Continuous lithium iron phosphate precursor reaction device and reaction synthesis method

Abstract

The invention relates to the technical field of iron phosphate preparation, in particular to a continuous lithium iron phosphate precursor reaction device and a reaction synthesis method. The device comprises a first feeding assembly, a second feeding assembly, a mixed feeding assembly and a plurality of reaction kettles which are sequentially connected in series in the feeding direction, the first feeding assembly, the second feeding assembly and the mixed feeding assembly are all communicated with the first reaction kettle in the feeding direction; every two adjacent reaction kettles are communicated through a connecting pipeline; and a material conveying pump and a material conveying flow meter are arranged on the connecting pipeline. The method adopts the device to continuously synthesize the lithium iron phosphate precursor. The continuous large-scale reaction kettle system can be provided, the problems that the crystal structure is difficult to regulate and control and the product quality does not reach the standard can be solved, and stable, efficient and continuous production of the lithium iron phosphate precursor iron phosphate product is promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of iron phosphate preparation, and in particular to a continuous lithium iron phosphate precursor reaction device and a reaction synthesis method. Background Art

[0002] With the large-scale commercial application of lithium iron phosphate materials in the fields of power batteries and energy storage, it is necessary to increase the production capacity of lithium iron phosphate. However, the industrial synthesis technology of iron phosphate, the precursor of lithium iron phosphate materials, has become the biggest constraint on the rapid expansion of lithium iron phosphate production capacity. The reaction vessel and its supporting equipment for completing the industrial iron phosphate synthesis controllable technology are iron phosphate reactor systems, which are one of the most critical equipment links in iron phosphate synthesis technology. In order to expand the production capacity of iron phosphate, it has become a development trend to gradually and continuously scale up the reactor system. However, in the actual debugging and trial production process, the continuous large-scale reactor system often encounters problems such as difficulty in crystal structure control and substandard product quality.

[0003] In summary, it is necessary to develop a continuous lithium iron phosphate precursor reaction device and reaction synthesis method, which can not only provide a continuous large-scale reactor system, but also solve the problems of difficult crystal structure control and substandard product quality. Summary of the invention

[0004] The object of the present invention is to provide a continuous lithium iron phosphate precursor reaction device and reaction synthesis method, and the specific technical scheme is as follows:

[0005] In a first aspect, the present invention provides a continuous lithium iron phosphate precursor reaction device, comprising a first feeding assembly, a second feeding assembly, a mixed feeding assembly, and a plurality of reaction kettles sequentially arranged in series along a feeding direction;

[0006] Two adjacent reactors are connected via a connecting pipeline; a feed pump and a feed flow meter are arranged on the connecting pipeline;

[0007] The first feed assembly comprises a first feed pipeline, a first feed pump and a first feed flowmeter; the first feed pump and the first feed flowmeter are arranged on the first feed pipeline; the second feed assembly comprises a second feed pipeline, a second feed pump and a second feed flowmeter; the second feed pump and the second feed flowmeter are arranged on the second feed pipeline; the first feed pipeline and the second feed pipeline are both connected to the first reactor along the feed direction;

[0008] The mixed feed assembly includes a static mixer, a third feed assembly, a fourth feed assembly and a mixed feed pipeline; the third feed assembly includes a third feed pipeline, a third feed pump and a third feed flowmeter; the third feed pump and the third feed flowmeter are arranged on the third feed pipeline; the fourth feed assembly includes a fourth feed pipeline, a fourth feed pump and a fourth feed flowmeter; the fourth feed pump and the fourth feed flowmeter are arranged on the fourth feed pipeline; a feed port and a discharge port are arranged on the static mixer, the feed port is connected to the third feed pipeline and the fourth feed pipeline, and the discharge port is connected to the first reactor along the feeding direction through the mixed feed pipeline;

[0009] A stirring component is arranged inside each of the reaction kettles, and a stirring driving component is arranged outside each of the reaction kettles. The output end of the stirring driving component is connected to the stirring component.

[0010] Optionally, the continuous lithium iron phosphate precursor reaction device also includes a heating device and multiple preheating components; the preheating component is arranged on the outer wall of each of the reaction kettles; the preheating component is arranged on the outer wall of each of the connecting pipelines; and each of the preheating components is connected to the heating device.

[0011] Optionally, the preheating component includes an insulation layer and a heat pipe; the heat pipe is spirally arranged on the outer wall of each reaction kettle; the heat pipe is spirally arranged on the outer wall of each connecting pipeline; the heat pipe is connected to the heating equipment; and the insulation layer is arranged on the outer wall of the heat pipe.

