A method for recovering multiple metals from spent lithium batteries

Abstract

The application discloses a method for recovering multiple metals from waste lithium batteries, comprising the following steps: S1. mixing waste lithium battery black powder with a magnesium-containing chlorinating agent, and performing roasting treatment to obtain a roasting product; S2. mixing the roasting product with a weak alkaline leaching agent, and performing leaching treatment, and after filtration, a lithium-containing solution and a filter residue are obtained; S3. adding an ammonia-carbonate-sulfite composite leaching agent to the filter residue to perform ammonia leaching treatment, and after filtration, a nickel-cobalt-rich ammonia complex leaching solution and a manganese-rich solid residue are obtained; S4. sequentially performing heating and extraction treatment on the nickel-cobalt-rich ammonia complex leaching solution, and nickel sulfate and cobalt sulfate are obtained; performing dissolution and precipitation treatment on the manganese-rich solid residue, and a manganese salt is obtained; through the synergistic coupling of magnesium chloride roasting and composite ammonia leaching, lithium is preferentially extracted, and the pre-activation of transition metal phases is realized, so that the inherent contradiction that lithium efficient extraction and nickel-cobalt efficient leaching cannot be achieved simultaneously in the existing process is successfully resolved.

Description

Technical Field

[0001] This invention relates to the field of battery recycling technology, and in particular to a method for recovering multiple metals from waste lithium batteries. Background Technology

[0002] With the rapid development of the new energy vehicle industry and the arrival of the retirement wave of power batteries, the efficient recovery of valuable metals such as lithium, nickel, cobalt, and manganese from the cathode materials of spent lithium-ion batteries has become a research hotspot in the field of resource recycling. Currently, combined processes are widely used due to their combination of the high efficiency of pyrometallurgical processes and the selectivity of hydrometallurgical processes. For example, using carbonaceous materials as a reducing agent for reduction roasting followed by water leaching to extract lithium, and then using ammonia leaching of the water leaching residue to recover nickel and cobalt, can achieve preferential separation of lithium and selective dissolution of nickel and cobalt. This technical route is considered one of the most promising recycling solutions for industrialization.

[0003] However, this type of combined process has long been plagued by an irreconcilable contradiction: in order to achieve a high lithium leaching rate in the water leaching stage, conventional reduction roasting (such as carbothermal reduction) reduces nickel and cobalt to elemental metals or low-activity oxides. These phases have extremely low reactivity in the subsequent ammonia leaching process, and high concentrations of reducing agents and long leaching times are required to achieve efficient dissolution of nickel and cobalt. Conversely, if the roasting reduction intensity is reduced to accommodate ammonia leaching, the lithium water leaching rate will drop significantly to about 80%, making it difficult to achieve high recovery rates for both lithium and transition metals at the same time. This has become the core bottleneck restricting the further industrialization of this type of process.

[0004] Therefore, how to achieve efficient lithium leaching during the roasting stage of lithium-preferred extraction and subsequent ammonia leaching without harsh conditions, while not affecting the lithium leaching efficiency, remains an unsolved technical problem. Summary of the Invention

[0005] In view of this, this application provides a method for recovering multiple metals from waste lithium batteries, which solves the problem of how to efficiently recover lithium, cobalt and nickel from waste lithium batteries at the same time.

[0006] To achieve the above technical objectives, this application adopts the following technical solution: In a first aspect, this application provides a method for recovering multiple metals from spent lithium batteries, comprising the following steps: S1. Mix waste lithium battery black powder with a magnesium-containing chlorinating agent and calcine it to obtain the calcined product; S2. The roasted product is mixed with a weakly alkaline leaching agent, leached, filtered, and a lithium-containing solution and filter residue are obtained. S3. Add an ammonia-carbonate-sulfite composite leaching agent to the filter residue for ammonia leaching treatment. After filtration, a nickel-cobalt-ammonia complex leaching solution and a manganese-rich solid residue are obtained. S4. The nickel-cobalt-ammonia complex leachate is subjected to heating and extraction treatment in sequence to obtain nickel sulfate and cobalt sulfate; the manganese-rich solid residue is dissolved and precipitated to obtain manganese salt.

