A device system for preparing battery-grade lithium hydroxide

Abstract

The utility model provides a kind of preparation device system of battery-grade lithium hydroxide, including the feed unit, pretreatment unit, extraction-stripping unit, electrodialysis unit and evaporation unit connected in turn;The extraction-stripping unit includes the extraction module and stripping module of cyclic connection, the extraction module is connected the pretreatment unit, the stripping module is connected the inlet of the electrodialysis unit, the electrodialysis unit is provided three-way outlet, one way is connected the stripping module, one way is connected the evaporation unit, another is connected the feed unit.The utility model shortens lithium hydroxide preparation process, effectively improves lithium yield, improves product purity.

Description

Technical Field

[0001] This utility model belongs to the field of lithium hydroxide preparation technology, and relates to a preparation device system for battery-grade lithium hydroxide. Background Technology

[0002] Lithium hydroxide is an important lithium compound widely used in many industries such as chemical raw materials, chemical reagents, petroleum, metallurgy, glass, and ceramics. It is also one of the main materials for the cathode of ternary high-nickel lithium batteries. Its price is higher than that of lithium carbonate, and the market demand is large.

[0003] Currently, methods for preparing lithium hydroxide include limestone roasting, pressure leaching, ion-exchange membrane electrolysis, lithium carbonate causticizing, and precipitation. However, these methods suffer from drawbacks such as stringent operating conditions, complex and cumbersome processes, and low economic efficiency. Furthermore, the limestone roasting method is generally suitable for lithium ore, and the waste generated during the preparation process has a certain environmental impact. The precipitation method involves adding a lithium carbonate solution to limewater, utilizing the difference in solubility to allow lithium carbonate to react with calcium hydroxide to form calcium carbonate precipitate and lithium hydroxide product. The calcium carbonate precipitate is then separated by filtration, and the lithium hydroxide product is prepared by crystallization. However, the precipitation method consumes a large amount of quicklime and produces difficult-to-treat calcium carbonate waste, which has a significant environmental impact. In addition, the resulting lithium hydroxide product has a high calcium content, requiring further purification, making the process lengthy and complex.

[0004] Therefore, proposing a device for directly producing battery-grade lithium hydroxide from industrial-grade crude lithium carbonate is of great significance for the diversified use of lithium resources. Utility Model Content

[0005] In view of the shortcomings of the existing technology, the purpose of this utility model is to provide a preparation device system for battery-grade lithium hydroxide, which effectively removes impurities from the raw materials, realizes the separation of lithium from other element ions, reduces lithium loss, improves lithium yield, and improves the purity of battery-grade lithium hydroxide products.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] This invention provides a device system for preparing battery-grade lithium hydroxide. The device system includes a feeding unit, a pretreatment unit, an extraction-back-extraction unit, an electrodialysis unit, and an evaporation unit connected in sequence. The extraction-back-extraction unit includes an extraction module and a back-extraction module connected in a loop. The extraction module is connected to the pretreatment unit, and the back-extraction module is connected to the inlet of the electrodialysis unit. The electrodialysis unit has three outlets: one connected to the back-extraction module, one connected to the evaporation unit, and the other connected to the feeding unit.

[0008] The process of this invention is short. It removes suspended solids and impurity ions from the raw materials through a pretreatment unit, and then uses an extraction-back-extraction process to achieve efficient separation of lithium from other elements in the raw materials and further remove impurities. Subsequently, the combined process of electrodialysis and evaporation is used to greatly improve the lithium recovery rate and achieve product refining and purification.

[0009] As a preferred embodiment of this utility model, the feeding unit includes a feeding device and a dissolving device connected to each other, and the dissolving device is connected to the outlet of the pretreatment unit and the outlet of the electrodialysis unit respectively.

[0010] This invention is applicable to the processing of solid raw materials. The solid raw materials are fed into the dissolving device by a feeding device to dissolve them and obtain a raw material solution containing impurities, so that the impurities can be efficiently removed by a subsequent pretreatment unit.

