Method for roasting and recycling lithium from waste lithium ion battery cathode material

Abstract

The application provides a method for roasting and recycling lithium from waste lithium ion battery positive electrode materials, comprising the following steps: 1) mixing and roasting waste lithium ion battery positive electrode materials and thiourea-based compounds at 200-500 DEG C to obtain a roasting product; 2) performing leaching treatment on the roasting product in water at 40-70 DEG C to obtain a lithium-rich solution. The method for roasting and recycling lithium from waste lithium ion battery positive electrode materials provided by the application can realize high lithium leaching rate, and has the advantages of simple process, low cost and environmental friendliness.

Description

Technical Field

[0001] This invention relates to the field of waste battery recycling, and in particular to a method for recovering lithium by roasting waste lithium-ion battery cathode materials. Background Technology

[0002] Lithium-ion batteries are widely used in electric vehicles, smart home products, computers, power banks, and portable electronic products due to their advantages such as high energy density, no memory effect, low pollution, and small size. However, with the increase in retired batteries, resource shortages and environmental problems are becoming increasingly serious. Therefore, the development and application of economical and efficient waste lithium-ion battery recycling technology is urgently needed. The rational recycling and utilization of lithium metal from waste lithium-ion batteries has significant economic and environmental implications.

[0003] Common lithium recovery methods include pyrometallurgical and hydrometallurgical methods. While these methods achieve high lithium leaching rates, significant lithium entrainment occurs during subsequent extraction and separation of other metals, resulting in poor selectivity. Furthermore, the leaching process requires the addition of large amounts of acids, alkalis, reducing agents, precipitants, and complexing agents, increasing process costs and complexity. Additionally, the introduction of excessive substances into the recovery system reduces the lithium metal recovery rate.

[0004] Therefore, there is an urgent need to develop a method for recovering lithium from waste lithium-ion battery cathode materials by roasting, which has a high lithium recovery rate, simple process and low cost. Summary of the Invention

[0005] This invention provides a method for recovering lithium by roasting waste lithium-ion battery cathode materials. This method can achieve a high lithium leaching rate and has the advantages of simple process, low cost and environmental friendliness.

[0006] This invention provides a method for recovering lithium by roasting waste lithium-ion battery cathode materials, comprising the following steps:

[0007] 1) At 200-500℃, waste lithium-ion battery cathode materials and non-metallic thiourea-based compounds are mixed and roasted to obtain roasted products;

[0008] 2) The calcined product is leached in water at 40-70℃ to obtain a lithium-rich solution.

[0009] The method for recovering lithium by roasting waste lithium-ion battery cathode materials as described above, wherein in step 1), the non-metallic thiourea-based compound includes at least one of thiourea dioxide, methylthiourea, diethylthiourea, and diphenylthiourea.

[0010] The method for recovering lithium by roasting waste lithium-ion battery cathode materials as described above, wherein in step 1), the mass ratio of the waste lithium-ion battery cathode material to the non-metallic thiourea-based compound is 1:0.8-1.3.

[0011] The method for recovering lithium by roasting waste lithium-ion battery cathode materials as described above, wherein the mixed roasting includes: mixing the waste lithium-ion battery cathode material and the non-metallic thiourea-based compound, and then heating to the roasting temperature at a rate of 5-10°C / min.

[0012] The method for recovering lithium by roasting waste lithium-ion battery cathode materials as described above, wherein the roasting temperature is 250-400℃, and the mass ratio of the waste lithium-ion battery cathode material to the non-metallic thiourea-based compound is 1:0.9-1.2.

[0013] The method for recovering lithium by roasting waste lithium-ion battery cathode materials as described above, wherein in step 1), the roasting time is 30-90 min;

[0014] Preferably, the roasting time is 50-70 minutes.

[0015] The method for recovering lithium by roasting waste lithium-ion battery cathode materials as described above, wherein in step 2), the solid-liquid ratio of the roasting product to water is 50-150 g / L.

[0016] Preferably, the solid-liquid ratio of the calcined product to water is 90-120 g / L.

[0017] The method for recovering lithium by roasting waste lithium-ion battery cathode materials as described above, wherein in step 2), the duration of the leaching process is 30-70 minutes;

[0018] Preferably, the leaching process lasts for 40-60 minutes.

