A method for recovering valuable metals from an ammoniacal solution containing nickel, cobalt, lithium

Abstract

The application provides a method for recovering valuable metals from an ammonia solution containing nickel, cobalt and lithium, comprising the following steps: S1, performing solvent extraction on a first aqueous phase by using an organic phase to obtain a nickel-containing loaded organic phase and a lithium-cobalt-containing raffinate; S2, washing ammonia from the loaded organic phase, then stripping the loaded organic phase, evaporating and crystallizing the stripping solution to obtain a nickel sulfate product, and returning the organic phase after stripping to the solvent extraction; S3, heating and evaporating ammonia from the lithium-cobalt-containing raffinate, performing solid-liquid separation, obtaining lithium-cobalt-containing ammonia evaporation precipitate and ammonia evaporation post-liquid, and recycling the ammonia evaporation post-liquid and ammonia for ammonia leaching of waste materials containing lithium, nickel and cobalt; adding a lithium source or a cobalt source to the ammonia evaporation precipitate and mixing, adjusting the molar ratio of lithium to cobalt in the ammonia evaporation precipitate to 1, and then roasting to obtain a lithium cobalt oxide positive electrode material. The method is simple, can efficiently recover valuable metals, and no waste liquid is generated.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of resource recycling, in particular to a method for recovering valuable metals from an ammonia-containing solution containing nickel, cobalt and lithium. BACKGROUND

[0002] Lithium-ion batteries are widely used in electronic devices and new energy vehicles due to their high energy density, small size and light weight. However, the widespread use of lithium-ion batteries will inevitably generate a large number of waste lithium-ion batteries. If these waste lithium-ion batteries are not properly treated, on the one hand, they will pollute the environment and harm human health, and on the other hand, they will cause the loss of strategic metals such as lithium, nickel and cobalt contained therein. Therefore, from the perspective of environmental protection and resource conservation, the recycling of waste lithium-ion batteries has significant economic and environmental significance.

[0003] At present, the traditional wet recovery process is widely used in experimental research and industrial production due to its low energy consumption and high recovery rate. Typical wet recovery leaching systems include acid leaching and ammonia leaching. In acid leaching, valuable metals and impurities are leached into the solution, resulting in a long subsequent solution purification and product preparation process, and the generation of salt-containing wastewater and harmful waste residue. In contrast, the ammonia leaching system has the characteristic of selectivity. In ammonia leaching, nickel, cobalt and lithium are selectively leached into the solution, while iron, magnesium, manganese and calcium impurities do not react with ammonia and enter the slag, greatly reducing the subsequent purification process. After ammonia leaching, how to prepare high-value-added products from the ammonia solution is the key. In the ammonia leaching solution, cobalt is complexed with ammonia and is not easy to be recovered. Usually, a reducing agent and a sulfidizing agent are added to recover cobalt in the form of cobalt sulfide, and then the cobalt sulfate product is prepared through acid dissolution, extraction and other processes, which has a long process and consumes expensive acid and reducing agent. For the recovery of nickel and lithium in the ammonia solution, the typical chemical precipitation method has the problems of low metal recovery rate and the inability to recycle ammonia.

[0004] In the prior art, the recovery of valuable metals from ammonia-containing solutions containing recoverable metals usually faces the problems of long recovery process, high-salt wastewater generation, and the need to strictly control the pH of the system.

[0005] Therefore, it is of great significance to develop a more effective and sustainable method for recovering nickel, cobalt and lithium from ammonia solution for the resource utilization of waste batteries and the development of ammonia leaching technology. SUMMARY

[0006] In view of the problems of long process, low recovery rate, salt-containing wastewater generation, and the inability to recycle ammonia in the prior art, the present application provides a new recovery method. The method can simply and efficiently recover nickel, cobalt and lithium from the ammonia solution, obtain high-value-added nickel sulfate and lithium cobaltate products, and realize the closed-loop recycling of ammonia without waste liquid generation.

