Method for extracting high-purity metal salt from waste battery material

Abstract

The invention discloses a method for extracting high-purity metal salt from a waste battery material, and relates to a recovery and regeneration technology of a battery material. The method is especially suitable for regeneration extraction of battery materials such as lithium carbonate and nickel sulfate. According to the method, a multi-stage precise purification process is adopted, and the method comprises the steps of primary coarse precipitation, secondary purification, solvent extraction and refining, ion exchange, refining and crystallization, detection control and the like, so that high recovery rate and ultralow impurity control are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the recycling and regeneration technology of battery materials, and in particular to a method for extracting high-purity metal salt from waste battery materials. BACKGROUND

[0002] With the rapid development of new energy vehicles, energy storage systems and consumer electronics, the demand for lithium-ion batteries continues to rise, and the number of waste batteries also shows explosive growth. According to statistics, the theoretical recovery amount of power batteries in China in 2022 has reached 750,000 tons, and the actual recovery amount is about 300,000 tons. It is estimated that by 2027, the market size will grow to 55 billion RMB.

[0003] Waste batteries contain a large amount of high-value metals such as lithium, cobalt, nickel, and manganese. The recovery of these metals not only has significant economic value, but also helps to alleviate resource shortages and environmental pollution problems. Currently, the recycling technology of waste batteries mainly includes three ways: hydrometallurgy, pyrometallurgy and direct recovery.

[0004] Hydrometallurgy has become the mainstream technology due to its high metal recovery rate and high product purity. This method dissolves the metal through chemical means such as acid leaching, and then separates and purifies it through processes such as precipitation, extraction, and ion exchange. However, hydrometallurgy has the problems of complex process, long process, and difficult wastewater treatment.

[0005] Pyrometallurgy reduces the metal through high-temperature smelting, and the process flow is relatively simple, but it has high energy consumption, high pollution, and relatively low metal recovery rate. Direct recovery technology attempts to directly reuse the electrode material without damaging the structure of the battery material, and has the advantages of low energy consumption and environmental friendliness, but it still faces technical difficulties and has not been widely applied.

[0006] In the actual recovery process, impurities such as iron, aluminum, calcium, magnesium and other metal ions in waste batteries are often difficult to completely remove, affecting the electrochemical performance of the regenerated material. Especially in the preparation of high-performance battery materials, the requirement for impurity content is extremely high, usually below 10-50 ppm. The existing purification methods, such as simple precipitation or ion exchange, are difficult to simultaneously meet the requirements of high recovery rate and ultra-low impurity content.

[0007] Therefore, developing a multi-stage precision purification process to achieve high-purity extraction and control impurities below 30 ppm has become a key problem to be solved in the current battery material recycling field. SUMMARY

[0008] In order to solve the technical problems involved in the background art, the present application provides a method for extracting high-purity metal salt from waste battery materials.

[0009] Specific schemes are as follows:

[0010] A method for extracting high-purity metal salt from waste battery material, characterized in that it comprises the following steps:

[0011] a) primary rough precipitation:

[0012] The waste battery material is subjected to acid leaching to obtain a leaching solution containing metal ions; 1.5-3.0 parts by mass of sodium hydroxide solution or lime milk is added to every 100 parts by mass of the leaching solution, the pH is adjusted to 4.0-5.5, and Ca 2+ , Mg 2+ metal ions are precipitated and removed; a mixed solution of citric acid-tartaric acid with a volume ratio of 1:1 is added to adjust the pH to 3.0-4.0, 0.5-1.5 parts by mass of an auxiliary agent is added, and the reaction is carried out at 40-60°C for 2-3 hours, after which the pH is adjusted to 2.0-2.5 to separate Fe 3+ , Li+;

[0013] b) secondary purification:

[0014] 0.5-1.0 parts by mass of a precipitant is added to the clarified solution, and complex precipitation is carried out to remove residual Fe, Al trace impurities; the reaction temperature is 25-35°C, and the reaction time is 30-60 minutes;

[0015] c) solvent extraction refining:

