Method for dissolving and crystallizing waste lithium battery

Abstract

The invention discloses a method for dissolving and crystallizing a waste lithium battery, which comprises the following steps: S1, crushing and sorting the waste lithium battery to obtain a first material containing metal; s2, the first material enters a blending machine system to be blended, and a second material is obtained; s3, the second material enters a roasting system to be roasted, and a roasted material is obtained; and S4, the roasted material enters a dissolving tank to be dissolved, and metal lithium is obtained. According to the method for dissolving and crystallizing the waste lithium battery, the waste lithium battery is subjected to working procedure treatment such as electrolyte preheating and decomposition, crushing and screening, roasting and dissolving, valuable metal lithium can be extracted, the automation degree of the waste lithium battery treatment process can be improved, the labor intensity of the production process can be reduced, and the production efficiency can be improved. And the treatment efficiency and the recycling rate of the waste lithium battery are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium batteries, and in particular, relates to a method for realizing dissolution and crystallization of waste lithium batteries. Background Art

[0002] With the rapid development of the new energy vehicle industry, the demand for lithium batteries for vehicles is increasing, and a large number of waste lithium batteries are also generated. If these waste lithium batteries are not properly handled, they will not only pollute the environment, but also waste precious resources. Therefore, the recycling technology of waste lithium batteries has become one of the current research hotspots.

[0003] At present, there are several main technologies for recycling and treating waste lithium batteries, including low-temperature pyrolysis technology, high-temperature pyrolysis technology, gradient pyrolysis technology, oxygen-free carbonization pyrolysis technology, solvent pyrolysis technology, gas-driven stripping and sorting technology, and multi-stage pyrolysis technology. These technologies are of great significance in achieving the effective recycling and resource reuse of waste lithium batteries, but in practical applications, they generally face challenges in terms of technology, cost, environmental protection treatment efficiency, and recovery rate.

[0004] Although the current treatment of waste lithium batteries has achieved certain results, there are mainly the following defects in actual use:

[0005] 1. Low recycling efficiency: Current dissolution recycling technology may not be able to fully recover all valuable components in waste lithium batteries, especially metal elements such as lithium, cobalt, and nickel. Insufficient recycling rate will lead to waste of resources.

[0006] 2. Insufficient metal purity: During the dissolution and crystallization process, impurities and unwanted metal ions may exist, which will affect the purity of the final recovered metal. Insufficient purity will reduce the utilization value of the recovered metal.

[0007] 3. High technical complexity: Multi-step process: The dissolution crystallization process may involve multiple steps, including pretreatment, dissolution, separation, crystallization, etc. These steps need to be precisely controlled to ensure the recovery effect. The complex process increases the difficulty and cost of operation. Summary of the invention

[0008] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides a method for dissolving and crystallizing waste lithium batteries, the purpose of which is to increase the utilization value of recovered metals.

[0009] In order to achieve the above object, the technical solution adopted by the present invention is: a method for dissolving and crystallizing waste lithium batteries, comprising the steps of:

[0010] S1. After crushing and sorting the waste lithium batteries, a first material containing metal is obtained;

[0011] S2, the first material enters the crushing machine system for crushing to obtain the second material;

[0012] S3, the second material enters the roasting system for calcination to obtain a roasting material;

[0013] S4. The calcined material enters a dissolving tank for dissolution to obtain metallic lithium.

[0014] The crushing system includes a crushing machine, and a plurality of crushing machines are provided.

[0015] In the step S2, the first material is transported to the crusher system through the crusher feeding system.

[0016] The crusher feeding system includes a weighing scale, a first conveyor for receiving the first material from the weighing scale, a second conveyor for receiving the first material from the first conveyor, and a third conveyor for receiving the first material from the second conveyor, and the crusher receives the first material from the third conveyor.

[0017] The startup process of the crusher feeding system comprises the following steps:

[0018] Step 1: starting the third conveyor;

[0019] Step 2: starting the second conveyor;

[0020] Step 3: starting the first conveyor;

[0021] Step 4: Start the measuring scale.

[0022] In step S2, the process of the first material entering the crushing machine system includes the following steps:

[0023] S201, turning on the measuring scale and starting timing at the same time;

[0024] S202, opening the feed valve of the crushing machine to feed the crushing machine;

[0025] S203, the feed valve of the crusher is closed.

[0026] In the step S3, the second material is transported to the roasting system through a roasting kiln feeding system.

