Production equipment and production method of lithium iron manganese phosphate positive electrode material precursor

Abstract

The invention discloses production equipment and a production method of a lithium manganese iron phosphate positive electrode material precursor, and relates to the technical field of synthesis of lithium manganese iron phosphate. The manganese dissolving reaction kettle is used for mixing the ferric salt solution, a manganese source and a reducing agent to generate a ferromanganese salt solution; the liquid preparation kettle is used for mixing the ferromanganese salt solution with an additive to generate a mixed solution, and the additive is a phosphorus source and a lithium source, or the additive is phosphoric acid; the synthesis furnace is used for generating a lithium iron manganese phosphate positive electrode material precursor; according to the method, the iron source and the hydrochloric acid are utilized to generate the ferric salt solution, then the ferric salt solution and the manganese source are utilized to generate the ferromanganese salt mixed solution, then the reducing agent is added to generate the mixed solution in which the manganese is kept positive bivalent and the iron is kept positive bivalent, and finally the additive is added to prepare the ferromanganese phosphorus mixed solution or the ferromanganese lithium phosphorus mixed solution. And the lithium iron manganese phosphate positive electrode material precursor powder with stable product quality and good product quality can be generated in the synthesis furnace.

Description

Technical Field

[0001] The present invention relates to the technical field of lithium manganese iron phosphate synthesis, and in particular to a production device and a production method of a lithium manganese iron phosphate positive electrode material precursor. Background Art

[0002] Previous synthesis methods of lithium manganese iron phosphate were mainly divided into solid-phase method and liquid-phase method. The solid-phase method adopts mixed sintering of manganese source, iron source, phosphorus source and lithium source. It has the advantages of simple process, less equipment required, easy production and low cost. It is widely used in the preparation of lithium manganese iron phosphate positive electrode materials. However, it is difficult to solve the problem of uneven distribution of manganese and iron elements, which affects the material's ion transfer rate, rate performance, gram capacity and cycle performance, making it difficult for its comprehensive electrochemical performance to meet the indicators required for actual applications, thereby restricting the commercial application process of lithium manganese iron phosphate materials; the improved solid-phase method is to prepare manganese iron precursors, such as ferromanganese oxalate, ferromanganese carbonate, ferromanganese phosphate, ferromanganese pyrophosphate, etc., but there is still uneven distribution of manganese iron, and it is impossible to prepare precursors with stable quality. The liquid phase method mainly refers to the sol-gel method and the hydrothermal method. The sol-gel method dissolves the phosphorus source, manganese source (manganese nitrate), iron source (ferric nitrate), and lithium source in a certain proportion and then crystallizes to obtain a liquid slurry. After preheating, a honeycomb gel is formed, which is crushed, rolled, sintered, and ground to obtain the finished lithium iron manganese phosphate. However, the sol-gel method has two problems: first, when the sol-gel method crystallizes from the solution to form a slurry, the manganese element and the iron element crystallize asynchronously, resulting in uneven mixing of the two elements of manganese and iron, resulting in the appearance of impurities in the solid solution of the positive electrode material, causing manganese to dissolve; second, the nitrate ions in the raw materials cause environmental pressure on the treatment of nitrogen oxide tail gas and also increase production costs; the hydrothermal method uses ferrous sulfate, manganous sulfate, phosphoric acid, and lithium hydroxide in a high-temperature and high-pressure hydrothermal reactor to generate lithium iron manganese phosphate, lithium sulfate, and water. The primary particle size of the lithium iron manganese phosphate produced by this method is relatively uniform, but there is also the problem of uneven distribution due to asynchronous crystallization of manganese and iron, and the hydrothermal method is expensive and has high production costs, making it unsuitable for large-scale commercial promotion.

[0003] Therefore, people are in urgent need of a production equipment that can produce lithium manganese iron phosphate positive electrode material precursor with uniform distribution of manganese and iron. Summary of the Invention

[0004] The purpose of the present invention is to provide a production device and a production method for a lithium manganese iron phosphate positive electrode material precursor, which utilizes an iron source, a manganese source, hydrochloric acid, a reducing agent and an additive to prepare a mixed solution in which manganese maintains a positive divalence and iron maintains a positive divalence, which is conducive to generating a lithium manganese iron phosphate positive electrode material precursor in a synthesis furnace with uniform distribution of manganese and iron, stable product quality and good product quality.

[0005] To achieve the above-mentioned objectives, the present invention provides the following solutions: The present invention provides a production device for a lithium iron manganese phosphate positive electrode material precursor, comprising: an iron dissolution reactor for generating an iron salt solution; a manganese dissolution reactor for mixing the iron salt solution, a manganese source and a reducing agent to generate a manganese iron salt solution, the feed port of the manganese dissolution reactor being connected to the discharge port of the iron dissolution reactor; a liquid preparation reactor for mixing the manganese iron salt solution with an additive to generate a mixed liquid, the feed port of the liquid preparation reactor being connected to the discharge port of the manganese dissolution reactor, the additive being a phosphorus source and a lithium source, or the additive being phosphoric acid; and a synthesis furnace for generating a lithium iron manganese phosphate positive electrode material precursor, the feed port of the synthesis furnace being connected to the discharge port of the liquid preparation reactor.

