Dehydration method and dehydration device for ferric phosphate hydrate

Abstract

The invention provides a dehydration method and a dehydration device for ferric phosphate hydrate, and relates to the technical field of substance dehydration. According to the method, the crystal water in the ferric phosphate hydrate is removed through microwave irradiation, heating to 150 DEG C or above and heat transfer for crystal water removal are not needed, and the energy consumption is low. Moreover, the method provided by the invention does not need to remove crystal water in a rotary kiln or a tunnel kiln and does not introduce new impurities such as magnetic foreign matters, and the prepared anhydrous iron phosphate is high in purity and does not affect the performance of the battery when being applied to the battery. Under the action of microwave irradiation, after a large number of water molecules obtain energy, the interior of the ferric phosphate hydrate overflows to form countless tiny pore channels, so that the obtained anhydrous ferric phosphate tissue is expanded and loosened, a grinding process and a lithium intercalation process in a downstream lithium iron phosphate production process are facilitated, and the performance of a terminal product lithium iron phosphate is comprehensively improved. Moreover, the method provided by the invention is simple in process, simple to operate, low in cost and suitable for industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of dehydration methods, and in particular to a dehydration method and a dehydration device for ferric phosphate hydrate. Background Art

[0002] With the rapid development of new energy vehicles, the development of new energy materials around the world has made great progress. Lithium iron phosphate batteries have been particularly developed in recent years due to their safety, stability, and long-term recycling. Anhydrous iron phosphate is the necessary raw material for the preparation of lithium iron phosphate.

[0003] Anhydrous iron phosphate is obtained by dehydrating iron phosphate hydrate, for example, the dehydration temperature of FePO4·2H2O is about 150-200°C. The prior art is to heat and dehydrate iron phosphate hydrate in a rotary kiln or other kiln to prepare anhydrous iron phosphate. However, the above dehydration method has the following shortcomings: First, the rotary kiln or tunnel kiln uses heat exchange and heat convection to heat iron phosphate hydrate, which has low heat transfer efficiency, large required temperature gradient, large heat loss, and high energy consumption; second, at high temperature, the iron phosphate hydrate particles and the kiln wall and other kiln parts are repeatedly rubbed for a long time, which easily introduces particles such as iron element or oxide. When used in the production process of preparing lithium iron phosphate, the above magnetic foreign matter is difficult to be cleaned up, which seriously affects the performance of the battery. Summary of the invention

[0004] In view of this, the object of the present invention is to provide a dehydration method and a dehydration device for ferric phosphate hydrate. The method provided by the present invention has low energy consumption, does not introduce other impurities, and has high purity of ferric phosphate hydrate.

[0005] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0006] The invention provides a method for dehydrating ferric phosphate hydrate, comprising the following steps: dehydrating the ferric phosphate hydrate by microwave irradiation to obtain anhydrous ferric phosphate.

[0007] Preferably, the frequency of the microwave irradiation dehydration is 0.3-300 GHz.

[0008] Preferably, the power of the microwave irradiation dehydration is 4-100 kW.

[0009] Preferably, the microwave irradiation dehydration time is 80 to 100 minutes.

[0010] Preferably, the ferric phosphate hydrate includes one or more of ferric phosphate dihydrate, ferric phosphate monohydrate and ferric phosphate octahydrate.

[0011] The present invention provides a dehydration device used in the dehydration method described in the above technical solution, comprising a microwave heating component, a heating component and a transmission component;

[0012] The microwave heating assembly comprises a microwave generator 11 and a microwave heater 13 connected to the microwave generator 11;

[0013] The heated component includes an open material storage device 21, and the material of the open material storage device 21 does not contain magnetic substances;

[0014] The transmission assembly includes a conveyor belt 31 , and the open storage device 21 is located on the surface of the conveyor belt 31 .

[0015] Preferably, the microwave heating assembly further includes a bracket 14 for supporting the microwave heater 13 .

[0016] Preferably, the microwave heating assembly further comprises a partition 15 located between the microwave heater 13 and the open material storage device 21 .

