Sintering furnace and sintering method thereof

Abstract

The invention discloses a sintering furnace and a sintering method thereof.The sintering furnace sequentially comprises a feeding device, a furnace body and a discharging device from top to bottom, the furnace body comprises a plurality of sections, and the sections comprise a first sintering preheater, a second sintering preheater, a sintering thermostat, a sintering reactor, a sintering reaction separator and a nitrogen cooler; the nitrogen rotating pipeline is arranged in the furnace body, the nozzles are sequentially arranged on the nitrogen rotating pipeline, the nozzles of the nitrogen rotating pipeline and the butterfly valve of each section of the furnace body are jointly controlled in a fluidization mode or an atmosphere protection mode, the spiral turning and stirring effect on powder can be effectively formed, and the heating uniformity of the powder is improved.

Description

Technical Field

[0001] The present invention relates to the field of lithium battery material preparation, and in particular to a sintering furnace and a sintering method thereof. Background Art

[0002] With the rapid development of the electric vehicle industry, the production of lithium battery materials has also attracted much attention. At present, the sintering process in the production of lithium battery materials has the highest cost, so it has attracted the most attention. Taking lithium iron phosphate as an example, the sintering process mainly involves mixing raw material particles such as iron phosphate, lithium carbonate, and glucose, and then calcining them at high temperature. Common calcination equipment in the prior art includes horizontal kilns, rotary kilns, etc., but they all have problems such as large footprint, high investment, low efficiency, material adhesion, and difficulty in control.

[0003] Therefore, the prior art urgently needs a sintering equipment with small footprint, low investment, high efficiency and the ability to accurately control the sintering process. Summary of the invention

[0004] In order to solve one of the problems existing in the prior art, the present invention provides a sintering furnace, which comprises a feeding device, a furnace body and a discharging device from top to bottom, wherein the furnace body comprises a plurality of sections, and the sections are respectively a first sintering preheater, a second sintering preheater, a sintering thermostat, a sintering reactor, a sintering reaction precipitator, and a nitrogen cooler; in addition, the sintering furnace also comprises a nitrogen source and a nitrogen heater; The first sintering preheater, the second sintering preheater, the sintering thermostat, the sintering reactor, and the sintering reaction precipitator are all provided with an internal heater and an external heater; A nitrogen cyclone pipeline is arranged in the furnace body, the nitrogen cyclone pipeline is spiral-shaped, and nozzles arranged in sequence are arranged on the nitrogen cyclone pipeline; an air inlet is also arranged on the nitrogen cyclone pipeline; The nitrogen source is connected to the nitrogen cooler through a first pipeline, and the nitrogen enters the nitrogen cyclone pipeline through an air inlet on the nitrogen cyclone pipeline in the nitrogen cooler; the nitrogen source is connected to the nitrogen heater through a second pipeline, and the nitrogen is connected to the sintering reaction precipitator through a pipeline after being heated, and enters the nitrogen cyclone pipeline through an air inlet on the nitrogen cyclone pipeline in the sintering reaction precipitator; A furnace butterfly valve is provided at the bottom of each section; The discharging device comprises a first powder buffer bin, a second powder buffer bin and a spiral discharging device; a ball valve is arranged on the upper part of the first powder buffer bin, a first butterfly valve of the discharging device is arranged on the lower part of the first powder buffer bin, and a second butterfly valve of the discharging device is arranged on the lower part of the second powder buffer bin; the nitrogen source is also connected to the inner cavity of the discharging device through a third pipeline.

[0005] Furthermore, the nozzles in the nitrogen cyclone pipeline within one pitch are sequentially arranged as nozzle No. 1, nozzle No. 2, nozzle No. 3 and nozzle No. 4, the diameter of the lower nozzle of nozzle No. 1 is 2.5 times the diameter of the upper nozzle, the diameter of the lower nozzle of nozzle No. 2 is 2.2 times the diameter of the upper nozzle, the diameter of the lower nozzle of nozzle No. 3 is 1.5 times the diameter of the upper nozzle, and the diameter of the lower nozzle of nozzle No. 4 is 1.7 times the diameter of the upper nozzle.

[0006] Furthermore, the sintering furnace also includes a filtering and dust removal device, and the filtering and dust removal device is one or more. The gas generated in the furnace body is connected to the filtering and dust removal device through a pipeline, and the gas is discharged from the furnace body after filtering and dust removal.

[0007] Furthermore, a water cooling jacket is arranged outside the nitrogen cooler.

[0008] Furthermore, the feeding device includes a feeding device, a powder bin and a spiral feeding device.

[0009] Furthermore, each section of the furnace body is a hollow cylinder, and the cylinder includes an outer metal shell, the inner part of the outer metal shell is an inner shell, the outer part of the outer metal shell is provided with a heat insulation layer, and the heat insulation layer is provided with an observation window; Furthermore, the inner shell is a quartz tube or a silicon carbide tube.

[0010] Furthermore, the feeding device is provided with a feeding device filter, and the discharging device is provided with an exhaust filter.

