An efficient method for recovering valuable metals from waste lithium iron phosphate materials

Abstract

The present invention relates to the field of metal recovery technology, and in particular to a method for efficiently recovering valuable metals from waste lithium iron phosphate materials. The preparation process comprises the following steps: immersing waste lithium iron phosphate materials in a sulfuric acid solution, adding lithium ion adsorption crystal colloid to a lithium-containing recovery liquid, and continuously adding a saturated sodium carbonate solution to the lithium ion solution until no new precipitation is generated in the system, thereby obtaining lithium carbonate precipitation and completing lithium recovery. The present invention forms a rigid network of acrylamide through covalent crosslinking, then inserts acrylic acid therein, and forms an interpenetrating network structure through chemical bonds, so that the prepared polyacrylamide-polyacrylic acid double network crystal colloid has good mechanical properties and toughness, resists acid corrosion of sulfuric acid pickling solution, maintains its structure unchanged in an acid environment during the adsorption of lithium ions, and the network structure formed during the polymerization process can expose more adsorption sites, thereby improving the recovery rate of valuable metal lithium.

Description

Technical Field

[0001] The present invention relates to the technical field of metal recovery, and in particular to a method for efficiently recovering valuable metals in waste lithium iron phosphate materials. Background Art

[0002] Waste lithium iron phosphate materials usually refer to waste containing lithium positive electrode active substances generated during the production, use or recycling of lithium iron phosphate batteries. The positive electrode materials separated from retired lithium iron phosphate batteries after discharge, crushing and sorting will contain lithium iron phosphate, conductive agent, binder and aluminum foil fragments. After flotation, waste lithium iron phosphate materials recovered from retired batteries can be obtained.

[0003] In addition to lithium iron phosphate, waste lithium iron phosphate materials may also contain elements such as carbon, chromium, and manganese. The lithium ion content in lithium iron phosphate accounts for a relatively high proportion, and the recovery value of lithium is very high. The process of recovering lithium from waste lithium iron phosphate materials has also achieved certain results in development. Therefore, the main metal recovered from waste lithium iron phosphate materials is lithium. Lithium recovery is generally recovered by a reduction acid leaching-precipitation method, that is, the waste lithium iron phosphate material is first acid-leached to allow the lithium element to exist in the acid leaching solution in the form of ions, and then the lithium ions are precipitated as lithium carbonate by adding carbonate, thereby recovering the lithium ions. However, this method will precipitate other elements such as iron, chromium, and manganese while precipitating the lithium element. Therefore, it is necessary to selectively adsorb lithium ions. The present invention provides an efficient recovery method for valuable metals in waste lithium iron phosphate materials, which selectively adsorbs lithium ions by preparing a crystal gel that has selective adsorption of lithium ions, thereby improving the recovery of valuable metal lithium in waste lithium iron phosphate materials. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the object of the present invention is to provide a method for efficiently recovering valuable metals from waste lithium iron phosphate materials.

[0005] A method for efficiently recovering valuable metals from waste lithium iron phosphate materials comprises the following steps:

[0006] The waste lithium iron phosphate material disassembled from the battery is immersed in a sulfuric acid solution with a material-liquid ratio of 1g: (10-15)mL. The concentration of the sulfuric acid solution is 2-4mol / L. Then 3-5vol% H2O2 is added. The temperature is raised to 60-80℃ and the reaction is carried out for 3-4h. At the same time, it is stirred at a speed of 300-400r / min. The solid matter is then removed by filtration. NaOH solution is added to the filtrate to adjust the pH value to 6.5-7.5 to obtain a lithium-containing recovery liquid.

[0007] The lithium ion adsorbed crystal colloid is added to the lithium-containing recovery liquid at a solid-liquid ratio of 1 g: (5-8) mL, and the mixture is shaken at a constant temperature of 30-35°C and a speed of 120-150 r / min for 12-13 hours. The filtrate is then filtered to remove the adsorbed lithium ion crystal colloid, which is then placed in a 0.5-1 M HCl solution and shaken at a speed of 150-180 r / min at 30-35°C for 12-13 hours for desorption to obtain a lithium ion solution.

[0008] The lithium ion solution is heated to 55-60°C, and a saturated sodium carbonate solution is continuously added to the lithium ion solution while stirring at a speed of 50-60 r / min until no new precipitation is generated in the system, lithium carbonate precipitation is obtained, and lithium recovery is completed.

