A lithium iron phosphate continuous dynamic carbonization reduction roasting device and a roasting method
By using a continuous dynamic carbonization reduction roasting device and method for lithium iron phosphate, the discontinuity and adhesion problems in the solid-phase lithium iron phosphate production were solved, achieving efficient and stable lithium iron phosphate production and improving product quality and yield.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- LIAONING DONGDA POWDER ENG TECH CO LTD
- Filing Date
- 2023-04-07
- Publication Date
- 2026-05-22
AI Technical Summary
The existing solid-phase lithium iron phosphate production process suffers from problems such as intermittent and discontinuous production, easy adhesion of materials during high-temperature sintering, wear and tear, and product contamination by impurities, resulting in unstable product quality.
The continuous dynamic carbonization reduction roasting device of lithium iron phosphate is adopted, including spray drying, decoking carbonization, and reduction roasting units, to achieve continuous dynamic roasting of materials, avoid sticking and wear, and ensure stable product quality.
It enables continuous production of lithium iron phosphate, avoids sticking and wear during roasting, improves product quality stability, reduces energy consumption, and increases the annual output per furnace.
Smart Images
Figure CN116379772B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of new energy battery technology, and in particular to a continuous dynamic carbonization reduction roasting apparatus and roasting method for lithium iron phosphate. Background Technology
[0002] Lithium-ion batteries are a type of energy storage battery with great development potential. Their main technological requirements are improving performance indicators such as energy density, ensuring product stability, and reducing production costs. The performance and price of lithium-ion batteries mainly depend on the performance of the cathode material. Lithium iron phosphate (LFP) is the main cathode material for lithium-ion batteries, and its crystal form, density, and other performance indicators mainly depend on its preparation process and key furnace equipment. The preparation processes for LFP mainly include solid-phase and liquid-phase methods. The advantages of liquid-phase synthesis of LFP are easy control of crystal form and particle size, uniform phase, small powder particle size, and a simple process. However, it requires high-pressure equipment, resulting in high equipment investment and complex processes. In contrast, the solid-phase method has advantages such as simple equipment and processes, easy operation, easy control of preparation conditions, lower cost, and suitability for industrial production. Therefore, the solid-phase method is widely used in production practice. Currently, the main process flow of the solid-phase method includes: spray drying granulation - cooling and loading - high-temperature sintering - cooling and crushing - lithium iron phosphate product, and it is a periodic, intermittent, and discontinuous production process. In the existing technology, the main drawback of the solid-state process is that the granulated particles need to be cooled before being loaded into saggers and then into the roller kiln, which leads to the separation of drying granulation and high-temperature reduction sintering; while the shelf-type layered arrangement of saggers requires the material in the saggers to be sintered at high temperature in the roller kiln.
[0003] To address the main shortcomings of the solid-state process, application number 201710767835.3 proposes a process and apparatus for preparing lithium iron phosphate cathode materials, using a screw reactor instead of traditional intermittent heating equipment (kiln) for high-temperature sintering of lithium iron phosphate raw materials. This solves the problems of intermittent production and uneven heating of materials to some extent, and successfully eliminates the use of saggers. However, adhesion still occurs during sintering, and crushing and homogenization are still required after sintering. Application number 202211099991.4 proposes a method for preparing lithium iron phosphate by sintering in an atmosphere rotary kiln, using an atmosphere rotary kiln instead of a roller furnace to produce lithium iron phosphate, eliminating the use of saggers and achieving dynamic calcination of materials. However, the material particles contain organic matter, which will adhere in the rotary kiln, and crushing is still required after sintering. Patent number 202122797353.7 proposes a rotary sintering apparatus for preparing lithium iron phosphate materials, eliminating the use of graphite saggers. However, this device has a large contact surface with the material, and under high temperatures, continuous wear generates impurities that contaminate the product, leading to unstable product quality. Patent No. 201910888014.4 proposes a low-cost method for preparing lithium iron phosphate using phosphoric acid, iron filings, ferric oxide, and lithium carbonate as raw materials. This method uses a roller furnace for calcination, which suffers from material adhesion during the sintering process. Patent No. 202111676130.3 describes a lithium iron phosphate production equipment and its preparation method, eliminating the need for graphite saggers; however, this equipment results in a discontinuous production process.
[0004] Therefore, the aforementioned technical issues still need to be addressed. Summary of the Invention
[0005] The purpose of this invention is to provide a continuous dynamic carbonization reduction roasting apparatus and roasting method for lithium iron phosphate, so as to achieve continuous production and dynamic roasting, avoid adhesion during roasting and breakage and homogenization after sintering, avoid wear and impurity contamination of products under high temperature conditions, and achieve the quality stability of lithium iron phosphate.