[0012] Optionally, the continuous lithium iron phosphate precursor reaction device further includes a plurality of temperature sensors; the temperature sensors are arranged in each of the reaction kettles; the temperature sensors are arranged in each of the connecting pipelines; each of the temperature sensors is connected to the heating equipment;

[0013] The continuous lithium iron phosphate precursor reaction device also includes multiple liquid level sensors and a main controller; the liquid level sensor is set in each of the reactors; the main controller includes a PLC controller, and is connected to each of the liquid level sensors, the heating equipment, the feed pump, the feed flowmeter, the first feed pump, the first feed flowmeter, the second feed pump, the second feed flowmeter, the static mixer, the third feed pump, the third feed flowmeter, the fourth feed pump, the fourth feed flowmeter and the stirring drive.

[0014] Optionally, the continuous lithium iron phosphate precursor reaction device also includes multiple pneumatic control valves; the pneumatic control valves are arranged on the first feed pipeline, the second feed pipeline, the third feed pipeline, the fourth feed pipeline and each connecting pipeline; each pneumatic control valve is connected to the PLC controller.

[0015] Optionally, the continuous lithium iron phosphate precursor reaction device also includes multiple pneumatic switching valves; the pneumatic switching valves are arranged on the first feed pipeline, the second feed pipeline, the third feed pipeline, the fourth feed pipeline and each connecting pipeline; each pneumatic switching valve is connected to the PLC controller.

[0016] In a second aspect, the present invention provides a reaction synthesis method of the continuous lithium iron phosphate precursor reaction device, comprising:

[0017] Step S1: Use the first feeding component to feed an iron salt solution with a mass concentration of 10 to 80 g / L at a flow rate of 2 to 12 m 3 / h feeding; using the second feeding component to feed the phosphate solution with a mass concentration of 10 to 80 g / L at a flow rate of 2 to 12 m 3 / h feeding; using the third feeding component to feed 3% to 30% of the oxidizing liquid at a flow rate of 0.1 to 1.0 m 3 / h feeding, using the fourth feeding assembly to feed 5% to 100% of the pH adjusting liquid at a flow rate of 0.1 to 1.0 m 3 / h feeding, the oxidizing liquid and the pH regulating liquid are synchronously fed into the static mixer, and after being mixed by the static mixer to form a mixed liquid, the mixed liquid is fed into the first reactor along the feeding direction through the mixed feeding pipeline; the iron salt solution, the phosphate salt solution and the mixed liquid are synchronously fed into the first reactor along the feeding direction;

[0018] The heating device and the preheating component are used to preheat the liquid in each of the reactors and each of the connecting pipelines to a target temperature, and the temperature of the liquid in each of the reactors and each of the connecting pipelines is monitored in real time by the temperature sensor; when the monitored temperature is lower than the target temperature, the heating temperature of the preheating component is increased by the heating device until the monitored temperature reaches the target temperature;

[0019] Step S2, when the liquid in the first reactor along the feeding direction exceeds 15% of the liquid level therein, start the stirring component in the first reactor to stir the liquid, so that the liquid gradually reacts to synthesize ferric phosphate; when the liquid in the first reactor along the feeding direction exceeds 60% of the liquid level therein, use the connecting pipeline to introduce the liquid into the second reactor arranged along the feeding direction, and when the liquid in the second reactor exceeds 15% of the liquid level therein, start the stirring component in the second reactor to stir the liquid. liquid, so that the incompletely reacted liquid continues to react to synthesize ferric phosphate; when the liquid in the second reactor along the feeding direction exceeds 60% of the liquid level in the reactor, the connecting pipeline is used to introduce the liquid into the third reactor arranged along the feeding direction, and when the liquid in the third reactor exceeds 15% of the liquid level therein, the stirring component in the third reactor is started to stir the liquid, so that the incompletely reacted liquid continues to react to synthesize ferric phosphate; and so on, until the liquid passes through all the reactors and flows out to obtain the ferric phosphate product.

[0020] Optionally, the iron salt used in the iron salt solution includes one or more of ferrous oxalate, ferric chloride, ferric oxide, ferrous sulfate, ferrous oxide, ferric sulfate, ferric nitrate, ferric carbonate, ferric acetylacetonate, ferric gluconate and ammonium ferric citrate; the phosphate salt used in the phosphate solution includes one or more of phosphoric acid, sodium pyrophosphate, diammonium hydrogen phosphate, sodium dihydrogen phosphate, monoammonium phosphate, trisodium phosphate, disodium hydrogen phosphate, sodium hypophosphite and calcium hydrogen phosphate.

