A precursor solution, its preparation method, and a method for recovering valuable metals.

Abstract

This invention belongs to the field of valuable metal recycling, specifically relating to a precursor solution, a preparation method, and a method for recycling valuable metals. The precursor solution includes valuable metal ions, chloride ions, and sulfate ions from the raw material to be recycled. The raw material to be recycled is lithium-containing waste battery cathode material. The valuable metal ions include lithium ions and transition metal ions. The molar number of sulfate ions does not exceed 0.55 times the molar number of lithium ions. This invention can effectively improve the lithium recovery rate and the separation rate of lithium from other metal elements.

Description

Technical Field

[0001] This invention belongs to the field of valuable metal recovery, specifically relating to a precursor solution, its preparation method, and a method for recovering valuable metals. Background Technology

[0002] Lithium-ion batteries, due to their high specific capacity and long cycle life, have been widely used in the consumer battery market and occupy a major share of the power battery market in the electric vehicle sector. It is estimated that the cumulative potential demand for lithium batteries from 2020 to 2060 will reach 25 TWh. If 1 GWh of batteries corresponds to approximately 600 tons of lithium carbonate, then the demand for lithium carbonate would be approximately 15 million tons. With the vigorous development of new energy vehicles, the demand for lithium, nickel, cobalt, and manganese, key components of ternary cathode materials, has increased significantly. At the same time, a large number of discarded lithium-ion batteries have been phased out, resulting in both resource waste and environmental pollution. Considering environmental factors, resource constraints, and the price of key components, the recycling of discarded lithium-ion batteries is a necessary undertaking.

[0003] Chinese patent document CN 112652807 A discloses a method for selectively recovering lithium from spent lithium-ion battery cathode materials using Lewis acids. The method involves mixing and calcining the spent lithium-ion battery cathode material with Lewis acids, causing lithium ions to form soluble lithium salts that are extracted from the cathode material. The lithium salts are then leached and precipitated using a neutral solution. While this method has a short overall recovery process, the Lewis acids used are transition metal halides, transition metal sulfates, and transition metal nitrates, which are not only costly and difficult to treat in subsequent wastewater treatment, but also prone to environmental pollution.

[0004] Patent application CN 113278805 A discloses a method for roasting ammonium sulfate, followed by water leaching of the roasted product. After leaching, the product is filtered and separated to obtain a lithium-rich leachate and a transition metal slag phase, thus achieving a high recovery rate of precious metals. Although this low-temperature acid roasting method achieves a high recovery rate, its separation rate is low, meaning the resulting leachate contains a high content of impurity ions. This necessitates complex impurity removal methods to obtain a high-purity target product, and the wastewater generated during the impurity removal process causes significant environmental pollution. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide a precursor solution, a preparation method and a valuable metal recovery method, which can effectively improve the recovery rate of lithium and the separation rate of lithium from other metal elements.

[0006] This invention provides a precursor solution comprising valuable metal ions, chloride ions, and sulfate ions from raw materials to be recycled. The raw materials to be recycled are lithium-containing waste battery cathode materials. The valuable metal ions include lithium ions and transition metal ions. The molar number of sulfate ions does not exceed 0.55 times the molar number of lithium ions.

[0007] Preferably, the molar ratio of sulfate ions to lithium ions is 0.1 to 0.55:1. More preferably, the molar ratio of sulfate ions to lithium ions is 0.45 to 0.55:1, and even more preferably, 0.5:1.

[0008] Preferably, the number of moles of chloride ions is more than 1 times the number of moles of total transition metal ions. Preferably, the molar ratio of chloride ions to total transition metal ions is 1 to 3:1, more preferably 2 to 3:1, and even more preferably 2:1.

[0009] Lithium-containing waste battery cathode materials include, but are not limited to, one or more mixtures of lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide. They are typically cathode materials for nickel-cobalt manganese ternary batteries, nickel-cobalt aluminum ternary batteries, or nickel-cobalt manganese aluminum quaternary batteries.

[0010] The precursor solution of the present invention preferably also includes an appropriate amount of transition metal ions that meet the content ratio of the target battery cathode material.

[0011] This invention provides a method for preparing a precursor solution, comprising the steps of mixing a chloride solution of the raw material to be recovered with an acid or salt containing sulfate to obtain a precursor solution.

[0012] After mixing, it is preferable to add an appropriate amount of transition metal salt so that the proportion of transition metal meets the target battery cathode material content ratio.

[0013] Preferably, the method for preparing the chloride solution of the raw material to be recycled is as follows: the raw material to be recycled is mixed with ammonium chloride, subjected to chlorination roasting, and then separated into solid and liquid components after water leaching to obtain the chloride solution; or, the raw material to be recycled is mixed with hydrochloric acid to obtain the chloride solution.

[0014] Preferably, the raw materials to be recycled are first crushed. Chlorination roasting is carried out directly in an air atmosphere.

