Composite drying method and equipment for efficiently preparing high-quality iron phosphate

Abstract

The invention relates to iron phosphate preparation, in particular to a composite drying method and equipment for efficiently preparing high-quality iron phosphate, and the method comprises the following steps: placing an iron phosphate material in a set drying environment, and reducing the water content of the iron phosphate material to be below a set value through a fluidization-rotation composite drying process; the fluidization-rotation composite drying process comprises the steps that fluidization airflow is introduced to enable the iron phosphate material to be in a fluidization state, and meanwhile the iron phosphate material continuously moves in the conveying direction through rotation motion of equipment. The equipment comprises an outer barrel, an inner barrel and a power assembly, an air cavity is formed between the outer barrel and the inner barrel, the air cavity is communicated with an external air source, and the external air source penetrates through the inner barrel through the air cavity and enters a fluidization rotation cavity on the inner side to provide fluidization power for materials. In the drying process, the materials are always kept in a fluidized and rolling state, the material adhesion problem is solved, and the product uniformity is improved; and the heat exchange drying rate is increased through cooperation of fluidization and rotation, and efficient and automatic production is achieved.

Description

Technical Field

[0001] This invention relates to the field of lithium-ion battery cathode material precursor preparation technology, and particularly to a composite drying method and equipment for efficiently preparing high-quality iron phosphate, which is especially suitable for the continuous drying and calcination of iron phosphate (FePO4). Background Technology

[0002] Iron phosphate is a key precursor for preparing high-performance lithium iron phosphate (LiFePO4) cathode materials for lithium-ion batteries. Its drying and calcination processes directly affect the purity, crystallinity, particle size, morphology, and final electrochemical performance of the product.

[0003] Currently, commonly used drying equipment in industrial production includes steam rotary dryers, flash dryers, paddle dryers, and microwave dryers; calcination equipment mainly includes rotary kilns and gas suspension roasting furnaces. These devices have the following problems in practical applications:

[0004] 1. Rotary kilns are prone to sticking to the walls and forming balls when processing high-moisture filter cakes, requiring pre-drying equipment, resulting in a long process and low thermal efficiency. 2. Gas suspension furnaces have high requirements for material flowability and particle size, and the system is complex and difficult to control; 3. Although microwave drying is significantly energy-efficient, it requires high equipment investment and limits large-scale production.

[0005] It is evident that traditional equipment still has room for improvement in terms of heat utilization efficiency, material processing uniformity, and continuous operation. Existing technologies should be optimized to adapt to both highly moist and viscous materials, while also achieving efficient, energy-saving, and continuous production. Therefore, more reasonable technical solutions are needed to address the technical problems existing in current technologies. Summary of the Invention

[0006] The main objective of this invention is to provide a composite drying method and equipment for the efficient preparation of high-quality ferric phosphate. Through equipment structure innovation and process optimization, the wet ferric phosphate material can be directly fed into the rotary device to achieve continuous, efficient, and uniform drying and calcination, thereby improving product quality and energy utilization efficiency.

[0007] To achieve the above objectives, the drying method adopted by the present invention is as follows: A composite drying method for efficiently preparing high-quality ferric phosphate includes: Moist ferric phosphate material is placed in a set drying environment and subjected to a fluidized-rotary combined drying process to reduce the moisture content of the ferric phosphate material to below the set value. The fluidized-rotary composite drying process includes introducing a fluidizing gas flow to fluidize the iron phosphate material, while simultaneously utilizing the rotational motion of the equipment to continuously move the material along the conveying direction.

[0008] The aforementioned composite drying method, under the action of hot airflow, fills the ferric phosphate material bed with gas, breaking down liquid bridges formed between particles due to surface moisture. This prevents the moist ferric phosphate material from clumping and adhering to the inner wall of the equipment during the drying process. The large and constantly renewed gas-solid contact area ensures uniform temperature distribution within the bed. As drying progresses, the material gradually transforms from a highly moist, agglomerated state to a dispersed, suspended state, ultimately achieving efficient heat and mass transfer. Simultaneously, the rotational motion of the equipment causes the ferric phosphate material in the bed to be lifted, agitated, and slid down by the inner cylinder wall. The inclined cylinder, in one cycle of agitation and sliding, causes the ferric phosphate material to shift towards the lower end. This cyclical process ensures continuous movement of the material along the conveying direction. Therefore, the drying process for moist ferric phosphate material is simplified, and the processing efficiency is improved.