[0006] Preferably, the production equipment of the lithium manganese iron phosphate positive electrode material precursor further includes an impurity removal device, which is arranged between the iron dissolution reactor and the synthesis furnace, and the impurity removal device is a solid-liquid separator.

[0007] Preferably, the production equipment of the lithium manganese iron phosphate positive electrode material precursor also includes a pre-concentrator, which includes a Venturi structure and a gas-liquid separation structure. The feed port of the Venturi structure is connected to the liquid preparation kettle, the discharge port is connected to the feed port of the gas-liquid separation structure, the negative pressure suction port is connected to the high-temperature flue gas channel of the synthesis furnace, and the liquid outlet of the gas-liquid separation structure is connected to the synthesis furnace.

[0008] Preferably, the gas outlet of the gas-liquid separation structure is connected to a hydrochloric acid storage tank for storing hydrochloric acid through an absorption tower, and the hydrochloric acid storage tank is connected to the hydrochloric acid feed port of the iron dissolution reactor.

[0009] Preferably, the liquid preparation kettle is connected to the top of the inner cavity of the synthesis furnace through an atomizing device, and the atomizing device is connected to the liquid preparation kettle, the desalted water supply pipeline and the high-pressure protective gas supply pipeline through valves respectively.

[0010] Preferably, the synthesis furnace comprises a furnace body and a burner for ejecting hot air flow, and the burner is arranged on the furnace body.

[0011] Preferably, the production equipment of the lithium manganese iron phosphate positive electrode material precursor further includes a liquid preparation storage tank, the feed port of the liquid preparation storage tank is connected to the liquid preparation kettle, the discharge port is connected to the synthesis furnace, and the liquid preparation storage tank is provided with a feed port for supplying the additive.

[0012] Preferably, a cooler for cooling the lithium manganese iron phosphate positive electrode material precursor powder is provided at the bottom of the synthesis furnace, and the feed port of the cooler is connected to the discharge port of the synthesis furnace.

[0013] Preferably, the production equipment of the lithium manganese iron phosphate positive electrode material precursor also includes a processing unit for processing the lithium manganese iron phosphate positive electrode material precursor powder, and the processing unit includes a crusher, a demagnetizer, a screening machine, a silo and a packaging machine arranged in sequence, and the feed port of the crusher is connected to the discharge port of the cooler.

[0014] The present invention also provides a method for producing a lithium manganese iron phosphate positive electrode material precursor using the above-mentioned production equipment for the lithium manganese iron phosphate positive electrode material precursor, comprising the following steps:

[0015] S1: adding hydrochloric acid into the iron dissolution reactor through the hydrochloric acid feed port, and adding an iron source into the iron dissolution reactor through the iron source feed port, the iron source reacts with the hydrochloric acid to generate an iron salt solution, and the iron salt solution is transferred to the manganese dissolution reactor;

[0016] S2: adding manganese source into the manganese dissolution reactor through the manganese source feed port to react and generate manganese iron salt solution;

[0017] S3: adding a reducing agent into the manganese dissolution reactor through the reducing agent feed port to keep the manganese and iron in the manganese ferromanganese salt solution at a positive divalent value;

[0018] S4: transferring the manganese iron salt solution into a liquid preparation kettle, adding additives into the liquid preparation kettle through an additive feed port to prepare a manganese iron phosphorus mixed solution or a manganese iron lithium phosphorus mixed solution;

[0019] S5: The manganese iron phosphorus mixed solution or the manganese iron lithium phosphorus mixed solution is supplied into the synthesis furnace for heating, and the reaction generates manganese iron pyrophosphate powder or lithium iron manganese phosphate powder, which is the precursor powder of the manganese iron phosphate lithium positive electrode material.

[0020] Compared with the prior art, the present invention mainly achieves the following technical effects:

[0021] First, an iron salt solution is generated by using an iron source and hydrochloric acid, and then the iron salt solution is used with a manganese source to generate a manganese-iron salt mixture. Then, a reducing agent is added to generate a mixture in which manganese maintains a positive divalence and iron maintains a positive divalence. Finally, additives are added to prepare a manganese-iron-phosphorus mixture or a manganese-iron-lithium-phosphorus mixture, thereby achieving uniform distribution of manganese and iron, which is conducive to generating a lithium manganese iron phosphate positive electrode material precursor powder with stable product quality and good product quality in a synthesis furnace.

[0022] Compared with the prior art, other solutions of the present invention have achieved the following technical effects:

[0023] The pre-concentrator can use the heat of the high-temperature flue gas from the synthesis furnace to preheat the manganese iron phosphorus mixture or manganese iron lithium phosphorus mixture, and at the same time, the separated acid gas is transported to the absorption tower. The absorption tower recovers hydrochloric acid in the acid gas and supplies it to the iron dissolution reactor for use.

