Continuous calcining device for producing lithium iron phosphate

Abstract

The utility model relates to the technical field of battery material synthesis devices, in particular to a continuous calcining device for producing lithium iron phosphate. According to the technical scheme, the device comprises a low-temperature furnace feeding bin, a low-temperature calcining furnace, a buffer stock bin, a high-temperature calcining rotary furnace and a multi-stage material cooling device which are communicated through pipelines; the low-temperature calcining furnace, the high-temperature calcining furnace and the multi-stage material cooling device are respectively provided with a material inlet and a material outlet, the material outlet of the low-temperature calcining furnace is connected with the material inlet of the low-temperature calcining furnace, and the material outlet of the low-temperature calcining furnace is connected with the material inlet of the high-temperature calcining rotary furnace through a pipeline; the pipeline is sequentially provided with a buffer bin and a material conveyor in series, and a material outlet of the high-temperature calcining rotary furnace is connected with a material inlet of the multi-stage material cooling device. The multi-stage fishbone-shaped material shoveling plates are arranged in the low-temperature calcining furnace, and the spiral shoveling plates are arranged in the high-temperature calcining furnace, so that the mixing uniformity of sintered materials in the low-temperature calcining furnace is improved, and the phenomenon of back mixing of the materials can be effectively avoided.

Description

Technical Field

[0001] The utility model relates to the technical field of battery material synthesis devices, in particular to a continuous calcining device for producing lithium iron phosphate. Background Art

[0002] As a carrier of new energy, lithium-ion batteries have been successfully industrialized and applied to many fields such as new energy vehicles, electronic products, energy storage equipment, etc. They are more energy-saving and environmentally friendly than traditional energy. At present, lithium-ion batteries are mainly divided into three categories: ternary, lithium iron phosphate and lithium cobalt oxide batteries. Among them, lithium iron phosphate batteries have better thermal stability and safety, and the cost of raw materials is lower, making them the most widely used lithium-ion batteries on the market. The industrial production methods of lithium iron phosphate batteries mainly include solid-phase method and hydrothermal synthesis method. The actual industrial production is mainly based on high-temperature solid-phase method, which is specifically prepared by mixing, grinding, spraying, coating, high-temperature sintering and other processes of a certain proportion of lithium source, phosphorus source, iron source and organic carbon source and other related doping additives.

[0003] The process of synthesizing lithium iron phosphate materials by high-temperature solid-phase sintering or calcination is generally completed in a roasting furnace. Compared with the static high-temperature roasting method, the dynamic roasting rotary kiln (kiln) can overcome the defects of under-burning, undercooked or over-burning of powder materials during the sintering process, and improve the roasting uniformity and product quality of the product. However, in actual production, the existing lithium battery positive electrode material lithium iron phosphate roasting equipment still has problems such as uneven heat transfer, poor thermal stability, and high energy consumption. At the same time, the existing high-temperature solid-phase sintering production equipment is mostly carried out in the same rotary kiln (kiln), which is prone to "re-mixing" of materials, affecting the quality and application performance of the fired products. Utility Model Content

[0004] In view of the technical problems existing in the prior art, the utility model provides a continuous calcination device for producing lithium iron phosphate.

[0005] In order to achieve the above purpose, the utility model adopts the following technical solutions:

[0006] A continuous calcination device for producing lithium iron phosphate, characterized in that it comprises a low-temperature furnace feed bin, a low-temperature calcining furnace, a buffer bin, a high-temperature calcining rotary furnace and a multi-stage material cooling device, and the various components are connected by pipelines; the low-temperature calcining furnace, the high-temperature calcining furnace and the multi-stage material cooling device are respectively provided with a material inlet and a material outlet, the material outlet of the low-temperature furnace feed bin is connected to the material inlet of the low-temperature calcining furnace, the material outlet of the low-temperature calcining furnace is connected to the material inlet of the high-temperature calcining rotary furnace through a pipeline, the pipeline is sequentially provided with a buffer bin and a material transmitter in series, and a connection is established between the material outlet of the high-temperature calcining rotary furnace and the material inlet of the multi-stage material cooling device.

[0007] According to the continuous calcination device for producing lithium iron phosphate, the low-temperature calcination furnace and the high-temperature calcination furnace are respectively provided with a protective shell, a heat-insulating lining, an electric heating layer, a mixing reaction chamber and a mixing reaction chamber body from the outside to the inside.

[0008] According to the continuous calcination device for producing lithium iron phosphate, the electric heating layer and the mixing reaction chamber shell are distributed in a parallel and circumferential manner.

