Method for recovering positive electrode of waste battery

Abstract

The recovery method provided in the application comprises the following steps: heat treatment of the positive electrode powder and a reducing agent, reduction of nickel, cobalt and manganese in the positive electrode powder, and separation of nickel, cobalt, manganese and lithium in the positive electrode powder by water washing. The obtained solid filter material mainly comprises nickel, cobalt and manganese metals and oxides, and further comprises a small amount of Li2CO3. Then, the solid filter material is dissolved and electrolyzed by using sulfuric acid. Compared with a traditional process, the recovery method provided in the application greatly reduces the consumption of sulfuric acid, and the treatment process is simple and the economic benefit of recovery is high.

Description

Technical Field

[0001] This application relates to the field of battery recycling technology, and in particular to a method for recycling the positive electrode of a waste battery. Background Technology

[0002] With the continuous expansion of the electric vehicle and renewable energy markets, new energy batteries, as an important energy storage device, have been widely used in automobiles, power tools, mobile devices, and other fields due to their high energy density and long lifespan. However, the recycling and disposal of used batteries remains a global challenge. Once batteries are damaged or reach the end of their lifespan, a large number of used batteries are generated, posing potential pollution and resource waste problems to the environment. Among these, batteries using ternary materials as the positive electrode active material are particularly widely used.

[0003] Traditional recycling processes mainly include pyrometallurgy and hydrometallurgy. Pyrometallurgy extracts valuable metals or compounds from cathode materials through high-temperature treatment. While the process is simple, its recovery efficiency and product quality are relatively low, and it easily generates harmful gases that pollute the environment. Hydrometallurgy, on the other hand, involves pre-treating the cathode material and then using processes such as acid leaching and extraction to enrich and recycle or utilize the valuable metals. However, this process requires large amounts of acids, alkalis, or extraction solutions. Summary of the Invention

[0004] The purpose of this application is to provide a method for recycling the positive electrode of waste batteries, thereby improving the recovery rate of nickel and cobalt while reducing the use of sulfuric acid. The specific technical solution is as follows:

[0005] The first aspect of this application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0006] (1) Obtain the positive electrode of the waste battery, and pre-treat the positive electrode to obtain positive electrode powder;

[0007] (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, then washed with water and filtered to obtain solid filter material and lithium-containing filtrate; the reducing agent is selected from at least one of carbon monoxide and carbon powder; the solid filter material includes elemental Me, oxide MeO and Li2CO3, wherein Me is selected from at least one of elements Ni, Co and Mn;

[0008] (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone the dissolution reaction.

[0009] (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

[0010] In some embodiments of this application, in step (2), the reducing agent is selected from carbon monoxide, and the flow rate of carbon monoxide introduced per 10g of positive electrode powder is 1L / min to 3L / min; or, the reducing agent is selected from carbon powder, and the mass ratio of the positive electrode powder to the carbon powder is 100:(8 to 15).

[0011] In some embodiments of this application, in step (2), the heat treatment time t1 is 1h to 3h.

[0012] In some embodiments of this application, in step (2), the water washing satisfies at least one of the following conditions:

[0013] Condition a: The solid-liquid ratio of the water wash is 1:(10 to 100), wherein the unit of solid in the water wash is g and the unit of liquid is ml;

[0014] Condition b: The washing process is completed when the pH of the washing solution after rinsing is 7 to 8.

[0015] In some embodiments of this application, in step (2), the lithium elution rate of the lithium-containing filtrate is 85% to 90%.

[0016] In some embodiments of this application, in step (3), the slurry has a solid content W1 of 1 g / L to 50 g / L and a pH of 3 to 6.5.

[0017] In some embodiments of this application, in step (3), the temperature T2 of the dissolution reaction is 50°C to 80°C and the time t2 is 0.5h to 2h.

[0018] In some embodiments of this application, in step (3), the number of moles of sulfuric acid is N1, the total number of moles of nickel, cobalt and manganese in the liquid phase is N2, and the number of moles of lithium in the liquid phase is N7, satisfying 0.9╳(N2+0.5N7)≤N1≤1.1╳(N2+0.5N7), wherein the number of moles of sulfuric acid is calculated as the number of moles of "H2SO4".

[0019] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 6.5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V.

[0020] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V.

[0021] In some embodiments of this application, in step (4), at least the solid filter material is added to the slurry during the electrolysis process.

[0022] In some embodiments of this application, the solid filter media is added to the slurry to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 3 to 6.5.

[0023] In some embodiments of this application, the solid filter media and sulfuric acid are added to the slurry to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 3 to 6.5.

[0024] In some embodiments of this application, the solid filter media and sulfuric acid are added to the slurry to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 3 to 5.

[0025] In some embodiments of this application, when the total mass of nickel and / or cobalt added to the cathode product is m1, the solid filter material is added, or the solid filter material and sulfuric acid are added; wherein, m1≤0.1m0; m0 is the total mass of nickel and / or cobalt in the solid filter material added when preparing the slurry in step (3).

[0026] In some embodiments of this application, 0.0001m0 ≤ m1 ≤ 0.1m0.

[0027] In some embodiments of this application, the total molar amount of nickel and / or cobalt added to the cathode product is N3, and the total molar amount of nickel and / or cobalt added to the solid filter material is N4, where 0.95N3≤N4≤1.05N3.

[0028] In some embodiments of this application, the number of moles of lithium in the added solid filter material is N5, and the number of moles of added sulfuric acid is N6, where 0.45N5≤N6≤0.55N5, and the number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

[0029] In some embodiments of this application, step (4) includes any of the following:

[0030] Method 1: Continuously add the solid filter material and sulfuric acid to the slurry. When the first preset condition is reached, discharge part of the electrolytically treated slurry and purify the lithium element in the electrolytically treated slurry to obtain mother liquor. Return the mother liquor to the slurry in step (4) to continue the electrolytic treatment, so that the electrolytic treatment continues without stopping.

[0031] Method 2: Add the solid filter material and sulfuric acid to the slurry, and stop the electrolysis process when the second preset condition is reached;

[0032] Method 3: Add the solid filter material and sulfuric acid to the slurry. After a period of time, stop feeding. Stop the electrolysis process when the third preset condition is reached.

[0033] Method 4: Add the solid filter material to the slurry, and stop the electrolysis process when the fourth preset condition is reached.

[0034] In some embodiments of this application, in Method 1, the first preset condition is that the actual concentration C1 of lithium salt in the electrolyzed slurry satisfies 0.7C2≤C1<C2, wherein the theoretical saturation concentration of lithium salt in the electrolyzed slurry is C2.

[0035] In some embodiments of this application, the volume of the slurry is V, and the volume of the electrolyzed slurry discharged each time is V', where V' ≤ 0.2V.

[0036] In some embodiments of this application, the discharged electrolytically treated slurry is filtered to obtain filter residue and filtrate. The lithium element in the filtrate is purified to obtain lithium salt and mother liquor. The mother liquor is returned to the slurry in step (4) to continue the electrolytic treatment. The purification treatment includes evaporation, concentration and crystallization or carbonization deposition.

[0037] In some embodiments of this application, in the second method, the second preset condition is the actual concentration C1 of lithium salt in the electrolyzed slurry, which satisfies 0.9C2≤C1<C2, wherein the theoretical saturation concentration of lithium salt in the electrolyzed slurry is C2.

[0038] In some embodiments of this application, in method three, the third preset condition is any one of the following conditions:

[0039] (1) The pH of the electrolyzed slurry is less than or equal to 3;

[0040] (2) The total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%;

[0041] (3) The current density during the electrolysis process is less than or equal to 8 mA / cm². 2 .

[0042] In some embodiments of this application, in method four, the fourth preset condition is any one of the following conditions:

[0043] (4) The pH of the electrolyzed slurry is greater than or equal to 6.5;

[0044] (5) The total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%;

[0045] (6) The current density during the electrolysis process is less than or equal to 8 mA / cm². 2 .

