Use of iridium chloride bridging dimers

Abstract

The application discloses application of iridium-chlorine bridge dimer, and recovery of iron phosphate in waste lithium iron phosphate powder. The iridium-chlorine bridge dimer is used to generate singlet oxygen under light irradiation, to form a metal complex with an organic ligand, and to selectively strengthen oxidation of lithium iron phosphate material, so that the lithium iron phosphate material is converted into insoluble iron phosphate precipitate, and the purpose of efficient separation of components and recovery of products is achieved. The recovery rate of the iron phosphate in the waste lithium iron phosphate powder is higher than 96% by using the iridium-chlorine bridge dimer, and the purity of the recovered iron phosphate in the waste lithium iron phosphate powder is higher than 98%.

Description

Technical Field

[0001] This invention relates to the field of resource recycling technology, and in particular to the application of an iridium-chlorine bridged dimer. Background Technology

[0002] Lithium iron phosphate (LFP), as a novel cathode material for lithium-ion batteries, is widely used in energy storage, communication base stations, and new energy vehicles due to its advantages such as good safety performance, excellent cycle performance, and long service life. With the rapid development of new energy vehicles and the increasing number of retired LFP batteries in my country, recycling retired LFP batteries has become a significant practical issue. Furthermore, LFP batteries are rich in iron phosphate, and from the perspective of the recycling market and resource recycling, achieving high-value recovery of iron phosphate from waste LFP batteries has certain economic benefits. However, current recycling of waste LFP power batteries mainly relies on wet processes, which use a combination of acid and oxidants to convert the components in the pretreated waste LFP active material into water-soluble Li salts and insoluble FePO4, thereby achieving effective recovery of each component. However, this method suffers from problems such as high acid and alkali consumption and low yield and purity of the recycled products.

[0003] For example, a traditional method involves mixing low-concentration inorganic acids with waste lithium iron phosphate powder and reacting it under high temperature and oxygen-rich conditions to convert it into insoluble iron phosphate leaching residue and water-soluble Li salts. This method can achieve Li + The FePO4 was separated and the corresponding products were recovered separately, but some Fe remained in the acidic system. 3+ and PO4 3- Dissolution and the subsequent neutralization of residual acid will cause some Li to be released. + The entrainment loss results in low yield and purity of recovered Li₂CO₃. Another method involves reacting waste lithium iron phosphate powder with ferric salts and an oxidant to obtain lithium solution and leaching residue containing ferric phosphate and ferric salts. The lithium solution is then pH-adjusted and carbonates are added to obtain crude lithium carbonate. The leaching residue containing ferric phosphate and ferric salts is washed with dilute acid to recover the ferric phosphate and ferric salts. While this method allows for the separate recovery of Li and FePO₄, the operation is cumbersome, and the component separation is incomplete, resulting in low recovery rates of Li and FePO₄ and low product purity. The highest recovery rate of lithium recovered in the form of lithium carbonate is only 95.12%. Summary of the Invention

[0004] Therefore, in order to improve the purity and yield of iron phosphate in waste lithium iron phosphate powder, it is necessary to provide an application of iridium chloride bridged dimer.

[0005] This invention provides an application of an iridium chloride bridged dimer, which is used to recycle iron phosphate from waste lithium iron phosphate powder.

[0006] In one embodiment, the general structural formula of the iridium-chlorine bridged dimer is:

[0007]

[0008] R1 and R2 are each independently selected from A is selected from any of the following groups: Where: * indicates a connection or fusion site.

[0009] X1 to X4 are each independently selected from H, F, Cl or Br. Each time Y1 appears, it is independently selected from N or CR3. Each time R3 appears, it is independently selected from -H, -D or a straight-chain alkyl group having 1 to 5 C atoms.

[0010] In one embodiment, the structure of the iridium-chlorine bridged dimer is as shown in one of formulas (1-1) and (1-4):

[0011]

[0012] In one embodiment, the chemical composition of the waste lithium iron phosphate powder, by weight percentage, includes: 2%–5% lithium, 25%–35% iron, 15%–25% phosphorus, 0.1%–0.5% aluminum, 0.01%–0.1% copper, 0.0001%–0.01% manganese, 0.0001%–0.01% cobalt, 35%–42% oxygen, 5%–12% carbon, 0.0001%–0.01% nickel, and 0.0001%–0.01% fluorine.

[0013] In one embodiment, the step of recycling iron phosphate from waste lithium iron phosphate powder includes:

[0014] S100: The iridium chloride bridged dimer, the first organic solvent, the organic ligand, water, and the waste lithium iron phosphate powder are mixed, irradiated under visible light, and filtered to prepare the first solid and the first solution.

[0015] S110: Mix the first solid and the second organic solvent, filter, and prepare the second solid and the second solution.

[0016] S120: Mix the second solid, inorganic acid, and water, filter, and prepare the third solution.

[0017] S130: The pH of the third solution is adjusted to 1-2 by a pH adjuster, the reaction is carried out, the solution is filtered, and the filter residue is recovered.

[0018] In one embodiment, the step of recycling iron phosphate from waste lithium iron phosphate powder has one or more of the following features:

[0019] (1) The organic ligand is selected from one or more of imidazole organic ligands, quinoline organic ligands and amino acid organic ligands;

[0020] (2) The first organic solvent is selected from one or more of dichloromethane, chloroform, methanol, ethanol and acetonitrile;

[0021] (3) In step S100, the molar ratio of the iridium chloride bridge dimer, the organic ligand and the waste lithium iron phosphate powder is (0.6-1.5):(1.2-3.0):1, and the mass ratio of the first solvent, water and the waste lithium iron phosphate powder is (1-3):(5-12):1.

