Manganese iron lithium phosphate calcination rotary kiln guide vane and scraper structure and calcination method

Abstract

The application discloses a kind of lithium manganese iron phosphate calcination rotary kiln flow guide blade and dipper structure and calcination method, spiral flow guide blade is fixed in hot kiln cylinder body, the radial height of the spiral flow guide blade is greater than the maximum accumulation thickness of lower material of the hot kiln cylinder body;Flow guide groove between the spiral flow guide blade is arranged with dipper, the dipper is evenly distributed in the inner wall of the hot kiln cylinder body using axial staggered and angle complementary way, the maximum lifting height of material of the dipper is always lower than the top of the spiral flow guide blade, all falling materials accurately fall into the flow guide groove;The spiral flow guide blade and the dipper inside the hot kiln cylinder body jointly constitute approximately grid-like stiffened plate composite structure, with material flow guide, heat exchange strengthening and cylinder structure strengthening.This application realizes accurate control material, efficient heat exchange, energy saving and cost reduction, high-stability lithium manganese iron phosphate calcination production, improves product quality and production efficiency, reduces production and equipment operation and maintenance cost.

Description

Technical Field

[0002] This invention relates to a rotary kiln equipment technology for lithium manganese iron phosphate, and in particular to a rotary kiln guide vane and scraper structure for roasting lithium manganese iron phosphate, as well as a roasting method. Background Technology

[0003] Lithium manganese iron phosphate (LMP) is a core cathode material for lithium-ion batteries. The high-temperature roasting process during its production directly determines the product's purity and electrochemical properties. An externally heated rotary kiln is the core equipment for the large-scale roasting of LMP. The externally heated rotary kiln uses external heating to supply heat to the cylinder, combined with internal flow guiding and lifting plate structures to achieve continuous material conveying, tumbling, and heat exchange, thus completing the high-temperature roasting of the material.

[0004] Currently, the internal structure of existing externally heated rotary kilns has several technical defects: First, traditional spiral guide vanes are mostly integral short-segment structures with gaps at the joints, making it easy for materials to short-circuit and cross-contaminate during transport. This makes it impossible to accurately control the residence time of materials in the kiln, resulting in some materials being under-roasted and others over-roasted, leading to poor heat uniformity and low product qualification rate. Second, the radial height of conventional guide vanes is too low, only covering the thickness of the conventional material accumulation in the kiln. During material transport, materials are prone to overflowing from the guide channel. Furthermore, when the kiln is ventilated in reverse, the airflow easily carries fine powder and particles out of the kiln, causing material loss and increasing production costs and exhaust gas treatment pressure. Third, the traditional lifting plate structure has a single and fixed arrangement. First, the existing rotary kiln lacks an effective internal reinforcement structure. Long-term continuous high-temperature operation of the cylinder can easily lead to deformation, resulting in poor equipment rigidity, stability, and short service life. To ensure cylinder strength, the cylinder wall thickness needs to be increased, further reducing heat exchange efficiency and increasing equipment weight and manufacturing costs. Second, the feed and discharge ends of the rotary kiln have the same flow guide structure parameters as the main body of the cylinder, resulting in poor feed and discharge uniformity. Uneven material distribution and large differences in heating rates occur at the feed end, while material stagnation and poor discharge occur at the discharge end, severely affecting the quality consistency and production continuity of batch roasting of lithium manganese iron phosphate.

[0005] In summary, the existing rotary kiln has poor compatibility between the internal spiral guide vanes and the lifting plate structure, resulting in core problems such as low material timing accuracy, high material loss, low heat exchange efficiency, insufficient equipment stability, and uneven feeding and discharging. These issues make it difficult to meet the needs of large-scale, high-quality roasting production of high-purity, high-consistency lithium manganese iron phosphate materials. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a reasonable structure, precise material control, efficient heat exchange, low loss and high stability of the guide vane and scraper structure of the lithium manganese iron phosphate roasting rotary kiln.

