Device and method for recovering valuable metals from retired lithium-ion batteries

Abstract

The present invention discloses a device and method for recovering valuable metals from retired lithium-ion batteries. The device includes a chemical chain reaction system, a gas distribution system, and an entrainment and collection device. The chemical chain reaction system includes an air reactor heating furnace and a reduction reactor heating furnace, which are connected in series via a cyclone separation device and a gas-solid separator, respectively. The air reactor heating furnace is used to oxidize incompletely reduced lithium-ion battery carriers and provide reaction heat for the reduction reactor heating furnace. Quartz tubes are provided in both the air reactor heating furnace and the reduction reactor heating furnace. The upper end of the quartz tube in the reduction reactor heating furnace is connected to the entrainment and collection device. The gas distribution system includes a dry air bottle, a nitrogen bottle, and a hydrogen bottle, and the dry air bottle is connected to the bottom end of the quartz tube in the air reactor heating furnace. The present invention can orderly reduce lithium-ion battery carriers, improve the selectivity and conversion rate of the target product, reduce the loss of valuable metal elements, and at the same time solve the high energy consumption and high pollution problems caused by the difficulty in controlling process parameters of traditional pyrometallurgical recovery technology.

Description

Technical Field

[0001] The present invention relates to the technical field of waste lithium battery recycling, and in particular to a device and method for recycling valuable metals from retired lithium-ion batteries. Background Art

[0002] The rapid iteration and update of new energy vehicles has caused power batteries represented by lithium-ion batteries (LIBs) to face a large number of retirement problems. The positive electrode materials of LIBs are rich in valuable metals such as Li and Co, and have significant pollution and resource characteristics. If they cannot be effectively recovered, it will not only damage the environment, but also lead to the loss of valuable scarce metals. Therefore, the efficient recovery of valuable metals in lithium-ion batteries is of great significance. Fire recovery is to reduce the metal compounds in LIBs to low-valent oxidation or soluble states under a high-temperature environment provided by a reducing agent (gas or solid), and then recover the valuable metals through physical or chemical leaching. Fire metallurgical recovery of valuable metals from retired LIBs has great development advantages due to its advantages of large processing capacity and simple process, and no need to screen and enrich LIBs. For example, Chinese patent CN112424383A discloses a recovery method for valuable metals from waste lithium-ion batteries, which includes a waste battery pre-treatment process, a crushing process, a preheating process, a melting process, and a slag separation process. This invention can recover valuable metals such as copper, nickel, and cobalt from waste lithium-ion batteries as alloys at a high recovery rate, and can effectively remove phosphorus; Chinese patent CN112111651A discloses a pyrometallurgical process for the recovery of waste lithium-ion battery powder, including crushing, screening, roasting, alkaline leaching, evaporation, acid leaching, and filtration of waste lithium-ion batteries. This invention improves the recovery rate of valuable metals such as nickel, cobalt, and manganese and the removal rate of fluorine from waste lithium-ion battery powder; Chinese patent CN114381605A discloses a comprehensive method for the recovery of valuable metals from waste lithium-ion battery black powder, including high-temperature reduction of waste lithium-ion battery black powder, selective hydrochlorination, water leaching, magnetic separation, alkaline leaching, alkaline neutralization, and filtration. This invention can efficiently recover valuable metals such as lithium, nickel, manganese, and cobalt from waste lithium-ion battery black powder. However, the above-mentioned prior art uses pyrometallurgical methods to recover valuable metals, which have the following problems:

[0003] (1) High energy consumption, large consumption of chemical reagents, and acid and alkali waste liquid generated during the leaching process, which can easily cause secondary pollution;

[0004] (2) The pyrometallurgical recovery process is complex and costly, and the roasting process easily produces toxic and harmful gases such as HF and PF5 that pollute the environment;

[0005] (3) It is difficult to achieve orderly regulation of parameters during the reduction process, resulting in low selectivity and conversion rate of the reduction products, serious loss of valuable metal elements, and low overall recovery efficiency. Summary of the Invention

[0006] The purpose of the present invention is to provide a device and method for recovering valuable metals from retired lithium-ion batteries. The device uses the cathode material of the waste lithium-ion batteries as a chemical chain carrier. On the one hand, the selectivity and conversion rate of the target product are improved through the complementary matching of temperature and reducing gas, thereby reducing the loss of valuable metal elements. On the other hand, the device and method solve the high energy consumption and high pollution problems caused by the difficulty in controlling process parameters in traditional pyrometallurgical recovery technology, thereby achieving the goal of green, energy-saving and efficient recovery of valuable metals from retired lithium-ion batteries.