[0009] According to the continuous calcination device for producing lithium iron phosphate, the inner wall of the mixing reaction chamber of the low-temperature calcination furnace is sequentially provided with multi-stage material copying plates, and the inner wall of the mixing reaction chamber of the high-temperature calcination furnace is provided with a spiral copying plate, and the material of the copying plate can be selected from any one of heat-resistant alloy and silicon carbide.

[0010] According to the continuous calcination device for producing lithium iron phosphate, each level of the material copying plate arranged in the low-temperature calcination furnace is in a "fishbone" shape, consisting of a main copying plate and n levels of alternate auxiliary copying plates, wherein 3≤n≤8.

[0011] According to the continuous calcination device for producing lithium iron phosphate, the bottom end of the main copying plate is parallel to the inner wall of the mixing reaction chamber and is seamlessly welded thereto, and the top end is in a broken line shape with a bending angle of 90°<α≤120° and is discontinuously connected with the top ends of other levels of main copying plates to form a material flow chamber; the n levels of alternate auxiliary copying plates are parallel to each other, each level of auxiliary copying plates is of different lengths, and both ends thereof are seamlessly welded to the main copying plate and the reaction wall respectively.

[0012] According to the continuous calcination device for producing lithium iron phosphate, the high-temperature calcination furnace and the low-temperature calcination furnace are respectively provided with calcination zones from low to high temperature in the mixing reaction chamber according to the material travel direction, and different calcination zones are provided with temperature wireless sensors.

[0013] According to the continuous calcination device for producing lithium iron phosphate, the heating layers of different calcination zones are provided with temperature control switches, and a PLC automatic interlock is built between the temperature control switches and the temperature wireless sensors provided in the corresponding calcination zones.

[0014] According to the continuous calcination device for producing lithium iron phosphate, a nitrogen channel is also provided, the nitrogen channel inlet is arranged at the discharge end of the high-temperature calcining furnace, and the nitrogen channel outlet is arranged at the feed end of the low-temperature calcining furnace. Nitrogen enters through the nitrogen channel inlet at the discharge end of the high-temperature calcining furnace, passes through the material conveyor, the buffer silo, the material transfer pipeline, and the reaction mixing chamber of the low-temperature calcining furnace in sequence, and is discharged through the nitrogen channel outlet. Nitrogen flows from the high-temperature zone to the low-temperature zone in the sintering system, and is in reverse contact with the material.

[0015] Compared with the prior art, the utility model has the following advantages: by arranging a multi-stage "fishbone" shaped material lifting plate in the low-temperature calcining furnace and a spiral lifting plate in the high-temperature calcining furnace, it is beneficial to improve the mixing uniformity of the sintering materials in the low-temperature calcining furnace and can effectively avoid the occurrence of material backmixing.

[0016] By setting different temperature zones and temperature control switches along the traveling direction of the solid mixed materials in the high and low temperature calcining furnaces, and establishing a PLC automatic interlocking device between the temperature control switch and the wireless temperature sensor set in the corresponding calcining temperature zone, the temperature in different temperature zones can be automatically controlled, which is beneficial to improve the sintering compaction density and carbon coating uniformity of the product and realize the effective use of energy.

[0017] The utility model has a simple structure, is conducive to realizing automation and continuous operation, and improves the utilization efficiency of a single set of equipment

[0018] And the stability of product quality is suitable for industrial application. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a schematic diagram of the overall structure of the utility model;

[0020] FIG2 is a schematic diagram of the structure of a low-temperature calcining furnace of the utility model;

[0021] FIG3 is a schematic diagram of the structure of a high temperature calcining furnace of the utility model;

[0022] FIG4 is a schematic cross-sectional view of the reaction chamber of the low-temperature rotary furnace of the present invention.

[0023] Figure numerals: 1, low temperature calcining furnace, 101, low temperature furnace protection shell, 102, low temperature furnace mixing reaction chamber, 103, low temperature furnace heating layer, 104, low temperature furnace fixed base, 105, low temperature furnace material copying plate, 105a, main copying plate, 105b, multi-stage auxiliary copying plate, 105c, material flow chamber, 106, low temperature furnace mixing reaction chamber, 107, wireless temperature control sensor, 108, low temperature furnace electric heating circuit, 109, heating layer master control switch, 110, low temperature furnace material inlet, 111, low temperature furnace material outlet, 112, temperature control switch; 2. High-temperature calcining furnace, 201. High-temperature furnace material inlet, 202. High-temperature furnace spiral material copying plate, 203. High-temperature furnace heating layer, 204. High-temperature furnace fixed base, 205. High-temperature furnace material outlet, 206. High-temperature furnace electric heating circuit, 207. High-temperature furnace wireless temperature control sensor; 3. Material transfer pipeline, 4. Material transmitter, 5. Low-temperature furnace feed bin, 6. Multi-stage material cooling device, 601. Cooling device material inlet, 602. Cooling device material discharge port, 7. Power cord, 8. Nitrogen inlet, 9. Buffer silo, 10. Nitrogen outlet.