[0006] To address the aforementioned technical problems, the embodiments of the present invention provide the following technical solutions:
[0007] The first aspect of this invention provides a continuous dynamic carbonization reduction roasting apparatus for lithium iron phosphate, comprising a raw material pool, a spray drying device connected to the raw material pool via a first pipeline, a second pipeline connected to the spray drying device, a first cyclone bag filter connected to the end of the second pipeline away from the spray drying device, a feeding device connected to the bottom of the first cyclone bag filter, a decoking carbonization device connected to the bottom of the feeding device, a third pipeline connected to the decoking carbonization device, and a second cyclone bag filter connected to the end of the third pipeline away from the decoking carbonization device. The equipment is also connected to a fourth pipeline, and a heating device is connected to the end of the fourth pipeline on the side away from the feeding device. A fifth pipeline is also connected to the heating device, and a tar removal device is connected to the end of the fifth pipeline on the side away from the heating device. The tar removal device and the second cyclone bag filter are connected through a tar removal pipeline. The second cyclone bag filter is also connected to a primary reduction roasting unit. The primary reduction roasting unit is connected to a secondary reduction roasting unit. The secondary reduction roasting unit and the fifth pipeline are connected through a sixth pipeline, and a nitrogen source is connected to the sixth pipeline.
[0008] Furthermore, an air heating device for heating the raw material is connected to the first pipeline near the spray drying equipment.
[0009] A slurry pump is also installed on the first pipeline.
[0010] Furthermore, the sixth pipelines located on both sides of the nitrogen source are respectively equipped with first control valves for controlling the direction and flow rate of nitrogen.
[0011] The tar removal equipment is also connected to a seventh pipeline, and the end of the seventh pipeline, which is away from the tar removal equipment, is connected to a tar storage tank.
[0012] Furthermore, the first cyclone bag filter is also connected to an eighth pipeline, on which a first induced draft fan is installed;
[0013] A third induced draft fan is installed on the decoking pipeline.
[0014] Furthermore, the primary reduction calcination unit includes:
[0015] The first feeding component is connected to the second cyclone bag filter.
[0016] The first reduction roasting furnace is connected to the first feeding component;
[0017] The ninth pipeline is connected to the first reduction roasting furnace;
[0018] The tenth pipeline is connected to both the first reduction roasting furnace and the secondary reduction roasting unit;
[0019] A second control valve is installed on the tenth pipeline and controls the gas flow rate in the tenth pipeline;
[0020] Among them, a temperature regulating device, a third cyclone bag filter and a second induced draft fan are sequentially installed on the ninth pipeline near the first reduction roasting furnace.
[0021] Furthermore, the secondary reduction calcination unit includes:
[0022] The second reduction roasting furnace is connected to both the first reduction roasting furnace and the tenth pipeline located away from the first reduction roasting furnace.
[0023] The second feeding component is connected to the second reduction roasting furnace;
[0024] The cooling rotary kiln is connected to the second feeding component.
[0025] A second aspect of the present invention provides a continuous dynamic carbonization reduction roasting method for lithium iron phosphate, comprising:
[0026] After mixing ferric phosphate, lithium carbonate and glucose, deionized water is added for batching. After mixing and crystallizing with deionized water as a dispersant, the mixture is milled to obtain a slurry. The slurry is pumped into a spray drying device and simultaneously exchanged with an air heating device at 250℃-280℃ to form powder particles.
[0027] The powdered particles, heated to 130℃~140℃, are fed into the decoking and carbonization equipment through a first cyclone bag filter and a feeding device. They are mixed with nitrogen gas at 450℃-650℃ and heated to 450℃~550℃ within 3-5 hours. The glucose in the powdered particles forms water, tar, and carbon coated on the surface of the solid powder, thus completing the decoking and carbonization process.
[0028] The material that has completed decoking and carbonization enters the second cyclone bag filter in the form of gas phase and solid phase for gas-solid separation. The separated gas phase material enters the detarting equipment for detaring. The obtained nitrogen is mixed with nitrogen supplemented from the nitrogen source and then enters the heating equipment before entering the feeding equipment.
[0029] The solid material obtained from the gas-solid separation enters the primary reduction roasting unit and undergoes dynamic roasting in a spiral state under a nitrogen protective atmosphere. It is then pre-reduced by heating to 650-780℃ for 1-2 hours. The pre-reduced material enters the secondary reduction roasting unit, where it undergoes dynamic roasting in a spiral motion under a nitrogen protective atmosphere at 650-780℃. The process of reducing the valence state of iron and removing CO2 by converting lithium carbonate to lithium oxide takes place for 3-5 hours, resulting in a single-phase lithium iron phosphate material.
[0030] Furthermore, the mass ratio of iron phosphate, lithium carbonate, and glucose is 1:0.24~0.26:0.12~0.14;
[0031] Deionized water accounts for 60% to 80% of the total mass.