[0007] To achieve the above-mentioned purpose, the present invention discloses, on one hand, a device for recovering valuable metals from retired lithium-ion batteries, comprising a chemical chain reaction system, a gas distribution system and an entrainment collection device; the chemical chain reaction system comprises an air reactor heating furnace and a reduction reactor heating furnace, the reduction reactor heating furnace is used to reduce the lithium-ion battery carrier, the air reactor heating furnace is used to oxidize the incompletely reduced lithium-ion battery carrier and provide reaction heat for the reduction reactor heating furnace; a gas-solid separator and a cyclone separation device are connected between the air reaction heating furnace and the reduction reactor heating furnace, wherein the gas-solid separator is located in the air reactor. The reaction heating furnace and the reduction reactor heating furnace are located at the lower part, and the cyclone separation device is located at the upper part of the air reaction heating furnace and the reduction reactor heating furnace; quartz tubes are provided in both the air reaction heating furnace and the reduction reaction heating furnace for reducing and oxidizing lithium-ion battery carriers; the upper end of the quartz tube in the reduction reactor heating furnace is connected to the elutriation collection device; the gas distribution system includes a dry air bottle, a nitrogen bottle and a hydrogen bottle, the dry air bottle is connected to the bottom end of the quartz tube in the air reactor heating furnace; the nitrogen bottle and the hydrogen bottle are connected to the bottom end of the quartz tube in the reduction reactor heating furnace.

[0008] Furthermore, an air distribution plate is provided at the lower portion of the two quartz tubes.

[0009] Furthermore, it also includes a temperature controller, which is connected to the air reactor heating furnace and the reduction reactor heating furnace.

[0010] Furthermore, the dry air bottle is connected to the bottom end of the quartz tube in the air reactor heating furnace through a pressure reducing valve, a mass flow controller and a flow meter; the nitrogen bottle and the hydrogen bottle are connected to the bottom end of the quartz tube in the reduction reaction heating furnace through a pressure reducing valve, a mass flow controller and a flow meter.

[0011] On the other hand, the present invention also discloses a method for recovering valuable metals from retired lithium-ion batteries, comprising the following steps:

[0012] S1. Discharging and disassembling lithium-ion batteries: The collected waste lithium-ion batteries were soaked in 5% NaCl solution for 24 hours to release the residual power. After discharge, they were dried in a forced air drying oven. The plastic layer of the dried retired lithium-ion batteries was peeled off and the positive electrode materials of the batteries were separated by mechanical disassembly.

[0013] S2. Soak the lithium-ion battery cathode material obtained in step S1 in a 5% NaOH solution for 2 h to remove the aluminum foil and the binder. Rinse the obtained black sample with deionized water several times until the rinse solution is neutral, and then dry it in a 105° C. forced air drying oven for 12 h to obtain a black solid powder.

[0014] S3, grinding and sieving the dried black solid powder obtained in step S2 to a particle size of 140 to 270 mesh to obtain a lithium ion battery positive electrode material carrier for chemical looping reduction, and storing the carrier in a desiccator for later use;

[0015] S4. Reducing the lithium ion battery carrier obtained in step S3 in a reduction reaction furnace at a reduction temperature of 600-1000° C. for a reduction time of 30-120 min; introducing hydrogen with a concentration of 3 vol% as a reducing gas and nitrogen as a protective gas into the reduction reactor furnace, and collecting the reduction product by the elutriation collection device.

[0016] S5. The lithium battery carrier that is not completely reduced in step S4 is passed into an air reactor heating furnace for oxidation. After oxidation, the carrier is passed into a reduction reactor heating furnace for reduction operation in step S4, and the cycle is repeated.

[0017] S6, element separation and recovery: The reduction product collected in step S5 is subjected to element separation and recovery based on the properties of the metal elements in the lithium-ion battery positive electrode material, or is directly used to prepare the lithium-ion battery positive electrode material. Furthermore, in step S5, fresh lithium battery carrier is added to the air reactor as a feed.

