Method for preferentially extracting lithium from waste ternary lithium ion battery powder

Abstract

The invention belongs to the technical field of waste lithium ion battery recovery, and discloses a method for preferentially extracting lithium from waste ternary lithium ion battery powder. The method comprises the following steps: mixing the waste ternary lithium ion battery powder with water, ammonium sulfate and concentrated sulfuric acid to form slurry; carrying out curing treatment on the slurry; and grinding the cured material, and performing water leaching to obtain a lithium-containing solution and water leaching residues. According to the method for preferentially extracting lithium from the waste ternary lithium ion battery powder, the pyrometallurgy and hydrometallurgy means are combined, the required energy consumption is low, the temperature of a reaction system is far lower than the high temperature required by a conventional pyrometallurgy process, remarkable selectivity is shown in the lithium recovery process, and the method is suitable for industrial production. The selectivity not only improves the recovery efficiency of lithium and reduces the interference of other metals, but also enables the required reagents to have few types and low dosage. In addition, the method does not need a tedious impurity removal means subsequently, and is a method for treating the waste ternary lithium ion battery powder with low industrial cost and high return rate.

Description

Technical Field

[0001] The invention belongs to the technical field of recycling waste lithium-ion batteries, and in particular relates to a method for preferentially extracting lithium from waste ternary lithium-ion battery powder. Background Art

[0002] Nickel-cobalt-manganese-oxide ternary battery materials have become one of the most promising cathode materials due to their outstanding characteristics such as long life, low self-discharge and high specific capacity. Waste ternary lithium battery powder contains valuable metals such as lithium, nickel, cobalt and manganese, which are important secondary resources and urgently need to be recycled. The conventional wet process for recycling waste lithium batteries is to use full wet leaching for valuable metals, that is, the waste ternary lithium-ion batteries are pre-treated and then the valuable metals are dissolved from the cathode materials with acid and leached together. The leachate is subjected to impurity removal, extraction and other processes to recover nickel, cobalt and manganese, and lithium products are obtained by precipitation; while the conventional pyrometallurgical process is to discharge the waste lithium-ion batteries, mix them with reducing agents and slag-making agents, and directly put them into a furnace above 1000°C for reduction smelting. During the smelting process, low-boiling point metals and compounds are recovered by condensation, and metals with melting points lower than the reaction temperature are reduced to form alloys. At present, a single wet process or pyrometallurgical process cannot meet the complex lithium battery recycling needs at this stage.

[0003] The pyrometallurgical-wet metal combined treatment process mainly utilizes reducing agents or salt additives to selectively convert the lithium element in the active material into soluble compounds, such as Li2CO3, LiNO3, Li2SO4, etc., through roasting, while other metal elements still exist in the form of water-insoluble elements or oxides, and then the lithium in the black powder is selectively leached out through water immersion.

[0004] Patent application CN117904453B discloses a method for selective lithium extraction for lithium battery recycling and its application. The patent soaks the positive and negative electrode waste materials of the battery in inorganic acid and then heat-insulates and ages them for 20 to 30 hours, then roasts and sinters at 600 to 750 ° C, and the sintered material is leached in a dilute sulfuric acid solution. Modified adsorption composite particles are added to the leachate for impurity removal and filtration to obtain lithium sulfate recovery liquid. The patent combines pyrometallurgy and hydrometallurgy, and has strong selectivity in the impurity removal process, but the process flow is complicated and time-consuming, and the modified adsorption composite particles are difficult to prepare, which is not suitable for large-scale industrial production needs. Patent application CN110828926B discloses a method for the coordinated recovery of metals and graphite from waste lithium-ion battery positive and negative electrode materials, adding excess concentrated sulfuric acid to the positive and negative electrode waste materials of the battery for aging to obtain solidified clinker, and then slurry leaching with water or dilute acid, and solid-liquid separation to obtain leachate containing lithium, nickel, cobalt and graphite. However, the patent did not take into account the difficulty and cost of subsequent separation of lithium, nickel, cobalt and other elements from the leachate. Patent application CN111254294B discloses a method for selectively extracting lithium from waste lithium-ion battery powder and electrolytically separating and recovering manganese dioxide. Excess concentrated sulfuric acid is added to the waste lithium-ion battery powder, and then roasted at a temperature of 350-750°C for 1-5 hours. The roasted material is leached with pure water, and the lithium-containing leachate is respectively sulfided and oxidized and precipitated to remove impurities, and the lithium-containing purified liquid is electrolyzed to obtain manganese dioxide. This patent also selectively converts lithium in the battery powder into lithium sulfate, but the types of reagents consumed in the impurity removal process are many and the amount is large, which greatly increases the industrial cost.

