Method for recovering lithium compound from cathode material waste crucible

Abstract

The present invention relates to a method for recovering a lithium compound from a cathode material waste crucible, the method comprising the steps of: ultrasonically treating the cathode material waste crucible in water or an aqueous solution to generate a lithium compound-containing aqueous solution; separating the lithium compound-containing aqueous solution from the cathode material waste crucible by filtration; and evaporating the lithium compound-containing aqueous solution. Accordingly, lithium compounds can be recovered from the cathode material waste crucible in a simple and eco-friendly manner with high recovery efficiency.

Description

Method for recovering lithium compounds from waste cathode crucibles

[0001] The present invention relates to a method for recovering lithium compounds from waste cathode crucibles, and more particularly, to a method for simply and environmentally friendly recovering lithium compounds from waste cathode crucibles with a high recovery rate.

[0002] With the rapid development of the IT industry, electric vehicles, and energy storage systems (ESS), demand for lithium secondary batteries is increasing. Along with these market trends, demand for cathode materials used in lithium secondary batteries is also growing day by day.

[0003] Typically, cathode materials are manufactured by calcining raw materials such as lithium hydroxide or lithium carbonate with NCM, NCA, or LFP precursors in a reaction crucible. During the high-temperature cathode manufacturing process, the excessive amount of lithium hydroxide or lithium carbonate used erodes, forming Li-Al-O (LiAlO2). Furthermore, during repeated calcination processes, the lithium hydroxide or lithium carbonate components penetrate and diffuse from the surface of the reaction crucible into the interior, forming a Li-Al-O structure throughout the interior.

[0004] LiAlO2, which is formed by the erosion reaction of lithium compounds on the surface of the reaction crucible, causes cracks on the surface of the reaction crucible, which reduces the recovery efficiency after manufacturing the cathode material and shortens its service life.

[0005] Accordingly, the lifespan of the reaction crucible used in the continuous cathode material manufacturing process is approximately 30 days, requiring periodic replacement. Currently, the recycling rate of waste reaction crucibles generated after cathode material manufacturing is still low.

[0006] In addition, LiAlO2, which is produced through the reaction between lithium compounds and a reaction crucible, is an advanced raw material containing lithium, a valuable metal resource, but is being disposed of due to the lack of recycling technology.

[0007] Therefore, there is an urgent need to develop a recycling technology for waste cathode materials.

[0008] Conventional methods for recovering lithium compounds include methods such as crushing or breaking up waste cathode crucibles, then neutralizing them after acid leaching using strong acids such as nitric acid or sulfuric acid, or using high-heat treatment instead of strong acids (Republic of Korea Patent Nos. 10-2540810 and 10-2420751).

[0009] However, the method of using such strong acids requires an additional acid treatment process to solve environmental problems, and it is uneconomical because it requires multiple washing processes as a large amount of intermediate products are generated and act as impurities.

[0010] In addition, the method using high-temperature treatment requires high-temperature equipment, and the manufacturing cost increases due to the input of gas, and not only does it cause environmental problems due to carbon emissions, but it is also inefficient due to high power consumption, and there are problems in that the after-sales management costs increase due to damage to the equipment.

[0011] Therefore, there is a need to develop a method for recovering lithium compounds from waste cathode crucibles in an economical and environmentally friendly manner using a simple process with a high recovery rate.

[0012] One object of the present invention is to provide a method for economically and environmentally recovering lithium compounds from waste cathode material crucibles with a high recovery rate through a simple process.

[0013] On the one hand, the present invention

[0014] (i) a step of ultrasonic treating a cathode waste crucible in water or an aqueous solution to produce an aqueous solution containing a lithium compound;

[0015] (ii) a step of filtering the lithium compound-containing aqueous solution to separate it from the cathode material waste crucible; and

[0016] (iii) A method for recovering a lithium compound from a waste cathode crucible is provided, including a step of evaporating the above lithium compound-containing aqueous solution.

[0017] A method for recovering a lithium compound from a waste cathode crucible according to one embodiment of the present invention may further include, prior to step (i), a step of grinding or crushing the waste cathode crucible.

[0018] In one embodiment of the present invention, the cathode material waste crucible may be a waste reaction vessel used in the manufacture of cathode materials using at least one of lithium hydroxide and lithium carbonate as raw materials.

