A method for preferentially extracting lithium from waste ternary lithium ion battery powder

Abstract

The present application belongs to the technical field of waste lithium ion battery recycling, and discloses a method for preferentially extracting lithium from waste ternary lithium ion battery powder: waste ternary lithium ion battery powder is mixed with water, ammonium sulfate and concentrated sulfuric acid to form a slurry; the slurry is subjected to ripening treatment; the ripened material is ground and then water immersed to obtain a lithium-containing solution and a water immersion residue. The method for preferentially extracting lithium from waste ternary lithium ion battery powder combines pyrometallurgical and hydrometallurgical means, not only has low energy consumption, but also has a reaction system temperature far lower than the high temperature required by conventional pyrometallurgical processes; moreover, the method exhibits significant selectivity in the process of recovering lithium, which not only improves the recovery efficiency of lithium and reduces the interference of other metals, but also reduces the types and amount of required reagents. In addition, the method does not require complicated impurity removal means, and is a method for treating waste ternary lithium ion battery powder with low industrial cost and high return rate.

Description

Technical Field

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

[0002] Lithium nickel cobalt manganese oxide (NiCoMnO) ternary lithium battery materials, with their outstanding characteristics of long lifespan, low self-discharge, and high specific capacity, have become one of the most promising cathode materials. Waste ternary lithium battery powder contains valuable metals such as lithium, nickel, cobalt, and manganese, representing important secondary resources that urgently need resource recycling. Conventional wet leaching processes for recycling waste lithium batteries involve the complete wet leaching of valuable metals. This involves pre-treating the waste ternary lithium-ion batteries and then using acid to dissolve the valuable metals from the cathode material and leach them together. The leachate undergoes impurity removal and extraction processes to recover nickel, cobalt, and manganese, and lithium is obtained through precipitation. Conventional pyrometallurgical processes involve discharging waste lithium-ion batteries, mixing them with reducing agents and slagging agents, and then directly placing them into a furnace at over 1000°C for reduction smelting. During smelting, low-boiling-point metals and compounds are recovered through condensation, while metals with melting points below the reaction temperature are reduced to form alloys. Currently, neither single wet nor pyrometallurgical processes can meet the complex lithium battery recycling needs of today.

[0003] The pyrometallurgical-hydrometallurgical combined process mainly utilizes reducing agents or salt additives to selectively convert lithium elements in active materials into soluble compounds, such as Li2CO3, LiNO3, and Li2SO4, through calcination. Other metal elements remain in the form of insoluble elements or oxides. Then, lithium is selectively leached from the black powder through water immersion.

[0004] Patent application CN117904453B discloses a method for selective lithium extraction in lithium battery recycling and its application. This patent involves soaking waste positive and negative electrode materials of batteries in inorganic acid, aging them at a constant temperature for 20-30 hours, and then sintering them at 600-750℃. The sintered material is then leached in a dilute sulfuric acid solution. Modified adsorption composite particles are added to the leachate for impurity removal and filtration, yielding a lithium sulfate recovery solution. This patent combines pyrometallurgy and hydrometallurgy, exhibiting strong selectivity in the impurity removal process. However, the process is complex, time-consuming, and the preparation of modified adsorption composite particles is difficult, making it unsuitable for large-scale industrial production. Patent application CN110828926B discloses a method for the co-recovery of metals and graphite from waste lithium-ion battery positive and negative electrode materials. Excess concentrated sulfuric acid is added to the waste positive and negative electrode materials for curing to obtain solidified curing material. This material is then leached in water or dilute acid, and solid-liquid separation yields a leachate containing lithium, nickel, and cobalt, as well as graphite. However, this patent does not consider the difficulty and cost of subsequent separation of elements such as lithium, nickel, and cobalt 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. This method involves adding excess concentrated sulfuric acid to the waste lithium-ion battery powder, then calcining it at 350-750°C for 1-5 hours. The calcined material is then leached with pure water. The lithium-containing leachate is then purified by sulfidation precipitation and oxidation neutralization precipitation to remove impurities. The purified lithium-containing solution is then electrolyzed to obtain manganese dioxide. This patent also selectively converts lithium in the battery powder into lithium sulfate, but the purification process consumes a large variety and quantity of reagents, significantly increasing industrial costs.

[0005] In summary, while new processes combining pyrometallurgy and hydrometallurgy, such as the sulfation roasting-water leaching process, have overcome to some extent the shortcomings of pyrometallurgical technology, such as high temperature and high energy consumption, and the lengthy recovery process of hydrometallurgical technology, they still have problems such as high reagent consumption, high system temperature, and the 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 deficiencies and defects mentioned in the background art above and to provide a method for preferentially extracting lithium from waste ternary lithium-ion battery powder.