[0024] a and b are the rotating motors of the low-temperature rotary furnace and the high-temperature calcining rotary furnace, respectively. DETAILED DESCRIPTION

[0025] The utility model is used for a continuous calcining device for producing lithium iron phosphate, comprising a low-temperature furnace feeding bin, a low-temperature calcining furnace, a high-temperature calcining rotary furnace, a material transfer pipeline, a buffer bin, a material conveyor, a multi-stage material cooling device, a heat source, a nitrogen channel and related connection control valves and components.

[0026] The low-temperature calcining furnace, the high-temperature calcining furnace and the multi-stage material cooling device are respectively provided with a material inlet and a material outlet, wherein the low-temperature furnace feed bin is connected to the material inlet of the low-temperature calcining furnace, and the material outlet of the low-temperature calcining furnace is connected to the material inlet of the high-temperature calcining rotary furnace. A material transfer pipeline is provided from the material outlet of the low-temperature calcining furnace to the material inlet of the high-temperature calcining rotary furnace, and a buffer silo and a material conveyor are arranged in series on the material transfer pipeline. A connection is established between the material outlet of the high-temperature calcining rotary furnace and the material inlet of the multi-stage material cooling device.

[0027] Furthermore, both the low temperature calcining furnace and the high temperature calcining furnace are rotatable furnaces, and a rotating motor is provided near the material inlet to drive the low temperature calcining furnace and the high temperature calcining furnace to rotate through a gear support structure. The low temperature calcining furnace and the high temperature calcining furnace use electric heating to provide the heat required for continuous calcination.

[0028] Furthermore, the low-temperature calcining furnace body and the high-temperature calcining furnace body are respectively provided with a protective shell, an electric heating layer, and a mixing reaction chamber shell in sequence from the outside to the inside.

[0029] As shown in FIG1 , the low-temperature calcining furnace includes a low-temperature furnace protection shell and a low-temperature furnace mixing reaction chamber shell. Both ends of the low-temperature furnace mixing reaction chamber shell extend out of the low-temperature furnace protection shell and are provided with a gear support mechanism. The rotating motor drives the mixing reaction chamber shell of the low-temperature calcining furnace to rotate through the gear support structure.

[0030] The inner wall of the protective shell is provided with a heat-insulating lining, and its material can be selected from any one or two or three of aluminum silicate fiber, graphite or silicon carbide, etc.; a low-temperature furnace heating layer is provided outside the lower mixing reaction chamber shell in the low-temperature furnace protective shell 101. The low-temperature furnace heating layer is parallel to the mixing reaction chamber shell.

[0031] Furthermore, the reaction chamber wall in the mixing reaction chamber of the low-temperature calcining furnace is sequentially provided with multiple levels of material copying plates;

[0032] Furthermore, the multi-stage material copying plate is composed of a main copying plate and n-stage auxiliary copying plates which are alternately arranged in sequence, wherein 3≤n≤8, and the shape thereof is like a fishbone;

[0033] Furthermore, the bottom end of the main copying plate is parallel to the wall of the mixing reaction chamber and is seamlessly welded thereto, and the top end is in a broken line shape to form a material flow chamber with the top ends of the main copying plates of other levels of materials, wherein the range of the top angle α of the main copying plate is selected as: 90°<α≤120°;

[0034] Furthermore, the multiple levels of alternate auxiliary copying plates are parallel to each other, and both ends thereof are seamlessly welded to the main copying plates and the reaction chamber wall respectively.

[0035] The mixing reaction chamber of the low-temperature calcining furnace is equipped with calcining zones from low to high temperature according to the direction of material travel, and different calcining zones are equipped with temperature wireless sensors; the wireless temperature sensor probe can be selected from high-temperature and corrosion-resistant materials such as ceramics, silicon carbide and semiconductors; the heating layers of different calcining zones are equipped with temperature control switches, and a PLC automatic interlock is built between the temperature control switch and the temperature wireless sensor set in the corresponding calcining zone.