[0019] The method for recovering lithium by roasting waste lithium-ion battery cathode materials as described above, wherein in step 2), the roasting product and water are stirred during the leaching process at a stirring rate of 100-300 r / min.

[0020] Preferably, the stirring rate is 150-200 r / min.

[0021] The method for recovering lithium by roasting waste lithium-ion battery cathode materials as described above, wherein the waste lithium-ion battery cathode materials include at least one of nickel-cobalt-manganese ternary lithium cathode materials, lithium cobalt oxide, and lithium manganese oxide.

[0022] This invention involves mixing and calcining spent lithium-ion battery cathode materials with a non-metallic thiourea-based compound. The decomposition of the non-metallic thiourea-based compound generates sulfur dioxide and sulfurous acid, which in turn causes the spent cathode material to form lithium oxide and other transition metal oxides. Subsequently, the lithium oxide reacts with the sulfur dioxide and sulfurous acid to form lithium sulfate, which is then leached in water to obtain a lithium-rich solution. The lithium-rich solution obtained by this method has a high lithium leaching rate, and the method does not introduce other impurity ions, avoiding the subsequent impurity removal costs. Furthermore, this method requires low energy consumption, has low raw material costs, and produces no harmful substances, thus being environmentally friendly. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the process of the present invention. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions in the embodiments of this invention will be clearly and completely described below in conjunction with the embodiments of this invention. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0025] This invention provides a method for recovering lithium by roasting waste lithium-ion battery cathode materials, such as... Figure 1 As shown, it includes the following steps:

[0026] 1) At 200-500℃, waste lithium-ion battery cathode materials and non-metallic thiourea-based compounds are mixed and roasted to obtain roasted products;

[0027] 2) At 40-70℃, the calcined product is leached in water to obtain a lithium-rich solution.

[0028] Specifically, in step 1), waste lithium-ion battery cathode material and non-metallic thiourea-based compound are mixed and then ground. Subsequently, the mixed raw materials are roasted at a temperature of 200-500°C in an aerobic environment. After cooling, the roasted product is obtained.

[0029] This invention does not limit the grinding method and time. As long as the waste lithium-ion battery cathode material and non-metallic thiourea-based compound are mixed evenly, for example, a ball mill can be used for grinding, and the grinding time is 30 minutes.

[0030] The present invention does not limit the heating method of the roasting temperature. For example, continuous heating or stepped heating can be used, as long as the roasting temperature can be reached.

[0031] This invention does not limit the source of the positive electrode material of waste lithium-ion batteries. For example, waste lithium batteries can be disassembled and the positive electrode sheets obtained from the disassembly can be crushed.

[0032] In step 2), the calcined product obtained in step 1) is mixed with water, heated and then leached. The leaching temperature is controlled at 40-70℃. A lithium-containing solution and leaching residue are obtained by stirring. After solid-liquid separation, a lithium-containing solution is obtained. The lithium-containing solution is then concentrated to obtain a lithium-rich solution.

[0033] This invention does not limit the heating method; for example, it can be heated by a water bath, as long as the leaching temperature can be reached.

[0034] This invention does not limit the stirring method or stirring rate. For example, mechanical stirring or magnetic stirring can be used, as long as the leaching effect can be achieved.

[0035] This invention does not limit the method of solid-liquid separation. For example, filtration or centrifugation can be used, as long as the lithium-containing solution can be separated from the leaching residue.

[0036] The present invention does not limit the concentration method of lithium-containing solution. For example, the lithium-containing solution can be heated to 95°C and kept at a constant temperature to achieve the purpose of concentration.

