阅读说明：本技术 一种废旧锂离子电池预提锂方法 (Method for pre-extracting lithium from waste lithium ion battery ) 是由 许开华 张坤 李琴香 杨健 蒋良兴 肖力 华文超 于 2021-09-16 设计创作，主要内容包括：本发明涉及废旧锂离子电池回收技术领域,提供一种废旧锂离子电池预提锂方法,包括：步骤1：对废旧锂离子电池进行预处理,得到电极活性材料粉末；步骤2：利用碱性溶液对电极活性材料粉末进行碱洗处理,过滤,除铜、铝,对碱洗处理后的电极活性材料粉末进行烘干处理；步骤3：将烘干的电极活性材料粉末与过渡金属盐溶液按一定固液比装入高压反应釜中,进行水热反应；步骤4：将水热反应后的溶液取出,过滤,得到富锂浸出液和过渡金属氧化物浸出渣；步骤5：对富锂浸出液进行净化除杂后,添加碳酸盐或碳酸氢盐进行沉锂,得到碳酸锂。本发明能够提高锂以及镍钴锰等有价金属的回收率,提高锂离子电池回收产品的纯度,且降低回收成本。(The invention relates to the technical field of waste lithium ion battery recovery, and provides a method for pre-extracting lithium from waste lithium ion batteries, which comprises the following steps: step 1: pretreating the waste lithium ion battery to obtain electrode active material powder; step 2: carrying out alkaline washing treatment on the electrode active material powder by using an alkaline solution, filtering, removing copper and aluminum, and drying the electrode active material powder subjected to alkaline washing treatment; and step 3: putting the dried electrode active material powder and a transition metal salt solution into a high-pressure reaction kettle according to a certain solid-to-liquid ratio, and carrying out hydrothermal reaction; and 4, step 4: taking out the solution after the hydrothermal reaction, and filtering to obtain a lithium-rich leaching solution and transition metal oxide leaching residues; and 5: and purifying the lithium-rich leaching solution to remove impurities, and adding carbonate or bicarbonate to precipitate lithium to obtain lithium carbonate. The invention can improve the recovery rate of valuable metals such as lithium, nickel, cobalt, manganese and the like, improve the purity of the recovered products of the lithium ion battery and reduce the recovery cost.)

1. A method for pre-extracting lithium from a waste lithium ion battery is characterized by comprising the following steps:

step 1: pretreatment of

Carrying out short-circuit discharge, disassembly, crushing, roasting and screening on the waste lithium ion battery to obtain electrode active material powder;

step 2: alkali washing, filtering and drying

Carrying out alkaline washing treatment on the electrode active material powder by using an alkaline solution, filtering, removing copper and aluminum, and drying the electrode active material powder subjected to alkaline washing treatment;

and step 3: hydrothermal reaction

Putting the dried electrode active material powder and a transition metal salt solution into a high-pressure reaction kettle according to a certain solid-to-liquid ratio, and carrying out hydrothermal reaction;

and 4, step 4: filtration

Taking out the solution after the hydrothermal reaction, and filtering to obtain a lithium-rich leaching solution and transition metal oxide leaching residues;

and 5: purifying, removing impurities and precipitating lithium

And purifying the lithium-rich leaching solution to remove impurities, and adding carbonate or bicarbonate to precipitate lithium to obtain lithium carbonate.

2. The method for pre-extracting lithium from waste lithium ion batteries according to claim 1, wherein the waste lithium ion batteries are one or more of waste lithium nickel oxide lithium ion batteries, lithium cobalt oxide lithium ion batteries, lithium manganate lithium ion batteries and nickel cobalt manganate lithium ion batteries.

3. The method for pre-extracting lithium from waste lithium ion batteries according to claim 1, wherein in the step 1, the waste lithium ion batteries are subjected to short-circuit discharge in a sodium sulfite solution until the termination voltage is lower than 1V, and the solute concentration of the sodium sulfite solution is 5-20%; disassembling the waste lithium ion battery after short-circuit discharge to obtain battery cell components; crushing the components of the battery core to obtain crushed materials; heating the crushed materials to 400-600 ℃ at the speed of 2-10 ℃/min in the air atmosphere, carrying out heat preservation roasting, and stripping the adhesive; in the adhesive stripping process, lime water with the concentration not lower than 50mg/L is adopted to absorb waste gas released in the stripping process, so that calcium fluoride is obtained; separating the stripped product to obtain Al and Cu foils and an electrode active material;

in the step 2, the alkaline solution is NaOH or NH₄One or more of OH and KOH, wherein the pH value of the alkaline solution is 10-14, the alkaline washing time is controlled to be 10-60min, and the temperature is controlled to be 20-50 ℃.