[0027] The feeding system for entering the roasting kiln includes a fourth conveyor for receiving the second material crushed by the crushing machine system, a fifth conveyor for receiving the second material from the fourth conveyor, and a sixth conveyor for receiving the second material from the fifth conveyor. The roasting system receives the second material from the sixth conveyor.

[0028] The step S4 comprises:

[0029] S401, opening the water inlet valve of the dissolution tank to replenish water to the dissolution tank;

[0030] S402, turning on the stirring device of the dissolving tank to stir;

[0031] S403, closing the water inlet valve, opening the supply valve of the dissolving tank, and adding the third material into the dissolving tank;

[0032] S404, opening the feed valve of the dissolving tank, and adding the roasting material into the dissolving tank;

[0033] S405, after the roasting material feeding is completed, the water inlet valve of the dissolving tank is opened again to replenish water to the dissolving tank again;

[0034] S406, after closing the water inlet valve, dissolving the roasting material.

[0035] The waste lithium battery is a lithium iron phosphate battery, and potassium carbonate is added to the first material.

[0036] The present invention realizes the method for dissolving and crystallizing waste lithium batteries. By preheating and decomposing electrolyte, crushing and screening, roasting, dissolving and other processes of the waste lithium batteries, valuable metallic lithium can be extracted, the degree of automation of the waste lithium battery processing process can be improved, the labor intensity of the production process can be reduced, and the processing efficiency and recycling rate of the waste lithium batteries can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] This specification includes the following drawings, which show the following contents:

[0038] Figure 1 It is a flow chart of the method for realizing dissolution and crystallization of waste lithium batteries according to the present invention;

[0039] Figure 2 It is a schematic diagram of the state of the crushing machine in various operating stages;

[0040] Figure 3 It is a schematic diagram of the structure of the feeding system of the crushing machine;

[0041] Figure 4 It is the automatic control process flow chart of the feeding system of the crushing machine;

[0042] Figure 5 It is a schematic diagram of the structure of the feeding system into the roasting kiln;

[0043] Figure 6 It is a flow chart of the automatic control process of the feeding system into the roasting kiln;

[0044] Figure 7 It is a schematic diagram of the structure of the dissolving tank;

[0045] The markings in the figure are:

[0046] 1. The first conveyor; 2. The second conveyor; 3. The third conveyor; 4. The fourth conveyor; 5. The fifth conveyor; 6. The sixth conveyor; 7. The crushing machine; 8. The roasting system. DETAILED DESCRIPTION

[0047] The specific implementation methods of the present invention are further explained in detail below by describing the embodiments with reference to the accompanying drawings, with the aim of helping those skilled in the art to have a more complete, accurate and in-depth understanding of the concept and technical solution of the present invention and facilitating its implementation.

[0048] It should be noted that, in the following embodiments, the "first", "second", "third", "fourth", "fifth" and "sixth" do not represent an absolute distinction in structure and / or function, nor do they represent a sequence of execution, but are merely for the convenience of description.

[0049] like Figures 1 to 7 As shown, the present invention provides a method for dissolving and crystallizing waste lithium batteries, comprising the following steps:

[0050] S1. After crushing and sorting the waste lithium batteries, a first material containing metal is obtained;

[0051] S2, the first material enters the crushing machine system for crushing to obtain the second material;

[0052] S3, the second material enters the roasting system for high-temperature calcination to obtain a roasting material;

[0053] S4. The calcined material enters a dissolving tank for dissolution to obtain metallic lithium.

[0054] Specifically, the method of the present invention mainly makes full use of the high-temperature and low-oxygen heat source of the cement kiln to reduce energy consumption, pyrolyze toxic waste gas, and extract valuable metallic lithium by preheating and decomposing the electrolyte, crushing and screening, roasting, dissolving, filtering, evaporation and crystallization of waste lithium batteries.

[0055] The method of the present invention mainly focuses on optimizing and adjusting the process such as the feeding system, the pounding system, the dissolution and crystallization system from the perspective of production process control, thereby improving the degree of automation of the waste lithium battery processing process, reducing the labor intensity of the production process, and further improving the processing efficiency and recycling rate of waste lithium batteries.

[0056] According to the production process and characteristics of used lithium batteries, the entire production line can be divided into a certain number of process control units, each of which performs a relatively independent process action to complete the corresponding production process task. Each process control unit is equipped with a certain number of process instruments, valves and motors, and executes corresponding control commands according to the process tasks to be completed.