[0046] The beneficial effects of this application are:

[0047] The recycling method provided in this application pre-recovers lithium from waste ternary lithium batteries, achieving the separation of lithium and nickel, cobalt, and manganese. Specifically, the cathode powder is heat-treated with a reducing agent to reduce the nickel, cobalt, and manganese, and then washed with water to essentially separate the nickel, cobalt, and manganese from the lithium. The resulting solid filter material mainly consists of nickel, cobalt, and manganese metal (Me) and its oxide (MeO), and also includes a small amount of Li2CO3. Subsequently, the nickel, cobalt, and manganese metal and its oxide produced by reduction are acid-dissolved and electrolyzed. During the slurry electrolysis process, the washed solid filter material and a small amount of sulfuric acid can be continuously added, and part of the electrolyzed slurry (i.e., the slurry in electrolysis) can be discharged. After lithium extraction, the resulting mother liquor can be returned, thus achieving a cyclical recycling process. Alternatively, the washed solid filter material and a small amount of sulfuric acid can be added, and the electrolysis process can be stopped when preset conditions are reached. Alternatively, the feeding can be stopped after electrolysis for a period of time as needed, that is, the addition of washed solid filter material and sulfuric acid can be stopped, and the electrolysis process will stop. Alternatively, only solid filter material can be added, and the electrolysis process can be stopped when preset conditions are reached. Of the four processes mentioned above, only Li... + It consumes sulfuric acid, which is much less than traditional processes, and the process is simple.

[0048] Of course, implementing any product or method of this application does not necessarily require achieving all of the advantages described above at the same time. Attached Figure Description

[0049] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other embodiments can be obtained based on these drawings.

[0050] Figure 1 A flowchart illustrating the recycling methods of some embodiments of this application;

[0051] Figure 2 The image shows the X-ray diffraction pattern of the calcined material in Example 1. Detailed Implementation

[0052] The technical solutions of this application will be clearly and completely described below with reference to the embodiments and accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art based on this application are within the scope of protection of this application.

[0053] This application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0054] (1) Obtain the positive electrode of the waste battery and pre-treat the positive electrode to obtain positive electrode powder;

[0055] (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, and then washed and filtered to obtain solid filter material and lithium-containing filtrate; the solid filter material includes at least elemental Me and / or oxide MeO, wherein Me is selected from at least one of the elements Ni, Co and Mn;

[0056] (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone a dissolution reaction.

[0057] (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

[0058] In some embodiments of this application, in step (2), the reducing agent is selected from at least one of carbon monoxide and toner.

[0059] In some embodiments of this application, in step (2), the washing is a water wash.

[0060] The recycling method provided in this application has a simple processing flow and can reduce the amount of acid used, resulting in low resource consumption.

[0061] The first aspect of this application provides a method for recycling the positive electrode of a waste battery, which includes the following steps:

[0062] (1) Obtain the positive electrode of the waste battery and pre-treat the positive electrode to obtain positive electrode powder;

[0063] (2) The positive electrode powder and reducing agent are heat-treated at a temperature T1 of 550℃ to 700℃, then washed with water and filtered to obtain solid filter material and lithium-containing filtrate; the reducing agent is selected from at least one of carbon monoxide and carbon powder, specifically, Figure 1 The experimental flow chart shows that the reducing agent is selected from carbon monoxide; the solid filter media includes elemental Me, oxide MeO and Li2CO3, wherein Me is selected from at least one of the elements Ni, Co and Mn;

[0064] (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone a dissolution reaction.

[0065] (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

[0066] The recycling method provided in this application pre-recovers lithium from waste ternary lithium batteries, achieving separation of lithium and nickel, cobalt, and manganese. Specifically, when the reducing agent is carbon monoxide (CO), the reaction 2LiMeO2 + 2CO = Li2CO3 + Me + MeO + CO2 occurs. CO reacts with LiMeO2 to generate CO2, which then reacts with C in the cathode powder to generate CO. This CO2 continues to react with the cathode powder, removing carbon and reducing nickel, cobalt, and manganese. The nickel, cobalt, and manganese are then largely separated from lithium through water washing. The resulting solid filter material mainly consists of nickel, cobalt, and manganese metal (Me) and its oxide (MeO), and also includes a small amount of Li2CO3. Subsequently, the reduced nickel, cobalt, and manganese metal and its oxide are acid-dissolved and electrolyzed. During the slurry electrolysis process, the washed solid filter material and a small amount of sulfuric acid can be continuously added to ensure the lithium content in the slurry during electrolysis. + With a suitable Ni content (not too high to cause saturation and affect electrolysis), some of the electrolyzed slurry can be discharged to ensure the Ni content in the slurry during the electrolysis process. 2+ / Co2 + The dynamic equilibrium of lithium content allows the mother liquor obtained after lithium extraction to be returned to the slurry in the electrolysis process, thus achieving a cyclical recycling process. Alternatively, it can be supplemented with washed solid filter media and a small amount of sulfuric acid to achieve the desired Li content in the slurry. + Electrolysis should be stopped when the concentration is saturated or near saturation; alternatively, feeding can be stopped after a period of electrolysis, i.e., the addition of washed solid filter media and sulfuric acid should be stopped, while electrolysis will continue. + The concentration gradually increases while the content of nickel and cobalt ions gradually decreases, and the electrolytic treatment will stop after reaching a certain level; alternatively, only solid filter media can be added. The lithium in the solid filter media will consume the sulfuric acid in the slurry, and the electrolytic treatment will stop when preset conditions are reached. In the above four processes, since sulfuric acid is generated during the electrolytic treatment, the consumption of sulfuric acid is greatly reduced compared with traditional processes, and the treatment process is simple.

[0067] When carbon (C) powder is used as the reducing agent, the reaction 2LiMeO2 + C = Li2CO3 + Me + MeO occurs, removing carbon from the cathode powder and reducing nickel, cobalt, and manganese. The process is similar to when CO is used as the reducing agent, and will not be elaborated further here. When using carbon powder as the reducing agent, an inert gas, such as nitrogen, is introduced to facilitate the reduction roasting process.

[0068] Specifically, in the recovery method provided in this application, the dissolution and electrolysis processes of the solid filter media Me / MeO are carried out in the same electrolytic cell or connected containers. Since sulfuric acid is generated during the electrolysis process, the H2SO4 produced can continuously dissolve the newly added solid filter media Me / MeO, allowing for full utilization of the sulfuric acid and reducing acid consumption. In this process, the amount of sulfuric acid used is significantly reduced compared to traditional processes, which often require SO4 in combination with Co, Ni, and Mn. 2- If calculated using sulfur (S), 1 mol of Co / Ni / Mn corresponds to 1 mol of S, thus requiring a corresponding amount of S to match the molar amounts of Co, Ni, and Mn. However, in the recovery method provided in this application, most of the Li element is removed during the water washing step. The sulfuric acid consumed by Me / MeO during dissolution corresponds to (equal in amount to) the H2SO4 produced during electrolysis, meaning that Me does not consume S. Therefore, only the S element needed to replenish the Li that was not washed away during the water washing process needs to be replenished, thus reducing the consumption of sulfuric acid. Consequently, the overall demand for sulfuric acid or acidic substances is reduced during the recovery process.

[0069] In addition, in step (2), the heat treatment temperature T1 is between 550°C and 700°C. For example, the heat treatment temperature T1 can be 550°C, 560°C, 570°C, 580°C, 590°C, 600°C, 610°C, 620°C, 630°C, 640°C, 650°C, 660°C, 670°C, 680°C, 690°C, or 700°C, or any two of the above numbers. When the heat treatment temperature is too low, for example below 550°C, the structure of LiMeO2 cannot be destroyed, the reaction is insufficient, and most of the trivalent Me ions cannot be converted into divalent Me ions. When the heat treatment temperature is too high, for example above 700°C, most of the Li element will volatilize, resulting in a significant reduction in the Li recovery rate and causing economic losses. Therefore, by controlling the heat treatment temperature T1 within the above range, the reducing agent can react fully with LiMeO2, the lithium element recovery rate is high, and thus the economic benefits of the recycling process can be improved.

[0070] This application does not impose any particular restrictions on the method of obtaining the positive electrode of the waste battery, as long as it can achieve the purpose of this application. For example, it can be obtained by dismantling the waste battery or by purchasing it directly.

[0071] In this application, when the reducing agent is selected from CO, the heat treatment in step (2) includes the following reaction:

[0072] 2CO+2LiMeO2=Li2CO3+Me+MeO+CO2↑;

[0073] CO2 + C = 2CO↑.

[0074] In this application, the dissolution reaction in step (3) includes the following reactions:

[0075] Me + H₂SO₄ = H₂↑ + MeSO₄;

[0076] MeO + H2SO4 = H2O + MeSO4;

[0077] Li2CO3+H2SO4=Li2SO4+H2O+CO2.

