Continuous equipment for preparing expanded graphite material from negative electrode of waste lithium ion battery

Abstract

The utility model discloses continuous equipment for preparing an expanded graphite material from a negative electrode of a waste lithium ion battery. The equipment comprises a pickling device, a strong oxidation impurity removal device and a centrifugal device which are sequentially communicated through a pipeline, the grabbing device comprises a track and a mechanical claw which is arranged on the track and can move along the track and move up and down, the track is arranged above the centrifugal device, the drying device and the high-temperature expansion device which are sequentially arranged, and the mechanical claw is used for conveying device materials below the track. The waste graphite negative electrode is safely converted into graphite oxide through the pickling device, the strong oxidation impurity removal device and the centrifugal device, then the graphite oxide is sequentially moved to the drying device from the centrifugal device through the grabbing device, and finally the graphite oxide is converted into high-value porous expanded graphite in the high-temperature expansion device. High-value utilization of low-carbon, efficient, green and sustainable retired lithium ion battery negative electrodes is achieved, and the method is suitable for continuous large-scale production of expanded graphite materials.

Description

Technical Field

[0001] The utility model belongs to the technical field of lithium ion recovery, and in particular relates to a device for continuously preparing expanded graphite material from negative electrodes of waste lithium ion batteries. Background Art

[0002] To meet the needs of sustainable development, the lithium-ion battery market continues to expand. However, due to the limited service life of lithium batteries, a wave of retirement has swept in, but the actual recycling volume is less than 38.5%, which brings environmental pressure and safety hazards. As an important part of solid waste, lithium-ion batteries will inevitably bring extensive and profound energy and environmental problems if they are not handled properly. In the industrial field, high-temperature pyrolysis, chemical dissolution and other methods are generally used to recycle the precious metal part of the positive electrode of lithium-ion batteries for recycling. However, the current recycling methods rarely pay attention to the recovery of negative electrode graphite. The negative electrode part is mostly incinerated, the product is single, the energy consumption required is high, it is easy to cause waste gas pollution, and the recovery rate is low. Utility Model Content

[0003] The utility model aims to provide a device for continuously preparing expanded graphite material from the negative electrode of waste lithium-ion batteries, so as to realize the continuous preparation of expanded graphite material from the negative electrode product graphite of retired lithium batteries.

[0004] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0005] A continuous device for preparing expanded graphite material from the negative electrode of waste lithium-ion batteries, comprising an acid washing device for negative electrode graphite intercalation reaction, a strong oxidation impurity removal device for oxidizing and dispersing dissolved graphite, and a centrifugal device with a screen inside for filtering graphite, which are sequentially connected through pipelines;

[0006] It also includes a grabbing device, which includes a track and a mechanical claw arranged on the track, which can move along the track and can move up and down to grab the screen; a centrifugal device, a drying device for continuously drying the screen transmitted by the mechanical claw, and a high-temperature expansion device for expanding graphite powder are placed in sequence below the track.

[0007] Furthermore, the pickling device comprises a pickling container, a feed pipe connected to the waste graphite transportation pipeline is arranged on the top of the pickling container, and a sulfuric acid tank for storing concentrated sulfuric acid is connected to the side wall of the pickling container.

[0008] Furthermore, a refrigeration device is arranged around the periphery of the pickling container.

[0009] Furthermore, the strong oxidation impurity removal device includes a stirrer, the top of which is connected to the discharge port of the pickling device, and the interior of the stirrer is connected to a potassium permanganate tank, a hydrogen peroxide tank and a deionized water storage tank through pipelines.

[0010] Furthermore, three spray heads are arranged on the top of the agitator, and the three spray heads are respectively connected to a potassium permanganate tank, a hydrogen peroxide tank and a deionized water storage tank through pipelines.

[0011] Furthermore, the centrifugal device comprises a centrifuge, a screen is nested in the centrifuge, and a discharge port of a strong oxidation impurity removal device, a deionized water tank and a hydrochloric acid tank are connected above the screen through pipelines.

[0012] Furthermore, the drying device comprises a drying conveyor belt for transmitting the screen, and an inlet cabin, a drying cabin and an outlet cabin are sequentially arranged on the conveyor belt.