[0011] Furthermore, a thermocouple and a pressure gauge are provided on the furnace body.

[0012] Furthermore, the nitrogen source is a nitrogen bottle or a nitrogen preparation device.

[0013] Furthermore, after being discharged from the furnace body, the nitrogen passes through a steam treatment device and then a carbon treatment device, and then returns to the furnace body for recycling.

[0014] Furthermore, the furnace body butterfly valve includes a motor, a valve body and a valve core. The motor S can drive the valve core to rotate. An inflation ring is arranged in the valve body. The inflation ring is in a circular shape in the valve body. A plurality of inflation holes are arranged at intervals on the inner wall of the valve body. A buffer chamber S is arranged between the inflation ring and the inflation hole. The buffer chamber S connects the inflation ring and the inflation hole. A gas inlet is arranged on the outer wall of the valve body. The nitrogen in the nitrogen source is connected to the gas inlet through a pipeline. The nitrogen enters the inflation ring and the buffer chamber in turn and enters the furnace body through the inflation hole. The angle between the direction of the inflation hole and the inner wall of the valve body is an acute angle.

[0015] The present invention also protects the sintering method of the sintering furnace as described above, wherein the nozzle of the nitrogen cyclone pipeline and the furnace body butterfly valve of each section are jointly controlled in the following manner: Streaming mode: S1: Close the discharging device; S2: Fully open the furnace butterfly valves of all sections; S3: The nozzles of the nitrogen cyclone pipeline are opened from bottom to top in sequence and maintained for a certain period of time to form a spiral stirring airflow for the particles in the furnace body; S4: After step S3 continues for a predetermined time, the discharge device returns to normal operation, and the furnace butterfly valves of all sections return to normal openings; Protective atmosphere mode: The nozzles of the nitrogen cyclone pipeline are all open; The pressure of the gas ejected from the nozzle of the nitrogen cyclone pipeline in the fluidized mode is P1, and the pressure of the gas ejected from the nozzle of the nitrogen cyclone pipeline in the protective atmosphere mode is P2, and P1 is greater than P2.

[0016] Furthermore, the sintering furnace is discharged according to the following steps: A1. Open the ball valve on the top of the first powder buffer bin; A2. The powder enters the first powder buffer bin. When the first powder buffer bin is full, close the ball valve on the top of the first powder buffer bin; A3. Open the first butterfly valve of the discharging device; A4. The powder enters the second powder buffer bin. When the second powder buffer bin is full, close the first butterfly valve of the discharge device; A5. Use nitrogen to replace the gas in the first powder buffer bin; A6. Open the second butterfly valve of the discharging device and open the spiral discharging device; A7. Close the second butterfly valve of the discharging device; A8. Use nitrogen to replace the gas in the second powder buffer bin; Each time the discharge is completed, steps S1 to S4 in the fluidization mode are performed once.

[0017] The device proposed in the present invention enhances the fluidization function of the material by arranging a nitrogen spiral loop, effectively controls the state of the material in the furnace body, and cooperates with the control method during the sintering process to make the powder present a fluidized state and a convection state, so that the material in each part can be heated evenly, while also avoiding the problem of powder residue during the advancement process. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] In order to more clearly illustrate the technical solutions in the specific implementation manner of the present invention, the drawings required for use in the specific implementation manner or the description of the prior art will be briefly introduced below.

[0019] Figure 1It is an overall schematic diagram of the sintering furnace disclosed in the embodiment of the first aspect of the present invention.

[0020] Figure 2 It is a cross-sectional schematic diagram of the sintering furnace disclosed in the embodiment of the first aspect of the present invention.

[0021] Figure 3 It is a cross-sectional schematic diagram of a certain section of the furnace body of the sintering furnace disclosed in the embodiment of the first aspect of the present invention.

[0022] Figure 4 It is a schematic diagram of a feeding device of a sintering furnace disclosed in an embodiment of the first aspect of the present invention.

[0023] Figure 5 It is a schematic diagram of a discharge device of a sintering furnace disclosed in an embodiment of the first aspect of the present invention.

[0024] Figure 6 It is a schematic diagram of a nitrogen cyclone pipeline of a sintering furnace disclosed in an embodiment of the first aspect of the present invention.

[0025] Figure 7 It is a schematic diagram of a filter screen at the connection between a certain section of the furnace body of the sintering furnace disclosed in the embodiment of the first aspect of the present invention and a filtering and dust removal device.

[0026] Figure 8 It is a schematic diagram of the connection between the nitrogen source and the furnace body of the sintering furnace and the subsequent processing equipment disclosed in the embodiment of the first aspect of the present invention.

[0027] Fig. 9 This is a schematic diagram of nozzle No. 1 on the nitrogen cyclone device.

[0028] Fig.10 This is a schematic diagram of the No. 2 nozzle on the nitrogen cyclone device.

[0029] Fig.11 This is a schematic diagram of the No. 3 nozzle on the nitrogen cyclone device.