[0005] In summary, the new process combining pyrometallurgy and hydrometallurgy, such as the sulfation roasting-water leaching process, has overcome the defects of high temperature and high energy consumption of the pyrometallurgical system and lengthy recovery process of the hydrometallurgical technology to a certain extent, but there are still problems such as large reagent consumption, high system temperature, and generation of wastewater or waste gas. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the shortcomings and defects mentioned in the above background technology and provide a method for preferentially extracting lithium from waste ternary lithium-ion battery powder.

[0007] In order to solve the above technical problems, the technical solution proposed by the present invention is: A method for preferentially extracting lithium from waste ternary lithium-ion battery powder comprises the following steps: (1) Mixing waste ternary lithium-ion battery powder with water, ammonium sulfate and concentrated sulfuric acid into a slurry; (2) subjecting the slurry to a aging treatment; (3) Grinding the material matured in step (2) and then leaching it in water to obtain a lithium-containing solution and leaching residue.

[0008] In the above-mentioned method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, in step (1), the molar ratio of lithium element in the waste ternary lithium-ion battery powder to ammonium sulfate is 1:0.1~1:0.5; more preferably, the molar ratio of lithium element in the waste ternary lithium-ion battery powder to ammonium sulfate is 1:0.1~1:0.2; the introduction of ammonium sulfate strengthens the sulfation transformation of lithium, and can synergistically promote the transformation of lithium into lithium sulfate with concentrated sulfuric acid during the low-temperature sulfuric acid aging process.

[0009] In the above-mentioned method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, in step (1), the amount of concentrated sulfuric acid used is 0.8 to 0.9 times the theoretical amount of sulfuric acid required to completely convert lithium in the waste ternary lithium-ion battery powder into lithium sulfate. More preferably, the amount of concentrated sulfuric acid used is 0.8 times the theoretical amount of sulfuric acid required to completely convert lithium in the waste ternary lithium-ion battery powder into lithium sulfate. Under this condition, the reaction is in an acid-deficient environment, which is conducive to the selective reaction of concentrated sulfuric acid with lithium, and the consumption of concentrated sulfuric acid is low.

[0010] In the above method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, in step (1), the amount of water used is 20% to 80% of the mass of the waste ternary lithium-ion battery powder. The purpose of wetting the powder with water is to activate the metal ions in the waste ternary lithium-ion battery powder, which is beneficial to increase the activity coefficient of the metal ions and facilitate the subsequent reaction. The amount of water needs to be controlled within this range, otherwise too much water will reduce the concentration of sulfuric acid and thus extend the aging time.

[0011] In the above method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, in step (2), the aging temperature is 100-250°C and the aging time is 0.5-2.5h. More preferably, the aging time is 2h and the aging temperature is 200°C. Under this condition, the concentrated sulfuric acid and the waste ternary lithium-ion battery powder react more fully, and the temperature of the reaction system will not be too high, thereby achieving the purpose of reducing energy consumption and saving resources.

[0012] In the above-mentioned method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, the liquid-to-solid ratio of the water immersion is 5:1~10:1, and the ratio unit is mL / g; the water immersion is carried out at room temperature, the water immersion time is 30~60min, and the stirring rate during leaching is 500~800rad / min. During the leaching process, most of the lithium in the waste ternary lithium-ion battery powder is dissolved in water in the form of lithium sulfate to obtain a lithium-containing solution. Through solid-liquid separation, lithium exists in the liquid phase in the form of lithium sulfate, and nickel, cobalt and manganese exist in the slag phase in the form of metal oxides, thereby achieving preferential extraction of lithium.

[0013] In the above method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, in step (3), the lithium content in the water-leached residue is reduced to below 0.5%.

