A method for recovering waste lithium batteries with low carbon by in-situ fluorine fixation of shrimp shells

Abstract

This invention relates to a method for the in-situ solidification of fluorine from shrimp shells in a low-carbon manner for the recycling of waste lithium batteries. The method includes the following steps: uniformly mixing shrimp shell biomass powder with the positive electrode material of waste lithium batteries to obtain a reactant; calcining the reactant at 450–600 °C to obtain a solid-phase pyrolysis residue; mixing the solid-phase pyrolysis residue with a leaching agent for leaching treatment, and separating to obtain a lithium-rich filtrate. This invention utilizes shrimp shell biomass powder, which, after pyrolysis, forms a natural composite of calcium encapsulated / confined by porous carbon. This composite is then uniformly mixed with the positive electrode material and co-calcined in situ, allowing the active sites of calcium and the fluorine diffusion channels to be highly coupled at the micrometer scale, generating stable CaF2. This achieves in-situ solidification of fluorine at the source, reducing equipment corrosion and exhaust gas treatment load. Simultaneously, solidified fluorine does not interfere with the phase transformation of lithium, preserving the conversion of lithium to the water-soluble phase and improving the recovery rate. This invention also features a low calcination temperature and uses waste to treat waste, effectively reducing energy consumption and costs.

Description

Technical Field

[0001] This invention belongs to the field of waste lithium battery recycling, specifically involving a method for the in-situ solid fluorine recycling of waste lithium batteries using shrimp shells in a low-carbon manner. Background Technology

[0002] With the explosive growth of electric vehicles and portable electronic devices, lithium-ion batteries (LIBs) have ushered in their first large-scale retirement wave. Waste lithium-ion batteries contain large amounts of valuable metals such as lithium (Li), cobalt (Co), nickel (Ni), and manganese (Mn). Efficient recycling of these batteries not only has enormous economic value but is also a key way to alleviate mineral resource shortages. However, existing waste lithium battery recycling processes (especially the mainstream high-temperature pyrolysis or thermal decomposition pretreatment processes) face significant environmental safety and cost bottlenecks.

[0003] In existing technologies, mainstream high-temperature pyrolysis or thermal decomposition pretreatment processes typically involve pyrolyzing or roasting spent lithium batteries at temperatures of 400–800 °C. However, this process presents a serious problem of releasing highly toxic fluorine-containing waste gases. Under high-temperature conditions, the polyvinylidene fluoride (PVDF) cathode binder and residual lithium hexafluorophosphate (LiPF6) electrolytes widely present in the batteries undergo irreversible thermal decomposition, releasing high concentrations of highly corrosive and toxic fluorine-containing gases such as hydrogen fluoride (HF) and phosphorus pentafluoride (PF5), posing a significant threat to the safety of operators and equipment.

[0004] Furthermore, current technologies for treating fluorine-containing exhaust gases largely rely on "end-of-pipe" treatment techniques such as alkaline spraying. However, these technologies suffer from high treatment costs and a high risk of secondary pollution. These methods place extremely high demands on the corrosion resistance of exhaust gas treatment equipment, resulting in massive initial fixed asset investment. Simultaneously, the treatment process consumes large quantities of alkaline reagents and generates substantial amounts of secondary wastewater that is fluorine-containing, high in salinity, and complex in composition, making subsequent advanced treatment extremely challenging. In addition, traditional pyrometallurgical processes involve high roasting temperatures, typically above 600°C or even exceeding 1000°C, and long roasting times, resulting in both high energy consumption and high carbon emissions.

[0005] In summary, existing methods for recycling and pre-treatment of waste lithium batteries have the following problems: ① significant safety hazards and serious release of fluorine-containing waste gas; ② high end-of-pipe treatment costs and stringent system corrosion prevention requirements; ③ easy to cause secondary pollution and extremely difficult post-treatment; ④ high roasting temperature, resulting in high process energy consumption and carbon emissions. Summary of the Invention

[0006] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a method for the in-situ solidification of fluorine in shrimp shells for low-carbon recycling of waste lithium batteries, thereby solving the technical problems of severe release of fluorine-containing waste gas and high roasting temperature in the recycling process of waste lithium batteries in the prior art.