[0018] The beneficial effects of the present invention are that, compared with the prior art, the present invention has the following advantages:

[0019] (1) The present invention achieves high conversion rate and target product selectivity for the reduction of lithium-ion battery carriers based on chemical looping combustion technology, with less loss of target products. The maximum lithium cobalt oxide conversion rate achieved by reducing the lithium cobalt oxide carrier is 98.36%;

[0020] (2) The particle density and particle size (50% of the raw material) of the target product obtained by chemical chain reduction in the present invention gradually decrease due to reduction wear and tear and crushing into fine particles. It can be efficiently collected by elutriation, and the operation is simple. The metal element separation and recovery can be achieved without adding chemical reagents.

[0021] (3) Compared with the traditional pyrometallurgical recovery technology, the present invention adopts a chemical chain reaction system. In the reduction reaction furnace, the carrier flows from top to bottom, the temperature at the top of the reactor furnace is high and the temperature at the bottom is low; the reducing gas flows from bottom to top, dense in the low temperature area and thin in the high temperature area. This countercurrent contact, temperature gradient and concentration gradient complement each other's reaction characteristics enable the two to fully transfer heat and mass, release energy in a step-by-step manner and convert chemical energy in a graded manner, and realize the orderly reduction of the lithium-ion battery carrier to the target product throughout the process. In addition, the carrier will be subjected to reaction stress, thermal stress and mechanical stress during the fluidization process of the two reactors, which can easily lead to the instability of its own lattice structure. In particular, the wear and tear in the reduction reactor accelerates the peeling and separation of the carrier product layer, increases the reaction contact area, and can achieve efficient reduction of the carrier.

[0022] (4) The carrier that is not completely reduced in the present invention can enter the air reactor and be oxidized again. The oxidation heat absorption not only provides feed and reaction heat for the reduction reactor to realize the chemical chain cycle process, but also can reduce the heat load of the system to a certain extent, thereby achieving the purpose of reducing the energy consumption of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is a schematic structural diagram of a device for recovering valuable metals from retired lithium-ion batteries according to the present invention;

[0024] Figure 2 is a flow chart of the method for recovering valuable metals from retired lithium-ion batteries of the present invention;

[0025] Figure 3 is a flow chart of the preparation process of the LiCoO2 carrier in a specific embodiment;

[0026] Figure 4 is a diagram of the morphology, surface element distribution and crystal composition of the newly prepared LiCoO2 support in a specific embodiment;

[0027] Figure 5 is an XRD result diagram in a specific embodiment;

[0028] FIG6 is a diagram showing the effect of different reduction conditions on the reduction conversion rate of the LiCoO2 carrier in a specific embodiment;

[0029] Figure 7 is a SEM spectrum of the product obtained by chemical chain reduction of LiCoO2 support under different reduction conditions in a specific embodiment;

[0030] Figure 8 : is an EDS spectrum of the product obtained by chemical chain reduction of LiCoO2 support under different reduction conditions in a specific embodiment;

[0031] Figure 9 is an XRD diagram of the reduction product of the LiCoO2 carrier under different reduction conditions in a specific embodiment; in the figure, 1- dry air bottle, 2- nitrogen bottle, 3-3vol% concentration hydrogen bottle, 401- pressure reducing valve I, 402- pressure reducing valve II, 403- pressure reducing valve III, 501- mass flow controller I, 502- mass flow controller

[0032] II, 503-mass flow controller III, 601-three-way valve I, 602-three-way valve II, 701-flow meter

[0033] I, 702-flow meter II, 8-temperature controller, 9-gas-solid separator, 1001-air distribution plate I, 1002-air distribution plate II, 1101-lithium ion battery carrier I, 1102-lithium ion battery carrier II, 1201-air reactor heating furnace, 1202-reduction reactor heating furnace, 1301-quartz tube I, 1302-quartz tube II,