[0019] In one embodiment of the present invention, the lithium compound may be at least one selected from the group consisting of lithium hydroxide (LiOH), lithium carbonate (Li2CO3), lithium phosphate (Li3PO4), lithium chloride (LiCl), lithium fluoride (LiF), and lithium sulfate (Li2SO4).

[0020] In one embodiment of the present invention, in step (i), the aqueous solution may contain a hydroxide salt, carbonic acid, carbonate, phosphate, phosphoric acid, hydrochloric acid, hydrofluoric acid or sulfuric acid.

[0021] In one embodiment of the present invention, in step (i), the aqueous solution may contain a hydroxide salt, a carbonate salt or a carbonic acid salt.

[0022] In one embodiment of the present invention, the hydroxide salt, carbonate salt and phosphate salt may be a salt of an alkali metal or an alkaline earth metal.

[0023] In one embodiment of the present invention, the hydroxide salt may be at least one selected from the group consisting of Ca(OH)2, Mg(OH)2, NaOH, and KOH.

[0024] In one embodiment of the present invention, the carbonate may be at least one selected from the group consisting of Na2CO3, CaCO3, and K2CO3.

[0025] In one embodiment of the present invention, the phosphate may be at least one selected from the group consisting of Na3PO4, K3PO4, and Ca3(PO4)2.

[0026] In one embodiment of the present invention, in step (i), the ultrasonic treatment is performed at 200 W / m 3 It can be performed with the above output and ultrasonic frequency of 10KHz or higher.

[0027] In one embodiment of the present invention, in step (i), the ultrasonic treatment can be performed at a temperature of 20°C or higher.

[0028] In one embodiment of the present invention, in step (i), the ultrasonic treatment can be performed under stirring.

[0029] The method for recovering a lithium compound from a cathode crucible according to one embodiment of the present invention may further include a step of crystallizing the lithium compound after step (iii).

[0030] A method for recovering a lithium compound from a waste cathode crucible according to one embodiment of the present invention may further include, after step (ii), a step of cleaning and recovering the waste cathode crucible.

[0031] The method for recovering a lithium compound from a spent cathode crucible according to the present invention is to recover a lithium compound economically and environmentally in a simple process by treating the spent cathode crucible with ultrasonic waves in water or an aqueous solution to induce the lithium (Li) element in the spent cathode crucible to react with a component in the water or aqueous solution to produce a lithium compound.

[0032] Hereinafter, the present invention will be described in more detail.

[0033]

[0034] One embodiment of the present invention is a method for recovering a lithium compound from a cathode waste crucible,

[0035] (i) a step of ultrasonic treating a cathode waste crucible in water or an aqueous solution to produce an aqueous solution containing a lithium compound;

[0036] (ii) a step of filtering the lithium compound-containing aqueous solution to separate it from the cathode material waste crucible; and

[0037] (iii) A method comprising a step of evaporating the above lithium compound-containing aqueous solution.

[0038]

[0039] A method for recovering a lithium compound from a spent cathode crucible according to one embodiment of the present invention comprises treating the spent cathode crucible with ultrasonic waves in water or an aqueous solution to induce lithium (Li) element present in the spent cathode crucible, particularly lithium (Li) element penetrating into the interior of the spent cathode crucible, to react with a component in water or an aqueous solution to produce a lithium compound, and then separating and recovering the lithium compound, thereby obtaining a lithium compound economically and environmentally friendly through a simple process.

[0040]

[0041] In one embodiment of the present invention, the cathode material waste crucible refers to a waste reaction vessel used in the manufacture of cathode materials, and may be a waste reaction vessel used in the manufacture of cathode materials using at least one of lithium hydroxide and lithium carbonate as raw materials.

[0042] Specifically, the above-mentioned cathode waste crucible is a waste crucible used for manufacturing cathode materials by calcining at high temperatures at least one of lithium hydroxide and lithium carbonate as raw materials, and may have Al2O3 as its main component. During the high-temperature calcination process, lithium element, among the components contained in the raw materials, primarily penetrates into the interior of the cathode waste crucible and is also combined in the form of lithium oxide on the surface of the waste crucible.

[0043]

[0044] A method for recovering a lithium compound from a waste cathode crucible according to one embodiment of the present invention may further include, prior to step (i), a step of grinding or crushing the waste cathode crucible.