[0009] Furthermore, the preparation method of lithium ion adsorption crystal colloid comprises the following steps:

[0010] 0.5-1 parts by mass of polyacrylamide-polyacrylic acid double network crystal gel is added to 15-20 parts by mass of acetic acid aqueous solution, stirred at room temperature until it is completely dissolved, then 5-10 parts by mass of glutaraldehyde solution is added, stirred for 20-30 minutes, and then 50-75% by mass of lithium ion molecular sieve powder is added. Then, it is placed in a refrigerator at -4-0°C for 4-4.5 hours, then stirred in an ice water bath for 1-2 hours, then placed at room temperature and heated to 22-24°C, and washed twice with deionized water to obtain lithium ion adsorption crystal gel.

[0011] Furthermore, the preparation method of the polyacrylamide-polyacrylic acid double network cryogel comprises the following steps:

[0012] The polyacrylamide single network gel is completely immersed in an acrylic acid aqueous solution with a system mass percentage of 20-25wt%, and then 0.5-0.8wt% of polyethylene glycol diacrylate and 1-2wt% of 2-hydroxy-2-methylpropiophenone are added. The gel is swollen in the dark at 0-4°C for 24-25 hours, and then irradiated with ultraviolet light for 30-60 minutes. The product is then placed in a 0.1-0.15M NaCl solution for 48-50 hours and dried for 3-4 hours to obtain a polyacrylamide-polyacrylic acid double network crystal gel.

[0013] Furthermore, the preparation method of the polyacrylamide single network gel comprises the following steps:

[0014] 10-15 parts by mass of acrylamide and 1-3 parts by mass of N,N'-methylenebisacrylamide are dissolved in 20-25 parts by mass of water, stirred until completely dissolved, 0.5-0.8 parts by mass of ammonium persulfate and 1-1.2 parts by mass of tetramethylethylenediamine are added, reacted in an ice-water bath at 0-4°C for 5-10 minutes, then injected into the gaps of the polytetrafluoroethylene template, reacted in a water bath at 60-65°C for 2-3 hours, then immersed in deionized water for 48-50 hours to remove unreacted monomers, and dried for 3-4 hours to obtain a polyacrylamide single network gel.

[0015] Furthermore, the preparation method of lithium ion molecular sieve powder includes the following steps:

[0016] MnCO3 and LiNO3 are ground in a molar ratio of 1: (1-1.2) until they are fully mixed, and then transferred to a muffle furnace for calcination. The temperature is increased to 270-275°C at a heating rate of 0.5°C / min and calcined for 3-3.2 hours. The temperature is then increased to 350-360°C and calcined for 12-13 hours. The mixture is cooled to room temperature with the furnace, and then acid-washed with 0.5-0.8 mol / L HCl solution for 12-13 hours. The lithium ion molecular sieve powder is obtained after filtration and drying.

[0017] Furthermore, the concentration of acrylic acid in the acrylic acid aqueous solution is 20-25 wt %.

[0018] Furthermore, the concentration of acetic acid in the acetic acid aqueous solution is 2-3 wt %.

[0019] Furthermore, the concentration of the pentanediol solution is 8-10 wt %.

[0020] The present invention has the following advantages:

[0021] 1. The present invention forms a rigid network of acrylamide through covalent crosslinking, and then inserts acrylic acid into the network, and forms an interpenetrating network structure through chemical bonds, so that the prepared polyacrylamide-polyacrylic acid double network crystal gel has good mechanical properties and toughness, and the covalent network can resist acid corrosion of sulfuric acid leaching solution, and maintains its structure unchanged in the acid environment during the adsorption of lithium ions. The good toughness prevents the crystal gel from being easily broken under the action of oscillating force, and has good stability. At the same time, the network structure formed during the polymerization process can expose more adsorption sites, adsorb lithium ions in the acid leaching solution under acidic conditions, and release lithium ions through swelling during desorption, thereby improving the recovery rate of valuable metal lithium.

