Method for efficiently recycling lithium and manganese elements in lithium iron manganese phosphate battery material

Abstract

The invention discloses a method for efficiently recycling lithium and manganese elements in a lithium manganese iron phosphate battery material, which comprises the following detailed process flows: discharging a waste lithium manganese iron phosphate battery, disassembling and sorting to obtain lithium manganese iron phosphate positive electrode powder, adding ammonium sulfate into the positive electrode powder, uniformly mixing, and roasting under an oxidation condition to obtain a roasted material; performing water leaching on the roasted material to selectively leach out lithium and manganese, adding ammonium carbonate into a manganese-containing lithium sulfate solution to generate manganese carbonate precipitate, and re-dissolving the manganese carbonate to obtain refined manganese carbonate which is used as a manganese source for preparing lithium iron manganese phosphate; the filtrate after filtration is a lithium sulfate solution, the solution is neutralized with ammonia water to remove impurities to obtain a pure lithium sulfate solution, ammonium carbonate is added into the lithium sulfate solution to prepare a lithium carbonate finished product, and the prepared lithium carbonate mother liquor is subjected to evaporative crystallization to prepare an ammonium sulfate byproduct.

Description

Technical Field

[0001] The invention belongs to the field of resource utilization of solid wastes, and specifically relates to a method for efficiently recovering lithium and manganese elements in lithium iron manganese phosphate battery materials. Background Art

[0002] As an important cathode material for lithium-ion batteries, lithium iron manganese phosphate has attracted extensive attention in recent years because of its high energy density, good cycle performance and high safety. However, with the mass production and application of lithium-ion batteries, the treatment and recycling of waste batteries have become increasingly prominent. Lithium and manganese, as the main components of lithium iron manganese phosphate, are both important strategic resources. Lithium resources are unevenly distributed around the world, and the cost of mining and refining is high. Although manganese is relatively abundant, its high-quality and low-cost supply also faces challenges. Therefore, recovering lithium and manganese elements from waste lithium iron manganese phosphate batteries is of great significance for alleviating resource shortages, reducing production costs, and promoting sustainable development.

[0003] Currently reported methods for recovering valuable metals from waste lithium manganese iron phosphate batteries include pyrometallurgy and wet recovery. These methods can achieve the extraction of lithium elements to a certain extent, but they still face huge challenges, mainly including: complex battery structure, diverse components, difficulty in recycling, possible secondary pollution during the recycling process, and high recycling costs. In this context, the development of efficient and environmentally friendly lithium manganese iron phosphate recovery technology to improve the recovery rate of lithium and manganese elements will become the focus of industry attention. It has been reported in the literature that ammonium sulfate-assisted roasting can selectively extract lithium elements from lithium iron phosphate positive electrode materials. Ammonium sulfate-assisted roasting achieves rapid delithiation of lithium iron phosphate and converts lithium iron phosphate into iron phosphate in an air atmosphere, converting 98% of lithium into soluble lithium sulfate. Summary of the invention

[0004] The present invention provides a method for efficiently recovering lithium and manganese elements in lithium iron manganese phosphate battery materials. Specifically, the present invention proposes that LiMn1-xFexPO4 positive electrode powder adopts oxalic acid as a leaching agent to leach lithium and phosphorus in the positive electrode powder, neutralizes and concentrates the oxalic acid leaching solution, adds NaOH, and supplements phosphoric acid to adjust the pH to prepare lithium phosphate; the invention is for waste LiMn 1-x Fe x The recycling of PO4 positive electrode powder provides a new idea.

[0005] The present invention is achieved through the following technical steps: 1. After the waste lithium iron manganese phosphate batteries are discharged, they are disassembled and sorted to obtain lithium iron manganese phosphate positive electrode powder; 2. Add 1-2 times the mass of ammonium sulfate solid to the lithium manganese iron phosphate positive electrode powder, mix evenly, place in a quartz boat, and react at 300-700°C in a tube furnace for 2-4 hours to obtain ammonium sulfate auxiliary roasting material; 3. Add pure water to the ammonium sulfate-assisted roasting material for water leaching, with a liquid-to-solid ratio of 5-10:1, add sulfuric acid to adjust the pH to 3-5, react at 20-60°C for 30-120 min, and filter to obtain the water leaching liquid and water leaching residue.