[0078] In this application, when Me is selected from Ni, Co, and Mn (i.e., the waste battery is a nickel-cobalt-manganese ternary battery), the electrolytic treatment in step (4) includes the following reactions:

[0079] 2NiSO4+2H2O=2Ni+2H2SO4+O2↑

[0080] 2CoSO4+2H2O=2Co+2H2SO4+O2↑

[0081] NiSO4+MnSO4+2H2O=Ni+MnO2+2H2SO4

[0082] CoSO4+MnSO4+2H2O=Co+MnO2+2H2SO4

[0083] In one possible example, for an 811 ternary battery, after reduction and calcination of the solid filter material, Ni and Co elements mainly exist in elemental form, Mn element mainly exists in oxide form (MnO), and a small amount of Li₂CO₃ is also contained.

[0084] Dissolution reactions include:

[0085] 8Ni+Co+MnO+10H2SO4=8NiSO4+CoSO4+MnSO4+H2O+9H2↑;

[0086] Li2CO3+H2SO4=Li2SO4+H2O+CO2↑;

[0087] Electrolysis reactions include:

[0088] 8NiSO4 + CoSO4 + MnSO4 + 10H2O = 8Ni + Co + MnO2 + 10H2SO4 + 4O2↑; Therefore, the overall reaction equation for dissolution and electrolysis includes the reaction shown in the following equation, in which elemental Ni and Co are transformed from the slurry into cathode products:

[0089] 8Ni+Co+MnO+9H2O=8Ni+Co+MnO2+9H2↑+4O2↑;

[0090] Li2CO3+H2SO4=Li2SO4+H2O+CO2↑.

[0091] As can be seen from the above reaction formula, although sulfuric acid is consumed during the dissolution reaction of nickel, cobalt, and manganese, an equal amount of sulfuric acid is generated during the electrolysis process. Only lithium carbonate consumes sulfuric acid. Therefore, only the amount of sulfuric acid corresponding to that of lithium carbonate needs to be replenished during the entire recovery process, thus reducing the amount of sulfuric acid consumed. At the same time, since the content of lithium carbonate is relatively small, the amount of sulfuric acid consumed is also small, resulting in a reduction in the total amount of sulfuric acid consumed during the entire recovery process.

[0092] Other ternary batteries are similar, such as the ternary 622 lithium-ion battery and the ternary 523 lithium-ion battery, which will not be discussed further here.

[0093] In another possible example, for lithium cobalt oxide batteries, the solid filter material includes elemental Co, oxide CoO and Li2CO3. The overall reaction anode produces O2, and only Li2CO3 consumes sulfuric acid. However, due to the low content of lithium carbonate, the overall amount of sulfuric acid consumed is also low.

[0094] Specifically, when Me is Co (i.e., the waste battery is a lithium cobalt oxide battery), the dissolution reaction in step (3) includes the following reactions:

[0095] Co + H₂SO₄ = H₂↑ + CoSO₄;

[0096] CoO + H2SO4 = H2O + CoSO4;

[0097] Li2CO3+H2SO4=Li2SO4+H2O+CO2↑;

[0098] The electrolytic treatment in step (4) includes the following reactions:

[0099] 2CoSO4+2H2O=2Co+2H2SO4+O2↑;

[0100] The overall reaction equation includes:

[0101] 2CoO=Co+O2↑;

[0102] 2Co + 2H₂O = 2Co + 2H₂↑ + O₂↑

[0103] Li2CO3+H2SO4=Li2SO4+H2O+CO2↑;

[0104] In some embodiments of this application, the waste battery is a waste ternary nickel-cobalt-manganese battery, and the anode product includes manganese dioxide.

[0105] In some embodiments of this application, in step (2), the reducing agent is selected from carbon monoxide, and the flow rate of carbon monoxide introduced per 10g of positive electrode powder is 1L / min to 3L / min. For example, the flow rate V of carbon monoxide can be 1L / min, 1.2L / min, 1.4L / min, 1.5L / min, 1.6L / min, 1.8L / min, 2L / min, 2.2L / min, 2.4L / min, 2.5L / min, 2.6L / min, 2.8L / min, or 3L / min, or any two of the above numbers. By adjusting the flow rate V of carbon monoxide within the above range, on the one hand, CO and LiMeO2 react fully, which is beneficial for separating lithium elements in the subsequent water washing process; on the other hand, residual carbon in the positive electrode powder can be removed. The resulting solid filter material is basically free of carbon and most of the lithium elements are washed away, which is beneficial for improving the recovery rate of Me elements.

[0106] In some embodiments of this application, the reducing agent is selected from carbon powder, and the mass ratio of cathode powder to carbon powder is 100:(8 to 15). For example, the mass ratio of cathode powder to carbon powder can be 100:8, 100:9, 100:10, 100:11, 100:12, 100:13, 100:14, or 100:15, or any two of the above numbers. By adjusting the mass ratio of cathode powder to carbon powder within the above range, the carbon powder reacts fully with LiMeO2, which is beneficial for separating lithium elements during the subsequent acid washing process.

[0107] In some embodiments of this application, the heat treatment time t1 in step (2) is between 1 h and 3 h. For example, the heat treatment time t1 can be 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h, 1.9 h, 2 h, 2.1 h, 2.2 h, 2.3 h, 2.4 h, 2.5 h, 2.6 h, 2.7 h, 2.8 h, 2.9 h, or 3 h, or any two of the above values. By adjusting the heat treatment time t1 within the above range, CO can fully react with LiMeO2, converting trivalent Me ions into divalent Me ions, which is beneficial to improving the recovery rate of Me element; moreover, lithium element is not easily volatilized, and the recovery rate of lithium element is high when recovering lithium element through lithium-containing filtrate in the subsequent process. Thus, the economic benefits of the recovery process can be improved.

[0108] In some embodiments of this application, in step (2), the solid-liquid ratio X of the water washing is 1:(10 to 100), in g / ml. For example, the solid-liquid ratio X can be 1:10, 1:20, 1:30, 1:40, 1:50, 1:60, 1:70, 1:80, 1:90, or 1:100, or any two of the above numbers. By adjusting the solid-liquid ratio X of the water washing within the above range, the recovery rate of lithium ions can be improved.

[0109] In some embodiments of this application, in step (2), the washing is completed when the pH of the washing solution after multiple washes is 7 to 8. For example, the pH of the washing solution can be 7.1, 7.2, 7.3, 7.4, 7.5, 7.6, 7.7, 7.8, 7.9, or 8, or any two of the above numbers. The fact that the pH of the washing solution after washing is within the above range indicates that most of the lithium element has been cleaned. Therefore, by controlling the pH of the washing solution within the above range, effective separation of lithium and me elements can be achieved.

[0110] In some embodiments of this application, in step (2), the solid-liquid ratio X of the water washing is 1:(10 to 100), and the pH of the washing solution after water washing is 7 to 8, at which point the water washing is completed. By adjusting the solid-liquid ratio X of the water washing and the pH of the washing solution after water washing within the above ranges, effective separation of lithium and Me elements can be achieved.

[0111] In some embodiments of this application, in step (2), the lithium elution rate of the lithium-containing filtrate is 85% to 90%. For example, the lithium elution rate of the lithium-containing filtrate can be 85%, 86%, 87%, 88%, 89%, or 90%, or any two of the above figures. A lithium elution rate within the above range indicates that after acid washing, most of the lithium element remains in the lithium-containing filtrate, thus increasing the lithium recovery rate during subsequent lithium element recovery from the filtrate. Simultaneously, it can reduce the lithium content in the solid filter material, which is beneficial for subsequent electrolysis reactions.

[0112] In some embodiments of this application, in step (3), the solid content W1 of the slurry is from 1 g / L to 50 g / L, and the pH is from 3 to 6.5. For example, the solid content W of the slurry can be 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L, or 50 g / L, or between any two of the above figures. For example, the pH of the slurry can be 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.2, 5.5, 5.7, 6, 6.1, 6.2, 6.3, 6.4, or 6.5, or any two of the above numbers. By controlling the solid content W1 and pH of the slurry in step (3) within the above ranges, it is possible to avoid the continuous generation of sulfuric acid and the resulting H+ during subsequent electrolysis treatment due to the electrolysis rate exceeding the dissolution rate. + The accumulation of these deposits can then affect subsequent electrolytic processing.