[0013] Furthermore, it also includes a solid collecting device disposed below the track and between the drying device and the high-temperature expansion device.

[0014] The solid collecting device comprises a collecting funnel and a flipping device nested in the collecting funnel for placing a screen transported by a mechanical claw and capable of flipping. The discharge port of the collecting funnel is connected to the high-temperature expansion device through a pipeline.

[0015] Furthermore, the high-temperature expansion device comprises a tubular furnace whose feed inlet is connected to a discharge outlet of the solid collection device.

[0016] Furthermore, it also includes a screen cleaning device for cleaning the screen, and the screen cleaning device is arranged below the track of the grabbing device.

[0017] Compared with the prior art, the utility model has the following beneficial effects:

[0018] The utility model simplifies the original Hummer method disassembly process by three steps of progressive crushing and screening the negative electrode of the waste lithium-ion battery in the pickling device, the strong oxidation impurity removal device and the centrifugal device, and realizes automatic, safe and efficient collection of graphite in the negative electrode of the lithium battery. The graphite in the negative electrode of the lithium-ion battery undergoes intercalation reaction in the pickling device, is oxidized and dispersed in the strong oxidation impurity removal device, and then solid graphite oxide is separated by a screen in the centrifugal device. The screen containing the graphite oxide is moved from the centrifugal device to the drying device by a grabbing device for drying, and then the screen containing the dried graphite oxide is moved to the high-temperature expansion device. Finally, the graphite oxide is converted into high-value porous expanded graphite in the high-temperature expansion device, realizing the high-value utilization of the negative electrode of retired lithium-ion batteries with low carbon, high efficiency, green and sustainable properties. The utility model can directly prepare expanded graphite by improving the Hummer method, optimize process equipment, simplify experimental steps, shorten modification time and improve oxidation safety.

[0019] Furthermore, the utility model arranges three spray heads on the top of the agitator of the strong oxidation impurity removal device, and the three spray heads are respectively connected to the potassium permanganate tank, the hydrogen peroxide tank and the deionized water storage tank through pipelines. Adding oxidant or cleaning liquid by using the spray heads can make the additive contact with the reaction liquid more fully, so that the graphite powder in the agitator is oxidized more thoroughly and at the same time ensures that the oxidized graphite is washed more fully.

[0020] Furthermore, a centrifuge of the centrifugal device of the utility model is embedded with a screen, and the screen is connected to a deionized water tank and a hydrochloric acid tank. After the graphite oxidized by the strong oxidation and impurity removal device passes through the screen for the first solid-liquid separation, the graphite oxide solid in the screen is cleaned and impurized with hydrochloric acid and deionized water respectively, and then centrifuged to obtain pure graphite oxide, which simplifies the centrifugal washing steps of graphite oxide and provides an effective way to realize the automated development of high-performance expanded graphite materials.

[0021] Furthermore, the utility model provides an automatic drying device, which combines a conveyor belt with a drying chamber, thereby achieving the drying of graphite oxide in a simple, convenient and fully automatic manner.

[0022] Furthermore, the utility model provides a solid collecting device below the track, between the drying device and the high-temperature expansion device. The solid collecting device includes an automatic flipping device and a collecting funnel. The screen containing the intermediate product graphite oxide is fixedly placed in the flipping device at the center of the collecting funnel. After the flipping device is flipped 180°, the graphite oxide is separated from the screen and poured into the collecting funnel for collection. After the flipping device is flipped 180° again, it returns to its original position, thereby realizing the collection of the intermediate product in a simple, convenient and fully automatic manner. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 This is the principle diagram of the overall device of the utility model;

[0024] Figure 2 for Figure 1 Cross-section of the medium pickling unit;

[0025] Figure 3 for Figure 1 Schematic diagram of the structure of the medium-strong oxidation impurity removal device;

[0026] Figure 4 for Figure 1 Schematic diagram of the structure of the grabbing device;

[0027] Figure 5 for Figure 1 Schematic diagram of the centrifugal device structure;

[0028] Figure 6 for Figure 1 Cross-section of the drying device;