[0009] Furthermore, in this method, to better dry the ferric phosphate material, the drying environment is optimized, and one feasible option is proposed: during the fluidized-rotary combined drying process, ferric phosphate material with a moisture content of 20%~60% is placed in a rotating combined fluidized bed, and an airflow of 60℃~600℃ is introduced for drying, reducing the moisture content of the ferric phosphate material to 0.5%~25%. Using this scheme, ferric phosphate material with high moisture content can be processed without adhesion; simultaneously, during drying, the drying speed and effect can be controlled by adjusting the temperature of the introduced airflow, i.e., the higher the temperature of the introduced airflow, the faster the dehydration and drying speed of the ferric phosphate material.

[0010] In some solutions, the airflow velocity in the fluidized bed can be controlled by adjusting the gas flow rate, taking into account the moisture content or surface adhesion of the ferric phosphate material, to achieve the optimal fluidization state of the ferric phosphate material and prevent it from clumping and sticking to the walls. During operation, the airflow can be adjusted manually or automatically using valve groups, and the fluidization state of the ferric phosphate material in the fluidized rotary chamber can be observed through an internal video display or an observation window. Timely flow rate adjustments can be made to ensure the ferric phosphate material remains in a suitable fluidized state, thus optimizing the treatment effect of the fluidized rotary composite drying process.

[0011] The above content describes the method of fluidized rotary combined drying. The present invention also provides a processing device for performing fluidized rotary drying.

[0012] A high-efficiency composite drying device for preparing high-quality iron phosphate, used to achieve the above-mentioned composite drying method, includes an outer cylinder and an inner cylinder, with an air cavity formed between the outer cylinder and the inner cylinder. The air cavity is connected to an external air source and used to guide the airflow through the inner cylinder into the fluidized rotary chamber on the inside. The composite drying device also includes a power component for driving the outer cylinder and the inner cylinder to rotate synchronously.

[0013] The aforementioned processing equipment allows external airflow to pass through the inner cylinder and enter the fluidized rotary chamber, causing the ferric phosphate material to be in a fluidized state and not to adhere to the inner wall of the equipment. Under the action of the airflow, it undergoes drying treatment. At the same time, by utilizing the synchronous rotation of the outer and inner cylinders, the ferric phosphate material is carried up, stirred, and slid down by the inner cylinder wall. In one cycle of stirring and sliding, the inclined cylinder causes the ferric phosphate material to move towards the lower end. This cyclical process enables the material to move continuously along the conveying direction.

[0014] Furthermore, the ferric phosphate material is fluidized and tumbled inside the inner cylinder to achieve the drying process. The structure of the inner cylinder can be constructed in various forms and is not limited to one specific one. Here, we optimize and propose one feasible option: the inner cylinder includes several fluidized gas distribution plates, which are connected end to end to form a circular or polygonal inner cylinder. When adopting the above scheme, the fluidized gas distribution plates can be straight plates or arc-shaped plates. Adjacent fluidized gas distribution plates are spliced ​​together to form the inner cylinder. The inner cylinder and the outer cylinder are coaxially arranged and rotate synchronously. When the power component applies driving force to the outer cylinder, the outer cylinder drives the inner cylinder to rotate synchronously, thereby continuously tumbling and tumbling the ferric phosphate material in the fluidized rotating chamber and maintaining a fluidized state, thus enabling drying.

[0015] Furthermore, the inner and outer cylinders can be synchronously connected and fitted through various structures, and are not limited to a single one. Here, we optimize and propose one feasible option: an annular gap is formed between the inner and outer cylinders, and several supporting members are arranged within the annular gap to divide it into several air chambers. When adopting the above scheme, the annular gap can be a uniform circular gap, a polygonal gap, or a gap enclosed by a polygon and a circle.

[0016] In some designs, the support components include structures such as T-shaped support plates and L-shaped support plates, which are fixed between the outer cylinder and the inner cylinder by means of welding, riveting, bolting, etc.

[0017] In other solutions, a groove can be cut into the outer cylinder, and a fluidizing gas distribution plate can be placed at the groove. At the same time, a gap is formed between the fluidizing gas distribution plate and the groove to form an air cavity. The external gas source enters the groove through the gap and then enters the internal fluidized rotary composite cavity through the fluidizing gas distribution plate to achieve the drying treatment of iron phosphate material.

[0018] In some other designs, the support component can be integrally formed with the inner cylinder and then connected to the outer cylinder. With this structure, the support component can be connected to the outer cylinder using fasteners.

