Reaction device and reaction process for battery graphite negative electrode materials

Abstract

The present invention discloses a reaction device for battery graphite negative electrode materials, comprising a rotary reactor having a coating granulation section and a carbonization section, in sequence. The rotary reactor is provided with a plurality of spaced-apart heating furnaces on the outer wall of the cylinder near the feed end thereof for providing heat to the coating granulation section. The plurality of heating furnaces are arranged in sequence along the material flow direction as a first heating furnace, a second heating furnace, and a third heating furnace, and the internal temperatures T1, T2, and T3 and the residence times t1, t2, and t3 of the rotary reactor sections corresponding to the first, second, and third heating furnaces are controlled. The present invention also provides a continuous coating granulation-carbonization reaction device and process for battery graphite negative electrode materials. By controlling the temperature parameters during coating granulation, the present invention achieves a high tap density, a small specific surface area, and excellent physical and chemical properties of the coated granulated product, resulting in excellent electrochemical properties of the resulting graphite negative electrode material.

Description

Technical Field

[0001] The present invention belongs to the field of battery materials, and in particular relates to a preparation process and device for negative electrode materials. Background Art

[0002] Graphite anode materials currently used on a large scale in the lithium-ion battery industry are typically coated and granulated before graphitization to improve their electrochemical performance. Carbonization is then used to reduce volatile matter and increase tap density, thereby increasing material loading and operational safety during the graphitization process. The coating granulation-carbonization process for preparing graphite anode materials for lithium-ion batteries involves the following steps: first, petroleum coke / needle coke and asphalt are pulverized to 8-10 microns and 2-3 microns, respectively, through a pulverizer. The two are then mixed in a specific proportion and fed into a coating reactor. A resistance wire is installed outside the reactor, transferring heat through the reactor wall to the material inside. The material temperature is controlled according to a specific temperature control curve to soften and melt the asphalt, and then coat and carbonize the coke powder. However, due to the limitation of heat transfer of equipment, the maximum temperature of the material can generally only reach 650℃. Some aromatic hydrocarbons in the asphalt that require high temperature > 650℃ to decompose cannot be decomposed. The material coming out of the coated reactor needs to be cooled to <100℃ through the cooling kettle of the water-cooled jacket indirect cooling device, and then sent to the roller kiln or tunnel kiln to be heated to 1000℃ to further decompose and carbonize the aromatic hydrocarbons in the asphalt. It is then sent to the graphitization furnace to complete graphitization at about 3000℃. After cooling, it is processed to obtain the product carbon-based lithium battery graphite negative electrode material.

[0003] The existing coating granulation-carbonization process for graphite negative electrode materials for lithium-ion batteries has the following problems: 1. The main thermal equipment, the reactor and cooling kettle, are intermittently operated equipment, and the processing capacity of each equipment is low, resulting in high labor costs; 2. Due to heat transfer limitations, the processing capacity of each equipment is small and production efficiency is low; 3. The thermal system is unreasonable. The material is heated to 650°C in the coating reactor. When discharging, the material needs to be cooled to room temperature by indirect water cooling in the cooling kettle. The material is then sent to a roller kiln or tunnel kiln, heated again to around 1000°C, and then cooled to room temperature, resulting in serious energy waste.

[0004] Patent application CN113101887A discloses a continuous reaction processing device for lithium-ion battery graphite negative electrode materials / lithium-ion battery phosphates and ternary positive electrode materials, which can well solve the above problems. However, the temperature of the continuous reaction device is divided into only two zones, namely the coating granulation reaction temperature zone (medium and low temperature zone) and the carbonization temperature zone (high temperature zone). The temperature of the coating granulation section is difficult to accurately control, the heating furnace has serious temperature channeling, and traditional burner heating is difficult to meet the requirements of 250-400°C low temperature zone temperature control. The above defects and shortcomings will lead to a rapidly increasing temperature curve in the longitudinal direction of the rotary reactor, the temperature is too high during coating granulation, and the volatile volatilization rate of the material during coating granulation is too fast, resulting in a low tap density of the coated granulation product, a large specific surface area, and low physical and chemical properties of the final product. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the above background technology and provide a reaction device and a continuous coating granulation-carbonization reaction process for a battery graphite negative electrode material with high tap density and small specific surface area. To solve the above technical problems, the technical solution proposed by the present invention is as follows:

[0006] A reaction device for battery graphite negative electrode materials, comprising a rotary reactor sequentially provided with a coating granulation section and a carbonization section, wherein the rotary reactor is provided with a plurality of spaced heating furnaces on the outer wall of the cylinder on one side near the feeding end thereof for providing heat to the coating granulation section, wherein the plurality of heating furnaces are sequentially arranged along the material flow direction as a first heating furnace, a second heating furnace, and a third heating furnace, and the first heating furnace, the second heating furnace, and the third heating furnace are respectively used to control the internal temperatures T1, T2, and T3 of the heated rotary reactor sections, and the residence times t1, t2, and t3 of the materials in the rotary reactor sections corresponding to the first heating furnace, the second heating furnace, and the third heating furnace, respectively, satisfy the following relationship:

[0007]

[0008] Wherein, ρ1 is the tap density of the discharged product, ρ0 is the tap density of the initial material, β1 is the specific surface area of ​​the discharged product, β0 is the specific surface area of ​​the initial material, 250℃≤T1≤T2≤T3≤750℃, t1, t2, and t3 are all 20-180min, and the coefficient k1=(0.8-3)×10 4 ℃.min, coefficient k2=(1.5-3.5)×10 4 ℃.min, coefficient k3=(4.5-10)×10 4 ℃.min, coefficient k4=(0.5-3)×10 3 ℃.min, coefficient k5=(3-9)×10 3 ℃.min.