[0021] Optionally, the pH adjusting liquid includes an acidic adjusting liquid and an alkaline adjusting liquid; the acidic reagent used in the acidic adjusting liquid includes one or more of nitric acid, phosphoric acid, concentrated sulfuric acid and aqua regia; the alkaline reagent used in the alkaline adjusting liquid includes one or more of ammonia water, sodium hydroxide, calcium hydroxide, calcium oxide, sodium carbonate and sodium bicarbonate; the reagent used in the oxidizing liquid includes one or more of potassium permanganate, hydrogen peroxide, potassium persulfate and ammonium persulfate.

[0022] Optionally, the target temperature is 40-120°C.

[0023] The application of the technical solution of the present invention has at least the following beneficial effects:

[0024] (1) The continuous lithium iron phosphate precursor reaction device provided by the present invention can not only provide a continuous large-scale reactor system, but also solve the problems of difficulty in crystal structure regulation and substandard product quality, and promote the stable and efficient continuous production of lithium iron phosphate precursor iron phosphate products. Specifically, the first feeding component is used to introduce the iron salt solution into the first reactor in the feeding direction according to the set flow rate, the second feeding component is used to introduce the phosphate solution into the first reactor in the feeding direction according to the set flow rate, and the mixed feeding component is used to mix the oxidation liquid and the pH regulating liquid according to the set flow rate and then introduce them into the first reactor in the feeding direction. Subsequently, the feed liquid flows into multiple reactors arranged in series in the feeding direction in sequence through the first reactor, and the iron salt solution, the phosphate salt solution, the oxidation liquid and the pH regulating liquid are continuously and gradually synthesized into the iron phosphate product under the stirring action, so as to realize the stable and efficient continuous production of the iron phosphate product; in addition, the multiple reactors arranged in series in sequence along the feeding direction can ensure the gradual, stable and continuous synthesis of the iron phosphate product, thereby solving the problems of difficulty in crystal structure regulation and substandard product quality.

[0025] (2) The present invention provides a reaction synthesis method for a continuous lithium iron phosphate precursor reaction device. By strictly controlling the feed concentration and feed flow rate of the iron salt solution, the phosphorus salt solution, the oxidizing liquid and the pH regulating liquid, it is possible to ensure that the iron-phosphorus ratio is appropriate, and the iron phosphate product is prepared by reaction under appropriate oxidation conditions and pH conditions; the feed liquid temperature is strictly controlled by the preheating component and the heating equipment to ensure that the reaction temperature is appropriate, thereby efficiently synthesizing the iron phosphate product; when the feed liquid in each reactor exceeds 15% of the liquid level therein, the feed liquid is stirred to improve the reaction efficiency; if the feed liquid does not exceed 15% of the liquid level in the reactor, stirring is not required, because there is an empty path between the stirring component and the bottom of the reactor, so stirring is not required in the empty path, thereby reducing energy consumption; when the feed liquid in the previous reactor along the feed direction exceeds 60% of the liquid level therein, the feed liquid is introduced from the previous reactor into the next reactor, on the one hand, ensuring that the unreacted feed liquid continues to react to synthesize the iron phosphate product, and on the other hand, ensuring that the feeding and discharging of the reactor are continuously controllable, preventing the reactor from overflowing, and avoiding safety accidents. Therefore, the reaction synthesis method can ensure the gradual, stable and continuous synthesis of the iron phosphate product.

[0026] In addition to the above-described objects, features and advantages, the present invention has other objects, features and advantages. The present invention will be further described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The drawings constituting a part of this application are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0028] Figure 1 It is a structural schematic diagram of a continuous lithium iron phosphate precursor reaction device in Example 1;

[0029] Among them, 1. the first feeding component, 1.1. the first feeding pipeline, 1.2. the first feeding pump, 1.3. the first feeding flowmeter, 2. the mixing feeding component, 2.1. the static mixer, 2.2. the third feeding component, 2.2.1. the third feeding pipeline, 2.2.2. the third feeding pump, 2.2.3. the third feeding flowmeter, 2.3. the fourth feeding component, 2.3.1. the fourth feeding pipeline, 2.3.2. the fourth feeding pump, 2.3.3. the fourth feeding flowmeter, 2.4. the mixing feeding pipeline, 3. the reactor, 4. the connecting pipeline, 5. the stirring component, 6. the stirring driving component, 7. the preheating component, 8. the pneumatic regulating valve, 9. the pneumatic switching valve, 10. the feeding pump, 11. the feeding flowmeter. DETAILED DESCRIPTION

[0030] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 belong to the scope of protection of the present invention.

