Method for recovering lithium element extracted from waste battery electrolyte

Abstract

The invention discloses a method for recovering lithium element in waste battery electrolyte, which comprises the following steps: firstly, safely disassembling a waste battery and preliminarily extracting the electrolyte through a mechanical cutting and crushing technology, and strictly controlling the temperature in the process to avoid the release of harmful gas and ensure the safety and cleanness of the operation environment; then, a low-temperature freezing technology is adopted, and the solvent curing process in the electrolyte is accurately controlled; under the combined action of the uniform dispersion of the catalyst and the microwave heating technology, the chemical reaction in the electrolyte is obviously accelerated, so that the recovery efficiency is improved, and the purity and quality of the product are ensured; the uniformity and high efficiency of microwave heating are combined with the enhanced mixing effect of mechanical stirring to jointly promote sufficient precipitation of metal salt in the electrolyte, and favorable conditions are created for subsequent separation work; and finally, accurately separating the metal salt and the organic solvent through a chemical precipitation method, and purifying the organic solvent by utilizing a distillation technology to obtain a high-purity product.

Description

Technical Field

[0001] The invention relates to the technical field of waste battery treatment, and in particular to a method for recovering lithium elements from electrolyte of waste batteries. Background Art

[0002] With the transformation of the global energy structure and the rapid development of the new energy industry, lithium, as a key strategic resource, has become increasingly important. Lithium is not only widely used in battery manufacturing, new energy vehicles, energy storage systems and other fields, but also plays an important role in many industries such as medicine and chemical industry. However, the natural reserves of lithium resources are limited and unevenly distributed, and the high cost of mining and extraction makes the sustainable use of lithium resources an urgent problem to be solved.

[0003] The recycling of lithium resources, especially the recovery of lithium from metal salt-containing precipitates, is of great economic and environmental significance. Such precipitates usually come from wastewater treatment, waste recycling and other links in industrial production processes, which are rich in various metal ions, including lithium. However, due to the complex composition of the precipitate, the low content of lithium, and the interference of other metal ions, the recovery of lithium is more difficult.

[0004] However, it is not easy to recover lithium from such precipitates. Due to the complex composition of the precipitates, the relatively low content of lithium, and the serious interference of other metal ions, traditional recovery methods such as low-temperature decomposition and solvent extraction are simple in process, but have problems such as difficult to accurately control process conditions, low recovery rate, and difficulty in effectively separating and recovering valuable products. These problems not only limit the efficiency and purity of lithium recovery, but also increase production costs and the risk of environmental pollution.

[0005] Therefore, it is necessary to provide a method for recovering lithium from waste battery electrolyte to solve the above technical problems. Summary of the invention

[0006] The invention overcomes the shortcomings of the prior art and provides a method for recovering lithium elements from waste battery electrolyte.

[0007] To achieve the above object, the technical solution adopted by the present invention is: a method for recovering lithium from waste battery electrolyte, comprising the following steps:

[0008] S1: Dismantle the waste batteries and use mechanical methods such as cutting and crushing to safely open the battery shell and contact the electrolyte, and use physical methods to initially extract the electrolyte under low temperature conditions;

[0009] S2: Using a low-temperature freezing method, the electrolyte is exposed to a low-temperature environment to partially solidify the solvent in the electrolyte;

[0010] S3: Dispersing the catalyst evenly in the electrolyte;

[0011] S4: Use microwave heating technology to uniformly heat the electrolyte;

[0012] S5: Use mechanical stirring simultaneously during microwave heating;

[0013] S6: After the pyrolysis and stirring process is completed, the valuable metal salts and organic solvents are separated by a chemical precipitation method, the separated organic solvent is distilled and purified, and the decomposed metal salts are chemically converted into high-purity lithium salts.

[0014] In a preferred embodiment of the present invention, in said S1, the low temperature range is -10--50°C, the physical method is centrifugation, and the centrifuge speed range is 3000-5000rpm.

[0015] In a preferred embodiment of the present invention, in said S2, the low temperature range of the low temperature freezing method is -10--40°C, and the low temperature time range is 2-4h.

[0016] In a preferred embodiment of the present invention, in S3, the catalyst includes but is not limited to metal oxides or ion exchange resins.

[0017] In a preferred embodiment of the present invention, in said S3, the mass ratio of the catalyst to the electrolyte is in the range of 1-10:1-50.

[0018] In a preferred embodiment of the present invention, in S4, the microwave heating temperature ranges from 60 to 80° C., and the microwave heating time ranges from 10 to 20 min.

