Recycling Method and Device for Waste Lithium Battery Electrolyte

Abstract

A recycling method based on waste lithium battery electrolyte wastewater comprises the following steps: performing a pressure filtration operation on the waste lithium battery electrolyte wastewater; mixing the electrolyte filtrate with a soluble salt and then performing a salting-out separation operation; performing a fine separation operation on the crude liquid separation; mixing the first high-salt water and the second high-salt water and then performing a gas flotation oil removal operation; performing a freezing crystallization operation on the third high-salt water to obtain lithium-rich water containing salting-out salt crystals; performing a solid-liquid separation operation on the lithium-rich water containing salting-out salt crystals; mixing the lithium-rich water and a carbonate and then performing a precipitation separation operation.

Description

Technical Field

[0001] The present application relates to a method and device for recycling waste lithium battery electrolyte. Background Art

[0002] The electrolyte is a key material for lithium batteries, with a mass fraction of about 15% in lithium batteries and a large consumption. In the waste lithium battery recycling process, a large amount of water is required in the processes of battery discharge pretreatment, electrolyte waste gas spray treatment, and battery crushing treatment. At the same time, the electrolyte will also enter the water. Therefore, a large amount of waste lithium battery electrolyte wastewater will be generated in the waste lithium battery recycling process. However, at present, the recycling and utilization of electrolytes in the field of waste lithium battery recycling are very few, causing a double pressure on the environment and resources.

[0003] The electrolyte generally consists of high-purity organic solvents (such as dimethyl carbonate (DMC), ethylene carbonate (EC), etc.), electrolyte lithium salts (such as lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate (LiAsF6), etc.), and necessary additives. Among them, the electrolyte solvent has a stable structure and is difficult to oxidize and degrade. Entering the water will greatly increase the COD in the water body. When the electrolyte lithium salt meets water, chemical reactions such as hydrolysis can occur, causing heavy metal pollution. If the electrolyte wastewater cannot be properly treated, it will seriously endanger the ecological environment and human health. Currently, the commonly used methods for treating electrolyte wastewater include activated carbon adsorption method, precipitation-biological method, and advanced oxidation technology (such as electro-Fenton method, Fe / C micro-electrolysis-Fenton method, etc.). Among them, after the activated carbon in the activated carbon adsorption method adsorbs organic substances, it needs to be desorbed and regenerated before it can be reused; the precipitation-biological method needs to be treated with a flocculant first, and then the wastewater is adjusted to meet the biochemical conditions before the COD can be removed; the advanced oxidation technology needs to add various reagents or an external power supply after coagulation, precipitation, and pH adjustment to remove the COD. Moreover, these methods can only degrade the organic components in the water and cannot recycle and reuse the organic components. Therefore, these methods have the following defects: low COD treatment efficiency and inability to recycle and reuse the stable electrolyte, and the treatment cost pressure is extremely high for a huge amount of wastewater.

[0004] Therefore, how to separate and recycle the stable electrolyte from the wastewater of the waste lithium battery recycling line, reduce the COD of the wastewater, and reduce the wastewater treatment cost is an urgent problem to be solved at present. Summary of the Invention

[0005] Based on this, it is necessary to provide a recycling and treatment method and device for waste lithium battery electrolyte wastewater that is simple to operate, can recycle the stable electrolyte from the wastewater, reduce the COD in the wastewater, and reduce the treatment cost at the same time.

[0006] A recycling method based on waste lithium-ion battery electrolyte wastewater, comprising the following steps:

[0007] Perform a pressure filtration operation on the waste lithium-ion battery electrolyte wastewater to obtain an electrolyte filtrate;

[0008] Mix the electrolyte filtrate with a soluble salt and then perform a salting-out separation operation to obtain a crude liquid separation and a first high-salt water;

[0009] Perform a fine liquid separation operation on the crude liquid separation to obtain a first electrolyte solvent and a second high-salt water;

[0010] Mix the first high-salt water and the second high-salt water and then perform an air flotation oil removal operation to obtain a second electrolyte solvent and a third high-salt water;

[0011] Perform a freeze crystallization operation on the third high-salt water to obtain lithium-rich water containing salting-out salt crystals;

[0012] Perform a solid-liquid separation operation on the lithium-rich water containing salting-out salt crystals to obtain salting-out salt crystals and lithium-rich water, and recycle the salting-out salt crystals;

[0013] Mix the lithium-rich water and a carbonate and then perform a precipitation separation operation to obtain crude lithium carbonate and filtered clear water, and recycle the filtered clear water.

[0014] In one embodiment, the step of performing a pressure filtration operation on the waste lithium-ion battery electrolyte wastewater to obtain an electrolyte filtrate is specifically:

[0015] Perform a pressure filtration operation on the high-concentration electrolyte through a first pressure filter to obtain the electrolyte filtrate.

[0016] In one embodiment, the specific operation steps of mixing the electrolyte filtrate with a soluble salt and then performing a salting-out separation operation to obtain a crude liquid separation and a first high-salt water are:

[0017] Add the electrolyte filtrate and the soluble salt to a salting-out stirring tank for salting-out stratification operation to obtain the crude liquid separation and the first high-salt water.

[0018] In one embodiment, the specific operation steps of performing a fine liquid separation operation on the crude liquid separation to obtain an electrolyte solvent and a second high-salt water are:

[0019] Transport the crude liquid separation to an oil-water separator for oil-water separation operation to obtain the first electrolyte solvent and the second high-salt water, and perform a recovery operation on the first electrolyte solvent.

[0020] In one embodiment, the specific operating steps for mixing the first high-salt water and the second high-salt water and then performing air flotation for oil removal to obtain a second electrolyte solvent and a third high-salt water are as follows:

[0021] Mix the first high-salt water and the second high-salt water and then transport them to an air flotation reaction tank for air flotation for oil removal to obtain the second electrolyte solvent and the third high-salt water, and perform a recovery operation on the second electrolyte solvent.

[0022] In one embodiment, the specific operating steps for performing freeze crystallization on the third high-salt water to obtain lithium-rich water containing salt precipitation crystals are as follows:

[0023] Perform freeze crystallization on the third high-salt water through a freeze crystallizer to obtain the lithium-rich water containing salt precipitation crystals.

[0024] In one embodiment, the steps for performing solid-liquid separation on the lithium-rich water containing salt precipitation crystals to obtain salt precipitation crystals and lithium-rich water, and recycling the salt precipitation crystals are specifically as follows:

[0025] Perform solid-liquid separation on the lithium-rich water containing salt precipitation crystals through a solid-liquid separator to obtain the salt precipitation crystals and the lithium-rich water, and transport the salt precipitation crystals to a salt precipitation stirring tank for recycling.

[0026] In one embodiment, the steps for mixing the lithium-rich water and a carbonate and then performing precipitation separation to obtain crude lithium carbonate and filtered clear water, and recycling the filtered clear water are specifically as follows:

[0027] Transport the lithium-rich water to a precipitation reaction tank, and add a carbonate to the precipitation reaction tank for a mixed precipitation reaction to obtain a mixed slurry;

[0028] Transport the mixed slurry to a second filter press for filter pressing to obtain the crude lithium carbonate and the filtered clear water, and transport the filtered clear water to the waste lithium battery recycling production line equipment for recycling.

[0029] In one embodiment, the temperature of the freeze crystallization is 0°C - 5°C.

