WO2018076747A1 - System for preparing lithium hydroxide - Google Patents

Abstract

Provided is a system for preparing lithium hydroxide at a low cost. The system comprises a preparation subsystem and further comprises a protective gas supply subsystem (1000) for removing carbon dioxide from air, so as to provide carbon dioxide-free air as a protective gas for a process for preparing lithium hydroxide. The protective gas supply subsystem comprises a filtration unit (100) for removing particulate matter from the air by filtration, the filtration unit comprising a gas inlet portion (112), a filtration portion and a gas outlet portion (113); a mother liquid storage device (200) that stores the lithium hydroxide mother liquid remaining after crystals precipitate out in a concentration and crystallization device; an absorption tower (300), into which the lithium hydroxide mother liquid is introduced as an absorbing agent to absorb carbon dioxide from the filtered air so as to obtain a carbon dioxide-free gas; a gas drying device (400) for drying the carbon dioxide-free gas to obtain a protective gas; and a supply device (500) that supplies the protective gas to the preparation subsystem, wherein at least one layer of filter screen of at least one filtration member (12) in the filtration portion is a magnetic filter screen.

Description

Lithium hydroxide preparation system Technical field

The invention belongs to the field of battery material preparation, and in particular relates to a lithium hydroxide preparation system.

Background technique

With the application of lithium ion batteries in new energy vehicles, high nickel and high energy density cathode materials have become a development trend. At present, high-nickel cathode materials generally use lithium hydroxide as a raw material. Compared with lithium carbonate, lithium hydroxide has advantages in crystal structure, solubility, etc., or more suitable for future lithium-ion materials. The premise is to continuously increase the energy density.

Now, the preparation of battery-grade lithium hydroxide products generally uses the following processes and devices:

1) removing impurities from raw materials, using raw material removing device to remove impurities and purifying with crude lithium carbonate, industrial grade lithium carbonate, lithium chloride, lithium sulfate, etc.

2) causticizing, adding the purified raw material to a causticizing device, causticizing reaction with calcium hydroxide solution or sodium hydroxide solution to obtain a lithium hydroxide solution;

3) concentrated crystallization, concentrated crystallization of the lithium hydroxide solution using a concentrated crystallization device to obtain lithium hydroxide crystals and lithium hydroxide mother liquor;

4) crystal drying, using a crystal drying device to dynamically dry lithium hydroxide crystals;

5) crushing, crushing the dried lithium hydroxide by using a crushing device;

6) Screening and packaging, using the screening and packaging device to sieve and package the crushed lithium hydroxide to form a finished product.

In the above production process, the prepared lithium hydroxide is very easy to absorb carbon dioxide in the air, and re-generates lithium carbonate, in order to avoid reaction with carbon dioxide, to ensure that the carbonate content in the product is ≤0.7wt.% to achieve the purity standard, in the harsh Inertizers, concentrated crystallization devices, crystal drying devices, crushing devices, and screening and packaging devices are all supplied with an inert gas such as nitrogen or argon as a shielding gas to prevent carbon dioxide from entering the air, but the above preparation process takes a long time. The use of many devices, the consumption of inert gas is very large, greatly increasing the preparation cost of lithium hydroxide.

Summary of the invention

The present invention has been made to solve the above problems, and an object thereof is to provide a lithium hydroxide production system which can produce lithium hydroxide at low cost.

In order to achieve the above object, the present invention employs the following structure.

The lithium hydroxide preparation system according to the present invention comprises: a preparation subsystem, which uses a lithium salt as a raw material to prepare a hydroxide by a raw material removing device, a causticizing device, a concentrated crystallization device, a crystal drying device, a crushing device, and a screening packaging device. The lithium product is characterized in that it further comprises: a shielding gas supply subsystem for removing carbon dioxide from the air, thereby providing carbon dioxide-free air as a shielding gas for the preparation process of the lithium hydroxide, and protecting the gas supply subsystem The system includes: a filtering device having: an air inlet portion that introduces outside air, a filter portion that communicates with the air inlet portion, filters and removes particulate matter in the introduced outside air, and communicates with the filter portion to filter The air outlet port derived from the rear air; the mother liquid storage device stores the lithium hydroxide mother liquor remaining after the crystal is precipitated in the concentrated crystallizing device; the absorption tower has a gas inlet portion connected to the gas outlet port to introduce the filtered air The absorbent inlet portion communicates with the mother liquid storage device, and the lithium hydroxide mother liquid is introduced as an absorbent; the tower body communicates with the gas inlet portion and communicates with the absorption liquid inlet portion, and the absorbent is used for the filtered air. The carbon dioxide is absorbed to obtain a carbon dioxide-free gas; the gas discharge port portion communicates with the tower body to discharge the carbon dioxide-free gas; and the liquid discharge port portion communicates with the tower body, and the absorbent that absorbs the carbon dioxide is discharged as the absorption solution. a gas drying device that communicates with the gas discharge port to dry the carbon dioxide-free gas to obtain a shielding gas And a supply device in communication with the gas drying device to provide the shielding gas to the preparation subsystem, wherein the filter portion includes at least one filter member, each filter member including a multi-layer filter, at least one of the at least one filter member The filter is a magnetic filter.

The lithium hydroxide preparation system according to the present invention may further have a feature that the filter device has a casing, including: a casing body, an air inlet portion on one side of the casing body, and a side of the casing body. The air outlet portion includes: at least two filter members installed in the casing between the air inlet portion and the air outlet portion to filter air entering from the air inlet portion; and a cleaning member for filtering The components are cleaned and the cleaned particles are washed and discharged.

The lithium hydroxide preparation system according to the present invention may further have the following feature: the cleaning member comprises: at least one cleaning plate unit installed in the casing, each cleaning plate unit being located between the adjacent two filtering members, a rotating plate rotatably mounted in the housing; a plurality of air nozzles mounted on the front surface of the rotating plate, capable of jetting air to the filtering member to eject particulate matter from the filtering member; and a first cleaning liquid distribution tube mounted on the rotation a cleaning liquid is sprayed along the back surface of the plate; the air blowing plate unit is installed in the casing, between the air outlet portion and the filter member closest to the air outlet portion, and has a rotating plate and a plurality of air nozzles a second cleaning liquid distribution pipe, mounted on the inner wall of the casing body, spraying the cleaning liquid along the inner side wall of the casing body opposite to the other side of the filtering member; the cleaning control unit is connected to all the rotating plates, and is controlled Each rotating plate is rotated to be perpendicular to the filtering member in the filtering state, and is rotated to the front side toward the filtering member in the cleaning state; and the cleaning liquid discharge unit, At the bottom of the housing body, the cleaning liquid adhered particulate matter discharged from the housing body.