[0019] Furthermore, the air cavity is connected to an external air source to obtain fluidized gas. The connection structure can be constructed in various forms and is not limited to a single one. Here, we optimize and propose one feasible option: an air inlet box structure is provided at the air cavity. The air inlet box structure is connected to the external air source and forms a vent that connects to the air inlet cavity. When the vent is connected to the air cavity, the gas from the external air source enters the air cavity through the vent. With this scheme, the air inlet box structure and the air cavity slide together, and the mating surface is airtight. When the outer and inner cylinders rotate, they slide together and can switch between connecting to the air cavity via the air inlet box structure. Generally, rotating to the lowermost air cavity will connect to the air inlet box structure and obtain fluidized gas.

[0020] Furthermore, the air inlet box structure is fitted with the outer and inner cylinders to supply air. Its structure can adopt various schemes; here, we optimize and propose one feasible option: the air inlet box structure has several vents spaced at intervals along its circumference, and the layout of the vents corresponds to the air cavity. When adopting the above scheme, the number of vents can be single or multiple. When using a single vent, as the outer and inner cylinders rotate, the single vent connects to the air cavity one by one; when using multiple vents, as the outer and inner cylinders rotate, the air cavity passes through and connects to the vents sequentially.

[0021] Furthermore, the mating structure of the outer and inner cylinders can take various forms. However, to ensure air supply and maintain sealing during rotation, an optimization is proposed, and one feasible option is suggested: the end faces of the outer and inner cylinders are flush to form a smooth contact surface, and the air inlet box is correspondingly attached to the smooth contact surface to form a contact sealing structure. The contact sealing structure includes a venting surface corresponding to the smooth contact surface, and the vent is located on the venting surface and is switched to communicate with the air cavity. When adopting the above scheme, the cross-section of the vent is generally less than or equal to the cross-section of the air cavity. However, when the distance between adjacent air cavities is greater than a certain extent, the cross-section of the vent can also be greater than the cross-section of the air cavity to avoid air leakage when the air cavity and the vent are switched to communicate.

[0022] Furthermore, to maintain better sealing and prevent air leakage when the vent is connected to the air cavity, or to prevent airflow when the air cavity switches connections with the vent, an optimization is proposed, and one feasible option is suggested: a sealing structure is formed on both sides of the vent, and the length of the sealing structure is greater than or equal to the air inlet length of the air cavity on its circumference. When adopting the above solution, the sealing structure can be constructed as a sealing strip, sealing baffle, or sealing block, integrally formed with the air inlet box structure, or connected and fixed to the air inlet box structure using fasteners.

[0023] Furthermore, the equipment provided by this invention can connect to an external feeding mechanism and subsequent processing mechanism during material feeding and discharging, achieving continuous automatic feeding and discharging. Specifically, an optimized and feasible option is proposed here: the outer cylinder is connected to a feeding structure, which includes a feeding channel extending into the fluidized rotary chamber; it also includes a discharging structure, which includes a discharging channel located at the discharging end of the outer cylinder. When adopting the above solution, the feeding structure may include a feeding hopper, and the discharging structure may include a discharging hopper.

[0024] Compared with the prior art, some of the beneficial effects of the technical solution disclosed in this invention include: A fluidized airflow is introduced through a fluidization-rotation composite structure. Under the action of the hot airflow, the ferric phosphate material bed is filled with gas, breaking the liquid bridges formed between particles due to surface wetting. The material gradually changes from a highly moist and agglomerated state to a dispersed and suspended state, preventing the moist ferric phosphate material from clumping and adhering to the inner wall of the equipment during the drying process. At the same time, under the action of the rotation mechanism, the ferric phosphate material is kept in a fluidized and tumbling state, which not only solves the problem of material adhesion but also improves product uniformity. The synergistic effect of fluidization and rotation significantly improves heat exchange efficiency and drying rate. Meanwhile, the rotational motion of the equipment enables the ferric phosphate material to move and be conveyed continuously along the conveying direction, realizing the efficient and automated production of high-quality ferric phosphate. Attached Figure Description

[0025] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 A schematic diagram of the material morphology for processing ferric phosphate in a fluidized rotary kiln (0 min).

[0027] Figure 2 A schematic diagram of the material morphology for processing ferric phosphate in a fluidized rotary kiln (15 min).

[0028] Figure 3 A schematic diagram of the material morphology for processing ferric phosphate in a fluidized rotary kiln (30 min).

[0029] Figure 4 A schematic diagram of the material morphology for processing ferric phosphate in a fluidized rotary kiln (45 min).

