A method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries

Abstract

The present invention discloses a method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries, which relates to the field of battery technology. The method comprises the following steps: S1, reduction: mixing the cathode material of waste ternary lithium batteries with a reducing agent and then roasting to obtain a roasted product; S2, water leaching: mixing the roasted product with water for water leaching and performing solid-liquid separation; collecting the liquid phase to obtain a first liquid phase; S3, impurity removal: mixing the first liquid phase, a metal extractant and a pH regulator for extraction; separating the lithium-containing aqueous phase after extraction; S4, lithium precipitation: mixing the lithium-containing aqueous phase with a carbonate to obtain lithium carbonate. The method of the present invention simplifies the process flow of separating and extracting various metals, reduces the reagents consumed for separating and extracting metal elements, reduces the recycling cost and obtains high-purity lithium carbonate.

Description

Technical Field

[0001] The present invention belongs to the technical field of batteries, and particularly relates to a method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries. Background Art

[0002] As a green and environmentally friendly new energy source, lithium-ion batteries have the advantages of good reliability, high safety, small size, and light weight. Currently, they have been widely used in fields such as digital products, electric vehicles, and military products. With the continuous use of lithium-ion batteries, waste lithium-ion batteries will inevitably be generated. The interior of waste lithium-ion batteries contains relatively many valuable metal elements, so waste lithium-ion batteries have a certain recycling value.

[0003] A method for recycling waste electrolyte of lithium-ion batteries is disclosed in the related art, including the following steps: S1, preparing lithium-containing fluorine slag; S2, pulping the lithium-containing fluorine slag with water, adding a leaching agent to dissolve the lithium in the lithium-containing fluorine slag in water, and filtering to obtain a crude lithium solution; S3, adjusting the pH value with an alkaline reagent to remove impurities in the crude lithium solution to obtain a refined lithium solution; S4, adding a carbonate in the refined lithium solution for precipitation to obtain crude lithium carbonate. The recycling efficiency of the above recycling method is relatively low. Summary of the Invention

[0004] The purpose of the present invention is to provide a method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries to solve at least one aspect of the problems and defects raised in the above background art.

[0005] Specifically, the first aspect of the present invention discloses a method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries, including the following steps:

[0006] S1, Reduction:

[0007] Mix the cathode material of waste ternary lithium batteries and a reducing agent and then roast to obtain a roasted product;

[0008] S2, Water Leaching:

[0009] Mix the roasted product and water for water leaching, and perform solid-liquid separation; collect the liquid phase to obtain a first liquid phase;

[0010] S3, Impurity Removal:

[0011] Mix the first liquid phase, a metal extractant, and a pH regulator and then extract; after extraction, separate to obtain a lithium-containing aqueous phase;

[0012] S4, Lithium Precipitation:

[0013] Mix the lithium-containing aqueous phase and a carbonate to obtain lithium carbonate;

[0014] The metal extractant includes the following preparation raw materials:

[0015] Acrylate polymer and P204;

[0016] The acrylate polymer comprises the following raw materials for preparation in parts by weight:

[0017] 100 parts of isobutyl acrylate, 1 to 2 parts of trimethylolpropane trimethacrylate, 3 to 4 parts of 3-(4-methoxyphenyl)-2-acrylate propyl ester, 10 to 20 parts of tetraallyl silicate, 50 to 70 parts of n-butanol, and 0.1 to 5 parts of benzoyl peroxide.

[0018] According to one technical solution in the technical solution of the method of the present invention, it has at least the following beneficial effects:

[0019] In the present invention, first through high-temperature reduction roasting, some metal elements in the ternary material are reduced to metals; at the same time, part of the organic impurities in the cathode material of the waste ternary lithium battery are decomposed into small molecules and removed;

[0020] By using water to leach the roasted product, the leaching of lithium is realized; then a metal extractant is used for extraction to further purify the lithium-containing aqueous phase; finally, carbonate is used to precipitate lithium, thereby forming high-purity lithium carbonate; thus, the recycling of lithium is realized.

[0021] The method of the present invention simplifies the process flow of separating and extracting various metals, reduces the reagents consumed for separating and extracting metal elements, reduces the recovery cost and obtains high-purity lithium carbonate.

