Rotary furnace for source dust fall for recycling waste lithium batteries

Abstract

The invention discloses a source dust falling rotary furnace for recycling waste lithium batteries, and belongs to the technical field of lithium battery recycling. The rotary furnace for source dust fall for recycling the waste lithium batteries comprises a feeding bin, a furnace body, a furnace tube, an exhaust hopper, a spiral conveyor and a barrel. The furnace tube is arranged in the furnace body, the barrel body is arranged in the furnace tube, and an opening is formed in the upper part of the barrel body; a conveying mechanism of the spiral conveyor is mounted in the barrel; the feeding bin is fixed above the cylinder body; the exhaust hopper is fixed on the furnace tube and communicated with the interior of the furnace tube, and the exhaust hopper is located at the feeding end of the furnace body. According to the rotary furnace provided by the invention, dust in hot gas is simply and efficiently reduced and black powder is recycled by utilizing the structure of the rotary furnace.

Description

Technical Field

[0001] The invention relates to the technical field of lithium battery recycling, and in particular to a rotary kiln for source dust reduction for recycling waste lithium batteries. Background Art

[0002] At present, the lithium battery recycling process often uses a rotary kiln to dry and pyrolyze the shredded battery materials, so as to evaporate and remove the electrolyte in the shredded materials, and to pyrolyze and remove the battery separators, binders and other organic matter in the shredded materials, so as to facilitate the separation of the positive / negative electrode powder and the aluminum foil / copper foil current collector, and facilitate the subsequent crushing, sorting and recycling of black powder, copper, aluminum, casing, etc.

[0003] During the high-temperature pyrolysis process, the pyrolysis gas containing electrolyte and organic pyrolysis components easily reacts with oxygen in the air, causing combustion or explosion. Therefore, during the pyrolysis process, inert gases such as nitrogen and carbon dioxide are usually injected into the rotary kiln to replace oxygen and dilute the oxygen concentration, and the oxygen content is controlled within 5% to prevent the occurrence of safety accidents.

[0004] Therefore, a large amount of pyrolysis gas at about 400°C will be generated during the pyrolysis operation of the rotary kiln. The pyrolysis gas contains inert gas, electrolyte and pyrolysis components of organic matter. At the same time, after the binder in the positive / negative electrode powder is pyrolyzed, the mutually bonded powder agglomerates collapse, and the lithium battery positive electrode powder with a particle size (D50) of 0.5-25μm and the lithium battery negative electrode powder with a particle size (D50) of 8-28μm are turned over in the rotary kiln. Some fine powders diffuse into the high-temperature pyrolysis gas and are discharged from the rotary kiln from the exhaust port, causing excessive loss of the battery positive / negative electrode powder (hereinafter referred to as black powder), resulting in a decrease in the black powder recovery rate, easy blockage of the exhaust pipe, increased difficulty in exhaust gas treatment, increased treatment costs, and decreased recovery efficiency.

[0005] In order to solve the problem of taking away too much black powder during the pyrolysis exhaust of the rotary furnace, professional technicians in the same industry have carried out some research, which is summarized as follows:

[0006] 1. Foshan Tianlu Intelligent Equipment Co., Ltd. applied for patent CN202311507208.8, which discloses a rotary furnace exhaust powder feeding bin. An exhaust port is provided above the feeding bin, and a settling channel is between the rotary furnace tube and the exhaust port. A barrier net is installed in the settling channel. The exhaust gas dust is decelerated and settles under its own weight. The settled material flows into the rotary furnace tube. The present invention can prevent the material from being discharged with the exhaust gas, and at the same time, the material in the exhaust gas is settled and transferred to the inside of the rotary furnace, reducing the waste of materials and improving the utilization rate of materials.

[0007] Although the feed bin can partially settle the dry dusty gas discharged from the rotary kiln, for the pyrolysis gas of the lithium battery recycling pyrolysis furnace containing small droplets of electrolyte, organic gas, etc., the static barrier net and sedimentation channel are easily blocked by the settled small droplets and black powder dust, making it difficult to carry out dust removal continuously, and it 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 disclosed an environmentally friendly rotary kiln exhaust settling chamber. After the exhaust gas carrying dust particles and other particulate impurities generated by the operation of the rotary kiln enters the chamber through the connecting pipe, some larger impurities will settle into the funnel through the larger opening at the top of the funnel due to gravity and be discharged from the bottom discharge pipe, while some smaller impurities are still floating in the chamber and are discharged from the top discharge pipe. After being intercepted and filtered by the filtering device, they are discharged into the atmosphere.