[0037] The present invention provides a method for recovering lithium from waste lithium-ion battery cathode materials by roasting. The method involves roasting the waste lithium-ion battery cathode materials with a non-metallic thiourea-based compound in an aerobic environment at 200-500°C. At this temperature, the non-metallic thiourea-based compound can be completely decomposed, producing sulfur dioxide gas and sulfurous acid, which have strong reducing properties. The waste cathode materials react under the dual synergistic reduction-induced mechanism of sulfur dioxide and sulfurous acid. The collapse of the waste lithium-ion battery structure causes lithium to preferentially release, producing lithium oxide and other transition metal oxides. Lithium oxide is preferentially generated under the action of sulfur dioxide and sulfurous acid. Subsequently, because the binding force between lithium and sulfate is stronger than that between other transition metals and sulfate, lithium oxide preferentially reacts with sulfur dioxide and sulfurous acid to form soluble lithium sulfate. Then, the mixture of lithium sulfate and other transition metal oxides is mixed with water, and the leaching temperature is controlled between 40-70°C. Lithium sulfate dissolves in the water to form a lithium-rich solution, while the other transition metal oxides exist in solid form in the leaching residue. When the roasting temperature is below 200℃, the oxidation reaction of the waste cathode material is low, which is not conducive to the formation of lithium oxide, thus leading to a decrease in the lithium leaching rate. If the roasting temperature is above 500℃, the energy consumed by roasting is too large, resulting in energy loss. In addition, when the leaching temperature is below 40℃, the leaching temperature is too low, resulting in low leaching efficiency of lithium sulfate, thus affecting the lithium leaching rate. When the leaching temperature is above 70℃, the leaching reaction is violent during the leaching process, leading to the generation of side reactions during the leaching process, which reduces the lithium leaching rate.

[0038] The present invention provides a method for recovering lithium from waste lithium-ion battery cathode materials by roasting. On the one hand, through a simple two-step process, lithium can be preferentially extracted from waste lithium-ion batteries and stored in the form of lithium sulfate, while other metals are transformed into transition metal oxides. This allows lithium to be selectively leached in water, significantly improving the lithium leaching rate. On the other hand, the roasting process can be carried out at low temperatures, resulting in low energy consumption. Moreover, after the low-cost non-metallic thiourea-based compound decomposes during the roasting process, no other impurity ions are introduced into the entire system, avoiding increased subsequent impurity removal costs. In addition, no acids or alkalis are used in the entire system, avoiding the generation of waste acids and alkalis, thus making the method environmentally friendly.

[0039] In one embodiment, a saturated sodium carbonate solution can be added to the above-mentioned lithium-rich solution to form lithium carbonate precipitate. Then, the lithium carbonate is separated from the solution and washed and dried to obtain high-purity lithium carbonate.

[0040] In one specific embodiment, in step 1), the non-metallic thiourea-based compound includes at least one of thiourea dioxide, methylthiourea, diethylthiourea, and diphenylthiourea, preferably thiourea dioxide. When waste lithium-ion battery cathode material is roasted with thiourea dioxide at 200-500°C, the structure of the waste lithium-ion battery cathode material collapses, and lithium is preferentially extracted and converted into lithium oxide. Thiourea dioxide decomposes upon heating to generate sulfurous acid and sulfur dioxide gas, which are strong reducing agents. Then, sulfurous acid decomposes upon heating to continue generating sulfur dioxide gas. Subsequently, lithium oxide reacts with sulfur dioxide gas and sulfurous acid to generate water-soluble lithium sulfate, selectively leaching lithium to obtain a lithium-rich solution. These non-metallic thiourea-based compounds can all generate sulfur dioxide gas and the strong reducing agent sulfurous acid during roasting, thereby achieving selective leaching of lithium without introducing other impurity ions into the system, reducing subsequent impurity removal processes, lowering recycling costs, and these non-metallic thiourea-based compounds are low in cost and environmentally friendly, with thiourea dioxide being the most cost-effective.

[0041] In one specific embodiment, in step 1), the mass ratio of waste lithium-ion battery cathode material to non-metallic thiourea-based compound is 1:0.8-1.3. Specifically, the mass ratio of waste lithium-ion battery cathode material to non-metallic thiourea-based compound can be selected from the range of thiourea dioxide, methylthiourea, diethylthiourea, or any two thereof. When the mass ratio of waste lithium-ion battery cathode material to non-metallic thiourea-based compound is within the above range, the sulfur dioxide gas and sulfurous acid generated by the thermal decomposition of the non-metallic thiourea-based compound can cause the structure of the waste cathode material to collapse, thereby preferentially releasing lithium from it and reacting with the generated lithium oxide, thus improving the lithium leaching rate of the waste cathode material, while also reducing the use of non-metallic thiourea-based compound and lowering costs. If the mass ratio of spent lithium-ion battery cathode material to non-metallic thiourea-based compound is less than 1:1.3, the excessive use of non-metallic thiourea-based compound leads to excessive sulfur dioxide gas from its decomposition. After reacting with lithium oxide to form lithium sulfate, the remaining sulfur dioxide gas and sulfurous acid react with other transition metal oxides to form soluble sulfates, reducing the lithium leaching rate and potentially causing excessive sulfur dioxide gas production, resulting in environmental pollution. If the mass ratio of spent lithium-ion battery cathode material to non-metallic thiourea-based compound is greater than 1:0.8, it indicates a high amount of spent cathode material, leading to excessive lithium oxide and insufficient sulfur dioxide gas from its decomposition. This prevents complete conversion of lithium oxide to lithium sulfate, leaving some lithium residue in the solid oxide and reducing the lithium leaching rate.