[0113] In some embodiments of this application, in step (3), the temperature T2 of the dissolution reaction is 50°C to 80°C, and the time t2 is 0.5h to 2h. For example, the temperature T2 of the dissolution reaction can be 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, or any two of the above numbers. For example, the time t2 of the dissolution reaction can be 0.5h, 0.6h, 0.7h, 0.8h, 0.9h, 1h, 1.1h, 1.2h, 1.3h, 1.4h, 1.5h, 1.6h, 1.7h, 1.8h, 1.9h, or 2h, or any two of the above numbers. By controlling the temperature T2 and time t2 of the dissolution reaction within the above ranges, it is beneficial to fully dissolve the solid filter material to obtain a slurry with the desired solid content.

[0114] In some embodiments of this application, in step (3), the number of moles of sulfuric acid is N1, the total number of moles of nickel, cobalt and manganese in the liquid phase is N2, and the number of moles of lithium in the liquid phase is N7, satisfying 0.9×(N2+0.5N7)≤N1≤1.1×(N2+0.5N7), wherein the number of moles of sulfuric acid is calculated as the number of moles of "H2SO4". For example, N1 can be 0.90×(N2+0.5N7), 0.91×(N2+0.5N7), 0.92×(N2+0.5N7), 0.93×(N2+0.5N7), 0.94×(N2+0.5N7), 0.95×(N2+0.5N7), 0.96×(N2+0.5N7), 0.97×(N2+0.5N7), 0.98×(N2+0.5N7), 0.99×(N2+0.5N7), 1 ...9×(N2+0.5N7), 7) 1.01×(N2+0.5N7), 1.02×(N2+0.5N7), 1.03×(N2+0.5N7), 1.04×(N2+0.5N7), 1.05×(N2+0.5N7), 1.06×(N2+0.5N7), 1.07×(N2+0.5N7), 1.08×(N2+0.5N7), 1.09×(N2+0.5N7) or 1.1×(N2+0.5N7), or any two of the above numbers. The total number of moles of Me and lithium in the liquid phase is basically the same as the number of moles of sulfuric acid. During the dissolution process, Me can be converted into MeSO4, and then sulfuric acid with a molar number of Me can be generated during the electrolysis process. In the subsequent dissolution and electrolysis process, only sulfuric acid corresponding to the number of moles of lithium needs to be added. Therefore, the overall consumption of sulfuric acid is small, which improves the economic benefits of recovery.

[0115] In some embodiments of this application, in step (3), the number of moles of sulfuric acid is N1, and the total number of moles of nickel, cobalt, and manganese in the solid filter material is N5, where N1 < N5. For example, N1 can be 0.9N5, 0.85N5, 0.8N5, 0.7N5, 0.6N5, 0.5N5, 0.4N5, 0.3N5, ​​etc. To ensure that the pH of the slurry meets the requirements and to better initiate electrolysis directly, the difference between N1 and N5 can be larger, and the undissolved solid filter material can be dissolved using sulfuric acid generated by electrolysis. For example, 0.4N5 ≤ N1 ≤ 0.8N5.

[0116] In some embodiments of this application, in step (3), the sulfuric acid is commercially available concentrated sulfuric acid.

[0117] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V. For example, the pH of the electrolysis treatment can be 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5, or any two of the above numbers. For example, the temperature T3 of the electrolysis treatment can be 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, or any two of the above numbers. For example, the voltage for electrolysis can be 2.5V, 2.7V, 2.9V, 3V, 3.2V, 3.4V, 3.5V, 3.7V, 3.9V, 4V, 4.2V, 4.4V, or 4.5V, or any two of the above values. During electrolysis, when the pH, temperature (T3), and voltage are within the above ranges, the electrolysis reaction rate is faster, which is conducive to the complete progress of the electrolysis reaction and improves the economic efficiency of the recovery.

[0118] In some embodiments of this application, in step (4), the pH of the electrolysis treatment is 3 to 6.5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V. For example, the pH of the electrolysis treatment can be 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.2, 5.5, 5.7, 6, 6.1, 6.2, 6.3, 6.4, or 6.5, or any two of the above numbers. For example, the temperature T3 of the electrolysis treatment can be 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, or any two of the above numbers. For example, the voltage for electrolysis can be 2.5V, 2.7V, 2.9V, 3V, 3.2V, 3.4V, 3.5V, 3.7V, 3.9V, 4V, 4.2V, 4.4V, or 4.5V, or any two of the above values. During electrolysis, when the pH, temperature (T3), and voltage are within the above ranges, the electrolysis reaction rate is faster, which is conducive to the complete progress of the electrolysis reaction and improves the economic efficiency of the recovery.

[0119] In some embodiments of this application, in step (4), adding solid filter media to the slurry during the electrolytic treatment process involves adding solid filter media and sulfuric acid to the slurry. Preferably, the solid filter media and sulfuric acid are added to the slurry to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and to maintain the pH of the slurry in the range of 3 to 5. For example, adding solid filter media to the slurry maintains the solid content W2 of the slurry at 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L, or 50 g / L, or between any two of the above numbers; and maintains the pH of the slurry at 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, or 5, or between any two of the above numbers.

[0120] In some embodiments of this application, the solid filter media and sulfuric acid are added to the slurry to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 3 to 6.5. For example, adding solid filter media to the slurry maintains the solid content W2 of the slurry at 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L, or 50 g / L, or between any two of the above numbers; and maintains the pH of the slurry at 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.2, 5.5, 5.7, 6, 6.1, 6.2, 6.3, 6.4, or 6.5, or between any two of the above numbers.

[0121] The addition of washed solid filter media (mainly containing Me / MeO and a small amount of Li2CO3) to the slurry serves two purposes. First, the added solid filter media can continuously react with the H2SO4 generated by electrolysis, thus consuming the H2SO4 in the system. +Maintaining the pH of the system within the aforementioned range ensures the normal operation of the electrolysis process. Furthermore, the generation of H2SO4 during slurry electrolysis allows for the continued dissolution of newly added solid filter media, increasing the throughput. Most of the H2SO4 is recycled, with only a small portion of the sulfuric acid consumed by lithium, reducing the overall H2SO4 usage and enabling the electrolysis reaction to proceed continuously. Additionally, no reducing agent is required during electrolysis, reducing its use and saving process steps. Therefore, by adding solid filter media and sulfuric acid to maintain the slurry's solid content and pH within the aforementioned range, the dissolution and electrolysis reactions can proceed continuously, including continuous electrolysis or cessation after a certain period, while avoiding the negative impact of continuous sulfuric acid generation on H2SO4 levels. + The accumulation of sediment can affect the normal operation of the electrolytic process. In some embodiments of this application, solid filter media and sulfuric acid are added to the slurry, and step (4) includes any one of the following three methods:

[0122] Method 1: Solid filter media and sulfuric acid are continuously added to the slurry. When the first preset condition is reached, a portion of the electrolyzed slurry is discharged. The lithium element in the electrolyzed slurry is purified to obtain mother liquor, which is then returned to the slurry in step (4) for continued electrolysis, allowing the electrolysis to continue without stopping. Preferably, the first preset condition is that the actual concentration C1 of lithium salt in the electrolyzed slurry satisfies 0.7C2≤C1<C2, where the theoretical saturation concentration of lithium salt in the electrolyzed slurry is C2. In Method 1, the sulfuric acid generated by electrolysis and the added sulfuric acid can dissolve more solid filter media, enabling the dissolution reaction to continue. Simultaneously, as the electrolysis reaction proceeds, Li₂CO₃ reacts to form Li₂SO₄ in the liquid phase of the slurry, enriching it and increasing the lithium ion concentration. A portion of the slurry needs to be discharged. However, discharging this portion reduces the content of Me (e.g., Ni and / or Co) in the system. Therefore, the purified mother liquor from the discharged slurry is added back into the slurry for continued electrolysis. The Ni and / or Co content in the mother liquor is highly compatible with the required Ni and / or Co content in the system. Adding it to the slurry helps maintain the Ni and / or Co ion concentration in the liquid phase within a relatively constant range, allowing the electrolysis reaction to continue uninterrupted. Thus, the electrolysis and dissolution reactions can proceed simultaneously and continuously during the recovery process, achieving uninterrupted continuous recovery and improving recovery rate and production capacity. In addition, if the lithium ion concentration in the electrolyzed slurry is too low, it indicates that the reaction is incomplete, and if the lithium ion concentration is too high, it will affect the electrolysis reaction. Therefore, when the first preset condition meets 0.7C2≤C1<C2, a portion of the electrolyzed slurry is discharged, which is economically efficient. Specifically, C1 can be 0.7C2, 0.71C2, 0.72C2, 0.73C2, 0.74C2, 0.75C2, 0.76C2, 0.77C2, 0.78C2, 0.79C2, 0.8C2, 0.81C2, 0.82C2, 0.83C2, 0.84C2, 0.85C2, 0.86C2, 0.87C2, 0.88C2, 0.89C2, 0.9C2, 0.91C2, 0.92C2, 0.93C2, or 0.94C2, 0.95C2, 0.96C2, 0.97C2, 0.98C2, or 0.99C2, or any two of the above numbers. Furthermore, no harmful gases are generated during the entire recycling process, making it an environmentally friendly recycling method.