The lithium hydroxide preparation system according to the present invention may further have the following feature: the absorption tower is a falling film absorption tower, and the absorption tower further has: a reversing valve installed on the liquid discharge port portion, having one inlet and two outlets The inlet is in communication with the liquid discharge port, one outlet is connected to the mother liquor storage device as a first outlet, and the other outlet is in communication with the causticizing device as a second outlet.

The lithium hydroxide preparation system according to the present invention may further have the following feature: the absorption tower further has: a pH value detecting controller connected to the liquid discharge port portion and the reversing valve to detect absorption in the liquid discharge port portion The pH value of the solution, and when the detection result is pH value ≤ 13, the control reversing valve is turned to the second outlet to discharge the absorption solution to the causticizing device; otherwise, the control reversing valve is turned to the first outlet to make the absorption solution Discharge to the mother liquor storage device.

The lithium hydroxide production system according to the present invention may further have a feature that the flow rate of the absorbent entering from the inlet portion of the absorbent is 0.5 to 1 m ³ /min, and the flow rate of the filtered air entering from the gas inlet portion is 1 ~20m ³ /min.

The lithium hydroxide preparation system according to the present invention may further have the following feature: the gas drying device comprises: a gas-liquid cyclone separator having a gas-liquid inlet portion communicating with the gas discharge port portion to allow carbon dioxide-free gas to enter; a separating portion communicating with the gas-liquid inlet portion to perform gas-liquid separation of the entering carbon dioxide-free gas; and an outlet portion communicating with the separating portion to discharge the separated low-moisture gas; and a dryer connected to the outlet portion Pass, dry the low water content gas.

The lithium hydroxide preparation system according to the present invention may further have the feature that the outlet portion includes a first outlet unit and a second outlet unit, and the first outlet unit is connected to the causticizing device, the concentrated crystallization device, and the crystal drying device. For supplying a portion of the low moisture gas, the second outlet unit is in communication with the dryer and another portion of the low moisture gas is sent to the dryer.

The lithium hydroxide preparation system according to the present invention may further have the following features: the dryer has: at least two drying towers and a first steering valve, each drying tower having: an introduction portion communicating with the outlet portion, a low-moisture gas is introduced; the drying portion is connected to the introduction portion, and is filled with a desiccant to absorb moisture in the low-moisture gas; the lead-out portion is connected to the drying portion, and the protective gas obtained after drying is discharged; and heating a portion installed on the drying portion to heat the desiccant to remove the adsorbed moisture. The first steering valve is installed between all the drying towers and the outlet portion, and has a first inlet port and at least two first discharge ports. The first inlet port is in communication with the outlet portion, and the at least two first outlet ports are respectively in communication with the introduction portions of the at least two drying towers, the gas drying device further comprising a drying control unit, the drying control unit and the first steering valve and two The heating portions are connected to control the first steering valve to be steered to communicate with the introduction portion of the other at least one drying tower when the water absorption of the at least one drying tower reaches saturation. Saturation control to achieve at least one heating unit for heating the drying tower.

The lithium hydroxide preparation system according to the present invention may further include: a gas storage device communicating with the lead-out portions of the two drying towers to store the shielding gas, the dryer further having a second steering valve, the second steering valve Installed between two drying towers and a gas storage device, having two second inlet ports and one second outlet port, the two second inlet ports respectively communicating with the outlet portions of the two drying towers, the second inlet port In communication with the gas storage device, the drying control unit is further coupled to the second steering valve to control the second steering valve to be in communication with the outlet portion of the other drying tower when the water absorption of one of the drying towers is saturated.

The role and effect of the invention

According to the lithium hydroxide preparation system of the present invention, since the filtering device is capable of filtering out particulate matter in the air in the protective gas supply subsystem, the absorption tower can utilize the remaining lithium hydroxide mother liquor as the absorbent after the crystal is precipitated in the concentrated crystallization device. After the filtered carbon dioxide in the air is absorbed, since the concentration of hydroxide in the lithium hydroxide mother liquor is very high, the carbon dioxide in the air can be sufficiently absorbed, thereby achieving the purpose of effectively removing carbon dioxide, and further, the gas drying device is used to The carbon dioxide gas is dried to obtain a shielding gas, and the supply device can supply the shielding gas to the preparation subsystem, so that an inexpensive gas such as air can be used as a shielding gas used in a large quantity in the preparation subsystem, thereby effectively reducing lithium hydroxide. Preparation costs.

Further, since at least one of the at least one filter member is a magnetic filter, the magnetic foreign matter can be adsorbed, thereby effectively removing the magnetic foreign matter.

DRAWINGS

1 is a schematic structural view of a shielding gas supply subsystem according to an embodiment of the present invention;

2 is a structural block diagram of an embodiment of a shielding gas supply subsystem according to the present invention;

3 is a schematic structural view of a filter device according to an embodiment of the present invention;

Figure 4 is a block diagram showing the structure of a cleaning member according to the present invention in an embodiment;

Figure 5 (a) is a schematic structural view of the cleaning plate unit according to the present invention as seen from the front in the embodiment;

Figure 5 (b) is a schematic view showing the structure of the cleaning plate unit according to the present invention as seen from the back in the embodiment;

Figure 6 is a control flow chart of the cleaning control unit according to the present invention in an embodiment;

Figure 7 is a control flow chart of the pH detecting controller according to the present invention in the embodiment;

Figure 8 is a schematic structural view of a gas-liquid cyclone separator according to the present invention in an embodiment;

Figure 9 is a control flow chart of the drying control unit according to the present invention in the embodiment.

detailed description

Hereinafter, the lithium hydroxide production system according to the present invention will be described in detail with reference to the accompanying drawings.

<Example>

In this embodiment, a lithium hydroxide preparation system is used to prepare a battery-grade lithium hydroxide product, which includes a preparation subsystem and a shielding gas supply subsystem.

The preparation subsystem uses a lithium salt such as crude lithium carbonate, industrial grade lithium carbonate, lithium chloride or lithium sulfate as a raw material to prepare a lithium hydroxide product, which comprises: a raw material removing device, a causticizing device, a concentrated crystallization device, and a crystal drying device. , crushing device and screening packaging device.

The shielding gas supply subsystem is used to remove carbon dioxide from the air to provide carbon dioxide-free air as a shielding gas for the lithium hydroxide preparation process.