[0016] The above-mentioned clear solution is placed in a multistage solvent extraction tower, 1.0-2.0 parts by mass of an organic extractant is used for mild extraction, and trace impurities are separated; the extraction temperature is 20-30°C, and the extraction time is 10-20 minutes;

[0017] d) ion exchange:

[0018] The extracted solution passes through an ion exchange resin bed, the flow rate is controlled at 1.0-2.0 BV / h, and the resin bed height is 50-100 cm;

[0019] e) refining and crystallization:

[0020] The above-processed solution is concentrated to 1 / 2-1 / 3 of the original volume, cooled to 5-15°C, and high-purity metal sulfate or chloride crystals are precipitated; the mother liquor is discarded, and residual impurities are removed;

[0021] f) detection and control:

[0022] Ion chromatography or spectral analysis is performed on the finished product to monitor the content of main impurities, and ensure that the content of Fe, Al, and Ca impurities is reduced to below 30 ppm; if it exceeds the standard, part of the processing steps can be repeated until the standard is met.

[0023] Preferably, the acid used in the acid leaching step in step a) is sulfuric acid or hydrochloric acid, with a concentration of 1.0-2.0 mol / L, a leaching temperature of 60-80°C, and a leaching time of 2-4 hours.

[0024] Preferably, the preparation method of the auxiliary agent in step a) is as follows:

[0025] 10-15 parts by mass of allyl mercaptan, 11-16 parts by mass of maleic anhydride, and 17-29 parts by mass of pentaerythritol tetra(3-mercaptopropionate), 3-5 parts by mass of potassium ethoxide are dissolved in 200-260 parts by mass of a mixed solvent of dimethyl sulfoxide and N,N-dimethylformamide in a volume ratio of 1:1, and stirred at 60-90°C for 5-8 hours. After the reaction is completed, the solvent is removed by reduced pressure distillation at a pressure of ≤10 mmHg and a temperature of 60-80°C to obtain the auxiliary agent.

[0026] Preferably, the precipitant in step b) is ethylenediaminetetraacetic acid (EDTA) or oxalic acid.

[0027] Preferably, the organic extractant in step c) is Cyanex 301, Cyanex 302, Cyanex 272, or bis(2-ethylhexyl)phosphoric acid.

[0028] Preferably, the ion exchange resin in step d) is a mixed bed of strong acid cation exchange resin and strong base anion exchange resin, with a volume ratio of 30-40:60-70.

[0029] Preferably, the strong acid cation exchange resin is one of Purolite C100, ResinTech CG8, Dowex HCR-S / S, and Amberlite IR120.

[0030] Preferably, the strong base anion exchange resin is one of Purolite A400, ResinTech SBG1, Dowex 1X8, and Amberlite IRA-400.

[0031] Preferably, the cooling rate in step e) is 1-2°C / h, and the crystal aging time is 12-24 hours.

[0032] The method is suitable for treating different types of waste battery materials, including lithium iron phosphate, ternary materials, and lithium cobaltate materials.

[0033] Reaction mechanism

[0034] Multi-michael addition reaction: the multi-thiol group of pentaerythritol tetra(3-mercaptopropionate) undergoes nucleophilic addition to the double bond of maleic anhydride to form a branched molecule containing thioester, and the density of its thiol functional group is increased by 25% compared with the monothiol system, and multiple coordination active sites are constructed.

[0035] Chelation synergistic leaching mechanism: the carboxyl group of the branched molecule forms ionic bonding with Li+, and the thioether group forms coordination bonding with Fe 3+ to form an octahedral coordination to generate a stable [Fe(SR)(COO)3]- complex ion, break the FePO4 lattice structure, and realize synchronous leaching of iron and lithium.

[0036] Technical effects

[0037] Ultra-high purity: the main impurities in the final product are controlled within 30 ppm, meeting the requirements of cutting-edge battery materials.

[0038] Efficient use of resources: solid impurities in the refining step can be reused, and the overall metal recovery rate is high.

[0039] Strong adaptability: this method is suitable for different types of battery raw materials, and only the precipitation and extraction conditions need to be adjusted.