[0029] Figure 7for Figure 1 Schematic diagram of the structure of the solid collection device;

[0030] Figure 8 for Figure 1 Schematic diagram of the structure of the medium and high temperature expansion device;

[0031] Fig. 9 for Figure 1 Schematic diagram of the structure of the middle screen cleaning device;

[0032] In the figure: 1-pickling device, 11-feeding pipe, 12-refrigeration device, 13-pickling container, 14-sulfuric acid tank;

[0033] 2-strong oxidation impurity removal device, 21-agitator, 22-potassium permanganate tank, 23-hydrogen peroxide tank, 24-water storage tank;

[0034] 3-grasping device, 31-track, 32-mechanical claw;

[0035] 4-centrifugal device, 41-centrifuge, 42-screen, 43-sealing cover, 44-deionized water tank, 45-hydrochloric acid tank, 46-drainage tank;

[0036] 5-drying device, 51-drying conveyor belt, 52-drying cabin, 53-sliding cover, 54-vacuum pump;

[0037] 6-solid collecting device, 61-collecting funnel, 62-turning device, 63-vacuum pump, 64-transport pipeline;

[0038] 7-high temperature expansion device, 71-tube furnace, 72-product collection barrel;

[0039] 8-screen cleaning device, 81-cleaning box. DETAILED DESCRIPTION

[0040] The present invention will be further described in detail below in conjunction with specific embodiments, which are intended to explain the present invention rather than to limit it.

[0041] See also Figure 1 The utility model includes a pickling device 1, a strong oxidation impurity removal device 2, a centrifugal device 4, a drying device 5, a solid collecting device 6, a high temperature expansion device 7, a screen cleaning device 8 and a grabbing device 3. Among them, the pickling device 1, the strong oxidation impurity removal device 2 and the centrifugal device 4 are connected in sequence through pipelines, the grabbing device 3 includes a circular track arranged above the centrifugal device 4, the drying device 5, the solid collecting device 6 and the screen cleaning device 8, the grabbing device 3 is used to transfer materials to the devices below it, and the solid collecting device 6 and the high temperature expansion device 7 are connected through pipelines.

[0042] See also Figure 2The pickling device 1 includes a feed pipe 11, a refrigeration device 12, a pickling container 13 and a sulfuric acid tank 14. The feed pipe 11 is arranged on the top of the pickling container 13, and the feed pipe 11 is connected to the waste graphite transportation pipeline. The bottom of the pickling container 13 is provided with a discharge port. In order to facilitate the discharge of all the reaction liquid, the bottom of the pickling container is set to be inclined at 5°, and the discharge port is set at the lowest point of the inclination. The refrigeration device 12 is arranged on the periphery of the pickling container 13, and the refrigeration device 12 surrounds the entire pickling container 13 for cooling the pickling container 13. One side of the pickling container 13 is connected to the sulfuric acid tank 14 for storing concentrated sulfuric acid through a pipeline. When in use, the upper end of the pickling container 13 is sealed, and concentrated sulfuric acid is added into the pickling container 13 by the sulfuric acid tank 14. The coarse-screened graphite powder slowly enters the pickling container 13 from the feed pipe 11 through the graphite transport pipeline under program control. A weight detection device is also provided in the pickling container 13. The feeding time (quality) of the feed pipe 11 is controlled according to the set ratio based on the quality of the concentrated sulfuric acid; the coarse-screened graphite powder reacts with the concentrated sulfuric acid in the pickling container 13, and a tripod stirring rack is installed at the bottom of the pickling container 13 to ensure uniform mixing and sufficient reaction. A large amount of heat is generated during the reaction, and the refrigeration device 12 is used to cool the pickling container 13.

