System and method for continuously and efficiently preparing iron phosphate

Abstract

A system and method for continuously and efficiently preparing iron phosphate. The system comprises a multifunctional tower (1), wherein a feeding unit (2), an enhancement reaction unit (3) and an aging unit (4) are sequentially provided in the multifunctional tower (1) from top to bottom; the feeding unit (2) comprises a feeding valve (201) and a circulation pump for realizing continuous feeding; the enhancement reaction unit (3) comprises an enhancer set (301) for enhancing the mass and heat transfer effect of reaction materials in the multifunctional tower (1); the aging unit (4) comprises a switching-type up-down countercurrent device (401) for performing uniform stress grinding on a reaction product; the switching-type up-down countercurrent device (401) comprises an upper circulation pipe (4011) and a lower circulation pipe (4012), an end portion of the upper circulation pipe (4011) is provided with a first distribution disc (4013), an end portion of the lower circulation pipe (4012) is provided with a second distribution disc (4014), and an outlet of the first distribution disc (4013) is arranged opposite to an outlet of the second distribution disc (4014). The system can improve the mass transfer effect between the reaction materials and improve the reaction efficiency, and can obtain a high-quality iron phosphate product.

Description

A system and method for continuously and efficiently preparing iron phosphate Technical Field The invention belongs to the technical field of iron phosphate production, and in particular to a system and method for continuously and efficiently preparing iron phosphate. Background Art As people pay more and more attention to the safety of new energy vehicles, lithium iron phosphate stands out among many lithium battery materials due to its high safety characteristics and has been greatly sought after by the market. Iron phosphate and lithium iron phosphate belong to the same orthorhombic crystal system, which makes the structure stable during the insertion and extraction of lithium. In addition, iron phosphate contains both iron source and phosphorus source. During the synthesis process, lithium iron phosphate can be prepared by introducing lithium source through lithium phosphate or lithium hydroxide. The performance indicators of the precursor iron phosphate (morphology, iron-phosphorus ratio, particle size, impurity element content, specific surface area, etc.) have a significant impact on the electrochemical properties of lithium iron phosphate battery materials. The preparation technology of iron phosphate is of great significance to the electrochemical properties of lithium iron phosphate positive electrode materials and the industrial application of lithium iron phosphate batteries. At present, most industrial iron phosphate preparation technologies use intermittent reactors. The iron phosphate crystals produced by traditional production processes are mostly flaky structures with poor and irregular agglomerate size consistency and low crystal specific surface area. At the same time, the reaction efficiency of preparing iron phosphate is low and the raw material conversion rate is low. Therefore, the rapid and efficient production of high-quality iron phosphate is a technical problem that needs to be solved urgently. In view of this, the present invention is proposed. Summary of the invention The first purpose of the present invention is to provide a system for continuously and efficiently preparing iron phosphate. The system adds an intensification unit in the intensified reaction unit, and the intensification unit is used to circulate and stir the liquid in the multifunctional tower to improve the mass transfer effect between the reaction materials and improve the reaction efficiency; at the same time, an aging unit is set to uniformly grind the reaction product to obtain a high-quality iron phosphate product. The second object of the present invention is to provide a method for preparing ferric phosphate using the above-mentioned system for preparing ferric phosphate. The method is simple to operate, has milder operating conditions, and has low energy consumption, achieving a better processing effect than the prior art process. In order to achieve the above-mentioned purpose of the present invention, the following technical solutions are particularly adopted: The present invention provides a system for continuously and efficiently preparing ferric phosphate, comprising: A multifunctional tower, wherein a feeding unit, an enhanced reaction unit and an aging unit are sequentially arranged from top to bottom in the multifunctional tower; The feeding unit includes a feeding valve and a circulating pump to achieve continuous feeding; The enhanced reaction unit includes an enhanced unit for enhancing the mass and heat transfer effects of the reaction materials in the multifunctional tower; The aging unit includes a switching type up-and-down reversible flow device to evenly apply force to grind the reaction product; The switching type up-and-down reversible flow device includes an upper circulation pipeline and a lower circulation pipeline. A first distribution plate is arranged at the end of the upper circulation pipeline, a second distribution plate is arranged at the end of the lower circulation pipeline, and the outlets of the first distribution plate and the second distribution plate are arranged opposite to each other. In the prior art, the following problems mainly exist in the preparation of iron phosphate: The traditional process for