[0017] Preferably, the dehydration device further comprises a channel-shaped control box 4, the microwave generator 11 is located on the upper surface of the channel-shaped control box 4; the microwave heater 13, the bracket 14, the partition 15 and the open material storage device 21 are located in the channel-shaped control box 4;

[0018] The conveyor belt 31 enters from one side of the channel-shaped control box 4 and is led out from the opposite side.

[0019] Preferably, the transmission assembly further includes a frame 32 supporting the conveyor belt 31 .

[0020] The present invention provides a method for dehydrating iron phosphate hydrate, comprising the following steps: subjecting iron phosphate hydrate to microwave irradiation dehydration to obtain anhydrous iron phosphate. The present invention utilizes microwave irradiation to remove crystal water in iron phosphate hydrate, and there is no need to heat iron phosphate hydrate to above 150°C and conduct heat transfer so that water molecules obtain energy and separate from iron phosphate molecules, and the energy consumption is low. Moreover, the method provided by the present invention does not require dehydration of crystal water in a rotary kiln or a tunnel kiln, and does not introduce new impurities such as magnetic foreign matter. The obtained anhydrous iron phosphate has high purity and is applied to batteries without affecting the performance of the batteries. Under the action of microwave irradiation, a large number of water molecules in iron phosphate hydrate obtain energy and overflow from the inside of the iron phosphate hydrate, forming countless tiny pores, so that the obtained anhydrous iron phosphate tissue expands and becomes loose, which is beneficial to the grinding process and lithium insertion process of the downstream lithium iron phosphate production process, thereby comprehensively improving the performance of the terminal product lithium iron phosphate. Moreover, the method provided by the present invention has simple process, simple operation, low cost, and is suitable for industrial production.

[0021] The present invention provides a dehydration device used in the dehydration method described in the above technical solution, comprising a microwave heating component, a heated component and a transmission component; the microwave heating component comprises a microwave generator 11 and a microwave heater 13 connected to the microwave generator 11; the heated component comprises an open storage device 21, the material of the open storage device 21 does not contain magnetic substances; the transmission component comprises a conveyor belt 31, and the open storage device 21 is located on the surface of the conveyor belt 31. The dehydration device provided by the present invention generates microwaves through the microwave generator 11, and the microwave heater 13 converts microwave energy into heat energy. When the iron phosphate hydrate passes through the microwave heater 13, the microwave energy generated by the microwave generator 11 is absorbed by the iron phosphate hydrate, so that the water inside the iron phosphate hydrate is rapidly heated and vaporized, thereby achieving dehydration of the iron phosphate hydrate and obtaining anhydrous iron phosphate. The dehydration device provided by the present invention is used to dehydrate the iron phosphate hydrate, which has low energy consumption, and countless tiny channels are formed in the material during microwave irradiation, so that the obtained anhydrous iron phosphate tissue is expanded and loosened, which is beneficial to the grinding process and lithium insertion process of the downstream lithium iron phosphate production process, thereby comprehensively improving the performance of the terminal product lithium iron phosphate. At the same time, the iron phosphate hydrate does not need to be turned over and does not contact other equipment components except for the open storage device 21 that does not contain magnetic substances during the dehydration process, which significantly reduces the risk of introducing magnetic foreign matter, and the obtained anhydrous iron phosphate has high purity. Moreover, the device used in the present invention is simple and low in cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the structure of the dehydration device, wherein 11-microwave generator, 12-connecting waveguide, 13-microwave heater, 14-bracket, 15-partition, 21-open storage device, 31-conveyor belt, 32-frame, 4-channel-shaped control box. DETAILED DESCRIPTION

[0023] The invention provides a method for dehydrating ferric phosphate hydrate, comprising the following steps: dehydrating the ferric phosphate hydrate by microwave irradiation to obtain anhydrous ferric phosphate.

[0024] Unless otherwise specified, the materials and equipment used in the present invention are all commercially available products in the art.

[0025] In the present invention, the ferric phosphate hydrate preferably includes one or more of ferric phosphate dihydrate, ferric phosphate monohydrate and ferric phosphate octahydrate, and more preferably ferric phosphate dihydrate.

