Lithium ion recovery method and system based on magnetic field coupling valuable metal leaching

Abstract

The invention discloses a lithium ion recovery method and system based on magnetic field coupling valuable metal leaching, and the method comprises the steps: S1, carrying out the pretreatment of a waste lithium ion battery, and obtaining a to-be-leached positive electrode material; s2, mixing the positive electrode material with a leaching solution containing an acidic medium and at least one reducing agent; and S3, in the leaching treatment process, an external magnetic field is applied to the reaction mixture. By introducing the magnetic field coupling technology, the movement track and speed of charged particles such as H < + > in the solution are changed, and the concentration of H < + > at a reaction interface is increased, so that dissolution and release of metal ions are accelerated, meanwhile, the activation energy of the reaction is reduced, and the leaching efficiency is remarkably improved. The magnetic field-assisted leaching reduces the dependence on high-temperature and high-concentration acid, and reduces the energy consumption and environmental pollution risk. The invention provides a new technical approach for efficient recovery of waste lithium ion batteries, and has remarkable economic and environmental benefits.

Description

Technical Field

[0001] The present invention relates to the field of solid waste resource utilization and hydrometallurgical technology, and in particular to a lithium ion recovery method and system based on magnetic field-coupled valuable metal leaching. Background Art

[0002] Lithium-ion batteries, due to their high energy density, long cycle life, and environmentally friendly advantages, have been widely used in portable electronic devices, electric vehicles, and energy storage systems. This has resulted in the generation of a large amount of waste lithium-ion batteries. These waste batteries contain a variety of valuable metals, such as lithium, cobalt, nickel, and manganese, as well as substances that pose potential environmental risks. Therefore, the effective recycling of waste lithium-ion batteries and the extraction of valuable metals not only brings significant economic benefits but also reduces environmental pollution, playing a vital role in the sustainable use of resources.

[0003] Currently, the main methods for recycling spent lithium-ion batteries include pyrometallurgy and hydrometallurgy. Hydrometallurgy has become a hot topic in research and application due to its advantages, such as high metal recovery rates, high product purity, and relatively low energy consumption. In the hydrometallurgical recycling process, the leaching step is the key step in dissolving valuable metals from the cathode material into the solution. Its efficiency directly affects the economic and feasibility of the entire recycling process.

[0004] Traditional wet leaching processes, such as acid leaching, usually require high reaction temperatures, high acid concentrations, and long leaching times, and often require the addition of reducing agents to promote the dissolution of high-valent metals (such as Co(III), Ni(III), and Mn(IV)). These harsh reaction conditions not only lead to high energy consumption and chemical reagent costs, but may also cause secondary pollution problems, such as acid mist emissions and the generation of large amounts of acidic wastewater. Although studies have attempted to improve leaching efficiency by optimizing leaching parameters (such as acid type and concentration, temperature, solid-liquid ratio, reducing agent type and dosage, etc.), the improvement effect is often limited, and it is difficult to fundamentally change the limitations of reaction kinetics.

[0005] As a non-contact physical field, magnetic fields have been shown to influence the motion of charged particles in solutions and the kinetics of chemical reactions. For example, magnetic fields can alter the migration rate and path of ions through the Lorentz force, affecting the concentration distribution of reactants at the solid-liquid interface and even potentially reducing the activation energy of reactions, thereby accelerating chemical reactions. Applying magnetic field technology to the leaching of valuable metals from spent lithium-ion batteries is expected to significantly improve leaching efficiency under relatively mild conditions, reduce energy and chemical consumption, and minimize environmental pollution.

[0006] In view of the above problems, there is an urgent need for a lithium ion recovery method and system based on magnetic field coupled valuable metal leaching. Summary of the Invention

[0007] In light of this, the present application provides a lithium ion recovery method and system based on magnetic field-coupled valuable metal leaching. The primary purpose is to overcome the technical challenges of existing wet-process recycling of spent lithium-ion batteries, including low leaching efficiency, harsh reaction conditions, high energy costs, and significant environmental pollution risks.

