Rotary furnace for recycling waste lithium battery with source dust

Abstract

The application discloses a rotary furnace for source dust reduction in waste lithium battery recycling, and belongs to the technical field of lithium battery recycling. The rotary furnace for source dust reduction in waste lithium battery recycling comprises a feeding bin, a furnace body, a furnace pipe, an exhaust hopper, a screw conveyor and a cylinder body. The furnace pipe is arranged in the furnace body, the cylinder body is installed in the furnace pipe, and the cylinder body is open at the top. The conveying mechanism of the screw conveyor is installed in the cylinder body. The feeding bin is fixed above the cylinder body. The exhaust hopper is fixed on the furnace pipe and communicates with the inside of the furnace pipe. The exhaust hopper is located at the feeding end of the furnace body. The rotary furnace can simply and efficiently reduce dust in hot gas and realize black powder recycling.

Description

Technical Field

[0001] This invention relates to the field of lithium battery recycling technology, specifically to a rotary kiln for dust reduction at the source in the recycling of waste lithium batteries. Background Technology

[0002] Currently, the lithium battery recycling process commonly uses rotary kilns to dry and pyrolyze the shredded battery material. This process evaporates the electrolyte from the shredded material and pyrolyzes the organic matter such as battery separators and binders from the shredded material. This facilitates the separation of positive / negative electrode powder from aluminum / copper foil current collectors, which is beneficial for the subsequent crushing, sorting, and recycling of black powder, copper, aluminum, and casing.

[0003] During high-temperature pyrolysis, pyrolysis gases containing electrolyte and organic pyrolysis components are prone to react with oxygen in the air, causing combustion or explosion. Therefore, during pyrolysis, inert gases such as nitrogen and carbon dioxide are usually injected into the rotary kiln to replace oxygen and dilute the oxygen concentration, keeping the oxygen content below 5% to prevent safety accidents.

[0004] Therefore, the rotary kiln generates a large amount of pyrolysis gas at around 400°C during pyrolysis. This pyrolysis gas contains inert gas, electrolyte, and organic pyrolysis components. Simultaneously, after the binder in the positive / negative electrode powders pyrolyzes, the bonded powder clumps collapse. Lithium battery positive electrode powder with a particle size (D50) of 0.5-25μm and lithium battery negative electrode powder with a particle size (D50) of 8-28μm tumble in the rotary kiln. Some fine powder diffuses into the high-temperature pyrolysis gas and is discharged from the rotary kiln through the exhaust port, resulting in excessive loss of battery positive / negative electrode powder (hereinafter referred to as black powder). This leads to a decrease in black powder recovery rate, easy blockage of exhaust pipes, increased difficulty in tail gas treatment, increased treatment costs, and decreased recycling efficiency.

[0005] To address the issue of excessive black powder being carried away during the exhaust process of rotary kiln pyrolysis, professionals in the industry have conducted some research, which is summarized below:

[0006] 1. Foshan Tianlu Intelligent Equipment Co., Ltd. has applied for patent CN202311507208.8, which discloses a rotary kiln exhaust and powder return feeding hopper. An exhaust port is provided above the feeding hopper, and a settling channel is located between the rotary kiln tube and the exhaust port. A baffle net is installed inside the settling channel, causing the exhaust dust to slow down and settle under its own weight. The settled material flows into the rotary kiln tube. This invention can prevent material from being discharged with the exhaust gas, while simultaneously settling the material in the exhaust gas and transferring it into the rotary kiln, reducing material waste and improving material utilization.

[0007] Although the feed hopper can partially settle the dry, dusty gas discharged from the rotary kiln, the static barrier net and settling channel are easily blocked by the settled droplets and black dust in the pyrolysis gas of the lithium battery recycling pyrolysis furnace, which contains small droplets such as electrolyte and organic gases. This makes it difficult to carry out dust removal continuously and is not suitable for the application of lithium battery recycling pyrolysis furnace.

[0008] 2. Xiamen Juchen Electromechanical Technology Co., Ltd. applied for patent CN202221537841.2, which discloses an environmentally friendly rotary kiln exhaust settling chamber. The exhaust gas, carrying dust particles and other particulate impurities, generated during rotary kiln operation enters the chamber through a connecting pipe. Some larger particles settle into the funnel due to gravity through the larger opening at the top and are discharged through the bottom discharge pipe. Smaller particles remain floating in the chamber and are discharged through the top discharge pipe. After being filtered by a filtration device, the particles are released into the atmosphere.