[0019] In a preferred embodiment of the present invention, in said S4, the microwave frequency is 2000-3000 MHz.

[0020] In a preferred embodiment of the present invention, in S5, the mechanical stirring speed ranges from 500 to 1000 rpm, and the stirring time ranges from 15 to 30 min.

[0021] In a preferred embodiment of the present invention, in said S6, distillation and purification are performed, and the distillation temperature is 70-150°C.

[0022] In a preferred embodiment of the present invention, in S6, the chemical conversion operation is a method such as precipitation, crystallization or ion exchange.

[0023] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0024] (1) The present invention provides a method for recovering lithium from waste battery electrolyte. By combining advanced technical means such as low-temperature freezing, catalyst assistance, microwave heating, and chemical precipitation, the present invention effectively solves the problems of low lithium content, strong interference from other metal ions, and low recovery rate in traditional recovery methods. In particular, the introduction of microwave heating technology can achieve uniform and rapid heating of the electrolyte, promote the chemical conversion and separation of lithium elements, and thus significantly improve the recovery efficiency and purity of lithium elements. This is of great significance for improving the utilization rate of lithium resources and reducing production costs.

[0025] (2) In the present invention, the recovery method not only improves the recovery efficiency of lithium elements, but also reduces energy consumption and material consumption in the production process by optimizing process parameters and using environmentally friendly catalysts. At the same time, the separated organic solvent is distilled and purified to achieve resource recycling and reduce waste emissions. These measures work together to effectively reduce production costs and environmental pollution risks, which is in line with the concept of green and sustainable development.

[0026] (3) In the present invention, the recovery method sets clear process parameter ranges in each step, such as low-temperature freezing temperature, microwave heating temperature and time, stirring speed, etc. The precise control of these parameters makes the entire recovery process more stable and controllable; in addition, by introducing advanced technologies such as catalysts and microwave heating, the stability and efficiency of the process are further enhanced, and the difficulty of operation and error rate are reduced. This provides a strong guarantee for industrial production and ensures the quality and consistency of the recovered products. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0028] Figure 1 It is a flow chart of a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0029] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0031] like Figure 1 As shown, the present invention provides a method for recovering lithium from waste battery electrolyte, comprising the following steps:

[0032] S1: Dismantle the waste battery, use mechanical methods such as cutting and crushing to safely open the battery shell and contact the electrolyte, and use physical methods to initially extract the electrolyte under low temperature conditions. The low temperature range is -10--50℃. The physical method is centrifugation, and the centrifuge speed range is 3000-5000rpm;

[0033] S2: Using the low-temperature freezing method, the electrolyte is exposed to a low-temperature environment to partially solidify the solvent in the electrolyte. The low-temperature range of the low-temperature freezing method is -10--40°C, and the low-temperature time range is 2-4h;

[0034] S3: uniformly dispersing a catalyst in an electrolyte, wherein the catalyst includes but is not limited to a metal oxide or an ion exchange resin, and a mass ratio of the catalyst to the electrolyte is in a range of 1-10:1-50;

[0035] S4: using microwave heating technology to uniformly heat the electrolyte, the microwave heating temperature range is 60-80°C, the microwave heating time range is 10-20min, and the microwave frequency is 2000-3000MHz;

[0036] S5: Mechanical stirring is used during microwave heating, the mechanical stirring speed ranges from 500-1000 rpm, and the stirring time ranges from 15-30 min;

[0037] S6: After the pyrolysis and stirring processes are completed, the valuable metal salts and organic solvents are separated by chemical precipitation. The separated organic solvent is distilled and purified. The distillation temperature is 70-150°C. The decomposed metal salts are chemically converted into high-purity lithium salts by precipitation, crystallization or ion exchange.

[0038] It should be noted that:

[0039] Step S1 achieves safe disassembly of waste batteries through mechanical methods of cutting and crushing, effectively avoiding potential safety hazards such as short circuits and explosions that may occur when handling complete batteries. At the same time, the use of physical centrifugation technology to initially extract the electrolyte in a low-temperature environment not only significantly reduces the volatilization of the electrolyte and the release of harmful gases, but also ensures the relative stability of the electrolyte; the high-speed rotation of the centrifuge further demonstrates its advantage of efficient separation, separating the solid impurities in the electrolyte from the liquid components, greatly improving the purity of the electrolyte, and laying a solid foundation for subsequent resource recovery;

