Method for selectively extracting lithium from waste lithium-ion battery powders by means of aluminum-carbon synergistic reduction

Abstract

Provided in the present disclosure is a method for selectively extracting lithium from waste lithium-ion battery powders by means of aluminum-carbon synergistic reduction, which method is characterized by comprising the following steps: S1, mixing a mixed solid consisting of waste battery powders, carbon powders and aluminum powders with an alcohol substance, ball-milling same, and then drying same, so as to obtain a ball-milled material; S2, roasting the ball-milled material, so as to obtain roasted residue; and S3, mixing water and the roasted residue, then introducing carbon dioxide for leaching, and performing solid-liquid separation, so as to obtain a selective lithium extraction liquid and lithium extraction residue.

Description

A method for selectively extracting lithium from waste lithium-ion battery powder by aluminum-carbon co-reduction Technical Field

[0001] The present invention relates to the field of waste lithium battery recycling, and in particular to a method for selectively extracting lithium from waste lithium-ion battery powder by aluminum-carbon co-reduction. Background Art

[0002] Since their commercialization by Sony in 1991, rechargeable lithium-ion batteries (LIBs) have been widely adopted worldwide due to their high specific energy, high voltage, and reversibility. Under the strategic goal of achieving carbon peak and carbon neutrality, the new energy industry has received strong support from national policies. Furthermore, according to statistics, lithium batteries currently account for 37% of the global rechargeable market, and their market share is expected to continue to rise as their applications continue to expand. The maximum charge and discharge cycle for a lithium battery is 1,000 cycles, meaning a large number of batteries will be scrapped as they expire. It is estimated that by 2025, the scrap volume of power lithium batteries in my country will reach 134.5 GWh. Because waste lithium batteries contain large amounts of heavy metals and toxic and hazardous substances, they pose significant potential environmental risks. However, a United Nations Programme report indicates that the current recycling rate for waste lithium batteries remains low. This has led to a rapid increase in the global supply of waste lithium batteries, creating significant environmental pressures. It also offers broad prospects for the recycling of valuable metal resources, highlighting their increasing economic value and environmental benefits. Taking effective recycling measures and policies can not only reduce dependence on raw mineral resources, but also help the world achieve dual carbon goals and environmental protection. It will also help to better stimulate consumer willingness, promote automobile consumption, cultivate and expand the development of the power battery recycling industry, and achieve a win-win situation in economic and social benefits.

[0003] Most traditional high-temperature pyrometallurgical processes for recycling lithium batteries can effectively recycle valuable metals Ni and Co, but most of the lithium is lost in the smelting slag during the smelting process, resulting in a low overall recovery rate of lithium. In addition, the pyrometallurgical process consumes a lot of energy, and the waste gas and waste residue generated can cause secondary pollution. Conventional wet treatment processes are difficult to achieve selective leaching of lithium, and the metal element composition in the leachate is complex. Further separation and purification steps are lengthy, the operation is difficult, and the loss of lithium is large, resulting in a low overall recovery rate. In order to improve the recovery rate of lithium, some researchers have proposed to preferentially separate lithium from waste batteries, simplify the subsequent separation and recovery steps of lithium, and thus reduce the loss of lithium. Although a single wet process can achieve selective recovery of lithium, it has strict requirements on the reaction process conditions, and because the selected reagents are expensive and used in large quantities, it is difficult to achieve economical and efficient recovery of lithium.

[0004] Considering the drawbacks of recycling lithium batteries using the above-mentioned single wet or pyrometallurgical processes, more and more researchers are conducting in-depth research on the combined pyrometallurgical and wet recycling process. However, there are still many problems in the related reported technologies. For example, the roasting process requires higher temperatures (usually 700-750°C) and longer times (usually more than 3 hours), making it difficult to promote and apply; when using coal powder as a reducing agent, the amount of reducing agent used in the reduction roasting stage is large, the cost is high, and the reduction roasting conditions are unfriendly; when using hydrogen as a reducing agent to treat waste lithium-ion battery powder, the utilization efficiency of hydrogen is low, the energy consumption is high, and there are also safety hazards; using aluminum powder as a reducing agent also has major safety hazards. Therefore, there is an urgent need to find an efficient, green, and low-energy consumption lithium-ion battery recycling process.

[0005] Summary of the Invention

[0006] The present disclosure aims to address at least one of the technical problems existing in the aforementioned prior art. To this end, the present disclosure proposes a method for selectively extracting lithium from waste lithium-ion battery powder using aluminum-carbon co-reduction. The aluminum-carbon co-reduction roasting process not only optimizes existing carbothermal or aluminothermic reduction processes for treating waste lithium batteries, making the process more economical and environmentally friendly, but also provides an important technical reference for pre-treatment and sorting of waste lithium batteries, such as aluminum and copper removal.

[0007] According to a first aspect of the present disclosure, a method for selectively extracting lithium from waste lithium-ion battery powder by aluminum-carbon co-reduction is proposed, comprising the following steps:

[0008] S1: mixing a solid mixture consisting of waste battery powder, carbon powder and aluminum powder with an alcohol substance, ball-milling the mixture, and then drying the mixture to obtain a ball-milled material;

[0009] S2: calcining the ball mill material to obtain calcined slag;

[0010] S3: mixing water with the roasted slag and introducing carbon dioxide to perform leaching, and obtaining a selective lithium extraction solution and lithium extraction slag after solid-liquid separation.

