-2h, and after the reaction is completed, solid-liquid separation is performed to obtain sponge copper and ferrous sulfate solution. The ferrous sulfate solution is used to prepare the leaching agent base solution in the mild leaching stage.

13. The leaching process of claim 11, wherein, The process of acid dissolving iron slag includes: mixing the obtained iron slag with water to make a slurry, controlling the liquid-solid ratio to 1:1-3, heating to 40℃-85℃, and then mixing with sulfuric acid to a pH value of 0.5-1.

5.

14. The leaching process according to claim 13, characterized in that, During the mild copper immersion process, sulfuric acid is added to control the pH value to 1.0-2.0, the reaction temperature is controlled at 40℃-85℃, and the reaction time is 1h-2h. After the reaction is completed, solid-liquid separation is performed to obtain the graphite and the copper immersion liquid.

Images