[0011] As a preferred embodiment of the present invention, the pretreatment unit includes at least two stages of filtration devices connected in sequence, the first stage of the filtration device being connected to the dissolving device, and the last stage of the filtration device being connected to the extraction-re-extraction unit.

[0012] This invention uses a filtration device with at least two stages to perform multi-stage filtration of the raw material solution, which fully removes suspended solids from the solution and initially removes impurity ions such as calcium and magnesium from the solution, reducing the pressure of subsequent impurity removal and preventing impurities in the solution from reducing the purity of the product.

[0013] As a preferred embodiment of this utility model, the extraction module includes an empty lithium extraction device and a washing device that are connected in a cycle, and the empty lithium extraction device is connected to the pretreatment unit.

[0014] The back-extraction module includes a lithium-loaded back-extraction device, which is connected to the washing device and the empty lithium extraction device respectively. The lithium-loaded back-extraction device is also cyclically connected to the electrodialysis unit.

[0015] This invention introduces an extraction module to achieve deep separation and washing of lithium ions from other impurities by using an extractant to extract lithium from the raw material solution after preliminary impurity removal. It further removes calcium, magnesium, and other cations and / or anions from the solution. Then, a lithium-loaded back-extraction device is used to back-extract the lithium-loaded extractant to obtain a high-purity lithium-containing solution, which effectively improves the purity of subsequent products and shortens the overall process flow.

[0016] As a preferred embodiment of this utility model, the extraction module includes at least two stages of empty lithium extraction devices and at least two stages of washing devices connected in sequence; the back-extraction module includes at least two stages of loaded lithium back-extraction devices connected in sequence; the first stage of the empty lithium extraction device is connected to the last stage of the loaded lithium back-extraction device; the last stage of the empty lithium extraction device is connected to the pretreatment unit; the first stage of the washing device is cyclically connected to the last stage of the empty lithium extraction device; the last stage of the washing device is connected to the first stage of the loaded lithium back-extraction device; the first stage of the loaded lithium back-extraction device is also connected to the inlet end of the electrodialysis unit; the last stage of the loaded lithium back-extraction device is also connected to the outlet end of the electrodialysis unit.

[0017] This invention introduces a multi-stage extraction-washing-back-extraction process to efficiently separate lithium ions from impurity elements in the raw material solution after preliminary impurity removal, fully extracting lithium ions and effectively increasing the yield of lithium hydroxide products.

[0018] As a preferred embodiment of the present invention, the electrodialysis unit includes a bipolar membrane electrodialysis device.

[0019] This invention utilizes bipolar membrane electrodialysis to process lithium-containing solutions, producing crude lithium hydroxide while simultaneously generating various high-value byproducts. This enhances the economic efficiency of the lithium hydroxide production process and enables internal system circulation, thereby improving the utilization rate of raw materials and other required materials.

[0020] As a preferred embodiment of this invention, the bipolar membrane electrodialysis device is provided with an acid outlet, an alkali outlet and a dilute salt solution outlet; the acid outlet is connected to the back-extraction module, the alkali outlet is connected to the evaporation unit, and the dilute salt solution outlet is connected to the pretreatment unit.

[0021] This invention obtains different by-product raw materials from different outlets of a bipolar membrane electrodialysis device, and achieves internal recycling of raw materials through connection and layout with internal units, thereby achieving energy saving.

[0022] As a preferred embodiment of the present invention, the evaporation unit includes a primary evaporation device, a recrystallization device, and a drying device connected in sequence, wherein the primary evaporation device is connected to the electrodialysis unit.

[0023] This invention enables the evaporation, recrystallization, and drying of crude lithium hydroxide to obtain battery-grade lithium hydroxide products.