[0007] A method for recovering valuable metals from an ammonia solution containing nickel, cobalt and lithium, comprising:

[0008] Step S1, an organic phase is formed by a chelating extractant and a kerosene diluent, and an ammonia solution containing nickel, cobalt and lithium is a first aqueous phase, solvent extraction is performed on the first aqueous phase by the organic phase, and a nickel-containing loaded organic phase and a lithium and cobalt-containing raffinate are obtained;

[0009] Step S2, after washing ammonia from the loaded organic phase with a first dilute sulfuric acid having a pH of 4-5, the loaded organic phase is back-extracted with a second dilute sulfuric acid, the second aqueous phase obtained by back-extraction is evaporated and crystallized to obtain a nickel sulfate product, and the organic phase after back-extraction is returned to solvent extraction;

[0010] Step S3, the lithium and cobalt-containing raffinate is heated to evaporate ammonia, after evaporating a certain volume, solid-liquid separation is performed, a lithium and cobalt-containing ammonia evaporation precipitate and an ammonia evaporation after-liquid are obtained, the ammonia evaporation after-liquid and ammonia are recovered and used for ammonia leaching of waste materials containing lithium, nickel and cobalt, a lithium source or a cobalt source is added to the ammonia evaporation precipitate and mixed, the molar ratio of lithium to cobalt in the ammonia evaporation precipitate is adjusted to 1, and then calcination is performed to obtain a lithium cobaltate positive electrode material.

[0011] Optionally, in step S1, the ammonia solution has a nickel concentration > 0 g / L, a cobalt concentration ≥ 1.5 g / L, and a lithium concentration ≥ 1.0 g / L. In the ammonia solution, nickel can exist as long as it exists, and the amount of nickel concentration will not affect extraction and back-extraction. However, if the concentrations of cobalt and lithium do not meet the requirements, their precipitation rates will decrease during the ammonia evaporation process.

[0012] Optionally, in step S1, the ammonia solution refers to an ammonia solution generated by an ammonia leaching reaction of a mixed material of waste nickel-cobalt-manganese or nickel-cobalt-aluminum or lithium nickelate and cobalt lithiumate with an ammonia-ammonium salt mixed solution; preferably, the mixed material is a mixed material formed by waste batteries; and the ammonia-ammonium salt mixed solution refers to an ammonia-ammonium carbonate or ammonia-ammonium bicarbonate mixed solution.

[0013] Optionally, in step S1, the chelating extractant is selected from Mextral 54-100, and the kerosene is selected from sulfonated kerosene. Mextral 54-100 mainly contains β-diketone, and has the advantages of fast phase separation, high loading capacity and no need for saponification for the extraction of valuable metals in the ammonia system.

[0014] Optionally, in step S1, the volume fraction of the extractant in the organic phase is 20%-30%, the volume ratio of the organic phase to the first aqueous phase is 2:1-4:1, and the extraction time is 2 min-8 min.

[0015] Optionally, in step S2, the volume ratio of the loaded organic phase to the first dilute sulfuric acid during ammonia washing is 1:1-2:1, the washing time is 3 min-7 min, and the washing stage is 2 stages. Under this condition, ammonia co-extraction can be removed as much as possible, and nickel back-extraction can be avoided.

[0016] Optionally, in step S2, the volume ratio of the loaded organic phase to the second dilute sulfuric acid is 1:2-1:1, the concentration of the second dilute sulfuric acid is 10 g / L-20 g / L, and the stripping time is 4 min-8 min. When the concentration of the sulfuric acid is lower, the single-stage stripping rate of nickel decreases. When the concentration of the sulfuric acid is higher, the extraction rate of nickel does not increase significantly, but the consumption of sulfuric acid increases.

[0017] Optionally, in step S3, when the ammonia evaporation process is carried out under negative pressure, the solution temperature is higher than 60 DEG C; when the ammonia evaporation process is carried out under normal pressure, the solution temperature is higher than 90 DEG C; and the evaporation volume in the ammonia evaporation process is more than 30% of the initial volume of the solution.