[0007] Preferably, the magnesium-containing chlorinating agent includes one or more of magnesium chloride hexahydrate and basic magnesium chloride; the mass ratio of the waste lithium battery black powder to the magnesium-containing chlorinating agent is 1:03-0.8.

[0008] Preferably, in step S1, the calcination temperature is 450-550℃, the calcination time is 30-120 min, and the calcination atmosphere is an oxygen-containing atmosphere.

[0009] Preferably, in step S2, the weakly alkaline leaching agent includes one or more of dilute ammonia water and sodium carbonate solution.

[0010] Preferably, in step S2, the leaching temperature is 20-60℃ and the time is 0.5-2h; the solid-liquid ratio of the leaching treatment is 1:5-20.

[0011] Preferably, in step S3, the ammonia-carbonate-sulfite composite leaching agent comprises the following components in parts by mass: 1-5 parts ammonia water, 0.5-2 parts ammonium carbonate, and 0.2-1 parts ammonium sulfite.

[0012] Preferably, in step S3, the ammonia leaching treatment is carried out at a temperature of 50-90°C for a time of 0.5-2 hours.

[0013] Preferably, in step S4, the nickel-cobalt-ammonia complex leaching solution is heated to boiling to obtain a precipitate; the precipitate is dissolved with acid and then extracted with an extractant to obtain nickel sulfate and cobalt sulfate.

[0014] Preferably, in step S4, after dissolving the manganese-rich solid residue with acid, sodium carbonate and / or sodium oxalate are added to obtain manganese carbonate and / or manganese oxalate.

[0015] Preferably, the waste lithium batteries include one or more of the following: ternary lithium-ion batteries, lithium cobalt oxide batteries, lithium manganese oxide batteries, and lithium iron phosphate batteries.

[0016] The beneficial effects of this application are as follows: This application achieves the pre-activation of transition metal phases while preferentially extracting lithium through the synergistic coupling of magnesium chloride roasting and composite ammonia leaching, thus successfully resolving the inherent contradiction in existing processes where it is difficult to achieve both efficient lithium extraction and efficient nickel-cobalt leaching. This method does not require a strong reducing roasting atmosphere or excessive reducing agent, and achieves highly selective separation and high-yield recovery of lithium, nickel, cobalt and manganese. Detailed Implementation

[0017] The embodiments of the technical solution of this application will be described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0018] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0019] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0020] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0021] Unless otherwise explicitly defined and specified herein, all technical and scientific terms used in this application shall have the generally accepted meanings understood by one of ordinary skill in the field of chemical and chemical materials technology (including but not limited to polymer chemistry, inorganic chemistry, organic synthesis, catalysis chemistry, materials processing, and chemical unit operations) based on their professional knowledge and conventional practice. The use of any terminology herein is intended to describe the specific embodiments of this application in the clearest and most accurate manner, so as to fully disclose the technical solution. Such use shall not in any way be construed as a limitation on the scope of the claims, nor does it imply the exclusion of equivalent technical solutions that could be reasonably known by one of skill in the art based on the concept of this application.

[0022] The terms "comprising," "including," "having," "containing," and any grammatical variations or similar expressions used in the specification and claims of this application are all open-ended and non-exhaustive descriptive terms. Their purpose is to explicitly describe the existence of the stated technical features, components, steps, or parts, while explicitly allowing and covering the possibility that other features, components, steps, parts, or any combinations thereof not explicitly listed may exist or be added to the technical solution, as long as such additions do not destroy the integrity and inventiveness of the original technical solution.

[0023] When the terms "embodiments," "some embodiments," or "specific embodiments" are mentioned in the specification, they refer to examples that, in conjunction with the specific parameters, materials, steps, and results described in that section, constitute one or a group of examples for implementing the technical solutions of this application. These embodiments are used for full disclosure and illustrative purposes, not for exhaustive enumeration. Those skilled in the art should understand that, without departing from the overall inventive concept of this application, the various technical features disclosed in different embodiments can be combined, substituted, modified, or deleted to form other implementation methods that are not listed one by one in the specification but also fall within the protection scope of this application.

[0024] Unless otherwise expressly specified and limited, all terms related to chemical process operations, material preparation, processing and analytical testing involved in this application shall be interpreted in the broadest sense based on the conventional understanding of those skilled in the art.