preparing iron phosphate uses an intermittent autoclave reactor. The iron phosphate crystals produced by traditional industrial production mostly have a flaky structure, with inconsistent and irregular aggregate sizes, a low specific surface area of the crystals, and the intermittent autoclave reactor is for intermittent production, resulting in low reaction efficiency and low raw material conversion rate. To solve the above technical problems, the present invention provides a system for continuously and efficiently preparing iron phosphate. The overall structure of the system is simple. By arranging a strengthening unit in the multi-functional tower, the mass transfer and heat transfer effects of the reaction materials in the multi-functional tower can be enhanced, the temperature and material concentration distribution in the reaction section are made uniform, and high-efficiency synthesis of high-quality iron phosphate is realized; at the same time, an aging unit is arranged below the strengthening reaction unit. Through the switching type up-and-down reversible flow device arranged in the aging unit, the product particles in the slurry in the multi-functional tower are evenly ground without dead angles, forming ideal spherical-like particles and appropriate particle sizes, and improving the product quality. Preferably, a number of nozzles are respectively arranged on the first distribution plate and the second distribution plate. The nozzles of the first distribution plate are arranged at both ends of the first distribution plate, and the nozzles on the second distribution plate are arranged at the middle part of the second distribution plate. By arranging nozzles at the ends of the first distribution plate and the second distribution plate and arranging the nozzles alternately, the slurry coming out of the nozzles can be ejected alternately from the upper and lower parts, so that the product crystals are evenly ground from different directions in the slurry, forming ideal spherical-like particles and improving the product quality. Preferably, the strengthening unit includes a hydraulic strengthening reactor. The inlet of the hydraulic strengthening reactor is connected to the feeding unit. A conveying pipeline is arranged below the hydraulic reactor, and the conveying pipeline extends above the second distribution plate. Preferably, the strengthening unit further includes a sieve plate arranged above the hydraulic strengthening reactor. A first liquid extraction port is arranged above the sieve plate, and the liquid coming out of the first liquid extraction port returns to the inlet of the hydraulic strengthening reactor through a circulation pipeline and a circulation pump. Preferably, a grid is arranged below the hydraulic strengthening reactor. A second liquid extraction port is arranged above the grid, and the second liquid extraction port is respectively connected to the upper circulation pipeline and the lower circulation pipeline. Preferably, the second liquid extraction port is connected to the product outlet. Preferably, an outlet valve is provided on the hydraulic intensification reactor and the conveying pipeline, and a spray gun is provided at the end of the conveying pipeline. By providing the spray gun, the liquid material can be ejected and energy can be transmitted, so that the liquid material in the intensification reaction unit is fully stirred and mixed. Preferably, a gas outlet is provided at the top of the multi-functional tower, and the gas outlet is communicated with a reflux pipeline and a heat exchanger to condense and separate the generated gas; Preferably, the reflux pipeline is connected to the circulation pipeline to return the condensed ammonia water to the reaction system. In the present invention, by providing a feeding unit, continuous feeding can be realized, and the production efficiency can be improved. By providing an intensification reaction unit and an aging unit, high-quality iron phosphate can be efficiently prepared. Specifically, The intensification reaction unit is provided with an intensification unit to realize full stirring and mixing of the reaction materials in the reaction unit, so that the concentration and temperature are evenly distributed. A switching type up-and-down reversible flow device is provided in the aging unit, so that the iron phosphate particles are fully mixed evenly during the generation process by force movement and spin movement, and high-quality spherical iron phosphate products are obtained. The switching type up-and-down reversible flow device controls the spraying time of the liquid material from the nozzles of the upper and lower two circulation pipelines by switching the valve switches on the upper and lower two circulation pipelines, adjusts the flow direction of the slurry in the aging unit, and evenly grinds the product particles without dead angles through the flow of the slurry in different directions. When specifically designing the switching type up-and-down reversible flow device of the present invention, an upper distribution plate and a lower distribution plate are provided, and the two distribution plates are arranged on the same straight line. The advantage of this setting is that it can ensure that the slurry can smoothly move upward or downward during the switching operation, and the opposite setting of the distribution plates can reduce the dead zone of fluid flow and ensure more uniform distribution of the slurry in the aging unit. In addition, nozzles are provided on the distribution plates to enable the slurry to be ejected from the distribution plates in a spray shape. By