Semi-continuous production method of graphitized precursor of artificial graphite negative electrode material

Abstract

The invention discloses a semi-continuous production method of a graphitized precursor of an artificial graphite negative electrode material. The preparation method comprises the following steps: S1, granulating raw materials in a reaction kettle, heating to 650 DEG C under the action of continuous stirring of a stirrer, and keeping the temperature for 1-4 hours to form a pre-carbonized precursor of the artificial graphite negative electrode material; s2, the granulated pre-carbonized precursor enters high-temperature continuous conveying equipment and is conveyed to a buffer bin A or a buffer bin B through the high-temperature continuous conveying equipment; s3, the pre-carbonized precursor in the buffer bin A or the buffer bin B is discharged to a continuous pre-carbonization rotary kiln through quantitative feeding equipment, and a graphitized precursor is formed after the pre-carbonized precursor is treated through the continuous pre-carbonization rotary kiln; and S4, cooling the graphitized precursor treated by the continuous pre-carbonization rotary kiln to 60 DEG C through cooling equipment. The method is particularly suitable for production of artificial graphite negative electrode materials of middle-and-high-end lithium ion batteries. And the construction cost and the operation cost are greatly reduced, the application prospect is wide, and the system is particularly worthy of popularization and application.

Description

Technical Field

[0001] The invention relates to a semi-continuous production method of a graphitized precursor of an artificial graphite negative electrode material, and belongs to the field of manufacturing artificial graphite negative electrode materials for lithium ion batteries. Background Art

[0002] At present, there are two production processes for the pre-carbonization precursor of artificial graphite negative electrode materials: intermittent reactor + intermittent cooling reactor, and continuous granulation. The continuous granulation process is currently only used in a few domestic artificial graphite negative electrode material products due to the low maturity of the equipment. The production process of the vast majority of artificial graphite negative electrode material products at home and abroad still uses the intermittent production process of intermittent reactor + intermittent cooling reactor.

[0003] There are two production processes for graphitization precursor of artificial graphite negative electrode material in China, namely pre-carbonization tunnel kiln and continuous pre-carbonization rotary kiln. Both production processes are relatively mature. Tunnel kiln has the advantages of large single-furnace output, low energy consumption and high product quality, but the amount of auxiliary material crucible is large and the equipment for loading and unloading crucible is not mature enough, which results in high operating cost and low automation degree of loading and unloading crucible. Continuous pre-carbonization rotary kiln is a set of continuous production equipment. No manual auxiliary operation is required from the material entering the furnace to the material leaving the furnace. It has the advantages of good product quality, high automation degree, low operating cost and green environmental protection.

[0004] The graphitization precursor of artificial graphite negative electrode materials at home and abroad usually adopts the intermittent production process of intermittent reactor + intermittent cooling reactor + pre-carbonization tunnel kiln or intermittent reactor + intermittent cooling reactor + continuous pre-carbonization rotary kiln. These two processes have the following disadvantages: 1. After the materials are granulated in the reactor, they need to be cooled to below 60°C before leaving the cooling kettle, and then the pre-carbonized precursors leaving the kettle are stored in this process; subsequently, the pre-carbonized precursors undergo a low-temperature carbonization process in a pre-carbonization tunnel kiln or a continuous pre-carbonization rotary kiln, where the temperature is raised from room temperature to 950~1050°C, to form a graphitized precursor. This process allows the materials to undergo a production process of room temperature → 650°C → 60°C → room temperature → 950~1050°C. From the perspective of the theory and practice of artificial graphite negative electrode materials, the cooling process of the materials in the cooling kettle is only a simple physical cooling process, which has no effect on the product quality of the pre-carbonized precursors and graphitized precursors of artificial graphite negative electrode materials. In addition, the materials have undergone a heat treatment process at 650°C in the reactor, and the low-boiling volatiles in the materials have been fully released, so the materials do not need to be heated below 650°C in the pre-carbonization tunnel kiln or the continuous pre-carbonization rotary kiln. Therefore, the cooling process of the material in the cooling kettle and the heating process below 650°C in the pre-carbonization tunnel kiln or the continuous pre-carbonization rotary kiln waste a lot of energy.