[0025] Regarding performance testing and structural characterization, all testing and characterization methods involved in this application, unless otherwise specified, refer to conventional methods known in the art. Specific testing conditions may be selected and adjusted according to the sample properties and relevant national standards, international standards, or industry-standard methods. Test items may include mechanical properties (such as tensile, bending, and impact strength), thermal properties (such as DSC and TGA analysis), and chemical stability (such as solvent resistance and acid / alkali corrosion resistance). Structural characterization methods may include FT-IR, NMR, XRD, SEM, TEM, and BET. All test results should be understood to be within the allowable range of conventional experimental errors.

[0026] Regarding numerical values ​​and ranges, all parameter ranges expressed in this application in the form of "from a certain value to a certain value" should be understood as explicitly disclosing the endpoints of the range, each specific numerical point between the endpoints, and all sub-ranges formed by any two numerical points within the range. For example, "30℃ to 80℃" discloses 30, 31, ..., 80℃, as well as sub-ranges such as 30-50℃, 45-70℃, etc. When a numerical value is preceded by "about," "approximately," or similar words, it indicates that the numerical value is allowed to have reasonable errors recognized in the art under the measurement or control conditions, which can generally be understood as the deviation allowed by relevant standards or a normal fluctuation range of ±5% or ±10%.

[0027] The recovery of lithium, nickel, cobalt, and manganese from spent lithium-ion battery cathode materials typically employs a combined process of roasting, water leaching for preferential lithium extraction, and ammonia leaching for selective nickel and cobalt recovery. However, this process suffers from a long-standing inherent contradiction: to achieve a high lithium leaching rate in the water leaching stage, conventional reduction roasting (such as carbothermic reduction) reduces nickel and cobalt to elemental metals or low-activity oxides (Ni, Co, NiO, CoO, etc.). These phases exhibit extremely low reactivity in the subsequent ammonia leaching process, requiring high concentrations of reducing agents and long leaching times to achieve efficient dissolution of nickel and cobalt. Conversely, if the roasting reduction intensity is reduced to accommodate ammonia leaching, the lithium leaching rate drops significantly to around 80%. This seesaw effect—where optimization of one aspect inevitably comes at the expense of deterioration of the other—is the core bottleneck hindering the industrialization of this type of process. Although some existing technologies have attempted to introduce magnesium chloride as a roasting aid, its function is limited to promoting the chlorination extraction of lithium. It has not realized that the regulatory effect of magnesium chloride on the transition metal phase can serve the subsequent ammonia leaching across stages, nor has it proposed a design idea to synergistically couple the two separation steps.

[0028] The challenge lies in simultaneously achieving two objectives during the lithium-preferential extraction roasting stage without relying on strong reducing conditions: firstly, efficiently converting lithium into a water-soluble phase (such as LiCl); and secondly, transforming the phases of nickel and cobalt from dense, inert oxides into highly reactive forms, without affecting lithium leaching efficiency or introducing difficult-to-separate impurities. This requires the roasting additives and their reaction pathways to be selective, acting on lithium while embedding into the transition metal lattice in a specific manner without rendering it insoluble. Furthermore, the design of the subsequent ammonia leaching system needs to precisely match the characteristics of this pre-activated phase, enabling nickel and cobalt to efficiently complex and dissolve without strong reducing agents or under extreme conditions, while manganese is retained in the residue due to differences in solubility and the synergistic precipitation effect of carbonate and sulfite ions.

[0029] This application provides a method for recovering multiple metals from spent lithium batteries, including the following steps: S1. Mix waste lithium battery black powder with a magnesium-containing chlorinating agent and calcine it to obtain the calcined product; S2. The roasted product is mixed with a weakly alkaline leaching agent, leached, filtered, and a lithium-containing solution and filter residue are obtained. S3. Add an ammonia-carbonate-sulfite composite leaching agent to the filter residue for ammonia leaching treatment. After filtration, a nickel-cobalt-ammonia complex leaching solution and a manganese-rich solid residue are obtained. S4. The nickel-cobalt-ammonia complex leachate is subjected to heating and extraction treatment in sequence to obtain nickel sulfate and cobalt sulfate; the manganese-rich solid residue is dissolved and precipitated to obtain manganese salt.