[0009] In the above reaction apparatus, preferably, T1, T2, and T3 are 250-400°C, 300-500°C, and 450-750°C, respectively, and t1, t2, and t3 are 20-60min, 30-100min, and 20-80min, respectively.

[0010] In the above reaction device, preferably, T1, T2, and T3 are 250-400°C, 400-450°C, and 450-650°C, respectively, and the coefficient k1 is (0.8-1.1)×10 4 ℃.min, coefficient k2=(1.6-2.0)×10 4 ℃.min, coefficient k3=(6.5-8.5)×10 4 ℃.min, coefficient k4=(0.8-2)×10 3 ℃.min, coefficient k5=(4-8)×10 3 ℃.min.

[0011] In the above reaction device, preferably, and Taking into account that the difference in temperature in each temperature interval and the residence time of the material in the interval will affect the tap density and specific surface area of ​​the product, and the main influencing factors of the tap density and specific surface area are different, the present invention needs to control the temperature, residence time and coefficient k to satisfy the above relationship.

[0012] In the above reaction device, preferably, the heating method of the first heating furnace is hot air heating, and the heating method of the second heating furnace and the third heating furnace is gas burner combustion heating.

[0013] In the above reaction device, preferably, the hot air discharged from the first heating furnace is sent to the inlet of the first combustion-supporting fan of the second heating furnace through the first induced draft fan as the combustion-supporting air of the second heating furnace to achieve energy saving of the combustion system.

[0014] Our research has found that the residence time at different temperature ranges during the coating granulation reaction significantly affects the tap density and specific surface area of ​​the coated granulation product. Specifically, within the 250-400°C range, the low-melting-point asphaltenes in the coated granulation material slowly and fully melt and coat the particle surface, while simultaneously adhering small particles to large particles to form secondary particles. This process should be given sufficient residence time to ensure that the coating reaction kinetics allow the low-melting-point asphaltenes to fully enter the pores within the particles, fill defects, reduce particle pores, and achieve comprehensive and sufficient coating of the particle surface. This prevents the low-melting-point asphaltenes from rapidly volatilizing and carbonizing due to excessive heating rates, failing to fully coat the particle surface, resulting in a decrease in tap density. After the particle surface is fully coated, the material is then slowly heated to 300-500°C to restructure and decompose the asphaltene into low-molecular substances, which are then volatilized. Some of the activated molecules in the asphaltene undergo condensation and dehydrogenation to form an intermediate phase, which is coated and fixed on the particle surface. The kinetic rate of this process must not be too high, otherwise excessive heating rates will cause the asphaltene components on the coated particle surface to quickly volatilize and form new secondary pores, resulting in an increase in specific surface area and a decrease in tap density. The asphaltene on the particle surface forms a stable partially carbonized coating, which is further expelled at 450-750°C to form semi-coke and densify. The heating rate can be appropriately increased during this process.

[0015] In a more preferred solution, in order to increase the tap density of the coated granulation product, the residence time at 250-450°C during coating granulation should be appropriately extended. In order to reduce the specific surface area of ​​the product after coating granulation, the residence time of coating granulation at 450-650°C should be appropriately extended. Based on the above research results, during the continuous coating granulation reaction, we mixed the negative electrode base material and the coating material and then passed them through specific temperature zones and specific residence times for heating reaction. The final product has a high tap density and a small specific surface area. In a more preferred solution, we chose to divide the heating furnace of the coating section of the rotary reactor into three sections. The temperature of the first heating furnace is controlled at 250-400°C, the temperature of the second heating furnace is controlled at 400-450°C, and the temperature of the third heating furnace is controlled at 450-650°C to meet the requirement of heating the material temperature zone within the range of 250-450°C in the coating section of the rotary reactor, and to prevent the temperature of the low temperature section from being uncontrolled and the reaction time in the low temperature section from being too short when a single heating furnace is used in the coating section of the rotary reactor. By adopting the coating granulation temperature zone control of the present invention and combining it with the residence time control of the material in each section, the reaction time of the material in each temperature zone can be controlled, and the final product has high density, small specific surface area and good physical and chemical properties.

[0016] In addition, the first heating furnace is heated by hot air, which makes the heating temperature easier to control and can utilize hot air for heat exchange, thus saving energy.

[0017] The present invention uses the first heating furnace, the second heating furnace and the third heating furnace to respectively control the internal temperatures T1, T2, T3 of the rotary reactor sections heated by them, and the residence times t1, t2, t3 of the materials in the rotary reactor sections corresponding to the first heating furnace, the second heating furnace and the third heating furnace respectively satisfy the above relationship, and through the control of various coefficients k1, k2, etc., it is possible to achieve control of the tap density and specific surface area of ​​the discharge product, thereby optimizing the electrochemical performance of the product.

[0018] In the above-mentioned reaction device, preferably, the rotary reactor is provided with a fourth heating furnace on the outer wall of the cylinder at the carbonization section for providing heat to the carbonization section. The fourth heating furnace is arranged close to the third heating furnace. The fourth heating furnace is used to control the internal temperature of the rotary reactor section heated by it to be between 600-1150°C, and the internal temperature of the rotary reactor section heated by the fourth heating furnace is higher than the internal temperature of the rotary reactor section heated by the third heating furnace.

