A method for extracting and recovering lithium from lithium-containing wastewater

Abstract

The application discloses a method for extracting and recovering lithium from lithium-containing wastewater, and belongs to the technical field of lithium-containing wastewater recovery. The method comprises the following steps: extracting lithium-containing wastewater by using an organic extraction reagent, obtaining a first organic phase loaded with lithium after phase separation; washing the first organic phase, and obtaining a second organic phase after phase separation; and stripping the second organic phase with a stripping agent to obtain a lithium-containing solution; the extractant in the organic extraction reagent comprises a phosphine-based extractant and a ketone-based extractant; and the stripping agent is an organic acid. The extraction system can realize high selectivity and high extraction rate of lithium ions in the lithium-containing wastewater under neutral or weak alkaline conditions without adding ferric chloride as a co-extraction agent. The method has a short process flow and is relatively simple to operate, and the organic extraction reagent can be recycled. In addition, the use of an organic acid as the stripping agent reduces the corrosion of the equipment in the stripping process, and improves the safety and economic benefits.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium-containing wastewater recovery, and particularly relates to a method for extracting and recovering lithium from lithium-containing wastewater. BACKGROUND

[0002] Lithium is widely used in medicine, glass, ceramics, lubricating grease, alloy and new energy fields, and is known as "white oil". In the field of new energy, about 60% of lithium consumption is related to batteries, and the adoption of lithium battery driven personal electronic products, electric vehicles and energy storage systems has steadily increased. A battery for an electric vehicle requires about 20 kg of lithium. A 10 MW-hour energy storage system requires at least 700 kg of lithium. With the increasing demand for lithium batteries, it is necessary to develop lithium resources extraction and recovery.

[0003] There are many methods for extracting lithium at present, and solvent extraction has great advantages in lithium extraction process due to its high separation coefficient of metal ions, high selectivity, simple operation, low energy consumption, low cost and large processing capacity.

[0004] The extraction system for extracting lithium is usually TBP (tributyl phosphate) + FeCl3 system. The extractant TBP in the TBP + FeCl3 extraction system is easy to prepare, low in price and high in selectivity to lithium. However, the solubility of TBP in water is relatively large, in addition, to prevent the hydrolysis of iron, the brine needs to maintain a certain acidity, and a higher concentration of acid is needed to strip the metal ions during stripping, and the high concentration of acid will break the phosphine oxygen bond of TBP, causing the degradation of TBP. In addition, the extractant TBP needs to add ferric chloride to promote the extraction rate of lithium. Therefore, it is urgent to provide a method for recovering lithium with good lithium selectivity, clear phase separation interface and slow extractant loss.

[0005] In addition, the whole process of solvent extraction method includes extraction, washing, stripping, regeneration and the like. In the process of stripping lithium ions, acid is usually used to strip lithium into the aqueous phase, and then after adjusting the pH of the aqueous phase, saturated sodium carbonate is added to convert lithium ions into battery-grade lithium carbonate as the product terminal. However, the above process has great corrosiveness to the equipment, which shortens the service life of the equipment. Therefore, a suitable method is also needed to obtain lithium products to reduce the corrosion of the equipment and reduce the cost.

[0006] In view of this, the present application is proposed. SUMMARY

[0007] The purpose of the present application includes providing a method for extracting and recovering lithium from lithium-containing wastewater to solve or improve at least one of the above technical problems.

[0008] The present application can be achieved as follows:

[0009] In a first aspect, the present application provides a method for extracting and recovering lithium from lithium-containing wastewater, comprising the following steps:

[0010] extracting the neutral or alkaline lithium-containing wastewater with an organic extraction reagent to obtain a first organic phase loaded with lithium after phase separation;

[0011] washing the first organic phase, and obtaining a second organic phase after phase separation;

[0012] stripping the second organic phase with a stripping agent to obtain a lithium-containing solution and a third organic phase after phase separation;

[0013] wherein the extractant contained in the organic extraction reagent includes a phosphine-based extractant and a ketone-based extractant; and the stripping agent is an organic acid.

[0014] In an optional embodiment, the phosphine-based extractant includes an oxidized phosphine substance having three alkyl chains.

[0015] In an optional embodiment, the phosphine-based extractant includes at least one of trioctylphosphine oxide, trihexylphosphine oxide, trinonylphosphine oxide, and tridecylphosphine oxide.

[0016] In an optional embodiment, the phosphine-based extractant includes at least one of Cyanex 923 and TRPO.

[0017] In an optional embodiment, the ketone-based extractant includes at least one of an alkylphenyl-methyl-β-diketone and an alkylphenyl-ethyl-β-diketone.

[0018] In an optional embodiment, the alkylphenyl-methyl-β-diketone includes at least one of dodecylphenyl-methyl-β-diketone and tetradecylphenyl-methyl-β-diketone.

[0019] In an optional embodiment, the dodecylphenyl-methyl-β-diketone includes at least one of LIX 54, LIX 54-100, Metrax 54, and Metrax 54-100.

[0020] In an optional embodiment, the alkylphenyl-ethyl-β-diketone includes at least one of dodecylphenyl-ethyl-β-diketone, tetradecylphenyl-ethyl-β-diketone, and decylphenyl-ethyl-β-diketone.

[0021] In an optional embodiment, the mass ratio of the phosphine-based extractant to the ketone-based extractant in the extractant is 1:9 to 9:1.

[0022] In an optional embodiment, the mass ratio of the phosphine-based extractant to the ketone-based extractant is (1-3):(1-3).

[0023] In optional embodiments, the volume percentage of the extractant contained in the organic extraction reagent is 10% to 60%.

[0024] In optional embodiments, the organic extraction reagent further comprises a diluent.

[0025] In optional embodiments, the diluent comprises sulfonated kerosene.