[0008] According to a first aspect of the present invention, a lithium ion recovery method based on magnetic field-coupled valuable metal leaching is provided, comprising the following steps: S1, pre-treating waste lithium-ion batteries to obtain a positive electrode material containing the valuable metal to be leached; S2, mixing the positive electrode material with a leaching solution comprising an acidic medium and at least one reducing agent to form a reaction mixture; S3, applying an external magnetic field to the reaction mixture during the leaching treatment of the reaction mixture to dissolve the valuable metal.

[0009] As a preferred technical solution, the pretreatment in step S1 includes calcining the positive electrode material. Furthermore, the calcination temperature can be 400-1000°C.

[0010] As a preferred technical solution, the reducing agent in step S2 is selected from at least one of ferrous sulfate, ferrous chloride, and ferrous nitrate. The acidic medium is a mixture of one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, and perchloric acid.

[0011] As a preferred technical solution, the magnetic field strength of the external magnetic field in step S3 is 0.1-2 T. The leaching treatment can be performed at a water bath temperature of 20-150° C. Furthermore, the leaching treatment process further includes mechanically stirring the reaction mixture.

[0012] According to the second aspect of the present invention, the present invention also provides a lithium ion recovery system based on magnetic field coupled valuable metal leaching for implementing any of the methods described above, comprising: a reaction vessel for accommodating a reaction mixture containing a positive electrode material and a leaching solution; a stirring structure for stirring the reaction mixture placed in the reaction vessel; and a magnetic field generating structure for applying an external magnetic field to the reaction mixture in the reaction vessel.

[0013] As a preferred technical solution, the system further includes a temperature control structure for controlling the temperature of the reaction mixture.

[0014] The present invention introduces an external magnetic field during the wet leaching process of waste lithium-ion battery positive electrode materials, utilizes the magnetic field's regulatory effect on the movement behavior of charged particles (such as H+ ions, metal ions, reducing agent ions, etc.) in the leaching system and its possible positive impact on the reaction activation energy, and significantly enhances the mass transfer process of valuable metals from the solid phase to the liquid phase and the chemical reaction kinetics.

[0015] Beneficial effects

[0016] The present invention provides a lithium ion recovery method and system based on magnetic field coupled valuable metal leaching. The application of an external magnetic field in the present application can accelerate ion migration and increase the effective collision frequency and concentration of reactants at the solid-liquid interface, thereby greatly improving the leaching rate of valuable metals (such as nickel, cobalt, etc.), which is much higher than the traditional leaching method without magnetic field assistance. Due to the strengthening effect of the magnetic field, it is possible to achieve or even exceed the leaching effect under relatively milder conditions (such as lower reaction temperature, lower acid concentration or shorter leaching time), thereby helping to reduce heating energy consumption and chemical reagent consumption. By optimizing the leaching conditions, reducing the amount of acid and reducing agent used, and possibly shortening the reaction time, it is helpful to reduce the generation of acid mist and the concentration of pollutants in the wastewater, thereby alleviating the pressure of subsequent three waste treatment and reducing the overall impact on the environment. The improvement in leaching efficiency directly increases the recovery of valuable metals; the mildness of the reaction conditions reduces energy and material costs; and the improvement in environmental friendliness may also reduce environmental protection treatment costs. These factors work together to help improve the economic feasibility of the entire waste lithium ion battery recycling process.

[0017] The above description is only an overview of the technical solution of the present application. In order to more clearly understand the technical means of the present application, it can be implemented in accordance with the contents of the specification. In order to make the above and other purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] The accompanying drawings, as part of this disclosure, are intended to provide a further understanding of the disclosure. The exemplary embodiments of the disclosure and their descriptions are intended to explain the disclosure and do not constitute undue limitations thereon. Obviously, the drawings described below are merely examples, and those skilled in the art can derive other drawings based on these drawings without inventive effort.