[0022] The metal extractant of the present invention is made of acrylate polymer and P204; the acrylate polymer contains lipophilic groups such as phenyl group and silicon-containing group, so that it can effectively adsorb the P204 liquid-phase extractant, thereby improving the stability of the liquid-phase extractant; further improving the extraction efficiency.

[0023] According to some embodiments of the present invention, the reducing agent in step S1 is biochar.

[0024] According to some embodiments of the present invention, the mass ratio of the biochar to the cathode material of the waste ternary lithium battery is 1:10 - 20.

[0025] According to some embodiments of the present invention, the temperature of the roasting in step S1 is 600°C - 900°C.

[0026] According to some embodiments of the present invention, the atmosphere of the roasting in step S1 is a reducing atmosphere.

[0027] According to some embodiments of the present invention, the reducing atmosphere includes hydrogen.

[0028] According to some embodiments of the present invention, the volume fraction of hydrogen in the reducing atmosphere is 10% to 12%.

[0029] According to some embodiments of the present invention, the roasting time is 3 h to 6 h.

[0030] According to some embodiments of the present invention, in step S2, the mass-volume ratio of the roasted product to the water is 1 g: 20 mL to 30 mL.

[0031] According to some embodiments of the present invention, in step S2, the temperature of the water immersion is 70 °C to 90 °C.

[0032] According to some embodiments of the present invention, in step S2, the time of the water immersion is 2 h to 3 h.

[0033] According to some embodiments of the present invention, in step S3, the mass-volume ratio of the metal extractant to the first liquid phase is 1 g: 10 mL to 20 mL.

[0034] According to some embodiments of the present invention, in step S3, a pH regulator is added to control the pH to 3 to 4.

[0035] According to some embodiments of the present invention, the preparation method of the metal extractant includes the following steps:

[0036] Mix the acrylate polymer and P204 for 12 h to 13 h; perform solid-liquid separation and collect the solid phase.

[0037] According to some embodiments of the present invention, the mass ratio of the acrylate polymer to P204 is 1: 2 to 10.

[0038] According to some embodiments of the present invention, the preparation method of the acrylate polymer includes the following steps:

[0039] S01. After mixing isobutyl acrylate, trimethylolpropane trimethacrylate, 3-(4-methoxyphenyl)-2-acrylate propyl ester, tetraallyl silicate and n-butanol, a first mixture is prepared;

[0040] S02. Then, react the first mixture with benzoyl peroxide.

[0041] According to some embodiments of the present invention, in step S01, the temperature of the mixing is 100 °C to 110 °C.

[0042] According to some embodiments of the present invention, in step S01, the time of the mixing is 1 h to 2 h.

[0043] According to some embodiments of the present invention, in step S02, the temperature of the reaction is 110 °C to 125 °C.

[0044] According to some embodiments of the present invention, the reaction time in step S02 is 2 h to 3 h.

[0045] According to some embodiments of the present invention, after the reaction in step S02, the pH value is adjusted to neutral to obtain a neutral emulsion.

[0046] According to some embodiments of the present invention, the temperature of the mixing in step S4 is 70 °C to 80 °C.

[0047] According to some embodiments of the present invention, the pH after the mixing in step S4 is 8 to 11.

[0048] According to some embodiments of the present invention, the carbonate in step S4 includes sodium carbonate. Specific Embodiments

[0049] The following will clearly and completely describe the concept and technical effects generated by the present invention in combination with embodiments to fully understand the purpose, features, and effects of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

[0050] In the description of the present invention, the description of reference terms such as "one embodiment", "some embodiments", "schematic embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0051] For those conditions not specified in the examples, they are carried out according to conventional conditions or conditions recommended by the manufacturer. For reagents or instruments not specified for the manufacturer, they are all conventional products that can be obtained through commercial purchase.