4. The method for pre-extracting lithium from waste lithium ion batteries according to claim 3, wherein in the step 2, the pH value of the alkaline solution is 10-12, the alkaline washing time is controlled to be 10-30min, and the temperature is controlled to be 25-35 ℃.

5. The method for pre-extracting lithium from waste lithium ion batteries according to claim 1, wherein in the step 3, the volume of the high-pressure reaction kettle is 1L, 500mL of transition metal salt solution is added into the high-pressure reaction kettle, and dried electrode active material powder is added according to a solid-to-liquid ratio of 10-100 g/L; controlling the reaction temperature of the hydrothermal reaction at 150-; the transition metal salt solution is one or more of sulfates, chlorides and nitrates of nickel, cobalt and manganese metals, and the concentration of the transition metal salt solution is 1-20 wt.%.

6. The method for pre-extracting lithium from waste lithium ion batteries according to claim 5, wherein the concentration of the transition metal salt solution is 1-10 wt.%, and the solid-to-liquid ratio is 20-50 g/L; the reaction temperature of the hydrothermal reaction is controlled to be 200-250 ℃, and the reaction time is controlled to be 180-360 min.

7. The method for pre-extracting lithium from waste lithium ion batteries according to claim 1, wherein in the step 5, the purification and impurity removal comprises adding NaOH into the leachate to adjust the pH value of the leachate to 8-10, and then adding Na into the leachate₂S, precipitating to remove transition metal ions.

8. The method for pre-extracting lithium from waste lithium ion batteries according to claim 7, wherein in the step 5, NaOH is added into the leachate to adjust the pH value of the leachate to 8.5-9.5.

9. The method for pre-extracting lithium from waste lithium ion batteries according to claim 1, wherein in the step 5, the lithium precipitation is to add carbonate or bicarbonate of sodium, potassium or ammonium to the purified and impurity-removed solution to adjust the pH value of the solution to 11-13, control the lithium precipitation temperature to 80-95 ℃, and precipitate to obtain lithium carbonate.

10. The method for pre-extracting lithium from waste lithium ion batteries according to claim 9, wherein in the step 5, the pH value of the solution is adjusted to 12-13.

Technical Field

The invention relates to the technical field of waste lithium ion battery recovery, in particular to a method for pre-extracting lithium from waste lithium ion batteries.

Background

With the rapid development of modern technology, the pollution problem of social energy and environment ecology becomes more and more prominent, and especially the pollution problem of various waste batteries to the environment and the ecology becomes the focus of social attention. Lithium ion batteries are widely used in the field of power batteries and energy storage batteries due to the characteristics of high capacity, stable cycle performance, high working platform voltage and the like, and the requirements of power and energy storage batteries on battery materials are generally greater than those of conventional small batteries. Therefore, in the future 3-5 years, a large number of lithium ion batteries are scrapped, and the recycling of the lithium ion batteries has high social value.