[0007] To achieve the above-mentioned technical objectives, the technical solution provided by this invention is as follows: In a first aspect, the present invention provides a method for in-situ solid fluorine co-processing and low-carbon recycling of waste lithium batteries using shrimp shells, comprising the following steps: S1, mixing shrimp shell biomass powder with waste lithium battery cathode material uniformly to obtain a material to be reacted; S2, calcining the material to be reacted at 450-600 °C to obtain a solid-phase pyrolysis residue; S3, mixing the solid-phase pyrolysis residue with a leaching agent for leaching treatment, and obtaining a lithium-rich filtrate after separation.

[0008] Compared with the prior art, the beneficial effects of the present invention include: This invention utilizes shrimp shell biomass powder, in which endogenous CaCO3 from the shrimp shell is embedded in a chitin protein matrix in the form of nano / micron-sized particles. After pyrolysis, it forms a natural complex in which calcium is encapsulated / confined by porous carbon. The shrimp shell biomass powder is then uniformly mixed with the cathode material and co-calcined in situ, allowing the active sites of calcium and fluorine diffusion channels to be highly coupled at the micron scale. The confinement of the carbon skeleton and the appropriate alkalinity allow calcium to preferentially abstract fluorine to form stable CaF2, achieving in-situ solidification of fluorine at the source, reducing equipment corrosion and exhaust gas treatment load. At the same time, solidification of fluorine does not interfere with the phase transformation of valuable lithium metal in the cathode, preserving the conversion of lithium to the water-soluble phase and improving the recovery rate. This invention uses a low calcination temperature and shrimp shells as raw material, effectively reducing energy consumption and costs by treating waste with waste. Attached Figure Description

[0009] Figure 1 This is a process flow diagram of a method for the in-situ solid fluorine recycling of waste lithium batteries using shrimp shells in a low-carbon manner, according to the present invention. Detailed Implementation

[0010] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0011] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains; the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the invention; the terms “comprising” and “having”, and any variations thereof, in the specification, claims, and foregoing description of the invention, are intended to cover non-exclusive inclusion.

[0012] 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 the invention. 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.

[0013] To address the shortcomings of current waste lithium battery recycling processes, such as severe fluoride-containing gas release and high roasting temperatures, this invention provides a method for the in-situ solidification of fluoride from shrimp shells in a synergistic low-carbon recovery process. The method utilizes layered porous biochar generated from shrimp shell pyrolysis to in-situ adsorb free gaseous fluoride released during roasting. Furthermore, the endogenous calcium source within the shrimp shell undergoes a highly efficient in-situ heterogeneous chemical reaction with fluoride in a mild, low-to-medium temperature roasting system, converting it at the source into thermodynamically stable solid calcium fluoride (CaF2), which is then retained in the residue. Simultaneously, this process achieves a very high fluoride solidification rate at around 500 °C, significantly reducing pyrolysis energy consumption. Building upon this, as a green synergistic extension of the process, the roasting product can be easily separated and extracted using room-temperature water immersion, achieving efficient extraction of valuable lithium metal without the need for additional complex acid-base reagents. This enables the source interception and in-situ solidification of harmful fluoride-containing waste gas, as well as the low-carbon, high-efficiency recovery of valuable metals.

[0014] Firstly, see [the following] Figure 1 This invention provides a method for the in-situ solidification of fluorine in shrimp shells for low-carbon recycling of waste lithium batteries, comprising the following steps: S1, mix shrimp shell biomass powder with waste lithium battery cathode material evenly to obtain the material to be reacted; S2, the material to be reacted is roasted at 450-600 ℃ to obtain solid pyrolysis residue; S3 involves mixing the solid pyrolysis residue with a leaching agent for leaching treatment, followed by separation to obtain a lithium-rich filtrate.