[0031] Embodiment 1:

[0032] See also Figure 1 A continuous lithium iron phosphate precursor reaction device comprises a first feeding assembly 1, a second feeding assembly (not shown in the figure), a mixed feeding assembly 2, and a plurality of (e.g., 4) reactors 3 arranged in series in a feeding direction;

[0033] Two adjacent reactors 3 are connected via a connecting pipeline 4; a feed pump 10 (specifically a variable frequency pump) and a feed flow meter 11 are arranged on the connecting pipeline 4;

[0034] The first feed assembly 1 comprises a first feed pipeline 1.1, a first feed pump 1.2 (specifically a variable frequency pump) and a first feed flowmeter 1.3; the first feed pump 1.2 and the first feed flowmeter 1.3 are arranged on the first feed pipeline 1.1; the second feed assembly comprises a second feed pipeline, a second feed pump (specifically a variable frequency pump) and a second feed flowmeter; the second feed pump and the second feed flowmeter are arranged on the second feed pipeline; the first feed pipeline 1.1 and the second feed pipeline are both connected to the first reactor 3 along the feed direction;

[0035] The mixed feed component 2 includes a static mixer 2.1, a third feed component 2.2, a fourth feed component 2.3 and a mixed feed pipeline 2.4; the third feed component 2.2 includes a third feed pipeline 2.2.1, a third feed pump 2.2.2 (specifically a variable frequency pump) and a third feed flowmeter 2.2.3; the third feed pump 2.2.2 and the third feed flowmeter 2.2.3 are arranged on the third feed pipeline 2.2.1; the fourth feed component 2.3 includes a fourth feed pipeline 2.3. 1. A fourth feed pump 2.3.2 (specifically a variable frequency pump) and a fourth feed flowmeter 2.3.3; the fourth feed pump 2.3.2 and the fourth feed flowmeter 2.3.3 are arranged on the fourth feed pipeline 2.3.1; a feed port and a discharge port are arranged on the static mixer 2.1, the feed port is connected to the third feed pipeline 2.2.1 and the fourth feed pipeline 2.3.1, and the discharge port is connected to the first reactor 3 along the feed direction through the mixed feed pipeline 2.4;

[0036] A stirring member 5 is provided in each of the reactors 3, and a stirring driving member 6 (specifically a motor) is provided outside each of the reactors 3, and the output end of the stirring driving member 6 is connected to the stirring member 5. The stirring member 5 includes a stirring shaft and a stirring blade provided on the stirring shaft.

[0037] The continuous lithium iron phosphate precursor reaction device also includes a heating device (not shown in the figure) and multiple preheating components 7; the preheating component 7 is arranged on the outer wall of each of the reaction kettles 3; the preheating component 7 is arranged on the outer wall of each of the connecting pipelines 4; each of the preheating components 7 is connected to the heating device.

[0038] The preheating assembly 7 includes a heat-insulating layer and a heat-conducting pipe; the heat-conducting pipe is spirally arranged on the outer wall of each of the reactors 3; the heat-conducting pipe is spirally arranged on the outer wall of each of the connecting pipelines; the heat-conducting pipe is connected to the heating device; the heat-insulating layer is arranged on the outer wall of the heat-conducting pipe away from the reactor 3 or away from the connecting pipeline. The heating device uses electric heating to heat the heat-conducting oil, uses a power pump to pump the heat-conducting oil into each heat-conducting pipe, and then, after the heat-conducting pipe heats the reactor 3 and the connecting pipeline, it returns to the heating device, realizing continuous circulation and replenishment of heat; in addition, the heat-insulating layer is used to reduce the heat loss of the heat-conducting oil in the heat-conducting pipe.

[0039] The continuous lithium iron phosphate precursor reaction device also includes a plurality of temperature sensors (not shown in the figure); the temperature sensor is arranged in each of the reaction kettles 3; the temperature sensor is arranged in each of the connecting pipes 4; and each of the temperature sensors is connected to the heating equipment.