[0034] 14- cyclone separation device, 15- separation and collection device. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] like Figure 1As shown, a device for recovering valuable metals from retired lithium-ion batteries includes a chemical chain reaction system, a gas distribution system, and an elutriation collection device 15. The chemical chain reaction system includes an air reactor heating furnace 1201 and a reduction reactor heating furnace 1202. The air reactor heating furnace 1201 is used to oxidize incompletely reduced lithium-ion battery carriers and provide reaction heat for the reduction reactor heating furnace 1202. The reduction reactor heating furnace 1102 is used to reduce the lithium-ion battery carriers. A gas-solid separator 9 and a cyclone separation device 14 are connected between the air reaction heating furnace 1201 and the reduction reactor heating furnace 1202. The gas-solid separator 9 is located below the air reaction heating furnace 1201 and the reduction reactor heating furnace 1202, and the cyclone separation device 14 is located above the air reaction heating furnace 1201 and the reduction reactor heating furnace 1202. The cyclone separator 14 utilizes a centrifugal cylindrical structure to separate lithium-ion battery carriers oxidized in the air reactor furnace for introduction into the reduction reactor furnace for reduction. The gas-solid separator 9 utilizes a filtration-type gas-solid separation mechanism to separate incompletely reduced lithium-ion batteries from the reduction reactor furnace for introduction into the air reactor furnace for oxidation. A quartz tube I1301 is located within the air reactor furnace 1201, while a quartz tube II1302 is located within the reduction reactor furnace 1202. Quartz tube I is equipped with an air distribution plate I1001, while quartz tube II is equipped with an air distribution plate II1002. Lithium-ion battery carriers I1101 are positioned above air distribution plate I1001, while lithium-ion battery carriers II1102 are positioned above air distribution plate II1002. Air inlets are located at the bottoms of both the air reactor furnace 1201 and the reduction reactor furnace 1202. An entrainment and collection device 15 collects the reduction products resulting from the reduction of the lithium-ion battery carriers 1102 in the reduction reactor furnace 1202. The gas distribution system includes a dry air cylinder 1, a nitrogen cylinder 2, and a 3 vol% concentration hydrogen cylinder 3. The gas outlet of the dry air cylinder 1 is connected to a pressure reducing valve I401, a mass flow controller I501, and an inlet of a three-way valve I601 in sequence through a pipeline. The gas outlet of the nitrogen cylinder 1 is connected to a pressure reducing valve II402, a mass flow controller II502, and an inlet of a three-way valve II602 in sequence through a pipeline. The gas outlet of the 3 vol% concentration hydrogen cylinder 3 is connected to a pressure reducing valve III403, a mass flow controller III503, and a second inlet of the three-way valve II602 in sequence through a pipeline. The outlet of the three-way valve I601 is connected to the inlet of a flowmeter 701, the outlet of the three-way valve II602 is connected to the inlet of a flowmeter II702, and the outlets of the flowmeter I701 and the flowmeter II702 are respectively connected to the gas inlet of the reactor through pipelines.

[0037] The reducing gas used in this device is not limited to hydrogen, and can also be carbon monoxide, methane, etc.

[0038] like Figure 2As shown, the present invention also discloses a method for recovering valuable metals from retired lithium-ion batteries, comprising the following steps:

[0039] S1. Discharging and disassembling lithium-ion batteries: The collected waste lithium-ion batteries were soaked in 5% NaCl solution for 24 hours to release the residual power. After discharge, they were dried in a forced air drying oven. The plastic layer of the dried retired lithium-ion batteries was peeled off and the positive electrode materials of the batteries were separated by mechanical disassembly.

[0040] S2. Soak the lithium-ion battery positive electrode material obtained in step S1 in 5% NaOH solution for 2 hours to remove the aluminum foil and adhesive. Rinse the obtained black sample with deionized water several times until the rinse solution is neutral, and then place it in a 105° C. forced air drying oven and dry it for 12 hours to obtain a black solid powder.

[0041] S3. Grind and sieve the dried black solid powder obtained in step S2 to a particle size of 140 to 270 meshes to obtain a lithium-ion battery positive electrode material carrier for chemical loop reduction, and store it in a desiccator for later use.

[0042] S4, the lithium ion battery carrier obtained in step S3 is reduced in the reduction reactor heating furnace 1202, the reduction temperature is 600-1000 ° C, and the reduction time is 30-120 min; then, hydrogen (concentration 3 vol%) is introduced into the reduction reaction heating furnace 1202 through the 3 vol% concentration hydrogen bottle 3 as a reducing gas, and the hydrogen flow rate is 20-60 mL / min; nitrogen is introduced as a protective gas through the nitrogen bottle 2, and the flow rate is 60 mL / min. The specific operation is as follows: take 2g of battery carrier powder and place it in the center of the quartz tube II1302, heat it to the reaction temperature under a nitrogen atmosphere, and the heating rate is 15 ° C / min. After reaching the reaction temperature, the gas is switched to hydrogen reducing gas for reduction for a certain time. After the reduction is completed, the gas is switched to nitrogen purging for a period of time to ensure that the reaction gas in the pipeline is completely discharged and cooled to room temperature. The reduction product is collected by the said entrainment collection device 15.

