Method for dissolving and separating lithium battery black powder

Abstract

The present disclosure provides a method for dissolving and separating lithium battery black powder. A method for dissolving and separating lithium battery black powder, characterized in that the separation method comprises the following steps: S1, a molten salt comprising NaF-AlF3 base or KF-AlF3 base or NaF-KF-AlF3 base is placed in a graphite crucible, the graphite crucible is placed in a high-temperature resistance furnace as a whole, and the molten salt is melted by heating; S2, the lithium battery black powder is pressed into a sheet shape and added into the graphite crucible in S1 in batches to react with the molten salt; S3, the graphite crucible is disassembled to obtain white molten salt and black precipitate and separate them; S4, the black precipitate in S3 is dissolved with an aluminum salt solution, and the dissolved solution is filtered, washed and dried to obtain a mixture dry powder of Ni, Mn and Co oxides, so as to realize the separation of Ni, Co and Mn in the black powder components.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to the technical field of lithium battery recycling, in particular to a method for dissolving and separating lithium battery black powder. BACKGROUND

[0002] With the rapid development of new energy industry, the use of lithium batteries is showing a sharp increase trend, and the number of waste lithium batteries is also rising. The recycling of waste lithium batteries has become an urgent and important task.

[0003] The lithium batteries meeting the scrapping standard are sequentially discharged, disassembled, crushed and sorted to obtain lithium battery black powder. The lithium battery black powder, as a key intermediate product of waste lithium battery recycling, is the main raw material for subsequent harmless treatment and valuable resource recovery. The lithium battery black powder is a black or gray-black powder composed of one or more metal elements such as lithium, nickel, cobalt, manganese, iron and phosphorus, and is an intermediate product obtained after pretreatment of waste lithium batteries.

[0004] The current black powder treatment method is mainly based on fire method and wet method. The fire method recovery utilizes high temperature to remove organic matter in lithium batteries, and simultaneously reduces the valuable metals. Although the fire method treatment process is simple, a large amount of harmful gas and dust is usually generated in the process, which causes serious harm to the environment and human health. The wet method recovery process selectively extracts metal elements in lithium battery black powder through chemical reaction with a solvent, including using precipitation method or solvent extraction method, etc. to separate the dissolved metal components. The advantage of the wet method for treating lithium battery black powder is high extraction efficiency, and the disadvantages are long process, large amount of waste liquid and great harm of waste liquid. SUMMARY

[0005] One of the technical problems to be solved by the present disclosure is that the existing fire method for treating black powder generates a large amount of harmful gas and dust, which pollutes a lot, and the wet method generates a large amount of waste liquid, which is complicated.

[0006] To solve the above technical problems, the present disclosure provides a method for dissolving and separating lithium battery black powder, which comprises:

[0007] S1, a molten salt comprising NaF-AlF3 base or KF-AlF3 base or NaF-KF-AlF3 base is contained in a graphite crucible, the whole graphite crucible is placed in a high-temperature resistance furnace, and the molten salt is melted by heating;

[0008] S2, the lithium battery black powder is pressed into a sheet shape and added into the graphite crucible in S1 in batches to react with the molten salt;

[0009] S3, the graphite crucible is disassembled to obtain white molten salt and black precipitate and separate them;

[0010] S4, dissolving the black precipitate in S3 with an aluminum salt solution, filtering, washing and drying the solution to obtain a dry powder of a mixture of Ni, Mn, Co oxides.

[0011] In some embodiments, the method for dissolving and separating lithium battery black powder as described above, wherein the molar ratio of NaF to AlF3 in the molten salt in S1 is 1.0-3.0 when the molten salt in S1 only includes NaF-AlF3.

[0012] In some embodiments, the method for dissolving and separating lithium battery black powder as described above, wherein the molar ratio of KF to AlF3 in the molten salt in S1 is 1.0-3.0 when the molten salt in S1 only includes KF-AlF3.

[0013] In some embodiments, the method for dissolving and separating lithium battery black powder as described above, wherein the molar ratio of NaF+KF to AlF3 in the molten salt in S1 is 1.0-3.0 when the molten salt in S1 only includes NaF-KF-AlF3.