[0024] The setting of the liquid storage tank not only provides a place for testing whether the manganese iron phosphorus mixture or the manganese iron lithium phosphorus mixture is qualified before it enters the synthesis furnace, but also serves as a device for receiving and storing the manganese iron phosphorus mixture or the manganese iron lithium phosphorus mixture. It can continuously supply the manganese iron phosphorus mixture or the manganese iron lithium phosphorus mixture into the synthesis furnace, thereby realizing the continuous production of lithium manganese iron phosphate positive electrode material precursor powder. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0026] Figure 1 This is a system diagram of a production equipment for a lithium manganese iron phosphate cathode material precursor according to an embodiment of the present invention;

[0027] Figure 2 Schematic diagram of the structure of the pre-concentrator in an embodiment of the present invention;

[0028] Among them, 1. Iron dissolution reactor; 2. Manganese dissolution reactor; 3. Liquid preparation reactor; 4. Impurity removal device; 5. Liquid preparation storage tank; 6. Pre-concentrator; 7. Atomization device; 8. Synthesis furnace; 9. Cooler; 10. Crusher; 11. Demagnetizer; 12. Screening machine; 13. Silo; 14. Packaging machine; 15. Absorption tower; 16. Venturi structure; 17. Gas-liquid separation structure; 18. Circulation pump; 19. Feed pump; 20. Hydrochloric acid storage tank. DETAILED DESCRIPTION

[0029] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0030] The purpose of the present invention is to provide a production device and a production method for a lithium manganese iron phosphate positive electrode material precursor to solve the problems existing in the prior art. A mixed solution in which manganese is kept at a positive divalence and iron is kept at a positive divalence is prepared by using an iron source, a manganese source, hydrochloric acid, a reducing agent and an additive, which is conducive to the generation of a lithium manganese iron phosphate positive electrode material precursor with uniform distribution of manganese and iron in a synthesis furnace, stable product quality and good product quality.

[0031] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0032] Please refer to Figure 1 、 Figure 2 As shown, a production device for a lithium manganese iron phosphate positive electrode material precursor is provided, comprising an iron dissolving reactor 1 for generating an iron salt solution, a manganese dissolving reactor 2 for mixing the iron salt solution, a manganese source and a reducing agent to generate a manganese iron salt solution, a liquid preparation reactor 3 for mixing the manganese iron salt solution with an additive to generate a mixed solution, and a synthesis furnace 8 for generating a lithium manganese iron phosphate positive electrode material precursor, wherein the iron dissolving reactor 1 is provided with a hydrochloric acid feed port and an iron source feed port; the feed port of the manganese dissolving reactor 2 is connected to the discharge port of the iron dissolving reactor 1, and the manganese dissolving reactor 2 is provided with a manganese source feed port and a reducing agent feed port; the feed port of the liquid preparation reactor 3 is connected to the discharge port of the manganese dissolving reactor 2, and the liquid preparation reactor 3 is provided with a An additive feed port is provided on the top, and the additives are a phosphorus source and a lithium source. In this case, a phosphorus source feed port and a lithium source feed port are provided on the liquid preparation kettle 3, or the additive is phosphoric acid, and in this case, a phosphoric acid feed port is provided on the liquid preparation kettle 3; the feed port of the synthesis furnace 8 is connected to the discharge port of the liquid preparation kettle 3; when the device is in use, an iron salt solution is first generated by using an iron source and hydrochloric acid, and then a manganese-iron salt mixture is generated by using the iron salt solution and a manganese source, and then a reducing agent is added to generate a mixture in which manganese remains divalent and iron remains divalent, and finally an additive is added to prepare a manganese-iron-phosphorus mixture or a manganese-iron-lithium-phosphorus mixture, thereby achieving uniform distribution of manganese and iron, which is conducive to the generation of a manganese-iron-phosphate lithium positive electrode material precursor powder with stable product quality and good product quality in the synthesis furnace 8.

[0033] In this embodiment, the iron source is at least one of Fe, FeO, Fe2O3, Fe3O4, FeCO3, FeC2O4, FeOOH, FeCl2, and FeCl3; the manganese source is at least one of Mn, MnO, MnCO3, MnC2O4, and MnCl2; the reducing agent is at least one of citric acid, oxalic acid, tartaric acid, formic acid, and hydroxylamine hydrochloride; the lithium source is at least one of lithium carbonate, lithium hydroxide, lithium chloride, lithium phosphate, and lithium dihydrogen phosphate; and the phosphorus source is at least one of phosphoric acid, iron phosphate, lithium iron phosphate, lithium manganese iron phosphate, lithium phosphate, and lithium dihydrogen phosphate.

[0034] The number of the iron dissolving reactor 1 and the manganese dissolving reactor 2 is at least one. If a production capacity of 10,000 tons / year is to be provided, the total capacity of the iron dissolving reactor 1 and the manganese dissolving reactor 2 should be at least 90 cubic meters. The material of the iron dissolving reactor 1 and the manganese dissolving reactor 2 should be FRP or other acid corrosion-resistant materials, and have a certain heat resistance, can withstand high temperatures of 80 to 120°C, and have a certain insulation effect, with a thermal conductivity of less than 10kJ / (m·h·K).

