A method for recovering copper from waste lithium iron phosphate battery materials

Abstract

The present invention discloses a method for recovering copper from waste lithium iron phosphate battery materials. The method comprises the following steps: 1) subjecting the waste lithium iron phosphate battery materials to acid leaching, controlling the pH value of the reaction solution to less than 0.8 at the end of the reaction, and obtaining a waste lithium iron phosphate battery material leachate, wherein the waste lithium iron phosphate battery material leachate contains copper and iron; 2) extracting the leachate with an extractant to obtain a copper-loaded extractant and a raffinate having a pH value less than 0.8; and 3) sequentially washing and stripping the copper-loaded extractant obtained in step 2) to obtain a copper stripping solution and a stripped extractant. The method provided by the present invention can extract and recover copper from the waste lithium iron phosphate battery material leachate without being affected by impurity elements such as iron.

Description

Technical Field

[0001] The present invention relates to the technical field of hydrometallurgy, and in particular to a method for recovering copper from waste lithium iron phosphate battery materials. Background Art

[0002] Copper is a vital raw material and strategic resource for national economic development and national defense science and technology development, and is also a key indicator for impurity element control. Spent lithium iron phosphate battery materials contain copper, which is often removed as an impurity element.

[0003] The existing method of extracting copper from waste lithium iron phosphate battery materials has the disadvantages of poor copper separation and recovery effect, high process cost, complicated operation, and environmental protection. Therefore, it is necessary to propose a process method that has good separation and recovery effect of copper in waste lithium iron phosphate battery materials and is simple to operate. Summary of the Invention

[0004] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method for recovering copper from waste lithium iron phosphate battery materials. The method has a good copper extraction effect and can effectively remove copper from the lithium iron phosphate battery material leachate without being affected by impurity elements such as iron.

[0005] To achieve the above object, the present invention provides the following technical solution: a method for recovering copper from waste lithium iron phosphate battery materials, comprising the following steps:

[0006] 1) acid leaching the waste lithium iron phosphate battery material, controlling the pH value of the reaction solution to be less than 0.8 at the end of the reaction, to obtain a waste lithium iron phosphate battery material leachate, wherein the waste lithium iron phosphate battery material leachate contains copper and iron;

[0007] 2) extracting the leachate with an extractant to obtain a copper-loaded extractant and a raffinate having a pH value of less than 0.8; and

[0008] 3) washing and stripping the copper-loaded extractant obtained in step 2) in sequence to obtain a copper stripping solution and a stripping extractant;

[0009] Wherein, the extractant comprises a chelating resin of formula (I) and / or formula (II):

[0010] (I) (II)

[0011] in:

[0012] P is the base resin;

[0013] R1 and R2 are each independently a nitrogen-containing heterocyclic group;

[0014] R3 is an acyl group or hydrogen; and

[0015] M is ( ) x , wherein n and m are independently integers of 2-10; x is 0 or 1.

[0016] The present invention does not particularly limit the base resin P. Preferably, the base resin P is selected from polystyrene resins, copolymers of styrene and divinylbenzene, phenolic resin polymers, polyacrylic resins, and silicone-based resins. More preferably, the base resin P is selected from polystyrene resins and copolymers of styrene and divinylbenzene.

[0017] Specifically, n and m are independently 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0018] Preferably, the nitrogen-containing heterocyclic groups R1 and R2 are each independently selected from a pyridine group, an imidazole group, a benzimidazole group, a pyrazole group, a quinoline group, a pyrazine group, a triazine group and a triazole group.

[0019] More specifically, the nitrogen-containing heterocyclic groups R1 and R2 are each independently selected from the following groups:

[0020] 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 and .

[0021] Preferably, the nitrogen-containing heterocyclic groups R1 and R2 are each independently selected from the following groups:

[0022] 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 and .