[0030] Figure 5 A schematic diagram of the material morphology for processing ferric phosphate in a fluidized rotary kiln (60 min).

[0031] Figure 6 A schematic diagram of the material morphology for processing ferric phosphate in a fluidized rotary kiln (75 min).

[0032] Figure 7 A schematic diagram of the material morphology for processing ferric phosphate in a fluidized rotary kiln (90 min).

[0033] Figure 8 A schematic diagram of the material morphology of ferric phosphate material processed in a conventional rotary kiln (0 min).

[0034] Figure 9 A schematic diagram of the material morphology of ferric phosphate material processed in a conventional rotary kiln (15 min).

[0035] Figure 10 A schematic diagram of the material morphology of ferric phosphate material processed in a conventional rotary kiln (30 min).

[0036] Figure 11 A schematic diagram of the material morphology of ferric phosphate material processed in a conventional rotary kiln (45 min).

[0037] Figure 12 A schematic diagram of the material morphology of ferric phosphate material processed in a conventional rotary kiln (60 min).

[0038] Figure 13 A schematic diagram of the material morphology of ferric phosphate material processed in a conventional rotary kiln (75 min).

[0039] Figure 14 A schematic diagram of the material morphology of ferric phosphate material processed in a conventional rotary kiln (90 min).

[0040] Figure 15 This is a schematic diagram of the overall structure of the device in this invention.

[0041] Figure 16 This is a schematic diagram of the air inlet box of the present invention.

[0042] Figure 17 This is a schematic diagram of a mating structure between the inner and outer cylinders.

[0043] In the above diagram, the meanings of each label are as follows: 1. Outer cylinder; 2. Inner cylinder; 201. Fluidized rotary chamber; 202. Support component; 3. Air chamber; 4. Insulation structure; 5. Feeding structure; 6. Vent; 7. Sealing structure; 8. Rotary bearing structure; 9. Transmission structure; 10. Discharge structure; 11. Air inlet box structure; 12. Telescopic clamping shaft; 13. Elastic clamping component. Detailed Implementation

[0044] The following description, in conjunction with the accompanying drawings and specific embodiments, further illustrates this embodiment.

[0045] In view of the problems that existing technologies for drying wet ferric phosphate materials result in clumping and sticking to the walls, leading to poor drying effects, or even furnace blockage, shutdown, and frequent cleaning, the following embodiments optimize and overcome the defects of the existing technologies.

[0046] Example 1 This embodiment provides a composite drying method for efficiently preparing high-quality ferric phosphate, including: S01: Place the ferric phosphate material in a set drying environment and perform a fluidized-rotary combined drying process to reduce the moisture content of the ferric phosphate material to below the set value.

[0047] S02: The fluidization-rotation composite drying process includes introducing a fluidizing gas flow to make the iron phosphate material enter the fluidized state, and synchronous rotation to make the iron phosphate material move along the conveying direction.

[0048] The composite drying method disclosed in this embodiment fills the space between the iron phosphate material beds with gas under the action of hot airflow, breaking up the liquid bridges formed between particles due to surface moisture. This prevents the moist iron phosphate material from clumping and adhering to the inner wall of the equipment during the drying process. The gas-solid contact area is huge and constantly renewed, resulting in a uniform temperature distribution within the bed. As drying proceeds, the material gradually changes from a highly moist, agglomerated state to a dispersed, suspended state, ultimately achieving efficient heat and mass transfer. Simultaneously, the rotational motion of the equipment causes the iron phosphate material in the bed to be lifted, stirred, and slid down by the inner cylinder wall. The inclined cylinder, in one cycle of stirring and sliding, causes the iron phosphate material to shift towards the lower end. This cyclical movement allows the material to move continuously along the conveying direction.

[0049] The drying process for wet ferric phosphate materials has been simplified, thus improving processing efficiency.

[0050] In this method, to better dry ferric phosphate materials, the drying environment is set. One feasible option is proposed here: during the fluidized-rotary combined drying process, ferric phosphate materials with a moisture content of 20%~60% are placed in a rotating combined fluidized bed, and an airflow of 60℃~600℃ is introduced for drying, reducing the moisture content of the ferric phosphate materials to 0.5%~25%. Using this scheme, ferric phosphate materials with high moisture content can be processed while avoiding adhesion. Furthermore, during drying, the drying speed and effect can be controlled by adjusting the temperature of the introduced airflow; that is, the higher the temperature of the introduced airflow, the faster the dehydration and drying speed of the ferric phosphate materials.