[0057] In the above step S1, the waste lithium battery is first crushed, and then sorted to screen out impurities, and the remaining is mainly lithium-containing raw materials to obtain metal-containing materials. If the waste lithium battery is a lithium iron phosphate battery, the lithium iron phosphate battery can be crushed and sorted to obtain lithium iron phosphate powder.

[0058] Preferably, before crushing and sorting the waste lithium batteries, the waste lithium batteries can be preheated, and the electrolyte can be separated from the waste lithium batteries by pyrolysis, and collected and processed, so as to achieve safe and efficient processing of the waste lithium batteries and recovery of valuable materials therein.

[0059] like Figure 3 As shown, the crushing system includes multiple crushing machines. The first material of lithium iron phosphate after crushing and sorting is measured by a weighing scale, and then transported to the crushing system together with a certain ratio of potassium carbonate powder, and is fully mixed and ground in the crushing machine. The second material obtained after grinding has a smaller particle size than the first material. The crushing, stirring and grinding process effectively promotes the contact between lithium iron phosphate and potassium carbonate, accelerates the chemical reaction, and effectively improves the recovery efficiency of metal elements. Figure 2 As shown, the status of the crushing machine in each operating stage is displayed in detail. During the production process, the working status of the crushing machine can be monitored in real time.

[0060] In the above step S2, the first material is conveyed to the crusher system through the crusher feeding system. The crusher feeding system includes a weighing scale, a first conveyor for receiving the first material from the weighing scale, a second conveyor for receiving the first material from the first conveyor, and a third conveyor for receiving the first material from the second conveyor, and the crusher receives the first material from the third conveyor.

[0061] In the normal production process, in order to prevent the accumulation of materials inside the crusher, the feeding system equipment group of the roasting kiln is started first to make the crusher clean and empty. After the equipment group is started and operates normally, the crusher feeding system equipment group can be automatically started according to the preset sequence. Figure 4 As shown in the figure, the startup process of the crusher feeding system includes the following steps:

[0062] Step 1: Start the third conveyor;

[0063] Step 2: Start the second conveyor;

[0064] Step 3: Start the first conveyor;

[0065] Step 4: Start the weighing scale.

[0066] In the above step S2, the process of the first material entering the crushing machine system includes the following steps:

[0067] S201, turn on the weighing scale and start timing at the same time;

[0068] S202, opening the feed valve of the crushing machine to feed the crushing machine;

[0069] S203, the feed valve of the crusher is closed.

[0070] When the "Select" button is enabled and the system receives the "Auto Run" command, the corresponding pounding equipment will first run to the initial position. After reaching the initial position, it will feedback the "pounding machine allows feeding" signal to the pounding feeding system group.

[0071] Description of the pounding machine feeding system: When the pounding machine feeding system group receives the "feeding allowed" signal, the pounding machine put into use will feed in sequence according to the pre-set order.

[0072] In the above step S201, when the first material is a mixture of lithium iron phosphate black powder and potassium carbonate, the first metering scale is first turned on, and the first metering scale measures the lithium iron phosphate black powder discharged from the first silo, and starts timing at the same time, which is set to T1 time. When the T1 time reaches the set value or the weight of the lithium iron phosphate black powder reaches the target value, the first metering scale stops, and the first silo stops discharging the lithium iron phosphate black powder. Wait for T2 time, the second metering scale measures the potassium carbonate discharged from the second silo, and starts timing at the same time, which is set to T3 time. When the T3 time reaches the set value or the weight of the potassium carbonate reaches the target value, the second metering scale stops, and the second silo stops discharging potassium carbonate.

[0073] In the above step S202, after waiting for T4 time, the feed valve of the crusher is opened and feeding into the crusher begins. After the feeding continues for T5 time, the feed valve of the crusher is closed, and the current feeding into the crusher ends.

[0074] In the above step S203, after T6 time, the current crusher feeding process is completed and the crusher feeding valve is closed. In order to improve the feeding efficiency, the program sets T0 time inside. When the weighing scale starts weighing, T0 starts counting. When the material enters the crusher, T0 timing ends and the material metering of the next cycle begins.

[0075] In the above step S3, the second material is transported to the roasting system through the roasting kiln feeding system. In the normal production process, it is necessary to start the relevant equipment of the roasting kiln feeding system first. After the startup of this group of equipment is completed, a "startup completion signal" is sent to the crushing machine system. After the crushing machine is started, when the "crushing machine automatic operation" state is reached, the crushing machine feeding system can be started to ensure that the crushed products are delivered to the roasting kiln system in time.