[0035] The liquid level sensor can be used in conjunction with the alarm device to enable the iron dissolution reactor 1 and the manganese dissolution reactor 2 to have high liquid level alarm and ultra-high liquid level alarm functions, and the settings of high liquid level and ultra-high liquid level are selected according to actual needs; the temperature sensor can be used in conjunction with the alarm device to enable the iron dissolution reactor 1 and the manganese dissolution reactor 2 to have high temperature alarm and ultra-high temperature alarm functions, and the settings of high temperature and ultra-high temperature are selected according to actual needs; the flow sensor can be used in conjunction with the alarm device to enable the iron dissolution reactor 1 and the manganese dissolution reactor 2 to have high flow alarm and ultra-high flow alarm functions (for hydrochloric acid and additives), and the settings of high flow and ultra-high flow are selected according to actual needs.

[0036] The production equipment of the lithium manganese iron phosphate positive electrode material precursor also includes a de-impurity device 4, which is arranged between the iron dissolution reactor 1 and the synthesis furnace 8. In this embodiment, it is specifically arranged between the liquid preparation reactor 3 and the synthesis furnace 8. The de-impurity device 4 is a solid-liquid separator, such as a filter press, a centrifuge, a filter, etc., which can be used for solid-liquid separation. The de-impurity device 4 removes impurities from the manganese iron phosphorus mixed liquid or the manganese iron lithium phosphorus mixed liquid output from the liquid preparation reactor 3, removes undissolved raw materials and other metal particles (such as Cu, SiO2, etc.), and the de-impurity filter residue is collected and transported, and the manganese iron phosphorus mixed liquid or manganese iron lithium phosphorus mixed liquid after de-impurity is continued to be transported.

[0037] There are multiple impurity removal devices 4, and the multiple impurity removal devices 4 exist in parallel. When one of the impurity removal devices 4 fails, the other impurity removal devices 4 can be started to work to ensure the continuity of work.

[0038] The production equipment of the lithium iron manganese phosphate positive electrode material precursor in this embodiment also includes a pre-concentrator 6, which includes a venturi structure 16 and a gas-liquid separation structure 17. The feed port of the venturi structure 16 is connected to the liquid preparation kettle 3, the discharge port is connected to the feed port of the gas-liquid separation structure 17, the negative pressure suction port is connected to the high-temperature flue gas channel of the synthesis furnace 8, and the liquid outlet of the gas-liquid separation structure 17 is connected to the synthesis furnace 8. The heat of the high-temperature flue gas of the synthesis furnace 8 can be used to preheat and concentrate the manganese iron phosphorus mixture or the manganese iron lithium phosphorus mixture (after preheating, the water evaporates to complete the concentration), thereby improving the reaction efficiency of the manganese iron phosphorus mixture or the manganese iron lithium phosphorus mixture in the synthesis furnace 8.

[0039] In this embodiment, the pre-concentrator 6 is arranged between the impurity removal device 4 and the synthesis furnace 8 .

[0040] A circulating pump 18 can be provided to provide power for the manganese iron phosphorus mixture or the manganese iron lithium phosphorus mixture. The liquid inlet of the circulating pump 18 is respectively connected to the liquid outlet of the gas-liquid separation structure 17 and the liquid outlet of the impurity removal device 4. The liquid outlet of the circulating pump 18 is respectively connected to the liquid inlet of the synthesis furnace 8 and the venturi structure 16. A feeding pump 19 is provided on the connecting pipeline between the circulating pump 18 and the synthesis furnace 8.

[0041] The Venturi structure 16 and the gas-liquid separation structure 17 can be arranged in one piece or in a separate piece. Both are made of acid-corrosion-resistant materials. The material of the Venturi structure 16 can withstand a high temperature of 600°C and an internal negative pressure close to 1 atmosphere. In this embodiment, the diameter of the throat part of the Venturi structure 16 is 150mm~500mm, the height of the Venturi structure 16 is 3000mm~5000mm, the diameter of the gas-liquid separation structure 17 is 750mm~1250mm, and the height of the gas-liquid separation structure 17 is 2000mm~3000mm.

[0042] The gas outlet of the gas-liquid separation structure 17 is connected to the hydrochloric acid storage tank 20 for storing hydrochloric acid through the absorption tower 15. The hydrochloric acid storage tank 20 is connected to the hydrochloric acid feed port of the iron dissolution reactor 1, so that the HCl acid gas separated by the gas-liquid separation structure 17 is transported to the absorption tower 15. The absorption tower 15 recovers the hydrochloric acid in the acid gas and supplies it to the iron dissolution reactor 1 for use. In this embodiment, the absorption tower 15 recovers more than 80% of the HCl in the acid gas discharged from the gas-liquid separation structure 17 to generate regenerated hydrochloric acid with a concentration of 10% to 25%. The waste gas after acid recovery is sent to the waste gas treatment system for treatment and then discharged.