using the distribution plates and nozzles in combination, not only the distribution effect of the slurry in the multi-functional tower is improved, but also the mixing effect of the slurry is improved, making the slurry mixing more uniform and improving the product quality. When specifically designing the present invention, the nozzles of the upper distribution plate are arranged on both sides of the upper distribution plate, and the nozzles of the lower distribution plate are arranged in the middle position of the lower distribution plate. The advantage of this design is that by using the nozzles on both sides of the distribution plate and the nozzles in the middle of the lower distribution plate in combination, the hydrodynamics of the entire system is coordinated to ensure the optimization of the dynamic characteristics when the fluid enters, passes through and leaves the multi-functional tower, thereby improving the overall efficiency and performance; and the nozzles on both sides of the upper distribution plate realize uniform distribution of the slurry during the slurry inlet and end outflow stages, and the nozzles in the middle of the lower distribution plate quickly stir during the slurry mixing process. By using the nozzles of the upper distribution plate and the nozzles of the lower distribution plate in combination, the turbulence during the slurry flow process is reduced, thereby improving the efficiency and reaction speed. In the system for continuously and efficiently preparing iron phosphate according to the present invention, by respectively arranging two sampling outlets on the side wall of the multi-functional tower, the concentration of the discharge outlet can be adjusted. At the same time, the sampling outlet located above is used in cooperation with the sieve plate to intercept the reaction materials, so that the sampling outlet extracts clear liquid; the sampling outlet located in the middle is used in cooperation with the grid to intercept particulate matters, and at the same time ensure that the sampling outlet extracts clear liquid, avoiding waste of resources. Those skilled in the art can understand that the enhanced reactor adopted in the present invention has been reflected in the prior patents of the present inventor, such as the patents with application numbers CN201610641119.6, CN201610641251.7, CN201710766435.0, CN106187660, CN105903425A, CN109437390A, CN205833127U and CN207581700U. The specific product structure and working principle of the microbubble generator (i.e., the enhanced reactor) are introduced in detail in the prior patent CN201610641119.6. The application document records that "the microbubble generator includes a main body and a secondary fragmentation member. There is a cavity in the main body. The main body is provided with an inlet communicating with the cavity. The opposite first end and second end of the cavity are both open. Among them, the cross-sectional area of the cavity decreases from the middle of the cavity to the first end and the second end of the cavity; the secondary fragmentation member is arranged at at least one of the first end and the second end of the cavity. A part of the secondary fragmentation member is arranged in the cavity. An annular channel is formed between the secondary fragmentation member and the through holes open at both ends of the cavity. The microbubble generator also includes an air inlet pipe and a liquid inlet pipe." From the specific structure disclosed in this application document, its specific working principle can be known: the liquid tangentially enters the microbubble generator through the liquid inlet pipe, rotates at a super high speed and cuts the gas, so that the gas bubbles are broken into microbubbles of micron size, thereby increasing the mass transfer area between the liquid phase and the gas phase. Moreover, the microbubble generator in this patent belongs to a pneumatic enhanced reactor. In addition, the prior patent 201610641251.7 records that the primary bubble breaker has a circulating liquid inlet, a circulating gas inlet and a gas-liquid mixture outlet, and the secondary bubble breaker connects the feed port with the gas-liquid mixture outlet, indicating that the bubble breaker requires gas-liquid mixture to enter. In addition, it can be seen from the following drawings that the primary bubble breaker mainly uses circulating liquid as power, so in fact the primary bubble breaker belongs to a hydraulic enhanced reactor, and the secondary bubble breaker simultaneously passes the gas-liquid mixture into an elliptical rotating ball for rotation, thereby achieving bubble breaking during the rotation process, so the secondary bubble breaker actually belongs to a gas-liquid linkage enhanced reactor. In fact, whether it is a hydraulic enhanced reactor or a gas-liquid linkage enhanced reactor, it is a specific form of an enhanced reactor. However, the enhanced reactor adopted by the present invention is not limited to the above-mentioned forms. The specific structure of the bubble breaker recorded in the prior patent is only one of the forms that can be adopted by the enhanced reactor of the present invention. In addition, the prior patent 201710766435.0 states that "the principle of the bubble breaker is to use high-speed jets to achieve mutual collision of gases", and also explains that it can be used in a micro-interface enhanced reactor, verifying the correlation between the bubble breaker and the micro-interface generator; and the prior patent CN106187660 also has relevant records on the specific structure of the bubble breaker, see the specification for details. -

