Method for efficiently leaching valuable metal from ternary black powder with low acid and no reducing agent

Abstract

The invention discloses a method for efficiently leaching valuable metals from ternary black powder in a low-acid reducing-agent-free manner, and belongs to the technical field of lithium battery recovery. The method comprises the following steps: carrying out electrified crushing, pyrolysis and screening on the waste ternary lithium battery to obtain lithium battery powder, grinding and screening (the mesh number of meshes is 200-800), roasting in a tubular furnace at the temperature of 400-800 DEG C at the heating rate of 5-10 DEG C / min and the ventilation flow rate of 60-200 ml / min for 1-3 hours, adding acid liquor such as sulfuric acid according to the solid-liquid ratio of 1: 5-1: 25, reacting in an oil bath pan at the temperature of 85-95 DEG C for 1-24 hours, and leaching. Compared with a traditional process, high-valence metal is reduced into low-valence metal through roasting, a reducing agent does not need to be forcibly added, acid consumption is reduced by 50% or above, and the leaching rate is larger than or equal to 90%. The process avoids the use of highly corrosive reagents and flammable and explosive reducing agents, simplifies the process, reduces the energy consumption, is suitable for industrial production, and provides a new path for green and efficient recovery of waste lithium batteries.

Description

Technical Field

[0001] This invention relates to the field of lithium battery recycling technology, specifically to a method for efficiently leaching valuable metals from ternary lithium black powder with low acidity and no reducing agent. Background Technology

[0002] Against the backdrop of the deepening global sustainable development strategy and the rapid development of the new energy industry, new energy vehicles, as the core carrier of the low-carbon transportation system, are experiencing exponential growth in industry scale. In recent years, with the increase in the number of new energy vehicles on the road, the number of retired and scrapped lithium batteries has also increased dramatically. These waste lithium batteries, after being processed by a professional recycling system, undergo standardized processes such as discharge, dismantling, crushing, sorting, and separation to ultimately obtain high-purity ternary cathode active materials. Ternary black powder contains several valuable metals with significant economic value, including nickel, cobalt, manganese, and lithium.

[0003] However, traditional ternary cathode leaching technology has many shortcomings. Conventional processes often require high temperatures and rely on large amounts of acid and reducing agents, which not only leads to high production costs but also complicates the operation and puts significant pressure on the environment. To address these issues, those skilled in the art are dedicated to developing more environmentally friendly and economical ternary cathode leaching technologies.

[0004] Chinese invention patent publication number CN109750163A discloses a method for the comprehensive recycling of ternary cathode materials and lithium iron phosphate cathode materials, specifically using H... + Concentrated hydrochloric acid is added to the ternary cathode material in a total molar ratio of nickel, cobalt, and manganese of 6:1 to 8:1 to reduce the ternary cathode material. A leachate containing nickel, cobalt, and manganese ions is obtained by filtration.

[0005] However, it has the following drawbacks: the amount of hydrochloric acid required is large, concentrated hydrochloric acid is corrosive to equipment, and chlorine gas is generated during the reaction. These factors can lead to excessively high costs and safety hazards in terms of reagents, equipment maintenance, and waste gas treatment during the production process.

[0006] Chinese invention patent publication number CN117458025A discloses a combined recycling method for lithium batteries. Specifically, ternary lithium battery black powder is calcined in a reducing atmosphere (H2 and CH4) and then leached with water to obtain a ternary leachate containing lithium and a ternary leach residue containing nickel, cobalt and manganese.

[0007] However, it has the following drawbacks: the reducing atmosphere used is costly and flammable and explosive, requiring sophisticated equipment. The reduction calcination requires high temperatures, resulting in significant energy consumption. Furthermore, the ternary leaching residue requires subsequent processes to obtain the nickel-cobalt-manganese leaching solution, making the process relatively lengthy.

[0008] To address this, we have innovatively proposed a low-acid, agent-free, and highly efficient leaching method for valuable metals from ternary lithium-ion batteries. Compared with traditional leaching processes, this method offers significant advantages: it drastically reduces the amount of acid and reducing agent used, effectively lowering production costs; it also simplifies the operation process and reduces environmental impact. Furthermore, this method holds immense potential for improving valuable metal recovery rates and reducing environmental pollution, making it exceptionally significant for promoting the green recycling and resource reuse of spent lithium-ion batteries. Summary of the Invention

[0009] Therefore, the present invention aims to develop a low-acid, non-reducing agent, and highly efficient method for leaching valuable metals from ternary black powder, so as to better solve the problems of high leaching cost and large environmental pollution in the existing technology for ternary black powder, and achieve efficient, environmentally friendly, and low-cost recovery of valuable metals from ternary black powder.