[0040] The continuous lithium iron phosphate precursor reaction device also includes a plurality of liquid level sensors (not shown in the figure) and a main controller (not shown in the figure); the liquid level sensors are arranged in each of the reactors 3 to monitor the liquid level in each reactor 3. The main controller is a PLC controller, and is connected with each of the liquid level sensors, the heating equipment, the feed pump 10, the feed flow meter 11, the first feed pump 1.2, the first feed flow meter 1.3, the second feed pump, the second feed flow meter, the static mixer 2.1, the third feed pump 2.2.2, the third feed flow meter 2.2.3, the fourth feed pump 2.3.2, the fourth feed flow meter 2.3.3 and the stirring drive 6.

[0041] The continuous lithium iron phosphate precursor reaction device also includes a plurality of pneumatic regulating valves 8; the pneumatic regulating valves 8 are arranged on the first feed pipeline 1.1, the second feed pipeline, the third feed pipeline 2.2.1, the fourth feed pipeline 2.3.1 and each of the connecting pipelines 4 to assist in adjusting the feed speed. Each of the pneumatic regulating valves 8 is connected to the PLC controller.

[0042] The continuous lithium iron phosphate precursor reaction device also includes a plurality of pneumatic switch valves 9; the pneumatic switch valves 9 are arranged on the first feed pipeline 1.1, the second feed pipeline, the third feed pipeline 2.2.1, the fourth feed pipeline 2.3.1 and each of the connecting pipelines 4 to control the feed on and off. Each of the pneumatic switch valves 9 is connected to the PLC controller.

[0043] The reaction synthesis method of the continuous lithium iron phosphate precursor reaction device is as follows:

[0044] Step S1: Use the first feed component 1 to feed the iron salt solution with a mass concentration of 45g / L at a flow rate of 6m 3 / h feeding; using the second feeding component to feed a phosphate solution with a mass concentration of 45g / L at a flow rate of 6m 3 / h feed; the third feed assembly 2.2 is used to feed 8% of the oxidizing liquid at a flow rate of 0.5m 3 / h feeding, the fourth feeding assembly 2.3 is used to feed 85% of the pH adjusting liquid at a flow rate of 0.5m 3 / h feeding, the oxidizing liquid and the pH regulating liquid are synchronously fed into the static mixer 2.1, and after being mixed by the static mixer 2.1 to form a mixed liquid, the mixed liquid is fed into the first reactor 3 along the feeding direction through the mixed feeding pipeline 2.4; the iron salt solution, the phosphate salt solution and the mixed liquid are synchronously fed into the first reactor 3 along the feeding direction;

[0045] The heating device and the preheating component 7 are used to preheat the liquid in each of the reactors 3 and each of the connecting pipelines 4 to a target temperature, and the temperature of the liquid in each of the reactors 3 and each of the connecting pipelines 4 is monitored in real time by the temperature sensor; when the monitored temperature is lower than the target temperature, the heating temperature of the preheating component 7 is increased by the heating device until the monitored temperature reaches the target temperature;

[0046] Step S2, when the liquid in the first reactor 3 along the feeding direction exceeds 15% of the liquid level therein, start the stirring component 5 in the first reactor 3 to stir the liquid, so that the liquid gradually reacts to synthesize iron phosphate; when the liquid in the first reactor 3 along the feeding direction exceeds 60% of the liquid level in the reactor 3, use the connecting pipeline 4 to introduce the liquid into the second reactor 3 arranged along the feeding direction, and when the liquid in the second reactor 3 exceeds 15% of the liquid level therein, start the stirring component 5 in the second reactor 3 to stir The feed liquid is introduced into the third reactor 3 arranged along the feeding direction by the connecting pipeline 4 when the feed liquid in the second reactor 3 exceeds 60% of the liquid level in the reactor 3, and when the feed liquid in the third reactor 3 exceeds 15% of the liquid level therein, the stirring component 5 in the third reactor 3 is started to stir the feed liquid, so that the feed liquid that has not been completely reacted continues to react to synthesize iron phosphate; and so on, until the feed liquid passes through all the reactors 3 and flows out to obtain the iron phosphate product.

[0047] The iron salt used in the iron salt solution is ferrous sulfate; the phosphate salt used in the phosphate salt solution is monoammonium phosphate.

[0048] The pH regulating liquid is an acidic regulating liquid, which is a phosphoric acid solution with a mass percentage of 85%; the oxidant used in the oxidizing liquid is hydrogen peroxide.

[0049] The target temperature is 90°C.

[0050] Embodiment 2:

[0051] The difference from Example 1 is that the mass concentration of the iron salt solution is 45 g / L and the flow rate is 2 m 3 / h feed; the mass concentration of the phosphate solution is 20g / L, and the flow rate is 6m 3 / h feed; the mass percentage of the oxidizing liquid is 8%, and the flow rate is 0.5m 3 / h feed; the mass percentage of pH adjustment liquid is 50%, and the flow rate is 0.5m 3 / h feed.