[0009] Although the settling chamber can allow gravity settling of dust-laden gas discharged from the rotary kiln, resulting in the settling of some larger particles, the settled particles need to be reprocessed. Furthermore, for pyrolysis gas from lithium battery recycling pyrolysis furnaces containing small droplets such as electrolyte and organic gases, the static settling chamber and bottom dust discharge pipe are easily clogged by the settled small droplets and black dust, making continuous dust removal difficult. Therefore, it is not suitable for applications in lithium battery recycling pyrolysis furnaces.

[0010] 3. Some companies treat the exhaust gas from the lithium battery recycling rotary kiln after it has been discharged from the kiln, using subsequent tail gas treatment systems. These systems include cyclone separators, metal bag filters, settling chambers, and conveyor screw conveyors. While these methods offer some dust removal, they also present challenges such as the need for reprocessing of the black powder, easy clogging of metal bags and pipes, increased difficulty in tail gas treatment, higher treatment costs, and reduced recycling efficiency.

[0011] In summary, existing dust removal methods for rotary kiln pyrolysis gas in lithium battery recycling have failed to effectively address the high dust concentration in the exhaust gas, leading to decreased black powder recovery rates, easy blockage of exhaust pipes, increased difficulty in tail gas treatment, higher processing costs, and reduced recycling efficiency. Based on commonly used solutions in existing technologies, it is difficult to devise a simple and efficient technology to reduce dust in hot gas and achieve black powder recovery using the rotary kiln's own structure. Summary of the Invention

[0012] Based on existing technologies and common solutions, it is difficult to conceive of a simple and efficient way to reduce dust in hot gas and recover black powder using the structure of the rotary kiln itself.

[0013] The purpose of this invention is to overcome the above-mentioned technical deficiencies and provide a rotary kiln for dust reduction at the source for the recycling of waste lithium batteries, solving the technical problem in the prior art of how to use the rotary kiln's own structure to simply and efficiently reduce dust in pyrolysis gas and achieve the recovery of black powder.

[0014] To achieve the above technical objectives, the present invention provides a rotary kiln for dust reduction at the source for recycling waste lithium batteries, comprising: a feeding hopper, a furnace body, a furnace tube, an exhaust hopper, a screw conveyor, and a cylinder.

[0015] The furnace tube is disposed inside the furnace body, the cylindrical body is installed inside the furnace tube, and the top of the cylindrical body is open;

[0016] The conveying mechanism of the screw conveyor is installed inside the cylinder; the feed bin is fixed above the cylinder.

[0017] The exhaust hopper is fixed to the furnace tube and communicates with the interior of the furnace tube. The exhaust hopper is located at the feed end of the furnace body.

[0018] In any embodiment, a baffle is also included, which is fixed between the furnace tube and the cylinder.

[0019] In any embodiment, it also includes blades fixed to the inner wall of the furnace tube.

[0020] In any embodiment, a discharge hopper is also included, which is fixed to the discharge end of the furnace body.

[0021] In any embodiment, the cylinder is a U-shaped cylinder with an open top.

[0022] In any embodiment, a through hole is provided at the top of the cylinder.

[0023] In any embodiment, the blade is a helical blade.

[0024] In any embodiment, the screw conveyor is a twin-screw conveyor.

[0025] In any embodiment, a gate valve is also included, which is installed on the feed hopper.

[0026] In any embodiment, the gate valve includes a first sub-gate valve and a second sub-gate valve, which are installed sequentially from top to bottom on the feed hopper.

[0027] Compared with the prior art, the beneficial effects of the present invention include: the shredded lithium battery material is fed from the feed hopper to the conveying part of the screw conveyor, and is then conveyed into the furnace tube by the screw conveyor. The furnace body heats the furnace tube, and the shredded material in the furnace tube is pyrolyzed and conveyed to the tail of the furnace as the furnace tube rotates. A large amount of pyrolysis gas is generated during the pyrolysis of the shredded material. The pyrolysis gas passes through the screw mechanism, where most of the dust is blocked by the material in the screw mechanism, and then enters the exhaust hopper from the top opening of the cylinder and is discharged. Thus, with minimal modifications to the rotary kiln, the dust in the pyrolysis gas is reduced simply and efficiently by utilizing the rotary kiln's own structure, and the black powder is retained in the furnace tube, achieving the recovery of the black powder. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the rotary kiln for dust reduction at the source in the recycling of waste lithium batteries according to Embodiment 1 of the present invention.

[0029] Figure 2 This is a right view of the furnace tube in Embodiment 1 of the present invention.

[0030] Figure 3 This is a schematic diagram of the internal structure of the cylinder in Embodiment 1 of the present invention.