[0043] In order to improve the reaction effect of the manganese iron phosphorus mixture or the manganese iron lithium phosphorus mixture in the synthesis furnace 8, the liquid preparation kettle 3 is connected to the inner cavity top of the synthesis furnace 8 through the atomizing device 7. The atomizing device 7 is connected to the liquid preparation kettle 3, the desalted water supply pipeline and the high-pressure shielding gas supply pipeline through valves respectively. The atomizing device 7 can be adapted to different modes in the synthesis furnace 8 by means of an on-off valve. In the acid mist production mode of the synthesis furnace 8, the atomizing device 7 receives the manganese iron phosphorus mixture or the manganese iron lithium phosphorus mixture and the high-pressure shielding gas (nitrogen or argon). The high-pressure shielding gas provides an atomization driving force for the manganese iron phosphorus mixture or the manganese iron lithium phosphorus mixture and forms a protective atmosphere to prevent ferrous ion oxidation. In this embodiment, the atomizing device 7 atomizes the manganese iron phosphorus mixture or the manganese iron lithium phosphorus mixture with a flow rate of 2000L / h to 14000L / h, and the high-pressure shielding gas flow rate is 200 to 2800m 3 / h, the pressure must be greater than 0.3MPa, the average particle size of the mist droplets is 10μm~100μm, and the acid mist production mode is carried out; in the water mist drying furnace mode and the water mist hot stop mode of the synthesis furnace 8, the atomizing device 7 receives the desalted water and sprays it on the top of the inner cavity of the synthesis furnace 8 to avoid overheating of the furnace top and protect the synthesis furnace 8 body. In this embodiment, the atomizing device 7 atomizes the desalted water with a flow rate of 2000L / h~14000L / h to carry out the water mist drying furnace mode and the water mist hot stop mode, and the pressure of the desalted water is greater than 1 standard atmospheric pressure.

[0044] In this embodiment, the atomizing device 7 is arranged between the pre-concentrator 6 and the synthesis furnace 8 .

[0045] The modes of the atomizing device 7 also include a shutdown mode and a gun test mode. In the shutdown mode, the spray gun is in the gun test position outside the synthesis furnace 8, and the atomizing device 7 does not provide an atomizing function. In the gun test mode, the spray gun is in the gun test position outside the synthesis furnace 8, and the atomizing device 7 provides a water mist function to test the atomization effect. The atomizing device 7 can be detachably arranged on the synthesis furnace 8. After the atomizer is disassembled by a pneumatic or electric machine, the shutdown mode and the gun test mode can be entered.

[0046] The atomizing device 7 is provided with multiple spray guns, and at least one nozzle is provided at the end of the spray gun. The nozzle needs to be made of acid-corrosion-resistant hard material, such as stainless steel, titanium alloy or niobium, and the nozzles are evenly distributed to improve the uniformity of the spray.

[0047] The synthesis furnace 8 includes a furnace body and a burner for ejecting a hot air flow. The burner is connected to a fire channel for providing fuel gas and air. The burner is arranged on the furnace body. Specifically, a plurality of evenly distributed burners can be arranged on the inner wall surface of the furnace body to improve the heating uniformity and heating efficiency. In this embodiment, the furnace body is composed of at least four layers of materials, which are divided into an outer insulation layer, an intermediate metal furnace body, an inner insulation layer, and an inner wall refractory layer from the outside to the inside. The refractory layer generally adopts refractory materials that are resistant to acid corrosion and high temperature. The furnace diameter of the synthesis furnace 8 body is 6000mm~15000mm, and the height of the furnace body is 15000mm~40000mm; the maximum temperature in the furnace of the synthesis furnace 8 is 1100℃, and the reaction temperature is 550℃~750℃; the time from the start of the synthesis reaction to the fall of the atomized droplets in the synthesis furnace 8 to the bottom of the furnace is 10~60s, and the production efficiency of the synthesis furnace 8 is 1t / h~7t / h.

[0048] In this embodiment, the synthesis furnace 8 includes multiple working modes, namely, minor maintenance mode, major maintenance mode, cold stop standby mode, heating mode, water mist drying furnace mode, acid mist production mode, water mist hot stop mode, and cooling mode. In different modes, the states and functions of the synthesis furnace 8 are as follows:

[0049] The minor maintenance mode is a maintenance state in which no scaffolding is set up inside the synthesis furnace 8. In the minor maintenance mode, the synthesis furnace 8 is in a shutdown state, and the relevant energy required for the maintenance work is isolated and listed depending on the situation.

[0050] The overhaul mode is a maintenance state in which a scaffolding needs to be set up inside the synthesis furnace 8. In the overhaul mode, the synthesis furnace 8 is completely out of service, and all energy related to the synthesis furnace 8 has been isolated and listed.

[0051] The cold stop standby mode is a shutdown stage in which the synthesis furnace 8 is at room temperature. In the cold stop standby mode, all energy related to the synthesis furnace 8 has been released from isolation and can be ignited and heated at any time.

[0052] The heating mode is the stage in which the synthesis furnace 8 is heated to 450°C after ignition. In the heating mode, the function of the synthesis furnace 8 is to use the heat energy and hot air generated after the combustion of the gas to slowly heat up the entire synthesis furnace 8 as a whole, so as to enter the water mist drying furnace mode. In the heating mode, the air-fuel ratio (the volume ratio of combustion air and gas) is between 7 and 20. The atomizing device 7 is still in the shutdown mode, but it needs to be prepared to switch to the water mist drying furnace mode. In the heating mode, several temperature platforms should be set between 100°C and 420°C. The temperature platform refers to the temperature remaining unchanged for a period of time. The overall temperature change curve is in the shape of a step, and the tread of the step is the temperature platform. The setting of the temperature platform can protect the various materials of the synthesis furnace 8 furnace body, prevent the problem of excessive temperature gradient of the furnace wall material due to excessive heating, and keep the various materials basically in a synchronous heating state.