[0045] If a step of grinding or crushing the entire lithium-containing portion of the cathode waste crucible is further included, the recovery rate of the lithium compound can be increased and the process can be performed efficiently.

[0046] The above grinding or pulverization can be performed using a conventional method used in the relevant technical field, for example, a grinder or a cutter mixer can be used.

[0047] The average particle size of the cathode waste crucible powder after the grinding may be 0.01 to 2 mm, and the average particle size of the cathode waste crucible powder after the crushing may be 0.1 to 100 mm, preferably 0.1 to 20 mm. Within the above average particle size range, processes such as ultrasonic treatment and filtration can be efficiently performed while increasing the recovery rate of lithium compounds.

[0048]

[0049] The above step (i) is a step of generating an aqueous solution containing a lithium compound by ultrasonicating a cathode waste crucible in water or an aqueous solution to induce the generation of a lithium compound.

[0050] When the cathode waste crucible is ultrasonically treated in water or an aqueous solution, the lithium (Li) element present in the cathode waste crucible can react with components in the water or aqueous solution to produce a lithium compound.

[0051] Among the components of the cathode crucible, other than lithium, the other components are insoluble in water and thus difficult to react with components in water or aqueous solutions. Furthermore, lithium is physically permeable, making it easy to react with water or aqueous solutions. Consequently, high-purity lithium compounds can be produced.

[0052]

[0053] The above lithium compound may be at least one selected from the group consisting of lithium hydroxide (LiOH), lithium carbonate (Li2CO3), lithium phosphate (Li3PO4), lithium chloride (LiCl), lithium fluoride (LiF), and lithium sulfate (Li2SO4).

[0054] The type of the lithium compound may vary depending on the type of material used in the reaction, as described below.

[0055]

[0056] In the above step (i), the water may be a reacting substance and a reaction solvent, and may react with lithium to produce lithium hydroxide.

[0057] In the above step (i), the aqueous solution is a solution in which a salt or acid is dissolved in water, and the type of lithium compound produced may vary depending on the dissolved component.

[0058] For example, the aqueous solution may be a solution containing a hydroxide salt, a carbonate salt, a carbonic acid salt, a phosphate salt, phosphoric acid, hydrochloric acid, hydrofluoric acid or sulfuric acid, i.e., a solution in which these salts or acids are dissolved in water.

[0059] If the above aqueous solution contains a hydroxide salt, lithium hydroxide can be produced.

[0060] If the above aqueous solution contains carbonate or carbonic acid, lithium carbonate can be produced.

[0061] If the above aqueous solution contains phosphate or phosphoric acid, lithium phosphate can be produced.

[0062] If the above aqueous solution contains hydrochloric acid, lithium chloride can be produced.

[0063] If the above aqueous solution contains hydrofluoric acid, lithium fluoride can be produced.

[0064] If the above aqueous solution contains sulfuric acid, lithium sulfate can be produced.

[0065] Preferably, the aqueous solution may contain a hydroxide salt, a carbonate salt or a carbonic acid salt.

[0066] When containing hydroxide, carbonate, carbonic acid, hydrochloric acid or hydrofluoric acid, the products are lithium hydroxide, lithium carbonate, lithium chloride or lithium fluoride, respectively, so they can be directly applied as raw materials for manufacturing cathode materials or for other purposes without a separate reprocessing process.

[0067] Lithium phosphate or lithium sulfate, obtained using aqueous solutions containing phosphate, phosphoric acid, or sulfuric acid, require a separate acid treatment process. For example, lithium phosphate and lithium sulfate require additional processes to convert them into lithium hydroxide or lithium carbonate, which can be used as raw materials for cathode material production or for other applications.

[0068] Since lithium phosphate has lower water solubility than other lithium compounds and may cause precipitation, it is advisable to increase the amount of aqueous solution added.

[0069] The above hydroxides, carbonates and phosphates may be salts of alkali metals or alkaline earth metals.

[0070] For example, the hydroxide salt may be one or more selected from the group consisting of Ca(OH)2, Mg(OH)2, NaOH and KOH, but is not limited thereto.

[0071] The above carbonate may be one or more selected from the group consisting of Na2CO3, CaCO3 and K2CO3, but is not limited thereto.

