WO2022252603A1 - Method for treating high-salt wastewater by discharging waste batteries and use thereof - Google Patents

Abstract

Disclosed in the present invention are a method for treating high-salt wastewater by discharging waste batteries and the use thereof. The method comprises the following steps: recycling waste lithium batteries, separating same to obtain aluminum, copper and manganese, melting aluminum and adding copper and manganese thereto to prepare a copper-manganese-doped aluminum sheet, and connecting same to a positive electrode of a direct-current voltage stabilizer; and filtering high-salt wastewater, then immersing the positive electrode connected to the copper-manganese-doped aluminum sheet and a negative electrode in the high-salt wastewater, followed by discharging and filtering same to obtain sulfate wastewater. Compared with the prior art, the present invention uses the electric energy of the waste lithium batteries to treat high-salt wastewater, so that the effect of complete discharge of the waste lithium batteries can be achieved, while materials such as NH₄ ⁺, Na⁺, SO₄ ^2-, F^- and carbonates can be removed from the high-salt wastewater, and the cost can be indirectly reduced. A copper-manganese-doped aluminum sheet involves the addition of copper and manganese to aluminum, which accelerates the electrolysis of an aluminum electrode, increases the autolysis of the aluminum electrode, accelerates the treatment of wastewater by aluminum ions, and further prevents easy passivation of the aluminum.

Description

A method and application of waste battery discharge treatment of high-salt wastewater technical field

The invention belongs to the technical field of wastewater treatment, and in particular relates to a method and application of waste battery discharge treatment of high-salt wastewater.

Background technique

Lithium batteries are widely used in 3C digital products, new energy electric vehicles, bicycles, industrial energy storage and other industries. The current service life of lithium batteries is relatively short, generally 2 to 6 years, which brings a large number of retired lithium batteries build up.

In the recycling and treatment of waste lithium batteries, the residual electrical energy in waste lithium batteries is usually treated by electrochemical discharge with a certain concentration of sodium chloride salt solution. The residual electric energy of the waste lithium battery is relatively high. In the case of discharge, the high-concentration sodium chloride solution can corrode the shell of the battery cell, and the explosion-proof hole of the battery cell is also dissolved, which inevitably causes the electrolyte to leak into the sodium chloride salt solution, resulting in electrolysis. The electrolyte in the liquid reacts with water to cause leakage of the organic solvent. Among them, the electrolyte reacts with water to generate hydrogen fluoride, and the organic carbonates in the leaked electrolyte will also volatilize. At the same time, the sodium chloride salt solution generates chlorine gas and hydrogen gas under discharge conditions, and the risk of explosion is prone to occur under light conditions. Harmful exhaust fumes diffuse into the air. Therefore, the discharge of waste lithium batteries poses a direct threat to the safety and health of operators, damages the discharge equipment of waste lithium batteries, and further creates potential environmental risks, as well as equipment required for waste gas treatment and the discharge of waste lithium batteries. The working environment puts forward higher requirements.

The high-salt wastewater generated in the waste lithium battery precursor production process contains NH ₄ ⁺ , Na ⁺ , SO ₄ ^2- , F ^- and other inorganic substances, as well as residual carbonates, polyvinylidene fluoride, polytetrafluoroethylene, methylol Organic substances and organic salts such as sodium cellulose base. It is a very representative type of industrial wastewater with the characteristics of large changes in water quality and quantity, complex components, and difficult biochemical degradation. At present, some people use electrochemical treatment of industrial high-salt wastewater, which has the advantages of simultaneous removal of multiple pollutants, good removal efficiency, wide range of applicable pH, and small footprint, but the power consumption of the electrochemical treatment process is relatively large. , the discharge efficiency and safety are not high enough, and the processing cost is relatively high.

Contents of the invention

The present invention aims to solve at least one of the technical problems in the above-mentioned prior art. For this reason, the present invention proposes a method and application of waste battery discharge treatment of high-salt wastewater. The method utilizes the remaining electric energy of waste lithium batteries to treat high-salt wastewater, which can achieve the effect of complete discharge of waste lithium batteries (high discharge efficiency), It can also remove NH ₄ ⁺ , Na ⁺ , SO ₄ ^2- , F ^- , carbonates and other substances in high-salt wastewater, and can indirectly reduce the cost. Aluminum-doped copper-manganese flakes are copper and manganese added to aluminum to accelerate the electrolysis of aluminum electrodes, increase the autolysis of aluminum electrodes, accelerate the production of aluminum ions to treat wastewater, and make aluminum difficult to passivate.