[0052] Example 1

[0053] This example is a method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries, which consists of the following steps:

[0054] S1. Mix the cathode material of waste ternary lithium-ion batteries and biochar (the mass ratio of the cathode material of waste ternary lithium-ion batteries to biochar is 15:1), and then calcine to obtain a calcined product;

[0055] The roasting temperature is 800 °C, the roasting time is 6 h, and the roasting atmosphere is a reducing atmosphere (argon-hydrogen, with the volume fraction of hydrogen being 11%);

[0056] S2. Mix the roasted product with water (the mass-volume ratio of the roasted product to water is 1 g:28 mL) and perform water leaching (the leaching temperature is 90 °C and the time is 3 h) to obtain the first liquid phase;

[0057] S3. Impurity removal:

[0058] Mix the first liquid phase, a metal extractant (the mass-volume ratio of the metal extractant to the first liquid phase is 1 g:15 mL), and a pH regulator (hydrochloric acid with a mass fraction of 30%) and then perform extraction (the pH of extraction is 3.5); after extraction, separate to obtain a lithium-containing aqueous phase;

[0059] S4. Lithium precipitation:

[0060] Mix the lithium-containing aqueous phase with sodium carbonate (pH is 10.5, temperature is 75 °C, time is 3 h), filter after complete precipitation, wash and dry the precipitate to prepare lithium carbonate;

[0061] The metal extractant includes the following raw materials for preparation by weight:

[0062] 1 part of acrylate polymer and 8 parts of P204;

[0063] The preparation method of the metal extractant in this example consists of the following steps:

[0064] Mix the acrylate polymer and P204 and then process for 12 h; perform solid-liquid separation and collect the solid phase.

[0065] The acrylate polymer includes the following raw materials for preparation by weight:

[0066] 100 parts of isobutyl acrylate, 1.5 parts of trimethylolpropane trimethacrylate, 3 parts of 3-(4-methoxyphenyl)-2-acryloyl propyl ester, 12 parts of tetraallyl silicate, 70 parts of n-butanol, and 3 parts of benzoyl peroxide.

[0067] The preparation method of the acrylate polymer in this example consists of the following steps:

[0068] S1. Mix isobutyl acrylate, trimethylolpropane trimethacrylate, 3-(4-methoxyphenyl)-2-acryloyl propyl ester, tetraallyl silicate, and n-butanol and then keep warm at 110 °C for 1.5 h to obtain the first mixture.

[0069] S2. Mix 1 / 2 of the formulated amount of benzoyl peroxide with the first mixture and then keep warm at 115 °C for 1.5 h to obtain the second mixture.

[0070] S3. Mix half of the formula amount of benzoyl peroxide with the second mixture, keep it at 125 °C for 1.5 h, then cool it to room temperature (25 °C), and then add ammonia water (mass fraction 28%) to adjust the pH to neutral.

[0071] Example 2

[0072] This example is a method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries, which consists of the following steps:

[0073] S1. Mix the cathode material of waste ternary lithium-ion batteries with biochar (the mass ratio of the cathode material of waste ternary lithium-ion batteries to biochar is 10:1), and then calcine to obtain a calcined product.

[0074] The calcination temperature is 700 °C, the calcination time is 6 h, and the calcination atmosphere is a reducing atmosphere (argon-hydrogen, the volume fraction of hydrogen is 10%).

[0075] S2. Mix the calcined product with water (the mass-volume ratio of the calcined product to water is 1 g:30 mL), and perform water leaching (the leaching temperature is 70 °C and the time is 3 h) to obtain a first liquid phase.

[0076] S3. Impurity removal:

[0077] Mix the first liquid phase, a metal extractant (the mass-volume ratio of the metal extractant to the first liquid phase is 1 g:20 mL), and a pH regulator (hydrochloric acid with a mass fraction of 30%), and then perform extraction (the pH of extraction is 3.5); after extraction, separate to obtain a lithium-containing aqueous phase.

[0078] S4. Lithium precipitation:

[0079] Mix the lithium-containing aqueous phase with sodium carbonate (pH is 10.5, temperature is 80 °C, time is 3 h), filter after complete precipitation, wash and dry the precipitate to prepare lithium carbonate.

[0080] The metal extractant includes the following raw materials in parts by weight for preparation:

[0081] 1 part of acrylate polymer and 10 parts of P204;

[0082] In this example, the preparation method of the metal extractant refers to that in Example 1.

[0083] The acrylate polymer includes the following raw materials in parts by weight for preparation:

[0084] 100 parts of isobutyl acrylate, 1 part of trimethylolpropane trimethacrylate, 4 parts of 3-(4-methoxyphenyl)-2-acrylate propyl ester, 20 parts of tetraallyl silicate, 70 parts of n-butanol, and 3 parts of benzoyl peroxide.

[0085] In this example, the preparation method of the acrylate polymer was carried out with reference to Example 1.