[0024] As a preferred embodiment of the present invention, the evaporation unit further includes a secondary evaporation device, a refrigeration device, and a centrifugal separation device connected in sequence, wherein the secondary evaporation device is connected to the primary evaporation device.

[0025] This invention adds a secondary evaporation unit to process the raw materials generated by the bipolar membrane electrodialysis device, obtaining sodium hydroxide as a byproduct, thereby improving the lithium yield of the entire system.

[0026] As a preferred embodiment of this utility model, the evaporation unit further includes a three-stage evaporation device, the inlet of which is connected to the two-stage evaporation device, the outlet of which is connected to the one-stage evaporation device, and the three-stage evaporation device is also connected to the outside.

[0027] This invention adds a third-stage evaporation unit to further process the mother liquor produced by the second-stage evaporation unit, concentrates the lithium hydroxide and sodium hydroxide products in the mother liquor, reuses the lithium hydroxide by-product in the first-stage evaporation unit for internal use, and sells the sodium hydroxide by-product externally, thereby further improving the lithium yield.

[0028] The system refers to an equipment system, device system, or production device.

[0029] Compared with the prior art, the beneficial effects of this utility model are as follows:

[0030] (1) This utility model shortens the lithium hydroxide preparation process by connecting and synergistically working the various units, omits the alkali causticization in the traditional process, has a lower dependence on raw materials, and improves the overall economic benefits.

[0031] (2) By setting up an extraction-re-extraction unit, the present invention performs single element extraction on the solution after the raw material has been initially purified, thereby achieving efficient separation of lithium ions from other anions and cations, reducing the burden of subsequent impurity removal, and providing a prerequisite for the preparation of battery-grade lithium carbonate.

[0032] (3) This utility model introduces bipolar membrane electrodialysis to prepare lithium hydroxide, while obtaining a variety of by-products and returning them to other processing units, realizing the internal recycling of the device system, thereby achieving the purpose of energy saving, and also solving the problem of long-distance transportation of raw materials. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the apparatus system for preparing battery-grade lithium hydroxide provided in Example 1.

[0034] Figure 2 This is a schematic diagram of the apparatus system for preparing battery-grade lithium hydroxide provided in Example 2.

[0035] Figure 3 This is a schematic diagram of the apparatus system for preparing battery-grade lithium hydroxide provided in Example 3.

[0036] Figure 4This is a schematic diagram of the apparatus system for preparing battery-grade lithium hydroxide provided in Example 4.

[0037] Figure 5 This is a schematic diagram of the apparatus system for preparing battery-grade lithium hydroxide provided in Example 5.

[0038] Figure 6 This is a schematic diagram of the apparatus system for preparing battery-grade lithium hydroxide provided in Example 6.

[0039] Among them, 11-feeding device; 12-dissolving device; 21-first filtration device; 22-second filtration device; 31-empty lithium extraction device; 32-washing device; 33-loaded lithium back-extraction device; 41-bipolar membrane electrodialysis device; 51-first-stage evaporation device; 52-recrystallization device; 53-drying device; 61-second-stage evaporation device; 62-freezing device; 63-centrifugal separation device; 71-third-stage evaporation device; 311-first-stage empty lithium extraction device; 312-second-stage empty lithium extraction device; 321-first-stage washing device; 322-second-stage washing device; 331-first-stage loaded lithium back-extraction device; 332-second-stage loaded lithium back-extraction device. Detailed Implementation

[0040] It should be understood that in the description of this utility model, the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used solely for the convenience of describing this utility model and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this utility model. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this utility model, unless otherwise stated, "a plurality of" means two or more.

[0041] It should be noted that, in the description of this utility model, unless otherwise explicitly specified and limited, the terms "set," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model based on the specific circumstances.

[0042] Those skilled in the art should understand that this utility model necessarily includes the necessary pipelines, conventional valves and general pump equipment for achieving complete process, but the above content is not the main utility model point of this utility model. Those skilled in the art can add layouts based on process flow and equipment structure selection. This utility model does not make any special requirements or specific limitations in this regard.