[0022] (4) Visible light irradiation conditions include: irradiation at a temperature of 5℃~40℃ for 5h~20h;

[0023] (5) The second organic solvent is selected from one or more of dichloromethane, chloroform, methanol, ethanol, tetrahydrofuran, and acetonitrile;

[0024] (6) The mass ratio of the second solvent to the waste lithium iron phosphate powder is (2-8):1;

[0025] (7) The inorganic acid is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid;

[0026] (8) In step S120, the mass ratio of the inorganic acid, water and the waste lithium iron phosphate powder is (1-3):(3-8):1;

[0027] (9) The pH adjuster is selected from one or more of concentrated ammonia, ammonium carbonate and ammonium bicarbonate;

[0028] (10) In step S130, the reaction time is 4 hours to 12 hours and the reaction temperature is 40℃ to 100℃.

[0029] In one embodiment, the step of recycling iron phosphate from waste lithium iron phosphate powder has one or more of the following features:

[0030] (1) The amino acid organic ligands are selected from one or more of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, and histidine.

[0031] (2) The imidazole organic ligand is selected from one or more of imidazole, benzimidazole and 2-ethylbenzimidazole;

[0032] (3) The quinoline organic ligands are selected from one or more of tetrahydroquinoline and tetrahydroisoquinoline;

[0033] (4) The wavelength range of visible light is 450nm~550nm.

[0034] In one embodiment, the step of recycling iron phosphate from waste lithium iron phosphate powder further includes a step of recycling lithium chloride:

[0035] Evaporate the first solution, filter, wash the filter residue with an organic solvent, and dry.

[0036] In one embodiment, the step of recycling iron phosphate from waste lithium iron phosphate powder further includes the step of recycling the iridium chloride bridged dimer:

[0037] The second solution, strong acid, and water are mixed to prepare a mixture; the organic layer solution in the mixture is extracted; and the organic layer solution is evaporated.

[0038] The strong acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, formic acid, trifluoroacetic acid, and trifluoromethanesulfonic acid.

[0039] In one embodiment, the step of recovering the iridium chloride bridged dimer has at least one of the following characteristics:

[0040] (1) The mixture further includes a metal chloride, which is selected from one or more of sodium chloride, potassium chloride, magnesium chloride, calcium chloride and zinc chloride;

[0041] (2) The mass ratio of the waste lithium iron phosphate, the strong acid and water is 1:(0.5-5):(1-3).

[0042] This invention utilizes an iridium chloride-bridged dimer that generates singlet oxygen under light, forming a highly photosensitizing metal complex with organic ligands. This complex selectively enhances the oxidation of lithium iron phosphate materials, converting them into insoluble iron phosphate precipitates, thus achieving efficient separation of components and product recovery. The recovery rate of iron phosphate from waste lithium iron phosphate powder using the iridium chloride-bridged dimer is higher than 96%, and the purity of the iron phosphate in the recovered waste lithium iron phosphate powder is consistently higher than 98%.

[0043] Furthermore, this invention can further recover lithium from waste lithium iron phosphate powder in the form of lithium chloride, and recover iridium chloride bridged dimers for reuse. The overall recycling process has the advantages of simple operation, low acid and alkali consumption and oxidant consumption, green and environmentally friendly, controllable quality and easy industrialization, which can generate good economic and social benefits and has broad prospects for industrial application. Attached Figure Description

[0044] Figure 1XRD pattern of anhydrous lithium chloride recovered in Example 1.

[0045] Figure 2 XRD patterns of the recovered ferric phosphate sample and the standard sample in Example 1. Detailed Implementation

[0046] This invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this invention. Of course, they are merely examples and are not intended to limit the invention. Furthermore, reference numerals and / or letters may be repeated in different instances. Such repetition is for the purpose of simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or settings discussed.

[0047] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of the invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified. In the description of the present invention, "a number" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0048] Unless otherwise specified, all percentages, fractions, and ratios are calculated based on the total mass of the compositions of the present invention. Unless otherwise specified, all masses of the listed ingredients give an amount of active substance and therefore do not include solvents or byproducts that may be present in commercially available materials. The term "percentage by mass" may be expressed by the symbol "%".

[0049] The terms “comprising,” “including,” “containing,” “having,” “comprising,” or other variations thereof are intended to cover non-closed inclusion, and no distinction is made between these terms. The term “comprising” means that other steps and ingredients may be added without affecting the final result. The term “comprising” also includes the terms “consisting of” and “substantially composed of.” The compositions and methods / processes of the present invention comprise, consist of, and substantially consist of the essential elements and limitations described herein, as well as any additional or optional ingredients, components, steps, or limitations described herein. No distinction is made between the terms “efficacy,” “performance,” “effect,” and “potency” herein.

[0050] The terms "preferred," "more preferably," etc., used in this invention refer to embodiments of the invention that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this invention.

[0051] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0052] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the specification of this invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0053] This invention provides an application of an iridium chloride bridged dimer, which is used to recycle iron phosphate from waste lithium iron phosphate powder.