[0009] Although the settling chamber can gravity settle the dust-containing gas discharged from the rotary kiln and settle some of the larger particles, the settled particles need to be reprocessed. In addition, for the pyrolysis gas of the lithium battery recycling pyrolysis furnace containing small droplets of electrolyte, organic gas, etc., the static settling chamber and the bottom dust exhaust pipe are easily blocked by the settled small droplets and black powder dust, making it difficult to carry out dust removal continuously. It is not suitable for the application of lithium battery recycling pyrolysis furnace.

[0010] 3. Some companies treat the pyrolysis gas from the lithium battery recycling rotary furnace in the subsequent tail gas treatment system after it is discharged from the furnace body, including cyclone separator dust removal, metal bag dust removal, settling chamber dust removal, conveying spiral dust removal and other methods. Although there is a certain dust removal effect, there are problems such as the need to re-process the black powder, the metal bag and pipeline are easy to be blocked, the difficulty of tail gas treatment is increased, the treatment cost is increased, and the recycling efficiency is reduced.

[0011] In summary, the existing dedusting method of pyrolysis gas in rotary furnaces for lithium battery recycling has failed to effectively solve the problem of high dust concentration in exhaust gas, resulting in a decrease in black powder recovery rate, easy blockage of exhaust pipes, increased difficulty in exhaust gas treatment, increased treatment costs, and decreased recovery benefits. Based on the general solutions of the prior art, it is difficult to think of using the structure of the rotary furnace itself to simply and efficiently reduce dust in hot gas and achieve the technical problem of black powder recovery. Summary of the invention

[0012] Based on the common solutions of the prior art, it is difficult to think of using the structure of the rotary kiln itself to simply and efficiently reduce the dust in the hot air and realize the technical problem of recovering the black powder.

[0013] The purpose of the present invention is to overcome the above-mentioned technical deficiencies and provide a rotary kiln for source dust reduction for recycling of waste lithium batteries, so as to solve the technical problem in the prior art of how to utilize the structure of the rotary kiln itself to simply and efficiently reduce the dust in the pyrolysis gas and realize the recovery of black powder.

[0014] In order to achieve the above technical purpose, the technical solution of the present invention provides a rotary furnace for dust reduction at the source for recycling waste lithium batteries, comprising: a feed bin, a furnace body, a furnace pipe, an exhaust hopper, a screw conveyor and a cylinder;

[0015] The furnace tube is arranged in the furnace body, the cylinder is installed in the furnace tube, and the top of the cylinder is open;

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

[0017] The exhaust hopper is fixed on the furnace tube and communicated with the interior of the furnace tube. The exhaust hopper is located at the feeding end of the furnace body.

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

[0019] In any embodiment, it further comprises blades, wherein the blades are fixed on the inner wall of the furnace tube.

[0020] In any embodiment, a discharge hopper is further included, and the discharge hopper 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 opened on the top of the cylinder.

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

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

[0025] In any embodiment, a gate valve is further included, and the gate valve is installed on the feed bin.

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

[0027] Compared with the prior art, the beneficial effects of the present invention include: the shredded lithium battery crushed materials are added from the feed bin and fall into the conveying part of the screw conveyor, and are spirally conveyed into the furnace tube by the screw conveyor. The furnace body heats the furnace tube, and the crushed materials in the furnace tube are pyrolyzed and conveyed to the furnace tail as the furnace tube rotates. A large amount of pyrolysis gas is generated when the crushed materials are pyrolyzed. The pyrolysis gas passes through the spiral mechanism, and most of the dust is blocked by the material in the spiral mechanism. Then, the pyrolysis gas enters the exhaust hopper from the upper opening of the cylinder and is discharged. Therefore, with relatively minor changes to the rotary kiln, the dust in the pyrolysis gas is simply and efficiently reduced by utilizing the structure of the rotary kiln itself, and the black powder is retained in the furnace tube, thereby realizing the recovery of the black powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of a rotary kiln for source dust reduction for recycling of waste lithium batteries according to Example 1 of the present invention.