[0022] 2. The present invention uses polyacrylamide-polyacrylic acid double network crystal gel to load lithium ion molecular sieve. The grid inside the polyacrylamide-polyacrylic acid double network crystal gel presents a weakly alkaline microenvironment. When loading lithium ion molecular sieve, the dissolution of manganese in the acidic leachate can be reduced, thereby avoiding the decomposition of the lithium ion molecular sieve due to the lack of manganese. In addition, the grid gaps of the polyacrylamide-polyacrylic acid double network crystal gel can tightly load the lithium ion molecular sieve particles, preventing the lithium ion molecular sieve particles from falling off or aggregating over a large area. At the same time, the network of the polyacrylamide-polyacrylic acid double network crystal gel has a certain toughness, which can buffer the volume change of the lithium ion molecular sieve during the lithium insertion / deinsertion process, and maintain the lithium ion molecular sieve still has good adsorption capacity when repeatedly used.

[0023] 3. The present invention prepares lithium ion molecular sieves from manganese carbonate and lithium nitrate through a method of low-temperature pre-calcination-high-temperature crystallization-acid washing. Low-temperature pre-calcination forms a transition phase, and high-temperature crystallization promotes the directional growth of the structure and inhibits the generation of impurity phases, ensuring that the final product is a lithium-rich lithium ion molecular sieve, enhancing the lithium ion molecular sieve's ability to embed and deintercalate lithium ions, and achieving high crystallinity and high specific surface area of ​​the lithium ion molecular sieve. In addition, the acid leaching solution of the lithium iron phosphate material disassembled from waste batteries also contains manganese ions. The manganese ions in the leaching solution can replenish the manganese dissolved by the lithium ion molecular sieve, thereby preventing the lithium ion molecular sieve from precipitating manganese and decomposing after repeated use, ensuring that the lithium ion adsorption crystal colloid still has good adsorption capacity after multiple uses. In addition, since the acid leaching solution of the lithium iron phosphate material contains almost no magnesium, the lithium ion molecular sieve will not adsorb magnesium and lithium at the same time and cannot be effectively distinguished, thereby ensuring the purity of the recovered lithium carbonate. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 This is a scanning electron microscope image of the lithium ion molecular sieve powder prepared in Example 1 of the present invention.

[0025] Figure 2 This is the XRD pattern of the lithium ion molecular sieve powder prepared in Example 1 of the present invention.

[0026] Figure 3 This is a pH value diagram measured by a polyacrylamide-polyacrylic acid double network crystal gel pH meter prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0027] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0028] Example 1:

[0029] A method for efficiently recovering valuable metals from waste lithium iron phosphate materials comprises the following steps:

[0030] S1: Grind MnCO3 and LiNO3 in a molar ratio of 1:1 until they are fully mixed, move them into a muffle furnace and calcine them. Heat them to 270℃ at a heating rate of 0.5℃ / min and calcine them for 3h, then heat them to 350℃ and calcine them for 12h. Cool them to room temperature with the furnace, then pickle them with 0.5mol / L HCl solution for 12h, filter and dry them to obtain lithium ion molecular sieve powder. The electron microscope image is as follows: Figure 1 As shown, the XRD pattern is Figure 2 shown.

[0031] S2: Dissolve 10 parts by mass of acrylamide and 1 part by mass of N,N'-methylenebisacrylamide in 20 parts by mass of water, stir until completely dissolved, add 0.5 parts by mass of ammonium persulfate and 1 part by mass of tetramethylethylenediamine, react in an ice-water bath at 0°C for 5 minutes, then inject into the gaps of the polytetrafluoroethylene template, react in a water bath at 60°C for 2 hours, then soak in deionized water for 48 hours to remove unreacted monomers, and dry for 3 hours to obtain a polyacrylamide single network gel.

[0032] S3: The polyacrylamide single network gel is completely immersed in an acrylic acid aqueous solution with a system mass percentage of 20wt%, wherein the concentration of acrylic acid in the acrylic acid aqueous solution is 20wt%, and then 0.5wt% of polyethylene glycol diacrylate and 1wt% of 2-hydroxy-2-methylpropiophenone are added. The gel is swollen in the dark at 0°C for 24h, and then irradiated with ultraviolet light for 30min. The product is then placed in a 0.1M NaCl solution for 48h and dried for 3h to obtain a polyacrylamide-polyacrylic acid double network gel. Its pH value is as follows: Figure 3 shown.