[0011] When aluminum is used alone for reduction and lithium extraction, there are certain safety hazards due to the high activity of aluminum and the high heat generated during the reaction. In addition, when the amount of aluminum is increased to achieve a better lithium extraction effect, lithium aluminate impurities will be produced subsequently. The reaction equation is as follows: Li2O+Al2O3→2LiAlO2. The solubility of the lithium aluminate generated under this reaction condition is not high, which will directly affect the lithium leaching rate. At the same time, the removal process of partially dissolved lithium aluminate is complicated, and the residual aluminum will also have a great impact on the performance of the battery. If carbon is used alone for reduction and lithium extraction, the amount of carbon required is large, and a higher roasting temperature and a longer time are required to achieve a better lithium extraction effect. The present invention adopts an aluminum-carbon synergistic reduction method for selective lithium extraction. The introduction of aluminum allows the reaction to start and continue at a lower temperature, converting nickel, cobalt and manganese into corresponding oxides. Carbon can then further react with the oxides, and nickel and cobalt are converted into elements, making the reaction more thorough and improving the lithium extraction rate. Furthermore, with the participation of carbon, lithium oxide preferentially reacts with generated carbon dioxide to form lithium carbonate, while aluminum reacts and converts to aluminum oxide. Through solid-liquid separation, a selective lithium extraction solution is obtained. Compared to the single carbothermic reduction or aluminothermic reduction methods used in existing technologies, the aluminum-carbon synergistic reduction method disclosed in this disclosure not only ensures good lithium extraction results, but also offers improved economic efficiency and safety.

[0012] In some embodiments, the waste battery powder is waste ternary lithium-ion battery powder. After selective lithium extraction, the nickel, cobalt, and manganese in the waste ternary lithium-ion battery powder are transferred to the lithium extraction slag, which is then directly used to prepare ternary cathode materials, thereby achieving good economic benefits.

[0013] In some embodiments, in step S1, the alcohol substance is ethanol.

[0014] In some embodiments, in step S1, the mass content of carbon powder in the mixed solid is 10% to 20%, the mass content of aluminum powder is 3% to 10%, and the liquid-to-solid ratio of the alcohol to the mixed solid is 3 to 5 mL / g. To achieve optimal lithium extraction results during aluminum-carbon synergistic reduction, the total amount of aluminum and carbon added is lower than the amount required when adding carbon alone.

[0015] In some embodiments, in step S2, the calcination is performed under an inert atmosphere.

[0016] In some embodiments, in step S2, the calcination temperature is 500-700°C; and / or the calcination time is 60-180 minutes. During the selective lithium extraction process by aluminum-carbon synergistic reduction, the calcination temperature and time are lower than when carbon is added alone.

[0017] The reaction equation of step S2 is as follows: 4LiNi 0.5 Co 0.2 Mn0.3 O2+C→2Li2O+2NiO+0.8CoO+1.2MnO+CO2 6LiNi 0.5 Co 0.2 Mn 0.3 O2+2Al→3Li2O+3NiO+1.2CoO+1.8MnO+Al2O3 NiO+C→Ni+CO2 CoO+C→Co+CO2 Li2O+CO2→Li2CO3

[0018] In some embodiments, in step S3, the liquid-to-solid ratio of water to calcined slag is (5-20):1 mL / g; and / or the flow rate of carbon dioxide is 100-500 mL / min; and / or the leaching time is 60-240 minutes; and / or the leaching temperature is 25-50° C. The carbon dioxide and water react with the lithium in the calcined slag to generate lithium bicarbonate, which is transferred to the liquid phase, achieving the effect of selective lithium extraction.

[0019] According to a second aspect of the present disclosure, a method for preparing lithium carbonate is proposed, comprising the steps of the method for selectively extracting lithium from waste lithium-ion battery powder by aluminum-carbon co-reduction as described in the first aspect of the present disclosure.

[0020] In some embodiments, the method for preparing lithium carbonate further comprises the following steps:

[0021] S4: mixing the selective lithium extraction solution with an acid solution to obtain a pre-lithium extraction solution;

[0022] S5: heating and mixing the pre-lithium extraction liquid and carbonate, and obtaining lithium carbonate solid after solid-liquid separation.

[0023] The main component of the selective lithium extraction solution is lithium bicarbonate. Heating the solution to completely decompose lithium bicarbonate requires considerable energy. By first reacting the solution with acid and then adding carbonate, solid lithium carbonate can be obtained more easily.

[0024] In some embodiments, the acid solution is sulfuric acid, the concentration of the sulfuric acid is 0.5-2.0 mol / L, and the molar ratio of the selective lithium extraction solution to the sulfuric acid is 2:1 to 1:3 in terms of lithium bicarbonate:sulfuric acid.

[0025] In some embodiments, the selective lithium extraction solution is further concentrated after being mixed with the acid solution.

[0026] In some embodiments, the lithium concentration in the pre-lithium extraction solution is 15-20 g / L; and / or, after the pre-lithium extraction solution is mixed with the carbonate, the carbonate concentration is 65-80 g / L, and the temperature of the heating and mixing is 80-100° C. Increasing the temperature can accelerate the precipitation process of lithium carbonate.

[0027] In some embodiments, the heating and mixing time is 30 to 120 minutes.

[0028] In some embodiments, step S5 further includes purifying the lithium carbonate solid, and the purification process is: dissolving the lithium carbonate solid in water, introducing carbon dioxide to react, separating the solid and liquid, and heating and decomposing to obtain purified lithium carbonate.

[0029] In some embodiments, during the purification process, the liquid-to-solid ratio of water to lithium carbonate solid is 5-10 mL / g.

[0030] In some embodiments, during the purification process, the flow rate of carbon dioxide is 100-500 mL / min, the heating temperature is 100-120° C., and the heating time is 2-3 hours. After purification, battery-grade lithium carbonate is obtained.

[0031] According to a third aspect of the present disclosure, a method for comprehensive recycling of waste lithium-ion battery powder is proposed, comprising the steps of the method for preparing lithium carbonate as described in the second aspect of the present disclosure.

[0032] In some embodiments, the method for comprehensive recycling of waste lithium-ion battery powder further comprises the following steps:

[0033] S6: The lithium extraction slag in step S3 is sequentially subjected to alkaline leaching and acid leaching.

[0034] In some embodiments, in step S6, the alkaline leaching uses a sodium hydroxide solution having a concentration of 0.5 to 2 mol / L and a liquid-to-solid ratio of the sodium hydroxide solution to the lithium extraction slag of approximately 5:1 mL / g. The aluminum is recovered by leaching the lithium extraction slag with the alkaline solution.