[0030] In this application, in step S1, the magnesium-containing chlorinating agent undergoes thermal decomposition during calcination in an oxygen-containing atmosphere, releasing HCl gas. HCl preferentially reacts with lithium in the cathode material to form LiCl, while Mg... 2+ Gradually, it enters the oxide lattice of transition metals (Ni, Co, Mn), forming a Mg-doped solid solution phase (Mg-Me-O). This process achieves a dual function: on the one hand, the generated LiCl is readily soluble in the weakly alkaline leaching agent in step S2, increasing the lithium leaching rate, while the compounds of Ni, Co, and Mn, due to their extremely low solubility under these conditions, are almost completely retained in the filter residue, thus achieving efficient separation of lithium from transition metals; on the other hand, Mg... 2+ The doping of Ni causes lattice distortion in transition metal oxides, refines grains, and significantly increases specific surface area. This pre-activation effect lays the phase foundation for efficient ammonia leaching in step S3. In step S3, NH3 in the ammonia-carbonate-sulfite composite leaching agent reacts with Ni... 2+ Co 2+ To form a stable [Ni(NH3)] n ] 2+ and [Co(NH3)] n ] 2+ Complex ions allow them to selectively enter the liquid phase; while Mn 2+ In this alkaline system, the solubility is low, and the synergistic effect of carbonate and sulfite promotes the formation of MnCO3 or (NH4)2Mn(SO3)2 precipitates, which are retained in the residue. Since step S1 has transformed the phases of Ni and Co from inert oxides to solid solutions with abundant defects and active sites through Mg doping, efficient leaching of Ni and Co can be achieved in step S3 without high concentrations of reducing agents or extreme conditions, while the leaching rate of Mn is low. Step S4 recovers high-purity products from the nickel-cobalt-rich solution and the manganese-rich residue, respectively. The above steps are not isolated operations, but utilize the core mechanism of Mg doping pre-activation. The magnesium chloride in S1 serves both the preferential lithium extraction in S2 and provides activation residue for the efficient ammonia leaching of nickel and cobalt in S3, thus resolving the inherent contradiction in the recycling of waste lithium battery cathode materials where efficient preferential lithium extraction and efficient selective separation of nickel, cobalt, and manganese are difficult to achieve simultaneously.

[0031] In some embodiments, the magnesium-containing chlorinating agent includes one or more of magnesium chloride hexahydrate and basic magnesium chloride; the mass ratio of the waste lithium battery black powder to the magnesium-containing chlorinating agent is 1:03-0.8.

[0032] In this embodiment, magnesium chloride hexahydrate (MgCl₂) 2•6H2O) hydrolyzes stepwise during calcination, releasing HCl and H2O, and begins to react with lithium at about 270℃; basic magnesium chloride (Mg(OH)Cl) has a slightly higher decomposition temperature and can also provide a chlorine source; in the mass ratio range of 1:0.3-0.8, the amount of Mg doping is sufficient to produce a significant lattice expansion and specific surface area increase effect, while avoiding the formation of insoluble magnesium impurity phases in the calcination product or increasing the impurity burden of subsequent processing due to excessive magnesium salt.

[0033] In some embodiments, in step S1, the calcination temperature is 450-550°C, the calcination time is 30-120 min, and the calcination atmosphere is an oxygen-containing atmosphere.

[0034] In this embodiment, within this temperature range, magnesium chloride hexahydrate fully decomposes and completes the formation of LiCl and the Mg doping reaction, while the transition metal oxide has not undergone excessive sintering or grain coarsening, maintaining high reactivity. Below 450°C, the chlorination reaction is incomplete, and the lithium leaching rate decreases. Above 550°C, on the one hand, some LiCl may volatilize and be lost, and on the other hand, the Mg-doped solid solution may undergo phase separation or transform into a more stable inert phase, reducing the pre-activation effect.

[0035] In some embodiments, in step S2, the weakly alkaline leaching agent includes one or more of dilute ammonia water and sodium carbonate solution.

[0036] In this embodiment, the weakly alkaline environment of dilute ammonia (pH=9-10) or 0.1-0.5 mol / L sodium carbonate solution can efficiently dissolve LiCl while avoiding the hydrolysis or dissolution of transition metals. Dilute ammonia has buffering capacity, which can maintain a stable leaching pH; sodium carbonate can inhibit the dissolution of transition metal carbonates through the common ion effect. If the leaching agent is too alkaline, trace amounts of aluminum or zinc impurities may dissolve, affecting the purity of the lithium product; if the alkalinity is insufficient, the lithium leaching rate will decrease.