In the current domestic waste lithium ion battery recovery technology, the mainstream way for treating the electrode active material of the waste lithium ion battery is as follows: 1) acid reduction leaching to obtainContaining Li⁺、Ni²⁺、Co²⁺、Mn²⁺、Al³⁺、Fe³⁺Precipitating the leachate of plasma to remove iron and aluminum, and then adjusting the pH value to respectively obtain precipitates of single metal; 2) precipitating to remove iron and aluminum, extracting nickel, cobalt and manganese, and performing acid back extraction to obtain a salt solution only containing nickel, cobalt or manganese. The existing waste lithium ion battery recycling technology has certain defects, for example, a method for recycling valuable metals from nickel cobalt lithium manganate batteries and preparing nickel cobalt lithium manganate disclosed in chinese patent CN104538695A "a method for recycling valuable metals from nickel cobalt lithium manganate batteries by using an acid leaching method" firstly leaching an electrode active material with an inorganic acid to obtain a leachate, precipitating to remove iron and aluminum, then adding an alkali to control different PH values to obtain precipitates corresponding to a single metal, and finally recovering lithium. Also, as "a process for recovering valuable metals from waste lithium batteries" disclosed in chinese patent CN102162034A, the recovery of valuable metals such as cobalt, copper, nickel, and aluminum is realized by using the process steps of pretreatment, leaching, chemical impurity removal, extraction and separation, but expensive extractants are used in the extraction and separation process, and the operation is complicated, and the process is close to the recovery process used in industrial production, but has the disadvantage of high recovery cost. The processes are that firstly, acid leaching is carried out, then impurities are removed, metals such as nickel, cobalt and manganese are recovered, and finally lithium is recovered, so that entrainment and precipitation of lithium are easily caused when valuable metal elements such as nickel, cobalt and manganese are recovered, the recovery rate of lithium is reduced, and only a single waste lithium ion battery is treated.

Disclosure of Invention

Aiming at the problems in the prior art, the invention provides a method for pre-extracting lithium from a waste lithium ion battery, which can improve the recovery rate of valuable metals such as lithium, nickel, cobalt, manganese and the like, improve the purity of the recovered product of the lithium ion battery and reduce the recovery cost.

The technical scheme of the invention is as follows:

a method for pre-extracting lithium from a waste lithium ion battery is characterized by comprising the following steps:

step 1: pretreatment of

Carrying out short-circuit discharge, disassembly, crushing, roasting and screening on the waste lithium ion battery to obtain electrode active material powder;

step 2: alkali washing, filtering and drying

Carrying out alkaline washing treatment on the electrode active material powder by using an alkaline solution, filtering, removing copper and aluminum, and drying the electrode active material powder subjected to alkaline washing treatment;

and step 3: hydrothermal reaction

Putting the dried electrode active material powder and a transition metal salt solution into a high-pressure reaction kettle according to a certain solid-to-liquid ratio, and carrying out hydrothermal reaction;

and 4, step 4: filtration

Taking out the solution after the hydrothermal reaction, and filtering to obtain a lithium-rich leaching solution and transition metal oxide leaching residues;

and 5: purifying, removing impurities and precipitating lithium

And purifying the lithium-rich leaching solution to remove impurities, and adding carbonate or bicarbonate to precipitate lithium to obtain lithium carbonate.

Furthermore, the waste lithium ion battery is one or more of a waste lithium nickel oxide lithium ion battery, a waste lithium cobalt oxide lithium ion battery, a waste lithium manganese oxide lithium ion battery and a waste lithium nickel cobalt manganese oxide lithium ion battery.

Further, in the step 1, short-circuit discharge is performed on the waste lithium ion battery in a sodium sulfite solution until the termination voltage is lower than 1V, and the solute concentration of the sodium sulfite solution is 5-20%; disassembling the waste lithium ion battery after short-circuit discharge to obtain battery cell components; crushing the components of the battery core to obtain crushed materials; heating the crushed materials to 400-600 ℃ at the speed of 2-10 ℃/min in the air atmosphere, carrying out heat preservation roasting, and stripping the adhesive; in the adhesive stripping process, lime water with the concentration not lower than 50mg/L is adopted to absorb waste gas released in the stripping process, so that calcium fluoride is obtained; separating the stripped product to obtain Al and Cu foils and an electrode active material;

in the step 2, the alkaline solution isNaOH、NH₄One or more of OH and KOH, wherein the pH value of the alkaline solution is 10-14, the alkaline washing time is controlled to be 10-60min, and the temperature is controlled to be 20-50 ℃.

Further, in the step 2, the pH value of the alkaline solution is 10-12, the alkaline washing time is controlled to be 10-30min, and the temperature is controlled to be 25-35 ℃.