[0086] Example 3

[0087] This example is a method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries, which consists of the following steps:

[0088] S1. Mix the cathode material of waste ternary lithium-ion batteries and biochar (the mass ratio of the cathode material of waste ternary lithium-ion batteries to biochar is 20:1), and then calcine to obtain a calcined product.

[0089] The calcination temperature is 700 °C, the calcination time is 6 h, and the calcination atmosphere is a reducing atmosphere (argon-hydrogen, the volume fraction of hydrogen is 12%).

[0090] S2. Mix the calcined product and water (the mass-volume ratio of the calcined product to water is 1 g:30 mL), and perform water leaching (the leaching temperature is 80 °C and the time is 3 h) to obtain a first liquid phase.

[0091] S3. Impurity removal:

[0092] Mix the first liquid phase, a metal extractant (the mass-volume ratio of the metal extractant to the first liquid phase is 1 g:10 mL), and a pH regulator (hydrochloric acid with a mass fraction of 30%), and then perform extraction (the pH of extraction is 3.5); after extraction, separate to obtain a lithium-containing aqueous phase.

[0093] S4. Lithium precipitation:

[0094] Mix the lithium-containing aqueous phase and sodium carbonate (pH is 10.5, temperature is 80 °C, time is 3 h), filter after complete precipitation, wash and dry the precipitate to prepare lithium carbonate.

[0095] The metal extractant includes the following raw materials in parts by weight for preparation:

[0096] 1 part of acrylate polymer and 2 parts of P204;

[0097] In this example, the preparation method of the metal extractant was carried out with reference to Example 1.

[0098] The acrylate polymer includes the following raw materials in parts by weight for preparation:

[0099] 100 parts of isobutyl acrylate, 2 parts of trimethylolpropane trimethacrylate, 4 parts of 3-(4-methoxyphenyl)-2-propenyl propionate, 10 parts of tetraallylsilicate, 70 parts of n-butanol, and 3 parts of benzoyl peroxide.

[0100] In this example, the preparation method of the acrylate polymer was carried out with reference to Example 1.

[0101] Example 4

[0102] This embodiment is a method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries, which consists of the following steps:

[0103] S1. Mix the cathode material of waste ternary lithium-ion batteries and biochar (the mass ratio of the cathode material of waste ternary lithium-ion batteries to biochar is 15:1), and then calcine to obtain a calcined product;

[0104] The calcination temperature is 800 °C, the calcination time is 4 h, and the calcination atmosphere is a reducing atmosphere (argon-hydrogen, the volume fraction of hydrogen is 10%);

[0105] S2. Mix the calcined product and water (the mass-volume ratio of the calcined product to water is 1 g:25 mL), and perform water leaching (the leaching temperature is 90 °C and the time is 3 h) to obtain a first liquid phase;

[0106] S3. Impurity removal:

[0107] Mix the first liquid phase, a metal extractant (the mass-volume ratio of the metal extractant to the first liquid phase is 1 g:18 mL), and a pH regulator (hydrochloric acid with a mass fraction of 30%), and then perform extraction (the pH of extraction is 3.5); after extraction, separate to obtain a lithium-containing aqueous phase;

[0108] S4. Lithium precipitation:

[0109] Mix the lithium-containing aqueous phase and sodium carbonate (pH is 10.5, temperature is 80 °C, time is 3 h), filter after complete precipitation, wash and dry the precipitate to prepare lithium carbonate;

[0110] The metal extractant includes the following raw materials in parts by weight for preparation:

[0111] 1 part of acrylate polymer and 8 parts of P204;

[0112] In this embodiment, the preparation method of the metal extractant is carried out with reference to Example 1.

[0113] The acrylate polymer includes the following raw materials in parts by weight for preparation:

[0114] 100 parts of isobutyl acrylate, 1.2 parts of trimethylolpropane trimethacrylate, 3.8 parts of 3-(4-methoxyphenyl)-2-acrylate propyl ester, 18 parts of tetraallyl silicate, 70 parts of n-butanol, and 3 parts of benzoyl peroxide.

[0115] In this embodiment, the preparation method of the acrylate polymer is carried out with reference to Example 1.