[0007] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0008] A method for preferentially extracting lithium from waste ternary lithium-ion battery powder includes the following steps:

[0009] (1) Mix waste ternary lithium-ion battery powder with water, ammonium sulfate and concentrated sulfuric acid to form a slurry;

[0010] (2) The slurry is subjected to a maturation treatment;

[0011] (3) Grind the material after maturation in step (2) and then soak it in water to obtain a lithium-containing solution and water-soaked residue.

[0012] 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 to ammonium sulfate in the waste ternary lithium-ion battery powder is 1:0.1 to 1:0.5; more preferably, the molar ratio of lithium element to ammonium sulfate in the waste ternary lithium-ion battery powder is 1:0.1 to 1:0.2; the introduction of ammonium sulfate plays a strengthening role in the sulfation transformation of lithium, and can synergistically promote the transformation of lithium to lithium sulfate with concentrated sulfuric acid during the low-temperature sulfuric acid ripening process.

[0013] In the above-described 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 these conditions, the reaction is in a sub-acidic environment, which is conducive to the selective reaction of concentrated sulfuric acid with lithium, while the consumption of concentrated sulfuric acid is relatively low.

[0014] In the above-described 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 increasing the activity coefficient of the metal ions and facilitating subsequent reactions. The amount of water needs to be controlled within this range; otherwise, excessive water will reduce the concentration of sulfuric acid, thus prolonging the aging time.

[0015] In the above-described method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, in step (2), the aging temperature is 100~250℃ and the aging time is 0.5~2.5h. More preferably, the aging time is 2h and the aging temperature is 200℃. Under these conditions, the reaction between concentrated sulfuric acid and waste ternary lithium-ion battery powder is more complete, and the reaction system temperature will not be too high, thus achieving the purpose of reducing energy consumption and saving resources.

[0016] In the above-described method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, the liquid-to-solid ratio of the water leaching is 5:1 to 10:1, with the unit being mL / g; the water leaching is carried out at room temperature for 30 to 60 minutes, and the stirring rate during leaching is 500 to 800 rad / min. During the leaching process, most of the lithium in the waste ternary lithium-ion battery powder dissolves in the water as lithium sulfate, resulting in a lithium-containing solution. Through solid-liquid separation, lithium exists in the liquid phase as lithium sulfate, while nickel, cobalt, and manganese exist in the slag phase as metal oxides, thus achieving preferential lithium extraction.

[0017] In the above-mentioned 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%.

[0018] In the above-described method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, the lithium leaching rate in the lithium-containing solution is not less than 95%.

[0019] In the above-described method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, sodium hydroxide solution is added to the lithium-containing solution for precipitation and impurity removal, followed by filtration. The resulting filtrate is then heated in a water bath with saturated sodium carbonate solution. After the reaction is complete, the filtrate is filtered to obtain a white precipitate, which is then washed to obtain lithium carbonate.

[0020] In the above-described method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, the water bath heating temperature is 80~95℃, the heating time is 60~90min, and the concentration of the sodium hydroxide solution is 1mol / L~1.5mol / L.

[0021] In the above-described method for preferentially extracting lithium from waste ternary lithium-ion battery powder, preferably, the purity of the lithium carbonate is not less than 99%.

[0022] This invention converts lithium in waste ternary lithium-ion battery powder into lithium sulfate in a sub-acid system under the synergistic effect of ammonium sulfate and concentrated sulfuric acid. During this process, nickel, cobalt, and manganese are not converted; they exist primarily as metal oxides in the slag phase. This is because the conversion of nickel, cobalt, and manganese into their corresponding sulfates requires sufficient sulfuric acid and a high temperature. Therefore, this application achieves efficient preferential lithium extraction by controlling a lower temperature, a sub-acid level, and adding a small amount of ammonium sulfate.

[0023] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0024] This invention proposes a method for preferentially extracting lithium from waste ternary lithium-ion battery powder, combining pyrometallurgical and hydrometallurgical techniques. This method not only requires low energy consumption and operates at a reaction temperature far lower than the high temperatures required by conventional pyrometallurgical processes, but also exhibits significant selectivity in lithium recovery. This selectivity not only improves lithium recovery efficiency and reduces interference from other metals, but also reduces the number and amount of reagents needed. Furthermore, this method eliminates the need for cumbersome subsequent impurity removal methods, making it a low-cost, high-return approach for processing waste ternary lithium-ion battery powder. Attached Figure Description

[0025] Figure 1 This is a process flow diagram of the present invention for preferentially extracting lithium from waste ternary lithium-ion battery powder. Detailed Implementation

[0026] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0027] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0028] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0029] The black powder mentioned in the following examples and comparative examples is waste ternary lithium-ion battery powder obtained by pretreatment methods such as splitting, pyrolysis, crushing and sieving from the same batch of waste ternary lithium-ion batteries. By 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%.