[0072] The above phosphate may be one or more selected from the group consisting of Na3PO4, K3PO4 and Ca3(PO4)2, but is not limited thereto.

[0073] The concentration of hydroxide, carbonate, carbonic acid, phosphate, phosphoric acid, hydrochloric acid, hydrofluoric acid or sulfuric acid in the aqueous solution may be, but is not limited to, 0.1 to 5.0 M. When the concentration of hydroxide, carbonate, carbonic acid, phosphate, phosphoric acid, hydrochloric acid, hydrofluoric acid or sulfuric acid in the aqueous solution is within the above range, the recovery rate of the lithium compound can be increased. Specifically, when the concentration of hydroxide, carbonate, carbonic acid, phosphate, phosphoric acid, hydrochloric acid, hydrofluoric acid or sulfuric acid in the aqueous solution is less than 0.1 M, the recovery rate of the lithium compound may be reduced, and when it exceeds 5.0 M, by-products or unreacted substances may increase, which may result in an additional purification process or a reduction in the recovery rate and purity.

[0074] In the above step (i), the water or aqueous solution may be used at a ratio of 1 to 50 L per 1 kg of the cathode material waste crucible, but is not limited thereto. If the water or aqueous solution is used within the above ratio range, the recovery rate of the lithium compound can be increased.

[0075]

[0076] In the above step (i), the ultrasonic treatment is 200 W / m 3 Ideally, for example, 300 to 4000 W / m 3 The ultrasonic treatment can be performed at an output of 10 KHz or higher, specifically 10 KHz to 200 KHz, preferably 24 to 80 KHz. If the ultrasonic treatment is performed outside the output and frequency conditions, the recovery rate of the lithium compound may be lowered.

[0077] In the above step (i), the ultrasonic treatment may be performed at a temperature of 20°C or higher, for example, 20 to 90°C, preferably 30 to 60°C. If the ultrasonic treatment is performed at a temperature lower than 20°C, the recovery rate of the lithium compound may decrease, and if it is performed at a temperature higher than 90°C, by-products may be generated or the amount of water evaporated may increase.

[0078] In the above step (i), the ultrasonic treatment may be performed for 1 minute or more, for example, 2 minutes to 1 hour. When the ultrasonic treatment time is within the above range, the recovery rate of the lithium compound is excellent.

[0079] In the above step (i), the ultrasonic treatment in a state where the waste crucible is ground or crushed can be performed under stirring. If the ultrasonic treatment is performed under stirring, the recovery rate of the lithium compound can be increased.

[0080] The above stirring can be performed using a conventional method used in the relevant technical field.

[0081] If the raw material is a cathode waste crucible disc, the cathode waste crucible can be equipped with an ultrasonic device so that ultrasonic energy reaches the interior of the waste crucible where lithium elements penetrate and exist in an oxide state.

[0082]

[0083] The above step (ii) is a step of filtering the lithium compound-containing aqueous solution obtained above to separate it from the cathode material waste crucible.

[0084] The above filtration can be performed using conventional means used in the art, for example, a solid-liquid separator or filter.

[0085]

[0086] The above step (iii) is a step of evaporating the lithium compound-containing aqueous solution separated above to obtain a lithium compound as a solid.

[0087] After the above step (iii), a step of crystallizing the lithium compound may be further included.

[0088] The above crystallization can be performed by a conventional method used in the art depending on the type of lithium compound.

[0089] The obtained lithium compound may be crystalline or amorphous.

[0090]

[0091] A method for recovering a lithium compound from a waste cathode crucible according to one embodiment of the present invention may further include, after step (ii), a step of cleaning and recovering the waste cathode crucible.

[0092] The above cleaning can be performed with water, for example, industrial water, and can be performed repeatedly.

[0093]

[0094] Hereinafter, the present invention will be described in more detail through examples, comparative examples, and experimental examples. These examples, comparative examples, and experimental examples are intended solely to illustrate the present invention, and it will be apparent to those skilled in the art that the scope of the present invention is not limited thereto.

[0095]

[0096] Manufacturing Example 1: Preparation of a cathode material waste crucible

[0097] The cathode waste crucible, the main component of which is Al2O3, was obtained from a domestic cathode material manufacturer and discarded after 30 days of use using the same cathode material manufacturing process using lithium hydroxide as a raw material.