[0015] Chlorination roasting causes the raw materials to be recycled to undergo a solid-phase reaction with the cathode material under certain temperature conditions. The LiO bonds and MO bonds (M represents the transition metals in the cathode material, such as Ni, Co, and Mn) are broken, and lithium ions and transition metal ions are converted into soluble chloride salts. The metal ions can be directly enriched into the aqueous solution by simple water leaching, so that lithium, nickel, cobalt, and manganese in the raw materials to be recycled all enter the liquid phase.

[0016] When the raw materials to be recycled are mixed with hydrochloric acid, the positive electrode powder can be directly digested without the need for calcination and water leaching steps. Preferably, in addition to hydrochloric acid, sulfuric acid or sulfate can also be added during mixing, so that sulfuric acid or sulfate can be omitted in subsequent steps.

[0017] The present invention involves mixing the chloride solution of the raw material to be recycled with an acid or salt containing sulfate ions. This includes adding the acid or salt containing sulfate ions during the preparation of the chloride solution of the raw material to be recycled, and both of these are within the scope of protection of this application.

[0018] Before the raw materials to be recycled are mixed with ammonium chloride or hydrochloric acid, the raw materials to be recycled are first activated at 500-600°C to separate the positive electrode powder from the current collector aluminum foil; the molar ratio of ammonium chloride or hydrochloric acid to lithium in the raw materials to be recycled is 2-4:1, more preferably 3:1; the chlorination roasting temperature is 200-400°C, more preferably 300°C, and the roasting time is 30-180 min, more preferably 30 min; the water immersion temperature is 20-80°C, and the time is 10-60 min; the sulfate-containing acid or salt includes, but is not limited to, one or more mixtures of sulfuric acid, ammonium sulfate, ammonium bisulfate, sodium sulfate, nickel sulfate, cobalt sulfate, and manganese sulfate.

[0019] A precursor solution is obtained by adding an appropriate amount of transition metal salt to ensure the transition metal ratio meets the content ratio of the positive electrode material in the battery. This means that, for example, in the case of nickel-cobalt-manganese (NiCoMn) ternary batteries, some metal is usually lost during the recycling of spent NiCoMn batteries. Therefore, adding an appropriate amount of NiCoMn metal ensures that the NiCoMn content meets the content ratio of the target NiCoMn ternary battery, thus allowing the resulting precursor solution to be used in the preparation of NiCoMn ternary batteries. The amount of material added is determined by the difference between the NiCoMn content in the positive electrode material of a new NiCoMn ternary battery and the NiCoMn content in the positive electrode material of a spent NiCoMn ternary battery. The added substance is in the form of a metal chloride or sulfate; for NiCoMn ternary batteries, this is nickel chloride, cobalt chloride, and manganese chloride, or nickel sulfate, cobalt sulfate, and manganese sulfate.

[0020] Preferably, before mixing the raw materials to be recycled with ammonium chloride, the raw materials to be recycled are first activated. The activation temperature is preferably 500-600℃, more preferably 550℃, and the activation time is 60-90 minutes, preferably 60 minutes. This invention has found that when the activation temperature is <500℃, it is difficult to completely decompose the binders, etc.; when the activation temperature is >600℃, energy consumption increases, and the material's activity is easily lost, which is detrimental to subsequent operations.

[0021] After activation, the material is sieved to remove the current collector, yielding the raw material to be recycled. The purpose of activation is to remove the current collector (aluminum foil, copper foil, copper wire, etc.) and binders from the battery positive electrode material, causing the organic matter to decompose. After sieving, the raw material to be recycled can be obtained.

[0022] This invention provides a method for recovering valuable metals, comprising the following steps: heating the precursor solution to obtain pyrolysis products, then leaching the pyrolysis products with water and separating the solid and liquid components to obtain a lithium sulfate solution and an oxide precursor.

[0023] Preferably, the heating is spray pyrolysis. Preferably, the heating or spray pyrolysis temperature is 500–850°C, more preferably 650–850°C, and if spray pyrolysis is performed, the gas flow rate is preferably 10 L / min.

[0024] Through spray pyrolysis, transition metal chlorides are converted into oxides, while lithium remains in the form of lithium sulfate. Due to the good solubility of lithium sulfate, it can be directly leached with water to obtain a lithium sulfate solution and an oxide filter cake, which serves as the precursor for the resulting oxide.

[0025] Preferably, before water leaching of the pyrolysis products, a secondary roasting step is included, wherein the secondary roasting temperature is 450–600°C and the secondary roasting time is 1–60 minutes. Preferably, the secondary roasting temperature is 500°C and the secondary roasting time is 1 minute.

[0026] Alternatively, the pyrolysis products can be leached with water, and after solid-liquid separation, the lithium sulfate solution can be purified by adding lithium hydroxide or sodium hydroxide. The ratio of the molar amount of lithium hydroxide or sodium hydroxide to the sum of the molar amounts of other metals (mainly nickel, cobalt, and manganese) in the lithium sulfate solution is 2.05 to 2.2:1.