[0035] In some embodiments, in step S6, the alkali leaching process is performed under heating conditions, and the heating temperature is 25-50°C.

[0036] In some embodiments, in step S6, sulfuric acid is used for acid leaching, the concentration of the sulfuric acid is 1 to 3 mol / L, and the liquid-to-solid ratio of the sulfuric acid to the leached residue is about 10:1 mL / g.

[0037] In some embodiments, in step S6, hydrogen peroxide is further added during the acid leaching, wherein the mass concentration of the hydrogen peroxide is about 30%, and the hydrogen peroxide is added so that the hydrogen peroxide content in the solution is 20-40 g / L.

[0038] In some embodiments, in step S6, the acid leaching temperature is 50-80°C and the acid leaching time is 60-180 minutes. The leached residue after aluminum removal is subjected to oxidative acid leaching to extract the valuable metals therein, which are directly used in the subsequent preparation of the ternary cathode material.

[0039] In some embodiments, the method for comprehensive recycling of waste lithium-ion battery powder further comprises the following steps:

[0040] S7: After the acid leaching in step S6, a metal solution is obtained, and the lithium carbonate solid obtained in step S5 is used as raw materials to prepare a ternary positive electrode material LiNi x Co y Mn z O2.

[0041] In some embodiments, the specific steps of step S7 are as follows: the metal liquid is reduced with iron powder to remove copper, the pH value is adjusted to remove iron and aluminum, and then the calcium and magnesium are extracted to remove calcium and magnesium. Then, the ternary precursor Ni is synthesized by coprecipitation in a reactor according to the ratio of nickel, cobalt and manganese. x Co y Mn z (OH)2, the ternary precursor Ni x Co y Mn z (OH)2 and the lithium carbonate solid are mixed in a certain proportion and calcined in two stages, and then ground and sieved to prepare the ternary positive electrode material LiNi x Co y Mn z O2.

[0042] According to a fourth aspect of the present disclosure, a method for preparing a ternary lithium battery is proposed, comprising the steps of the methods described in the first, second and third aspects of the present disclosure.

[0043] According to the fifth aspect of the present disclosure, a lithium extraction method is proposed for use in the preparation of lithium carbonate, positive electrode materials or ternary lithium batteries, or in the comprehensive recovery of waste lithium-ion battery powder, including the method for selectively extracting lithium from waste lithium-ion battery powder by aluminum-carbon co-reduction as described in the first aspect of the present disclosure.

[0044] The present invention adopts a synergistic reduction roasting-wet extraction process to preferentially and selectively extract lithium from waste lithium-ion battery materials, and then leaches and extracts nickel, cobalt and manganese from the resulting lithium extraction slag. Finally, the recovered lithium is prepared into lithium carbonate, and the nickel, cobalt and manganese are prepared into a ternary precursor. The lithium carbonate and the ternary precursor are then used to synthesize lithium-ion battery positive electrode materials, thereby realizing the recovery and recycling of valuable metals in waste lithium batteries.

[0045] According to one embodiment of the present disclosure, there are at least the following beneficial effects:

[0046] (1) The present disclosure adopts a synergistic reduction roasting-water leaching method to achieve selective separation and extraction of lithium from waste battery powder. The reducing properties of carbon powder and aluminum powder carried by the battery powder itself are utilized to achieve the selective transformation of Li in the battery powder into Li2CO3, which can greatly reduce the amount of external reducing agent and has high economic value.

[0047] (2) The aluminum-carbon synergistic in-situ reduction roasting-leaching process disclosed in the present invention not only optimizes the existing carbon thermal reduction or aluminum thermal reduction process for treating waste lithium batteries, lowers the reaction temperature, and reduces the amount of reducing agent used, making the process more economical and environmentally friendly, but also provides an important technical reference for the early pretreatment and sorting process of waste lithium batteries, such as aluminum removal. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] The present disclosure is further described below with reference to the accompanying drawings and embodiments, wherein:

[0049] FIG1 is a process flow chart of a method for comprehensive recycling of waste lithium-ion battery powder according to Example 1 of the present disclosure;

[0050] FIG2 is an XRD pattern of battery-grade lithium carbonate prepared in Example 1 of the present disclosure;

[0051] Figure 3 shows the Ni prepared in Example 1 of the present disclosure. 0.5 Co 0.2 Mn 0.3 XRD pattern of (OH)2;

[0052] FIG4 is a LiNi prepared in Example 1 of the present disclosure 0.5 Co 0.2 Mn 0.3 XRD pattern of O2. DETAILED DESCRIPTION

[0053] The following will clearly and completely describe the concept and technical effects of the present disclosure in conjunction with embodiments to fully understand the purpose, features and effects of the present disclosure.

[0054] Example 1

[0055] A method for selectively extracting lithium from waste lithium-ion battery powder by aluminum-carbon co-reduction, comprising the following steps:

[0056] After disassembly, crushing, and screening, used ternary lithium batteries were pre-processed to obtain ternary battery powder. The Li, Ni, Co, Mn, C, and Al contents were 5.61%, 21.47%, 8.73%, 14.58%, 3.0%, and 0.27%, respectively. 500g of the used ternary battery powder was added to carbon powder and aluminum powder in a ratio that resulted in a solid mixture with carbon and aluminum contents of 10.0% and 10.0%, respectively. Anhydrous ethanol was then added to the mixture at a solid-liquid ratio of 1:3 g / mL to form a slurry. The mixture was then milled in a planetary ball mill at 200 rpm for 180 minutes. After milling, the milled material was removed and dried in a 100°C oven for later use. The dried material was spread flat in a crucible and placed in a high-sealed, high-temperature tube furnace. Argon was introduced as a protective gas and the calcination temperature was set at 650°C for 150 minutes. After calcination, the slag is ground into a fine powder to obtain the calcined slag. The calcined slag is added to a reactor, and pure water is added at a liquid-to-solid ratio of 10 mL / g. Carbon dioxide is introduced for selective leaching at a carbon dioxide flow rate of 500 mL / min, a leaching time of 240 minutes, and a leaching temperature of 40°C. The leached slurry is filtered and washed to obtain a selective lithium extraction solution and a preferential lithium extraction slag.