[0019] In the attached figure:

[0020] Figure 1 A schematic diagram showing the method of enhancing the leaching of valuable metals from waste lithium-ion batteries by magnetic field coupling according to an embodiment of the present invention is shown;

[0021] Figure 2Shows the X-ray diffraction pattern of the raw material provided by the present invention;

[0022] Figure 3 Shows the X-ray diffraction patterns of Comparative Example 1 and Examples 1-3 provided by the present invention;

[0023] Figure 4 Shown is a scanning SEM image of the raw material provided by the present invention;

[0024] Figure 5 Shown are scanning SEM images of Comparative Example 1 and Examples 1-3 provided by the present invention;

[0025] Figure 6 A graph showing the effects of different magnetic field intensities on the leaching rates of nickel and cobalt in waste ternary lithium batteries provided by Comparative Example 1 and Examples 1-3 of the present invention is shown;

[0026] Figure 7 A schematic diagram showing the effects of different temperatures on the leaching rates of nickel and cobalt in waste ternary lithium batteries is shown in Examples 1 and 4-6 provided by the present invention;

[0027] Figure 8 The effects of different temperatures on the leaching rates of nickel and cobalt in waste ternary lithium batteries are shown in Examples 1 and 7-9 provided by the present invention;

[0028] Figure 9 The graphs showing the effects of different temperatures on the leaching rates of nickel and cobalt in waste ternary lithium batteries are shown in Examples 1 and 10-12 provided by the present invention;

[0029] Figure 10 The effects of different temperatures on the leaching rates of nickel and cobalt in waste ternary lithium batteries are shown in Example 1 and Examples 13-15 provided by the present invention.

[0030] It should be noted that these drawings and textual descriptions are not intended to limit the conceptual scope of the present invention in any way, but rather to illustrate the concept of the present invention for those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. The following embodiments are used to illustrate the present invention but are not used to limit the scope of the present invention.

[0032] In the description of the present invention, it should be noted that the terms "upper", "lower", "front", "back", "left", "right", "vertical", "inside", "outside", etc., indicating directions or positional relationships, are based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the present invention.

[0033] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood broadly. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; and direct or indirect connections through an intermediary. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0034] Example 1

[0035] like Figure 1-10As shown, the present invention provides a lithium ion recovery method based on magnetic field-coupled valuable metal leaching, which mainly includes the following steps: S1. Pre-treating the waste lithium ion battery to obtain the positive electrode material containing the valuable metal to be leached. The purpose of this pre-treatment step is to separate the positive electrode active material in the waste lithium ion battery from other components (such as the shell, negative electrode, separator, electrolyte, current collector, etc.), and to perform preliminary purification and activation of the positive electrode material to facilitate subsequent leaching operations. The specific pre-treatment process may include: (a) Discharge treatment: The recycled waste lithium ion battery (such as lithium cobalt oxide battery, lithium manganese oxide battery, lithium iron phosphate battery, ternary lithium battery or a mixture thereof) is first safely discharged to eliminate residual power and prevent the risk of short circuit, fire, etc. during the subsequent disassembly process. Discharge can be carried out in a conductive medium, for example, immersing the battery in a sodium chloride (NaCl) aqueous solution with a mass percentage concentration of 5%-10% until the battery voltage drops to a safe level. (b) Disassembly and separation: The discharged battery is physically disassembled to separate the battery shell, positive electrode sheet, negative electrode sheet, separator, etc. Focus on collecting the positive electrode sheet, which is usually composed of an aluminum foil current collector coated with a positive electrode active material (such as LiCoO2, LiMn2O4, LiFePO4, LiNixCoyMnzO2, etc., and mixed with a conductive agent and a binder). (c) Preliminary acquisition of positive electrode materials: The positive electrode active material is peeled off from the aluminum foil current collector by mechanical methods (such as scraping, ultrasonic peeling, solvent dissolution of the binder, etc.) to obtain a crude positive electrode material powder. (d) Calcination treatment: In order to remove the residual organic binder (such as PVDF) in the crude positive electrode material and possibly change the crystal structure of the positive electrode material to improve its leaching activity, the peeled positive electrode material powder is usually required to be calcined. Calcination can be performed in a muffle furnace at a temperature between 400°C and 1000°C for 20 to 120 minutes. In Example 1, the calcination temperature was 800°C for 2 hours. After calcination, the calcined positive electrode sheet was physically crushed and sieved to obtain a black powder. After cooling to room temperature, the collected black powder is the positive electrode material to be leached.