[0023] In the present invention, the acid leaching in step 1) is not particularly limited and can be carried out in a manner commonly used in the art. Preferably, an acid solution is used as the leaching agent, the ratio of the acid solution to the waste lithium iron phosphate battery material is measured at a molar ratio of acid in the acid solution to lithium iron phosphate of 0.8-1.8:1, the temperature is 30-65°C, the time is 2-6 hours, and the acid solution concentration is preferably 0.5-6 mol / L. The acid solution includes at least one of hydrochloric acid, sulfuric acid, and nitric acid solution, preferably sulfuric acid solution.

[0024] In the present invention, the pH value of the waste lithium iron phosphate battery material leachate in step 1) is less than 0.8, preferably, 0.1-0.7, and the pH value of the raffinate is preferably ≤0.7.

[0025] Preferably, the extraction in step 1) is a single-stage, or multi-stage series and / or parallel extraction, and the number of extraction stages is 1-10, preferably 2-7.

[0026] Preferably, the extraction flow rate is 1-25 Bv / h, preferably 1.5-10 Bv / h.

[0027] Preferably, the stripping agent used in the stripping in step 3) is any one of an inorganic acid solution, ammonia water, and disodium EDTA, or a combination of disodium EDTA and an inorganic acid solution or ammonia water, respectively. The inorganic acid solution includes hydrochloric acid and / or sulfuric acid, and the concentration of the sulfuric acid is 1-6 mol / L, preferably 2-3 mol / L; the concentration of the ammonia water is 1-6 mol / L, preferably 2-4 mol / L; the concentration of the disodium EDTA is 0.05-0.3 mol / L, preferably 0.1-0.2 mol / L.

[0028] Preferably, the stripping flow rate is 0.5-5 Bv / h, preferably 0.5-3 Bv / h.

[0029] Preferably, the number of washing stages in step 3) is 1-10, preferably 2-7.

[0030] Preferably, the washing flow rate is 1-25 Bv / h, preferably 2-10 Bv / h.

[0031] Preferably, the pH value of the washing liquid used for the washing is 0.1-1.2, preferably 0.5-1.0, more preferably 0.8-1.0.

[0032] In the present invention, the washing liquid having a pH value of 0.8-1.0 is not particularly limited, and is preferably a hydrochloric acid and / or sulfuric acid solution.

[0033] Preferably, the water after washing is directly used as water for the acid leaching in step 1), thereby reducing the amount of water used in the recovery process.

[0034] Preferably, the extractant after stripping in step 3) is regenerated and recycled. Preferably, the regeneration is performed to control the pH value of the regenerated water to be 0.2-3, more preferably, 0.5-2.5.

[0035] Preferably, the regenerated water is directly used as water for preparing the stripping agent, thereby reducing the amount of water used in the recovery process.

[0036] In the present invention, the regeneration agent used in the regeneration is not particularly limited, and is preferably water, such as any one or more of pure water, soft water, and tap water.

[0037] In the present invention, the copper stripping solution can be directly or concentrated to prepare metallic copper by electrowinning or iron powder can be added to prepare sponge copper.

[0038] Compared with the prior art, the present invention provides a method for recovering copper from waste lithium iron phosphate battery materials, which has the following beneficial effects:

[0039] 1. The method provided by the present invention can effectively extract and separate copper without being affected by impurity elements such as iron. In addition, the chelating resin can be recycled after regeneration, and the operating cost is low.

[0040] 2. In the method provided by the present invention, the copper content in the raffinate is ≤0.005 g / L, and the loss rates of iron and phosphorus are less than 1%. DETAILED DESCRIPTION

[0041] In the following, various aspects of the invention as well as further objects, features and advantages will be described in more detail.