[0057] A method for preparing lithium carbonate further comprises the following steps:

[0058] The selective lithium extraction solution is mixed with 1.0 mol / L sulfuric acid at a molar ratio of 1:1 (calculated based on the molar amount of lithium bicarbonate in the lithium extraction solution) at room temperature and pressure to extract lithium for 120 minutes. After the lithium extraction is completed, the lithium extraction solution is concentrated to 15-20 g / L. Then, based on the reaction ratio of carbonate ion to lithium (1:2), a sodium carbonate solution is added at an excess of 5% to 10% of sodium carbonate for heating precipitation. After filtration, lithium carbonate solid is obtained. After purification of the lithium carbonate solid, pure battery-grade lithium carbonate can be obtained. The XRD pattern of the battery-grade lithium carbonate is shown in Figure 2.

[0059] The purification process involves dissolving lithium carbonate solid in pure water at a liquid-to-solid ratio of 10 mL / g, then introducing carbon dioxide at a flow rate of 300 mL / min for 2 hours at room temperature. After filtration, the filtrate is heated and decomposed at 100°C for 3 hours. After filtration and drying, battery-grade lithium carbonate is obtained.

[0060] A method for comprehensive recycling of waste lithium-ion battery powder further comprises the following steps:

[0061] Take the above-mentioned lithium-extracted slag and mix it with 1.0 mol / L sodium hydroxide solution for leaching, with a liquid-solid ratio of 5:1 mL / g, heat it to 50°C, and leach it for 120 minutes to remove aluminum. After aluminum removal, filter it and collect the filtrate containing NaAlO2 to recover aluminum; the leached slag after aluminum removal is mixed with sulfuric acid with a concentration of 2.0 mol / L, with a liquid-solid ratio of 10 mL / g, add 30% hydrogen peroxide to make its concentration in the solution 30 g / L, heat it to 80°C and leach it for 120 minutes to extract nickel, cobalt and manganese. Finally, the nickel, cobalt and manganese metal liquid is reduced with iron powder to remove copper, adjusted to remove iron and aluminum, and then extracted to remove calcium and magnesium. Then, according to the ratio of nickel, cobalt and manganese, the ternary precursor Ni is synthesized in the reactor by co-precipitation. 0.5 Co 0.2 Mn 0.3 (OH)2, the ternary precursor Ni 0.5 Co 0.2 Mn 0.3 (OH)2 and the lithium carbonate solid are mixed in a certain proportion and calcined in two stages, and then ground and sieved to prepare the ternary positive electrode material LiNi 0.5 Co 0.2 Mn 0.3 O2. Ni 0.5 Co 0.2 Mn 0.3 (OH)2 and LiNi 0.5 Co 0.2 Mn 0.3 The XRD patterns of O2 are shown in Figures 3 and 4, respectively.

[0062] In the above steps, after roasting to extract lithium, the leaching rates of Li, Ni, Co and Al are 95.5%, 0.55%, 0.63% and 0.57% respectively. After alkaline leaching, the extraction rate of Al is 96%. The extraction rates of Ni, Co and Mn are 97.0%, 98.0% and 95% respectively after sulfuric acid leaching of the alkaline leaching residue. The purity of the prepared lithium carbonate is 99.5%.

[0063] Example 2

[0064] A method for selectively extracting lithium from waste lithium-ion battery powder by aluminum-carbon co-reduction, comprising the following steps:

[0065] After disassembly, crushing, and screening, used ternary lithium batteries were pre-processed to obtain ternary battery powder. The Li, Ni, Co, Mn, C, and Al contents were 5.61%, 21.47%, 8.73%, 14.58%, 3.0%, and 0.27%, respectively. To 500g of the used ternary battery powder, carbon powder and aluminum powder were added in appropriate proportions to achieve a carbon and aluminum content of 20.0% and 3.0%, respectively. Anhydrous ethanol was then added to form a slurry at a solid-to-liquid ratio of 1:3 g / mL. The slurry was then milled in a planetary ball mill at 200 rpm for 180 minutes. After milling, the milled material was removed and dried in a 100°C oven for later use. The dried material was spread flat in a crucible and calcined in a sealed, high-temperature tube furnace with argon as the shielding gas at 650°C for 150 minutes. After calcination, the slurry was ground into a fine powder to obtain the calcined slag. The calcined slag was added to a reactor, and pure water was added at a liquid-to-solid ratio of 10 mL / g. Carbon dioxide was introduced for selective leaching at a carbon dioxide flow rate of 500 mL / min, a leaching time of 240 minutes, and a leaching temperature of 40°C. The leached slurry was filtered and washed to obtain a selective lithium extraction solution and preferential lithium extraction slag.

[0066] A method for preparing lithium carbonate further comprises the following steps:

[0067] The selective lithium extraction solution is mixed with 1.0 mol / L sulfuric acid at a molar ratio of 1:1 (calculated based on the molar amount of lithium bicarbonate in the lithium extraction solution) at room temperature and pressure to extract lithium for 120 minutes. After lithium extraction, the lithium extraction solution is concentrated to 15-20 g / L. Then, based on the reaction ratio of carbonate to lithium (1:2), a sodium carbonate solution with a 5% to 10% excess of sodium carbonate is added for heating and precipitation. Lithium carbonate solid is obtained after filtration. Purification of the lithium carbonate solid yields pure battery-grade lithium carbonate.

[0068] The purification process involves dissolving lithium carbonate solid in pure water at a liquid-to-solid ratio of 10 mL / g, then introducing carbon dioxide at a flow rate of 300 mL / min for 2 hours at room temperature. After filtration, the filtrate is heated and decomposed at 120°C for 2 hours. After filtration and drying, battery-grade lithium carbonate is obtained.