[0043] The technical solution of this utility model will be further described below with reference to the accompanying drawings and specific embodiments.

[0044] In one specific embodiment, the present invention provides a device system for preparing battery-grade lithium hydroxide, comprising a feeding unit, a pretreatment unit, an extraction-re-extraction unit, an electrodialysis unit and an evaporation unit connected in sequence, to produce battery-grade lithium hydroxide product using industrial-grade crude lithium carbonate solid as raw material.

[0045] The feeding unit includes an interconnected feeding device and a dissolving device, with the dissolving device connected to the outlets of both the pretreatment unit and the electrodialysis unit. In application, the feeding device transports the unpacked industrial-grade crude lithium carbonate solid to the dissolving device. An alkaline additive is added to dissolve the solid raw material into a lithium carbonate solution containing impurities. The alkaline additive used in the dissolving device is a byproduct of the electrodialysis unit, or it can be a prepared lithium hydroxide product solution, reducing the need for external raw material replenishment and lowering process costs. The required dissolving water is recycled from the permeate of the electrodialysis unit, while additional dilute brine is added to control the lithium carbonate concentration in the lithium carbonate solution. The feeding device can be a belt conveyor; the dissolving device includes a dissolving kettle, or other commonly used devices in the art, which are not specifically limited in this invention.

[0046] The pretreatment unit includes at least two sequentially connected filtration stages. The first stage filtration stage is connected to the dissolution device, and the last stage filtration stage is connected to the extraction-back-extraction unit. This process filters out suspended solids from the lithium carbonate solution and preliminarily removes impurities such as calcium and magnesium before transporting the solution to the extraction-back-extraction unit. This invention does not specifically limit the type of filtration device; those skilled in the art can select any one or a combination of at least two of nanofiltration, microfiltration, or ultrafiltration according to process requirements. That is, all filtration devices can employ the same filtration mode or a combination of different filtration modes, such as a combination of microfiltration and nanofiltration, nanofiltration and ultrafiltration, or ultrafiltration and microfiltration, etc.

[0047] The extraction-re-extraction unit includes an extraction module and a reciprocating extraction module. The extraction module is connected to the pretreatment unit, and the re-extraction module is connected to the inlet of the electrodialysis unit. This invention provides two layout schemes for the extraction-re-extraction unit according to different process requirements.

[0048] Option 1: Single-stage extraction-back-extraction only. The extraction module includes a circulating empty lithium extraction device and a washing device, the empty lithium extraction device being connected to the pretreatment unit; the back-extraction module includes a loaded lithium back-extraction device, the loaded lithium back-extraction device being connected to both the washing device and the empty lithium extraction device, and the loaded lithium back-extraction device also being circulatingly connected to the electrodialysis unit.

[0049] Option 2: Multi-stage extraction-back-extraction. The extraction module includes at least two sequentially connected stages of unloaded lithium extraction devices and at least two sequentially connected washing devices; the back-extraction module includes at least two sequentially connected stages of loaded lithium back-extraction devices; the first-stage unloaded lithium extraction device is connected to the last-stage loaded lithium back-extraction device; the last-stage unloaded lithium extraction device is connected to the pretreatment unit; the first-stage washing device is cyclically connected to the last-stage unloaded lithium extraction device; the last-stage washing device is connected to the first-stage loaded lithium back-extraction device; the first-stage loaded lithium back-extraction device is also connected to the inlet of the electrodialysis unit; the last-stage loaded lithium back-extraction device is also connected to the outlet of the electrodialysis unit.

[0050] It should be noted that the number of stages in the empty lithium extraction device can be 2 to 10, the number of stages in the washing device can be 2 to 5, and the number of stages in the loaded lithium back-extraction device can be 2 to 3. When there are two stages in the empty lithium extraction device, washing device, or loaded lithium back-extraction device, the last stage is the second stage device. Furthermore, the number of stages in the empty lithium extraction device, washing device, and loaded lithium back-extraction device can be the same or different.