[0033] S4: Add 0.5 parts by mass of polyacrylamide-polyacrylic acid double network crystal gel to 15 parts by mass of acetic acid aqueous solution, wherein the acetic acid concentration in the acetic acid aqueous solution is 2wt%, stir at room temperature until it is completely dissolved, then add 5 parts by mass of glutaraldehyde solution, the concentration of pentanediol solution is 8wt%, stir for 20 minutes, then add 50% by mass of lithium ion molecular sieve powder of the system, then place in a refrigerator at -4°C for 4 hours, then stir in an ice water bath for 1 hour, then place at room temperature and heat to 22°C, wash twice with deionized water to obtain lithium ion adsorption crystal gel.

[0034] S5: The waste lithium iron phosphate material disassembled from the battery is immersed in a sulfuric acid solution with a material-liquid ratio of 1g:10mL. The concentration of the sulfuric acid solution is 2mol / L. Then 3vol% H2O2 is added. The temperature is raised to 60℃ and the reaction is carried out for 3h. At the same time, the stirring speed is 300r / min. The solid matter is then removed by filtration. The filtrate is added with NaOH solution to adjust the pH value to 6.5 to obtain a lithium-containing recovery liquid;

[0035] The lithium ion adsorbed crystal gel was added to the lithium-containing recovery liquid at a solid-liquid ratio of 1 g:5 mL, and the mixture was shaken at a constant temperature of 30°C and a speed of 120 r / min for 12 hours. The filtrate was then filtered to remove the adsorbed lithium ion adsorbed crystal gel, which was then placed in a 0.5 M HCl solution and shaken at 30°C and a speed of 150 r / min for 12 hours for desorption to obtain a lithium ion solution.

[0036] The lithium ion solution was heated to 55°C, and a saturated sodium carbonate solution was continuously added to the lithium ion solution while stirring at a speed of 50 r / min until no new precipitation was generated in the system, thereby obtaining lithium carbonate precipitation and completing lithium recovery.

[0037] Example 2:

[0038] A method for efficiently recovering valuable metals from waste lithium iron phosphate materials comprises the following steps:

[0039] S1: Grind MnCO3 and LiNO3 in a molar ratio of 1:1.2 until they are fully mixed, transfer them to a muffle furnace and calcine them. Heat the temperature to 270℃ at a heating rate of 0.5℃ / min and calcine for 3h, then heat the temperature to 350℃ and calcine for 12h. Cool them to room temperature with the furnace, then pickle them with 0.5mol / L HCl solution for 12h, filter and dry them to obtain lithium ion molecular sieve powder.

[0040] S2: Dissolve 15 parts by mass of acrylamide and 3 parts by mass of N,N'-methylenebisacrylamide in 25 parts by mass of water, stir until completely dissolved, add 0.8 parts by mass of ammonium persulfate and 1.2 parts by mass of tetramethylethylenediamine, react in an ice-water bath at 0°C for 5 minutes, then inject into the gaps of the polytetrafluoroethylene template, react in a water bath at 60°C for 2 hours, then soak in deionized water for 48 hours to remove unreacted monomers, and dry for 3 hours to obtain a polyacrylamide single network gel.

[0041] S3: The polyacrylamide single network gel is completely immersed in an acrylic acid aqueous solution with a system mass percentage of 25 wt%, wherein the concentration of acrylic acid in the acrylic acid aqueous solution is 25 wt%, and then 0.8 wt% of polyethylene glycol diacrylate and 2 wt% of 2-hydroxy-2-methylpropiophenone are added. The gel is swollen in the dark at 0°C for 24 h, and then irradiated with ultraviolet light for 30 min. The product is then placed in a 0.15 M NaCl solution for 48 h and dried for 3 h to obtain a polyacrylamide-polyacrylic acid double network crystal gel.

[0042] S4: Add 1 part by mass of polyacrylamide-polyacrylic acid double network crystal gel to 20 parts by mass of acetic acid aqueous solution, wherein the acetic acid concentration in the acetic acid aqueous solution is 2wt%, stir at room temperature until it is completely dissolved, then add 10 parts by mass of glutaraldehyde solution, the concentration of pentanediol solution is 10wt%, stir for 20 minutes, then add 50% by mass of lithium ion molecular sieve powder of the system, then place in a refrigerator at -4°C for 4 hours, then stir in an ice water bath for 1 hour, then place at room temperature and heat to 22°C, wash twice with deionized water to obtain lithium ion adsorption crystal gel.