[0040] Green and clean: most chemicals can be recycled and reused, waste liquid is neutralized and decompressed, and is non-toxic. DETAILED DESCRIPTION

[0041] In order to enable those skilled in the art to better understand the technical solutions of the present application, the present application will be further described in detail below in combination with specific embodiments.

[0042] Example 1

[0043] a) Primary coarse precipitation:

[0044] The waste battery material is subjected to acid leaching, using sulfuric acid with a concentration of 1.0 mol / L, leaching temperature of 60°C, and leaching time of 2 hours to obtain a leaching solution containing metal ions; 1.5 g of sodium hydroxide solution is added to every 100 g of leaching solution, and the pH is adjusted to 4.0 to precipitate and remove Ca 2+ , Mg 2+ metal ions; a mixed solution of citric acid-tartaric acid with a volume ratio of 1:1 is added to adjust the pH to 3.0, 0.5 g of auxiliary agent is added, and the reaction is carried out at 40°C for 2 hours. After filtration, the pH is adjusted to 2.0 to separate Fe 3+ , Li+;

[0045] Auxiliary agent preparation method:

[0046] 10 g of allyl mercaptan, 11 g of maleic anhydride and 17 g of pentaerythritol tetra(3-mercaptopropionate), 3 g of potassium ethoxide are dissolved in 200 g of a mixture of dimethyl sulfoxide and N,N-dimethylformamide in a volume ratio of 1:1, and stirred at 60°C for 5 hours. After the reaction is completed, the solvent is removed by distillation under reduced pressure, with a pressure of ≤10 mmHg and a temperature of 60°C, to obtain the additive.

[0047] b) Secondary purification:

[0048] 0.5 g of precipitant ethylenediaminetetraacetic acid (EDTA) is added to the clear solution to complex and precipitate residual Fe, Al trace impurities; the reaction temperature is 25°C and the reaction time is 30 minutes;

[0049] c) Solvent extraction refining:

[0050] The supernatant obtained above is placed in a multi-stage solvent extraction tower, 1.0 g of organic extractant Cyanex 301 is used for light extraction, and trace impurities are separated; the extraction temperature is 20°C and the extraction time is 10 minutes;

[0051] d) Ion exchange:

[0052] The extracted solution passes through an ion exchange resin bed at a flow rate of 1.0 BV / h, and the height of the resin bed is 50 cm; the ion exchange resin is a mixed bed of strong acid cation exchange resin Purolite C100 and strong base anion exchange resin Purolite A400, with a volume ratio of 30:70;

[0053] e) Refining and crystallization:

[0054] The above treated solution is concentrated to 1 / 2 of the original volume, cooled to 5°C at a cooling rate of 1°C / h, and high-purity metal sulfate crystals are precipitated, with a crystal aging time of 12 hours; the mother liquor is discarded, taking away the residual impurities;

[0055] f) Detection control:

[0056] Ion chromatography is performed on the finished product to monitor the content of main impurities, ensuring that the content of Fe, Al and Ca impurities is reduced to below 30 ppm; if it exceeds the standard, part of the processing steps can be repeated until the standard is met.

[0057] Example 2

[0058] a) Primary rough precipitation:

[0059] The waste battery material is subjected to acid leaching using hydrochloric acid with a concentration of 1.3 mol / L, a leaching temperature of 65°C and a leaching time of 2.5 hours to obtain a leaching solution containing metal ions; 2.0 g of lime milk is added to every 100 g of the leaching solution to adjust the pH to 4.5, and Ca is precipitated and removed2+ Mg 2+ Metal ions; add a mixed solution of citric acid-tartaric acid with a volume ratio of 1:1 to adjust the pH to 3.3, add 0.8g of the auxiliary agent, react at 45℃ for 2.2 hours, adjust the pH to 2.2 after filtration to separate Fe 3+ Li+;

[0060] Auxiliary agent preparation method:

[0061] Dissolve 12g of allyl mercaptan, 13g of maleic anhydride, and 21g of pentaerythritol tetra(3-mercaptopropionate) in 220g of a mixed solvent of dimethyl sulfoxide and N,N-dimethylformamide with a volume ratio of 1:1, add 3.5g of potassium ethoxide, stir at 70℃ for 6 hours, and then remove the solvent by reduced pressure distillation with a pressure of ≤10mmHg and a temperature of 65℃. The auxiliary agent is obtained.