Further, in the step 3, the volume of the high-pressure reaction kettle is 1L, 500mL of transition metal salt solution is added into the high-pressure reaction kettle, and dried electrode active material powder is added according to the solid-to-liquid ratio of 10-100 g/L; controlling the reaction temperature of the hydrothermal reaction at 150-; the transition metal salt solution is one or more of sulfates, chlorides and nitrates of nickel, cobalt and manganese metals, and the concentration of the transition metal salt solution is 1-20 wt.%.

Further, the concentration of the transition metal salt solution is 1-10 wt.%, and the solid-to-liquid ratio is 20-50 g/L; the reaction temperature of the hydrothermal reaction is controlled to be 200-250 ℃, and the reaction time is controlled to be 180-360 min.

Further, in the step 5, the step of purifying and removing impurities includes adding NaOH to the leachate to adjust the pH of the leachate to 8-10, and then adding Na₂S, precipitating to remove transition metal ions.

Further, in the step 5, NaOH is added to the leachate to adjust the pH of the leachate to 8.5-9.5.

Further, in the step 5, the lithium precipitation is to add carbonate or bicarbonate of sodium, potassium or ammonium to the purified solution to adjust the pH value of the solution to 11-13, control the lithium precipitation temperature to 80-95 ℃, and precipitate to obtain lithium carbonate.

Further, in the step 5, the pH value of the solution is adjusted to 12-13.

The invention has the beneficial effects that:

(1) the invention adopts a recovery mode of extracting lithium from the electrode active material in advance and then recovering valuable metal elements such as nickel, cobalt, manganese and the like, breaks through the inherent technical thought of recovering the valuable metal elements such as nickel, cobalt, manganese and the like and then recovering lithium in the conventional waste lithium ion battery recovery technology, solves the technical problem of low product purity caused by lithium entrainment in a nickel, cobalt and manganese precursor when the nickel, cobalt and manganese precursor is precipitated and then a lithium product is precipitated in the conventional waste lithium ion battery recovery technology, and improves the recovery rate of the lithium, the nickel, cobalt, manganese and other valuable metals.

(2) According to the invention, the electrode active material is subjected to alkali washing in advance to remove impurities such as copper and aluminum, so that the concentration of impurity ions in a leachate in the subsequent process of recovering valuable metals such as lithium, nickel, cobalt and manganese is greatly reduced, the loss of the valuable metals such as lithium, nickel, cobalt and manganese caused by entrainment in the impurity removal process of the traditional recovery process is avoided, the recovery rate of the valuable metals such as lithium, nickel, cobalt and manganese is further improved, and the purity of the recovered product is improved.

(3) According to the invention, the electrode active material subjected to alkali washing and impurity removal is subjected to hydrothermal reaction treatment, lithium is enriched in the leachate subjected to hydrothermal treatment, purification and impurity removal are carried out, and lithium precipitation is carried out to recover lithium, so that the extraction rate of lithium is effectively ensured, the pre-extraction rate of lithium is above 95% under the cooperative control of all links in the recovery process, the leaching rate of valuable metals such as nickel, cobalt, manganese and the like in the hydrothermal reaction is below 1%, the entrainment loss of valuable metal elements such as nickel, cobalt, manganese and the like in the electrode active material is reduced, the recovery rate of lithium is improved, the recovery rates of other valuable metal elements are ensured, and the impurity removal process is reduced.

(4) The method can simultaneously treat various waste lithium ion batteries without respectively recovering, is suitable for forming a closed flow, does not produce secondary pollution, gives consideration to environmental protection and economic benefits, has large variable operating condition range, simple operation and good repeatability, is different from the prior method which is mostly only suitable for laboratories, and is particularly suitable for industrial amplification production.

Drawings

Fig. 1 is a flow chart of a method for pre-extracting lithium from a waste lithium ion battery according to the invention.

Fig. 2 is an SEM image of the positive electrode active material powder before hydrothermal treatment in example 1.

Fig. 3 is an SEM image of the positive electrode active material powder after hydrothermal treatment in example 1.

Fig. 4 is an XRD pattern of lithium carbonate obtained after lithium deposition in example 1.

Detailed Description

The invention will be further described with reference to the accompanying drawings and specific embodiments.

As shown in fig. 1, the method for pre-extracting lithium from waste lithium ion batteries of the present invention comprises the following steps:

step 1: pretreatment of

And carrying out short-circuit discharge, disassembly, crushing, roasting and screening on the waste lithium ion battery to obtain electrode active material powder.