[0069] A method for comprehensive recycling of waste lithium-ion battery powder further comprises the following steps:

[0070] Take the above-mentioned lithium-extracted slag and mix it with 1.0 mol / L sodium hydroxide solution for leaching, with a liquid-solid ratio of 5:1 mL / g, heat it to 50°C, and leach it for 120 minutes to remove aluminum. After aluminum removal, filter it and collect the filtrate containing NaAlO2 to recover aluminum; the leached slag after aluminum removal is mixed with sulfuric acid with a concentration of 2.0 mol / L, with a liquid-solid ratio of 10 mL / g, add 30% hydrogen peroxide to make its concentration in the solution 30 g / L, heat it to 80°C and leach it for 120 minutes to extract nickel, cobalt and manganese. Finally, the nickel, cobalt and manganese metal liquid is reduced with iron powder to remove copper, adjusted to remove iron and aluminum, and then extracted to remove calcium and magnesium. Then, according to the ratio of nickel, cobalt and manganese, the ternary precursor Ni is synthesized in the reactor by co-precipitation. 0.5 Co 0.2 Mn 0.3 (OH)2, the ternary precursor Ni 0.5 Co 0.2 Mn 0.3 (OH)2 and the lithium carbonate solid are mixed in a certain proportion and calcined in two stages, and then ground and sieved to prepare the ternary positive electrode material LiNi 0.5 Co 0.2 Mn 0.3 O2.

[0071] In the above steps, after roasting to extract lithium, the leaching rates of Li, Ni, Co and Al are 96%, 0.48%, 0.56% and 0.52% respectively. After alkaline leaching, the extraction rate of Al is 97%. The extraction rates of Ni, Co and Mn are 98.0%, 97.0% and 96% respectively after sulfuric acid leaching of the alkaline leaching residue. The purity of the prepared lithium carbonate is 99.6%.

[0072] Example 3

[0073] A method for selectively extracting lithium from waste lithium-ion battery powder by aluminum-carbon co-reduction, comprising the following steps:

[0074] After disassembly, crushing, and screening, used ternary lithium batteries were pre-processed to obtain ternary battery powder. The Li, Ni, Co, Mn, C, and Al contents were 5.61%, 21.47%, 8.73%, 14.58%, 3.0%, and 0.27%, respectively. To 500g of the used ternary battery powder, carbon powder and aluminum powder were added in appropriate proportions to achieve a solid mixture with carbon and aluminum contents of 15.0% and 7.0%, respectively. Anhydrous ethanol was then added to form a slurry at a solid-to-liquid ratio of 1:3 g / mL. The mixture was then milled in a planetary ball mill at 200 rpm for 180 minutes. After milling, the milled material was removed and dried in a 100°C oven for later use. The dried material was spread flat in a crucible and calcined in a sealed, high-temperature tube furnace with argon as the shielding gas at 600°C for 150 minutes. After calcination, it was ground into a fine powder to obtain slag. The calcined slag was added to a reactor, and pure water was added at a liquid-to-solid ratio of 10 mL / g. Carbon dioxide was introduced for selective leaching at a carbon dioxide flow rate of 500 mL / min, a leaching time of 240 minutes, and a leaching temperature of 40°C. The leached slurry was filtered and washed to obtain a selective lithium extraction solution and preferential lithium extraction slag.

[0075] A method for preparing lithium carbonate further comprises the following steps:

[0076] The selective lithium extraction solution is mixed with 1.0 mol / L sulfuric acid at a molar ratio of 1:1 (calculated based on the molar amount of lithium bicarbonate in the lithium extraction solution) at room temperature and pressure to extract lithium for 120 minutes. After lithium extraction, the lithium extraction solution is concentrated to 15-20 g / L. Then, based on the reaction ratio of carbonate to lithium (1:2), a sodium carbonate solution with a 5% to 10% excess of sodium carbonate is added for heating and precipitation. Lithium carbonate solid is obtained after filtration. Purification of the lithium carbonate solid yields pure battery-grade lithium carbonate.

[0077] The purification process involves dissolving lithium carbonate solid in pure water at a liquid-to-solid ratio of 10 mL / g, then introducing carbon dioxide at a flow rate of 300 mL / min for 2 hours at room temperature. After filtration, the filtrate is heated and decomposed at 100°C for 3 hours. After filtration and drying, battery-grade lithium carbonate is obtained.

[0078] A method for comprehensive recycling of waste lithium-ion battery powder further comprises the following steps:

[0079] Take the above-mentioned lithium-extracted slag and mix it with 1.0 mol / L sodium hydroxide solution for leaching, with a liquid-solid ratio of 5:1 mL / g, heat it to 50°C, and leach it for 120 minutes to remove aluminum. After aluminum removal, filter it and collect the filtrate containing NaAlO2 to recover aluminum; the leached slag after aluminum removal is mixed with sulfuric acid with a concentration of 2.0 mol / L, with a liquid-solid ratio of 10 mL / g, add 30% hydrogen peroxide to make its concentration in the solution 30 g / L, heat it to 80°C and leach it for 120 minutes to extract nickel, cobalt and manganese. Finally, the nickel, cobalt and manganese metal liquid is reduced with iron powder to remove copper, adjusted to remove iron and aluminum, and then extracted to remove calcium and magnesium. Then, according to the ratio of nickel, cobalt and manganese, the ternary precursor Ni is synthesized in the reactor by co-precipitation. 0.5 Co 0.2 Mn 0.3 (OH)2, the ternary precursor Ni 0.5 Co 0.2 Mn 0.3 (OH)2 and the lithium carbonate solid are mixed in a certain proportion and calcined in two stages, and then ground and sieved to prepare the ternary positive electrode material LiNi 0.5 Co 0.2 Mn 0.3 O2.