[0030] A recovery device for waste lithium battery electrolyte wastewater uses the recovery method for electrolyte of any of the above embodiments to recover the electrolyte, and circularly uses the filtered clear water after the recovery treatment;

[0031] The recycling device includes a first filter press, a salting-out component, a fine separation component, a flotation separation component, an electrolyte storage tank, a crystallization component, a solid-liquid separation component, and a precipitation separation component. The feed end of the first filter press is used to externally connect to the equipment of a waste lithium battery recycling production line, and the liquid outlet end of the first filter press is communicated with the salting-out component; the salting-out component is communicated with the fine separation component, the electrolyte storage tank is respectively communicated with the fine separation component and the flotation separation component, the crystallization component is respectively communicated with the flotation separation component and the solid-liquid separation component, the solid-liquid separation component is communicated with the salting-out component, and the precipitation separation component is respectively communicated with the solid-liquid separation component and the equipment of the waste lithium battery recycling production line.

[0032] In one embodiment, the salting-out component is provided with a salting-out stirring tank, and the salting-out stirring tank is provided with a first liquid inlet, a first aqueous phase liquid outlet, and a plurality of first organic phase liquid outlets. The first liquid inlet is communicated with the liquid outlet end of the first filter press.

[0033] In one embodiment, the fine separation component is provided with an oil-water separator, and the oil-water separator is provided with a second liquid inlet, a second aqueous phase liquid outlet, and a second organic phase liquid outlet. The second liquid inlet is communicated with a plurality of the first organic phase liquid outlets so that the oil-water separator is communicated with the salting-out stirring tank, and the second organic phase liquid outlet is communicated with the liquid inlet end of the electrolyte storage tank.

[0034] In one embodiment, the flotation separation component is provided with a flotation reaction tank, and the flotation reaction tank is provided with a third liquid inlet, a third aqueous phase liquid outlet, and a third organic phase liquid outlet. The first aqueous phase liquid outlet and the second aqueous phase liquid outlet are both communicated with the third liquid inlet so that the flotation reaction tank is respectively communicated with the salting-out stirring tank and the oil-water separator, and the third organic phase liquid outlet is communicated with the liquid inlet end of the electrolyte storage tank.

[0035] In one embodiment, the crystallization component is provided with a freeze crystallizer, and the feed end of the freeze crystallizer is communicated with the third aqueous phase liquid outlet.

[0036] In one embodiment, the solid-liquid separation component is provided with a solid-liquid separator. The liquid inlet end of the solid-liquid separator is communicated with the discharge end of the freeze crystallizer, and the solid discharge end of the solid-liquid separator is communicated with the salting-out stirring tank.

[0037] In one embodiment, the precipitation separation assembly includes a first liquid storage tank, a precipitation reaction tank, a second filter press and a second liquid storage tank. The liquid inlet end of the first liquid storage tank is connected to the liquid outlet end of the solid-liquid separator. The liquid outlet end of the first liquid storage tank is respectively connected to the feed end of the precipitation reaction tank and the equipment of the waste lithium battery recycling production line. The discharge end of the precipitation reaction tank is connected to the feed end of the second filter press. The liquid discharge end of the second filter press is connected to the liquid inlet end of the second liquid storage tank. The liquid outlet end of the second liquid storage tank is connected to the equipment of the waste lithium battery recycling production line.

[0038] Compared with the prior art, the present application has at least the following advantages:

[0039] 1. In the recovery method of waste lithium battery electrolyte wastewater of the present application, first, the electrolyte wastewater is subjected to a pressure filtration operation to remove the solid impurities in the wastewater and obtain an electrolyte filtrate. Then, the electrolyte filtrate is mixed with a soluble salt for salting-out separation operation to obtain a crude liquid separation and a first high-salt water, that is, the density of the aqueous phase is increased by the soluble salt, so that the organic phase and the aqueous phase of the electrolyte can be separated. Secondly, the crude liquid separation is subjected to a fine liquid separation operation to obtain a first electrolyte solvent and a second high-salt water, so that the electrolyte solvent insoluble in water can be recovered. Immediately afterwards, the first high-salt water and the second high-salt water are mixed for air flotation oil removal operation. Through air flotation treatment, the electrolyte solvent soluble in water is separated from the water to obtain a second electrolyte solvent and a third high-salt water. At the same time, the oxygen in the air can oxidize some organic substances, which can not only effectively reduce the COD in the water, but also separate the electrolyte solvent soluble in water, so that the stable electrolyte solvent can be separated and recovered from the wastewater of the waste lithium battery recycling production line. Finally, the third high-salt water is subjected to a freezing crystallization operation, that is, a lithium-rich water containing salting-out salt crystals is formed, and then the lithium-rich water containing salting-out salt crystals is subjected to a solid-liquid separation operation to obtain salting-out salt crystals and lithium-rich water, and the salting-out salt crystals are recovered and reused as soluble salts, so that the treatment cost of the wastewater can be effectively reduced.

[0040] 2. In the recovery method of waste lithium battery electrolyte wastewater of the present application, only by separating the electrolyte solvent through salting-out separation operation, fine liquid separation operation and air flotation oil removal operation, the COD of the wastewater can be effectively reduced, and the recovery treatment process of waste lithium battery electrolyte wastewater can be greatly simplified. At the same time, after mixing the lithium-rich water and carbonate and performing a precipitation separation operation to obtain crude lithium carbonate and filtered clear water, not only can the electrolyte lithium salt be effectively recovered, but also the filtered clear water can be recycled to the equipment of the waste lithium battery recycling production line for recycling, so that zero discharge of waste lithium battery electrolyte wastewater can be realized, and then the recycling of water resources can be realized, and the wastewater treatment cost can be further reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] To more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the following will briefly introduce the accompanying drawings required for the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other accompanying drawings can also be obtained based on these drawings.

[0042] Figure 1 It is a flowchart of a recycling method for waste lithium battery electrolyte wastewater according to an embodiment of the present application;

[0043] Figure 2 It is a schematic flow diagram of a recycling method for waste lithium battery electrolyte wastewater according to an embodiment of the present application;

[0044] Figure 3 It is a schematic structural diagram of a recycling device for waste lithium battery electrolyte wastewater according to an embodiment of the present application;

[0045] Figure 4 For Figure 3 It is a schematic diagram of a partial structure of the recycling device for waste lithium battery electrolyte wastewater shown;

[0046] Figure 5 For Figure 3 It is a schematic diagram of a partial structure of the recycling device for waste lithium battery electrolyte wastewater shown;

[0047] Reference numerals: recycling device 10; first filter press 100; salting-out component 200; salting-out stirring tank 210; first liquid inlet 2102; first aqueous phase outlet 2104; first organic phase outlet 2106; fine separation component 300; oil-water separator 310; second liquid inlet 3102; second aqueous phase outlet 3104; second organic phase outlet 3106; air flotation separation component 400, air flotation reaction tank 410; third liquid inlet 4102; third aqueous phase outlet 4104; third organic phase outlet 4106; electrolyte storage tank 500; crystallization component 600; freeze crystallizer 610; solid-liquid separation component 700; solid-liquid separator 710; precipitation separation component 800; first liquid storage tank 810; precipitation reaction tank 820; second filter press 830; second liquid storage tank 840; waste lithium battery recycling production line equipment 900; wastewater storage tank 1000. Detailed implementation manners

[0048] To facilitate the understanding of this application, the following will provide a more comprehensive description of this application with reference to the relevant drawings. The preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough and comprehensive understanding of the disclosure of this application.