[0032] Furthermore, the gaseous materials obtained from the gas-solid separation are water vapor and tar, as well as nitrogen as a protective gas.
[0033] Furthermore, after the nitrogen in the nitrogen source enters the second reduction roasting furnace, it enters the first reduction roasting furnace through the tenth pipeline, and then exits through the ninth pipeline in sequence from the temperature control equipment, the third cyclone bag filter, and the second induced draft fan.
[0034] The solid material obtained from the gas-solid separation enters the first reduction roasting furnace through the first feeding element, then enters the second reduction roasting furnace, and finally enters the cooling rotary kiln through the second feeding element.
[0035] Compared to existing technologies, the lithium iron phosphate continuous dynamic carbonization reduction roasting apparatus provided in the first aspect of this invention involves the following steps: Raw materials from the raw material pool enter a spray drying device through a first pipeline, then a first cyclone bag filter through a second pipeline, and finally a decoking carbonization device through a feeding device. The material then enters a second cyclone bag filter through a third pipeline, and subsequently enters a primary reduction roasting unit and a secondary reduction roasting unit. Nitrogen from the nitrogen source can enter either a fifth pipeline or the secondary reduction roasting unit, depending on the actual situation. After entering the fifth pipeline, the nitrogen enters the heating device along with the material, then enters the feeding device through a fourth pipeline, and finally enters the decoking carbonization device. The nitrogen from the nitrogen source, along with the gas in the material, enters the secondary reduction roasting unit, then the primary reduction roasting unit, and is discharged from the primary reduction roasting unit. Therefore, the continuous dynamic carbonization reduction roasting device for lithium iron phosphate achieves continuous production; the material moves within the device, achieving dynamic roasting, and a separate decoking carbonization device is provided to avoid adhesion during roasting and to prevent breakage and homogenization after sintering; the material passes through a primary reduction roasting unit and a secondary reduction roasting unit, avoiding wear and impurity contamination of the product at high temperatures, thus achieving the quality stability of lithium iron phosphate.
[0036] The continuous dynamic carbonization reduction roasting method for lithium iron phosphate provided in the second aspect of the present invention has the same technical effect as the continuous dynamic carbonization reduction roasting apparatus for lithium iron phosphate. Attached Figure Description
[0037] The above and other objects, features, and advantages of exemplary embodiments of the present invention will become readily apparent upon reading the following detailed description with reference to the accompanying drawings. In the drawings, several embodiments of the invention are illustrated by way of example and not limitation, with the same or corresponding reference numerals denoteing the same or corresponding parts, wherein:
[0038] Figure 1 A schematic diagram of a continuous dynamic carbonization reduction roasting apparatus for lithium iron phosphate is shown.
[0039] Figure 2 A schematic diagram of a continuous dynamic carbonization reduction roasting method for lithium iron phosphate is shown.
[0040] Explanation of icon numbers:
[0041] 1. Raw material tank; 11. First pipeline; 12. Slurry pump;
[0042] 2. Decoking and carbonization equipment; 21. Third pipeline;
[0043] 3. Feeding equipment;
[0044] 4. First cyclone bag filter dust collector; 41. Eighth pipeline; 42. First induced draft fan;
[0045] 5. Second cyclone bag filter dust collector; 51. Coke removal pipeline; 52. Third induced draft fan;
[0046] 6. Primary reduction roasting unit; 61. First feeding component; 62. First reduction roasting furnace; 63. Ninth pipeline; 64. Temperature control equipment; 65. Third cyclone bag filter dust collector; 66. Second induced draft fan; 67. Tenth pipeline; 68. Second control valve;
[0047] 7. Secondary reduction roasting unit; 71. Second reduction roasting furnace; 72. Second feeding component; 73. Cooling rotary kiln;
[0048] 8. Nitrogen source; 81. Sixth pipeline; 82. First control valve;
[0049] 9. Heating equipment; 91. Fourth pipeline;
[0050] 10. Tar removal equipment; 101. Seventh pipeline; 102. Tar storage tank; 103. Fifth pipeline;
[0051] 20. Spray drying equipment; 201. Second pipeline;
[0052] 30. Air heating equipment. Detailed Implementation
[0053] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Unless otherwise specified, the techniques used in the embodiments are conventional means well known to those skilled in the art.