[0019] In the above-mentioned reaction device, preferably, a first cooling component for preliminarily cooling the material after the carbonization section is further provided on the outer wall of the cylinder of the rotary reactor. The first cooling component is arranged close to the carbonization section, and the first cooling component is used to cool the reaction material to below 200°C; along the flow direction of the material, a second cooling component for further cooling the reaction material to below 60°C is also provided behind the first cooling component. A first cooling component is provided between the carbonization section and the intermediate discharging system of the rotary reactor to achieve cooling of the reaction material to below 200°C, and a second cooling component is provided between the intermediate discharging system and the discharging system to further cool the material to below 60°C. The first and second cooling components include a cooler, a water inlet pipe, a water outlet pipe, a spraying mechanism, a water collection tank, a return water pump, etc. The water collection tank is provided at the bottom of the rotary reactor and the cooler, and the spraying mechanism is installed above the rotary reactor and the cooler.

[0020] In the above-mentioned reaction device, preferably, the carbonized flue gas discharged from the rotary reactor is dust-removed by a flue gas dust collector and then enters a flue gas incinerator through a flue gas duct. The flue gas incinerator is provided with a hot gas exhaust outlet, which is connected to a heat exchanger and then to the hot air inlet of the first heating furnace through a hot air furnace; the flue gas duct is provided with an insulation device for preventing the carbonized flue gas from condensing in the duct.

[0021] In the above-mentioned reaction apparatus, the rotary reactor is preferably arranged at an angle, with the feed end of the rotary reactor at an elevated position and the discharge end at a lower position; the angle between the central axis of the rotary reactor and the horizontal line is ≤10°. The feed end of the rotary reactor is provided with a kiln tail box and a kiln tail sealing device, and the discharge end of the rotary reactor is provided with a kiln head box and a kiln head sealing device. The kiln tail box is provided with a flue gas outlet for discharging carbonized flue gas from the rotary reactor; the kiln tail sealing device and the kiln head sealing device are connected to nitrogen pipelines.

[0022] In the above reaction device, preferably, the first heating furnace, the second heating furnace, the third heating furnace, the fourth heating furnace and the cooling assembly are all coaxial with the rotary reactor and arranged at intervals.

[0023] As a general technical concept, the present invention also provides a continuous coating granulation-carbonization reaction process for battery graphite negative electrode materials using the above-mentioned reaction device, comprising the following steps:

[0024] S1: Start the rotary reactor, turn on the first heating furnace, the second heating furnace, the third heating furnace and the fourth heating furnace of the carbonization section, so that different parts of the rotary reactor reach the preset temperature; turn on the first cooling component;

[0025] S2: feeding the mixed material of the negative electrode base material and the coating material into the rotary reactor through a feeding system;

[0026] S3: Through the rotation and self-propulsion of the rotary reactor, the incoming material passes through the coating and granulation section (corresponding to the sections heated by the first, second and third heating furnaces), the carbonization section (corresponding to the section heated by the fourth heating furnace) and the preliminary cooling section (corresponding to the section cooled by the first cooling assembly) of the rotary reactor in sequence, and the residence time of the material in the coating and granulation section is controlled;

[0027] S4: The material after cooling treatment is sent out through a discharging system, completing the continuous coating granulation-carbonization reaction.

[0028] The reaction device for battery graphite negative electrode materials of the present invention includes a feeding system, a kiln tail box, a rotary reactor, a kiln head box, an intermediate discharging system, a second cooling assembly and a discharging system in sequence along the material flow direction. The feeding system and the intermediate discharging system are connected to the corresponding feeding end and discharging end of the rotary reactor. The rotary reactor includes a graphite negative electrode material coating and granulation section connected to the feeding end, a carbonization section and a preliminary cooling section connected to the coating and granulation section, so as to realize the continuous transportation of the reaction materials from the feeding end, the coating and granulation section, the carbonization section, the preliminary cooling section to the discharging end.

[0029] Outside the coating and granulation section of the rotary reactor are located the first, second, and third heating furnaces, which heat the reaction materials and granulate them. Outside the carbonization section of the rotary reactor is located the fourth heating furnace, which heats and carbonizes the reaction materials. Outside the first and second cooling assemblies of the rotary reactor are water spraying devices, which cool the reaction materials. The first heating furnace is heated by hot air, while the second, third, and fourth heating furnaces are heated by natural gas burners. The second, third, and fourth heating furnaces consist of a furnace body and heating elements mounted on and extending into the body. The third and fourth heating furnaces maintain higher temperatures and use regenerative burners to recover heat.

[0030] Support devices for supporting corresponding positions of the rotary reactor are installed at intervals on the outside of the rotary reactor; the rotary reactor includes a reactor body and a rotary drive component. The reactor body is arranged inside the first, second, third and fourth heating furnaces and the first cooling assembly and is connected to the feeding system and the discharging system. The rotary drive component is arranged outside the reactor body and drives the reactor body to rotate.

[0031] The rotary reactor's feeding system is connected to the kiln tail box via a feed screw mechanism. The rotary reactor's discharge end is connected to the second cooling assembly via an intermediate discharge system, and then discharged through the discharge system. The rotary reactor's inlet and outlet are equipped with kiln tail and kiln head sealing devices to prevent external air from entering the reactor. Nitrogen inlet pipes are installed at both the inlet and outlet sealing devices and the second cooling assembly to ensure that nitrogen is filled into the reactor, ensuring that the material undergoes the coating, granulation, and carbonization reaction under the protection of an inert nitrogen atmosphere.