[0027] The secondary roasting or impurity removal operation of this invention is to eliminate the influence of impurities on the results. Only one of these operations needs to be performed, or both operations can be performed simultaneously. Preferably, the water leaching temperature is 20–80°C, more preferably 70°C, and the time is 10–60 min, preferably 60 min.

[0028] Preferably, the lithium sulfate solution undergoes a lithium precipitation reaction to obtain lithium carbonate.

[0029] The lithium precipitation reaction is carried out by mixing lithium sulfate solution and sodium carbonate solution, and the reaction temperature is 60-100℃, more preferably 85℃.

[0030] Preferably, lithium carbonate and an oxide precursor are mixed and calcined to obtain a new cathode material. The stoichiometric ratio of the oxide precursor to lithium carbonate, the calcination temperature, and the calcination time can be adjusted according to the requirements of the final synthesized cathode material.

[0031] The beneficial effects of this invention are that it effectively separates lithium and transition metals. Transition metal chlorides are converted into metal oxides through pyrolysis, while lithium exists in the form of lithium sulfate. This not only effectively improves the lithium recovery rate and purity, but also allows the leached oxide filter cake to be directly prepared as a cathode material. In this invention, the degree of transition metal conversion to metal oxides during pyrolysis is high, resulting in high lithium extraction selectivity, and the purity of the recovered lithium carbonate powder is not less than 98.5 wt%.

[0032] For nickel-cobalt-manganese ternary batteries, this invention involves activating and sieving the cathode material from spent batteries to obtain ternary material powder. This powder is then chlorinated, roasted, and leached in water to obtain a solution containing nickel chloride, cobalt chloride, manganese chloride, and lithium chloride. Sulfuric acid is added according to the molar amount of lithium to supplement the nickel, cobalt, and manganese content to meet the requirements of the prepared ternary precursor material. Finally, the precursor solution is pyrolyzed, and the pyrolysis products are leached in water to obtain an oxide filter cake and a lithium sulfate solution, thereby achieving the separation of lithium and transition metals. The transition metal oxide slag can be directly used as a precursor to prepare the cathode material. This invention utilizes the easy pyrolysis of nickel chloride, cobalt chloride, and manganese chloride to separate nickel, cobalt, and manganese from lithium, simultaneously achieving efficient recycling of spent lithium batteries and low-cost preparation of NCM cathode material precursors.

[0033] This invention adds sulfuric acid to the precursor solution. Lithium chloride volatilizes during pyrolysis, leading to some lithium loss, while lithium sulfate is very stable during pyrolysis. The lithium loss after pyrolysis is reduced to 6% in the precursor solution with added sulfate, demonstrating that sulfate plays a crucial role in fixing lithium ions and reducing their volatilization. The addition of sulfuric acid is significant for effectively improving lithium recovery efficiency.

[0034] At the same spray pyrolysis temperature (650℃), when the molar ratio of lithium to sulfuric acid in the precursor solution was 1:0.5, the lithium leaching rate reached 93.40%. Compared with the absence of sulfuric acid, the introduction of sulfuric acid significantly improved the lithium leaching rate. Furthermore, the leaching rates of transition metals (Ni, Co, Mn) further decreased, all falling below 1%, indicating that the introduction of sulfuric acid further enhanced the separation rate of lithium from transition metals.

[0035] Introducing a certain amount of sulfate ions into chloride salts (nickel chloride, cobalt chloride, manganese chloride, lithium chloride) before pyrolysis (the molar ratio of sulfate ions to lithium ions conforms to the Li2SO4 ratio, i.e., 1:2) can significantly reduce lithium loss while increasing the lithium leaching rate and the separation rate of lithium from transition metals, thereby improving recovery efficiency and product purity.

[0036] Lithium sulfate is more stable than lithium chloride. However, when sulfate ions are introduced into chloride salts (nickel chloride, cobalt chloride, manganese chloride, lithium chloride), it is generally believed that nickel sulfate, cobalt sulfate, and manganese sulfate will also be formed. These sulfates are also more stable than chloride salts. This will result in undecomposed sulfates (nickel sulfate, cobalt sulfate, manganese sulfate) entering the leaching solution along with lithium sulfate, making it impossible to separate lithium from nickel, cobalt, and manganese. In addition, sulfates such as manganese sulfate and cobalt sulfate are easily decomposed at high temperatures, producing SO2. Therefore, those skilled in the art generally believe that although introducing sulfate ions will reduce lithium loss, it will also result in low separation rate and SO2 generation. In the course of extensive experiments, the inventors of this application discovered that when the amount of sulfate ions to lithium is in a specific molar ratio (1:2), sulfate ions only react with lithium to form lithium sulfate during pyrolysis. This stabilizes lithium and avoids the formation of nickel sulfate, cobalt, manganese sulfate, and the generation of SO2 (lithium sulfate does not easily generate SO2 at high temperatures), significantly improving the lithium recovery and separation rate. Attached Figure Description

[0037] Figure 1 This is a flowchart illustrating an embodiment of the present invention.

[0038] Figure 2 The effect of adding sulfuric acid on the leaching rate of various metal elements.