[0037] In some embodiments, in step S2, the leaching temperature is 20-60°C and the time is 0.5-2h; the solid-liquid ratio of the leaching treatment is 1:5-20.

[0038] In some embodiments, in step S3, the ammonia-carbonate-sulfite composite leaching agent comprises the following components in parts by mass: 1-5 parts ammonia water, 0.5-2 parts ammonium carbonate, and 0.2-1 parts ammonium sulfite.

[0039] In this embodiment, ammonia provides the complexing ligand; ammonium carbonate provides carbonate ions, which react with Mn. 2+ It generates sparingly soluble MnCO3 and also acts as a pH buffer; ammonium sulfite provides SO3. 2- It has weak reducing properties, which can assist Ni / Co in reducing from a high oxidation state to a low oxidation state and promote complexation. Simultaneously, it reacts with Mn...2+ It can generate (NH4)2Mn(SO3)2 precipitate, which enhances the retention of manganese. The three work synergistically, resulting in high leaching rates of Ni and Co, and low leaching rate of Mn.

[0040] In some embodiments, in step S3, the temperature of the ammonia immersion treatment is 50-90°C, and the time is 0.5-2 hours.

[0041] In this embodiment, increasing the temperature can accelerate the Ni / Co ammonia complexation reaction kinetics and shorten the leaching time; however, excessively high temperatures (>90°C) can lead to increased NH3 volatilization and loss of leaching agent.

[0042] In some embodiments, in step S4, the nickel-cobalt-ammonia complex leaching solution is heated to boiling to obtain a precipitate; the precipitate is dissolved with acid and then extracted with an extractant to obtain nickel sulfate and cobalt sulfate.

[0043] In this embodiment, the nickel-cobalt-ammonia complex leaching solution is heated to boiling. After the ammonia gas escapes, nickel and cobalt co-precipitate in the form of basic carbonates or hydroxides. The precipitate is filtered and dissolved in dilute sulfuric acid (0.5-1.0 mol / L) to obtain a Ni-containing solution. 2+ Co 2+ The solution was prepared; then, a mixed extractant of P204 and Cyanex 272 (volume ratio 1-3:1) was used for extraction and separation at a pH of about 4-5. Co preferentially entered the organic phase, while Ni remained in the aqueous phase. After back-extraction, nickel sulfate and cobalt sulfate were obtained by crystallization.

[0044] In some embodiments, in step S4, after dissolving the manganese-rich solid residue with acid, sodium carbonate and / or sodium oxalate are added to obtain manganese carbonate and / or manganese oxalate.

[0045] In this embodiment, the manganese-rich solid residue mainly contains MnCO3 and a small amount of (NH4)2Mn(SO3)2. It is dissolved in dilute sulfuric acid (0.5-1.0 mol / L), and after filtering to remove insoluble carbon residue, sodium carbonate is added to the filtrate to adjust the pH to about 7-8, and MnCO3 is precipitated. If it is necessary to prepare manganese oxalate, sodium oxalate is used instead of sodium carbonate.

[0046] In some embodiments, the waste lithium batteries include one or more of ternary lithium-ion batteries, lithium cobalt oxide batteries, lithium manganese oxide batteries, and lithium iron phosphate batteries.

[0047] The following specific embodiments further illustrate this solution. Example 1