[0014] In some embodiments, the method for dissolving and separating lithium battery black powder as described above, wherein the aluminum salt solution in S4 is one of aluminum chloride solution, aluminum sulfate solution or aluminum nitrate solution.

[0015] In some embodiments, the method for dissolving and separating lithium battery black powder as described above, wherein the density of the black powder in S2 is greater than the density of the molten salt to sufficiently react with the molten salt.

[0016] In some embodiments, the method for dissolving and separating lithium battery black powder as described above, wherein the density of the black powder is 2.2-3 g / cm 3 .

[0017] In some embodiments, the method for dissolving and separating lithium battery black powder as described above, wherein MgF2 can be added to the black powder in S1 to reduce the viscosity of the molten salt and improve the separation performance of the molten salt from C in the black powder; CaF2 can also be added to the black powder to reduce the melting temperature of the molten salt.

[0018] In some embodiments, the method for dissolving and separating lithium battery black powder as described above, wherein argon gas is introduced into the electric resistance furnace in S1 to prevent oxidation of the graphite crucible.

[0019] In some embodiments, the method for dissolving and separating lithium battery black powder as described above, wherein when the concentration of LiF in the white molten salt in S3 reaches 1%, part of the white molten salt can be collected to extract lithium salt.

[0020] By the technical scheme, the method for dissolving and separating the black powder of the lithium battery provided by the present disclosure can make the Ni, Co and Mn compounds in the black powder change into corresponding oxide precipitates in the molten salt, and then deposit at the bottom of the molten salt, and finally the precipitates can be taken out through slagging and other operations. Thus, the separation of Ni, Co and Mn in the black powder components is realized, without the need to directly reduce the valuable metals in the black powder through high temperature to cause a large amount of harmful gas and dust, and without the need to separate the metal components through solvent extraction to cause a large amount of waste liquid, and meanwhile, the reaction can be continuously carried out according to the output of the precipitates and the addition of the molten salt and the black powder at different stages. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 is a flowchart of the method for dissolving and separating the black powder of the lithium battery disclosed by the present disclosure. DETAILED DESCRIPTION

[0022] In order to further illustrate the technical means and effects adopted by the present disclosure to achieve the predetermined purposes, the following describes the specific implementation, features and effects of the method for dissolving and separating the black powder of the lithium battery according to the present disclosure in combination with the preferred embodiments.

[0023] Embodiment One

[0024] A method for dissolving and separating the black powder of the lithium battery, comprising the following steps

[0025] S1: 400g of molten salt composed of NaF-AlF3 and having a molar ratio of NaF to AlF3 of 2.3 is added to a graphite crucible, and MgF2 and CaF2 are also added at this time, and the composition ratio in the graphite crucible is 49% NaF-41% AlF3-5% MgF2-5% CaF2, and then the graphite crucible is placed in an electric resistance furnace, and argon is introduced to prevent high-temperature oxidation of the graphite crucible, and the target temperature of the electric resistance furnace is controlled to 980°C by an external temperature controller to melt the molten salt;

[0026] S2: 100g of black powder 1 is weighed and tabletted, and is added to the molten salt in batches, and a graphite tongs pot cover is covered for reaction for 4h;

[0027] S3: after the molten salt is cooled, the graphite crucible is disassembled, and the solid substances in the graphite crucible are manually separated to obtain 405g of white molten salt on the upper layer and black precipitates on the lower layer;

[0028] S4: the black precipitates are dissolved with an aluminum salt solution, and the dissolved solution is filtered, washed and dried to obtain 85g of a mixture of Ni, Mn and Co oxide dry powder;

[0029] Finally, the concentrations of Li, Ni, Co, and Mn in the white molten salt are quantitatively analyzed, and the concentrations of Li, Ni, Co, and Mn in the dry powder of the mixture are analyzed, so that the recovery ratio of Li in the upper molten salt and the recovery ratio of Ni, Co, and Mn in the dry powder of the mixture can be obtained, respectively.

[0030] It should be noted that the addition of MgF2 can improve the viscosity of the molten salt and separate C in the black powder, so as to collect more Ni, Co, and Mn in the black powder. CaF2 can reduce the melting temperature of the molten salt. It can be understood that when the molten salt is heated and melted by the resistance furnace, the melting temperature of the molten salt can be reduced, the heating time can be greatly shortened, and the efficiency of the experiment can be improved.