[0039] Figure 3 The effect of different sulfuric acid contents on the leaching rate of various metal elements. Detailed Implementation

[0040] The present invention will become clearer from the following detailed description with reference to the accompanying drawings and preferred embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of the invention.

[0041] Example 1

[0042] A method for recovering valuable metals, the sample being a lithium nickel cobalt manganese oxide (NCM523) battery, such as... Figure 1 As shown, it includes the following steps:

[0043] (1) The waste nickel cobalt manganese oxide (NCM523) cathode material was activated at 550℃ for 60 min, the activated product was sieved to obtain ternary material powder, and then further pulverized.

[0044] (2) The ternary material powder obtained in step (1) was thoroughly mixed with NH4Cl. The molar ratio of NH4Cl to lithium in the waste lithium-ion battery cathode material was 3:1. The mixture was then subjected to chlorination roasting at 300°C for 30 min in an air atmosphere. The roasted product was thoroughly mixed with deionized water (solid-liquid ratio of 30 mL / g). The water leaching temperature was 60°C and the leaching time was 60 min. After leaching, the mixture was filtered and separated to obtain a lithium and transition metal chloride solution.

[0045] (3) The lithium, nickel, cobalt, and manganese elements in the chloride solution obtained in step (2) were analyzed and determined using inductively coupled plasma atomic emission spectrometry. Sulfuric acid was added in such an amount that the molar ratio of sulfate ions to lithium ions in the solution was 0.5:1. According to the designed stoichiometric ratio of NCM523, the corresponding elements were added to make the molar ratio of transition metal elements in the solution Ni:Co:Mn=5:2:3, in which nickel chloride hexahydrate, cobalt chloride hexahydrate, and manganese chloride tetrahydrate were used as nickel, cobalt, and manganese sources. Deionized water was then added to adjust the total concentration of transition metal ions in the solution to 0.5M to obtain the precursor solution.

[0046] (4) The precursor solution obtained in step (3) is subjected to spray pyrolysis at a pyrolysis temperature of 650℃ and an oxygen flow rate of 10L / min to obtain the pyrolysis product.

[0047] (5) The pyrolysis product obtained in step (4) is subjected to a second calcination at a temperature of 500℃ for 30 min. The obtained second calcination product is thoroughly mixed with deionized water (solid-liquid ratio of 30 mL / g), and the water leaching temperature is 70℃ for 60 min. After leaching, the lithium sulfate leachate and oxide filter cake are obtained by filtration and separation. The filter cake meets the requirements of NCM523 ternary precursor.

[0048] (6) The mass fraction of lithium in the lithium sulfate leaching solution from step (5) was determined by inductively coupled plasma atomic emission spectrometry to be 14.7 g / L, with a lithium leaching rate of 98.0%. Excess sodium carbonate was added to the lithium sulfate leaching solution, and lithium carbonate was deposited at 85°C. The lithium carbonate recovered and prepared using this embodiment had a purity of 99.5 wt%.

[0049] (7) The oxide filter cake from step (5) and the lithium carbonate from step (6) are mixed in the stoichiometric ratio of lithium nickel cobalt manganese oxide (NCM523) and calcined at 950°C for 12 hours to obtain a new lithium nickel cobalt manganese oxide (NCM523) cathode material.

[0050] Example 2

[0051] A method for recovering valuable metals, with the sample mainly being a lithium nickel cobalt manganese oxide (NCM333) battery, includes the following steps:

[0052] (1) The waste nickel cobalt manganese oxide (NCM333) cathode material was activated at 550℃ for 60 min, the activated product was sieved to obtain ternary material powder, and then further pulverized.

[0053] (2) The ternary material powder obtained in step (1) was thoroughly mixed with NH4Cl, and the molar ratio of NH4Cl to lithium in the waste lithium-ion battery cathode material was 2:1. The mixture was then subjected to chlorination roasting at 300°C for 30 min in an air atmosphere. The roasted product was thoroughly mixed with deionized water (solid-liquid ratio of 30 mL / g), and the water leaching temperature was 60°C for 60 min. After leaching, the mixture was filtered and separated to obtain a lithium and transition metal chloride solution.

[0054] (3) In the chloride solution obtained in step (2), lithium, nickel, cobalt and manganese elements were analyzed and determined by inductively coupled plasma atomic emission spectrometry. Sulfuric acid was added so that the molar ratio of sulfate ions to lithium ions in the solution was 0.5:1. According to the designed stoichiometric ratio of NCM333, the corresponding elements were added so that the molar ratio of transition metal elements in the solution was Ni:Co:Mn=1:1:1, in which nickel chloride hexahydrate, cobalt chloride hexahydrate and manganese chloride tetrahydrate were used as nickel, cobalt and manganese sources. Deionized water was added to adjust the total concentration of transition metal ions in the solution to 0.5M to obtain the precursor solution.

[0055] (4) The precursor solution obtained in step (3) is subjected to spray pyrolysis at a pyrolysis temperature of 750℃ and an oxygen flow rate of 10L / min to obtain the pyrolysis product.