[0048] A method for recovering multiple metals from spent lithium batteries includes the following steps: S1. Take 500 g of waste lithium battery cathode material black powder (ICP-OES analysis showed Li 3.42 wt%, Ni 16.3 wt%, Co 8.7 wt%, Mn 8.1 wt%), mix it with magnesium chloride hexahydrate at a mass ratio of 1:0.5, i.e., add 250 g of MgCl₂. 2• 6H2O, place both in a mortar and grind manually for 15 minutes until they are evenly mixed, transfer to a corundum crucible, place the crucible in a muffle furnace, heat to 500℃ at 5℃ / min in air atmosphere, keep warm and calcine for 80 minutes, and after calcine, cool naturally to room temperature to obtain a gray-black loose calcined product. S2. Transfer the calcined product to a 5 L beaker, add 2.5 L of 0.5 mol / L ammonia solution (solid-liquid ratio 1:5), and leach at 300 rpm for 30 minutes in a 40℃ water bath. After leaching, vacuum filter, collect the filtrate (containing lithium solution) and filter residue. Wash the filter residue twice with 500 mL of deionized water, combine the washing liquid with the filtrate, concentrate the lithium-containing filtrate, add saturated sodium carbonate solution, react at 90℃ for 2 hours, precipitate, filter, wash, and dry to obtain lithium carbonate product; S3. Prepare 2.0 L of composite leaching agent, with the following composition: 4.0 mol / L ammonia, 1.2 mol / L ammonium carbonate, and 0.5 mol / L ammonium sulfite. After mixing, adjust the pH to 10.5. Take 300 g of the dried filter residue obtained in step S2, add the composite leaching agent (solid-liquid ratio 1:6.7), transfer it to a 3 L three-necked flask equipped with a reflux condenser, and leach it in an oil bath at 80℃ with stirring at 400 rpm for 70 minutes. After leaching, cool and filter to obtain nickel-rich cobalt-ammonia complex leaching solution and manganese-rich solid residue. S4. Heat the nickel-cobalt-ammonia complex leaching solution to boiling, evaporate the ammonia for 40 minutes until no ammonia odor remains, and a blue-green precipitate will form. After filtration, dissolve the precipitate in 0.5 mol / L H2SO4 to obtain Ni-containing... 2+ Co 2+ The sulfate solution was extracted with a mixed extractant of P204 and Cyanex 272 (volume ratio 2:1, diluted with sulfonated kerosene to 40%) at an organic phase: aqueous phase ratio of 1:1 for 10 minutes. After phase separation, the aqueous phase was nickel-rich and the organic phase was loaded with cobalt. The organic phase was back-extracted with 0.5 mol / L H2SO4, and the back-extract was cobalt-rich. The nickel-rich and cobalt-rich solutions were concentrated and crystallized to obtain NiSO4•6H2O and CoSO4•7H2O, respectively. The manganese-rich solid residue was dissolved in 1 mol / L H2SO4 at 60℃ for 1 hour. After filtering to remove insoluble carbon residue, saturated sodium carbonate solution was slowly added to the filtrate until the pH reached 7.5, forming a light pink manganese carbonate precipitate. The precipitate was filtered, washed, and dried to obtain MnCO3. Example 2

[0049] A method for recovering multiple metals from waste lithium batteries is the same as in Example 1, except that the mass ratio of waste lithium battery black powder to magnesium chloride hexahydrate is changed to 1:0.3. Example 3

[0050] A method for recovering multiple metals from waste lithium batteries is the same as in Example 1, except that the calcination temperature in step S1 is 450°C. Example 4

[0051] A method for recovering multiple metals from waste lithium batteries is the same as in Example 1, except that in step S3, the concentration of the composite leaching agent ammonium sulfite is 0.2 mol / L.

[0052] Comparative Example 1 A method for recovering multiple metals from spent lithium batteries, otherwise identical to Example 1, except that MgCl₂ is not added. 2• 6H2O.

[0053] Comparative Example 2 A method for recovering multiple metals from waste lithium batteries is the same as in Example 1, except that ammonium sulfite is not added to the composite leaching agent.

[0054] Comparative Example 3 A method for recovering multiple metals from waste lithium batteries is the same as in Example 1, except that the composite leaching agent is replaced with ammonia.

[0055] Comparative Example 4 A method for recovering multiple metals from spent lithium batteries, otherwise identical to Example 1, except that MgCl₂ is used. 2• 6H2O was replaced with an equimolar amount of CaCl2 2• 6H2O.

[0056] Comparative Example 5 A method for recovering multiple metals from waste lithium batteries is the same as in Example 1, except that the 0.5 mol / L ammonia solution in step S2 is replaced with 0.5 mol / L dilute sulfuric acid.

[0057] Testing and Evaluation The recovery rate of the recovered metals obtained in each example and comparative example was determined by inductively coupled plasma optical emission spectrometry (ICP-OES); wherein, the overall recovery rate (%) = (mass of metal in the final product / total mass of the metal in the raw material black powder) × 100%, and the results are shown in Table 1.