[0053] The water mist drying furnace mode is the stage from the temperature of synthesis furnace 8 reaching 450°C to the start of the acid mist production mode. In this mode, synthesis furnace 8's function is to completely evaporate the liquid water inside the furnace and consume all remaining oxygen in the furnace, creating an oxygen-free environment to prevent oxidation of ferrous ions and prepare all conditions for synthesis furnace 8 to enter the acid mist production mode. The air-fuel ratio in water mist drying furnace mode is between 7 and 15. The appropriate air-fuel ratio ensures that the oxygen in the combustion air is consumed to less than 1% in the fire channel. In water mist drying furnace mode, atomizer 7 must be activated and operated in normal water mist mode to protect synthesis furnace 8.

[0054] The acid mist production mode is the stage in which the synthesis furnace 8 formally produces the lithium iron manganese phosphate positive electrode material precursor. In the acid mist production mode, the function of the synthesis furnace 8 is to provide various conditions required for the atomization high-temperature synthesis reaction together with the atomization device 7. The atomization high-temperature synthesis reaction refers to the reaction process in which a solution of a certain ratio is atomized and then dried at high temperature, and then undergoes one or more of a series of chemical reactions such as precipitation reaction, condensation reaction, combination reaction, decomposition reaction, etc. to form a target solid powder. It is divided into two stages: atomization and high-temperature synthesis. The synthesis furnace 8 causes the atomized manganese iron phosphorus mixture or manganese iron lithium phosphorus mixture to undergo a high-temperature synthesis reaction under a high-temperature environment to generate lithium iron manganese phosphate positive electrode material precursor powder, and the generated lithium iron manganese phosphate positive electrode material precursor powder is collected at the bottom of the furnace. In the acid mist production mode, the air-fuel ratio is between 7 and 15. The appropriate air-fuel ratio ensures that the oxygen in the combustion air is consumed to less than 1% in the fire channel, avoiding a large amount of oxygen being brought into the synthesis furnace 8 and causing ferrous ion oxidation. In the acid mist production mode, the atomization device 7 operates in the acid mist mode.

[0055] The water mist hot stop mode is the stage when the synthesis furnace 8 suspends production and is about to switch back to the acid mist production mode, or the stage before completely stopping production and entering the cooling mode. During this stage, the temperature of the synthesis furnace 8 is greater than or equal to 450°C. In the water mist hot stop mode, the function of the synthesis furnace 8 is to keep the synthesis furnace 8 in a hot stop state. It can be switched back to the acid mist production mode as needed. The gas flow rate is basically the same as that in the acid mist production mode, and the air-fuel ratio is between 7 and 15. The appropriate air-fuel ratio ensures that the oxygen in the combustion air is completely consumed in the fire channel. In the water mist hot stop mode, the atomizing device 7 is still running, and the atomizing device 7 operates in the normal water mist mode to protect the synthesis furnace 8.

[0056] The cooling mode is a stage in which the synthesis furnace 8 is cooled from 450° C. to room temperature. In the cooling mode, the atomizing device 7 operates in the shutdown mode and stops supplying gas.

[0057] The production equipment of the lithium iron manganese phosphate positive electrode material precursor also includes a liquid preparation storage tank 5, the feed port of the liquid preparation storage tank 5 is connected to the liquid preparation kettle 3, and the discharge port is connected to the synthesis furnace 8. The liquid preparation storage tank 5 is provided with a feed port for adding additives, and the composition of the additives is the same as the composition of the additives added to the liquid preparation kettle 3. The setting of the liquid preparation storage tank 5 not only provides a place for detecting whether the manganese iron phosphorus mixture or the manganese iron lithium phosphorus mixture is qualified before entering the synthesis furnace 8, but also serves as a device for receiving and storing the manganese iron phosphorus mixture or the manganese iron lithium phosphorus mixture. It can continuously supply the manganese iron phosphorus mixture or the manganese iron lithium phosphorus mixture into the synthesis furnace 8, thereby realizing the continuous production of the lithium iron manganese phosphate positive electrode material precursor.

[0058] The number of liquid storage tanks 5 is at least one. If a production capacity of 10,000 tons / year is required, the total capacity of all liquid storage tanks 5 is at least 60 cubic meters. The material of the liquid storage tank 5 should be PPH or other acid corrosion-resistant materials, the operating temperature can reach 100°C, and it has the characteristics of wear resistance, high temperature resistance and non-toxicity.

[0059] In this embodiment, the liquid preparation storage tank 5 is arranged between the impurity removal device 4 and the pre-concentrator 6 .