In the invention, the operations of short-circuit discharging the waste lithium ion battery, disassembling the discharged waste lithium ion battery, crushing the cell component obtained after disassembly, stripping the binder, separating to obtain the electrode active component and the like can adopt the operations known in the field. Preferably, the waste lithium ion battery is subjected to short-circuit discharge in a sodium sulfite solution until the termination voltage is lower than 1V, and the solute concentration of the sodium sulfite solution is 5-20%; disassembling the waste lithium ion battery after short-circuit discharge to obtain battery cell components; crushing the components of the battery core to obtain crushed materials; heating the crushed materials to 400-600 ℃ at the speed of 2-10 ℃/min in the air atmosphere, carrying out heat preservation roasting, and stripping the adhesive; in the adhesive stripping process, lime water with the concentration not lower than 50mg/L is adopted to absorb waste gas released in the stripping process, so that calcium fluoride is obtained; and separating the stripped product to obtain Al and Cu foils and an electrode active material.

The waste lithium ion battery is one or more of a waste lithium nickel oxide lithium ion battery, a waste lithium cobalt oxide lithium ion battery, a waste lithium manganese oxide lithium ion battery and a waste lithium nickel cobalt manganese oxide lithium ion battery. The method can simultaneously treat various waste lithium ion batteries without respectively recovering, is suitable for forming a closed flow, does not produce secondary pollution, gives consideration to environmental protection and economic benefits, has large variable operating condition range, simple operation and good repeatability, is different from the prior method which is mostly only suitable for laboratories, and is particularly suitable for industrial amplification production.

Step 2: alkali washing, filtering and drying

And (3) carrying out alkaline washing treatment on the electrode active material powder by using an alkaline solution, filtering, removing copper and aluminum, and drying the electrode active material powder subjected to alkaline washing treatment.

The alkaline solution is NaOH and NH₄One or more of OH and KOH, wherein the pH value of the alkaline solution is 10-14, the alkaline washing time is controlled to be 10-60min, and the temperature is controlled to be 20-50 ℃. Further, the pH value of the alkaline solution is 10-12, the alkaline washing time is controlled to be 10-30min, and the temperature is controlled to be 25-35 ℃.

According to the invention, the electrode active material is subjected to alkali washing in advance to remove impurities such as copper and aluminum, so that the concentration of impurity ions in a leachate in the subsequent process of recovering valuable metals such as lithium, nickel, cobalt and manganese is greatly reduced, the loss of the valuable metals such as lithium, nickel, cobalt and manganese caused by entrainment in the impurity removal process of the traditional recovery process is avoided, the recovery rate of the valuable metals such as lithium, nickel, cobalt and manganese is further improved, and the purity of the recovered product is improved.

And step 3: hydrothermal reaction

And (3) putting the dried electrode active material powder and the transition metal salt solution into a high-pressure reaction kettle according to a certain solid-to-liquid ratio, and carrying out hydrothermal reaction.

The volume of the high-pressure reaction kettle is 1L, 500mL of transition metal salt solution is added into the high-pressure reaction kettle, and dried electrode active material powder is added according to the solid-to-liquid ratio of 10-100 g/L; controlling the reaction temperature of the hydrothermal reaction at 150-; the transition metal salt solution is one or more of sulfates, chlorides and nitrates of nickel, cobalt and manganese metals, and the concentration of the transition metal salt solution is 1-20 wt.%. Further, the concentration of the transition metal salt solution is 1-10 wt.%, and the solid-to-liquid ratio is 20-50 g/L; the reaction temperature of the hydrothermal reaction is controlled to be 200-250 ℃, and the reaction time is controlled to be 180-360 min.

According to the invention, the electrode active material subjected to alkali washing and impurity removal is subjected to hydrothermal reaction treatment, lithium is enriched in the leachate subjected to hydrothermal treatment, purification and impurity removal are carried out, and lithium precipitation is carried out to recover lithium, so that the extraction rate of lithium is effectively ensured, the pre-extraction rate of lithium is above 95% under the cooperative control of all links in the recovery process, the leaching rate of valuable metals such as nickel, cobalt, manganese and the like in the hydrothermal reaction is below 1%, the entrainment loss of valuable metal elements such as nickel, cobalt, manganese and the like in the electrode active material is reduced, the recovery rate of lithium is improved, the recovery rates of other valuable metal elements are ensured, and the impurity removal process is reduced.