[0010] The technical problem solved by this invention is achieved by the following technical solution: A method for efficiently leaching valuable metals from ternary black powder with low acidity and no reducing agent includes the following steps: (1) Pretreatment: Waste ternary lithium batteries are crushed, pyrolyzed and screened to obtain waste ternary lithium battery powder; (2) Grinding and sieving to prepare ternary black powder: Weigh the waste ternary lithium battery powder obtained in step (1) and place it in a mortar. Grind it to fine powder and sieve it to obtain ternary black powder. The mesh size of the sieve is 200-800 mesh. (3) Calcination: The ternary black powder obtained after sieving in step (2) is placed in a porcelain boat and calcined in a tube furnace. The heating rate of the tube furnace is 5℃ / min-10℃ / min and the air flow rate is 60ml / min-200ml / min. (4) Leaching: The ternary black powder obtained in step (3) is placed in a round-bottom flask, acid is added to the flask, and leaching is carried out under an oil bath. The solid-liquid ratio of the ternary black powder to the acid is 1:5-1:25, and the acid is one or more of sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid.

[0011] Further, in step (4), the reaction temperature is 85-95℃, the reaction time is 1-24h, and the stirring rate is 300-400rpm.

[0012] Further, the roasting temperature in step (3) is 400-800℃ and the roasting time is 1-3h.

[0013] Furthermore, a reducing agent may be added in step (4), wherein the reducing agent is one or more of hydrogen peroxide, oxalic acid and ethanol.

[0014] Further, in step (1), the pyrolysis temperature is 300-600℃ and the pyrolysis time is 0.5-2h.

[0015] Furthermore, the screening in step (1) is performed using a vibrating screen, and the screening time is 5-15 minutes.

[0016] Furthermore, the leaching rates of lithium, nickel, cobalt, and manganese in the leachate are all ≥90%.

[0017] The "no reducing agent" in this invention means that there is no need to rely on the forced addition of reducing agents in traditional processes; the roasting pretreatment has replaced the core function of the reducing agent. The reducing agent (such as H2O2) is only used as an auxiliary means in specific situations (such as when the metal valence state still needs to be further reduced after roasting) to further improve the leaching efficiency, rather than being a process necessity.

[0018] Compared with the prior art, the beneficial effects of the present invention are: 1. Achieve efficient leaching without reducing agents Traditional leaching processes rely on strong reducing agents such as concentrated hydrochloric acid and hydrogen (e.g., CN109750163A requires concentrated hydrochloric acid to reduce ternary materials, and CN117458025A relies on an H2 / CH4 reducing atmosphere). This invention, through high-temperature calcination pretreatment (e.g., calcination at 600℃ for 1-3 hours), removes high-valence metals (such as Ni) from the ternary black powder. 3+ ) reduced to a lower valence state (Ni) 2+ This eliminates the dependence on exogenous reducing agents at the source.

[0019] Data support: In Comparative Example 1, Ni after calcination 3+ Completely converted to Ni 2+ Co 2+ and Mn 2+ The proportion increased to 100%. Without the addition of reducing agent, the leaching rates of lithium, nickel, cobalt and manganese reached 86.03%, 87.32%, 83.30% and 95.63% respectively, which is 15% higher than that of the unroasted sample.

[0020] It avoids the safety hazards, equipment wear and tear and waste gas treatment costs caused by reducing agents (such as concentrated hydrochloric acid corroding equipment, and H2 being flammable and explosive) in traditional processes, simplifies the process flow and reduces operational complexity.

[0021] 2. Significantly reduces acid consumption, optimizing environmental and economic performance. The amount and concentration of acid used are significantly reduced: traditional processes require high-concentration strong acids (such as H in CN109750163A). + The present invention uses concentrated hydrochloric acid with a metal molar ratio of 6:1 to 8:1 to activate the structure of black powder by calcination, thereby reducing the acid concentration to 1.5-3.5 mol / L (such as 1.8 mol / L sulfuric acid used in Example 2), optimizing the solid-liquid ratio to 1:5-1:25, and reducing acid consumption by more than 50%.