[0031] In this embodiment, only the black powder is added to the molten salt in a molten state for reaction, so that the Ni, Co, and Mn compounds can be converted into corresponding oxides in the molten salt, and then deposited at the bottom of the molten salt. Finally, the precipitate can be taken out by slagging and other operations, the separation of Ni, Co, and Mn in the black powder is completed, no excess harmful gas and dust are generated, and no excess waste liquid is generated. The reaction can continue according to the specific situation of the reaction, and the collection efficiency is ensured.

[0032] Example Two

[0033] A method for dissolving and separating black powder of lithium battery, comprising the following steps:

[0034] S1: 400g of molten salt composed of NaF-AlF3 and having a molar ratio of NaF to AlF3 of 2.3 is added to a graphite crucible, and MgF2 and CaF2 are also added. At this time, the composition ratio in the graphite crucible is 49% NaF-41% AlF3-5% MgF2-5% CaF2. Then, the graphite crucible is placed in an electric resistance furnace, and argon is introduced to prevent the graphite crucible from being oxidized at high temperature. The target temperature of the electric resistance furnace is controlled to 980°C by an external temperature controller to melt the molten salt.

[0035] S2: 100g of black powder 2 is weighed and tabletted, and then added to the molten salt in batches, and the graphite tongs pot cover is covered for reaction for 4h.

[0036] S3: After the molten salt is cooled, the graphite crucible is disassembled, and the solid material in the graphite crucible is manually separated to obtain 395g of white molten salt in the upper layer and black precipitate in the lower layer.

[0037] S4: The black precipitate is dissolved with an aluminum salt solution, and the dissolved solution is filtered, washed, and dried to obtain 90g of a mixture of Ni, Mn, and Co oxides in dry powder form.

[0038] Finally, quantitative analysis of the concentrations of Li, Ni, Co, and Mn in the white molten salt and analysis of the concentrations of Li, Ni, Co, and Mn in the dry powder mixture are performed to obtain the recovery ratios of Li in the upper layer of molten salt and Ni, Co, and Mn in the dry powder mixture, respectively.

[0039] In this embodiment, the black powder is added to the molten salt in a molten state to react, so that the Ni, Co, and Mn compounds in the molten salt are converted into corresponding oxides, which are then deposited at the bottom of the molten salt. Finally, the precipitates are removed by slagging and other operations, thereby separating Ni, Co, and Mn in the black powder. No excess harmful gas and dust are generated, and no excess waste liquid is generated. The reaction can be continuously performed by adding molten salt and black powder according to the specific conditions of the reaction, thereby ensuring the collection efficiency.

[0040] Embodiment Three

[0041] A method for dissolving and separating black powder of lithium batteries, comprising the following steps:

[0042] S1: 400g of molten salt composed of NaF-KF-AlF3 and having a molar ratio of NaF+KF to AlF3 of 1.1 is added to a graphite crucible, and MgF2 and CaF2 are also added. At this time, the composition ratio in the graphite crucible is 44% NaF-5% KF-36% AlF3-5% MgF2-5% CaF2-5% Al2O3. Then, the graphite crucible is placed in an electric resistance furnace, and argon is introduced to prevent the graphite crucible from being oxidized at high temperature. The target temperature of the electric resistance furnace is controlled to 940°C by an external temperature controller to melt the molten salt.

[0043] S2: 100g of black powder 2 is weighed and tabletted, and then added to the molten salt in batches. The graphite crucible is covered with a graphite tongs cover and reacted for 4h.

[0044] S3: After the molten salt is cooled, the graphite crucible is disassembled, and the solid material in the graphite crucible is manually separated to obtain 396g of white molten salt in the upper layer and black precipitates in the lower layer.

[0045] S4: The black precipitates are dissolved in an aluminum salt solution, and the dissolved solution is filtered, washed, and dried to obtain 90g of a mixture of Ni, Mn, and Co oxides in dry powder form.