[0054] It should be noted that, unless otherwise stated, the technical or scientific terms used in this invention should be understood in their ordinary sense by those skilled in the art. In this document, relational terms such as “first” and “second” are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The terms “connection,” “linked,” etc., should be interpreted broadly, for example, referring to a fixed connection, a detachable connection, or an integral connection; a mechanical connection or an electrical connection; a direct connection or an indirect connection via an intermediate medium. The terms “comprising,” “including,” or any other variations thereof are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase “comprising…” does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0055] This invention provides a continuous dynamic carbonization reduction roasting apparatus for lithium iron phosphate, such as... Figure 1As shown, the lithium iron phosphate continuous dynamic carbonization reduction roasting device includes a raw material pool 1. The raw material pool 1 is connected to a spray drying device 20 via a first pipeline 11. The spray drying device 20 is connected to a second pipeline 201. The end of the second pipeline 201 away from the spray drying device 20 is connected to a first cyclone bag filter 4. The bottom of the first cyclone bag filter 4 is connected to a feeding device 3. The bottom of the feeding device 3 is connected to a decoking carbonization device 2. The decoking carbonization device 2 is connected to a third pipeline 21. The end of the third pipeline 21 away from the decoking carbonization device 2 is connected to a second cyclone bag filter 5. The feeding device 3 is also connected to... A fourth pipe 91 is connected to the end of the fourth pipe 91, which is away from the feeding device 3. A heating device 9 is connected to the end of the fourth pipe 9, which is away from the feeding device 3. A fifth pipe 103 is also connected to the heating device 9. A tar removal device 10 is connected to the end of the fifth pipe 103, which is away from the heating device 9. The tar removal device 10 and the second cyclone bag filter 5 are connected to each other through a tar removal pipe 51. The second cyclone bag filter 5 is also connected to a primary reduction roasting unit 6. The primary reduction roasting unit 6 is connected to a secondary reduction roasting unit 7. The secondary reduction roasting unit 7 and the fifth pipe 103 are connected through a sixth pipe 81. A nitrogen source 8 is connected to the sixth pipe 81.
[0056] In this embodiment, the raw materials in the raw material pool 1 enter the spray drying equipment 20 through the first pipeline 11, enter the first cyclone bag filter 4 through the second pipeline 201, and then enter the decoking and carbonization equipment 2 through the feeding equipment 3. The material enters the second cyclone bag filter 5 through the third pipeline 21, and then sequentially enters the primary reduction roasting unit 6 and the secondary reduction roasting unit 7. The nitrogen in the nitrogen source 8 can enter the fifth pipeline 103 or the secondary reduction roasting unit 7 according to the actual situation. After entering the fifth pipeline 103, the nitrogen enters the heating equipment 9 together with the material, and then enters the feeding equipment 3 through the fourth pipeline 91, and then enters the decoking and carbonization equipment 2. The nitrogen in the nitrogen source 8 and the gas in the material enter the secondary reduction roasting unit 7 together, and then enter the primary reduction roasting unit 6, and is discharged from the primary reduction roasting unit 6. Therefore, the continuous dynamic carbonization reduction roasting device for lithium iron phosphate achieves continuous production; the material moves within the device, achieving dynamic roasting, and a separate decoking carbonization device 2 is provided to avoid adhesion during roasting and to prevent breakage and homogenization after sintering; the material passes through the primary reduction roasting unit 6 and the secondary reduction roasting unit 7, avoiding wear and impurity contamination of the product under high temperature conditions, thus achieving the quality stability of lithium iron phosphate.
[0057] In a specific embodiment, such as Figure 1 As shown, an air heating device 30 for heating the raw material is connected to the first pipe 11 near the spray drying device 20.
[0058] A slurry pump 12 is also installed on the first pipeline 11.
[0059] In this embodiment, the raw material is located in the raw material pool 1 and enters the spray drying equipment 20 through the first pipeline 11 under the action of the slurry pump 12. At the same time, the target heat in the air heating equipment 30 enters the spray drying equipment 20 through the first pipeline 11. The raw material is heated by the spray drying equipment 20 and the target heat to form powder particles.
[0060] More specifically, the raw materials are mixed and stirred in raw material tank 1, and deionized water is added as a dispersant for mixing and crystallization. After mixing and crystallization, the mixture is then machine-milled to obtain a slurry.
[0061] In a specific embodiment, such as Figure 1 As shown, the sixth pipeline 81 located on both sides of the nitrogen source 8 is equipped with a first control valve 82 for controlling the direction and flow rate of nitrogen.
[0062] The tar removal equipment 10 is also connected to a seventh pipeline 101, and the end of the seventh pipeline 101 away from the tar removal equipment 10 is connected to a tar storage tank 102.
[0063] In this embodiment, when the first control valve 82 near the fifth pipeline 103 is closed and the first control valve 82 near the secondary reduction roasting unit 7 is opened, nitrogen from the nitrogen source 8 enters the secondary reduction roasting unit 7 as a protective atmosphere through the sixth pipeline 81. Meanwhile, CO2 and water vapor from the secondary reduction roasting unit 7 enter the primary reduction roasting unit 6 along with the nitrogen, and the gaseous material from the primary reduction roasting unit 6 is discharged from the primary reduction roasting unit 6.