[0049] It should be noted that when an element is referred to as being "fixed to" another element, it can be directly on the other element or there can also be an intermediate element. When an element is considered to be "connected" to another element, it can be directly connected to the other element or there may be an intermediate element at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are only for illustrative purposes and do not represent the only embodiments.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the technical field to which this application belongs. The terms used in the specification of this application herein are only for the purpose of describing specific embodiments and are not intended to limit this application. The term "and / or" used herein includes any and all combinations of one or more of the related listed items.

[0051] Please refer to Figure 1 and Figure 2 , a recovery method for waste lithium battery electrolyte wastewater of an embodiment, includes some or all of the following steps:

[0052] S100, perform a pressure filtration operation on the waste lithium battery electrolyte wastewater to obtain an electrolyte filtrate.

[0053] In this embodiment, since the wastewater from the waste lithium battery recycling production line contains solid impurities, it is necessary to remove the solid impurities by pressure filtration to obtain the electrolyte filtrate to be recycled, so as to avoid the influence of solid impurities on the recovery of the electrolyte.

[0054] S200, mix the electrolyte filtrate with a soluble salt and then perform a salting-out separation operation to obtain a crude liquid separation and a first high-salt water.

[0055] In this embodiment, since some carbonates in the electrolyte solvent are insoluble in water, but their density is close to that of water and they can be dispersed in water but do not form layers. Therefore, by adding a soluble salt, the density of the aqueous phase is increased, so that the crude liquid separation and the first high-salt water are layered, so that the organic phase containing the electrolyte solvent component and the aqueous phase can be layered, thereby realizing the separation of the organic phase and the aqueous phase.

[0056] S300, perform a fine liquid separation operation on the crude liquid separation to obtain a first electrolyte solvent and a second high-salt water.

[0057] In this embodiment, since the water content in the crude separated liquid is relatively high, the crude separated liquid is subjected to fine separation operation to obtain a first electrolyte solvent and a second high-salt water, so as to reduce the water content of the recovered electrolyte solvent and ensure the purity of the recovered electrolyte solvent.

[0058] S400, mix the first high-salt water and the second high-salt water and then perform air flotation oil removal operation to obtain a second electrolyte solvent and a third high-salt water.

[0059] In this embodiment, air flotation treatment is performed on the lithium-rich high-salt wastewater by using air, which can promote the separation of the water-soluble electrolyte solvent from water to obtain a second electrolyte solvent and a third high-salt water. In this way, the water-soluble electrolyte solvent can be recovered, and at the same time, the oxygen in the air can oxidize some organic substances, thereby effectively reducing the COD in the wastewater. Further, the lithium-rich high-salt water can be further recovered through subsequent processes, so that both the electrolyte lithium salt and the electrolyte solvent can be effectively recovered. In this way, a stable electrolyte can be separated and recovered from the wastewater of the waste lithium battery recycling production line.

[0060] S500, perform freeze crystallization operation on the third high-salt water to obtain lithium-rich water containing salting-out salt crystals.

[0061] In this embodiment, by performing freeze crystallization operation on the third high-salt water to obtain lithium-rich water containing salting-out salt crystals, the soluble salt is precipitated at low temperature to form crystals, that is, salting-out salt crystals, and the salting-out salt crystals can be recycled, so as to reduce the treatment cost of the wastewater.

[0062] S600, perform solid-liquid separation operation on the lithium-rich water containing salting-out salt crystals to obtain salting-out salt crystals and lithium-rich water, and recycle the salting-out salt crystals.

[0063] In this embodiment, the lithium-rich water containing salting-out salt crystals is subjected to solid-liquid separation operation to obtain salting-out salt crystals and lithium-rich water. The salting-out salt crystals are recycled as soluble salts, so that the materials are recycled, and further, the treatment cost of the wastewater can be effectively reduced.

[0064] S700, mix the lithium-rich water and carbonate and then perform precipitation separation operation to obtain crude lithium carbonate and filtered clear water, and recycle the filtered clear water.

[0065] In this embodiment, precipitation separation is carried out by mixing carbonate with lithium-rich water to obtain crude lithium carbonate and filtered clear water. In this way, the electrolyte lithium salt can be recovered, and at the same time, the filtered clear water is sent back to the waste lithium battery recycling treatment equipment for recycling, so as to achieve zero discharge of wastewater, and further achieve the recycling of water resources, and further reduce the treatment cost of wastewater.

[0066] The above-mentioned recycling method for waste lithium-ion battery electrolyte wastewater first performs a pressure filtration operation on the electrolyte wastewater to remove solid impurities from the wastewater and obtain an electrolyte filtrate. Then, the electrolyte filtrate is mixed with a soluble salt for a salting-out separation operation to obtain a crude liquid separation and a first high-salt water, that is, the density of the aqueous phase is increased by the soluble salt, so that the organic phase and the aqueous phase of the electrolyte can be separated. Secondly, the crude liquid separation is subjected to a fine liquid separation operation to obtain a first electrolyte solvent and a second high-salt water, so that the electrolyte solvent insoluble in water can be recovered. Immediately afterwards, the first high-salt water and the second high-salt water are mixed for an air flotation oil removal operation, and the electrolyte solvent soluble in water is separated from the water through air flotation treatment to obtain a second electrolyte solvent and a third high-salt water. At the same time, the oxygen in the air can oxidize some organic substances. In this way, not only can the COD in the water be effectively reduced, but also the electrolyte solvent soluble in water can be separated, and the stable electrolyte solvent can be separated and recovered from the wastewater of the waste lithium-ion battery recycling production line. Finally, through a freezing crystallization operation on the third high-salt water, that is, a lithium-rich water containing salting-out salt crystals is formed, and then a solid-liquid separation operation is performed on the lithium-rich water containing salting-out salt crystals to obtain salting-out salt crystals and lithium-rich water, and the salting-out salt crystals are recycled and reused as soluble salts, so that the treatment cost of the wastewater can be effectively reduced.

[0067] Furthermore, by simply separating the electrolyte solvent through salting-out separation operation, fine liquid separation operation and air flotation oil removal operation, the COD of the wastewater can be effectively reduced, and the recycling treatment process of waste lithium-ion battery electrolyte wastewater can be greatly simplified. At the same time, after mixing the lithium-rich water and carbonate and performing a precipitation separation operation to obtain crude lithium carbonate and filtered clear water, not only can the electrolyte lithium salt be effectively recovered, but also the filtered clear water can be recycled to the equipment of the waste lithium-ion battery recycling production line for recycling, so that zero discharge of waste lithium-ion battery electrolyte wastewater can be achieved, and then the recycling of water resources can be realized, and the wastewater treatment cost can be further reduced.

[0068] In one embodiment, the step of performing a pressure filtration operation on the waste lithium-ion battery electrolyte wastewater to obtain an electrolyte filtrate is specifically as follows: the high-concentration electrolyte is subjected to a pressure filtration operation through a first pressure filter to obtain the electrolyte filtrate. It should be noted that the solid impurities in the high-concentration electrolyte are removed through the first pressure filter to facilitate the subsequent recovery of the electrolyte.