[0046] Finally, quantitative analysis of the concentrations of Li, Ni, Co, and Mn in the white molten salt and analysis of the concentrations of Li, Ni, Co, and Mn in the dry powder mixture are performed to obtain the recovery ratios of Li in the upper layer of molten salt and Ni, Co, and Mn in the dry powder mixture, respectively.

[0047] It should be noted that: in this embodiment, Al2O3 is gradually generated from AlF3 in the molten salt as the reaction proceeds under high temperature environment, and Al2O3 can reduce the liquidus temperature of the molten salt to better realize the phase change from liquid to solid, which is conducive to the experiment.

[0048] In this embodiment, only by adding black powder to the molten salt in a molten state to react, the Ni, Co and Mn compounds in the molten salt can be converted into corresponding oxide precipitates, and then deposited at the bottom of the molten salt. Finally, through the operation of slagging, the precipitates can be taken out, the separation of Ni, Co and Mn in the black powder is completed, no excess harmful gas and dust are produced, and no excess waste liquid is produced. The reaction can continue according to the specific situation of the reaction to ensure the collection efficiency.

[0049] Example Four

[0050] A method for dissolving and separating black powder of lithium battery, comprising the following steps:

[0051] S1: 400g of molten salt composed of KF-AlF3 and having a molar ratio of KF-AlF3 of 1.95 is added to a graphite crucible, and MgF2 and CaF2 are also added. At this time, the composition ratio in the graphite crucible is 54% KF-40% AlF3-3% MgF2-3% CaF2. Then the graphite crucible is placed in an electric resistance furnace, and argon is introduced to prevent high-temperature oxidation of the graphite crucible. The target temperature of the electric resistance furnace is controlled to 950℃ by an external temperature controller to melt the molten salt;

[0052] S2: 100g of black powder 2 is weighed and tabletted, and then added to the molten salt in batches, and the graphite tongs pot cover is covered for reaction for 4h;

[0053] S3: After the molten salt is cooled, the graphite crucible is disassembled, and the solid substances in the graphite crucible are manually separated to obtain 394g of white molten salt on the upper layer and black precipitate on the lower layer;

[0054] S4: The black precipitate is dissolved with an aluminum salt solution, and the dissolved solution is filtered, washed and dried to obtain a mixture of Ni, Mn and Co oxide dry powder with a mass of 91g;

[0055] Finally, the concentrations of Li, Ni, Co and Mn elements in the white molten salt are quantitatively analyzed, and the concentrations of Li, Ni, Co and Mn elements in the mixture dry powder are analyzed, so as to obtain the recovery ratio of Li in the upper layer molten salt and the recovery ratio of Ni, Co and Mn in the mixture dry powder, respectively.

[0056] The embodiment only needs to add the black powder into the molten salt in a molten state to react, so that the Ni, Co and Mn compounds in the molten salt are converted into corresponding oxides precipitates, and then deposited at the bottom of the molten salt. Finally, through the operation of slagging, the precipitates can be taken out, the separation of Ni, Co and Mn in the black powder is completed, no excess harmful gas and dust are produced, and no excess waste liquid is produced. The reaction can be continuously carried out according to the specific situation of the reaction, and the collection efficiency is ensured.

[0057] In the experiment, two kinds of battery black powder were used, namely black powder 1 and black powder 2. The chemical compositions of the two kinds of black powder are listed in Tables 1 and 2 below.

[0058] Table 1 Chemical composition analysis results of black powder 1

[0059]

[0060] Table 2 Chemical composition analysis results of black powder 2

[0061]

[0062] It should be noted that the above two kinds of black powder are commonly used in the art, and black powder with the above composition ratio can be directly obtained for separation.

[0063] The recovery ratios of Ni, Co and Mn in the mixture dry powder in Examples 1-4 are shown in the following table:

[0064]

[0065] In the above Examples 1 to 8, the mass of the molten salt is 400g, the mass of the black powder is 100g, and the reaction time is 4h. At the same time, the specific experimental steps of Example Four and Example Eight are the same as those of Example One, and the specific experimental steps of Example One can be referred to.

[0066] From the comparison of Example One and Example Two, it can be seen that the molten salt with the composition of Example One has a higher recovery rate of Ni, Co and Mn in black powder 1, and the recovery rate of Co is higher in particular.