[0043] See also Figure 3 The strong oxidation impurity removal device 2 includes a stirrer 21 and a potassium permanganate tank 22, a hydrogen peroxide tank 23 and a deionized water storage tank 24 arranged on its side and connected to it through pipelines. The top of the stirrer 21 is closed and has a feed port, which is connected to the discharge port of the pickling container 13 and is located below the discharge port of the pickling container 13 in space. The stirrer 21 has a stirring paddle inside, a discharge port at the bottom, and three spray heads at the top, which are respectively connected to the potassium permanganate tank 22, the hydrogen peroxide tank 23 and the deionized water storage tank 24 through pipelines. At the same time, a gas purification device is also arranged on the top of the stirrer 21. The graphite powder mixed liquid that has completed the intercalation reaction with concentrated sulfuric acid in the pickling device 1 enters the strong oxidation impurity removal device 2 from the discharge port under the action of gravity, and then enters the agitator 21 from the feed port of the agitator 21. The agitator 21 is also provided with a weight detection device. The feeding time and sequence of the three spray heads are controlled according to the set ratio according to the mass of the mixed liquid inside the agitator 21. Under program control, potassium permanganate, hydrogen peroxide and deionized water are sprayed into the agitator 21 from the upper spray head of the agitator 21 in turn and cooperate with the stirring paddle at the bottom thereof, so that the reaction proceeds slowly and orderly in steps, and the gas generated by the reaction is purified by the top gas purification device and discharged.

[0044] See also Figure 4 The grabbing device 3 includes a track 31 arranged on the top of the centrifugal device 4, the drying device 5, the solid collecting device 6 and the screen cleaning device 8. A mechanical claw 32 is arranged on the track 31. The mechanical claw 32 has four fingers and a magnetic device is arranged at the center of the grip. The magnetic device adopts a magnetic buckle. Under program control, the mechanical claw 32 can move along the track 31 and can also move up and down to grab things.

[0045] See also Figure 5 The centrifugal device 4 includes a centrifuge 41, a screen 42, a sealing cover 43, a deionized water tank 44, a hydrochloric acid tank 45 and a drainage pool 46. The screen 42 is made of polypropylene or metal, has an inner diameter of 5.5um, and a mesh size of 2500. It is nested in the centrifuge 41 and sealed by a sealing cover 43. A small hole with a diameter of 200mm is opened at the center of the upper end of the sealing cover 43. Four mutually symmetrical grooves for diversion are arranged around the hole. The four grooves are respectively connected to the discharge port of the strong oxidation impurity removal device 2, the deionized water tank 44, the hydrochloric acid tank 45 and the drainage pool 46 through pipelines. A float for detecting the amount of liquid is built in the 1 / 4 depth of the wall of the centrifuge 10. The liquid after the strong oxidation impurity removal device 2 enters the centrifugal device 4 for centrifugation to separate and collect solids. The liquid flows from the groove into the small hole and enters the screen 42 in the centrifuge 41. When the float detects that the liquid volume has reached the corresponding height, the liquid intake is stopped, and the centrifugation is started according to the set speed and time. The waste liquid after centrifugation is led to the drainage tank 46 through the pipeline, and then the solid graphite oxide powder remaining in the screen 42 is pickled and washed with water to remove impurities. After pickling with hydrochloric acid, it is centrifuged, and then washed with deionized water and centrifuged to finally obtain the graphite powder remaining in the screen 42.

[0046] See also Figure 6 The drying device 5 includes a drying conveyor belt 51, a drying cabin 52, a sliding cover 53, a vacuum pump 54 and a refrigeration component. The drying conveyor belt 51 is located directly below the running direction of the track 31 of the grabbing device 3, and an inlet cabin, a drying cabin 52 and an outlet cabin are arranged on it in sequence. The upper part of the inlet cabin and the outlet cabin is provided with a sliding cover 53 for sealing. The vacuum pump 54 and the refrigeration component are connected to the drying cabin 52 to vacuum freeze-dry the inside. The mechanical claw 32 of the grabbing device 3 grabs the sealed screen 42 that has been centrifuged by the centrifuge 4, and then transports it to the entrance cabin of the drying conveyor 51. At this time, the hatch door between the entrance cabin and the drying cabin is closed, the upper sliding cover 53 of the entrance cabin is opened, and the vacuum state in the entrance cabin is released. The mechanical claw 32 places the screen 42 into the entrance cabin and moves it to the exit cabin to wait. The upper sliding cover of the entrance cabin is closed, and the hatch door between it and the drying cabin is opened. The vacuum pump 54 works to restore the entrance cabin and the drying cabin to the vacuum state, and the drying conveyor 51 sends the screen 42 into the drying cabin for vacuum freeze drying. After the set time is reached, the drying conveyor 17 is started, and the above method is reversed. The mechanical claw 32 grabs the screen 42 in the exit cabin and removes it from the drying device 5.