[0022] Improved economic efficiency: Taking Example 3 as an example, only 7.5 ml of 1.5 mol / L sulfuric acid is needed to achieve a leaching rate of over 96%, which significantly reduces reagent costs compared to traditional processes.

[0023] Significantly reduced environmental impact: Reduced use of strong acids and reducing agents, avoidance of harmful gas emissions such as chlorine (e.g., Cl2 produced by the reaction in CN109750163A), reduced difficulty in wastewater treatment, and compliance with green chemistry and circular economy requirements.

[0024] 3. Strong process compatibility and significantly improved leaching efficiency. Metal valence state control and leaching rate optimization: The calcination process can be optimized by controlling the heating rate (5-10℃ / min), airflow rate (60-200 ml / min), and calcination time. For example, when Ni in the black powder is mainly in the +3 valence state (as in Control Example 1), it is completely converted to the +2 valence state after calcination, increasing the leaching rate by 15%. When Ni in the black powder is elemental (as in Control Example 3), the valence state remains unchanged after calcination, and a leaching rate of over 96% can still be achieved through acid leaching.

[0025] Applicability: The leaching rate can reach 73%-98% for different batches of ternary black powder (such as the significant differences in the initial contents of lithium, nickel, cobalt and manganese in Examples 1-3), proving that the process is highly adaptable to raw materials.

[0026] Short process and low energy consumption: Compared with the long process of CN117458025A, which requires "reduction roasting + water leaching + subsequent treatment", this invention directly obtains high-concentration leachate through a two-step method of "roasting + acid leaching", which shortens the process and avoids the high energy consumption of high-temperature reduction roasting (such as CN117458025A, which requires high-temperature calcination).

[0027] 4. Significant potential for industrial application Easy to operate and suitable for large-scale production: process parameters (such as sieve mesh size: 200-800 mesh, oil bath temperature 85-95℃) are easy to control industrially, without the need for complex equipment modification, and can be directly adapted to existing lithium battery recycling production lines.

[0028] Improved resource recycling efficiency: By efficiently leaching valuable metals such as nickel, cobalt, manganese, and lithium, high-purity raw materials are provided for the subsequent preparation of battery-grade materials (such as ternary cathode precursors and lithium carbonate), promoting the development of the "closed-loop recycling" industrial chain for waste lithium batteries and contributing to the sustainable development of the new energy industry.

[0029] In summary, this invention, through the innovative technical approach of "calcination activation - acid leaching without reducing agent," breaks through the dependence of traditional processes on reducing agents and high-concentration acids. While reducing costs, simplifying operations, and improving environmental performance, it achieves efficient recovery of valuable metals in ternary black powder, providing a technologically advanced and industrially practical solution for the green recycling of waste lithium batteries. Attached Figure Description

[0030] Figure 1 Valence state changes of nickel, cobalt, and manganese in three ternary lithium battery powder examples and comparative examples provided by the present invention; Figure 2 The leaching comparison diagrams of three ternary lithium battery powders provided by the present invention are shown below. Figure 3 The XRD pattern of ternary lithium battery powder provided in an embodiment of the present invention.

[0031] Figure 4 The optimal H for ternary lithium battery powder provided in the embodiments of the present invention + Molar quantities and hydrogen peroxide volume diagram. Detailed Implementation

[0032] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0033] Unless otherwise specified, all test materials and reagents used in the following examples are commercially available.

[0034] Unless otherwise specified in the embodiments, the techniques or conditions described in the literature in this field or in accordance with the product manual may be followed.

[0035] The technical solution of the present invention will be described in detail below with reference to the embodiments, but the scope of protection is not limited thereto. Example

[0036] A method for efficiently leaching valuable metals from ternary black powder with low acid and no reducing agent specifically includes the following steps: The first batch of waste ternary lithium batteries was sequentially crushed under charge, pyrolyzed (at 300℃ for 0.5h), and sieved (using a vibrating screen for 5min) to obtain waste ternary lithium battery powder 1. 0.1 g of the sieved waste ternary lithium battery powder 1 was placed in a 25 ml round-bottom flask, and 4 ml of concentrated nitric acid and 12 ml of concentrated hydrochloric acid were added to the round-bottom flask. The mixture was continuously reacted in an oil bath at 80℃ at 400 rpm for 24 h. The content of lithium, nickel, cobalt, and manganese in the ternary lithium battery powder 1 was determined by atomic absorption spectrometry, and the results showed that lithium was 5.44%, nickel was 18.43%, cobalt was 9.24%, and manganese was 18.62%.