[0032] The reaction device for battery graphite negative electrode materials of the present invention, when in operation, first starts the rotary reactor to rotate the rotary reactor; then starts the first heating furnace, the second heating furnace, the third heating furnace and the fourth heating furnace and the first and second cooling components to make the corresponding sections of the device body reach the corresponding preset temperature zone; then starts the feeding system to allow the material (such as needle coke and asphalt mixed in a certain proportion) to enter the rotary reactor through the feeding system; finally, starts the discharging system to discharge the material that has completed coating and carbonization from the discharging system. Compared with the traditional structure, this equipment realizes the continuity of battery graphite negative electrode material coating, negative electrode material carbonization and cooling processes through an integrated rotary reactor, ensures product consistency and significantly improves product quality; it replaces the current negative electrode material coating reactor coating + cooling kettle cooling + roller kiln or tunnel kiln carbonization + water indirect cooling equipment, greatly simplifies the process flow and the labor intensity and number of operators, and greatly reduces the energy consumption per ton of product, significantly reduces equipment investment, labor costs and energy consumption costs, and can realize large-scale equipment; at the same time, it is easy to realize computer automation control, which greatly reduces production costs.

[0033] Compared with the prior art, the advantages of the present invention are:

[0034] 1. The reaction device of the battery graphite negative electrode material of the present invention controls the temperature parameters during coating and granulation (the temperature and residence time satisfy the above relationship), so that the volatilization rate of the volatile matter of the material during coating and granulation is appropriate, the coated granulation product has a high tap density, a small specific surface area, and good physical and chemical properties, and the electrochemical properties of the graphite negative electrode material finally obtained are good.

[0035] 2. The reaction device for battery graphite negative electrode materials of the present invention divides the coating granulation section heating zone of the rotary reactor into three coating granulation sections, thereby avoiding the temperature channeling problem caused by the single heating temperature of the coating granulation section. The three temperature partitions of the coating granulation section can ensure that the coating granulation process is carried out effectively, the coating granulation (such as asphalt coating coke powder) reaction is carried out in an orderly manner, the volatilization rate of the volatile matter is controllable, the product tap density is higher, and the specific surface area is stable and controllable.

[0036] 3. The reaction device and process for the battery graphite negative electrode material of the present invention obtain a graphite negative electrode product with high tap density, small specific surface area and good physical and chemical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0038] Figure 1 This is the reaction device for the battery graphite negative electrode material of Example 1.

[0039] Figure 2 This is a process flow chart of the continuous coating granulation-carbonization reaction process of the battery graphite negative electrode material in Example 1.

[0040] Legend:

[0041] 1. Feeding system; 2. Kiln tail box; 3. Kiln tail sealing device; 4. Rotary reactor; 5. First heating furnace; 6. Second heating furnace; 7. Third heating furnace; 8. Fourth heating furnace; 9. First cooling assembly; 10. Kiln head sealing device; 11. Kiln head box; 12. Support device; 13. Drive device; 14. Second cooling assembly; 15. Hot blast furnace; 16. First combustion-supporting fan; 17. First induced draft fan; 18. Second induced draft fan; 19. Second combustion-supporting fan; 20. Third induced draft fan; 21. Water collection tank; 22. Return water pump; 23. Discharging system; 24. Flue gas dust collector. DETAILED DESCRIPTION

[0042] To facilitate understanding of the present invention, the present invention will be described in more comprehensive and detailed form below in conjunction with the accompanying drawings and preferred embodiments. However, the protection scope of the present invention is not limited to the following specific embodiments.

[0043] Unless otherwise defined, all technical terms used hereinafter have the same meanings as those generally understood by those skilled in the art. The technical terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0044] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0045] Example 1:

[0046] like Figure 1 As shown, the reaction device for battery graphite negative electrode materials in this embodiment includes a rotary reactor 4 provided with a coating granulation section and a carbonization section in sequence. The rotary reactor 4 is provided with a plurality of spaced heating furnaces on the outer wall of the cylinder on one side near its feeding end for providing heat to the coating granulation section. The plurality of heating furnaces are sequentially arranged along the material flow direction as a first heating furnace 5, a second heating furnace 6 and a third heating furnace 7. The first heating furnace 5, the second heating furnace 6 and the third heating furnace 7 are respectively used to control the internal temperature T1, T2 and T3 of the heated sections of the rotary reactor 4 and the residence time t1, t2 and t3 of the materials in the sections of the rotary reactor 4 corresponding to the first heating furnace 5, the second heating furnace 6 and the third heating furnace 7 respectively satisfy the following relationship:

[0047]

[0048] Wherein, ρ1 is the tap density of the discharged product, ρ0 is the tap density of the initial material, β1 is the specific surface area of ​​the discharged product, β0 is the specific surface area of ​​the initial material, 250℃≤T1≤T2≤T3≤750℃, t1, t2, and t3 are all 20-180min, and the coefficient k1=(0.8-3)×10 4 ℃.min, coefficient k2=(1.5-3.5)×10 4 ℃.min, coefficient k3=(4.5-10)×10 4 ℃.min, coefficient k4=(0.5-3)×10 3 ℃.min, coefficient k5=(3-9)×10 3 ℃.min.