[0052] Embodiment 3:

[0053] The difference from Example 1 is that the mass concentration of the iron salt solution is 60 g / L, and the flow rate is 6 m 3 / h feed; the mass concentration of the phosphate solution is 45g / L, and the flow rate is 6m 3 / h feed; the mass percentage of the oxidizing liquid is 8%, and the flow rate is 0.5m 3 / h feed; the mass percentage of pH adjustment liquid is 50%, and the flow rate is 0.5m 3 / h feed.

[0054] Embodiment 4:

[0055] Different from Example 1, the iron salt solution is 45 g / L, and the iron salt used is ferrous oxalate; the phosphate salt solution is 45 g / L.

[0056] Embodiment 5:

[0057] Different from Example 1, the target temperature is 60°C.

[0058] Embodiment 6:

[0059] Different from Example 1, the target temperature is 40°C.

[0060] Comparative Example 1:

[0061] The difference from Example 1 is that the mass concentration of the iron salt solution is 45 g / L and the flow rate is 6 m 3 / h feed; the mass concentration of the phosphate solution is 45g / L, and the flow rate is 15m 3 / h feed; the mass percentage of the oxidizing liquid is 8%, and the flow rate is 0.5m 3 / h feed; the mass percentage of pH adjustment liquid is 50%, and the flow rate is 0.5m 3 / h feed.

[0062] Comparative Example 2:

[0063] The difference from Example 1 is that the mass concentration of the iron salt solution is 100 g / L and the flow rate is 6 m 3 / h feed; the mass concentration of the phosphate solution is 65g / L, and the flow rate is 6m 3 / h feed; the mass percentage of the oxidizing liquid is 30%, and the flow rate is 0.5m 3 / h feed; the mass percentage of pH adjustment liquid is 50%, and the flow rate is 0.5m 3 / h feed.

[0064] Comparative Example 3:

[0065] Different from Example 1, the target temperature is 180°C.

[0066] Comparative Example 4:

[0067] Different from Example 1, the target temperature is 20°C.

[0068] 10 g of the iron phosphate products prepared in Examples 1-6 and Comparative Examples 1-4 were sampled and tested, and the test results are shown in Table 1. The test method was tested using the test method in Part 7 of the Chemical Standard HG / T 4701-2021 Iron Phosphate for Batteries. The standards for the test items in the data in Table 1 refer to the Type I index in Table 1 in Part 6 of the Chemical Standard HG / T 4701-2021 Iron Phosphate for Batteries.

[0069] Table 1 Performance test results

[0070]

[0071]

[0072] From the data in Table 1, it can be seen that compared with Comparative Examples 1-4, the present invention can prepare iron phosphate products for batteries that meet the chemical standard HG / T 4701-2021 by using Examples 1-6. This shows that the reaction device and reaction synthesis method used in the present invention can ensure the appropriate iron-phosphorus ratio by strictly controlling the feed concentration and feed flow of the iron salt solution, the phosphate salt solution, the oxidizing solution and the pH regulating solution, and react under appropriate oxidation conditions and pH conditions, thereby ensuring the stable, efficient and continuous production of the lithium iron phosphate precursor iron phosphate product.

[0073] In Comparative Example 1, the flow rate of the phosphate solution used is too large, resulting in an imbalance in the iron-phosphorus ratio, and it is impossible to obtain an iron phosphate product for batteries that meets the chemical standard HG / T 4701-2021.

[0074] The mass concentration of the iron salt solution used in Comparative Example 2 is too high, resulting in an imbalance in the iron-phosphorus ratio, and it is impossible to obtain an iron phosphate product for batteries that meets the chemical standard HG / T 4701-2021.

[0075] The target temperature used in Comparative Example 3 is too high, the solubility of phosphorus ions is enhanced, the reaction rate is accelerated, the temperature is too high, the crystal nucleation is disturbed, the iron-phosphorus ratio is reduced, the particles are excessively agglomerated, the D50 particle size is too large, and the obtained iron phosphate product does not meet the chemical standard HG / T 4701-2021 battery iron phosphate product standard. The target temperature used in Comparative Example 4 is too low, the reaction rate is slow, it is not suitable for crystal growth, the particle size growth is limited, the iron-phosphorus binding effect is poor, and the D50 particle size is too small. The obtained iron phosphate product does not meet the chemical standard HG / T 4701-2021 battery iron phosphate product standard.