To achieve the above object, the present invention adopts the following technical solutions:

A method for treating high-salt wastewater by discharge of waste batteries, comprising the following steps:

(1) Melt aluminum, add copper and manganese to make aluminum-doped copper-manganese sheets, and connect them to the positive pole of the constant voltage regulator;

(2) Filtrate the high-salt wastewater, then immerse the positive and negative electrodes connected with the aluminum-doped copper-manganese sheet in the high-salt wastewater, discharge treatment, and filter to obtain sulfate wastewater; the aluminum-doped copper-manganese sheet is The extension of the positive pole of the constant voltage regulator.

The aforementioned use of aluminum, copper, and manganese produced in the recycling of waste lithium batteries to make aluminum-doped copper-manganese sheets as extension electrodes improves the recycling value of waste lithium battery resources. The aluminum electrode is mixed with recycled copper and manganese to avoid passivation during electrolysis of the extended electrode and improve the efficiency of electrolysis of high-salt wastewater.

The aluminum-doped copper-manganese sheet is used as an extended electrode instead of directly as the positive electrode. One is to allow the connected multiple waste lithium batteries (battery packs) to be continuously discharged until they run out of power. Second, if the aluminum-doped copper-manganese sheet is used directly As a positive electrode, it cannot continue to discharge after dissolution, resulting in poor wastewater treatment effect.

High-salt wastewater: high-salt wastewater refers to wastewater with a total salt content of at least 1%. The high-salt wastewater of the present invention mainly contains NH ₄ ⁺ , Na ⁺ , SO ₄ ^2- , Ca ²⁺ , F ^- , Cl ^- , CO ₃ ^2- .

In step (2), the salt concentration of the sulfate wastewater is <4.5g/L.

Preferably, in step (1), the aluminum, copper and manganese are obtained by separating and recycling waste lithium batteries.

Preferably, in step (1), the melting temperature of the aluminum is 660°C-1100°C.

Preferably, in step (1), the mass ratio of aluminum, copper and manganese is 100:(0.1-5):(0.1-5).

Preferably, in step (2), the high-salt wastewater is wastewater generated in the waste lithium battery recycling process or high-salt wastewater produced in printing and dyeing, smelting, chemical industry, and manufacturing.

Further preferably, the wastewater generated in the waste lithium battery recovery process is one or both of the impurity removal wastewater generated in the acid leaching process in the waste lithium battery recovery process or the deamination wastewater generated in the aging process. (The aging process is a conventional process for the recovery and treatment of positive electrode materials in waste lithium batteries)

More preferably, the volume ratio of the impurity-removing wastewater produced by the acid leaching process in the waste lithium battery recovery process to the deamination wastewater produced in the aging process of the waste lithium battery recovery process is (1.5-3):1.

Preferably, in step (2), the process of adjusting the pH of the high-salt wastewater is also included before filtering the high-salt wastewater.

Further preferably, the substance used in the pH adjustment process is one of sodium hydroxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sulfuric acid or hydrochloric acid.

More preferably, the pH is adjusted to 6.0-8.0.

Preferably, in step (2), the positive electrode is plated with an inert metal or an inert metal electrode; the aluminum-doped copper-manganese sheet is an extended electrode and is immersed in high-salt wastewater together with the positive electrode.

Further preferably, the inert metal-plated/inert metal electrode is a titanium-based/titanium-plated electrode, a titanium oxide electrode, an iron-nickel oxide electrode, a platinum-based/platinized electrode, or a platinum oxide electrode.

Preferably, in step (2), the negative pole is a graphite electrode.

Further preferably, the graphite electrode is a graphite mesh electrode, a graphite wire electrode, a graphite rod electrode, a graphite plate electrode

Preferably, in step (2), the output current of the discharge treatment is 0.05-3.0A.

Preferably, in step (2), the electrical energy for the discharge treatment is provided by several waste lithium batteries.

Preferably, the several waste lithium batteries are connected in series or in parallel to a constant voltage regulator.

Multiple used lithium battery packs (battery packs) are connected in series to increase the current required to access the constant voltage regulator, and multiple used lithium battery packs (battery packs) are connected in parallel to continuously provide the voltage required by the constant voltage regulator .