[0080] In the above steps, after roasting to extract lithium, the leaching rates of Li, Ni, Co, and Al are 97.8%, 0.52%, 0.43%, and 0.56%, respectively. After alkaline leaching, the extraction rate of Al is 97%. The extraction rates of Ni, Co, and Mn are 98.0%, 98.0%, and 96%, respectively, after sulfuric acid leaching of the alkaline leaching residue. The purity of the prepared lithium carbonate is 99.8%.

[0081] Comparative Example 1

[0082] A method for selectively extracting lithium from waste lithium-ion battery powder by aluminum-carbon co-reduction, comprising the following steps:

[0083] After disassembly, crushing, and screening, used ternary lithium batteries were pre-processed to obtain ternary battery powder. The Li, Ni, Co, Mn, C, and Al contents were 5.61%, 21.47%, 8.73%, 14.58%, 3.0%, and 0.27%, respectively. 500g of the used ternary battery powder was mixed with aluminum powder in a proportioned ratio to achieve an aluminum content of 20.0%. Anhydrous ethanol was then added to the mixture at a solid-to-liquid ratio of 1:3 g / mL to form a slurry. The mixture was then milled in a planetary ball mill at 200 rpm for 180 minutes. After milling, the milled material was removed and dried in a 100°C oven for later use. The dried material was spread flat in a crucible and calcined in a high-sealed, high-temperature tubular furnace with argon as the shielding gas at 650°C for 150 minutes. After calcination, the powder was ground into a fine powder to obtain slag. The calcined slag was added to a reactor, and pure water was added at a liquid-to-solid ratio of 10 mL / g. Carbon dioxide was introduced for selective leaching at a carbon dioxide flow rate of 500 mL / min, a leaching time of 240 minutes, and a leaching temperature of 40°C. The leached slurry was filtered and washed to obtain a selective lithium extraction solution and preferential lithium extraction slag.

[0084] A method for preparing lithium carbonate further comprises the following steps:

[0085] The selective lithium extraction solution is mixed with 1.0 mol / L sulfuric acid at a molar ratio of 1:1 (calculated based on the molar amount of lithium bicarbonate in the lithium extraction solution) at room temperature and pressure to extract lithium for 120 minutes. After lithium extraction, the lithium extraction solution is concentrated to 15-20 g / L. Then, based on the reaction ratio of carbonate to lithium (1:2), sodium carbonate solution is added with a 5% to 10% excess of carbonate for heating and precipitation. Lithium carbonate solid is obtained after filtration. Purification of the lithium carbonate solid yields pure battery-grade lithium carbonate.

[0086] The purification process involves dissolving lithium carbonate solid in pure water at a liquid-to-solid ratio of 10 mL / g, then introducing carbon dioxide at a flow rate of 300 mL / min for 2 hours at room temperature. After filtration, the filtrate is heated and decomposed at 100°C for 3 hours. After filtration and drying, battery-grade lithium carbonate is obtained.

[0087] A method for comprehensive recycling of waste lithium-ion battery powder further comprises the following steps:

[0088] Take the above-mentioned lithium-extracted slag and mix it with 1.0 mol / L sodium hydroxide solution for leaching, with a liquid-solid ratio of 5:1 mL / g, heat it to 50°C, and leach it for 120 minutes to remove aluminum. After aluminum removal, filter it and collect the filtrate containing NaAlO2 to recover aluminum; the leached slag after aluminum removal is mixed with sulfuric acid with a concentration of 2.0 mol / L, with a liquid-solid ratio of 10 mL / g, add 30% hydrogen peroxide to make its concentration in the solution 30 g / L, heat it to 80°C and leach it for 120 minutes to extract nickel, cobalt and manganese. Finally, the nickel, cobalt and manganese metal liquid is reduced with iron powder to remove copper, adjusted to remove iron and aluminum, and then extracted to remove calcium and magnesium. Then, according to the ratio of nickel, cobalt and manganese, the ternary precursor Ni is synthesized in the reactor by co-precipitation. 0.5 Co 0.2 Mn 0.3 (OH)2, the ternary precursor Ni 0.5 Co 0.2 Mn 0.3 (OH)2 and the lithium carbonate solid are mixed in a certain proportion and calcined in two stages, and then ground and sieved to prepare the ternary positive electrode material LiNi 0.5 Co 0.2 Mn 0.3 O2.

[0089] In the above steps, after calcination and lithium extraction, the leaching rates of Li, Ni, Co, and Al were 67.8%, 0.85%, 0.73%, and 0.76%, respectively. After alkaline leaching, the extraction rate of Al was 80%. Sulfuric acid leaching of the alkaline leaching residue yielded extraction rates of Ni, Co, and Mn of 90.0%, 88.0%, and 91%, respectively. The prepared lithium carbonate had a purity of 99.6%. Adding aluminum powder alone for calcination and lithium extraction lacked further reaction between carbon and battery powder, resulting in poor lithium extraction results.

[0090] Comparative Example 2

[0091] A method for selectively extracting lithium from waste lithium-ion battery powder by aluminum-carbon co-reduction, comprising the following steps:

[0092] After disassembly, crushing, and screening, used ternary lithium batteries were pre-processed to obtain ternary battery powder. The Li, Ni, Co, Mn, C, and Al contents were 5.61%, 21.47%, 8.73%, 14.58%, 3.0%, and 0.27%, respectively. 500g of the used ternary battery powder was mixed with carbon powder in a proportioned ratio to achieve a carbon content of 30.0%. Anhydrous ethanol was then added to the mixture at a solid-to-liquid ratio of 1:3 g / mL to form a slurry. The mixture was then milled in a planetary ball mill at 200 rpm for 180 minutes. After milling, the milled material was removed and dried in a 100°C oven for later use. The dried material was spread flat in a crucible and calcined in a sealed, high-temperature tube furnace with argon as the shielding gas at 650°C for 150 minutes. After calcination, the powder was ground into a fine powder to obtain the calcined slag. The calcined slag was added to a reactor, and pure water was added at a liquid-to-solid ratio of 10 mL / g. Carbon dioxide was introduced for selective leaching at a carbon dioxide flow rate of 500 mL / min, a leaching time of 240 minutes, and a leaching temperature of 40°C. The leached slurry was filtered and washed to obtain a selective lithium extraction solution and preferential lithium extraction slag.