[0042] The present invention provides a method for recovering copper from waste lithium iron phosphate battery materials, which comprises the following steps:

[0043] 1) acid leaching the waste lithium iron phosphate battery material, controlling the pH value of the reaction solution to be less than 0.8 at the end of the reaction, to obtain a waste lithium iron phosphate battery material leachate, wherein the waste lithium iron phosphate battery material leachate contains copper and iron;

[0044] 2) extracting the leachate with an extractant to obtain a copper-loaded extractant and a raffinate having a pH value of less than 0.8; and

[0045] 3) washing and stripping the copper-loaded extractant obtained in step 2) in sequence to obtain a copper stripping solution and a stripping extractant;

[0046] Wherein, the extractant comprises a chelating resin of formula (I) and / or formula (II):

[0047] (I) (II)

[0048] in:

[0049] P is the base resin;

[0050] R1 and R2 are each independently a nitrogen-containing heterocyclic group;

[0051] R3 is an acyl group or hydrogen; and

[0052] M is ( ) x , wherein n and m are independently integers of 2-10; x is 0 or 1.

[0053] The chelating resin of the present invention has good selectivity for metal ions and can realize the extraction and separation of metal ions such as copper and iron in an acidic solution (pH <0.8) with good separation effect.

[0054] The present invention does not particularly limit the base resin P. Preferably, the base resin P is selected from polystyrene resins, copolymers of styrene and divinylbenzene, phenolic resin polymers, polyacrylic resins, and silicone-based resins. More preferably, the base resin P is selected from polystyrene resins and copolymers of styrene and divinylbenzene.

[0055] Specifically, n and m are independently 2, 3, 4, 5, 6, 7, 8, 9 or 10.

[0056] Preferably, the nitrogen-containing heterocyclic groups R1 and R2 are each independently selected from a pyridine group, an imidazole group, a benzimidazole group, a pyrazole group, a quinoline group, a pyrazine group, a triazine group and a triazole group.

[0057] More specifically, the nitrogen-containing heterocyclic groups R1 and R2 are each independently selected from the following groups:

[0058] 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 and .

[0059] Preferably, the nitrogen-containing heterocyclic groups R1 and R2 are each independently selected from the following groups:

[0060] 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 and .

[0061] Preferably, the acyl group is -(CO)R4 or -CH2(CO)R4, wherein R4 is a straight-chain or branched alkyl group having a carbon chain number of 1-5, -N-(R5)2 or a nitrogen-containing heterocyclic group as defined for R1 or R2, wherein R5 is a straight-chain or branched alkyl group having a carbon chain number of 1-5.

[0062] Preferably, the chelating resin of formula (I) has a structure selected from the following:

[0063] 、 、 、 、 、 、 、 、 、 、 、 .

[0064] Preferably, the chelating resin of formula (II) has a structure selected from the following:

[0065] 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 .

[0066] More preferably, the chelating resin comprises:

[0067] and ,or and ,or and ,or ,or ,or and ,or ,or and ,or ,or ,or ,or and ,

[0068] Wherein P is independently selected from polystyrene resin, copolymer of styrene and divinylbenzene, phenolic resin polymer, polyacrylic resin and silicon-based resin.

[0069] In the present invention, the acid leaching in step 1) is not particularly limited and can be carried out in a manner commonly used in the art. Preferably, an acid solution is used as the leaching agent, the ratio of the acid solution to the waste lithium iron phosphate battery material is measured based on a molar ratio of acid in the acid solution to lithium iron phosphate of 0.8-1.8:1, the temperature is 20-65°C, the time is 2-6 hours, and the acid solution concentration is preferably 0.5-6 mol / L. The acid solution includes at least one of hydrochloric acid, sulfuric acid, and nitric acid solution, preferably sulfuric acid solution.

[0070] In the present invention, the pH value of the waste lithium iron phosphate battery material leachate in step 1) is less than 0.8, preferably, 0.1-0.7; the pH value of the raffinate is preferably ≤0.7.

[0071] In the present invention, the pH value of the feed solution is controlled to be less than 0.8, preferably 0.1-0.7, and the pH value of the raffinate is controlled to be less than 0.8, preferably ≤ 0.7. On the one hand, precipitation of ferric phosphate can be avoided, and on the other hand, a higher extraction rate of copper can be ensured.