[0040] The S2 step uses a low-temperature freezing method to partially solidify the solvent in the electrolyte, which not only greatly promotes the effective separation of metal salts and organic solvents in the subsequent process and significantly improves the recovery efficiency, but also effectively curbs the volatilization of the electrolyte by maintaining a low-temperature environment, thereby significantly reducing the potential risk of environmental pollution; in addition, by controlling the time and temperature range of low-temperature treatment, the degree of solvent solidification can be accurately grasped, paving the way for subsequent recovery and treatment work and ensuring the smooth progress of the entire process;

[0041] The S3 step introduces the use of catalysts, which significantly accelerates the decomposition and conversion process of harmful substances in the electrolyte, not only improving the overall efficiency of recycling, but also ensuring the quality of the recycled products; the uniform mixing of the catalyst in the electrolyte ensures that it can play a comprehensive and efficient role, further improving the reaction efficiency and product purity, adding an important link to the environmentally friendly and efficient battery recycling process;

[0042] The S4 step uses advanced microwave heating technology to achieve rapid and uniform heating of the electrolyte, completely solving the temperature gradient problem common in traditional heating methods, thereby significantly improving heating efficiency and uniformity. In addition, microwave heating does not rely on heat conduction media, effectively reducing energy loss during the transmission process and avoiding harmful gas emissions that may be caused by traditional heating, reflecting its significant advantages in energy conservation and environmental protection; more importantly, by controlling the heating temperature, microwave heating technology promotes the acceleration of chemical reactions in the electrolyte, providing strong support for the efficient separation of metal salts and organic solvents, and further promoting the optimization and upgrading of the battery recycling process;

[0043] Step S5 combines the dual advantages of mechanical stirring and microwave heating. By strengthening the mixing effect, it not only significantly improves the rate of chemical reactions in the electrolyte, but also ensures the uniformity of the products, laying the foundation for efficient recovery. Appropriate stirring speed and time settings effectively prevent the precipitation of solid particles in the electrolyte, maintain the continuous stability of the reaction system, and ensure the smooth recovery process. The synergistic effect of stirring and heating, like a catalyst, greatly improves the yield and purity of the recovered products, making the entire recovery process more efficient and reliable.

[0044] The S6 step is a key link in the entire recycling process. It uses a chemical precipitation method to achieve effective separation of metal salts and organic solvents in the electrolyte, which not only promotes the classification and recycling of resources, but also lays a solid foundation for subsequent high-value utilization. Through fine distillation and purification of the separated organic solvents, high-purity organic solvent products can be produced to meet market demand. At the same time, chemical conversion of metal salts can produce chemicals with significant economic value such as high-purity lithium salts. In addition, the S6 step has always taken environmental protection and emission reduction as its core concept. Through a series of efficient separation and purification technologies, it has greatly reduced the generation and emission of waste, effectively reduced the negative impact on the environment, and demonstrated the advanced concept of green recycling.

[0045] In summary, the method for recovering lithium from waste battery electrolyte achieves the optimization of the entire process from safe disassembly of waste batteries to efficient extraction of electrolyte, and then to precise separation of metal salts and organic solvents through a series of steps; the method effectively avoids the safety hazards when handling complete batteries in step S1, and improves the purity of the electrolyte through low-temperature centrifugation technology; the low-temperature freezing method in step S2 further promotes solvent solidification and metal salt separation, reducing the risk of environmental pollution; the combination of catalyst and microwave heating technology in steps S3 and S4 significantly accelerates the decomposition and chemical reaction of harmful substances, and improves the recovery efficiency and product quality; the synergistic effect of mechanical stirring and microwave heating in step S5 strengthens the mixing effect, ensuring the stability of the reaction system and the uniformity of the product; finally, the chemical precipitation and purification technology in step S6 realizes the classified recovery and high-value utilization of resources, reflecting the concept of environmental protection and efficient recovery.

[0046] Embodiment 1:

[0047] S1: Disassembly of waste batteries and preliminary electrolyte extraction

[0048] Preparation: Select a batch of discarded lithium-ion batteries as the objects to be processed, and ensure that the batteries are fully discharged and the shells are not damaged. Prepare disassembly tools, including electric cutters, crushers, gloves, goggles, and gas masks.

[0049] Safe disassembly: In a well-ventilated professional disassembly room, first use an electric cutter to cut along the seams of the battery shell and gradually open the battery shell; use a crusher to further crush the internal components of the battery to initially separate the electrolyte from the solid materials.

[0050] Low-temperature preliminary extraction: The crushed battery mixture is quickly transferred to a container equipped with a low-temperature cooling system and the temperature is controlled at -20°C. The mixture is centrifuged at 4000 rpm for 30 minutes; during this process, most of the electrolyte is separated from the solid impurities due to the centrifugal force, and the electrolyte after centrifugation is collected for the next step of processing.