[0116] Example 5

[0117] This embodiment is a method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries, which consists of the following steps:

[0118] S1. Mix the cathode material of waste ternary lithium-ion batteries and biochar (the mass ratio of the cathode material of waste ternary lithium-ion batteries to biochar is 12:1), and then calcine to obtain a calcined product;

[0119] The calcination temperature is 700 °C, the calcination time is 6 h, and the calcination atmosphere is a reducing atmosphere (argon-hydrogen, the volume fraction of hydrogen is 10%);

[0120] S2. Mix the calcined product and water (the mass-volume ratio of the calcined product to water is 1 g:25 mL), and perform water leaching (the leaching temperature is 90 °C and the time is 3 h) to obtain a first liquid phase;

[0121] S3. Impurity removal:

[0122] Mix the first liquid phase, a metal extractant (the mass-volume ratio of the metal extractant to the first liquid phase is 1 g:18 mL), and a pH regulator (hydrochloric acid with a mass fraction of 30%), and then perform extraction (the pH of extraction is 3.5); after extraction, separate to obtain a lithium-containing aqueous phase;

[0123] S4. Lithium precipitation:

[0124] Mix the lithium-containing aqueous phase and sodium carbonate (pH is 10.5, temperature is 80 °C, time is 3 h), filter after complete precipitation, wash and dry the precipitate to prepare lithium carbonate;

[0125] The metal extractant includes the following raw materials in parts by weight for preparation:

[0126] 1 part of acrylate polymer and 3 parts of P204;

[0127] In this embodiment, the preparation method of the metal extractant is carried out with reference to Example 1.

[0128] The acrylate polymer includes the following raw materials in parts by weight for preparation:

[0129] 100 parts of isobutyl acrylate, 1.6 parts of trimethylolpropane trimethacrylate, 3 parts of 3-(4-methoxyphenyl)-2-propenyl acrylate, 17 parts of tetraallyl silicate, 70 parts of n-butanol, and 3 parts of benzoyl peroxide.

[0130] In this embodiment, the preparation method of the acrylate polymer is carried out with reference to Example 1.

[0131] Comparative Example 1

[0132] This comparative example is a method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries, which consists of the following steps:

[0133] S1. Mix the spent ternary lithium-ion battery cathode material and biochar (the mass ratio of the spent ternary lithium-ion battery cathode material to biochar is 12:1), and then calcine to obtain a calcined product;

[0134] The calcination temperature is 700 °C, the calcination time is 6 h, and the calcination atmosphere is a reducing atmosphere (argon-hydrogen, the volume fraction of hydrogen is 10%);

[0135] S2. Mix the calcined product and water (the mass-volume ratio of the calcined product to water is 1 g:25 mL) and perform water leaching (the leaching temperature is 90 °C and the time is 3 h) to obtain a first liquid phase;

[0136] S3. Impurity removal:

[0137] Mix the first liquid phase, a metal extractant (the mass-volume ratio of the metal extractant to the first liquid phase is 1 g:18 mL), and a pH regulator (hydrochloric acid with a mass fraction of 30%) and then perform extraction (the pH of extraction is 3.5); after extraction, separate to obtain a lithium-containing aqueous phase;

[0138] S4. Lithium precipitation:

[0139] Mix the lithium-containing aqueous phase and sodium carbonate (pH is 10.5, temperature is 80 °C, time is 3 h), filter after complete precipitation, wash and dry the precipitate to prepare lithium carbonate;

[0140] The metal extractant includes the following raw materials for preparation in parts by weight:

[0141] 1 part of acrylate polymer (the same as in Example 5) and 1 part of P204.

[0142] Comparative Example 2

[0143] This comparative example is a method for recycling lithium carbonate from the spent ternary lithium battery cathode material, which consists of the following steps:

[0144] S1. Mix the spent ternary lithium-ion battery cathode material and biochar (the mass ratio of the spent ternary lithium-ion battery cathode material to biochar is 12:1), and then calcine to obtain a calcined product;

[0145] The calcination temperature is 700 °C, the calcination time is 6 h, and the calcination atmosphere is a reducing atmosphere (argon-hydrogen, the volume fraction of hydrogen is 10%);

[0146] S2. Mix the calcined product and water (the mass-volume ratio of the calcined product to water is 1 g:25 mL) and perform water leaching (the leaching temperature is 90 °C and the time is 3 h) to obtain a first liquid phase;

[0147] S3. Impurity removal:

[0148] Mix the first liquid phase, a metal extractant (the mass-volume ratio of the metal extractant to the first liquid phase is 1 g: 18 mL), and a pH regulator (hydrochloric acid with a mass fraction of 30%) and then perform extraction (the pH of the extraction is 3.5); after extraction, separate to obtain a lithium-containing aqueous phase;

[0149] S4. Precipitate lithium:

[0150] Mix the lithium-containing aqueous phase and sodium carbonate (pH is 10.5, temperature is 80 °C, time is 3 h), filter after complete precipitation, wash and dry the precipitate to prepare lithium carbonate;

[0151] The metal extractant includes the following raw materials for preparation by weight:

[0152] 1 part of acrylate polymer and 5 parts of P204;

[0153] The preparation method of the metal extractant in this comparative example is carried out with reference to Example 1.

[0154] The acrylate polymer includes the following raw materials for preparation by weight:

[0155] 100 parts of isobutyl acrylate, 3 parts of 3-(4-methoxyphenyl)-2-acrylate propyl ester, 17 parts of tetraallyl silicate, 70 parts of n-butanol, and 3 parts of benzoyl peroxide.

[0156] The preparation method of the acrylate polymer in this comparative example consists of the following steps:

[0157] S1. Mix isobutyl acrylate, 3-(4-methoxyphenyl)-2-acrylate propyl ester, tetraallyl silicate, and n-butanol and keep warm at 110 °C for 1.5 h to obtain a first mixture.

[0158] S2. Mix 1 / 2 of the formulated amount of benzoyl peroxide and the first mixture and keep warm at 115 °C for 1.5 h to obtain a second mixture.

[0159] S3. Mix 1 / 2 of the formulated amount of benzoyl peroxide and the second mixture and keep warm at 125 °C for 1.5 h; cool to room temperature (25 °C), and then add ammonia water (mass fraction of 28%) to adjust the pH to neutral.

[0160] Comparative Example 3

[0161] This comparative example is a method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries, which consists of the following steps:

[0162] S1. Mix the cathode material of waste ternary lithium-ion batteries and biochar (the mass ratio of the cathode material of waste ternary lithium-ion batteries to biochar is 12:1) and then roast to obtain a roasted product;

[0163] The roasting temperature is 700 °C, the roasting time is 6 h, and the roasting atmosphere is a reducing atmosphere (argon-hydrogen, with a hydrogen volume fraction of 10%);

[0164] S2. Mix the roasted product with water (the mass-to-volume ratio of the roasted product to water is 1 g:25 mL) and perform water leaching (the leaching temperature is 90 °C and the time is 3 h) to obtain the first liquid phase;

[0165] S3. Impurity removal:

[0166] Mix the first liquid phase, a metal extractant (the mass-to-volume ratio of the metal extractant to the first liquid phase is 1 g:18 mL), and a pH regulator (hydrochloric acid with a mass fraction of 30%) and then perform extraction (the pH of extraction is 3.5); after extraction, separate to obtain a lithium-containing aqueous phase;

[0167] S4. Lithium precipitation:

[0168] Mix the lithium-containing aqueous phase and sodium carbonate (pH is 10.5, temperature is 80 °C, time is 3 h), filter after complete precipitation, wash and dry the precipitate to prepare lithium carbonate;

[0169] The metal extractant comprises the following raw materials in parts by weight for preparation:

[0170] 1 part of acrylate polymer and 5 parts of P204;

[0171] In this comparative example, the preparation method of the metal extractant refers to that in Example 1.

[0172] The acrylate polymer comprises the following raw materials in parts by weight for preparation:

[0173] 100 parts of isobutyl acrylate, 1.6 parts of trimethylolpropane trimethacrylate, 17 parts of tetraallyl silicate, 70 parts of n-butanol, and 3 parts of benzoyl peroxide.

[0174] The preparation method of the acrylate polymer in this comparative example consists of the following steps:

[0175] S1. Mix isobutyl acrylate, trimethylolpropane trimethacrylate, tetraallyl silicate, and n-butanol and keep them at 110 °C for 1.5 h to obtain a first mixture.

[0176] S2. Mix 1 / 2 of the formula amount of benzoyl peroxide with the first mixture and keep them at 115 °C for 1.5 h to obtain a second mixture.