[0043] S5: The waste lithium iron phosphate material disassembled from the battery is immersed in a sulfuric acid solution with a material-liquid ratio of 1g:15mL. The concentration of the sulfuric acid solution is 2mol / L. Then 5vol% H2O2 is added. The temperature is raised to 60℃ and the reaction is carried out for 3h. At the same time, the speed is stirred at 300r / min. The solid matter is then removed by filtration. The filtrate is added with NaOH solution to adjust the pH value to 6.5 to obtain a lithium-containing recovery liquid;

[0044] The lithium ion adsorbed crystal gel was added to the lithium-containing recovery liquid at a solid-liquid ratio of 1 g:8 mL, and the mixture was shaken at a constant temperature of 30°C and a speed of 120 r / min for 12 hours. The filtrate was then filtered to remove the adsorbed lithium ion adsorbed crystal gel, which was then placed in a 0.5 M HCl solution and shaken at 30°C and a speed of 150 r / min for 12 hours for desorption to obtain a lithium ion solution.

[0045] The lithium ion solution was heated to 55°C, and a saturated sodium carbonate solution was continuously added to the lithium ion solution while stirring at a speed of 50 r / min until no new precipitation was generated in the system, thereby obtaining lithium carbonate precipitation and completing lithium recovery.

[0046] Example 3:

[0047] A method for efficiently recovering valuable metals from waste lithium iron phosphate materials comprises the following steps:

[0048] S1: Grind MnCO3 and LiNO3 in a molar ratio of 1:1 until they are fully mixed, transfer them to a muffle furnace and calcine them. Heat the temperature to 275°C at a heating rate of 0.5°C / min and calcine for 3.2 hours. Then heat the temperature to 360°C and calcine for 13 hours. Cool them to room temperature with the furnace, and then acid-wash them with 0.8 mol / L HCl solution for 13 hours. After filtering and drying, lithium ion molecular sieve powder is obtained.

[0049] S2: Dissolve 10 parts by mass of acrylamide and 1 part by mass of N,N'-methylenebisacrylamide in 20 parts by mass of water, stir until completely dissolved, add 0.5 parts by mass of ammonium persulfate and 1 part by mass of tetramethylethylenediamine, react in an ice-water bath at 4°C for 10 minutes, then inject into the gaps of the polytetrafluoroethylene template, react in a water bath at 65°C for 3 hours, then soak in deionized water for 50 hours to remove unreacted monomers, and dry for 4 hours to obtain a polyacrylamide single network gel.

[0050] S3: The polyacrylamide single network gel is completely immersed in an acrylic acid aqueous solution with a system mass percentage of 20 wt%, wherein the concentration of acrylic acid in the acrylic acid aqueous solution is 20 wt%, and then 0.5 wt% of polyethylene glycol diacrylate and 1 wt% of 2-hydroxy-2-methylpropiophenone are added. The gel is swollen in the dark at 4°C for 25 h, and then irradiated with ultraviolet light for 60 min. The product is then placed in a 0.1 M NaCl solution for 50 h and dried for 4 h to obtain a polyacrylamide-polyacrylic acid double network crystal gel.

[0051] S4: Add 0.5 parts by mass of polyacrylamide-polyacrylic acid double network crystal gel to 15 parts by mass of acetic acid aqueous solution, wherein the acetic acid concentration in the acetic acid aqueous solution is 2wt%, stir at room temperature until it is completely dissolved, then add 5 parts by mass of glutaraldehyde solution, the concentration of pentanediol solution is 8wt%, stir for 30 minutes, then add 50% by mass of lithium ion molecular sieve powder of the system, then place in a refrigerator at 0°C for 4.5 hours, then stir in an ice water bath for 2 hours, then place at room temperature and heat to 24°C, wash twice with deionized water to obtain lithium ion adsorption crystal gel.

[0052] S5: The waste lithium iron phosphate material disassembled from the battery is immersed in a sulfuric acid solution with a material-liquid ratio of 1g:10mL. The concentration of the sulfuric acid solution is 4mol / L. Then 3vol% H2O2 is added. The temperature is raised to 80℃ and the reaction is carried out for 4h. At the same time, the speed is stirred at 400r / min. The solid matter is then removed by filtration. The filtrate is added with NaOH solution to adjust the pH value to 7.5 to obtain a lithium-containing recovery liquid;

[0053] The lithium ion adsorbed crystal gel was added to the lithium-containing recovery liquid at a solid-liquid ratio of 1 g:5 mL, and the mixture was shaken at a constant temperature of 35°C and a speed of 150 r / min for 13 hours. The filtrate was then filtered to remove the adsorbed lithium ion adsorbed crystal gel, which was then placed in a 0.5 M HCl solution and shaken at 35°C and a speed of 180 r / min for 13 hours for desorption to obtain a lithium ion solution.