The present invention also provides the application of the above-mentioned sulfate wastewater in washing nickel-cobalt-manganese hydroxide.

Compared with the prior art, the beneficial effects of the present invention are as follows:

1. The present invention combines physical discharge and electrochemical wastewater treatment. Compared with the prior art, the present invention utilizes the electric energy of waste lithium batteries to treat high-salt wastewater, which can not only achieve the effect of complete discharge of waste lithium batteries, but also remove NH ₄ ⁺ , Na ⁺ , SO ₄ ^2- in high-salt wastewater , F ^- , carbonates and other substances, and can indirectly reduce the cost. Aluminum-doped copper-manganese flakes are copper and manganese added to aluminum to accelerate the process of aluminum electrodes, increase the autolysis of aluminum electrodes, accelerate the production of aluminum ions to treat wastewater, and at the same time make aluminum difficult to passivate.

2. Aluminum, copper, and manganese come from the recycling of waste lithium batteries, which are recycled and reused waste aluminum, copper, and manganese. Therefore, the cost of redischarging residual electric energy to treat high-salt wastewater is reduced again. In the present invention, multiple waste lithium battery groups (battery packs) are discharged in series and parallel at the same time, which shortens the time required for discharging the waste lithium battery packs (battery packs), and improves the discharge efficiency.

3. During the discharge process of the waste lithium battery of the present invention, no damage will be caused to the outer casing of the battery cell, explosion-proof holes, internal materials, etc., and the complete shape of the waste lithium battery pack (battery pack) is ensured, which has high safety and can realize safe discharge To 0V, the voltage does not rebound after discharge.

4. After the aluminum-doped copper-manganese sheet immersed in high-salt wastewater is gradually dissolved, the electrode plated with inert metal/inert metal can still discharge normally. It only needs to connect a new aluminum-doped copper-manganese sheet to the positive electrode to continue discharging, and then treat high-salt water waste water. Using the residual electric energy in waste lithium batteries to electrochemically treat the migration of inorganic and organic substances in wastewater for flocculation regulation, ultimately improving the stability and stability of the entire wastewater treatment system, while reducing the energy consumption of wastewater treatment, thereby reducing treatment costs.

5. In the saline wastewater treated by the discharge of the present invention, the colloidal particles formed have low bound water content and strong flocculation performance, and the flocs can be removed by filtration, which can remove most of NH ₄ ⁺ , Na ⁺ , SO ₄ ^2- , F ^- , carbonates and other substances, less pretreatment procedures for high-salt wastewater, simple equipment and technology, high pollutant removal capacity, and less fouling, which also reduces the use and dependence on chemicals.

Description of drawings

Fig. 1 is a flow chart of waste battery electric energy treatment of high-salt wastewater according to Embodiment 1 of the present invention.

Detailed ways

The conception and technical effects of the present invention will be clearly and completely described below in conjunction with the embodiments, so as to fully understand the purpose, features and effects of the present invention. Apparently, the described embodiments are only some of the embodiments of the present invention, rather than all of them. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts belong to The protection scope of the present invention.

Example 1

The method for treating high-salt wastewater by discharging waste batteries in this embodiment includes the following specific steps:

(1) Preparation of waste lithium battery electrode materials: Recycled waste lithium batteries are disassembled and discharged, subjected to high-temperature pyrolysis, shredder crushing, shelling, screening, leaching, synthesis, separation, and recycling to obtain aluminum, copper, and manganese;

(2) Preparation of aluminum-copper-manganese flakes: place the aluminum recovered from waste lithium batteries in a smelting furnace with a heating temperature of 660°C, and add copper and manganese after melting in the sintering kiln. The mass ratio of aluminum, copper and manganese is 100: 0.1:0.1, after pouring into the mold to prepare aluminum-doped copper-manganese sheets, the size of aluminum-doped copper-manganese sheets is: 40.0cm*30.0cm*0.4cm;

(3) Pretreatment of high-salt wastewater: mix the impurity-removing wastewater generated by the acid leaching process in the waste lithium battery recycling process, and the deamination wastewater generated during aging, and mix the two at a volume ratio = 1.5:1 to obtain about 137L of high-salt wastewater, and use hydrogen The sodium oxide solution adjusts the pH of the high-salt wastewater to 6.53, and then filters out the insoluble matter in the high-salt wastewater to obtain the high-salt wastewater to be treated, and analyzes and measures the salt content, ammonia nitrogen content, COD content, pH and turbidity in the high-salt wastewater;