[0177] S3. Mix 1 / 2 of the formula amount of benzoyl peroxide with the second mixture and keep them at 125 °C for 1.5 h; then cool to room temperature (25 °C), and add ammonia water (with a mass fraction of 28%) to adjust the pH to neutral.

[0178] Comparative Example 4

[0179] This comparative example is a method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries, which consists of the following steps:

[0180] S1. Mix the cathode material of waste ternary lithium-ion batteries and biochar (the mass ratio of the cathode material of waste ternary lithium-ion batteries to biochar is 12:1), and then calcine to obtain a calcined product;

[0181] The calcination temperature is 700 °C, the calcination time is 6 h, and the calcination atmosphere is a reducing atmosphere (argon-hydrogen, the volume fraction of hydrogen is 10%);

[0182] S2. Mix the calcined product and water (the mass-volume ratio of the calcined product to water is 1 g:25 mL), and perform water leaching (the leaching temperature is 90 °C and the time is 3 h) to obtain a first liquid phase;

[0183] S3. Impurity removal:

[0184] Mix the first liquid phase, a metal extractant (the mass-volume ratio of the metal extractant to the first liquid phase is 1 g:18 mL), and a pH regulator (hydrochloric acid with a mass fraction of 30%), and then perform extraction (the pH of extraction is 3.5); after extraction, separate to obtain a lithium-containing aqueous phase;

[0185] S4. Lithium precipitation:

[0186] Mix the lithium-containing aqueous phase and sodium carbonate (pH is 10.5, temperature is 80 °C, time is 3 h), filter after complete precipitation, wash and dry the precipitate to prepare lithium carbonate;

[0187] The metal extractant includes the following raw materials in parts by weight for preparation:

[0188] 1 part of acrylate polymer and 5 parts of P204;

[0189] In this comparative example, the preparation method of the metal extractant refers to that in Example 1.

[0190] The acrylate polymer includes the following raw materials in parts by weight for preparation:

[0191] 100 parts of isobutyl acrylate, 1.6 parts of trimethylolpropane trimethacrylate, 3 parts of 3-(4-methoxyphenyl)-2-acrylate propyl ester, 70 parts of n-butanol, and 3 parts of benzoyl peroxide.

[0192] The preparation method of the acrylate polymer in this comparative example consists of the following steps:

[0193] S1. Mix isobutyl acrylate, trimethylolpropane trimethacrylate, 3-(4-methoxyphenyl)-2-acrylate propyl ester, and n-butanol, and keep the temperature at 110 °C for 1.5 h to obtain a first mixture.

[0194] S2. Mix half of the formulated amount of benzoyl peroxide with the first mixture and keep it at 115°C for 1.5 h to obtain a second mixture.

[0195] S3. Mix half of the formulated amount of benzoyl peroxide with the second mixture, keep it at 125°C for 1.5 h, then cool it to room temperature (25°C), and then add ammonia water (mass fraction 28%) to adjust the pH to neutral.

[0196] Comparative Example 5

[0197] This comparative example is a method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries, which consists of the following steps:

[0198] S1. Mix the cathode material of waste ternary lithium-ion batteries with biochar (the mass ratio of the cathode material of waste ternary lithium-ion batteries to biochar is 12:1), and then calcine to obtain a calcined product.

[0199] The calcination temperature is 700°C, the calcination time is 6 h, and the calcination atmosphere is a reducing atmosphere (argon-hydrogen, the volume fraction of hydrogen is 10%).

[0200] S2. Mix the calcined product with water (the mass-volume ratio of the calcined product to water is 1 g:25 mL), and perform water leaching (the leaching temperature is 90°C and the time is 3 h) to obtain a first liquid phase.

[0201] S3. Impurity removal:

[0202] Mix the first liquid phase, a metal extractant (the mass-volume ratio of the metal extractant (P204) to the first liquid phase is 1 g:18 mL), and a pH regulator (hydrochloric acid with a mass fraction of 30%), and then perform extraction (the pH of extraction is 3.5); after extraction, separate to obtain a lithium-containing aqueous phase.

[0203] S4. Lithium precipitation:

[0204] Mix the lithium-containing aqueous phase with sodium carbonate (pH is 10.5, temperature is 80°C, time is 3 h), filter after complete precipitation, wash and dry the precipitate to prepare lithium carbonate.