[0006] 4. After the water extract is adjusted to pH=5.5-7.5 with ammonia water, ammonium carbonate with n(Mn):n(NH42CO3)=1.3-1.6 is added to precipitate the manganese in the water extract. The filter residue is manganese carbonate precipitate and the filtrate is lithium sulfate solution; 5. After the obtained manganese carbonate precipitate is dissolved with sulfuric acid, the solution is adjusted to pH=5.5-7.5 with ammonia water and ammonium carbonate with n(Mn):n(NH42CO3)=1.1-1.6 is added again to prepare a refined manganese carbonate precipitate, which is used for preparing the manganese source of lithium manganese iron phosphate.

[0007] 6. The lithium sulfate solution is neutralized to pH=8.5-9.5 with ammonia water, and the iron and phosphorus impurities in the solution are removed to obtain a pure lithium sulfate solution; 7. Add ammonium carbonate solid with n(Li):n(NH42CO3)=1.1-1.3 to the pure lithium sulfate solution, and react at 25-60°C for 1-3 h to obtain lithium carbonate product and prepare lithium carbonate mother liquor; 8. The refined manganese carbonate mother liquor is mixed with the lithium carbonate mother liquor, evaporated, cooled and crystallized at high temperature to prepare ammonium sulfate by-product.

[0008] Beneficial effects of the present invention: 1. Lithium manganese iron phosphate is calcined with ammonium sulfate, which can convert more than 98% of lithium into lithium sulfate, which is more conducive to the leaching of lithium elements; 2. The leaching process of the material after ammonium sulfate auxiliary roasting through the water leaching system is simple, and the lithium and manganese leaching rates are high.

[0009] 3. The ammonium sulfate-assisted roasting material water leachate is a manganese-containing lithium sulfate solution. By adding ammonium carbonate, the manganese element can be recovered separately. Ammonium carbonate can be further added to the lithium sulfate solution to recover the lithium element separately. The remaining liquid can be concentrated to recover all sulfur and ammonium elements, and finally achieve closed-loop recovery of all elements in lithium iron manganese phosphate. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0011] The present invention is further described below in conjunction with the embodiments, but the present invention is not limited in any way. Any changes or substitutions made based on the teachings of the present invention belong to the protection scope of the present invention.

[0012] A method for efficiently recovering lithium and manganese elements from lithium iron manganese phosphate battery materials comprises the following steps; (1) After the waste lithium manganese iron phosphate batteries are discharged, they are disassembled and sorted to obtain lithium manganese iron phosphate positive electrode powder; (2) Add 1-2 times the mass of ammonium sulfate solid to the lithium manganese iron phosphate positive electrode powder, mix well, place in a quartz boat, and react at 300-700°C in a tube furnace for 2-4 hours to obtain ammonium sulfate auxiliary roasting material; (3) adding pure water to the ammonium sulfate auxiliary roasting material for water leaching, with a liquid-to-solid ratio of 5-10:1, adding sulfuric acid to adjust the pH to 3-5, reacting at 20-60°C for 30-120 min, and filtering to obtain the water leaching liquid and water leaching residue; (4) After the water extract is adjusted to pH 5.5-7.5 with ammonia water, ammonium carbonate with n(Mn):n(NH42CO3)=1.3-1.6 precipitates the manganese in the water extract, the filter residue is manganese carbonate precipitate, and the filtrate is lithium sulfate solution; (5) After the obtained manganese carbonate precipitate is dissolved in sulfuric acid, the solution is adjusted to pH = 5.5-7.5 with ammonia water, and ammonium carbonate with n(Mn):n(NH42CO3)=1.1-1.6 is added again to prepare a refined manganese carbonate precipitate, which is used for preparing the manganese source of lithium manganese iron phosphate; (6) The lithium sulfate solution is neutralized to pH = 8.5-9.5 with ammonia water, and the iron and phosphorus impurities in the solution are removed to obtain a pure lithium sulfate solution; (7) Add ammonium carbonate solid with n(Li):n(NH42CO3)=1.1-1.3 to pure lithium sulfate solution, and react at 25-60°C for 1-3 h to obtain lithium carbonate product and prepare lithium carbonate mother liquor; (8) The refined manganese carbonate mother liquor is mixed with the lithium carbonate mother liquor, evaporated at high temperature, cooled and crystallized to obtain ammonium sulfate by-product.

[0013] Example 1 (1) After the waste lithium manganese iron phosphate batteries are discharged, they are disassembled and sorted to obtain lithium manganese iron phosphate positive electrode powder; (2) adding 2 times the mass of ammonium sulfate solid to the lithium manganese iron phosphate positive electrode powder obtained in step (1), mixing evenly, placing in a quartz boat, and reacting at 300-700° C. in a tube furnace for 2-4 h to obtain an ammonium sulfate auxiliary roasting material; (3) The ammonium sulfate-assisted roasting material obtained in step (2) is added into pure water for water leaching, with a liquid-to-solid ratio of 10:1, and a small amount of sulfuric acid is added to adjust the pH to 3. The mixture is reacted at 60°C for 30-120 min, and the water leaching liquid and water leaching residue are obtained by filtering.