[0042] In one specific embodiment, the co-calcination includes: mixing waste lithium-ion battery cathode material and a non-metallic thiourea-based compound, and then heating to the calcination temperature at a rate of 5-10°C / min. Specifically, the heating rate during calcination can be any value within the range of 5°C / min, 7°C / min, 10°C / min, or 5-10°C / min. When the heating rate is within the above range, the non-metallic thiourea-based compound can be fully decomposed to produce sulfur dioxide gas and sulfurous acid. The lithium in the waste cathode material can be fully converted into lithium oxide and react fully with the sulfur dioxide gas and sulfurous acid, which can further improve the lithium leaching rate and reduce energy consumption, thereby reducing recycling costs.

[0043] In one specific embodiment, the roasting temperature is 250-400℃, and the mass ratio of waste lithium-ion battery cathode material to non-metallic thiourea-based compound is 1:0.9-1.2. When the roasting temperature and the mass ratio of waste lithium-ion battery cathode material to non-metallic thiourea-based compound are within the above ranges, the lithium in the waste cathode material can be fully converted into lithium oxide, and then fully reacted with sulfur dioxide gas and sulfurous acid to convert into lithium sulfate, further improving the lithium leaching rate and reducing the energy consumption during roasting and the amount of non-metallic thiourea-based compound used, thereby further reducing the recycling cost.

[0044] In one specific embodiment, in step 1), the roasting time is 30-90 min. Specifically, the ratio of roasting time to the total mass of the roasted raw material can be selected from any value within the range of 30 min, 60 min, 90 min, or 30-90 min. When the roasting time is within the above range, the non-metallic thiourea-based compound can be fully decomposed to produce sulfur dioxide gas and sulfurous acid, and the waste cathode material can be fully reacted into lithium oxide and other transition metal oxides, so that the subsequent generation of lithium sulfate can proceed smoothly, thereby further improving the lithium leaching rate and reducing the recycling energy consumption. Preferably, the roasting time is 50-70 min. When the roasting time is within the range of 50-70 min, the waste cathode material and the non-metallic thiourea-based compound can react more fully, further improving the lithium leaching rate and reducing the recycling energy consumption. More preferably, the roasting time is 60 min.

[0045] In one specific embodiment, in step 2), the solid-liquid ratio of the roasted product to water is 50-150 g / L. When the solid-liquid ratio of the roasted product to water is within the above range, the lithium sulfate in the roasted product can be fully dissolved in the water, thereby increasing the lithium leaching rate and saving water consumption and energy consumption required for subsequent lithium solution concentration, thus reducing recovery costs. If the solid-liquid ratio of the roasted product to water is less than 50 g / L, the amount of water used during leaching is too large, leading to water waste and a low lithium content in the lithium solution, resulting in increased energy consumption for subsequent lithium solution concentration and low purity of the subsequent product. If the solid-liquid ratio of the roasted product to water is higher than 150 g / L, the amount of water used is low, and lithium sulfate cannot be completely dissolved from the roasted product during leaching, resulting in incomplete separation of lithium from other oxides, thereby reducing the lithium leaching rate. Preferably, the solid-liquid ratio of the roasted product to water is 90-120 g / L. Within this range, lithium sulfate in the calcined product can be completely dissolved in water, and the concentration of the prepared lithium-containing solution is appropriate, thereby further improving the lithium leaching rate and reducing the energy consumption for recovery.