[0018] Optionally, in step S3, the lithium source is selected from one or more of lithium carbonate and lithium hydroxide, and the cobalt source is selected from one or more of cobalt carbonate, cobalt tetroxide and cobalt oxalate.

[0019] Optionally, in step S3, the calcination process adopts two-stage calcination, the first-stage calcination temperature is 300 DEG C-500 DEG C, the calcination time is 3 h-10 h, the second-stage calcination temperature is 800 DEG C-900 DEG C, and the calcination time is 6 h-8 h. In the ammonia evaporation precipitation, cobalt exists in the form of carbonate, and the decomposition temperature is 300 DEG C-500 DEG C; lithium exists in the form of lithium carbonate, and the reaction process is that cobalt carbonate is first decomposed into cobalt tetroxide at low temperature, and then the decomposed cobalt tetroxide reacts with lithium carbonate at high temperature to form lithium cobalt oxide. The two-stage calcination can first make the cobalt carbonate fully decomposed into cobalt tetroxide at low temperature, and then the decomposed cobalt tetroxide reacts with lithium carbonate at high temperature, so that the decomposition and synthesis processes are more sufficient. If one-stage calcination is directly adopted, the decomposition and synthesis reactions directly occur at a higher temperature, a longer calcination time is required, the energy consumption is high, and agglomeration occurs between the calcination products, so that the product with clear boundaries cannot be obtained.

[0020] The technical scheme provided by the present application has at least the following beneficial effects:

[0021] In the present application, the nickel with slightly poor ammonia complexing ability is first selectively separated and recovered by using solvent extraction to obtain a nickel sulfate product. The lithium in the raffinate and the cobalt with strong ammonia complexing ability are directly subjected to ammonia evaporation to destroy the structure of the cobalt ammonia complex. In this process, a large amount of ammonia and water are volatilized, and the cobalt and lithium are precipitated from the solution together. Moreover, the evaporated ammonia and the liquid after ammonia evaporation can be recycled. In the ammonia evaporation precipitation, the lithium and the cobalt are uniformly mixed, the lithium and cobalt molar ratio in the ammonia evaporation precipitation is adjusted to 1 by mixing the ammonia evaporation precipitation with a small amount of cobalt source or lithium source, and lithium cobalt oxide positive electrode material can be directly prepared after calcination.

[0022] The present application has the advantages of simple process, short flow, high metal recovery rate, no need of saponification in the extraction process, no need of solution pH control in the ammonia evaporation process, and recycling of the ammonia evaporation solution and evaporated ammonia. Lithium and cobalt are precipitated simultaneously and mixed uniformly in the ammonia evaporation precipitation, which overcomes the problem of uneven mixing of lithium source and cobalt source in the solid-phase synthesis of lithium cobaltate. In addition, the present application can be applied to other ammonia leaching solutions containing nickel, cobalt and lithium, and provides technical support for the separation and cooperative recovery of multiple metals in ammonia system. BRIEF DESCRIPTION OF DRAWINGS

[0023] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative effort based on these drawings.

[0024] Figure 1 The process flow chart of the present application;

[0025] Figure 2 The phase analysis diagram of the lithium cobaltate product obtained in Example 1 of the present application;

[0026] Figure 3 The morphology diagram of the lithium cobaltate product obtained in Example 1 of the present application. DETAILED DESCRIPTION

[0027] In order to make the purpose, technical solutions and advantages of the present application more clear, the technical solutions of the present application will be described in detail below in combination with the drawings and specific embodiments.