[0051] The empty-load lithium extraction device utilizes an extractant to extract lithium ions from a crude lithium carbonate solution, thereby separating lithium ions from other cations in the crude lithium carbonate solution, such as calcium, magnesium, sodium, and potassium, and simultaneously separating lithium ions from other anions in the crude lithium carbonate solution, such as chloride, sulfate, nitrate, and fluoride ions. The separated cations and anions are discharged from the system as tailings. After the extractant extracts lithium ions, a lithium-loaded extractant is formed, which then enters the washing section of the extraction module. The lithium-loaded extractant is washed with a washing liquid to remove impurities entrained on its surface, achieving further purification of the lithium-loaded extractant. The washing liquid used in the washing section contains not only the washed-off impurities but also a small amount of lithium ions. The purified washing liquid is returned to the empty-load lithium extraction device for further lithium resource recovery, while the washed-off impurities are discharged from the system along with the tailings. In the lithium-loaded back-extraction device, the back-extraction liquid and the lithium-loaded extractant undergo an exchange reaction in a countercurrent manner. The resulting empty-loaded extractant is reused in the extraction module, while the purified lithium sulfate solution enters the electrodialysis unit. The stripping agent can be a sulfuric acid solution commonly used in this field.

[0052] The electrodialysis unit has three outlets: one connected to the back-extraction module, one to the evaporation unit, and the other to the feed unit. The electrodialysis unit includes a bipolar membrane electrodialysis device. Specifically, the bipolar membrane electrodialysis device has an acid outlet, an alkali outlet, and a dilute brine outlet; the acid outlet is connected to the back-extraction module, the alkali outlet is connected to the evaporation unit, and the dilute brine outlet is connected to the pretreatment unit. The first permeate produced by the bipolar membrane electrodialysis device is returned to the back-extraction module via the acid outlet for recycling as a back-extraction agent. The second permeate produced by the bipolar membrane electrodialysis device is returned to the evaporation unit via the alkali outlet for concentration to obtain crude lithium hydroxide, which is used to prepare the final battery-grade lithium hydroxide product. The third permeate produced by the bipolar membrane electrodialysis device is returned to the pretreatment unit via the dilute brine outlet for further lithium recovery, thus achieving internal recycling.

[0053] The bipolar membrane electrodialysis device utilizes the water dissociation properties of the bipolar membrane and the selective permeability of conventional anion and cation membranes to convert salts into acids and bases. The device comprises several cation and anion membranes, as well as a saline chamber located between them, as is well known to those skilled in the art. Under the influence of an electric field, ions migrate directionally and selectively permeate the membranes, causing the bipolar membrane to dissociate water into H+. + and OH - Cations migrate towards the cathode, permeate the cation exchange membrane, and react with OH- generated by the bipolar membrane. -The reaction produces alkali, which flows out through the alkali outlet; anions migrate towards the anode, permeate the anion membrane, and combine with H+ ions generated by the bipolar membrane to form acid, which flows out through the acid outlet. Concentrated brine passes through the brine chamber to form dilute brine, which is discharged through the dilute brine outlet. Under the influence of the electric field, the two-stage membrane electrodialysis unit produces an acidic first product, an alkali second product, mainly containing lithium hydroxide and a small amount of sodium hydroxide; and a dilute brine containing lithium sulfate, which is returned to the dissolution unit of the pretreatment unit to be used as makeup water for preparing lithium carbonate solution and to further recover lithium ions.