[0036] S2, the positive electrode material is mixed with a leaching solution comprising an acidic medium and at least one reducing agent to form a reaction mixture. The positive electrode material to be leached (black powder) obtained by pretreatment in step S1 is mixed with a pre-prepared leaching solution in a reaction vessel. Specifically, in this embodiment 1, 2g of the positive electrode material to be leached (black powder) is mixed with 50mL of 2mol / L sulfuric acid solution, and 1g of sodium chloride and 1.39g of ferrous sulfate heptahydrate are added thereto, mechanically stirred under 80°C water bath conditions, the speed is 300r / min, and a 0.3T magnetic field is applied at the same time. The reaction time is 80min, and the reaction is completed to obtain a reacted liquid.

[0037] The acidic medium in the leaching solution in this application is used to provide H+ ions to dissolve the valuable metal oxides in the positive electrode material. (a) Acidic medium: Optional acidic medium includes, but is not limited to, one of the inorganic strong acids such as hydrochloric acid (HCl), sulfuric acid (H2SO4), nitric acid (HNO3), phosphoric acid (H3PO4), perchloric acid (HClO4), or a mixture thereof in any proportion. The concentration of the acid is determined according to actual needs. For example, the concentration of the inorganic acid ranges from 0.1 mol / L to 4 mol / L. (b) Reducing agent: Since valuable metals such as cobalt, nickel, and manganese in the positive electrode material usually exist in a high-valent state (such as +3 or +4), these high-valent oxides have low solubility in acid. Therefore, a reducing agent needs to be added to the leaching solution to reduce these high-valent metal ions to low-valent ions (usually +2) that are easily soluble in the acidic medium. Optional reducing agents include, but are not limited to, at least one of ferrous salts such as ferrous sulfate (FeSO4), ferrous chloride (FeCl2), and ferrous nitrate (Fe(NO3)2). The amount of reducing agent used can be determined according to the composition and stoichiometric relationship of the positive electrode material, or optimized according to experiments. For example, the reducing agent concentration ranges from 0.1 mol / L to 3 mol / L. (c) Solid-liquid ratio: The mixing ratio of the positive electrode material powder and the leaching solution (i.e., the solid-liquid ratio) is also an important parameter affecting the leaching effect. For example, the leaching solid-liquid ratio ranges from 5 g / L to 100 g / L. By mixing the positive electrode material, the acidic medium and the reducing agent in a certain proportion, a reaction mixture (usually a solid-liquid slurry) for subsequent leaching treatment can be formed.

[0038] S3. During the leaching treatment of the reaction mixture to dissolve the valuable metals, an external magnetic field is applied to the reaction mixture. This is the core step of the present invention, that is, while chemical leaching is being carried out, an external magnetic field is introduced for strengthening. (a) Leaching condition control: Temperature control: The leaching reaction is usually carried out at a certain temperature to increase the reaction rate. A water bath or other thermostat can be used to control the temperature of the reaction mixture within a preset range. For example, the water bath temperature can be from 20°C to 150°C, and 80°C is used in this embodiment 1. Mechanical stirring: In order to ensure sufficient contact between the solid and liquid phases in the reaction mixture and enhance mass transfer, it is usually necessary to continuously mechanically stir the reaction mixture. Equipment such as a magnetic stirrer or a mechanical stirring paddle can be used. The stirring rate in this embodiment 1 is 300r / min. (b) External magnetic field application: Under the above-mentioned leaching conditions (temperature, stirring), an external magnetic field is applied to the entire reaction mixture area through a magnetic field generating structure. The type of magnetic field can be a steady magnetic field or an alternating magnetic field, and its magnetic field intensity can be controlled within the range of 0.1 Tesla (T) to 2 Tesla (T), and the direction of application and uniformity of the magnetic field should be optimized according to the shape of the reaction vessel and the specific experimental device. Wherein, the magnetic field intensity applied in the present embodiment 1 is 0.3T, and the reaction time is 80min. (c) leaching time: at the set temperature, stirring rate and magnetic field intensity, the leaching reaction is allowed to continue for a period of time to ensure that the valuable metals are dissolved from the solid phase into the liquid phase as completely as possible. The leaching time can be, for example, 20 minutes to 180 minutes, and preferably, the leaching time is 20min to 80min. After the reaction is completed, heating, stirring and magnetic field application are stopped, and the resulting reaction product mainly includes a leachate containing dissolved valuable metal ions and an undissolved solid residue.