[0056] (5) The pyrolysis product obtained in step (4) is subjected to a second calcination at a temperature of 500℃ for 30 min. The obtained second calcination product is thoroughly mixed with deionized water (solid-liquid ratio of 30 mL / g), and the water leaching temperature is 70℃ for 60 min. After leaching, the lithium sulfate leachate and oxide filter cake are obtained by filtration and separation. The various indicators of the filter cake meet the requirements of NCM333 ternary precursor.

[0057] (6) The mass fraction of lithium in the lithium sulfate leaching solution from step (5) was determined by inductively coupled plasma atomic emission spectrometry to be 14.5 g / L, with a lithium leaching rate of 96.7%. Excess sodium carbonate was added to the lithium sulfate leaching solution, and lithium carbonate was deposited at 85°C. The lithium carbonate recovered and prepared using this embodiment had a purity of 99.5 wt%.

[0058] (7) The oxide filter cake from step (5) and the lithium carbonate from step (6) are mixed in the stoichiometric ratio of lithium nickel cobalt manganese oxide (NCM333) and calcined at 950°C for 12 hours to obtain a new lithium nickel cobalt manganese oxide (NCM333) cathode material.

[0059] Example 3

[0060] A method for recovering valuable metals, with the main sample being a lithium nickel cobalt manganese oxide (NCM811) battery, such as... Figure 1 As shown, it includes the following steps:

[0061] (1) The waste nickel cobalt manganese oxide (NCM811) cathode material was activated at 550℃ for 60 min, the activated product was sieved to obtain ternary material powder, and then further pulverized.

[0062] (2) The ternary material powder obtained in step (1) was thoroughly mixed with NH4Cl, and the molar ratio of NH4Cl to lithium in the waste lithium-ion battery cathode material was 3:1. The mixture was then subjected to chlorination roasting at 300°C for 30 min in an air atmosphere. The roasted product was thoroughly mixed with deionized water (solid-liquid ratio of 30 mL / g), and the water leaching temperature was 60°C for 60 min. After leaching, the mixture was filtered and separated to obtain a lithium and transition metal chloride solution.

[0063] (3) The lithium, nickel, cobalt, and manganese elements in the solution were analyzed and determined using inductively coupled plasma atomic emission spectrometry. Ammonium sulfate was added to make the molar ratio of sulfate ions to lithium ions in the solution 0.5:1. According to the designed stoichiometric ratio of NCM811, the corresponding elements were added to make the molar ratio of transition metal elements in the solution Ni:Co:Mn=8:1:1. Nickel chloride hexahydrate, cobalt chloride hexahydrate, and manganese chloride tetrahydrate were used as nickel, cobalt, and manganese sources. Deionized water was then added to adjust the total concentration of transition metal ions in the solution to 0.5M to obtain the precursor solution.

[0064] (4) The precursor solution obtained in step (3) is subjected to spray pyrolysis at a pyrolysis temperature of 850℃ and an oxygen flow rate of 10L / min to obtain the pyrolysis product.

[0065] (5) The pyrolysis product obtained in step (4) is subjected to a second calcination at a temperature of 500℃ for 60 min. The obtained second calcination product is thoroughly mixed with deionized water (solid-liquid ratio of 30 mL / g), and the water leaching temperature is 70℃ for 60 min. After leaching, the lithium sulfate leachate and oxide filter cake are obtained by filtration and separation. The filter cake meets the requirements of NCM811 ternary precursor.

[0066] (6) The mass fraction of lithium in the lithium sulfate leaching solution from step (5) was determined by inductively coupled plasma atomic emission spectrometry to be 14.3 g / L, with a lithium leaching rate of 95.3%. Excess sodium carbonate was added to the lithium sulfate leaching solution, and lithium carbonate was deposited at 90°C. The lithium carbonate recovered and prepared using this embodiment had a purity of 99.6 wt%.

[0067] (7) The oxide filter cake from step (5) and the lithium carbonate from step (6) are mixed in the stoichiometric ratio of lithium nickel cobalt manganese oxide (NCM811) and calcined at 780°C for 15 hours to obtain a new lithium nickel cobalt manganese oxide (NCM811) cathode material.

[0068] Example 4

[0069] A method for recovering valuable metals, with the main sample being a lithium nickel cobalt manganese oxide (NCM523) battery, such as... Figure 1 As shown, it includes the following steps:

[0070] (1) The waste nickel cobalt manganese oxide (NCM523) cathode material was activated at 550℃ for 60 min. The activated product was sieved to separate the aluminum foil and obtain ternary material powder, which was then further pulverized.

[0071] (2) The ternary material powder obtained in step (1) is leached with hydrochloric acid. The amount of hydrochloric acid added is 10% more than the sum of the molar amounts of hydrochloric acid required for leaching lithium, nickel, cobalt and manganese ions of different valence states in the ternary material powder. The leaching is carried out at 80°C so that all nickel, cobalt, manganese and lithium dissolve into the liquid phase to form chlorides. The leached material is then subjected to solid-liquid separation to obtain filtrate.