[0062] b) Secondary purification:

[0063] Add 0.6g of the precipitant oxalic acid to the clear solution, complex and precipitate to remove residual Fe, Al trace impurities; the reaction temperature is 28℃, and the reaction time is 35 minutes;

[0064] c) Solvent extraction refining:

[0065] Put the above obtained clear solution into a multi-stage solvent extraction tower, use 1.3g of the organic extractant Cyanex302 for light extraction, and separate trace impurities; the extraction temperature is 23℃, and the extraction time is 13 minutes;

[0066] d) Ion exchange:

[0067] Pass the extracted solution through an ion exchange resin bed with a flow rate controlled at 1.3BV / h and a resin bed height of 65cm; the ion exchange resin is a mixed bed of strong acid cation exchange resin ResinTech CG8 and strong base anion exchange resin ResinTech SBG1 with a volume ratio of 33:67;

[0068] e) Refining and crystallization:

[0069] Concentrate the above treated solution to 5 / 12 of the original volume, cool to 8℃ at a cooling rate of 1.2℃ / h, and precipitate high-purity chloride crystals, with a crystal aging time of 15 hours; discard the mother liquor to remove residual impurities;

[0070] f) Detection control:

[0071] Perform ion chromatography on the finished product to monitor the content of main impurities, and ensure that the Fe, Al, and Ca impurity contents are reduced to below 30ppm; if the standard is exceeded, repeat part of the processing steps until the standard is met.

[0072] Example 3

[0073] a) Primary rough precipitation:

[0074] The waste battery material is subjected to acid leaching using sulfuric acid with a concentration of 1.7 mol / L, leaching temperature of 75°C, and leaching time of 3.5 hours to obtain a leaching solution containing metal ions; 2.5 g of sodium hydroxide solution is added to every 100 g of the leaching solution, and the pH is adjusted to 5.0 to precipitate and remove Ca 2+ , Mg 2+ metal ions; a mixed solution of citric acid-tartaric acid with a volume ratio of 1:1 is added to adjust the pH to 3.7, 1.2 g of an auxiliary agent is added, and the reaction is carried out at 55°C for 2.8 hours; after filtration, the pH is adjusted to 2.4 to separate Fe 3 + , Li+;

[0075] Auxiliary agent preparation method:

[0076] 14 g of allyl mercaptan, 15 g of maleic anhydride, and 26 g of pentaerythritol tetra(3-mercaptopropionate) are dissolved in 250 g of a mixed solvent of dimethyl sulfoxide and N,N-dimethylformamide with a volume ratio of 1:1, 4.5 g of potassium ethoxide is added, and the reaction is carried out at 85°C for 7 hours; after the reaction is completed, the solvent is removed by reduced pressure distillation with a pressure ≤10 mmHg and a temperature of 75°C to obtain the auxiliary agent.

[0077] b) Secondary purification:

[0078] 0.8 g of the precipitant ethylenediaminetetraacetic acid (EDTA) is added to the clear solution to complex and precipitate residual Fe, Al trace impurities; the reaction temperature is 32°C, and the reaction time is 50 minutes;

[0079] c) Solvent extraction refining:

[0080] The clear solution obtained above is placed in a multi-stage solvent extraction tower, 1.7 g of the organic extractant bis(2-ethylhexyl) phosphoric acid is used for mild extraction, and trace impurities are separated; the extraction temperature is 28°C, and the extraction time is 17 minutes;

[0081] d) Ion exchange:

[0082] The extracted solution passes through an ion exchange resin bed with a flow rate controlled at 1.7 BV / h, and the resin bed height is 85 cm; the ion exchange resin is a mixed bed of strong acid cation exchange resin Dowex HCR-S / S and strong base anion exchange resin Dowex 1X8 with a volume ratio of 37:63;

[0083] e) Refining and crystallization:

[0084] The treated solution is concentrated to 1 / 3 of the original volume, cooled to 12°C at a cooling rate of 1.8°C / h, and high-purity metal sulfate is precipitated, with a crystal aging time of 20 hours; the mother liquor is discarded, and residual impurities are removed;

[0085] f) Detection control:

[0086] The finished product is subjected to ion chromatography to monitor the content of main impurities, and the content of Fe, Al, and Ca impurities is ensured to be reduced to below 30 ppm; if the content exceeds the standard, the partial processing steps can be repeated until the standard is met.