[0054] In a specific example, the general structural formula of the iridium-chlorine bridged dimer is:

[0055]

[0056] R1 and R2 are each independently selected from A is selected from any of the following groups: Where: * indicates a connection or fusion site.

[0057] X1 to X4 are each independently selected from H, F, Cl or Br. Each time Y1 appears, it is independently selected from N or CR3. Each time R3 appears, it is independently selected from -H, -D or a straight-chain alkyl group having 1 to 5 C atoms.

[0058] In a specific example, the structure of the iridium-chlorine bridged dimer is shown in one of the formulas (1-1) and (1-4):

[0059]

[0060]

[0061] Understandably, the iridium-chloride bridged dimers of formulas (1-1) to (1-4) are, in order, 2-phenylpyridine iridium dichloride bridge, 2-(2,4-difluorophenyl)pyridine iridium dichloride bridge, 2-phenylquinoline iridium dichloride bridge, and 2-phenylisoquinoline iridium dichloride bridge.

[0062] In a specific example, the chemical composition of waste lithium iron phosphate powder, by weight percentage, includes: 2%–5% lithium, 25%–35% iron, 15%–25% phosphorus, 0.1%–0.5% aluminum, 0.01%–0.1% copper, 0.0001%–0.01% manganese, 0.0001%–0.01% cobalt, 35%–42% oxygen, 5%–12% carbon, 0.0001%–0.01% nickel, and 0.0001%–0.01% fluorine.

[0063] In a specific example, the step of recycling iron phosphate from waste lithium iron phosphate powder includes steps S100 to S130.

[0064] Step S100: Mix iridium chloride bridged dimer, first organic solvent, organic ligand, water and waste lithium iron phosphate powder, irradiate under visible light, filter, and prepare first solid and first solution.

[0065] In a specific example, the organic ligand is selected from one or more of imidazole organic ligands, quinoline organic ligands, and amino acid organic ligands.

[0066] Furthermore, the amino acid organic ligands are selected from one or more of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, and histidine.

[0067] The imidazole organic ligands are selected from one or more of imidazole, benzimidazole, and 2-ethylbenzimidazole;

[0068] Quinoline organic ligands are selected from one or more of tetrahydroquinoline and tetrahydroisoquinoline.

[0069] In one specific example, the first organic solvent is selected from one or more of dichloromethane, chloroform, methanol, ethanol, and acetonitrile.

[0070] In a specific example, the molar ratio of iridium chloride bridged dimer, organic ligand, and waste lithium iron phosphate powder is (0.6–1.5):(1.2–3.0):1, and the mass ratio of the first solvent, water, and waste lithium iron phosphate powder is (1–3):(5–12):1.

[0071] In a specific example, the conditions for visible light irradiation include irradiation at a temperature of 5℃ to 40℃ for 5 to 20 hours.

[0072] Preferably, the visible light irradiation conditions include irradiation at a temperature of 30°C to 40°C for 6 to 12 hours.

[0073] Understandably, the wavelengths of the visible light mentioned above are 450nm to 500nm.

[0074] Step S110: Mix the first solid and the second organic solvent, filter, and prepare the second solid and the second solution.

[0075] In one specific example, the second organic solvent is selected from one or more of dichloromethane, chloroform, methanol, ethanol, tetrahydrofuran, and acetonitrile.

[0076] Furthermore, the mass ratio of the second solvent to the waste lithium iron phosphate powder is (2-8):1.

[0077] Step S120: Mix the second solid, inorganic acid and water, filter, and prepare the third solution.

[0078] In a specific example, the inorganic acid is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid, and phosphoric acid.

[0079] In a specific example, the mass ratio of inorganic acid, water, and waste lithium iron phosphate powder is (1-3):(3-8):1.

[0080] Step S130: Adjust the pH of the third solution to 1-2 with a pH adjuster to carry out the reaction, filter, and recover the filter residue.

[0081] Preferably, in step S130, the pH value is adjusted to 1.5-2, and the pH adjuster reacts with the third solution in a neutralization reaction.

[0082] In one specific example, the pH adjuster is selected from one or more of concentrated ammonia, ammonium carbonate, and ammonium bicarbonate.

[0083] In a specific example, in step S130, the reaction time is 4 to 12 hours and the reaction temperature is 40°C to 100°C.

[0084] Understandably, the process of recycling iron phosphate from waste lithium iron phosphate powder also includes the process of recycling lithium chloride:

[0085] Evaporate the first solution, filter, wash the filter residue with an organic solvent, and dry.

[0086] Preferably, using acetonitrile as the organic solvent can further improve the recovery rate of lithium chloride.

[0087] In a specific example, the process of recycling iron phosphate from waste lithium iron phosphate powder also includes the step of recycling iridium chloride bridged dimers:

[0088] A second solution, a strong acid, and water are mixed to prepare a mixture. The organic layer solution in the mixture is extracted and then evaporated.

[0089] The strong acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, formic acid, trifluoroacetic acid, and trifluoromethanesulfonic acid.

[0090] Understandably, the mass of hydrochloric acid is 50%–200% of the mass of waste lithium iron phosphate powder; the mass of sulfuric acid is 80%–300% of the mass of waste lithium iron phosphate powder; the mass of nitric acid is 100%–500% of the mass of waste lithium iron phosphate powder; the mass of formic acid is 80%–350% of the mass of waste lithium iron phosphate powder; the mass of trifluoroacetic acid is 100%–250% of the mass of waste lithium iron phosphate powder; and the mass of trifluoromethanesulfonic acid is 150%–300% of the mass of waste lithium iron phosphate powder.