[0076] like Figure 5 As shown, the feeding system into the roasting kiln includes a fourth conveyor for receiving the second material from the crusher, a fifth conveyor for receiving the second material from the fourth conveyor, and a sixth conveyor for receiving the second material from the fifth conveyor, the roasting system receives the second material from the sixth conveyor, the fourth conveyor is located below the crusher, the fifth conveyor is located below the fourth conveyor, and the sixth conveyor is located below the fifth conveyor.

[0077] like Figure 6 As shown, the startup process of the feeding system into the roasting kiln is as follows:

[0078] Before starting, first select the feeding mode. After the corresponding starting conditions are met, click the start button, and the process control unit will ring for 10 seconds. After the ringing is completed, the group of equipment will automatically start according to the program steps preset by the system. When the vulcanization valve on the last crushing machine is started, the system program will automatically start the corresponding crushing machine and the discharger set at the discharge port of the crushing machine according to the use of the "Select" button. That is, if a crushing machine is put into use, the system will start the discharger first in sequence. After the discharger is started, the system program will send an "Auto Run" signal to the corresponding crushing machine, and the second material in the crushing machine will be transported to the roasting system through the feeding system into the roasting kiln. If it is not put into use, the corresponding crushing machine and discharger will not move. During the startup process, if an abnormality occurs, the emergency stop button can be used to safely stop this group of crushing machines.

[0079] In this embodiment, the fourth conveyor, the fifth conveyor and the sixth conveyor are all chain conveyors.

[0080] The roasting kiln is the main equipment of the roasting system, which calcines the crushed second material at high temperature. The high-temperature calcination technology can effectively decompose and remove the organic matter that binds the waste lithium batteries, so as to achieve the separation of the components of the lithium batteries. At the same time, the metals and their compounds in the batteries can be oxidized, reduced and decomposed, and the valuable metals in the waste lithium batteries can be effectively extracted, reducing the emission of harmful substances that may be generated during the recycling process.

[0081] In the roasting kiln, the materials are calcined under high temperature and low oxygen conditions. As the temperature rises, the electrolyte, cathode material and other components inside the second material begin to undergo chemical changes, gradually breaking down into smaller, easier-to-handle molecules or atomic groups. In this process, valuable metal elements are effectively released and enriched. In addition, some toxic waste gases may be generated during the high-temperature calcination process. These waste gases are treated by the flue gas treatment system of the cement kiln, and the high temperature and low oxygen environment of the cement kiln is used for pyrolysis and purification to reduce the emission of harmful substances. Ultimately, the valuable metal elements in waste lithium batteries can be efficiently extracted, the recycling efficiency can be improved, the recycling of resources can be realized, and environmental pollution can be reduced.

[0082] The above step S4 comprises:

[0083] S401, opening the water inlet valve of the dissolution tank to replenish water to the dissolution tank;

[0084] S402, turning on the stirring device of the dissolving tank to stir;

[0085] S403, close the water inlet valve, open the supply valve of the dissolving tank, and add the third material into the dissolving tank;

[0086] S404, opening the feed valve of the dissolving tank, and adding the roasting material into the dissolving tank;

[0087] S405, after the roasting material is fed, the water inlet valve of the dissolving tank is opened again to replenish water to the dissolving tank again;

[0088] S406, after closing the water inlet valve, dissolving the roasting material.

[0089] like Figure 7 As shown, a water inlet valve is provided at the water inlet of the dissolving tank, a supply valve is provided at the first feed inlet of the dissolving tank, and a feed valve is provided at the second feed inlet of the dissolving tank.

[0090] In the above step S401, water can be added to the dissolution tank after the water inlet valve is opened.

[0091] In the above step S402, when the liquid level in the dissolving tank reaches the first set value, the stirring device provided inside the dissolving tank is turned on, and the stirring device is used for stirring. The function of stirring is to promote the mixing of substances, and can effectively mix solid particles or liquid with the solvent to accelerate the dissolution process. Through stirring, the solid particles can be dispersed into the solvent more quickly, reducing the dissolution time. At the same time, precipitation and stratification can be prevented, and the uniformity of the solution can be maintained.