[0072] (3) The lithium, nickel, cobalt, and manganese elements were analyzed and determined using inductively coupled plasma atomic emission spectrometry. Sulfuric acid was added to make the molar ratio of sulfate ions to lithium ions in the solution 0.55:1. According to the designed stoichiometric ratio of NCM523, the corresponding elements were added to make the molar ratio of transition metal elements in the solution Ni:Co:Mn=5:2:3. Nickel chloride hexahydrate, cobalt chloride hexahydrate, and manganese chloride tetrahydrate were used as nickel, cobalt, and manganese sources. Deionized water was then added to adjust the total concentration of transition metal ions in the solution to 0.5M to obtain the precursor solution.

[0073] (4) The precursor solution obtained in step (3) is subjected to spray pyrolysis at a pyrolysis temperature of 650℃ and an oxygen flow rate of 10L / min to obtain the pyrolysis product.

[0074] (5) The pyrolysis product obtained in step (4) is subjected to a second calcination at a temperature of 500℃ for 30 min. The obtained second calcination product is thoroughly mixed with deionized water (solid-liquid ratio of 30 mL / g), and the water leaching temperature is 70℃ for 60 min. After leaching, the lithium sulfate leachate and oxide filter cake are obtained by filtration and separation. The filter cake meets the requirements of NCM523 ternary precursor.

[0075] (6) After diluting a sample of the lithium sulfate leachate from step (5), the mass fraction of lithium was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES), which showed a lithium leaching rate of 98.7%, to be 14.8 g / L. Excess sodium carbonate was added to the lithium sulfate leachate obtained in step (5), and lithium carbonate was deposited at 90°C. The lithium carbonate recovered and prepared using this embodiment had a purity of 99.5 wt%.

[0076] (7) The oxide filter cake from step (5) and the lithium carbonate from step (6) are mixed in the stoichiometric ratio of lithium nickel cobalt manganese oxide (NCM523) and calcined at 950°C for 12 hours to obtain a new lithium nickel cobalt manganese oxide (NCM523) cathode material.

[0077] Example 5

[0078] A method for recovering valuable metals, with samples mainly consisting of lithium cobalt oxide (LCO) batteries, such as... Figure 1 As shown, it includes the following steps:

[0079] (1) The waste lithium cobalt oxide (LCO) cathode material was activated at 550°C for 60 min. The activated product was sieved to separate the aluminum foil and obtain cathode material powder, which was then further pulverized.

[0080] (2) The positive electrode material powder obtained in step (1) is leached with hydrochloric acid. The amount of hydrochloric acid added is 5% more than the sum of the molar amounts of hydrochloric acid required for leaching lithium and cobalt ions of different valence states in the positive electrode material powder. The leaching is carried out at 80°C so that all lithium and cobalt dissolve into the liquid phase to form chloride. The leached material is then subjected to solid-liquid separation to obtain filtrate.

[0081] (3) The filtrate obtained in step (2) was analyzed and determined to contain lithium and cobalt using inductively coupled plasma atomic emission spectrometry. Ammonium sulfate was added to make the molar ratio of sulfate ions to lithium ions in the solution 0.4:1; then deionized water was added to adjust the total concentration of transition metal ions in the solution to 0.5M, thus obtaining the precursor solution.

[0082] (4) The precursor solution obtained in step (3) is subjected to spray pyrolysis at a pyrolysis temperature of 550℃ and an oxygen flow rate of 10L / min to obtain the pyrolysis product.

[0083] (5) The pyrolysis product obtained in step (4) is subjected to a second roasting at a temperature of 500℃ for 1 min. The obtained second roasting product is thoroughly mixed with deionized water (solid-liquid ratio of 30 mL / g), the water leaching temperature is 70℃, the leaching time is 60 min, and after leaching, the lithium sulfate leachate and oxide filter cake are obtained by filtration.

[0084] (6) After diluting a sample of the lithium sulfate leachate from step (5), the mass fraction of lithium was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES), which showed a lithium leaching rate of 95.3%, to be 14.3 g / L. Excess sodium carbonate was added to the lithium sulfate leachate obtained in step (5), and lithium carbonate was deposited at 90°C. The lithium carbonate recovered and prepared using this embodiment had a purity of 99.5 wt%.

[0085] The oxide filter cake from step (5) and the lithium carbonate from step (6) were mixed in the stoichiometric ratio of lithium cobalt oxide (LCO) and calcined at 950°C for 12 hours to obtain a new lithium cobalt oxide (LCO) cathode material.

[0086] Example 6

[0087] A method for recovering valuable metals, with the main sample being a lithium nickel cobalt manganese oxide (NCM811) battery, such as... Figure 1 As shown, it includes the following steps:

[0088] (1) The waste nickel cobalt manganese oxide (NCM811) cathode material was activated at 550℃ for 60 min, the activated product was sieved to obtain ternary material powder, and then further pulverized.