[0069] In one embodiment, the specific operating steps for salting-out separation by mixing the electrolyte filtrate with a soluble salt are as follows: adding the electrolyte filtrate and the soluble salt into a salting-out stirring tank for salting-out stratification operation to obtain the crude liquid separation and the first high-salt water. It should be noted that since some carbonates in the electrolyte are insoluble in water, but their density is close to that of water, they can be dispersed in water but do not form layers. In view of this characteristic, in this embodiment, a soluble salt is added to increase the density of water, so that an upper and lower layer separation of the organic phase and the water phase can be formed, thereby separating the organic components dispersed in water in the electrolyte, and then effectively recovering the electrolyte.

[0070] In one embodiment, the specific operating steps for fine liquid separation of the crude liquid separation are as follows: transporting the crude liquid separation to an oil-water separator for oil-water separation operation to obtain the first electrolyte solvent and the second high-salt water, and performing a recovery operation on the first electrolyte solvent. It can be understood that by performing an oil-water separation operation on the crude liquid separation through an oil-water separator, that is, further separating the crude liquid separation, the electrolyte organic components in the crude liquid separation can be separated from the water phase, thereby effectively recovering the electrolyte solvent.

[0071] In one embodiment, the specific operating steps for air flotation oil removal by mixing the first high-salt water and the second high-salt water to obtain the second electrolyte solvent and the third high-salt water are as follows: mixing the first high-salt water and the second high-salt water and transporting them to an air flotation reaction tank for air flotation oil removal operation to obtain the second electrolyte solvent and the third high-salt water, and performing a recovery operation on the second electrolyte solvent. It can be understood that since the first high-salt water and the second high-salt water are mixed with some electrolyte solvents soluble in water, it is necessary to perform an air flotation oil removal operation on the first high-salt water and the second high-salt water. The air flotation treatment is carried out on the lithium-rich high-salt wastewater. On the one hand, it can promote the separation of the electrolyte solvent soluble in water from water, and on the other hand, it can oxidize the organic matter, so that the COD in the wastewater can be effectively reduced, and at the same time, the electrolyte solvent soluble in water can be recovered.

[0072] In one embodiment, the specific operating steps for freeze crystallization of the third high-salt water to obtain lithium-rich water containing salting-out salt crystals are as follows: performing freeze crystallization operation on the third high-salt water through a freeze crystallizer to obtain the lithium-rich water containing salting-out salt crystals. It can be understood that by performing a freeze crystallization operation on the third high-salt water through a freeze crystallizer, the lithium-rich high-salt wastewater crystallizes salting-out salt crystals under low-temperature conditions, so that lithium-rich water containing salting-out salt crystals can be obtained.

[0073] In one embodiment, the steps of performing solid-liquid separation on the lithium-rich water containing salting-out crystals to obtain salting-out crystals and lithium-rich water, and recycling the salting-out crystals are specifically as follows: performing solid-liquid separation on the lithium-rich water containing salting-out crystals through a solid-liquid separator to obtain the salting-out crystals and the lithium-rich water, and transporting the salting-out crystals to the salting-out stirring tank for recycling. It can be understood that the salting-out crystals separated by the solid-liquid separator can be recycled as soluble salts back to the salting-out stirring tank, so as to realize the recycling of resources and effectively reduce the wastewater treatment cost.

[0074] In one embodiment, the steps of mixing the lithium-rich water and carbonate and then performing precipitation separation to obtain crude lithium carbonate and filtered clear water, and recycling the filtered clear water are specifically as follows: First, transporting the lithium-rich water to a precipitation reaction tank, and adding carbonate into the precipitation reaction tank for mixing and precipitation reaction to obtain a mixed slurry. Then, transporting the mixed slurry to a second filter press for filtration to obtain the crude lithium carbonate and the filtered clear water, and transporting the filtered clear water to the waste lithium battery recycling production line equipment for recycling. It can be understood that lithium reacts with the carbonate to form lithium carbonate precipitation after mixing with the lithium-rich water. By stirring the lithium-rich water and carbonate in the precipitation reaction tank to form a mixed slurry, that is, a mixed slurry containing lithium carbonate precipitation. Then, performing filtration on the mixed slurry through the second filter press, so as to obtain crude lithium carbonate and realize the recovery of electrolyte lithium salt. The filtered clear water is recycled back to the waste lithium battery production line recycling equipment for recycling, so as to realize zero discharge of wastewater, and further realize the recycling of water resources and reduce the wastewater treatment cost.

[0075] In one embodiment, the temperature of the freeze crystallization is 0°C - 5°C. It can be understood that at 0°C - 5°C, the solution saturation of the high-salt water is relatively low, and soluble salts can be precipitated, so as to realize the recycling of soluble salts and effectively reduce the wastewater treatment cost.

[0076] Further, in one embodiment, the soluble salt is sodium sulfate. It can be understood that the density of water is increased by the soluble salt, so that the layering of the organic phase and the water phase can be achieved, and then the organic phase and the water phase can be effectively separated. At the same time, due to the wide source and low cost of sodium sulfate, the cost of wastewater treatment can be effectively reduced. Further, in one embodiment, the salting-out temperature is 20°C - 35°C. It can be understood that the solubility of the soluble salt in this temperature range is relatively high, and it can be mixed with water to form a saturated high-salt water, and at the same time, it can avoid the volatilization of the electrolyte at high temperature, so that the organic phase and the water phase can be separated to a large extent. Further, in one embodiment, the addition amount of the soluble salt is 20wt% - 35wt%. Under the conditions of 20°C - 35°C, 20wt% - 35wt% of sodium sulfate can compete with the electrolyte for solubility in water to the greatest extent, while increasing the density of the water body to separate the electrolyte from the water. Further, in one embodiment, the oil-water ratio of the rough liquid separation is ********. It can be understood that the oil-water ratio separated by the above salting-out temperature and the addition amount of the soluble salt is ********, and the organic components of the electrolyte solvent can be separated to a large extent, so as to facilitate further separation in the follow-up. Further, in one embodiment, the water content of the first electrolyte solvent is less than 5%. It can be understood that the water content of the first electrolyte solvent obtained by further separating the rough liquid separated by the above salting-out temperature and the addition amount of the soluble salt is less than 5%, so that the purity of the recycled electrolyte can meet the resource recovery standard, so that the recycling steps can be effectively simplified, and the treatment cost during the recycling of the electrolyte solvent can be reduced.

[0077] Please refer to Figure 3 , the present application also provides a recycling device 10 for waste lithium battery electrolyte wastewater, and the electrolyte is recycled by using the recycling method for waste lithium battery electrolyte wastewater described in any one of the above embodiments.

[0078] It should be noted that there is an unclear "********" in the original text for the "oil-water ratio" part, which is retained as it is in the translation. If you can provide the correct value, I can further improve the translation.In one of the embodiments, the recycling device 10 includes a first filter press 100, a salting-out component 200, a fine separation component 300, a flotation separation component 400, an electrolyte storage tank 500, a crystallization component 600, a solid-liquid separation component 700, and a precipitation separation component 800. The feed end of the first filter press 100 is used to externally connect to the waste lithium battery recycling production line equipment 900, and the liquid outlet end of the first filter press 100 is communicated with the salting-out component 200; the salting-out component 200 is communicated with the fine separation component 300, the electrolyte storage tank 500 is respectively communicated with the fine separation component 300 and the flotation separation component 400, the crystallization component 600 is respectively communicated with the flotation separation component 400 and the solid-liquid separation component 700, the solid-liquid separation component 700 is communicated with the salting-out component 200, and the precipitation separation component 800 is respectively communicated with the solid-liquid separation component 700 and the waste lithium battery recycling production line equipment 900.