1 is a schematic structural view of a protective gas supply subsystem according to an embodiment of the present invention; and FIG. 2 is a structural block diagram of an embodiment of a protective gas supply subsystem according to the present invention.

As shown in FIGS. 1 and 2, the shielding gas supply subsystem 1000 includes a filtering device 100, a mother liquid storage device 200, an absorption tower 300, a gas drying device 400, a supply device 500, and a gas storage device 600.

Fig. 3 is a schematic view showing the structure of a filtering device according to the present invention in an embodiment.

As shown in FIGS. 1 and 3, the filtering device 100 is for filtering out particulate matter in the air, and includes a housing 11, three filter members 12, and a cleaning member 13.

The housing 11 is made of stainless steel (surface-sprayed with PTFE) or plastic material and is not magnetic. It includes a case body 111, an air inlet portion 112, and an air outlet portion 113. The case body 111 has a hollow structure.

The air inlet portion 112 is located on the right side of the casing body 111 and includes an air inlet 112a and a sealing cover (not shown). The air inlet 112a is for allowing air to enter the housing 11, and the sealing cover is matched with the air inlet 112a for closing and closing the air inlet 112a in the cleaning state.

The air outlet portion 113 is located on the left side of the casing body 111 and includes a fan 113a and an outlet portion 113b. The air inlet end of the fan 113a faces the filter member 12, and the air outlet end of the fan 113a is blown toward the outlet portion 113b. That is, in Fig. 1, air enters the casing 11 from right to left for filtration. The outlet portion 113b has an air outlet 113b-1 for discharging the filtered air. In this embodiment, the intake air amount of the blower 113a 15-20m ³ / min, air permeability of the filter member 12 is 20-30m ³ / min.

The three filter members 12 are all mounted in the casing body 111 between the intake port portion 112 and the air outlet portion 113 to filter the air entering from the air inlet portion 112. Each filter member 12 includes a plurality of layers of screens and a fixed frame that secures the filters. The three filter members 12 are sequentially recorded in the air entering direction from right to left, and are sequentially referred to as a first filter member 121, a second filter member 122, and a third filter member 123. The first filter member 121 filters coarse particles and dust; the second filter member 122 filters fine particles such as fine pollen; and the third filter member 123 filters fine particles of 0.1 micrometer to 0.5 micrometer.

In this embodiment, the filter screens of the first filter member 121 and the second filter member 122 located at the outermost layer are all magnetic filter nets, that is, a total of four magnetic filter screens are provided. The magnetic filter is an electromagnet filter, which has magnetic attraction after energization and magnetic energy of 10,000 Gauss, which can adsorb magnetic foreign matter in the air.

Fig. 4 is a block diagram showing the structure of a cleaning member according to the present invention in an embodiment.

As shown in FIGS. 3 and 4, the cleaning member 13 is used for cleaning the three filter members 12, and cleaning the cleaned particles out of the housing 11, which includes: two cleaning plate units 131, a blowing plate unit 132, The second cleaning liquid distribution pipe 133, the air supply unit 134, the water supply unit 135, the three ultrasonic vibration members 136, the cleaning liquid discharge unit 137, and the cleaning control unit 138.

Two cleaning plate units 131 are installed in the casing body 111, and each cleaning plate unit 131 is located between two adjacent filtering members 12, as shown in Fig. 1, one cleaning plate unit 131 is located at the first filtering member 121 and Between the second filter members 122, another wash plate unit 131 is located between the second filter member 122 and the third filter member 123.

Fig. 5 (a) is a schematic view showing the structure of the cleaning plate unit according to the present invention as seen from the front in the embodiment; and Fig. 5 (b) is a structural view showing the cleaning plate unit according to the present invention as seen from the back in the embodiment.

As shown in FIG. 5, each of the cleaning plate units 131 has a rotating plate 131a, a plurality of air nozzles 131b, and a first cleaning liquid distribution pipe 131c.

The rotating plate 131a is rotatably mounted in the casing body 111, and the rotating plate 131a includes a plate main body 131a-1 and a rotating shaft 131a-2. The plate main body 131a-1 is mounted in the casing body 111 via a rotating shaft 131a-2, and the rotating shaft 131a-2 is fixed in the middle of the plate main body 131a-1, and the rotating shaft 131a-2 is rotatably mounted on both sides of the casing main body 111. On the wall.

Further, inside the rotating plate 131a, an air supply passage (not shown) communicating with all of the air nozzles 131b is provided, and the inlet A of the air supply passage extends from the inside of the rotating shaft 131a-2 to the air supply. Units 134 are in communication.

Moreover, the inside of the rotating plate 131a is further provided with a first water supply passage communicating with the first cleaning liquid distribution pipe 131c. (not shown), the inlet B of the first water supply passage extends from the inside of the rotating shaft 131a-2 to communicate with the water supply unit 135.

The plurality of air nozzles 131b are evenly arranged in eight rows on the front surface of the rotating plate 131a (i.e., the side facing the air inlet 112a), with the rotating shaft 131a-2 as a center line, and four rows on the upper and lower sides for being located on the right side thereof. The filter member 12 is blown to eject the particulate matter from the filter screen of the filter member 12. In this embodiment, the air nozzle 131b discharges a high-pressure gas, so that the effect of spraying the particles is better, the gas pressure is 0.1-0.5 MPa, and the distance from the air nozzle to the filter member is in the range of 10-50 cm. The 131b intermittently ejects the filter member 12 at a rate of 1-10 times/second, and the intermittent jet can not only improve the effect of ejecting the particulate matter but also save the amount of gas used.

After the air nozzle 131b ejects the filter member 12 from left to right, the particulate matter accumulated in the filter member 12 is ejected from the filter mesh of the filter member 12, and most of the particulate matter is sprayed toward the other rotating plate 131a. On the back side, for example, after the air nozzle 131b of the rotating plate 131a located on the left side of the second filter member 122 is blown toward the second filter member 122, most of the particulate matter is sprayed toward the rotating plate 131a located on the right side of the second filter member 122. back.

The first cleaning liquid distribution pipe 131c is attached to the back surface of the rotating plate 131a and is located at the upper portion of the back surface, and can spray the cleaning liquid along the back surface of the rotating plate 131a. When the cleaning state is in the cleaning state, the cleaning liquid is sprayed from the top to the bottom to absorb The particulate matter blown out by the high-pressure gas ejects the particles sprayed on the back surface, and a part of the particles in the air near the back side are also washed down, and then the cleaning liquid adhered with the particulate matter flows down the back surface of the rotating plate 131a. . The length of the first cleaning liquid distribution pipe 131c is equivalent to the length of the rotating plate 131a, and the first cleaning liquid distribution pipe 131c is evenly distributed with the liquid discharge holes in the radial direction.