(4) Discharge the waste lithium battery to treat high-salt wastewater: connect 12 waste lithium battery groups and 3 waste lithium battery groups in series, a total of 4 series groups, and then connect them in parallel to the constant voltage current regulator, and the constant voltage current regulator The positive and negative electrodes of the output end are connected to the high-salt wastewater to be treated, the positive electrode is an iron-nickel electrode, the external aluminum-doped copper-manganese sheet is connected, the negative electrode is a graphite rod electrode, the discharge treatment is 7h12min, the output current is 0.20A, graphite rod and aluminum-doped copper-manganese sheet The distance is 0.24cm, filter out the insoluble matter to obtain sulfate wastewater, analyze and measure the salt content, ammonia nitrogen content, COD content, pH and turbidity in the saline wastewater, until the residual voltage of the battery cell in the waste lithium battery pack is <0.05V, that is The discharge is complete.

Fig. 1 is the flow chart of waste battery electric energy treatment high-salt waste water of embodiment 1 of the present invention, can obtain from Fig. 1, the aluminum, copper, manganese that reclaims from waste lithium battery are prepared into aluminum-doped copper-manganese sheets and connected to constant voltage and steady flow The device is used to discharge high-salt wastewater to obtain sulfate wastewater.

Example 2

The method for treating high-salt wastewater by discharging waste batteries in this embodiment includes the following specific steps:

(1) Preparation of waste lithium battery electrode materials: Recycled waste lithium batteries are disassembled and discharged, subjected to high-temperature pyrolysis, crushing and shelling by a crusher, screening, leaching, synthesis, etc., to separate and recycle to obtain aluminum, copper, and manganese;

(2) Preparation of aluminum-copper-manganese flakes: place the aluminum recovered from waste lithium batteries in a smelting furnace at a heating temperature of 683°C, and add copper and manganese after melting in the sintering kiln. The mass ratio of aluminum, copper and manganese is 100: 1.2: 0.5, after pouring into the mold to make aluminum-doped copper-manganese sheets, the size of aluminum-doped copper-manganese sheets is: 40.0cm*40.0cm*0.3cm;

(3) Pretreatment of high-salt wastewater: The impurity removal wastewater produced by the acid leaching process in the waste lithium battery recycling process is about 65L of high-salt wastewater. Use sodium hydroxide solution to adjust the pH of the high-salt wastewater to 7.14, and then filter out the high-salt wastewater The insoluble matter in the water is obtained from the high-salt wastewater to be treated, and the salt content, ammonia nitrogen content, COD content, pH and turbidity in the high-salt wastewater are analyzed and determined;

(4) Waste lithium battery discharge treatment of high-salt wastewater: 20 waste lithium battery groups, 5 waste lithium battery groups in series, a total of 4 series groups, and then connected in parallel to the constant voltage current regulator, the output terminal of the constant voltage current regulator The positive and negative electrodes are connected to the high-salt wastewater to be treated, the positive electrode is an iron-nickel electrode, the external aluminum-doped copper-manganese sheet is connected, the negative electrode is a graphite rod electrode, the discharge treatment is 4h34min, the output current is 1.25A, and the distance between the graphite rod and the aluminum sheet is 0.28cm Remove insoluble matter to obtain sulfate wastewater, analyze and measure the salt content, ammonia nitrogen content, COD content, pH and turbidity in the saline wastewater, until the residual voltage of the battery cell in the waste lithium battery pack is <0.05V, the discharge is complete.

Example 3

The method for treating high-salt wastewater by discharging waste batteries in this embodiment includes the following specific steps:

(1) Preparation of waste lithium battery electrode materials: Recycled waste lithium batteries are disassembled and discharged, subjected to high-temperature pyrolysis, shredder crushing, shelling, screening, leaching, synthesis, separation, and recycling to obtain aluminum, copper, and manganese;

(2) Preparation of aluminum-doped copper-manganese sheets: Place the aluminum recovered from waste lithium batteries in the sintering kiln of a smelting furnace with a heating temperature of 728°C and then add copper and manganese. The mass ratio of aluminum, copper and manganese is 100:1.8 : 2.5, poured into the mold after molding, and prepared into aluminum-doped copper-manganese sheet, the size of aluminum-doped copper-manganese sheet is: 40.0cm*30.0cm*0.4cm;