[0030] Fig.12 This is a schematic diagram of nozzle No. 4 on the nitrogen cyclone device.

[0031] Fig.13 It is the movement trajectory of powder particles in the furnace body of the sintering furnace in the fluidized mode in the embodiment of the first aspect of the present invention.

[0032] Fig.14 It is the pressure distribution at various locations on the cross section of the furnace body of the sintering furnace in the embodiment of the first aspect of the present invention.

[0033] Fig.15 It is a three-dimensional schematic diagram of the velocity distribution of powder in the furnace body of the sintering furnace in the embodiment of the first aspect of the present invention.

[0034] Fig.16It is the distribution of powder velocity at various locations on the cross section of the furnace body of the sintering furnace in the embodiment of the first aspect of the present invention.

[0035] Fig.17 It is a three-dimensional diagram of the furnace butterfly valve.

[0036] Fig.18 It is a cross-sectional diagram of the furnace butterfly valve.

[0037] Fig.19 yes Fig.18 Schematic diagram of AA section (without valve core).

[0038] Fig. 20 yes Fig.18 AA section diagram of (with valve core).

[0039] Fig.21 yes Fig.18 Schematic diagram of BB section (rotated 90° to the right, the outline of the valve core is shown by dotted line).

[0040] 1 feeding device, 2 discharging device, 3 first sintering preheater, 4 sintering thermostat, 5 sintering reactor, 6 sintering reaction precipitator, 7 nitrogen cooler, 8 second sintering preheater, 9 first filtering dust removal device, 10 external metal shell, 11 internal shell, 12 insulation layer, 13 feeding device filter, 14 feeding device powder bin, 15 spiral feeding device, 16 feeding device butterfly valve, 17 second filtering dust removal device, 18 third filtering dust removal device, 19 fourth filtering dust removal device, 20 nitrogen cyclone pipeline, 21 air inlet, 22 nozzle, 22a- Nozzle No. 1, 22b No. 2 nozzle, 22c No. 3 nozzle, 22d No. 4 nozzle, 23 nitrogen source, 24 nitrogen heater, 25 steam treatment device, 26 carbon treatment device, 27 fifth filtering and dust removal device, 28 sixth filtering and dust removal device, 29 internal heater, 30 external heater, 31 filter, 33 pressure gauge, 34 thermocouple, 35 furnace body butterfly valve, 36 observation window, 37 first powder buffer bin, 38 second powder buffer bin, 39 spiral discharging device, 40 exhaust filter, 41 first butterfly valve of discharging device, 42 second butterfly valve of discharging device, 43 motor, 44 valve body, 45 valve core, 46 inflation ring, 47 buffer chamber, 48 inflation hole, 49 gas inlet. DETAILED DESCRIPTION

[0041] The structure and operation of the present invention will be further described in detail below in conjunction with the accompanying drawings. Obviously, the accompanying drawings are provided only for a better understanding of the present invention and should not be construed as limiting the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] In the description of the present invention, it should be noted that, if the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. appear, the orientation or position relationship indicated is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, if the terms "first" and "second" appear, they are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0043] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected" and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a direct connection, or an indirect connection through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. Example 1

[0044] Combination Figures 1 to 21 As shown, this embodiment discloses a sintering furnace, which includes a feeding device 1, a furnace body and a discharging device 2 from top to bottom, wherein the furnace body includes several sections, and the sections are respectively a first sintering preheater 3, a second sintering preheater 8, a sintering thermostat 4, a sintering reactor 5, a sintering reaction precipitator 6, and a nitrogen cooler 7; in addition, the sintering furnace also includes a nitrogen source 23 and a nitrogen heater 24.

[0045] The working process of the device disclosed in the present invention is as follows: the material to be sintered enters the furnace body through the feeding device 1, and then passes through the first sintering preheater 3, the second sintering preheater 8, the sintering thermostat 4, the sintering reactor 5, and the sintering reaction precipitator 6 for staged heating and completes the preparation of the positive or negative electrode material of the lithium-ion battery, and then is discharged from the discharging device 2. The first sintering preheater 3 heats the material from 0°C to 150°C to remove the crystal water of glucose, and the second sintering preheater 8 further heats the material from 150°C to 300°C to decompose the glucose into carbon and water. Subsequently, the sintering is carried out in the sintering thermostat, the sintering reactor and the sintering reaction precipitator. The temperature and reaction degree in the sintering thermostat, sintering reactor and sintering reaction precipitator are different. The nitrogen cooler 7 at the bottom reduces the temperature of the material from 780°C to 60°C, and the material after cooling can be discharged.

[0046] The reaction process is carried out under the protection of nitrogen. The running direction of nitrogen is opposite to that of the material. Nitrogen enters from the bottom, then moves upward, and is discharged from the top or the filtering dust removal device connected to the furnace body.