[0054] The lithium ion solution was heated to 60°C, and a saturated sodium carbonate solution was continuously added to the lithium ion solution while stirring at a speed of 60 r / min until no new precipitation was generated in the system, thereby obtaining lithium carbonate precipitation and completing lithium recovery.

[0055] Comparative Example 1:

[0056] Compared with Example 1, the difference of Comparative Example 1 is that step S1 is not performed, and lithium ion molecular sieve powder is not added in step S4, but Li4Ti5O 12 The lithium ion molecular sieve was replaced with the other steps remaining unchanged, which is recorded as Comparative Example 1.

[0057] Comparative Example 2:

[0058] Compared with Example 1, the difference of Comparative Example 2 is that step S3 is not performed, and polyacrylamide-polyacrylic acid double network crystal gel is not added in step S4. Instead, polyacrylamide single network gel is used to replace polyacrylamide-polyacrylic acid double network crystal gel, and the other steps remain unchanged, which is recorded as Comparative Example 2.

[0059] Comparative Example 3:

[0060] Compared with Example 1, the difference of Comparative Example 3 is that step S2 is not performed, polyacrylamide single network gel is not added in step S3, acrylic crystal gel is prepared, and the acrylic crystal gel is used to replace the polyacrylamide-polyacrylic acid double network crystal gel in step S4. The other steps remain unchanged and are recorded as Comparative Example 3.

[0061] Comparative Example 4:

[0062] Compared with Example 1, the difference of Comparative Example 4 is that step S4 is not performed, and lithium ion adsorption crystal gel is not used in step S5. Instead, polyacrylamide-polyacrylic acid double network crystal gel is used to replace lithium ion adsorption crystal gel, and the other steps remain unchanged, which is recorded as Comparative Example 4.

[0063] Comparative Example 5:

[0064] Compared with Example 1, the difference of Comparative Example 5 is that step S4 is not performed, and lithium ion adsorption crystal colloid is not used in step S5. Instead, lithium ion molecular sieve powder is used to replace lithium ion adsorption crystal colloid. The other steps remain unchanged and are recorded as Comparative Example 5.

[0065] The purity of lithium carbonate in Test Examples 1-3 and Comparative Example 1 is shown in Table 1.

[0066] The lithium recovery rates of Test Examples 1-3 and Comparative Examples 1-3 are shown in Table 2.

[0067] The adsorption amounts of the lithium ion adsorption crystal gels of Examples 1-3 and Comparative Examples 4-5 in the first adsorption and after 5 adsorption-desorption cycles are shown in Table 3.

[0068] Table 1

[0069]

[0070] Table 2

[0071]

[0072] Table 3

[0073]

[0074] As can be seen from Table 1, the purity of lithium carbonate obtained in Examples 1-3 is 98%, while the purity of lithium carbonate in Comparative Example 1 is 95%. The titanium-based lithium adsorbent Li4Ti5O 12 However, since the acid leaching solution of lithium iron phosphate material does not contain titanium, the titanium-based lithium adsorbent is prone to decomposition during the adsorption process of the acid leaching solution, resulting in impurities during desorption and reducing the purity of lithium carbonate.

[0075] As can be seen from Table 2, the lithium recovery rates of Examples 1-3 are all higher than those of the comparative example, which shows that the raw material combination of the present invention has better lithium recovery capability.

[0076] It can be seen from Table 3 that the first lithium adsorption amount and the adsorption amount after 5 cycles of Examples 1-3 are higher than those of Comparative Examples 4-5, and the degree of decrease in the adsorption amount after 5 cycles is also lower than that of the Comparative Examples. It can be seen that the raw material combination of Examples 1-3 can maintain the good adsorption capacity of the lithium ion molecular sieve during repeated use.

[0077] It should be understood that those skilled in the art may make improvements or modifications based on the above description, and all such improvements and modifications shall fall within the scope of protection of the appended claims. Any portion of this specification not described in detail is prior art known to those skilled in the art.