[0049] In this embodiment, T1, T2, and T3 are 250-400°C, 300-500°C, and 450-750°C, respectively; t1, t2, and t3 are 20-60 min, 30-100 min, and 20-80 min, respectively. A more preferred solution is that T1, T2, and T3 are 250-400°C, 400-450°C, and 450-650°C, respectively; and the coefficient k1 = (0.8-1.1) × 10 4 ℃.min, coefficient k2=(1.6-2.0)×10 4 ℃.min, coefficient k3=(6.5-8.5)×10 4 ℃.min, coefficient k4=(0.8-2)×10 3 ℃.min, coefficient k5=(4-8)×10 3 ℃.min. A further preferred solution is, and

[0050] In this embodiment, the first heating furnace 5 is heated by hot air, and the second heating furnace 6 and the third heating furnace 7 are heated by burner combustion.

[0051] In this embodiment, the hot air exhausted from the first heating furnace 5 is sent to the inlet of the first combustion-supporting fan 16 of the second heating furnace 6 through the first induced draft fan 17 as the combustion-supporting air of the second heating furnace 6.

[0052] In this embodiment, a fourth heating furnace 8 is provided on the outer wall of the cylinder of the rotary reactor 4 at the carbonization section for providing heat to the carbonization section. The fourth heating furnace 8 is arranged close to the third heating furnace 7. The fourth heating furnace 8 is used to control the internal temperature of the heated section of the rotary reactor 4 to be between 600 and 1150°C, and the internal temperature of the section of the rotary reactor 4 heated by the fourth heating furnace 8 is higher than the internal temperature of the section of the rotary reactor 4 heated by the third heating furnace 7.

[0053] In this embodiment, a first cooling component 9 for preliminarily cooling the material after the carbonization section is further provided on the outer wall of the cylinder of the rotary reactor 4. The first cooling component 9 is arranged close to the carbonization section. The first cooling component 9 is used to cool the reaction material to below 200°C; along the flow direction of the material, a second cooling component 14 for further cooling the reaction material to below 60°C is also provided behind the first cooling component 9.

[0054] In this embodiment, the carbonized flue gas discharged from the rotary reactor 4 is dust-removed by the flue gas dust collector 24 and then enters the flue gas incinerator through the flue gas duct. The flue gas incinerator is provided with a hot gas exhaust port, which is connected to the hot air inlet of the first heating furnace 5 through the hot air furnace 15 after being connected to the heat exchanger; the flue gas duct is provided with an insulation device for preventing the carbonized flue gas from condensing in the duct.

[0055] In this embodiment, the rotary reactor 4 is arranged tilted, with the feed end of the rotary reactor 4 at a high position and the discharge end at a low position; the angle between the central axis of the rotary reactor 4 and the horizontal line is ≤10°.

[0056] like Figure 2 As shown, the continuous coating granulation-carbonization reaction process of the battery graphite negative electrode material using the above-mentioned reaction device in this embodiment includes the following steps:

[0057] S1: Start the rotary reactor 4, start the first heating furnace 5, the second heating furnace 6, the third heating furnace 7 and the fourth heating furnace 8 of the carbonization section, so that different parts of the rotary reactor 4 reach the preset temperature; start the first cooling component 9;

[0058] S2: The mixture of the negative electrode base material and the coating material is fed into the rotary reactor 4 through a feeding system 1;

[0059] S3: Through the rotation and self-propelling of the rotary reactor 4, the incoming material passes through the coating and granulation section and the carbonization section of the rotary reactor 4 in sequence, and the residence time of the material in the coating and granulation section is controlled;

[0060] S4: The material after cooling is sent out through a discharging system 23, thus completing the continuous coating granulation-carbonization reaction.

[0061] Specifically, the reaction device for battery graphite negative electrode materials in this embodiment includes a feeding system 1, a kiln tail box 2, a rotary reactor 4, a kiln head box 11, an intermediate discharging system, a second cooling assembly 14 and a discharging system 23. The feeding system 1 and the discharging system 23 are docked at the corresponding feed end and discharging end of the rotary reactor 4. The rotary reactor 4 includes a graphite negative electrode material coating and granulation section connected to the feed end, a graphite negative electrode material carbonization section and a cooling section connected to the coating and granulation section, so as to realize the continuous transportation of the reaction materials from the feed end, the coating and granulation section, the carbonization section, the cooling section to the discharging end in sequence. A first heating furnace 5, a second heating furnace 6 and a third heating furnace 7 are arranged outside the coating and granulation section of the rotary reactor 4, which are used to achieve coating and granulation of the reaction materials by heating; a fourth heating furnace 8 is arranged outside the carbonization section of the rotary reactor 4, which is used to achieve carbonization of the reaction materials by heating; a water sprinkling device is arranged outside the first cooling component 9 and the second cooling component 14 of the rotary reactor 4, which is used to achieve cooling of the reaction materials by sprinkling water.