[0026] In optional embodiments, the extraction comprises at least one of the following features:

[0027] Feature 1: the volume ratio of the organic extraction reagent to the lithium-containing wastewater is 5:1 to 1:5;

[0028] Feature 2: the extraction temperature is 20°C to 70°C;

[0029] Feature 3: the extraction time is 0.05h to 5h;

[0030] Feature 4: the extraction stage is 1 to 10 stages;

[0031] Feature 5: the extraction is performed at a rotation speed of 150rpm to 450rpm.

[0032] In optional embodiments, the pH value of the lithium-containing wastewater is adjusted to neutral or alkaline before the extraction.

[0033] In optional embodiments, an alkaline solution is used to adjust the pH value of the lithium-containing wastewater.

[0034] In optional embodiments, the alkaline solution comprises a carbonate solution or a hydroxide solution.

[0035] In optional embodiments, after the pH value is adjusted by the carbonate solution, the concentration of carbonate in the lithium-containing wastewater is 0.5 times to 1.5 times the concentration of lithium; or, after the pH value is adjusted by the hydroxide solution, the concentration of hydroxide in the lithium-containing wastewater is 1 times to 3 times the concentration of lithium.

[0036] In optional embodiments, the washing comprises at least one of the following features:

[0037] Feature 6: the washing reagent used for washing comprises at least one of water, a lithium-containing salt solution, and an acid;

[0038] Feature 7: the volume ratio of the first organic phase to the washing reagent is 20:1 to 1:5;

[0039] Feature 8: the washing temperature is 20°C to 70°C;

[0040] Feature 9: the washing time is 0.05h to 5h;

[0041] Feature 10: the washing is performed for 1 to 10 stages.

[0042] Feature 11: the washing is performed at a rotation speed of 150 rpm to 450 rpm.

[0043] In an optional embodiment, the lithium salt concentration of the lithium salt solution is greater than 0 mol / L and does not exceed 1 mol / L, or the concentration of the acid is greater than 0 mol / L and does not exceed 1 mol / L.

[0044] In an optional embodiment, the stripping includes at least one of the following features:

[0045] Feature 12: the stripping agent used for the stripping is an aqueous organic acid solution.

[0046] Feature 13: the volume ratio of the second organic phase to the stripping agent is 20:1 to 1:5.

[0047] Feature 14: the stripping temperature is 20℃ to 70℃.

[0048] Feature 15: the stripping time is 0.05h to 5h.

[0049] Feature 16: the stripping is performed for 1 to 10 stages.

[0050] Feature 17: the stripping is performed at a rotation speed of 150 rpm to 450 rpm.

[0051] In an optional embodiment, the concentration of the aqueous organic acid solution is 0.1 mol / L to 6 mol / L.

[0052] In an optional embodiment, further comprising: regenerating the third organic phase.

[0053] In an optional embodiment, the regenerating agent used for the regeneration includes at least one of water, an inorganic salt, and a base.

[0054] In an optional embodiment, the inorganic salt includes a carbonate.

[0055] In an optional embodiment, the inorganic salt includes at least one of sodium carbonate and potassium carbonate.

[0056] In an optional embodiment, the base includes at least one of sodium hydroxide and potassium hydroxide.

[0057] In an optional embodiment, the lithium-containing wastewater includes lithium-containing wastewater generated in a ternary battery powder recycling process.

[0058] The beneficial effects of the present application include:

[0059] By using the organic extraction reagent including phosphine extraction agent and ketone extraction agent to extract the lithium-containing wastewater, high selectivity and high extraction rate of lithium ions in the lithium-containing wastewater can be achieved under neutral or weak alkaline conditions without adding ferric chloride as a co-extraction agent. Moreover, the above-mentioned extraction agent can be recycled multiple times, and the extraction operation is simple. Accordingly, the recovery process is simple, easy to operate, and low in cost. In addition, using organic acid as a stripping agent reduces the corrosion of the equipment during the stripping process compared with the existing technology using inorganic acid such as sulfuric acid or hydrochloric acid, thereby improving safety and economic benefits. BRIEF DESCRIPTION OF DRAWINGS

[0060] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0061] Figure 1 The main process flow chart of the method for extracting and recovering lithium from lithium-containing wastewater provided by the present application. DETAILED DESCRIPTION

[0062] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be described clearly and completely. The specific conditions not mentioned in the embodiments are carried out according to the conventional conditions or the conditions recommended by the manufacturer. The reagents or instruments not mentioned by the manufacturer are all conventional products that can be purchased in the market.

[0063] The method for extracting and recovering lithium from lithium-containing wastewater provided by the present application will be described in detail as follows.

[0064] The present application provides a method for extracting and recovering lithium from lithium-containing wastewater, which combines Figure 1 and includes the following steps:

[0065] The neutral or alkaline lithium-containing wastewater is extracted by using an organic extraction reagent, and a first organic phase loaded with lithium is obtained after phase separation;

[0066] The first organic phase is washed, and a second organic phase is obtained after phase separation;

[0067] The second organic phase is stripped with a stripping agent, and a lithium-containing solution and a third organic phase are obtained after phase separation;

[0068] The extraction agent contained in the organic extraction reagent includes phosphine extraction agent and ketone extraction agent; and the stripping agent is organic acid.

[0069] In the above organic extraction reagents, the phosphine-based extraction agent is mainly used for synergistic extraction of lithium ions with the ketone-based extraction agent, and can improve the phase interface. In the present application, the phosphine-based extraction agent is a general term, including both the extraction agent containing P-C bond and the extraction agent not containing P-C bond (such extraction agent is also commonly referred to as "phosphorus-based extraction agent"). The ketone-based extraction agent mainly plays a role in extracting lithium ions. Through enol tautomerization of the ketone-based extraction agent under alkaline conditions, hydrogen ions are hydrolyzed out to exchange cations with lithium ions in the aqueous phase, thereby completing the extraction of lithium ions. The phosphine-based extraction agent provided by the present application can effectively extract lithium ions in lithium-containing wastewater when used in combination with the ketone-based extraction agent.