[0007] The technical solution of this invention is: A spiral guide vane and lifter plate structure for an externally heated rotary kiln for calcining lithium manganese iron phosphate includes a kiln shell, spiral guide vanes, and lifter plate assembly. The specific structural arrangement and design are as follows: 1. Overall flow guiding structure arrangement: The inner wall of the hot kiln cylinder is welded and fixed with spiral flow guiding blades along the entire axial direction of the hot kiln cylinder. The spiral flow guiding blades serve as the core material conveying structure, used to achieve stable feeding of granular and powdered lithium manganese iron phosphate materials along the axial direction of the hot kiln cylinder, and to precisely control the roasting residence time of the materials in the hot kiln cylinder, adapting to the time requirements of the high-temperature roasting process of lithium manganese iron phosphate.

[0008] 2. Segmented Overlapping Spiral Guide Blade Design: The spiral guide blade adopts a segmented spiral structure design. Multiple spiral guide blades are connected end to end along the conveying direction, and a fixed overlap is set at the connection between the beginning and end of adjacent spiral guide blades. There are no gaps or dead angles at the connection of the spiral guide blades, forming a continuous and complete spiral guide channel, which completely eliminates material conveying short circuits, material cross-contamination, and stagnation.

[0009] 3. Ultra-high radial dimension spiral guide blade structure design: The radial height of the spiral guide blade is greater than that of the spiral guide blade in a traditional rotary kiln, and the height of the spiral guide blade is higher than the preset dimension of the maximum material accumulation thickness at the bottom of the hot kiln shell. This ensures that the material will not overflow the guide groove when it is conveyed forward along the guide groove between the spiral guide blades. At the same time, it is suitable for reverse airflow conditions in the hot kiln shell. Under normal process wind speed conditions, it can effectively prevent fine powder and small particles of material from being carried up by the airflow and carried out of the kiln tail, which greatly reduces material loss.

[0010] 4. Staggered Lifting Plate Layout: Three lifting plates are staggered at preset intervals between the gaps of the spiral guide vanes. The three types of lifting plates are staggered and complementary in function, which can realize the all-round turning of all powdery and granular materials in the hot kiln cylinder, without any dead corners of material turning. At the same time, the lifting plates adopt a staggered avoidance design, which does not interfere with the normal axial flow of materials along the spiral guide channel, taking into account both the continuity of material conveying and the uniformity of heat exchange.

[0011] 5. Low-dust material lifting structure design: The lifting plate hot kiln body rotates synchronously, continuously lifting and slightly raising the material in the guide groove between the spiral guide blades. The natural falling trajectory of the material after being lifted is always lower than the top height of the spiral guide blades, ensuring that all the lifted material falls back into the guide groove between the spiral guide blades. Structurally, this avoids the material dust and fine particles being carried away by the reverse central airflow in the hot kiln body, further eliminating material scattering and loss.

[0012] 6. Grid-like reinforcing composite structure: The high radial spiral guide vanes, together with the staggered lifters, form an integrated reinforcing rib plate structure with an approximate grid shape inside the hot kiln shell. This composite structure has the triple functions of guiding flow, heat exchange and structural reinforcement, without the need for additional reinforcing components.

[0013] 7. Lightweight kiln shell adaptation design: Relying on the structural reinforcement of the internal grid-like reinforcing ribs, the kiln shell structure design can be optimized while ensuring the overall rigidity and strength of the kiln shell remains unchanged. This reduces the shell wall thickness, lowers the equipment weight and manufacturing cost, and the thin-walled shell increases the heat exchange area of ​​the guide vanes and lifters, thereby improving the heat transfer efficiency from the external heat source to the material inside the kiln shell.

[0014] 8. Optimized design of multi-head spiral guide vanes at the feed end: The feed end of the hot kiln cylinder adopts a multi-head spiral guide vane structure. Compared with the spiral guide vanes of the main body of the cylinder, the number of spiral heads of the spiral guide vanes at the feed end is increased by four times, and the lead of the spiral guide vanes at the feed end is consistent with that of the spiral guide vanes of the main body of the cylinder. The multi-head guide structure realizes uniform distribution of feed, and the feed end can quickly and evenly distribute the material, so that the material can achieve synchronous and uniform heating in the initial stage of heating, realize stable and uniform feeding of material, and eliminate the problems of material accumulation and flow deviation.