[0039] Subsequent steps may include conventional solid-liquid separation (e.g., centrifugation, filtration) and washing to obtain a pure leachate, which is then fixed to volume to obtain a leachate containing valuable metals. For example, solid-liquid separation can be performed using a centrifuge at a speed of 5000-10000 rpm for 3-10 minutes. In Example 1, the centrifuge speed used was 8000 rpm, the centrifugation time was 5 minutes, and multiple washings were performed to obtain separated solids and liquids.

[0040] Example 2

[0041] The difference from Example 1 is that the magnetic field strength in step 3 is 0.1 T, and the other conditions are exactly the same as those in Example 1.

[0042] Example 3

[0043] The difference from Example 1 is that the magnetic field strength in step 3 is 0.5 T, and the other conditions are exactly the same as those in Example 1.

[0044] Example 4

[0045] The difference from Example 1 is that the water bath temperature in step 3 is 20° C., and the other conditions are exactly the same as those in Example 1.

[0046] Example 5

[0047] The difference from Example 1 is that the water bath temperature in step 3 is 40° C., and the other conditions are exactly the same as those in Example 1.

[0048] Example 6

[0049] The difference from Example 1 is that the water bath temperature in step 3 is 60° C., and the other conditions are exactly the same as those in Example 1.

[0050] Example 7

[0051] The difference from Example 1 is that the mass of the black powder used in step 3, i.e., the positive electrode material to be leached, is 4 g, and the other conditions are exactly the same as those in Example 1.

[0052] Example 8

[0053] The difference from Example 1 is that the mass of the black powder used in step 3, i.e., the positive electrode material to be leached, is 3 g, and the other conditions are exactly the same as those in Example 1.

[0054] Example 9

[0055] The difference from Example 1 is that the mass of the black powder used in step 3, i.e., the positive electrode material to be leached, is 1 g, and the other conditions are exactly the same as those in Example 1.

[0056] Example 10

[0057] The difference from Example 1 is that the sulfuric acid concentration in step 3 is 3 mol / L, and the other conditions are exactly the same as those in Example 1.

[0058] Example 11

[0059] The difference from Example 1 is that the concentration of sulfuric acid in step 3 is 1 mol / L, and the other conditions are exactly the same as those in Example 1.

[0060] Example 12

[0061] The difference from Example 1 is that the concentration of sulfuric acid in step 3 is 0.5 mol / L, and the other conditions are exactly the same as those in Example 1.

[0062] Example 13

[0063] The difference from Example 1 is that the reaction time in step 3 is 20 min, and the other conditions are exactly the same as in Example 1.

[0064] Example 14

[0065] The difference from Example 1 is that the reaction time in step 3 is 40 min, and the other conditions are exactly the same as those in Example 1.

[0066] Example 15

[0067] The difference from Example 1 is that the reaction time in step 3 is 60 min, and the other conditions are exactly the same as those in Example 1.

[0068] Comparative Example 1:

[0069] The difference from Example 1 is that no magnetic field is introduced during the leaching process, and other conditions are exactly the same as those in Example 1.