[0205] The test data of lithium recovery rate and lithium carbonate purity in Examples 1-5 and Comparative Examples 1-5 of the present invention are shown in Table 1.

[0206] Table 1 Test data of lithium recovery rate and lithium carbonate purity in Examples 1-5 and Comparative Examples 1-5 of the present invention

[0207] - Lithium recovery rate (%) Purity of lithium carbonate (%) Example 1 95.53 99.94 Example 2 94.71 99.83 Example 3 94.37 99.62 Example 4 93.96 99.41 Example 5 93.05 99.10 Comparative Example 1 90.01 98.87 Comparative Example 2 91.12 98.73 Comparative Example 3 89.32 98.61 Comparative Example 4 89.12 98.03 Comparative Example 5 87.32 97.39

[0208] In summary, in the present invention, through high-temperature reduction roasting first, some metal elements in the ternary material are reduced to metals; meanwhile, some of the organic impurities in the cathode material of the waste ternary lithium battery are decomposed into small molecules and removed; by using water to leach the roasted product, the leaching of lithium is achieved; then a metal extractant is used for extraction to further purify the lithium-containing aqueous phase; finally, carbonate is used to precipitate lithium, thereby forming high-purity lithium carbonate; thus, the recycling of lithium is realized. The method of the present invention simplifies the process flow of separating and extracting various metals, reduces the reagents consumed for separating and extracting metal elements, reduces the recycling cost and produces high-purity lithium carbonate. The metal extractant of the present invention is made of acrylate polymer and P204; the acrylate polymer contains lipophilic groups such as phenyl and silicon-containing groups, so that it can effectively adsorb the P204 liquid-phase extractant, thereby improving the stability of the liquid-phase extractant; further improving the extraction efficiency.

[0209] In the specific embodiments described above, the purpose, technical solutions and beneficial effects of the present invention have been further described in detail. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for recycling lithium carbonate from the cathode material of waste ternary lithium batteries, characterized in that, It includes the following steps: S1. Reduction: Mix the spent ternary lithium battery cathode material with a reducing agent and then calcine to obtain a calcined product; S2. Water leaching: Mix the calcined product with water for water leaching, and perform solid-liquid separation; collect the liquid phase to obtain a first liquid phase; S3. Impurity removal: Mix the first liquid phase, a metal extractant, and a pH regulator for extraction; after extraction, separate to obtain a lithium-containing aqueous phase; S4. Lithium precipitation: Mix the lithium-containing aqueous phase with a carbonate to obtain lithium carbonate; The metal extractant includes the following preparation raw materials: Acrylate polymer and P204; The acrylate polymer includes the following preparation raw materials in parts by weight: 100 parts of isobutyl acrylate, 1 to 2 parts of trimethylolpropane trimethacrylate, 3 to 4 parts of 3-(4-methoxyphenyl)-2-acrylate propyl ester, 10 to 20 parts of tetraallyl silicate, 50 to 70 parts of n-butanol, and 0.1 to 5 parts of benzoyl peroxide; The preparation method of the acrylate polymer includes the following steps: S01. Mix isobutyl acrylate, trimethylolpropane trimethacrylate, 3-(4-methoxyphenyl)-2-acrylate propyl ester, tetraallyl silicate, and n-butanol to obtain a first mixture; S02. Then mix the first mixture with benzoyl peroxide for reaction.

2. The method according to claim 1, characterized in that, The reducing agent in step S1 is biochar.

3. The method according to claim 1, wherein The calcination temperature in step S1 is 600°C to 900°C.

4. The method according to claim 1, wherein The calcination atmosphere in step S1 is a reducing atmosphere.

5. The method according to claim 1, characterized in that The mass-volume ratio of the calcined product to the water in step S2 is 1 g: 20 mL to 30 mL.

6. The method according to claim 1, wherein The water leaching temperature in step S2 is 70°C to 90°C.

7. The method according to claim 1, characterized in that, The mass-volume ratio of the metal extractant to the first liquid phase in step S3 is 1 g: 10 mL to 20 mL.

8. The method according to claim 1, wherein Add a pH regulator in step S3 to control the pH to 3 to 4.

9. The method according to claim 1, wherein The mixing temperature in step S4 is 70°C to 80°C.

10. The method according to claim 1, characterized in that, The pH after mixing in step S4 is 8 to 11.