[0060] A cooler 9 for cooling the lithium manganese iron phosphate positive electrode material precursor powder is provided at the bottom of the synthesis furnace 8. The feed port of the cooler 9 is connected to the discharge port of the synthesis furnace 8. The discharge port of the synthesis furnace 8 is provided at the bottom of the furnace. A valve body is provided between the feed port of the cooler 9 and the discharge port of the synthesis furnace 8. By opening the valve body, the lithium manganese iron phosphate positive electrode material precursor powder is transferred to the cooler 9 for cooling. In this embodiment, the cooler 9 can cool the lithium manganese iron phosphate positive electrode material precursor powder at about 400°C to about 80°C.

[0061] In this embodiment, after the cooler 9 cools the lithium iron manganese phosphate positive electrode material precursor powder, a processing unit for processing the lithium iron manganese phosphate positive electrode material precursor powder is also provided. The processing unit includes a crusher 10, a demagnetizer 11, a screening machine 12, a silo 13 and a packaging machine 14 arranged in sequence. The feed port of the crusher 10 is connected to the discharge port of the cooler 9. The function of the crusher 10 is to crush the lithium iron manganese phosphate positive electrode material precursor powder to improve its particle size uniformity; the demagnetizer 11 is used to remove the crushed lithium iron manganese phosphate. Magnetic substances in the positive electrode material precursor powder; the screening machine 12 is used to screen the demagnetized lithium iron manganese phosphate positive electrode material precursor powder to screen out the lithium iron manganese phosphate positive electrode material precursor powder with a qualified particle size; the silo 13 is used to store the qualified lithium iron manganese phosphate positive electrode material precursor powder after screening; the packaging machine 14 is used to pack, heat-seal and wrap the qualified lithium iron manganese phosphate positive electrode material precursor powder; the lithium iron manganese phosphate positive electrode material precursor powder packaged by the packaging machine 14 is transported to the finished product warehouse by the transfer equipment.

[0062] The average particle size of the packaged lithium manganese iron phosphate positive electrode material precursor product in this embodiment is 1-20 μm, and the bulk density is 0.2-0.4 g / cm 3 , tap density is 0.4~0.8g / cm 3 , carbon content is less than 0.2%.

[0063] In this embodiment, the lithium iron manganese phosphate positive electrode material precursor powder is ferromanganese pyrophosphate powder or lithium iron manganese phosphate powder.

[0064] The present invention also provides a method for producing a lithium manganese iron phosphate positive electrode material precursor using the above-mentioned production equipment for the lithium manganese iron phosphate positive electrode material precursor, comprising the following steps:

[0065] S1: adding hydrochloric acid to the iron dissolution reactor 1 through the hydrochloric acid feed port, and adding an iron source to the iron dissolution reactor 1 through the iron source feed port, the iron source reacts with the hydrochloric acid to generate an iron salt solution, and the iron salt solution is transferred to the manganese dissolution reactor 2;

[0066] S2: adding a manganese source into the manganese dissolution reactor 2 through the manganese source feed port to react and generate a manganese iron salt solution;

[0067] S3: adding a reducing agent into the manganese dissolution reactor 2 through the reducing agent feed port to keep the manganese and iron in the manganese ferromanganese salt solution at a positive divalent value;

[0068] S4: transferring the manganese iron salt solution to the liquid preparation kettle 3, adding additives to the liquid preparation kettle 3 through the additive feed port to prepare a manganese iron phosphorus mixed solution or a manganese iron lithium phosphorus mixed solution;

[0069] S5: The manganese iron phosphorus mixed liquid or manganese iron lithium phosphorus mixed liquid transferred from the liquid preparation kettle 3 is removed by the impurity removal device 4 and then enters the liquid preparation storage tank 5 to test whether the mixed liquid is qualified. The unqualified mixed liquid is re-proportioned by adding additives. The qualified manganese iron phosphorus mixed liquid or manganese iron lithium phosphorus mixed liquid enters the pre-concentrator 6 for preheating and concentration. The preheated and concentrated manganese iron phosphorus mixed liquid or manganese iron lithium phosphorus mixed liquid is supplied to the synthesis furnace 8 for heating to react and generate lithium manganese iron phosphate positive electrode material precursor powder;

[0070] S6: The lithium manganese iron phosphate cathode material precursor powder is processed in sequence by the cooler 9, crusher 10, demagnetizer 11, screening machine 12, silo 13 and packaging machine 14, and then transported to the finished product warehouse.

[0071] Adaptive changes based on actual needs are all within the scope of protection of the present invention.

[0072] It should be noted that it will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the present invention. Therefore, the embodiments should be considered in all respects as illustrative and non-restrictive, and the scope of the present invention is defined by the appended claims, not the foregoing description, and it is intended that all variations within the meaning and range of equivalents of the claims be encompassed within the present invention. Any reference signs in the claims should not be construed as limiting the claim to which they relate.

[0073] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only intended to help understand the method and core concept of the present invention. At the same time, those skilled in the art will find that the specific implementation methods and application scopes may vary based on the concept of the present invention. In summary, the contents of this specification should not be construed as limiting the present invention.