[0046] In one specific embodiment, in step 2), the leaching process lasts for 30-70 minutes. Specifically, when the leaching time is within this range, lithium sulfate can be completely dissolved in water during the leaching process, achieving separation of lithium sulfate from other transition metal oxides, thereby improving the lithium leaching rate and recovery efficiency. If the leaching time is less than 30 minutes, the leaching time is too short, and the soluble lithium sulfate is not fully dissolved, thus reducing the lithium leaching rate; if the leaching time is more than 70 minutes, the leaching time is too long, causing free lithium to be coated, thus reducing the lithium leaching rate, while also generating unnecessary side reactions and increasing energy consumption. Preferably, the leaching process lasts for 40-60 minutes. Within this range, lithium sulfate can be fully separated from other transition metal oxides and dissolved more completely, further improving the lithium leaching rate and completing the leaching process more efficiently.

[0047] In one specific embodiment, in step 2), the calcined product and water are stirred during the leaching process at a stirring rate of 100-300 r / min. Specifically, after the calcined product and water are mixed during the leaching process, they are continuously stirred to achieve lithium leaching. The stirring rate can be selected from any value within the range of 100 r / min, 200 r / min, 300 r / min, or 100-300 r / min. When the stirring rate is within the above range, the calcined product can fully contact the water, allowing the lithium sulfate in the calcined product to dissolve efficiently in the water, reducing the residual amount of lithium sulfate in the calcined product, increasing the lithium leaching rate, and further improving the efficiency of the leaching process. If the stirring rate is lower than 100 r / min, the stirring rate is too slow, and the lithium sulfate cannot dissolve sufficiently, thus reducing the leaching rate. If the reaction rate is higher than 300 r / min, the stirring rate is too fast, causing heat to be generated during the leaching process, resulting in a leaching temperature difference, which affects the lithium leaching rate and increases unnecessary energy consumption. Preferably, the stirring rate is 150-200 r / min. When the stirring rate is in the range of 150-200 r / min, lithium sulfate in the calcined product can be leached out more quickly and completely, increasing the lithium leaching rate and shortening the leaching process.

[0048] In one specific embodiment, the waste lithium-ion battery cathode material includes at least one of nickel-cobalt-manganese ternary lithium cathode material, lithium cobalt oxide, and lithium manganese oxide. When the waste cathode material is one of the above materials, it is reacted into lithium oxide, nickel oxide, manganese oxide, or cobalt oxide during the roasting process. Lithium oxide is converted into lithium sulfate, while nickel oxide, manganese oxide, or cobalt oxide exists as solid oxides, thereby achieving efficient lithium leaching and improving the lithium leaching rate.

[0049] The present invention will be further described in detail below through specific embodiments.

[0050] Example 1

[0051] The method for recovering lithium from waste lithium-ion battery cathode materials by roasting in this embodiment includes the following steps:

[0052] 1. Take 100g of LiNi cathode material from a waste lithium-ion battery. 0.8 Co 0.1 Mn 0.1 O2 powder and 120g of thiourea dioxide were mixed and ground in a ball mill for 30 minutes. The mass ratio of waste lithium-ion battery cathode material to non-metallic thiourea-based compound was 1:1.2.

[0053] 2. The mixed and ground materials are co-calcined at a temperature of 350°C at a heating rate of 5°C / min for 60 min.

[0054] 3. The roasted product from the co-mixed roasting and water are subjected to a water leaching process under the conditions of a solid-liquid ratio of 100 g / L, a leaching temperature of 60℃, a leaching time of 60 min, and a stirring rate of 200 r / min to obtain a lithium-containing solution and a leaching residue. The lithium-containing leaching solution is heated to 95℃ and concentrated to obtain a lithium-rich solution.

[0055] Example 2

[0056] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1. The difference is that the mass ratio of waste lithium-ion battery cathode materials to non-metallic thiourea-based compounds is 1:0.8, the roasting temperature is 250°C, the roasting time is 40 min, the solid-liquid ratio of the roasting product to water is 90 g / L, the leaching temperature is 40°C, the leaching time is 40 min, and the stirring rate is 150 r / min.

[0057] Example 3

[0058] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1. The difference is that the mass ratio of waste lithium-ion battery cathode materials to non-metallic thiourea-based compounds is 1:1, the roasting temperature is 300℃, the roasting time is 50min, the leaching temperature is 40℃, the leaching time is 40min, and the stirring rate is 150r / min.