[0015] Understandably, the solid-phase pyrolysis residue can be ground as needed to improve leaching efficiency. The lithium recovered by this invention is mainly in the lithium-rich filtrate, which can be further processed according to actual needs. For example, adding sodium carbonate can precipitate lithium to obtain lithium carbonate, or it can be used directly as a lithium source.

[0016] In some embodiments, in step S1, the shrimp shell includes at least one of lobster shells and crayfish shells, more preferably crayfish shells. It should be noted that crayfish, originally named *Procambarus clarkii*, have a wide distribution range. Discarded shrimp shells, as a typical type of kitchen waste, are often disposed of through landfill or incineration, which not only occupies land but also easily breeds bacteria and pollutes the environment. Meanwhile, shrimp shells, as natural biomass materials, are naturally rich in endogenous calcium-based components such as calcium carbonate (CaCO3), which can form biochar with a high specific surface area and rich pore structure after pyrolysis. This invention innovatively introduces discarded shrimp shells as a synergistic reactant, utilizing in-situ solid fluorine fixation in shrimp shells to synergistically and low-carbonly recycle waste lithium batteries, constructing a multi-effect synergistic low-carbon recycling path that primarily focuses on waste treatment, in-situ solid fluorine fixation, and supplemented by high-value recycling.

[0017] In some embodiments, in step S1, the shrimp shell biomass powder is the undersize powder that has passed through a 100-mesh sieve.

[0018] In some embodiments, in step S1, the waste lithium batteries include at least one of LiFePO4, lithium nickel cobalt manganese oxide series batteries (NCM111 / 523 / 622 / 811 and lithium-rich manganese-based), lithium cobalt oxide, lithium manganese oxide and lithium nickel cobalt aluminum oxide (NCA) batteries.

[0019] In some embodiments, in step S1, the mass ratio of shrimp shell biomass powder to waste lithium battery cathode material is (1-4):1.

[0020] In some embodiments, in step S2, the calcination process is carried out in a tube furnace, and the calcination atmosphere includes air.

[0021] In some embodiments, in step S2, the heating rate of the calcination process is 3 to 20 °C / min.

[0022] In some embodiments, the calcination time in step S2 is 20 to 60 minutes.

[0023] In some embodiments, in step S3, the leaching agent includes deionized water.

[0024] In some embodiments, in step S3, the ratio between the solid pyrolysis residue and the leaching agent is (5-100) g: 1 L.

[0025] In some embodiments, the leaching conditions in step S3 include: leaching for 5 to 60 minutes under stirring conditions.

[0026] Furthermore, the stirring speed is 200–400 rpm.

[0027] The main mechanism of action and advantages of this invention are as follows: (1) This invention uses shrimp shell biomass powder. The endogenous CaCO3 in the shrimp shell is embedded in the chitin protein matrix in the form of nano / micron particles. After pyrolysis, it forms a natural complex in which calcium is wrapped / confined by porous carbon. The shrimp shell powder is uniformly mixed with the positive electrode material and then co-calcined in situ, so that the active sites of calcium and the fluorine diffusion channels are highly coupled at the micron scale. This invention breaks the traditional end-of-pipe treatment approach and achieves in-situ solidification of fluorine in the source stage in the pyrolysis furnace. It eliminates the serious corrosion of the recovery equipment by the highly toxic HF gas from the source and greatly reduces the load on the subsequent tail gas treatment system.

[0028] (2) As can be seen from the above, the endogenous calcium (CaCO3) in the shrimp shell pyrolyzes to form a porous carbon skeleton, which is a symbiotic natural complex at the microscale. The confinement of the carbon skeleton and the appropriate alkalinity allow the calcium source in the shrimp shell to combine with gaseous fluorine in a directional manner to generate stable CaF2, without interfering with the phase transformation of valuable lithium metal in the positive electrode. This makes the in-situ solid fluorine reaction of the present invention have high phase selectivity, thereby preserving the conversion of lithium to the water-soluble phase and improving the recovery rate.