[0093] A method for preparing lithium carbonate further comprises the following steps:

[0094] The selective lithium extraction solution is mixed with 1.0 mol / L sulfuric acid at a molar ratio of 1:1 (calculated based on the molar amount of lithium bicarbonate in the lithium extraction solution) at room temperature and pressure to extract lithium for 120 minutes. After lithium extraction, the lithium extraction solution is concentrated to 15-20 g / L. Then, based on the reaction ratio of carbonate to lithium (1:2), sodium carbonate solution is added with a 5% to 10% excess of carbonate for heating and precipitation. Lithium carbonate solid is obtained after filtration. Purification of the lithium carbonate solid yields pure battery-grade lithium carbonate.

[0095] The purification process involves dissolving lithium carbonate solid in pure water at a liquid-to-solid ratio of 10 mL / g, then introducing carbon dioxide at a flow rate of 300 mL / min for 2 hours at room temperature. After filtration, the filtrate is heated and decomposed at 100°C for 3 hours. After filtration and drying, battery-grade lithium carbonate is obtained.

[0096] A method for comprehensive recycling of waste lithium-ion battery powder further comprises the following steps:

[0097] Take the above-mentioned lithium-extracted slag and mix it with 1.0 mol / L sodium hydroxide solution for leaching, with a liquid-solid ratio of 5:1 mL / g, heat it to 50°C, and leach it for 120 minutes to remove aluminum. After aluminum removal, filter it and collect the filtrate containing NaAlO2 to recover aluminum; the leached slag after aluminum removal is mixed with sulfuric acid with a concentration of 2.0 mol / L, with a liquid-solid ratio of 10 mL / g, add 30% hydrogen peroxide to make its concentration in the solution 30 g / L, heat it to 80°C and leach it for 120 minutes to extract nickel, cobalt and manganese. Finally, the nickel, cobalt and manganese metal liquid is reduced with iron powder to remove copper, adjusted to remove iron and aluminum, and then extracted to remove calcium and magnesium. Then, according to the ratio of nickel, cobalt and manganese, the ternary precursor Ni is synthesized in the reactor by co-precipitation. 0.5 Co 0.2 Mn 0.3 (OH)2, the ternary precursor Ni 0.5 Co 0.2 Mn 0.3 (OH)2 and the lithium carbonate solid are mixed in a certain proportion and calcined in two stages, and then ground and sieved to prepare the ternary positive electrode material LiNi 0.5 Co 0.2 Mn 0.3 O2.

[0098] In the above steps, after calcination and lithium extraction, the leaching rates of Li, Ni, Co, and Al were 88.0%, 0.80%, 0.63%, and 0.7%, respectively. After alkaline leaching, the Al extraction rate was 92%. Sulfuric acid leaching of the alkaline leached residue yielded Ni, Co, and Mn extraction rates of 92.0%, 92.0%, and 91%, respectively, resulting in a lithium carbonate with a purity of 99.5%. Carbothermal reduction alone was less effective in lithium extraction under the above calcination conditions.

[0099] Comparative Example 3

[0100] A method for selectively extracting lithium from waste lithium-ion battery powder by aluminum-carbon co-reduction, comprising the following steps:

[0101] After disassembly, crushing, and screening, used ternary lithium batteries were pre-processed to obtain ternary battery powder. The Li, Ni, Co, Mn, C, and Al contents were 5.61%, 21.47%, 8.73%, 14.58%, 3.0%, and 0.27%, respectively. To 500g of the used ternary battery powder, carbon powder and aluminum powder were added in appropriate proportions to achieve a carbon and aluminum content of 15.0% and 1.5%, respectively. Anhydrous ethanol was then added to the mixture at a solid-to-liquid ratio of 1:3 g / mL to form a slurry. The mixture was then milled in a planetary ball mill at 200 rpm for 180 minutes. After milling, the milled material was removed and dried in a 100°C oven for later use. The dried material was spread flat in a crucible and calcined in a high-sealed, high-temperature tube furnace with argon as the shielding gas at 650°C for 150 minutes. After calcination, the mixture was ground into a fine powder to obtain slag. The calcined slag was added to a reactor, and pure water was added at a liquid-to-solid ratio of 10 mL / g. Carbon dioxide was introduced for selective leaching at a carbon dioxide flow rate of 500 mL / min, a leaching time of 240 minutes, and a leaching temperature of 40°C. The leached slurry was filtered and washed to obtain a selective lithium extraction solution and preferential lithium extraction slag.

[0102] A method for preparing lithium carbonate further comprises the following steps:

[0103] The selective lithium extraction solution is mixed with 1.0 mol / L sulfuric acid at a molar ratio of 1:1 (calculated based on the molar amount of lithium bicarbonate in the lithium extraction solution) at room temperature and pressure to extract lithium for 120 minutes. After lithium extraction, the lithium extraction solution is concentrated to 15-20 g / L. Then, based on the reaction ratio of carbonate to lithium (1:2), sodium carbonate solution is added with a 5% to 10% excess of carbonate for heating and precipitation. Lithium carbonate solid is obtained after filtration. Purification of the lithium carbonate solid yields pure battery-grade lithium carbonate.

[0104] The purification process involves dissolving lithium carbonate solid in pure water at a liquid-to-solid ratio of 10 mL / g, then introducing carbon dioxide at a flow rate of 300 mL / min for 2 hours at room temperature. After filtration, the filtrate is heated and decomposed at 100°C for 3 hours. After filtration and drying, battery-grade lithium carbonate is obtained.