[0051] In some solutions, the airflow velocity in the fluidized bed can be controlled by adjusting the airflow rate, taking into account the moisture content or surface adhesion of the ferric phosphate material, to achieve the optimal fluidization state and prevent clumping and adhesion to the walls. During operation, the airflow can be adjusted manually or automatically using valve groups, and the fluidization state of the ferric phosphate material in the fluidized rotary chamber can be observed through an internal video display or an observation window. Timely flow rate adjustments are made to ensure the ferric phosphate material remains in a suitable fluidized state, thus optimizing the fluidized rotary composite drying process.

[0052] When implemented according to this solution, significant improvements were achieved compared to traditional technical solutions.

[0053] Here are some actual experimental cases for comparison, and the data in Table 1 below is as follows: Using the conventional rotary kiln drying process as a comparative example of the fluidized rotary composite drying process disclosed in this embodiment, the following data on changes in moisture content, material temperature, and material morphology were obtained.

[0054] Table 1 Comparison of Ferric Phosphate Processing Data by Rotary Furnace-Fluidized Rotary Furnace

[0055] Actual material images for the above seven examples are provided simultaneously; please refer to the instruction manual for details. Figures 1-14 .

[0056] From Table 1 and Appendix Figures 1-14 The records show a comparison of the performance of conventional externally heated rotary kilns and fluidized bed rotary kilns in processing ferric phosphate materials, as follows: 1. Experimental Background Experimental materials: the same ferric sulfate filter cake dispersion.

[0057] Experimental conditions: Both experimental furnaces were heated to 300℃ and held at that temperature for 2 hours before feeding. The experiment lasted for 90 minutes.

[0058] Comparison dimensions: moisture content (total water), material temperature, and material morphology inside the furnace (refer to images 1-7 and 1A-7A).

[0059] 2. Detailed comparative analysis (1) Moisture removal efficiency (drying rate) Using the conventional rotary kiln drying process as a comparative example of the fluidized rotary composite drying process disclosed in this embodiment, the following data on the change in moisture content were obtained.

[0060] Table 2 Comparison of moisture content between conventional rotary kiln drying process and fluidized rotary kiln combined drying process

[0061] Conclusion: The drying efficiency of the fluidized rotary kiln is significantly higher than that of the ordinary rotary kiln.

[0062] (2) Material heating rate (heat transfer efficiency) By comparing the drying process of a conventional rotary kiln with the fluidized rotary kiln combined drying process disclosed in this embodiment, the following data on the change in material temperature were obtained.

[0063] Table 3 Comparison of material temperatures between conventional rotary kilns and fluidized rotary kilns

[0064] Conclusion: The material in the fluidized rotary kiln heats up extremely quickly, while the material in the ordinary rotary kiln heats up slowly and is severely underheated.

[0065] (3) Material morphology and adhesion within the furnace (based on...) Figures 1-14 contrast) Fluidized rotary kiln (corresponding to picture 1-) Figure 7 ): 15 minutes after feeding (Image 2): The material is well dispersed and there is no adhesion between the material and the furnace tube.

[0066] Experimental process (30-90 minutes): As time went on, the particle size gradually decreased, and the fluidized dispersion state was maintained without agglomeration.

[0067] Ordinary externally heated rotary kiln (corresponding to) Figures 8-14 ): Feeding time 15 minutes ( Figure 9 ): The material has clumped together and partially adhered to the furnace tube wall.

[0068] In the early stage of the experiment (15-60 minutes): the particles remained in a sticky and clumped state, hindering heat exchange.

[0069] Later stage of the experiment (75 minutes) Figure 13 The material did not begin to disperse until the 75th minute when sampling was taken. This indicates that the thermal efficiency was extremely low in the first 60 minutes, with a significant amount of time spent overcoming the thermal resistance within the agglomerates and clumps.

[0070] Conclusion: Fluidized rotary kilns can effectively disperse materials and prevent them from sticking to the walls; ordinary rotary kilns suffer from severe agglomeration and wall-sticking. (4) Overall Conclusion By comparing the experimental data from 90 minutes at a constant temperature of 300℃, the following key conclusions can be drawn: 1. Heat transfer and drying performance: The fluidized rotary kiln has significant advantages. It raises the material temperature to 181℃ within 90 minutes and reduces the moisture content to 11.26%. In contrast, a conventional rotary kiln only reaches a material temperature of 75℃, with a moisture content still as high as 30.66%, resulting in extremely poor drying performance.