[0087] Example 4

[0088] a) Primary coarse precipitation:

[0089] The waste battery material is subjected to acid leaching using hydrochloric acid with a concentration of 2.0 mol / L, leaching temperature of 80°C, and leaching time of 4 hours to obtain a leaching solution containing metal ions; 3.0 g of lime milk is added to every 100 g of the leaching solution, and the pH is adjusted to 5.5 to precipitate and remove Ca 2+ , Mg 2+ metal ions; a mixed solution of citric acid-tartaric acid with a volume ratio of 1:1 is added to adjust the pH to 4.0, 1.5 g of an additive is added, and the reaction is carried out at 60°C for 3 hours; after filtration, the pH is adjusted to 2.5 to separate Fe 3+ , Li+.

[0090] Additive preparation method:

[0091] 15 g of allyl mercaptan, 16 g of maleic anhydride, and 29 g of pentaerythritol tetra(3-mercaptopropionate) are dissolved in 260 g of a mixed solvent of dimethyl sulfoxide and N,N-dimethylformamide with a volume ratio of 1:1, and 5 g of potassium ethoxide is added; the reaction is carried out at 90°C for 8 hours under stirring; after the reaction is completed, the solvent is removed by reduced pressure distillation at a pressure of ≤10 mmHg and a temperature of 80°C to obtain the additive.

[0092] b) Secondary purification:

[0093] In the clarified solution, 1.0 g of a precipitant oxalic acid is added to complex and precipitate residual Fe, Al trace impurities; the reaction temperature is 35°C, and the reaction time is 60 minutes;

[0094] c) Solvent extraction refining:

[0095] The above-obtained clear solution is placed in a multi-stage solvent extraction tower, and 2.0 g of an organic extractant Cyanex272 is used for light extraction to separate trace impurities; the extraction temperature is 30°C, and the extraction time is 20 minutes;

[0096] d) Ion exchange:

[0097] The extracted solution is passed through an ion exchange resin bed at a flow rate of 2.0 BV / h, and the height of the resin bed is 100 cm; the ion exchange resin is a mixed bed of strong acid cation exchange resin Amberlite IR120 and strong base anion exchange resin Amberlite IRA-400, with a volume ratio of 40:60;

[0098] e) purification and crystallization:

[0099] The above treated solution is concentrated to 1 / 3 of the original volume, cooled to 15°C at a cooling rate of 2°C / h, and high-purity chloride crystals are precipitated, with a crystal aging time of 24 hours; the mother liquor is discarded, and the residual impurities are removed;

[0100] f) detection control:

[0101] The finished product is subjected to ion chromatography to monitor the content of main impurities, ensuring that the content of Fe, Al, and Ca impurities is reduced to below 30 ppm; if the content exceeds the standard, the partial treatment steps can be repeated until the standard is met.

[0102] Comparative Example 1

[0103] a) primary coarse precipitation:

[0104] The waste battery material is subjected to acid leaching using sulfuric acid at a concentration of 1.0 mol / L, with a leaching temperature of 60°C and a leaching time of 2 hours, to obtain a leaching solution containing metal ions; 1.5 g of sodium hydroxide solution is added to every 100 g of leaching solution to adjust the pH to 4.0, and Ca 2+ , Mg 2+ metal ions are precipitated and removed; a mixed solution of citric acid-tartaric acid is added at a volume ratio of 1:1 to adjust the pH to 3.0, and the reaction is carried out at 40°C for 2 hours; after filtration, the pH is adjusted to 2.0 to separate Fe 3+ , Li+;

[0105] b) secondary purification:

[0106] 0.5 g of precipitant ethylenediaminetetraacetic acid (EDTA) is added to the clarified solution to complex and precipitate residual Fe, Al trace impurities; the reaction temperature is 25°C, and the reaction time is 30 minutes;