[0091] In one specific example, the mixture also includes a metal chloride selected from one or more of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, and zinc chloride.

[0092] Furthermore, the mass of the metal chloride is 40% to 200% of the mass of the waste lithium iron phosphate powder.

[0093] In a specific example, the mass ratio of waste lithium iron phosphate, strong acid, and water is 1:(0.5-5):(1-3).

[0094] This invention utilizes an iridium chloride-bridged dimer that generates singlet oxygen under light, forming a highly photosensitizing metal complex with organic ligands. This complex selectively enhances the oxidation of lithium iron phosphate materials, converting them into insoluble iron phosphate precipitates, thus achieving efficient separation of components and product recovery. The recovery rate of iron phosphate from waste lithium iron phosphate powder using the iridium chloride-bridged dimer is higher than 96%, and the purity of the iron phosphate in the recovered waste lithium iron phosphate powder is consistently higher than 98%.

[0095] Furthermore, this invention can further recover lithium from waste lithium iron phosphate powder in the form of lithium chloride, and recover iridium chloride bridged dimers for reuse. The overall recycling process has the advantages of simple operation, low acid and alkali consumption and oxidant consumption, green and environmentally friendly, controllable quality and easy industrialization, which can generate good economic and social benefits and has broad prospects for industrial application.

[0096] The application of the iridium chloride bridged dimer of the present invention will be further described in detail below with reference to specific embodiments. Unless otherwise specified, all raw materials involved in the following specific embodiments are commercially available.

[0097] The elemental composition of the waste lithium iron phosphate powder in the following embodiments is shown in the table below:

[0098]

[0099] Example 1

[0100] 400g of waste lithium iron phosphate powder, 2500g of 2-phenylquinoline iridium dichlorobridge, 400g of benzimidazole, 800g of methanol, and 2500g of pure water were mixed. The mixture was reacted at 30℃ under 500nm LED light for 6.0h. The methanol was removed by vacuum concentration, and the solid and liquid phases were separated to obtain a first solid and a first lithium solution. The lithium solution was evaporated and concentrated, and the solid and liquid phases were separated again. The solution was washed with acetonitrile and dried to obtain anhydrous lithium chloride. Yield: 96.8%; Purity: 98.5%.

[0101] The first solid was dissolved in 1200g of dichloromethane, and the solid and liquid were separated to obtain a second solid, ferrophosphorus slag, and a second organic solution. The organic solution was extracted with 240g of hydrochloric acid and 450g of water, and the organic layer was collected. The collected organic layer was evaporated to dryness to recover 2-phenylquinoline iridium dichlorobridge. Yield: 99.2%; Purity: 99.5%.

[0102] Ferrophosphate slag was mixed with 520g hydrochloric acid and 2000g pure water and reacted. Solid-liquid separation was performed to obtain carbon slag and a third liquid acid leaching solution. The pH of the acid leaching solution was adjusted to 1.8 using ammonium carbonate, and the reaction was carried out at 70℃ for 6.0h. Solid-liquid separation was then performed, followed by washing, drying, and dehydration to obtain battery-grade ferric phosphate. Yield: 98.4%; Purity: 99.8%.

[0103] The prepared iron phosphate and lithium chloride were analyzed by atomic emission spectrometry (ICP) and chemical analysis. The contents of impurities lithium, sodium, potassium, calcium, barium, copper, manganese, cobalt, nickel and iridium in iron phosphate were all less than 10 ppm; the contents of impurities potassium, calcium, iron, barium, copper, manganese, cobalt, nickel and phosphorus in lithium chloride were all less than 10 ppm, and the total organic carbon (TOC) was less than 25 ppm.

[0104] 2400g of the 2-phenylquinoline iridium dichlorobridge recovered in Example 1 was mixed with 400g of waste lithium iron phosphate powder, 400g of benzimidazole, 800g of methanol, and 3000g of pure water. The mixture was reacted at 30°C under 500nm LED light for 6.0h. The methanol was removed by vacuum concentration, and the solid and liquid phases were separated to obtain a first solid and lithium liquid. The lithium liquid was evaporated and concentrated, the solid and liquid phases were separated, washed with acetonitrile, and dried to obtain anhydrous lithium chloride. Yield: 96.7%; Purity: 98.5%.

[0105] The first solid was dissolved in 1300g of dichloromethane, and the solid and liquid were separated to obtain phospho-iron slag and an organic solution. The organic solution was extracted with 250g of hydrochloric acid and 500g of water, and the organic layer was collected. The collected organic layer was evaporated to dryness to recover 2-phenylquinoline iridium dichlorobridge. Yield: 99.2%; Purity: 99.5%.

[0106] Ferrophosphate slag was mixed with 550g hydrochloric acid and 2400g pure water and reacted. Solid-liquid separation was performed to obtain carbon slag and an acid leaching solution. The pH of the acid leaching solution was adjusted to 1.8 with ammonium carbonate, and the reaction was carried out at 70℃ for 6.0h. Solid-liquid separation was performed, followed by washing, drying, and dehydration to obtain battery-grade ferric phosphate. Yield: 98.3%; Purity: 99.8%.

[0107] like Figure 1 The image shown is the XRD pattern of anhydrous lithium chloride recovered in Example 1. Figure 2 The XRD patterns of the recovered ferric phosphate sample and the standard sample are shown.