[0070] The leaching rates of nickel and cobalt in waste lithium cobalt oxide batteries using the treatment methods of Examples 1-15 and Comparative Example 1 are compared:

[0071] (1) The X-ray diffraction pattern of the raw material of the invention is as follows Figure 2 As shown, the sample is at 2Theta( 0 ) shows a major diffraction peak at about 18-25°, which is consistent with the standard card of LiMnxCoyNizO2 (PDF#74-0919), confirming the presence of LiMnxCoyNizO2 in the raw material.

[0072] (2) The X-ray diffraction patterns of the leached residues of Comparative Example 1 and Examples 1-3 are as follows: Figure 3 As shown, the sample is at 2Theta( 0 ) shows a main diffraction peak at about 18-25°, but the peak is significantly weakened. This may be due to the erosion of the leaching agent causing the collapse of the LiMnxCoyNizO2 layered structure, resulting in a decrease in the crystallinity of the residual phase. Among them, the peak intensity of the leached residue of Example 1 decreases most significantly, indicating that the leaching is most complete. This is because the magnetic field changes the H in the solution. + The trajectory and velocity of charged particles increase the H + concentration, thereby accelerating the dissolution and release of metal ions, while reducing the activation energy of the reaction and improving the leaching efficiency.

[0073] (3) As attached Figure 4 As shown, the raw material of the invention is composed of irregular particles and agglomerates with clear boundaries between particles. Since this spherical morphology is not formed in one step, but is formed by the agglomeration of primary particles into spheres, the primary particles that make up the crystal are irregularly arranged at the grain boundaries.

[0074] (4) By the attached Figure 5It can be seen that the morphology of the residue after leaching with sulfuric acid has changed significantly. Compared with the inventive raw material, the original spherical structure in Comparative Example 1 collapsed, and the surface and edges of the residue became blurred, which indicates that the edges of the inventive raw material particles were dissolved during the leaching process. When a magnetic field was introduced during the leaching process, the original primary particles in Example 1 almost completely disappeared, and the surface showed a velvety flocculent substance, which indicated that the leaching process was more thorough. However, at higher magnetic field intensities, the leaching of Examples 2 and 3 was not thorough. This is because the metal ions in the material will be magnetized, generating a magnetic moment consistent with the direction of the magnetic field. This magnetization effect causes the metal ions to gather on the surface of the material, forming a dense magnetic layer, which hinders the contact between the leaching agent and the internal metal, thereby reducing the leaching efficiency.

[0075] (5) The effect of different magnetic field intensities on the leaching efficiency of nickel and cobalt in waste lithium batteries was investigated. The nickel and cobalt concentrations in the leachates treated by the methods of Examples 1-3 and Comparative Example 1 were compared with the efficiency of the completely digested leachate. The comparison results are shown in the attached figure. Figure 6 As shown. Figure 6 The results showed that the introduction of magnetic field promoted the leaching of waste lithium batteries, increasing the leaching efficiency of nickel and cobalt by 4.6% and 5.2% respectively, with the leaching rate of nickel reaching 99.8% and the leaching rate of cobalt reaching 99.7%.

[0076] (6) The effect of different water bath temperatures on the leaching efficiency of nickel and cobalt in waste lithium batteries was investigated. The nickel and cobalt concentrations in the leachates treated by the methods of Example 1 and Examples 4-6 were compared with the efficiency of the completely digested leachate. The comparison results are shown in the attached figure. Figure 7 shown. Figure 7 The results show that by comparing the leaching rates at different reaction temperatures, it can be found that the reaction temperature plays a promoting role in the treatment of waste lithium batteries. As the reaction temperature increases, the leaching rate also increases. When the reaction temperature is 80°C, the leaching rates of nickel and cobalt reach 99.8% and 99.7% respectively.