[0028] Example 1

[0029] Mextral 54-100 was dissolved in sulfonated kerosene to prepare an extractant with a volume fraction of 20%. The ammonia-ammonium carbonate leaching solution (Li: 2.3 g / L, Ni: 10.9 g / L, Co: 5.5 g / L) of waste nickel-cobalt-manganese materials was subjected to solvent extraction under the condition of a volume ratio of organic phase to aqueous phase of 2:1, and the extraction time was 5 min. The extraction rate of nickel was 99.32%, and the extraction rates of lithium and cobalt were 0.64% and 0.35%, respectively. Then, the loaded organic phase was washed with sulfuric acid at pH = 4, and the washing time was 3 min. The volume ratio of organic phase to aqueous phase was 2:1. After two-stage washing, ammonia was completely washed out, and nickel was not lost. Then, 10 g / L of dilute sulfuric acid solution was used for stripping, and the stripping time was 4 min. The volume ratio of organic phase to aqueous phase was 1:1. The stripping rate of nickel was 99.6%. The nickel sulfate product was obtained by evaporating and crystallizing the stripping solution. The nickel content in the obtained nickel sulfate product was 22.13%, the cobalt content was 0.0039%, the lithium content was 0.0003%, and the manganese content was 0.0021%. Then, the raffinate was subjected to atmospheric ammonia evaporation, and the evaporation temperature was 90°C. The evaporation volume was 40% of the initial solution volume. The precipitation rate of cobalt reached 93.6%, and the precipitation rate of lithium reached 70%. The mixture of ammonia evaporation precipitation and a small amount of cobalt carbonate made the molar ratio of lithium to cobalt in the precipitate be 1. Then, the lithium cobalt oxide product was obtained by first calcining at 300°C for 3 h and then calcining at 800°C for 6 h. The phase analysis of the product is shown in Figure 2 , the product is high-purity lithium cobalt oxide. The morphology of the product is shown in Figure 3 . The obtained product presents a clear boundary of accumulated block shape. The cobalt content in the prepared lithium cobalt oxide material is 59.5%, the lithium content is 7.41%, the nickel content is 0.0026%, and the manganese content is 0.0032%.

[0030] Example 2

[0031] The Mextral 54-100 was dissolved in sulfonated kerosene to prepare an extractant with a volume fraction of 30%. The ammonia-ammonium carbonate leaching solution (Li: 4.3 g / L, Ni: 25.9 g / L, Co: 10.5 g / L) of the waste nickel-cobalt-aluminum material was subjected to solvent extraction under the condition of an organic phase to water phase volume ratio of 3:1. After 2 min of extraction, the nickel extraction rate was 99.32%, and the lithium and cobalt extraction rates were 0.21% and 0.94%, respectively. Then, the loaded organic phase was washed with sulfuric acid at pH = 5. The washing time was 5 min, and the organic phase to water phase volume ratio was 1:1. After two-stage washing, the ammonia was completely washed out, and the nickel was not lost. Then, 15 g / L of dilute sulfuric acid solution was used for stripping. The stripping time was 5 min, and the organic phase to water phase volume ratio was 1:2. The nickel stripping rate was 99.6%. The stripping solution was subjected to evaporation crystallization to obtain a nickel sulfate product. The nickel content in the obtained nickel sulfate product was 21.98%, the cobalt content was 0.0038%, the lithium content was 0.0001%, and the aluminum content was 0.0017%. Then, the raffinate was subjected to atmospheric ammonia evaporation. The ammonia evaporation temperature was 100°C, and the evaporation volume was 30% of the initial solution volume. The cobalt precipitation rate reached 98.6%, and the lithium precipitation rate reached 54%. The mixed ammonia evaporation precipitation and a small amount of lithium carbonate were used to adjust the molar ratio of lithium to cobalt in the precipitation to 1. Then, the lithium cobalt oxide product was obtained by first calcining at 500°C for 10 h and then calcining at 900°C for 8 h. The cobalt content in the prepared lithium cobalt oxide material was 60.01%, the lithium content was 7.18%, the nickel content was 0.0079%, and the aluminum content was 0.0057%.