[0014] In the above-mentioned method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, the leaching rate of lithium in the lithium-containing solution is not less than 95%.

[0015] The above-mentioned method for preferentially extracting lithium from waste ternary lithium-ion battery powder is preferably, wherein sodium hydroxide solution is added to the lithium-containing solution for precipitation and impurity removal, and the solution is filtered. A saturated sodium carbonate solution is added to the obtained filtrate for water bath heating. After the reaction is completed, the solution is filtered to obtain a white precipitate, which is washed to obtain lithium carbonate.

[0016] In the above-mentioned method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, the water bath heating temperature is 80-95°C, the heating time is 60-90 min; and the concentration of the sodium hydroxide solution is 1 mol / L-1.5 mol / L.

[0017] In the above-mentioned method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, the purity of the lithium carbonate is not less than 99%.

[0018] In the present invention, in the acid-deficient system, the lithium in the waste ternary lithium-ion battery powder is converted into lithium sulfate under the synergistic effect of ammonium sulfate and concentrated sulfuric acid; in this process, nickel, cobalt and manganese are not converted, and nickel, cobalt and manganese are basically present in the slag phase in the form of metal oxides, because the conversion of nickel, cobalt and manganese into corresponding sulfates needs to be carried out under the conditions of sufficient sulfuric acid and high temperature. Therefore, the present application only needs to effectively realize the preferential extraction of lithium by controlling a lower temperature, insufficient sulfuric acid and adding a small amount of ammonium sulfate.

[0019] Compared with the prior art, the present invention has the following beneficial effects: The method for preferentially extracting lithium from waste ternary lithium-ion battery powder proposed in the present invention combines pyrometallurgy and hydrometallurgy, not only requires low energy consumption, the temperature of the reaction system is much lower than the high temperature required by the conventional pyrometallurgical process, but also shows significant selectivity in the process of recovering lithium, which not only improves the recovery efficiency of lithium, reduces the interference of other metals, but also reduces the number of reagents required and the amount used. In addition, the method does not require cumbersome impurity removal means in the follow-up, and is a method for treating waste ternary lithium-ion battery powder with low industrial cost and high return rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 The present invention is a process flow chart for preferentially extracting lithium from waste ternary lithium-ion battery powder. DETAILED DESCRIPTION

[0021] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0022] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0023] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0024] The black powder described in the following examples and comparative examples is waste ternary lithium ion battery powder obtained by pretreatment methods such as disassembly, pyrolysis, crushing and screening of the same batch of waste ternary lithium ion batteries. In terms of mass percentage, the lithium content is 3.77%, the nickel content is 11.45%, the cobalt content is 11.76%, and the manganese content is 10.47%.

[0025] Embodiment 1: The method for preferentially extracting lithium from waste ternary lithium-ion battery powder (hereinafter referred to as black powder) of this embodiment has a process flow chart as shown in FIG. Figure 1 As shown, the following steps are included: (1) Take 30g of black powder and 2.16g of ammonium sulfate and mix them evenly in the ratio of nLi:n(NH4)2SO4=1:0.1, then add 12mL (40% of the mass of black powder) of water to moisten the mixed powder; after the powder is completely moistened, add 6.42g of 98% industrial concentrated sulfuric acid (0.8 times the theoretical amount required for black powder) and stir thoroughly until the material becomes a slurry; (2) subjecting the slurry obtained in step (1) to a aging treatment at a aging temperature of 200° C. for 2 h, until the slurry agglomerates and hardens after aging is complete; (3) Grinding the slaked material after cooling down into powder, taking 30 g of the powder for water leaching, wherein the liquid-to-solid ratio of the water leaching is 10:1, the ratio unit is mL / g, the water leaching is carried out at room temperature for 30 min, the stirring rate during leaching is controlled at 800 rad / min, filtering after the water leaching is completed, and obtaining a lithium-containing solution and water leaching residue; (4) The lithium-containing solution obtained in step (3) is precipitated and impurities are removed by adding 1 mol / L NaOH solution, filtered, and a saturated sodium carbonate solution is added to the filtrate, heated in a water bath at 80° C. for 60 min, mixed and stirred, and filtered to obtain a white precipitate, which is then washed to obtain lithium carbonate.