[0015] The beneficial effects of this invention are: 1. This invention achieves stable axial material conveying by welding spiral guide vanes along the entire length of the hot kiln cylinder. At the same time, the segmented overlapping seamless spiral guide vane design completely eliminates material conveying short circuits, material leakage, and stagnation. It can precisely control the roasting residence time of lithium manganese iron phosphate material in the hot kiln cylinder, ensuring that the heating time of each batch of material is consistent, fundamentally solving the problems of over-burning and under-burning of materials, and significantly improving the purity and electrochemical performance consistency of lithium manganese iron phosphate products.

[0016] 2. This invention uses a heightened spiral guide vane structure, with the height of the spiral guide vane exceeding the maximum accumulation thickness of the material, which can completely block the overflow problem during the material conveying process; at the same time, it is combined with a low dust material lifting structure, the lifting and falling range of the material is controlled, and combined with the reverse airflow working condition adaptation design, it effectively avoids the airflow in the kiln carrying fine powder and particles of material out of the kiln body, greatly reducing material scattering loss, significantly improving raw material utilization rate, and reducing the pressure of tail gas dust treatment.

[0017] 3. This invention features three staggered lifting plates arranged within the guide channels between the spiral guide blades, enabling omnidirectional, dead-angle-free material agitation. This completely solves the problems of localized material accumulation and uneven heat exchange in traditional equipment, significantly improving the heat exchange efficiency between the material and the hot air and kiln wall, shortening the roasting cycle, reducing overall equipment energy consumption, and increasing the efficiency of large-scale production. Simultaneously, the mesh-like composite structure increases the effective heat exchange area within the kiln, further enhancing the heat exchange effect.

[0018] 4. The present invention uses a heightened spiral guide vane and an interlaced baffle to form an integrated grid-like reinforcing rib structure. Without the need for additional reinforcing components, it can significantly improve the structural strength and overall rigidity of the hot kiln shell, effectively resist the thermal deformation and stress deformation of the hot kiln shell under high temperature continuous operation, reduce the probability of equipment failure, significantly extend the continuous working service life of the hot kiln, and reduce the frequency and cost of equipment maintenance.

[0019] 5. This invention relies on the reinforcing effect of the composite stiffening plates inside the kiln shell to reduce the wall thickness of the shell while ensuring that the rigidity and strength of the kiln shell meet the standards, thereby achieving lightweight design of the equipment and reducing the manufacturing cost. At the same time, the thin-walled kiln shell has lower thermal conductivity resistance and higher heat source utilization, further improving the overall heat exchange efficiency and achieving energy-saving and efficiency-enhancing production results.

[0020] 6. This invention adopts a multi-head spiral guide vane structure at the feeding end of the hot kiln. Compared with the spiral guide vane structure of the main body of the hot kiln, the number of heads is four times that of the main body, while the lead remains the same. The feeding end can achieve rapid and uniform material distribution, so that the material maintains a consistent heating rate in the initial heating stage, avoiding product performance deviations caused by initial heating differences; eliminating material accumulation, blockage, and flow deviation problems, and ensuring continuous, stable, and standardized production of lithium manganese iron phosphate roasting process.

[0021] 7. This invention is mainly applied to the high-temperature roasting and cooling processes of lithium manganese iron phosphate powder and granular materials, which can improve product quality and production efficiency, reduce production and equipment operation and maintenance costs, and is also applicable to other external heating rotary kiln material conveying, heat exchange and roasting processing scenarios. It is easy to promote and implement and has good economic benefits. Attached Figure Description

[0022] Figure 1 A schematic diagram of the kiln body shape in the guide vane and scraper plate structure of a rotary kiln for roasting lithium manganese iron phosphate. Figure 2 for Figure 1 Cross-sectional view of the intermediate-heat kiln section; Figure 3 This is a partially enlarged cross-sectional view of the cylinder of the second intermediate-temperature kiln; Figure 4 for Figure 2 Enlarged cross-sectional view of the feed end. Detailed Implementation

[0023] Example 1: See Figure 1 -- Figure 4 In the figure, 1-hot kiln body, 2-spiral guide vane, 3-lifting plate, 4-feed end body, 5-feed spiral guide vane, 6-tire, 7-hot and cold kiln connecting flange, 8-overlapping part of spiral guide vane, 9-cooling body.