[0062] The first heating furnace 5 is heated by hot air, while the second, third, and fourth heating furnaces 6, 7, and 8 are heated by natural gas burners. During the establishment of the first, second, third, and fourth temperature fields, since there is no material in the rotary reactor 4 and no volatiles enter the incinerator for incineration, the hot air from the first heating furnace 5 is provided by a natural gas-fired hot air furnace 15. After the material enters the rotary reactor 4 for processing, the flue gas enters the incinerator for incineration. The hot air generated by the high-temperature exhaust gas from the flue gas incineration and the heat exchange with fresh air enters the hot air furnace 15, providing a heat source for the first heating furnace 5. The hot air at the outlet of the first heating furnace 5 is delivered via a first induced draft fan 17 to the inlet of the first combustion-supporting fan 16 of the second heating furnace 6, where it serves as combustion air for the second heating furnace 6, thereby achieving energy conservation in the combustion system. The second heating furnace 6 is equipped with a natural gas-fired burner. The natural gas and the combustion air introduced by the first combustion-supporting fan 16 mix and combust, releasing heat. The combustion exhaust gas from the second heating furnace 6 is discharged through a second induced draft fan 18. The third heating furnace 7 and the fourth heating furnace 8 are both provided with natural gas combustion burner devices. Natural gas and combustion air supplied by the second combustion-supporting fan 19 are mixed and burned to release heat. The combustion exhaust gas of the third heating furnace 7 and the fourth heating furnace 8 is discharged through the third induced draft fan 20.

[0063] The first cooling assembly 9 and the second cooling assembly 14 include a cooler, a water inlet pipe, a water outlet pipe, a spraying mechanism, a water collection tank 21, a return water pump 22, etc. The water collection tank 21 is arranged at the lower part of the rotary reactor 4 and the cooler, and the spraying mechanism is installed above the rotary reactor 4 and the cooler.

[0064] Nitrogen with a purity of not less than 99% is introduced into the kiln tail box 2, kiln tail sealing device 3, kiln head box 11, kiln head sealing device 10 and second cooling assembly 14 of the rotary reactor 4 so that the materials react under the protection of nitrogen inert atmosphere.

[0065] Support devices 12 are installed at intervals on the outside of the rotary reactor 4 to support corresponding positions of the rotary reactor 4. Since the rotary reactor 4 is a continuous, integrated structure with a long length, the support devices 12 are installed at each interval to facilitate the support of the rotary reactor 4 and improve the stability of the equipment.

[0066] A driving device 13 for rotationally driving the rotary reactor 4 is installed outside the rotary reactor 4 .

[0067] The flue gas outlet duct of the kiln tail box 2 of the rotary reactor 4 is equipped with a flue gas dust collector 24 (gravity / filtration treatment device) to purify the flue gas and prevent dust from settling and clogging in the subsequent flue gas duct. An electric heating device is also installed on the flue gas outlet duct of the kiln tail box 2 of the rotary reactor 4 to prevent low-boiling-point substances such as asphalt in the flue gas from condensing and clogging the flue gas duct.

[0068] Specifically, the continuous coating granulation-carbonization reaction process of the battery graphite negative electrode material of this embodiment includes the following steps: first start the rotary reactor 4 and the first cooling component 9, so that the rotary reactor 4 and the second cooling component 14 are filled with a nitrogen atmosphere; then start each heating furnace and the condensed water arranged outside the first cooling component 9 and the second cooling component 14, so that the corresponding section reaches the corresponding preset temperature zone; then start the feeding system 1, so that the mixed material (such as needle coke and asphalt) mixed in a certain proportion is transported into the rotary reactor 4 through the feeding system 1; finally, start the intermediate discharging system and the discharging system 23, so that the material that has completed coating and carbonization is output from the discharging system 23.

[0069] In order to better understand the solutions in the above embodiments, this embodiment provides a process for coating granulation-carbonization reaction of an artificial graphite-based negative electrode material, the preparation method of which includes the following steps:

[0070] (1) Petroleum coke with ash content <0.6%, sulfur content <0.5%, volatile matter <13%, and moisture content <10% is selected as raw material, which is dried to moisture content <3% using a drum dryer and then ground using a mechanical mill. The particle size distribution of the ground coke powder is D 50 =10μm, and material A was obtained.

[0071] (2) Material A and asphalt with a softening point of 200-250°C are fed into a mixer at a mass ratio of 100:4 to obtain material B; the mixed material is fed into a continuous feeding bin via a vacuum feeder, and then fed into a rotary reactor 4 via a screw conveyor, and then coated, granulated and carbonized under nitrogen protection. The angle between the axis of the rotary reactor 4 and the horizontal line is 1.5°, the rotation speed is 0.5 rpm, the temperatures of the first heating furnace 5, the second heating furnace 6, the third heating furnace 7 and the fourth heating furnace 8 are controlled to 300°C, 450°C, 650°C and 950°C, respectively. The residence time of the material in the first heating furnace 5, the second heating furnace 6, the third heating furnace 7 and the fourth heating furnace 8 are 20 min, 30 min, 20 min and 40 min, respectively. The coefficient k1 is 1×10 4 ℃.min, coefficient k2 is 1.7×10 4 ℃.min, coefficient k3 is 6.5×10 4 ℃.min, coefficient k4 is 1.9×10 3 ℃.min, coefficient k5 is 6.5×10 3 ℃.min, and after cooling in the cooling section, the coated granulated carbonized product C is obtained.

[0072] In this embodiment, the tap density of the initial raw material is 0.56 g / cm3 and the specific surface area is 3.2 m 2 / g. After the above process, the particle size distribution of the discharged material C is tested.50 =15.60μm, tap density is 0.90g / cm3, specific surface area is 1.8m 2 / g, volatile matter content <0.6%.

[0073] Example 2:

[0074] The reaction device for the battery graphite negative electrode material and the continuous coating granulation-carbonization reaction device and process for the battery graphite negative electrode material in this embodiment are the same as those in Example 1.