Here, the cleaning liquid used is preferably viscous to the particulate matter, which increases the efficiency of adsorption and adhesion of the particles by the cleaning liquid. For example, using a viscous foam dedusting agent, the foam dedusting agent may be composed of: 1 to 5% by volume of sodium lauryl sulfate, a fatty alcohol polyoxyethylene ether sulfate, and rosin soap foaming. An aqueous solution of the agent.

The blower unit 132 is mounted in the case body 111 between the air outlet portion 112 and the third filter member 123. The blower unit 132 has a rotating plate 132a and a plurality of air nozzles 132b. The structure of the rotating plate 132a and the air nozzle 132b is the same as that of the above-described rotating plate 131a and air nozzle 131b, and the number of air nozzles 132b is also the same as the number of air nozzles 131b in the cleaning plate unit 131, and therefore will not be described again. . Similarly, the blower unit 132 can also eject the third filter member 123 located on the right side thereof through the air nozzle 132b, thereby ejecting the particulate matter from the filter screen of the filter member 12.

The second cleaning liquid distribution pipe 133 is installed at the top of the rightmost right side wall of the casing body 111, and sprays the cleaning liquid along the right side wall of the casing body 111, and the structure and corresponding structure of the second cleaning liquid distribution pipe 133 The function is the same as that of the first cleaning liquid distribution pipe 131c, that is, the length of the second cleaning liquid distribution pipe 133 is equivalent to the length of the right side wall of the second cleaning liquid distribution pipe 133, and the second cleaning liquid distribution pipe 133 is along A liquid discharge hole is evenly distributed in the radial direction, and the sprayed cleaning liquid is also the same as the first cleaning liquid distribution pipe 131c.

In addition, a liquid inlet (not shown) of the second cleaning liquid distribution pipe 133 extends out of the casing body 111 and communicates with the water supply unit 135.

The air supply unit 134 is connected to the inlets A of the three air supply passages of the three rotating plates 131a and 132a, and is provided for The air passage supplies air to the air nozzle 131b.

The water supply unit 135 is connected to the inlet B of the first water supply passage and the inlet of the second cleaning liquid distribution pipe 133 to supply water to the first cleaning liquid distribution pipe 131c and the second cleaning liquid distribution pipe 133.

The three ultrasonic vibrating members 136 are respectively mounted on the three fixing frames of the three filtering members 12, and in the cleaning state, the filtering member 12 is driven to vibrate by the ultrasonic vibrating member 136, and under the action of the ultrasonic waves, the dust on the filtering net is accelerated and disengaged. , which can improve the cleaning effect.

As shown in FIG. 3, the cleaning liquid discharge unit 137 is attached to the bottom of the case body 111, and discharges the cleaning liquid to which the particulate matter adheres from the inside of the case body 111. In the present embodiment, the cleaning liquid discharge unit 137 includes three cleaning liquid discharge valves 137a, and the number of the cleaning liquid discharge valves 137a is exactly equal to the total number of the first cleaning liquid distribution tubes 131c and the second cleaning liquid distribution tubes 133. As shown in FIG. 1, three cleaning liquid discharge valves 137a are respectively mounted on the bottom wall mounting portion 111a of the case body 111 between the right side wall of the case body 111 and the first filter member 121, as viewed from the right to the left. The bottom wall mounting portion 111a between the filter member 121 and the first cleaning plate unit 131, and the bottom wall mounting portion 111a between the second filter member 122 and the second cleaning plate unit 131.

Further, each of the bottom wall mounting portions 111a has a funnel shape whose cross section decreases from top to bottom, and this shape can well guide the cleaning liquid to flow into the cleaning liquid discharge valve 137a and be discharged from the cleaning liquid discharge valve 137a.

As shown in FIG. 4, the cleaning control unit 138 and the two cleaning plate units 131, the air blowing plate unit 132, the second cleaning liquid distribution pipe 133, the air supply unit 134, the water supply unit 135, the three ultrasonic vibration members 136, and the cleaning liquid Discharge units 137 are all connected to control their operation.

In addition, the cleaning control unit 138 is also connected to the four-layer electromagnet filter (not shown) and the fan 113a, and is capable of controlling the four-layer electromagnet filter to be energized and de-energized, and controlling the opening and closing of the fan 113a.

Specifically, in the filtered state, the cleaning control unit 138 can control all of the rotating plates 131a and 132a to rotate perpendicular to the corresponding filter member 12, and control the four-layer electromagnet filter to be energized to make it magnetic, and then control the fan. 113a starts pumping. By rotating both of the rotating plates 131a and 132a to be perpendicular to the corresponding filter member 12, normal circulation of air can be ensured, so that the filtering process proceeds smoothly.

In the cleaning state, the cleaning control unit 138 can control the fan 113a to stop running, the four-layer electromagnet filter is deenergized, and control all the rotating plates 131a and 132a to rotate to the front side parallel to the corresponding filter member 12, and then control three The ultrasonic vibrating members 136 vibrate, the air supply unit 134 supplies air to the air nozzles 131b, the water supply unit 135 supplies water to the first cleaning liquid distribution tubes 131c and the second cleaning liquid distribution tubes, and further controls all of the air nozzles 131b and 132b to perform jetting. And controlling the first cleaning liquid distribution pipe 131c and the second cleaning liquid distribution pipe 133 to spray the cleaning liquid, and also controlling the three cleaning liquid discharge valves 137a to be opened for discharging.

After the cleaning state is over, the washing control unit 138 controls all of the air nozzles 131b and 132b to stop the air injection, and controls the first cleaning liquid distribution pipe 131c and the second cleaning liquid distribution pipe 133 to stop spraying the cleaning liquid, and also controls the air supply unit 134. The gas supply is stopped, the water supply unit 135 stops the water supply, and the three cleaning liquid discharge valves 137a are controlled to be closed after the liquid discharge is completed.

The cleaning state referred to herein means that the ventilation amount of the filtering device 10 is reduced to 90%, and it is necessary to feed the filter member. The state of cleaning; or means that the set cleaning cycle is reached. For example, the set cleaning cycle can be cleaned every other day. In this embodiment, the cleaning cycle will be described as an example.

Fig. 6 is a control flow chart of the cleaning control unit according to the present invention in the embodiment.