[0079] In this embodiment, the electrolyte wastewater of the waste lithium battery recycling production line equipment 900 is filtered by the first filter press 100 to obtain electrolyte filtrate. The electrolyte filtrate and soluble salt are mixed by the salting-out component 200 to form a layer, so that a crude liquid separation and a first high-salt water can be obtained. The crude liquid separation is subjected to a fine liquid separation operation by the fine separation component 300 to obtain a first electrolyte solvent and a second high-salt water. The first electrolyte solvent is recycled through the electrolyte storage tank 500. Then, the first high-salt water and the second high-salt water are mixed and subjected to an oil removal operation by the flotation separation component 400 to obtain a second electrolyte solvent and a third high-salt water. The second electrolyte solvent is recycled through the electrolyte storage tank 500, so that a stable electrolyte solvent can be separated and recycled from the wastewater of the waste lithium battery recycling production line. The third high-salt water is subjected to a freezing crystallization operation by the crystallization component 600 to obtain lithium-rich water containing salting-out salt crystals. Then, the lithium-rich water containing salting-out salt crystals is subjected to a solid-liquid operation by the solid-liquid separation component 700 to obtain salting-out salt crystals and lithium-rich water. The salting-out salt crystals are transported to the salting-out component 200 as soluble salts for recycling and reuse, so that the treatment cost of wastewater can be effectively reduced. The lithium-rich water is transported to the precipitation separation component 800 and mixed with carbonate for precipitation separation operation to obtain crude lithium carbonate and filtered clear water, so that the electrolyte lithium salt in the wastewater can be recovered. The filtered clear water is transported to the waste lithium battery recycling production line equipment 900 for recycling and reuse, realizing zero discharge of wastewater treatment, enabling the recycling of water resources, and further reducing the wastewater treatment cost.

[0080] Such as Figure 3 and Figure 5As shown, in one embodiment, the salting-out component 200 is provided with a salting-out stirring tank 210. The salting-out stirring tank 210 is provided with a first liquid inlet 2102, a first aqueous phase liquid outlet 2104, and a plurality of first organic phase liquid outlets 2106. The first liquid inlet 2102 is communicated with the liquid outlet end of the first filter press 100. It can be understood that the electrolyte filtrate enters the salting-out stirring tank 210 through the first liquid inlet 2102, is mixed with the soluble salt, and then performs a salting-out separation operation. After salting-out separation, a crude liquid separation and a first high-salt water are obtained. Further, in one embodiment, a salting-out salt automatic stirring and dosing device is provided in the salting-out stirring tank 210. In this way, the accuracy of adding salt can be ensured, and at the same time, automated production can be achieved, thereby effectively improving the wastewater treatment efficiency.

[0081] As Figure 3 and Figure 5 As shown, in one embodiment, the fine separation component 300 is provided with an oil-water separator 310. The oil-water separator 310 is provided with a second liquid inlet 3102, a second aqueous phase liquid outlet 3104, and a second organic phase liquid outlet 3106. The second liquid inlet 3102 is communicated with a plurality of the first organic phase liquid outlets 2106, so that the oil-water separator 310 is communicated with the salting-out stirring tank 210. The second organic phase liquid outlet 3106 is communicated with the liquid inlet end of the electrolyte storage tank 500. It should be noted that the crude liquid separation after salting-out stratification is transported to the second liquid inlet 3102 through a plurality of first organic phase liquid outlets 2106 for fine liquid separation operation, while the first high-salt water is transported to the third liquid inlet 3202 through the first aqueous phase liquid outlet 2104 for air flotation operation. The oil-water separator 310 further separates the oil and water in the crude liquid separation. The separated first electrolyte solvent is transported to the electrolyte storage tank 500 through the second organic phase liquid outlet 3106 for recovery. In this way, the electrolyte solvent insoluble in water can be recovered.

[0082] As Figure 3 and Figure 5 As shown, in one embodiment, the air flotation separation component 400 is provided with an air flotation reaction tank 410. The air flotation reaction tank 410 is provided with a third liquid inlet 4102, a third aqueous phase liquid outlet 4104, and a third organic phase liquid outlet 4106. The first aqueous phase liquid outlet 2104 and the second aqueous phase liquid outlet 3104 are both communicated with the third liquid inlet 4102, so that the air flotation reaction tank 410 is respectively communicated with the salting-out stirring tank 210 and the oil-water separator 310. The third organic phase liquid outlet 4106 is communicated with the liquid inlet end of the electrolyte storage tank 500.

[0083] It should be noted that the soluble electrolyte solvents in the first high-salt water and the second high-salt water are separated through the air flotation reaction tank 410, and the obtained second electrolyte solvent is transported to the electrolyte storage tank 500 through the third organic phase liquid outlet 4106 for recovery. In this way, the water-soluble organic components in the electrolyte solvent can be effectively recovered, thereby effectively recovering the electrolyte solvent and effectively reducing the COD in the wastewater.

[0084] Furthermore, in one embodiment, the air flotation reaction tank 410 is provided with a surfactant automatic dosing device. By using the surfactant to defoam the bubbles generated during the air flotation process, the stratification separation of the electrolyte solvent and water can be effectively promoted. Further, in one embodiment, the surfactant is at least one of phosphate esters or silicone-based compounds. By providing the surfactant, the bubbles generated during the air flotation process can be defoamed, thereby effectively promoting the stratification effect of the electrolyte solvent and water.

[0085] Furthermore, in one embodiment, the number of the first organic phase liquid outlets 2106 is five, and the five first organic phase liquid outlets 2106 are sequentially distributed from top to bottom in the salting-out stirring tank 210. By providing five first organic phase liquid outlets 2106, different first organic phase liquid outlets 2106 can be selected according to different liquid level conditions to transfer the rough liquid separation to the oil-water separator 310. In this way, the separation completeness of the electrolyte can be ensured, thereby effectively improving the recovery rate of the electrolyte and effectively reducing the COD of the wastewater. Further, in one embodiment, the salting-out assembly 200 is provided with five liquid level gauges, and each liquid level gauge is arranged on the pipeline where the corresponding first organic phase liquid outlet 2106 is communicated with the corresponding second liquid inlet 3102. Through the liquid level gauge, the liquid level condition of the salting-out stirring tank 210 can be monitored in real time, so that the corresponding first organic phase outlet can be selected according to the liquid level condition to ensure the transfer completeness of the rough liquid separation, thereby effectively improving the recovery rate of the electrolyte solvent.

[0086] As Figure 5 shown, in one embodiment, the crystallization assembly 600 is provided with a freeze crystallizer 610, and the feed end of the freeze crystallizer 610 is communicated with the third aqueous phase liquid outlet 3204. It should be noted that the third high-salt water after air flotation treatment is transported to the freeze crystallizer 610 through the third aqueous phase liquid outlet 3204 for freeze crystallization operation to form lithium-rich water containing salting-out salt crystals. Further, in one embodiment, the freeze crystallizer 610 is an OLSO crystallizer or a DTB crystallizer.

[0087] As Figure 5As shown, in one embodiment, the solid-liquid separation assembly 700 is provided with a solid-liquid separator 710. The liquid inlet end of the solid-liquid separator 710 is communicated with the discharge end of the freezing crystallizer 610, and the solid discharge end of the solid-liquid separator 710 is communicated with the salting-out stirring tank 210. It can be understood that the lithium-rich water containing salting-out salt crystals is transported from the freezing crystallizer 610 to the solid-liquid separator 710 for solid-liquid separation operation, so that the salting-out salt crystals and the lithium-rich water can be separated. The salting-out salt crystals can be recycled as soluble salts, thereby effectively reducing the treatment cost of wastewater. Further, in one embodiment, the solid-liquid separator 710 is one of a centrifuge or a filter press.