[0051] S2: Low temperature freezing solidification solvent

[0052] Low temperature environment setting: Transfer the collected electrolyte to a special low temperature freezing device, set the temperature to -30℃, and ensure that the temperature in the device is evenly distributed.

[0053] Freeze solidification: Expose the electrolyte to a low-temperature environment for 3 hours, periodically checking the temperature changes to ensure that the temperature is stable within the set range; during this process, the solvent portion of the electrolyte will gradually solidify to form a solid-liquid mixture.

[0054] S3: Catalyst addition and mixing

[0055] Catalyst selection: Metal oxide catalyst: manganese dioxide, as a medium to accelerate decomposition; the mass ratio of catalyst to electrolyte was set at 5:25.

[0056] Uniform dispersion: Slowly add the manganese dioxide catalyst powder into the electrolyte and use a mechanical stirrer to perform preliminary stirring at a speed of 300 rpm to ensure that the catalyst is evenly dispersed in the electrolyte; the stirring time is controlled within 10 minutes to avoid excessive stirring to generate foam.

[0057] S4: Microwave heating to promote reaction

[0058] Preparation of microwave heating equipment: Transfer the electrolyte containing manganese dioxide catalyst to a reactor suitable for microwave heating. The reactor should be resistant to high temperature, corrosion and have good microwave transmittance.

[0059] Heating process: Set the power and frequency of the microwave heating equipment to quickly raise the temperature of the reactor to 70°C and maintain this temperature range for 15 minutes; the microwave frequency is set to 2450MHz to ensure uniform heating. During the heating process, closely observe the temperature changes and reaction conditions and adjust the heating parameters in a timely manner.

[0060] S5: Intensive mixing and stirring

[0061] Stirring equipment connection: While heating with microwave, connect a mechanical stirrer to the reactor and set the stirring speed to 800 rpm.

[0062] Synergistic effect: The stirrer starts working and continuously stirs the electrolyte at a speed of 800 rpm for 20 minutes. During the stirring process, microwave heating and mechanical stirring work synergistically to accelerate the chemical reaction rate in the electrolyte and ensure uniform mixing of the reactants.

[0063] S6: Chemical precipitation separation and purification

[0064] Chemical precipitation: Add an appropriate amount of precipitant sodium carbonate to the heated and stirred electrolyte to convert the metal ions into insoluble carbonate precipitates; at the same time, adjust the pH value to optimize the precipitation effect.

[0065] Solid-liquid separation: Separate the precipitate from the organic solvent by centrifugation; collect the organic solvent for subsequent distillation purification. The distillation temperature is set at 100°C and the distillation is continued until a high-purity organic solvent product is obtained.

[0066] Metal salt conversion: The metal salt in the precipitate is dissolved, precipitated, crystallized or ion exchanged to finally prepare high-purity lithium salt.

[0067] Comparative Example 1:

[0068] The electrolyte is recovered using a low-temperature decomposition method: in a semi-separated state of the battery, it is baked at a lower temperature to decompose the electrolyte at a lower temperature, and then the decomposition products are recovered.

[0069] Comparative Example 2:

[0070] The electrolyte is recovered by solvent extraction: the electrolyte is extracted with a solvent, the extracted liquid is decomposed at a lower temperature, and the solvent is separated by distillation. The solvent can be recycled, and the electrolyte decomposition products can be recovered by acid absorption.

[0071] Experiment 1:

[0072] 1. Experimental Preparation

[0073] Sample preparation: precipitates (containing metal salts) collected from Example 1, Comparative Example 1 and Comparative Example 2 and purified lithium salt samples;

[0074] Original sediment mass (m1): 100g.

[0075] Experimental equipment: electronic balance, oven, or high-temperature furnace, ICP-MS (inductively coupled plasma mass spectrometer, used to accurately determine the content of metal elements).

[0076] 2. Experimental Procedure

[0077] 2.1 Sediment treatment

[0078] The precipitate was dried to remove moisture, and the mass change before and after drying was recorded.

[0079] The dried precipitate is dissolved and converted into a solution form that can be analyzed;

[0080] The mass loss during the drying process is very small, and the mass of the precipitate after drying (m2) is still 100g.

[0081] 2.2 Lithium salt sample treatment

[0082] The purified lithium salt sample was subjected to the same drying and dissolution treatment.