[0043] S5. The lithium-ion battery carriers I1102 that were not completely reduced in step S4 are passed through the gas-solid separator 9 into the air reactor heating furnace 1201 for oxidation. The oxidized lithium-ion battery carriers I1101 are then passed through the cyclone separation device 14 into the reduction reaction heating furnace 102 for the reduction operation in step S4, and this cycle is repeated. Fresh lithium-ion battery carriers 1101 are added to the air reaction heating furnace 1201 as feed.

[0044] S6. Element separation and recovery: The reduction product collected in step S5 is subjected to element separation and recovery according to the difference in properties of the metal elements in the positive electrode material of the lithium-ion battery, or is directly used for preparing the positive electrode material of the lithium-ion battery.

[0045] The method is further described in detail below by conducting a chemical chain reduction experiment using collected waste lithium cobalt oxide (LiCoO2) lithium ion batteries as chemical chain circulation carriers.

[0046] (1) Preparation of LiCoO2 carrier: Figure 3 The preparation process for the LiCoO2 carrier involves soaking retired LiCoO2 batteries in a 5% NaCl solution for 24 hours to release any residual charge. After discharge, the batteries are dried in a forced-air drying oven. The plastic layer of the dried retired LiCoO2 batteries is removed and the positive electrode material is separated by mechanical disassembly. The collected positive electrode material is soaked in a 5% NaOH solution for 2 hours to remove the aluminum foil and adhesive. The resulting black sample is rinsed several times with deionized water until the rinse solution is neutral, then dried in a 105°C forced-air drying oven for 12 hours. The dried sample is ground and sieved to a particle size of 140 to 270 mesh to obtain the LiCoO2 carrier, which is then stored in a desiccator for later use.

[0047] (2) Characterization of LiCoO2 carrier: The physical and chemical characteristics of the freshly prepared LiCoO2 carrier, including specific surface area, pore size, surface morphology, element distribution and crystal composition, were analyzed. The results showed that the specific surface area of ​​the lithium cobalt oxide carrier was 9.7 m 2 / g, pore volume 0.031cm 3 / g, the average pore size is 9.254nm, and the pore size distribution is mainly mesopores. Figure 2 As shown in the SEM characterization, it can be seen that ( Figure 4 a) The surface of the LiCoO2 carrier is porous and consists of a large number of structural micro-regions, which can provide a place for the reaction. EDS spectrum analysis ( Figure 4 b and Figure 4 c) shows that Co and O elements are evenly distributed on the surface of the support. Figure 5 XRD results show that the main component of the support is LiCoO2, with few impurities. The small amount of CoO2 may be due to partial decomposition of LiCoO2 during the preparation process of the support. The characterization results prove that the prepared LiCoO2 support has the potential to be used as a chemical chain support.

[0048] (3) Chemical chain reduction of LiCoO2 carrier: The chemical chain reduction experiment of LiCoO2 carrier was carried out in the chemical chain device. In each experiment, 2g of LiCoO2 carrier powder was placed in the center of the quartz tube, and heated to the reaction temperature under the protection of N2 atmosphere (N2 flow rate was 60mL / min), with a heating rate of 15℃ / min. After reaching the set temperature, the gas was switched to H2 with a concentration of 3% to start the reduction experiment. The reaction temperatures were set to 600℃, 700℃, 800℃, 900℃ and 1000℃, respectively, and the reaction times were 30min, 60min, 90min and 120min, respectively. The flow rates of 3% H2 were 20mL / min, 40mL / min and 60mL / min, respectively. After the reaction was completed, the gas was switched to nitrogen purge for a period of time to ensure that the reaction gas in the pipeline was completely discharged and cooled to room temperature. The reduction product was collected by the entrainment collection device 15 and the mass was recorded.