[0088] As Figures 3 to 5 shown, in one embodiment, the precipitation separation assembly 800 includes a first liquid storage tank 810, a precipitation reaction tank 820, a second filter press 830 and a second liquid storage tank 840. The liquid inlet end of the first liquid storage tank 810 is connected to the liquid discharge end of the solid-liquid separator 710. The liquid outlet end of the first liquid storage tank 810 is respectively communicated with the feed end of the precipitation reaction tank 820 and the waste lithium battery recycling production line equipment 900. The discharge end of the precipitation reaction tank 820 is communicated with the feed end of the second filter press 830. The liquid discharge end of the second filter press 830 is communicated with the liquid inlet end of the second liquid storage tank 840. The liquid outlet end of the second liquid storage tank 840 is communicated with the waste lithium battery recycling production line equipment 900. It should be noted that the salting-out salt crystals are sent back to the salting-out stirring tank 210 for recycling, realizing the recycling of materials, while the lithium-rich water is transported to the first liquid storage tank 810. When the lithium content < 15 g / L, the wastewater is directly sent back to the waste lithium battery recycling production line equipment 900 to be combined with the electrolyte wastewater for electrolyte recovery treatment. When the lithium content > 15 g / L, the wastewater is transported from the first liquid storage tank 810 to the precipitation reaction tank 820 to react with carbonate to form a mixed slurry containing lithium carbonate precipitate, and then the mixed slurry is transported to the second filter press 830 for filtration operation to obtain crude lithium carbonate and filtered clear water. At the same time, the lithium content of the filtered clear water after the filtration operation < 1 g / L, and the filtered clear water is introduced into the second liquid storage tank 840 for storage, and then the filtered clear water is transported to the water inlet of the waste lithium battery recycling production line equipment 900 through the second liquid storage tank 840, so that the water resources are recycled, and at the same time, zero discharge of wastewater treatment is realized, thereby effectively reducing the cost of waste lithium battery recycling treatment. Further, in one embodiment, a lithium content detector is provided on the first liquid storage tank 810. The lithium content in the first liquid storage tank 810 can be monitored in real time through the lithium content detector, so that different discharge routes can be selected according to the content, which can effectively simplify the wastewater treatment process and thus effectively improve the wastewater recovery treatment efficiency.

[0089] As Figure 4As shown, in one embodiment, the recycling device 10 further includes a waste water storage tank 1000. The liquid inlet end of the waste water storage tank 1000 is connected to the waste lithium battery recycling production line equipment 900, and the liquid outlet end of the waste water tank is connected to the feeding end of the first filter press 100. It can be understood that since the amount of waste water in the waste lithium battery recycling production line equipment 900 is relatively large, it is necessary to store and distribute it through the waste water storage tank 1000 to adapt to the waste water treatment capacity of the treatment device.

[0090] The following are examples, but it should be noted that the following examples do not exhaust all possible situations, and the materials used in the following examples can be obtained from commercial channels without special instructions.

[0091] Example 1

[0092] Press-filter the waste lithium battery electrolyte waste water, take the electrolyte filtrate into the salting-out stirring tank, add soluble salt for mixing, the addition amount of the soluble salt is 20 wt%, the salting-out temperature is 20 °C, to obtain a crude liquid separation and a first high-salt water. Perform an oil-water separation operation on the crude liquid separation to obtain a first electrolyte solvent and a second high-salt water. Transport the first high-salt water and the second high-salt water to a flotation reaction tank for flotation treatment to obtain a second electrolyte solvent and a third high-salt water. Transport the first electrolyte solvent and the second electrolyte solvent to an electrolyte storage tank for recovery. Perform a freeze crystallization operation on the third high-salt water, the freeze crystallization temperature is 0 °C, to obtain lithium-rich water containing salting-out salt crystals. Perform a solid-liquid separation operation on the lithium-rich water containing salting-out salt crystals to obtain salting-out salt crystals and lithium-rich water. Recycle and reuse the salting-out salt crystals. Perform a precipitation separation operation on the lithium-rich water and carbonate to obtain crude lithium carbonate and filtered clear water.

[0093] Example 2

[0094] Press-filter the waste lithium battery electrolyte waste water, take the electrolyte filtrate into the salting-out stirring tank, add soluble salt for mixing, the addition amount of the soluble salt is 30 wt%, the salting-out temperature is 30 °C, to obtain a crude liquid separation and a first high-salt water. Perform an oil-water separation operation on the crude liquid separation to obtain a first electrolyte solvent and a second high-salt water. Transport the first high-salt water and the second high-salt water to a flotation reaction tank for flotation treatment to obtain a second electrolyte solvent and a third high-salt water. Transport the first electrolyte solvent and the second electrolyte solvent to an electrolyte storage tank for recovery. Perform a freeze crystallization operation on the third high-salt water, the freeze crystallization temperature is 3 °C, to obtain lithium-rich water containing salting-out salt crystals. Perform a solid-liquid separation operation on the lithium-rich water containing salting-out salt crystals to obtain salting-out salt crystals and lithium-rich water. Recycle and reuse the salting-out salt crystals. Perform a precipitation separation operation on the lithium-rich water and carbonate to obtain crude lithium carbonate and filtered clear water.

[0095] Example 3

[0096] Filter press the waste lithium battery electrolyte wastewater, take the electrolyte filtrate into the salting-out stirring tank, add soluble salts and mix them. The addition amount of the soluble salts is 35 wt%, and the salting-out temperature is 35 °C to obtain a crude liquid separation and a first high-salt water. Perform an oil-water separation operation on the crude liquid separation to obtain a first electrolyte solvent and a second high-salt water. Transport the first high-salt water and the second high-salt water to a flotation reaction tank for flotation treatment to obtain a second electrolyte solvent and a third high-salt water. Transport the first electrolyte solvent and the second electrolyte solvent to an electrolyte storage tank for recovery. Perform a freeze crystallization operation on the third high-salt water, and the freeze crystallization temperature is 5 °C to obtain lithium-rich water containing salting-out salt crystals. Perform a solid-liquid separation operation on the lithium-rich water containing salting-out salt crystals to obtain salting-out salt crystals and lithium-rich water. Recycle and reuse the salting-out salt crystals. Perform a precipitation separation operation on the lithium-rich water and carbonate to obtain crude lithium carbonate and filtered clear water.

[0097] Comparative Example 1

[0098] Filter press the waste lithium battery electrolyte wastewater, take the electrolyte filtrate into the salting-out stirring tank, add soluble salts and mix them. The addition amount of the soluble salts is 10 wt%, and the salting-out temperature is 15 °C to obtain a crude liquid separation and a first high-salt water. Perform an oil-water separation operation on the crude liquid separation to obtain a first electrolyte solvent and a second high-salt water. Transport the first high-salt water and the second high-salt water to a flotation reaction tank for flotation treatment to obtain a second electrolyte solvent and a third high-salt water. Transport the first electrolyte solvent and the second electrolyte solvent to an electrolyte storage tank for recovery. Perform a freeze crystallization operation on the third high-salt water, and the freeze crystallization temperature is 0 °C to obtain lithium-rich water containing salting-out salt crystals. Perform a solid-liquid separation operation on the lithium-rich water containing salting-out salt crystals to obtain salting-out salt crystals and lithium-rich water. Recycle and reuse the salting-out salt crystals. Perform a precipitation separation operation on the lithium-rich water and carbonate to obtain crude lithium carbonate and filtered clear water.