[0070] By using the above specific organic extraction reagent, lithium ions in lithium-containing wastewater can be extracted with high selectivity and high extraction rate under neutral or weak alkaline conditions without adding ferric chloride as a co-extraction agent. Moreover, the extraction reagents used in the whole process can be recycled multiple times, and the extraction operation is simple.

[0071] In some embodiments, the lithium-containing wastewater includes lithium-containing wastewater generated in a ternary battery powder recycling process, which can be sulfate raffinate wastewater generated in a ternary battery powder recycling process, and can also be lithium-containing wastewater from other sources.

[0072] In some embodiments, the phosphine-based extraction agent can include an oxidized phosphine substance having three alkyl chains, for example, at least one of trioctylphosphine oxide, trihexylphosphine oxide, trinonylphosphine oxide and tridecylphosphine oxide. In some specific embodiments, the phosphine-based extraction agent can include at least one of Cyanex 923 and TRPO.

[0073] In some embodiments, the ketone-based extraction agent can include at least one of an alkylphenyl-methyl-β-diketone and an alkylphenyl-ethyl-β-diketone. The alkylphenyl-methyl-β-diketone exemplarily but non-limitatively includes at least one of dodecylphenyl-methyl-β-diketone and tetradecylphenyl-methyl-β-diketone. The dodecylphenyl-methyl-β-diketone exemplarily but non-limitatively includes at least one of LIX 54, LIX 54-100, Metrax 54 and Metrax 54-100. The alkylphenyl-ethyl-β-diketone exemplarily but non-limitatively includes at least one of dodecylphenyl-ethyl-β-diketone, tetradecylphenyl-ethyl-β-diketone and decylphenyl-ethyl-β-diketone.

[0074] In some embodiments, the mass ratio of the phosphine-based extractant and the ketone-based extractant in the extractant can be 1:9 to 9:1, such as 1:9, 1:8, 1:7, 1:6, 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, or 9:1, etc., and can also be other values within the range of 1:9 to 9:1. When the mass ratio of the phosphine-based extractant and the ketone-based extractant is (1-3):(1-3), such as 1:1, 1:2, 1:3, 2:1, 2:3, 3:1, 3:2, etc., it can have a more optimal extraction effect on lithium ions.

[0075] In some embodiments, the volume percentage of the extractant contained in the organic extractant reagent can be 10% to 60%, such as 10%, 20%, 30%, 40%, 50%, or 60%, etc., and can also be other values within the range of 10% to 60%.

[0076] If the volume percentage of the extractant contained in the organic extractant reagent is less than 10%, it is not conducive to the extraction of lithium; if the volume percentage of the extractant contained in the organic extractant reagent is greater than 60%, it can easily lead to excessive viscosity of the organic phase, affecting mass transfer and reducing the extraction of lithium.

[0077] The above-mentioned organic extractant reagent also includes a diluent. The diluent can exemplarily but non-limitingly include sulfonated kerosene, etc.

[0078] As for the extraction stage, the volume ratio of the organic extractant reagent to the lithium-containing wastewater can be 5:1 to 1:5, such as 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, or 1:5, etc., and can also be other values within the range of 5:1 to 1:5.

[0079] If the volume ratio of the organic extractant reagent to the lithium-containing wastewater is greater than 5:1 (such as 8:1), the organic reagent is excessive, leading to poor selectivity of lithium ions in the extraction wastewater. If the volume ratio of the organic extractant reagent to the lithium-containing wastewater is less than 1:5 (such as 1:8), it can affect the extraction depth of the extractant on lithium ions to some extent.

[0080] The extraction temperature can be 20°C to 70°C, such as 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, or 70°C, etc., and can also be other values within the range of 20°C to 70°C.

[0081] If the extraction temperature is lower than 20°C, it can affect the flowability of the liquid and reduce the extraction effect; based on the fact that extraction is an exothermic reaction, if the extraction temperature is higher than 70°C, it can also affect the extraction effect.

[0082] The extraction time can be 0.05 h to 5 h, such as 0.05 h, 0.1 h, 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h or 5 h, or other values within the range of 0.05 h to 5 h.

[0083] The extraction stages can be one stage, or multiple stages, and the number of stages of the multiple extraction can be 2, 3, 4 or more. In some alternative embodiments, the number of stages of the multiple extraction can be 2 to 10. The above-mentioned multiple extraction can be performed in the manner of multiple countercurrent extraction.

[0084] The extraction can be performed at a rotation speed of 150 rpm to 450 rpm, such as 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm or 450 rpm.

[0085] Through the above-mentioned extraction treatment, lithium can be effectively separated, and a first organic phase loaded with a large amount of lithium is obtained. If sodium is contained in the lithium-containing wastewater, in addition to a large amount of lithium, a small amount or trace amount of sodium is also loaded in the first organic phase obtained by the extraction treatment. At the same time, in addition to the first organic phase, a first solution is also obtained by phase separation, and the subsequent treatment of the first solution is not limited.

[0086] In some embodiments, the pH value of the lithium-containing wastewater can be adjusted to neutral or alkaline before the above-mentioned extraction operation is performed.

[0087] Exemplarily, the pH value of the adjusted lithium-containing wastewater is 9.5 to 13.5, such as 9.5, 10, 10.5, 11, 11.5, 12, 12.5, 13 or 13.5.

[0088] Exemplarily, an alkaline solution can be used to adjust the pH value of the lithium-containing wastewater. The alkaline solution can include a carbonate solution (such as a sodium carbonate solution and a potassium carbonate solution) or a hydroxide solution (such as a potassium hydroxide or sodium hydroxide solution). By using a carbonate solution or a hydroxide solution to adjust the pH value of the lithium-containing solution, the acidity of the lithium-containing wastewater is adjusted at low cost and high efficiency.