[0076] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A continuous lithium iron phosphate precursor reaction device, characterized in that: It comprises a first feeding assembly (1), a second feeding assembly, a mixing feeding assembly (2), and a plurality of reaction kettles (3) arranged in series in sequence along the feeding direction; Two adjacent reaction kettles (3) are connected via a connecting pipeline (4); a feed pump (10) and a feed flow meter (11) are arranged on the connecting pipeline (4); The first feed assembly (1) comprises a first feed pipeline (1.1), a first feed pump (1.2) and a first feed flow meter (1.3); the first feed pump (1.2) and the first feed flow meter (1.3) are arranged on the first feed pipeline (1.1); the second feed assembly comprises a second feed pipeline, a second feed pump and a second feed flow meter; the second feed pump and the second feed flow meter are arranged on the second feed pipeline; the first feed pipeline (1.1) and the second feed pipeline are both connected to the first reactor (3) along the feed direction; The mixed feed component (2) comprises a static mixer (2.1), a third feed component (2.2), a fourth feed component (2.3) and a mixed feed pipeline (2.4); the third feed component (2.2) comprises a third feed pipeline (2.2.1), a third feed pump (2.2.2) and a third feed flow meter (2.2.3); the third feed pump (2.2.2) and the third feed flow meter (2.2.3) are arranged on the third feed pipeline (2.2.1); the fourth feed component (2.3) comprises a fourth feed pipeline (2 .3.1), a fourth feed pump (2.3.2) and a fourth feed flowmeter (2.3.3); the fourth feed pump (2.3.2) and the fourth feed flowmeter (2.3.3) are arranged on the fourth feed pipeline (2.3.1); a feed port and a discharge port are arranged on the static mixer (2.1), the feed port is connected to the third feed pipeline (2.2.1) and the fourth feed pipeline (2.3.1), and the discharge port is connected to the first reactor (3) along the feed direction through the mixed feed pipeline (2.4); A stirring component (5) is arranged inside each of the reaction kettles (3), and a stirring driving component (6) is arranged outside each of the reaction kettles (3), and an output end of the stirring driving component (6) is connected to the stirring component (5).

2. The continuous lithium iron phosphate precursor reaction device according to claim 1, characterized in that: It also comprises a heating device and a plurality of preheating components (7); the preheating component (7) is arranged on the outer wall of each of the reaction kettles (3); the preheating component (7) is arranged on the outer wall of each of the connecting pipelines (4); and each of the preheating components (7) is connected to the heating device.

3. The continuous lithium iron phosphate precursor reaction device according to claim 2, characterized in that: The preheating assembly (7) comprises a heat-insulating layer and a heat-conducting pipe; the heat-conducting pipe is spirally arranged on the outer wall of each of the reaction kettles (3); the heat-conducting pipe is spirally arranged on the outer wall of each of the connecting pipelines (4); the heat-conducting pipe is connected to the heating equipment; and the heat-insulating layer is arranged on the outer wall of the heat-conducting pipe.

4. The continuous lithium iron phosphate precursor reaction device according to claim 3, characterized in that: It also includes a plurality of temperature sensors; the temperature sensor is arranged in each of the reaction kettles (3); the temperature sensor is arranged in each of the connecting pipelines (4); each of the temperature sensors is connected to the heating equipment; The continuous lithium iron phosphate precursor reaction device also includes a plurality of liquid level sensors and a main controller; the liquid level sensor is arranged in each of the reaction kettles (3); the main controller includes a PLC controller, and is connected to each of the liquid level sensors, the heating equipment, the feed pump (10), the feed flow meter (11), the first feed pump (1.2), the first feed flow meter (1.3), the second feed pump, the second feed flow meter, the static mixer (2.1), the third feed pump (2.2.2), the third feed flow meter (2.2.3), the fourth feed pump (2.3.2), the fourth feed flow meter (2.3.3) and the stirring drive (6).

5. The continuous lithium iron phosphate precursor reaction device according to claim 4, characterized in that: It also includes a plurality of pneumatic regulating valves (8); the pneumatic regulating valves (8) are arranged on the first feed pipeline (1.1), the second feed pipeline, the third feed pipeline (2.2.1), the fourth feed pipeline (2.3.1) and each of the connecting pipelines (4); and each of the pneumatic regulating valves (8) is connected to the PLC controller.