[0071] 2. Anti-sticking and dispersibility: The fluidized rotary kiln utilizes fluidization technology to rapidly disperse materials upon entering the kiln body, keeping them in a loose state and preventing wet materials from adhering to the kiln wall (i.e., the "sticking" phenomenon). Ordinary rotary kilns, on the other hand, are severely hampered by material agglomeration and sticking to the wall, resulting in ineffective heat transfer to the materials and creating an unfavorable "externally hot and internally cold" operating condition.

[0072] 3. Process adaptability: For ferric phosphate materials with high moisture content and viscosity, fluidized rotary kiln is a better choice, which can significantly shorten drying time, improve production efficiency, and avoid equipment failure and cleaning work caused by material adhesion.

[0073] Example 2 The above embodiment 1 describes the method of fluidized rotary combined drying. This embodiment also provides processing equipment for performing fluidized rotary drying.

[0074] like Figure 15 , Figure 16 and Figure 17 As shown, a composite drying device for the efficient preparation of high-quality ferric phosphate is used to realize the above-mentioned composite drying method. It includes an outer cylinder 1 and an inner cylinder 2. An air cavity 3 is formed between the outer cylinder 1 and the inner cylinder 2. The air cavity 3 is connected to an external air source and is used to guide the airflow through the inner cylinder 2 into the fluidized rotary chamber 201 on the inner side. The composite drying device also includes a power component for driving the outer cylinder 1 and the inner cylinder 2 to rotate synchronously.

[0075] The processing equipment disclosed in this embodiment allows an external air source to pass through the inner cylinder 2 and enter the fluidizing rotary chamber 201, causing the ferric phosphate material to float and not adhere to the inner wall of the equipment. It is then dried under the action of the airflow. At the same time, the outer cylinder 1 and the inner cylinder 2 rotate synchronously to guide the ferric phosphate material to move in a set direction. After reaching the feeding position, it is automatically fed. The whole process is faster and more efficient.

[0076] The working principle of the equipment disclosed in this embodiment is as follows: the material enters the fluidized rotary chamber 201 inside the rotating inner cylinder 2, and hot drying air is introduced from the inlet of the air chamber 3. The hot air flows out from the holes of the airflow distribution plate, and the hot air forms a local fluidized state. The airflow carries the particles and passes through the material layer, breaking the liquid bridges formed between the particles due to surface wetting, avoiding the aggregation of small particles into large clumps, and at the same time keeping the material particles in a dispersed individual state to prevent the material from sticking to the wall. The rotation of the cylinder drives the material to turn over and gradually move along the set direction. That is, when there is a certain inclination angle, it gradually moves and is conveyed along the axial direction of the rotating part, thus taking into account both the drying reaction treatment and continuous conveying requirements of the material.

[0077] Preferably, in this embodiment, a heat insulation structure 4 is also provided on the outside of the outer cylinder 1. Specifically, the heat insulation structure 4 surrounds the outside of the outer cylinder 1 to form a wrap, and a heat insulation gap is formed between the two. A heat insulation medium can be placed in the heat insulation gap.

[0078] The ferric phosphate material floats and tumbles inside the inner cylinder 2 to achieve the drying process. The structure of the inner cylinder 2 can be constructed in various forms and is not limited to one. This embodiment optimizes and adopts one feasible option: the inner cylinder 2 includes several fluidizing gas distribution plates, which are connected end to end to form a circular or polygonal inner cylinder 2. When the above scheme is adopted, the fluidizing gas distribution plate can be a straight plate or an arc plate. Adjacent fluidizing gas distribution plates are spliced ​​together to form the inner cylinder 2. The inner cylinder 2 and the outer cylinder 1 are coaxially arranged and rotate synchronously. When the power component applies a driving force to the outer cylinder 1, the outer cylinder 1 drives the inner cylinder 2 to rotate synchronously, thereby causing the ferric phosphate material in the fluidized rotating chamber 201 to tumble and remain in a floating state, thus enabling drying.

[0079] The inner cylinder 2 and the outer cylinder 1 can be synchronously connected and fitted through various structures, and are not limited to one. This embodiment optimizes and adopts one feasible option: an annular gap is formed between the inner cylinder 2 and the outer cylinder 1, and several support members 202 are provided within the annular gap to divide the annular gap into several air cavities 3. When adopting the above scheme, the annular gap can be a uniform circular gap, a polygonal gap, or a gap enclosed by a polygon and a circle.

[0080] In some designs, the support member 202 includes structures such as a T-shaped support plate and an L-shaped support plate, which are fixed between the outer cylinder 1 and the inner cylinder 2 by means of welding, riveting, bolting, etc.