[0108] Example 2

[0109] 700g of waste lithium iron phosphate powder, 2900g of 2-phenylpyridinium iridium dichlorobridge, 450g of imidazole, 1500g of acetonitrile, and 4000g of pure water were mixed. The mixture was reacted at 40℃ under 450nm LED light for 12.0h. Acetonitrile was removed by vacuum concentration, and solid-liquid separation was performed to obtain a first solid and a first lithium solution. The lithium solution was evaporated and concentrated, and solid-liquid separation was performed again. The solution was washed with acetonitrile and dried to obtain anhydrous lithium chloride. Yield: 96.5%; Purity: 98.4%.

[0110] The first solid was dissolved in 4000g of chloroform, and the solid and liquid were separated to obtain a second solid, ferrophosphorus slag, and a second organic solution. The organic solution was extracted with 500g of hydrochloric acid and 1000g of water, and the organic layer was collected. The collected organic layer was evaporated to dryness to recover 2-phenylpyridine iridium dichlorobridge. Yield: 99.2%; Purity: 99.4%.

[0111] Ferrophosphate slag was mixed with 800g of sulfuric acid and 2500g of pure water and reacted. Solid-liquid separation was performed to obtain carbon slag and a third liquid acid leaching solution. The pH of the acid leaching solution was adjusted to 1.6 using ammonium bicarbonate, and the reaction was carried out at 85℃ for 5.0h. Solid-liquid separation was then performed, followed by washing, drying, and dehydration to obtain battery-grade ferric phosphate. Yield: 98.1%; Purity: 99.8%.

[0112] The prepared iron phosphate and lithium chloride were analyzed by atomic emission spectrometry (ICP) and chemical analysis. The contents of impurities lithium, sodium, potassium, calcium, barium, copper, manganese, cobalt, nickel and iridium in iron phosphate were all less than 10 ppm; the contents of impurities potassium, calcium, iron, barium, copper, manganese, cobalt, nickel and phosphorus in lithium chloride were all less than 10 ppm, and the total organic carbon (TOC) was less than 30 ppm.

[0113] Example 3

[0114] 1000g of waste lithium iron phosphate powder, 7000g of 2,4-difluoro-2-phenylpyridinium dichlorotrichloro-bridged compound, 790g of alanine, 2000g of ethanol, and 6000g of pure water were mixed. The mixture was reacted at 40℃ under 450nm LED light for 10.0h. The ethanol was removed by vacuum concentration, and the solid and liquid phases were separated to obtain a first solid and a first lithium solution. The lithium solution was evaporated and concentrated, and the solid and liquid phases were separated again. The solution was washed with acetonitrile and dried to obtain anhydrous lithium chloride. Yield: 96.5%; Purity: 98.3%.

[0115] The first solid was dissolved in 6000g of acetonitrile, and the solid and liquid phases were separated to obtain a second solid, ferrophosphorus slag, and an organic solution. The second organic solution was extracted with 1500g of hydrochloric acid and 2500g of water, and the organic layer was collected. The collected organic layer was evaporated to dryness, and 2,4-difluoro-2-phenylpyridinium dichlorobridge was recovered. Yield: 99.2%; Purity: 99.6%.

[0116] Ferrophosphate slag was mixed with 1500g of phosphoric acid and 4000g of pure water and reacted. Solid-liquid separation was performed to obtain carbon slag and a third liquid acid leaching solution. The pH of the acid leaching solution was adjusted to 1.5 with concentrated ammonia, and the reaction was carried out at 90℃ for 8.0h. Solid-liquid separation was performed, followed by washing, drying, and dehydration to obtain battery-grade ferric phosphate. Yield: 98.3%; Purity: 99.8%.

[0117] The prepared iron phosphate and lithium chloride were analyzed by atomic emission spectrometry (ICP) and chemical analysis. The contents of impurities lithium, sodium, potassium, calcium, barium, copper, manganese, cobalt, nickel and iridium in iron phosphate were all less than 10 ppm; the contents of impurities potassium, calcium, iron, barium, copper, manganese, cobalt, nickel and phosphorus in lithium chloride were all less than 10 ppm, and the total organic carbon (TOC) was less than 30 ppm.

[0118] Example 4

[0119] 600g of waste lithium iron phosphate powder, 7200g of 2-phenylisoquinoline iridium dichlorobridge, 900g of phenylalanine, 1000g of methanol, and 4000g of pure water were mixed. The mixture was reacted at 40℃ under 480nm LED light for 6.0h. The methanol was removed by vacuum concentration, and the solid and liquid phases were separated to obtain a first solid and a first lithium solution. The lithium solution was evaporated and concentrated, and the solid and liquid phases were separated again. The solution was washed with acetonitrile and dried to obtain anhydrous lithium chloride. Yield: 96.4%; Purity: 98.3%.

[0120] The first solid was dissolved in 2500g of tetrahydrofuran, and the solid and liquid phases were separated to obtain a second solid, ferrophosphorus slag, and a second organic solution. The organic solution was extracted with 500g of hydrochloric acid and 1500g of water, and the organic layer was collected. The collected organic layer was evaporated to dryness to recover 2-phenylisoquinoline iridium dichlorobridge. Yield: 99.2%; Purity: 99.7%.