[0123] In some embodiments of this application, C2 can be from 335 g / L to 345 g / L.

[0124] In some embodiments of this application, the volume of the slurry is V, and the volume of the electrolyzed slurry discharged each time is V', where V' ≤ 0.2V. For example, V' can be 0.01V, 0.03V, 0.05V, 0.07V, 0.1V, 0.12V, 0.15V, 0.17V, or 0.20V, or any two of the above values. Having the volume of the electrolyzed slurry discharged each time within the above range is beneficial because it allows the electrolysis and dissolution reactions to proceed simultaneously and continuously during the recovery process, achieving uninterrupted continuous recovery and improving recovery rate and production capacity.

[0125] In some embodiments of this application, the discharged electrolytically treated slurry is filtered to obtain filter residue and filtrate. The lithium element in the filtrate is purified to obtain lithium salt and mother liquor. The mother liquor is returned to the slurry in step (4) for further electrolytic treatment. The purification treatment is evaporation, concentration, and crystallization. Specifically, the filtrate is heated, and a certain amount of water is evaporated to precipitate lithium sulfate crystals, thus extracting the lithium element from the filtrate. The resulting mother liquor mainly includes Ni and / or Co elements. Adding the mother liquor to the slurry not only improves the final recovery rate of the target metal but also reduces solid waste in the recovery process. More importantly, the Ni and / or Co elements in the mother liquor can keep the ion concentration of Ni and / or Co elements in the liquid phase of the slurry dynamically within a relatively constant range. Furthermore, the return of the mother liquor can keep the liquid level in the electrolytic cell stable. Therefore, returning it to the slurry ensures that the electrolytic reaction can continue without stopping, which is beneficial for achieving continuous recovery without interruption. This application does not have any particular limitation on the temperature of the heated filtrate, as long as the purpose of this application can be achieved.

[0126] In some embodiments of this application, the discharged electrolytically treated slurry is filtered to obtain filter residue and filtrate. The lithium element in the filtrate is purified to obtain lithium salt and mother liquor. The mother liquor is returned to the slurry in step (4) for further electrolytic treatment. The purification treatment includes carbonization deposition. Specifically, a carbonizing agent is added to the filtrate for carbonization deposition. The carbonizing agent can be one or more of sodium carbonate, potassium carbonate, and carbon dioxide. The filtrate is carbonized to obtain a lithium-containing salt, a nickel-containing and / or cobalt-containing salt, and mother liquor, thereby realizing the recovery of lithium. After lithium extraction by carbonization deposition, elements such as nickel / cobalt will also be deposited in solid form (e.g., nickel carbonate, cobalt carbonate). At this point, nickel / cobalt carbonate can be separated from lithium carbonate, and then the nickel and cobalt carbonate can be returned to the slurry. Before returning to the slurry, the nickel / cobalt carbonate can be dissolved with sulfuric acid to improve the recovery rate of nickel and cobalt. More importantly, the dissolved nickel / cobalt elements can keep the ion concentration of Ni and / or Co elements in the liquid phase of the slurry in a relatively constant range to ensure that the electrolysis reaction can continue without stopping. Moreover, returning the mother liquor can also keep the liquid level in the electrolytic cell stable. When the carbonizing agent is selected from sodium carbonate, it is best to remove the sodium sulfate in the mother liquor before returning it to the slurry. Of course, the sodium can be removed after the sodium in the mother liquor has accumulated to a certain extent, and then the reaction can be carried out in the slurry.

[0127] In this application, the method for removing sodium from the mother liquor generally involves evaporating and crystallizing the mother liquor before returning it to the system to separate most of the sodium as sodium sulfate, after which the remaining mother liquor is returned to the slurry. This process does not strictly limit the method of sodium removal from the mother liquor; those skilled in the art can choose appropriate sodium removal methods according to actual needs.

[0128] Method 2: Add solid filter media and sulfuric acid to the slurry, and stop the electrolysis treatment when the second preset condition is reached. Preferably, the second preset condition is that the actual concentration C1 of lithium salt in the electrolyzed slurry satisfies 0.9C2≤C1<C2, where the theoretical saturation concentration of lithium salt in the electrolyzed slurry is C2. In Method 1 above, the sulfuric acid generated by electrolysis and the added sulfuric acid can dissolve more solid filter media, allowing the dissolution reaction to continue. Simultaneously, as the electrolysis reaction proceeds, Li2CO3 reacts to form Li2SO4 in the liquid phase of the slurry, enriching the lithium ion concentration. When the lithium ion concentration in the electrolyzed slurry satisfies 0.9C2≤C1<C2, i.e., close to the theoretical saturation concentration, the electrolysis reaction becomes difficult to continue, and the electrolysis treatment stops. Specifically, C1 can be 0.9C2, 0.91C2, 0.92C2, 0.93C2 or 0.94C2, 0.95C2, 0.96C2, 0.97C2, 0.98C2 or 0.99C2, or any two of the above numbers.

[0129] Method 3: Add solid filter media and sulfuric acid to the slurry. After a period of time, stop feeding. Stop electrolysis when the third preset condition is reached. When solid filter media and sulfuric acid are added for a period and then stopped, the amount consumed by the dissolution reaction gradually decreases. The sulfuric acid produced during electrolysis cannot be consumed in time, resulting in the amount of sulfuric acid produced by the electrolysis reaction exceeding the amount consumed by the dissolution reaction. As the reaction continues, sulfuric acid gradually accumulates, causing the pH of the system to decrease. Simultaneously, as the electrolysis and dissolution reactions proceed, nickel and / or cobalt are produced at the cathode. After feeding is stopped, the Co produced during dissolution... 2+ And / or Ni 2+ The amount is less than the Co lost due to electrolysis. 2+ And / or Ni 2+ The amount of Co in the system 2+ And / or Ni 2+ As the concentration decreases, the current density also gradually decreases. Therefore, when the third preset condition is any one of the following conditions (1) to (3), the electrolysis reaction stops, and the element recovery can be completed: (1) the pH of the electrolyzed slurry is less than or equal to 3; (2) the total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%; (3) the current density during the electrolysis process is less than or equal to 8 mA / cm². 2 Of course, those skilled in the art can also choose other suitable third preset conditions according to actual needs.

[0130] In some embodiments of this application, in step (4), adding solid filter media to the slurry during the electrolysis process is called adding solid filter media to the slurry. Preferably, the solid filter media is added to the slurry to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and to maintain the pH of the slurry in the range of 3 to 6.5. For example, adding solid filter media to the slurry maintains the solid content W2 of the slurry at 1 g / L, 2 g / L, 3 g / L, 4 g / L, 5 g / L, 10 g / L, 15 g / L, 20 g / L, 25 g / L, 30 g / L, 34 g / L, 40 g / L, 45 g / L, or 50 g / L, or between any two of the above numbers; and maintains the pH of the slurry at 3, 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, 4.5, 4.6, 4.7, 4.8, 4.9, 5, 5.2, 5.5, 5.7, 6, 6.1, 6.2, 6.3, 6.4, or 6.5, or between any two of the above numbers. When freshly added washed solid filter media (Me / MeO, Li2CO3) are added to the slurry, the added solid filter media can continuously react with the H2SO4 generated by electrolysis, thus consuming the H2SO4 in the system. +Maintaining the pH of the system within the above range ensures the normal operation of the electrolysis process. On the other hand, H2SO4 is generated during the slurry electrolysis process, which can continue to dissolve the newly added solid filter material, increasing the processing capacity of the solid filter material. Most of the H2SO4 is recycled, and only a small portion of the sulfuric acid is consumed by the lithium element, reducing the overall amount of H2SO4 used and enabling the electrolysis reaction to proceed continuously. Furthermore, no reducing agent is added during the electrolysis process, reducing the use of reducing agent and saving process steps. Thus, by adding solid filter material to maintain the solid content and pH of the slurry within the above range, the dissolution reaction and electrolysis reaction can continue for a period of time until the lithium element in the added solid filter material consumes all the sulfuric acid, and the electrolysis process stops. In some embodiments of this application, solid filter material is added to the slurry, and step (4) includes the following method four: adding solid filter material to the slurry, and stopping the electrolysis process when the fourth preset condition is reached. When only solid filter material is added, the lithium element in the solid filter material will continue to consume sulfuric acid. As the reaction continues, the amount of sulfuric acid decreases, causing the pH of the system to increase. Simultaneously, as the electrolysis and dissolution reactions proceed, nickel and / or cobalt are produced at the cathode, while Co is produced during dissolution due to the continuous consumption of sulfuric acid. 2+ And / or Ni 2+ The amount will gradually decrease as the reaction proceeds and the Co produced by dissolution... 2+ And / or Ni 2+ The amount will be less than the Co lost due to electrolysis. 2+ And / or Ni 2+ The amount of Co in the system 2+ And / or Ni 2+ The concentration will decrease, and the current density will also gradually decrease. Therefore, when the fourth preset condition is any one of the following conditions (4) to (6), the electrolysis reaction stops, and the element recovery can be completed: (4) the pH of the electrolyzed slurry is greater than or equal to 6.5; (5) the total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%; (6) the current density during the electrolysis process is less than or equal to 8 mA / cm. 2 Of course, those skilled in the art can also choose other suitable fourth preset conditions according to actual needs.