[0054] The evaporation unit comprises a primary evaporator, a recrystallization unit, and a drying unit connected in sequence. The primary evaporator is connected to the electrodialysis unit. The second permeate produced by the electrodialysis unit is a mixture mainly containing lithium hydroxide, with small amounts of sodium hydroxide and sulfate. The second permeate enters the primary evaporator to separate lithium hydroxide from the mixture of sodium hydroxide and sulfate. Under the effect of the common ion effect, after the water in the mixture evaporates, aluminum hydroxide preferentially crystallizes out, yielding crude lithium hydroxide and a first mother liquor. The first mother liquor mainly contains sodium hydroxide and sulfate. The first product then enters the recrystallization unit for secondary recrystallization, yielding battery-grade lithium hydroxide and a second mother liquor. The battery-grade lithium hydroxide is then packaged and recycled.

[0055] Furthermore, the evaporation unit also includes a secondary evaporator, a refrigeration unit, and a centrifugal separator connected in sequence, with the secondary evaporator connected to the primary evaporator. The first mother liquor produced by the primary evaporator contains a small amount of lithium, which is then passed sequentially through the secondary evaporator to further concentrate the sodium hydroxide, sulfate, and lithium hydroxide to obtain the second product and the third mother liquor. The second product mainly contains sulfate and sodium hydroxide, and is sent to the refrigeration unit. The third mother liquor mainly contains sodium hydroxide, lithium hydroxide, and a small amount of sulfate, thereby improving the overall lithium yield of the system. The refrigeration unit precipitates sodium sulfate from the second product, and the third product and the fourth mother liquor are efficiently separated by the centrifugal separator. The third product is sodium sulfate decahydrate, which serves as the outlet for sulfate in the system, while the fourth mother liquor mainly contains sodium hydroxide and lithium hydroxide.

[0056] Furthermore, the evaporation unit also includes a three-stage evaporation device. The inlet of the three-stage evaporation device is connected to the two-stage evaporation device, and the outlet of the three-stage evaporation device is connected to the one-stage evaporation device. The three-stage evaporation device is also connected to the outside environment. The fourth mother liquor is fed into the three-stage evaporation device for further concentration to obtain a fourth product and a fifth mother liquor. The fourth product is returned to the one-stage evaporation device to prepare lithium hydroxide, improving the overall lithium yield. The fifth mother liquor mainly contains sodium hydroxide and is used internally as a byproduct or sold externally.

[0057] Example 1

[0058] This embodiment provides a device system for preparing battery-grade lithium hydroxide, including a feeding unit, a pretreatment unit, an extraction-back-extraction unit, an electrodialysis unit, and an evaporation unit connected in sequence. Figure 1 As shown, the feeding unit includes a feeding device 11 and a dissolving device 12. The pretreatment unit includes a first filter device 21 and a second filter device 22 connected in sequence. The extraction-back-extraction unit includes an empty lithium extraction device 31, a washing device 32, and a loaded lithium back-extraction device 33 connected in sequence. The electrodialysis unit includes a bipolar membrane electrodialysis device 41, which is provided with an acid outlet, an alkali outlet, and a dilute brine outlet. The evaporation unit includes a primary evaporation device 51, a recrystallization device 52, and a drying device 53 connected in sequence. The feeding device 11 is a belt conveyor used to receive unpacked industrial-grade lithium carbonate solids. The dissolving device 12 is connected to the first filter device 21, and the second filter device 22 is connected to the empty lithium extraction device 31. The empty lithium extraction device 31 is cyclically connected to the washing device 32, which is connected to the inlet of the loaded lithium back-extraction device 33. The loaded lithium back-extraction device 33 is provided with two outlets, one of which is connected to the empty lithium extraction device 31, and the other of which is connected to the acid outlet of the bipolar membrane electrodialysis device 41. The alkaline solution outlet of the bipolar membrane electrodialysis device 41 is connected to the primary evaporation device 51, and the dilute saline solution outlet of the bipolar membrane electrodialysis device 41 is connected to the dissolving device 12.