[0005] 2. According to the traditional process, the pre-carbonized precursor discharged from the cooling kettle needs to be stored in large quantities in this process, and then transported to the pre-carbonization process by a forklift or a pneumatic conveying system, and then transported to the crucible loading device of the pre-carbonization tunnel kiln or the feed silo of the continuous pre-carbonization rotary kiln through the unpacking station or the pneumatic conveying system under the storage bin in the pre-carbonization process. This traditional process requires large-scale storage of materials in each process and a large amount of secondary transportation between each process, resulting in high equipment investment and high operating costs. Summary of the invention

[0006] The purpose of the present invention is to provide a semi-continuous production method of graphitized precursor of artificial graphite negative electrode material. The present invention can effectively solve the problems of energy waste, large number of equipment, high construction investment and high operating cost in traditional methods, and truly achieve cost reduction and efficiency improvement for enterprises.

[0007] The technical solution of the present invention is: a semi-continuous production method of graphitized precursor of artificial graphite negative electrode material, S1: The raw materials enter the reactor for granulation, and the temperature is raised to 650°C under the action of continuous stirring by the stirrer, and kept warm for 1-4 hours to form a pre-carbonized precursor of artificial graphite negative electrode material; S2: The pre-carbonized precursor after granulation enters the high-temperature continuous conveying equipment and is transported to the buffer silo A or buffer silo B by the high-temperature continuous conveying equipment; S3: The pre-carbonized precursor in the buffer silo A or the buffer silo B is fed to the continuous pre-carbonization rotary kiln through a quantitative feeding device, and is processed in the continuous pre-carbonization rotary kiln to form a graphitized precursor; S4: The graphitized precursor treated by the continuous pre-carbonization rotary kiln is cooled to 60° C. by a cooling device.

[0008] In the aforementioned semi-continuous production method of graphitized precursor of artificial graphite negative electrode material, in S2, the material output by the high-temperature continuous conveying equipment is crushed by a tubular crusher and then conveyed to a buffer silo or a buffer silo.

[0009] In the aforementioned semi-continuous production method of graphitized precursor of artificial graphite negative electrode material, in S4, the graphitized precursor cooled to 60°C by the cooling equipment enters the buffer silo C or the buffer silo D, and the graphitized precursor is packaged under the buffer silo C and the buffer silo D or transported to the next process by pneumatic conveying.

[0010] In the aforementioned semi-continuous production method of graphitized precursor of artificial graphite negative electrode material, one production system is composed of 10 to 20 reactors, 10 to 20 reactors share one high-temperature continuous conveying equipment, and 10 to 20 reactors are equipped with one continuous pre-carbonization rotary kiln. Each factory can set up multiple production systems according to production capacity requirements.

[0011] In the aforementioned semi-continuous production method of graphitized precursor of artificial graphite negative electrode material, the high-temperature continuous conveying equipment adopts a tube chain conveyor or a screw conveyor, insulation measures are arranged on the outside of the high-temperature continuous conveying equipment, and the material inside the high-temperature continuous conveying equipment is protected by nitrogen, so that it has the ability to withstand high temperatures and realize continuous material conveying.

[0012] In the aforementioned semi-continuous production method of graphitized precursor of artificial graphite negative electrode material, the buffer silo A, buffer silo B, buffer silo C and buffer silo D are all provided with stirring devices, cooling devices, sampling devices and weighing sensors, and the buffer silo A and buffer silo B are provided with insulation measures on the outside, and the volume of buffer silo A and buffer silo B should be ≥ the volume of a single reactor, and all buffer silos are provided with nitrogen or compressed air arch breaking devices at the cone position.

[0013] In the aforementioned semi-continuous production method of graphitized precursor of artificial graphite negative electrode material, the production capacity of the quantitative feeding equipment matches the production capacity of the reactor and the continuous pre-carbonization rotary kiln, and insulation measures are arranged outside the equipment.

[0014] In the aforementioned semi-continuous production method of graphitized precursor of artificial graphite negative electrode material, the production capacity of the continuous pre-carbonization rotary kiln is ≥5000t / a and matches the production capacity of the reactor.