[0047] See also Figure 7The solid collecting device 6 includes a collecting funnel 61 and a turning device 62. The collecting funnel 61 is embedded with the turning device 62. The turning device 62 is arranged below the track 31 of the grabbing device 3, and includes a screen holder arranged at the center of the funnel 61 and a mechanical arm with one end fixedly connected to the screen holder and the other end mounted on the side wall of the collecting funnel 61. The mechanical arm is arranged horizontally and can rotate around the mounting position of the mechanical arm with the side wall of the collecting funnel 61. A transport pipe 64 is arranged at the bottom of the collecting funnel 61, and a vacuum pump 63 is arranged on the transport pipe. The mechanical claw 32 transfers the screen 42 to the flip device 62 in the collection funnel 61. The screen holder is provided with a magnetic device. If the screen 42 is a metal screen, it is fixed to the screen holder by the magnetic device. The mechanical claw 31 takes the sealing cover 43 on the screen 42 away to the screen cleaning device 8 for cleaning. After the mechanical arm of the flip device 62 feels the load, it rotates 180° with the screen 42, pours the solid graphite oxide powder in the screen 42 into the collection funnel 61, and then rotates the screen 42 180° to restore the initial state. The screen 42 is taken away by the mechanical claw 32 to the screen cleaning device 8 for cleaning and reuse. The graphite oxide powder collected by the collection funnel 61 is sent to the high-temperature expansion device 7 through the vacuum pump 63 and the transport pipeline 64.

[0048] See also Figure 8 The high-temperature expansion device 7 includes a tubular furnace 71 and its control components and a product collection barrel 72 arranged at the bottom of the tubular furnace. The feed port at the top of the tubular furnace 71 is connected to the outlet of the transport pipeline 64 of the solid collection device 6. The oxidized graphite powder fed into the high-temperature expansion device 7 through the solid collection device 6 enters from the entrance of the tubular furnace 71. A quality detection device is provided in the tubular furnace 71. After the quality is detected to be unchanged, the entrance is closed. Under inert gas, the furnace body is subjected to programmed temperature rise and roasting. Finally, the high-value recycled worm-like porous expanded graphite material is collected in the product collection barrel 72. By optimizing the selection of the tubular furnace, the falling expanded graphite material is naturally collected by gravity, the final product can be quickly collected, and the processing process can be simplified.

[0049] See also Fig. 9 The screen cleaning device 8 includes a cleaning box 81, in which a flushing nozzle and a drying device are arranged. The screen 42 and the sealing cover 43 are flushed and dried according to the time set by the program after entering, and then placed on the top of the cleaning box 81 for standby use. The mechanical claw 32 moves to the top of the cleaning box 81 to grab and put into the centrifugal device 4 for continued production and use.

[0050] In summary, the utility model uses concentrated sulfuric acid to intercalate graphite in the negative electrode of the waste lithium-ion battery in the pickling device to form a graphite intercalation compound, and then adds oxidants potassium permanganate and hydrogen peroxide in the strong oxidation and impurity removal device to oxidize the graphite to generate hydrophilic functional groups such as carboxylic acid and hydroxyl groups, and then adds a large amount of water to disperse the oxidized graphite in the water, and then filters out the oxidized graphite in the centrifugal device for washing. The pickling device, the strong oxidation and impurity removal device, and the centrifugal device simplify the original Hummer method disassembly process through three progressive crushing and screening, and realize the safe conversion of the waste graphite negative electrode into oxidized graphite, and then use the grabbing device to move the oxidized graphite from the centrifugal device to the drying device and the solid collection device in turn for collection, and finally in the high-temperature expansion device, the oxidized graphite is converted into high-value porous expanded graphite, realizing the low-carbon, high-efficiency, green and sustainable high-value utilization of the negative electrode of retired lithium-ion batteries. The experimental steps are simplified and the modification time is shortened, which improves the reliability for industrial applications, greatly reduces the energy consumption of industrial processes, and achieves low-carbon, efficient, green and sustainable high-value utilization of waste lithium-ion batteries at the end of their life cycle, providing a scientific basis and technical support for the green development of waste lithium-ion battery recycling technology.