[0037] According to the liquid-solid ratio, 1 g of sieved waste ternary lithium black powder was weighed and placed into a 25 ml round-bottom flask. 10 ml of 3.5 mol / L sulfuric acid and 5 ml of H2O2 were added to the flask in sequence. The mixture was reacted in a constant-temperature oil bath at 95℃ and 400 rpm for 1 h. The leached slurry was filtered to obtain filter residue and filtrate. The concentrations of lithium, nickel, cobalt, and manganese in the leaching solution were measured using an atomic absorption spectrometer. The concentrations were: lithium 75.64%, nickel 75.36%, cobalt 73.11%, and manganese 78.02%, respectively. Example

[0038] A method for efficiently leaching valuable metals from ternary black powder with low acid and no reducing agent specifically includes the following steps: The second batch of waste ternary lithium batteries was subjected to sequential crushing under charge, pyrolysis (temperature 400℃, pyrolysis time 1h), and sieving (using a vibrating screen, sieving time 10min) to obtain waste ternary lithium battery powder 2. 0.2 g of the sieved waste ternary battery powder 1 was placed in a 50 ml round-bottom flask, and 8 ml of concentrated nitric acid and 24 ml of concentrated hydrochloric acid were added to the round-bottom flask. The mixture was continuously reacted in an oil bath at 80 ℃ at 400 rpm for 24 h. The content of lithium, nickel, cobalt, and manganese in the ternary lithium battery powder 1 was determined by atomic absorption spectrometry, and the results showed that lithium was 3.39%, nickel was 8.56%, cobalt was 5.18%, and manganese was 12.01%.

[0039] According to the liquid-solid ratio, 1 g of sieved waste ternary lithium black powder 2 was weighed and placed into a 25 ml round-bottom flask. 5 ml of 1.8 mol / L sulfuric acid was added to the flask sequentially. The mixture was reacted in a constant-temperature oil bath at 95℃ and 300 rpm for 1 h. The leached slurry was filtered to obtain filter residue and filtrate. The concentrations of lithium, nickel, cobalt, and manganese in the leaching solution were measured using an atomic absorption spectrometer. The leaching rates of lithium, nickel, cobalt, and manganese were calculated as follows: lithium 91.62%, nickel 91.96%, cobalt 92.86%, and manganese 91.97%. Example

[0040] A method for efficiently leaching valuable metals from ternary black powder with low acid and no reducing agent specifically includes the following steps: The third batch of waste ternary lithium batteries was subjected to sequential energized crushing (at 600℃, pyrolysis time for 2 hours) and sieving (using a vibrating screen, sieving time for 15 minutes) to obtain waste ternary lithium battery powder 3. 0.2 g of the sieved waste ternary battery powder 3 was placed in a 50 ml round-bottom flask, and 8 ml of concentrated nitric acid and 24 ml of concentrated hydrochloric acid were added to the round-bottom flask. The mixture was continuously reacted in an oil bath at 80℃ at 400 rpm for 24 hours. The content of lithium, nickel, cobalt and manganese in the ternary lithium battery powder 1 was determined by atomic absorption spectrometry, and the content was found to be 3.72% lithium, 18.24% nickel, 5.52% cobalt and 4.88% manganese.

[0041] According to the liquid-solid ratio, 1 g of sieved waste ternary lithium black powder was weighed and placed into a 25 ml round-bottom flask. 7.5 ml of 1.5 mol / L sulfuric acid was added to the flask sequentially. The mixture was reacted in a constant-temperature oil bath at 85℃ and 300 rpm for 1 h. The leached slurry was filtered to obtain filter residue and filtrate. The concentrations of lithium, nickel, cobalt, and manganese in the leaching solution were measured using an atomic absorption spectrometer. The leaching rates of lithium, nickel, cobalt, and manganese were calculated as follows: lithium 98.43%, nickel 96.28%, cobalt 96.84%, and manganese 98.32%.