[0064] When the first control valve 82 near the fifth pipeline 103 is opened and the first control valve 82 near the secondary reduction roasting unit 7 is closed, the nitrogen in the nitrogen source 8 enters the fifth pipeline 103 as a protective atmosphere through the sixth pipeline 81 and then enters the heating device 9.
[0065] When the first control valve 82 near the fifth pipeline 103 is opened, and the first control valve 82 near the secondary reduction roasting unit 7 is also opened, the nitrogen in the nitrogen source 8 enters the secondary reduction roasting unit 7 as a protective atmosphere through the sixth pipeline 81, and then enters the fifth pipeline 103 before entering the heating device 9.
[0066] The tar removed in the tar removal equipment 10 enters the tar storage tank 102 through the seventh pipeline 101. The nitrogen obtained is mixed with the nitrogen supplemented from the nitrogen source 8 and then recycled.
[0067] In a specific embodiment, such as Figure 1As shown, the first cyclone bag filter 4 is also connected to an eighth pipe 41, and the eighth pipe 41 is equipped with a first induced draft fan 42.
[0068] A third induced draft fan 52 is installed on the decoking pipeline 51.
[0069] In this embodiment, the powdered particles, under the attraction of the first induced draft fan 42, carry hot air and water vapor into the first cyclone bag filter 4, thereby achieving gas-solid separation.
[0070] The bottom of the first cyclone bag filter 4 is conical, causing the powdery particles inside the first cyclone bag filter 4 to enter the feeding device 3 in a cyclone manner. At the same time, the bottom of the feeding device 3 is also conical, causing the powdery particles inside the feeding device 3 and the nitrogen gas after heat exchange in the heating device 9 to enter the decoking and carbonization device 2 in a jet manner for decoking and carbonization. In the decoking and carbonization device 2, the material is suspended in the airflow and quickly mixes with nitrogen gas at 450℃-650℃. It is heated to 450℃~550℃ within 3-5 seconds for heat exchange. The glucose in the material forms water vapor, tar gas and carbon, completing the decoking and carbonization process. At this time, the glucose in the material exists in the form of carbon and is coated on the surface of the solid material.
[0071] In a specific embodiment, such as Figure 1 As shown, the primary reduction roasting unit 6 includes a first feeding component 61, a first reduction roasting furnace 62, a ninth pipeline 63, a tenth pipeline 67, and a second control valve 68. The first feeding component 61 is connected to the second cyclone bag filter 5. The first reduction roasting furnace 62 is connected to the first feeding component 61. The ninth pipeline 63 is connected to the first reduction roasting furnace 62. The tenth pipeline 67 is connected to both the first reduction roasting furnace 62 and the secondary reduction roasting unit 7. The second control valve 68 is installed on the tenth pipeline 67 and controls the gas flow rate within it. Specifically, the ninth pipeline 63, located near the first reduction roasting furnace 62, is sequentially equipped with a temperature regulating device 64, a third cyclone bag filter 65, and a second induced draft fan 66.
[0072] In this embodiment, the solid material in the second cyclone bag filter 5 enters the first reduction roasting furnace 62 through the first feeding component 61, which facilitates the entry of the solid material into the secondary reduction roasting unit 7.
[0073] The bottom of the second cyclone bag filter 5 is also conical.
[0074] Under the gravitational pull of the second induced draft fan 66, the gaseous material enters the temperature control device 64 and the third cyclone bag filter 65 sequentially through the ninth pipeline 63, and then is discharged.
[0075] In a specific embodiment, such as Figure 1 As shown, the secondary reduction roasting unit 7 includes a second reduction roasting furnace 71, a second feeding component 72, and a cooling rotary kiln 73. The second reduction roasting furnace 71 is connected to both the first reduction roasting furnace 62 and a tenth pipeline 67 located away from the first reduction roasting furnace 62. The second feeding component 72 is connected to the second reduction roasting furnace 71. The cooling rotary kiln 73 is connected to the second feeding component 72.
[0076] In this embodiment, the solid material in the first reduction roasting furnace 62 enters the second reduction roasting furnace 71 through the second feeding member 72, then enters the cooling rotary kiln 73, and is then discharged.
[0077] A second aspect of this invention provides a continuous dynamic carbonization reduction roasting method for lithium iron phosphate, such as... Figure 2 As shown, the continuous dynamic carbonization reduction roasting method for lithium iron phosphate includes:
[0078] After mixing iron phosphate, lithium carbonate and glucose, deionized water is added for batching. Deionized water is added as a dispersant for mixing and crystallization. After grinding, a slurry is obtained. The slurry is pumped into a spray drying equipment and simultaneously exchanged with air heating equipment at 250℃-280℃ to form powder particles.