[0014] (4) The water extract obtained in step (3) is adjusted to pH 5.5-7.5 with ammonia water, and ammonium carbonate is added in a ratio of n(Mn):n(NH42CO3)=1.3:1 to precipitate manganese in the water extract, the filter residue is manganese carbonate precipitate, and the filtrate is lithium sulfate solution; (5) The manganese carbonate precipitate obtained in step (4) is redissolved in sulfuric acid, the solution is adjusted to pH 5.5-7.5 with ammonia water, and ammonium carbonate with n(Mn)=1.1 is added to obtain a refined manganese carbonate product, which is used for preparing the manganese source of lithium manganese iron phosphate; (6) neutralizing the lithium sulfate solution obtained in step (4) with ammonia water to a pH of 8.5-9.5, and removing iron and phosphorus impurities in the solution to obtain a pure lithium sulfate solution; (7) adding the pure lithium sulfate solution obtained in step (6) to solid ammonium carbonate with n(Li)=1.1, and reacting at 25-60° C. for 1-3 h to obtain a lithium carbonate product and prepare a lithium carbonate mother liquor; (8) The refined manganese carbonate mother liquor obtained in step (5) and the lithium carbonate mother liquor obtained in step (7) are concentrated, cooled and crystallized at high temperature to prepare ammonium sulfate.

[0015] (9) In the entire process of step (2-3), the Li extraction rate is ≥98.5%, the Fe loss is ≤3%, the P loss is ≤5%, and the Mn extraction rate is ≥98.7%; (10) In the process of step (4), the Mn precipitation rate is ≥ 98.5%, and the Li loss is ≤ 7.6%; (11) In the process of step (7), the Li precipitation rate is ≥ 97.9%; Example 2 (1) After the waste lithium manganese iron phosphate batteries are discharged, they are disassembled, sorted and crushed to obtain lithium manganese iron phosphate positive electrode powder; (2) adding 1-2 times the mass of ammonium sulfate solid to the lithium manganese iron phosphate positive electrode powder obtained in step (1), mixing evenly, placing in a quartz boat, and reacting at 400° C. for 2-4 h in a tube furnace to obtain an ammonium sulfate auxiliary roasting material; (3) The ammonium sulfate-assisted roasting material obtained in step (2) is added into pure water for water leaching, with a liquid-to-solid ratio of 10:1, sulfuric acid is added to adjust the pH to 4.5, the reaction is carried out at 60°C for 30-120 min, and the water leaching liquid and water leaching residue are obtained by filtering.

[0016] (4) The water extract obtained in step (3) was adjusted to pH = 7.5 with ammonia water, and ammonium carbonate was added in a ratio of n(Mn):n(NH42CO3)=1.6:1 to precipitate manganese in the water extract, the filter residue was manganese carbonate precipitate, and the filtrate was lithium sulfate solution; (5) The manganese carbonate precipitate obtained in step (4) is redissolved in sulfuric acid, the solution is adjusted to pH = 7.5 with ammonia water, and ammonium carbonate with n (Mn) = 1.1-1.6 is added to obtain a refined manganese carbonate product, which is used for preparing the manganese source of lithium manganese iron phosphate; (6) neutralizing the lithium sulfate solution obtained in step (4) to a pH of 9.5 with aqueous ammonia, and removing iron and phosphorus impurities in the solution to obtain a pure lithium sulfate solution; (7) Adding the pure lithium sulfate solution obtained in step (6) to solid ammonium carbonate with n(Li):n(NH42CO3)=1.1-1.3, reacting at 60°C for 1-3 h to obtain a lithium carbonate product and prepare a lithium carbonate mother liquor; (8) The refined manganese carbonate mother liquor obtained in step (5) and the lithium carbonate mother liquor obtained in step (7) are concentrated, cooled and crystallized at high temperature to prepare ammonium sulfate.