[0131] In some embodiments of this application, solid filter media is added when the total mass of nickel and / or cobalt in the cathode product increases by m1. In some embodiments of this application, solid filter media and sulfuric acid are added when the total mass of nickel and / or cobalt in the cathode product increases by m1. Wherein, m1 ≤ 0.1m0; preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the total mass of nickel and / or cobalt in the solid filter media in step (3). For example, m1 can be 0.0001m0, 0.0005m0, 0.001m0, 0.005m0, 0.01m0, 0.02m0, 0.03m0, 0.04m0, 0.05m0, 0.06m0, 0.07m0, 0.08m0, 0.09m0, or 0.1m0, or any two of the above numbers. In this application, for example, m1 = 0.0001m0, that is, solid filter media is added while the electrolysis reaction is taking place, or solid filter media and sulfuric acid are added while the electrolysis reaction is taking place, which is beneficial for achieving continuous recovery. As another example, m1 = 0.1m0, that is, solid filter media is added when a certain amount of product is produced at the cathode, or solid filter media and sulfuric acid are added.

[0132] In some embodiments of this application, the amount of supplementary solid filter media is determined based on the amount of nickel and / or cobalt produced by electrolysis, and the total amount of nickel and / or cobalt contained in the supplementary solid filter media is substantially the same as the amount of nickel and cobalt metal produced. Specifically, the total molar amount of nickel and / or cobalt added to the cathode product is N3, and the total molar amount of nickel and / or cobalt in the supplementary solid filter media is N4, where 0.95N3 ≤ N4 ≤ 1.05N3. For example, N4 can be 0.95N3, 0.96N3, 0.97N3, 0.98N3, 0.99N3, N3, 1.01N3, 1.02N3, 1.03N3, 1.04N3, or 1.05N3, or any two of the above numbers.

[0133] In some embodiments of this application, the amount of sulfuric acid added is determined based on the amount of lithium in the added solid filter media. The amount of sulfuric acid added corresponds to the amount of lithium in the added solid filter media; for example, the molar amount of sulfuric acid added is substantially the same as the molar amount of lithium in the added solid filter media. Specifically, the molar amount of lithium in the added solid filter media is N5, and the molar amount of sulfuric acid added is N6, where 0.45N5 ≤ N6 ≤ 0.55N5. For example, N6 can be 0.45N5, 0.46N5, 0.47N5, 0.48N5, 0.49N5, 0.50N5, 0.51N5, 0.52N5, 0.53N5, 0.54N5, or 0.55N5, or any two of the above numbers. The molar amount of sulfuric acid is expressed as the molar amount of "H2SO4".

[0134] Example

[0135] The embodiments and comparative examples provided below illustrate the implementation of this application in more detail. Various tests and evaluations were conducted according to the methods described below. Furthermore, unless otherwise specified, "parts" and "%" are quality standards.

[0136] Test methods and equipment:

[0137] Purity test:

[0138] Cathode products: Digested with acid and then analyzed by ICP. Inductively coupled plasma mass spectrometry (ICP-MS) was used for analysis. When the purity of the cathode products is greater than or equal to 99%, it is recorded as "greater than 99%".

[0139] Calculation of elution rate:

[0140] The Li content in the cathode powder and the Li content in the washed solid filter media were determined by ICP. The Li elution rate was calculated as (1 - Li content in the washed solid filter media / Li content in the cathode powder) × 100%.

[0141] The elution rates of other elements can be calculated similarly.

[0142] X-ray diffraction (XRD) test:

[0143] The calcined material was tested using an X-ray diffractometer to obtain XRD patterns. The XRD tests were conducted using a Rigaku Uitima IV X-ray diffractometer (Japan), with a copper target and Kα rays as the testing conditions.

[0144] Preparation of positive electrode powder:

[0145] Used ternary 811 lithium-ion batteries (LiNi) 0.8 Co 0.1 Mn 0.1 The O2) is disassembled, and the resulting positive electrode material is crushed and sieved to obtain positive electrode material layer powder. The positive electrode material layer powder is pretreated in a rotary kiln at T4 = 550℃ by introducing air to remove residual conductive agent and binder. The pretreatment time is t4 = 2h. Then, it is passed through a 150-mesh sieve to obtain positive electrode powder. The lithium content in the positive electrode powder is 7.2% by mass.

[0146] Unless otherwise specified, the following examples and comparative examples all use the positive electrode powder prepared as described above.

[0147] Example 1 (Method 3)

[0148] 10g of the prepared cathode powder was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started, with a CO flow rate of V = 2L / min. The tube furnace temperature was set at T1 = 700℃, and the heating duration was t1 = 90min (1.5h). After cooling, the calcined material was removed and washed with water at a solid-liquid ratio of 1:50, using 500ml of water for 1h. After each wash, the material was filtered, and the solid-liquid ratio was repeated for three washes. The pH of the solution was measured, and the washing was completed when the pH reached 7. The filtered material contained solid filter media and lithium-containing filtrate. The solid filter media contained Me and MeO (mainly including Ni, Co, and MnO) as well as Li2CO3. The ICP data of the obtained solid filter media are shown in Table 1. Table 1 shows that the elution rate of Li is approximately 85%. The lithium-containing filtrate after washing was evaporated to obtain solid Li2CO3.

[0149] The XRD pattern of the calcined material is attached. Figure 2 As can be seen from the figure, there are characteristic peaks of MnO, Co, Ni and Li2CO3, indicating that the nickel, cobalt and manganese metals are reduced relatively thoroughly, that is, reduced to low-valence metals that are easily soluble in acid, which facilitates subsequent dissolution and electrolysis reactions.

[0150] The solid filter media was acid-dissolved using 10 ml of 4.8 mol / L sulfuric acid. Water was added to prepare a slurry with a solid content of W = 10 g / L and a pH of approximately 5.2. This slurry, obtained after partial acid dissolution of the solid filter media, was then fed into an electrolytic cell for electrolysis. A 316 stainless steel plate was used as the cathode, and a lead-silver alloy plate as the anode. The electrolysis temperature was controlled at T3 = 70℃, and a voltage of 3.5V was used for nickel-cobalt electrolysis. The pH of the slurry was controlled at 4 during the electrolysis process. For every 1 Ah of electrolysis (approximately 1.069 g of nickel-cobalt cathode product), 1.33 g of washed solid filter media (with a nickel-cobalt mass fraction of approximately 78% and a lithium mass percentage of 1.4%) needs to be added, along with 0.27 ml of sulfuric acid (4.8 mol / L). After 24 hours of electrolysis, feeding is stopped. The cathode product is a high-purity nickel-cobalt alloy, and the anode product is MnO2. Electrolysis is stopped when the total concentration of nickel-cobalt ions in this embodiment decreases to 0.05 wt%. The purity of the nickel-cobalt alloy produced by electrolysis reaches over 99%.