[0107] c) solvent extraction purification:

[0108] The above obtained clear solution is placed in a multi-stage solvent extraction tower, and 1.0 g of organic extractant Cyanex301 is used for light extraction to separate trace impurities; the extraction temperature is 20°C, and the extraction time is 10 minutes;

[0109] d) ion exchange:

[0110] The extracted solution is passed through an ion exchange resin bed at a flow rate of 1.0 BV / h, and the height of the resin bed is 50 cm; the ion exchange resin is a mixed bed of strong acid cation exchange resin Purolite C100 and strong base anion exchange resin Purolite A400, with a volume ratio of 30:70;

[0111] e) purification and crystallization:

[0112] The above-processed solution is concentrated to 1 / 2 of the original volume, cooled to 5°C at a cooling rate of 1°C / h, and high-purity metal sulfate crystals are precipitated, with a crystal aging time of 12 hours; the mother liquor is discarded, and residual impurities are removed;

[0113] f) detection control:

[0114] Ion chromatography is performed on the finished product to monitor the content of main impurities, ensuring that the content of Fe, Al, and Ca impurities is reduced to below 30 ppm; if the content exceeds the standard, the partial processing steps can be repeated until the standard is met.

[0115] Comparative Example 2

[0116] a) primary coarse precipitation:

[0117] The waste battery material is subjected to acid leaching using sulfuric acid at a concentration of 1.0 mol / L, a leaching temperature of 60°C, and a leaching time of 2 hours to obtain a leaching solution containing metal ions; 1.5 g of sodium hydroxide solution is added to every 100 g of the leaching solution to adjust the pH to 4.0, and Ca 2+ , Mg 2+ metal ions are precipitated and removed; a mixed solution of citric acid-tartaric acid is added at a volume ratio of 1:1 to adjust the pH to 3.0, 0.5 g of an additive is added, and the reaction is carried out at 40°C for 2 hours; after filtration, the pH is adjusted to 2.0 to separate Fe 3+ , Li+;

[0118] Preparation method of the additive:

[0119] 11 g of maleic anhydride, 17 g of pentaerythritol tetra(3-mercaptopropionate), and 3 g of potassium ethoxide are dissolved in 200 g of a mixed solvent of dimethyl sulfoxide and N,N-dimethylformamide at a volume ratio of 1:1, and the reaction is carried out at 60°C for 5 hours under stirring; after the reaction is completed, the solvent is removed by reduced pressure distillation at a pressure of ≤10 mmHg and a temperature of 60°C to obtain the additive.

[0120] b) secondary purification:

[0121] 0.5 g of a precipitant, ethylenediaminetetraacetic acid (EDTA), is added to the clarified solution to complex and precipitate residual Fe and Al trace impurities; the reaction temperature is 25°C, and the reaction time is 30 minutes;

[0122] c) solvent extraction refining:

[0123] The supernatant obtained above was placed in a multi-stage solvent extraction tower, and 1.0 g of organic extractant Cyanex 301 was used for mild extraction to separate trace impurities; the extraction temperature was 20°C, and the extraction time was 10 minutes;

[0124] d) ion exchange:

[0125] The extracted solution was passed through an ion exchange resin bed at a flow rate of 1.0 BV / h, and the resin bed height was 50 cm; the ion exchange resin was a mixed bed of strong acid cation exchange resin Purolite C100 and strong base anion exchange resin Purolite A400, with a volume ratio of 30:70;

[0126] e) refining and crystallization:

[0127] The solution treated above was concentrated to 1 / 2 of the original volume, cooled to 5°C at a cooling rate of 1°C / h, and high-purity metal sulfate crystals were precipitated, with a crystal aging time of 12 hours; the mother liquor was discarded, and residual impurities were removed;

[0128] f) detection control:

[0129] Ion chromatography was performed on the finished product to monitor the content of main impurities, ensuring that the Fe, Al, and Ca impurity contents were reduced to below 30 ppm; if the standard was exceeded, part of the processing steps could be repeated until the standard was met.