[0024] The lithium manganese iron phosphate rotary kiln consists of two main parts: a hot kiln body 1 and a cooling kiln body 9. Both the hot kiln body 1 and the cooling kiln body 9 are supported by tires 6. The entire lithium manganese iron phosphate rotary kiln is installed horizontally. The hot kiln body 1 is an externally heated lithium manganese iron phosphate roasting rotary kiln. The hot kiln body 1 is a horizontal cylindrical steel structure with external electric heating (not shown in the figure). The working state inside the hot kiln body 1 is that the material is conveyed axially forward and the gas flows in the opposite direction, so as to realize the high-temperature roasting of the material and the atmosphere control.

[0025] Spiral guide vanes 2 are fully welded along the entire axial direction inside the hot kiln shell 1. The spiral guide vanes 2 are prefabricated in sections and installed by on-site welding. The length of each spiral guide vane 2 is designed to match the diameter and pitch of the hot kiln shell 1. Adjacent spiral guide vanes 2 overlap end to end, and the overlap width is controlled within a reasonable process range. The overlapping part 8 of the spiral guide vanes is connected by spot welding to ensure that the entire guide channel is continuous without any breaks. The material can only be conveyed forward in one direction along the guide groove between the spiral guide vanes 2, completely eliminating the short-circuit material flow channel.

[0026] The spiral guide vane 2 adopts an extended structure design. The radial height of the spiral guide vane 2 exceeds the maximum material accumulation thickness inside the hot kiln shell 1 by 30-50mm during normal operation (specific values ​​can be 32mm, 36mm, 40mm, 45mm, 48mm, etc., set according to actual needs, and not listed one by one). This ensures that the material will not overflow the guide groove between the spiral guide vanes 2 under full-load material conveying conditions. At the same time, it is compatible with the conventional process parameters of reverse ventilation velocity (0.5-1.5m / s) inside the hot kiln shell 1, effectively suppressing the flying and carrying out of material dust.

[0027] In the guide channel between adjacent spiral guide vanes 2, straight plate-type lifting plates 3 are arranged at equal intervals and staggered. The lifting plates 3 are axially staggered and angularly complementary, and are evenly distributed on the circumference and axial position of the hot kiln cylinder 1. During the slow rotation of the hot kiln cylinder 1, the lifting plates 3 at different positions can respectively turn over and scatter the materials on the left, middle and right sides of the guide channel between the spiral guide vanes 2, so as to achieve heat exchange without dead corners of the materials. Moreover, the staggered arrangement will not block the axial conveying path of the materials, ensuring the smooth conveying of materials.

[0028] The height of the material lifted by the lifting plate 3 is strictly controlled. The maximum lifting height of the material is always lower than the top of the spiral guide blade 2. All falling material falls precisely into the guide groove between the spiral guide blades 2, avoiding fine powder material from being suspended in the central airflow area inside the hot kiln cylinder 1, and eliminating the problem of material loss due to airflow.

[0029] The heightened spiral guide vanes 2 and staggered lifting plates 3 are fully welded to the inner wall of the kiln shell 1, forming a grid-like rib structure inside the shell. This provides all-around support to the kiln shell 1 and enhances its resistance to high-temperature deformation. Based on the advantages of this structural reinforcement, the wall thickness of the kiln shell 1 can be reduced by approximately 2-4 mm from the traditional thickness. While ensuring the rigidity and stability of the equipment during operation, this improves the heat transfer rate of the kiln shell 1 and reduces the equipment's weight and material costs.

[0030] The feed spiral guide vanes 5 welded inside the feed end cylinder 4 of the lithium manganese iron phosphate rotary kiln adopt an eight-head spiral structure, while the main spiral guide vanes 2 inside the hot kiln cylinder 1 have a double-head spiral structure. The feed spiral guide vanes 5 and spiral guide vanes 2 have the same lead. The feed spiral guide vanes 5 quickly disperse and evenly distribute the material through the eight-head spiral, so that the material initially entering the hot kiln cylinder 1 spreads quickly and the heating rate is uniform, avoiding local material heating too fast or too slow. The multi-head spiral structure of the feed spiral guide vanes 5 ensures stable and uniform material feeding and eliminates feeding blockage and segregation problems.