[0026] Embodiment 2: The method for preferentially extracting lithium from waste ternary lithium-ion battery powder (hereinafter referred to as black powder) of this embodiment has a process flow chart as shown in FIG. Figure 1 As shown, the following steps are included: (1) Take 30g of black powder and 3.24g of ammonium sulfate and mix them evenly in the ratio of nLi:n(NH4)2SO4=1:0.15, then add 6mL (20% of the mass of black powder) of water to moisten the mixed powder; after the powder is completely moistened, add 6.83g of 98% industrial concentrated sulfuric acid (0.85 times the theoretical amount required for black powder) and stir thoroughly until the material becomes a slurry; (2) subjecting the slurry obtained in step (1) to a aging treatment at a aging temperature of 250° C. for 0.5 h, until the slurry agglomerates and hardens after aging is complete; (3) Grinding the slaked material after cooling down into powder, taking 30 g of the powder for water leaching, wherein the liquid-to-solid ratio of the water leaching is 5:1, the ratio unit is mL / g, the water leaching is carried out at room temperature for 45 min, the stirring rate during leaching is controlled at 500 rad / min, filtering after the water leaching is completed, and obtaining a lithium-containing solution and water leaching residue; (4) The lithium-containing solution obtained in step (3) is precipitated and impurities are removed by adding 1.2 mol / L NaOH solution, filtered, and a saturated sodium carbonate solution is added to the filtrate, heated in a water bath at 85° C. for 90 min, mixed and stirred, and filtered to obtain a white precipitate, which is then washed to obtain lithium carbonate.

[0027] Embodiment 3: The method for preferentially extracting lithium from waste ternary lithium-ion battery powder (hereinafter referred to as black powder) of this embodiment has a process flow chart as shown in FIG. Figure 1 As shown, the following steps are included: (1) Take 30g of black powder and 4.32g of ammonium sulfate and mix them evenly in the ratio of nLi:n(NH4)2SO4=1:0.2, then add 24mL of water (80% of the mass of black powder) to wet the mixed powder; after the powder is completely wetted, add 7.23g of 98% industrial concentrated sulfuric acid (0.9 times the theoretical amount required for black powder) and stir thoroughly until the material becomes a slurry; (2) The slurry obtained in step (1) is subjected to a aging treatment at a aging temperature of 100° C. for 2.5 h. After the slurry is completely lumped and hardened; (3) Grinding the slaked material after cooling into powder, taking 30 g of the powder for water immersion treatment, wherein the liquid-to-solid ratio of the water immersion is 10:1, the ratio unit is mL / g, the water immersion is carried out at room temperature for 60 min, the stirring rate during leaching is controlled at 600 rad / min, and filtering after the water immersion is completed to obtain a lithium-containing solution and water immersion residue; (4) The lithium-containing solution obtained in step (3) is precipitated and impurities are removed by adding 1.5 mol / L NaOH solution, filtered, and a saturated sodium carbonate solution is added to the filtrate, heated in a water bath at 95° C. for 70 min, mixed and stirred, and filtered to obtain a white precipitate, which is then washed to obtain lithium carbonate.

[0028] Comparative Example 1: The difference between this comparative example and Example 1 is only the amount of concentrated sulfuric acid added in step (1). In step (1) of this comparative example, the amount of concentrated sulfuric acid added is 1.5 times the theoretical amount required for black powder, specifically 12.04 g. The other processes and parameters are exactly the same as those in Example 1.

[0029] Comparative Example 2: The difference between this comparative example and Example 1 is that ammonium sulfate is not introduced in step (1), and the other processes and parameters are exactly the same as those in Example 1.

[0030] Comparative Example 3: The difference between this comparative example and Example 1 is that concentrated sulfuric acid is not introduced in step (1), and the other processes and parameters are exactly the same as those in Example 1.

[0031] After the water leaching in the above embodiments and comparative examples, the leaching rates of various metals in the black powder are shown in Table 1, and the residual lithium content in the water leaching residue and the final lithium carbonate purity are shown in Table 2.