[0047] The first sintering preheater 3, the second sintering preheater 8, the sintering thermostat 4, the sintering reactor 5, and the sintering reaction precipitator 6 are all provided with an internal heater 29 and an external heater 30; depending on the reaction materials, the internal heater 29 and the external heater 30 can be used alone or in combination, and the temperature of different sections in the furnace body can be accurately controlled. In some embodiments, if the reaction material is not sensitive to temperature, only nitrogen can be used to heat the material, and there is no need to activate the internal heater 29 and the external heater 30. The internal heater 29 is a heating rod or heater arranged on the inner wall of each section, and multiple heaters can be arranged as needed.

[0048] The problems of uneven distribution and adhesion of powder in the sintering furnace of positive and negative electrode materials of lithium-ion batteries have always been a problem that has attracted much attention. In the prior art, a spiral stirring device is usually used to stir the powder in the furnace body, or blowing holes are set on the outer wall of the furnace to disturb the powder with gas. However, both methods have major problems. For example, the stirring blades of the spiral stirring device are easily stuck by the powder, and the blowing holes on the outer wall can only blow the powder close to the furnace wall 5, resulting in poor fluidization effect.

[0049] To this end, the present invention provides a nitrogen cyclone pipeline 20 in the furnace body. The nitrogen cyclone pipeline 20 is spiral-shaped and is provided with nozzles 22 arranged in sequence. The nitrogen cyclone pipeline 20 is also provided with an air inlet 21 .

[0050] Combination Figure 2 and Figure 8 As shown, the nitrogen source 23 is connected to the nitrogen cooler 7 at the lower part of the furnace body through the first pipeline, and the nitrogen enters the nitrogen cyclone pipeline 20 through the air inlet 21 on the nitrogen cyclone pipeline 20 in the nitrogen cooler 7; the nitrogen source 23 is connected to the nitrogen heater 24 through the second pipeline, and the nitrogen is connected to the sintering reaction precipitator 6 through the pipeline after heating, and enters the nitrogen cyclone pipeline 20 through the air inlet 21 on the nitrogen cyclone pipeline 20 in the sintering reaction precipitator 6. In the optimized embodiment, the nitrogen discharged from the furnace body first passes through the steam treatment device 25 to remove the water vapor therein, and then passes through the carbon treatment device 26 to remove the carbon monoxide and carbon dioxide therein, and then can be recycled to reduce the pollution to the atmosphere.

[0051] A furnace butterfly valve 35 is provided at the lower part of each section; The nozzle of the nitrogen cyclone pipeline and the furnace butterfly valve 35 of each section are jointly controlled in the following manner: Streaming mode: S1: Close the discharging device 2; S2: Fully open the furnace butterfly valves 35 of all sections; S3: The nozzles 22 of the nitrogen cyclone pipeline 20 are opened from bottom to top in sequence and maintained for a certain period of time to form a spiral stirring airflow for the particles in the furnace body; S4: After step S3 continues for a predetermined time, the discharge device 2 returns to normal operation, and the furnace body butterfly valves 35 of all sections return to normal openings; Protective atmosphere mode: the nozzles 22 of the nitrogen cyclone 20 are all open; Among them, the gas pressure sprayed out of the nozzle 22 of the nitrogen cyclone pipeline 20 in the fluidized mode is P1, and the gas pressure sprayed out of the nozzle 22 of the nitrogen cyclone pipeline 20 in the protective atmosphere mode is P2. P1 is greater than P2. In the optimized embodiment, P1 is more than three times of P2.

[0052] In an optimized embodiment, Figures 9 to 12 As shown, the nozzles of the nitrogen cyclone 20 within one pitch are arranged in sequence as No. 1 nozzle 22a, No. 2 nozzle 22b, No. 3 nozzle 22c, and No. 4 nozzle 22d. The diameter of the lower nozzle of No. 1 nozzle 22a is 2.5 times the diameter of the upper nozzle, the diameter of the lower nozzle of No. 2 nozzle 22b is 2.2 times the diameter of the upper nozzle, the diameter of the lower nozzle of No. 3 nozzle 22c is 1.5 times the diameter of the upper nozzle, and the diameter of the lower nozzle of No. 4 nozzle 22d is 1.7 times the diameter of the upper nozzle. Such nozzle caliber design is the most favorable setting mode for fluidization effect found after many experiments. Figures 13 to 16 As shown, Fig.13 is the movement trajectory of powder particles in the furnace under fluidized mode, Fig.14 The pressure distribution at various locations on the furnace section is shown. Fig.15 A three-dimensional schematic diagram showing the velocity distribution of the powder in the furnace. Fig.16 The distribution of powder velocity at various locations on the furnace section is shown. It can be seen that the flow velocity of the powder is evenly distributed at various locations, so that the powder is heated evenly, which is conducive to improving the quality of lithium battery material products.

[0053] The nitrogen cyclone pipeline solves the problems in the prior art very well. The nitrogen cyclone pipeline spirals up in the furnace, comes into direct contact with the powder, and passes through the powder evenly. Therefore, when the spiral airflow blows through the powder in turn, a very uniform stirring effect can be formed. This gas disturbance method has no mechanical moving parts, so there will be no problem of the blade being stuck.