[0089] The concentration of carbonate in the lithium-containing wastewater after adjusting the pH value with the carbonate solution can be 0.5 times to 1.5 times (such as 0.5 times, 1 times or 1.5 times) the concentration of lithium. The concentration of hydroxide in the lithium-containing wastewater after adjusting the pH value with the hydroxide solution can be 1 times to 3 times (such as 1 times, 1.5 times, 2 times, 2.5 times or 3 times) the concentration of lithium. At the above-mentioned concentrations, better selectivity for lithium can be achieved.

[0090] If the lithium-containing wastewater is not subjected to pH value adjustment, when the lithium-containing wastewater is acidic, the extraction effect of lithium is poor when the organic extraction reagent is used to extract the lithium-containing wastewater.

[0091] In some embodiments, the washing reagent used for washing includes at least one of water, a lithium salt solution and an acid. The water can be pure water. The lithium salt concentration of the lithium salt solution is greater than 0 mol / L and not more than 1 mol / L (such as 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 0.8 mol / L or 1 mol / L, etc.). The concentration of the acid is greater than 0 mol / L and not more than 1 mol / L (such as 0.1 mol / L, 0.2 mol / L, 0.5 mol / L, 0.8 mol / L or 1 mol / L, etc.).

[0092] The first organic phase is washed by using the above washing reagent to remove as much sodium as possible from the first organic phase. The lithium ions in the lithium salt solution can exchange sodium ions, and the hydrogen ions in the acid can also exchange sodium ions.

[0093] The volume ratio of the first organic phase to the washing reagent can be 20:1 to 1:5, such as 20:1, 18:1, 15:1, 10:1, 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4 or 1:5, etc., or other values within the range of 20:1 to 1:5.

[0094] The washing temperature can be 20℃ to 70℃, such as 20℃, 25℃, 30℃, 35℃, 40℃, 45℃, 50℃, 55℃, 60℃, 65℃ or 70℃, etc., or other values within the range of 20℃ to 70℃.

[0095] The washing time can be 0.05h to 5h, such as 0.05h, 0.1h, 0.5h, 1h, 1.5h, 2h, 2.5h, 3h, 3.5h, 4h, 4.5h or 5h, etc., or other values within the range of 0.05h to 5h.

[0096] The washing stage can be one stage, or multiple stages. The number of stages of the multiple-stage washing can be 2, 3, 4 or more. In some optional embodiments, the number of stages of the multiple-stage washing can be 2 to 10. The above multiple-stage washing can be carried out by using a multi-stage countercurrent washing method.

[0097] The washing can be carried out at a rotation speed of 150rpm to 450rpm (such as 150rpm, 200rpm, 250rpm, 300rpm, 350rpm, 400rpm or 450rpm, etc.).

[0098] The second organic phase loaded with lithium is obtained by the above washing treatment. At the same time, in addition to the second organic phase, a second solution is also obtained by phase separation, and the subsequent treatment of the second solution is not limited.

[0099] In some embodiments, the stripping agent used for stripping is an aqueous organic acid solution. The concentration of the aqueous organic acid solution can be 0.1 mol / L to 6 mol / L, such as 0.1 mol / L, 0.5 mol / L, 1 mol / L, 2 mol / L, 3 mol / L, 4 mol / L, 5 mol / L, or 6 mol / L, etc. The aqueous organic acid can exemplarily but non-limitingly include at least one of oxalic acid (ethanedioic acid), benzenesulfonic acid, citric acid, and lactic acid.

[0100] By using an aqueous organic acid solution as a stripping agent, the corrosion of the equipment during stripping is greatly reduced, which is conducive to prolonging the service life of the equipment, improving safety and economic benefits. Moreover, by using an aqueous organic acid solution as a stripping agent, the lithium organic acid obtained by stripping can be directly used as an electrolyte for lithium ion batteries, which is conducive to reducing the complexity of the components of the entire extraction system.

[0101] The volume ratio of the second organic phase to the stripping agent can be 20:1 to 1:5, such as 20:1, 15:1, 10:1, 5:1, 4:1, 3:1, 2:1, 1:1, 1:2, 1:3, 1:4, or 1:5, etc., or other values within the range of 20:1 to 1:5.

[0102] The stripping temperature can be 20°C to 70°C, such as 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, or 70°C, etc., or other values within the range of 20°C to 70°C.

[0103] The stripping time can be 0.05 h to 5 h, such as 0.05 h, 0.1 h, 0.5 h, 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h, 4.5 h, or 5 h, etc., or other values within the range of 0.05 h to 5 h.

[0104] The stripping stage can be one stage, or multiple stages, and the number of stages of the multiple-stage stripping can be 2, 3, 4, or more. In some optional embodiments, the number of stages of the multiple-stage stripping can be 2 to 10. The above multiple-stage stripping can be performed in a multi-stage countercurrent stripping manner.

[0105] The stripping can be performed at a rotation speed of 150 rpm to 450 rpm, such as 150 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, or 450 rpm, etc.

[0106] Through the above stripping treatment and phase separation treatment, a lithium-containing solution and a third organic phase can be obtained.

[0107] In some embodiments, the third organic phase can be regenerated.

[0108] The regeneration reagent used for regeneration can include at least one of water, an inorganic salt, and a base. Among them, the water can be pure water. The inorganic salt can include a carbonate, such as at least one of sodium carbonate and potassium carbonate. The base can include at least one of sodium hydroxide and potassium hydroxide.

[0109] The regenerated organic phase obtained by regeneration can be recycled for use in the extraction stage as an extraction reagent.

[0110] As described above, the method for extracting and recovering lithium from lithium-containing wastewater provided by the present application has good selectivity for lithium, a clear phase separation interface, and can slow down the loss of the extractant. Moreover, the method has a simple process, is easy to operate, has low cost, has less corrosion to equipment, and is conducive to prolonging the service life of the equipment.

[0111] The features and performance of the present application are further described in detail below in conjunction with examples.