[0067] From the comparison of Example One and Example Three, it can be seen that the recovery rates of Ni, Co and Mn in the two examples are basically close, but the target temperature of Example Three is lower than that of Example One. Specifically, the addition of KF base can reduce the melting temperature of the molten salt, thereby reducing the melting temperature of the molten salt and reducing the consumption of the energy of the resistance furnace, greatly improving the efficiency of the reaction.

[0068] From the comparison of Example Two and Example Four, it can be seen that the molten salt with the composition of Example Two has a higher recovery rate of Ni, Co and Mn in black powder 2, and the recovery rate of Co is higher in particular.

[0069] Among them, Li can be dissolved in the form of LiF into the molten salt and is in liquid phase, so the recovery rates of the four embodiments for Li are basically close, only when the concentration of LiF is detected to be increased to 1% or more by an external detection device, the LiF can be extracted and collected.

[0070] In summary, by reacting the smut with the molten salt, the Ni, Co and Mn compounds are converted into corresponding oxide precipitates in the molten salt, so that the separation and collection of Ni, Co and Mn can be realized,

[0071] By using NaF-KF-AlF3 as the molten salt material, the recovery rate of Ni in the smut 1 can reach 97%, the recovery rate of Co can reach 91%, and the recovery rate of Mn can reach 98%.

[0072] So far, the embodiments of the present disclosure have been described in detail. In order to avoid obscuring the concept of the present disclosure, some details known in the art are not described. Those skilled in the art can fully understand how to implement the technical solutions disclosed herein according to the above description.

[0073] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art should understand that the above examples are only for illustration, not for limiting the scope of the present disclosure. Those skilled in the art should understand that the above embodiments can be modified or some technical features can be replaced equivalently without departing from the scope and spirit of the present disclosure. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way.

Claims

1. A method for dissolving and separating lithium battery black powder, characterized in that, Includes the following steps: S1, molten salt including NaF-AlF3-based, KF-AlF3-based, or NaF-KF-AlF3-based is placed in a graphite crucible, and the graphite crucible is placed in a high-temperature resistance furnace to melt the molten salt by heating. S2, lithium battery black powder is pressed into sheet form and added in batches to the graphite crucible in S1 to react with molten salt; S3, Disassemble the graphite crucible to obtain and separate white molten salt and black precipitate; S4, dissolve the black precipitate in S3 with the aluminum salt solution, filter, wash and dry the solution to obtain a dry powder of Ni, Mn and Co oxides; The black powder contains MgF2 to reduce the viscosity of the molten salt and improve the separation performance of the molten salt and C in the black powder; the black powder also contains CaF2 to reduce the melting temperature of the molten salt.

2. The method for dissolving and separating lithium battery black powder according to claim 1, characterized in that, When the molten salt in S1 includes only NaF-AlF3-based salts, the molar ratio of NaF to AlF3 is 1.0 to 3.

0.

3. The method for dissolving and separating lithium battery black powder according to claim 1, characterized in that, The molten salt in S1 consists only of KF-AlF3 base, with a molar ratio of KF to AlF3 of 1.0 to 3.

0.

4. The method for dissolving and separating lithium battery black powder according to claim 1, characterized in that, When the molten salt in S1 includes only NaF-KF-AlF3-based salts, the molar ratio of NaF+KF and AlF3 is 1.0~3.

0.

5. The method for dissolving and separating lithium battery black powder according to claim 1, characterized in that, The aluminum salt solution in S4 is one of aluminum chloride solution, aluminum sulfate solution, or aluminum nitrate solution.

6. The method for dissolving and separating lithium battery black powder according to claim 1, characterized in that, The density of the black powder in S2 is greater than that of the molten salt, so as to react fully with the molten salt.

7. The method for dissolving and separating lithium battery black powder according to claim 6, characterized in that, The density of the black powder is 2.2-3 g / cm³. 3 .

8. The method for dissolving and separating lithium battery black powder according to claim 1, characterized in that, Argon gas is introduced into the resistance furnace in S1 to prevent oxidation of the graphite crucible.

9. The method for dissolving and separating lithium battery black powder according to claim 1, characterized in that, When the LiF concentration in the white molten salt in S3 reaches 1%, a portion of the molten salt is collected to extract lithium salt.

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