[0015] In the aforementioned semi-continuous production method of graphitized precursor of artificial graphite negative electrode material, the cooling equipment adopts a slag cooler, a drum cooler or a water-cooled screw conveyor, and the cooling equipment adopts circulating water as the cooling medium, and nitrogen is used for protection inside.

[0016] In the aforementioned semi-continuous production method of graphitized precursor of artificial graphite negative electrode material, the temperature difference of the material from the discharge port of the reactor to the continuous pre-carbonization rotary kiln should be ≤300°C, and the feed material temperature of the continuous pre-carbonization rotary kiln should be ≥400°C.

[0017] Beneficial effects of the present invention: Compared with the prior art, the semi-continuous production method of the graphitized precursor of the artificial graphite negative electrode material of the present invention adopts the production method of intermittent reactor + high-temperature continuous conveying + continuous pre-carbonization rotary kiln, so that the material only undergoes a heat treatment process of normal temperature → 650°C granulation → high temperature above 400°C → 950-1050°C, which can save a lot of energy. At the same time, high-temperature continuous conveying equipment is used to convey the material between the granulation reactor and the continuous pre-carbonization rotary kiln, realizing the semi-continuous production mode of "intermittent granulation of a single intermittent reactor + continuous unloading of the reactor in 1 set of production system + high-temperature continuous conveying + continuous pre-carbonization rotary kiln", which effectively reduces the investment and operation costs. Specifically, it has the following advantages: ① It can solve the problem of energy waste. The present invention no longer sets up a cooling kettle. After the material is subjected to high temperature in the granulation kettle, it directly enters the continuous pre-carbonization rotary kiln through a high-temperature continuous conveying device. The temperature of the material drops below 250°C during the conveying and caching process, which can effectively save the energy required for the material to be cooled by 630°C in the cooling kettle and heated to 380°C in the continuous pre-carbonization rotary kiln.

[0018] ② It can effectively reduce investment. The present invention no longer has a cooling kettle, and the granulation process of forming a pre-carbonized precursor and the pre-carbonization process of forming a graphitized precursor are combined into one process. The equipment is closely connected, a large amount of factory buildings are saved, and the equipment investment and factory building investment can be effectively reduced.

[0019] ③ It can effectively save floor space. The present invention combines the granulation process of forming a precarbonized precursor and the precarbonization process of forming a graphitized precursor into one process, and the upstream and downstream equipment are closely connected, while reducing a large amount of intermediate product storage space, which can effectively save floor space.

[0020] ④ It can effectively reduce operating costs. The present invention no longer requires a cooling kettle, and the semi-continuous production process can reduce a large number of intermediate product transfer equipment, which can effectively reduce the use of electricity and public utilities, thereby reducing operating costs.

[0021] In summary, compared with the prior art, the present invention has significant advantages, greater strengths, broad application prospects, and is particularly worthy of popularization and application. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Attached Figure 1 It is a schematic diagram of the process flow of the present invention; Figure numerals: 1-reactor, 2-high temperature continuous conveying equipment, 3-buffer silo A, 4-buffer silo B, 5-tubular crusher, 6-quantitative feeding equipment, 7-continuous pre-carbonization rotary kiln, 8-cooling equipment, 9-buffer silo C, 10-buffer silo D. DETAILED DESCRIPTION

[0023] The present invention is further described below in conjunction with the accompanying drawings and embodiments, but they are not intended to limit the present invention.