[0029] Figure 2 It is a right side view of the furnace tube of Example 1 of the present invention.

[0030] Figure 3 It is a schematic diagram of the internal structure of the cylinder of Example 1 of the present invention.

[0031] Explanation of the reference numerals: 1. feed bin; 2. furnace body; 3. furnace tube; 4. exhaust hopper; 5. screw conveyor; 6. cylinder body; 7. baffle; 8. blade; 9. discharge hopper; 10. gate valve; 101. first sub-gate valve; 102. second sub-gate valve; 11. bracket. DETAILED DESCRIPTION

[0032] The "range" disclosed in this application is defined in the form of a lower limit and an upper limit, and a given range is defined by selecting a lower limit and an upper limit, and the selected lower limit and upper limit define the boundaries of the particular range. The range defined in this way can be inclusive or exclusive of the end values, and can be arbitrarily combined, that is, any lower limit can be combined with any upper limit to form a range.

[0033] If there is no special explanation, the "include" and "comprising" mentioned in this application are open-ended or closed-ended. For example, the "include" and "comprising" may mean that other components not listed may also be included or only the listed components may be included or only the listed components may be included.

[0034] If not specifically stated, in this application, the term "or" is inclusive. For example, the phrase "A or B" means "A, B, or both A and B". More specifically, any of the following conditions satisfies the condition "A or B": 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] In order to make the purpose, technical solution and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0036] In the present invention, reference is made to “some embodiments”, “this embodiment”, examples, etc., which describe a subset of all possible embodiments, but it can be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments and may be combined with each other without conflict.

[0037] If similar descriptions of "first / second" appear in the application documents, the following instructions are added. In the following description, the terms "first\second\third" involved are merely used to distinguish similar objects and do not represent a specific ordering of the objects. It can be understood that "first\second\third" can 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 association relationship between associated objects, indicating that three relationships may exist. For example, object A and / or object B may represent three situations: object A exists alone, object A and object B exist at the same time, and object B exists alone.

[0039] The following is an explanation of the embodiments of the present application. The embodiments described below are exemplary and are only used to explain the present application, and should not be construed as limiting the present application.

[0040] Example 1

[0041] Combination Figure 1-3 , this embodiment proposes a rotary furnace for dust reduction at the source for recycling waste lithium batteries, comprising: a feed bin 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 arranged in the furnace body 2, the cylinder 6 is installed in the furnace tube 3, and the top of the cylinder 6 is open;

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

[0044] The exhaust hopper 4 is fixed on the furnace tube 3 and communicated with the interior of the furnace tube 3 . The exhaust hopper 4 is located at the feeding end of the furnace body 2 .

[0045] On the basis of the above embodiment, 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 block part of the dust before entering the conveying mechanism, which can further reduce the dust in the pyrolysis gas. The baffle 7 can be one or more pieces or a continuous dust blocking box.

[0046] On the basis of the above embodiment, this embodiment further includes blades 8, and the blades 8 are fixed on the inner wall of the furnace tube 3. After the pyrolysis gas goes out from the opening of the cylinder 6, the blades 8 further block the dust, thereby further reducing the dust in the pyrolysis gas.

[0047] On the basis of the above embodiment, this embodiment further includes a discharge hopper 9, which is arranged at the discharge end of the furnace body 2. The crushed material is pyrolyzed and transported to the furnace tail as the furnace tube 3 rotates (it should be noted that the rotation of the furnace tube can be achieved by existing technology and will not be described in detail here), and is discharged from the discharge hopper 9. In order to reduce the oxygen content in the furnace tube 3, nitrogen is injected into the furnace tube 3 through the discharge hopper 9, which also facilitates the discharge of pyrolysis gas from the feed end of the furnace tube 3.

[0048] On the basis of the above embodiment, the cylinder 6 in this embodiment is a U-shaped cylinder 6 with an open top, so as to facilitate the pyrolysis gas to further contact with the blades 8 of the furnace body 2 to further intercept dust.

[0049] On the basis of the above embodiment, the blade 8 of this embodiment is a spiral blade, which is convenient for conveying materials and helps to intercept dust.