[0059] Example 4

[0060] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the roasting temperature is 400℃, the roasting time is 70min, the ratio of roasting product to water is 120g / L, the leaching temperature is 70℃, and the leaching time is 50min.

[0061] Example 5

[0062] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the roasting temperature is 200°C.

[0063] Example 6

[0064] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the roasting temperature is 500℃.

[0065] Example 7

[0066] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that methylthiourea is used as the non-metallic thiourea-based compound.

[0067] Example 8

[0068] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the mass ratio of waste lithium-ion battery cathode materials to non-metallic thiourea-based compounds is 1:0.8.

[0069] Example 9

[0070] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the mass ratio of waste lithium-ion battery cathode materials to non-metallic thiourea-based compounds is 1.3.

[0071] Example 10

[0072] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the mass ratio of waste lithium-ion battery cathode materials to non-metallic thiourea-based compounds is 1:0.5.

[0073] Example 11

[0074] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the heating rate of the calcination temperature is 7°C / min.

[0075] Example 12

[0076] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the heating rate of the calcination temperature is 10℃ / min.

[0077] Example 13

[0078] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the heating rate of the calcination temperature is 15℃ / min.

[0079] Example 14

[0080] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the roasting time is 50 min and the solid-liquid ratio of the roasting product to water is 90 g / L.

[0081] Example 15

[0082] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the roasting time is 90 min and the solid-liquid ratio of the roasting product to water is 120 g / L.

[0083] Example 16

[0084] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the roasting time is 20 minutes and the solid-liquid ratio of the roasting product to water is 200 g / L.

[0085] Example 17

[0086] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the leaching time is 40 minutes.

[0087] Example 18

[0088] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the leaching time is 70 minutes.

[0089] Example 19

[0090] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the leaching time is 20 minutes.

[0091] Example 20

[0092] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the stirring rate is 150 r / min.

[0093] Example 21

[0094] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the stirring rate is 300 r / min.

[0095] Example 22

[0096] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Example 1, except that the stirring rate is 50 r / min.

[0097] Example 23

[0098] The method for recovering lithium from waste lithium-ion battery cathode materials in this embodiment is basically the same as that in Embodiment 1, except that lithium cobalt oxide is used as the waste lithium-ion battery cathode material.

[0099] Comparative Example 1

[0100] The method for recovering lithium from waste lithium-ion battery cathode materials in this comparative example is basically the same as that in Example 1, except that the waste lithium-ion battery cathode materials are mixed and roasted with sodium bisulfate.

[0101] Comparative Example 2

[0102] The method for recovering lithium from waste lithium-ion battery cathode materials in this comparative example is basically the same as that in Example 1, except that the roasting temperature is 150°C.

[0103] Comparative Example 3

[0104] The method for recovering lithium from waste lithium-ion battery cathode materials in this comparative example is basically the same as that in Example 1, except that the waste lithium-ion battery cathode materials are mixed with sulfur dioxide gas for roasting.

[0105] Table 1. Operating parameters of the lithium recovery methods provided in Examples 1-23 and Comparative Examples 1-3.

[0106]

[0107]

[0108]

[0109] Test case

[0110] The lithium-rich solutions in the above examples and comparative examples were subjected to ICP-OES testing, and the lithium leaching rate, nickel leaching rate, cobalt leaching rate and manganese leaching rate were calculated according to Formula 1, as shown in Table 2.

[0111] Ei = (C i *V i ) / (M*W i )*100% (1)

[0112] Among them, C i The content of each element in the leachate is obtained through ICP-OES detection, V iM is the volume of the extract, M is the mass of the waste lithium-ion battery cathode material before calcination, and W is the mass of the extract. i It is the content of each element in the cathode material of waste lithium-ion batteries obtained through ICP-OES testing.