[0092] In the above step S403, when the liquid level in the dissolving tank rises to the second set value, the water inlet valve is closed, the water supply to the dissolving tank is stopped, and then the third material supply valve of the dissolving tank is opened, and the third material is added to the dissolving tank through the supply valve. The third material is Ca(OH)2. Adding calcium hydroxide to the dissolving tank can play the following roles:

[0093] 1. Adjust the pH value of the solution in the dissolution tank: Some metals or compounds in the waste battery may need to be effectively dissolved or separated under specific pH conditions. The addition of calcium hydroxide can neutralize the acidic substances in the solution, thereby adjusting the pH value of the solution to the required range.

[0094] 2. Promote the dissolution of metal oxides: For some waste batteries containing metal oxides (such as dry batteries containing manganese oxides), the alkaline environment of calcium hydroxide may help dissolve these oxides, thereby promoting subsequent metal recovery.

[0095] 3. Precipitation of harmful substances: During the treatment process, some harmful heavy metal ions (such as lead, cadmium, etc.) may be produced. The addition of calcium hydroxide can react with these ions to form insoluble hydroxide precipitates, thereby helping to remove these harmful substances from the solution.

[0096] 4. Improve dissolution efficiency: The addition of calcium hydroxide may improve the dissolution efficiency of metals in waste batteries by changing factors such as the ionic strength and solubility of the solution, allowing more metals to be effectively recovered.

[0097] In the above step S404, when the liquid level in the dissolving tank rises to the third set value, the supply valve is closed, and then the feed valve of the dissolving tank is opened, and the roasting material is added into the dissolving tank through the feed valve.

[0098] In the above step S405, after the roasting material added to the dissolving tank reaches the set value, the feeding of the roasting material is completed, the feeding valve is closed, and the water inlet valve of the dissolving tank is opened again to replenish water to the dissolving tank again.

[0099] In the above step S406, when the liquid level in the dissolving tank rises to the fourth set value, the water inlet valve is closed, the water replenishment to the dissolving tank is stopped, the roasting material dissolution stage is entered, and the roasting material in the dissolving tank is dissolved. After the dissolution time reaches the set value, the roasting material is dissolved. Finally, the discharge pump connected to the bottom discharge port of the dissolving tank and the discharge valve connected to the discharge pump are opened, and the dissolving tank is discharged. When the liquid level of the dissolving tank is reduced to the fifth set value, the discharge valve is closed, the dissolving tank is discharged, and metallic lithium is obtained. At this point, the system completes a cycle. After the restart conditions are met, the process production unit will start again to feed, dissolve, and discharge.

[0100] During the production process of this unit, the relevant regulating valves are automatically adjusted according to the set flow rate. If an abnormality occurs during the production process, the emergency stop button on the panel can be used to stop the equipment in this group to ensure production safety.

[0101] In this embodiment, the waste lithium battery is a lithium iron phosphate battery, and potassium carbonate needs to be added to the first material. After the waste lithium battery is crushed and sorted, lithium iron phosphate black powder is obtained, and the lithium iron phosphate black powder and potassium carbonate are mixed to form the first material; in the process of processing the waste lithium iron phosphate battery, potassium carbonate is added to the lithium iron phosphate black powder mainly based on the following considerations:

[0102] 1. Promote the recycling of valuable metals

[0103] The positive electrode material lithium iron phosphate in waste lithium iron phosphate batteries is the more valuable part, which contains metal elements such as lithium, iron, and phosphorus. By adding potassium carbonate, it can participate in chemical reactions, which helps to effectively extract these valuable metals from the waste. Specifically, potassium carbonate may act as a leaching agent or precipitant, reacting with metal ions in the waste to form soluble salts or precipitates, thereby facilitating subsequent separation and purification;

[0104] 2. Improve leaching efficiency

[0105] In the recycling process of waste lithium iron phosphate batteries, leaching is a key step, which directly affects the recovery rate and purity of valuable metals. The addition of potassium carbonate may help improve the leaching conditions and increase the leaching efficiency. For example, potassium carbonate can adjust the pH value of the leachate, making it easier for metal ions to transfer from the solid phase to the liquid phase; at the same time, potassium carbonate may also produce a synergistic effect with other leaching agents to further promote the leaching of metal ions;

[0106] 3. Optimizing the precipitation and crystallization process

[0107] In the recovery process, precipitation and crystallization are important steps to obtain high-purity metal compounds. The addition of potassium carbonate can affect the precipitation and crystallization process. By controlling the reaction conditions (such as temperature, concentration, pH value, etc.), the target metal ions are precipitated in a specific form to form compounds with higher purity.