[0081] In some other schemes, a groove can be made on the outer cylinder 1, and a fluidizing gas distribution plate can be set at the groove. At the same time, a gap is formed between the fluidizing gas distribution plate and the groove to form an air cavity. The external gas source enters the groove through the gap and then enters the internal fluidized rotary composite cavity through the fluidizing gas distribution plate to achieve the drying treatment of iron phosphate material.

[0082] In some other designs, the support member 202 can be integrally formed with the inner cylinder 2 and then connected to the outer cylinder 1. With this structure, the support member 202 can be connected to the outer cylinder 1 using fasteners.

[0083] The air cavity 3 is connected to an external air source to obtain fluidized gas. The connection structure can be constructed in various forms and is not limited to a single one. This embodiment optimizes and adopts one feasible option: an air inlet box structure 11 is provided at the air cavity 3. The air inlet box structure 11 is connected to the external air source and forms a vent 6 that connects to the air inlet cavity 3. When the vent 6 is connected to the air cavity 3, the gas from the external air source enters the air cavity 3 through the vent 6. With the above scheme, the air inlet box structure 11 and the air cavity 3 are in sliding fit, and the mating surface is airtight. When the outer cylinder 1 and the inner cylinder 2 rotate, they are in sliding fit and can switch between connecting to the air cavity 3 connected to the air inlet box structure 11. Generally, rotating to the lowermost air cavity 3 will connect to the air inlet box structure 11 and obtain fluidized gas.

[0084] The air inlet box structure 11 is attached to the outer cylinder 1 and the inner cylinder 2 to supply air. Its structure can adopt various schemes; this embodiment optimizes and adopts one feasible option: the air inlet box structure 11 has several vents 6 spaced along its circumference, and the layout of the vents 6 corresponds to the air cavity 3. When adopting the above scheme, the number of vents 6 can be single or multiple. When using a single vent 6, as the outer cylinder 1 and the inner cylinder 2 rotate, the single vent 6 connects to the air cavity 3 one by one; when using multiple vents 6, as the outer cylinder 1 and the inner cylinder 2 rotate, the air cavity 3 passes through and connects to the vents 6 sequentially.

[0085] The outer cylinder 1 and inner cylinder 2 can be fitted in various ways, but to ensure air supply and maintain sealing during rotation, this embodiment optimizes the design and adopts one feasible option: the end faces of the outer cylinder 1 and inner cylinder 2 are flush to form a smooth contact surface, and the air inlet box is attached to the smooth contact surface to form a contact sealing structure 7; the contact sealing structure 7 includes a ventilation surface that is attached to the smooth contact surface, and the ventilation port 6 is located on the ventilation surface and is switched to communicate with the air cavity 3. When the above scheme is adopted, the cross-section of the ventilation port 6 is generally less than or equal to the cross-section of the air cavity 3, but when the distance between adjacent air cavities 3 is greater than a certain extent, the cross-section of the ventilation port 6 can also be greater than the cross-section of the air cavity 3 to avoid air leakage when the air cavity 3 is switched to communicate with the ventilation port 6.

[0086] To maintain better sealing and prevent air leakage when the vent 6 is connected to the air cavity 3, or to prevent air leakage when the air cavity 3 switches connections with the vent 6, this embodiment optimizes the process and adopts one feasible option: sealing structures 7 are formed on both sides of the vent 6, and the length of the sealing structure 7 is greater than or equal to the air inlet length of the air cavity 3 on its circumference. When adopting the above solution, the sealing structure 7 can be constructed as a sealing strip, sealing baffle, or sealing block, integrally formed with the air inlet box structure 11, or connected and fixed to the air inlet box structure 11 using fasteners.

[0087] Preferably, in this embodiment, the air inlet box structure 11 is tightly fitted to the contact surface via a clamping structure. The clamping structure includes a telescopic clamping shaft 12 and an elastic clamping member 13 sleeved on the telescopic clamping shaft 12. The elastic clamping member 13 provides elastic force, and the telescopic clamping shaft 12 pushes the air inlet box structure 11 axially and clamps it against the contact surface.

[0088] The equipment provided by this invention can connect to an external feeding mechanism and subsequent processing mechanism during material feeding and discharging, achieving continuous automatic feeding and discharging. Specifically, this embodiment optimizes and adopts one feasible option: the outer cylinder 1 is connected to a feeding structure 5, which includes a feeding channel extending into the fluidizing rotary chamber 201; it also includes a discharging structure, which includes a discharging channel located at the discharging end of the outer cylinder 1. When adopting the above scheme, the feeding structure 5 may include a feeding hopper, and the discharging structure 10 may include a discharging hopper.