(3) Pretreatment of high-salt wastewater: about 57L of deammoniated wastewater is produced during aging in the waste lithium battery recycling process, and the pH of the high-salt wastewater is adjusted to 7.57 with sulfuric acid solution, and then the insoluble matter in the high-salt wastewater is filtered out to obtain high-salt wastewater to be treated Wastewater, analysis and determination of salt content, ammonia nitrogen content, COD content, pH and turbidity in high-salt wastewater;

(4) Waste lithium battery discharge treatment of high-salt wastewater: 8 waste lithium battery groups, 2 waste lithium battery groups in series, a total of 4 series groups, and then connected in parallel to the constant-voltage current regulator, the output of the constant-voltage current regulator The positive and negative electrodes are connected to the high-salt wastewater to be treated, the positive electrode is an iron-nickel electrode, the external aluminum-doped copper-manganese sheet is connected, the negative electrode is a graphite rod electrode, the discharge treatment is 2h39min, the output current is 1.6A, the distance between the graphite rod and the aluminum sheet is 0.22cm, filter Remove insoluble matter to obtain sulfate wastewater, analyze and measure the salt content, ammonia nitrogen content, COD content, pH and turbidity in the saline wastewater, until the residual voltage of the battery cell in the waste lithium battery pack is <0.05V, the discharge is complete.

Example 4

The method for treating high-salt wastewater by discharging waste batteries in this embodiment includes the following specific steps:

(1) Preparation of waste lithium battery electrode materials: Recycled waste lithium batteries are disassembled and discharged, subjected to high-temperature pyrolysis, shredder crushing, shelling, screening, leaching, synthesis, separation, and recycling to obtain aluminum, copper, and manganese;

(2) Preparation of aluminum-doped copper-manganese sheets: place the aluminum recovered from waste lithium batteries in a smelting furnace, heat at 728°C, and add copper and manganese after melting in the sintering kiln. The mass ratio of aluminum, copper and manganese is 100:3 : 2. After pouring into the model to form, the aluminum-doped copper-manganese sheet is prepared, and the size of the aluminum-doped copper-manganese sheet is: 40.0cm*30.0cm*0.4cm;

(3) Pretreatment of high-salt wastewater: about 231L of wastewater from the processing and cleaning of edge milling machine parts, adjust the pH of the high-salt wastewater to 7.83 with sulfuric acid solution, and then filter out the insolubles in the high-salt wastewater to obtain the high-salt wastewater to be treated. Analysis Determination of salt content, ammonia nitrogen content, COD content, pH and turbidity in high-salt wastewater;

(4) Waste lithium battery discharge treatment of high-salt wastewater: 8 waste lithium battery groups, 2 waste lithium battery groups in series, a total of 4 series groups, and then connected in parallel to the constant-voltage current regulator, the output of the constant-voltage current regulator The positive and negative electrodes are connected to the high-salt wastewater to be treated, the positive electrode is an iron-nickel electrode, the external aluminum-doped copper-manganese sheet is connected, the negative electrode is a graphite rod electrode, the discharge treatment is 2h39min, the output current is 1.6A, the distance between the graphite rod and the aluminum sheet is 0.18cm, and the filter Remove insoluble matter to obtain sulfate wastewater, analyze and measure the salt content, ammonia nitrogen content, COD content, pH and turbidity in the saline wastewater, until the residual voltage of the battery cell in the waste lithium battery pack is <0.05V, the discharge is complete.

Example 5

The method for treating high-salt wastewater by discharging waste batteries in this embodiment includes the following specific steps:

(1) Preparation of waste lithium battery electrode materials: Recycled waste lithium batteries are disassembled and discharged, subjected to high-temperature pyrolysis, shredder crushing, shelling, screening, leaching, synthesis, separation, and recycling to obtain aluminum, copper, and manganese;

(2) Preparation of aluminum-doped copper-manganese sheets: Place the aluminum recovered from waste lithium batteries in a sintering kiln with a heating temperature of 1100°C and then add copper and manganese. The mass ratio of aluminum, copper and manganese is 100:5: 5. After pouring into the model to form, the aluminum-doped copper-manganese sheet is prepared. The size of the aluminum-doped copper-manganese sheet is: 40.0cm*30.0cm*0.4cm;