And 4, step 4: filtration

And taking out the solution after the hydrothermal reaction, and filtering to obtain a lithium-rich leaching solution and transition metal oxide leaching residues.

And 5: purifying, removing impurities and precipitating lithium

And purifying the lithium-rich leaching solution to remove impurities, and adding carbonate or bicarbonate to precipitate lithium to obtain lithium carbonate.

The purification and impurity removal comprises the steps of adding NaOH into the leachate to adjust the pH value of the leachate to 8-10, and then adding Na₂S, precipitating to remove transition metal ions. Further, NaOH is added into the leaching solution to adjust the pH value of the leaching solution to 8.5-9.5.

And the lithium precipitation is to add carbonate or bicarbonate of sodium, potassium or ammonium into the purified and impurity-removed solution to adjust the pH value of the solution to 11-13, control the lithium precipitation temperature to be 80-95 ℃, and precipitate to obtain lithium carbonate. Further, the pH value of the solution is adjusted to 12-13.

In addition, the leaching residue of the transition metal oxide is treated to recover valuable metals.

The invention adopts a recovery mode of extracting lithium from the electrode active material in advance and then recovering valuable metal elements such as nickel, cobalt, manganese and the like, breaks through the inherent technical thought of recovering the valuable metal elements such as nickel, cobalt, manganese and the like and then recovering lithium in the conventional waste lithium ion battery recovery technology, solves the technical problem of low product purity caused by lithium entrainment in a nickel, cobalt and manganese precursor when the nickel, cobalt and manganese precursor is precipitated and then a lithium product is precipitated in the conventional waste lithium ion battery recovery technology, and improves the recovery rate of the lithium, the nickel, cobalt, manganese and other valuable metals.

Example 1

Mixing waste LiNiO₂、LiCoO₂、LiMnO₂、LiNi_xCo_yMn_1-x-yO₂Soaking the lithium ion battery, namely the waste mixed lithium ion batteryDischarging to the termination voltage of 1V in 5% sodium sulfite solution; disassembling the discharged waste lithium ion battery to obtain battery cell components; carrying out mechanical force integral crushing on the battery cell components to obtain crushed materials, screening the crushed materials with the particle size of less than 0.1mm, and sending the crushed materials into a roasting process; heating the crushed materials to 400 ℃ at the speed of 2 ℃/min in the air atmosphere, carrying out heat preservation roasting for 1h, stripping the adhesive, and absorbing roasting waste gas by using 50mg/L lime water; and separating the stripped product to obtain Al and Cu foils and an electrode active material. And (3) carrying out alkali washing on the electrode active material powder generated by roasting, wherein the alkali washing parameters are as follows: NH with pH 10₄And (3) carrying out alkaline washing on the OH solution for 10min at the alkaline washing temperature of 20 ℃, filtering, separating and drying to obtain the electrode active material purified by alkaline washing. Then carrying out hydrothermal treatment on the dried electrode active material powder, wherein the hydrothermal treatment parameters are as follows: the transition metal salt solution is MnSO₄Solution of MnSO₄The concentration of the solution is 1 wt.%, the solid-to-liquid ratio is 10g/L, the reaction temperature is 150 ℃, the reaction time is 60min, and the stirring speed is 400 rpm. And taking out the solution after the hydrothermal reaction, and filtering to obtain a lithium-rich leaching solution and transition metal oxide leaching residues. Finally, NaOH is added into the leaching solution to adjust the pH value of the leaching solution to 8, and Na is added₂S, precipitating to remove transition metal ions, and adding Na into the purified solution₂CO₃Adjusting the pH value of the solution to 11, controlling the lithium precipitation temperature to 80 ℃, precipitating and filtering to obtain Li₂CO₃。

Example 2

The present embodiment 2 differs from embodiment 1 in that: in the hydrothermal treatment process, the transition metal salt solution is NiSO₄And (3) solution.