[0041] The section, as well as the attached drawings, provide a detailed explanation of the specific working principle of the bubble breaker S-2. The top of the bubble breaker is a liquid phase inlet, and the side is a gas phase inlet. The liquid phase coming in from the top provides suction power, thereby achieving the effect of crushing into ultra-fine bubbles. It can also be seen in the attached drawings that the bubble breaker has a conical structure, and the diameter of the upper part is larger than that of the lower part, so that the liquid phase can better provide suction power. Since the enhanced reactor was just developed in the early stage of the prior patent application, it was named micron bubble generator (CN201610641119.6), bubble breaker (201710766435.0), etc. in the early stage. With the continuous technical improvement, it was later renamed as enhanced reactor. Now the enhanced reactor in the present invention is equivalent to the previous micron bubble generator, bubble breaker, etc., but the name is different. In summary, the enhanced reactor of the present invention belongs to the prior art. Preferably, the system for continuously and efficiently preparing iron phosphate of the present invention also includes a filter scrubber and a rotary kiln, wherein the filter scrubber is connected to the multifunctional tower for washing and drying the reaction product, and the rotary kiln is connected to the filter scrubber for calcining the reaction product. Preferably, a pressure monitoring device is provided inside the rotary kiln for controlling the pressure inside the rotary kiln. By setting up a filtration washer, the slurry drawn from the multi-functional tower can be filtered, and the product can be washed to remove soluble impurities and most of the water; by setting up a rotary kiln, the product can be made to have a pore structure, improving the product quality. At the same time, a pressure monitoring device is arranged inside the rotary kiln, which can monitor and control the pressure inside the rotary kiln, control the pore structure of the product, and rapidly reduce the pressure at the kiln outlet to make the product have a honeycomb-like pore structure. In addition, the present invention also provides a method for continuously and efficiently preparing iron phosphate, using the above-mentioned system to prepare iron phosphate. Preferably, the method for preparing iron phosphate includes the following steps: after the divalent iron salt and ammonium hydrogen phosphate are subjected to an oxidation reaction with hydrogen peroxide, ammonia gas is introduced for an intensification reaction. After the crude product is formed, deionized water is introduced for an aging reaction, and finally iron phosphate is obtained by calcination. Preferably, the reaction temperature during the aging reaction is 90 - 100 °C, and the reaction pressure is 0.9 - 1.1 atm; The reaction temperature during the calcination is 550 - 650 °C, and the reaction pressure is 1 - 2.5 atm. The preparation method of the present invention is simple to operate, the operating conditions are milder, and the product quality is higher. Compared with the prior art, the beneficial effects of the present invention are as follows: (1) In the present invention, an intensification reaction unit is arranged in the multi-functional tower. By adding an intensification unit in the intensification reaction unit and cooperating with the side-line circulation pipeline, the liquid in the multi-functional tower can be circulated and stirred, improving the mass transfer effect between the reaction materials and enhancing the reaction efficiency. (2) The aging unit of the present invention is arranged below the intensification reaction unit. By arranging a switching type up-and-down reversible flow device in the aging unit and cooperating with the intensification unit, the slurry can be alternately sprayed from the upper and lower nozzles, enabling the product particles to be uniformly stressed and ground without dead corners, forming ideal spherical-like particles and appropriate sizes for the product particles, and improving the product quality. (3) The present invention has a pressure monitoring and control device at the tail gas outlet of the rotary kiln, and the product has a honeycomb-like pore structure by controlling the slightly high pressure inside the rotary kiln and the rapid reduction of the pressure at the kiln outlet. BRIEF DESCRIPTION OF THE DRAWINGS By reading the detailed description of the preferred embodiments below, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings: FIG. 1 is a schematic structural diagram of a system for continuously and efficiently preparing iron phosphate provided in Embodiment 1 of the present invention; FIG. 2 is a partially enlarged view of the slurry flow in the aging unit provided in Embodiment 1 of the present invention. Wherein: 1 - Multi-functional tower; 2 - Feeding unit; 201 - Feeding valve; 3 - Enhanced reaction unit; 301 - Enhancement unit; 302 - Hydraulic enhanced reactor; 303 - Conveying pipeline; 3031 - Spray gun; 3032 - Outlet valve; 304 - Sieve plate; 305 - First liquid extraction outlet; 306 - Circulation pipeline; 307 - Grid; 308 - Second liquid extraction outlet; 4 - Aging unit; 401 - Up-and-down reversible flow device; 4011 - Upper circulation pipeline; 4012 - Lower circulation pipeline; 4013 - First distribution plate; 4014 - Second distribution plate; 4015 - Nozzle; 5 - Gas outlet; 6 - Return pipeline; 7 - Heat exchanger; 8 - Filter washer; 9 - Rotary kiln; 901 - Pressure monitoring and control device. Detailed implementation manners The technical solutions of the present invention will be clearly and completely described below in conjunction with the accompanying drawings and specific implementation manners. However, those skilled in the art will understand that the following described embodiments are part of the embodiments of the present invention, rather than all embodiments, and are only used to illustrate the present invention and should not be construed as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts fall within the scope of protection of the present invention. Conditions not specified in the embodiments are carried out according to conventional conditions or conditions