[0024] Embodiments of the present invention: A semi-continuous production method of a graphitized precursor of an artificial graphite negative electrode material, S1: The raw materials enter the reactor 1 for intermittent granulation, and are heated to 650°C under the action of continuous stirring by the stirrer, and kept warm for 1-4 hours to form a pre-carbonized precursor of artificial graphite negative electrode material; S2: the pre-carbonized precursor after granulation enters the high-temperature continuous conveying device 2, and is conveyed by the high-temperature continuous conveying device 2 to the tubular crusher 5 for crushing and then conveyed to the buffer silo A3 or the buffer silo B4; S3: the pre-carbonized precursor in the buffer silo A3 or the buffer silo B4 is fed to the continuous pre-carbonization rotary kiln 7 through the quantitative feeding device 6, and is processed in the continuous pre-carbonization rotary kiln 7 to form a graphitized precursor; S4: The graphitized precursor treated by the continuous pre-carbonization rotary kiln 7 is cooled to 60° C. by a cooling device 8; S5: The graphitized precursor cooled to 60° C. by the cooling device 8 enters the buffer silo C9 or the buffer silo D10. The graphitized precursor is packaged under the buffer silo C9 and the buffer silo D10 or transported to the next process by pneumatic conveying.

[0025] A production system is composed of 10 to 20 reactors 1, which share a high-temperature continuous conveying device 2. A continuous pre-carbonization rotary kiln 7 is set for each of the 10 to 20 reactors 1. Each factory can set up multiple production systems according to production capacity requirements. The 10 to 20 reactors 1 are unloaded alternately in sequence according to production requirements or 1 to 3 reactors are unloaded at the same time. The unloading time of each reactor 1 is controlled within 30 minutes, so that the materials of all reactors 1 used in a production system can continuously enter the high-temperature continuous conveying device 2 (a pipe chain conveyor in the attached figure).

[0026] The high-temperature continuous conveying equipment 2 can adopt a tube chain conveyor or a screw conveyor. Insulation measures are set on the outside of the high-temperature continuous conveying equipment 2 to ensure that the surface temperature of the equipment is not higher than 50°C. The material inside the high-temperature continuous conveying equipment 2 is protected by nitrogen to avoid oxidation of the material, so that it has the ability to resist high temperatures and realize continuous material conveying.

[0027] The buffer silo A3, buffer silo B4, buffer silo C9 and buffer silo D10 are all equipped with stirring devices, cooling devices, sampling devices and weighing sensors. The buffer silo A3 and buffer silo B4 are provided with heat preservation measures to prevent the surface temperature of buffer silo A3 and buffer silo B from being too high. The volume of buffer silo A3 and buffer silo B4 should be ≥ the volume of a single reactor 1 to ensure that there is enough volume to accommodate the materials produced by reactor 1. All buffer silos are equipped with nitrogen or compressed air arch breaking devices at the cone position, which can prevent material blockage and oxidation. The stirring device in the buffer silo can ensure that the material in the silo is uniform. At the same time, the buffer silo is provided with a sampling device. A cooling mechanism can also be provided inside the sampling device to quickly cool the sample to room temperature to facilitate manual sampling. The buffer silo A3 and the buffer silo B4 are provided with an adjustable water cooling device. When the sampling inspection is qualified, the silo material enters the continuous pre-carbonization rotary kiln 7 through the quantitative feeding equipment 6. When the material inspection is unqualified, the silo material can adjust the cooling speed so that the material in the silo is cooled to 60°C within 30 minutes. The silo material is packaged for temporary storage or sent to the silo in front of the reactor 1 through a pneumatic conveying system for re-granulation.

[0028] The production capacity of the quantitative feeding device 6 matches the production capacity of the reaction kettle 1 and the continuous pre-carbonization rotary kiln 7, and insulation measures are arranged outside the device to prevent the surface temperature of the device from being too high.

[0029] The production capacity of the continuous pre-carbonization rotary kiln 7 is ≥5000t / a and matches the production capacity of the reactor 1.

[0030] The cooling device 8 adopts a slag cooler, a drum cooler or a water-cooled screw conveyor. The cooling device 8 adopts circulating water as a cooling medium and is protected by nitrogen inside to avoid oxidation of the material.

[0031] The temperature difference of the material from the discharge port of the reactor 1 to the continuous pre-carbonization rotary kiln 7 should be ≤300°C, and the feed material temperature of the continuous pre-carbonization rotary kiln 7 should be ≥400°C.