[0121] Ferrophosphate slag was mixed with 650g of sulfuric acid and 2000g of pure water and reacted. Solid-liquid separation was performed to obtain carbon slag and a third liquid acid leaching solution. The pH of the acid leaching solution was adjusted to 1.5 with concentrated ammonia, and the reaction was carried out at 85℃ for 8.0h. Solid-liquid separation was performed, followed by washing, drying, and dehydration to obtain battery-grade ferric phosphate. Yield: 98.1%; Purity: 99.8%.

[0122] The iron phosphate and lithium chloride prepared above were analyzed by atomic emission spectrometry (ICP) and chemical analysis. The contents of impurities lithium, sodium, potassium, calcium, barium, copper, manganese, cobalt, nickel and iridium in iron phosphate were all less than 10 ppm; the contents of impurities potassium, calcium, iron, barium, copper, manganese, cobalt, nickel and phosphorus in lithium chloride were all less than 10 ppm, and the total organic carbon (TOC) was less than 25 ppm.

[0123] Example 5

[0124] 400g of waste lithium iron phosphate powder, 2500g of 2-phenylquinoline iridium dichlorobridge, 400g of benzimidazole, 800g of methanol, and 2500g of pure water were mixed. The mixture was reacted at 30℃ under 500nm LED light for 6.0h. The methanol was removed by vacuum concentration, and the solid and liquid phases were separated to obtain a first solid and a first lithium solution. The lithium solution was evaporated and concentrated, and the solid and liquid phases were separated again. The solution was washed with acetonitrile and dried to obtain anhydrous lithium chloride. Yield: 96.8%; Purity: 98.5%.

[0125] The first solid was dissolved in 1200g of dichloromethane, and the solid and liquid were separated to obtain a second solid, ferrophosphorus slag, and an organic solution. The organic solution was extracted with 400g of formic acid, 220g of sodium chloride, and 450g of water, and the organic layer was collected. The collected organic layer was evaporated to dryness to recover the 2-phenylquinoline iridium dichlorobridge. Yield: 99.2%; Purity: 99.5%.

[0126] Ferrophosphate slag was mixed with 520g hydrochloric acid and 2000g pure water and reacted. Solid-liquid separation was performed to obtain carbon slag and a third liquid acid leaching solution. The pH of the acid leaching solution was adjusted to 1.8 using ammonium carbonate, and the reaction was carried out at 70℃ for 6.0h. Solid-liquid separation was then performed, followed by washing, drying, and dehydration to obtain battery-grade ferric phosphate. Yield: 98.4%; Purity: 99.8%.

[0127] The prepared iron phosphate and lithium chloride were analyzed by atomic emission spectrometry (ICP) and chemical analysis. The contents of impurities lithium, sodium, potassium, calcium, barium, copper, manganese, cobalt, nickel and iridium in iron phosphate were all less than 10 ppm; the contents of impurities potassium, calcium, iron, barium, copper, manganese, cobalt, nickel and phosphorus in lithium chloride were all less than 10 ppm, and the total organic carbon (TOC) was less than 25 ppm.

[0128] Comparative Example 1

[0129] Waste lithium iron phosphate powder was processed using the same steps and processes as in Example 1, except that ultraviolet light was used for irradiation; all other operations were the same as in Example 1.

[0130] The yield of iron phosphate prepared above was only 53.1%, and the yield of lithium chloride was 41.3%. Atomic emission spectrometry (ICP) and chemical analysis showed that the contents of impurities sodium, potassium, calcium, barium, copper, manganese, cobalt, and nickel in iron phosphate were all less than 10 ppm, and the lithium content was 130 ppm; the contents of impurities potassium, calcium, iron, barium, copper, manganese, cobalt, nickel, and iridium in lithium chloride were all less than 20 ppm, and the total organic carbon (TOC) was 20 ppm.

[0131] Comparative Example 2

[0132] Waste lithium iron phosphate powder was processed using the same steps and processes as in Example 1, except that 650nm LED light was used for illumination; all other operations were the same as in Example 1.

[0133] The yield of iron phosphate prepared above was only 56.1%, and the yield of lithium chloride was 42.3%. Atomic emission spectrometry (ICP) and chemical analysis showed that the contents of impurities sodium, potassium, calcium, barium, copper, manganese, cobalt, and nickel in iron phosphate were all less than 10 ppm, and the lithium content was 115 ppm; the contents of impurities potassium, calcium, iron, barium, copper, manganese, cobalt, nickel, and iridium in lithium chloride were all less than 20 ppm, and the total organic carbon (TOC) was 20 ppm.

[0134] Comparative Example 3

[0135] Waste lithium iron phosphate powder was treated using the same steps and processes as in Example 1, except that no organic ligands were added; all other operations were the same as in Example 1.

[0136] The yield of iron phosphate prepared above was only 48.1%, and the yield of lithium chloride was 45.4%. Atomic emission spectrometry (ICP) and chemical analysis showed that the contents of impurities, sodium, potassium, calcium, barium, copper, manganese, cobalt, and nickel in iron phosphate were all less than 10 ppm, and the lithium content was 120 ppm; the contents of impurities, potassium, calcium, iron, barium, copper, manganese, cobalt, nickel, and iridium in lithium chloride were all less than 20 ppm, and the total organic carbon (TOC) was 20 ppm.

[0137] Comparative Example 4

[0138] Waste lithium iron phosphate powder was treated using the same steps and processes as in Example 1, except that the light irradiation reaction time was 2.0 h, and all other operations were the same as in Example 1.