As shown in FIG. 6, the workflow of the cleaning control unit 138 includes the following steps:

Step S1-1:

Controlling all of the rotating plates 131a and 132a to rotate to a horizontal state perpendicular to the corresponding filter member 12, and then proceeds to step S1-2;

Step S1-2:

Controlling the four-layer electromagnet filter to be energized, and then proceeds to step S1-3;

Step S1-3:

Control fan 113a starts pumping, and then proceeds to step S1-4;

Step S1-4:

Determining whether the cleaning cycle is reached, it is determined that the process proceeds to step S1-5, otherwise returns to step S1-2;

Step S1-5:

Control fan 113a stops running, and then proceeds to step S1-6;

Step S1-6:

Controlling the four-layer electromagnet filter power off degaussing, and then proceeds to step S1-7;

Step S1-7:

Controlling all of the rotating plates 131a and 132a to rotate to the front side parallel to the vertical state of the corresponding filter member 12, and then proceeds to step S1-8;

Step S1-8:

Controlling the three ultrasonic vibrating members 136 to vibrate, and then proceeds to step S1-9;

Step S1-9:

Control the air supply unit 134 to supply air to the air nozzle 131b, the water supply unit 135 supplies water to the first cleaning liquid distribution tube 131c and the second cleaning liquid distribution tube, and then proceeds to step S1-10;

Step S1-10:

Control all the air nozzles 131b and 132b to make a jet, and then proceeds to step S1-11;

Step S1-11:

Control the first cleaning liquid distribution tube 131c and the second cleaning liquid distribution tube 133 to spray the cleaning liquid, and then proceeds to step S1-12;

Step S1-12:

Controlling three cleaning liquid discharge valve 137a to open for liquid discharge, and then proceeds to step S1-13;

Step S1-13:

Determining whether the set cleaning time is completed, and determining to proceed to step S1-14, otherwise returning to step S1-10;

Step S1-14:

Control all the air nozzles 131b and 132b to stop the air jet, the first cleaning liquid distribution pipe 131c and the second cleaning liquid distribution pipe 133 stop spraying the cleaning liquid, the air supply unit 134 stops the air supply, and the water supply unit 135 stops the water supply, and the three cleaning liquids The discharge valve 137a is closed and then enters an end state.

Further, in the present embodiment, the filtering device 100 may further include a solid-liquid filtering device and a cleaning liquid recycling device not shown. The solid-liquid filtering device is connected to the three cleaning liquid discharge valves 137a for solid-liquid separation of the discharged cleaning liquid adsorbing the particulate matter, separating the particulate matter from the cleaning liquid, and discharging the separated cleaning liquid to the cleaning liquid for recycling. Device. The inlet of the cleaning liquid recycler and the separator solid-liquid connection collect the cleaning liquid discharged therefrom, and the outlet is connected with the first cleaning liquid distribution pipe 131c and the second cleaning liquid distribution pipe 133, and the collected cleaning liquid is supplied to the first cleaning. The liquid distribution pipe 131c and the second cleaning liquid distribution pipe 133. This allows recycling of the cleaning fluid, further reducing costs.

Further, as shown in Fig. 1, the mother liquid storage device 200 stores the lithium hydroxide mother liquid remaining after the crystals are precipitated in the concentrated crystallizing device. Since the lithium hydroxide mother liquid has a very high hydroxide content, it is possible to efficiently absorb carbon dioxide in the air.

In the present embodiment, the absorption tower 300 has a gas inlet portion 31, an absorbent inlet portion 32, a tower body 33, a gas discharge port portion 34, a liquid discharge port portion 35, a switching valve 36, and a pH value detecting controller 37.

The main body portion of the absorption tower 300 is a common falling film absorption tower, and the main body portion herein includes a gas inlet portion 31, an absorbent inlet portion 32, a tower body 33, a gas discharge port portion 34, and a liquid discharge port portion 35.

The gas inlet portion 31 communicates with the gas outlet portion 113 in the filtration device 100 to introduce the filtered air. The flow rate of the filtered air entering from the gas inlet portion 31 is 1 to 20 m ³ /min.

The absorbent inlet portion 32 communicates with the mother liquid storage device 200, and a lithium hydroxide mother liquid is introduced as an absorbent. The flow rate of the absorbent entering from the absorbent inlet portion 32 is 0.5 to 1 m ³ /min.

The tower body 33 communicates with the gas inlet portion 31 and communicates with the absorbing liquid inlet portion 32, and absorbs carbon dioxide in the filtered air with an absorbent to obtain a carbon dioxide-free gas. Lithium carbonate produced by the lithium hydroxide mother liquor in the tower body 33 absorbs carbon dioxide, and lithium carbonate crystallizes crystals due to low solubility. Therefore, a solid-liquid separator 33-1 is attached to the lower portion of the tower body 33, and the crystal and the carbon dioxide can be absorbed. The absorbent solution is phase-separated, and the lithium carbonate crystal is sent to a causticizing device as a raw material through a pipe to carry out causticization reaction to regenerate lithium hydroxide.

The gas discharge port portion 34 communicates with the tower body 33 to discharge the carbon dioxide-free gas.

The liquid discharge port portion 35 communicates with the column body 33, and the absorbent solution that has absorbed carbon dioxide is discharged as an absorption solution.

The reversing valve 36 is mounted on the liquid discharge port portion 35, has one inlet and two outlets, the inlet is in communication with the liquid discharge port portion 35, one outlet is connected as the first outlet to the mother liquid storage device 200, and the other outlet is used as the first The second outlet is connected to the causticizing device.

The pH detecting controller 37 is connected to both the liquid discharge port portion 35 and the switching valve 36 to detect the pH value of the absorbing solution located in the liquid discharge port portion 35, and when the detection result is pH ≤ 13, it indicates that the absorbing solution is in the absorbing solution. There is a large amount of lithium carbonate (the lithium hydroxide mother liquor will generate lithium carbonate after absorbing carbon dioxide), and the control reversing valve 36 is turned to the second out. Mouth, the absorption solution is discharged to the causticizing device, causticizing reaction, and regenerating lithium hydroxide; otherwise, it indicates that the absorption solution also has good carbon dioxide absorption performance, and the control reversing valve 36 is turned to the first outlet to make the absorption solution The discharge to the mother liquor storage device 200 continues to be recycled.

Fig. 7 is a control flow chart of the pH detecting controller according to the present invention in the embodiment.