[0049] (4) Reduction characteristics analysis: Figure 6 shows the effect of different reduction conditions on the reduction conversion rate of LiCoO2 carrier. The LiCoO2 conversion rate increases significantly with the increase of reduction temperature and reduction time ( Figure 6a ), when the reduction time is less than 60 minutes, the reduction time has a better effect on improving the LiCoO2 conversion rate than the temperature; when the reduction time is greater than 90 minutes, the reduction temperature has a better effect on improving the LiCoO2 conversion rate than the time. Moreover, the reduction temperature has an overall better effect on improving the LiCoO2 conversion rate than the reduction time. The highest LiCoO2 conversion rate of 98.36% was achieved at 1000°C for 120 minutes, indicating that the effect of the reduction temperature on the LiCoO2 conversion rate during the chemical chaining H2 reduction of the LiCoO2 carrier is more significant, which is consistent with the effect of temperature on the traditional hydrogen thermal reduction of LiCoO2. Therefore, temperature control can shorten the reduction time, achieve a high LiCoO2 conversion rate, and improve the reduction efficiency.

[0050] At different temperatures, the LiCoO2 conversion rate increases with the increase of H2 flow rate ( Figure 6b At relatively low temperatures (600°C to 900°C), increasing the H2 flow rate has a relatively slow effect on the LiCoO2 conversion rate. However, at 1000°C, increasing the H2 flow rate significantly accelerates the LiCoO2 conversion rate, indicating that high temperature and large H2 flow rates are beneficial for increasing the conversion rate of the LiCoO2 carrier and accelerating LiCoO2 conversion. Furthermore, when the H2 flow rate is low (less than 40 mL / min), the LiCoO2 conversion rate is relatively high. However, when the H2 flow rate is greater than 40 mL / min, the LiCoO2 conversion rate tends to be flat, and increasing the H2 flow rate has no significant effect on improving the LiCoO2 conversion rate.

[0051] (5) Analysis of the morphology of the reduction product: Figure 7 and Figure 8 The SEM and EDS spectra of the products obtained by chemical chain reduction of LiCoO2 carrier under different reduction conditions are respectively. The surface morphology of the reduction products obtained under different reduction conditions is significantly different ( Figure 5 After H2 reduction, the porous structure of the LiCoO2 support, consisting of numerous microdomains, is destroyed, transforming into a macroscopically distributed microsphere morphology. With increasing reduction temperature and H2 flow rate, the microspheres exhibit significant surface erosion, indicating enhanced LiCoO2 reduction. The distribution of Co on the surface becomes less uniform after H2 reduction, with some aggregation occurring (Figure 6). This is likely due to the reaction of LiCoO2 with H2 to form the metal oxides CoO2, CoO, and Li2O, leading to the migration of Co and Li during the reduction process.

[0052] (6) Analysis of the purity of the reduction product: Figure 9 shows the XRD patterns of the reduction products of the LiCoO2 carrier under different reduction conditions. The diffraction peak types and intensities of the product components in the figure can reflect the purity of the LiCoO2 reduction product to a certain extent. The fewer the diffraction peak types and the greater the intensity, the higher the purity of the reduction product. The main reduction products of the LiCoO2 carrier after H2 reduction include Li2O, CoO2, Co element, CoO and a small amount of LiOH. The product diffraction peak types obtained under low temperature and short time reduction conditions are more and less intense ( Figure 9a and b), indicating the purity of the LiCoO2 reduction product under low reduction intensity. At 1000 ° C, the diffraction peak types of the product are significantly reduced and the intensity is increased. At this time, the reduction intensity is enhanced, resulting in improved product purity. Similarly, increasing the H2 flow rate during the LiCoO2 reduction process will also reduce the diffraction peak types and increase the intensity of the LiCoO2 support reduction product ( Figure 9c The reduction in the product diffraction peak types indicates that the enhanced reduction intensity of LiCoO2 promotes the further reaction of the active components in the product (mainly LiOH and CoO) to generate Li2O and CoO2 or Co element, thereby increasing the diffraction peak intensity and thus improving the purity of the reduction product.

[0053] This embodiment achieves low-energy and orderly reduction of the LiCoO2 carrier by complementary matching of reduction temperature and hydrogen flow rate. The reduction products mainly generate Li2O and Co elements, with high product selectivity and conversion rate. The chemical chain reduction steps are simple, and the subsequent recovery and separation of valuable metals can achieve efficient recovery without the use of any chemical reagents, and no waste liquid is generated to cause secondary pollution.

[0054] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited thereto. Various changes that can be made within the scope of knowledge possessed by technicians in the relevant technical field without departing from the spirit of the present invention are all within the scope of protection of the claims of the present invention.