[0099] Comparative Example 2

[0100] Filter press the waste lithium battery electrolyte wastewater, take the electrolyte filtrate into the salting-out stirring tank, add soluble salts and mix them. The addition amount of the soluble salts is 40 wt%, and the salting-out temperature is 40 °C to obtain a crude liquid separation and a first high-salt water. Perform an oil-water separation operation on the crude liquid separation to obtain a first electrolyte solvent and a second high-salt water. Transport the first high-salt water and the second high-salt water to a flotation reaction tank for flotation treatment to obtain a second electrolyte solvent and a third high-salt water. Transport the first electrolyte solvent and the second electrolyte solvent to an electrolyte storage tank for recovery. Perform a freeze crystallization operation on the third high-salt water, and the freeze crystallization temperature is 0 °C to obtain lithium-rich water containing salting-out salt crystals. Perform a solid-liquid separation operation on the lithium-rich water containing salting-out salt crystals to obtain salting-out salt crystals and lithium-rich water. Recycle and reuse the salting-out salt crystals. Perform a precipitation separation operation on the lithium-rich water and carbonate to obtain crude lithium carbonate and filtered clear water.

[0101] Comparative Example 3

[0102] The waste lithium battery electrolyte wastewater is pressure-filtered, and the electrolyte filtrate is taken into the salting-out stirring tank and mixed with a soluble salt. The addition amount of the soluble salt is 45 wt%, and the salting-out temperature is 15 °C to obtain a crude liquid separation and a first high-salt water. The crude liquid separation is subjected to an oil-water separation operation to obtain a first electrolyte solvent and a second high-salt water. The first high-salt water and the second high-salt water are transported to a flotation reaction tank for flotation treatment to obtain a second electrolyte solvent and a third high-salt water. The first electrolyte solvent and the second electrolyte solvent are transported to an electrolyte storage tank for recovery. The third high-salt water is subjected to a freeze crystallization operation at a freeze crystallization temperature of 0 °C to obtain lithium-rich water containing salting-out salt crystals. The lithium-rich water containing salting-out salt crystals is subjected to a solid-liquid separation operation to obtain salting-out salt crystals and lithium-rich water. The salting-out salt crystals are recovered and reused. The lithium-rich water is subjected to a precipitation separation operation with a carbonate to obtain crude lithium carbonate and filtered clear water.

[0103] The COD of the filtered clear water of Examples 1-3 and Comparative Examples 1-3 was measured, and the recovery rate of the electrolyte solvent was measured. The results are shown in Table 1.

[0104] Example Salt addition amount wt% Salting-out temperature °C Freezing temperature °C COD content mg / L Electrolyte recovery rate % Electrolyte filtrate / / / 160680 / Example 1 20 20 0 41141 71.66% Example 2 30 30 3 32998 76.04% Example 3 35 35 5 38116 73.31% Comparative example 1 10 15 0 67520 51.95% Comparative example 2 40 40 0 53120 58.78% Comparative example 3 45 15 0 57175 62.84%

[0105] It can be seen from Table 1 that: compared with Comparative Examples 1-3, in Examples 1-3, the electrolyte wastewater was recovered by controlling the salt addition within the range of 20 wt% - 35 wt% and the salting-out temperature within the range of 20 °C - 35 °C. The COD content of the filtered clear water in Examples 1-3 was significantly lower than that in Comparative Examples 1-3, and the electrolyte recovery rate in Examples 1-3 was significantly higher than that in Comparative Examples 1-3. Among them, the electrolyte recovery rate in Example 2 was as high as 76.04%. Therefore, by using the recovery method and device for waste lithium battery electrolyte wastewater of the present application for wastewater treatment, the COD of the wastewater was significantly reduced, and the recovery rate of the electrolyte solvent was above 75%.

[0106] In summary, by using the recovery method and device for waste lithium battery electrolyte wastewater of the present application for electrolyte wastewater treatment, a stable electrolyte can be recovered from the wastewater, and while effectively reducing the COD in the wastewater, the treatment cost of the wastewater can also be reduced.

[0107] Compared with the prior art, the present application has at least the following advantages:

[0108] 1. The recycling method of waste lithium battery electrolyte wastewater in this application first performs a pressure filtration operation on the electrolyte wastewater to remove solid impurities in the wastewater and obtain an electrolyte filtrate. Then, the electrolyte filtrate is mixed with a soluble salt for salting-out separation operation to obtain a crude liquid separation and a first high-salt water, that is, the density of the aqueous phase is increased by the soluble salt, so that the organic phase and the aqueous phase of the electrolyte can be separated. Secondly, the crude liquid separation is subjected to a fine liquid separation operation to obtain a first electrolyte solvent and a second high-salt water, so that the water-insoluble electrolyte solvent can be recovered. Immediately afterwards, the first high-salt water and the second high-salt water are mixed for air flotation oil removal operation. Through air flotation treatment, the water-soluble electrolyte solvent is separated from the water to obtain a second electrolyte solvent and a third high-salt water. At the same time, the oxygen in the air can oxidize some organic substances, which can not only effectively reduce the COD in the water, but also separate the water-soluble electrolyte solvent, so that the stable electrolyte solvent can be separated and recovered from the wastewater of the waste lithium battery recycling production line. Finally, the third high-salt water is subjected to a freezing crystallization operation, that is, a lithium-rich water containing salting-out salt crystals is formed, and then the solid-liquid separation operation is performed on the lithium-rich water containing salting-out salt crystals to obtain salting-out salt crystals and lithium-rich water, and the salting-out salt crystals are recycled and reused as soluble salts, so that the wastewater treatment cost can be effectively reduced.

[0109] 2. The recycling method of waste lithium battery electrolyte wastewater in this application only needs to separate the electrolyte solvent through salting-out separation operation, fine liquid separation operation and air flotation oil removal operation, which can effectively reduce the COD of the wastewater, and can also greatly simplify the recycling treatment process of waste lithium battery electrolyte wastewater. At the same time, after mixing the lithium-rich water and carbonate and performing a precipitation separation operation to obtain crude lithium carbonate and filtered clear water, not only can the electrolyte lithium salt be effectively recovered, but also the filtered clear water can be recycled to the equipment of the waste lithium battery recycling production line for recycling, so that zero discharge of waste lithium battery electrolyte wastewater can be realized, and then the recycling of water resources can be realized, and the wastewater treatment cost can be further reduced.

[0110] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0111] The above embodiments only represent several implementation manners of this application, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that for those of ordinary skill in the art, without departing from the concept of this application, several deformations and improvements can be made, and these all belong to the protection scope of this application. Therefore, the protection scope of this application patent should be subject to the appended claims.