Claims

1. A production device for lithium manganese iron phosphate positive electrode material precursor, characterized in that: include: An iron dissolving reactor for generating an iron salt solution; A manganese dissolution reactor for mixing an iron salt solution, a manganese source and a reducing agent to generate a manganese iron salt solution, wherein the feed port of the manganese dissolution reactor is connected to the discharge port of the iron dissolution reactor; A liquid preparation kettle for mixing the ferromanganese salt solution with an additive to generate a mixed solution, wherein the feed port of the liquid preparation kettle is connected to the discharge port of the manganese dissolution reactor, and the additive is a phosphorus source and a lithium source, or the additive is phosphoric acid; A synthesis furnace for generating a precursor of lithium manganese iron phosphate positive electrode material, wherein the feed inlet of the synthesis furnace is connected with the discharge outlet of the liquid preparation kettle.

2. The production equipment of lithium manganese iron phosphate positive electrode material precursor according to claim 1, characterized in that: The production equipment of the lithium manganese iron phosphate positive electrode material precursor also includes an impurity removal device, which is arranged between the iron dissolution reactor and the synthesis furnace, and the impurity removal device is a solid-liquid separator.

3. The production equipment of lithium manganese iron phosphate positive electrode material precursor according to claim 1, characterized in that: The production equipment of the lithium manganese iron phosphate positive electrode material precursor also includes a pre-concentrator, which includes a venturi structure and a gas-liquid separation structure. The feed port of the venturi structure is connected to the liquid preparation kettle, the discharge port is connected to the feed port of the gas-liquid separation structure, the negative pressure suction port is connected to the high-temperature flue gas channel of the synthesis furnace, and the liquid outlet of the gas-liquid separation structure is connected to the synthesis furnace.

4. The production equipment of lithium manganese iron phosphate positive electrode material precursor according to claim 3, characterized in that: The gas outlet of the gas-liquid separation structure is connected to a hydrochloric acid storage tank for storing hydrochloric acid through an absorption tower, and the hydrochloric acid storage tank is connected to a hydrochloric acid feed port of the iron dissolution reactor.

5. The production equipment of lithium manganese iron phosphate positive electrode material precursor according to claim 1, characterized in that: The liquid preparation kettle is connected to the top of the inner cavity of the synthesis furnace through an atomizing device, and the atomizing device is connected to the liquid preparation kettle, the desalted water supply pipeline and the high-pressure protective gas supply pipeline through valves respectively.

6. The production equipment of lithium manganese iron phosphate positive electrode material precursor according to claim 5, characterized in that: The synthesis furnace comprises a furnace body and a burner for ejecting a hot gas flow, wherein the burner is arranged on the furnace body.

7. The production equipment of lithium manganese iron phosphate positive electrode material precursor according to claim 1, characterized in that: The production equipment of the lithium manganese iron phosphate positive electrode material precursor also includes a liquid preparation storage tank, the feed port of the liquid preparation storage tank is connected to the liquid preparation kettle, the discharge port is connected to the synthesis furnace, and the liquid preparation storage tank is provided with a feed port for supplying the additive.

8. The production equipment of lithium manganese iron phosphate positive electrode material precursor according to claim 1, characterized in that: A cooler for cooling the lithium manganese iron phosphate positive electrode material precursor powder is arranged at the bottom of the synthesis furnace, and the feed inlet of the cooler is communicated with the discharge outlet of the synthesis furnace.

9. The production equipment of lithium iron manganese phosphate positive electrode material precursor according to claim 8, characterized in that: The production equipment of the lithium manganese iron phosphate positive electrode material precursor also includes a processing unit for processing the lithium manganese iron phosphate positive electrode material precursor powder, and the processing unit includes a crusher, a demagnetizer, a screening machine, a silo and a packaging machine arranged in sequence, and the feed port of the crusher is connected to the discharge port of the cooler.

10. A method for producing a lithium manganese iron phosphate positive electrode material precursor, characterized in that: The production equipment of the lithium manganese iron phosphate positive electrode material precursor according to any one of claims 1 to 9 comprises the following steps: S1: adding hydrochloric acid into the iron dissolution reactor through the hydrochloric acid feed port, and adding an iron source into the iron dissolution reactor through the iron source feed port, the iron source reacts with the hydrochloric acid to generate an iron salt solution, and the iron salt solution is transferred to the manganese dissolution reactor; S2: adding a manganese source into the manganese dissolution reactor through a manganese source feed port to react and generate a manganese iron salt solution; S3: adding a reducing agent into the manganese dissolution reactor through a reducing agent feed port to keep the manganese in the ferromanganese salt solution at a positive divalence and the iron at a positive divalence; S4: transferring the ferromanganese salt solution to a liquid preparation kettle, adding additives to the liquid preparation kettle through an additive feed port to prepare a manganese iron phosphorus mixed solution or a manganese iron lithium phosphorus mixed solution; S5: The manganese iron phosphorus mixed solution or the manganese iron lithium phosphorus mixed solution is supplied into the synthesis furnace for heating, and the reaction generates ferromanganese pyrophosphate powder or lithium iron manganese phosphate powder, and the ferromanganese pyrophosphate powder or lithium iron manganese phosphate powder is the precursor powder of lithium iron manganese phosphate positive electrode material.

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