[0030] Example 1:

[0031] The method for preferentially extracting lithium from waste ternary lithium-ion battery powder (hereinafter referred to as black powder) in this embodiment is illustrated in the process flow diagram below. Figure 1 As shown, it includes the following steps:

[0032] (1) Take 30g of black powder and 2.16g of ammonium sulfate and mix them evenly according to the ratio of nLi:n(NH4)2SO4=1:0.1. Then add 12mL (40% of the mass of black powder) of water to wet the mixed powder. After the powder is completely wetted, add 6.42g of 98% industrial concentrated sulfuric acid (0.8 times the theoretical amount of black powder required) and stir thoroughly until the material becomes a slurry.

[0033] (2) The slurry obtained in step (1) is subjected to maturation treatment at a temperature of 200℃ for 2 hours. After maturation is complete, the slurry hardens and agglomerates.

[0034] (3) After the matured material in step (2) is cooled, it is ground into powder. Then, 30g of powder is subjected to water immersion treatment. The liquid-solid ratio of water immersion is 10:1, and the ratio unit is mL / g. Water immersion is carried out at room temperature for 30min. The stirring rate during immersion is controlled at 800rad / min. After water immersion, the mixture is filtered to obtain lithium-containing solution and water immersion residue.

[0035] (4) The lithium-containing solution obtained in step (3) is precipitated and impurities are removed by adding 1 mol / L NaOH solution, filtered, saturated sodium carbonate solution is added to the filtrate, heated in a water bath at 80°C for 60 min, mixed and stirred, filtered, and a white precipitate is obtained. The white precipitate is washed to obtain lithium carbonate.

[0036] Example 2:

[0037] The method for preferentially extracting lithium from waste ternary lithium-ion battery powder (hereinafter referred to as black powder) in this embodiment is illustrated in the process flow diagram below. Figure 1 As shown, it includes the following steps:

[0038] (1) Take 30g of black powder and 3.24g of ammonium sulfate and mix them evenly according to the ratio of nLi:n(NH4)2SO4=1:0.15. Then add 6mL (20% of the mass of black powder) of water to wet the mixed powder. After the powder is completely wetted, add 6.83g of 98% industrial concentrated sulfuric acid (0.85 times the theoretical amount of black powder required) and stir thoroughly until the material becomes a slurry.

[0039] (2) The slurry obtained in step (1) is subjected to maturation treatment at a temperature of 250°C for 0.5 hours. After maturation is complete, the slurry hardens and agglomerates.

[0040] (3) After the matured material in step (2) is cooled, it is ground into powder. Then, 30g of powder is subjected to water immersion treatment. The liquid-solid ratio of water immersion is 5:1, and the ratio unit is mL / g. Water immersion is carried out at room temperature for 45min. The stirring rate during immersion is controlled at 500rad / min. After water immersion, the mixture is filtered to obtain lithium-containing solution and water immersion residue.

[0041] (4) The lithium-containing solution obtained in step (3) is precipitated and purified by adding 1.2 mol / L NaOH solution, filtered, saturated sodium carbonate solution is added to the filtrate, heated in a water bath at 85°C for 90 min, mixed and stirred, filtered, and a white precipitate is obtained. The white precipitate is washed to obtain lithium carbonate.

[0042] Example 3:

[0043] The method for preferentially extracting lithium from waste ternary lithium-ion battery powder (hereinafter referred to as black powder) in this embodiment is illustrated in the process flow diagram below. Figure 1 As shown, it includes the following steps:

[0044] (1) Take 30g of black powder and 4.32g of ammonium sulfate and mix them evenly according to 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 of black powder required) and stir thoroughly until the material becomes a slurry.

[0045] (2) The slurry obtained in step (1) is subjected to maturation treatment at a temperature of 100℃ for 2.5h. After maturation is complete, the slurry hardens and agglomerates.

[0046] (3) After cooling the matured material after step (2), grind it into powder, and then take 30g of powder for water immersion treatment. The liquid-solid ratio of water immersion is 10:1, and the ratio unit is mL / g. The water immersion is carried out at room temperature for 60min. The stirring rate during immersion is controlled at 600rad / min. After the water immersion is completed, filter to obtain lithium-containing solution and water immersion residue.