Example 3

Mixing waste LiNiO₂、LiCoO₂、LiMnO₂、LiNi_xCo_yMn_1-x-yO₂The lithium ion battery, namely the waste mixed lithium ion battery, is soaked in a 10 percent sodium sulfite solution and is discharged until the stop voltage is 0.8V; disassembling the discharged waste lithium ion battery to obtain battery cell components; the cell components are subjected to mechanical force integral crushing to obtain crushed materials, and the crushed materials with the particle size of less than 0.1mm are screenedSending the mixture into a roasting process; heating the crushed aggregates to 450 ℃ at the speed of 5 ℃/min in the air atmosphere, carrying out heat preservation roasting for 1h, stripping the adhesive, and absorbing roasting waste gas by using 50mg/L lime water; and separating the stripped product to obtain Al and Cu foils and an electrode active material. And (3) carrying out alkali washing on the electrode active material powder generated by roasting, wherein the alkali washing parameters are as follows: NH with pH 10.5₄And (3) carrying out alkaline washing on the OH solution for 20min at an alkaline washing temperature of 25 ℃, filtering, separating and drying to obtain the electrode active material purified by alkaline washing. Then carrying out hydrothermal treatment on the dried electrode active material powder, wherein the hydrothermal treatment parameters are as follows: the transition metal salt solution is MnSO₄Solution of MnSO₄The concentration of the solution is 5 wt.%, the solid-to-liquid ratio is 20g/L, the reaction temperature is 200 ℃, the reaction time is 180min, and the stirring speed is 400 rpm. And taking out the solution after the hydrothermal reaction, and filtering to obtain a lithium-rich leaching solution and transition metal oxide leaching residues. Finally, NaOH is added into the leaching solution to adjust the pH value of the leaching solution to 8.5, and Na is added₂S, precipitating to remove transition metal ions, and adding Na into the purified solution₂CO₃Adjusting the pH value of the solution to 12, controlling the lithium precipitation temperature to 90 ℃, precipitating and filtering to obtain Li₂CO₃。

Example 4

Mixing waste LiNiO₂、LiCoO₂、LiMnO₂、LiNi_xCo_yMn_1-x-yO₂The lithium ion battery, namely the waste mixed lithium ion battery, is soaked in a 15 percent sodium sulfite solution and is discharged until the stop voltage is 0.7V; disassembling the discharged waste lithium ion battery to obtain battery cell components; carrying out mechanical force integral crushing on the battery cell components to obtain crushed materials, screening the crushed materials with the particle size of less than 0.1mm, and sending the crushed materials into a roasting process; heating the crushed aggregates to 450 ℃ at the speed of 10 ℃/min in the air atmosphere, carrying out heat preservation roasting for 1h, stripping the adhesive, and absorbing roasting waste gas by using 50mg/L lime water; and separating the stripped product to obtain Al and Cu foils and an electrode active material. And (3) carrying out alkali washing on the electrode active material powder generated by roasting, wherein the alkali washing parameters are as follows: NH with pH 12₄OH solution, alkali washing time is 30min, alkali washing temperature is 35 ℃, filtering, separating and dryingAnd drying to obtain the electrode active material purified by alkali washing. Then carrying out hydrothermal treatment on the dried electrode active material powder, wherein the hydrothermal treatment parameters are as follows: the transition metal salt solution is MnSO₄Solution of MnSO₄The concentration of the solution is 10 wt.%, the solid-to-liquid ratio is 50g/L, the reaction temperature is 250 ℃, the reaction time is 240min, and the stirring speed is 400 rpm. And taking out the solution after the hydrothermal reaction, and filtering to obtain a lithium-rich leaching solution and transition metal oxide leaching residues. Finally, NaOH is added into the leaching solution to adjust the pH value of the leaching solution to 9.5, and Na is added₂S, precipitating to remove transition metal ions, and adding Na into the purified solution₂CO₃Adjusting the pH value of the solution to 12.5, controlling the lithium precipitation temperature at 95 ℃, precipitating and filtering to obtain Li₂CO₃。