[0031] Example 2: A method for roasting lithium manganese iron phosphate material in a rotary kiln, comprising the following steps: S1. Feeding and distributing stage: The material enters through the feeding end of the hot kiln cylinder and is evenly distributed to the circumference of the hot kiln cylinder by the spiral guide blades at the feeding end in a multi-head spiral guide manner, so as to achieve rapid and uniform distribution at the feeding end and make the material heat up synchronously and uniformly in the initial heating stage. S2, Axial Conveying Stage: After the material enters the main body of the hot kiln cylinder, it is stably conveyed forward along the axial direction in the continuous spiral guide channel formed by the spiral guide blades; the ultra-high radial structure of the spiral guide blades constrains the material in the guide groove, preventing the material from overflowing or flowing out, while blocking the reverse central airflow from entraining the fine powder of the material. S3, Turning and Heat Exchange Stage: During the axial conveying of materials, the lifting plates rotate synchronously with the hot kiln cylinder, continuously lifting and raising the materials in the guide channel; through the staggered arrangement and differentiated lifting height of adjacent lifting plates, the materials are turned over in all directions in the circumferential and axial directions, and the natural falling trajectory of the raised materials is always lower than the top of the spiral guide blades, ensuring that all materials fall back into the guide channel; S4. Synergistic Enhancement Stage: The composite structure of the spiral guide vanes and the lifting plate forming a grid-like reinforcing rib provides structural support to the wall of the hot kiln cylinder during the material flow and heat exchange process, so that the thinned cylinder maintains sufficient rigidity and strength, while the thin-walled cylinder improves the heat transfer efficiency from the external heat source to the internal material. S5. Increased heat exchange area: The spiral guide vanes and the lifting plates are welded inside the hot kiln cylinder, which increases the contact area between the cylinder and the material, improves the heat exchange efficiency, and effectively reduces energy consumption.

[0032] Preferred solution: In step S2, by adjusting the pitch of the spiral guide vanes and / or the rotational speed of the hot kiln cylinder, the roasting residence time of the material in the hot kiln cylinder is precisely controlled to adapt to the time requirements of the high-temperature roasting process of lithium manganese iron phosphate.

[0033] Preferred solution: In step S3, the differentiated lifting height of the lifting plate is coordinated with the rotation of the hot kiln cylinder, so that the material forms a cyclic tumbling pattern of lifting-dispersing-falling within a single pitch of the spiral guide blade, and the material tumbling areas within adjacent pitches are connected to each other in the axial direction without any tumbling dead angles.

[0034] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications made based on the technical essence of the present invention shall still fall within the scope of the technical solution of the present invention.

Claims

1. A guide vane and skid plate structure for a rotary kiln for roasting lithium manganese iron phosphate, comprising a heated kiln cylinder, characterized in that: Spiral guide vanes are continuously welded and fixed on the inner wall of the hot kiln shell along the circumferential and axial directions. The radial height of the spiral guide vanes is greater than the maximum material accumulation thickness at the bottom of the hot kiln shell. Lifting plates are staggered at equal intervals in the guide groove between two adjacent spiral guide blades. The lifting plates are evenly distributed on the circumference and axial position of the hot kiln cylinder in a way that is axially staggered and angularly complementary. The lifting plates at different positions respectively turn over and throw the material on the left, middle and right sides of the guide groove, so as to achieve heat exchange without dead corners. Moreover, the staggered arrangement will not block the axial conveying path of the material, ensuring the smooth conveying of the material. The maximum lifting height of the material by the lifting plates is always lower than the top of the spiral guide blades, and all falling material falls accurately into the guide groove. The spiral guide vanes and the lifting plates together form an approximately mesh-like reinforcing rib composite structure inside the hot kiln shell. The composite structure has three functions: material guiding, heat exchange enhancement, and shell structure reinforcement.

2. The guide vane and scraper plate structure of a rotary kiln for roasting lithium manganese iron phosphate according to claim 1, characterized in that: The spiral guide vanes adopt a segmented spiral structure. Multiple spiral guide vanes are connected end to end along the conveying direction, and a fixed overlap is set at the connection between the beginning and end of adjacent spiral guide vanes to form a continuous spiral guide channel without gaps or dead angles.