[0139] The yield of iron phosphate prepared above was only 58.1%, and the yield of lithium chloride was 35.4%. Atomic emission spectrometry (ICP) and chemical analysis revealed that the contents of impurities sodium, potassium, calcium, barium, copper, manganese, cobalt, and nickel in iron phosphate were all less than 10 ppm, and the lithium content was 110 ppm; the contents of impurities potassium, calcium, iron, barium, copper, manganese, cobalt, nickel, and iridium in lithium chloride were all less than 20 ppm, and the total organic carbon (TOC) was 20 ppm.

[0140] Comparative Example 5

[0141] Waste lithium iron phosphate powder was processed using the same steps and processes as in Example 1, except that the reaction temperature during the light irradiation reaction was 100°C, and all other operations were the same as in Example 1.

[0142] The yield of iron phosphate prepared above was only 68.1%, and the yield of lithium chloride was 61.4%. Atomic emission spectrometry (ICP) and chemical analysis showed that the contents of impurities sodium, potassium, calcium, barium, copper, manganese, cobalt, and nickel in iron phosphate were all less than 10 ppm, and the lithium content was 100 ppm; the contents of impurities potassium, calcium, iron, barium, copper, manganese, cobalt, nickel, and iridium in lithium chloride were all less than 20 ppm, and the total organic carbon (TOC) was 20 ppm.

[0143] Comparative Example 6

[0144] Waste lithium iron phosphate powder was processed using the same steps and processes as in Example 1, with the only difference being the 2-phenylquinoline platinum dichlorobridge; all other operations were the same as in Example 1.

[0145] The yield of iron phosphate prepared above was only 68.1%, and the yield of lithium chloride was 21.3%. Atomic emission spectrometry (ICP) and chemical analysis showed that the contents of impurities sodium, potassium, calcium, barium, copper, manganese, cobalt, and nickel in iron phosphate were all less than 10 ppm, and the lithium content was 920 ppm; the contents of impurities potassium, calcium, iron, barium, copper, manganese, cobalt, nickel, and iridium in lithium chloride were all less than 20 ppm, and the TOC was 1280 ppm.

[0146] Comparative Example 7

[0147] Waste lithium iron phosphate powder was treated using the same steps and processes as in Example 1, with the only difference being the 2-pyridinecarboxylic acid iridium dichlorobridge; all other operations were the same as in Example 1.

[0148] The yield of iron phosphate prepared above was only 60.3%, and the yield of lithium chloride was 19.4%. Atomic emission spectrometry (ICP) and chemical analysis showed that the contents of impurities sodium, potassium, calcium, barium, copper, manganese, cobalt, and nickel in iron phosphate were all less than 10 ppm, and the lithium content was 1000 ppm; the contents of impurities potassium, calcium, iron, barium, copper, manganese, cobalt, nickel, and iridium in lithium chloride were all less than 20 ppm, and the TOC was 980 ppm.

[0149] Results analysis:

[0150] As can be seen from the results of Example 1 and Comparative Example 1, the use of ultraviolet light in the step of Comparative Example 1 resulted in a significant decrease in the yield of iron phosphate and lithium chloride, and a slight decrease in the purity of iron phosphate, thus failing to achieve the purpose of this invention.

[0151] As can be seen from the results of Example 1 and Comparative Example 2, the use of a 650nm LED in the step of Comparative Example 2 resulted in a significant decrease in the yield of iron phosphate and lithium chloride, and a slight decrease in the purity of iron phosphate, thus failing to achieve the objective of this invention.

[0152] As can be seen from the results of Example 1 and Comparative Example 3, in Comparative Example 3, without the addition of organic ligands, the yields of iron phosphate and lithium chloride decreased significantly, and the purity of iron phosphate also decreased slightly, thus failing to achieve the purpose of this invention.

[0153] The results of Example 1 and Comparative Example 4 show that in Comparative Example 4, the reaction time was 2.0 h, the yield of iron phosphate and lithium chloride decreased significantly, and the purity of iron phosphate also decreased slightly, thus failing to achieve the purpose of this invention.

[0154] As can be seen from the results of Example 1 and Comparative Example 5, in the step of Comparative Example 5, the light reaction temperature was 100°C, the yield of iron phosphate and lithium chloride decreased significantly, and the purity of iron phosphate also decreased slightly, thus failing to achieve the purpose of this invention.

[0155] As can be seen from the results of Example 1 and Comparative Example 6, when 2-phenylquinoline platinum dichlorobridge was selected as the recoverable material in Comparative Example 6, the yields of iron phosphate and lithium chloride decreased significantly, and the total organic carbon increased significantly, thus failing to achieve the purpose of this invention.

[0156] As can be seen from the results of Example 1 and Comparative Example 7, when 2-pyridinecarboxylic acid iridium dichlorobridge was selected as the recovered product in Comparative Example 7, the yields of iron phosphate and lithium chloride decreased significantly, and the total organic carbon increased significantly, thus failing to achieve the purpose of this invention.

[0157] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0158] The above-described embodiments are merely illustrative of several implementation methods of the present invention, facilitating a detailed and specific understanding of the technical solutions of the present invention. However, they should not be construed as limiting the scope of protection of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the scope of protection of the present invention. It should be understood that technical solutions obtained by those skilled in the art based on the technical solutions provided by the present invention through logical analysis, reasoning, or limited experimentation are all within the scope of protection of the appended claims. Therefore, the scope of protection of this invention patent should be determined by the content of the appended claims, and the specification can be used to interpret the content of the claims.