Claims

1. A device for recovering valuable metals from retired lithium-ion batteries, characterized in that: It includes chemical chain reaction system, gas distribution system and entrainment collection device; The chemical chain reaction system includes an air reactor heating furnace and a reduction reactor heating furnace, wherein the air reactor heating furnace is used to oxidize the incompletely reduced lithium-ion battery carrier and provide reaction heat for the reduction reactor heating furnace; A gas-solid separator and a cyclone separator are connected between the air reactor heating furnace and the reduction reactor heating furnace, wherein the gas-solid separator is located at the lower part of the air reactor heating furnace and the reduction reactor heating furnace, and the cyclone separator is located at the upper part of the air reactor heating furnace and the reduction reactor heating furnace; Quartz tubes are provided in the air reactor heating furnace and the reduction reactor heating furnace for reducing and oxidizing the lithium-ion battery carrier; The reduction reactor heating furnace is used to allow the lithium-ion battery carrier to flow from top to bottom and come into countercurrent contact with the reducing gas flowing from bottom to top, utilizing the characteristic that the carrier is worn and broken to form fine particles during the reduction process, and the product is collected by the entrainment collection device connected to the upper end of the quartz tube in the reduction reactor heating furnace; The gas distribution system includes a dry air bottle, a nitrogen bottle and a hydrogen bottle. The dry air bottle is connected to the bottom end of the quartz tube in the air reactor heating furnace; the nitrogen bottle and the hydrogen bottle are connected to the bottom end of the quartz tube in the reduction reactor heating furnace.

2. The device for recovering valuable metals from retired lithium-ion batteries according to claim 1, characterized in that: An air distribution plate is provided at the lower part of the two quartz tubes.

3. The device for recovering valuable metals from retired lithium-ion batteries according to claim 1, characterized in that: It also includes a temperature controller, which is connected to the air reactor heating furnace and the reduction reactor heating furnace.

4. The device for recovering valuable metals from retired lithium-ion batteries according to claim 1, characterized in that: The dry air bottle is connected to the bottom end of the quartz tube in the air reactor heating furnace through a pressure reducing valve, a mass flow controller and a flow meter; the nitrogen bottle and the hydrogen bottle are connected to the bottom end of the quartz tube in the reduction reactor heating furnace through a pressure reducing valve, a mass flow controller and a flow meter.

5. A method for recycling valuable metals from retired lithium-ion batteries according to any one of claims 1 to 4, characterized in that: The steps include: S1. Discharging and disassembling lithium-ion batteries: The collected waste lithium-ion batteries were soaked in 5% NaCl solution for 24 hours to release the residual power. After discharge, they were dried in a forced air drying oven. The plastic layer of the dried retired lithium-ion batteries was peeled off and the positive electrode materials of the batteries were separated by mechanical disassembly. S2. Soak the lithium-ion battery cathode material obtained in step S1 in a 5% NaOH solution for 2 h to remove the aluminum foil and the binder. Rinse the obtained black sample with deionized water several times until the rinse solution is neutral, and then dry it in a 105° C. forced air drying oven for 12 h to obtain a black solid powder. S3, grinding and sieving the dried black solid powder obtained in step S2 to a particle size of 140-270 mesh to obtain a lithium ion battery positive electrode material carrier for chemical looping reduction, and storing the carrier in a desiccator for later use; S4, reducing the lithium ion battery carrier obtained in step S3 in a reduction reactor heating furnace at a reduction temperature of 600-1000° C. for a reduction time of 30-120 min; introducing 3 vol% hydrogen as a reducing gas and nitrogen as a protective gas into the reduction reactor heating furnace, and collecting the reduction product by the aforementioned elutriation and collection device; S5, passing the lithium battery carrier that is not completely reduced in step S4 into an air reactor heating furnace for oxidation, and then passing the oxidized carrier into a reduction reactor heating furnace for the reduction operation in step S4, and the cycle is repeated; S6. Element separation and recovery: The reduction product collected in step S5 is subjected to element separation and recovery according to the difference in properties of the metal elements in the positive electrode material of the lithium-ion battery, or is directly used for preparing the positive electrode material of the lithium-ion battery.

6. The method according to claim 5, characterized in that In step S5, fresh lithium battery carriers are added into the air reactor heating furnace as supplementary materials.

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