[0054] When the fluidization mode is not in progress, the butterfly valves of each section of the furnace body can be set to different openings, so that the overall downward flow rate of the powder can be controlled. When the fluidization mode is in progress, the discharge device at the bottom is first closed, and then the butterfly valves of each section are fully opened, which can provide enough space for the nitrogen cyclone pipeline to stir and reduce the resistance of stirring. When all sections in the furnace body form a cavity connected up and down, spiral stirring will achieve a good stirring effect. When the fluidization mode ends, the butterfly valves of each section can return to the original opening state and continue to control the flow rate of the powder.

[0055] The specific structure of the butterfly valve in the present invention is specially designed. Since the temperature in the furnace of the present invention reaches 800°C, the sealing ring around the conventional butterfly valve is easy to fail and deform at high temperature, resulting in a decrease in the sealing performance of the butterfly valve. Therefore, the present invention adopts a new sealing structure.

[0056] Combination Figure 17-Figure 21 As shown, Fig.17 It is a three-dimensional diagram of the furnace butterfly valve. Fig.18 It is a cross-sectional diagram of the furnace butterfly valve. Fig.19 yes Fig.18 AA cross-sectional schematic diagram, in which the valve core is omitted. Fig. 20 yes Fig.15 AA cross-sectional schematic diagram, the valve core is shown. Fig.21 yes Fig.18 The BB cross-sectional diagram of FIG. 1 is rotated 90° to the right, in which the valve core is represented by a dotted line as its outline, and the valve body at the rear can be seen through the valve core.

[0057] The furnace body butterfly valve 35 includes a motor 43, a valve body 44 and a valve core 45, and the motor 43 can drive the valve core 45 to rotate. The sealing structure adopted by the present invention is as follows: an air-filling ring 46 is arranged in the valve body 44, and the air-filling ring 46 is in a circular ring shape in the valve body 44. A plurality of air-filling holes 48 are arranged at intervals on the inner wall of the valve body 44, and a buffer chamber 47 is arranged between the air-filling ring 46 and the air-filling hole 48, and the buffer chamber 47 communicates with the air-filling ring 46 and the air-filling hole 48. A gas inlet 49 is arranged on the outer wall of the valve body 44, and the nitrogen in the nitrogen source is communicated with the gas inlet 49 through a pipeline, and the nitrogen enters the air-filling ring 46 and the buffer chamber 47 in sequence and enters the furnace body through the air-filling hole 48, and the angle between the direction of the air-filling hole 48 and the inner wall of the valve body 44 is an acute angle. When the inflation hole is facing the direction of the material, nitrogen is blown toward the material, so that the material cannot pass through the gap between the valve core and the inner wall of the valve body, which greatly improves the sealing performance of the butterfly valve.

[0058] In addition to providing a stirring effect, the nitrogen cyclone can also provide a protective atmosphere, allowing the powder to react in an air-isolated state. The pressures required for nitrogen in these two modes are different. The gas pressure required for nitrogen stirring needs to be significantly higher than that in the atmosphere protection mode, and in the optimal embodiment, it is preferably more than 3 times. In the fluidized mode, since the valves on the nozzle are opened sequentially, the time for each nozzle to be opened can be set, such as opening them for 3 seconds or 5 seconds in sequence, and the time interval between the opening of two valves can also be set, such as opening a valve every 1 second. Therefore, the result is that only a part of the valves are opened at the same time, so the gas pressure ejected by the opened valve can be higher than the pressure in the atmosphere protection mode. The purpose of increasing the nozzle pressure can also be achieved by adjusting the gas delivery pressure of the pressure source.

[0059] In other embodiments, if the material is not sensitive to temperature, the nitrogen cyclone may not be provided.

[0060] In other embodiments, depending on the characteristics of the powder, except for the valves at the top and bottom of the furnace body, other valves may not be provided.

[0061] In the optimized embodiment, the discharging device includes a first powder buffer bin 37, a second powder buffer bin 38 and a spiral discharging device 39; a ball valve (not shown in the figure) is arranged on the upper part of the first powder buffer bin 37, a first butterfly valve 41 of the discharging device is arranged on the lower part of the first powder buffer bin 37, and a second butterfly valve 42 of the discharging device is arranged on the lower part of the second powder buffer bin 38. Before discharging, the ball valve on the upper part of the first powder buffer bin 37, the first butterfly valve 41 of the discharging device and the second butterfly valve 42 of the discharging device are all closed, and the discharging is carried out according to the following steps: A1. Open the ball valve on the top of the first powder buffer bin 37; A2. The powder enters the first powder buffer bin 37. When the first powder buffer bin 37 is full, the ball valve on the top of the first powder buffer bin 37 is closed; A3. Open the first butterfly valve 41 of the discharging device; A4. The powder enters the second powder buffer bin 38. When the second powder buffer bin 38 is full, the first butterfly valve 41 of the discharge device is closed; A5. Use nitrogen to replace the gas in the first powder buffer bin 37; A6. Open the second butterfly valve 42 of the discharging device and open the spiral discharging device 39; A7. Close the second butterfly valve 42 of the discharging device; A8. Use nitrogen to replace the gas in the second powder buffer bin 38; Each time the discharge is completed, steps S1 to S4 in the fluidization mode are performed once.