[0112] Example 1

[0113] The present example provides a method for recovering lithium from lithium-containing wastewater after recovering nickel, cobalt and manganese from ternary battery powder, comprising the following steps:

[0114] S1: Adjusting the pH value of the lithium-containing solution.

[0115] The pH value of the lithium-containing solution is adjusted to 10.5 using a saturated sodium carbonate solution, wherein the concentration of carbonate in the lithium-containing solution after adjusting the pH value is 0.6 times the concentration of lithium.

[0116] S2: Extraction.

[0117] The lithium-containing wastewater after adjusting the pH value in S1 is extracted with an organic extraction reagent, wherein the organic extraction reagent is obtained by mixing an extractant (obtained by mixing TRPO and LIX 54 at a mass ratio of 1:1) and sulfonated kerosene at a volume ratio of 40:60.

[0118] Specifically, the organic extraction reagent and the lithium-containing wastewater after adjusting the pH value are mixed at a volume ratio of 1:4, and four-stage countercurrent extraction is carried out at 25°C and 350 rpm. The total extraction time is 0.1 h. After phase separation, a first solution and a first organic phase loaded with a large amount of lithium and a small amount of sodium are obtained.

[0119] S3: Washing.

[0120] The first organic phase was mixed with a washing reagent (lithium sulfate solution with a concentration of 0.1 mol / L) at a volume ratio of 10:1, and six-stage countercurrent washing was performed at 25°C and 350 rpm for a total washing time of 0.2 h to remove the trace amount of sodium ions loaded. After phase separation, a second solution and a second organic phase loaded with high-purity lithium were obtained.

[0121] S4: stripping.

[0122] The second organic phase was mixed with a stripping reagent (oxalic acid aqueous solution with a concentration of 2 mol / L) at a volume ratio of 5:1, and three-stage countercurrent stripping was performed at 25°C and 350 rpm for a total stripping time of 0.2 h. After phase separation, a lithium oxalate solution and a third organic phase were obtained.

[0123] Example 2

[0124] The present example provides a method for recovering lithium from lithium-containing wastewater after recovering nickel, cobalt and manganese from ternary battery powder, comprising the following steps:

[0125] S1: adjusting the pH value of the lithium-containing solution.

[0126] The pH value of the lithium-containing solution was adjusted to 10.5 using a saturated sodium carbonate solution, wherein the concentration of carbonate in the lithium-containing solution after adjusting the pH value was 0.65 times the concentration of lithium.

[0127] S2: extraction.

[0128] The lithium-containing wastewater after adjusting the pH value in S1 was extracted using an organic extraction reagent, wherein the organic extraction reagent was obtained by mixing an extractant (obtained by mixing TRPO and Metrax 54 at a mass ratio of 1:3) and sulfonated kerosene at a volume ratio of 40:60.

[0129] Specifically, the organic extraction reagent was mixed with the lithium-containing wastewater after adjusting the pH value at a volume ratio of 1:4, and four-stage countercurrent extraction was performed at 30°C and 300 rpm for a total extraction time of 0.1 h. After phase separation, a first solution and a first organic phase loaded with a large amount of lithium and a trace amount of sodium were obtained.

[0130] S3: washing.

[0131] The first organic phase was mixed with a washing reagent (lithium sulfate solution with a concentration of 0.05 mol / L) at a volume ratio of 10:1, and six-stage countercurrent washing was performed at 30°C and 300 rpm for a total washing time of 0.2 h to remove the trace amount of sodium ions loaded. After phase separation, a second solution and a second organic phase loaded with high-purity lithium were obtained.

[0132] S4: stripping.

[0133] The second organic phase was mixed with a stripping agent (a 1 mol / L oxalic acid aqueous solution) at a volume ratio of 5:1, and was subjected to three-stage countercurrent stripping at 30°C and 300 rpm for a total stripping time of 0.2 h. After phase separation, a lithium oxalate solution and a third organic phase were obtained.

[0134] Example 3

[0135] The present example provides a method for recovering lithium from lithium-containing wastewater after recovering nickel, cobalt and manganese from ternary battery powder, comprising the following steps:

[0136] S1: adjusting the pH value of the lithium-containing solution.

[0137] The pH value of the lithium-containing solution was adjusted to 10 using a saturated sodium carbonate solution, wherein the concentration of carbonate in the lithium-containing solution after adjusting the pH value was 0.6 times the concentration of lithium.

[0138] S2: extraction.

[0139] The lithium-containing wastewater after adjusting the pH value in S1 was extracted using an organic extraction reagent, wherein the organic extraction reagent was obtained by mixing an extractant (obtained by mixing Cyanex 923 and Metrax 54-100 at a mass ratio of 1:3) and sulfonated kerosene at a volume ratio of 30:70.

[0140] Specifically, the organic extraction reagent was mixed with the lithium-containing wastewater after adjusting the pH value at a volume ratio of 1:2, and was subjected to five-stage countercurrent extraction at 30°C and 300 rpm for a total extraction time of 0.2 h. After phase separation, a first solution and a first organic phase loaded with a large amount of lithium and a small amount of sodium were obtained.

[0141] S3: washing.

[0142] The first organic phase was mixed with a washing reagent (a 0.03 mol / L lithium sulfate solution) at a volume ratio of 15:1, and was subjected to four-stage countercurrent washing at 25°C and 350 rpm for a total washing time of 0.1 h to remove the small amount of sodium ions loaded. After phase separation, a second solution and a second organic phase loaded with high-purity lithium were obtained.

[0143] S4: stripping.

[0144] The second organic phase was mixed with a stripping agent (a 6 mol / L benzenesulfonic acid aqueous solution) at a volume ratio of 15:1, and was subjected to three-stage countercurrent stripping at 25°C and 350 rpm for a total stripping time of 0.1 h. After phase separation, a lithium benzenesulfonate solution and a third organic phase were obtained.