3. The guide vane and scraper plate structure of a rotary kiln for roasting lithium manganese iron phosphate according to claim 1, characterized in that: The radial height of the spiral guide vanes exceeds the maximum material accumulation thickness inside the hot kiln cylinder by 30-50mm during normal operation, ensuring that the material will not overflow the guide trough under full-load material conveying conditions.

4. The guide vane and scraper plate structure of a rotary kiln for roasting lithium manganese iron phosphate according to claim 1, characterized in that: The measuring plates are arranged in groups, with each group consisting of three measuring plates. The three measuring plates are arranged in a way that is axially staggered and angularly complementary. Different groups are arranged at intervals but in the same way.

5. The guide vane and scraper plate structure of a rotary kiln for roasting lithium manganese iron phosphate according to claim 1, characterized in that: The feed end of the hot kiln shell is provided with a feed end spiral guide vane, which adopts an eight-head spiral structure. The spiral guide vane of the main body section of the hot kiln shell adopts a double-head spiral structure, and the lead of the feed end spiral guide vane and the spiral guide vane of the main body section are consistent.

6. The guide vane and scraper plate structure of a rotary kiln for roasting lithium manganese iron phosphate according to claim 1, characterized in that: Relying on the structural reinforcement effect of the composite structure, the wall thickness of the hot kiln cylinder is reduced by 2mm to 4mm compared with the same specification cylinder without internal reinforcing ribs, and the stiffness and strength of the thinned cylinder meet the requirements of the external heating and firing process.

7. A method for roasting lithium manganese iron phosphate material in a rotary kiln using the guide vanes and lifting plate structure of a rotary kiln for roasting lithium manganese iron phosphate as described in any one of claims 1-6, comprising the following steps: S1. Feeding and distributing stage: The material enters through the feeding end of the hot kiln cylinder and is evenly distributed to the circumference of the hot kiln cylinder by the spiral guide blades at the feeding end in a multi-head spiral guide manner, so as to achieve rapid and uniform distribution at the feeding end and make the material heat up synchronously and uniformly in the initial heating stage. S2, Axial Conveying Stage: After the material enters the main body of the hot kiln cylinder, it is stably conveyed forward along the axial direction in the continuous spiral guide channel formed by the spiral guide blades; the ultra-high radial structure of the spiral guide blades constrains the material in the guide groove, preventing the material from overflowing or flowing out, while blocking the reverse central airflow from entraining the fine powder of the material. S3, Turning and Heat Exchange Stage: During the axial conveying of materials, the lifting plates rotate synchronously with the hot kiln cylinder, continuously lifting and raising the materials in the guide channel; through the staggered arrangement and differentiated lifting height of adjacent lifting plates, the materials are turned over in all directions in the circumferential and axial directions, and the natural falling trajectory of the raised materials is always lower than the top of the spiral guide blades, ensuring that all materials fall back into the guide channel; S4. Synergistic Enhancement Stage: The composite structure of the spiral guide vanes and the lifting plate forming a grid-like reinforcing rib provides structural support to the wall of the hot kiln cylinder during the material flow and heat exchange process, so that the thinned cylinder maintains sufficient rigidity and strength, while the thin-walled cylinder improves the heat transfer efficiency from the external heat source to the internal material. S5. Increased heat exchange area: The spiral guide vanes and the lifting plates are welded inside the hot kiln cylinder, which increases the contact area between the cylinder and the material, improves the heat exchange efficiency, and effectively reduces energy consumption.

8. The method for roasting lithium manganese iron phosphate materials in a rotary kiln according to claim 7, characterized in that: In step S2, the roasting residence time of the material in the hot kiln is precisely controlled by adjusting the pitch of the spiral guide vanes and / or the rotational speed of the hot kiln cylinder to adapt to the time requirements of the high-temperature roasting process of lithium manganese iron phosphate.

9. The method for roasting lithium manganese iron phosphate materials in a rotary kiln according to claim 7, characterized in that: In step S3, the differentiated lifting height of the lifting plate, in conjunction with the rotation of the hot kiln cylinder, causes the material to form a cyclical tumbling pattern of lifting, dispersing, and falling within a single pitch of the spiral guide blades, and the material tumbling areas within adjacent pitches are connected to each other axially without any dead corners.

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