[0075] This embodiment provides a process for coating granulation-carbonization reaction of an artificial graphite-based negative electrode material. The coke powder in step (1) is calcined coke, and its preparation method includes the following steps:

[0076] (1) Use calcined coke with ash content <0.5%, sulfur content <0.5%, volatile matter <0.4%, and moisture <1% as raw material, grind it with a mechanical mill, and the particle size distribution of the coke powder after grinding is D 50 =8μm, and material A was obtained.

[0077] (2) Material A and asphalt with a softening point of 200-250°C are fed into a mixer at a mass ratio of 100:10 to obtain material B. The mixed material is fed into a continuous feeding bin via a vacuum feeder and then fed into a rotary reactor 4 via a screw conveyor. Then, the material is coated, granulated, and carbonized under nitrogen protection. The angle between the axis of the rotary reactor 4 and the horizontal line is 1.5°, the rotation speed is 1 rpm, and the temperatures of the first heating furnace 5, the second heating furnace 6, the third heating furnace 7, and the fourth heating furnace 8 are controlled at 250°C, 400°C, 650°C, and 950°C, respectively. The residence time of the material in the first heating furnace 5, the second heating furnace 6, the third heating furnace 7, and the fourth heating furnace 8 is 20 min, 40 min, 25 min, and 40 min, respectively. The coefficient k1 is 0.85×10 4 ℃.min, coefficient k2 is 2.3×10 4 ℃.min, coefficient k3 is 8.5×10 4 ℃.min, coefficient k4 is 1×10 3 ℃.min, coefficient k5 is 6.5×10 3 ℃.min, and after cooling in the cooling section, the coated granulated carbonized product C is obtained.

[0078] In this embodiment, the tap density of the initial raw material is 0.58 g / cm3 and the specific surface area is 4.5 m 2 / g. After the above process, the particle size distribution of the discharged material C is tested. 50 =17.50μm, tap density 0.9g / cm3, specific surface area 1.85m 2 / g, volatile matter content <0.6%.

[0079] Comparative Example 1:

[0080] The difference between this comparative example and Example 1 is that the temperature zones and residence times experienced by the material during coating granulation and carbonization in the rotary reactor 4 are different.

[0081] The specific steps include:

[0082] (1) Same as step (1) of Example 1.

[0083] (2) Material A and asphalt with a softening point of 200-250°C are fed into a mixer at a mass ratio of 100:4 for mixing to obtain material B; the mixed material is fed into a continuous feeding bin via a vacuum feeder, and then fed into a rotary reactor 4 with two temperature zones (the temperatures of the first heating furnace 5 and the second heating furnace 6 are controlled at 400-650°C (temperature range) and 950°C, respectively) via a screw conveyor, and then coated granulation and carbonization reactions are carried out under nitrogen protection. The angle between the axis of the rotary reactor 4 and the horizontal line is 1.5°, the rotation speed is 0.5 rpm, and the residence time of the material in the first heating furnace 5 and the second heating furnace 6 area is 100 min and 40 min, respectively. After cooling in the cooling section, the coated granulation carbonization product C is obtained.

[0084] After testing, the particle size distribution of material C is D 50 =13.40μm, tap density 0.68g / cm3, specific surface area 2.4m 2 / g, volatile matter content <0.6%.

[0085] Comparative Example 2:

[0086] The difference between this comparative example and Example 2 is that the temperature zones and residence times experienced by the material during coating granulation and carbonization in the rotary reactor 4 are different.

[0087] The specific steps include:

[0088] (1) Same as step (1) in Example 2.

[0089] (2) Material A and asphalt with a softening point of 200-250°C are fed into a mixer at a mass ratio of 100:10 for mixing to obtain material B; the mixed material is fed into a continuous feeding bin via a vacuum feeder, and then fed into a rotary reactor 4 with two temperature zones via a screw conveyor, and then coated granulation and carbonization reactions are carried out under nitrogen protection. The angle between the axis of the rotary reactor 4 and the horizontal line is 1.5°, the rotation speed is 1rpm, the temperatures of the first heating furnace 5 and the second heating furnace 6 are controlled at 400-650°C (temperature range) and 950°C, respectively. The residence time of the material in the first heating furnace 5 and the second heating furnace 6 is 100min and 40min, respectively. After cooling in the cooling section, the coated granulation carbonization product C is obtained.

[0090] After testing, the particle size distribution of material C is D 50 =13μm, tap density 0.69g / cm3, specific surface area 2.5m 2 / g, volatile matter content <0.6%.

[0091] Comparative Example 3:

[0092] The difference between this comparative example and Example 1 is that the residence time of the material in each temperature zone in the rotary reactor 4 during the coating granulation and carbonization treatment is different.

[0093] The specific steps include:

[0094] (1) Same as step (1) of Example 1.

[0095] (2) The other operations are the same as those in step (1) of Example 1, except that the residence time of the material in the first heating furnace 5, the second heating furnace 6, the third heating furnace 7, and the fourth heating furnace 8 are 15 min, 20 min, 20 min, and 40 min, respectively (the coefficient k1 is 0.75×10 4 ℃.min, coefficient k2 is 1.1×10 4 ℃.min, coefficient k 3-5 The same as in Example 1), after cooling in the cooling section, the coated granulated carbonized product C is obtained.