[0036] As shown in FIG1 , the high-temperature calcining rotary furnace 2 is provided with a high-temperature furnace protection shell and a high-temperature furnace mixing reaction chamber from the outside to the inside. Both ends of the high-temperature furnace mixing reaction chamber shell extend out of the high-temperature furnace protection shell, and the extended part is provided with a gear support structure, and a drive motor is provided to drive the rotation of the high-temperature furnace mixing reaction chamber shell. A high-temperature furnace heating layer is provided outside the high-temperature furnace mixing reaction chamber below the inside of the high-temperature furnace protection shell, and is connected to a temperature control switch. The high-temperature furnace heating layer and the high-temperature furnace mixing reaction chamber shell are parallel and circumferentially distributed to provide heat energy to the furnace body in the form of thermal radiation.

[0037] The inner wall of the high-temperature furnace protection shell is provided with a heat insulation layer, and the material thereof is selected to be high-temperature resistant aluminum silicate fiber.

[0038] Furthermore, a spiral lifting plate 202 is provided in the mixing reaction chamber of the high-temperature furnace, and low-temperature to high-temperature calcination zones are provided according to the direction of material movement, and different calcination zones are provided with temperature wireless sensors, and the temperature control range of each zone can be set specifically according to production parameters.

[0039] The temperature control switch and the temperature wireless sensor set in the corresponding calcining area are connected through a PLC automatic interlocking device to realize automatic control of the required temperature range of each zone.

[0040] The device is also provided with a nitrogen channel, the nitrogen channel air inlet is arranged at the material outlet 205 of the high-temperature calcining furnace, and the nitrogen channel air outlet is arranged at the material inlet of the low-temperature calcining furnace. The nitrogen flow enters along the material outlet 205 of the high-temperature calcining furnace, passes through the material conveyor 4, the high-temperature buffer silo 9, the material transfer pipeline 3, the low-temperature calcining furnace reaction mixing chamber in sequence, and is discharged through the nitrogen outlet 10.

[0041] The device is provided with a plurality of fixed bases at the bottom of the high-temperature calcining furnace and the low-temperature calcining furnace to support the entire furnace body.

[0042] The specific working principle of this device is:

[0043] 1) According to the process requirements, the temperature parameter ranges of different calcination temperature zones of the low-temperature calcination furnace 1 and the high-temperature calcination rotary furnace 2 are set respectively;

[0044] 2) Turn on the rotary motors a and b of the low-temperature calcining furnace 1 and the high-temperature calcining rotary furnace 2 in sequence, and turn on the power supply 7 at the same time, and realize automatic control of the required temperature range of each zone through the PLC automatic interlocking device set between the temperature control switches of the heating layers of different calcining zones in the reaction chambers of the high and low temperature calcining furnaces and the temperature wireless sensors set in the corresponding calcining zones.

[0045] 3) At the same time, the nitrogen inlet valve is opened. When the temperature in the calcining furnace reaches the preset range, the uniformly mixed solid materials are continuously transported to the low-temperature furnace reaction chamber 106 through the low-temperature furnace feed bin 5 and the low-temperature calcining furnace material inlet 110. The solid materials advance under the self-rotation power of the low-temperature furnace reaction chamber 106 and the continuous material mixing action of the multi-stage "fishbone" material lifting plate 105, and pass through the different temperature zones set in the mixing reaction chamber of the low-temperature calcining furnace in turn, and calcine to different degrees. In the continuous sintering process, material spheres are continuously formed; the time the material stays in each temperature zone can be adjusted by the frequency of the furnace body rotation.

[0046] 4) The material is continuously rotated out from the material outlet 111 of the low-temperature calcining furnace under the action of the rotating shear force of the calcining chamber itself, and enters the high-temperature buffer silo 9 through the material transfer pipe 3 by gravity or inertia, and then continuously transported to the mixing reaction chamber of the high-temperature calcining furnace 2 through the spiral conveying track of the material conveyor and the material inlet 201 of the high-temperature calcining rotary furnace;

[0047] 5) The materials are taken and sequentially passed through the low-temperature to high-temperature calcination zones of the high-temperature calcination rotary furnace. Similarly, the solid materials continuously transferred from the low-temperature calcination furnace are mixed by the self-rotation power of the reaction chamber of the high-temperature calcination furnace and the continuous material shoveling and mixing action of the spiral material shoveling plate 202. The materials sequentially pass through different temperature zones sequentially set in the mixing reaction chamber of the high-temperature calcination rotary furnace and are calcined to different degrees.