recommended by the manufacturer. Reagents or instruments not specified by the manufacturer are all conventional products that can be obtained through commercial purchase. In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present invention. In addition, the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance. In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "installation", "connection", and "coupling" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances. In order to more clearly elaborate on the technical solutions in the present invention, the following will be described in the form of specific embodiments. Embodiment 1 Referring to FIGS. 1-2, a system for continuously and efficiently preparing iron phosphate according to an embodiment of the present invention includes a multi-functional tower 1. Inside the multi-functional tower 1, a feeding unit 2, a strengthening reaction unit 3, and an aging unit 4 are sequentially arranged from top to bottom; the feeding unit 2 includes a feeding valve 201 and a circulation pump to achieve continuous feeding; the strengthening reaction unit 3 includes a strengthening unit 301 for enhancing the mass transfer and heat transfer effects of the reaction materials inside the multi-functional tower 1; specifically, the strengthening unit 301 includes a hydraulically actuated strengthening reactor 302. The inlet of the hydraulically actuated strengthening reactor 302 is connected to the feeding unit 2. A conveying pipeline 303 is arranged below the hydraulically actuated strengthening reactor 302, and the conveying pipeline 303 extends downward to the aging unit 4. Specifically, the conveying pipeline 303 is funnel-shaped to collect and convey the slurry to the aging unit 4; a sieve plate 304 is arranged above the hydraulically actuated strengthening reactor 302, and a first liquid extraction port 305 is arranged above the sieve plate 304. The liquid coming out of the first liquid extraction port 305 returns to the inlet of the hydraulically actuated strengthening reactor 302 through a circulation pipeline 306 and a circulation pump; a grid 307 is arranged below the hydraulically actuated strengthening reactor 302, and a second liquid extraction port 308 is arranged above the grid 307. The second liquid extraction port 308 is connected to the product outlet. The aging unit 4 of the present invention includes a switching up-and-down reversible flow device 401 to uniformly apply force to grind the reaction product. Specifically, the switching up-and-down reversible flow device 401 includes an upper circulation pipeline 4011 and a lower circulation pipeline 4012. A first distribution plate 4013 is provided at the end of the upper circulation pipeline 4011, and a second distribution plate 4014 is provided at the end of the lower circulation pipeline 4012. The outlets of the first distribution plate 4013 and the second distribution plate 4014 are arranged opposite to each other. Among them, a number of nozzles 4015 are respectively provided on the first distribution plate 4013 and the second distribution plate 4014. The nozzles 4015 of the first distribution plate 4013 are arranged at both ends of the first distribution plate 4013, and the nozzles 4015 on the second distribution plate 4014 are arranged in the middle part of the second distribution plate 4014. When the present invention is specifically arranged, an outlet valve 3032 is provided on the conveying pipeline 303, and a spray gun 3031 is provided at the end of the conveying pipeline 303. The spray gun 3031 sprays the slurry flowing out of the conveying pipeline 303 to increase the stirring rate between the reaction materials and improve the reaction conversion rate; the second liquid extraction port 308 is respectively connected to the upper circulation pipeline 4011 and the lower circulation pipeline 4012 to circulate the extracted materials to the multifunctional tower 1 for continuous reaction. In this embodiment, a gas outlet 5 is provided at the top of the multifunctional tower 1. The gas outlet 5 is communicated with a reflux pipeline 6 and a heat exchanger 7 to condense and separate the generated gas; the reflux pipeline 6 is connected to a circulation pipeline to return the condensed ammonia water to the reaction system. In this embodiment, the system for preparing iron phosphate further includes a filter washer 8 and a rotary kiln 9. The filter washer 8 is connected to the multifunctional tower 1 to wash and dry the reaction product. Specifically, the filter washer 8 is connected to the product outlet; the rotary kiln 9 is connected to the filter washer 8 to calcine the reaction product. A pressure monitoring and control device 901 is provided inside the rotary kiln 9 to control the pressure inside the rotary kiln 9. When the system for preparing iron sulfate of the present invention is actually applied, it includes the following technological process: The raw materials from the upstream storage tank enter the enhanced reaction unit 3 in the multi-functional tower 1 through the feed pump. First, hydrogen peroxide is introduced for oxidation, and then ammonia water is introduced for the reaction stage. The generated gas is condensed by the heat exchanger 7 after passing through the gas outlet 5 at the top of the tower and then separated. The separated oxygen is discharged from above, and the condensed ammonia water re-enters the multi-functional tower 1 through the circulation pump to continue participating in the reaction. The clear liquid drawn from the first liquid extraction port 305 of the multi-functional tower 1 enters the hydraulic enhanced reactor 302 in the multi-functional tower 1 together with the condensed ammonia water through the heat exchanger 7 and the circulation pump to enhance the mass transfer efficiency and reaction rate in the reactor. The sieve plate 304 provided above the enhanced unit 301 enriches the products generated by the reaction. The products generated by the reaction and part of the feed liquid form a turbid slurry and flow into the aging unit 4 of the multi-functional tower 1 through the conveying pipeline 303. The flow rate of the slurry is controlled by the outlet valve 3032. A grid is provided below the reactor slurry outlet valve 3032, and a second liquid extraction port 308 