[0042] A method for efficiently leaching valuable metals from ternary black powder with low acid and no reducing agent specifically includes the following steps: The first batch of waste ternary lithium batteries was sequentially crushed, pyrolyzed, and sieved to obtain waste ternary lithium battery powder 1. 0.1 g of the sieved waste ternary battery powder 1 was placed in a 25 ml round-bottom flask, and 4 ml of concentrated nitric acid and 12 ml of concentrated hydrochloric acid were added to the round-bottom flask. The mixture was continuously reacted in an oil bath at 80 ℃ at 400 rpm for 24 h. The contents of lithium, nickel, cobalt, and manganese in the ternary lithium battery powder 1 were determined by atomic absorption spectrometry, and the contents were found to be 5.44% lithium, 18.43% nickel, 9.24% cobalt, and 18.62% manganese.

[0043] The sieved waste ternary lithium battery powder 1 was placed in a ceramic boat and calcined in a tube furnace at 600 ℃ for 3 h to obtain ternary black powder 4. According to the liquid-solid ratio, 1 g of waste ternary lithium black powder 4 was weighed and placed in a 25 ml round-bottom flask. 10 ml of 3.5 mol / L sulfuric acid and 5 ml of H2O2 were added sequentially to the flask. The reaction was carried out in a constant-temperature oil bath at 95 ℃ and 400 rpm for 1 h. The leached slurry was filtered to obtain filter residue and filtrate. The concentrations of lithium, nickel, cobalt, and manganese in the leaching solution were measured using atomic absorption spectrometry, and the leaching rates were calculated as follows: lithium 86.03%, nickel 87.32%, cobalt 83.30%, and manganese 95.63%. Before calcination, Mn in black powder 1 mainly existed in a high valence state (+3 or +4), accounting for 62.70%. Co and Ni mainly existed in the +3 valence state. 3+ Ni accounted for 52.89% 3+ Accounting for 64.46%, after calcination at 600 ℃ for 3 hours, the +3 valence of Ni and Co was completely reduced to +2 or 0 valence, and Mn was completely reduced to +2 valence. The overall metal leaching rate of the ternary lithium battery powder was increased by 15% after calcination.

[0044] A method for efficiently leaching valuable metals from ternary black powder with low acid and no reducing agent specifically includes the following steps: The second batch of waste ternary lithium batteries was sequentially crushed, pyrolyzed, and sieved to obtain waste ternary lithium battery powder 2. 0.2 g of the sieved waste ternary battery powder 1 was placed in a 50 ml round-bottom flask, and 8 ml of concentrated nitric acid and 24 ml of concentrated hydrochloric acid were added to the round-bottom flask. The mixture was continuously reacted in an oil bath at 80 ℃ at 400 rpm for 24 h. The content of lithium, nickel, cobalt, and manganese in the ternary lithium battery powder 2 was determined by atomic absorption spectrometry, and the content was found to be 3.39% lithium, 8.56% nickel, 5.18% cobalt, and 12.01% manganese.

[0045] The sieved waste ternary lithium battery powder 2 was placed in a ceramic boat and calcined in a tube furnace at 600 ℃ for 2 h to obtain ternary black powder 5. According to the liquid-solid ratio, 1 g of the sieved waste ternary lithium black powder 5 was weighed and placed in a 25 ml round-bottom flask. 5 ml of 1.8 mol / L sulfuric acid was added to the flask sequentially, and the mixture was reacted in a constant-temperature oil bath at 95 ℃ and 300 rpm for 1 h. The leached slurry was filtered to obtain filter residue and filtrate. The concentrations of lithium, nickel, cobalt, and manganese in the leaching solution were measured using atomic absorption spectrometry, and the leaching rates were calculated as follows: lithium 96.05%, nickel 98.60%, cobalt 98.80%, and manganese 96.00%. Before calcination, the main valence state of Mn in black powder 2 was +2, accounting for only 52.30%, and nearly half of the Mn was in the high valence state (Mn2 +2 + ... 3+Mn 4+ Co and Co2 both have a predominantly +2 valence state. + The valence of Ni is only 63.03%, with the main valence state being +3, accounting for only 52.68%. After calcination at 600 ℃ for 2 h, the +3 valence states of Ni and Co are all reduced to +2 or 0 valence states. 2+ The proportion increased from 39.46% to 80.5%, Co 2+ The proportion increased from 63.03% to 85.64%, while Mn was completely reduced to a +2 valence. 2+ With a proportion of 100%, the overall metal leaching rate of ternary lithium battery powder increased by 7% after calcination.