Claims

1. A method for efficiently recovering valuable metals from waste lithium iron phosphate materials, characterized in that: The steps include: The waste lithium iron phosphate material disassembled from the battery is immersed in a sulfuric acid solution with a material-liquid ratio of 1g: (10-15)mL. The concentration of the sulfuric acid solution is 2-4mol / L. Then 3-5vol% H2O2 is added. The temperature is raised to 60-80℃ and the reaction is carried out for 3-4h. At the same time, the speed is stirred at 300-400r / min. The solid matter is then removed by filtration. The filtrate is added with NaOH solution to adjust the pH value to 6.5-7.5 to obtain a lithium-containing recovery liquid. The lithium ion adsorbed crystal colloid is added to the lithium-containing recovery liquid at a solid-liquid ratio of 1 g: (5-8) mL, and the mixture is shaken at a constant temperature of 30-35°C and a speed of 120-150 r / min for 12-13 hours. The filtrate is then filtered to remove the adsorbed lithium ion crystal colloid, which is then placed in a 0.5-1 M HCl solution and shaken at a speed of 150-180 r / min at 30-35°C for 12-13 hours for desorption to obtain a lithium ion solution. The lithium ion solution is heated to 55-60°C, and a saturated sodium carbonate solution is continuously added to the lithium ion solution while stirring at a speed of 50-60 r / min until no new precipitation is generated in the system, thereby obtaining lithium carbonate precipitation and completing lithium recovery; The preparation method of lithium ion adsorption crystal colloid comprises: 0.5-1 parts by mass of polyacrylamide-polyacrylic acid double network crystal gel is added to 15-20 parts by mass of acetic acid aqueous solution, stirred at room temperature until it is completely dissolved, then 5-10 parts by mass of glutaraldehyde solution is added, stirred for 20-30 minutes, and then 50-75% by mass of lithium ion molecular sieve powder is added, followed by placing in a refrigerator at -4-0°C for 4-4.5 hours, then stirring in an ice water bath for 1-2 hours, then placing at room temperature and heating to 22-24°C, and washing twice with deionized water to obtain lithium ion adsorption crystal gel; Dissolve 10-15 parts by mass of acrylamide and 1-3 parts by mass of N,N'-methylenebisacrylamide in 20-25 parts by mass of water, stir until completely dissolved, add 0.5-0.8 parts by mass of ammonium persulfate and 1-1.2 parts by mass of tetramethylethylenediamine, react in an ice-water bath at 0-4°C for 5-10 minutes, then inject into the gaps of the polytetrafluoroethylene template, react in a water bath at 60-65°C for 2-3 hours, then soak in deionized water for 48-50 hours to remove unreacted monomers, and dry for 3-4 hours to obtain a polyacrylamide single network gel; The polyacrylamide single network gel is completely immersed in an acrylic acid aqueous solution with a system mass proportion of 20-25wt%, and then 0.5-0.8wt% of polyethylene glycol diacrylate and 1-2wt% of 2-hydroxy-2-methylpropiophenone are added, and the gel is swollen in the dark at 0-4°C for 24-25h, followed by ultraviolet light irradiation for 30-60min, and then the product is placed in a 0.1-0.15M NaCl solution for 48-50h, and dried for 3-4h to obtain a polyacrylamide-polyacrylic acid double network gel; The preparation method of lithium ion molecular sieve includes: MnCO3 and LiNO3 are ground in a molar ratio of 1: (1-1.2) until they are fully mixed, and then transferred to a muffle furnace for calcination. The temperature is increased to 270-275°C at a heating rate of 0.5°C / min and calcined for 3-3.2 hours. The temperature is then increased to 350-360°C and calcined for 12-13 hours. The mixture is cooled to room temperature with the furnace, and then acid-washed with 0.5-0.8 mol / L HCl solution for 12-13 hours. The lithium ion molecular sieve powder is obtained after filtration and drying.

2. The method for efficiently recovering valuable metals from waste lithium iron phosphate materials according to claim 1, characterized in that: The concentration of acrylic acid in the acrylic acid aqueous solution is 20-25 wt %.

3. The method for efficiently recovering valuable metals from waste lithium iron phosphate materials according to claim 1, characterized in that: The concentration of acetic acid in the acetic acid aqueous solution is 2-3 wt %.

4. The method for efficiently recovering valuable metals from waste lithium iron phosphate materials according to claim 1, characterized in that: The concentration of the pentanediol solution is 8-10wt%.

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