[0072] Preferably, the extraction in step 1) is a single-stage, or multi-stage series and / or parallel extraction, and the number of extraction stages is 1-10, more preferably 2-7.

[0073] Preferably, the extraction flow rate is 1-25 Bv / h, more preferably, 1.5-10 Bv / h.

[0074] Preferably, the stripping agent used in the stripping in step 2) is any one of an inorganic acid solution, aqueous ammonia, and disodium EDTA, or a combination of disodium EDTA and an inorganic acid solution or aqueous ammonia, respectively. The inorganic acid solution includes hydrochloric acid and / or sulfuric acid, and the concentration of the sulfuric acid is 1-6 mol / L, preferably 2-3 mol / L; the concentration of the aqueous ammonia is 1-6 mol / L, preferably 2-4 mol / L; the concentration of disodium EDTA is 0.05-0.3 mol / L, preferably 0.1-0.2 mol / L.

[0075] Preferably, the stripping flow rate is 0.5-5 Bv / h, more preferably, 0.5-3 Bv / h.

[0076] Preferably, the number of washing stages in step 3) is 1-10, more preferably 2-7.

[0077] Preferably, the washing flow rate is 1-25 Bv / h, preferably 2-10 Bv / h.

[0078] Preferably, the pH value of the washing liquid used for the washing is 0.1-1.2, preferably 0.5-1.0, more preferably 0.8-1.0.

[0079] In the present invention, the washing liquid having a pH value of 0.8-1.0 is not particularly limited, and is preferably a hydrochloric acid and / or sulfuric acid solution.

[0080] Preferably, the water after washing is directly used as water for the acid leaching in step 1), thereby reducing the amount of water used in the recovery process.

[0081] In the present invention, controlling the pH value of the washing liquid to 0.8-1.0 can make it easier to wash out the iron, which on the one hand reduces the amount of washing acid used, and on the other hand prevents the precipitation of iron phosphate.

[0082] Preferably, the extractant after stripping in step 3) is regenerated and recycled. Preferably, the pH value of the regenerated water is controlled to be 0.2-3, more preferably, 0.5-2.5.

[0083] Preferably, the regenerated water is directly used as water for preparing the stripping agent, thereby reducing the amount of water used in the recovery process.

[0084] In the present invention, the regeneration agent used in the regeneration is not particularly limited, and is preferably water, such as any one or more of pure water, soft water, and tap water.

[0085] In the present invention, the copper stripping solution can be directly or concentrated to prepare metallic copper by electrowinning or iron powder can be added to prepare sponge copper.

[0086] The method provided by the present invention has good extraction and recovery effect on copper, can effectively separate copper from other metal ions such as iron, is simple to operate, and has low operating cost.

[0087] Example

[0088] The following will further illustrate the concept, specific structure and technical effects of the present invention in conjunction with the embodiments, so that those skilled in the art can fully understand the purpose, features and effects of the present invention. It will be readily understood by those skilled in the art that the embodiments herein are for illustrative purposes only and the scope of the present invention is not limited thereto.

[0089] Example 1

[0090] 60 g of waste lithium iron phosphate battery material was added to 250 mL of 1:6 sulfuric acid solution, heated at 60°C under nitrogen protection, and dissolved for 2 h. The pH value of the reaction solution was controlled to 0.2 at the reaction end point, and then filtered to obtain the waste lithium iron phosphate battery leachate containing copper and iron. The content of each element is shown in Table 1.

[0091] Table 1 Contents of elements in the leachate of waste lithium iron phosphate batteries

[0092] element Cu Fe P Al Li Content (g / L) 0.48 70.15 42.42 0.35 8.1

[0093] Using chelating resin (structural formula is and , where P is polystyrene resin microspheres, was used to extract copper from the leachate of used lithium iron phosphate batteries. The reaction equipment used was an ion exchange resin column, with three extraction stages and a controlled extraction flow rate of 2.5 Bv / h. Upon completion, a copper-loaded chelate resin and a raffinate were obtained. The copper-loaded chelate resin was washed with a sulfuric acid solution at a pH of 1 to remove impurities such as iron. The washing flow rate was controlled at 5 Bv / h and three washing stages, resulting in a washed copper-loaded chelate resin and a washed solution. Stripping was performed using 2 mol / L sulfuric acid at a controlled stripping flow rate of 0.5 Bv / h to obtain a copper stripping solution. The stripped chelate resin was then washed with pure water until the effluent pH reached 0.2 and recycled.