[0031] Explanation of reference numerals in the attached drawings: 1. Feed hopper; 2. Furnace body; 3. Furnace tube; 4. Exhaust hopper; 5. Screw conveyor; 6. Cylinder; 7. Baffle; 8. Blade; 9. Discharge hopper; 10. Slide valve; 101. First sub-slide valve; 102. Second sub-slide valve; 11. Support. Detailed Implementation

[0032] The "range" disclosed in this application is defined by a lower limit and an upper limit. A given range is defined by selecting a lower limit and an upper limit, which define the boundaries of the particular range. The range defined in this way can include or exclude endpoints and can be arbitrarily combined; that is, any lower limit can be combined with any upper limit to form a range.

[0033] Unless otherwise specified, the terms "comprising" and "including" as used in this application can be open-ended or closed-ended. For example, "comprising" and "including" can mean that other components not listed may also be included, or that only the listed components may be included.

[0034] Unless otherwise specified, the term "or" is inclusive in this application. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, the condition "A or B" is satisfied by any of the following conditions: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); or both A and B are true (or exist).

[0035] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0036] In this invention, the terms "some embodiments," "this embodiment," and examples are used to describe a subset of all possible embodiments. However, it is understood that "some embodiments" can be the same subset or different subsets of all possible embodiments and can be combined with each other without conflict.

[0037] If the application documents contain similar descriptions such as "first / second", the following explanation shall be added: In the following description, the terms "first / second / third" are used only to distinguish similar objects and do not represent a specific ordering of objects. It is understood that "first / second / third" may be interchanged in a specific order or sequence where permitted, so that the embodiments described herein can be implemented in an order other than that illustrated or described herein.

[0038] In this embodiment, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships. For example, object A and / or object B can represent three situations: object A exists alone, object A and object B exist simultaneously, and object B exists alone.

[0039] The following describes embodiments of this application. The embodiments described below are exemplary and are only used to explain this application, and should not be construed as limiting this application.

[0040] Example 1

[0041] Combination Figure 1-3 This embodiment proposes a rotary kiln for dust reduction at the source for recycling waste lithium batteries, including: a feeding hopper 1, a furnace body 2, a furnace tube 3, an exhaust hopper 4, a screw conveyor 5, and a cylinder 6;

[0042] The furnace tube 3 is disposed inside the furnace body 2, the cylinder 6 is installed inside the furnace tube 3, and the top of the cylinder 6 is open;

[0043] The conveying mechanism of the screw conveyor 5 is installed inside the cylinder 6; the feed bin 1 is fixed above the cylinder 6;

[0044] The exhaust hopper 4 is fixed to the furnace tube 3 and communicates with the interior of the furnace tube 3. The exhaust hopper 4 is located at the feed end of the furnace body 2.

[0045] Based on the above embodiments, this embodiment further includes a baffle 7, which is fixed between the furnace tube 3 and the cylinder 6. The pyrolysis gas first passes through the baffle 7 to trap some dust before entering the conveying mechanism, further reducing the dust content in the pyrolysis gas. The baffle 7 can be one or more pieces or a continuous dust-blocking box.

[0046] Based on the above embodiments, this embodiment further includes blades 8, which are fixed to the inner wall of the furnace tube 3. After the pyrolysis gas exits from the opening of the cylinder 6, it is further blocked by dust by the blades 8, further reducing the dust in the pyrolysis gas.

[0047] Based on the above embodiments, this embodiment further includes a discharge hopper 9, which is located at the discharge end of the furnace body 2. The crushed material is pyrolyzed and conveyed towards the tail of the furnace as the furnace tube 3 rotates (it should be noted that the rotation of the furnace tube can be achieved using existing technology, which will not be described in detail here), and is discharged from the discharge hopper 9. To reduce the oxygen content in the furnace tube 3, nitrogen gas is injected into the furnace tube 3 through the discharge hopper 9, which also facilitates the discharge of pyrolysis gases from the feed end of the furnace tube 3.

[0048] Based on the above embodiments, the cylinder 6 in this embodiment is a U-shaped cylinder 6 with an open top. This facilitates further contact between the pyrolysis gas and the blades 8 of the furnace body 2, further intercepting dust.

[0049] Based on the above embodiments, the blade 8 in this embodiment is a helical blade. This facilitates material conveying while also helping to trap dust.

[0050] Based on the above embodiments, the screw conveyor 5 in this embodiment is a twin-screw conveyor. In some embodiments, the screw conveyor 5 may also be a single-screw conveyor.

[0051] Based on the above embodiments, this embodiment also includes a gate valve 10, which is installed on the feed hopper 1. The gate valve 10 enables the sealing and opening of the feed inlet.

[0052] Based on the above embodiments, this embodiment further includes a first sub-gate valve 101 and a second sub-gate valve 102, which are installed sequentially from top to bottom on the feed hopper 1. This facilitates control of the feed inlet.