[0047] (4) The lithium-containing solution obtained in step (3) is precipitated and impurities are removed by adding 1.5 mol / L NaOH solution, filtered, saturated sodium carbonate solution is added to the filtrate, heated in a water bath at 95°C for 70 min, mixed and stirred, filtered, and a white precipitate is obtained. The white precipitate is washed to obtain lithium carbonate.

[0048] Comparative Example 1:

[0049] The only difference between this comparative example and Example 1 is 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 12.04g. Other processes and parameters are exactly the same as in Example 1.

[0050] Comparative Example 2:

[0051] The only difference between this comparative example and Example 1 is that ammonium sulfate is not introduced in step (1). The other processes and parameters are exactly the same as in Example 1.

[0052] Comparative Example 3:

[0053] The only difference between this comparative example and Example 1 is that concentrated sulfuric acid is not introduced in step (1). Other processes and parameters are exactly the same as in Example 1.

[0054] After water leaching in the above examples and comparative examples, the leaching rates of each metal in the black powder are shown in Table 1, and the residual lithium content and final lithium carbonate purity in the water leaching residue are shown in Table 2.

[0055] Table 1. Leaching rates of various valuable metals in black powder

[0056]

[0057] Table 2 Results of residual lithium content and lithium carbonate purity in water-leached residue

[0058]

[0059] The experimental results in Tables 1 and 2 show that: In Comparative Example 1, when concentrated sulfuric acid was added, the amount of concentrated sulfuric acid was 1.5 times the theoretical amount. Under these conditions, the reaction was in an over-acidic environment. After the lithium in the waste ternary lithium-ion battery powder was reacted, the remaining sulfuric acid continued to react with the nickel, cobalt, and manganese in the material, resulting in an increased leaching rate of nickel, cobalt, and manganese in the leachate, reducing the selectivity of lithium, and consequently reducing the purity of the subsequently prepared lithium carbonate. At the same time, it also increased the cost of separating lithium from nickel, cobalt, and manganese. In Comparative Example 2, since ammonium sulfate was not introduced, the efficiency of concentrated sulfuric acid in converting lithium in the black powder to lithium sulfate was low, and the lithium leaching rate decreased from 95.33% to 72.53%. In Comparative Example 3, since concentrated sulfuric acid was not introduced, ammonium sulfate was difficult to convert lithium in the black powder to lithium sulfate in the low-temperature system, resulting in a low lithium leaching rate and high difficulty in preparing lithium carbonate from the leachate. The experimental results of Examples 1, 2, and 3 above also show that the introduction of ammonium sulfate enhances the sulfation transformation of lithium and can synergistically promote the conversion of lithium to lithium sulfate with concentrated sulfuric acid during the low-temperature sulfuric acid ripening process.

Claims

1. A method for preferentially extracting lithium from waste ternary lithium-ion battery powder, characterized in that, Includes the following steps: (1) Mix waste ternary lithium-ion battery powder with water, ammonium sulfate and concentrated sulfuric acid to form a slurry; wherein, the amount of concentrated sulfuric acid used is 0.8 to 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; (2) The slurry is subjected to a maturation treatment; wherein the maturation temperature is 100~250℃ and the maturation time is 0.5~2.5h; (3) Grind the material after maturation in step (2) and then soak it in water to obtain a lithium-containing solution and water-soaked residue.

2. The method for preferentially extracting lithium from waste ternary lithium-ion battery powder as described in claim 1, characterized in that, In step (1), the molar ratio of lithium to ammonium sulfate in the waste ternary lithium-ion battery powder is 1:0.1 to 1:0.

5.

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

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

6. The method for preferentially extracting lithium from waste ternary lithium-ion battery powder as described in any one of claims 1 to 5, characterized in that, Sodium hydroxide solution was added to the lithium-containing solution for precipitation and impurity removal. After filtration, saturated sodium carbonate solution was added to the filtrate and heated in a water bath. After the reaction was completed, the solution was filtered to obtain a white precipitate, which was then washed to obtain lithium carbonate.

7. The method for preferentially extracting lithium from waste ternary lithium-ion battery powder as described in claim 6, characterized in that, The water bath heating temperature is 80~95℃, and the heating time is 60~90min.

8. The method for preferentially extracting lithium from waste ternary lithium-ion battery powder as described in claim 6, characterized in that, The purity of the lithium carbonate is not less than 99%.

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