[0094] In this embodiment, the copper content in the raffinate is 0.005 g / L, and the loss rates of iron and phosphorus are 0.4% and 0.5%, respectively.

[0095] Example 2

[0096] 50 g of waste lithium iron phosphate battery material was added to 250 mL of 1:9 sulfuric acid solution, heated to 60°C under nitrogen protection, and dissolved for 2 h. The pH value of the reaction solution was controlled to 0.6 at the reaction end point, and then filtered to obtain the waste lithium iron phosphate battery leachate containing copper and iron. The content of each element is shown in Table 2.

[0097] Table 2 Contents of main elements in the leachate of waste lithium iron phosphate battery materials

[0098] element Cu Fe P Al Li Content (g / L) 0.32 63.2 40.6 0.31 7.5

[0099] Using chelating resin (structural formula is and , where P is a polystyrene resin and a copolymer of styrene and divinylbenzene) to extract copper from the leachate of waste lithium iron phosphate battery materials. The reaction equipment is an ion exchange resin column, the extraction stage is three, and the extraction flow rate is controlled at 2 Bv / h. After extraction is completed, a copper-loaded chelate resin and a raffinate are obtained. The copper-loaded chelate resin is washed with sulfuric acid solution with a pH value of 1 to remove impurities such as iron. The washing flow rate is controlled at 3 Bv / h and the washing stage is three, resulting in a washed copper-loaded chelate resin and a washed solution. Stripping is performed using 3 mol / L sulfuric acid at a stripping flow rate of 3 Bv / h to obtain a copper stripping solution. The stripping chelate resin is washed with pure water until the pH of the effluent is 0.5 and then recycled.

[0100] In this example, the copper content in the raffinate is 0.003 g / L, and the loss rates of iron and phosphorus are 0.5% and 0.55%, respectively.

[0101] Example 3

[0102] 55 g of waste lithium iron phosphate battery material was added to 250 mL of a 1:7 sulfuric acid solution, heated to 60°C under nitrogen protection, and dissolved for 2 h. The pH value of the reaction solution was controlled to 0.5 at the reaction endpoint, and then filtered to obtain a waste lithium iron phosphate battery leachate containing copper and iron. The content of each element is shown in Table 3.

[0103] Table 3 Contents of main elements in the leachate of waste lithium iron phosphate battery materials

[0104] element Cu Fe P Al Li Content (g / L) 0.03 78.5 46.42 1.2 0.3

[0105] Using chelating resin (structural formula is and , where P is polystyrene resin microspheres, was used to extract copper from the leachate of waste lithium iron phosphate battery materials. The reaction equipment used was an ion exchange resin column, with two extraction stages and a controlled extraction flow rate of 5 Bv / h. Upon completion of the extraction, a copper-loaded chelate resin and a raffinate were obtained. The copper-loaded chelate resin was washed with sulfuric acid solution at a pH of 1 to remove impurities such as iron. The washing flow rate was controlled at 5 Bv / h and the washing stage was three, resulting in a washed copper-loaded chelate resin and a washed solution. Stripping was performed using 2 mol / L ammonia water at a controlled stripping flow rate of 0.5 Bv / h to obtain a copper stripping solution. The stripped chelate resin was then washed with pure water until the effluent pH reached 1.0 and then recycled.

[0106] In this embodiment, the copper content in the raffinate is less than 0.001 g / L, and the loss rates of iron and phosphorus are 0.4% and 0.5%, respectively.