[0083] 2.3 Element content determination

[0084] Use ICP-MS or other high-precision instruments to measure the lithium content in the treated sediment solution and the lithium salt sample solution respectively;

[0085] The mass of lithium in the precipitate solution determined by CP-MS (m Li,1 ): 1000mg

[0086] Example 1: The mass of lithium in the lithium salt sample solution measured by ICP-MS (m Li,2 ): 950mg;

[0087] Comparative Example 1: The mass of lithium in the lithium salt sample solution determined by ICP-MS (m Li,2 ): 890mg

[0088] Comparative Example 2: The mass of lithium in the lithium salt sample solution determined by ICP-MS (m Li,2 ): 930mg.

[0089] Recovery calculation

[0090] The mass of lithium recovered from the precipitate should be equal to the mass of lithium in the purified lithium salt.

[0091] The recovery rate (R) is calculated as follows:

[0092]

[0093] in, Represents the purification efficiency, Represents the correction factor for mass loss during drying.

[0094] Substitute the numerical value of Example 1 into the formula:

[0095]

[0096] Substitute the numerical value of Example 1 into the formula:

[0097]

[0098] Substitute the values ​​of Example 2 into the formula:

[0099]

[0100] According to these values, it can be concluded that in Example 1, the recovery rate of lithium salt reached 95%, in Comparative Example 1, the recovery rate of lithium salt reached 89%, and in Comparative Example 2, the recovery rate of lithium salt reached 93%;

[0101] In summary:

[0102] The drying, dissolution and ICP-MS determination methods used in this experiment all showed good reliability and accuracy. Their effective application provided a solid foundation for accurately determining the lithium content and calculating the recovery rate.

[0103] The effect of Example 1 is the best: Among all experimental conditions, Example 1 shows the best lithium recovery effect. Specifically, under the same original precipitate mass, the mass of lithium in the lithium salt sample after purification in Example 1 is closest to the mass of lithium in the original precipitate, and the calculated recovery rate is as high as 95%. This result is not only higher than Comparative Example 1 (89%) and Comparative Example 2 (93%), but also fully proves the efficiency and stability of the purification process under the experimental conditions.

[0104] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A method for recovering lithium from waste battery electrolyte, characterized in that: The following steps are involved: S1: Dismantle the waste batteries and use mechanical methods such as cutting and crushing to safely open the battery shell and contact the electrolyte, and use physical methods to initially extract the electrolyte under low temperature conditions; S2: Using a low-temperature freezing method, the electrolyte is exposed to a low-temperature environment to partially solidify the solvent in the electrolyte; S3: Dispersing the catalyst evenly in the electrolyte; S4: Use microwave heating technology to uniformly heat the electrolyte; S5: Use mechanical stirring simultaneously during microwave heating; S6: After the pyrolysis and stirring process is completed, the valuable metal salts and organic solvents are separated by a chemical precipitation method, the separated organic solvent is distilled and purified, and the decomposed metal salts are chemically converted into high-purity lithium salts.

2. The method for recovering lithium from waste battery electrolyte according to claim 1, characterized in that: In the S1, the low temperature range is -10--50°C, the physical method is centrifugation, and the centrifuge speed range is 3000-5000rpm.

3. The method for recovering lithium from waste battery electrolyte according to claim 1, characterized in that: In the S2, the low temperature range of the low temperature freezing method is -10--40°C, and the low temperature time range is 2-4h.

4. The method for recovering lithium from waste battery electrolyte according to claim 1, characterized in that: In S3, the catalyst includes but is not limited to metal oxides or ion exchange resins.

5. The method for recovering lithium from waste battery electrolyte according to claim 1, characterized in that: In the S3, the mass ratio of the catalyst to the electrolyte is in the range of 1-10:1-50.

6. The method for recovering lithium from waste battery electrolyte according to claim 1, characterized in that: In the step S4, the microwave heating temperature is in the range of 60-80°C, and the microwave heating time is in the range of 10-20 min.

7. The method for recovering lithium from waste battery electrolyte according to claim 1, characterized in that: In said S4, the microwave frequency is 2000-3000 MHz.

8. The method for recovering lithium from waste battery electrolyte according to claim 1, characterized in that: In the step S5, the mechanical stirring speed ranges from 500 to 1000 rpm, and the stirring time ranges from 15 to 30 min.

9. The method for recovering lithium from waste battery electrolyte according to claim 1, characterized in that: In S6, distillation is performed for purification, and the distillation temperature is 70-150°C.

10. The method for recovering lithium from waste battery electrolyte according to claim 1, characterized in that: In S6, the chemical conversion operation is a method such as precipitation, crystallization or ion exchange.

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