[0130] Comparative Example 3

[0131] a) primary coarse precipitation:

[0132] The waste battery material was subjected to acid leaching using sulfuric acid at a concentration of 1.0 mol / L, with a leaching temperature of 60°C and a leaching time of 2 hours to obtain a leaching solution containing metal ions; 1.5 g of sodium hydroxide solution was added to every 100 g of leaching solution to adjust the pH to 4.0, and Ca 2+ , Mg 2+ metal ions were precipitated and removed; a mixed solution of citric acid-tartaric acid was added to adjust the pH to 3.0, with a volume ratio of 1:1, and 0.5 g of an additive was added, and the reaction was carried out at 40°C for 2 hours; after filtration, the pH was adjusted to 2.0 to separate Fe 3+ , Li+;

[0133] Additive preparation method:

[0134] The 10 g allyl mercaptan, 11 g maleic anhydride, 3 g potassium ethoxide are dissolved in 200 g of a mixed solvent of dimethyl sulfoxide and N,N-dimethylformamide in a volume ratio of 1:1, and stirred at 60°C for 5 hours. After the reaction is completed, the solvent is removed by reduced pressure distillation at a pressure of ≤10 mmHg and a temperature of 60°C to obtain the adjuvant.

[0135] b) Secondary purification:

[0136] 0.5 g of the precipitant ethylenediaminetetraacetic acid (EDTA) is added to the clear solution to complex and precipitate the residual Fe and Al trace impurities. The reaction temperature is 25°C and the reaction time is 30 minutes.

[0137] c) Solvent extraction refining:

[0138] The supernatant obtained above is placed in a multi-stage solvent extraction tower, and 1.0 g of the organic extractant Cyanex 301 is used for mild extraction to separate trace impurities. The extraction temperature is 20°C and the extraction time is 10 minutes.

[0139] d) Ion exchange:

[0140] The extracted solution is passed through an ion exchange resin bed at a flow rate of 1.0 BV / h, and the height of the resin bed is 50 cm. The ion exchange resin is a mixed bed of strong acid cation exchange resin Purolite C100 and strong base anion exchange resin Purolite A400 with a volume ratio of 30:70.

[0141] e) Refining and crystallization:

[0142] The above treated solution is concentrated to 1 / 2 of the original volume, cooled to 5°C at a cooling rate of 1°C / h, and high-purity metal sulfate crystals are precipitated. The crystal aging time is 12 hours. The mother liquor is discarded, and the residual impurities are removed.

[0143] f) Detection control:

[0144] Ion chromatography is performed on the finished product to monitor the content of main impurities, ensuring that the content of Fe, Al, and Ca impurities is reduced to below 30 ppm. If the content exceeds the standard, some of the processing steps can be repeated until the standard is met.

[0145] Test indicators:

[0146] Metal recovery rate: calculated by determining the ratio of the metal content in the product to the metal content in the raw material.

[0147] Impurity content: the content of Fe, Al, Ca and other impurities in the product is analyzed by inductively coupled plasma mass spectrometry (ICP-MS).

[0148] Test results:

[0149] Table 1 recovery rate

[0150]

[0151]

[0152] Table 2 impurity content

[0153]

[0154] It can be seen from the above test results that the method has significant advantages in improving metal recovery rate and reducing impurity content, can meet the strict requirements of high-performance battery materials on impurity content, and has good application prospect.

[0155] It can be understood that the above embodiments are only exemplary embodiments adopted for illustrating the principles of the present application, and the present application is not limited thereto. Various modifications and improvements can be made by those skilled in the art without departing from the spirit and essence of the present application, and these modifications and improvements are also considered as the protection scope of the present application.