[0145] Example 4

[0146] The embodiment provides a method for recovering lithium from lithium-containing wastewater after recovering nickel, cobalt and manganese from ternary battery powder, and the method comprises the following steps:

[0147] S1: adjusting the pH value of the lithium-containing solution.

[0148] The pH value of the lithium-containing solution is adjusted to 11 by using a saturated sodium carbonate solution, and the concentration of carbonate in the lithium-containing solution after the pH value is adjusted is 0.7 times the concentration of lithium.

[0149] S2: extraction.

[0150] The lithium-containing wastewater after the pH value is adjusted in S1 is extracted by using an organic extraction reagent, and the organic extraction reagent is obtained by mixing an extractant (obtained by mixing tri-octyl phosphine oxide and LIX 54 at a mass ratio of 1:3) and sulfonated kerosene at a volume ratio of 45:55.

[0151] Specifically, the organic extraction reagent and the lithium-containing wastewater after the pH value is adjusted are mixed at a volume ratio of 1:4, five-stage countercurrent extraction is carried out at 25 DEG C and 350 rpm, and the total extraction time is 0.1 h. After phase separation, a first solution and a first organic phase loaded with a large amount of lithium and a small amount of sodium are obtained.

[0152] S3: washing.

[0153] The first organic phase and a washing reagent (a lithium sulfate solution with a concentration of 0.05 mol / L) are mixed at a volume ratio of 15:1, three-stage countercurrent washing is carried out at 25 DEG C and 350 rpm, and the total washing time is 0.1 h, so that the small amount of sodium ions loaded is removed. After phase separation, a second solution and a second organic phase loaded with high-purity lithium are obtained.

[0154] S4: stripping.

[0155] The second organic phase and a stripping agent (a citric acid aqueous solution with a concentration of 2 mol / L) are mixed at a volume ratio of 20:1, three-stage countercurrent stripping is carried out at 25 DEG C and 350 rpm, and the total stripping time is 0.1 h. After phase separation, a lithium citrate solution and a third organic phase are obtained.

[0156] Embodiment 5

[0157] The embodiment provides a method for recovering lithium from lithium-containing wastewater after recovering nickel, cobalt and manganese from ternary battery powder, and the method comprises the following steps:

[0158] S1: adjusting the pH value of the lithium-containing solution.

[0159] The pH value of the lithium-containing solution is adjusted to 10 by using a saturated sodium carbonate solution, and the concentration of carbonate in the lithium-containing solution after the pH value is adjusted is 0.55 times the concentration of lithium.

[0160] S2: Extraction.

[0161] The organic extraction reagent used in S1 is prepared by mixing tri-n-octylphosphine oxide and LIX 54 at a mass ratio of 1:2, and then mixing the mixture with sulfonated kerosene at a volume ratio of 40:60.

[0162] Specifically, the organic extraction reagent is mixed with the lithium-containing wastewater after pH adjustment at a volume ratio of 1:4, and four-stage countercurrent extraction is carried out at 30°C and 350 rpm, with a total extraction time of 0.2 h. After phase separation, a first solution and a first organic phase loaded with a large amount of lithium and a small amount of sodium are obtained.

[0163] S3: Washing.

[0164] The first organic phase is mixed with a washing reagent (a lithium sulfate solution with a concentration of 0.02 mol / L) at a volume ratio of 10:1, and four-stage countercurrent washing is carried out at 30°C and 350 rpm, with a total washing time of 0.2 h, to remove the small amount of sodium ions loaded. After phase separation, a second solution and a second organic phase loaded with high-purity lithium are obtained.

[0165] S4: Stripping.

[0166] The second organic phase is mixed with a stripping agent (a lactic acid aqueous solution with a concentration of 4 mol / L) at a volume ratio of 10:1, and three-stage countercurrent stripping is carried out at 30°C and 350 rpm, with a total stripping time of 0.2 h. After phase separation, a lithium lactate solution and a third organic phase are obtained.

[0167] Example 6

[0168] The present embodiment provides a method for recovering lithium from lithium-containing wastewater after recovering nickel, cobalt and manganese from ternary battery powder, comprising the following steps:

[0169] S1: Adjusting the pH value of the lithium-containing solution.

[0170] The pH value of the lithium-containing solution is adjusted to 12.5 using a saturated sodium carbonate solution, wherein the concentration of carbonate ions in the lithium-containing solution after pH adjustment is 1 times the concentration of lithium.

[0171] S2: Extraction.

[0172] The organic extraction reagent used in S1 is prepared by mixing tri-n-octylphosphine oxide and LIX 54-100 at a mass ratio of 1:3, and then mixing the mixture with sulfonated kerosene at a volume ratio of 10:90.

[0173] Specifically, the organic extraction reagent and the lithium-containing wastewater after pH adjustment are mixed at a volume ratio of 5:1, and ten-stage countercurrent extraction is carried out at 20°C and 450 rpm, and the total extraction time is 5h. After phase separation, a first solution and a first organic phase are obtained.

[0174] S3: Washing.

[0175] The first organic phase and the washing reagent (0.05 mol / L sulfuric acid aqueous solution) are mixed at a volume ratio of 10:1, and ten-stage countercurrent washing is carried out at 20°C and 450 rpm, and the total washing time is 5h. After phase separation, a second solution and a second organic phase are obtained.

[0176] S4: Stripping.

[0177] The second organic phase and the stripping agent (2 mol / L oxalic acid aqueous solution) are mixed at a volume ratio of 5:1, and ten-stage countercurrent stripping is carried out at 20°C and 450 rpm, and the total stripping time is 5h. After phase separation, a lithium oxalate solution and a third organic phase are obtained.

[0178] S5: Regeneration.

[0179] The third organic phase is regenerated by sodium hydroxide.

[0180] Example 7

[0181] The embodiment provides a method for recovering lithium from lithium-containing wastewater after recovering nickel, cobalt and manganese from ternary battery powder, and the method comprises the following steps:

[0182] S1: Adjusting the pH value of the lithium-containing solution.