[0098]

[0099] Example 1: Recovery of lithium compounds

[0100] 7 kg of the cathode material waste crucible of the above manufacturing example 1 was placed in a reactor filled with water and heated at 50°C for 10 minutes at 300 W / m 3 The reaction was carried out by ultrasonic treatment with the output and ultrasonic frequency of 24 kHz.

[0101] The above reaction product was filtered through a filter to obtain a solution, and the solution was heated to 100°C to evaporate moisture to obtain a lithium compound.

[0102]

[0103] Example 2: Recovery of lithium compounds

[0104] The lithium compound was recovered in the same manner as in Example 1, except that a 1.0 M NaOH aqueous solution was used instead of the water.

[0105]

[0106] Example 3: Recovery of lithium compounds

[0107] Lithium compounds were recovered in the same manner as in Example 1, except that a 1.0 M Ca(OH)2 aqueous solution was used instead of the water.

[0108]

[0109] Example 4: Recovery of lithium compounds

[0110] The lithium compound was recovered in the same manner as in Example 1, except that a 1.0 M Na2CO3 aqueous solution was used instead of the water.

[0111]

[0112] Example 5: Recovery of lithium compounds

[0113] The lithium compound was recovered in the same manner as in Example 1, except that a 1.0 M Na3PO4 aqueous solution was used instead of the water.

[0114]

[0115] Example 6: Recovery of lithium compounds

[0116] The lithium compound was recovered in the same manner as in Example 1, except that a 1.0 M phosphoric acid aqueous solution was used instead of the water.

[0117]

[0118] Example 7: Recovery of lithium compounds

[0119] The lithium compound was recovered in the same manner as in Example 1, except that a 1.0 M hydrochloric acid solution was used instead of the water.

[0120]

[0121] Example 8: Recovery of lithium compounds

[0122] The lithium compound was recovered in the same manner as in Example 1, except that a 1.0 M hydrofluoric acid solution was used instead of the water.

[0123]

[0124] Example 9: Recovery of lithium compounds

[0125] The lithium compound was recovered in the same manner as in Example 1, except that a 1.0 M sulfuric acid aqueous solution was used instead of the water.

[0126]

[0127] Example 10: Recovery of lithium compounds

[0128] The cathode waste crucible of the above Manufacturing Example 1 was crushed to an average particle size of 3 mm, placed in a reactor filled with a 1.0 M NaOH aqueous solution, and treated with ultrasonic waves while stirring, and the same procedure as Example 2 was followed to recover a lithium compound.

[0129]

[0130] Example 11: Recovery of lithium compounds

[0131] The lithium compound was recovered in the same manner as in Example 2, except that the upper surface lithium-containing portion of the positive electrode waste crucible of the above Manufacturing Example 1 was ground to an average particle diameter of 0.5 mm, and then placed in a reactor filled with a 1.0 M NaOH aqueous solution and ultrasonicated while stirring.

[0132]

[0133] Comparative Example 1: Recovery of lithium compounds

[0134] Lithium compounds were recovered in the same manner as in Example 1, except that ultrasonic treatment was not performed.

[0135]

[0136] Comparative Example 2: Recovery of lithium compounds

[0137] Lithium compounds were recovered in the same manner as in Example 2, except that ultrasonic treatment was not performed.

[0138]

[0139] Comparative Example 3: Recovery of lithium compounds

[0140] Lithium compounds were recovered in the same manner as in Example 9, except that ultrasonic treatment was not performed.

[0141]

[0142] Comparative Example 4: Recovery of lithium compounds

[0143] The cathode waste crucible of the above manufacturing example 1 was crushed to an average particle size of 5 mm, and then placed in a reactor filled with a 1.0 M sulfuric acid aqueous solution, and reacted at 50°C for 1 hour under stirring without ultrasonic treatment.

[0144] The above reaction product was filtered through a filter to obtain a solution, and the solution was heated to 100°C to evaporate moisture to obtain a lithium compound.

[0145]

[0146] Experimental Example 1: Recovery Rate Evaluation

[0147] The initial amount of lithium present in the cathode material crucible of the above Manufacturing Example 1 was measured through ICP (Inductively Coupled Plasma) analysis.