[0089] (2) The ternary material powder obtained in step (1) was thoroughly mixed with NH4Cl, and the molar ratio of NH4Cl to lithium in the waste lithium-ion battery cathode material was 3:1. The mixture was then subjected to chlorination roasting at 300°C for 30 min in an air atmosphere. The roasted product was thoroughly mixed with deionized water (solid-liquid ratio of 30 mL / g), and the water leaching temperature was 60°C for 60 min. After leaching, the mixture was filtered and separated to obtain a lithium and transition metal chloride solution.

[0090] (3) The lithium, nickel, cobalt, and manganese elements in the solution were analyzed and determined using inductively coupled plasma atomic emission spectrometry. Sulfuric acid was added to make the molar ratio of sulfate ions to lithium ions in the solution 0.5:1. According to the designed stoichiometric ratio of NCM811, the corresponding elements were added to make the molar ratio of transition metal elements in the solution Ni:Co:Mn=8:1:1. Nickel chloride hexahydrate, cobalt chloride hexahydrate, and manganese chloride tetrahydrate were used as nickel, cobalt, and manganese sources. Deionized water was then added to adjust the total concentration of transition metal ions in the solution to 0.5M to obtain the precursor solution.

[0091] (4) The precursor solution obtained in step (3) is subjected to spray pyrolysis at a pyrolysis temperature of 750℃ and an oxygen flow rate of 10L / min to obtain the pyrolysis product.

[0092] (5) The pyrolysis product obtained in step (4) is thoroughly mixed with deionized water (solid-liquid ratio of 30 mL / g), the water leaching temperature is 70 °C, the leaching time is 60 min, and after leaching, the lithium sulfate leachate and oxide filter cake are obtained by filtration and separation.

[0093] (6) The mass fraction of lithium in the lithium sulfate leaching solution from step (5) was determined using inductively coupled plasma atomic emission spectrometry (ICP-AES). A lithium hydroxide solution was added, with the ratio of lithium hydroxide added to the molar amounts of nickel, cobalt, and manganese in the solution being 2.1:1. After precipitation, the solution was filtered, and the filter cake was washed to obtain a nickel-cobalt-manganese hydroxide precipitate. Excess sodium carbonate was added to the lithium-rich leaching solution, and lithium carbonate was deposited at 85°C. The lithium carbonate recovered and prepared using this example had a purity of 99.8 wt%.

[0094] (7) The oxide filter cake from step (5) and the lithium carbonate from step (6) are mixed in the stoichiometric ratio of lithium nickel cobalt manganese oxide (NCM811) and calcined at 780°C for 15 hours to obtain a new lithium nickel cobalt manganese oxide (NCM811) cathode material.

[0095] Comparative Example 1

[0096] Compared with Example 1, sulfuric acid is not added in step (3), but everything else is the same as in Example 1.

[0097] Example 7

[0098] The lithium-ion losses of Example 1 and Comparative Example 1 were compared to obtain the loss comparison table shown in Table 1.

[0099] Table 1. Molar ratio of each metal element and lithium loss rate in pyrolysis products with different sulfuric acid contents.

[0100]

[0101] The lithium loss rate is calculated by measuring the lithium ion content in the lithium sulfate leaching solution in step (5), measuring the lithium ion content in the lithium and transition metal chloride solution in step (2), comparing the difference between the two, and dividing the difference by the lithium ion content in the lithium and transition metal chloride solution in step (2) to obtain the lithium loss rate.

[0102] Example 8

[0103] The leaching rates of each element in the lithium sulfate leachate from step (5) of Example 1 and Comparative Example 1 were compared to obtain the following results: Figure 2 The leaching rate diagram is shown. The leaching rate L of each element in step (5) is also shown. i Calculate according to formula (1)

[0104]

[0105] Among them, C i This indicates the concentration of each metal element "i" in the lithium sulfate leaching solution described in step (5) of the embodiment (in g / L). -1 V i This indicates the volume of the leachate (in liters). i The mass fraction (%) of each metal element "i" in the secondary roasting product described in step (5) of the embodiment is represented by m0, and the mass (g) of the secondary roasting product used for the water immersion experiment described in step (5) of the embodiment is represented by m0.

[0106] As can be seen from Examples 7-8, the addition of sulfuric acid can significantly improve the lithium leaching rate and the separation rate of lithium from other metal elements.

[0107] Example 9

[0108] Adjust the amount of sulfuric acid added, otherwise remain the same as in Example 1.

[0109] The leaching rates of various metal elements under different sulfuric acid contents were compared, and the results were as follows: Figure 3 The leaching rate of each metal element is shown. The calculation method for the leaching rate is the same as in Example 5.