Claims

1. A recycling method based on waste lithium battery electrolyte wastewater, characterized in that, It includes the following steps: Perform pressure filtration on the waste lithium battery electrolyte wastewater to obtain electrolyte filtrate; Mix the electrolyte filtrate with a soluble salt and then perform salting-out separation operation to obtain a crude separation liquid and a first high-salt water; Perform fine separation operation on the crude separation liquid to obtain a first electrolyte solvent and a second high-salt water; Mix the first high-salt water and the second high-salt water and then perform air flotation oil removal operation to obtain a second electrolyte solvent and a third high-salt water; Perform freeze crystallization operation on the third high-salt water to obtain lithium-rich water containing salting-out salt crystals; Perform solid-liquid separation operation on the lithium-rich water containing salting-out salt crystals to obtain salting-out salt crystals and lithium-rich water, and recycle the salting-out salt crystals; Mix the lithium-rich water and a carbonate and then perform precipitation separation operation to obtain crude lithium carbonate and filtered clear water, and recycle the filtered clear water; The specific operation steps for performing fine separation operation on the crude separation liquid to obtain a first electrolyte solvent and a second high-salt water are: Transport the crude separation liquid to an oil-water separator for oil-water separation operation to obtain the first electrolyte solvent and the second high-salt water, and recycle the first electrolyte solvent.

2. The recycling method based on waste lithium battery electrolyte wastewater according to claim 1, characterized in that, The step of performing pressure filtration on the waste lithium battery electrolyte wastewater to obtain electrolyte filtrate is specifically: Perform pressure filtration on the waste lithium battery electrolyte wastewater through a first pressure filter to obtain the electrolyte filtrate.

3. The recovery method based on waste lithium battery electrolyte wastewater according to claim 1, wherein, The specific operation steps for mixing the electrolyte filtrate with a soluble salt and then performing salting-out separation operation to obtain a crude separation liquid and a first high-salt water are: Add the electrolyte filtrate and the soluble salt into a salting-out stirring tank for salting-out stratification operation to obtain the crude separation liquid and the first high-salt water.

4. The recovery method based on waste lithium-ion battery electrolyte wastewater according to claim 1, wherein, The specific operation steps for mixing the first high-salt water and the second high-salt water and then performing air flotation oil removal operation to obtain a second electrolyte solvent and a third high-salt water are: Mix the first high-salt water and the second high-salt water and then transport them to an air flotation reaction tank for air flotation oil removal operation to obtain the second electrolyte solvent and the third high-salt water, and recycle the second electrolyte solvent.

5. The recovery method based on waste lithium battery electrolyte wastewater according to claim 1, wherein, The specific operation steps for performing freeze crystallization operation on the third high-salt water to obtain lithium-rich water containing salting-out salt crystals are: Perform freeze crystallization operation on the third high-salt water through a freeze crystallizer to obtain the lithium-rich water containing salting-out salt crystals.

6. The recycling method based on waste lithium battery electrolyte wastewater according to claim 3, wherein The step of performing solid-liquid separation operation on the lithium-rich water containing salting-out salt crystals to obtain salting-out salt crystals and lithium-rich water, and recycling the salting-out salt crystals is specifically: Perform solid-liquid separation operation on the lithium-rich water containing salting-out salt crystals through a solid-liquid separator to obtain the salting-out salt crystals and the lithium-rich water, and transport the salting-out salt crystals to the salting-out stirring tank for recycling.

7. The recovery method based on waste lithium battery electrolyte wastewater according to claim 1, wherein The step of mixing the lithium-rich water and a carbonate and then performing precipitation separation operation to obtain crude lithium carbonate and filtered clear water, and recycling the filtered clear water is specifically: Transport the lithium-rich water to a precipitation reaction tank, and add a carbonate into the precipitation reaction tank for mixing precipitation reaction to obtain a mixed slurry; The mixed slurry is transported to a second filter press for filter pressing operation to obtain the crude lithium carbonate and the filtered clear water, and the filtered clear water is transported to the waste lithium battery recycling production line equipment for recycling.

8. The recovery method based on waste lithium-ion battery electrolyte wastewater according to claim 1, wherein, The temperature of the freeze crystallization is 0°C - 5°C.

9. A recycling device based on waste lithium battery electrolyte wastewater, characterized in that, The electrolyte is recycled by using the recycling method based on waste lithium battery electrolyte wastewater described in any one of claims 1 - 8, and the filtered clear water after the recycling treatment is recycled; The recycling device includes a first filter press, a salting - out component, a fine separation component, a flotation separation component, an electrolyte storage tank, a crystallization component, a solid - liquid separation component, and a precipitation separation component. The feeding end of the first filter press is used to be externally connected to the waste lithium battery recycling production line equipment, and the liquid outlet end of the first filter press is communicated with the salting - out component; the salting - out component is communicated with the fine separation component, the electrolyte storage tank is respectively communicated with the fine separation component and the flotation separation component, the crystallization component is respectively communicated with the flotation separation component and the solid - liquid separation component, the solid - liquid separation component is communicated with the salting - out component, and the precipitation separation component is respectively communicated with the solid - liquid separation component and the waste lithium battery recycling production line equipment; The fine separation component is provided with an oil - water separator.

10. The recycling device for waste lithium battery electrolyte wastewater according to claim 9, characterized in that, The salting - out component is provided with a salting - out stirring tank, and the salting - out stirring tank is provided with a first liquid inlet, a first aqueous phase outlet, and a plurality of first organic phase outlets, and the first liquid inlet is communicated with the liquid outlet end of the first filter press.

11. The recycling device for waste lithium battery electrolyte wastewater according to claim 10, characterized in that, The oil - water separator is provided with a second liquid inlet, a second aqueous phase outlet, and a second organic phase outlet. The second liquid inlet is communicated with a plurality of the first organic phase outlets so that the oil - water separator is communicated with the salting - out stirring tank, and the second organic phase outlet is communicated with the liquid inlet end of the electrolyte storage tank.

12. The recycling device for waste lithium battery electrolyte wastewater according to claim 11, wherein, The flotation separation component is provided with a flotation reaction tank, and the flotation reaction tank is provided with a third liquid inlet, a third aqueous phase outlet, and a third organic phase outlet. The first aqueous phase outlet and the second aqueous phase outlet are both communicated with the third liquid inlet so that the flotation reaction tank is respectively communicated with the salting - out stirring tank and the oil - water separator, and the third organic phase outlet is communicated with the liquid inlet end of the electrolyte storage tank.

13. The recycling device for waste lithium battery electrolyte wastewater according to claim 12, characterized in that, The crystallization component is provided with a freeze crystallizer, and the feeding end of the freeze crystallizer is communicated with the third aqueous phase outlet.

14. The recycling device for waste lithium battery electrolyte wastewater according to claim 13, wherein, The solid - liquid separation component is provided with a solid - liquid separator. The liquid inlet end of the solid - liquid separator is communicated with the discharging end of the freeze crystallizer, and the solid discharging end of the solid - liquid separator is communicated with the salting - out stirring tank.

15. The recycling device for waste lithium battery electrolyte wastewater according to claim 14, wherein, The precipitation separation component includes a first liquid storage tank, a precipitation reaction tank, a second filter press, and a second liquid storage tank. The liquid inlet end of the first liquid storage tank is connected to the liquid discharging end of the solid - liquid separator. The liquid outlet end of the first liquid storage tank is respectively communicated with the feeding end of the precipitation reaction tank and the waste lithium battery recycling production line equipment. The discharging end of the precipitation reaction tank is communicated with the feeding end of the second filter press. The liquid discharging end of the second filter press is communicated with the liquid inlet end of the second liquid storage tank. The liquid outlet end of the second liquid storage tank is communicated with the waste lithium battery recycling production line equipment.

Images