[0107] Comparative Example 1

[0108] This embodiment is carried out with reference to the process in Extraction Example 1. The difference from Extraction Example 1 is that the structural formula of the chelating resin is , where P is polystyrene resin microspheres.

[0109] In this embodiment, the copper content in the raffinate is 0.014 g / L, and the iron loss rate is 1.6%.

[0110] The above merely describes exemplary embodiments or examples of the present invention and is not intended to limit the present invention. It will be apparent to those skilled in the art that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention are intended to be included within the scope of the claims of this application.

Claims

1. A method for recovering copper from waste lithium iron phosphate battery materials, characterized in that: The following steps are involved: 1) acid leaching the waste lithium iron phosphate battery material, controlling the pH value of the reaction solution to be less than 0.8 at the end of the reaction, to obtain a waste lithium iron phosphate battery material leachate, wherein the waste lithium iron phosphate battery material leachate contains copper and iron; 2) extracting the leachate with an extractant to obtain a copper-loaded extractant and a raffinate having a pH value less than 0.8; and 3) washing and stripping the copper-loaded extractant obtained in step 2) in sequence to obtain a copper stripping solution and a stripping extractant; Wherein, the extractant comprises a chelating resin of formula (I) and formula (II): (AND) (II) in: P is the base resin; R1 and R2 are each independently a nitrogen-containing heterocyclic group; R3 is an acyl group or hydrogen; and M is ( ) x , wherein n and m are independently integers of 2-10; x is 0, The nitrogen-containing heterocyclic groups R1 and R2 are each independently selected from the following groups: 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 、 , When R3 is an acyl group, R3 is -(CO)R4 or -CH2(CO)R4, wherein R4 is a straight chain or branched chain alkyl group with a carbon chain number of 1-5, or -N-(R5)2, wherein R5 is a straight chain or branched chain alkyl group with a carbon chain number of 1-5.

2. The method according to claim 1, characterized in that The base resin P is selected from polystyrene resin, copolymer of styrene and divinylbenzene, phenolic resin polymer, polyacrylic resin and silicon-based resin.

3. The method according to claim 1 or 2, characterized in that The chelating resin of formula (I) has a structure selected from the following: 、 、 、 、 、 ， and / or The chelating resin of formula (II) has a structure selected from the following: 、 、 、 、 、 、 、 、 、 ， Wherein P is independently selected from polystyrene resin, copolymer of styrene and divinylbenzene, phenolic resin polymer, polyacrylic resin and silicon-based resin.

4. The method according to claim 1, wherein The pH value of the waste lithium iron phosphate battery material leachate is 0.1-0.7; And / or, the pH value of the raffinate in step 1) is ≤0.

7.

5. The method according to claim 1, wherein Step 1) The extraction is a single-stage, or multi-stage series and / or parallel extraction, and the number of extraction stages is 1-10; And / or, the extraction flow rate is 1-25 Bv / h.

6. The method according to claim 1, characterized in that Step 3) The stripping agent used in the stripping is any one of an inorganic acid solution, ammonia water, and disodium EDTA, or a combination of disodium EDTA and an inorganic acid solution or ammonia water, wherein the inorganic acid solution includes hydrochloric acid and / or sulfuric acid, and the concentration of the sulfuric acid is 1-6 mol / L; the concentration of the ammonia water is 1-6 mol / L; and the concentration of the disodium EDTA is 0.05-0.3 mol / L. And / or, the stripping flow rate is 0.5-5 Bv / h.

7. The method according to claim 1, characterized in that Step 3) the number of washing stages is 1-10; and / or, the washing flow rate is 1-25 Bv / h; And / or, the pH value of the washing liquid used for washing is 0.1-1.

2.

8. The method according to claim 1, characterized in that Step 3) the extractant after stripping is regenerated and recycled, and the pH value of the regenerated water is controlled to be 0.2-3; The regeneration agent used in the regeneration is water.

9. The method according to claim 1, wherein The copper stripping solution is directly or concentrated before electrowinning to prepare metallic copper or iron powder is added to prepare sponge copper.

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