Claims

1. Use of an iridium chloro-bridged dimer, characterized in that, The iridium chloride bridge dimer is applied to recover iron phosphate in waste lithium iron phosphate powder; the step of recovering iron phosphate in waste lithium iron phosphate powder comprises: S100: mixing the iridium chloride bridge dimer, a first organic solvent, an organic ligand, water and the waste lithium iron phosphate powder, irradiating under visible light, filtering, preparing a first solid and a first solution, the organic ligand is selected from one or more of imidazole organic ligand, quinoline organic ligand and amino acid organic ligand, the first organic solvent is selected from one or more of dichloromethane, chloroform, methanol, ethanol and acetonitrile, the visible light irradiation conditions comprise: irradiating at a temperature of 5-40℃ for 5-20h, and the wavelength range of visible light is 450-550nm; S110: mixing the first solid and a second organic solvent, filtering, preparing a second solid and a second solution, the second organic solvent is selected from one or more of dichloromethane, chloroform, methanol, ethanol, tetrahydrofuran and acetonitrile; S120: mixing the second solid, an inorganic acid and water, filtering, preparing a third solution, S130: adjusting the pH value of the third solution to 1-2 by a pH adjuster for reaction, filtering, and recovering the filter residue; The structural general formula of the iridium chloride bridge dimer is: wherein R1 and R2 are each independently selected from X1-X4 are each independently selected from H, F, Cl or Br, Y1 is independently selected from N or CR3 at each occurrence, and R3 is independently selected from -H, -D or a straight-chain alkyl group having 1-5 C atoms at each occurrence.

2. Use of iridium chloro-bridged dimers according to claim 1, characterized in that, The structure of the iridium chloride bridge dimer is shown in one of formula (1-1) and (1-4):

3. Use of iridium chloro-bridged dimers according to claim 1, characterized in that, The chemical element composition of the waste lithium iron phosphate powder comprises, in terms of weight percentage, 2-5% of lithium, 25-35% of iron, 15-25% of phosphorus, 0.1-0.5% of aluminum, 0.01-0.1% of copper, 0.0001-0.01% of manganese, 0.0001-0.01% of cobalt, 35-42% of oxygen, 5-12% of carbon, 0.0001-0.01% of nickel and 0.0001-0.01% of fluorine.

4. The use of iridium chloro-bridged dimers according to claim 1, characterized in that, In the step of recovering iron phosphate in waste lithium iron phosphate powder, one or more of the following features is provided: (1) In step S100, the mass ratio of the iridium chloride bridge dimer, the organic ligand and the waste lithium iron phosphate powder is (0.6-1.5) : (1.2-3.0) : 1, and the mass ratio of the first solvent, water and the waste lithium iron phosphate powder is (1-3) : (5-12) : 1; (2) The mass ratio of the second solvent and the waste lithium iron phosphate powder is (2-8) : 1; (3) The inorganic acid is selected from one or more of hydrochloric acid, nitric acid, sulfuric acid and phosphoric acid; (4) In step S120, the mass ratio of the inorganic acid, water and the waste lithium iron phosphate powder is (1-3) : (3-8) : 1; (5) The pH adjuster is selected from one or more of concentrated ammonia, ammonium carbonate and ammonium bicarbonate; (6) In step S130, the reaction time is 4-12 hours, and the reaction temperature is 40-100 DEG C.

5. Use of iridium chloro-bridged dimers according to claim 1, characterized in that, The step of recovering iron phosphate from waste lithium iron phosphate powder has one or more of the following characteristics: (1) The amino acid organic ligand is selected from one or more of glycine, alanine, valine, leucine, isoleucine, methionine, proline, tryptophan, serine, tyrosine, cysteine, phenylalanine, asparagine, glutamine, threonine, aspartic acid, glutamic acid, lysine, arginine, and histidine; (2) The imidazole organic ligand is selected from one or more of imidazole, benzimidazole, and 2-ethylbenzimidazole; (3) The quinoline organic ligand is selected from one or more of tetrahydroquinoline and tetrahydroisoquinoline.

6. Use of iridium chloro-bridged dimers according to claim 1, characterized in that, The step of recovering iron phosphate from waste lithium iron phosphate powder further comprises a step of recovering lithium chloride: The first solution is evaporated, filtered, the filter residue is washed with an organic solvent, and dried.

7. The use of iridium chloro-bridged dimers according to claim 1, characterized in that, The step of recovering iron phosphate from waste lithium iron phosphate powder further comprises a step of recovering the iridium-chlorine bridge dimer: The second solution, a strong acid, and water are mixed to prepare a mixed solution, the organic layer solution in the mixed solution is extracted, and the organic layer solution is evaporated; The strong acid is selected from one or more of hydrochloric acid, sulfuric acid, nitric acid, formic acid, trifluoroacetic acid, and triflic acid.

8. Use of iridium chloro-bridged dimers according to claim 7, characterized in that, The step of recovering the iridium-chlorine bridge dimer has at least one of the following characteristics: (1) The mixed solution further comprises a metal chloride, and the metal chloride is selected from one or more of sodium chloride, potassium chloride, magnesium chloride, calcium chloride, and zinc chloride; (2) The mass ratio of the waste lithium iron phosphate, the strong acid, and water is 1 :(0.5-5):(1-3).

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