[0029] (3) Compared with the traditional pyrometallurgical process, the processing temperature of this invention is reduced by at least 50-100 ℃, which has significant energy-saving and carbon-reduction benefits.

[0030] (4) This invention applies kitchen waste to the low-carbon recycling of hazardous waste in new energy. The raw material, crayfish shells, is cheap and readily available, with a cost of almost zero, which truly realizes the economical and high-value utilization of solid waste.

[0031] The present invention will be further described in detail below through specific embodiments. It should be noted that the embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application. Where specific techniques or conditions are not specified in the embodiments, they shall be performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions. Reagents or instruments used that do not specify the manufacturer are all conventional products that can be obtained commercially.

[0032] The raw material for the shrimp shell biomass powder used was the crawfish shell (CS), which was collected in Wuhan, Hubei Province.

[0033] The cathode material from waste lithium batteries comes from NCM622 waste batteries. In order to simulate the state of waste batteries in actual industrial recycling and to standardize the material, the cathode waste was soaked in lithium-ion electrolyte (model: DW-LB019) for 30 minutes and then air-dried naturally as the reaction material for the standardized calcination experiment.

[0034] Example 1 A method for in-situ solidification of fluorine in shrimp shells for low-carbon recycling of waste lithium batteries includes the following steps: S1. Ingredients: Mix shrimp shell biomass powder that has passed through a 100-mesh sieve with waste lithium battery positive electrode material (standardized battery electrode material) at a mass ratio of 2:1 (total mass 3g) to obtain the material to be reacted.

[0035] S2. Calcination: The material to be reacted obtained in step S1 is placed in a tube furnace and heated to 500 ℃ at 5 ℃ / min under air atmosphere, and calcined at a constant temperature for 30 min to obtain solid pyrolysis residue.

[0036] S3, Water leaching: The solid pyrolysis residue collected in step S2 is placed in deionized water for leaching. The liquid-to-solid ratio (g / L) of the leaching is 10. The mechanical stirring is carried out at 300 rpm for 30 min. After leaching, the residue is filtered and the lithium-rich filtrate and leaching residue are collected separately.

[0037] Example 2 A method for in-situ solidification of fluorine in shrimp shells for low-carbon recycling of waste lithium batteries includes the following steps: S1. Ingredients: Mix shrimp shell biomass powder that has passed through a 100-mesh sieve with waste lithium battery cathode material at a mass ratio of 1:1 (total mass 3g) to obtain the material to be reacted.

[0038] S2. Calcination: The material to be reacted obtained in step S1 is placed in a tube furnace and heated to 500 ℃ at 5 ℃ / min under air atmosphere, and calcined at a constant temperature for 30 min to obtain solid pyrolysis residue.

[0039] S3, Water leaching: The solid pyrolysis residue collected in step S2 is placed in deionized water for leaching. The liquid-to-solid ratio (g / L) of the leaching is 10. The mechanical stirring is carried out at 300 rpm for 30 min. After leaching, the residue is filtered and the lithium-rich filtrate and leaching residue are collected separately.

[0040] Example 3 A method for in-situ solidification of fluorine in shrimp shells for low-carbon recycling of waste lithium batteries includes the following steps: S1. Ingredients: Mix shrimp shell biomass powder that has passed through a 100-mesh sieve with waste lithium battery cathode material at a mass ratio of 4:1 (total mass 3g) to obtain the material to be reacted.

[0041] S2. Calcination: The material to be reacted obtained in step S1 is placed in a tube furnace and heated to 500 ℃ at 5 ℃ / min under air atmosphere, and calcined at a constant temperature for 30 min to obtain solid pyrolysis residue.

[0042] S3, Water leaching: The solid pyrolysis residue collected in step S2 is placed in deionized water for leaching. The liquid-to-solid ratio (g / L) of the leaching is 10. The mechanical stirring is carried out at 300 rpm for 30 min. After leaching, the residue is filtered and the lithium-rich filtrate and leaching residue are collected separately.