[0183] The pH value of the lithium-containing solution is adjusted to 13 by using a sodium hydroxide solution, wherein the concentration of hydroxide ions in the lithium-containing solution after pH adjustment is 3 times the concentration of lithium.

[0184] S2: Extraction.

[0185] The lithium-containing wastewater after pH adjustment in S1 is extracted by using an organic extraction reagent, wherein the organic extraction reagent is obtained by mixing an extractant (obtained by mixing tridecyl phosphine oxide and Metrax 54 at a mass ratio of 3:1) and sulfonated kerosene at a volume ratio of 60:40.

[0186] Specifically, the organic extraction reagent and the lithium-containing wastewater after pH adjustment are mixed at a volume ratio of 1:5, and two-stage countercurrent extraction is carried out at 70°C and 150 rpm, and the total extraction time is 0.05h. After phase separation, a first solution and a first organic phase are obtained.

[0187] S3: Washing.

[0188] The first organic phase was mixed with a washing reagent (pure water) in a volume ratio of 10:1 and subjected to two-stage countercurrent washing at 70°C and 150 rpm for a total washing time of 0.05 h. After phase separation, a second solution and a second organic phase were obtained.

[0189] S4: stripping.

[0190] The second organic phase was mixed with a stripping reagent (oxalic acid aqueous solution with a concentration of 2 mol / L) in a volume ratio of 5:1 and subjected to two-stage countercurrent stripping at 70°C and 150 rpm for a total stripping time of 0.05 h. After phase separation, a lithium oxalate solution and a third organic phase were obtained.

[0191] S5: regeneration.

[0192] The third organic phase was regenerated using sodium carbonate.

[0193] Comparative Example 1

[0194] The difference between this comparative example and Example 1 is that the extractant is only TRPO.

[0195] Comparative Example 2

[0196] The difference between this comparative example and Example 1 is that the extractant is only LIX 54.

[0197] Comparative Example 3

[0198] The difference between this comparative example and Example 1 is that the ketone extractant in the extractant is 1,1,1-trifluoro-5,5-dimethyl-2,4-hexanedione.

[0199] Comparative Example 4

[0200] The difference between this comparative example and Example 1 is that the ketone extractant in the extractant is benzoyl trifluoropropionone.

[0201] Comparative Example 5

[0202] The difference between this comparative example and Example 1 is that the phosphine extractant in the extractant is dibutyl butylphosphonate.

[0203] Comparative Example 6

[0204] The difference between this comparative example and Example 1 is that the mass ratio of the phosphine extractant to the ketone extractant in the extractant is 0.5:9.5.

[0205] Comparative Example 7

[0206] The difference between this comparative example and Example 1 is that the mass ratio of the phosphine extractant to the ketone extractant in the extractant is 9.5:0.5.

[0207] Comparative Example 8

[0208] The difference between the present comparative example and Example 1 is that the volume percentage of the extractant contained in the organic extraction reagent is 5%.

[0209] Comparative Example 9

[0210] The difference between the present comparative example and Example 1 is that the volume percentage of the extractant contained in the organic extraction reagent is 70%.

[0211] Comparative Example 10

[0212] The difference between the present comparative example and Example 1 is that the volume ratio of the organic extraction reagent to the lithium-containing wastewater is 8:1.

[0213] Comparative Example 11

[0214] The difference between the present comparative example and Example 1 is that the lithium-containing wastewater is not subjected to pH adjustment, and the lithium-containing wastewater with pH of 5-6 is directly extracted.

[0215] Comparative Example 12

[0216] The difference between the present comparative example and Example 1 is that the extraction temperature is 75°C.

[0217] Comparative Example 13

[0218] The difference between the present comparative example and Example 1 is that the extraction system is replaced by TBP (tributyl phosphate) + FeCl3 system, and specifically, the mass ratio of TBP (tributyl phosphate) to FeCl3 is 1:1.5.

[0219] Test Example

[0220] The lithium ion and sodium ion contents in the lithium-containing solution after pH adjustment in the methods provided in Examples 1-7 and Comparative Examples 1-13 (the lithium ion and sodium ion contents in the initial lithium-containing wastewater in Comparative Example 11), the lithium ion and sodium ion contents in the first organic phase and the first solution obtained after extraction, and the lithium-containing solution (i.e. stripping solution) obtained after stripping are compared, and the results are shown in Table 1.

[0221] Table 1 Test Results

[0222]

[0223]

[0224] As can be seen from Table 1, the method provided in the present application can have high selectivity and high extraction rate for lithium ions in the lithium-containing wastewater, and the oil content in the first solution is low.

[0225] In the embodiment 6, the volume ratio of the organic phase to the aqueous phase is 5:1, which is the limit value, so that even if all the lithium of 0.7 g / L is transferred from the aqueous phase to the organic phase, the volume of the organic phase is five times that of the aqueous phase, and the concentration of all the lithium is diluted five times, becoming 0.14 g / L.

[0226] The diketone used in the comparative example 2 has a relatively strong hydrophilicity, and although it is an effective component for extracting lithium, it is lost with the aqueous phase, that is, it can extract lithium ions, but the oil content in the first solution is too high, and the application scenario is not realistic.

[0227] The extractant used in the comparative example 3 has a smaller molecular weight than the extractant used in the comparative example 2, and the loss with the aqueous phase is more serious, so the application scenario is not realistic.

[0228] As can be seen from the comparison between the other comparative examples and the embodiment 1, when the extractant or the extraction conditions are changed, the selectivity and the extraction rate of lithium ions are both reduced.

[0229] In summary, the method provided by the application has at least the following characteristics:

[0230] (1) The application uses a carbonate solution or a hydroxide solution to adjust the pH value of the lithium-containing solution, thereby achieving low-cost and efficient adjustment of the acidity of the lithium-containing wastewater.