is provided above the grid. The relatively clear washing liquid is drawn from here. Deionized water enters the aging unit 4 of the multi-functional tower 1 through the conveying pump and the extracted slurry together through the switching type up-and-down reversible flow device 401. The switching type up-and-down reversible flow device 401 can make the product crystals be uniformly stressed and ground in the slurry without dead angles of 360°, forming ideal spherical product particles. After the slurry is drawn from the product outlet, it is filtered, washed, and dried, and finally calcined in the rotary kiln 9. The pressure in the rotary kiln 9 is controlled by the pressure monitoring and control device 901, and the concentration of the product slurry drawn from the discharge port is adjusted by adjusting the extraction ratio of the washing liquid and the slurry. At the same time, the residual materials in the multi-functional tower 1 are discharged through the vent port. Example 2 The difference between this example and Example 1 is only that only a downward reversible flow device is provided. Example 3 The difference between this example and Example 1 is only that only an upward reversible flow device is provided. Example 4 The difference between this example and Example 1 is only that the nozzles on the first distribution plate and the second distribution plate are symmetrically arranged. Comparative Example 1 The difference between this example and Example 1 is only that no up-and-down reversible flow device is provided. Comparative Example 2 The difference between this example and Example 1 is only that no hydraulic enhanced reactor is provided. Comparative Example 3 The difference between this example and Example 1 is only that no pressure monitoring and control device is provided. Comparative Example 4 In this example, the prior art is adopted, and ammonia water, hydrogen peroxide, phosphoric acid, and ferrous sulfate are directly introduced into the batch reactor for oxidation reaction, and then deionized water is introduced for washing, drying, and calcining. Experimental Example 1 Using the systems of Examples 1-4 and Comparative Examples 1-3 respectively to prepare iron phosphate, the product parameters are as follows: Table 1 Product Parameters When preparing iron phosphate by the prior art, the compaction of the prepared lithium iron sulfate is usually about 1.5 g / m 3 or so, among which, the sulfur content is about 250 ppm, the magnesium content is about 25 ppm, the aluminum content is 70 ppm, and the specific surface area is 4.8 m 2 / g, and the true density is 0.75 g / m 3 . It can be seen from Table 1 that compared with the existing batch reactor, the compaction of the lithium iron sulfate in each embodiment of the present invention has increased significantly, and the compaction of the lithium iron sulfate in Example 1 has increased by nearly 1 g / m 3 , and the sulfur content, magnesium content and aluminum content in Example 1 are significantly reduced, significantly improving the product quality. It can be seen from Table 1 that Example 1 of the present invention is the optimal example. The system of this example uses the strengthening unit and the up-and-down reversible flow device in combination, and the product quality of the obtained lithium iron phosphate is significantly higher than that of the lithium iron phosphate prepared by the prior art; at the same time, the compaction of the lithium iron phosphate is significantly improved, indicating that the combination setting method of the strengthening unit and the up-and-down reversible flow device in Example 1 can achieve the optimal reaction effect. It can be seen that the preparation system of this example has low reaction energy consumption and good preparation effect. Among them, the compaction of the lithium iron phosphate in Comparative Example 1 is lower than that in Example 1, because the up-and-down reversible flow device is not set in Comparative Example 1, and it cannot grind the crude product iron phosphate in the multi-functional tower. It can be seen that Example 1 of the present invention designs the setting method of the up-and-down reversible flow device in the multi-functional tower, improving the quality of iron phosphate. In summary, compared with the prior art, the continuous and efficient iron phosphate preparation system of the present invention has a high raw material conversion rate and a high product yield, and is worthy of wide promotion and application. The present invention also provides a method for continuously and efficiently preparing iron phosphate, including the following steps: After the divalent iron salt and ammonium hydrogen phosphate are subjected to an oxidation reaction with hydrogen peroxide, ammonia gas is introduced for an intensification reaction. After the crude product is formed, deionized water is introduced for an aging reaction, and finally iron phosphate is obtained by calcination. Among them, the reaction temperature during the aging reaction is 90-100 °C, and the reaction pressure is 0.9-1.1 atm; The reaction temperature during calcination is 550-650 °C, and the reaction pressure is 1-2.5 atm. Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A system for continuously and efficiently preparing iron phosphate, characterized in that, Comprising: A multi-functional tower, in which a feeding unit, a strengthening reaction unit and an aging unit are sequentially arranged from top to bottom; The feeding unit includes a feeding valve and a circulation pump to achieve continuous feeding; The strengthening reaction unit includes a strengthening unit to enhance the mass transfer and heat transfer effects of the reaction materials in the multi-functional tower; The aging unit includes a switching type up-and-down reversible flow device to uniformly apply force to grind the reaction product; The switching type up-and-down reversible flow device includes an upper circulation pipeline and a lower circulation pipeline. A first distribution plate is arranged at the end of the upper circulation pipeline, a second distribution plate is arranged at the end of the lower circulation pipeline, and the outlets of the first distribution plate and the second distribution plate are arranged opposite to each other.