[0043] Example 4 A method for in-situ solidification of fluorine in shrimp shells for low-carbon recycling of waste lithium batteries includes the following steps: S1. Ingredients: Mix shrimp shell biomass powder that has passed through a 100-mesh sieve with waste lithium battery cathode material at a mass ratio of 2:1 (total mass 3g) to obtain the material to be reacted.

[0044] S2. Calcination: The material to be reacted obtained in step S1 is placed in a tube furnace and heated to 450 ℃ at 5 ℃ / min in air atmosphere, and calcined at a constant temperature for 30 min to obtain solid pyrolysis residue.

[0045] S3, Water leaching: The solid pyrolysis residue collected in step S2 is placed in deionized water for leaching. The liquid-to-solid ratio (g / L) of the leaching is 10. The mechanical stirring is carried out at 300 rpm for 30 min. After leaching, the residue is filtered and the lithium-rich filtrate and leaching residue are collected separately.

[0046] Example 5 A method for in-situ solidification of fluorine in shrimp shells for low-carbon recycling of waste lithium batteries includes the following steps: S1. Ingredients: Mix shrimp shell biomass powder that has passed through a 100-mesh sieve with waste lithium battery cathode material at a mass ratio of 2:1 (total mass 3g) to obtain the material to be reacted.

[0047] S2. Calcination: The material to be reacted obtained in step S1 is placed in a tube furnace and heated to 550 ℃ at 5 ℃ / min under air atmosphere, and calcined at a constant temperature for 30 min to obtain solid pyrolysis residue.

[0048] S3, Water leaching: The solid pyrolysis residue collected in step S2 is placed in deionized water for leaching. The liquid-to-solid ratio (g / L) of the leaching is 10. The mechanical stirring is carried out at 300 rpm for 30 min. After leaching, the residue is filtered and the lithium-rich filtrate and leaching residue are collected separately.

[0049] Example 6 A method for in-situ solidification of fluorine in shrimp shells for low-carbon recycling of waste lithium batteries includes the following steps: S1. Ingredients: Mix shrimp shell biomass powder that has passed through a 100-mesh sieve with waste lithium battery cathode material at a mass ratio of 2:1 (total mass 3g) to obtain the material to be reacted.

[0050] S2. Calcination: The material to be reacted obtained in step S1 is placed in a tube furnace and heated to 600 ℃ at 5 ℃ / min in air atmosphere, and calcined at a constant temperature for 30 min to obtain solid pyrolysis residue.

[0051] S3, Water leaching: The solid pyrolysis residue collected in step S2 is placed in deionized water for leaching. The liquid-to-solid ratio (g / L) of the leaching is 10. The mechanical stirring is carried out at 300 rpm for 30 min. After leaching, the residue is filtered and the lithium-rich filtrate and leaching residue are collected separately.

[0052] Comparative Example 1 The only difference between this comparative example and Example 1 is that the mass ratio of shrimp shell biomass powder to waste lithium battery cathode material in step S1 is adjusted to 0.5:1. The other steps and conditions are the same as in Example 1.

[0053] Comparative Example 2 The only difference between this comparative example and Example 1 is that the shrimp shell biomass powder in step S1 is removed, i.e., the reactant is 3g of pure waste lithium battery cathode material. The other steps and conditions are the same as in Example 1.

[0054] Comparative Example 3 The only difference between this comparative example and Example 1 is that in step S1, pure biochar without endogenous calcium is used instead of shrimp shell biochar powder. Specifically, coconut shell activated carbon powder that has passed through a 100-mesh sieve is mixed with waste lithium battery cathode material at a mass ratio of 2:1. Other steps and conditions are the same as in Example 1.

[0055] Comparative Example 4 The only difference between this comparative example and Example 1 is that commercial calcium carbonate (CaCO3) powder is used instead of shrimp shell biomass powder in step S1. Specifically, commercial analytical grade CaCO3 powder (passed through 100 mesh) is mixed with waste lithium battery cathode material at a mass ratio of 2:1. Other steps and conditions are the same as in Example 1.