[0105] A method for comprehensive recycling of waste lithium-ion battery powder further comprises the following steps:

[0106] Take the above-mentioned lithium-extracted slag and mix it with 1.0 mol / L sodium hydroxide solution for leaching, with a liquid-solid ratio of 5:1 mL / g, heat it to 50°C, and leach it for 120 minutes to remove aluminum. After aluminum removal, filter it and collect the filtrate containing NaAlO2 to recover aluminum; the leached slag after aluminum removal is mixed with sulfuric acid with a concentration of 2.0 mol / L, with a liquid-solid ratio of 10 mL / g, add 30% hydrogen peroxide to make its concentration in the solution 30 g / L, heat it to 80°C and leach it for 120 minutes to extract nickel, cobalt and manganese. Finally, the nickel, cobalt and manganese metal liquid is reduced with iron powder to remove copper, adjusted to remove iron and aluminum, and then extracted to remove calcium and magnesium. Then, according to the ratio of nickel, cobalt and manganese, the ternary precursor Ni is synthesized in the reactor by co-precipitation. 0.5 Co 0.2 Mn 0.3 (OH)2, the ternary precursor Ni 0.5 Co 0.2 Mn 0.3 (OH)2 and the lithium carbonate solid are mixed in a certain proportion and calcined in two stages, and then ground and sieved to prepare the ternary positive electrode material LiNi 0.5 Co 0.2 Mn 0.3 O2.

[0107] In the above steps, after calcination and lithium extraction, the leaching rates of Li, Ni, Co, and Al were 87.0%, 0.77%, 0.56%, and 0.67%, respectively. Al extraction after alkaline leaching reached 94%, and the extraction rates of Ni, Co, and Mn from the alkaline leaching residue were 92.0%, 93.0%, and 92%, respectively. The prepared lithium carbonate had a purity of 99.5%. The low amount of aluminum powder added meant that it preferentially reacted with only a small portion of the battery powder during calcination, resulting in poor overall lithium extraction.

Claims

1. A method for selectively extracting lithium from waste lithium-ion battery powder by aluminum-carbon coordinated reduction, characterized in that: The following steps are involved: S1: mixing a mixed solid consisting of waste battery powder, carbon powder and aluminum powder with an alcohol substance, ball milling the mixture, and then drying the mixture to obtain a ball milling material; S2: calcining the ball mill material to obtain calcined slag; S3: mixing water with the roasted slag and introducing carbon dioxide to perform leaching, and obtaining a selective lithium extraction solution and lithium extraction slag after solid-liquid separation.

2. The method according to claim 1, characterized in that The waste battery powder is waste ternary lithium-ion battery powder.

3. The method according to claim 1, characterized in that In step S1, the mass content of carbon powder in the mixed solid is 10% to 20%, and the mass content of aluminum powder is 3% to 10%; and / or the liquid-to-solid ratio of the alcohol substance to the mixed solid is (3 to 5): 1 mL / g.

4. The method according to claim 1, characterized in that: In step S2, the calcination temperature is 500-700°C; and / or the calcination time is 60-180 minutes.

5. The method according to claim 1, characterized in that In step S3, the liquid-to-solid ratio of water to roasted slag is (5-20): 1 mL / g; and / or the flow rate of the carbon dioxide is 100-500 mL / min; and / or the leaching time is 60-240 min; and / or the leaching temperature is 25-50° C.

6. A method for preparing lithium carbonate, characterized in that: The method comprises the steps of any one of claims 1 to 5.

7. The method according to claim 6, characterized in that The following steps are also included: S4: mixing the obtained selective lithium extraction solution with an acid solution to obtain a pre-lithium extraction solution; S5: heating and mixing the pre-lithium extraction liquid and carbonate, and obtaining lithium carbonate solid after solid-liquid separation.

8. The method according to claim 7, characterized in that The acid solution is sulfuric acid, the concentration of the sulfuric acid is 0.5-2.0 mol / L, and the molar ratio of the selective lithium extraction solution to the sulfuric acid is 2:1-1:3 in terms of lithium bicarbonate:sulfuric acid.

9. The method according to claim 7, characterized in that: The concentration of lithium in the pre-lithium extraction solution is 15-20 g / L; and / or, after the pre-lithium extraction solution is mixed with carbonate, the concentration of carbonate ions is 65-80 g / L; and / or, the temperature of the heating and mixing is 80-100°C.

10. The method according to claim 7, characterized in that Step S5 also includes purifying the lithium carbonate solid. The purification process is as follows: dissolving the lithium carbonate solid in water, introducing carbon dioxide to react, separating the solid and the liquid, and heating and decomposing the solid to obtain purified lithium carbonate.

11. A method for comprehensive recycling of waste lithium-ion battery powder, characterized in that: The method comprises the steps of any one of claims 6 to 10.

12. The method according to claim 11, characterized in that The following steps are also included: S6: The lithium extraction slag obtained in step S3 is subjected to alkaline leaching and acid leaching in sequence.

13. The method according to claim 12, characterized in that In step S6, the alkaline leaching uses a sodium hydroxide solution, the concentration of the sodium hydroxide solution is 0.5-2 mol / L, and the liquid-to-solid ratio of the sodium hydroxide solution to the lithium extraction slag is about 5:1 mL / g.

14. The method according to claim 12, characterized in that In step S6, the alkali leaching process is carried out under heating conditions, and the heating temperature is 25-50°C.

15. The method according to claim 12, characterized in that In step S6, sulfuric acid is used for acid leaching, the concentration of the sulfuric acid is 1-3 mol / L, and the liquid-to-solid ratio of the sulfuric acid to the leached residue is about 10:1 mL / g.

16. A method for preparing a ternary lithium battery, comprising the steps of the method described in any one of claims 1 to 15.

17. Application of a lithium extraction method in the preparation of lithium carbonate, positive electrode materials or ternary lithium batteries, or in the comprehensive recovery of waste lithium ion battery powder, characterized in that: The lithium extraction method includes the method for selectively extracting lithium from waste lithium-ion battery powder by aluminum-carbon co-reduction as described in any one of claims 1 to 5.

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