As shown in FIG. 7, the workflow of the pH detection controller 37 includes the following steps:

Step S2-1:

Detecting the pH value of the absorption solution located in the liquid discharge port portion 35, and then proceeds to step S2-2;

Step S2-2:

Determine whether the pH value ≤ 13 is established, if it is to proceed to step S2-3, otherwise proceed to step S2-4;

Step S2-3:

Controlling the diverter valve 36 to the second outlet, discharging the absorption solution to the causticizing device, and then returning to step S2-2;

Step S2-4:

The control switching valve 36 is turned to the first outlet to discharge the absorption solution to the mother liquid storage device 200, and then returns to step S2-2.

The pH detecting controller 37 continuously repeats the above process until it is turned off.

The gas drying device 400 communicates with the gas discharge port portion 34, and dries the carbon dioxide-free gas to obtain a shielding gas. The gas drying device 400 includes a gas-liquid cyclone 41, a dryer 42, and a drying control unit 43.

Figure 8 is a schematic view showing the structure of a gas-liquid cyclone separator according to the present invention in an embodiment.

As shown in FIGS. 1 and 8, the gas-liquid cyclone separator 41 has a gas-liquid inlet portion 411, a separation portion 412, a gas outlet portion 413, and a liquid outlet portion 414.

The gas-liquid inlet portion 411 communicates with the gas discharge port portion 34 to allow the carbon dioxide-free gas to enter the gas-liquid cyclone 41. An atomizing water nozzle 411-1 is installed in the gas-liquid inlet portion 411 for cleaning a trace amount of lithium carbonate solution which may be carried in the air, and collecting fine droplets in the air to increase the separation effect.

The separation unit 412 communicates with the gas-liquid inlet portion 411 to perform gas-liquid separation of the entering carbon dioxide-free gas.

The gas outlet portion 413 communicates with the separation portion 412 to discharge the separated low water content gas. The gas outlet portion 413 includes a first outlet unit 413a and a second outlet unit 413b,

The first outlet unit 413a is in communication with a causticizing device, a concentrating crystallization device, and a crystal drying device for a device having a low water content in the shielding gas for supplying a part of the low water content gas directly to the devices.

The second outlet unit 413b is in communication with the dryer 42 to deliver another portion of the low moisture content gas to the dryer 42.

The liquid outlet portion 414 is attached to the bottom of the separation portion 412 for discharging the separated liquid.

The dryer 42 communicates with the outlet portion 413 to dry the low moisture content gas. It has two drying towers 421 and a first steering valve 422 and a second steering valve 423.

Each drying tower 421 has an introduction portion 421a, a drying portion 421b, a lead portion 421c, and a heating portion 421d.

The introduction portion 421a communicates with the gas outlet portion 413 to introduce a low water content gas.

The drying portion 421b communicates with the introduction portion 421a, and is filled with a desiccant to absorb moisture in the low-moisture gas. A highly dry gas is obtained. The desiccant used is a highly water-absorbent desiccant, and after the desiccant absorbs water, the absorbed moisture can be evaporated to restore water absorption properties, thereby being able to be reused.

The lead-out unit 421c communicates with the drying unit 421b, and guides the protective gas obtained after drying.

The heating unit 421d is attached to the drying unit 421b, and heats the desiccant to remove the adsorbed moisture.

The first steering valve 422 is installed between the two drying towers 421 and the gas outlet portion 413, and has a first inlet port and two first discharge ports. The first inlet port communicates with the gas outlet portion 413, and the two first discharge ports communicate with the introduction portions 421a of the two drying towers 42, respectively.

The second steering valve 423 is installed between the two drying towers 42 and the gas storage device 40. The second steering valve 423 has two second inlets and a second outlet, the two inlets are respectively connected to the outlets 421c of the two drying towers 42, and the second inlets are connected to the gas storage device 600. ,

The drying control unit 43 is connected to the first steering valve 422 and the two heating portions 421d and the second steering valve 423. It is capable of controlling the first steering valve 422 to be in communication with the introduction portion 421a of the other drying tower 421 when the water absorption of the drying tower 421 reaches saturation, and controlling the second steering valve 423 to be diverted to the outlet of the other drying tower 42 The portion 421c is in communication with each other, and the heating portion 421d of the drying tower 42 that has reached saturation is controlled to be heated to evaporate the absorbed moisture and restore the water absorption performance.

Figure 9 is a control flow chart of the drying control unit according to the present invention in the embodiment.

As shown in FIG. 9, the workflow of the drying control unit 43 includes the following steps. For convenience of description, the two drying towers 421 are respectively referred to as a first drying tower 421 and a second drying tower 421, and the first drying tower 421 is used. The water absorption performance is saturated as an example:

Step S3-1:

Controlling the first steering valve 422 and the second steering valve 423 to respectively communicate with the introduction portion 421a and the lead-out portion 421c of the first drying tower 421, and then proceeds to step S3-2;

Step S3-2:

Determining whether the water absorption performance of the first drying tower 421 reaches saturation (can be judged by, for example, water absorption time), when it is judged as YES, proceeds to step S3-3, otherwise returns to step S3-1;

Step S3-3:

Controlling the first steering valve 422 and the second steering valve 423 to respectively communicate with the introduction portion 421a and the lead-out portion 421c of the second drying tower 421, and then proceeds to step S3-4;

Step S3-4:

The heating portion 421d that controls the first drying tower 42 is heated until the first drying tower 42 resumes water absorption performance.

The control process in which the second drying tower 421 reaches a saturated state is also the same as that of the first drying tower 421, and details are not described herein again.

The supply device 500 is in communication with the gas drying device 400 and the gas storage device 600 to provide a shielding gas to the preparation subsystem. The supply device 500 includes a pipe and a gas conveying member that communicates the first outlet unit 413a with the causticizing device, the concentrating crystallization device, and the crystal drying device, and supplies the gas storage device 600 to the crushing device and the screening packaging device. The pipeline and the gas conveying member that are supplied with the air are connected.

The gas storage device 600 communicates with the second discharge port of the second steering valve 423 to store the highly dried protective gas.

Tables 1 to 3 below are specific causticizing reactors, LiOH solution transfer and storage devices, and LiOH mother liquors in a causticizing apparatus and a concentrated crystallization apparatus, without a shielding gas, nitrogen gas as a shielding gas, and the present invention. The experimental data table for the cleaned air as a protective gas, Table 4 is the cost comparison table, using these data as an example to prove the effect of the program:

Table 1. Experiments without atmosphere protection

Table 2, experiment under nitrogen protection

Table 3, experiment under purified air protection

Table 4, nitrogen and clean air cost comparison

gas Output unit cost Input costs Nitrogen 0.5 to 0.8 yuan / m ³ Big Purifying air ≤0.1 yuan / m ³ small

It can be seen from the above table that after the shielding gas of the present invention, the content of carbonate in each device or process is effectively suppressed, and the effect is equivalent to that of using an inert gas, but the input cost is much lower than that of using an inert gas. As a solution to protect the gas.