[0231] (2) The application uses a specific organic extractant, which can have high selectivity and high extraction rate for lithium ions in the lithium-containing wastewater under neutral or weakly alkaline conditions without adding ferric chloride as a co-extractant. Moreover, the extractant used in the entire process can be recycled multiple times, and the extraction operation is simple.

[0232] (3) The application uses an aqueous organic acid solution as a stripping agent, which greatly reduces the corrosion of the equipment during the stripping process, is conducive to prolonging the service life of the equipment, improving safety and economic benefits. Moreover, the lithium organic acid obtained by stripping using the aqueous organic acid solution can be directly used as an electrolyte for lithium ion batteries, which is conducive to reducing the complexity of the components of the entire extraction system.

[0233] The above is only a preferred embodiment of the application and is not used to limit the application. For those skilled in the art, the application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the application shall be included in the protection scope of the application.

Claims

1. A method for extracting and recovering lithium from lithium-containing wastewater, characterized in that, Includes the following steps: First, the pH value of the lithium-containing wastewater is adjusted to neutral or alkaline. Then, the neutral or alkaline lithium-containing wastewater is extracted with an organic extraction reagent. After phase separation, the first organic phase loaded with lithium is obtained. The first organic phase was washed and separated to obtain the second organic phase; The second organic phase was back-extracted with a back-extracting agent, and after phase separation, a lithium-containing solution and a third organic phase were obtained; The organic extraction reagent contains extractants including phosphine extractants and ketone extractants; The phosphine extractant includes at least one of trioctylphosphine oxide, trihexylphosphine oxide, trinonylphosphine oxide, and tridecylphosphine oxide; The ketone extractant comprises at least one of alkylphenyl-methyl-β-dione and alkylphenyl-ethyl-β-dione; wherein the alkylphenyl-methyl-β-dione comprises at least one of dodecylphenyl-methyl-β-dione and tetradecylphenyl-methyl-β-dione; and the alkylphenyl-ethyl-β-dione comprises at least one of dodecylphenyl-ethyl-β-dione, tetradecylphenyl-ethyl-β-dione, and decylphenyl-ethyl-β-dione. The mass ratio of the phosphine extractant to the ketone extractant is 1:9 to 9:1; the volume ratio of the organic extractant to the lithium-containing wastewater is 5:1 to 1:5; the volume percentage of the extractant in the organic extractant is 10% to 60%; and the extraction temperature is 20°C to 70°C. The stripping agent used in the stripping process is an aqueous solution of an organic acid.

2. The method according to claim 1, characterized in that, The phosphine extractant includes at least one of Cyanex 923 and TRPO; And / or, the ketone extractant includes at least one of LIX 54, LIX 54-100, Metrax 54 and Metrax 54-100.

3. The method according to claim 1 or 2, characterized in that, The mass ratio of the phosphine extractant to the ketone extractant is (1~3):(1~3).

4. The method according to claim 1 or 2, characterized in that, The organic extraction reagent also includes a diluent.

5. The method according to claim 4, characterized in that, The diluent includes sulfonated kerosene.

6. The method according to claim 1 or 2, characterized in that, The extraction includes at least one of the following characteristics: Feature 1: The extraction time is 0.05h~5h; Feature 2: The extraction stages are 1 to 10 stages; Feature 3: The extraction is carried out at a rotation speed of 150 rpm to 450 rpm.

7. The method according to claim 1 or 2, characterized in that, The pH of the lithium-containing wastewater was adjusted using an alkaline solution.

8. The method according to claim 7, characterized in that, The alkaline solution includes a carbonate solution or a hydroxide solution.

9. The method according to claim 8, characterized in that, In lithium-containing wastewater where the pH value is adjusted using carbonate solution, the concentration of carbonate ions is 0.5 to 1.5 times the concentration of lithium; or, in lithium-containing wastewater where the pH value is adjusted using hydroxide solution, the concentration of hydroxide ions is 1 to 3 times the concentration of lithium.

10. The method according to claim 1 or 2, characterized in that, The washing process includes at least one of the following features: Feature 4: The washing reagent used in the washing process includes at least one of water, a lithium salt solution, and an acid; Feature 5: The volume ratio of the first organic phase to the washing reagent is 20:1 to 1:5; Feature 6: The washing temperature is 20℃~70℃; Feature 7: The washing time is 0.05h to 5h; feature 8: The washing process is of grade 1 to grade 10; Feature 9: The washing is performed at a speed of 150 rpm to 450 rpm.

11. The method according to claim 10, characterized in that, The lithium salt concentration of the lithium salt solution is greater than 0 mol / L and does not exceed 1 mol / L, or the concentration of the acid is greater than 0 mol / L and does not exceed 1 mol / L.

12. The method according to claim 1 or 2, characterized in that, The back-extraction includes at least one of the following features: Feature 10: The concentration of the organic acid aqueous solution is 0.1 mol / L to 6 mol / L; Feature 11: The volume ratio of the second organic phase to the stripping agent is 20:1 to 1:5; Feature 12: The back-extraction temperature is 20℃~70℃; Feature 13: The back-extraction time is 0.05h to 5h; Feature 14: The number of back-extraction stages is 1 to 10; Feature 15: The back-extraction is carried out at a rotation speed of 150 rpm to 450 rpm.

13. The method according to claim 1 or 2, characterized in that, Also includes: The third organic phase is regenerated.

14. The method according to claim 13, characterized in that, The regeneration reagent used in the regeneration includes at least one of water, inorganic salts, and alkali.

15. The method according to claim 14, characterized in that, The inorganic salts include carbonates.

16. The method according to claim 15, characterized in that, The inorganic salt includes at least one of sodium carbonate and potassium carbonate.

17. The method according to claim 14, characterized in that, The alkali includes at least one of sodium hydroxide and potassium hydroxide.

18. The method according to claim 1 or 2, characterized in that, The lithium-containing wastewater includes lithium-containing wastewater generated during the recycling of ternary battery powder.

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