[0108] 4. Reduce processing costs

[0109] Potassium carbonate is a common chemical raw material with a relatively low price and is easy to obtain. Adding potassium carbonate to the treatment process of waste lithium iron phosphate batteries can reduce the treatment cost to a certain extent. At the same time, the addition of potassium carbonate may also improve the treatment efficiency, reduce the treatment time and energy consumption, and further reduce the overall cost.

[0110] The above method for dissolving and crystallizing waste lithium batteries has the following advantages:

[0111] 1. The treatment process of waste lithium batteries is further simplified, effectively reducing the labor intensity of production personnel. By making full use of the high-temperature and low-oxygen heat source of the cement kiln, the high-temperature and low-oxygen heat source can reduce energy consumption and pyrolyze toxic waste gas, which is both safe and efficient, and low-carbon and environmentally friendly.

[0112] 2. The further improvement of the degree of automation in the production process has effectively improved the purity of lithium elements in the recycling of waste lithium batteries and increased their utilization value.

[0113] The present invention is described above by way of example in conjunction with the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-mentioned methods. As long as various non-substantial improvements are made using the method concept and technical solution of the present invention; or the above concept and technical solution of the present invention are directly applied to other occasions without improvement, they are all within the protection scope of the present invention.

Claims

1. A method for dissolving and crystallizing waste lithium batteries, characterized in that: Includes steps: S1. After crushing and sorting the waste lithium batteries, a first material containing metal is obtained; S2, the first material enters the crushing machine system for crushing to obtain the second material; S3, the second material enters the roasting system for calcination to obtain a roasting material; S4. The calcined material enters a dissolving tank for dissolution to obtain metallic lithium.

2. The method for dissolving and crystallizing waste lithium batteries according to claim 1, characterized in that: The crushing system includes a crushing machine, and a plurality of crushing machines are provided.

3. The method for dissolving and crystallizing waste lithium batteries according to claim 2, characterized in that: In the step S2, the first material is transported to the crusher system through the crusher feeding system.

4. The method for dissolving and crystallizing waste lithium batteries according to claim 3, characterized in that: The crusher feeding system includes a weighing scale, a first conveyor for receiving the first material from the weighing scale, a second conveyor for receiving the first material from the first conveyor, and a third conveyor for receiving the first material from the second conveyor, and the crusher receives the first material from the third conveyor.

5. The method for dissolving and crystallizing waste lithium batteries according to claim 4, characterized in that: The startup process of the crusher feeding system comprises the following steps: Step 1: starting the third conveyor; Step 2: starting the second conveyor; Step 3: starting the first conveyor; Step 4: Start the measuring scale.

6. The method for dissolving and crystallizing waste lithium batteries according to any one of claims 4 to 5, characterized in that: In step S2, the process of the first material entering the crushing machine system includes the following steps: S201, turning on the measuring scale and starting timing at the same time; S202, opening the feed valve of the crushing machine to feed the crushing machine; S203, the feed valve of the crusher is closed.

7. The method for dissolving and crystallizing waste lithium batteries according to any one of claims 1 to 6, characterized in that: In the step S3, the second material is transported to the roasting system through a roasting kiln feeding system.

8. The method for dissolving and crystallizing waste lithium batteries according to claim 7, characterized in that: The feeding system into the roasting kiln includes a fourth conveyor for receiving the second material from the crusher, a fifth conveyor for receiving the second material from the fourth conveyor, and a sixth conveyor for receiving the second material from the fifth conveyor, and the roasting system receives the second material from the sixth conveyor.

9. The method for dissolving and crystallizing waste lithium batteries according to any one of claims 1 to 8, characterized in that: The step S4 comprises: S401, opening the water inlet valve of the dissolution tank to replenish water to the dissolution tank; S402, turning on the stirring device of the dissolving tank to stir; S403, closing the water inlet valve, opening the supply valve of the dissolving tank, and adding the third material into the dissolving tank; S404, opening the feed valve of the dissolving tank, and adding the roasting material into the dissolving tank; S405, after the roasting material feeding is completed, the water inlet valve of the dissolving tank is opened again to replenish water to the dissolving tank again; S406, after closing the water inlet valve, dissolving the roasting material.

10. The method for dissolving and crystallizing waste lithium batteries according to any one of claims 1 to 8, characterized in that: The waste lithium battery is a lithium iron phosphate battery, and potassium carbonate is added to the first material.

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