Example 5

Mixing waste LiNiO₂、LiCoO₂、LiMnO₂、LiNi_xCo_yMn_1-x-yO₂The lithium ion battery, namely the waste mixed lithium ion battery, is soaked in a 20 percent sodium sulfite solution and is discharged until the stop voltage is 0.5V; disassembling the discharged waste lithium ion battery to obtain battery cell components; carrying out mechanical force integral crushing on the battery cell components to obtain crushed materials, screening the crushed materials with the particle size of less than 0.1mm, and sending the crushed materials into a roasting process; heating the crushed aggregates to 600 ℃ at the speed of 10 ℃/min in the air atmosphere, carrying out heat preservation roasting for 1h, stripping the adhesive, and absorbing roasting waste gas by using 50mg/L lime water; and separating the stripped product to obtain Al and Cu foils and an electrode active material. And (3) carrying out alkali washing on the electrode active material powder generated by roasting, wherein the alkali washing parameters are as follows: NH with pH 14₄And (3) carrying out alkaline washing on the OH solution for 60min at an alkaline washing temperature of 50 ℃, filtering, separating and drying to obtain the electrode active material purified by alkaline washing. Then carrying out hydrothermal treatment on the dried electrode active material powder, wherein the hydrothermal treatment parameters are as follows: the transition metal salt solution is MnSO₄Solution of MnSO₄The concentration of the solution is 20 wt.%, the solid-to-liquid ratio is 100g/L, the reaction temperature is 300 ℃, the reaction time is 360min, and the stirring speed is 400 rpm. Then taking out the solution after the hydrothermal reaction, and filtering to obtain a lithium-rich leaching solution and a transition metal oxide leaching solutionAnd (6) deslagging. Finally, NaOH is added into the leaching solution to adjust the pH value of the leaching solution to 10, and Na is added₂S, precipitating to remove transition metal ions, and adding Na into the purified solution₂CO₃Adjusting the pH value of the solution to 13, controlling the lithium precipitation temperature to 90 ℃, precipitating and filtering to obtain Li₂CO₃。

As shown in fig. 2 and 3, SEM (scanning electron microscope) images of the positive electrode active material powder before and after the hydrothermal treatment in example 1 were obtained. As shown in fig. 4, the XRD pattern of lithium carbonate obtained after lithium deposition in example 1 is shown. As can be seen from fig. 2 and 3, the sample powder is transformed from spherical primary particles into secondary particles having no standard shape before and after the treatment due to the lithium deintercalation. As can be seen from FIG. 4, obtained is Li with good crystal form₂CO₃。

In the embodiment of the invention, the percentage content of aluminum in the active substance after alkaline washing is reduced from 0.92% to 0.01%, the pre-extraction rate of lithium reaches 97%, the leaching rates of nickel, cobalt and manganese valuable metals in hydrothermal treatment are all below 0.5%, the comprehensive recovery rate of lithium exceeds 85%, and the obtained Li₂CO₃The purity of (2) is over 99.5%.

Comparative example 1

Comparative example 1 differs from example 1 in that any one of the transition metal salt solutions was not selected during the hydrothermal treatment, but Na was selected₂SO₄The solution hydrothermally treats the dried electrode active material powder.

In the comparative example 1, the percentage of aluminum in the active material after alkaline washing was reduced from 0.92% to 0.01%, and the pre-extraction rate of lithium was less than 5%. It can be seen that the other salt solutions do not have the effect of pre-extracting lithium.

Comparative example 2

The difference between the comparative example 2 and the example 1 is that the technological reaction time parameter selected in the hydrothermal treatment process is not within the set range of 180-360min, and the hydrothermal reaction time is controlled to be 30min

In the comparative example 2, the percentage content of aluminum in the active material after alkaline washing is reduced from 0.92% to 0.01%, and the pre-extraction rate of lithium is lower than 50%, which shows that the pre-extraction rate of lithium is reduced when the hydrothermal reaction time parameter is not in the set range.

It is to be understood that the above-described embodiments are only a few embodiments of the present invention, and not all embodiments. The above examples are only for explaining the present invention and do not constitute a limitation to the scope of protection of the present invention. All other embodiments, which can be derived by those skilled in the art from the above-described embodiments without any creative effort, namely all modifications, equivalents, improvements and the like made within the spirit and principle of the present application, fall within the protection scope of the present invention claimed.