The role and effect of the embodiment

According to the lithium hydroxide preparation system described in the embodiment, since the filter device can filter out particulate matter in the air in the protective gas supply subsystem, the absorption tower can utilize the remaining lithium hydroxide mother liquor as the absorption after the crystal is precipitated in the concentrated crystallization device. The agent absorbs the carbon dioxide in the filtered air. Since the hydrogen hydroxide concentration in the lithium hydroxide mother liquor is very high, the carbon dioxide in the air can be sufficiently absorbed, thereby achieving the purpose of effectively removing carbon dioxide, and further, the gas drying device The carbon dioxide-free gas is dried to obtain a shielding gas, and the supply device can supply the shielding gas to the preparation subsystem, so that an inexpensive gas such as air can be used as a shielding gas used in a large quantity in the preparation subsystem, thereby effectively reducing hydrogen. The cost of preparing lithium oxide.

Further, since the drying control unit 43 can control the first steering valve 422 to be in communication with the introduction portion 421a of the other drying tower 421 when the water absorption of one drying tower 421 reaches saturation, and control the second steering valve 423 to turn to another The lead-out portion 421c of one drying tower 42 is in communication, and also controls the heating of the drying tower 42 that reaches saturation. The portion 421d is heated to evaporate the absorbed moisture and restore the water absorption performance. This ensures that the gas drying process can be carried out continuously, so that the entire shielding gas supply subsystem can continuously supply gas.

In addition, since the pH detecting controller 37 can detect the pH value of the absorbing solution located in the liquid discharge port portion 35, and when the detection result is pH ≤ 13, the control switching valve 36 is diverted to the second outlet to make the absorbing solution The causticizing device is discharged to the causticizing device to regenerate lithium hydroxide; otherwise, the control diverter valve 36 is diverted to the first outlet, and the absorption solution is discharged to the mother liquid storage device 200 for further recycling. In this way, the absorption solution can be recycled reasonably, and the carbon dioxide can be effectively absorbed, and the saturated absorption solution can be returned to the causticizing device for reaction.

The gas filtration process can be carried out continuously so that the entire shielding gas supply subsystem can continuously supply gas.

Further, in the filter device, since a total of four filter screens of the two filter members are magnetic filters, magnetic foreign matter can be adsorbed, thereby effectively removing magnetic foreign matter.

Moreover, since the control unit can rotate the rotating plate to be perpendicular to the filtering member in the filtering state, thereby ensuring normal filtration, and when a large amount of dust or the like is accumulated in the filtering member and needs to be cleaned (in the cleaning state) The control unit is capable of rotating the rotating plate such that the side on which the air nozzle is mounted faces the filter member, so that the air nozzle can eject the filter member to eject the particulate matter from the filter member and spray the particulate matter toward the shell body. On the inner side wall opposite to the other side of the filter member, the cleaning liquid is sprayed along the inner side wall by the cleaning liquid distribution pipe, and the cleaning liquid to which the particulate matter adheres is discharged from the casing body through the cleaning liquid discharge valve. Therefore, the air filtering device can effectively clean the filter member without directly spraying the filter member, thereby effectively avoiding problems such as breakage and meshage caused by the filter member after water absorption, and ensuring filtration. The filtering effect and service life of the components.

Further, since the air nozzle ejects a high-pressure gas, the particulate matter can be better ejected from the filter member; and, since the air nozzle intermittently ejects the filter member at a speed of 1-10 times/second, Not only can the effect of ejecting particulate matter be further improved, but also the amount of gas used can be saved, thereby reducing the cost.

Further, since the ultrasonic vibrating member can drive the filter member to vibrate in the cleaning state, the dust on the filter net is accelerated and desorbed under the action of the ultrasonic wave, so that the cleaning effect can be further improved.

The above embodiments are merely illustrative of the technical solutions of the present invention. The lithium hydroxide preparation system according to the present invention is not limited to the structure described in the above embodiments, but is subject to the scope defined by the claims. Any modifications or additions or equivalent substitutions made by those skilled in the art to which this invention pertains are within the scope of the appended claims.

In addition, in the above embodiment, the shielding gas supply subsystem further includes a gas storage device, and the second inlet port of the second steering valve of the dryer is in communication with the gas storage device, so that the gas storage device can be used The finished highly dry protective gas is stored. In the present invention, depending on the actual situation, for example, the amount of intake air of the filter device is not large, resulting in a small amount of air output after the dryer is dried. In this case, a gas storage device can be disposed in the protective gas supply subsystem, and The supply device is brought into direct communication with the second inlet of the second steering valve of the dryer.

In addition, in the above embodiment, all of the steering valves are used to connect with the two inlet pipes or the two. Take over. The invention can also use two valve switches connected with two inlet connecting pipes, and two valve switches are connected with two sending connecting pipes, and then the control unit realizes the turning on and off functions by controlling the respective valve switches.

Further, in the above embodiment, the air filtering device has three filter members, and as the air filtering device of the present invention, it is also possible to provide only two filter members or have three or more filters depending on the actual filtering conditions. The member, and the filter particle size of the filter member can also be selected depending on the situation. The more the number of filter members, the finer the particle size and the better the filtration effect, but the filtration time will be longer and the cost will increase.

Further, in the above embodiment, in order to filter the magnetic foreign matter, the filter mesh located at the outermost layer of the first filter member and the second filter member is a magnetic filter mesh, and in the air filter device of the present invention, at least one filter member is provided At least one layer of the filter is a magnetic filter, and the magnetic foreign matter can be filtered. Similarly, the more the number of the magnetic filter, the better the effect of the magnetic difference, but the corresponding cost will increase, so it can be based on actual conditions. The need for the situation to determine the number of magnetic filters.