[0026] In the present invention, the microwave frequency of the microwave dehydration is preferably 0.3-300 GHz, more preferably 10-250 GHz. In a specific embodiment, the frequency of the microwave dehydration may be 0.3 GHz, 0.5 GHz, 1 GHz, 10 GHz, 50 GHz, 100 GHz, 150 GHz, 200 GHz, 250 GHz or 300 GHz. The power of the microwave dehydration is preferably 4-100 kW, more preferably 20-50 kW. In a specific embodiment, the power of the microwave dehydration may be 4 kW, 10 kW, 20 kW, 30 kW, 40 kW, 50 kW, 60 kW, 70 kW, 80 kW, 90 kW or 100 kW. The time of the microwave dehydration is preferably 80-100 min, more preferably 85-95 min, and further preferably 90 min.

[0027] The present invention also provides a dehydration device used in the method described in the above technical solution, the structural schematic diagram of which is shown in FIG. Figure 1 As shown below, combined Figure 1 The device is described in detail.

[0028] The dehydration device provided by the present invention includes a microwave heating component, a heat receiving component and a transmission component; the microwave heating component includes a microwave generator 11 and a microwave heater 13 connected to the microwave generator 11; the heat receiving component includes an open storage device 21, and the material of the open storage device 21 does not contain magnetic substances; the transmission component includes a conveyor belt 31, and the open storage device 21 is located on the surface of the conveyor belt 31.

[0029] In the present invention, the microwave generator 11 is preferably connected to the microwave heater 13 by connecting the waveguide 12. In the present invention, the function of the microwave heater 13 is to convert the microwave energy generated by the microwave generator 11 into heat energy. In the present invention, the microwave generator is an electronic device capable of generating microwave signals, which uses special electronic components and circuits to generate high-frequency electromagnetic oscillations to generate microwave signals; the working principle of the microwave generator is based on the principle of the oscillation circuit, including an oscillation circuit and an amplification circuit; the oscillation circuit is composed of a feedback circuit and an inductor and capacitor capable of generating resonance. When the charge oscillates between the inductor and the capacitor, an electromagnetic wave is generated; after the electromagnetic wave is amplified by the amplification circuit, it becomes a microwave signal.

[0030] In the present invention, the microwave heating assembly preferably also includes a bracket 14 supporting the microwave heater 13, and a partition 15 located between the microwave heater 13 and the open storage device 21, wherein the function of the partition is to prevent the material in the open storage device 21 from splashing and to prevent dust from entering the material.

[0031] In the present invention, the material of the open storage device 21 is preferably plastic. The present invention has no special limitation on the plastic, and any plastic known to those skilled in the art that does not contain magnetic substances and is not affected by microwave radiation may be used.

[0032] In the present invention, the transmission assembly preferably also includes a frame 32 supporting the conveyor belt 31. The material of the frame 32 preferably includes metal. The present invention does not specifically limit the type of the metal, and any metal that can be used as a frame and is well known to those skilled in the art can be used.

[0033] In the present invention, the dehydration device preferably also includes a channel-shaped control box 4, the microwave generator 11 is located on the upper surface of the channel-shaped control box 4; the microwave heater 13, the bracket 14, the partition 15 and the open storage device 21 are located in the channel-shaped control box 4; the conveyor belt 31 enters from one side of the channel-shaped control box 4 and is discharged from the opposite side.

[0034] Combine the following Figure 1 The dehydration method of iron phosphate hydrate is described in detail. Under room temperature, iron phosphate hydrate is placed in an open storage device 21 on the surface of a conveyor belt 31, a microwave generator 11 generates microwaves, and the microwaves are transmitted to a microwave heater 13 through a connecting waveguide 12, and the microwave heater 13 converts microwave energy into heat energy. When the open storage device 21 containing iron phosphate hydrate passes through the microwave heater 13, the microwave energy is absorbed by the iron phosphate hydrate, so that the water inside the iron phosphate hydrate is rapidly heated and vaporized, and the iron phosphate hydrate is dehydrated to obtain anhydrous iron phosphate; a partition 15 is provided between the microwave heater 13 and the open storage device 21, which can prevent the material in the open storage device 21 from splashing and prevent dust from entering the material; the conveyor belt 31 passes through the channel-shaped control box 4 and is supported by the frame 32; the microwave heater 13 is supported by the bracket 14.