Claims

1. A semi-continuous production method of graphitized precursor of artificial graphite negative electrode material, characterized in that: S1: the raw materials enter the reactor (1) for granulation, and are heated to 650°C under the action of continuous stirring by the stirrer, and kept at this temperature for 1-4 hours to form a pre-carbonized precursor of artificial graphite negative electrode material; S2: the pre-carbonized precursor after granulation enters the high-temperature continuous conveying device (2), and is conveyed by the high-temperature continuous conveying device (2) to the buffer silo A (3) or the buffer silo B (4); S3: the pre-carbonized precursor in the buffer silo A (3) or the buffer silo B (4) is fed to the continuous pre-carbonization rotary kiln (7) via the quantitative feeding device (6), and is processed in the continuous pre-carbonization rotary kiln (7) to form a graphitized precursor; S4: The graphitized precursor treated in the continuous pre-carbonization rotary kiln (7) is cooled to 60° C. by a cooling device (8).

2. The semi-continuous production method of a graphitized precursor of an artificial graphite negative electrode material according to claim 1, characterized in that: In S2, the material outputted from the high-temperature continuous conveying device (2) is crushed by the tubular crusher (5) and then conveyed to the buffer silo (3) or the buffer silo (4).

3. The semi-continuous production method of a graphitized precursor of an artificial graphite negative electrode material according to claim 1, characterized in that: In S4, the graphitized precursor cooled to 60°C by the cooling device (8) enters the buffer silo C (9) or the buffer silo D (10), and the graphitized precursor is packaged under the buffer silo C (9) and the buffer silo D (10) or transported to the next process by pneumatic conveying.

4. The semi-continuous production method of a graphitized precursor of an artificial graphite negative electrode material according to claim 1, characterized in that: One set of production system is composed of 10 to 20 reactors (1), and the 10 to 20 reactors (1) share one high-temperature continuous conveying device (2). The 10 to 20 reactors (1) are equipped with one continuous pre-carbonization rotary kiln (7). Each factory can be equipped with multiple production systems according to production capacity requirements.

5. The semi-continuous production method of graphitized precursor of artificial graphite negative electrode material according to claim 1, characterized in that: The high temperature continuous conveying equipment (2) adopts a tube chain conveyor or a screw conveyor, and the high temperature continuous conveying equipment (2) is provided with heat preservation measures on the outside, and the internal material of the high temperature continuous conveying equipment (2) is protected by nitrogen, so that the high temperature continuous conveying equipment (2) has the ability to resist high temperature and realize continuous material conveying.

6. The semi-continuous production method of a graphitized precursor of an artificial graphite negative electrode material according to claim 1, characterized in that: The buffer silo A (3), buffer silo B (4), buffer silo C (9) and buffer silo D (10) are all provided with a stirring device, a cooling device, a sampling device and a weighing sensor. The buffer silo A (3) and buffer silo B (4) are provided with heat preservation measures on the outside. The volume of the buffer silo A (3) and buffer silo B (4) should be greater than or equal to the volume of a single reactor (1). All buffer silos are provided with nitrogen or compressed air arch breaking devices at the cone position.

7. The semi-continuous production method of graphitized precursor of artificial graphite negative electrode material according to claim 1, characterized in that: The production capacity of the quantitative feeding device (6) matches the production capacity of the reaction kettle (1) and the continuous pre-carbonization rotary kiln (7), and thermal insulation measures are arranged outside the device.

8. The semi-continuous production method of graphitized precursor of artificial graphite negative electrode material according to claim 1, characterized in that: The production capacity of the continuous pre-carbonization rotary kiln (7) is ≥5000t / a and matches the production capacity of the reaction kettle (1).

9. The semi-continuous production method of graphitized precursor of artificial graphite negative electrode material according to claim 1, characterized in that: The cooling device (8) adopts a slag cooler, a cylindrical cooler or a water-cooled screw conveyor. The cooling device (8) adopts circulating water as a cooling medium and nitrogen is used for protection inside.

10. The semi-continuous production method of graphitized precursor of artificial graphite negative electrode material according to claim 1, characterized in that: The temperature difference of the material from the discharge port of the reactor (1) to the continuous pre-carbonization rotary kiln (7) should be ≤300°C, and the feed material temperature of the continuous pre-carbonization rotary kiln (7) should be ≥400°C.

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