[0053] Based on the above embodiments, this embodiment also includes a support 11, which is fixed to the outer wall of the cylinder 6 located outside the furnace tube 3. The support 11 is used to support the cylinder 6.

[0054] The working process of the rotary kiln for dust suppression at the source of waste lithium battery recycling in this embodiment is as follows:

[0055] Shredded lithium battery material is fed into the feed hopper 1, undergoes air replacement through the first sub-gate valve 101 and the second sub-gate valve 102, and is sealed and dropped into the conveying mechanism of the screw conveyor 5. The screw conveyor 5 then conveys the material into the rotary furnace tube. The furnace body 2 heats the furnace tube 3. As the furnace tube 3 rotates, the shredded material inside the furnace tube 3 is pyrolyzed and conveyed towards the tail of the furnace. It is discharged from the discharge hopper 9 after being sealed by the gate valve. A large amount of pyrolysis gas is generated during the pyrolysis of the shredded material. In order to reduce the oxygen content in the furnace tube, nitrogen is generally injected into the furnace tube 3 from the discharge hopper 9. The pyrolysis gas mixed with nitrogen passes through the baffle 7, the screw conveyor 5, the U-shaped cylinder 6, and the spiral blades 8 on the inner wall of the furnace tube at the feed end, and is discharged from the exhaust hopper 4. After being treated by the existing tail gas treatment system, it is discharged outdoors in compliance with standards.

[0056] Example 2

[0057] The difference between this embodiment and the rotary kiln for dust suppression at the source of waste lithium battery recycling in Embodiment 1 is that a through hole is provided at the top of the cylinder 6 (not shown in the figure but easy to understand). In this embodiment, the top of the cylinder 6 is not completely open, but the pyrolysis gas is discharged through the through hole. The inner wall of the upper part of the cylinder 6 also has a certain blocking effect on dust.

[0058] Other beneficial effects of this invention:

[0059] 1. Reduce the dust concentration of the discharged pyrolysis gas inside the furnace tube and return the separated dust directly to the inside of the furnace tube.

[0060] 2. Dust separation is achieved through the feeding double spiral (single spiral is also acceptable) and the dust removal effect of the material in the spiral and the spiral blades on the inner wall of the furnace tube on the dust-laden pyrolysis gas.

[0061] 3. The separated dust is directly returned to the inside of the furnace tube by the reverse conveying action of the material in the spiral and the spiral blades on the inner wall of the furnace tube through the feeding double spiral (single spiral is also acceptable).

[0062] 5. The feeding double spiral (single spiral is also acceptable) and the material in the spiral and the spiral blades on the inner wall of the furnace tube have a self-cleaning effect during operation, and will not clog during continuous operation.

[0063] 6. The furnace temperature is around 400℃, which will not condense the electrolyte vapor and organic gases in the pyrolysis gas, and will not affect the normal discharge of the pyrolysis gas.

[0064] 7. When the high-temperature pyrolysis gas passes through the material in the feed twin screw, it can also assist in heating the material, thus achieving a certain energy-saving effect.

[0065] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A rotary kiln for dust reduction at the source in the recycling of waste lithium batteries, characterized in that, include: Feed hopper, furnace body, furnace tubes, exhaust hopper, screw conveyor and cylinder; The furnace tube is disposed inside the furnace body, the cylindrical body is installed inside the furnace tube, and the top of the cylindrical body is open; The conveying mechanism of the screw conveyor is installed inside the cylinder; the feed bin is fixed above the cylinder. The exhaust hopper is fixed to the furnace tube and communicates with the interior of the furnace tube. The exhaust hopper is located at the feed end of the furnace body. It also includes a baffle, which is fixed between the furnace tube and the cylinder; The cylinder is a U-shaped cylinder with an open top or the cylinder has a through hole at the top; It also includes blades, which are fixed to the inner wall of the furnace tube; It also includes a discharge hopper, which is fixed to the discharge end of the furnace body. Nitrogen gas is injected into the furnace tube through the discharge hopper to facilitate the discharge of pyrolysis gas from the feed end of the furnace tube.

2. The rotary kiln for dust suppression at the source for recycling waste lithium batteries according to claim 1, characterized in that, The blades are helical blades.

3. The rotary kiln for dust suppression at the source for recycling waste lithium batteries according to claim 1, characterized in that, The screw conveyor is a twin screw conveyor.

4. The rotary kiln for dust suppression at the source for recycling waste lithium batteries according to claim 1, characterized in that, It also includes a gate valve, which is installed on the feed hopper.

5. The rotary kiln for dust suppression at the source for recycling waste lithium batteries according to claim 4, characterized in that, The gate valve includes a first sub-gate valve and a second sub-gate valve, which are installed sequentially from top to bottom on the feed hopper.

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