Claims (10)

A lithium hydroxide preparation system comprises: a preparation subsystem, which uses a lithium salt as a raw material to prepare a lithium hydroxide product through a raw material removing device, a causticizing device, a concentrated crystallization device, a crystal drying device, a crushing device, and a screening packaging device, It is characterized by: Protecting the gas supply subsystem to remove carbon dioxide from the air, thereby providing carbon dioxide-free air as a shielding gas for the preparation process of lithium hydroxide, The shielding gas supply subsystem includes: The filter device includes: a port portion that introduces outside air, a filter portion that communicates with the port portion, filters and removes particulate matter in the introduced outside air, and communicates with the filter portion, The outlet portion from which the filtered air is led; a mother liquor storage device storing the lithium hydroxide mother liquor remaining after crystals are precipitated in the concentrated crystallization device; The absorption tower has a gas inlet portion communicating with the outlet end of the valve member to introduce filtered air, and an absorbent inlet portion communicating with the mother liquid storage device to introduce the lithium hydroxide mother liquor as an absorbent a tower body communicating with the gas inlet portion and communicating with the absorption liquid inlet portion, wherein the absorbent is used to absorb carbon dioxide in the filtered air to obtain a carbon dioxide-free gas; a gas discharge port a portion communicating with the tower body to discharge the carbon dioxide-free gas; and a liquid discharge port portion communicating with the tower body to discharge the absorbent that absorbs carbon dioxide as an absorption solution; a gas drying device connected to the gas discharge port and drying the carbon dioxide-free gas to obtain the shielding gas; a supply device in communication with the gas drying device to provide the shielding gas to the preparation subsystem, Wherein the filter portion comprises at least one filter member, each of the filter members comprises a multi-layer filter, at least one of the at least one filter member being a magnetic filter. The lithium hydroxide production system according to claim 1, wherein: Wherein the filtering device has: a housing comprising: a housing body, the air inlet portion on one side of the housing body, and the air outlet portion on one side of the housing body; The filter portion includes: at least two filter members installed in the housing between the air inlet portion and the air outlet portion to filter air entering from the air inlet portion; as well as The cleaning member cleans the filter member, and the cleaned particles are washed and discharged. The lithium hydroxide production system according to claim 1, wherein: Wherein the cleaning member comprises: At least one cleaning plate unit mounted in the housing, each of the cleaning plate units being located between two adjacent filter members, having: a rotating plate rotatably mounted in the housing; An air nozzle, mounted on a front surface of the rotating plate, capable of jetting air to the filter member to eject particulate matter from the filter member; and a first cleaning liquid distribution tube mounted on a back surface of the rotating plate Spraying the cleaning liquid on the back side; a blower unit mounted in the housing at the air outlet portion and the closest to the air outlet portion Between the filter members, having: the rotating plate and a plurality of the air nozzles; a second cleaning liquid distribution tube mounted on an inner wall of the shell body, spraying a cleaning liquid along an inner side wall of the shell body opposite to the other side of the filter member; a cleaning control unit connected to all of the rotating plates, controlling each of the rotating plates to rotate perpendicular to the filtering member in a filtering state, and rotating in a cleaning state to face the filtering toward the filtering Component; The cleaning liquid discharge unit is attached to the bottom of the casing body, and discharges the cleaning liquid to which the particulate matter adheres from the casing body. The lithium hydroxide production system according to claim 1, wherein: Wherein the absorption tower is a falling film absorption tower, The absorption tower further has: a reversing valve installed on the liquid discharge port portion, having an inlet and two outlets, the inlet being in communication with the liquid discharge port portion, and the outlet being the first outlet In communication with the mother liquor storage device, the other of the outlets is in communication with the causticizing device as a second outlet. The lithium hydroxide production system according to claim 4, wherein: Wherein the absorption tower further has: a pH detecting controller connected to the liquid discharge port portion and the reversing valve, detecting a pH value of the absorption solution located in the liquid discharge port portion, and Controlling that the diverter valve is diverted to the second outlet when the detection result is pH ≤13, so that the absorption solution is discharged to the causticizing device; otherwise, the reversing valve is controlled to turn to the first An outlet for discharging the absorption solution to the mother liquor storage device. The lithium hydroxide production system according to claim 1, wherein: The flow rate of the absorbent entering from the inlet portion of the absorbent is 0.5 to 1 m ³ /min, and the flow rate of the filtered air entering from the gas inlet portion is 1 to 20 m ³ /min. The lithium hydroxide production system according to claim 1, wherein: Wherein the gas drying device comprises: The gas-liquid cyclone separator has a gas-liquid inlet portion communicating with the gas discharge port portion to allow the carbon dioxide-free gas to enter, and a separation portion communicating with the gas-liquid inlet portion to enter the gas-free portion Carbon dioxide gas is subjected to gas-liquid separation; and an outlet portion is connected to the separation portion to discharge the separated low-moisture gas; and A dryer is connected to the outlet portion to dry the low moisture content gas. The lithium hydroxide production system according to claim 7, wherein: Wherein the outlet portion includes a first outlet unit and a second outlet unit, The first outlet unit is in communication with the causticizing device, the concentrated crystallization device, and the crystal drying device for supplying a portion of the low moisture content gas, The second outlet unit is in communication with the dryer and another portion of the low moisture content gas is sent to the dryer. The lithium hydroxide production system according to claim 7 or 8, wherein: Wherein the dryer has: at least two drying towers and a first steering valve, Each of the drying towers has: an introduction portion communicating with the outlet portion to introduce the low water content gas; a drying portion communicating with the introduction portion, filling a desiccant, absorbing the low portion Water in the moisture content gas; the lead-out portion is connected to the drying portion, and the protective gas obtained after drying is led out; and the heating portion is attached to the drying portion, and the desiccant is heated and removed Adsorbed moisture, The first steering valve is installed between all the drying towers and the outlet portion, and has: a first inlet port and at least two first discharge ports, wherein the first inlet port is connected to the outlet portion Passing, at least two of the first discharge ports are respectively in communication with the introduction portion of at least two of the drying towers, The gas drying device further includes a drying control unit, The drying control unit is coupled to the first steering valve and the two heating portions, and is configured to control the first steering valve to be turned to at least one of the other when at least one of the drying towers reaches water saturation The introduction portion of the drying tower is in communication, and the heating portion of the at least one drying tower that has reached saturation is controlled to perform the heating. The lithium hydroxide preparation system according to claim 9, further comprising: a gas storage device communicating with the outlet portions of the two drying towers to store the shielding gas, The dryer further has a second steering valve installed between the two drying towers and the gas storage device, having: two second inlets and one second outlet, two The second inlet port is respectively connected to the lead-out portions of the two drying towers, and the second inlet port is in communication with the gas storage device. The drying control unit is further connected to the second steering valve, and when the water absorption of the drying tower reaches saturation, the second steering valve is further controlled to be in communication with the outlet portion of the other drying tower. .

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