[0062] The purpose of such a setting is to isolate the material from the outside air when discharging, effectively improve the sealing of the vertical pipe furnace, and ensure that the material is always carried out under the protective atmosphere of nitrogen. After each discharging, the fluidization mode can be carried out so that the material is more uniform before discharging. It is understandable that the fluidization mode can also be set according to other time periods, such as regularly, or when local uneven distribution and particle adhesion are found.

[0063] Specifically, the sintering furnace further includes a filtering dust removal device, which is one or more filtering dust removal devices. The gas generated in the furnace body is connected to the filtering dust removal device through a pipeline, and the gas is discharged after filtering and dust removal. In a specific embodiment, a filtering dust removal device can be configured for each section in the furnace body, for example Figure 2 The first filter dust removal device 9, the second filter dust removal device 17, the third filter dust removal device 18, the fourth filter dust removal device 19, the fifth filter dust removal device 27 and the sixth filter dust removal device 28 are shown to discharge the waste gas generated after the reaction. Figure 7 As shown, a filter screen 31 can be provided at the place where the filtering dust removal device is connected to the furnace body to prevent powder from leaking from the connection. In an optimized embodiment, the nitrogen exhausted from the furnace body first passes through the steam treatment device 25 to remove the water vapor therein, and then passes through the carbon treatment device 26 to remove the carbon monoxide and carbon dioxide therein, and then can be recycled to reduce pollution to the atmosphere.

[0064] Specifically, a water cooling jacket is provided outside the nitrogen cooler, and the water cooling jacket can assist the nitrogen in cooling the powder.

[0065] Specifically, the feeding device 1 includes a feeding device powder bin 14 and a spiral feeding device 15. The feeding device can be provided with a valve, or a two-stage powder bin similar to the discharging device, so as to play a sealing role during feeding.

[0066] Specifically, each section of the furnace body is a hollow cylinder, and the cylinder includes an outer metal shell 10, an inner shell 11 is inside the outer metal shell 10, and a heat insulation layer 12 is arranged outside the outer metal shell 10, and an observation window 36 is arranged on the heat insulation layer; Specifically, the inner shell is a quartz tube or a silicon carbide tube.

[0067] Specifically, the feeding device 1 and the discharging device 2 are both provided with filters. The feeding device 1 is provided with a feeding device filter 13 , and the discharging device 2 is provided with an exhaust filter 40 .

[0068] Specifically, the furnace body is provided with a thermocouple 34 and a pressure gauge 33. The thermocouple 34 and the pressure gauge 33 measure the temperature and pressure in the furnace body and provide the information to the control system.

[0069] Specifically, the nitrogen source is a nitrogen bottle or a nitrogen preparation device.

[0070] The working pressure in the furnace body of the sintering furnace is 0-2MPa.

[0071] The spiral discharging device 39 provided in the discharging device 2 can perform accurate control of the discharging.

[0072] The present invention can achieve the following technical effects: Nitrogen has a design of "intake at the bottom and exhaust at the top". It enters the nitrogen cooling section to cool the reacted materials and complete the cooling process. The heat exchanged nitrogen rises, which is equivalent to preheating the nitrogen and heating the materials in the reaction section, which has energy-saving function. The materials pass through the reaction section and various reactions in the preheating section. The overflowed mixed gas is filtered by the filter dust removal device, and then treated to remove water vapor, carbon monoxide and carbon dioxide, and returned to the furnace body for recycling, which meets environmental protection requirements and makes full use of energy. From the input of raw materials to the output of products, stainless steel seamless steel pipes are used, lined with quartz tubes (or silicon carbide) for power transmission, which avoids the introduction of metal impurities such as copper, zinc, and iron. The design of the vertical sintering furnace realizes large-scale industrial production of products and greatly improves the quality of products.

[0073] The nitrogen spiral loop has a fluidizing function for the material, which effectively controls the state of the material in the furnace, presenting a fluidized convection state. During the reaction process, the material in each part is heated evenly, and the problem of powder residue during the propulsion process is also avoided.

[0074] Example 2 This embodiment discloses a sintering method according to the sintering furnace of Embodiment 1, wherein the nozzle 22 of the nitrogen cyclone pipeline 20 and the furnace body butterfly valve 35 of each section are jointly controlled in the following manner: Streaming mode: S1: Close the discharging device 2; S2: Fully open the furnace butterfly valves 35 of all sections; S3: The nozzles 22 of the nitrogen cyclone pipeline 20 are opened from bottom to top in sequence and maintained for a certain period of time to form a spiral stirring airflow for the particles in the furnace body; S4: After step S3 continues for a predetermined time, the discharge device 2 returns to normal operation, and the furnace body butterfly valves 35 of all sections return to normal openings; Protective atmosphere mode: the nozzles 22 of the nitrogen cyclone 20 are all open; The pressure of the gas ejected from the nozzle 22 of the nitrogen cyclone pipeline 20 in the fluidized mode is P1, and the pressure of the gas ejected from the nozzle 22 of the nitrogen cyclone pipeline 20 in the protective atmosphere mode is P2, and P1 is greater than P2.