[0056] Comparative Example 5 The only difference between this comparative example and Example 1 is that the shrimp shell biomass powder and the waste lithium battery cathode material are calcined separately in different areas. Specifically, the shrimp shell biomass powder and the waste lithium battery cathode material are taken in the same ratio (2:1), but placed in different areas of the quartz boat of the tubular furnace and not mixed. The other steps and conditions are the same as in Example 1.

[0057] Performance testing (1) Test Item Description In-situ curing rate of gas-phase fluoride: All trace amounts of tail gas generated during the calcination process in step S2 are introduced into the sodium hydroxide absorbent. After the reaction is complete, the fluoride ion concentration C in the absorbent is strictly determined according to the national standard GB7484-87 (ion-selective electrode method). absorbedThe total mass of fluorine in the gas phase captured was determined by combining the total volume of the absorbent with the total volume of the absorbent solution. m g The total amount of F released was determined by setting a blank group. m total_F The in-situ curing rate of gaseous fluorine is determined according to the following formula. R F (%).

[0058]

[0059] Lithium recovery rate: The mass of lithium in the lithium-rich filtrate and the washed filter residue obtained in step S3 was determined by flame atomic absorption spectrometry (AAS), and recorded as follows: m Li_fluid (mg) and m Li_residue (mg), water leaching rate of lithium η Li The calculation formula for (%) is as follows:

[0060] (2) Test results The results of the in-situ solidification rate of gas-phase fluorine and the synergistic recovery rate of lithium in water immersion in Examples 1-6 and Comparative Examples 1-5 are shown in Table 1 below.

[0061] Table 1. Test results of Examples 1-6 and Comparative Examples 1-5

[0062] As shown in Table 1, the samples treated by the methods in Examples 1-6 of this invention exhibit high in-situ solidification rates of gas-phase fluorine and good synergistic lithium recovery rates from water leaching. Example 1 achieved an excellent fluorine removal rate of 90.15%. At a synergistic calcination temperature of 500 °C, the highly active volatiles and biochar released from waste shrimp shells not only enhanced the chemical adsorption barrier to free fluorine within the micro-region but also induced a directional mineralization phase transition of lithium in the cathode material. Due to the high phase selectivity of the solidification reaction, the endogenous calcium in the system preferentially extracts fluorine from the gas phase, generating thermodynamically extremely stable insoluble CaF2. This, to a certain extent, prevents the disordered solidification of lithium, promoting the conversion of lithium into a water-soluble compound form. Therefore, in the subsequent room-temperature pure water leaching, valuable lithium metal is rapidly released without being encapsulated or interfered with by fluorides, achieving a high recovery rate of 94.35%. Considering both benefits and cost, Example 1 is the optimal embodiment.

[0063] Increasing the proportion in Example 3 and significantly increasing the temperature in Example 6 did not result in a significant linear increase in the solidification rate of fluorine, and even affected the lithium recovery rate. In Comparative Example 1, the amount of shrimp shell biomass powder was insufficient, and the in-situ solidification rate of gas-phase fluorine decreased significantly. Therefore, in this invention, the mass ratio of shrimp shell biomass powder to waste lithium battery cathode material is (1-4):1, and more preferably (2-4):1; the calcination temperature is 450-600 ℃, and more preferably 450-550 ℃.

[0064] In Comparative Example 2, removing the shrimp shell biomass powder completely eliminated the fluoride fixation effect. In Comparative Example 3, the synergistic water immersion lithium recovery rate was high, but the in-situ solidification rate of gas-phase fluoride was low. This was mainly because it was only physically adsorbed and easily desorbed and released after pyrolysis. This indicates that when pure biomass char without endogenous calcium is used, lithium phase transformation still occurs, but fluoride is not fixed. In Comparative Example 4, commercial calcium carbonate was used, and both the in-situ solidification rate of gas-phase fluoride and the lithium recovery rate were low. This shows that shrimp shells are a natural composite material symbiotic at the microscale of "porous carbon skeleton formed by the pyrolysis of endogenous calcium (CaCO3) + chitin", which cannot be replaced by any carbon- or calcium-containing substance.