[0032] Example 3

[0033] The Mextral 54-100 was dissolved in sulfonated kerosene to prepare an extractant with a volume fraction of 30%. The ammonia-ammonium carbonate leaching solution (Li: 4.3 g / L, Ni: 25.9 g / L, Co: 10.5 g / L) of the waste lithium nickelate and lithium cobaltate mixture was subjected to solvent extraction under the condition of an organic phase to water phase volume ratio of 3:1. After 8 min of extraction, the nickel extraction rate was 99.32%, and the lithium and cobalt extraction rates were 0.21% and 0.94%, respectively. Then, the loaded organic phase was washed with sulfuric acid at pH = 5. The washing time was 7 min, and the organic phase to water phase volume ratio was 1:1. After two-stage washing, the ammonia was completely washed out, and the nickel was not lost. Then, 15 g / L of dilute sulfuric acid solution was used for stripping. The stripping time was 8 min, and the organic phase to water phase volume ratio was 1:2. The nickel stripping rate was 99.6%. The nickel sulfate product was obtained by evaporating and crystallizing the stripping solution. The nickel content of the obtained nickel sulfate product was 21.86%, the cobalt content was 0.0094%, the lithium content was 0.0006%, and the aluminum content was 0.0037%. Then, the raffinate was subjected to negative pressure ammonia evaporation. The pressure in the extraction device was -0.02 Mpa by vacuum pump extraction, the ammonia evaporation temperature was 70°C, and the evaporation volume was 30% of the initial solution volume. The cobalt precipitation rate reached 98.6%, and the lithium precipitation rate reached 54%. The mixed ammonia evaporation and precipitation and a small amount of lithium hydroxide were used to adjust the molar ratio of lithium to cobalt in the precipitate to 1. Then, the lithium cobaltate product was obtained by first calcining at 500°C for 10 h and then calcining at 900°C for 8 h. The cobalt content of the prepared lithium cobaltate material was 59.38%, the lithium content was 7.09%, the nickel content was 0.0031%, and the aluminum content was 0.0041%.

[0034] Example 4

[0035] The Mextral 54-100 is dissolved in sulfonated kerosene to prepare an extractant with a volume fraction of 25%. Under the condition of a volume ratio of organic phase to water phase of 4:1, solvent extraction is performed on the ammonia-ammonium bicarbonate leaching solution (Li: 6.7 g / L, Ni: 25.9 g / L, Co: 10.5 g / L) of waste nickel-cobalt-manganese material. After 4 min of extraction, the extraction rate of nickel is 99.32%, and the extraction rates of lithium and cobalt are 1.02% and 0.34%, respectively. Then, the loaded organic phase is washed with sulfuric acid at pH = 4. The washing time is 3 min, and the volume ratio of organic phase to water phase is 2:1. After two-stage washing, ammonia is completely washed out, and nickel is not lost. Stripping is performed using a dilute sulfuric acid solution of 20 g / L. The stripping time is 5 min, and the volume ratio of organic phase to water phase is 1:1 during stripping. The stripping rate of nickel is 99.6%. The nickel sulfate product is obtained by evaporation and crystallization of the stripping solution. The nickel content of the obtained nickel sulfate product is 22.06%, the cobalt content is 0.0062%, the lithium content is 0.0007%, and the manganese content is 0.0038%. Then, the raffinate is subjected to negative pressure ammonia evaporation. The pressure in the extraction device is -0.02 Mpa by means of a vacuum pump extraction device. The ammonia evaporation temperature is 60°C. The evaporation volume is 50% of the initial solution volume. The cobalt precipitation rate reaches 93.6%, and the lithium precipitation rate reaches 80%. The molar ratio of lithium to cobalt in the mixed ammonia evaporation precipitation and a small amount of cobalt tetraoxide is adjusted to 1. Then, the lithium cobaltate product is obtained by first calcining at 300°C for 3 h and then calcining at 800°C for 6 h. The cobalt content of the prepared lithium cobaltate material is 59.84%, the lithium content is 7.23%, the nickel content is 0.0048%, and the manganese content is 0.0033%.