2. The system for continuously and efficiently preparing iron phosphate according to claim 1, wherein A number of nozzles are respectively arranged on the first distribution plate and the second distribution plate. The nozzles on the first distribution plate are arranged at both ends of the first distribution plate, and the nozzles on the second distribution plate are arranged at the middle part of the second distribution plate.

3. The system for continuously and efficiently preparing iron phosphate according to claim 1, characterized in that, The strengthening unit includes a hydraulically actuated strengthening reactor. The inlet of the hydraulically actuated strengthening reactor is connected to the feeding unit, and a conveying pipeline is arranged below the hydraulically actuated reactor and extends above the second distribution plate.

4. The system for continuously and efficiently preparing iron phosphate according to claim 3, wherein, The strengthening unit further includes a sieve plate arranged above the hydraulically actuated strengthening reactor. A first liquid extraction port is arranged above the sieve plate, and the liquid coming out of the first liquid extraction port returns to the inlet of the hydraulically actuated strengthening reactor through a circulation pipeline and a circulation pump.

5. The system for continuously and efficiently preparing iron phosphate according to claim 3, wherein A grid is arranged below the hydraulically actuated strengthening reactor, and a second liquid extraction port is arranged above the grid. The second liquid extraction port is respectively connected to the upper circulation pipeline and the lower circulation pipeline; Preferably, the second liquid extraction port is connected to a product outlet.