[0089] In this embodiment, the power component includes a driver and a transmission structure 9. The driver can be a motor, and the transmission structure 9 can be a belt drive, chain drive, or gear drive, etc. When the motor rotates, the outer cylinder 1 and the inner cylinder 2 can be driven to rotate synchronously through the transmission structure 9. In order to achieve better rotation of the inner cylinder 2 and the outer cylinder 1, a slewing bearing structure 8 is provided at the outer cylinder 1. The slewing bearing structure 8 includes a support wheel, etc.

[0090] The above are the embodiments listed in this example; however, this example is not limited to the optional embodiments described above; those skilled in the art can arbitrarily combine the above methods to obtain other various embodiments; anyone can derive other various forms of embodiments under the guidance of this example. The above specific embodiments should not be construed as limiting the scope of protection of this example; the scope of protection of this example should be determined by the claims.

Claims

1. A composite drying method for efficiently preparing high-quality ferric phosphate, characterized in that, include: Moist ferric phosphate material is placed in a set drying environment, and the moisture content of the ferric phosphate material is reduced to below the set value by performing a fluidization-rotation combined drying process. The fluidized-rotary composite drying process includes introducing a fluidizing gas flow to fluidize the iron phosphate material, while simultaneously utilizing the rotational motion of the equipment to continuously move the material along the conveying direction.

2. The composite drying method for efficiently preparing high-quality ferric phosphate according to claim 1, characterized in that: During the fluidized-rotary combined drying process, ferric phosphate material with a moisture content of 20% to 60% is placed in a rotating fluidized rotary chamber, and an airflow of 60℃ to 600℃ is introduced for drying, reducing the moisture content of the ferric phosphate material to 0.5% to 25%.

3. A high-efficiency composite drying device for preparing high-quality ferric phosphate, used to implement the composite drying method described in claim 1 or 2, characterized in that: The equipment includes an outer cylinder (1) and an inner cylinder (2), with an air cavity (3) formed between the outer cylinder (1) and the inner cylinder (2). The air cavity (3) is connected to an external air source and is used to guide the airflow through the inner cylinder (2) into the fluidized rotary chamber (201) on the inside. The composite drying equipment also includes a power component for driving the outer cylinder (1) and the inner cylinder (2) to rotate synchronously.

4. The composite drying equipment for high-efficiency preparation of high-quality ferric phosphate according to claim 3, characterized in that: The inner cylinder (2) includes several fluidized gas distribution plates, which are connected end to end to form a circular inner cylinder (2) or a polygonal inner cylinder (2).

5. The composite drying equipment for efficiently preparing high-quality ferric phosphate according to claim 3 or 4, characterized in that: An annular gap is formed between the inner cylinder (2) and the outer cylinder (1), and a number of support members (202) are provided in the annular gap to divide the annular gap into a number of air cavities (3).

6. The composite drying equipment for high-efficiency preparation of high-quality ferric phosphate according to claim 3, characterized in that: An air inlet box structure (11) is provided at the air cavity (3). The air inlet box structure (11) is connected to an external air source and forms an air vent (6) that is connected to the air inlet cavity (3). When the air vent (6) is connected to the air cavity (3), the gas from the external air source enters the air cavity (3) through the air vent (6).

7. The composite drying equipment for efficiently preparing high-quality ferric phosphate according to claim 6, characterized in that: The air inlet box structure (11) has several air vents (6) spaced along the circumference, and the layout of the air vents (6) corresponds to the air cavity (3).

8. The composite drying equipment for efficiently preparing high-quality ferric phosphate according to claim 6 or 7, characterized in that: The outer cylinder (1) and the inner cylinder (2) are flush with each other to form a contact light surface. The air inlet box is attached to the contact light surface to form a contact sealing structure (7). The contact sealing structure (7) includes a ventilation surface that is attached to the contact light surface. The ventilation port (6) is located on the ventilation surface and is switched to communicate with the air cavity (3).

9. The composite drying equipment for high-efficiency preparation of high-quality ferric phosphate according to claim 3, characterized in that: The outer cylinder (1) is connected to a feeding structure (5), which includes a feeding channel extending into the fluidized rotary chamber (201); it also includes a discharge structure, which includes a discharge channel located at the discharge end of the outer cylinder (1).

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