[0036] Comparative Example 1

[0037] M eXtral 54-100 was dissolved in sulfonated kerosene to prepare an extractant with a volume fraction of 20%, and under the condition of a volume ratio of organic phase to aqueous phase of 2:1, solvent extraction was performed on the ammonia-ammonium carbonate leaching solution (Li: 0.5 g / L, Ni: 0.9 g / L, Co: 1.0 g / L) of waste nickel-cobalt-manganese materials. After 2 min of extraction, the nickel extraction rate was 99.01%, and the lithium and cobalt extraction rates were 0.12% and 0.31%, respectively. Then, the loaded organic phase was washed with sulfuric acid at pH = 5, the washing time was 5 min, the volume ratio of organic phase to aqueous phase was 1:1, after two-stage washing, ammonia was completely washed out, and nickel was not lost, and then 15 g / L of dilute sulfuric acid solution was used for stripping, the stripping time was 5 min, the volume ratio of organic phase to aqueous phase was 1:2, the nickel stripping rate was 99.07%, and the stripping solution was evaporated and crystallized to obtain nickel sulfate product, the nickel content in the obtained nickel sulfate product was 21.98%, the cobalt content was 0.0028%, the lithium content was 0.0001%, and the manganese content was 0.0015%. Then, atmospheric ammonia evaporation was performed on the raffinate, the ammonia evaporation temperature was 110°C, the evaporation volume was 30% of the initial solution volume, the cobalt precipitation rate was 49.16%, and the lithium precipitation rate was 28.6%. It can be seen that when the nickel concentration in the ammonia solution is low, it will not affect the extraction rate and stripping rate, and when the cobalt and lithium concentrations are low, the precipitation rate will be greatly reduced during ammonia evaporation.

[0038] Comparative Example 2

[0039] Mextral 54-100 was dissolved in sulfonated kerosene to prepare an extractant with a volume fraction of 10%, and under the condition of a volume ratio of organic phase to aqueous phase of 2:1, solvent extraction was performed on the leaching solution in Example 1, after 2 min of extraction, the nickel extraction rate was 68.79%, and the lithium and cobalt extraction rates were 0.14% and 0.24%, respectively. It can be seen that when the extractant concentration is low, the extraction rate will be greatly reduced.

[0040] Comparative Example 3

[0041] The loaded organic phase after washing in Example 2 was stripped with 5.5 g / L of dilute sulfuric acid to strip nickel, under the condition of a stripping time of 5 min and a volume ratio of organic phase to aqueous phase of 1:2, the nickel stripping rate was 40.37%, the stripping solution was evaporated and crystallized to obtain nickel sulfate product, the nickel content in the obtained nickel sulfate product was 21.80%, the cobalt content was 0.0091%, the lithium content was 0.0005%, and the aluminum content was 0.0039%. It can be seen that when the sulfuric acid concentration for stripping is low, the stripping rate will be greatly reduced.

[0042] Comparative Example 4

[0043] The raffinate in Example 1 was subjected to atmospheric evaporation of ammonia, and when the evaporation temperature was 80°C and the evaporation volume was 30% of the initial solution volume, the cobalt precipitation rate was 46.3% and the lithium precipitation rate was 35%. Thus, when the atmospheric evaporation temperature is lower than 90°C, the cobalt and lithium precipitation rates will be reduced.

[0044] Comparative Example 5

[0045] The raffinate in Example 2 was subjected to atmospheric evaporation of ammonia, and when the evaporation temperature was 90°C and the evaporation volume was 20% of the initial solution volume, the cobalt precipitation rate was 38.7% and the lithium precipitation rate was 26%. Thus, when the evaporation volume is lower than 30%, the cobalt and lithium precipitation rates will be reduced.

[0046] Comparative Example 6

[0047] The raffinate in Example 3 was subjected to negative pressure evaporation of ammonia, and the pressure in the device was -0.02 MPa by means of a vacuum pump, the evaporation temperature was 50°C and the evaporation volume was 30% of the initial solution volume, the cobalt precipitation rate was 56.1% and the lithium precipitation rate was 37.5%. Thus, when the negative pressure evaporation temperature is lower than 60°C, the cobalt and lithium precipitation rates will be reduced.