[0017] (9) In the entire process of step (2-3), the Li extraction rate is ≥98.6%, the Fe loss is ≤3%, the P loss is ≤10%, and the Mn extraction rate is ≥99.1%; (10) In the process of step (4), the Mn precipitation rate is ≥ 99.2%, and the Li loss is ≤ 5.3%; (11) In the process of step (7), the Li precipitation rate is ≥ 98.5%; Example 3 (1) After the waste lithium manganese iron phosphate batteries are discharged, they are disassembled, sorted and crushed to obtain lithium manganese iron phosphate positive electrode powder; (2) adding 1-2 times the mass of ammonium sulfate solid to the lithium manganese iron phosphate positive electrode powder obtained in step (1), mixing evenly, placing in a quartz boat, and reacting in a tube furnace at 300-700° C. for 4 h to obtain an ammonium sulfate auxiliary roasting material; (3) The ammonium sulfate-assisted roasting material obtained in step (2) is added into pure water for water leaching, with a liquid-to-solid ratio of 5-10:1, and a small amount of sulfuric acid is added to adjust the pH to 3.5. The mixture is reacted at 20-60°C for 120 min, and filtered to obtain a primary water leaching liquid and a primary water leaching residue.

[0018] (4) The pH value of the primary water extract obtained in step (3) is adjusted to 7.5 by using ammonia water, and then ammonium carbonate is added in a ratio of n(Mn):n(NH42CO3)=1.4:1 to precipitate the manganese in the primary water extract, the filter residue is manganese carbonate precipitate, and the filtrate is lithium sulfate solution; (5) The manganese carbonate precipitate obtained in step (4) is redissolved in sulfuric acid, the solution is adjusted to pH = 7.5 with ammonia water, and ammonium carbonate with n (Mn) = 1.1-1.6 is added to obtain a refined manganese carbonate product, which is used for preparing the manganese source of lithium manganese iron phosphate; (6) neutralizing the lithium sulfate solution obtained in step (4) to a pH of 8.5-9.5 with aqueous ammonia, and removing iron and phosphorus impurities in the solution to obtain a pure lithium sulfate solution; (7) Adding the pure lithium sulfate solution obtained in step (6) to solid ammonium carbonate with n(Li):n(NH42CO3)=1.1-1.3, reacting at 25-60°C for 2 h to obtain a lithium carbonate product and prepare a lithium carbonate mother liquor; (8) The refined manganese carbonate mother liquor obtained in step (5) and the lithium carbonate mother liquor obtained in step (7) are concentrated, cooled and crystallized at high temperature to prepare ammonium sulfate solid.

[0019] (9) In the entire process of step (2-3), the Li extraction rate is ≥99.3%, the Fe loss is ≤1.5%, the P loss is ≤8%, and the Mn extraction rate is ≥99.3%; (10) In the process of step (4), the Mn precipitation rate is ≥ 98.5%, and the Li loss is ≤ 4.5%; (11) In the process of step (7), the Li precipitation rate is ≥ 97.5%.

Claims

1. A method for efficiently recovering lithium and manganese elements from lithium iron manganese phosphate battery materials, characterized in that The steps include: (1) After the waste lithium manganese iron phosphate batteries are discharged, they are disassembled and sorted to obtain lithium manganese iron phosphate positive electrode powder; (2) Add 1-2 times the mass of ammonium sulfate solid to the lithium manganese iron phosphate positive electrode powder, mix well, place in a quartz boat, and react at 300-700°C in a tube furnace for 2-4 hours to obtain ammonium sulfate auxiliary roasting material; (3) adding pure water to the ammonium sulfate auxiliary roasting material for water leaching, with a liquid-to-solid ratio of 5-10:1, adding sulfuric acid to adjust the pH to 3-5, reacting at 20-60°C for 30-120 min, and filtering to obtain the water leaching liquid and water leaching residue; (4) After the water extract is adjusted to pH 5.5-7.5 with ammonia water, ammonium carbonate is added at a ratio of n(Mn):n(NH42CO3)=1.3-1.6:1 to precipitate the manganese in the water extract. The filter residue is manganese carbonate precipitate and the filtrate is lithium sulfate solution; (5) After the obtained manganese carbonate precipitate is dissolved in sulfuric acid, the solution is adjusted to pH = 5.5-7.5 with ammonia water, and ammonium carbonate with n(Mn):n(NH42CO3)=1.1-1.6 is added again to prepare a refined manganese carbonate precipitate, which is used for preparing the manganese source of lithium manganese iron phosphate; (6) The lithium sulfate solution is neutralized to pH = 8.5-9.5 with ammonia water, and the iron and phosphorus impurities in the solution are removed to obtain a pure lithium sulfate solution; (7) Add ammonium carbonate solid with n(Li):n(NH42CO3)=1.1-1.3 to pure lithium sulfate solution, and react at 25-60°C for 1-3 h to obtain lithium carbonate product and prepare lithium carbonate mother liquor; (8) The refined manganese carbonate mother liquor is mixed with the lithium carbonate mother liquor, evaporated at high temperature, cooled and crystallized to prepare ammonium sulfate by-product.

Images