[0079] Powdered particles at 130℃~140℃ are fed into the decoking and carbonization equipment through the first cyclone bag filter and the feeding equipment. They are mixed with nitrogen gas at 450℃-650℃ and heated to 450℃~550℃ within 3-5 hours. The glucose in the powdered particles forms water, tar and carbon coated on the surface of the solid powder, thus completing the decoking and carbonization. At this time, the glucose exists in the form of carbon.
[0080] The material that has completed decoking and carbonization enters the second cyclone bag filter in the form of gas phase and solid phase for gas-solid separation. The separated gas phase material enters the detarting equipment for detaring. The obtained nitrogen is mixed with nitrogen supplemented from the nitrogen source and then enters the heating equipment before entering the feeding equipment.
[0081] The solid phase material of the mixture of iron phosphate and lithium carbonate obtained by gas-solid separation enters the primary reduction roasting unit and undergoes dynamic roasting in a spiral state under the protective atmosphere of nitrogen. The temperature is raised to 650-780℃ for 1-2 hours for heating and pre-reduction. The pre-reduced material enters the secondary reduction roasting unit, where it undergoes dynamic roasting in a spiral motion at 650-780℃ under the protective atmosphere of nitrogen. The reduction of iron valence state and the removal of CO2 to convert lithium carbonate into lithium oxide are carried out for 3-5 hours to obtain single-phase lithium iron phosphate.
[0082] In this embodiment, continuous production is achieved during the continuous dynamic carbonization reduction roasting process of lithium iron phosphate; the material is dynamically roasted, and decoking and carbonization are carried out through a separately set decoking and carbonization equipment, thereby avoiding adhesion during roasting and avoiding breakage and homogenization after sintering; the material passes through a primary reduction roasting unit and a secondary reduction roasting unit, avoiding wear and impurity contamination of the product under high temperature conditions, thus achieving the quality stability of lithium iron phosphate.
[0083] Among them, lithium iron phosphate produced from the secondary reduction roasting unit enters the cooling rotary kiln and is cooled for 1 to 2 hours to form lithium iron phosphate product.
[0084] To further improve the performance of lithium iron phosphate after continuous dynamic carbonization reduction roasting, in a specific embodiment, the mass ratio of iron phosphate, lithium carbonate and glucose is 1:0.24~0.26:0.12~0.14.
[0085] Deionized water accounts for 60% to 80% of the total mass.
[0086] In a specific embodiment, the gaseous materials obtained from gas-solid separation are water vapor, tar, and nitrogen as a protective gas.
[0087] In a specific embodiment, after the nitrogen in the nitrogen source enters the second reduction roasting furnace, it enters the first reduction roasting furnace through the tenth pipeline, simultaneously replenishing the heat in the first reduction roasting furnace, and then exits through the ninth pipeline in sequence from the temperature control device, the third cyclone bag filter device, and the second induced draft fan.
[0088] The solid material obtained from gas-solid separation enters the first reduction roasting furnace through the first feeding element, then enters the second reduction roasting furnace, and finally enters the cooling rotary kiln through the second feeding element.
[0089] In this embodiment, a two-stage roasting process was implemented, namely, a pre-reduction process with heating and a reduction process with isothermal temperature, and the gaseous and solid phase materials were discharged through different paths. This improved the quality of lithium iron phosphate after continuous dynamic carbonization reduction roasting. Example
[0090] Iron phosphate, lithium carbonate and glucose are mixed and crystallized in a raw material pool and then machine-milled to obtain a slurry. The slurry is then heat-exchanged with air at 270°C in a spray drying equipment to form powder particles. After drying, the powder particles are fed into the decoking and carbonization equipment through a first cyclone bag filter and a feeding device.
[0091] The decoking and carbonization material enters the second cyclone bag filter in gas and solid phases for gas-solid separation. The separated solid material enters the first reduction roasting furnace and is heated to 735°C under nitrogen protection.
[0092] The material in the first reduction roasting furnace is then placed in the second reduction roasting furnace and kept at a constant temperature for 3.5 hours. The solid material that meets the requirements is then placed in the cooling rotary kiln from the second reduction roasting furnace and cooled for 1.5 hours to form lithium iron phosphate product. Example
[0093] Iron phosphate, lithium carbonate and glucose are mixed and crystallized in a raw material pool and then machine-milled to obtain a slurry. The slurry is then heat-exchanged with air at 250°C in a spray drying equipment to form powder particles. After drying, the powder particles are fed into the decoking and carbonization equipment through a first cyclone bag filter and a feeding device.