[0048] The above is merely a specific embodiment of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical scope disclosed by the present application, which should be encompassed in the protection scope of the present application. Thus, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A process for the recovery of valuable metals from an ammoniacal solution containing nickel, cobalt, lithium, characterized in that, The application relates to a preparation method of a lithium cobaltate positive electrode material. The method comprises the following steps: S1, forming an organic phase by using a chelating extractant and a kerosene diluent, and using an ammonia solution containing nickel, cobalt and lithium as a first aqueous phase, and performing solvent extraction on the first aqueous phase by using the organic phase, so as to obtain a loaded organic phase containing nickel and a raffinate containing lithium and cobalt; the chelating extractant is selected from Mextral 54-100, and the kerosene is selected from sulfonated kerosene; S2, washing ammonia in the loaded organic phase by using first dilute sulfuric acid with pH=4-5, and then performing back extraction on the loaded organic phase by using second dilute sulfuric acid with a concentration of 10g / L-20g / L; the second aqueous phase obtained through back extraction is subjected to evaporation crystallization to obtain a nickel sulfate product, and the organic phase after back extraction is returned to solvent extraction; S3, heating and evaporating ammonia in the raffinate containing lithium and cobalt, and then performing solid-liquid separation after evaporating a certain volume, so as to obtain an ammonia evaporation precipitate containing lithium and cobalt and an ammonia evaporation solution, and the ammonia evaporation solution and ammonia are recovered and used for ammonia leaching of waste materials containing lithium, nickel and cobalt; a lithium source or a cobalt source is added into the ammonia evaporation precipitate and mixed, the molar ratio of lithium to cobalt in the ammonia evaporation precipitate is adjusted to 1, and then the ammonia evaporation precipitate is calcined, so as to obtain the lithium cobaltate positive electrode material; The calcination process adopts two-stage calcination, the first-stage calcination temperature is 300-500 DEG C, the first-stage calcination time is 3-10h, the second-stage calcination temperature is 800-900 DEG C, and the second-stage calcination time is 6-8h.

2. The method of claim 1, wherein, In step S1, the ammonia solution contains nickel with a concentration of more than 0g / L, cobalt with a concentration of more than or equal to 1.5g / L, and lithium with a concentration of more than or equal to 1.0g / L.

3. The method of claim 1, wherein, In step S1, the ammonia solution is an ammonia solution generated through ammonia leaching of waste nickel-cobalt-manganese or nickel-cobalt-aluminum or mixed materials of lithium nickelate and lithium cobaltate, and an ammonia-ammonium salt mixed solution; the ammonia-ammonium salt mixed solution is an ammonia-ammonium carbonate mixed solution or an ammonia-ammonium bicarbonate mixed solution.

4. The method of claim 1, wherein, In step S1, the volume fraction of the extractant in the organic phase is 20%-30%, the volume ratio of the organic phase to the first aqueous phase is 2:1-4:1, and the extraction time is 2-8min.

5. The method of claim 1, wherein, In step S2, the volume ratio of the loaded organic phase to the first dilute sulfuric acid is 1:1-2:1 during ammonia washing, the washing time is 3-7min, and the washing stage number is 2.

6. The method of claim 1, wherein, In step S2, the volume ratio of the loaded organic phase to the second dilute sulfuric acid is 1:2-1:1 during back extraction, and the back extraction time is 4-8min.

7. The method of claim 1, wherein, In step S3, the solution temperature is higher than 60 DEG C when the ammonia evaporation process is performed under negative pressure, the solution temperature is higher than 90 DEG C when the ammonia evaporation process is performed under normal pressure, and the evaporation volume in the ammonia evaporation process is more than 30% of the initial volume of the solution.

8. The method of claim 1, wherein, In step S3, the lithium source is selected from one or more of lithium carbonate and lithium hydroxide, and the cobalt source is selected from one or more of cobalt carbonate, cobalt tetroxide and cobalt oxalate.

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