[0059] Example 2

[0060] This embodiment provides a device system for preparing battery-grade lithium hydroxide, which differs from Embodiment 1 in that: Figure 2 As shown, the evaporation unit also includes a secondary evaporation device 61, a refrigeration device 62 and a centrifugal separation device 63 connected in sequence. The secondary evaporation device 61 is connected to the primary evaporation device 51, and the rest of the structure is the same as in Embodiment 1.

[0061] Example 3

[0062] This embodiment provides a device system for preparing battery-grade lithium hydroxide, which differs from Embodiment 2 in that: Figure 3 As shown, the evaporation unit also includes a three-stage evaporation device 71. The inlet of the three-stage evaporation device 71 is connected to the two-stage evaporation device 61. The three-stage evaporation device 71 is provided with two outlets. One outlet is connected to the first-stage evaporation device 51, and the other outlet is connected to the outside. The rest of the structure is the same as in Embodiment 2.

[0063] Example 4

[0064] This embodiment provides a device system for preparing battery-grade lithium hydroxide, including a feeding unit, a pretreatment unit, an extraction-back-extraction unit, an electrodialysis unit, and an evaporation unit connected in sequence. Figure 4As shown, the feeding unit includes a feeding device 11 and a dissolving device 12. The pretreatment unit includes a first filtration device 21 and a second filtration device 22 connected in sequence. The extraction-back-extraction unit includes a first-stage empty lithium extraction device 311 and a second-stage empty lithium extraction device 312 connected to each other, a first-stage washing device 321 and a second-stage washing device 322 connected to each other, and a first-stage loaded lithium back-extraction device 331 and a second-stage loaded lithium back-extraction device 332 connected to each other. The electrodialysis unit includes a bipolar membrane electrodialysis device 41, which is provided with an acid outlet, an alkali outlet, and a dilute brine solution outlet. The evaporation unit includes a first-stage evaporation device 51, a recrystallization device 52, and a drying device 53 connected in sequence. The feeding device 11 is a belt conveyor used to receive unpacked industrial-grade lithium carbonate solids. The dissolving device 12 is connected to the first filtration device 21. The second filtration device 22 is connected to the second-stage empty lithium extraction device 312. The first-stage empty lithium extraction device 311 is connected to both the first washing device and the second-stage loaded lithium back-extraction device 332. The second-stage empty lithium extraction device 312 is cyclically connected to the first washing device. The second-stage washing device 322 is connected to the first-stage loaded lithium back-extraction device 331. The first-stage loaded lithium back-extraction device 331 is connected to the inlet of the bipolar membrane electrodialysis device 41. The second-stage loaded lithium back-extraction device is connected to the acid outlet of the bipolar membrane electrodialysis device 41. The alkaline outlet of the bipolar membrane electrodialysis device 41 is connected to the first-stage evaporation device 51, and the dilute brine outlet of the bipolar membrane electrodialysis device 41 is connected to the dissolving device 12.

[0065] Example 5

[0066] This embodiment provides a device system for preparing battery-grade lithium hydroxide, which differs from Embodiment 4 in that: Figure 5 As shown, the evaporation unit also includes a secondary evaporation device 61, a refrigeration device 62 and a centrifugal separation device 63 connected in sequence. The secondary evaporation device 61 is connected to the primary evaporation device 51, and the rest of the structure is the same as in Embodiment 4.

[0067] Example 6

[0068] This embodiment provides a device system for preparing battery-grade lithium hydroxide, which differs from Embodiment 5 in that: Figure 6 As shown, the evaporation unit also includes a three-stage evaporation device 71. The inlet of the three-stage evaporation device 71 is connected to the two-stage evaporation device 61. The three-stage evaporation device 71 is provided with two outlets. One outlet is connected to the first-stage evaporation device 51, and the other outlet is connected to the outside. The rest of the structure is the same as in embodiment 5.

[0069] The applicant declares that the above description is only a specific embodiment of the present utility model, but the protection scope of the present utility model is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present utility model fall within the protection and disclosure scope of the present utility model.