[0035] In order to further illustrate the present invention, the dehydration method and dehydration device of ferric phosphate hydrate provided by the present invention are described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0036] Example 1

[0037] use Figure 1 The dehydration device shown was used to dehydrate the dihydrated ferric phosphate. 20.00 g of dihydrated ferric phosphate was irradiated with microwaves at 100 GHz and 5 kW for 90 min to obtain 16.162 g of anhydrous ferric phosphate (water content of about 0.1%).

[0038] The prepared anhydrous ferric phosphate was subjected to a thermogravimetric analysis experiment, and no mass loss was observed after being kept at 550°C for 2 h, indicating that the dehydration was complete.

[0039] Example 2

[0040] use Figure 1 The device shown is used to dehydrate ferric phosphate dihydrate. 1000 g ferric phosphate dihydrate was irradiated with microwaves at 100 GHz and 5 kW for 90 min to obtain 808.27 g anhydrous ferric phosphate (water content of about 0.12%).

[0041] The prepared anhydrous ferric phosphate was subjected to a thermogravimetric analysis experiment, and no mass loss was observed after being kept at 550°C for 2 h, indicating that the dehydration was complete.

[0042] Example 3

[0043] use Figure 1 The device shown is used to dehydrate ferric phosphate dihydrate. 5000 g ferric phosphate dihydrate was irradiated with microwaves at 100 GHz and 5 kW for 90 min to obtain 4042.56 g anhydrous ferric phosphate (water content of about 0.15%).

[0044] The prepared anhydrous ferric phosphate was subjected to a thermogravimetric analysis experiment, and no mass loss was observed after being kept at 550°C for 2 h, indicating that the dehydration was complete.

[0045] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A method for dehydrating ferric phosphate hydrate, comprising the following steps: The ferric phosphate hydrate is subjected to microwave irradiation and dehydration to obtain anhydrous ferric phosphate.

2. The dehydration method according to claim 1, characterized in that: The frequency of the microwave irradiation dehydration is 0.3-300 GHz.

3. The dehydration method according to claim 1, characterized in that: The power of the microwave irradiation dehydration is 4-100 kW.

4. The dehydration method according to claim 3, characterized in that: The microwave irradiation dehydration time is 80 to 100 minutes.

5. The dehydration method according to claim 1, characterized in that: The ferric phosphate hydrate includes one or more of ferric phosphate dihydrate, ferric phosphate monohydrate and ferric phosphate octahydrate.

6. The dehydration device used in the dehydration method according to any one of claims 1 to 5, comprising a microwave heating component, a heating component and a transmission component; The microwave heating assembly comprises a microwave generator (11) and a microwave heater (13) connected to the microwave generator (11); The heated component comprises an open material storage device (21), and the material of the open material storage device (21) does not contain magnetic substances; The transmission assembly comprises a conveyor belt (31), and the open material storage device (21) is located on the surface of the conveyor belt (31).

7. The dehydration device according to claim 6, characterized in that: The microwave heating assembly further comprises a bracket (14) for supporting the microwave heater (13).

8. The dehydration device according to claim 7, characterized in that: The microwave heating assembly further comprises a partition (15) located between the microwave heater (13) and the open material storage device (21).

9. The dehydration device according to any one of claims 6 to 8, characterized in that: The dehydration device further comprises a channel-shaped control box (4), the microwave generator (11) being located on the upper surface of the channel-shaped control box (4); the microwave heater (13), the bracket (14), the partition (15) and the open material storage device (21) being located inside the channel-shaped control box (4); The conveyor belt (31) enters from one side of the channel-shaped control box (4) and is led out from the opposite side.

10. The dehydration device according to claim 6, characterized in that: The transmission assembly also includes a frame (32) supporting the conveyor belt (31).

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