6. The system for continuously and efficiently preparing iron phosphate according to claim 3, wherein An outlet valve is arranged on the conveying pipeline, and a spray gun is arranged at the end of the conveying pipeline.

7. The system for continuously and efficiently preparing iron phosphate according to claim 4, wherein A gas outlet is arranged at the top of the multi-functional tower, and the gas outlet is communicated with a reflux pipeline and a heat exchanger to condense and separate the generated gas; Preferably, the reflux pipeline is connected to the circulation pipeline to return the condensed ammonia water to the reaction system.

8. The system for continuously and efficiently preparing iron phosphate according to claim 1, wherein, It further includes a filter washer and a rotary kiln. The filter washer is connected to the multi-functional tower to wash and dry the reaction product, and the rotary kiln is connected to the filter washer to calcine the reaction product; Preferably, a pressure monitoring device is arranged inside the rotary kiln to control the pressure inside the rotary kiln.

9. A method for preparing iron phosphate by using the system for continuously and efficiently preparing iron phosphate according to any one of claims 1-8, characterized in that, Including the following steps: After subjecting ferrous salt and ammonium hydrogen phosphate to an oxidation reaction with hydrogen peroxide, ammonia gas is introduced for a strengthening reaction. After generating a crude product, deionized water is introduced for an aging reaction, and finally iron phosphate is obtained by calcination.

10. The method for continuously and efficiently preparing iron phosphate according to claim 9, characterized in that, The reaction temperature during the aging reaction is 90 - 100 °C, and the reaction pressure is 0.9 - 1.1 atm; The reaction temperature during the calcination is 550 - 650 °C, and the reaction pressure is 1 - 2.5 atm.

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