[0077] (7) The effect of different solid-liquid ratios on the leaching efficiency of nickel and cobalt in waste lithium batteries was investigated. The nickel and cobalt concentrations in the leachates treated by the methods of Example 1 and Examples 7-9 were compared with those of the completely digested leachates. The comparison results are shown in the attached figure. Figure 8 shown. Figure 8 The results show that by comparing the leaching rates under different solid-liquid ratios, it can be found that appropriately increasing the solid-liquid ratio promotes the treatment of waste lithium batteries. However, a higher solid-liquid ratio will reduce the effective surface area of ​​each particle involved in the reaction per unit volume, thereby weakening the metal leaching effect.

[0078] (8) The effect of different sulfuric acid concentrations on the leaching efficiency of nickel and cobalt in waste lithium batteries was investigated. The nickel and cobalt concentrations in the leachates treated by the methods of Example 1 and Examples 10-12 were compared with the efficiency of the completely digested leachate. The comparison results are shown in the attached figure. Figure 9 shown. Figure 9 The results show that by comparing the leaching rates under different sulfuric acid concentrations, it can be found that appropriately increasing the sulfuric acid concentration promotes the leaching of waste lithium batteries, but higher acidity will increase the viscosity of the solution, which is not conducive to the leaching of metal ions.

[0079] (9) The effect of different sulfuric acid concentrations on the leaching efficiency of nickel and cobalt in waste lithium batteries was investigated. The nickel and cobalt concentrations in the leachates treated by the methods of Example 1 and Examples 13-15 were compared with the efficiency of the completely digested leachate. The comparison results are shown in the attached figure. Figure 10 As shown. Figure 10 The results show that by comparing the leaching rates under different leaching time conditions, it can be found that increasing the leaching time promotes the recovery of waste lithium batteries. When the leaching time is 80 minutes, the leaching rates of nickel and cobalt reach 99.8% and 99.7% respectively.

[0080] Example 16

[0081] The present invention also provides a lithium ion recovery system based on magnetic field coupled valuable metal leaching for implementing the above method. The system includes at least the following main structures:

[0082] Reaction vessel: This is used to hold the reaction mixture formed in step S2 (i.e., the mixed slurry of cathode material, acidic medium, and reducing agent) and serves as the location for the leaching reaction in step S3. The reaction vessel should be made of a material that can withstand the corrosion of the acidic medium used and a certain operating temperature. Common materials include glass and polytetrafluoroethylene (PTFE)-lined reactors. Its shape and size are determined by the processing volume.

[0083] Stirring mechanism: This mechanism is used to effectively mechanically agitate the reaction mixture within the reaction vessel to ensure adequate contact between the solid and liquid phases, enhance mass transfer, prevent solid particle settling, and help maintain a uniform temperature. This mechanism can include a stirring paddle (e.g., anchor, paddle, turbine, etc.) extending into the reaction vessel and its drive motor. For small-scale experiments, it can be a magnetic stirrer placed at the bottom of the reaction vessel and a matching magnetic stirrer base.

[0084] Magnetic field generating structure: This is the key structure for realizing the core technical features of the present invention, and is used to apply a controllable external magnetic field to the reaction mixture in the reaction vessel. The magnetic field generating structure can adopt various forms according to actual needs.

[0085] Permanent magnet array: One or more permanent magnets with specific shapes and magnetic field strengths (such as NdFeB strong magnetic materials) can be reasonably arranged around the outside of the reaction vessel (for example, placed opposite each other on both sides of the reaction vessel, or arranged around the reaction vessel) to form a magnetic field of desired strength and distribution within the reaction area.

[0086] In one possible embodiment, one or more electromagnet coils can be used to generate a magnetic field with adjustable strength and direction by controlling the magnitude and direction of the current flowing through the coils. The electromagnet can be designed as a solenoid surrounding the reaction vessel, or a magnetic yoke structure can be used to concentrate the magnetic field on the reaction area.

[0087] In this embodiment, for laboratory studies requiring a highly uniform magnetic field, one or more pairs of Helmholtz coils can be used, with the reaction vessel positioned in its central region. The magnetic field generating structure should be designed to ensure that the generated magnetic field effectively covers the primary area of ​​the reaction mixture, and the magnetic field strength and uniformity can be adjusted or optimized based on process requirements.