[0075] Specifically, the sintering furnace also includes a discharging process, and the discharging process is performed according to the following steps: A1. Open the ball valve on the top of the first powder buffer bin 37; A2. The powder enters the first powder buffer bin 37. When the first powder buffer bin 37 is full, the ball valve on the top of the first powder buffer bin 37 is closed; A3. Open the first butterfly valve 41 of the discharging device; A4. The powder enters the second powder buffer bin 38. When the second powder buffer bin 38 is full, the first butterfly valve 41 of the discharge device is closed; A5. Use nitrogen to replace the gas in the first powder buffer bin 37; A6. Open the second butterfly valve 42 of the discharging device and open the spiral discharging device 39; A7. Close the second butterfly valve 42 of the discharging device; A8. Use nitrogen to replace the gas in the second powder buffer bin 38; Each time the discharge is completed, steps S1 to S4 in the fluidization mode are performed once.

[0076] The device provided by the present invention can realize precise control of material heating and pressure, and the reaction is sufficient. The reaction rate is better than the traditional method. The battery performance is tested and is 10% higher. The sintering material filling rate is high, reaching 95%, which saves 80% energy compared with horizontal furnaces and rotary furnaces. The investment is small. Calculated based on a 12,500-ton production line, a horizontal kiln requires an investment of 60-80 million yuan, a length of 68-108 meters, and an area of ​​300 square meters. A rotary furnace requires an investment of 15-20 million yuan, a length of 18-22 meters, and an area of ​​60 square meters. The sintering furnace of the present invention only requires an investment of 1.5 million yuan, is arranged vertically, occupies a high space, and covers an area of ​​9 square meters.

[0077] The above embodiments are only used to illustrate the present invention, wherein the structure, connection method and manufacturing process of each component may be changed. Any equivalent transformations and improvements based on this technical solution should not be excluded from the protection scope of the present invention.

Claims

1. A sintering furnace, characterized in that: The sintering furnace comprises, from top to bottom, a feeding device (1), a furnace body and a discharging device (2), wherein the furnace body comprises a plurality of sections, the sections being respectively a first sintering preheater (3), a second sintering preheater (8), a sintering thermostat (4), a sintering reactor (5), a sintering reaction precipitator (6), and a nitrogen cooler (7); in addition, the sintering furnace also comprises a nitrogen source (23) and a nitrogen heater (24); The first sintering preheater (3), the second sintering preheater (8), the sintering thermostat (4), the sintering reactor (5), and the sintering reaction precipitator (6) are all provided with an internal heater (29) and an external heater (30); A nitrogen cyclone pipeline (20) is arranged in the furnace body, the nitrogen cyclone pipeline (20) is spiral-shaped, and nozzles (22) arranged in sequence are arranged on the nitrogen cyclone pipeline (20); an air inlet (21) is also arranged on the nitrogen cyclone pipeline (20); The nitrogen source (23) is connected to the nitrogen cooler (7) through a first pipeline, and the nitrogen enters the nitrogen cyclone pipeline (20) through an air inlet (21) on the nitrogen cyclone pipeline (20) in the nitrogen cooler (7); the nitrogen source (23) is connected to the nitrogen heater (24) through a second pipeline, and the nitrogen is connected to the sintering reaction precipitator (6) through a pipeline after being heated, and enters the nitrogen cyclone pipeline (20) through an air inlet (21) on the nitrogen cyclone pipeline (20) in the sintering reaction precipitator (6); A furnace butterfly valve 35 is provided at the lower part of each section; The discharge device (2) comprises a first powder buffer bin (37), a second powder buffer bin (38) and a spiral discharge device (39); a ball valve is arranged at the top of the first powder buffer bin (37), a first butterfly valve (41) of the discharge device is arranged at the bottom of the first powder buffer bin (37), and a second butterfly valve (42) of the discharge device is arranged at the bottom of the second powder buffer bin (38); the nitrogen source (23) is also connected to the inner cavity of the discharge device (2) via a third pipeline.

2. The sintering furnace according to claim 1, characterized in that: The nozzles of the nitrogen cyclone pipeline (20) within one pitch are sequentially arranged as a No. 1 nozzle (22a), a No. 2 nozzle (22b), a No. 3 nozzle (22c), and a No. 4 nozzle (22d); the diameter of the lower nozzle of the No. 1 nozzle (22a) is 2.5 times the diameter of the upper nozzle, the diameter of the lower nozzle of the No. 2 nozzle (22b) is 2.2 times the diameter of the upper nozzle, the diameter of the lower nozzle of the No. 3 nozzle (22c) is 1.5 times the diameter of the upper nozzle, and the diameter of the lower nozzle of the No. 4 nozzle (22d) is 1.7 times the diameter of the upper nozzle.