[0148] In addition, the amount of lithium recovered was calculated from the amount of lithium compound obtained in the above examples and comparative examples.

[0149] The recovery rate was calculated using the following mathematical formula 1.

[0150] [Mathematical Formula 1]

[0151]

[0152]

[0153] Recovery Rate (%) Example 182% Example 294% Example 395% Example 496% Example 591% Example 691% Example 793% Example 893% Example 992% Example 1096% Example 1198% Comparative Example 152% Comparative Example 275% Comparative Example 378% Comparative Example 479%

[0154]

[0155] As shown in Table 1 above, it can be confirmed that Examples 1 to 11, in which the cathode material waste crucible was reacted by ultrasonic treatment in water or an aqueous solution according to the present invention, have a superior recovery rate of lithium compounds compared to Comparative Examples 1 to 4, in which the reaction was performed without ultrasonic treatment.

[0156] In particular, Examples 2 to 9 using aqueous solutions showed better recovery rates than Example 1 using water, and among the aqueous solutions, Examples 2 to 4 using aqueous solutions containing hydroxides or carbonates showed better recovery rates.

[0157] In addition, it was shown that Examples 10 to 11, which performed ultrasonic treatment after crushing or grinding, showed improved recovery rates compared to Example 2, which used a disc.

[0158]

[0159] While specific aspects of the present invention have been described in detail above, it should be apparent to those skilled in the art that these specific descriptions are merely preferred embodiments and do not limit the scope of the present invention. Those skilled in the art will be able to make various applications and modifications within the scope of the present invention based on the above description.

[0160] Accordingly, the substantial scope of the present invention will be defined by the appended claims and their equivalents.

Claims

1. (i) A step of producing an aqueous solution containing a lithium compound by ultrasonic treating a cathode waste crucible in water or an aqueous solution; (ii) a step of filtering the lithium compound-containing aqueous solution to separate it from the cathode material waste crucible; and (iii) A method for recovering a lithium compound from a waste cathode crucible, comprising a step of evaporating the lithium compound-containing aqueous solution.

2. A recovery method according to claim 1, further comprising a step of grinding or crushing the cathode waste prior to step (i).

3. A recovery method in the first paragraph, wherein the cathode material waste crucible is a waste reaction vessel used in the manufacture of cathode materials using at least one of lithium hydroxide and lithium carbonate as raw materials.

4. A recovery method in the first paragraph, wherein the lithium compound is at least one selected from the group consisting of lithium hydroxide (LiOH), lithium carbonate (Li2CO3), lithium phosphate (Li3PO4), lithium chloride (LiCl), lithium fluoride (LiF), and lithium sulfate (Li2SO4).

5. A recovery method in step (i) of paragraph 1, wherein the aqueous solution contains a hydroxide salt, a carbonate salt, a carbonic acid salt, a phosphate salt, phosphoric acid, hydrochloric acid, hydrofluoric acid or sulfuric acid.

6. A recovery method in step (i) of paragraph 5, wherein the aqueous solution contains hydroxide salt, carbonate salt or carbonic acid.

7. A recovery method in paragraph 5, wherein the hydroxide salt, carbonate salt and phosphate salt are salts of an alkali metal or an alkaline earth metal.

8. A recovery method in paragraph 7, wherein the hydroxide salt is at least one selected from the group consisting of Ca(OH)2, Mg(OH)2, NaOH, and KOH.

9. A recovery method in paragraph 7, wherein the carbonate is at least one selected from the group consisting of Na2CO3, CaCO3, and K2CO3.

10. A recovery method in claim 7, wherein the phosphate is at least one selected from the group consisting of Na3PO4, K3PO4, and Ca3(PO4)2.

11. In the first paragraph, in step (i), the ultrasonic treatment is 200 W / m 3 A recovery method performed with an output of the above and an ultrasonic frequency of 10 KHz or higher.

12. A recovery method in step (i) of paragraph 1, wherein the ultrasonic treatment is performed at a temperature of 20°C or higher.

13. A recovery method in step (i) of paragraph 1, wherein the ultrasonic treatment is performed under stirring.

14. A recovery method further comprising, after step (iii) of paragraph 1, a step of crystallizing a lithium compound.

15. A recovery method according to claim 1, further comprising, after step (ii), a step of cleaning and recovering the cathode waste crucible.

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