[0110] At the same spray pyrolysis temperature (650℃), when the molar ratio of lithium to sulfuric acid in the precursor solution was 1:0.25, the lithium leaching rate was 85.49%, which was lower than that when the molar ratio was 1:0.5, and the separation rate of lithium from transition metals was also lower. When the sulfuric acid content was further increased, resulting in a 1:1 molar ratio of lithium to sulfuric acid in the precursor solution, the lithium leaching rate increased, but this also led to a large amount of transition metals being leached as sulfates. This is because transition metal sulfates are relatively stable and do not pyrolyze to form oxides at 650℃. In summary, a lithium-sulfuric acid molar ratio of 1:0.5 resulted in a high lithium leaching rate and a high separation rate between lithium and transition metals.

[0111] Based on the phase composition of the pyrolysis products and thermodynamic calculations, the added sulfate ions ultimately combine with lithium ions to form lithium sulfate. The leaching and separation rates are highest when the molar ratio of lithium ions to sulfate ions is 1:0.5. Slightly increasing the amount of sulfuric acid, such as to a lithium ion to sulfate ion molar ratio of 1:0.55, further improves the lithium leaching rate. However, the excess sulfuric acid inevitably combines with transition metals, and the entry of transition metal sulfates into the liquid phase leads to a decrease in the separation rate. Overall, a high level of lithium leaching rate and separation rate from transition metals is achieved when the molar ratio of sulfate ions to lithium ions is between 0.1 and 0.55:1.

[0112] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of protection of this application is limited to these examples; within the framework of this application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of one or more embodiments of this application as described above, which are not provided in detail for the sake of brevity.

[0113] One or more embodiments in this application are intended to cover all such substitutions, modifications, and variations that fall within the broad scope of this application. Therefore, any omissions, modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of one or more embodiments in this application should be included within the protection scope of this application.

Claims

1. A precursor solution, characterized in that, The raw materials to be recycled include valuable metal ions, chloride ions, and sulfate ions. The raw materials to be recycled are lithium-containing waste battery cathode materials. The valuable metal ions include lithium ions and transition metal ions. The number of moles of sulfate ions does not exceed 0.55 times the number of moles of lithium ions.

2. The precursor solution as described in claim 1, characterized in that, The molar ratio of sulfate ions to lithium ions is 0.45 to 0.55:

1.

3. The precursor solution as described in claim 2, characterized in that, The molar ratio of sulfate ions to lithium ions is 0.5:1; the molar ratio of chloride ions to total transition metal ions is 1 to 3:1; the lithium-containing waste battery cathode material includes one or more of lithium cobalt oxide, lithium nickel oxide, lithium nickel cobalt manganese oxide, and lithium nickel cobalt aluminum oxide; and also includes an appropriate amount of transition metal ions to meet the content ratio of the target battery cathode material.

4. A method for preparing a precursor solution as described in any one of claims 1-3, characterized in that, The steps are as follows: the chloride solution of the raw material to be recovered is mixed with an acid or salt containing sulfate to obtain a precursor solution.

5. The method for preparing the precursor solution as described in claim 4, characterized in that, The method for preparing the chloride solution of the raw material to be recycled is as follows: the raw material to be recycled is mixed with ammonium chloride, subjected to chlorination roasting, leached in water, and then separated into solid and liquid components to obtain the chloride solution; or, the raw material to be recycled is mixed with hydrochloric acid to obtain the chloride solution. Before the raw materials to be recycled are mixed with ammonium chloride or hydrochloric acid, the raw materials to be recycled are activated at 500-600°C to separate the positive electrode powder from the current collector aluminum foil. The molar ratio of ammonium chloride or hydrochloric acid to lithium in the raw material to be recovered is 2-4:1; the chlorination roasting temperature is 200-400℃; the water immersion temperature is 20-80℃; the sulfate-containing acid or salt includes one or more mixtures of sulfuric acid, ammonium sulfate, ammonium bisulfate, sodium sulfate, nickel sulfate, cobalt sulfate, and manganese sulfate.

6. A method for recycling valuable metals, characterized in that, The precursor solution as described in any one of claims 1-3 is heated to obtain a pyrolysis product, and then the pyrolysis product is leached with water and separated into solid and liquid components to obtain a lithium sulfate solution and an oxide precursor.

7. The method for recovering valuable metals as described in claim 6, characterized in that, The heating is performed by spray pyrolysis; the heating temperature is 500–850°C; the water leaching temperature is 20–80°C.

8. The method for recovering valuable metals as described in claim 6, characterized in that, in Before water leaching of the pyrolysis products, the method further includes a secondary roasting step, wherein the secondary roasting temperature is 450–600°C; or… After water leaching and solid-liquid separation of the pyrolysis products, the lithium sulfate solution is first purified by adding lithium hydroxide or sodium hydroxide to the lithium sulfate solution.

9. The method for recovering valuable metals as described in claim 6, characterized in that, The lithium sulfate solution undergoes a lithium precipitation reaction to obtain lithium carbonate; The lithium precipitation reaction involves mixing lithium sulfate solution and sodium carbonate solution at a reaction temperature of 60–100°C.

10. The method for recovering valuable metals as described in claim 9, characterized in that, A new cathode material is obtained by mixing lithium carbonate and oxide precursors and calcining them.

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