Claims

1. A continuous device for preparing expanded graphite material from the negative electrode of waste lithium-ion batteries, characterized in that: It comprises an acid washing device (1) for negative electrode graphite intercalation reaction, a strong oxidation impurity removal device (2) for oxidizing and dispersing graphite, and a centrifugal device (4) with a screen (42) inside and used for filtering graphite, which are sequentially connected through pipelines; The invention also comprises a grabbing device (3), the grabbing device (3) comprising a track (31) and a mechanical claw (32) arranged on the track and capable of moving along the track and moving up and down to grab the screen (42); a centrifugal device (4), a drying device (5) for continuously drying the screen (42) transmitted by the mechanical claw (32), and a high-temperature expansion device (7) for expanding graphite powder are sequentially arranged below the track (31).

2. The equipment for preparing expanded graphite material from the negative electrode of waste lithium-ion batteries according to claim 1, characterized in that: The pickling device (1) comprises a pickling container (13), the top of which is provided with a feed pipe (11) connected to a waste graphite transport pipeline, and the side wall of which is connected with a sulfuric acid tank (14) for storing concentrated sulfuric acid.

3. The equipment for preparing expanded graphite material from the negative electrode of waste lithium-ion batteries according to claim 2, characterized in that: A refrigeration device (12) is arranged around the periphery of the pickling container (13).

4. The equipment for preparing expanded graphite material from the negative electrode of waste lithium-ion batteries according to claim 1, characterized in that: The strong oxidation impurity removal device (2) comprises a stirrer (21), the top of which is connected to the discharge port of the pickling device (1), and the interior of which is connected to a potassium permanganate tank (22), a hydrogen peroxide tank (23) and a deionized water storage tank (24) via pipelines.

5. The equipment for preparing expanded graphite material from the negative electrode of waste lithium-ion batteries according to claim 4, characterized in that: The top of the stirrer (21) is provided with three spray heads, and the three spray heads are respectively connected to a potassium permanganate tank (22), a hydrogen peroxide tank (23) and a deionized water storage tank (24) through pipelines.

6. The equipment for preparing expanded graphite material from the negative electrode of waste lithium-ion batteries according to claim 1, characterized in that: The centrifugal device (4) comprises a centrifuge (41), a screen (42) is nested in the centrifuge (41), and the screen (42) is connected to the discharge port of the strong oxidation impurity removal device (2), a deionized water tank (44) and a hydrochloric acid tank (45) through pipelines.

7. The equipment for preparing expanded graphite material from the negative electrode of waste lithium-ion batteries according to claim 1, characterized in that: The drying device (5) comprises a drying conveyor belt (51) for transmitting the screen (42), and an inlet cabin, a drying cabin (52) and an outlet cabin are sequentially arranged on the conveyor belt (51).

8. The equipment for preparing expanded graphite material from the negative electrode of waste lithium-ion batteries according to claim 1, characterized in that: It also includes a solid collecting device (6) disposed below the track (31) and between the drying device (5) and the high-temperature expansion device (7), The solid collecting device (6) comprises a collecting funnel (61) and a flipping device (62) nested in the collecting funnel (61) for placing the screen (42) transported by the mechanical claw (32) and capable of automatic flipping. The discharge port of the collecting funnel (61) is connected to the high-temperature expansion device (7) through a pipeline.

9. The equipment for preparing expanded graphite material from the negative electrode of waste lithium-ion batteries according to claim 8, characterized in that: The high-temperature expansion device (7) comprises a tubular furnace (71) whose feed inlet is connected to a discharge outlet of a solid collecting device (6).

10. The equipment for preparing expanded graphite material from the negative electrode of waste lithium-ion batteries according to claim 1, characterized in that: It also comprises a screen cleaning device (8) for cleaning the screen (42), and the screen cleaning device (8) is arranged below the track (31) of the grabbing device (3).

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