[0065] The solidification effect of partitioned isolation in Comparative Example 5 is significantly less than that of complete mixing in Example 1.

[0066] In summary, this invention utilizes shrimp shell biomass powder. The endogenous CaCO3 from the shrimp shell is embedded in a chitin protein matrix in nano / micron-sized particles. After pyrolysis, it forms a natural complex where calcium is encapsulated / confined by porous carbon. Furthermore, the shrimp shell powder is uniformly mixed with the cathode material and then co-calcined in situ. This allows for a high degree of coupling between the calcium active sites and fluorine diffusion channels at the micron scale. The confinement of the carbon skeleton and the appropriate alkalinity allow calcium to preferentially abstract fluorine to form stable CaF2, preventing disordered co-solidification with lithium, thus preserving the conversion of lithium to the water-soluble phase. In other words, this invention enables in-situ solidification of fluorine at the source, reducing equipment corrosion and exhaust gas treatment load. Simultaneously, fluorine solidification does not interfere with the phase transition of valuable lithium metal in the cathode, preserving the conversion of lithium to the water-soluble phase and improving recovery rate. This invention also features a low calcination temperature and uses shrimp shells as raw material, effectively reducing energy consumption and costs by using waste to treat waste.

[0067] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for recovering waste lithium batteries with low carbon by in-situ fluorine fixation using shrimp shells, characterized in that, Includes the following steps: S1, mix shrimp shell biomass powder with waste lithium battery cathode material evenly to obtain the material to be reacted; S2, the material to be reacted is roasted at 450-600 ℃ to obtain solid pyrolysis residue; S3 involves mixing the solid pyrolysis residue with a leaching agent for leaching treatment, followed by separation to obtain a lithium-rich filtrate.

2. The method for in-situ solid fluorine fixation and low-carbon recycling of waste lithium batteries using shrimp shells according to claim 1, characterized in that, In step S1, the shrimp shell includes at least one of lobster shell and crayfish shell; The shrimp shell biomass powder is the powder that passed through a 100-mesh sieve; The waste lithium batteries include at least one of LiFePO4, lithium nickel cobalt manganese oxide, lithium cobalt oxide, lithium manganese oxide, and lithium nickel cobalt aluminum oxide batteries.

3. The method for in-situ solid fluorine fixation and low-carbon recycling of waste lithium batteries using shrimp shells according to claim 1, characterized in that, In step S1, the mass ratio of the shrimp shell biomass powder to the waste lithium battery cathode material is (1-4):

1.

4. The method for in-situ solid fluorine fixation and low-carbon recycling of waste lithium batteries using shrimp shells as described in claim 1, characterized in that, In step S2, the roasting process is carried out in a tube furnace, and the roasting atmosphere includes air.

5. The method for in-situ solid fluorine fixation and low-carbon recycling of waste lithium batteries using shrimp shells according to claim 1, characterized in that, In step S2, the heating rate of the calcination treatment is 3 to 20 °C / min.

6. The method for in-situ solid fluorine fixation and low-carbon recycling of waste lithium batteries using shrimp shells according to claim 1, characterized in that, In step S2, the roasting time is 20 to 60 minutes.

7. The method for in-situ solid fluorine fixation and low-carbon recycling of waste lithium batteries using shrimp shells according to claim 1, characterized in that, In step S3, the leaching agent includes deionized water.

8. The method for in-situ solid fluorine fixation and low-carbon recycling of waste lithium batteries using shrimp shells according to claim 1, characterized in that, In step S3, the ratio between the solid pyrolysis residue and the leaching agent is (5-100) g: 1 L.

9. The method for in-situ solid fluorine fixation and low-carbon recycling of waste lithium batteries using shrimp shells according to claim 1, characterized in that, In step S3, the leaching conditions include: leaching for 5 to 60 minutes under stirring conditions.

10. The method for in-situ solid fluorine fixation and low-carbon recycling of waste lithium batteries using shrimp shells according to claim 9, characterized in that, The stirring speed is 200–400 rpm.

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