[0151] Table 1

[0152]

[0153] Example 2 (Method 1)

[0154] 10g of the prepared positive electrode powder was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started, with a CO flow rate of V = 2.5 L / min. The tube furnace temperature was set at T1 = 650℃, and the heating duration was t1 = 120 min (2 h). After cooling, the powder was removed and washed with water at a solid-liquid ratio of 1:80, using 800 ml of water for 1 h. After each wash, the powder was filtered, and then washed again with water at a solid-liquid ratio of 1:80. After three washes, the pH of the solution was measured. The washing was completed when the pH reached 7, yielding a solid filter material and a lithium-containing filtrate. The solid filter material contained Me and MeO (mainly including Ni, Co, and MnO) as well as Li2CO3. The elution rate of Li was 88%. The washed lithium solution was then evaporated to obtain solid Li2CO3.

[0155] The solid filter media was acid-dissolved using 8 ml of 4.8 mol / L sulfuric acid. Water was added to prepare a slurry with a solid content of W = 15 g / L and a pH of approximately 5.3. The slurry (volume V = 500 ml) obtained after partial acid dissolution of the solid filter media was fed into an electrolytic cell for electrolysis. A 316 stainless steel plate was used as the cathode and a lead-silver alloy plate was used as the anode. The electrolysis temperature was controlled at T3 = 70℃, and a voltage of 3.5V was used for nickel-cobalt electrolysis. The pH of the slurry was controlled at 4. During the electrolysis process, every 1 Ah of electrolysis (approximately 1.069 g of nickel-cobalt cathode products) required the addition of 1.33 g of washed solid filter media (with a nickel-cobalt mass fraction of approximately 80% and a lithium mass percentage of 1.5%), along with 0.28 ml of sulfuric acid (concentration 4.8 mol / L). After continuous electrolysis for a period of time, the cathode product is a high-purity nickel-cobalt alloy with a purity of over 99%, and the anode product is MnO2. After the lithium sulfate concentration in the electrolytic slurry is reduced to 250 g / L, 50 ml of the electrolytic slurry is discharged, and 30 wt% of water is evaporated for concentration and crystallization. After filtration, solid lithium sulfate and mother liquor are obtained. The mother liquor is returned to the slurry to maintain ion balance and allow electrolysis to continue without stopping.

[0156] The theoretical saturation concentration of lithium sulfate in the electrolytically treated slurry is calculated as 340 g / L.

[0157] Example 3 (Method 2)

[0158] 20g of the prepared positive electrode powder was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started, with a CO flow rate of V = 1 L / min. The tube furnace temperature was set at T1 = 600℃, and the heating duration was t1 = 150 min (2.5 h). After cooling, the powder was removed and washed with water at a solid-liquid ratio of 1:50, using 1000 ml of water for 1 h. After each wash, the powder was filtered, and then washed again with water at a solid-liquid ratio of 1:50. After three washes, the pH of the solution was measured. The washing was completed when the pH reached 7, yielding a solid filter material and a lithium-containing filtrate. The solid filter material contained Me and MeO (mainly including Ni, Co, and MnO) as well as Li2CO3. The elution rate of Li was 90%. The washed lithium solution was then evaporated to obtain solid Li2CO3.

[0159] Solid filter media was acid-dissolved using 17 ml of 4.8 mol / L sulfuric acid. Water was added to prepare a slurry with a solid content of W = 13 g / L and a pH of approximately 5.3. This slurry, obtained after partial acid dissolution of the solid filter media, was then fed into an electrolytic cell for electrolysis. A 316 stainless steel plate was used as the cathode, and a lead-silver alloy plate as the anode. The electrolysis temperature was controlled at T3 = 70℃, and a voltage of 3.5V was used for nickel-cobalt electrolysis. The pH of the slurry was controlled at 4. During electrolysis, for every 1 Ah (approximately 1.069 g of nickel-cobalt produced at the cathode), 1.28 g of washed solid filter media (approximately 81% nickel-cobalt mass fraction and 1.6% lithium mass percentage) was added, along with 0.3 ml of 4.8 mol / L sulfuric acid. The cathode product was a high-purity nickel-cobalt alloy with a purity exceeding 99%, and the anode product was MnO2. Electrolysis is stopped once the lithium sulfate concentration in the slurry reaches 320 g / L. The slurry after electrolysis is stopped can be completely discharged, evaporated, concentrated, and crystallized to obtain lithium sulfate and mother liquor. The mother liquor can be reused for the next electrolysis.

[0160] The theoretical saturation concentration of lithium sulfate in the electrolytically treated slurry is calculated as 340 g / L.

[0161] Example 4 (Method Four)

[0162] 10g of the prepared positive electrode powder was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started, with a CO flow rate of V = 2 L / min. The tube furnace temperature was set at T1 = 700℃, and the heating duration was t1 = 90 min (1.5 h). After cooling, the powder was removed and washed with water at a solid-liquid ratio of 1:50, using 500 ml of water for 1 h. After each wash, the powder was filtered, and the solid-liquid ratio was repeated at 1:50. After three washes, the pH of the solution was measured. The washing was completed when the pH reached 7, yielding a solid filter material and a lithium-containing filtrate containing Me and MeO (mainly including Ni, Co, and MnO), as well as Li2CO3. The elution rate of Li was 85%. The washed lithium solution was then evaporated to obtain solid Li2CO3.

[0163] Solid filter media was acid-dissolved using 10 ml of 4.8 mol / L sulfuric acid. Water was added to prepare a slurry with a solid content of W = 10 g / L and a pH of approximately 5.2. This slurry, obtained after partial acid dissolution of the solid filter media, was then fed into an electrolytic cell for electrolysis. A 316 stainless steel plate was used as the cathode, and a lead-silver alloy plate as the anode. The electrolysis temperature was controlled at T3 = 70℃, and a voltage of 3.5V was used for nickel-cobalt electrolysis. The pH of the slurry was controlled at 4. During electrolysis, for every 1 Ah (approximately 1.069 g of nickel-cobalt produced at the cathode), 1.33 g of washed solid filter media (with a nickel-cobalt mass fraction of approximately 78%) needed to be added. The cathode product was a high-purity nickel-cobalt alloy, and the anode product was MnO2. As the reaction proceeded, the sulfuric acid was gradually converted to Li... + Electrolysis is stopped when the pH of the electrolyzed slurry reaches 6.5. The purity of the nickel-cobalt alloy produced by electrolysis reaches over 99%.

[0164] Example 5

[0165] 10g of the prepared cathode powder was mixed with 1g of carbon powder and placed in a quartz boat, which was then placed in a tube furnace. N2 was first introduced for a period of time until all other gases in the tube were exhausted. Heating was then initiated, with N2 continuously introduced throughout the process. The tube furnace temperature was set at T1 = 700℃, and the heating duration was t1 = 90 min (1.5 h). After cooling, the calcined material was removed and washed with water at a solid-liquid ratio of 1:50, using 500 ml of water for 1 h. After each wash, the material was filtered, and the solid-liquid ratio was repeated at 1:50. After three washes, the pH of the solution was measured. Washing was completed when the pH reached 7. Filtration yielded a solid filter media and a lithium-containing filtrate. The solid filter media contained Me and MeO (mainly including Ni, Co, and MnO) as well as Li₂CO₃. ICP testing of the solid filter media showed a Li elution rate of 86%. The washed lithium solution was then evaporated to obtain solid Li₂CO₃.

[0166] The XRD pattern of the calcined material was similar to that in Example 1, with characteristic peaks of MnO, Co, Ni, and Li2CO3, indicating that nickel, cobalt, and manganese metals can also be reduced using carbon powder, which facilitates subsequent dissolution and electrolysis reactions.

[0167] The subsequent acid dissolution and electrolysis processes are the same as in Example 1, and the purity of the nickel-cobalt alloy produced by electrolysis reaches over 99%.

[0168] Comparative Example 1

[0169] 10g of the prepared cathode powder was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started, with a CO flow rate of V = 2 L / min. The tube furnace temperature was set at T1 = 500℃, and the heating duration was t1 = 90 min. After cooling, the calcined material was removed and washed with water, the same as in Example 1. The elution rate of Li in the lithium-containing filtrate obtained after washing was 22%. The solid filter material obtained after washing was prepared into a slurry using sulfuric acid. It was found that most of the solids could not be dissolved by the acid and could not effectively carry out the electrolytic reaction.

[0170] Compared with Example 1, Comparative Example 1 shows that when the reduction temperature T1 is too low, the reduction of the cathode powder is incomplete, and the lithium element cannot be effectively separated from the cathode powder, resulting in a low lithium recovery rate and the inability to effectively carry out subsequent dissolution and electrolysis reactions.