[0094] The decoking and carbonization material enters the second cyclone bag filter in gas and solid phases for gas-solid separation. The separated solid material enters the first reduction roasting furnace and is heated to 700°C under nitrogen protection.
[0095] The material in the first reduction roasting furnace is then placed in the second reduction roasting furnace and kept at a constant temperature for 3.5 hours. The solid material that meets the requirements is then placed in the cooling rotary kiln from the second reduction roasting furnace and cooled for 2.5 hours to form lithium iron phosphate product. Example
[0096] Ferric phosphate, lithium carbonate, and glucose are mixed and crystallized in a raw material pool, then machine-milled to obtain a slurry. The slurry is then subjected to heat exchange with air at 270°C in a spray drying equipment to form powder particles.
[0097] The powdered particles are introduced into the cyclone bag filter for gas-solid separation in both gas and solid phases. The separated solid material is then introduced into the first reduction roasting furnace and heated to 735°C under nitrogen protection.
[0098] The material in the first reduction roasting furnace is then placed in the second reduction roasting furnace and kept at a constant temperature for 3.5 hours. The solid material that meets the requirements is then placed in the cooling rotary kiln from the second reduction roasting furnace and cooled for 2.5 hours to form lithium iron phosphate product.
[0099] The experimental results are as follows:
[0100] Group Calcination temperature (°C) Production time h Energy saving % Annual output per furnace (wt) <![CDATA[Discharge specific capacity Ah·g -1 > Example 1 780 4 60 5 155 Example 2 715 6 50 4 142 Example 3 650 7 40 3 113
[0101] As shown in the table, the overall production time is reduced to 5-6 hours compared to the existing technology, which takes more than 20 hours. Energy consumption is reduced by 40-60% from slurry to finished lithium iron phosphate product. The discharge specific capacity performance is stable and improved, and the annual output of a single furnace can reach 30,000-50,000 tons. Among them, the lithium iron phosphate sample prepared in Example 1 with a calcination temperature of 780℃ and a production time of 4 hours has the highest discharge specific capacity at a charging current density of 0.1C. This indicates that the lithium iron phosphate product prepared at a synthesis temperature of 780℃, a calcination and holding time of 4 hours, and after decoking and carbonization treatment has the best electrochemical performance.
[0102] Compared to Examples 1 and 2, Example 3 did not perform decoking and carbonization treatment on the powdered particles after gas-solid separation, resulting in a product with relatively poor electrochemical performance.
[0103] This invention achieves continuous addition of iron phosphate, lithium carbonate, and glucose, enabling continuous production of lithium iron phosphate. It eliminates the need for a sagger, effectively utilizing the residual heat carried by the dried powder material and avoiding the ineffective heat required for sagger heating. The static calcination of the sagger is replaced with dynamic calcination of the powder, improving gas-solid heat transfer and the reduction reaction rate, while reducing product energy consumption. Furthermore, due to the continuous production process, the sagger is eliminated, removing steps such as cooling and storing the dried material in the sagger and cooling and crushing the product. Simultaneously, the change from static calcination to dynamic calcination of the powder significantly reduces the reduction calcination time, decreasing production time from over 20 hours to 4-7 hours, thus increasing the output per furnace.
[0104] This invention replaces the single-stage roasting process with a two-stage roasting process, namely a pre-reduction process with heating and a constant-temperature reduction process. It also replaces the existing layered static roasting with dynamic roasting, avoiding the uneven roasting uniformity caused by the unevenness of shelf-type layered roasting. Furthermore, it adds an independent decoking and carbonization unit for glucose, preventing agglomeration and clumping during roasting and eliminating the need for the final pulverization step. This improves the quality of lithium iron phosphate.
[0105] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.
Claims
1. A continuous dynamic carbonization reduction roasting apparatus for lithium iron phosphate, comprising a raw material pool, wherein the raw material pool is connected to a spray drying device via a first pipeline, characterized in that, The spray drying equipment is connected to a second pipeline. A first cyclone bag filter is connected to the end of the second pipeline away from the spray drying equipment. A feeding device is connected to the bottom of the first cyclone bag filter. A decoking and carbonization device is connected to the bottom of the feeding device. The decoking and carbonization device is connected to a third pipeline. A second cyclone bag filter is connected to the end of the third pipeline away from the decoking and carbonization device. A fourth pipeline is also connected to the feeding device. A heating device is connected to the end of the fourth pipeline away from the feeding device. A fifth pipeline is also connected to the heating device. A tar removal device is connected to the end of the fifth pipeline away from the heating device. The tar removal device and the second cyclone bag filter are connected via a decoking pipeline. The second cyclone bag filter is also connected to a primary reduction roasting unit. A secondary reduction roasting unit is connected to the primary reduction roasting unit. The secondary reduction roasting unit and the fifth pipeline are connected via a sixth pipeline. A nitrogen source is connected to the sixth pipeline. An air heating device for heating the raw material is connected to the first pipeline near the spray drying equipment. A slurry pump is also installed on the first pipeline.