[0050] On the basis of the above embodiment, the screw conveyor 5 of this embodiment is a double screw conveyor. In some embodiments, the screw conveyor 5 can also be a single screw conveyor.

[0051] On the basis of the above embodiment, this embodiment further comprises a gate valve 10, and the gate valve 10 is installed on the feed bin 1. The gate valve 10 realizes the sealing and opening of the feed port.

[0052] On the basis of the above embodiment, this embodiment further comprises a first sub-gate valve 101 and a second sub-gate valve 102, which are sequentially installed on the feed bin 1 from top to bottom, so as to facilitate the control of the feed of the feed port.

[0053] On the basis of the above embodiment, this embodiment further includes a bracket 11, and the bracket 11 is fixed on the outer wall of the cylinder 6 located outside the furnace tube 3. The bracket 11 is used to support the cylinder 6.

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

[0055] The shredded lithium battery crushed materials are added from the feed bin 1, and the air is replaced by the first sub-gate valve 101 and the second sub-gate valve 102, and the crushed materials are sealed and dropped to the conveying mechanism of the screw conveyor 5, and are spirally conveyed to the rotary furnace tube by the screw conveyor 5. The furnace body 2 heats the furnace tube 3, and the crushed materials in the furnace tube 3 are pyrolyzed and conveyed to the furnace tail as the furnace tube 3 rotates, and are discharged from the furnace tube 3 after being sealed by the gate valve from the discharge hopper 9. A large amount of pyrolysis gas is generated during the pyrolysis of the crushed materials. 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. It enters the tail gas treatment system of the prior art for treatment and is discharged outdoors after meeting the standards.

[0056] Example 2

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

[0058] Other beneficial effects of the present invention:

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

[0060] 2. Dust separation is achieved through the dust reduction effect of 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 on the dust-containing pyrolysis gas.

[0061] 3. The separated dust is directly returned to the inside of the furnace tube through the reverse conveying effect of 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.

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

[0063] 6. The temperature inside the furnace is about 400℃, which will not condense the electrolyte vapor and organic gas 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 feeding double screw, it can also assist in heating the material, achieving a certain energy-saving effect.

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

Claims

1. A rotary kiln for dust reduction at the source for recycling waste lithium batteries, characterized in that: include: Feed bin, furnace body, furnace tube, exhaust hopper, screw conveyor and cylinder; The furnace tube is arranged in the furnace body, the cylinder is installed in the furnace tube, and the top of the cylinder is open; The conveying mechanism of the screw conveyor is installed in the cylinder; the feed bin is fixed above the cylinder; The exhaust hopper is fixed on the furnace tube and communicated with the interior of the furnace tube. The exhaust hopper is located at the feeding end of the furnace body.

2. The rotary kiln for dust reduction at the source for recycling waste lithium batteries according to claim 1, characterized in that: It also includes a baffle, which is fixed between the furnace tube and the cylinder.

3. The rotary kiln for dust reduction at the source for recycling waste lithium batteries according to claim 1, characterized in that: It also includes blades, which are fixed on the inner wall of the furnace tube.

4. The rotary kiln for dust reduction at the source for recycling waste lithium batteries according to claim 1, characterized in that: It also includes a discharge hopper, which is fixed to the discharge end of the furnace body.

5. The rotary kiln for dust reduction at the source for recycling waste lithium batteries according to claim 1, characterized in that: The cylinder is a U-shaped cylinder with an open top.

6. The rotary kiln for dust reduction at the source for recycling waste lithium batteries according to claim 1, characterized in that: A through hole is provided on the top of the cylinder.

7. The rotary kiln for dust reduction at the source for recycling waste lithium batteries according to claim 3, characterized in that: The blades are spiral blades.

8. The rotary kiln for dust reduction at the source for recycling waste lithium batteries according to claim 1, characterized in that: The screw conveyor is a double screw conveyor.

9. The rotary kiln for dust reduction 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 bin.

10. The rotary kiln for dust reduction at the source for recycling waste lithium batteries according to claim 9, characterized in that: The gate valve comprises a first sub-gate valve and a second sub-gate valve, and the first sub-gate valve and the second sub-gate valve are sequentially installed on the feed bin from top to bottom.

Images