[0088] Temperature control structure: used to accurately control and maintain the temperature of the reaction mixture during the leaching process. The temperature control structure may include: a heating / cooling unit: for example, the reaction vessel may be placed in a constant temperature water bath, and the reaction temperature may be controlled by the heating and cooling functions of the water bath. Alternatively, the reaction vessel itself may be designed as a structure with a heating / cooling jacket, and the temperature may be adjusted by introducing a heat medium (such as hot water, steam) or a coolant (such as cooling water) into the jacket. Temperature sensor: a temperature sensor (such as a thermocouple, platinum resistance, etc.) is installed in the reaction vessel or close to the outer wall of the container to monitor the temperature of the reaction mixture in real time. Temperature controller: receives the signal from the temperature sensor, and according to the set target temperature, automatically adjusts the power or medium flow of the heating / cooling unit through algorithms such as PID control to achieve precise control of the reaction temperature.

[0089] The above description is merely a preferred embodiment of the present invention and does not constitute any form of limitation to the present invention. Although the present invention has been disclosed as above in terms of a preferred embodiment, it is not intended to limit the present invention. Any technician familiar with this patent can make slight changes or modifications to equivalent embodiments of equivalent changes using the above-mentioned technical contents without departing from the scope of the technical solution of the present invention. The implementation schemes in the above-mentioned embodiments can also be further combined or replaced. However, any simple modifications, equivalent changes and modifications made to the above-mentioned embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the solution of the present invention.

Claims

1. A lithium electron recovery method based on magnetic field coupled valuable metal leaching, characterized in that: The following steps are involved: s1. Pre-treating waste lithium-ion batteries to obtain a positive electrode material containing the valuable metal to be leached; s2. mixing the cathode material with a leaching solution comprising an acidic medium and at least one reducing agent to form a reaction mixture; s3. During the leaching process of the reaction mixture to dissolve the valuable metals, an external magnetic field is applied to the reaction mixture.

2. The lithium electron recovery method based on magnetic field coupled valuable metal leaching according to claim 1, characterized in that: The pretreatment in step s1 includes calcining the positive electrode material.

3. The lithium electron recovery method based on magnetic field coupled valuable metal leaching according to claim 2, characterized in that: The temperature of the calcination treatment is 400-1000°C.

4. The lithium electron recovery method based on magnetic field coupled valuable metal leaching according to claim 3, characterized in that: The reducing agent is selected from at least one of ferrous sulfate, ferrous chloride and ferrous nitrate.

5. The lithium electron recovery method based on magnetic field coupled valuable metal leaching according to claim 4, characterized in that: The acidic medium is a mixture of one or more of hydrochloric acid, sulfuric acid, nitric acid, phosphoric acid, perchloric acid, etc.

6. The lithium electron recovery method based on magnetic field coupled valuable metal leaching according to claim 2, characterized in that: The magnetic field strength of the external magnetic field is 0.1-2T.

7. The lithium electron recovery method based on magnetic field coupled valuable metal leaching according to claim 6, characterized in that: The leaching treatment is carried out at a water bath temperature of 20-150°C.

8. The lithium electron recovery method based on magnetic field coupled valuable metal leaching according to claim 7, characterized in that: The leaching process also includes mechanically stirring the reaction mixture.

9. A lithium electron recovery system based on magnetic field coupled valuable metal leaching for implementing the method according to any one of claims 1 to 8, characterized in that: include: a reaction vessel for containing a reaction mixture comprising a cathode material and a leaching solution; a stirring structure, for stirring the reaction mixture placed in the reaction vessel; The magnetic field generating structure is used to apply an external magnetic field to the reaction mixture in the reaction container.

10. The lithium electron recovery system based on magnetic field coupled valuable metal leaching according to claim 9, characterized in that: The system further comprises a temperature control structure for controlling the temperature of the reaction mixture.

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