Claims

1. A method for extracting high-purity metal salts from waste battery materials, characterized in that, Includes the following steps: a) Primary coarse precipitate: Waste battery materials are acid-leached to obtain a leachate containing metal ions. 1.5–3.0 parts by weight of sodium hydroxide solution or lime slurry are added to every 100 parts by weight of the leachate to adjust the pH to 4.0–5.5, precipitating and removing Ca. 2+ Mg 2+ Metal ions; adjust the pH to 3.0–4.0 by adding a citric acid-tartaric acid mixture (1:1 volume ratio), add 0.5–1.5 parts by weight of an auxiliary agent, react at 40–60°C for 2–3 hours, filter, and adjust the pH to 2.0–2.5 to separate Fe. 3+ 、Li+; b) Secondary purification: Add 0.5–1.0 parts by weight of precipitant to the clear solution to complex and precipitate and remove residual Fe and trace Al impurities; the reaction temperature is 25–35℃ and the reaction time is 30–60 minutes. c) Solvent extraction purification: The clear liquid obtained above was placed into a multi-stage solvent extraction tower, and 1.0 to 2.0 parts by weight of organic extractant was used for light extraction to separate trace impurities; the extraction temperature was 20 to 30°C, and the extraction time was 10 to 20 minutes. d) Ion exchange: The extracted solution is passed through an ion exchange resin bed at a flow rate of 1.0–2.0 BV / h and a resin bed height of 50–100 cm. e) Refining and crystallization: The solution after the above treatment is concentrated to 1 / 2 to 1 / 3 of its original volume, cooled to 5 to 15°C, and high-purity metal sulfate or chloride crystals are precipitated; the mother liquor is discarded, and residual impurities are removed. f) Detection and control: Perform ion chromatography or spectral analysis on the finished product to monitor the content of major impurities and ensure that the content of Fe, Al, and Ca impurities is reduced to below 30 ppm; if the content exceeds the standard, some processing steps can be repeated until the standard is met.

2. The method for extracting high-purity metal salts from waste battery materials according to claim 1, characterized in that: The acid used in the acid leaching step in step a) is sulfuric acid or hydrochloric acid with a concentration of 1.0 to 2.0 mol / L, a leaching temperature of 60 to 80°C, and a leaching time of 2 to 4 hours.

3. The method for extracting high-purity metal salts from waste battery materials according to claim 1, characterized in that: The preparation method of the auxiliary agent in step a) is as follows: 10-15 parts by weight of allyl thiol, 11-16 parts by weight of maleic anhydride, 17-29 parts by weight of pentaerythritol tetra(3-mercaptopropionate), and 3-5 parts by weight of potassium ethoxide are dissolved in 200-260 parts by weight of a 1:1 mixture of dimethyl sulfoxide and N,N-dimethylformamide. The mixture is stirred and reacted at 60-90°C for 5-8 hours. After the reaction is completed, the solvent is removed by vacuum distillation at a pressure ≤10 mmHg and a temperature of 60-80°C to obtain the auxiliary agent.

4. The method for extracting high-purity metal salts from waste battery materials according to claim 1, characterized in that: In step b), the precipitant is ethylenediaminetetraacetic acid (EDTA) or oxalic acid.

5. The method for extracting high-purity metal salts from waste battery materials according to claim 1, characterized in that: In step c), the organic extractant is Cyanex 301, Cyanex 302, Cyanex 272, or bis(2-ethylhexyl)phosphoric acid.

6. The method for extracting high-purity metal salts from waste battery materials according to claim 1, characterized in that: The ion exchange resin in step d) is a mixed bed of strongly acidic cation exchange resin and strongly basic anion exchange resin, with a volume ratio of 30-40:60-70.

7. The method for extracting high-purity metal salts from waste battery materials according to claim 6, characterized in that: The strongly acidic cation exchange resin is one of Purolite C100, ResinTech CG8, Dowex HCR-S / S, and Amberlite IR120.

8. A method for extracting high-purity metal salts from waste battery materials according to claim 6, characterized in that: The strongly basic anion exchange resin is one of Purolite A400, ResinTech SBG1, Dowex 1X8, and Amberlite IRA-400.

9. The method for extracting high-purity metal salts from waste battery materials according to claim 1, characterized in that: In step e), the cooling rate is 1-2°C / h, and the crystal aging time is 12-24 hours.

10. The method for extracting high-purity metal salts from waste battery materials according to claim 1, characterized in that: The method is applicable to processing different types of waste battery materials, including lithium iron phosphate, ternary materials, and lithium cobalt oxide materials.

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