Claims

1. A device system for preparing battery-grade lithium hydroxide, characterized in that, The preparation apparatus system includes a feeding unit, a pretreatment unit, an extraction-back-extraction unit, an electrodialysis unit, and an evaporation unit connected in sequence. The extraction-back-extraction unit includes an extraction module and a back-extraction module connected in a loop. The extraction module is connected to the pretreatment unit, and the back-extraction module is connected to the inlet of the electrodialysis unit. The electrodialysis unit has three outlets: one connected to the back-extraction module, one connected to the evaporation unit, and the other connected to the feeding unit.

2. The apparatus system for preparing battery-grade lithium hydroxide according to claim 1, characterized in that, The feeding unit includes a feeding device and a dissolving device connected to each other. The dissolving device is connected to the outlet of the pretreatment unit and the electrodialysis unit, respectively.

3. The apparatus system for preparing battery-grade lithium hydroxide according to claim 2, characterized in that, The pretreatment unit includes at least two stages of filtration devices connected in sequence, with the first stage of filtration device connected to the dissolving device and the last stage of filtration device connected to the extraction-re-extraction unit.

4. The apparatus system for preparing battery-grade lithium hydroxide according to any one of claims 1-3, characterized in that, The extraction module includes an empty lithium extraction device and a washing device connected in a cycle, and the empty lithium extraction device is connected to the pretreatment unit. The back-extraction module includes a lithium-loaded back-extraction device, which is connected to the washing device and the empty lithium extraction device respectively. The lithium-loaded back-extraction device is also cyclically connected to the electrodialysis unit.

5. The apparatus system for preparing battery-grade lithium hydroxide according to any one of claims 1-3, characterized in that, The extraction module includes at least two stages of unloaded lithium extraction devices and at least two stages of washing devices connected in sequence; the back-extraction module includes at least two stages of loaded lithium back-extraction devices connected in sequence. The first-stage empty lithium extraction device is connected to the last-stage loaded lithium back-extraction device. The final stage of the empty lithium extraction device is connected to the pretreatment unit; The first-stage washing device is cyclically connected to the last-stage empty lithium extraction device. The final stage washing device is connected to the first stage lithium-loaded back-extraction device; The first-stage lithium-loaded back-extraction device is also connected to the inlet of the electrodialysis unit; The final stage of the lithium-loaded back-extraction device is also connected to the outlet of the electrodialysis unit.

6. The apparatus system for preparing battery-grade lithium hydroxide according to claim 1, characterized in that, The electrodialysis unit includes a bipolar membrane electrodialysis device.

7. The apparatus system for preparing battery-grade lithium hydroxide according to claim 6, characterized in that, The bipolar membrane electrodialysis device is equipped with an acid outlet, an alkaline outlet and a dilute saline solution outlet. The acid solution outlet is connected to the back-extraction module, the alkali solution outlet is connected to the evaporation unit, and the dilute salt solution outlet is connected to the pretreatment unit.

8. The apparatus system for preparing battery-grade lithium hydroxide according to claim 1, 6, or 7, characterized in that, The evaporation unit includes a primary evaporator, a recrystallization unit, and a drying unit connected in sequence, with the primary evaporator connected to the electrodialysis unit.

9. The apparatus system for preparing battery-grade lithium hydroxide according to claim 8, characterized in that, The evaporation unit further includes a secondary evaporation device, a refrigeration device, and a centrifugal separation device connected in sequence, wherein the secondary evaporation device is connected to the primary evaporation device.

10. The apparatus system for preparing battery-grade lithium hydroxide according to claim 9, characterized in that, The evaporation unit also includes a three-stage evaporation device. The inlet of the three-stage evaporation device is connected to the two-stage evaporation device, and the outlet of the three-stage evaporation device is connected to the one-stage evaporation device. The three-stage evaporation device is also connected to the outside environment.

Images