[0032] Table 1 Leaching rate of each valuable metal in black powder

[0033] Table 2 Residual lithium content of water leaching residue and purity of lithium carbonate

[0034] It can be seen from the test results of Table 1 and Table 2 that: in Comparative Example 1, when concentrated sulfuric acid is added, the amount of concentrated sulfuric acid is 1.5 times the theoretical amount. Under this condition, the reaction is in an overacid environment. After the lithium in the waste ternary lithium-ion battery powder is reacted, the remaining sulfuric acid will continue to react with the nickel, cobalt and manganese in the material, resulting in an increase in the leaching rate of nickel, cobalt and manganese in the leachate, reducing the selectivity of lithium, and then resulting in a decrease in the purity of the subsequently prepared lithium carbonate. At the same time, it will also increase the cost of subsequent separation of lithium and nickel, cobalt and manganese; in Comparative Example 2, since ammonium sulfate is not introduced, the efficiency of concentrated sulfuric acid alone in converting lithium in black powder into lithium sulfate is low, and the leaching rate of lithium is reduced from 95.33% to 72.53%; in Comparative Example 3, since concentrated sulfuric acid is not introduced, ammonium sulfate is difficult to convert lithium in black powder into lithium sulfate under a low temperature system, resulting in a low leaching rate of lithium and high difficulty in preparing lithium carbonate from the leachate. It can also be seen from the test results of Example 1, Comparative Example 2 and Comparative Example 3 that the introduction of ammonium sulfate strengthens the sulfation transformation of lithium and can synergistically promote the transformation of lithium into lithium sulfate with concentrated sulfuric acid during the low-temperature sulfuric acid aging process.

Claims

1. A method for preferentially extracting lithium from waste ternary lithium-ion battery powder, characterized in that: The following steps are involved: (1) Mixing waste ternary lithium-ion battery powder with water, ammonium sulfate and concentrated sulfuric acid into a slurry; (2) subjecting the slurry to a aging treatment; (3) Grinding the material matured in step (2) and then leaching it in water to obtain a lithium-containing solution and leaching residue.

2. The method for preferentially extracting lithium from waste ternary lithium-ion battery powder as claimed in claim 1, characterized in that: In step (1), the molar ratio of lithium element in the waste ternary lithium ion battery powder to ammonium sulfate is 1:0.1~1:0.5; the amount of concentrated sulfuric acid used is 0.8 times~0.9 times the theoretical amount of sulfuric acid required to completely convert the lithium in the waste ternary lithium ion battery powder into lithium sulfate.

3. The method for preferentially extracting lithium from waste ternary lithium-ion battery powder as claimed in claim 1, characterized in that: In step (1), the amount of water used is 20% to 80% of the mass of the waste ternary lithium-ion battery powder.

4. The method for preferentially extracting lithium from waste ternary lithium-ion battery powder as claimed in claim 1, characterized in that: In step (2), the aging temperature is 100-250° C., and the aging time is 0.5-2.5 h.

5. The method for preferentially extracting lithium from waste ternary lithium-ion battery powder as claimed in claim 1, characterized in that: The liquid-to-solid ratio of the water immersion is 5:1-10:1, and the ratio unit is mL / g; the water immersion is carried out at room temperature, the water immersion time is 30-60 minutes, and the stirring rate during leaching is 500-800 rad / min.

6. The method for preferentially extracting lithium from waste ternary lithium-ion battery powder as claimed in claim 1, characterized in that: In step (3), the lithium content in the water-leached slag is reduced to below 0.5%, and the lithium leaching rate in the lithium-containing solution is not less than 95%.

7. The method for preferentially extracting lithium from waste ternary lithium-ion battery powder according to any one of claims 1 to 6, characterized in that: Sodium hydroxide solution is added to the lithium-containing solution to precipitate and remove impurities, and the solution is filtered. A saturated sodium carbonate solution is added to the obtained filtrate to heat it in a water bath. After the reaction is completed, the solution is filtered to obtain a white precipitate, which is washed to obtain lithium carbonate.

8. The method for preferentially extracting lithium from waste ternary lithium-ion battery powder as claimed in claim 7, characterized in that: The water bath heating temperature is 80-95° C., and the heating time is 60-90 min.

9. The method for preferentially extracting lithium from waste ternary lithium-ion battery powder as claimed in claim 7, characterized in that: The purity of the lithium carbonate is not less than 99%.

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