6. The continuous lithium iron phosphate precursor reaction device according to claim 5, characterized in that: It also includes a plurality of pneumatic switch valves (9); the pneumatic switch valves (9) are arranged on the first feed pipeline (1.1), the second feed pipeline, the third feed pipeline (2.2.1), the fourth feed pipeline (2.3.1) and each of the connecting pipelines (4); and each of the pneumatic switch valves (9) is connected to the PLC controller.

7. A reaction synthesis method of a continuous lithium iron phosphate precursor reaction device as claimed in any one of claims 4 to 6, characterized in that: include: Step S1: using the first feed component (1) to feed an iron salt solution with a mass concentration of 10 to 80 g / L at a flow rate of 2 to 12 m 3 / h feeding; using the second feeding component to feed the phosphate solution with a mass concentration of 10 to 80 g / L at a flow rate of 2 to 12 m 3 / h feeding; using the third feeding component (2.2) to feed 3% to 30% of the oxidizing liquid at a flow rate of 0.1 to 1.0 m 3 / h feeding, using the fourth feeding component (2.3) to feed 5% to 100% of the pH regulating liquid at a flow rate of 0.1 to 1.0 m 3 / h feeding, the oxidizing liquid and the pH regulating liquid are synchronously fed into the static mixer (2.1), and after being mixed by the static mixer (2.1) to form a mixed liquid, the mixed liquid is fed into the first reactor (3) along the feeding direction through the mixed feeding pipeline (2.4); the iron salt solution, the phosphate salt solution and the mixed liquid are synchronously fed into the first reactor (3) along the feeding direction; The heating device and the preheating component (7) are used to preheat the liquid in each of the reaction kettles (3) and each of the connecting pipelines (4) to a target temperature, and the temperature of the liquid in each of the reaction kettles (3) and each of the connecting pipelines (4) is monitored in real time by the temperature sensor; when the monitored temperature is lower than the target temperature, the heating temperature of the preheating component (7) is increased by the heating device until the monitored temperature reaches the target temperature; Step S2: when the liquid in the first reactor (3) along the feeding direction exceeds 15% of the liquid level therein, the stirring component (5) in the first reactor (3) is started to stir the liquid so that the liquid gradually reacts to synthesize ferric phosphate; when the liquid in the first reactor (3) along the feeding direction exceeds 60% of the liquid level therein, the connecting pipeline (4) is used to introduce the liquid into the second reactor (3) arranged along the feeding direction, and when the liquid in the second reactor (3) exceeds 15% of the liquid level therein, the stirring component (5) in the second reactor (3) is started. The feed liquid is stirred so that the feed liquid that has not completely reacted continues to react to synthesize iron phosphate; when the feed liquid in the second reactor (3) along the feeding direction exceeds 60% of the liquid level in the reactor (3), the feed liquid is introduced into the third reactor (3) arranged along the feeding direction by using the connecting pipeline (4); when the feed liquid in the third reactor (3) exceeds 15% of the liquid level therein, the stirring component (5) in the third reactor (3) is started to stir the feed liquid so that the feed liquid that has not completely reacted continues to react to synthesize iron phosphate; and so on, until the feed liquid passes through all the reactors (3) and flows out to obtain the iron phosphate product.

8. The reaction synthesis method according to claim 7, characterized in that: The iron salt used in the iron salt solution includes one or more of ferrous oxalate, ferric chloride, ferric oxide, ferrous sulfate, ferrous oxide, ferric sulfate, ferric nitrate, ferric carbonate, ferric acetylacetonate, ferric gluconate and ammonium ferric citrate; the phosphate salt used in the phosphate salt solution includes one or more of phosphoric acid, sodium pyrophosphate, diammonium hydrogen phosphate, sodium dihydrogen phosphate, monoammonium phosphate, trisodium phosphate, disodium hydrogen phosphate, sodium hypophosphite and calcium hydrogen phosphate.

9. The reaction synthesis method according to claim 7, characterized in that: The pH regulating liquid includes an acidic regulating liquid and an alkaline regulating liquid; the acidic reagent used in the acidic regulating liquid includes one or more of nitric acid, phosphoric acid, concentrated sulfuric acid and aqua regia; the alkaline reagent used in the alkaline regulating liquid includes one or more of ammonia water, sodium hydroxide, calcium hydroxide, calcium oxide, sodium carbonate and sodium bicarbonate; the reagent used in the oxidizing liquid includes one or more of potassium permanganate, hydrogen peroxide, potassium persulfate and ammonium persulfate.

10. The reaction synthesis method according to claim 7, characterized in that: The target temperature is 40-120°C.

Images