2. The lithium iron phosphate continuous dynamic carbonization reduction roasting apparatus according to claim 1, characterized in that, The sixth pipeline located on both sides of the nitrogen source is respectively equipped with a first control valve for controlling the direction and flow rate of nitrogen. The tar removal equipment is also connected to a seventh pipeline, and the end of the seventh pipeline, which is away from the tar removal equipment, is connected to a tar storage tank.
3. The lithium iron phosphate continuous dynamic carbonization reduction roasting apparatus according to claim 1, characterized in that, The first cyclone bag filter is also connected to an eighth pipeline, on which a first induced draft fan is installed; A third induced draft fan is installed on the decoking pipeline.
4. The lithium iron phosphate continuous dynamic carbonization reduction roasting apparatus according to claim 1, characterized in that, The primary reduction calcination unit includes: The first feeding component is connected to the second cyclone bag filter. The first reduction roasting furnace is connected to the first feeding component; The ninth pipeline is connected to the first reduction roasting furnace; The tenth pipeline is connected to both the first reduction roasting furnace and the secondary reduction roasting unit; A second control valve is installed on the tenth pipeline and controls the gas flow rate in the tenth pipeline; Among them, a temperature regulating device, a third cyclone bag filter, and a second induced draft fan are sequentially installed on the ninth pipeline near the first reduction roasting furnace.
5. The lithium iron phosphate continuous dynamic carbonization reduction roasting apparatus according to claim 4, characterized in that, The secondary reduction calcination unit includes: The second reduction roasting furnace is connected to both the first reduction roasting furnace and the tenth pipeline located away from the first reduction roasting furnace. The second feeding component is connected to the second reduction roasting furnace; The cooling rotary kiln is connected to the second feeding component.
6. A continuous dynamic carbonization reduction roasting method for lithium iron phosphate, characterized in that, The lithium iron phosphate continuous dynamic carbonization reduction roasting apparatus as described in claim 1 comprises: After mixing ferric phosphate, lithium carbonate and glucose, deionized water is added for batching. Deionized water is used as a dispersant. After mixing and crystallizing, the mixture is milled to obtain a slurry. The slurry is pumped into a spray drying device and simultaneously exchanged with an air heating device at 250℃~280℃ to form powder particles. The powdered particles, heated to 130℃~140℃, are fed into the decoking and carbonization equipment through a first cyclone bag filter and a feeding device. They are mixed with nitrogen gas at 450℃~650℃ and heated to 450℃~550℃ within 3~5 hours. The glucose in the powdered particles forms water, tar, and carbon coated on the surface of the solid powder, thus completing the decoking and carbonization. The material that has completed decoking and carbonization enters the second cyclone bag filter in the form of gas phase and solid phase for gas-solid separation. The separated gas phase material enters the detarting equipment for detaring. The obtained nitrogen is mixed with nitrogen supplemented from the nitrogen source and then enters the heating equipment before entering the feeding equipment. The solid material obtained from the gas-solid separation enters the primary reduction roasting unit and undergoes dynamic roasting in a spiral state under a nitrogen protective atmosphere. It is then pre-reduced by heating to 650℃~780℃ for 1h~2h. The pre-reduced material enters the secondary reduction roasting unit, where it undergoes dynamic roasting in a spiral motion at 650℃~780℃ under a nitrogen protective atmosphere. The process of reducing the valence state of iron and removing CO2 by converting lithium carbonate to lithium oxide takes place for 3h~5h, yielding lithium iron phosphate single-phase material.
7. The continuous dynamic carbonization reduction roasting method for lithium iron phosphate according to claim 6, characterized in that, The mass ratio of iron phosphate, lithium carbonate, and glucose is 1:0.24~0.26:0.12~0.14; Deionized water accounts for 60% to 80% of the total mass.
8. The continuous dynamic carbonization reduction roasting method for lithium iron phosphate according to claim 6, characterized in that, The gaseous materials obtained from gas-solid separation are water vapor, tar, and nitrogen as a protective gas.
9. The continuous dynamic carbonization reduction roasting method for lithium iron phosphate according to claim 6, characterized in that, After the nitrogen in the nitrogen source enters the second reduction roasting furnace, it enters the first reduction roasting furnace through the tenth pipeline, and then exits through the ninth pipeline in sequence from the temperature control equipment, the third cyclone bag filter, and the second induced draft fan. The solid material obtained from the gas-solid separation enters the first reduction roasting furnace through the first feeding element, then enters the second reduction roasting furnace, and finally enters the cooling rotary kiln through the second feeding element.