[0058] Table 1 Test Results ; As shown in Table 1, under optimal conditions, Example 1 of this application achieves comprehensive recovery rates of 95.3%, 96.7%, 96.3%, and 94.8% for lithium, nickel, cobalt, and manganese, respectively. All four indicators are at high levels, achieving a balance between preferential lithium extraction and efficient recovery of nickel, cobalt, and manganese. In contrast, Comparative Example 1 shows a significant decrease in lithium, nickel, and cobalt recovery rates; the absence of ammonium sulfite or the use of only ammonia water results in a significant reduction in nickel and cobalt recovery rates or substantial manganese loss; the use of CaCl2 or acidic leaching also fails to achieve both high recovery rates for lithium and transition metals. The above comparisons fully demonstrate that this application, through the synergistic coupling of MgCl2 roasting and composite ammonia leaching, successfully overcomes the inherent contradiction in existing technologies where efficient lithium extraction and efficient nickel and cobalt leaching are difficult to achieve simultaneously, and significantly improves the comprehensive recovery efficiency of each metal.

[0059] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for recovering multiple metals from waste lithium batteries, characterized in that, Includes the following steps: S1. Mix waste lithium battery black powder with a magnesium-containing chlorinating agent and calcine it to obtain the calcined product; S2. The roasted product is mixed with a weakly alkaline leaching agent, leached, filtered, and a lithium-containing solution and filter residue are obtained. S3. Add an ammonia-carbonate-sulfite composite leaching agent to the filter residue for ammonia leaching treatment. After filtration, a nickel-cobalt-ammonia complex leaching solution and a manganese-rich solid residue are obtained. S4. The nickel-cobalt-ammonia complex leachate is subjected to heating and extraction treatment in sequence to obtain nickel sulfate and cobalt sulfate; the manganese-rich solid residue is dissolved and precipitated to obtain manganese salt.

2. The method for recovering multiple metals from spent lithium batteries according to claim 1, characterized in that, The magnesium-containing chlorinating agent includes one or more of magnesium chloride hexahydrate and basic magnesium chloride; the mass ratio of the waste lithium battery black powder to the magnesium-containing chlorinating agent is 1:03-0.

8.

3. The method for recovering multiple metals from waste lithium batteries according to claim 1, characterized in that, In step S1, the calcination temperature is 450-550℃, the calcination time is 30-120 min, and the calcination atmosphere is an oxygen-containing atmosphere.

4. The method for recovering multiple metals from spent lithium batteries according to claim 1, characterized in that, In step S2, the weakly alkaline leaching agent includes one or more of dilute ammonia water and sodium carbonate solution.

5. The method for recovering multiple metals from waste lithium batteries according to claim 1, characterized in that, In step S2, the leaching treatment temperature is 20-60℃ and the time is 0.5-2h; the solid-liquid ratio of the leaching treatment is 1:5-20.

6. The method for recovering multiple metals from spent lithium batteries according to claim 1, characterized in that, In step S3, the ammonia-carbonate-sulfite composite leaching agent comprises the following components in parts by mass: 1-5 parts ammonia water, 0.5-2 parts ammonium carbonate, and 0.2-1 parts ammonium sulfite.

7. The method for recovering multiple metals from spent lithium batteries according to claim 1, characterized in that, In step S3, the ammonia leaching treatment is carried out at a temperature of 50-90℃ for a time of 0.5-2 hours.

8. The method for recovering multiple metals from waste lithium batteries according to claim 1, characterized in that, In step S4, the nickel-cobalt-ammonia complex leaching solution is heated to boiling to obtain a precipitate; the precipitate is dissolved with acid and then extracted with an extractant to obtain nickel sulfate and cobalt sulfate.

9. The method for recovering multiple metals from spent lithium batteries according to claim 1, characterized in that, In step S4, after dissolving the manganese-rich solid residue with acid, sodium carbonate and / or sodium oxalate are added to obtain manganese carbonate and / or manganese oxalate.

10. The method for recovering multiple metals from spent lithium batteries according to claim 1, characterized in that, The waste lithium batteries include one or more of the following: ternary lithium-ion batteries, lithium cobalt oxide batteries, lithium manganese oxide batteries, and lithium iron phosphate batteries.