[0048] 6) The material is continuously transferred to the multi-stage cooling device 6 for cooling through the material outlet 205 of the high-temperature calcining furnace. After the product passes the inspection, it enters the packaging process.

[0049] The utility model provides a multi-stage "fishbone" material lifting plate in the low-temperature calcining furnace and a spiral lifting plate in the high-temperature calcining furnace, which is beneficial to improving the mixing uniformity of sintering materials in the low-temperature calcining furnace and can effectively avoid the occurrence of material back-mixing.

[0050] By setting different temperature zones and temperature control switches along the traveling direction of the solid mixed materials in the high and low temperature calcining furnaces, and establishing a PLC automatic interlocking device between the temperature control switch and the wireless temperature sensor set in the corresponding calcining temperature zone, the temperature in different temperature zones can be automatically controlled, which is beneficial to improve the sintering compaction density and carbon coating uniformity of the product and realize the effective use of energy.

[0051] The above is a preferred embodiment of the present invention. For ordinary technicians in this field, according to the teachings of the present invention, without departing from the principles and spirit of the present invention, changes, modifications, substitutions and variations made to the implementation methods are still within the scope of protection of the present invention.

[0052] The above is a preferred embodiment of the present invention. For ordinary technicians in this field, according to the teachings of the present invention, without departing from the principles and spirit of the present invention, changes, modifications, substitutions and variations made to the implementation methods are still within the scope of protection of the present invention.

Claims

1. A continuous calcination device for producing lithium iron phosphate, characterized in that: It comprises a low-temperature furnace feed bin (5), a low-temperature calcining furnace (1), a buffer bin (9), a high-temperature calcining furnace (2) and a multi-stage material cooling device (6); The low-temperature calcining furnace (1), the high-temperature calcining furnace (2) and the multi-stage material cooling device (6) are respectively provided with a material inlet and a material outlet. The material outlet of the low-temperature furnace feed bin (5) is connected to the material inlet of the low-temperature calcining furnace. The material outlet of the low-temperature calcining furnace is connected to the material inlet of the high-temperature calcining rotary furnace via a pipeline. The pipeline is provided with a buffer bin (9) and a material conveyor (4) in series. The material outlet of the high-temperature calcining rotary furnace is connected to the material inlet of the multi-stage material cooling device (6).

2. A continuous calcination device for producing lithium iron phosphate according to claim 1, characterized in that: The low-temperature calcining furnace (1) and the high-temperature calcining furnace (2) are respectively provided with a protective shell, a heat-insulating lining, an electric heating layer, a mixing reaction chamber and a mixing reaction chamber body in order from the outside to the inside.

3. A continuous calcination device for producing lithium iron phosphate according to claim 2, characterized in that: The electric heating layer is distributed in a parallel and circumferential manner with the shell of the mixing reaction chamber.

4. A continuous calcination device for producing lithium iron phosphate according to claim 2, characterized in that: The inner wall of the mixing reaction chamber of the low-temperature calcining furnace (1) is provided with multiple levels of material lifting plates in sequence, and the inner wall of the mixing reaction chamber of the high-temperature calcining furnace (2) is provided with a spiral lifting plate, and the material of the lifting plate is selected from any one of heat-resistant alloy and silicon carbide.

5. A continuous calcination device for producing lithium iron phosphate according to claim 4, characterized in that: The material copying plate arranged in the low-temperature calcining furnace (1) is composed of a main copying plate and n levels of alternate auxiliary copying plates, wherein 3≤n≤8.

6. A continuous calcination device for producing lithium iron phosphate according to claim 5, characterized in that: The bottom end of the main copying plate is parallel to the inner wall of the mixing reaction chamber and is seamlessly welded thereto, and the top end is in a broken line shape with a folding angle of 90°<α≤120° and is discontinuously connected with the top ends of other main copying plates at all levels to form a material flow chamber; the n levels of alternate auxiliary copying plates are parallel to each other, and the length of each auxiliary copying plate is different, and the two ends thereof are seamlessly welded to the main copying plate and the reaction wall respectively.

7. A continuous calcination device for producing lithium iron phosphate according to claim 2, characterized in that: The high-temperature calcining furnace (2) and the low-temperature calcining furnace (1) are respectively provided with calcining zones from low to high temperatures in the mixing reaction chamber according to the direction of material movement, and temperature wireless sensors are provided in different calcining zones.

8. A continuous calcination device for producing lithium iron phosphate according to claim 7, characterized in that: The heating layers of different calcining zones are equipped with temperature control switches, and a PLC automatic interlock is built between the temperature control switches and the temperature wireless sensors set in the corresponding calcining zones.

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