[0096] After testing, the particle size distribution of material C is D 50 =12μm, tap density 0.7g / cm3, specific surface area 2.0m 2 / g, volatile matter content <0.8%. This comparative example shows that the residence time does not meet the requirements. Even if the coefficients k1 and k2 are reduced, the tap density and specific surface area cannot reach the levels of Example 1. That is, the temperature of each zone, the residence time, and the coefficient k of the present invention all need to be reasonably controlled to achieve excellent product performance.

Claims

1. A reaction device for a graphite negative electrode material of a battery, comprising a rotary reactor (4) provided with a coating granulation section and a carbonization section in sequence, characterized in that: The rotary reactor (4) is provided with a plurality of spaced heating furnaces on the outer wall of the cylinder near the feeding end thereof for providing heat to the coating granulation section. The plurality of heating furnaces are sequentially arranged along the material flow direction as a first heating furnace (5), a second heating furnace (6) and a third heating furnace (7). The first heating furnace (5), the second heating furnace (6) and the third heating furnace (7) are respectively used to control the internal temperature of the heated section of the rotary reactor (4). T 1 、T 2 、T 3 and the residence time of the material in the sections of the rotary reactor (4) corresponding to the first heating furnace (5), the second heating furnace (6) and the third heating furnace (7) respectively t 1 、t 2 、t 3 satisfies the following relationship: ， ； in, ρ 1 is the tap density of the discharged product, ρ 0 is the tap density of the initial material, β 1 is the specific surface area of ​​the discharged product, β 0 is the specific surface area of ​​the initial material, 250℃≤ T 1≤ T 2≤ T 3≤750℃, t 1 、t 2 、t 3 are all 20-180min, coefficient k 1=(0.8-3)×10 4 ℃·min, coefficient k 2 = (1.5 - 3.5) × 10 4 ℃·min, coefficient k 3 = (4.5 - 10) × 10 4 ℃·min, coefficient k 4 = (0.5 - 3) × 10 3 ℃·min, coefficient k 5=(3-9)×10 3 ℃·min; T 1 、T 2 、T 3 are 250-400℃, 300-500℃, 450-750℃ respectively, t 1 、t 2 、t 3 are 20-60min, 30-100min and 20-80min respectively.

2. The reaction device according to claim 1, characterized in that T 1 、T 2 、T 3 are 250-400℃, 400-450℃, 450-650℃ respectively, coefficient k 1=(0.8-1.1)×10 4 ℃·min, coefficient k 2 = (1.6 - 2.0) × 10 4 ℃·min, coefficient k 3 = (6.5 - 8.5) × 10 4 ℃·min, coefficient k 4 = (0.8 - 2) × 10 3 ℃·min, coefficient k 5=(4-8)×10 3 ℃·min.

3. The reaction device according to claim 2, characterized in that , ,and .

4. The reaction device according to any one of claims 1 to 3, characterized in that The first heating furnace (5) is heated by hot air, and the second heating furnace (6) and the third heating furnace (7) are heated by gas burner combustion.

5. The reaction device according to claim 4, characterized in that The hot air discharged from the first heating furnace (5) is sent to the inlet of the first combustion-supporting fan (16) of the second heating furnace (6) through the first induced draft fan (17) as combustion-supporting air for the second heating furnace (6).

6. The reaction device according to any one of claims 1 to 3, characterized in that The rotary reactor (4) is provided with a fourth heating furnace (8) on the outer wall of the cylinder at the carbonization section for providing heat to the carbonization section. The fourth heating furnace (8) is arranged close to the third heating furnace (7). The fourth heating furnace (8) is used to control the internal temperature of the heated section of the rotary reactor (4) to be between 600°C and 1150°C, and the internal temperature of the section of the rotary reactor (4) heated by the fourth heating furnace (8) is higher than the internal temperature of the section of the rotary reactor (4) heated by the third heating furnace (7).

7. The reaction device according to any one of claims 1 to 3, characterized in that A first cooling assembly (9) for preliminarily cooling the material after passing through the carbonization section is further provided on the outer wall of the cylinder of the rotary reactor (4). The first cooling assembly (9) is arranged close to the carbonization section and is used to cool the reaction material to below 200°C. A second cooling assembly (14) for further cooling the reaction material to below 60°C is further provided behind the first cooling assembly (9) along the material flow direction.

8. The reaction device according to any one of claims 1 to 3, characterized in that The carbonized flue gas discharged from the rotary reactor (4) is dedusted by a flue gas dust collector (24) and then enters a flue gas incinerator through a flue gas duct. The flue gas incinerator is provided with a hot gas outlet, which is connected to a heat exchanger and then to a hot air inlet of the first heating furnace (5) through a hot air furnace (15). The flue gas duct is provided with a heat preservation device for preventing the carbonized flue gas from condensing in the duct.

9. A continuous coating granulation-carbonization reaction process for battery graphite negative electrode materials using the reaction device according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1: starting the rotary reactor (4), turning on the first heating furnace (5), the second heating furnace (6), the third heating furnace (7) and the fourth heating furnace (8) of the carbonization section, so that different parts of the rotary reactor (4) reach a preset temperature; S2: feeding the mixed material of the negative electrode base material and the coating material into the rotary reactor (4) through a feeding system (1); S3: through the rotation and self-propelling of the rotary reactor (4), the incoming material passes through the coating and granulation section and the carbonization section of the rotary reactor (4) in sequence, and the residence time of the material in the coating and granulation section is controlled; S4: The material after cooling is sent out through a discharging system (23), thus completing the continuous coating granulation-carbonization reaction.

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