3. The sintering furnace according to claim 1, characterized in that: The sintering furnace also includes a filtering and dust removal device, which is one or more filtering and dust removal devices. The gas generated in the furnace body is connected to the filtering and dust removal device through a pipeline, and the gas is discharged from the furnace body after filtering and dust removal.

4. The sintering furnace according to claim 1, characterized in that: A water cooling jacket is arranged outside the nitrogen cooler (7).

5. The sintering furnace according to claim 1, characterized in that: The feeding device (1) comprises a feeding device powder bin (14) and a screw feeding device (15).

6. The sintering furnace according to claim 1, characterized in that: Each section of the furnace body is a hollow cylinder, wherein the cylinder comprises an outer metal shell (10), wherein the interior of the outer metal shell (10) is an inner shell (11), and a heat insulation layer (12) is arranged outside the outer metal shell (10), and an observation window (36) is arranged on the heat insulation layer (12).

7. The sintering furnace according to claim 1, characterized in that: The inner shell (11) is a quartz tube or a silicon carbide tube.

8. The sintering furnace according to claim 1, characterized in that: The feeding device (1) is provided with a feeding device filter (13), and the discharging device (2) is provided with an exhaust filter (40).

9. The sintering furnace according to claim 1, characterized in that: The furnace body is provided with a thermocouple (34) and a pressure gauge (33).

10. The sintering furnace according to claim 1, characterized in that: The nitrogen source (23) is a nitrogen bottle or a nitrogen preparation device.

11. The sintering furnace according to claim 3, characterized in that: After being discharged from the furnace body, the nitrogen first passes through the steam treatment device (25) and then passes through the carbon treatment device (26), and then returns to the furnace body for recycling.

12. The sintering furnace according to claim 1, characterized in that: The furnace body butterfly valve (35) comprises a motor (43), a valve body (44) and a valve core (45). The motor (43) can drive the valve core (45) to rotate. An air filling ring (46) is arranged in the valve body (44). The air filling ring (46) is in a circular ring shape in the valve body (44). A plurality of air filling holes (48) are arranged at intervals on the inner wall of the valve body (44). A buffer chamber (47) is arranged between the air filling ring (46) and the air filling hole (48). The buffer chamber (47) is connected to the inflation ring (46) and the inflation hole (48); a gas inlet (49) is provided on the outer wall of the valve body (44); nitrogen in the nitrogen source (23) is connected to the gas inlet (49) through a pipeline; the nitrogen enters the inflation ring (46), the buffer chamber (47) in sequence, and enters the interior of the furnace through the inflation hole (48); the included angle between the direction of the inflation hole (48) and the inner wall of the valve body (44) is an acute angle.

13. A sintering method using a sintering furnace according to any one of claims 1 to 12, characterized in that: The nozzle (22) of the nitrogen cyclone pipeline (20) and the furnace butterfly valve (35) of each section are jointly controlled in the following manner: Streaming mode: S1: Close the discharging device (2); S2: Fully open the furnace butterfly valves (35) of all sections; S3: the nozzles (22) of the nitrogen cyclone pipeline (20) are opened in sequence from bottom to top and maintained for a certain period of time to form a spiral stirring airflow for the particles in the furnace body; S4: After step S3 continues for a predetermined time, the discharge device (2) returns to normal operation, and the furnace body butterfly valves (35) of all sections return to normal openings; Protective atmosphere mode: the nozzles (22) of the nitrogen cyclone (20) are all open; The pressure of the gas ejected from the nozzle (22) of the nitrogen cyclone pipeline (20) in the fluidized mode is P1, and the pressure of the gas ejected from the nozzle (22) of the nitrogen cyclone pipeline (20) in the protective atmosphere mode is P2, and P1 is greater than P2.

14. The sintering method of the sintering furnace according to claim 13, characterized in that: The sintering furnace also includes a discharging process, and the discharging process is performed according to the following steps: A1. Open the ball valve on the top of the first powder buffer bin (37); A2. The powder enters the first powder buffer bin (37). When the first powder buffer bin (37) is full, the ball valve at the top of the first powder buffer bin (37) is closed; A3. Open the first butterfly valve (41) of the discharging device; A4. The powder enters the second powder buffer bin (38). When the second powder buffer bin (38) is full, the first butterfly valve (41) of the discharge device is closed. A5. Using nitrogen to replace the gas in the first powder buffer bin (37); A6. Open the second butterfly valve (42) of the discharging device and open the spiral discharging device (39); A7. Close the second butterfly valve (42) of the discharging device; A8. Using nitrogen to replace the gas in the second powder buffer bin (38); Each time the discharge is completed, steps S1 to S4 in the fluidization mode are performed once.

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