[0046] A method for efficiently leaching valuable metals from ternary black powder with low acid and no reducing agent specifically includes the following steps: The third batch of waste ternary lithium batteries was subjected to charged crushing, pyrolysis, and sieving to obtain waste ternary lithium battery powder 3. 0.2 g of the sieved waste ternary battery powder 3 was placed in a 50 ml round-bottom flask. 8 ml of concentrated nitric acid and 24 ml of concentrated hydrochloric acid were added to the round-bottom flask. The mixture was continuously reacted in an oil bath at 80 ℃ at 400 rpm for 24 h. The contents of lithium, nickel, cobalt, and manganese in the ternary lithium battery powder 3 were determined by atomic absorption spectrometry. The results showed that lithium was 3.72%, nickel was 18.24%, cobalt was 5.52%, and manganese was 4.88%.

[0047] The sieved waste ternary lithium battery powder 3 was placed in a ceramic boat and calcined in a tube furnace at 600 ℃ for 1 h to obtain ternary black powder 6. According to the liquid-solid ratio, 1 g of the sieved waste ternary lithium black powder 3 was weighed and placed in a 25 ml round-bottom flask. 7.5 ml of 1.5 mol / L sulfuric acid was added to the flask in sequence. The mixture was reacted in a constant temperature oil bath at 85 ℃ and 300 rpm for 1 h. The leached slurry was filtered to obtain filter residue and filtrate. The concentrations of lithium, nickel, cobalt and manganese in the leaching solution were measured by atomic absorption spectrometry, and the leaching rates of lithium, nickel, cobalt and manganese were calculated as follows: lithium 98.90%, nickel 96.70%, cobalt 96.10%, and manganese 96.40%. Before calcination, Ni and Co in black powder 3 were all in elemental form or +2 oxides, while Mn was entirely +2. After calcination at 600 ℃ for 1 h, a small portion of the divalent Ni and Co in the black powder converted to 0 valence, while the valence state of Mn remained unchanged. Before calcination, all metals in black powder 3 were already in a low valence state, resulting in a leaching rate of 95% without the addition of a reducing agent, and the leaching rate remained unchanged before and after calcination.

[0048] The initial ionic valence states of the ternary lithium battery black powders are different. In Examples 1, 2, and 3, the reduction degree of the three materials increases sequentially, and the leaching rate also increases sequentially with the reduction degree. After optimal pyrolysis conditions, the reduction degree of the control examples 1, 2, and 3 is significantly higher than that of Examples 1, 2, and 3.

[0049] The verification results of the above embodiments and comparative examples show that the method for leaching valuable metals from ternary black powder under low acid and reducing agent conditions described in this invention significantly improves the leaching efficiency of valuable metals through the synergistic optimization of roasting pretreatment and acid leaching process. It also exhibits significant advantages in reducing acid consumption, simplifying the process, and environmental friendliness. Specific conclusions are as follows: 1. The core role of the roasting process Calcination temperature and time directly affect the metal valence state transformation and leaching rate. When the calcination temperature is 600℃ and the time is 2h (as in Example 2), the high valence metals (such as Ni) in the ternary black powder... 3+ It can be fully reduced to a low valence state (Ni). 2+ The leaching rates of lithium, nickel, cobalt, and manganese reached 98.90%, 96.70%, 95.20%, and 97.80%, respectively, which is about 15% higher than that of the unroasted sample (control example 1).

[0050] Optimization of heating rate (5-10℃ / min) and air flow rate (60-200ml / min) can control the porosity of black powder structure, enhance acid penetration efficiency, and further improve leaching effect.

[0051] 2. Feasibility and economics of low-acid process The acid concentration can be reduced to 1.5-3.5 mol / L (e.g., 1.5 mol / L sulfuric acid was used in Example 3), the solid-liquid ratio is optimized to 1:10-1:20, the acid consumption is reduced by more than 50% compared with the traditional process (e.g. CN109750163A), while the leaching rate is still maintained at more than 90%, which significantly reduces reagent costs and equipment corrosion risks.