[0171] Comparative Example 2

[0172] 10g of the prepared cathode powder was placed in a quartz boat and then placed in a tube furnace. CO gas was first introduced for a period of time until other gases in the tube were purged. Then heating was started, with a CO flow rate of V = 2 L / min. The tube furnace temperature was set at T1 = 800℃, and the heating duration was t1 = 90 min. After cooling, the calcined material was removed and washed with water, the same as in Example 1. The elution rate of Li in the lithium-containing filtrate obtained after washing was 45%, indicating that most of the Li volatilized due to the high temperature.

[0173] The subsequent acid dissolution and electrolysis processes are the same as in Example 1.

[0174] Compared with Example 1, Comparative Example 2 shows that when the reduction temperature T1 is too high, lithium volatilizes, reducing the lithium recovery rate. However, the resulting solid filter material has a high degree of reduction and can undergo subsequent dissolution and electrolysis reactions.

[0175] Comparative Example 3

[0176] Except for the following parameters which differ from those in Example 1, all other parameters are the same as in Example 1:

[0177] Acid dissolution was performed using 25 ml of 4.8 mol / L sulfuric acid, followed by the addition of approximately 100 ml of water to prepare a slurry with a solid content of W = 0.1 g / L and a pH of approximately 2.

[0178] At the start of electrolysis, bubbles were observed to form on the cathode plate, and gradually, obvious bubbles appeared on the cathode plate. This was because there was too little positive electrode powder and too much acid in the slurry, which could not neutralize the sulfuric acid produced by electrolysis, preventing the electrolysis from proceeding normally and resulting in the production of hydrogen gas.

[0179] From Examples 1 to 5, and Comparative Examples 1 to 2, when the recovery method provided in this application is used, the elution rate of Li in the lithium-containing filtrate is higher than that of the comparative examples. Furthermore, since sulfuric acid is generated during the electrolysis process, the consumption of sulfuric acid is significantly reduced compared to traditional processes, resulting in high economic benefits from the recovery. In addition, by controlling the heat treatment temperature within the range specified in this application, the elution rate of Li can reach 85%, achieving full recovery of lithium.

[0180] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, or article that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, or article.

[0181] The above description is only a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the scope of protection of this application.

Claims

1. A method for recycling the positive electrode of a waste battery, comprising the following steps: (1) Obtain the positive electrode of the waste battery, and pre-treat the positive electrode to obtain positive electrode powder; (2) The positive electrode powder and the reducing agent are heat-treated at a temperature T1 of 550°C to 700°C, then washed with water and filtered to obtain solid filter material and lithium-containing filtrate; the reducing agent is selected from at least one of carbon monoxide and carbon powder; The solid filter media includes elemental Me, oxide MeO, and Li2CO3, wherein Me is selected from at least one of the elements Ni, Co, and Mn; (3) The solid filter material is mixed with sulfuric acid to undergo a dissolution reaction to obtain a slurry. The slurry contains a solid phase and a liquid phase. The solid phase includes the solid filter material that has not undergone the dissolution reaction. (4) Electrolyze the slurry to obtain an anode product, a cathode product and an electrolyzed slurry, wherein the cathode product includes nickel and / or cobalt.

2. The recycling method according to claim 1, wherein, In step (2), the reducing agent is selected from carbon monoxide, and the flow rate of carbon monoxide introduced per 10g of positive electrode powder is 1L / min to 3L / min; or, the reducing agent is selected from carbon powder, and the mass ratio of positive electrode powder to carbon powder is 100:(8 to 15). Preferably, in step (2), the heat treatment time t1 is 1 hour to 3 hours; Preferably, in step (2), the water washing satisfies at least one of the following conditions: Condition a: The solid-liquid ratio of the water washing is 1:(10 to 100), wherein the unit of solid in the water washing is g and the unit of liquid is ml; Condition b: The washing process is completed when the pH of the washing solution after the water washing is 7 to 8; Preferably, in step (2), the lithium elution rate of the lithium-containing filtrate is 85% to 90%.

3. The recycling method according to claim 1, wherein, In step (3), the solid content W1 of the slurry is 1 g / L to 50 g / L, and the pH is 3 to 6.5; Preferably, in step (3), the temperature T2 of the dissolution reaction is 50°C to 80°C and the time t2 is 0.5h to 2h; Preferably, in step (3), the number of moles of sulfuric acid is N1, the total number of moles of nickel, cobalt and manganese in the liquid phase is N2, and the number of moles of lithium in the liquid phase is N7, satisfying 0.9╳(N2+0.5N7)≤N1≤1.1╳(N2+0.5N7), wherein the number of moles of sulfuric acid is calculated as the number of moles of "H2SO4".

4. The recycling method according to claim 1, wherein, In step (4), the pH of the electrolytic treatment is 3 to 5, the temperature T3 is 30°C to 80°C, and the voltage is 2.5V to 4.5V; Preferably, in step (4), at least the solid filter material is added to the slurry during the electrolysis process; More preferably, the solid filter media is added to the slurry to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 3 to 6.5; or, The solid filter media and sulfuric acid are added to the slurry to maintain the solid content W2 of the slurry in the range of 1 g / L to 50 g / L and the pH of the slurry in the range of 3 to 5.

5. The recycling method according to claim 4, wherein, When the mass of nickel and / or cobalt added to the cathode product is m1, the solid filter material is added, or the solid filter material and sulfuric acid are added. Where m1 ≤ 0.1m0; Preferably, 0.0001m0 ≤ m1 ≤ 0.1m0; m0 is the sum of the mass of nickel and / or cobalt in the solid filter material added during the preparation of the slurry in step (3).

6. The recycling method according to claim 5, wherein, The total molar amount of nickel and / or cobalt added to the cathode product is N3, and the total molar amount of nickel and / or cobalt added to the solid filter material is N4, where 0.95N3≤N4≤1.05N3.

7. The recycling method according to claim 6, wherein, The number of moles of lithium in the added solid filter material is N5, and the number of moles of added sulfuric acid is N6, where 0.45N5≤N6≤0.55N5; The number of moles of sulfuric acid is expressed as the number of moles of "H2SO4".

8. The recycling method according to claim 4, wherein, Step (4) includes any of the following methods: Method 1: Continuously add the solid filter material and sulfuric acid to the slurry. When the first preset condition is reached, discharge part of the electrolytically treated slurry and purify the lithium element in the electrolytically treated slurry to obtain mother liquor. Return the mother liquor to the slurry in step (4) to continue the electrolytic treatment, so that the electrolytic treatment continues without stopping. Method 2: Add the solid filter material and sulfuric acid to the slurry, and stop the electrolysis process when the second preset condition is reached; Method 3: Add the solid filter material and sulfuric acid to the slurry. After a period of time, stop feeding. Stop the electrolysis process when the third preset condition is reached. Method 4: Add the solid filter material to the slurry, and stop the electrolysis process when the fourth preset condition is reached.

9. The recycling method according to claim 8, wherein, In the first method, the first preset condition is that the actual concentration C1 of lithium salt in the electrolyzed slurry satisfies 0.7C2≤C1<C2, wherein the theoretical saturation concentration of lithium salt in the electrolyzed slurry is C2. Preferably, the volume of the slurry is V, and the volume of the electrolyzed slurry discharged each time is V', where V' ≤ 0.2V; Preferably, after the discharged electrolytically treated slurry is filtered to obtain filter residue and filtrate, the lithium element in the filtrate is purified to obtain lithium salt and mother liquor, and the mother liquor is returned to the slurry in step (4) to continue the electrolytic treatment, wherein the purification treatment includes evaporation, concentration and crystallization or carbonization deposition.

10. The recycling method according to claim 8, wherein, In the second method, the second preset condition is the actual concentration C1 of lithium salt in the electrolyzed slurry, which satisfies 0.9C2≤C1<C2, wherein the theoretical saturation concentration of lithium salt in the electrolyzed slurry is C2.

11. The recycling method according to claim 8, wherein, In the third method, the third preset condition is any one of the following conditions: (1) The pH of the electrolyzed slurry is less than or equal to 3; (2) The total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%; (3) The current density during the electrolysis process is less than or equal to 8 mA / cm². 2 .

12. The recycling method according to claim 8, wherein, In the fourth method, the fourth preset condition is any one of the following conditions: (4) The pH of the electrolyzed slurry is greater than or equal to 6.5; (5) The total mass concentration of nickel ions and / or cobalt ions in the electrolyzed slurry is less than or equal to 0.05%; (6) The current density during the electrolysis process is less than or equal to 8 mA / cm². 2 .

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