(3) Pretreatment of high-salt wastewater: the impurity removal wastewater produced by the acid leaching process in the recycling process of waste lithium batteries, and the deamination wastewater produced during aging, the two are mixed at a volume ratio = 3:1 to obtain about 137L of high-salt wastewater, which is oxidized with hydrogen The sodium solution adjusts the pH of the high-salt wastewater to 7.98, and then filters out the insoluble matter in the high-salt wastewater to obtain the high-salt wastewater to be treated, and analyzes and measures the salt content, ammonia nitrogen content, COD content, pH and turbidity in the high-salt wastewater;

(4) Waste lithium battery discharge treatment of high-salt wastewater: connect 28 waste lithium battery groups and 7 waste lithium battery groups in series, a total of 4 series groups, and then connect them in parallel to the constant-voltage current regulator, and the constant-voltage current regulator output The positive and negative electrodes at the terminal are connected to the high-salt wastewater to be treated, the positive electrode is an iron-nickel electrode, the external aluminum-doped copper-manganese sheet is connected, the negative electrode is a graphite rod electrode, the discharge treatment is 13h 48min, the output current is 3.0A, graphite rod and aluminum-doped copper-manganese sheet The distance is 0.15cm, filter out the insoluble matter to obtain sulfate wastewater, analyze and measure the salt content, ammonia nitrogen content, COD content, pH and turbidity in the saline wastewater, until the residual voltage of the battery cell in the waste lithium battery pack is <0.05V, that is The discharge is complete.

Comparative Results:

Table 1 Embodiment 1～5 each item data comparison table

It can be seen from Table 1 that the salt content of the high-salt wastewater treated by discharge has been reduced by more than 76%, the ammonia nitrogen content has been reduced by more than 75%, the COD content has been reduced by more than 74%, and the turbidity has been reduced by more than 76%. It proves that the high-salt wastewater after discharge treatment has low bound water content and strong flocculation performance. Most of the NH ₄ ⁺ , Na ⁺ , SO ₄ ^2- , F in high-salt wastewater can be removed by filtering and removing flocs. ^- , carbonates and other substances.

The embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments, and within the scope of knowledge of those of ordinary skill in the art, various modifications can be made without departing from the spirit of the present invention. Variety. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other if there is no conflict.

Claims (10)

A method for discharging high-salt wastewater, comprising the following steps: (1) Melt aluminum, add copper and manganese to make aluminum-doped copper-manganese sheets, and connect them to the positive pole of the constant voltage regulator; (2) Filter the high-salt wastewater, then immerse the positive and negative electrodes connected with the aluminum-doped copper-manganese sheet in the high-salt wastewater, discharge treatment, and filter to obtain sulfate wastewater; the aluminum-doped copper-manganese sheet is constant pressure The extension of the positive pole of the current regulator. The method according to claim 1, characterized in that, in step (1), the aluminum, copper, and manganese are recovered from waste lithium batteries. The method according to claim 1, characterized in that, in step (2), the mass ratio of aluminum, copper and manganese is 100:(0.1-5):(0.1-5). The method according to claim 1, characterized in that, in step (3), the high-salt wastewater is wastewater generated in the waste lithium battery recycling process or high-salt wastewater produced in printing and dyeing, smelting, and chemical manufacturing. The method according to claim 4, characterized in that, the waste water generated in the waste lithium battery recovery process is one of the impurity removal waste water produced by the acid leaching process in the waste lithium battery recovery process or the deamination waste water produced in the aging process or two. The method according to claim 1, characterized in that, in step (2), the positive electrode is plated with an inert metal or an inert metal electrode; the aluminum-doped copper-manganese sheet is an extended electrode and is immersed in high-salt wastewater together with the positive electrode. The method according to claim 1, characterized in that, in step (2), before the high-salt wastewater is filtered, the process of adjusting the pH of the high-salt wastewater is also included; the substance used in the process of adjusting the pH is hydrogen One of sodium oxide, potassium hydroxide, calcium hydroxide, magnesium hydroxide, sulfuric acid or hydrochloric acid. The method according to claim 1, characterized in that in step (2), the output current of the discharge treatment is 0.05-3.0A. The method according to claim 1, characterized in that, in step (2), the electrical energy for the discharge treatment is provided by several waste lithium batteries. The method described in any one of claims 1-9 is applied in the preparation of nickel-cobalt-manganese hydroxide.

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