[0113] Table 2 Leaching rates of Examples 1-23 and Comparative Examples 1-3

[0114]

[0115]

[0116] Table 2 shows that, comparing Examples 1-23 with Comparative Examples 1-3, it was found that mixing and calcining the waste cathode material with the non-metallic thiourea-based compound at 200-500°C, followed by water immersion treatment at 40-70°C, helps to improve the lithium leaching rate. Examples 1, 8, 9, and 10 show that a mass ratio of waste cathode material to non-metallic thiourea-based compound of 1:0.8-1.3 is beneficial for improving the lithium leaching rate. Examples 1 and 11-13 show that a calcination heating rate of 5-10... At a certain temperature (℃ / min), the lithium leaching rate can be further improved. A comparison of Examples 1 and 14-16 shows that when the calcination time is 30-90 min and the solid-liquid ratio of the calcined product to water is 50-150 g / L, the lithium leaching rate is significantly improved. A comparison of Examples 1 and 17-19 shows that the lithium leaching rate is even better when the leaching time is 30-70 min. According to Examples 1 and 20-22, the lithium leaching rate is even better when the stirring rate during leaching is 100-300 r / min. In summary, the method for recovering lithium from waste lithium-ion battery cathode materials provided by this invention can achieve preferential lithium leaching at low temperatures and exhibits a high lithium leaching rate.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for recovering lithium by roasting waste lithium-ion battery cathode materials, characterized in that, Includes the following steps: 1) Under an aerobic environment, waste lithium-ion battery cathode materials and non-metallic thiourea-based compounds are mixed and roasted at 200-500℃ to obtain roasted products; 2) The calcined product is leached in water at 40-70℃ to obtain a lithium-rich solution.

2. The method for recovering lithium by roasting waste lithium-ion battery cathode materials according to claim 1, characterized in that, In step 1), the non-metallic thiourea compound includes at least one of thiourea dioxide, methylthiourea, diethylthiourea, and diphenylthiourea.

3. The method for recovering lithium by roasting waste lithium-ion battery cathode materials according to claim 1 or 2, characterized in that, In step 1), the mass ratio of the waste lithium-ion battery cathode material to the non-metallic thiourea-based compound is 1:0.8-1.

3.

4. The method for recovering lithium by roasting waste lithium-ion battery cathode materials according to claim 1, characterized in that, The mixed roasting includes: mixing the waste lithium-ion battery cathode material and the non-metallic thiourea-based compound, and then heating it to the roasting temperature at a rate of 5-10°C / min.

5. The method for recovering lithium by roasting waste lithium-ion battery cathode materials according to claim 4, characterized in that, The calcination temperature is 250-400℃, and the mass ratio of the waste lithium-ion battery cathode material to the non-metallic thiourea-based compound is 1:0.9-1.

2.

6. The method for recovering lithium by roasting waste lithium-ion battery cathode materials according to any one of claims 1-2 or 4-5, characterized in that, In step 1), the roasting time is 30-90 minutes.

7. The method for recovering lithium by roasting waste lithium-ion battery cathode materials according to claim 6, characterized in that, The roasting time is 50-70 minutes.

8. The method for recovering lithium by roasting waste lithium-ion battery cathode materials according to any one of claims 1-2 or 4-5, characterized in that, In step 2), the solid-liquid ratio of the calcined product to water is 50-150 g / L.

9. The method for recovering lithium by roasting waste lithium-ion battery cathode materials according to claim 8, characterized in that, The solid-liquid ratio of the calcined product to water is 90-120 g / L.

10. The method for recovering lithium by roasting waste lithium-ion battery cathode materials according to any one of claims 1-2 or 4-5, characterized in that, In step 2), the leaching treatment lasts for 30-70 minutes.

11. The method for recovering lithium by roasting waste lithium-ion battery cathode materials according to claim 10, characterized in that, The leaching treatment lasts for 40-60 minutes.

12. The method for recovering lithium by roasting waste lithium-ion battery cathode materials according to any one of claims 1-2 or 4-5, characterized in that, In step 2), the roasted product and water are stirred during the leaching process at a stirring rate of 100-300 r / min.

13. The method for recovering lithium by roasting waste lithium-ion battery cathode materials according to claim 12, characterized in that, The stirring rate is 150-200 r / min.

14. The method for recovering lithium by roasting waste lithium-ion battery cathode materials according to any one of claims 1-2, 4-5, 7, 9, 11, and 13, characterized in that, The waste lithium-ion battery cathode material includes at least one of nickel-cobalt-manganese ternary lithium cathode material, lithium cobalt oxide, and lithium manganese oxide.

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