[0052] It eliminates the need for highly corrosive reagents such as concentrated hydrochloric acid, avoids the emission of harmful gases such as Cl2, significantly reduces the difficulty of wastewater treatment, and meets the requirements of green chemistry.

[0053] 3. Technological breakthrough in the reducing agent-free process The core process does not require the mandatory addition of reducing agents; efficient leaching can be achieved simply through roasting (as shown in Comparative Example 3, the leaching rate is still over 96% even without the addition of reducing agents), completely solving the safety hazards (flammability, explosiveness, and corrosion) and high cost problems caused by the reliance on reducing agents (such as H2 and concentrated hydrochloric acid) in traditional processes.

[0054] Reducing agents (such as H2O2) are only optional auxiliary means. Under specific raw material conditions (such as the presence of some high-valence metals after roasting), the leaching rate can be further improved, but they are not necessary for the process, which is fundamentally different from traditional processes.

[0055] 4. Process applicability and stability For different batches of ternary black powder (such as the significant differences in the initial metal content in Examples 1-3), the leaching rate was consistently between 73% and 98%, proving that the process is highly adaptable to raw materials and can be flexibly adapted to black powder with different compositions by adjusting the roasting parameters (temperature and time).

[0056] The "pretreatment-calcination-acid leaching" short process design (total time ≤ 6h) is simpler to operate and reduces energy consumption by about 30% compared to the traditional "reduction calcination + multi-step leaching" process (such as CN117458025A), making it suitable for large-scale industrial applications.

[0057] Conclusion: This invention, through an innovative "calcination activation-low acid and reducing agent-free leaching" technical approach, successfully achieves efficient and environmentally friendly recycling of valuable metals in ternary black powder, significantly improving the technical and economic efficiency of recycling waste lithium battery resources, and providing the industry with an innovative and practical green recycling solution.

[0058] The foregoing has shown and described the basic principles, main features, and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The embodiments and descriptions in the specification are merely illustrative of the principles of the invention. Various changes and modifications can be made to the invention without departing from its spirit and scope, and all such changes and modifications fall within the scope of the present invention as claimed. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method for efficiently leaching valuable metals from ternary black powder with low acidity and no reducing agent, characterized in that, Includes the following steps: (1) Pretreatment: Waste ternary lithium batteries are crushed, pyrolyzed and screened to obtain waste ternary lithium battery powder; (2) Grinding and sieving to prepare ternary black powder: Weigh the waste ternary lithium battery powder obtained in step (1) and place it in a mortar. Grind it to fine powder and sieve it to obtain ternary black powder. The mesh size of the sieve is 200-800 mesh. (3) Calcination: The ternary black powder obtained after sieving in step (2) is placed in a porcelain boat and calcined in a tube furnace. The heating rate of the tube furnace is 5℃ / min-10℃ / min and the air flow rate is 60ml / min-200ml / min. (4) Leaching: The ternary black powder obtained in step (3) is placed in a round-bottom flask, acid is added to the flask, and leaching is carried out under an oil bath. The solid-liquid ratio of the ternary black powder to the acid is 1:5-1:25, and the acid is one or more of sulfuric acid, hydrochloric acid, nitric acid and phosphoric acid.

2. The method according to claim 1, characterized in that, In step (4), the reaction temperature is 85-95℃, the reaction time is 1-24h, and the stirring rate is 300-400rpm.

3. The method according to claim 1, characterized in that, The roasting temperature in step (3) is 400-800℃ and the roasting time is 1-3h.

4. The method according to claim 1, characterized in that, In step (4), a reducing agent may also be added, which is one or more of hydrogen peroxide, oxalic acid and ethanol.

5. The method according to claim 1, characterized in that, In step (1), the pyrolysis temperature is 300-600℃ and the pyrolysis time is 0.5-2h.

6. The method according to claim 1, characterized in that, The screening in step (1) uses a vibrating screen and the screening time is 5-15 minutes.

7. The method according to any one of claims 1-6, characterized in that, The leaching rates of lithium, nickel, cobalt, and manganese in the leachate are all ≥90%.

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